Sample records for krypton isotopic anomalies

  1. Trapping Metastable Krypton Atoms for Radio-Isotope Dating

    NASA Astrophysics Data System (ADS)

    Zappala, Jake; Bailey, Kevin; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Thomas

    2014-05-01

    We have developed a MOT of metastable krypton atoms achieving a loading rate of 1012 s-1 for the abundant isotope 84Kr. At the same time, the trap is capable of single atom detection of the rare isotopes 81Kr and 85Kr used for radio-isotope dating. Metastable atom production via gas discharge remains a major limit to trapping efficiency. We are exploring direct optical excitation methods to overcome this limit. This technique uses a krypton lamp to produce resonant 124 nm light and an 819 nm laser to drive the krypton from the ground state to the metastable level. These advancements would lead to a next generation ATTA instrument for 81Kr dating. Improved efficiency would open up new opportunities such as dating deep ice core samples. This work is supported by DOE, Office of Nuclear Physics, under contract DEAC02-06CH11357.

  2. A primary isotopic gas standard for krypton with values for isotopic composition and molar mass traceable to the Système International d’Unités

    Microsoft Academic Search

    Y Aregbe; S Valkiers; J Poths; J Nørgaard; H Kipphardt; P De Bièvre; P. D. P Taylor

    2001-01-01

    Isotope amount ratios of krypton were measured on subsamples from one large batch of high purity krypton separated from the atmosphere. Synthetic mixtures of enriched krypton isotopes were used to “calibrate” the measurements with small uncertainties. The result is a primary isotopic gas standard (PIGS) IRMM-2030 with certified values for isotope ratios, isotopic composition, and molar mass of krypton with

  3. Krypton isotope analysis using near-resonant stimulated Raman spectroscopy

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1994-12-01

    A method for measuring low relative abundances of {sup 85}Kr in one liter or less samples of air has been under development here at Pacific Northwest Laboratory. The goal of the Krypton Isotope Laser Analysis (KILA) method is to measure ratios of 10{sup {minus}10} or less of {sup 85}Kr to more abundant stable krypton. Mass spectrometry and beta counting are the main competing technologies used in rare-gas trace analysis and are limited in application by such factors as sample size, counting times, and selectivity. The use of high-resolution lasers to probe hyperfine levels to determine isotopic abundance has received much attention recently. In this study, we report our progress on identifying and implementing techniques for trace {sup 85}Kr analysis on small gas samples in a static cell as well as limitations on sensitivity and selectivity for the technique. High-resolution pulsed and cw lasers are employed in a laser-induced fluorescence technique that preserves the original sample. This technique, is based on resonant isotopic depletion spectroscopy (RIDS) in which one isotope is optically depleted while preserving the population of a less abundant isotope. The KILA method consists of three steps. In the first step, the 1s{sub 5} metastable level of krypton is populated via radiative cascade following two-photon excitation of the 2p{sub 6} energy level. Next, using RBDS, the stable krypton isotopes are optically depleted to the ground state through the 1s{sub 4} level with the bulk of the {sup 85}Kr population being preserved. Finally, the remaining metastable population is probed to determine {sup 85}Kr concentration. The experimental requirements for each of these steps are outlined below.

  4. s-process studies - Xenon and krypton isotopic abundances

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.; Ward, R. A.

    1978-01-01

    We propose an analysis of the s-process contributions to the isotopes of xenon and krypton. The object is to aid studies of the possibility that meteorites may contain gas that was carried in presolar grains that were grown in stellar ejecta and that were not degassed prior to incorporation into parent bodies. That model suggests routine interstellar fractionation of s-isotopes from r-isotopes owing to differential incorporation into dust. We show that a deficiency of s-process nuclei cannot yield details of Xe-X, but the gross similarities are strong enough to lead one to think that such a deficiency may play a role in a more complicated explanation. We predict the existence of an s-rich complement somewhere if fractional separation of this type has played a role in Xe-X. We show that the analogous decomposition of krypton is more uncertain, and we call for measurements of neutron-capture cross sections to alleviate these uncertainties.

  5. Shape coexistence and evolution in neutron-deficient krypton isotopes

    E-print Network

    Z. J. Bai; X. M. Fu; C. F. Jiao; F. R. Xu

    2015-03-31

    Total Routhian Surface (TRS) calculations have been performed to investigate shape coexistence and evolution in neutron-deficient krypton isotopes ${}^{72,74,76}$Kr. The ground-state shape is found to change from oblate in ${}^{72}$Kr to prolate in ${}^{74,76}$Kr, in agreement with experimental data. Quadrupole deformations of the ground states and coexisting $0^{+}_{2}$ states as well as excitation energies of the latter are also well reproduced. While the general agreement between calculated moments of inertia and those deduced from observed spectra confirms the prolate nature of the low-lying yrast states of all three isotopes (except the ground state of ${}^{72}$Kr), the deviation at low spins suggests significant shape mixing. The role of triaxiality in describing shape coexistence and evolution in these nuclei is finally discussed.

  6. Isotope shift and hyperfine structure studies of the krypton ion and the thallium atom 

    E-print Network

    Li, Yingfeng

    1991-01-01

    ISOTOPE SHIFT AND HYPERFINE STRUCTURE STUDIES OF THE KRYPTON ION AND THE THALLIUM ATOM A Thesis by YINGFENG LI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree...) Lewis A. Ford (Member) Christian P. Burger (Member) Richard L. Arnowitt (Head of Department) August 1991 777 ABSTRACT Isotope Shift and Hyperfine Structure Studies of the Krypton Ion and the Thallium Atom. tAugust 1991) Yingfeng Li, B. S...

  7. Isotopic anomalies in extraterrestrial grains.

    PubMed

    Ireland, T R

    1996-03-01

    Isotopic compositions are referred to as anomalous if the isotopic ratios measured cannot be related to the terrestrial (solar) composition of a given element. While small effects close to the resolution of mass spectrometric techniques can have ambiguous origins, the discovery of large isotopic anomalies in inclusions and grains from primitive meteorites suggests that material from distinct sites of stellar nucleosynthesis has been preserved. Refractory inclusions, which are predominantly composed of the refractory oxides of Al, Ca, Ti, and Mg, in chondritic meteorites commonly have excesses in the heaviest isotopes of Ca, Ti, and Cr which are inferred to have been produced in a supernova. Refractory inclusions also contain excess 26Mg from short lived 26Al decay. However, despite the isotopic anomalies indicating the preservation of distinct nucleosynthetic sites, refractory inclusions have been processed in the solar system and are not interstellar grains. Carbon (graphite and diamond) and silicon carbide grains from the same meteorites also have large isotopic anomalies but these phases are not stable in the oxidized solar nebula which suggests that they are presolar and formed in the circumstellar atmospheres of carbon-rich stars. Diamond has a characteristic signature enriched in the lightest and heaviest isotopes of Xe, and graphite shows a wide range in C isotopic compositions. SiC commonly has C and N isotopic signatures which are characteristic of H-burning in the C-N-O cycle in low-mass stars. Heavier elements such as Si, Ti, Xe, Ba, and Nd, carry an isotopic signature of the s-process. A minor population of SiC (known as Grains X, ca. 1%) are distinct in having decay products of short lived isotopes 26Al (now 26Mg), 44Ti (now 44Ca), and 49V (now 49Ti), as well as 28Si excesses which are characteristic of supernova nucleosynthesis. The preservation of these isotopic anomalies allows the examination of detailed nucleosynthetic pathways in stars. PMID:11541324

  8. Xenon and krypton isotopes in extraterrestrial regolith soils and in the solar wind

    Microsoft Academic Search

    R. O. Pepin; R. H. Becker; P. E. Rider

    1995-01-01

    Isotopic distributions of pure solar-wind xenon and krypton are derived from an extensive data base of xenon and krypton compositions evolved from lunar and meteoritic regolith samples by acid-etching or combustion-pyrolysis experiments in several different laboratories. Regolith Xe and Kr are nonuniform mixtures of primary solar-wind components with others arising in situ from cosmic-ray spallation, neutron-capture in iodine and bromine,

  9. Development of an improved detector for krypton-81 and other noble-gas isotopes

    Microsoft Academic Search

    Hurst

    1988-01-01

    Phase 1 studies focused on the annealing (transient melting) of silicon and germanium targets with a krypton-fluoride (KrF) excimer laser. A suitable target of a semiconducting material--as a means of storing noble gas atoms--is a key component of a device called the RISTRON for counting isotopes of a noble gas. A means for isotopic selective counting of atoms such as

  10. 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.

  11. Calcium isotopic anomalies in the Allende meteorite

    Microsoft Academic Search

    T. Lee; D. A. Papanastassiou; G. J. Wasserburg

    1978-01-01

    We report isotopic anomalies in Ca which were found in two Ca-Al-rich inclusions of the Allende meteorite. These inclusions previously had been shown to contain special anomalies for Mg and O which were attributed to fractionation and unknown nuclear effects. The Ca data, when corrected for mass fractionation by using ⁴°Ca\\/⁴⁴Ca as a standard, show nonlinear isotopic effects in ⁴⁸Ca

  12. Chromium isotopic anomalies in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Papanastassiou, D. A.

    1986-01-01

    Abundances of the chromium isotopes in terrestrial and bulk meteorite samples are identical to 0.01 percent. However, Ca-Al-rich inclusions from the Allende meteorite show endemic isotopic anomalies in chromium which require at least three nucleosynthetic components. Large anomalies at Cr-54 in a special class of inclusions are correlated with large anomalies at Ca-48 and Ti-50 and provide strong support for a component reflecting neutron-rich nucleosynthesis at nuclear statistical equilibrium. This correlation suggests that materials from very near the core of an exploding massive star may be injected into the interstellar medium.

  13. Isotopic anomalies from neutron reactions during explosive carbon burning

    NASA Technical Reports Server (NTRS)

    Lee, T.; Schramm, D. N.; Wefel, J. P.; Blake, J. B.

    1979-01-01

    The heavy isotopic anomalies observed recently in the fractionation and unknown nuclear inclusions from the Allende meteorite are explained by neutron reactions during the explosive carbon burning (ECB). This model produces heavy anomalies in the same zone where Al-26 and O-16 are produced, thus reducing the number of source zones required for the isotopic anomalies. Unlike the classical r-process, the ECB n-process avoids the problem with the Sr anomaly and may resolve the problem of conflicting time scales between Al-26 and the r-process isotopes I-129 and Pu-244. Experimental studies of Zr and Ce isotopic composition are proposed to test this model.

  14. Nucleosynthetic strontium isotope anomalies in carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tetsuya; Fukami, Yusuke; Okui, Wataru; Ito, Nobuaki; Yamazaki, Hiroshi

    2015-04-01

    Precise Sr isotopic compositions in samples from sequential acid leaching experiments have been determined for three carbonaceous chondrites, Allende, Murchison, and Tagish Lake, together with those in the bulk aliquots of these meteorites. The chondritic acid leachates and residues were characterized by Sr isotope anomalies with variable ?84Sr values (106 relative deviation from a standard material) ranging from +120 to - 4700 ppm, documenting multiple nucleosynthetic sources within a single meteorite. In addition, the ?84Sr patterns across leaching samples for individual chondrites differed from one another. The highest ?84Sr values were observed for leaching Step 3 (HCl+H2O, 75 °C) for Allende and Murchison likely because of the incorporation of calcium and aluminum-rich inclusions (CAIs). In contrast, extremely low ?84Sr values were observed in the later fractions (Steps 6 and 7) for Murchison and Tagish Lake, suggesting the existence of s-process-enriched presolar SiC grains derived from AGB stars. A ?84Sr-?54Cr diagram was prepared with the CAIs and bulk aliquots of carbonaceous chondrites and other meteorites (noncarbonaceous) that were plotted separately; however, they still formed a global positive correlation. CAIs presented the highest ?84Sr and ?54Cr values, whereas carbonaceous chondrites and noncarbonaceous meteorites had intermediate and the lowest ?84Sr and ?54Cr values, respectively. The positive trend was interpreted as resulting from global thermal processing in which sublimation of high ?84Sr and ?54Cr carriers generated the excess ?84Sr and ?54Cr signatures in CAIs, while noncarbonaceous planetesimals accreted from materials that underwent significant thermal processing and thus had relatively low ?84Sr and ?54Cr values. Apart from the global trend, the carbonaceous chondrites and noncarbonaceous meteorites both exhibited intrinsic variations that highlight an isotopic dichotomy similar to that observed in other isotope combinations (e.g., ?54Cr-?50Ti, ?54Cr-?17O). A plausible scenario for creation of the intrinsic variations involves local thermal processing (e.g., flash heating for chondrule formation) caused by additional selective destruction of presolar grains differently than that caused by global thermal processing. The existence of such a global positive trend and local variations for two meteorite groups suggests a complicated dynamic history for the dust grains with respect to thermal processing, material transportation, and mixing in the protoplanetary disk prior to planetesimal formation.

  15. The calcium isotopic anomaly in magnetic CP stars

    Microsoft Academic Search

    C. R. Cowley; S. Hubrig

    2005-01-01

    Chemically peculiar stars in the magnetic sequence can show the same isotopic anomaly in calcium previously discovered for mercury-manganese stars in the non-magnetic sequence. In extreme cases, the dominant isotope is the exotic 48Ca. Measurements of Ca II lines arising from 3d-4p transitions reveal the anomaly by showing shifts up to 0.2 Å for the extreme cases - too large

  16. Isotopic Anomalies in CP Stars: Helium, Mercury, Platinum, and Calcium

    E-print Network

    Cowley, C R; Castelli, F

    2007-01-01

    We review the classical observational results for isotopic abundance variations for several elements in CP stars. We concentrate on the "newest" anomaly, in calcium. The cosmically very rare isotope, Ca-48 can rival and even dominate the more common, alpha nuclide, Ca-40. Relevant examples are found in the hot, non-magnetic HgMn stars, and the field horizontal-branch star, Feige 86. The calcium anomaly is also present in cool, magnetic stars, including the notorious HD 101065, Przybylski's star.

  17. Isotope shift and hyperfine structure studies of the krypton ion and the thallium atom

    E-print Network

    Li, Yingfeng

    1991-01-01

    . The theoretical background of each experimental method and a description of each experiment is given. In the first experiment a beam of krypton ions wss excited collinearly by a cw dye-laser beam. Doppler tuning into resonance is carried out by scanning... structure measurements. More recently, with the availability of high-power narrow-band lasers since the 1970s, it has been possible to attain a very high spectral resolution, and Doppler-free spectra in the optical domain were invented. The collinear...

  18. Barium and neodymium isotopic anomalies in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Mcculloch, M. T.; Wasserburg, G. J.

    1978-01-01

    The discovery of Ba and Nd isotopic anomalies in two inclusions from the Allende meteorite is reported. The inclusions are Ca-Al-rich objects typical of the type considered as high-temperature condensation products in the solar nebula and contain distinctive Mg and O isotopic anomalies of the FUN (mass Fractionation, Unknown Nuclear processes) type. Mass-spectrometry results are discussed which show that inclusion C1 has anomalies in Ba at masses 134 and 136, while inclusion EK1-4-1 exhibits large marked negative anomalies at 130, 132, 134, and 136, as well as a positive anomaly at 137. It is also found that inclusion EK1-4-1 shows marked negative anomalies in Nd at masses 142, 146, 148, and 150, in addition to a positive anomaly at 145. These isotopic shifts are attributed to addition of r-process nuclei rather than mass fractionation. It is suggested that an onion-shell supernova explosion followed by injection into the solar nebula is the most likely generic model that may explain the observations.

  19. Production of krypton and xenon isotopes in thick stony and iron targets isotropically irradiated with 1600 MeV protons

    NASA Astrophysics Data System (ADS)

    Gilabert, E.; Lavielle, B.; Michel, R.; Leya, I.; Neumann, S.; Herpers, U.

    2002-07-01

    Two spherical targets made of gabbro with a radius of 25 cm and of steel with a radius of 10 cm were irradiated isotropically with 1.6 GeV protons at the SATURNE synchrotron at Laboratoire National Saturne (LNS)/CEN Saclay, in order to simulate the production of nuclides in meteorites induced by galactic cosmic-ray protons in space. These experiments supply depth dependent production rate data for a wide range of radioactive and stable isotopes in up to 28 target elements. In this paper, we report results for 78Kr, 80-86Kr isotopes in Rb, Sr, Y and Zr and for 124Xe, 126Xe, 128-132Xe, 134Xe, 136Xe isotopes in Ba and La. Krypton and xenon concentrations have been measured at different depths in the spheres by using conventional mass spectrometry. Based on Monte-Carlo techniques, theoretical production rates are calculated by folding depth-dependent spectra of primary and secondary protons and secondary neutrons with the excitation functions of the relevant nuclear reactions. The comparison of the model calculation results with experimental data in the thick target experiments performed at LNS and previously at CERN have allowed adjustments of the poorly known excitation functions of neutron-induced reactions. Thus, for the two experiments at SATURNE, excellent agreement is obtained between experimental and calculated production rates for most Kr and Xe isotopes in all investigated target elements. Only Xe production in Ba in the gabbro is underestimated by the calculations by about 25%. This work validates the approach of the thin-target model calculations of cosmogenic nuclide production rates in the attempt of modeling the interaction of galactic cosmic-ray protons with stony and iron meteorites in space as well as with lunar samples.

  20. Endemic Mo Isotopic Anomalies in Iron and Carbonaceous Meteorites

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Papanastassiou, D. A.; Wasserburg, G. J.; Ngo, H. H.

    2004-01-01

    Mo in refractory interstellar grains shows large isotope anomalies. Recent Mo studies showed isotope effects in Allende and Murchison, and in iron meteorites, mesosiderites, and pallasites. Excesses of p- and r-process isotopes (or depletion of sprocess isotopes) of up to 3.5 epsilon units (epsilon u=parts in 10(exp 4)) were reported. We have reported on endemic isotope anomalies in Ru. Other workers have resolved no isotope anomalies for Mo or Ru and have claimed that the work by others is incorrect. Because Ru isotopes can interfere at Mo-96, Mo-98, Mo-100, we improved the chemical separations and eliminated interferences. For Mo work, we used the same solutions from which we separated and analyzed Ru. Three of the iron meteorites (Coahuila, Cape York, and Cape of Good Hope) were chosen for their large Mo isotopic effects. Mo was loaded on outgassed Re filaments, and then reduced; we used Ba(OH)2-NaOH as emitter, and measured Mo in static mode, as MoO3(-). We used Mo-98/Mo-96 for the mass fractionation correction (exponential law). No interferences from Ru or Zr isotopes were detected using the electron multiplier and no corrections were needed. For results on Mo standards we show 2 sigma(not 2 sigma mean) external precision better than: 0.7 epsilon u for Mo-94/Mo-96 and Mo-95/Mo-96; 1.0 epsilon u for Mo-92/Mo-96 and Mo-97/Mo-96; 1.4 epsilon u for Mo-100/Mo-96. Reproducibility for Mo standards is shown as contours (blue lines).

  1. The longevity of the South Pacific isotopic and thermal anomaly

    USGS Publications Warehouse

    Staudigel, H.; Park, K.-H.; Pringle, M.; Rubenstone, J.L.; Smith, W.H.F.; Zindler, A.

    1991-01-01

    The South Pacific is anomalous in terms of the Sr, Nd, and Pb isotope ratios of its hot spot basalts, a thermally enhanced lithosphere, and possibly a hotter mantle. We have studied the Sr, Nd, and Pb isotope characteristics of 12 Cretaceous seamounts in the Magellans, Marshall and Wake seamount groups (western Pacific Ocean) that originated in this South Pacific Isotopic and Thermal Anomaly (SOPITA). The range and values of isotope ratios of the Cretaceous seamount data are similar to those of the island chains of Samoa, Tahiti, Marquesas and Cook/Austral in the SOPITA. These define two major mantle components suggesting that isotopically extreme lavas have been produced at SOPITA for at least 120 Ma. Shallow bathymetry, and weakened lithosphere beneath some of the seamounts studied suggests that at least some of the thermal effects prevailed during the Cretaceous as well. These data, in the context of published data, suggest: 1. (1)|SOPITA is a long-lived feature, and enhanced heat transfer into the lithosphere and isotopically anomalous mantle appear to be an intrinsic characteristic of the anomaly. 2. (2)|The less pronounced depth anomaly during northwesterly plate motion suggests that some of the expressions of SOPITA may be controlled by the direction of plate motion. Motion parallel to the alignment of SOPITA hot spots focusses the heat (and chemical input into the lithosphere) on a smaller cross section than oblique motion. 3. (3)|The lithosphere in the eastern and central SOPITA appears to have lost its original depleted mantle characteristics, probably due to enhanced plume/lithosphere interaction, and it is dominated by isotopic compositions derived from plume materials. 4. (4)|We speculate (following D.L. Anderson) that the origin of the SOPITA, and possibly the DUPAL anomaly is largely due to focussed subduction through long periods of the geological history of the earth, creating a heterogeneous distribution of recycled components in the lower mantle. ?? 1991.

  2. The calcium isotopic anomaly in magnetic CP stars

    E-print Network

    Cowley, C R; Cowley, Ch. R.

    2005-01-01

    Chemically peculiar stars in the magnetic sequence can show the same isotopic anomaly in calcium previously discovered for mercury-manganese stars in the non-magnetic sequence. In extreme cases, the dominant isotope is the exotic 48^Ca. Measurements of Ca II lines arising from 3d-4p transitions reveal the anomaly by showing shifts up to 0.2 AA for the extreme cases - too large to be measurement errors. We report measurements of miscellaneous objects, including two metal-poor stars, two apparently normal F-stars, an Am-star, and the N-star U Ant. Demonstrable anomalies are apparent only for the Ap stars. The largest shifts are found in rapidly oscillating Ap stars and in one weakly magnetic Ap star, HD 133792. We note the possible relevance of these shifts for the GAIA mission.

  3. The calcium isotopic anomaly in magnetic CP stars

    E-print Network

    Ch. R. Cowley; S. Hubrig

    2005-01-26

    Chemically peculiar stars in the magnetic sequence can show the same isotopic anomaly in calcium previously discovered for mercury-manganese stars in the non-magnetic sequence. In extreme cases, the dominant isotope is the exotic 48^Ca. Measurements of Ca II lines arising from 3d-4p transitions reveal the anomaly by showing shifts up to 0.2 AA for the extreme cases - too large to be measurement errors. We report measurements of miscellaneous objects, including two metal-poor stars, two apparently normal F-stars, an Am-star, and the N-star U Ant. Demonstrable anomalies are apparent only for the Ap stars. The largest shifts are found in rapidly oscillating Ap stars and in one weakly magnetic Ap star, HD 133792. We note the possible relevance of these shifts for the GAIA mission.

  4. Isotopic anomalies from neutron reactions during explosive carbon burning

    NASA Technical Reports Server (NTRS)

    Lee, T.; Schramm, D. N.; Wefel, J. P.; Blake, J. B.

    1978-01-01

    The possibility that the newly discovered correlated isotopic anomalies for heavy elements in the Allende meteorite were synthesized in the secondary neutron capture episode during the explosive carbon burning, the possible source of the O-16 and Al-26 anomalies, is examined. Explosive carbon burning calculations under typical conditions were first performed to generate time profiles of temperature, density, and free particle concentrations. These quantities were inputted into a general neutron capture code which calculates the resulting isotopic pattern from exposing the preexisting heavy seed nuclei to these free particles during the explosive carbon burning conditions. The interpretation avoids the problem of the Sr isotopic data and may resolve the conflict between the time scales inferred from 1-129, Pu-244, and Al-26.

  5. NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES

    SciTech Connect

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim [Bristol Isotope Group, School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ (United Kingdom); Russell, Sara, E-mail: r.steele@uclmail.net [Meteoritics and Cosmic mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

    2012-10-10

    We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61}, or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the {sup 58}Ni/{sup 61}Ni internally normalized {sup 60}Ni/{sup 61}Ni, {sup 62}Ni/{sup 61}Ni, and {sup 64}Ni/{sup 61}Ni ratios. The chondrites show a range of 0.15, 0.29, and 0.84 in {epsilon}{sup 60}Ni{sub 58/61}, {epsilon}{sup 62}Ni{sub 58/61}, and {epsilon}{sup 64}Ni{sub 58/61} relative to a typical sample precision of 0.03, 0.05, and 0.08 (2 s.e.), respectively. The carbonaceous chondrites show the largest positive anomalies, enstatite chondrites have approximately terrestrial ratios, though only EH match Earth's composition within uncertainty, and ordinary chondrites show negative anomalies. The meteorite data show a strong positive correlation between {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}, an extrapolation of which is within the error of the average of previous measurements of calcium-, aluminium-rich inclusions. Moreover, the slope of this bulk meteorite array is 3.003 {+-} 0.166 which is within the error of that expected for an anomaly solely on {sup 58}Ni. We also determined to high precision ({approx}10 ppm per AMU) the mass-dependent fractionation of two meteorite samples which span the range of {epsilon}{sup 62}Ni{sub 58/61} and {epsilon}{sup 64}Ni{sub 58/61}. These analyses show that 'absolute' ratios of {sup 58}Ni/{sup 61}Ni vary between these two samples whereas those of {sup 62}Ni/{sup 61}Ni and {sup 64}Ni/{sup 61}Ni do not. Thus, Ni isotopic differences seem most likely explained by variability in the neutron-poor {sup 58}Ni, and not correlated anomalies in the neutron-rich isotopes, {sup 62}Ni and {sup 64}Ni. This contrasts with previous inferences from mass-independent measurements of Ni and other transition elements which invoked variable contributions of a neutron-rich component. We have examined different nucleosynthetic environments to determine the possible source of the anomalous material responsible for the isotopic variations observed in Ni and other transition elements within bulk samples. We find that the Ni isotopic variability of the solar system cannot be explained by mixing with a component of bulk stellar ejecta from either SN II, Wolf-Rayet or, an asymptotic giant branch source and is unlikely to result from bulk mixing of material from an SN Ia. However, variable admixture of material from the Si/S zone of an SN II can create all the characteristics of Ni isotope variations in solar system materials. Moreover, these characteristics can also be provided by an SN II with a range of masses from 15 to 40 M{sub Sun }, showing that input from SN II is a robust source for Ni isotope variations in the solar system. Correlations of Ni isotope anomalies with O, Cr, and Ti isotope ratios and Pb/Yb in bulk meteorites suggest that the heterogeneous distribution of isotopic anomalies in the early solar system likely resulted from nebular sorting of chemically or physically different materials bearing different amounts of isotopes synthesized proximally to the collapse of the protosolar nebula.

  6. Oxygen isotopic anomalies in Allende inclusion HAL

    NASA Astrophysics Data System (ADS)

    Lee, T.; Mayeda, T. K.; Clayton, R. N.

    1980-07-01

    An oxygen isotopic study which demonstrates the Allende inclusion HAL is a FUN object is discussed; the hibonite core, black inner rim and fine-grained outer rim have beem sampled. The oxygen in HAL is found to be heterogeneous, the rim samples having oxygen compositions similar to that of melilites and alteration products in other Allende inclusions including the FUN inclusion EK1-4-1, while the oxygen in the hibonite core shows the most extreme deviation from the AD line so far observed. The oxygen in HAL hibonite, in ED1-4-1 spinel and in spinels of usual Allende inclusions form an approximate linear array with a slope close to 1/2. With regard to the fractionation process, it is noted that the fractionation per amu for various elements does not correlate inversely with mass and that fractionation is elementally selective, probably according to volatility.

  7. Structure of Krypton isotopes calculated with symmetry conserving configuration mixing methods

    E-print Network

    Tomás R. Rodríguez

    2014-08-25

    Shape transitions and shape coexistence in the $^{70-98}$Kr region are studied in a unified view with state-of-the-art beyond self-consistent mean field methods based on the Gogny D1S interaction. Beyond mean field effects are taken into account through the exact angular momentum and particle number restoration and the possibility of axial and non-axial shape mixing. The results of the low-lying properties of these isotopes are in good agreement with the experimental data when the triaxial degree of freedom is included. Shape transitions from axial-oblate ($^{70-72}$Kr) to triaxial-prolate ($^{74-78}$Kr) and from spherical-triaxial ($^{86-92}$Kr) to axial-oblate ($^{94-98}$Kr) ground states are obtained. Additionally, low-lying $0^{+}$ excited states and quasi-gamma bands are found showing the richness of the collective structure in this region.

  8. Isotopic anomaly and stratification of Ca in magnetic Ap stars

    E-print Network

    T. Ryabchikova; O. Kochukhov; S. Bagnulo

    2008-01-15

    We have carried out an accurate investigation of the Ca isotopic composition and stratification in the atmospheres of 23 magnetic chemically peculiar (Ap) stars of different temperature and magnetic field strength. With the UVES spectrograph at the 8m ESO VLT, we have obtained high-resolution spectra of Ap stars in the wavelength range 3000-10000 A. Using a detailed spectrum synthesis calculations, we have reproduced a variety of Ca lines in the optical and ultraviolet spectral regions, inferring the overall vertical distribution of Ca abundance, then we have deduced the relative isotopic composition and its dependence on height using the profile of the the IR-triplet Ca II line at lambda 8498 A. In 22 out of 23 studied stars, we found that Ca is strongly stratified, being usually overabundant by 1.0-1.5 dex below log tau_5000 ~ -1, and strongly depleted above log tau_5000 = -1.5. The IR-triplet Ca II line at lambda 8498 A reveals a significant contribution of the heavy isotopes 46Ca and 48Ca, which represent less than 1% of the terrestrial Ca isotopic mixture. We confirm our previous finding that the presence of heavy Ca isotopes is generally anticorrelated with the magnetic field strength. Moreover, we discover that in Ap stars with relatively small surface magnetic fields (atmospheric layers. This vertical isotopic separation, observed for the first time for any metal in a stellar atmosphere, disappears in stars with magnetic field strength above 6-7 kG. We suggest that the overall Ca stratification and depth-dependent isotopic anomaly observed in Ap stars may be attributed to a combined action of the radiatively-driven diffusion and light-induced drift.

  9. Nucleosynthetic Nd isotope anomalies in primitive enstatite chondrites

    NASA Astrophysics Data System (ADS)

    Boyet, M.; Gannoun, A.

    2013-11-01

    We carried out stepwise dissolutions of four primitive enstatite chondrites (EC) belonging to the EH subgroup. Large Nd isotope anomalies are found in the most refractory phases, dissolved using strong acids. Residues are characterized by excesses in 142Nd and deficits in 145Nd, 148Nd and 150Nd isotopes. The Nd anomalies measured in the ALHA77295 residue are even greater than those measured in the Murchison carbonaceous chondrite (CC) using a similar analytical technique (Qin et al., 2011). Once corrected for a common Sm/Nd evolution, the 142Nd excess in the ALHA77295 residue is equal to 700 ppm relative to the terrestrial standard value. The Nd isotope patterns measured in EC and CC residues can be adjusted to coincide by adding a small amount of an s-process-rich carrier phase such as SiC and 0.075% is required to fit the ALHA7795 residue. Small isotope differences still persist between these residues even if they can be considered similar within error. In enstatite chondrites, residues have a deficit in 150Nd similar to or smaller than that measured in 148Nd, whereas in SiC extracted from carbonaceous chondrites or in whole rock, the deficit in 150Nd is always greater than that in 148Nd. Moreover in a binary 142Nd-148Nd diagram, the best-fit lines obtained for leachates and residues from carbonaceous chondrites and enstatite chondrites have slightly different slopes. For the same 148Nd/144Nd ratio, the anomalous component in an enstatite chondrite has a higher 142Nd/144Nd ratio compared to carbonaceous chondrites, a feature already observed at the whole rock scale. Our results suggest that different chondrite groups sample different reservoirs of presolar grains formed in different environments. Assuming that the carrier of this anomalous component measured in residues of enstatite chondrites are SiC, our results may suggest that different meteorite parent bodies sample reservoirs of presolar SiC formed in different stellar environments. This could explain why ALHA77295, the sample which is the most enriched in presolar grains, has a bulk 142Nd isotope composition similar to the terrestrial value. Further investigation of enstatite chondrites is needed to test whether the isotope composition of the most refractory phases is similar to that measured in carbonaceous chondrites and in particular the 144Sm that is a p-process isotope only. Finally this study highlights the difficulty of interpreting the 142Nd excess in terrestrial samples relative to chondrites since incomplete mixing of nucleosynthetic material in the solar nebula creates significant 142Nd variation, as shown by ALHA77295.

  10. MG isotopic anomalies in the Allende meteorite and correlation with O and SR effects

    Microsoft Academic Search

    Typhoon Lee; D. A. Papanastassiou

    1974-01-01

    Measurements are given of the Mg isotopic composition in samples of the Allende meteorite. It is shown that some inclusions rich in refractory elements contain Mg of isotopic abundance distinct from normal Mg. Measured Mg isotopic ratios were corrected for mass fractionation by normalizing to the terrestrial (normal) Mg-25\\/Mg-24. Relative to normal Mg, Allende samples show distinct isotopic anomalies which

  11. Grain carriers of isotopic anomalies. [interstellar isotope injection into early solar nebula

    NASA Technical Reports Server (NTRS)

    Margolis, S. H.; Falk, S. W., Jr.

    1979-01-01

    The dynamics of grain motion through gas are examined in terms of the injection of isotopically anomalous (compared to solar abundances) material into the early solar nebula. Calculations indicate that the injected grains cannot penetrate to the center of any of a range of reasonable configurations, suggesting the formation of an edge region enriched in injected material. Furthermore, the dynamical behavior of grains in turbulent flows indicates that pockets of grains can have some resistance to turbulent diffusion. The constraints developed here are used to delineate a set of consistent, injected-grain models for the origin of the isotopic anomalies in meteorite inclusions.

  12. On strontium isotopic anomalies and odd-A p-process abundances. [in solar system

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1978-01-01

    Several aspects of the nucleosynthesis of Sr isotopes are considered in an attempt to shed light on the problem of the Sr isotopic anomalies discovered in an inclusion of the Allende meteorite. Decomposition of the Sr isotopes into average r-, s-, and p-process nucleosynthetic classes is performed. It is suggested that the Allende inclusion most likely has an excess of s-process Sr and that the initial Sr-87/Sr-86 isotopic ratio is probably slightly more primitive than basaltic achondrites. The results also show that Sn-115 is mostly due to the r-process and that odd-A yields are very small. It is concluded that if the Sr anomaly in the inclusion is an average s enhancement, it argues somewhat in favor of a model of gas/dust fractionation of s and r isotopes during accumulation of the inclusion parent in the protosolar cloud.

  13. Noble gas anomalies and synthesis of the chemical elements

    NASA Astrophysics Data System (ADS)

    Sabu, D. D.; Manuel, O. K.

    1980-06-01

    The elemental and isotopic abundances of noble gases trapped in meteorites are discussed in relation to the origin of the chemical elements and the condensation of the solar system. The abundance patterns of the two types of planetary noble gases and of solar noble gases are examined, and it is suggested that type-X planetary noble gases, which contain isotopically anomalous argon, krypton and xenon and normal helium and neon, were derived from the outer regions of a supernova, while the Y-type planetary noble gases, which consist of isotopically normal argon, krypton and xenon, were derived from its inner regions. It is argued, however, that variations in the isotopic composition of neon can be explained by mass fraction or mass fractionation plus spallation without recourse to separate nucleogenetic anomalies. It is also concluded that the differences in the abundance patterns of planetary noble gases are primarily the result of stellar fusion reactions and adsorption, rather than gas solubility.

  14. Nitrogen Isotopic Anomalies in a Hydrous Interplanetary Dust Particle

    NASA Technical Reports Server (NTRS)

    Smith, J. B.; Dai, Z. R.; Weber, P. K.; Graham, G. A.; Hutcheon, I. D.; Bajt, S.; Ishii, H.; Bradley, J. P.

    2005-01-01

    Interplanetary dust particles (IDPs) collected in the stratosphere are the fine-grained end member (5 - 50 microns in size) of the meteoritic material available for investigation in the laboratory. IDPs are derived from either cometary or asteroidal sources. Some IDPs contain cosmically primitive materials with isotopic signatures reflecting presolar origins. Recent detailed studies using the NanoSIMS have shown there is a wide variation of isotopic signatures within individual IDPs; grains with a presolar signature have been observed surrounded by material with a solar isotopic composition. The majority of IDPs studied have been anhydrous. We report here results from integrated NanoSIMS/FIB/TEM/Synchrotron IR studies of a hydrous IDP, focused on understanding the correlations between the isotopic, mineralogical and chemical compositions of IDPs.

  15. Isotopic Anomalies in Organic Nanoglobules from Comet 81P/Wild 2: Comparison to Murchison Nanoglobules and Isotopic Anomalies Induced in Terrestrial Organics by Electron Irradiation

    SciTech Connect

    De Gregorio, B.; Stroud, R; Nittler, L; Alexander, C; Kilcoyne, A; Zega, T

    2010-01-01

    Nanoglobules are a form of organic matter found in interplanetary dust particles and primitive meteorites and are commonly associated with {sup 15}N and D isotopic anomalies that are suggestive of interstellar processes. We report the discovery of two isotopically-anomalous organic globules from the Stardust collection of particles from Comet 81P/Wild 2 and compare them with nanoglobules from the Murchison CM2 meteorite. One globule from Stardust Cometary Track 80 contains highly aromatic organic matter and a large {sup 15}N anomaly ({delta}{sup 15}N = 1120{per_thousand}). Associated, non-globular, organic matter from this track is less enriched in {sup 15}N and contains a mixture of aromatic and oxidized carbon similar to bulk insoluble organic material (IOM) from primitive meteorites. The second globule, from Cometary Track 2, contains non-aromatic organic matter with abundant nitrile ({single_bond}C{triple_bond}N) and carboxyl ({single_bond}COOH) functional groups. It is significantly enriched in D ({delta}D = 1000{per_thousand}) but has a terrestrial {sup 15}N/{sup 14}N ratio. Experiments indicate that similar D enrichments, unaccompanied by {sup 15}N fractionation, can be reproduced in the laboratory by electron irradiation of epoxy or cyanoacrylate. Thus, a terrestrial origin for this globule cannot be ruled out, and, conversely, exposure to high-energy electron irradiation in space may be an important factor in producing D anomalies in organic materials. For comparison, we report two Murchison globules: one with a large {sup 15}N enrichment and highly aromatic chemistry analogous to the Track 80 globule and the other only moderately enriched in {sup 15}N with IOM-like chemistry. The observation of organic globules in Comet 81P/Wild 2 indicates that comets likely sampled the same reservoirs of organic matter as did the chondrite parent bodies. The observed isotopic anomalies in the globules are most likely preserved signatures of low temperature (<10 K) chemistry in the interstellar medium or perhaps the outer regions of the solar nebula. In other extraterrestrial samples, D isotopic anomalies, but not those of {sup 15}N, may be explained in part by exposure to ionizing electron radiation.

  16. Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids

    NASA Technical Reports Server (NTRS)

    Cooper, George W.; Thiemens, Mark H.; Jackson, Teresa L.; Chang, Sherwood

    1997-01-01

    Intramolecular carbon, hydrogen, and sulfur isotope ratios were measured on a homologous series of organic sulfonic acids discovered in the Murchison meteorite. Mass-independent sulfur isotope fractionations were observed along with high deuterium/hydrogen ratios. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low-temperature environment that is consistent with that of interstellar clouds. Sulfur-33 enrichments observed in methanesulfonic acid could have resulted from gas-phase ultraviolet irradiation of a precursor, carbon disulfide. The source of the sulfonic acid precursors may have been the reactive interstellar molecule carbon monosulfide.

  17. Foraminiferal isotope anomalies from northwestern Pacific marginal sediments

    NASA Astrophysics Data System (ADS)

    Ohkushi, Ken'ichi; Ahagon, Naokazu; Uchida, Masao; Shibata, Yasuyuki

    2005-04-01

    We evaluated the influence of methane release from methane hydrate reservoirs in the northwestern Pacific continental margin on stable isotope values. We analyzed stable isotopes of foraminifera from a piston core collected at 1066-m water depth off eastern Hokkaido, northern Japan. Carbon isotope signals indicated that planktonic and benthic foraminifera in several glacial sediment layers in the core were highly depleted in 13C; both the planktonic and benthic foraminiferal ?13C values ranged from about -10‰ to -2‰. Most foraminiferal tests in these horizons were brown as a result of postdepositional alteration. Foraminiferal oxygen isotopes fluctuated abnormally in the glacial sediment layers, showing small (about 0.5‰) positive shifts relative to normal glacial values. We attributed the positive shifts to authigenic carbonate formation in the foraminiferal tests. The authigenic carbonates have formed when rising methane, from methane hydrate in the sediment, became oxidized as it came in contact with dissolved sulfate near the seafloor. Episodic methane-release events may be associated with great plate-boundary earthquakes with epicenters near the coring site.

  18. Oxygen isotope anomaly observed in water vapor from Alert, Canada and the implication for the stratosphere

    PubMed Central

    Lin, Ying; Clayton, Robert N.; Huang, Lin; Nakamura, Noboru; Lyons, James R.

    2013-01-01

    To identify the possible anomalous oxygen isotope signature in stratospheric water predicted by model studies, 25 water vapor samples were collected in 2003?2005 at Alert station, Canada (82°30?N), where there is downward transport of stratospheric air to the polar troposphere, and were analyzed for ?17O and ?18O relative to Chicago local precipitation (CLP). The latter was chosen as a reference because the relatively large evaporative moisture source should erase any possible oxygen isotope anomaly from the stratosphere. A mass-dependent fractionation coefficient for meteoric waters, ?MDF(H2O) = 0.529 ± 0.003 [2? standard error (SE)], was determined from 27 CLP samples collected in 2003?2005. An oxygen isotopic anomaly of ?17O = 76 ± 16 ppm (2? SE) was found in water vapor samples from Alert relative to CLP. We propose that the positive oxygen isotope anomalies observed at Alert originated from stratospheric ozone, were transferred to water in the stratosphere, and subsequently mixed with tropospheric water at high latitudes as the stratospheric air descended into the troposphere. On the basis of this ground signal, the average ?17O in stratospheric water vapor predicted by a steady-state box model is ?40‰. Seven ice core samples (1930?1991) from Dasuopu glacier (Himalayas, China) and Standard Light Antarctic Precipitation did not show an obvious oxygen isotope anomaly, and Vienna Standard Mean Ocean Water exhibited a negative ?17O relative to CLP. Six Alert snow samples collected in March 2011 and measured at Laboratoire des Sciences du Climat et de l'Environnement, Gif sur Yvette, France, had 17Oexcess of 45 ± 5 ppm (2? SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

  19. A theoretical investigation of isotopic anomalies of xenon in terrestrial and extra-terrestrial samples

    NASA Technical Reports Server (NTRS)

    Sabu, D. D.

    1977-01-01

    The abundance and isotopic composition of noble gases in meteorites is discussed in relation to the composition of the early solar system. Carbonaceous chondrites contain a unique Xenon-X, which is rich in heavy and light isotopes. Variations in the occurrence of type-X and type-Y (the normal component) noble gases are of such magnitude that neither the injection of material from a nearby supernova nor presence of presolar grains can account for the anomalies in meteorites. Therefore, it is suggested that the entire solar system may have condensed from the debris of a single local supernova.

  20. Zr isotope anomalies in chondrites and the presence of 92Nb in the early solar system

    NASA Astrophysics Data System (ADS)

    Sanloup, Chrystèle; Blichert-Toft, Janne; Télouk, Philippe; Gillet, Philippe; Albarède, Francis

    2000-12-01

    The presence of Zr isotope anomalies in the early solar system is demonstrated with the identification of 92Zr excesses and 96Zr deficits in several chondrites and the CAI Allende inclusions. The isotopic composition of Zr in carbonaceous, enstatite, and ordinary chondrites, along with four SNC meteorites, was analyzed by plasma source mass spectrometry. Most chondrite samples show negative96Zr anomalies, which indicate the presence of a pre-solar nucleosynthetic component. Six of them also display a distinct negative92Zr anomaly, reaching down to -2.7±0.8 ? units for Forest Vale (H4). The CAI inclusions from Allende, which are among the oldest known igneous objects of the solar system and have the highest Zr/Nb ratios, also show negative ?92Zr of -2.4±0.5. Although a substantial fraction of the Zr isotope variability may be due to pre-solar nucleosynthetic processes, part of the 92Zr excess must result from the decay of the now extinct 92Nb.

  1. Update and improvement of the global krypton-85 emission inventory.

    PubMed

    Ahlswede, Jochen; Hebel, Simon; Ross, J Ole; Schoetter, Robert; Kalinowski, Martin B

    2013-01-01

    Krypton-85 is mainly produced in nuclear reactors by fission of uranium and plutonium and released during chopping and dissolution of spent fuel rods in nuclear reprocessing facilities. As noble gas it is suited as a passive tracer for evaluation of atmospheric transport models. Furthermore, research is ongoing to assess its quality as an indicator for clandestine reprocessing activities. This paper continues previous efforts to compile a comprehensive historic emission inventory for krypton-85. Reprocessing facilities are the by far largest emitters of krypton-85. Information on sources and calculations used to derive the annual krypton-85 emission is provided for all known reprocessing facilities in the world. In addition, the emission characteristics of two plants, Tokai (Japan) and La Hague (France), are analysed in detail using emission data with high temporal resolution. Other types of krypton-85 sources are power reactors, naval reactors and isotope production facilities. These sources contribute only little or negligible amounts of krypton-85 compared to the large reprocessing facilities. Taking the decay of krypton-85 into account, the global atmospheric inventory is estimated to about 5500 PBq at the end of 2009. The correctness if the inventory has been proven by meteorological simulations and its error is assumed to be in the range of a few percent. PMID:22858641

  2. Nucleosynthetic osmium isotope anomalies in acid leachates of the Murchison meteorite

    E-print Network

    Reisberg, L; Luguet, A; Pearson, D G; Gallino, R; Zimmermann, C

    2008-01-01

    We present osmium isotopic results obtained by sequential leaching of the Murchison meteorite, which reveal the existence of very large internal anomalies of nucleosynthetic origin. The Os isotopic anomalies are correlated, and can be explained by the variable contributions of components derived from the s, r and p-processes of nucleosynthesis. Much of the s-process rich osmium is released by relatively mild leaching, suggesting the existence of an easily leachable s-process rich presolar phase, or alternatively, of a chemically resistant r-process rich phase. The s-process composition of Os released by mild leaching diverges slightly from that released by aggressive digestion techniques, perhaps suggesting that the presolar phases attacked by these differing procedures condensed in different stellar environments. The correlation between 190Os and 188Os can be used to constrain the s-process 190Os/188Os ratio to be 1.275 pm 0.043. Such a ratio can be reproduced in a nuclear reaction network for a MACS value f...

  3. TITLE Revised Manuscript, submitted 1 April 2010 1 Isotopic Anomalies in Organic Nanoglobules from Comet 81P/Wild 2: Comparison to Murchison

    E-print Network

    Nittler, Larry R.

    Isotopic Anomalies in Organic Nanoglobules from Comet 81P/Wild 2: Comparison to Murchison Nanoglobules and Isotopic Anomalies Induced in Terrestrial Organics by Electron Irradiation AUTHORS Bradley T. De Materials Science and Technology Division, Code 6366, U.S. Naval Research Laboratory, 4555 Overlook Ave. SW

  4. Osmium isotope anomalies in chondrites: Results for acid residues and related leachates

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tetsuya; O'D. Alexander, Conel M.; Walker, Richard J.

    2010-03-01

    We have investigated Os isotope anomalies in acid residues enriched in insoluble organic matter (IOM) extracted from ten primitive chondrites, acid leachates and residues of these fractions, as well as acid leachates of bulk chondrites. Osmium isotopic compositions of bulk carbonaceous, ordinary and enstatite chondrites are also reported. Consistent with prior results, bulk chondrites have homogeneous Os isotope compositions for s-, r-, and p-process nuclides that are indistinguishable from terrestrial, at the current level of resolution. In contrast, nearly all the IOM-rich residues are enriched in s-process Os, evidently due to the preferential incorporation of s-process enriched presolar grains (most likely presolar SiC). Presolar silicate grains that formed in red giant branch (RGB) or asymptotic giant branch (AGB) stars are also likely hosts of additional s-process Os in chondrites. Consistent with one prior study, Os released by weak acid leaching of bulk chondrites is slightly to strongly enriched in r-process nuclides, of which the carrier may be fine-grained presolar silicates formed in supernovae or unidentified solar phases. Collectively, the different, chemically concentrated components in these meteorites are variably enriched in s-, r-, and possibly p-process Os, of which the individual carriers must have been produced in multiple stellar environments. The lack of evidence for Os isotopic heterogeneity among bulk chondrites contrasts with evidence for isotopic heterogeneities for various other elements at approximately the same levels of resolution (e.g., Cr, Mo, Ru, Ba, Sm, and Nd). One possible explanation for this is that the heterogeneities for some elements in bulk materials reflect selective removal of some types of presolar grains as a result of nebular processes, and that because of the strong chemical differences between Os and the other elements, the Os was not significantly affected. Another possible explanation is that late-stage injection of isotopically distinct materials into the nebula led to heterogeneous distribution of some elements. Osmium may not have been affected because of a lack of isotopic contrast with the pre-injection, well mixed nebula.

  5. The effect of rising atmospheric oxygen on carbon and sulfur isotope anomalies in the Neoproterozoic Johnnie Formation, Death Valley, USA

    Microsoft Academic Search

    Alan J. Kaufman; Frank A. Corsetti; Michael A. Varni

    2007-01-01

    Carbonates within the Rainstorm Member in the terminal Neoproterozoic Johnnie Formation of Death Valley, California record a remarkable negative carbon isotope anomaly – to a nadir of near ?11‰ – that accompanies a dramatic rise in trace sulfate abundance and fall of carbonate associated sulfate ?34S values. The carbonates, including the laterally extensive Johnnie Oolite, were deposited during marine flooding

  6. Theoretical investigation of isotopic anomaly of xenon in carbonaceous chondrites and other terrestrial and extra-terrestrial samples

    NASA Technical Reports Server (NTRS)

    Sabu, D. D.

    1974-01-01

    The composition of Xe released from carbonaceous chondrites between 600 and 1000 C, particularly its isotopic trapped forms, is analyzed. Data show trapped Xe to have the following forms: Xe-124, 126, 130, 131, 132, 134, and 136. Attempts were also made to explain the Xe anomaly by mass fractionation as well as determine the relationship between metoritic trapped Xe and solar Xe.

  7. Pelagic anomalies and isotope signatures of molybdenum in temperate tidal systems

    NASA Astrophysics Data System (ADS)

    Kowalski, N.; Dellwig, O.; Neubert, N.; Gräwe, U.; Beck, M.; Nägler, T. F.; Brumsack, H.-J.; van Beusekom, J. E. E.; Böttcher, M. E.

    2012-04-01

    The seasonal dynamics of the redox-sensitive trace metal molybdenum (Mo) and its stable isotope signatures were investigated in the water column and in surface sediments of two tidal basins of the German Wadden Sea, North Sea. Dissolved Mo was assumed to behave conservatively in oxic seawater for a long time. Seasonal observations in the water column of tidal basins of the German Wadden Sea, however, have shown pronounced negative anomalies with decreases down to 50% of the expected salinity-normalized values. This non-conservative behaviour was recognized repeatedly in early summer during the years 2007 to 2011. A shift towards heavier ?98/95Mo values during the depletion period indicates a preferential removal of light Mo isotopes from the aqueous solution. As the Mo depletion coincides with collapsing summer phytoplankton blooms we suggest a tight coupling of Mo with algae derived organic matter. We estimate an isotope enrichment factor from the field data of about -0.3‰ for the removal process which is in agreement with those determined experimentally by Zerkle et al. (2011) during biological Mo uptake, but much less than during the adsorption to metal oxi(hydroxi)des (Wasylenki et al., 2008). A close association of Mo to organic matter in the tidal ecosystems is further indicated by high contents of Mo in the exterior organic layer (periostracum) of the shell of the invader mussel Ensis americanus displaying an isotope signature below the seawater molybdate value. Immobilized Mo may be transported to the surface sediments via organic-rich aggregates. After incorporation into the sediment the aggregates may be rapidly decomposed by microorganisms leading to a release of Mo to the pore waters. A positive anomaly of dissolved Mo was observed in the water column of the tidal area of Sylt Island in 2009. Laboratory experiments demonstrate efficient Mo release from anoxic sediments during sediment re-suspension in oxic sea water. Together with first modelling results, these data lead to the conclusion, that intense sediment re-suspension by high-energy bottom currents and in particular during storm events may cause a significant oxidative release of Mo temporarily enhancing pelagic Mo concentrations.

  8. Ca ISOTOPE EFFECTS IN ORGUEIL LEACHATES AND THE IMPLICATIONS FOR THE CARRIER PHASES OF {sup 54}Cr ANOMALIES

    SciTech Connect

    Moynier, Frederic; Podosek, Frank A.; Brannon, Joyce [Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St Louis, One Brookings Drive, St Louis, MO 63130 (United States); Simon, Justin I.; DePaolo, Donald J. [Center for Isotope Geochemistry, Department of Earth and Planetary Science, University of California, Berkeley, CA 94720 (United States); Meyer, Bradley S., E-mail: moynier@levee.wustl.ed, E-mail: fap@levee.wustl.ed, E-mail: jcbontravel@yahoo.co, E-mail: Justin.I.Simon@NASA.go, E-mail: depaolo@eps.berkeley.ed, E-mail: mbradle@clemson.ed [Department of Physics and Astronomy, Clemson University, 118 Kinard Laboratory, Clemson, SC 29634-0978 (United States)

    2010-07-20

    Primitive meteorites contain small {sup 40}Ca excesses, in addition to rare anomalies in {sup 48}Ca. Refractory inclusions from Vigarano and Allende have larger {sup 40}Ca and resolvable {sup 48}Ca anomalies. These results imply that Ca isotopic heterogeneities were still present in the early solar system at both the mineral and whole-rock scale. The absence of correlated Ca isotope anomalies in leachates from the CI1 chondrite Orgueil containing large {sup 54}Cr anomalies has implications on the origin of the Cr anomalies. {sup 54}Cr has to be produced either in massive stars during s-process nucleosynthesis without accompanying {sup 48}Ca or in particular zones in the rare Type Ia supernovae. In the latter case, {sup 54}Cr has been produced in a zone predominantly enriched in Cr and {sup 54}Cr and not mixed with other zones, or {sup 54}Cr has been produced together with other neutron-rich nuclides and there has been subsequent decoupling of this material in the star, in the solar system, or in the laboratory.

  9. Optical isotope shift and hyperfine structure measurements in preparation of the ultra-sensitive detection of krypton atoms using stepwise laser excitation and field ionization 

    E-print Network

    Lassen, Jens

    1996-01-01

    (2&t) '(v/d) E: = E, exp( ? 2r / d)cos(tn, t) gvf s ? ~21n2(2&t) '(4v/d)es47v/d (10) (12) (13) (14) For fast beams like those produced by isotope separators on line (ISOL) devices, with typically 30 keV energy, a Kr ion would attain a speed...

  10. Optical isotope shift and hyperfine structure measurements in preparation of the ultra-sensitive detection of krypton atoms using stepwise laser excitation and field ionization

    E-print Network

    Lassen, Jens

    1996-01-01

    fit to the hyperfine structure data when evaluating the hyperfine structure constants A and B. The results are the hyperfinestructure constants and isotope shifts in two transitions from the 5 s'[1/2]0' , IS3 , and three transitions from the 5 s[3...

  11. Erosion during accretion: Consequences for planetary iron-silicate ratios and tungsten isotope anomalies

    NASA Astrophysics Data System (ADS)

    Dwyer, C. A.; Nimmo, F.; Asphaug, E. I.; O'Brien, D. P.; Chambers, J.

    2011-12-01

    The late stages of planetary accretion involve stochastic, large collisions [1]. Although such collisions are usually assumed to result in perfect mergers, many of the collisions may instead result in hit-and-run events [2, 3] or erosion of existing bodies' mantles [4]. Impact-related erosion can have profound consequences for the rate and style of accretion [5] and the bulk chemistries of terrestrial planets [6]. Here we present some preliminary investigations into the occurrence of erosional collisions during late-stage accretion and consequences for the bulk chemistry and isotopic characteristics of the resulting planets. We have performed a preliminary investigation into the nature of late-stage accretion using an N-body simulation in which the different possible collision outcomes are treated in a more realistic manner than hitherto. The simulation starts with 155 planetesimals of roughly lunar mass; at the end, four bodies remain with masses of 0.83, 0.62, 0.33, and 0.02 Mearth. Collisional efficiency is parametrized based on the results of [7]. The results of the collisions, especially highly disruptive collisions, are idealized in order to be computationally tractable; in particular, bodies smaller than a minimum mass are not permitted. To track the bulk compositional evolution of the bodies, we assume all are initially chondritic. We alter the bulk chemistry after an impact according to a scheme which is based on the assumption that mantle material is much more likely to be eroded than core material. We track the tungsten isotopic evolution of each body using the method of [8] and treat the extent of core-mantle equilibration as a free parameter. The stochastic nature of planetary accretion means that even with perfect mergers, the tungsten isotope anomaly (eW) of the final bodies will vary, due to variations in the timing of the impacts which create the final bodies. Irrespective of accretion style, the extent of core re-equilibration affects eW. Including the effects of impact erosion results in a larger spread in eW and an increase in the average eW. A range in values of silicate mass fraction is produced, supporting the idea that erosional accretion can cause changes in bulk chemistry [6]. Compared with simulations assuming perfect mergers, we find that the time required to complete terrestrial planet formation is longer (190 Myr). Due to the long formation time and the observed existence of tungsten isotopic anomalies preserved in terrestrial and meteoric samples, core-mantle equilibration was likely minor. Future work will include a more realistic model for fragment size distribution and a greater number of simulation runs. [1] O'Brien et al. (2006) Icarus 184, 39-58. [2] Asphaug et al. (2006) Nature 439, 155-160. [3] Kokubo & Genda (2010) ApJ 714, L21-L25. [4] Benz et al. (2007) Space Sci Rev 132, 189-202. [5] Chambers (2008) Icarus 198, 256-273. [6] O'Neill & Palme (2008) Phil Trans R Soc A 366, 4205-4238. [7] Asphaug (2009) Ann Rev Earth Planet Sci 37, 413-448. [8] Nimmo & Agnor (2006) EPSL 243, 26-43. [9] Agnor & Asphaug (2004) ApJ 613, L157-L160. [10] Kleine et al. (2009) GCA 75, 5150-5188.

  12. The path to krypton and xenon isotope measurements from few-micron sized samples. I - A low-blank gas extraction system

    Microsoft Academic Search

    K. Ocker; N. Thonnard

    1997-01-01

    Resonance Ionization Spectroscopy Time-of-Flight (RIS-TOF) mass spectrometry uses lasers tuned to specific atomic energy levels of an element to be analyzed, generating only the ions of the chosen element. The unique advantages of grain-specific isotope data and a recent unsuccessful attempt to measure the noble gases from individual 'X' SiC grains with the about 2000 Xe-132 atom detection limit of

  13. Titles of invited speakers, Kaplan Workshop 2005 1. Mark Thiemens: Mass independent isotope effects: meteoritic oxygen isotopic anomalies

    E-print Network

    Einat, Aharonov

    fractionation of divalent cations; new approaches to old problems. Specific: Calcium isotope fractionation in calcite and aragonite. 10. Boaz Luz: Isotopic fractionations in the global oxygen cycle from the DoleTitles of invited speakers, Kaplan Workshop 2005 1. Mark Thiemens: Mass independent isotope effects

  14. Isotopic Anomalies in Primitive Solar System Matter: Spin-State Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds

    NASA Technical Reports Server (NTRS)

    Wirstrom, Eva S.; Charnley, Steven B.; Cordiner, Martin A.; Milan, Stefanie N.

    2012-01-01

    Organic material found in meteorites and interplanetary dust particles is enriched in D and N-15, This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar core. Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and N-15 and can account for the largest isotop c enrichments measured in carbonaceous meteorites, However, more recent measurements have shown that, in some primitive samples, a large N-15 enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, N-15 enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H2, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both N-15 and D in dense cloud cores, We also show that while the nitriles, HCN and HNC, contain the greatest N-15 enrichment, this is not expected to correlate with extreme D emichment. These calculations therefore support the view that Solar System N-15 and D isotopic anomalies have an interstellar heritage, We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

  15. Isotopic Anomalies in Primitive Solar System Matter: Spin-State-Dependent Fractionation of Nitrogen and Deuterium in Interstellar Clouds

    NASA Technical Reports Server (NTRS)

    Wirstrom, Eva S.; Charnley, Steven B.; Cordiner, Martin A.; Milam, Stefanie N.

    2012-01-01

    Organic material found in meteorites and interplanetary dust particles is enriched in D and N-15. This is consistent with the idea that the functional groups carrying these isotopic anomalies, nitriles and amines, were formed by ion-molecule chemistry in the protosolar nebula, Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and N-15 and can account for the largest isotopic enrichments measured in carbonaceous meteorites. However, more recent measurements have shown that, in some primitive samples, a large N-15 enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, N-15 enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H2, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both N-15 and D in dense cloud cores. We also show that while the nitriles, HCN and HNC, contain the greatest N=15 enrichment, this is not expected to correlate with extreme D enrichment. These calculations therefore support the view that solar system N-15 and D isotopic anomalies have an interstellar heritage. We also compare our results to existing astronomical observations and briefly discuss future tests of this model.

  16. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure [sup 85]Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce [sup 85]Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p[sub 6] state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the [sup 85]Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p[sub 8] energy level. Non-isotopically selective de-excitation rates as high as 5 [times] 10[sup 5] sec[sup [minus]1] have been measured, yielding a signal-to-background ratio of >10[sup 6]. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by [sup 85]Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  17. Excitation rate and background measurements during LIF studies on krypton

    SciTech Connect

    Whitehead, C.A.; Cannon, B.D.; Wacker, J.F.

    1993-04-01

    The Krypton Isotope Laser Analysis (KILA) method is being developed at the Pacific Northwest Laboratory (PNL) to measure {sup 85}Kr concentrations in small air samples. The technique uses high-resolution lasers to excite individual isotopes of krypton specifically to induce {sup 85}Kr to fluorescence for detection by optical means. Production of krypton metastables via two-photon excitation to the 2p{sub 6} state has been shown to be 0.15% efficient in 0.13 mTorr of krypton--sufficiently high to demonstrate overall feasibility of the KILA method. Since this goal was met, focus has been directed toward development of a working vacuum ultraviolet (VUV) fluorescence detection system and toward understanding the VUV background. This report describes the progress made in these two areas. The second step of the KILA process is to optically pump all except the {sup 85}Kr isotopes from the metastable state back to the ground state using laser-induced fluorescence (LIF). The rate of this process and the VUV background afterward will determine the sensitivity and selectivity of the KILA approach. De-excitation of the metastable population was accomplished via one-photon absorption of a continuous-wave (c-w) laser to the 2p{sub 8} energy level. Non-isotopically selective de-excitation rates as high as 5 {times} 10{sup 5} sec{sup {minus}1} have been measured, yielding a signal-to-background ratio of >10{sup 6}. The lifetime of the metastables is 1.2 msec in 200 mTorr of neon--much longer than the time required to de-excite krypton metastables and to detect fluorescence produced by {sup 85}Kr. After attaining these high de-excitation rates, a gated VUV detection system was built with a dynamic range large enough to measure a small background following de-excitation of large metastable populations. Future experiments will focus on reducing the background level by another 2--3 orders of magnitude and perfecting the isotopically selective de-excitation technique with known samples.

  18. Experimental Investigation of Continuous-Wave Laser Ionization of Krypton

    SciTech Connect

    Cannon, Bret D.; Shannon, Robert F.

    2001-10-30

    This report describes experimental investigations of a method that uses continuous-wave (CW) lasers to ionize selected isotopes of krypton with high isotopic selectivity. The experiments show that the ionization rate is at least a factor of 100 lower than calculated with our model that has been described in a previous report. This discrepancy may be due to a much smaller excitation cross section that expected based on previous work and/or the aberrations in the ultraviolet beam used for the first step in the excitation. Additional problems with damage to mirrors, alignment instabilities, and manufacturers halting production of key products make this approach not worth further development at this time

  19. NUCLEOSYNTHETIC TUNGSTEN ISOTOPE ANOMALIES IN ACID LEACHATES OF THE MURCHISON CHONDRITE: IMPLICATIONS FOR HAFNIUM-TUNGSTEN CHRONOMETRY

    SciTech Connect

    Burkhardt, Christoph; Wieler, Rainer [Institute of Geochemistry and Petrology, Clausiusstrasse 25, ETH Zurich, CH-8092 Zurich (Switzerland); Kleine, Thorsten [Institut fuer Planetologie, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Strasse 10, D-48149 Muenster (Germany); Dauphas, Nicolas, E-mail: burkhardt@erdw.ethz.ch [Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)

    2012-07-01

    Progressive dissolution of the Murchison carbonaceous chondrite with acids of increasing strengths reveals large internal W isotope variations that reflect a heterogeneous distribution of s- and r-process W isotopes among the components of primitive chondrites. At least two distinct carriers of nucleosynthetic W isotope anomalies must be present, which were produced in different nucleosynthetic environments. The co-variation of {sup 182}W/{sup 184}W and {sup 183}W/{sup 184}W in the leachates follows a linear trend that is consistent with a mixing line between terrestrial W and a presumed s-process-enriched component. The composition of the s-enriched component agrees reasonably well with that predicted by the stellar model of s-process nucleosynthesis. The co-variation of {sup 182}W/{sup 184}W and {sup 183}W/{sup 184}W in the leachates provides a means for correcting the measured {sup 182}W/{sup 184}W and {sup 182}W/{sup 183}W of Ca-Al-rich inclusions (CAI) for nucleosynthetic anomalies using the isotopic variations in {sup 183}W/{sup 184}W. This new correction procedure is different from that used previously, and results in a downward shift of the initial {epsilon}{sup 182}W of CAI to -3.51 {+-} 0.10 (where {epsilon}{sup 182}W is the variation in 0.01% of the {sup 182}W/{sup 183}W ratio relative to Earth's mantle). This revision leads to Hf-W model ages of core formation in iron meteorite parent bodies that are {approx}2 Myr younger than previously calculated. The revised Hf-W model ages are consistent with CAI being the oldest solids formed in the solar system, and indicate that core formation in some planetesimals occurred within {approx}2 Myr of the beginning of the solar system.

  20. DUPAL anomaly in the Sea of Japan: Pb, Nd, and Sr isotopic variations at the eastern Eurasian continental margin

    USGS Publications Warehouse

    Tatsumoto, M.; Nakamura, Y.

    1991-01-01

    Volcanic rocks from the eastern Eurasian plate margin (southwestern Japan, the Sea of Japan, and northeastern China) show enriched (EMI) component signatures. Volcanic rocks from the Ulreung and Dog Islands in the Sea of Japan show typical DUPAL anomaly characteristics with extremely high ??208/204 Pb (up to 143) and enriched Nd and Sr isotopic compositions (??{lunate}Nd = -3 to -5, 87Sr 86Sr = ~0.705). The ??208/204 Pb values are similar to those associated with the DUPAL anomaly (up to 140) in the southern hemisphere. Because the EMI characteristics of basalts from the Sea of Japan are more extreme than those of southwestern Japan and inland China basalts, we propose that old mantle lithosphere was metasomatized early (prior to the Proterozoic) with subduction-related fluids (not present subduction system) so that it has been slightly enriched in incompatible elements and has had a high Th/U for a long time. The results of this study support the idea that the old subcontinental mantle lithosphere is the source for EMI of oceanic basalts, and that EMI does not need to be stored at the core/ mantle boundary layer for a long time. Dredged samples from seamounts and knolls from the Yamato Basin Ridge in the Sea of Japan show similar isotopic characteristics to basalts from the Mariana arc, supporting the idea that the Yamato Basin Ridge is a spreading center causing separation of the northeast Japan Arc from Eurasia. ?? 1991.

  1. Correlated O and Mg isotopic anomalies in Allende inclusions: II. Magnesium

    Microsoft Academic Search

    G. J. Wasserburg; Typhoon Lee; D. A. Papanastassiou

    1977-01-01

    Mg in two Allende Ca-Al rich inclusions shows large isotopic, mass-dependent fractionation which enriched the heavier isotopes. After normalization, Mg in these inclusions shows negative delta²⁶Mg which appears to require the presence of nuclear effects in Mg distinct from ²⁶Al decay. The Mg mass fractionation is correlated with distinct but smaller fractionation effects for O reported by Clayton and Mayeda

  2. Isotope Anomalies in the Fe-group Elements in Meteorites and Connections to Nucleosynthesis in AGB Stars

    NASA Astrophysics Data System (ADS)

    Wasserburg, G. J.; Trippella, O.; Busso, M.

    2015-05-01

    We study the effects of neutron captures in AGB stars on “Fe-group” elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in 54Cr, 58Fe, and 64Ni in solar system materials, which are commonly attributed to supernovae (SNe). However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5 {{M}? } and 3 {{M}? } AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of 54Cr, 58Fe, and 64Ni, while the other isotopes are little altered; hence, the observations may be explained by AGB processing. The results are robust and not dependent on the detailed initial isotopic composition. Consequences for other “Fe group” elements are then explored. They include 50Ti excesses and some production of 46,47,49Ti. In many circumstellar condensates, Ti quantitatively reflects these effects of AGB neutron captures. Scatter in the data results from small variations (granularity) in the isotopic composition of the local ISM. For Si, the main effects are instead due to variations in the local ISM from different SN sources. The problem of Ca is discussed, particularly with regard to 48Ca. The measured data are usually represented assuming terrestrial values for 42Ca/44Ca. Materials processed in AGB stars or sources with variable initial 42Ca/44Ca ratios can give apparent 48Ca excesses/deficiencies, attributed to SNe. The broader issue of galactic chemical evolution is also discussed in view of the isotopic granularity in the ISM.

  3. CO self-shielding as the origin of oxygen isotope anomalies in the early solar nebula.

    PubMed

    Lyons, J R; Young, E D

    2005-05-19

    The abundances of oxygen isotopes in the most refractory mineral phases (calcium-aluminium-rich inclusions, CAIs) in meteorites have hitherto defied explanation. Most processes fractionate isotopes by nuclear mass; that is, 18O is twice as fractionated as 17O, relative to 16O. In CAIs 17O and 18O are nearly equally fractionated, implying a fundamentally different mechanism. The CAI data were originally interpreted as evidence for supernova input of pure 16O into the solar nebula, but the lack of a similar isotope trend in other elements argues against this explanation. A symmetry-dependent fractionation mechanism may have occurred in the inner solar nebula, but experimental evidence is lacking. Isotope-selective photodissociation of CO in the innermost solar nebula might explain the CAI data, but the high temperatures in this region would have rapidly erased the signature. Here we report time-dependent calculations of CO photodissociation in the cooler surface region of a turbulent nebula. If the surface were irradiated by a far-ultraviolet flux approximately 10(3) times that of the local interstellar medium (for example, owing to an O or B star within approximately 1 pc of the protosun), then substantial fractionation of the oxygen isotopes was possible on a timescale of approximately 10(5) years. We predict that similarly irradiated protoplanetary disks will have H2O enriched in 17O and 18O by several tens of per cent relative to CO. PMID:15902251

  4. Concurrent Births of the Organic Matter and the Oxygen Isotope Anomaly in the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Hashizume, K.; Takahata, N.; Naraoka, H.; Sano, Y.

    2011-03-01

    The coherent enrichments of 17,18O and 13C detected among organic grains extracted from an Antarctic CR2 chondrite suggest that the non-mass-dependent O-isotope fractionation occurred in a warm environment such as the envelope of the solar nebula.

  5. The astrophysical interpretation of isotope anomalies in graphite and SiC grains of chondrites

    NASA Technical Reports Server (NTRS)

    Lavrukhina, A. K.

    1993-01-01

    The C, N, and Mg isotopic compositions in graphite and SiC grains of carbonaceous chondrites can be explained by nuclear processes in massive O,B stars of second generation passed a stage of WR star with intensive stellar wind, where grain condensation had taken place. The interstellar graphite and SiC grains with anomalous isotopic compositions of C, N, Ne, and Si and other elements of nucleosynthetic origin, found in non-equilibrated chondrites, are most suitable for determination of astro-physical objects, where nucleosynthesis had taken place. Two objects were examined: (1) massive O,B stars of second generation passed a stage of WR star with intensive stellar wind (O,B-WR model) and (2) low-mass stars (1 less than or equal to M/solar mass less than or equal to 3) during thermally pulsing asymptotic giant branch phase (TP-AGB model).

  6. Calcium isotopic anomalies and the lack of aluminum-26 in an unusual Allende inclusion

    Microsoft Academic Search

    T. Lee; W. A. Russell; G. J. Wasserburg

    1979-01-01

    We have studied the Mg and Ca isotopic compositions of an unusual Allende inclusion dominated by hibonite, which is the most refractory and possibly the most primitive major oxide mineral. No ²⁶Mg excess was found in spite of the high ²⁷Al\\/²⁴Mg (1> or approx. =10³) of some samples, indicating an initial (²⁶Al\\/²⁷Al)â<2 x 10⁻⁷, a factor of 250 less than

  7. Extreme Carbon Isotope Anomalies of the Proterozoic Eon: Fact or Fiction?

    Microsoft Academic Search

    A. J. Kaufman

    2008-01-01

    Post-Paleozoic carbon isotope variations constructed from time-series analyses of calcareous microfossils generally pale in comparison with the extreme variations recorded in Paleozoic and Proterozoic aged successions. The latter are primarily preserved in fine-grained inorganic carbonates, which due to their great antiquity and potential for diagenetic alteration have been viewed by some as imperfect recorders of seawater chemistry. In part, this

  8. Sources of the oxygen isotopic anomaly in atmospheric N2O

    Microsoft Academic Search

    Mao-Chang Liang; Yuk L. Yung

    2007-01-01

    One-dimensional and two-dimensional models are used to investigate the isotopic composition of atmospheric N2O. The sources of N2O in the atmosphere are based on recent laboratory measurements of the N2O quantum yield in the mixture of O3\\/O2\\/N2 (Estupiñán et al., 2002). Two recently proposed pathways (Estupiñán et al., 2002; Prasad, 2005) are evaluated in the model. We find that the

  9. Isotope Ratio Triangulation: A Method for Determining Uranium Isotope Ratios and Application to the Search for Uranium Isotope Anomalies in the Mineral Titanite

    E-print Network

    Hill, Joseph Roger

    2014-11-10

    The U-Pb dating methods used in many geochronology laboratories take advantage of a mixed 235U-233U spike for precise uranium isotopic measurements and current data reduction algorithms assume a uniform 238U/235U value of 137.88. Recent re...

  10. Isotope Ratio Triangulation: A Method for Determining Uranium Isotope Ratios and Application to the Search for Uranium Isotope Anomalies in the Mineral Titanite 

    E-print Network

    Hill, Joseph Roger

    2014-11-10

    The U-Pb dating methods used in many geochronology laboratories take advantage of a mixed 235U-233U spike for precise uranium isotopic measurements and current data reduction algorithms assume a uniform 238U/235U value of 137.88. Recent re...

  11. Silver isotopic anomalies in iron meteorites: cosmic-ray production and other possible sources

    SciTech Connect

    Reedy, R.C.

    1980-04-18

    The sources of excess /sup 107/Ag observed in iron meteorites by Kaiser, Kelly, and Wasserburg (1980) are examined, with emphasis on the reactions of cosmic-ray particles with palladium. The cross sections for the production of the silver isotopes from palladium by energetic cosmic-ray particles are evaluated or estimated and used to calculate spallogenic production rates relative to that of /sup 53/Mn from iron. The upper limit for the production rate of excess /sup 107/Ag by galactic-cosmic-ray particles is 400 atoms/min/kg(Pd) which, over an exposure age of 10/sup 9/ years, would make only 1% of the observed excesses of /sup 107/Ag. Neutron-capture reactions with Pd isotopes produce mainly /sup 109/Ag. Binary fission of a siderophilic superheavy element would be expected to yield more /sup 109/Ag than /sup 107/Ag. An intense proton irradiation in the early solar system probably would produce a lower ratio of (/sup 107/Pd//sup 108/Pd) to (/sup 26/Al//sup 27/Al) than observed in meteorites. Therefore the presence of excess /sup 107/Ag in iron meteorites with large Pd/Ag ratios very likely is due to the incorporation of 6.5 x 10/sup 6/-year /sup 107/Pd of nucleosynthetic origin in these meteorites.

  12. Heavy nitrogen in Bencubbin - A light-element isotopic anomaly in a stony-iron meteorite

    NASA Astrophysics Data System (ADS)

    Franchi, I. A.; Wright, I. P.; Pillinger, C. T.

    1986-09-01

    Bencubbin, an unusual breccia found in Australia, comprising 60 - 75% metal with silicate and chondritic clasts in a shock-welded matrix, has been shown to contain an unprecedented enrichment (by a factor of 2) of 15N, presumably a nucleosynthetic product which escaped homogenization in the solar nebula. Here the authors show that virtually all the nitrogen in Bencubbin is enriched, with a maximum ?15N, of +0,1033%. The nitrogen resides in two acid-resistant components, one more so than the other, which are present in different proportions in the metal and silicate. The more resistant component could be carbonaceous, with an unusually low C:N ratio and without an anomalous carbon isotopic composition (?13C ? +2,5%). Another possible host is a chromium-rich sulphide, which would indicate processing in a supernova.

  13. Krypton Fluoride Laser Driven Inertial Fusion Energy

    E-print Network

    1 Krypton Fluoride Laser Driven Inertial Fusion Energy Presented to NAS Committee on the Prospects Fluoride (KrF) Laser? · Gas Laser--Excimer (Excited Dimer) · Fundamental wavelength is 248 nm · Energy

  14. Radial Distribution Functions of Liquid Krypton

    Microsoft Academic Search

    Ashfaq A. Khan

    1964-01-01

    Radial distribution functions g of liquid krypton have been computed at several values of temperature and density from the Percus-Yevick (PY) and the convolution-hypernetted-chain (CHNC) integral equations using two different interaction potentials [the Lennard-Jones (LJ) and Guggenheim-McGlashan (GM)] between the krypton atoms. The computed g's are compared with the neutron diffraction experimental g's of Clayton and Heaton. From the computed

  15. Nitrogen isotope ratios of nitrate and N* anomalies in the subtropical South Pacific

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Chisato; Makabe, Akiko; Shiozaki, Takuhei; Toyoda, Sakae; Yoshida, Osamu; Furuya, Ken; Yoshida, Naohiro

    2015-05-01

    Nitrogen isotopic ratios of nitrate (?15N-NO3-) were analyzed above 1000 m water depth along 17°S in the subtropical South Pacific during the revisit WOCE P21 cruise in 2009. The ?15N-NO3- and N* values were as high as 17‰ and as low as -18 ?mol N L-1, respectively, at depths around 250 m east of 115°W, but were as low as 5‰ and as high as +1 ?mol N L-1, respectively, in subsurface waters west of 170°W. The relationships among NO3- concentrations, N* values, ?15N-NO3- values, and oxygen and nitrite concentrations suggest that a few samples east of 90°W were from suboxic and nitrite-accumulated conditions and were possibly affected by in situ water column denitrification. Most of the high-?15N-NO3- and negative-N* waters were probably generated by mixing between Subantarctic Mode Water from the Southern Ocean and Oxygen Deficit Zone Water from the eastern tropical South Pacific, with remineralization of organic matter occurring during transportation. Moreover, the relationship between ?15N-NO3- and N* values, as well as Trichodesmium abundances and size-specific nitrogen fixation rates at the surface, suggest that the low-?15N-NO3- and positive-N* subsurface waters between 160°E and 170°W were generated by the input of remineralized particles created by in situ nitrogen fixation, mainly by Trichodesmium spp. Therefore, the ?15N values of sediments in this region are expected to reveal past changes in nitrogen fixation or denitrification rates in the subtropical South Pacific. The copyright line for this article was changed on 5 JUN 2015 after original online publication.

  16. The effect of rising atmospheric oxygen on carbon and sulfur isotope anomalies recorded in the Neoproterozoic Johnnie Formation, Death Valley, USA

    NASA Astrophysics Data System (ADS)

    Kaufman, A. J.; Corsetti, F. A.

    2004-12-01

    Carbonates within the Rainstorm Member in the terminal Neoproterozoic Johnnie Formation of Death Valley, California record a remarkable negative ? 13C anomaly to a nadir of near -11‰ , accompanied by a dramatic rise in trace sulfate abundance (>500 ppm) and drop in carbonate associated sulfate ? 34S values from 26.6‰ to 15.8‰ . The carbonates, including the laterally extensive Johnnie Oolite, were deposited during marine flooding atop a sequence boundary best observed in cratonward sections. A similarly dramatic carbon isotope anomaly is recorded in broadly equivalent successions that post-date known Marinoan glacial deposits and pre-date the Precambrian-Cambrian boundary in Oman, India, China, Australia, and Namibia. The cause of the carbon and sulfur isotopic excursions was likely associated with a rise in atmospheric O2, which resulted in 1) the oxidation of exposed continental shelf sediments rich in fossil organic matter and sulfides, providing a source of 12C, 32S, and sulfate; and 2) the ventilation of the oceans. Large metazoan fossils (Ediacaran animals) first appear directly above this anomaly, suggesting that a critical threshold with respect to atmospheric O2 had been crossed at this time. A negative ? 13C excursion of similar magnitude occurs in overlying strata at the Precambrian-Cambrian boundary, which may reflect similar processes.

  17. REVIEW ARTICLE: Method for counting noble gas atoms with isotopic selectivity

    Microsoft Academic Search

    G. S. Hurst; M. G. Payne; S. D. Kramer; C. H. Chen; R. C. Phillips; S. L. Allman; G. D. Alton; J. W. T. Dabbs; R. D. Willis; B. E. Lehmann

    1985-01-01

    A method has been developed for direct counting of noble gas atoms and has been demonstrated for selected isotopes of krypton. In principle, a few atoms of the noble gases argon, krypton, xenon and radon can now be counted with isotopic selectivity whether stable or radioactive. A concept was originated in which a laser method would be used to count

  18. Formation of actinide hexafluorides at ambient temperatures with krypton difluoride

    Microsoft Academic Search

    L. B. Asprey; P. G. Eller; Scott A. Kinkead

    1986-01-01

    A second low-temperature agent, krypton difluoride, for generating volatile plutonium hexafluoride is reported (dioxygen difluoride is the only other reported agent). Plutonium hexafluoride is formed at ambient or lower temperature by the treatment of various solid substrates with krypton difluoride. Volatilization of uranium and neptunium from solid substrates using gaseous krypton difluoride is also reported for the first time. The

  19. Formation of actinide hexafluorides at ambient temperatures with krypton difluoride

    SciTech Connect

    Asprey, L.B.; Eller, P.G.; Kinkead, S.A.

    1986-02-27

    A second low-temperature agent, krypton difluoride, for generating volatile plutonium hexafluoride is reported (dioxygen difluoride is the only other reported agent). Plutonium hexafluoride is formed at ambient or lower temperature by the treatment of various solid substrates with krypton difluoride. Volatilization of uranium and neptunium from solid substrates using gaseous krypton difluoride is also reported for the first time. The formation of actinide hexafluorides has been confirmed for the reaction of krypton difluoride in anhydrous HF with UO/sub 2/ and with uranium and neptunium fluorides at ambient temperatures. Treatment of americium dioxide with krypton difluoride did not yield americium hexafluoride under the conditions studied. 15 references, 2 figures.

  20. Determination of oxygen self-diffusion in akermanite, anorthite, diopside, and spinel: Implications for oxygen isotopic anomalies and the thermal histories of Ca-Al-rich inclusions

    SciTech Connect

    Ryerson, F.J. (Lawrence Livermore National Lab., CA (United States)); McKeegan, K.D. (Univ. of California, Los Angeles, CA (United States))

    1994-09-01

    Oxygen self-diffusion coefficients have been measured for three natural diopsidic clinopyroxenes, a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic akermanite for oxygen fugacities ranging from the NNO to IW buffers. The oxygen diffusion data are used to evaluate the effects of three different types of thermal histories upon the oxygen isotopic compositions of minerals found in Type B Ca-Al-rich inclusions (CAIBs) in carbonaceous chondrites: (1) gas-solid exchange during isothermal heating, (2) gas-solid exchange as a function of cooling rate subsequent to instantaneous heating, and (3) isotopic exchange with a gaseous reservoir during partial melting and recrystallization. With the assumptions that the mineral compositions within a CAIB were uniformly enriched in [sup 16]O prior to any thermal processing, that effective diffusion dimensions may be estimated from observed grain sizes, and that diffusion in diopside is similar to that in fassaitic clinopyroxene, none of the above scenarios can reproduce the relative oxygen isotopic anomalies observed in CAIBs without improbably long or unrealistically intense thermal histories relative to current theoretical models of nebular evolution. The failure of these simple models, coupled with recent observations of disturbed magnesium isotopic abundances and correlated petrographic features in anorthite and melilite indicative of alteration and recrystallization, suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization possibly interspersed with multiple melting events. Because the modal abundance of spinel remains relatively constant for plausible melting scenarios, and its relatively sluggish diffusion kinetics prevent substantial equilibration, Mg-Al spinel is the most reliable indicator of the oxygen isotopic composition of precursor material which formed Type B CAIs.

  1. Resonance ionisation mass spectrometry of krypton and its applications in planetary science

    NASA Astrophysics Data System (ADS)

    Strashnov, I.; Gilmour, J. D.

    2014-06-01

    A new resonance ionisation time-of-flight mass spectrometer for determining krypton isotope ratios in extraterrestrial samples is presented. Laser heating is used to extract gas from mg-size samples. A cryogenic sample concentrator is employed. Atoms continuously condense on a 75 K stainless steel substrate at the back plate of a Wiley-McLaren laser ion source from where they are desorbed by a pulsed 1064 nm laser and resonantly ionized in the plume. A three-colour (116.5 nm, 558.1 nm and 1064 nm) excitation scheme is used. Tuneable coherent Vacuum Ultraviolet (vuv) radiation near 116.5 nm is generated by four-wave sum frequency mixing of 252.5 nm and 1507 nm pulsed dye laser beams in a binary mixture of negatively and positively dispersive gases (Xe and Ar). Isotope effects have been observed that reduce the reproducibility of isotope ratio measurements between odd-mass, non-zero nuclear spin isotopes and even-mass, zero nuclear spin isotopes. This can be minimised and stabilised by controlling the laser fluences, experimental geometry, and the population of the magnetic sub-levels of the excited atomic states used in the ionisation process. Once stability is achieved, sample-standard bracketing (during which the known isotope ratios of a standard are determined before and after the measurements of the sample under the same conditions) allows precision and reproducibility of 1 % for the major isotope ratios to be achieved in samples krypton atoms. Detection limits of atoms/isotope have been demonstrated, ratios of Kr in meteorites have been made with 5-10 % precision. Applications of the instrument in various areas of planetary science are also discussed.

  2. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Self-luminous products containing tritium, krypton-85, or promethium-147... Self-luminous products containing tritium, krypton-85, or promethium-147...distribution self-luminous products containing tritium, krypton-85, or...

  3. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Self-luminous products containing tritium, krypton-85, or promethium-147... Self-luminous products containing tritium, krypton-85, or promethium-147...distribution self-luminous products containing tritium, krypton-85, or...

  4. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Self-luminous products containing tritium, krypton-85, or promethium-147... Self-luminous products containing tritium, krypton-85, or promethium-147...distribution self-luminous products containing tritium, krypton-85, or...

  5. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Self-luminous products containing tritium, krypton-85, or promethium-147... Self-luminous products containing tritium, krypton-85, or promethium-147...distribution self-luminous products containing tritium, krypton-85, or...

  6. 10 CFR 30.19 - Self-luminous products containing tritium, krypton-85, or promethium-147.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Self-luminous products containing tritium, krypton-85, or promethium-147... Self-luminous products containing tritium, krypton-85, or promethium-147...distribution self-luminous products containing tritium, krypton-85, or...

  7. Theoretical investigation of isotopic anomalies of xenon in terrestrial and extra-terrestrial samples. Final technical report, 1972--1977

    Microsoft Academic Search

    Sabu

    1977-01-01

    The abundance and isotopic composition of noble gases in meteorites is discussed in relation to the composition of the early solar system. Carbonaceous chondrites contain a unique Xenon-X, which is rich in heavy and light isotopes. Variations in the occurrence of type-X and type-Y (the normal component) noble gases are of such magnitude that neither the injection of material from

  8. 1, 393412, 2004 Carbon isotope

    E-print Network

    Boyer, Edmond

    BGD 1, 393­412, 2004 Carbon isotope anomaly in the major plant C1 pool F. Keppler et al. Title Page Biogeosciences Discussions is the access reviewed discussion forum of Biogeosciences Carbon isotope anomaly.keppler@qub.ac.uk) 393 #12;BGD 1, 393­412, 2004 Carbon isotope anomaly in the major plant C1 pool F. Keppler et al. Title

  9. Isotopic composition of noble gases in geothermal fluids of the Krušné Hory Mts., Czechoslovakia, and the nature of the local geothermal anomaly

    NASA Astrophysics Data System (ADS)

    Polyak, B. G.; Prasolov, E. M.; ?ermák, V.; Verkhovskiy, A. B.

    1985-03-01

    The contents and isotopic composition of all noble gases in the fluids from two localities (Karlovy Vary and Franti\\vskovy Lázn?) in Western Czechoslovakia are given. The data show: (1) atmospheric Ne, Ar, Kr and Xe, which indicates meteoric recharge; (2) excess He, attributed to radiogenic contributions; (3) a small excess of Ne, but the data shed no light on its origin. Even though there is no evidence of any juvenile component in these mineral waters, part of the dissolved He is believed to be of deep (mantle) origin. Correlation between the ratio 3He /4He and heat flow has been reported in the literature: our data enabled a direct test of this relationship and proved its fairly good validity. The combined interpretation of the heat flow and isotopic composition shows that the local heat flow anomaly in the Krušné Hory graben is of deep origin and was produced by the mass outflow which occurred during the Alpine activation of the Bohemian Massif.

  10. The LUX experiment - Design and performance of the krypton removal system

    NASA Astrophysics Data System (ADS)

    Lee, Chang

    2013-04-01

    LUX is an experiment built to detect weakly interacting massive particles as a candidate for cold dark matter using liquid xenon as a target material. Since xenon is a noble gas, a getter is used to remove most impurities. However, noble gas impurities remain, including radioactive krypton and argon isotopes which could dominate the dark matter signal. To remove these contaminants, a chromatographic separation system based on adsorption on activated charcoal was built using helium as a carrier gas. This talk will review the design and performance of the chromatographic system as it processed the LUX xenon stockpile in the fall of 2012.

  11. Natural versus anthropogenic sources in the surface- and groundwater dissolved load of the Dommel river (Meuse basin): Constraints by boron and strontium isotopes and gadolinium anomaly

    NASA Astrophysics Data System (ADS)

    Petelet-Giraud, Emmanuelle; Klaver, Gerard; Negrel, Philippe

    2009-05-01

    SummaryThe river Dommel, a tributary of the Meuse River, drains an area of intensive agriculture (livestock farming, maize and grassland over 50% of the basin), and a dense population of about 600,000 people representing 20% of the total area. The combined human activities in the Dommel catchment lead to a large amount of dissolved elements and compounds released in surface- and groundwaters. The aim of this study was to discriminate the natural (including infiltration of Meuse water) versus anthropogenic sources of the dissolved load, and to identify the various pollution sources such as agriculture, industrial activity, and wastewater treatment plants, using geochemical tools including major- and trace elements, Sr and B isotopes, and rare earth elements (REE). For that purpose, a same-day geochemical "Snapshot" picture of the entire basin was combined with monthly monitoring in strategic points. The major- and trace elements analyses allowed discriminating the main pollution sources affecting the basin, i.e. point versus diffuse sources. Strontium isotopes helped to identify each tributary and to calculate mixing proportions. Combining these calculations with the Sr-isotopic data obtained from the "Snapshot" sampling campaign during a low-flow period, shows that Meuse water infiltration represents 25% of the total Dommel discharge. Boron isotopes used for assessing the amount of water affected by anthropogenic input cannot discriminate between the two main anthropogenic inputs, i.e. urban wastewater and the zinc-smelter effluent, as they have similar ?11B values. Finally, the REE, and especially the use of Gd anomalies (Gd ?), demonstrated the generalized impact of urban wastewater on the streams of the Dommel Basin. The coupled use of different geochemical tracers (Sr and B isotopes together with Gd ?) in addition to the standard major-element analyses, led to discriminating the various anthropogenic components influencing the Dommel Basin water quality. With these tools it also became possible to assess the complex water circulation and exchanges between water compartments, including the major role of Meuse water through the Bocholt-Herenthals canal.

  12. Correlated Si isotope anomalies and large 13C enrichments in a family of exotic SiC grains.

    PubMed

    Stone, J; Hutcheon, I D; Epstein, S; Wasserburg, G J

    1991-01-01

    A suite of morphologically distinctive silicon carbide (SiC) grains from the Orgueil and Murchison carbonaceous chondrite meteorites contains Si and C of highly anomalous isotopic composition. All of the SiC grains in this suite are characterized by a distinctive platy morphology and roughly developed hexagonal crystal forms that allow them to be distinguished from other types of SiC found in the host meteorites. The delta 29Si and delta 30Si values of individual SiC crystals deviate from those of normal solar material by more than 100%, while the delta 13C values range from 150 to 5200%. Isotopically normal C and Si are not found in any of these SiC crystals. The SiC grains belonging to this morphological suite are isotopically distinct from fine-grained SiC aggregates and other morphological types of SiC in unequilibrated meteorites. The 29Si/28Si and 30Si/28Si ratios of these platy grains are well correlated and define a linear array that does not pass through the composition of normal, solar Si. This behavior contrasts sharply with the diverse and poorly correlated Si isotopic compositions shown by the total SiC population. We suggest that the distinctive morphological characteristics and comparatively simple Si isotope systematics identify the platy SiC crystals as a genetically related family, formed around a single, isotopically heterogeneous presolar star or an association of related stars. The enrichments in 13C and the Si isotope systematics of the platy SiC are broadly consistent with theoretical models of nucleosynthesis in low-mass, carbon stars on the asymptotic giant branch. The Si isotope array most plausibly reflects mixing between 28Si-rich material, inherited from a previous generation of stars, and material enriched in 29Si and 30Si, produced in intershell regions by neutron capture during He-burning. 13C is also produced in intershell regions by proton reactions on 12C seed nuclei and is carried with s-process nuclei to the stellar envelope by convection which penetrates down to the He shell. The absence of a correlation between the Si and C isotopic compositions of the SiC suggests either episodic condensation of SiC, extending over several thermal pulses, in the atmosphere of a single star, or derivation of the SiC from several stars characterized by different rates of 13C production. In the multiple star scenario, the linear correlation of the 29Si/28Si and 30Si/28Si ratios among the platy SiC indicates that these stars evolved from a common Si seed composition under similar conditions of neutron-capture nucleosynthesis. The 29Si/30Si ratio of the SiC, inferred by us to be produced by neutron capture in the stellar interior, is distinct from values calculated from models of nucleosynthesis in AGB stars. PMID:11538380

  13. Determination of oxygen self-diffusion in åkermanite, anorthite, diopside, and spinel: Implications for oxygen isotopic anomalies and the thermal histories of Ca-Al-rich inclusions

    NASA Astrophysics Data System (ADS)

    Ryerson, F. J.; McKeegan, Kevin D.

    1994-09-01

    Oxygen self-diffusion coefficients have been measured for three natural diopsidic clinopyroxenes, a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic åkermanite for oxygen fugacities ranging from the NNO to IW buffers. The experiments employed a gas-solid isotopic exchange technique utilizing 99% 18O-enriched CO-CO2 gas mixtures to control both the oxygen fugacity and the isotopic composition of the exchange reservoir. Diffusion profiles of the 18O tracer were obtained by in-depth analysis with an ion microprobe. The experimental results, fit to the Arrhenius relation D = D0e(-Q/RT), yield the following: Do (m2 s-1)Q (kJ mol-1)diopside4.3limit- 3.8+32.6× 10 - 4457 ± 26åkermanite4.7limit- 4.4+83.5× 10 - 7457 ± 26278 ± 33spinel2.2limit- 1.8+8.7× 10 - 7404 ± 21anorthite8.4limit- 8.0+174× 10 - 13162 ± 36 At a given temperature, oxygen diffuses about 100 times more slowly in diopside than indicated by previous bulk-exchange experiments (CONNOLLY and MUEHLENBACHS, 1988). Our data for anorthite, spinel, and åkermanite agree well with prior results obtained by gas-solid exchange and depth profiling methods (ELPHICK et al., 1988; REDDY and COOPER, 1981; YURIMOTO et al., 1989, respectively). Since these other experiments were conducted at different oxygen fugacities, this agreement indicates that diffusion of oxygen in these nominally Fe-free minerals is not greatly affected by fO2 in the range between pure oxygen and the iron-wüstite buffer. However, our diffusion coefficients for anorthite, melilite, and spinel are also uniformly lower than those obtained by bulk analysis of crushed powders at similar temperatures (MUEHLENBACHS and KUSHIRO, 1974; HAYASHI and MUEHLENBACHS, 1986; ANDO and OISHI, 1974). The oxygen diffusion data are used to evaluate the effects of three different types of thermal histories upon the oxygen isotopic compositions of minerals found in Type B Ca-Al-rich inclusions (CAIBs) in carbonaceous chondrites: (1) gas-solid exchange during isothermal heating, (2) gas-solid exchange as a function of cooling rate subsequent to instantaneous heating, and (3) isotopic exchange with a gaseous reservoir during partial melting and recrystallization. With the assumptions that the mineral compositions within a CAIB were uniformly enriched in 16O prior to any thermal processing, that effective diffusion dimensions may be estimated from observed grain sizes, and that diffusion in diopside is similar to that in fassaitic clinopyroxene, none of the above scenarios can reproduce the relative oxygen isotopic anomalies observed in CAIBs without improbably long or unrealistically intense thermal histories relative to current theoretical models of nebular evolution. The failure of these simple models, coupled with recent observations of "disturbed" magnesium isotopic abundances and correlated petrographic features in anorthite and melilite indicative of alteration and recrystallization, suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization possibly interspersed with multiple melting events. Because the modal abundance of spinel remains relatively constant for plausible melting scenarios, and its relatively sluggish diffusion kinetics prevent substantial equilibration, Mg-Al spinel is the most reliable indicator of the oxygen isotopic composition of precursor material which formed Type B CAIs.

  14. Stable-isotopic anomalies and the accretionary assemblage of the Earth and Mars: A subordinate role for carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Warren, Paul H.

    2011-11-01

    Plots such as ? 54Cr vs. ? 50Ti and ? 54Cr vs. ? 17O reveal a fundamental dichotomy among planetary materials. The "carbonaceous" chondrites, by virtue of high ? 50Ti and high ? 62Ni, as well as, especially for any given ? 17O, high ? 54Cr, are separated by a wide margin from all other materials. The significance of the bimodality is further manifested by several types of meteorites with petrological-geochemical characteristics that suggest membership in the opposite category from the true pedigree as revealed by the stable isotopes. Ureilites, for example, despite having diversely low ? 17O and about the same average carbon content as the most C-rich carbonaceous chondrite, have clear stable-isotopic signatures of noncarbonaceous pedigree. The striking bimodality on the ? 54Cr vs. ? 50Ti and ? 54Cr vs. ? 17O diagrams suggests that the highest taxonomic division in meteorite/planetary classification should be between carbonaceous and noncarbonaceous materials. The bimodality may be an extreme manifestation of the effects of episodic accretion of early solids in the protoplanetary nebula. However, an alternative, admittedly speculative, explanation is that the bimodality corresponds to a division between materials that originally accreted in the outer solar system (carbonaceous) and materials that accreted in the inner solar system (noncarbonaceous). In any event, both the Earth and Mars plot squarely within the noncarbonaceous composition-space. Applying the lever rule to putative mixing lines on the ? 50Ti vs. ? 54Cr and ? 17O vs. ? 54Cr diagrams, the carbonaceous/(carbonaceous + noncarbonaceous) mixing ratio C/( C + NC) is most likely close to (very roughly) 24% for Earth and 9% for Mars. Estimated upper limits for C/( C + NC) are 32% for Earth and 18% for Mars. However, the uncertainties are such that isotopic data do not require or even significantly suggest that Earth has higher C/( C + NC) than Mars. Among known chondrite groups, EH yields a relatively close fit to the stable-isotopic composition of Earth.

  15. SST Anomalies + Wind Anomalies

    NSDL National Science Digital Library

    Greg Shirah

    2003-02-03

    Sea surface temperature (SST) anomalies and sea surface wind anomalies show the development of the 2002-2003 El Nino based on data from NASAs Aqua and QuikSCAT spacecraft. The wind data has been processed using the Variational Analysis Method (VAM).

  16. Krypton Isotopic Compositions in Mainstream SiC Stardust Grains

    NASA Astrophysics Data System (ADS)

    Buntain, J.; Lugaro, M.; Iliadis, C.; Raut, R.; Tonchev, A.; Karakas, A. I.

    2012-09-01

    Kr is believed to be ionised and implanted in presolar SiC grains via stellar winds. Using computed AGB stellar models, we compare them to observed grain data in order to explain the 2 types of implantation methods presented by Verchovsky (2004).

  17. Geochemical Fingerprinting of Trans-Atlantic African Dust Based on Radiogenic Sr-Nd-Hf Isotopes and Rare Earth Element Anomalies

    NASA Astrophysics Data System (ADS)

    Pourmand, A.; Prospero, J. M.; Sharifi, A.

    2014-12-01

    Mineral dust is an important component of Earth's climate system and biogeochemical cycles on a global scale. In order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites, we must be able to identify the source provenance of dust. Here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long-range African dust (LRAD) collected between 2003 and 2011 in the trade winds on the Caribbean island of Barbados. We find systematic differences between Sr-Nd-Hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport. These results indicate that coherent geochemical source signatures of LRAD can be preserved even after transport across thousands of kilometers. We investigated the possibility of identifying the potential source areas through comparisons with literature data. However, these data are almost entirely based on measurements of soil and sediment samples; this could lead to biases because of soil-aerosol particle size and composition differences. Nonetheless, our data suggest that many samples are linked to sources in Mali and sub-Saharan regions. Radiogenic Nd-Hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites. In order to establish firmer links between LRAD and dust source areas, however, we require much more data on the geochemical composition of aerosols from potential source areas in North Africa.

  18. Geochemical Fingerprinting of Trans-Atlantic African Dust Based on Radiogenic Sr-Nd-Hf Isotopes and Rare Earth Element Anomalies

    NASA Astrophysics Data System (ADS)

    Pourmand, Ali; Prospero, Joseph; Sharifi, Arash

    2015-04-01

    Mineral dust is an important component of Earth's climate system and biogeochemical cycles on a global scale. In order to understand the relationship between climate processes in the source areas and the properties of aerosols at distant receptor sites, we must be able to identify the source provenance of dust. Here we present a multiproxy study that characterizes the temporal variability in the geochemical composition of long-range African dust (LRAD) collected between 2003 and 2011 in the trade winds on the Caribbean island of Barbados. We find systematic differences between Sr-Nd-Hf isotopic composition and rare earth element anomalies of individual dust events and evidence of seasonal shifts in dust source activity and transport. These results indicate that coherent geochemical source signatures of LRAD can be preserved even after transport across thousands of kilometers. We investigated the possibility of identifying the potential source areas through comparisons with literature data. However, these data are almost entirely based on measurements of soil and sediment samples; this could lead to biases because of soil-aerosol particle size and composition differences. Nonetheless, our data suggest that many samples are linked to sources in Mali and sub-Saharan regions. Radiogenic Nd-Hf composition of aerosols can potentially be a useful proxy to study the proximity of mineral dust sources to depositional sites. In order to establish firmer links between LRAD and dust source areas, however, we require much more data on the geochemical composition of aerosols from potential source areas in North Africa.

  19. Stress enhanced diffusion of krypton ions in polycrystalline titanium

    SciTech Connect

    Nsengiyumva, S., E-mail: s.nsengiyumva@ru.ac.za [Department of Physics and Electronics, Rhodes University, Grahamstown 6140 (South Africa); Raji, A. T. [School of Interdisciplinary Research and Graduate Studies, University of South Africa, Mucklenuek Campus, P O Box 392, UNISA 0003, Pretoria (South Africa); Rivière, J. P. [Laboratoire de Métallurgie Physique, UMR 6630 CNRS- Université de Poitiers, Bd M. et P. Curie, BP30179, 86962 Chasseneuil Futuroscope, Cedex (France); Britton, D. T.; Härting, M. [NanoSciences Innovation Center, Department of Physics, University of Cape Town, Rondebosch 7701 (South Africa)

    2014-07-14

    An experimental investigation on the mutual influence of pre-existing residual stress and point defect following ion implantation is presented. The study has been carried out using polycrystalline titanium samples energetically implanted with krypton ions at different fluences. Ion beam analysis was used to determine the concentration profile of the injected krypton ions, while synchrotron X-ray diffraction has been used for stress determination. Ion beam analysis and synchrotron X-ray diffraction stress profile measurements of the implanted titanium samples show a clear evidence of stress-enhanced diffusion of krypton ions in titanium. It is further observed that for the titanium samples implanted at low fluence, ion implantation modifies the pre-existing residual stress through the introduction of point and open volume defects. The stress fields resulting from the ion implantation act to drift the krypton inclusions towards the surface of titanium.

  20. HETEROGENEOUS ISOTOPIC ANOMALIES OF SM AND GD IN THE NORTON COUNTY METEORITE: EVIDENCE FOR IRRADIATION FROM THE ACTIVE EARLY SUN

    SciTech Connect

    Hidaka, Hiroshi; Kondo, Tomoyo [Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima 739-8526 (Japan); Yoneda, Shigekazu, E-mail: hidaka@hiroshima-u.ac.jp [Department of Science and Engineering, National Museum of Nature and Science, Tokyo 169-0073 (Japan)

    2012-02-20

    Large and heterogeneous isotopic variations of {sup 150}Sm/{sup 149}Sm and {sup 158}Gd/{sup 157}Gd due to neutron capture reactions caused by cosmic-ray irradiation were found in chemical and mineral separates from the Norton County meteorite. The light-colored separates, consisting mainly of enstatite (Mg{sub 2}Si{sub 2}O{sub 6}), have a very large neutron fluence of 1.98 Multiplication-Sign 10{sup 17} n cm{sup -2}, which is 10 times higher than that of the whole rock. Furthermore, four chemical separates showed a large variation in neutron fluences, ranging from 1.82 Multiplication-Sign 10{sup 16} to 1.87 Multiplication-Sign 10{sup 17} n cm{sup -2}. The variable amounts of neutron fluences from a small single fragment of the Norton County meteorite cannot be simply explained by single-stage cosmic-ray irradiation in space. Rare earth element (REE) analyses revealed that the fractions with high neutron fluences have similar chemical properties to those in the early condensates in the solar system, showing depletions of Eu and Yb in their REE abundance patterns. The data provide evidence for an activity of the early Sun (T Tauri), suggesting the migration of early and intense irradiation materials into the Norton County meteorite's parent body.

  1. A first roadmap for kryptology. [isotopic composition from supernovae

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Dziczkaniec, M.

    1980-01-01

    Studies of the complex variations of the isotopic composition of xenon in the solar system have been christened 'xenology'. In the title of the present investigation, the word 'kryptology' is employed to indicate the primary objective of the reported studies. This objective is related to the prediction of the isotopic composition of krypton which comes from a number of specific locations of a supernova in association with the isotopic compositions of xenon from these locations. Krypton is a logical candidate for testing the stellar theory on geochemical grounds, taking into account also the point of view of nucleosynthesis, because the isotopes of xenon and krypton are formed by the same thermonuclear processes in stars. The data and arguments presented in the investigation show that the treatment by Heymann and Dziczkaniec (1979), although not wrong, is too simplistic, because it has ignored the possibility of holdup and arrest in Xe network.

  2. Numerical investigation of the Krypton Large IMpulse Thruster

    NASA Astrophysics Data System (ADS)

    Kurzyna, Jacek

    2014-05-01

    Although xenon has long remained the propellant of choice for Hall effect and ion thrusters, its very high price has motivated the investigation of other noble gases as cost-effective options. The development of a 500 W-class Hall thruster at the Institute of Plasma Physics and Laser Microfusion (IPPLM) aims at demonstrating the possibility of operating with krypton at efficiencies close to that obtained with xenon. However, krypton's lower ionization cross-sections need to be compensated by a significant increase of the mass flow rate in comparison with xenon. The subsequent increase of the thermal load has a large impact on the thermal design of the thruster. In order to assess the operating parameters and the thermal fluxes expected during krypton operation, an extensive parametric study of Krypton Large Impulse Thruster's performance was conducted with the one-dimensional time-dependent hydrodynamic HETMAn solver developed at IPPLM. Comparative computations for xenon and krypton confirm that high efficiencies with krypton are possible, with a predicted maximum efficiency only a few per cent below that of xenon, although at mass flow rates ˜50% higher.

  3. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Self-luminous products containing tritium, krypton-85 or promethium-147... Self-luminous products containing tritium, krypton-85 or promethium-147...produce self-luminous products containing tritium, krypton-85, or...

  4. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Self-luminous products containing tritium, krypton-85 or promethium-147... Self-luminous products containing tritium, krypton-85 or promethium-147...produce self-luminous products containing tritium, krypton-85, or...

  5. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Self-luminous products containing tritium, krypton-85 or promethium-147... Self-luminous products containing tritium, krypton-85 or promethium-147...produce self-luminous products containing tritium, krypton-85, or...

  6. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Self-luminous products containing tritium, krypton-85 or promethium-147... Self-luminous products containing tritium, krypton-85 or promethium-147...produce self-luminous products containing tritium, krypton-85, or...

  7. Two-step laser excitation and field-ionization of krypton and xenon atoms in collinear fast-beam laser spectroscopy

    Microsoft Academic Search

    Jens Lassen

    2000-01-01

    In the context of ultra-trace detection and spectroscopy of trace amounts of the noble gases krypton and xenon, a collinear fast-beam laser-spectroscopy method was developed. In both fundamental research of short-lived isotopes, as well as in practical applications the task lies in devising a method that efficiently uses the minute sample sizes (in general less than 1013 atoms) with a

  8. Kinetic modelling of krypton fluoride laser systems

    SciTech Connect

    Jancaitis, K.S.

    1983-11-01

    A kinetic model has been developed for the KrF* rare gas halide laser system, specifically for electron-beam pumped mixtures of krypton, fluorine, and either helium or argon. The excitation produced in the laser gas by the e-beam was calculated numerically using an algorithm checked by comparing the predicted ionization yields in the pure rare gases with their experimental values. The excitation of the laser media by multi-kilovolt x-rays was also modeled and shown to be similar to that produced by high energy electrons. A system of equations describing the transfer of the initial gas excitation into the laser upper level was assembled using reaction rate constants from both experiment and theory. A one-dimensional treatment of the interaction of the laser radiation with the gas was formulated which considered spontaneous and stimulated emission and absorption. The predictions of this model were in good agreement with the fluorescence signals and gain and absorption measured experimentally.

  9. Neutron capture time scale of the s-process, estimated from s-process krypton in a meteorite

    NASA Technical Reports Server (NTRS)

    Matsuda, J.-I.; Lewis, R. S.; Anders, E.

    1980-01-01

    A krypton fraction enriched in s-process isotopes was extracted from a mineral fraction of the Murchison C2 chondrite. The (Kr-86)/(Kr-84) ratio is enhanced by 6 standard deviations, showing that significant amounts of Kr-86 were made in the s-process, despite the short, 10.8 yr beta-decay half-life of its precursor, Kr-85. Judging from this sample, the mean neutron capture time in the s-process was on the order of 5-100 yr for nuclei with cross sections of 125 mb.

  10. Metastable Krypton Beam Source via Two-Photon Pumping Technique

    SciTech Connect

    Wong, W.W.; Young, L.

    2003-01-01

    Metastable beams of rare gas atoms have wide applications in chemical analysis of samples, as well as in aiding understanding of fundamental processes and physical attributes. Most current sources of metastable rare gas atomic beams, however, are limited in their flux density, which greatly reduces their utility in applications such as low level trace analysis and precision measurements. Previous work has demonstrated feasibility of metastable krypton production via two-photon pumping, and this paper extends that possibility into beam form. Further optimization on this scheme, moreover, promises 100-fold increase of metastable krypton flux density over that of an rf-driven discharge.

  11. Perfusion measurement with Rubidium 81 to Krypton 81m ratio

    E-print Network

    Beasley, Charles Ward

    1982-01-01

    PERFUSION MEASUREMENT WITH RUBIDIUM 81 TO KRYPTON BiM RATIO A Thesis by CHARLES WARD BEASLEY Submitted to the Graduate College of Texas A&M University in partial ful lfi 1 lment of the requirement for the degree: MASTER OF SCIENCE December... 1982 Major Subject: Veterinary Physiology PERFUSION MEASUREMENT WITH RUBIDIUM 81 TO KRYPTON 81M RATIO A Thesis by CHARLES WARD BEASLEY Approved as to style and content by: Chairma of ommittee pi Me er Member er Head of Department December...

  12. ATTA-3: a State-of-the-Art Instrument for Radio-Krypton Dating

    NASA Astrophysics Data System (ADS)

    Jiang, W.; Zappala, J. C.; Bailey, K.; Lu, Z.; Müller, P.; O'Connor, T. P.

    2013-12-01

    The ATTA-3 instrument at Argonne has recently enabled routine Kr-81 dating. The instrument is based on Atom Trap Trace Analysis (ATTA), a novel laser based atom counting technique that allows detection of long lived noble gas radioisotopes (Kr-81, Kr-85 and Ar-39) with extremely low abundance (1E-16 to 1E-10). At the center of the instrument is a magneto-optical trap (MOT), which traps and counts only the atoms of the desired isotope. This unique feature makes ATTA free of interference from any other isotopes or molecular species. For Kr-81 dating in the age range of 150 - 1,500 kyr, the required sample size is 5 - 10 micro-L STP of krypton gas, which can be extracted from approximately 100 - 200 kg of water or 40 - 80 kg of ice. Several recent developments in our lab may lead to further improvements to the current ATTA-3 apparatus: 1) The isotopic abundance ratio between the unknown, rare isotope (either Kr-81 or Kr-85) and the stable, abundant isotope (Kr-83) is measured. Here the stable isotope serves as a control isotope. A new method has been developed that allows more accurate measurements of the control isotope Kr-83. Combined with the ability to measure the rare Kr-81 and Kr-85 isotopes, this scheme allows ATTA-3 to directly determine 81Kr/Kr and 85Kr/Kr ratios without other supplemental measurements, to reduce the overall uncertainties of the measured isotope ratios, and also to improve the long term stability of the system. 2) The current capacity of the ATTA-3 instrument is about 120 samples per year. The throughput is mainly limited by the so called 'memory effect', which is caused by the residual samples trapped in the system after each measurement. These residual samples are gradually released in subsequent measurements, causing cross-sample contaminations. In order to mitigate this problem, we wash the system with a xenon discharge for about 36 hours between measurements. This practice limits the overall sample processing speed. Preliminary investigations of the memory effect indicate that it can be reduced and the wash time between measurements shortened. This will increase the number of samples that the ATTA-3 instrument can handle annually in the future. This work is supported by DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  13. Construction and operation of an argon \\/krypton\\/ ion laser

    Microsoft Academic Search

    I. Gutu; I. Ivanov; R. Medianu; C. Georgescu

    1975-01-01

    Argon (krypton) laser experiments were performed in a segmented graphite plasma tube. The plasma tube operated either in the 'open-flow' or 'close-mode'. Technological details of several laser components are shown. The efficiency of internal gas recirculation and the effect of magnetic field intensity, discharge current, and mirror transmittance on output power were investigated. Photographs of the optical radiation mode pattern

  14. Near ultraviolet operation of argon and krypton ion lasers

    Microsoft Academic Search

    S. M. Jarrett; G. C. Barker

    1969-01-01

    Several reports on operation of ion lasers on the transitions between states in doubtedly ionized argon and krypton (Ar III and Kr III) leading to oscillation in the near ultraviolet have been given in the last three years (1-3). These reports deal with ultraviolet operation utilizing plasma tubes specifically designed to achieve high current densities. We have experimented with production

  15. Bangui Anomaly

    NASA Technical Reports Server (NTRS)

    Taylor, Patrick T.

    2004-01-01

    Bangui anomaly is the name given to one of the Earth s largest crustal magnetic anomalies and the largest over the African continent. It covers two-thirds of the Central African Republic and therefore the name derives from the capitol city-Bangui that is also near the center of this feature. From surface magnetic survey data Godivier and Le Donche (1962) were the first to describe this anomaly. Subsequently high-altitude world magnetic surveying by the U.S. Naval Oceanographic Office (Project Magnet) recorded a greater than 1000 nT dipolar, peak-to-trough anomaly with the major portion being negative (figure 1). Satellite observations (Cosmos 49) were first reported in 1964, these revealed a 40nT anomaly at 350 km altitude. Subsequently the higher altitude (417-499km) POGO (Polar Orbiting Geomagnetic Observatory) satellite data recorded peak-to-trough anomalies of 20 nT these data were added to Cosmos 49 measurements by Regan et al. (1975) for a regional satellite altitude map. In October 1979, with the launch of Magsat, a satellite designed to measure crustal magnetic anomalies, a more uniform satellite altitude magnetic map was obtained. These data, computed at 375 km altitude recorded a -22 nT anomaly (figure 2). This elliptically shaped anomaly is approximately 760 by 1000 km and is centered at 6%, 18%. The Bangui anomaly is composed of three segments; there are two positive anomalies lobes north and south of a large central negative field. This displays the classic pattern of a magnetic anomalous body being magnetized by induction in a zero inclination field. This is not surprising since the magnetic equator passes near the center of this body.

  16. Dust Particle Growth in a Sputtering Discharge with Krypton

    NASA Astrophysics Data System (ADS)

    Tawidian, H.; Mikikian, M.; Lecas, T.; Boufendi, L.

    2011-11-01

    Dust particles are grown in the PKE chamber by sputtering materials. The sputtering efficiency and the gas phase reactions can be affected by the gas type and particularly by the ion mass. Due to the presence of growing dust particles, the huge loss of electrons can trigger many instabilities in the plasma. These instabilities, the growth kinetics and the structure of the dust cloud, are compared by using two different gases: argon and krypton.

  17. Accurate ab initio potential for the krypton dimer and transport properties of the low-density krypton gas.

    PubMed

    Waldrop, Jonathan M; Song, Bo; Patkowski, Konrad; Wang, Xiaopo

    2015-05-28

    A new highly accurate potential energy curve for the krypton dimer was constructed using coupled-cluster calculations up to the singles, doubles, triples, and perturbative quadruples level, including corrections for core-core and core-valence correlation and for relativistic effects. The ab initio data points were fitted to an analytic potential which was used to compute the most important transport properties of the krypton gas. The viscosity, thermal conductivity, self-diffusion coefficient, and thermal diffusion factor were calculated by the kinetic theory at low density and temperatures from 116 to 5000 K. The comparisons with literature experimental data as well as with values from other pair potentials indicate that our new potential is superior to all previous ones. The transport property values computed in this work are recommended as standard values over the complete temperature range. PMID:26026447

  18. Noble gas anomalies related to high-intensity methane gas seeps in the Black Sea

    NASA Astrophysics Data System (ADS)

    Holzner, C. P.; McGinnis, D. F.; Schubert, C. J.; Kipfer, R.; Imboden, D. M.

    2008-01-01

    Dissolved noble gases and tritium were analyzed at a series of high-intensity methane gas seeps in the Black Sea to study the transport and gas exchange induced by bubble-streams in the water column. These processes affect marine methane emissions to the atmosphere and are therefore relevant to climate warming. The seep areas investigated are located in the Dnepr paleo-delta, west of Crimea, and in the Sorokin Trough mud volcano area, south-east of Crimea. Noble gas concentration profiles at active seep sites revealed prominent anomalies compared to reference profiles that are unaffected by outgassing. Supersaturations of the light noble gases helium and neon observed relatively close to the sea floor are interpreted as effects of gas exchange between the water and the rising bubbles. Depletions of the heavy noble gases argon, krypton and xenon that were detected above an active, bubble-releasing mud volcano appear to be related to the injection of fluids depleted in noble gases that undergo vertical transport in the water column due to small density differences. In both cases, the noble gas anomalies clearly document seep-specific processes which are difficult to detect by other methods. Helium is generally enriched in the deep water of the Black Sea due to terrigenic input. Although exceptionally high helium concentrations observed in one seep area indicate a locally elevated helium flux, most of the seeps studied seem to be negligible sources of terrigenic helium. Noble gas analyses of sediment pore waters from the vicinity of a mud volcano showed large vertical gradients in helium concentrations. The helium isotope signature of the pore waters points to a crustal origin for helium, whereas the deep water of the Black Sea also contains a small mantle-type component.

  19. The effect of rising atmospheric oxygen on carbon and sulfur isotope anomalies recorded in the Neoproterozoic Johnnie Formation, Death Valley, USA

    Microsoft Academic Search

    A. J. Kaufman; F. A. Corsetti

    2004-01-01

    Carbonates within the Rainstorm Member in the terminal Neoproterozoic Johnnie Formation of Death Valley, California record a remarkable negative delta 13C anomaly to a nadir of near -110\\/00 , accompanied by a dramatic rise in trace sulfate abundance (>500 ppm) and drop in carbonate associated sulfate delta 34S values from 26.60\\/00 to 15.80\\/00 . The carbonates, including the laterally extensive

  20. Determination of oxygen self-diffusion in akermanite, anorthite, diopside, and spinel: Implications for oxygen isotopic anomalies and the thermal histories of Ca-Al-rich inclusions

    Microsoft Academic Search

    F. J. Ryerson; K. D. McKeegan

    1994-01-01

    Oxygen self-diffusion coefficients have been measured for three natural diopsidic clinopyroxenes, a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic akermanite for oxygen fugacities ranging from the NNO to IW buffers. The oxygen diffusion data are used to evaluate the effects of three different types of thermal histories upon the oxygen isotopic compositions of minerals found in Type

  1. Separation of krypton and xenon from reactor atmospheres by selective permeation. Final report. [LMFBR

    Microsoft Academic Search

    S. A. Stern; S. M. Leone; F. J. Onorato; S. C. Wang

    1978-01-01

    The removal of krypton and xenon from nuclear reactor atmospheres by permeation through silicone rubber capillaries has been studied theoretically and experimentally. Permeator modules resembling shell-and-tube heat exchangers have been constructed and tested. Permeation cascades were designed for the removal of krypton and xenon from the following nuclear atmospheres: (a) the atmosphere of a reactor containment building after a nuclear

  2. An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in

    E-print Network

    Zelevinsky, Tanya

    An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in xenon ultra-low contamination by krypton in xenon dark matter detectors Tae Hyun Yoon The XENON dark matter within its liquid xenon (LXe) target. The trace 85Kr in the xenon target undergoes -decay with a 687 ke

  3. The adsorption of argon, krypton and xenon on activated charcoal

    SciTech Connect

    Underhill, D.W. [Univ. of South Carolina, Columbia, SC (United States)

    1996-08-01

    Charcoal adsorption beds are commonly used to remove radioactive noble gases from contaminated gas streams. The design of such beds requires the adsorption coefficient for the noble gas. Here an extension of the Dubinin-Radushkevich theory of adsorption is developed to correlate the effects of temperature, pressure, concentration, and carrier gas on the adsorption coefficients of krypton, xenon, and argon on activated carbon. This model is validated with previously published adsorption measurements. It accurately predicts the equilibrium adsorption coefficient at any temperature and pressure if the potential energies of adsorption, the micropore volume, and the van der Waals constants of the gases are known. 18 refs., 4 figs.

  4. Abundance Anomaly of the 13C Isotopic Species of c-C3H2 in the Low-mass Star Formation Region L1527

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Sakai, Nami; Tokudome, Tomoya; López-Sepulcre, Ana; Watanabe, Yoshimasa; Takano, Shuro; Lefloch, Bertrand; Ceccarelli, Cecilia; Bachiller, Rafael; Caux, Emmanuel; Vastel, Charlotte; Yamamoto, Satoshi

    2015-07-01

    The rotational spectral lines of c-C3H2 and two kinds of the 13C isotopic species, c-{}13{{CCCH}}2 ({C}2v symmetry) and c-{{CC}}13{{CH}}2 (Cs symmetry), have been observed in the 1–3 mm band toward the low-mass star-forming region L1527. We have detected 7, 3, and 6 lines of c-C3H2, c-{}13{{CCCH}}2, and c-{{CC}}13{{CH}}2, respectively, with the Nobeyama 45 m telescope and 34, 6, and 13 lines, respectively, with the IRAM 30 m telescope, where seven, two, and two transitions, respectively, are observed with both telescopes. With these data, we have evaluated the column densities of the normal and 13C isotopic species. The [c-C3H2]/[c-{}13{{CCCH}}2] ratio is determined to be 310 ± 80, while the [c-C3H2]/[c-{{CC}}13{{CH}}2] ratio is determined to be 61 ± 11. The [c-C3H2]/[c-{}13{{CCCH}}2] and [c-C3H2]/[c-{{CC}}13{{CH}}2] ratios expected from the elemental 12C/13C ratio are 60–70 and 30–35, respectively, where the latter takes into account the statistical factor of 2 for the two equivalent carbon atoms in c-C3H2. Hence, this observation further confirms the dilution of the 13C species in carbon-chain molecules and their related molecules, which are thought to originate from the dilution of 13C+ in the gas-phase C+ due to the isotope exchange reaction: {}13{{{C}}}++{CO}\\to {}13{CO}+{{{C}}}+. Moreover, the abundances of the two 13C isotopic species are different from each other. The ratio of c-{}13{{CCCH}}2 species relative to c-{{CC}}13{{CH}}2 is determined to be 0.20 ± 0.05. If 13C were randomly substituted for the three carbon atoms, the [c-{}13{{CCCH}}2]/[c-{{CC}}13{{CH}}2] ratio would be 0.5. Hence, the observed ratio indicates that c-{{CC}}13{{CH}}2 exists more favorably. Possible origins of the different abundances are discussed. Based on observations carried out with the IRAM 30 m Telescope and the NRO 45 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). NRO is a branch of the National Astronomical Observatory of Japan, National Institutes of Natural Sciences, Japan.

  5. DOWN'S ANOMALY.

    ERIC Educational Resources Information Center

    PENROSE, L.S.; SMITH, G.F.

    BOTH CLINICAL AND PATHOLOGICAL ASPECTS AND MATHEMATICAL ELABORATIONS OF DOWN'S ANOMALY, KNOWN ALSO AS MONGOLISM, ARE PRESENTED IN THIS REFERENCE MANUAL FOR PROFESSIONAL PERSONNEL. INFORMATION PROVIDED CONCERNS (1) HISTORICAL STUDIES, (2) PHYSICAL SIGNS, (3) BONES AND MUSCLES, (4) MENTAL DEVELOPMENT, (5) DERMATOGLYPHS, (6) HEMATOLOGY, (7)…

  6. Krypton-85 hydrofracture engineering feasibility and safety evaluation

    SciTech Connect

    Peretz, F.J.; Muller, M.E.; Pan, P.Y.

    1981-07-01

    Engineering studies have been made to determine the hazards associated with the disposal of /sup 85/Kr using the hydrofracture process. To assess the hazards, an effort has been made to identify the equipment required to entrain and dissolve the noble gas into the grout stream at hydrofracture pressure (up to 350 bar). Off-the-shelf or slightly modified equipment has been identified for safe and effective compression and gas-grout mixing. Each monthly injection disposes of 1.6 x 10/sup 6/ Ci of /sup 85/Kr. By connecting only one gas cylinder to the injection system at a time, the maximum amount of krypton likely to be released as a result of equipment failure is limited to 128,000 Ci. An evaluation by Los Alamos Technical Associates shows that releasing this amount of gas in less than one hour under worst-case meteorological conditions through a 30-m stack would result in a whole-body dose of 170 millirem at a distance of 1 km from the facility. A krypton collection and recovery system can further reduce this dose to 17 millirem; increasing the distance to the site boundary to 3 km can also reduce the dose by a factor of ten. Lung and skin dose estimates are 1.6 and 120 times the whole-body dose, respectively. These are all worst-case values; releases under more typical conditions would result in a significantly lower dose. No insurmountable safety or engineering problems have been identified.

  7. Beam of metastable krypton atoms extracted from a rf-driven discharge

    SciTech Connect

    Chen, C. Y.; Bailey, K.; Li, Y. M.; O'Connor, T. P.; Lu, Z.-T.; Du, X.; Young, L.; Winkler, G.

    2001-01-01

    A rf-driven discharge is used to produce a beam of metastable krypton atoms at the 5s(3/2){sub 2} level with an angular flux density of 4x10{sup 14}s{sup -1}sr{sup -1} and most probable velocity of 290 m/s, while consuming 7x10{sup 16} krypton atoms/s. When operated in a gas-recirculation mode, the source consumes 2x10{sup 15} krypton atoms/s with the same atomic-beam output.

  8. Investigation of many-body forces in krypton and xenon

    SciTech Connect

    Salacuse, J.J.; Egelstaff, P.A.

    1988-10-15

    The simplicity of the state dependence at relatively high temperatures ofthe many-body potential contribution to the pressure and energy has been pointed out previously (J. Ram and P. A. Egelstaff, J. Phys. Chem. Liq. 14, 29 (1984); A. Teitsima and P. A. Egelstaff, Phys. Rev. A 21, 367 (1980)). In this paper, we investigate how far these many-body potential terms may be represented by simple models in the case of krypton on the 423-, 273-, 190-, and 150-K isotherms, and xenon on the 170-, 210-, and 270-K isotherms. At the higher temperatures the best agreement is found for the mean-field type of theory, and some consequences are pointed out. On the lower isotherms a state point is found where the many-body energy vanishes, and large departures from mean-field behavior are observed. This is attributed to the influence of short-ranged many-body forces.

  9. Sheath oscillation characteristics and effect on near-wall conduction in a krypton Hall thruster

    NASA Astrophysics Data System (ADS)

    Zhang, Fengkui; Kong, Lingyi; Li, Chenliang; Yang, Haiwei; Li, Wei

    2014-11-01

    Despite its affordability, the krypton Hall-effect thruster in applications always had problems in regard to performance. The reason for this degradation is studied from the perspective of the near-wall conductivity of electrons. Using the particle-in-cell method, the sheath oscillation characteristics and its effect on near-wall conduction are compared in the krypton and xenon Hall-effect thrusters both with wall material composed of BNSiO 2 . Comparing these two thrusters, the sheath in the krypton-plasma thruster will oscillate at low electron temperatures. The near-wall conduction current is only produced by collisions between electrons and wall, thereby causing a deficiency in the channel current. The sheath displays spatial oscillations only at high electron temperature; electrons are then reflected to produce the non-oscillation conduction current needed for the krypton-plasma thruster. However, it is accompanied with intensified oscillations.

  10. On the interference of Kr during carbon isotope analysis of methane using continuous-flow combustion-isotope ratio mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schmitt, Jochen; Seth, Barbara; Bock, Michael; van der Veen, Carina; Möller, Lars; Sapart, Celia; Prokopiou, Markella; Sowers, Todd; Röckmann, Thomas; Fischer, Hubertus

    2014-05-01

    Stable carbon isotope analysis of methane (?13C of CH4) on atmospheric samples is one key method to constrain the current and past atmospheric CH4 budget. A frequently applied measurement technique is gas chromatography isotope ratio mass spectrometry coupled to a combustion-preconcentration unit. This report shows that the atmospheric trace gas krypton can severely interfere during the mass spectrometric measurement leading to significant biases in ?13C of CH4 if krypton is not sufficiently separated during the analysis. According to our experiments, the krypton interference is likely composed of two individual effects with the lateral tailing of the doubly charged 86Kr peak affecting the neighbouring m/z 44 and partially the m/z 45 Faraday cups. Additionally, a broad signal affecting m/z 45 and especially m/z 46 is assumed to result from scattered ions of singly charged krypton. The introduced bias in the measured isotope ratios is dependent on the chromatographic separation, the Kr to CH4 mixing ratio in the sample, the mass spectrometer source tuning as well as the detector configuration and can amount to up to several permil in ?13C. Apart from technical solutions to avoid this interference we present correction routines to a posteriori remove the bias.

  11. DEVELOPMENT OF A HYDROGEN MORDENITE SORBENT FOR THE CAPTURE OF KRYPTON FROM USED NUCLEAR FUEL REPROCESSING OFF-GAS STREAMS

    SciTech Connect

    Mitchell Greenhalgh; Troy G. Garn; Jack D. Law

    2014-04-01

    A novel new sorbent for the separation of krypton from off-gas streams resulting from the reprocessing of used nuclear fuel has been developed and evaluated. A hydrogen mordenite powder was successfully incorporated into a macroporous polymer binder and formed into spherical beads. The engineered form sorbent retained the characteristic surface area and microporosity indicative of mordenite powder. The sorbent was evaluated for krypton adsorption capacities utilizing thermal swing operations achieving capacities of 100 mmol of krypton per kilogram of sorbent at a temperature of 191 K. A krypton adsorption isotherm was also obtained at 191 K with varying krypton feed gas concentrations. Adsorption/desorption cycling effects were also evaluated with results indicating that the sorbent experienced no decrease in krypton capacity throughout testing.

  12. Discovery of Cadmium, Indium, and Tin Isotopes

    NASA Astrophysics Data System (ADS)

    Amos, Stephanie; Thoennessen, Michael

    2009-10-01

    As of today, no comprehensive study has been made covering the initial observations and identifications of isotopes. A project has been undertaken at MSU to document the discovery of all the known isotopes. The criteria defining discovery of a given isotope is the publication of clear mass and element assignment in a refereed journal. Prior to the current work the documentation of the discovery of eleven elements had been completed^1. These elements are cerium^2, arsenic, gold, tungsten, krypton, silver, vanadium, einsteinium, iron, barium, and cobalt. We will present the new documentation for the cadmium, indium, and tin isotopes. Thirty-seven cadmium isotopes, thirty-eight indium isotopes, and thirty-eight tin isotopes have been discovered so far. The description for each discovered isotope includes the year of discovery, the article published on the discovery, the article's author, the method of production, the method of identification, and any previous information concerning the isotope discovery. A summary and overview of all ˜500 isotopes documented so far as a function of discovery year, method and place will also be presented. ^1http://www.nscl.msu.edu/˜thoennes/2009/discovery.htm ^2J.Q. Ginepro, J. Snyder, and M. Thoennessen, At. Data Nucl. Data. Tables, in press (2009), doi:10.1016/j.adt.2009.06.002

  13. Pathway to cryogen free production of hyperpolarized Krypton-83 and Xenon-129.

    PubMed

    Six, Joseph S; Hughes-Riley, Theodore; Stupic, Karl F; Pavlovskaya, Galina E; Meersmann, Thomas

    2012-01-01

    Hyperpolarized (hp) (129)Xe and hp (83)Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp (129)Xe MRI cumbersome. For hp (83)Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For (129)Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized (129)Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm(3)/min. For hp (83)Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm(3)/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D(1) transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

  14. Pathway to Cryogen Free Production of Hyperpolarized Krypton-83 and Xenon-129

    PubMed Central

    Six, Joseph S.; Hughes-Riley, Theodore; Stupic, Karl F.; Pavlovskaya, Galina E.; Meersmann, Thomas

    2012-01-01

    Hyperpolarized (hp) 129Xe and hp 83Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp 129Xe MRI cumbersome. For hp 83Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For 129Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.5±1.9% spin polarized 129Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm3/min. For hp 83Kr, the equivalent of 4.4±0.5% spin polarization in pure krypton at a production rate of 2 cm3/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D1 transition was observed and taken into account for the qualitative description of the SEOP process. PMID:23209620

  15. The atmosphere of Mars near the surface - Isotope ratios and upper limits on noble gases

    NASA Technical Reports Server (NTRS)

    Biemann, K.; Lafleur, A. L.; Owen, T.; Rushneck, D. R.; Howarth, D. W.

    1976-01-01

    Several analyses of the Martian atmosphere have been carried out with the mass spectrometer in the molecular-analysis experiment. The ratios of abundant isotopes of carbon and oxygen are within 10 per cent of terrestrial values, whereas nitrogen-15 is considerably enriched on Mars. Argon-38 has been detected, and new limits on abundances of krypton and xenon have been set. The limit on krypton is sufficiently low to suggest that the inventories of volatile substances on Mars and on earth may be distinctly different.

  16. First Detection of Krypton and Xenon in a White Dwarf

    NASA Technical Reports Server (NTRS)

    Werner, Klaus; Rauch, Thomas; Ringat, Ellen; Kruk, Jeffrey W.

    2012-01-01

    We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 KrVI-VII and Xe VI-VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 plus or minus 0.5 and log Xe = -4.2 plus or minus 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the-precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and thaI the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell nash or a binary white dwarf merger.

  17. FIRST DETECTION OF KRYPTON AND XENON IN A WHITE DWARF

    SciTech Connect

    Werner, Klaus; Rauch, Thomas; Ringat, Ellen [Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University Tuebingen, Sand 1, 72076 Tuebingen (Germany); Kruk, Jeffrey W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2012-07-01

    We report on the first detection of the noble gases krypton (Z = 36) and xenon (54) in a white dwarf. About 20 Kr VI- VII and Xe VI- VII lines were discovered in the ultraviolet spectrum of the hot DO-type white dwarf RE 0503-289. The observations, performed with the Far Ultraviolet Spectroscopic Explorer, also reveal highly ionized photospheric lines from other trans-iron group elements, namely Ga (31), Ge (32), As (33), Se (34), Mo (42), Sn (50), Te (52), and I (53), from which gallium and molybdenum are new discoveries in white dwarfs, too. For Kr and Xe, we performed an NLTE analysis and derived mass fractions of log Kr = -4.3 {+-} 0.5 and log Xe = -4.2 {+-} 0.6, corresponding to an enrichment by factors of 450 and 3800, respectively, relative to the Sun. The origin of the large overabundances is unclear. We discuss the roles of neutron-capture nucleosynthesis in the precursor star and radiation-driven diffusion. It is possible that diffusion is insignificant and that the observed metal abundances constrain the evolutionary history of the star. Its hydrogen deficiency may be the consequence of a late helium-shell flash or a binary white dwarf merger.

  18. Large area electron beam pumped krypton fluoride laser amplifier

    SciTech Connect

    Sethian, J.D.; Obenschain, S.P.; Gerber, K.A.; Pawley, C.J.; Serlin, V.; Sullivan, C.A. [Plasma Physics Division, Naval Research Laboratory, Washington DC 20375 (United States)] [Plasma Physics Division, Naval Research Laboratory, Washington DC 20375 (United States); Webster, W. [Research Support Instruments, 4325-B Forbes Boulevard, Lanham, Maryland 20706 (United States)] [Research Support Instruments, 4325-B Forbes Boulevard, Lanham, Maryland 20706 (United States); Deniz, A.V.; Lehecka, T. [Science Applications International Corporation, 1710 Goodridge Drive, McLean, Virginia 22102 (United States)] [Science Applications International Corporation, 1710 Goodridge Drive, McLean, Virginia 22102 (United States); McGeoch, M.W. [PLEX Corporation, 21 Addington Road, Brookline, Massachusetts 02146 (United States)] [PLEX Corporation, 21 Addington Road, Brookline, Massachusetts 02146 (United States); Altes, R.A.; Corcoran, P.A.; Smith, I.D. [Pulse Sciences, Incorporated, 600 McCormick Street, San Leandro, California 94577 (United States)] [Pulse Sciences, Incorporated, 600 McCormick Street, San Leandro, California 94577 (United States); Barr, O.C. [Pharos Technical Enterprises, 1603 Barcelona Street, Livermore, California 94550 (United States)] [Pharos Technical Enterprises, 1603 Barcelona Street, Livermore, California 94550 (United States)

    1997-06-01

    Nike is a recently completed multi-kilojoule krypton fluoride (KrF) laser that has been built to study the physics of direct drive inertial confinement fusion. This paper describes in detail both the pulsed power and optical performance of the largest amplifier in the Nike laser, the 60 cm amplifier. This is a double pass, double sided, electron beam-pumped system that amplifies the laser beam from an input of 50 J to an output of up to 5 kJ. It has an optical aperture of 60 cm {times} 60 cm and a gain length of 200 cm. The two electron beams are 60 cm high {times} 200 cm wide, have a voltage of 640 kV, a current of 540 kA, and a flat top power pulse duration of 250 ns. A 2 kG magnetic field is used to guide the beams and prevent self-pinching. Each electron beam is produced by its own Marx/pulse forming line system. The amplifier has been fully integrated into the Nike system and is used on a daily basis for laser-target experiments. {copyright} {ital 1997 American Institute of Physics.}

  19. Krypton charge exchange cross sections for Hall effect thruster models

    NASA Astrophysics Data System (ADS)

    Hause, Michael L.; Prince, Benjamin D.; Bemish, Raymond J.

    2013-04-01

    Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr+ + Kr and Kr2+ + Kr cross sections. The measurements of symmetric Kr+ + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr2+ + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr2+ + Kr ? Kr+ + Kr+ reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 Å2 with an exception near 70-80 eV.

  20. Inertial Fusion Target Physics Advantages with the Krypton Fluoride Laser

    NASA Astrophysics Data System (ADS)

    Obenschain, Stephen

    2010-11-01

    The krypton fluoride (KrF) laser's short wavelength, broad bandwidth and capability to provide extremely uniform target illumination are advantages towards obtaining high gain direct drive implosions. The short wavelength helps suppress deleterious laser-plasma instabilities, and allows one to employ higher ablation pressures. In addition, the KrF architecture allows one to zoom down the focal diameter to follow the size of the imploding pellet, thereby improving the coupling efficiency. The NRL researchers have been conducting theoretical and experimental studies to quantify the beneficial effects of utilizing KrF light. Experiments using the Nike facility have confirmed that KrF light significantly increases the threshold for laser-plasma instability. This presentation will discuss the observed target physics with KrF light and its effects towards facilitating the high gains needed for power production with inertial fusion. Simulations indicate that shock ignited designs can achieve gains above 200 with KrF energies as low a 1 megajoule. For fusion energy a laser driver must be capable of high repetition rates (5-10 Hz) along with adequate efficiency and durability. The Electra KrF 30-cm aperture electron-beam-pumped amplifier has demonstrated long duration continuous operation at high-repetition rates. This and other advances show that the KrF laser should be able to meet the requirements.

  1. Noble gas abundance and isotope ratios in the atmosphere of Jupiter from the Galileo Probe Mass Spectrometer

    Microsoft Academic Search

    P. R. Mahaffy; H. B. Niemann; A. Alpert; S. K. Atreya; J. Demick; T. M. Donahue; D. N. Harpold; T. C. Owen

    2000-01-01

    The Galileo Probe Mass Spectrometer provided the first data on the noble gas mixing and isotope ratios in the Jovian atmosphere. These measurements and the comparison with solar values constrain models of Jupiter's formation. Significant refinements to the initially reported abundances of argon, krypton, and xenon have been enabled through post-encounter laboratory calibrations using a refurbished engineering unit mass spectrometer

  2. Breaking through the glass ceiling: The correlation between the self-diffusivity in and krypton permeation through deeply supercooled liquid nanoscale methanol films

    NASA Astrophysics Data System (ADS)

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-01

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures (100-115 K) near the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited on top of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare-gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  3. Isentropic Compression of Argon and Krypton Using AN MC-1 Flux Compression Generator

    NASA Astrophysics Data System (ADS)

    Veeser, L.; Ekdahl, C.; Oona, H.; Rodriguez, P.; Schmitt, G.; Solem, J.; Younger, S.; Baker, S.; Hudson, C.; Lewis, W.; Marshall, B.; Turley, W.; Bykov, A.; Boriskov, G.; Dolotenko, M.; Egorov, N.; Kolokol'Chikov, N.; Kozlov, M.; Kuropatkin, Y.; Volkov, A.

    2004-11-01

    LANL and VNIIEF are performing a set of joint experiments to explore the conductivity and possible metalization of argon and krypton compressed to up to five times normal solid density. The experiments use a magnetic field of several megagauss, generated by a Russian MC-1 generator [1], to compress a metallic tube containing solidified argon or krypton. A probe in the center of the tube measures the electrical conductivity to the walls, and a 70-MeV betatron serves as an x-ray source for three radiographic measurements of the compression. Several of these experiments for argon compressed to around 4 to 5 times solid density indicate a conductivity in the range of 10 to 100 ?-1 cm-1, well below that of a metal. For krypton preliminary results show a conductivity of order 1000 or more, indicating likely metalization of the compressed sample.

  4. Thermodynamic properties and transport coefficients of arc lamp plasmas: argon, krypton and xenon

    NASA Astrophysics Data System (ADS)

    Murphy, Anthony B.; Tam, Eugene

    2014-07-01

    Calculated values of the density, specific heat, enthalpy, viscosity, thermal conductivity and electrical conductivity of thermal plasmas formed from three gases used in arc lamps, krypton, argon and xenon, are presented. The calculations, which assume local thermodynamic equilibrium, were performed for pressures from 1 to 100 atm and for the temperature range 300-30?000 K. The results were compared with those of previously published studies. Some discrepancies were found for krypton and xenon; these are attributed to the improved values of the collision integrals used here in calculating the transport coefficients.

  5. Beam of metastable krypton atoms extracted from a microwave-driven discharge

    SciTech Connect

    Ding, Y.; Bailey, K.; Davis, A. M.; Hu, S.-M.; Lu, Z.-T.; O'Connor, T. P. [Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 and Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) and Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) and Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 and Department of Geophysical Sciences, University of Chicago, Chicago, Illinois 60637 (United States) and Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026 (China) and Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637; Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States) and Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States); Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2006-12-15

    A microwave-driven discharge is used to produce a thermal beam of metastable krypton atoms at the 5s[3/2]{sub 2} level with an angular flux density of 7x10{sup 14} s{sup -1} sr{sup -1}, while consuming 1x10{sup 17} krypton atoms/s. This source of atomic beam uses commercially available microwave parts, and has achieved comparable beam flux and excitation efficiency with a previously described source that employs a rf-driven discharge [C. Y. Chen et al., Rev. Sci. Instrum. 72, 271 (2001)].

  6. Beta-decay study of neutron rich isotopes of Bromine and Krypton

    SciTech Connect

    Miernik, Krzysztof A [ORNL; Gross, Carl J [ORNL; Grzywacz, Robert Kazimierz [ORNL; Madurga, M [University of Tennessee, Knoxville (UTK); Mendez, II, Anthony J [ORNL; Miller, D. [University of Tennessee, Knoxville (UTK); Padgett, S [University of Tennessee, Knoxville (UTK); Paulauskas, Stanley V [ORNL; Rykaczewski, Krzysztof Piotr [ORNL; Stracener, Daniel W [ORNL; Wolinska-Cichocka, Marzena [ORNL; Zganjar, E. F. [Louisiana State University; Batchelder, J. C. [Oak Ridge Associated Universities (ORAU); Brewer, N.T. [Vanderbilt University; Cartegni, L. [University of Tennessee, Knoxville (UTK); Fijalkowska, Aleksandra G [ORNL; Hamilton, J. H. [Vanderbilt University; Hwang, J. K. [Vanderbilt University; Ilyushkin, S. [Mississippi State University (MSU); Jost, Carola U [ORNL; Karny, M. [University of Warsaw; Korgul, A. [University of Warsaw; Krolas, W. [Oak Ridge Associated Universities (ORAU); Liu, S.H. [UNIRIB/ORAU and Vanderbilt University, Nashville, Tennessee; Mazzocchi, C. [University of Warsaw; Ramayya, A. V. [Vanderbilt University; Surman, Rebecca [Union College; Winger, J. A. [Mississippi State University (MSU); Wolinska-Cichocka, M [Oak Ridge Associated Universities (ORAU)

    2013-01-01

    Short lived neutron rich nuclei including 93 Br, 93 Kr and 94 Kr were produced in proton induced fission of 238 U at the HRIBF in Oak Ridge. Their beta decay was studied by means of a high resolution on line mass separator and beta gamma spectroscopy methods. The half life of 93Br T1/2 = 152(8) ms and delayed branching ratio of Pn = 53-8+11 may be compared to the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half life of 94Kr T1/2 = 227(14) ms and B delayed branching ratio of Pn = 1.9+0.6 0.2 % of 93Kr are in very good agreement with literature values. The decay properties of 93Br include four new gamma transitions following beta delayed neutron emission.

  7. SST Anomalies + Wind Anomalies (with dates)

    NSDL National Science Digital Library

    Greg Shirah

    2003-02-03

    Sea surface temperature (SST) anomalies and sea surface wind anomalies show the development of the 2002-2003 El Nino based on data from NASAs Aqua and QuikSCAT spacecraft. The wind data has been processed using the Variational Analysis Method (VAM).

  8. Ce and Nd isotope geochemistry on island arc volcanic rocks with negative Ce anomaly: existence of sources with concave REE patterns in the mantle beneath the Solomon and Bonin island arcs

    Microsoft Academic Search

    Hiroshi Shimizu; Hideyuki Sawatari; Yousuke Kawata; Peter N. Dunkley; Akimasa Masuda

    1992-01-01

    138Ce\\/142Ce isotope ratios in Cenozoic island arc volcanic rocks are reported for the first time, together with isotope ratios of Nd and Sr and abundances of REE, Ba and Sr. The island arc volcanics studies here are boninites from Chichijima, the Bonin Islands, and basalts and andesites from the Solomon Islands. REE patterns of the island arc volcanic rocks from

  9. Purification of krypton-xenon mixture from fluorine-containing gases

    NASA Astrophysics Data System (ADS)

    Adamov, V. S.; Yatkin, V. A.

    2007-06-01

    Active alumina was used to purify krypton-xenon mixtures from fluorine-containing gases (tetrafluoromethane and sulfur hexafluoride). At 580°C, the admixtures are converted into aluminum trifluoride, with their content in the test gas mixture reducing from hundreds of ppm to 0.1 ppm or even below.

  10. Effective and accurate approach for modeling of commensurate-incommensurate transition in krypton monolayer on graphite.

    PubMed

    Ustinov, E A

    2014-10-01

    Commensurate-incommensurate (C-IC) transition of krypton molecular layer on graphite received much attention in recent decades in theoretical and experimental researches. However, there still exists a possibility of generalization of the phenomenon from thermodynamic viewpoint on the basis of accurate molecular simulation. Recently, a new technique was developed for analysis of two-dimensional (2D) phase transitions in systems involving a crystalline phase, which is based on accounting for the effect of temperature and the chemical potential on the lattice constant of the 2D layer using the Gibbs-Duhem equation [E. A. Ustinov, J. Chem. Phys. 140, 074706 (2014)]. The technique has allowed for determination of phase diagrams of 2D argon layers on the uniform surface and in slit pores. This paper extends the developed methodology on systems accounting for the periodic modulation of the substrate potential. The main advantage of the developed approach is that it provides highly accurate evaluation of the chemical potential of crystalline layers, which allows reliable determination of temperature and other parameters of various 2D phase transitions. Applicability of the methodology is demonstrated on the krypton-graphite system. Analysis of phase diagram of the krypton molecular layer, thermodynamic functions of coexisting phases, and a method of prediction of adsorption isotherms is considered accounting for a compression of the graphite due to the krypton-carbon interaction. The temperature and heat of C-IC transition has been reliably determined for the gas-solid and solid-solid system. PMID:25296827

  11. Optical pumping and g-factor of the 3P0 state of the first excited configuration of rare gases odd isotopes

    E-print Network

    Boyer, Edmond

    résultats sont comparés à des prévisions théoriques. Abstract. 2014 Metastable np5(n + 1)s 3P0 (1s3 in Paschen notation) atoms of odd isotopes of neon, krypton and xenon have been optically pumped in a beam of metastable atoms by means of a C.W. single-mode dye laser. A magnetic resonance experiment leads

  12. Correlation between the thermal expansion coefficient and heat capacity of an inert-gas single crystal: Krypton

    NASA Astrophysics Data System (ADS)

    Bodryakov, V. Yu.

    2015-03-01

    Correlation dependence of volumetric thermal expansion coefficient o( T) on heat capacity C( T) for single-crystal krypton is studied. It is shown that the dependence o( C) is observed not only at low temperatures, where it is linear and is known as the Grüneisen law, but also in a much wider temperature range up to the melting point of krypton. When the specific heat reaches a classical limit of 3 R (according to the Dulong-Petit law), the o( C) dependence considerably deviates from the low-temperature linear behavior. The concept of the differential Grüneisen parameter of krypton, ?' ˜ (?o/? C), is introduced, and its temperature dependence is estimated.

  13. Analysis of spacecraft anomalies

    NASA Technical Reports Server (NTRS)

    Bloomquist, C. E.; Graham, W. C.

    1976-01-01

    The anomalies from 316 spacecraft covering the entire U.S. space program were analyzed to determine if there were any experimental or technological programs which could be implemented to remove the anomalies from future space activity. Thirty specific categories of anomalies were found to cover nearly 85 percent of all observed anomalies. Thirteen experiments were defined to deal with 17 of these categories; nine additional experiments were identified to deal with other classes of observed and anticipated anomalies. Preliminary analyses indicate that all 22 experimental programs are both technically feasible and economically viable.

  14. Metastability-exchange and depolarising collisions in xenon and krypton

    Microsoft Academic Search

    V. Lefevre-Seguin; M. Leduc

    1977-01-01

    Collisions between rare-gas atoms in the 3P2 metastable state and in the ground state were studied. The metastable atoms were created by a discharge and oriented by optical pumping, and pressure broadening of their magnetic-resonance curves was measured. For xenon, mixtures of even and odd isotopes were used, leading to a determination of the cross section for metastability-exchange collisions. For

  15. Lifshitz scale anomalies

    NASA Astrophysics Data System (ADS)

    Arav, Igal; Chapman, Shira; Oz, Yaron

    2015-02-01

    We analyse scale anomalies in Lifshitz field theories, formulated as the relative cohomology of the scaling operator with respect to foliation preserving diffeomorphisms. We construct a detailed framework that enables us to calculate the anomalies for any number of spatial dimensions, and for any value of the dynamical exponent. We derive selection rules, and establish the anomaly structure in diverse universal sectors. We present the complete cohomologies for various examples in one, two and three space dimensions for several values of the dynamical exponent. Our calculations indicate that all the Lifshitz scale anomalies are trivial descents, called B-type in the terminology of conformal anomalies. However, not all the trivial descents are cohomologically non-trivial. We compare the conformal anomalies to Lifshitz scale anomalies with a dynamical exponent equal to one.

  16. Anomaly detection using topology

    NASA Astrophysics Data System (ADS)

    Basener, Bill; Ientilucci, Emmett J.; Messinger, David W.

    2007-04-01

    In this paper we present a new topology-based algorithm for anomaly detection in dimensionally large datasets. The motivating application is hyperspectral imaging where the dataset can be a collection of ~ 10 6 points in R k, representing the reflected (or radiometric) spectra of electromagnetic radiation. The algorithm begins by building a graph whose edges connect close pairs of points. The background points are the points in the largest components of this graph and all other points are designated as anomalies. The anomalies are ranked according to their distance to the background. The algorithm is termed Topological Anomaly Detection (TAD). The algorithm is tested on hyperspectral imagery collected with the HYDICE sensor which contains targets of known reflectance and spatial location. Anomaly maps are created and compared to results from the common anomaly detection algorithm RX. We show that the TAD algorithm performs better than RX by achieving greater separation of the anomalies from the background for this dataset.

  17. Si isotope homogeneity of the solar nebula

    SciTech Connect

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric [Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Jackson, Matthew G. [Department of Earth Science, University of California, Santa Barbara, CA 93109 (United States); Barrat, Jean-Alix, E-mail: eapringle@wustl.edu, E-mail: savage@levee.wustl.edu, E-mail: pringle@ipgp.fr, E-mail: moynier@ipgp.fr, E-mail: jackson@geol.ucsb.edu, E-mail: Jean-Alix.Barrat@univ-brest.fr [Université Européenne de Bretagne, Université de Brest, CNRS UMR 6538 (Domaines Océaniques), I.U.E.M., Place Nicolas Copernic, F-29280 Plouzané Cedex (France)

    2013-12-20

    The presence or absence of variations in the mass-independent abundances of Si isotopes in bulk meteorites provides important clues concerning the evolution of the early solar system. No Si isotopic anomalies have been found within the level of analytical precision of 15 ppm in {sup 29}Si/{sup 28}Si across a wide range of inner solar system materials, including terrestrial basalts, chondrites, and achondrites. A possible exception is the angrites, which may exhibit small excesses of {sup 29}Si. However, the general absence of anomalies suggests that primitive meteorites and differentiated planetesimals formed in a reservoir that was isotopically homogenous with respect to Si. Furthermore, the lack of resolvable anomalies in the calcium-aluminum-rich inclusion measured here suggests that any nucleosynthetic anomalies in Si isotopes were erased through mixing in the solar nebula prior to the formation of refractory solids. The homogeneity exhibited by Si isotopes may have implications for the distribution of Mg isotopes in the solar nebula. Based on supernova nucleosynthetic yield calculations, the expected magnitude of heavy-isotope overabundance is larger for Si than for Mg, suggesting that any potential Mg heterogeneity, if present, exists below the 15 ppm level.

  18. High-resolution electron impact excitation functions of metastable states of neon, argon, krypton and xenon

    Microsoft Academic Search

    S J Buckman; P Hammond; G C King; F H Read

    1983-01-01

    Electron impact excitation of the lowest-lying metastable states of neon, argon, krypton and xenon have been studied as a function of incident electron energy over the range from threshold to the 2P1\\/2 ionisation potential and at an energy resolution of 20 meV or better. A wealth of structure is observed. Several of the features are very narrow and are coincident

  19. Chemical Applications of Metastable Argon Atoms. III. Production of Krypton and Xenon Metastable Atoms

    Microsoft Academic Search

    D. H. Stedman; D. W. SETSERt

    1970-01-01

    An inexpensive experimental technique has been developed for the production of argon, krypton, and xenon metastable atoms using a discharge-flow system. The reactions of these metastable atoms with N2, CO, and N2O were investigated in the pressure range 0.3–10 torr, and the emission spectra resulting from the reactions were identified. These spectra gave information about the collision event and also

  20. Infrared Absorptions of Interstitial Hydrogen Atoms in Solid Argon and Krypton

    Microsoft Academic Search

    Vladimir E. Bondybey; George C. Pimentel

    1972-01-01

    Infrared absorptions are reported in the spectra of inert gas-hydrogen matrix samples which were deposited after the gas mixture passed through a glow discharge. For hydrogen in argon, absorption is recorded at 905 cm?1. This band shifts to 644 cm?1 for deuterium in argon and no new bands are observed with hydrogen-deuterium mixtures. With krypton matrix, similar absorptions are observed

  1. [Vascular anomalies: information documents].

    PubMed

    Philandrianos, C; Degardin, N; Casanova, D; Bardot, J; Petit, P; Bartoli, J-M; Magalon, G

    2011-06-01

    Vascular anomalies are a complex pathological group. They are composed of hemangiomas and other vascular tumors and congenital vascular malformations: venous, lymphatic, arteriovenous and capillary malformations. The management of these anomalies is difficult and must involve an interdisciplinary approach. To help patients to understand their pathology, we have made some information documents. PMID:20598795

  2. Anomalies from Immersions

    E-print Network

    Ospina, J F

    2001-01-01

    Two forms of anomalies for chiral spinors living on submanifolds of the spacetime are obtained from the integrality theorem for immersions. The first form of the chiral anomaly is the usual for chiral spinors living on D-brane and O-plane intersections, the second form is exotic.

  3. Anomalies from Immersions

    E-print Network

    Juan Ospina

    2001-08-15

    Two forms of anomalies for chiral spinors living on submanifolds of the spacetime are obtained from the integrality theorem for immersions. The first form of the chiral anomaly is the usual for chiral spinors living on D-brane and O-plane intersections, the second form is exotic.

  4. Isotopic Biogeochemistry

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  5. Hydrodynamics with Triangle Anomalies

    E-print Network

    Dam T. Son; Piotr Surowka

    2009-07-13

    We consider the hydrodynamic regime of theories with quantum anomalies for global currents. We show that a hitherto discarded term in the conserve current is not only allowed by symmetries, but is in fact required by triangle anomalies and the second law of thermodynamics. This term leads to a number of new effects, one of which is chiral separation in a rotating fluid at nonzero chemical potential. The new kinetic coefficients can be expressed, in a unique fashion, through the anomalies coefficients and the equation of state. We briefly discuss the relevance of this new hydrodynamic term for physical situations, including heavy ion collisions.

  6. Hydrodynamics with Triangle Anomalies

    SciTech Connect

    Son, Dam T. [Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1550 (United States); Surowka, Piotr [Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

    2009-11-06

    We consider the hydrodynamic regime of theories with quantum anomalies for global currents. We show that a hitherto discarded term in the conserved current is not only allowed by symmetries, but is in fact required by triangle anomalies and the second law of thermodynamics. This term leads to a number of new effects, one of which is chiral separation in a rotating fluid at nonzero chemical potential. The new kinetic coefficients can be expressed, in a unique fashion, through the anomaly coefficients and the equation of state. We briefly discuss the relevance of this new hydrodynamic term for physical situations, including heavy-ion collisions.

  7. Anomalies on orbifolds

    SciTech Connect

    Arkani-Hamed, Nima; Cohen, Andrew G.; Georgi, Howard

    2001-03-16

    We discuss the form of the chiral anomaly on an S1/Z2 orbifold with chiral boundary conditions. We find that the 4-divergence of the higher-dimensional current evaluated at a given point in the extra dimension is proportional to the probability of finding the chiral zero mode there. Nevertheless the anomaly, appropriately defined as the five dimensional divergence of the current, lives entirely on the orbifold fixed planes and is independent of the shape of the zero mode. Therefore long distance four dimensional anomaly cancellation ensures the consistency of the higher dimensional orbifold theory.

  8. IN-SITU STUDY OF OXYGEN ISOTOPES IN GRAPHITE FROM L3 CHONDRITES: INDICATIONS FOR OXYGEN ISOTOPIC HETEROGENEITY. S. Mostefaoui1, FJ. Stadermann2, and A. El Goresy1. !Max-

    E-print Network

    IN-SITU STUDY OF OXYGEN ISOTOPES IN GRAPHITE FROM L3 CHONDRITES: INDICATIONS FOR OXYGEN ISOTOPIC-situ study of graphite-bearing assemblages in ordinary chondrites we found large H and N isotopic anomalies in-situ measurements of oxygen isotopes in graphite from the Khohar and Mez6-Madaras (L3) chondrites

  9. Mass Anomalies on Ganymede

    Microsoft Academic Search

    G. Schubert; J. D. Anderson; R. A. Jacobson; E. L. Lau; W. B. Moore; J. Palguta

    2004-01-01

    Analysis of radio Doppler data from the Galileo spacecraft's flybys of Ganymede has detected the existence of mass anomalies on Ganymede that plausibly lie near the interface between the ice and silicate shells and near the surface.

  10. Identification of Isotopically Primitive Interplanetary Dust Particles: A NanoSIMS Isotopic Imaging Study

    SciTech Connect

    Floss, Christine; Stadermann, Frank J.; Bradley, John P.; Dai, Zurong; Bajt, Sasa; Giles, Graham; Lea, Alan S.

    2006-05-01

    We have carried out a comprehensive survey of the isotopic compositions (H, B, C, N, O,S) of a suite of interplanetary dust particles (IDPs), including both cluster and individual particles. Isotopic imaging with the NanoSIMS shows the presence of numerous discrete hotspots that are strongly enriched in 15N, including the largest 15N enrichments ({approx}1300 ?) observed in IDPs to date. A number of the IDPs also contain larger regions with more modest enrichments in 15N, leading to average bulk N isotopic compositions that are 15N-enriched in these IDPs. Although C isotopic compositions are normal in most of the IDPs, two 15N-rich hotspots have correlated 13C anomalies. CN?/C? ratios suggest that most of the 15N-rich hotspots are associated with relatively N-poor carbonaceous matter, although specific carriers have not been determined. H isotopic distributions are similar to those of N: D anomalies are present both as distinct very D-rich hotspots and as larger regions with more modest enrichments. Nevertheless, H and N isotopic anomalies are not directly correlated, consistent with results from previous studies. Oxygen isotopic imaging shows the presence of abundant presolar silicate grains in the IDPs. The O isotopic compositions of the grains are similar to those found in presolar oxide and silicate grains from primitive meteorites. Most of the silicate grains in the IDPs have isotopic ratios consistent with meteoritic Group 1 oxide grains, indicating origins in oxygen-rich red giant and asymptotic giant branch stars, but several presolar silicates exhibit the 17O and 18O enrichments of Group 4 oxide grains, whose origin is less well understood. Based on their N isotopic compositions, the IDPs studied here can be divided into two groups. One group is characterized as being ''isotopically primitive'' and consists of those IDPs that have anomalous bulk N isotopic compositions. These particles typically also contain numerous 15N-rich hotspots, occasional C isotopic anomalies, and abundant presolar silicate grains. In contrast, the other ''isotopically normal'' IDPs have normal bulk N isotopic compositions and, although some contain 15N-rich hotspots, none exhibit C isotopic anomalies and none contain presolar silicate or oxide grains. Thus, isotopically interesting IDPs can be identified and selected on the basis of their N isotopic compositions for further study. However, this distinction does not extend to H isotopic compositions. Although both H and N anomalies 2 are frequently attributed to the survival of molecular cloud material in IDPs and, thus, should be more common in IDPs with anomalous bulk N compositions, D anomalies are as common in normal IDPs as they are in those characterized as isotopically primitive, based on their N isotopes. This may be due to different effects of secondary processing on the isotopic systems involved.

  11. Radioactive Iodine and Krypton Control for Nuclear Fuel Reprocessing Facilities

    SciTech Connect

    Soelberg, Nicolas R. [Idaho National Laboratory, Idaho Falls, ID (United States); Garn, Troy [Idaho National Laboratory, Idaho Falls, ID (United States); Greenhalgh, Mitchell [Idaho National Laboratory, Idaho Falls, ID (United States); Law, Jack [Idaho National Laboratory, Idaho Falls, ID (United States); Jubin, Robert T. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Strachan, Denis M. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Thallapally, Praveen K. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

    2013-01-01

    Nuclear fission results in the production of fission products and activation products, some of which tend to be volatile during used fuel reprocessing. These can evolve in volatile species in the reprocessing facility off-gas streams, depending on the separations and reprocessing technologies that are used. Radionuclides that have been identified as “volatile radionuclides” are noble gases (most notably isotopes of Kr and Xe); 3H; 14C; and 129I. Radionuclides that tend to form volatile species that evolve into reprocessing facility off-gas systems are more challenging to efficiently control compared to radionuclides that tend to stay in solid or liquid phases. Future used fuel reprocessing facilities in the United States can require efficient capture of some volatile radionuclides in their off-gas streams to meet regulatory emission requirements. In aqueous reprocessing, these radionuclides are most commonly expected to evolve into off-gas streams in tritiated water [3H2O (T2O) and 3HHO (THO)], radioactive CO2, noble gases, and gaseous HI, I2, or volatile organic iodides. The fate and speciation of these radionuclides from a non-aqueous fuel reprocessing facility is less well known at this time, but active investigations are in progress. An Off-Gas Sigma Team was formed in late FY 2009 to integrate and coordinate the Fuel Cycle Research and Development (FCR&D) activities directed towards the capture and sequestration of the these volatile radionuclides (Jubin 2012a). The Sigma Team concept was envisioned to bring together multidisciplinary teams from across the DOE complex that would work collaboratively to solve the technical challenges and to develop the scientific basis for the capture and immobilization technologies such that the sum of the efforts was greater than the individual parts. The Laboratories currently participating in this effort are Argonne National Laboratory (ANL), Idaho National Laboratory (INL), Oak Ridge National Laboratory (ORNL), Pacific Northwest National Laboratory (PNNL), and Sandia National Laboratories (SNL). This article focuses on control of volatile radionuclides that evolve during aqueous reprocessing of UNF. In particular, most of the work by the Off-gas Sigma Team has focused on the capture and sequestration of 129I and 85Kr, mainly because, as discussed below, control of 129I can require high efficiencies to meet regulatory requirements, and control of 85Kr using cryogenic processing, which has been the technology demonstrated and used commercially to date, can add considerable cost to a reprocessing facility.

  12. The Pioneer Anomaly

    Microsoft Academic Search

    Jose A. de Diego; Darío Núñez

    2008-01-01

    Analysis of the radio-metric data from Pioneer 10 and 11 spacecrafts has\\u000aindicated the presence of an unmodeled acceleration starting at 20 AU, which\\u000ahas become known as the Pioneer anomaly. The nature of this acceleration is\\u000auncertain. In this paper we give a description of the effect and review some\\u000arelevant mechanisms proposed to explain the observed anomaly. We

  13. Design and construction of a cryogenic distillation device for removal of krypton for liquid xenon dark matter detectors.

    PubMed

    Wang, Zhou; Bao, Lei; Hao, Xihuan; Ju, Yonglin

    2014-01-01

    Liquid xenon (Xe) is one of the commendable detecting media for the dark matter detections. However, the small content of radioactive krypton-85 ((85)Kr) always exists in the commercial xenon products. An efficient cryogenic distillation system to remove this krypton (Kr) from commercial xenon products has been specifically designed, developed, and constructed in order to meet the requirements of the dark matter experiments with high- sensitivity and low-background. The content of krypton in regular commercial xenon products can be reduced from 10(-9) to 10(-12), with 99% xenon collection efficiency at maximum flow rate of 5 kg/h (15SLPM). The purified xenon gases produced by this distillation system can be used as the detecting media in the project of Panda X, which is the first dark matter detector developed in China. PMID:24517821

  14. The cosmic molybdenum-ruthenium isotope correlation

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Davis, Andrew M.; Marty, Bernard; Reisberg, Laurie

    2004-10-01

    Dauphas et al. [Astrophys. J. 565 (2002) 640-644] reported molybdenum isotopic anomalies in differentiated and bulk primitive meteorites. It is shown here that these isotopic anomalies correlate with one another in exactly the way expected from nucleosynthesis theory if different regions of the nebula received different contributions of s-process matter synthesized in low-mass AGB stars. Furthermore, when bulk measurements are grouped by meteorite class, the molybdenum isotopic anomalies correlate with the ruthenium isotopic anomalies recently reported by Chen et al. [Lunar Planet. Sci. XXXIV (2003) #1789], again indicating a heterogeneous distribution of s-process matter. As molybdenum is only moderately siderophile, most of the molybdenum presently in the mantle was delivered before the completion of core formation. In contrast, because ruthenium is highly siderophile, nearly all of the mantle ruthenium was delivered by a late veneer, after the end of core formation. Thus, the fact the silicate Earth lies on the Mo-Ru cosmic correlation supports the idea that the Earth accreted homogeneously. Stated otherwise, the feeding zone of the Earth did not change drastically with time, as both the bulk of the Earth and the late veneer accreted from material from the same Mo-Ru isotopic reservoir.

  15. Measurement of the Cotton-Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus

    E-print Network

    Mei, Hsien-Hao; Chen, Sheng-Jui; Pan, Sheau-shi

    2008-01-01

    Experiments for vacuum birefringence and vacuum dichroism have set up high-finesse high magnetic experimental apparatuses which are ideal for gaseous Cotton-Mouton effect measurements. PVLAS Collaboration has recently measured Cotton-Mouton effects in krypton, xenon and neon at the wavelength of 1064 nm. In this Letter, we report on our measurement of Cotton-Mouton effects in nitrogen, oxygen, carbon dioxide, argon, and krypton at pressure P = 0.5-300 Torr, temperature T = 295-298 K, and laser wavelength of 1064 nm in a magnetic field B = 2.3 T, using our Q & A experimental setup, which are in agreement with the PVLAS results.

  16. Measurement of the Cotton-Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus

    E-print Network

    Hsien-Hao Mei; Wei-Tou Ni; Sheng-Jui Chen; Sheau-shi Pan

    2009-02-11

    Experiments for vacuum birefringence and vacuum dichroism have been set up with high-finesse high magnetic experimental apparatuses, which seem to be ideal for small gaseous Cotton-Mouton effect (CME) measurements. PVLAS Collaboration has measured CMEs in krypton, xenon and neon at the wavelength of 1064 nm. In this Letter, we report on our measurement of CMEs in nitrogen, oxygen, carbon dioxide, argon, and krypton at the same wavelength in a magnetic field B = 2.3 T at pressure P = 0.5-300 Torr and temperature T = 295-298 K. Our results agree with the PVLAS results in the common cases.

  17. Breaking through the glass ceiling: the correlation between the self-diffusivity in and krypton permeation through deeply supercooled liquid nanoscale methanol films.

    PubMed

    Smith, R Scott; Matthiesen, Jesper; Kay, Bruce D

    2010-03-28

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures (100-115 K) near the glass transition temperature, T(g) (103 K). Layered films, consisting of CH(3)OH and CD(3)OH, are deposited on top of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above T(g). The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare-gas permeation technique as a tool for probing the diffusivity of supercooled liquids. PMID:20370128

  18. Calcium and titanium isotopic fractionations during evaporation

    NASA Astrophysics Data System (ADS)

    Zhang, Junjun; Huang, Shichun; Davis, Andrew M.; Dauphas, Nicolas; Hashimoto, Akihiko; Jacobsen, Stein B.

    2014-09-01

    Isotope fractionations associated with high temperature evaporation provide important constraints on the physicochemical processes that affected planetary materials at the birth of the solar system. Previous evaporation experiments have focused on isotopic fractionation of moderately to highly volatile elements. Here, we investigate the isotope fractionation behavior of two highly refractory elements, calcium and titanium, during evaporation of perovskite (CaTiO3) in a vacuum furnace. In our experiments, isotope fractionation during evaporation follows the Rayleigh law, but not the commonly used exponential law, with the dominant evaporating species being Ca(g) and TiO2(g). If isotope fractionations in early solar system materials did follow the Rayleigh law, the common practice of using an exponential fractionation law to correct for mass-dependent fractionation in the study of mass-independent fractionations may introduce significant artificial isotope anomalies.

  19. Neon isotopes in submarine basalts

    Microsoft Academic Search

    Philippe Sarda; Thomas Staudacher; Claude J. Allègre

    1988-01-01

    Very large neon isotopic anomalies have been accurately measured in mid-ocean ridge basalt glassy samples from diverse locations worldwide. Values for 20Ne\\/22Ne range up to ~ 13 and 21Ne\\/22Ne values range up to ~ 0.07 (present atmospheric values are 20Ne\\/22Ne = 9.8 and 21Ne\\/22Ne = 0.029). The data are highly correlated in the 20Ne\\/22Ne-21Ne\\/22Ne diagram, independent of sample location. Loihi

  20. Astrometric solar system anomalies

    SciTech Connect

    Nieto, Michael Martin [Los Alamos National Laboratory; Anderson, John D [PROPULSION LABORATORY

    2009-01-01

    There are at least four unexplained anomalies connected with astrometric data. perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr{sup -1}. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is produent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.

  1. Unintentional fatal intoxications with mitragynine and O-desmethyltramadol from the herbal blend Krypton.

    PubMed

    Kronstrand, Robert; Roman, Markus; Thelander, Gunilla; Eriksson, Anders

    2011-05-01

    The leaves of Kratom, a medicinal plant in Southeast Asia, have been used as an herbal drug for a long time. At least one of the alkaloids present in Kratom, mitragynine, is a mu-receptor agonist. Both Kratom and an additional preparation called Krypton are available via the internet. It seems to consist of powdered Kratom leaves with another mu-receptor agonist, O-desmethyltramadol, added. O-Desmethyltramadol is an active metabolite of tramadol, a commonly prescribed analgesic. We present nine cases of intoxication, occurring in a period of less than one year, where both mitragynine and O-desmethyltramadol were detected in the postmortem blood samples. Neither tramadol nor N-desmethyltramadol was present in these samples, which implies that the ingested drug was O-desmethyltramadol. The blood concentrations of mitragynine, determined by ultra-performance liquid chromatography-tandem mass spectrometry, ranged from 0.02 to 0.18 ?g/g, and O-desmethyltramadol concentrations, determined by gas chromatography with nitrogen-specific detection, ranged from 0.4 to 4.3 ?g/g. We believe that the addition of the potent mu-receptor agonist O-desmethyltramadol to powdered leaves from Kratom contributed to the unintentional death of the nine cases presented and conclude that intake of Krypton is not as harmless as it often is described on internet websites. PMID:21513619

  2. First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium

    SciTech Connect

    B. Beeler; B. Good; S. Rashkeev; M. Baskes; M. Okuniewski

    2012-06-01

    While metallic fuels have a long history of reactor use, their fundamental physical and thermodynamic properties are not well understood. Many metallic nuclear fuels are body-centered cubic alloys of uranium that swell under fission conditions, creating fission product gases such as helium, xenon and krypton. In this paper, helium, xenon, and krypton point defects are investigated in the a and ? phases of metallic uranium using first principles calculations. A density functional theory (DFT) framework is utilized with projector augmented-wave (PAW) pseudopotentials. Formation and incorporation energies of He, Xe, and Kr are calculated at various defect positions for the prediction of fission gas behavior in uranium. In most cases, defect energies follow a size effect, with helium incorporation and formation energies being the smallest. The most likely position for the larger Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed. This is the first detailed study of the stability and incorporation of fission gases in uranium.

  3. Evaluation of target power supplies for krypton storage in sputter-deposited metals

    SciTech Connect

    Greenwell, E.N.; McClanahan, E.D.; Moss, R.W.

    1986-04-01

    Implantation of /sup 85/Kr in a growing sputtered metal deposit has been studied for the containment of /sup 85/Kr recovered from the reprocessing of spent nuclear fuel. PNL, as part of DOE's research program for /sup 85/Kr storage, has developed krypton trapping storage devices (KTSDs) in a range of sizes for ''cold'' and radioactive testing. The KTSD is a stainless steel canister that contains a sputtering target for depositing an amorphous rare-earth transition metal on the inner wall and simultaneously implanting low-energy krypton ions in the growing deposit. This report covers the design requirements for the target power supply and the description, testing and evaluation of three basic designs. The designs chosen for evaluation were: (1) a standard commercial power supply with an external PNL-designed current interrupter, (2) a commercially manufactured power supply with an integral series-type interrupter, and (3) a commercially manufactured power supply with an integral shunt-type interrupter. The units were compared on the basis of performance, reliability, and life-cycle cost. 8 refs., 9 figs., 2 tabs.

  4. Electron excitation coefficients of neutral and ionic levels of krypton in Townsend discharges

    NASA Astrophysics Data System (ADS)

    Malovi?, G. N.; Strini?, A. I.; Petrovi?, Z. Lj.; Sadeghi, N.

    2006-08-01

    In this paper, we present experimental results for excitation coefficients of krypton atoms to several Kr and Kr + excited levels for E/ N (electric field to gas particle number density ratio usually in units of Townsend, 1 Td = 10 - 21 V m 2) values from 7 × 10 - 20 V m 2 to above 1 × 10 - 17 V m 2. The data have been obtained in two different parallel plate self-sustained Townsend discharge drift tubes. The spatial distribution of the emission intensities were recorded and then normalized to give excitation coefficients at the anode, by using the electron flux at this point. The values of these coefficients are placed on an absolute scale by using a standard tungsten ribbon lamp calibrated against a primary blackbody radiation standard. The ionization rates at different E/ N are obtained from the spatial emission profiles. The data for atomic krypton levels 2p 2, 2p 3, 2p 5, 2p 6, 2p 7, 2p 8, 3p 5 and 3p 6 (in Paschen notation) were converted to excitation coefficients by using quenching coefficients from the literature. The emission coefficients of eight 4s 24p 4 ( 3P)5p levels of Kr + have also been measured for E/ N values from about 1 × 10 - 18 V m 2 up to nearly 8 × 10 - 18 V m 2.

  5. First-principles calculations of the stability and incorporation of helium, xenon and krypton in uranium

    NASA Astrophysics Data System (ADS)

    Beeler, B.; Good, B.; Rashkeev, S.; Deo, C.; Baskes, M.; Okuniewski, M.

    2012-06-01

    While metallic fuels have a long history of reactor use, their fundamental physical and thermodynamic properties are not well understood. Many metallic nuclear fuels are body-centered cubic alloys of uranium that swell under fission conditions, creating fission product gases such as helium, xenon and krypton. In this paper, helium, xenon, and krypton point defects are investigated in the ? and ? phases of metallic uranium using first principles calculations. A density functional theory (DFT) framework is utilized with projector augmented-wave (PAW) pseudopotentials. Formation and incorporation energies of He, Xe, and Kr are calculated at various defect positions for the prediction of fission gas behavior in uranium. In most cases, defect energies follow a size effect, with helium incorporation and formation energies being the smallest. The most likely position for the larger Xe and Kr atoms in uranium is the substitutional site. Helium atoms are likely to be found in a wide variety of defect positions due to the comparable formation energies of all defect configurations analyzed. This is the first detailed study of the stability and incorporation of fission gases in uranium.

  6. Cerebral developmental venous anomalies

    Microsoft Academic Search

    Diego San Millán Ruíz; Philippe Gailloud

    2010-01-01

    Introduction  Cerebral developmental venous anomalies (DVAs) are the most frequently encountered cerebral vascular malformation. As such,\\u000a they are often observed incidentally during routine CT and MRI studies. Yet, what DVAs represent from a clinical perspective\\u000a is frequently not common knowledge and DVAs, therefore, still generate uncertainty and concern amongst physicians. This article\\u000a reviews our current understanding of developmental venous anomalies.\\u000a \\u000a \\u000a \\u000a \\u000a Results  In

  7. Classical Trace Anomaly

    E-print Network

    M. Farhoudi

    2005-11-03

    We seek an analogy of the mathematical form of the alternative form of Einstein's field equations for Lovelock's field equations. We find that the price for this analogy is to accept the existence of the trace anomaly of the energy-momentum tensor even in classical treatments. As an example, we take this analogy to any generic second order Lagrangian and exactly derive the trace anomaly relation suggested by Duff. This indicates that an intrinsic reason for the existence of such a relation should perhaps be, classically, somehow related to the covariance of the form of Einstein's equations.

  8. 658 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 60, NO. 2, APRIL 2013 Design and Simulation of Liquid Krypton

    E-print Network

    Harilal, S. S.

    tines and radiation damage when using present technology gamma ray crystal detectors, NaI(Tl) or solid658 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 60, NO. 2, APRIL 2013 Design and Simulation of Liquid Krypton as Gamma Ray Detector Syed M. Hassan, Ahmed Hassanein, David S. Koltick, Nader Satvat

  9. Hydration of krypton and consideration of clathrate models of hydrophobic effects from the perspective of quasi-chemical theory

    Microsoft Academic Search

    Henry S. Ashbaugh; D. Asthagiri; Lawrence R. Pratt; Susan B. Rempe

    2003-01-01

    Ab initio molecular dynamics (AIMD) results on a krypton–water liquid solution are presented and compared to recent XAFS results for the radial hydration structure for a Kr atom in liquid water solution. Though these AIMD calculations have important limitations of scale, the comparisons with the liquid solution results are satisfactory and significantly different from the radial distributions extracted from the

  10. 10 CFR 32.22 - Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...manufacture, process, or produce self-luminous products containing...krypton-85, or promethium-147 in self-luminous products manufactured...storage, use, and disposal of the self-luminous product to demonstrate...iv) Solubility in water and body fluids of the forms of the...

  11. New isotopic clues to solar system formation

    Microsoft Academic Search

    Typhoon Lee

    1979-01-01

    The presence of two new extinct nuclides Al-26 and Pd-107 with half lives of approximately one million years in the early solar system implies that there were nucleosynthetic activities involving a great many elements almost at the instant of solar system formation. Rate gas and oxygen isotopic abundance variations ('anomalies') relative to the 'cosmic' composition were observed in a variety

  12. Gravity Anomaly Simulator

    Microsoft Academic Search

    J. A. F. Gerrard; L. Strickland; A. L. Wade; H. K. Reynolds

    1957-01-01

    An instrument that will simulate the anomalous gravity effects of a subsurface body, having a density differing from that of its surroundings, is described. The device makes use of the similarity between the gravity equation and Lambert's cosine ? law, and enables the geophysicist to synthesize the anomaly producing body in a time much shorter than that required for conventional

  13. The Flyby Anomaly

    Microsoft Academic Search

    Claus Lämmerzahl; Hansjörg Dittus

    2008-01-01

    At various occasions a significant unexplained velocity increase by a few mm\\/s of satellites after an Earth swing-by has been observed what is called the flyby anomaly. We discuss the validity of these observations and discuss general features.

  14. Orbital Anomalies FLORIN DIACU

    E-print Network

    Diacu, Florin

    other parameters beyond gravita- tion, such as magnetic effects and solar wind. To know the exact they understand gravity at all. The Pioneer Anomaly On March 2, 1972, Pioneer 10 was launched from Cape Canaveral cosmic rays, magnetic fields, solar wind, neutral hydrogen, dust particles; the Jovian aurorae, radio

  15. Anomaly detection for diagnosis

    Microsoft Academic Search

    Roy A. Maxion

    1990-01-01

    The author presents a method for detecting anomalous events in communication networks and other similarly characterized environments in which performance anomalies are indicative of failure. The methodology, based on automatically learning the difference between normal and abnormal behavior, has been implemented as part of an automated diagnosis system from which performance results are drawn and presented. The dynamic nature of

  16. Anomaly detection: A survey

    Microsoft Academic Search

    Varun Chandola; Arindam Banerjee; Vipin Kumar

    2009-01-01

    to difierentiate between normal and anomalous behavior. When applying a given technique to a particular domain, these assumptions can be used as guidelines to assess the efiectiveness of the technique in that domain. For each category, we provide a basic anomaly detection technique, and then show how the difierent existing techniques in that category are variants of the basic tech-

  17. A Principled Anomalies as

    E-print Network

    Wang, Xiaorui "Ray"

    Erik M. Ferragut (ferragutem@ornl.gov) Jason Laska (laskaja@ornl.gov) Robert A. Bridges (bridgesra@ornl Application Conclusion Cyber Operational Challenge Question. How can intrusions be detected in an enterprise as Rare Events Anomaly Definition Main Theorem Application Conclusion Cyber Data and Requirements Cyber

  18. Congenital Vascular Anomalies.

    PubMed

    Gravereaux, Edwin C.; Nguyen, Louis L.; Cunningham, Leslie D.

    2004-04-01

    Congenital vascular anomalies are rare. The cardiovascular specialist should nevertheless be aware of the more common types of vascular anomalies and understand the implications for patient treatment and the likelihood of associated morbidity. The presentation of congenital arteriovenous malformations can range from asymptomatic or cosmetic lesions, to those causing ischemia, ulceration, hemorrhage, or high-output congestive heart failure. Treatment of large, symptomatic arteriovenous malformations often requires catheter-directed embolization prior to the attempt at complete surgical excision. Later recurrence, due to collateral recruitment, is frequent. Graded compression stockings and leg elevation are the mainstays of treatment for the predominantly venous congenital vascular anomalies. Most congenital central venous disorders are clinically silent. An exception is the retrocaval ureter. Retroaortic left renal vein, circumaortic venous ring, and absent, left-sided or duplicated inferior vena cava are relevant when aortic or inferior vena cava procedures are planned. The treatment of the venous disorders is directed at prevention or management of symptoms. Persistent sciatic artery, popliteal entrapment syndrome, and aberrant right subclavian artery origin are congenital anomalies that are typically symptomatic at presentation. Because they mimic more common diseases, diagnosis is frequently delayed. Delay can result in significant morbidity for the patient. Failure to make the diagnosis of persistent sciatic artery and popliteal entrapment can result in critical limb ischemia and subsequent amputation. Unrecognized aberrant right subclavian artery origin associated with aneurysmal degeneration can rupture and result in death. The treatment options for large-vessel arterial anomalies are surgical, sometimes in combination with endovascular techniques. PMID:15066242

  19. Anomaly-safe discrete groups

    NASA Astrophysics Data System (ADS)

    Chen, Mu-Chun; Fallbacher, Maximilian; Ratz, Michael; Trautner, Andreas; Vaudrevange, Patrick K. S.

    2015-07-01

    We show that there is a class of finite groups, the so-called perfect groups, which cannot exhibit anomalies. This implies that all non-Abelian finite simple groups are anomaly-free. On the other hand, non-perfect groups generically suffer from anomalies. We present two different ways that allow one to understand these statements.

  20. Global Climate Highlights and Anomalies

    NSDL National Science Digital Library

    NOAA's Global Climate Highlights and Anomalies page offers weekly summaries of global climate highlights and anomalies (warm, cold, wet, dry). Areas experiencing climate anomalies are color-marked on a global map, followed by written summaries of each region's climate conditions. All weeks are posted for the year 2000 (to present), and a link points users to the complete 1999 archive.

  1. Vascular Anomalies and Airway Concerns

    PubMed Central

    Clarke, Caroline; Lee, Edward I.; Edmonds, Joseph

    2014-01-01

    Vascular anomalies, both tumors and malformations, can occur anywhere in the body, including the airway, often without any external manifestations. However, vascular anomalies involving the airway deserve special consideration as proper recognition and management can be lifesaving. In this article, the authors discuss vascular anomalies as they pertains to the airway, focusing on proper diagnosis, diagnostic modalities, and therapeutic options. PMID:25045336

  2. Statistical analysis of the electrical breakdown time delay distributions in krypton

    SciTech Connect

    Maluckov, Cedomir A.; Karamarkovic, Jugoslav P.; Radovic, Miodrag K.; Pejovic, Momcilo M. [Technical Faculty in Bor, University of Belgrade, Vojske Jugoslavije 24, 19210 Bor (Serbia and Montenegro); Faculty of Civil Engineering and Architecture, University of Nis, Beogradska 14, 18000 Nis (Serbia and Montenegro); Faculty of Sciences and Mathematics, University of Nis, P.O. Box 224, 18001 Nis (Serbia and Montenegro); Faculty of Electronic Engineering, University of Nis, P.O. Box 73, 18001 Nis (Serbia and Montenegro)

    2006-08-15

    The statistical analysis of the experimentally observed electrical breakdown time delay distributions in the krypton-filled diode tube at 2.6 mbar is presented. The experimental distributions are obtained on the basis of 1000 successive and independent measurements. The theoretical electrical breakdown time delay distribution is evaluated as the convolution of the statistical time delay with exponential, and discharge formative time with Gaussian distribution. The distribution parameters are estimated by the stochastic modelling of the time delay distributions, and by comparing them with the experimental distributions for different relaxation times, voltages, and intensities of UV radiation. The transition of distribution shapes, from Gaussian-type to the exponential-like, is investigated by calculating the corresponding skewness and excess kurtosis parameters. It is shown that the mathematical model based on the convolution of two random variable distributions describes experimentally obtained time delay distributions and the separation of the total breakdown time delay to the statistical and formative time delay.

  3. Double shock front formation in cylindrical radiative blast waves produced by laser irradiation of krypton gas

    SciTech Connect

    Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T. [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)] [Center for High Energy Density Science, Department of Physics, The University of Texas at Austin, C1510, Austin, Texas 78712 (United States)

    2013-12-15

    Radiative blast waves were created by irradiating a krypton cluster source from a supersonic jet with a high intensity femtosecond laser pulse. It was found that the radiation from the shock surface is absorbed in the optically thick upstream medium creating a radiative heat wave that travels supersonically ahead of the main shock. As the blast wave propagates into the heated medium, it slows and loses energy, and the radiative heat wave also slows down. When the radiative heat wave slows down to the transonic regime, a secondary shock in the ionization precursor is produced. This paper presents experimental data characterizing both the initial and secondary shocks and numerical simulations to analyze the double-shock dynamics.

  4. Computation of thermodynamic and transport properties to predict thermophoretic effects in an argon-krypton mixture

    NASA Astrophysics Data System (ADS)

    Miller, Nicholas A. T.; Daivis, Peter J.; Snook, Ian K.; Todd, B. D.

    2013-10-01

    Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures.

  5. Computational modeling of Krypton gas puffs with tailored mass density profiles on Za)

    NASA Astrophysics Data System (ADS)

    Jennings, C. A.; Ampleford, D. J.; Lamppa, D. C.; Hansen, S. B.; Jones, B.; Harvey-Thompson, A. J.; Jobe, M.; Strizic, T.; Reneker, J.; Rochau, G. A.; Cuneo, M. E.

    2015-05-01

    Large diameter multi-shell gas puffs rapidly imploded by high current (˜20 MA, ˜100 ns) on the Z generator of Sandia National Laboratories are able to produce high-intensity Krypton K-shell emission at ˜13 keV. Efficiently radiating at these high photon energies is a significant challenge which requires the careful design and optimization of the gas distribution. To facilitate this, we hydrodynamically model the gas flow out of the nozzle and then model its implosion using a 3-dimensional resistive, radiative MHD code (GORGON). This approach enables us to iterate between modeling the implosion and gas flow from the nozzle to optimize radiative output from this combined system. Guided by our implosion calculations, we have designed gas profiles that help mitigate disruption from Magneto-Rayleigh-Taylor implosion instabilities, while preserving sufficient kinetic energy to thermalize to the high temperatures required for K-shell emission.

  6. Broadband low-density radiation source utilising argon, krypton, and xenon chlorides

    SciTech Connect

    Shuaibov, Aleksandr K; Dashchenko, Arkadii I; Shevera, Igor V [Uzhgorod National University, Uzhgorod (Ukraine)

    2002-03-31

    The parameters of a broadband excimer radiation source emitting in the 175-310-nm range and excited by a dc glow discharge in an Ar-Kr-Xe-Cl{sub 2} mixture are studied. The emission spectrum of the discharge consists of the ArCl, KrCl, XeCl, and Cl{sub 2} molecular emission bands. The optimal partial pressure of argon in the mixture is 1.3 kPa, those of krypton and xenon are 0.24 kPa each, and the partial chlorine pressure is in the 0.15-0.30-kPa range. The UV-VUV radiation power emitted from the entire side surface of the discharge tube amounts to 4-6 W for an efficiency of 15%-25%. The radiation source is of interest for applications in photometry, microelectronics, photochemistry, and medicine. (nonlinear optical phenomena)

  7. Solar-wind krypton and solid/gas fractionation in the early solar nebula

    SciTech Connect

    Wiens, R.C.; Burnett, D.S.; Neugebauer, M. (California Inst. of Tech., Pasadena (USA)); Pepin, R.O. (Univ. of Minnesota, Minneapolis (USA))

    1991-02-01

    Krypton is the best candidate for determining limits on solid/gas fractionation in the early sun because of the smoothness of the odd-mass abundance curve in its mass region, which permits relatively precise interpolations of its abundance assuming no fractionation. Here the authors calculate the solar-system Kr abundance from solar-wind noble-gas ratios, determined previously by low-temperature oxidations of lunar ilmenite grains, normalized to Si by spacecraft solar-wind measurements. The estimated {sup 83}Kr abundance of 4.1 {plus minus} 1.5 per 10{sup 6} Si atoms is within uncertainty of estimates assuming no fractionation, determined from DI-chondrite abundances of surrounding elements. This is significant because it is the first such constraint on solid/gas fractionation, though the large uncertainty only confines it to somewhat less than a factor of two.

  8. Phase behavior of mixed submonolayer films of krypton and xenon on graphite.

    PubMed

    Patrykiejew, A; Soko?owski, S

    2012-04-14

    Using the results of extensive Monte Carlo simulations in the canonical and grand canonical ensembles, we discuss the phase behavior of mixed submonolayer films of krypton and xenon adsorbed on the graphite basal plane. The calculations have been performed using two- and three-dimensional models of the systems studied. It has been demonstrated that out-of-plane motion does not affect the properties of the films as long as the total density is well below the monolayer completion and at moderate temperatures. For the total densities close to the monolayer completion, the promotion of particles to the second layer considerably affects the film properties. Our results are in a reasonable agreement with the available experimental data. The melting point of submonolayer films has been shown to exhibit non-monotonous changes with the film composition, and reaches minimum for the xenon concentration of about 50%. At the temperatures below the melting point, the structure of solid phases depends upon the film composition and the temperature; one can also distinguish commensurate and incommensurate phases. Two-dimensional calculations have demonstrated that for the xenon concentration between about 15% and 65% the adsorbed film exhibits the formation of a superstructure, in which each Xe atom is surrounded by six Kr atoms. This superstructure is stable only at very low temperatures and transforms into the mixed commensurate (?3×?3)R30° phase upon the increase of temperature. Such a superstructure does not appear when a three-dimensional model is used. Grand canonical ensemble calculations allowed us to show that for the xenon concentration of about 3% the phase diagram topology of monolayer films changes from the krypton-like (with incipient triple point) to the xenon-like (with ordinary triple point). PMID:22502538

  9. Anomaly mediated supersymmetry breaking

    SciTech Connect

    Alwis, S. P. de [Physics Department, University of Colorado, Boulder, Colorado 80309 (United States)

    2008-05-15

    A discrepancy between the anomaly mediated supersymmetry breaking (AMSB) gaugino mass calculated from the work of Kaplunovsky and Louis (hep-th/9402005) (KL) and other calculations in the literature is explained, and it is argued that the KL expression is the correct one relevant to the Wilsonian action. Furthermore it is argued that the AMSB contribution to the squark and slepton masses should be replaced by the contribution pointed out by Dine and Seiberg (DS) which has nothing to do with Weyl anomalies. This is not in general equivalent to the AMSB expression, and it is shown that there are models in which the usual AMSB expression would vanish but the DS one is nonzero. In fact the latter has aspects of both AMSB and gauge mediated supersymmetry (SUSY) breaking. In particular like the latter, it gives positive squared masses for sleptons.

  10. Mass Anomalies on Ganymede

    NASA Technical Reports Server (NTRS)

    Schubert, G.; Anderson, J. D.; Jacobson, R. A.; Lau, E. L.; Moore, W. B.; Palguta, J.

    2004-01-01

    Radio Doppler data from two Ganymede encounters (G1 and G2) on the first two orbits in the Galileo mission have been analyzed previously for gravity information . For a satellite in hydrostatic equilibrium, its gravitational field can be modeled adequately by a truncated spherical harmonic series of degree two. However, a fourth degree field is required in order to fit the second Galileo flyby (G2). This need for a higher degree field strongly suggests that Ganymede s gravitational field is perturbed by a gravity anomaly near the G2 closest approach point (79.29 latitude, 123.68 west longitude). In fact, a plot of the Doppler residuals , after removal of the best-fit model for the zero degree term (GM) and the second degree moments (J2 and C22), suggests that if an anomaly exists, it is located downtrack of the closest approach point, closer to the equator.

  11. Yukawa Textures and Anomalies

    E-print Network

    Pierre Binetruy; Pierre Ramond

    1994-12-29

    We augment the Minimal Supersymmetric Standard Model with a gauged family-dependent $U(1)$ to reproduce Yukawa textures compatible with experiment. In the simplest model with one extra chiral electroweak singlet field, acceptable textures require this $U(1)$ to be anomalous. The cancellation of its anomalies by a generic Green-Schwarz mechanism requires $\\sin^2\\theta_w=3/8$ at the string scale, suggesting a superstring origin for the standard model.

  12. Yearly Arctic Temperature Anomaly

    NSDL National Science Digital Library

    Cindy Starr

    2003-10-23

    This animation shows the yearly temperature anomaly over the Arctic region from 1981-82 through 2002-03. Years run from August 1 through July 31. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -7.0 to +7.0 degrees Celsius in increments of .25 degrees. (See color bar below)

  13. Anomaly for Model Building

    E-print Network

    Utpal Sarkar

    2006-06-19

    A simple algorithm to calculate the group theory factor entering in anomalies at four and six dimensions for SU(N) and SO(N) groups in terms of the Casimir invariants of their subgroups is presented. Explicit examples of some of the lower dimensional representations of $SU(n), n \\leq 5$ and SO(10) groups are presented, which could be used for model building in four and six dimensions.

  14. Pathogenesis of Vascular Anomalies

    PubMed Central

    Boon, Laurence M.; Ballieux, Fanny; Vikkula, Miikka

    2010-01-01

    Vascular anomalies are localized defects of vascular development. Most of them occur sporadically, i.e. there is no familial history of lesions, yet in a few cases clear inheritance is observed. These inherited forms are often characterized by multifocal lesions that are mainly small in size and increase in number with patient’s age. On the basis of these inherited forms, molecular genetic studies have unraveled a number of inherited mutations giving direct insight into the pathophysiological cause and the molecular pathways that are implicated. Genetic defects have been identified for hereditary haemorrhagic telangiectasia (HHT), inherited cutaneomucosal venous malformation (VMCM), glomuvenous malformation (GVM), capillary malformation - arteriovenous malformation (CM-AVM), cerebral cavernous malformation (CCM) and some isolated and syndromic forms of primary lymphedema. We focus on these disorders, the implicated mutated genes and the underlying pathogenic mechanisms. We also call attention to the concept of Knudson’s double-hit mechanism to explain incomplete penetrance and the large clinical variation in expressivity of inherited vascular anomalies. This variability renders the making of correct diagnosis of the rare inherited forms difficult. Yet, the identification of the pathophysiological causes and pathways involved in them has had an unprecedented impact on our thinking of their etiopathogenesis, and has opened the doors towards a more refined classification of vascular anomalies. It has also made it possible to develop animal models that can be tested for specific molecular therapies, aimed at alleviating the dysfunctions caused by the aberrant genes and proteins. PMID:21095468

  15. Shape evolution in yttrium and niobium neutron-rich isotopes

    SciTech Connect

    Rodriguez-Guzman, R.; Sarriguren, P. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 123, E-28006 Madrid (Spain); Robledo, L. M. [Departamento de Fisica Teorica, Modulo 15, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)

    2011-04-15

    The isotopic evolution of the ground-state nuclear shapes and the systematics of one-quasiproton configurations are studied in neutron-rich odd-A yttrium and niobium isotopes. We use a self-consistent Hartree-Fock-Bogoliubov formalism based on the Gogny energy density functional with two parametrizations, D1S and D1M. The equal-filling approximation is used to describe odd-A nuclei preserving both axial and time-reversal symmetries. Shape-transition signatures are identified in the N=60 isotopes in both the charge radii and spin parities of the ground states. These signatures are a common characteristic for nuclei in the whole mass region. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasiproton states. Finally, a global picture of the neutron-rich A{approx}100 mass region from krypton up to molybdenum isotopes is illustrated with the systematics of the nuclear charge radii isotopic shifts.

  16. Organic carbon isotope constraints on the dissolved organic carbon (DOC) reservoir at the Cryogenian–Ediacaran transition

    Microsoft Academic Search

    Ganqing Jiang; Xinqiang Wang; Xiaoying Shi; Shihong Zhang; Shuhai Xiao; Jin Dong

    2010-01-01

    Prominent negative carbonate carbon isotope (?13Ccarb) anomalies from some Ediacaran successions are accompanied by invariant or decoupled organic carbon isotope (?13Corg) values and have been interpreted as resulting from the remineralization of a large dissolved organic carbon (DOC) reservoir capable of buffering carbon isotopes of organic matter. This inferred oceanic DOC reservoir was thought to have initiated with the onset

  17. More Ca and Ti Isotopic Ratios in High-Density, Presolar Graphite Grains from Orgueil

    NASA Astrophysics Data System (ADS)

    Jadhav, M.; Zinner, E.; Amari, S.; Maruoka, T.

    2011-03-01

    We present Ca- and Ti-isotopic data for presolar graphites. Confirming previous conclusions, our results indicate that some 13C-enriched grains that have extremely large Ca and Ti anomalies probably originate from born-again AGB stars.

  18. Lunar and Planetary Science XXXV: Isotopes in Meteorites

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session"Isotopes in Meteorites" consisted of the following presentations:The Common Property of Isotopic Anomalies in Meteorites; Revised Production Rates for 22Na and 54Mn in Meteorites Using Cross Sections Measured for Neutron-induced Reactions; Modeling of 14C and 10Be Production Rates in Meteorites and Lunar Samples; Investigating Xenon Isotopic Fractionation During Rayleigh-type Distillation; The Mean Life Squared Relationship for Abundances of Extinct Radioactivities; and Magnesium Isotopic Fractionation of Forsterite During Evaporation from Different Crystallographic Surfaces.

  19. Performance of a continuous-wave forsterite laser with krypton ion, Ti:sapphire, and Nd:YAG pump lasers

    SciTech Connect

    Carrig, T.J.; Pollock, C.R. [Cornell Univ., Ithaca, NY (United States). School of Electrical Engineering] [Cornell Univ., Ithaca, NY (United States). School of Electrical Engineering

    1993-11-01

    The authors characterize continuous-wave operation of a chromium-doped forsterite (Cr{sup 4+}:Mg{sub 2}SiO{sub 4}) laser using krypton ion, Ti:sapphire, and Nd:YAG lasers as pump sources. Measurements were made pumping at 647 nm and 676 nm with the krypton ion laser, between 690 and 1,010 nm with the Ti:sapphire laser and at 1.06 {mu}m with the Nd:YAG laser. Threshold pump powers and slope efficiencies are compared for output coupler transmissions varying between 1 and 15.5%. Room temperature operation was only achieved using the Nd:YAG pump laser. Forsterite laser output power as a function of both temperature and pumping wavelength is discussed.

  20. Water: Thermodynamic and Dynamic Anomalies

    SciTech Connect

    Barbosa, Marcia C. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil)

    2009-04-19

    While the majority of fluids contract upon cooling, water expands when cooled below T = 4 deg. C at atmospheric pressure. This effect is called density anomaly. Besides the density anomaly, there are more than 60 other anomalies known for water. Diffusivity is one of them. For normal liquids the diffusion coefficient decreases under compression. However, experimental results have shown that for water at temperatures below approximately 10 deg. C, the diffusion coefficient increases under compression and has a maximum. The temperature of maximum density line, inside which the density anomaly occurs, and the line of maximum in diffusivity are located in the same region of the pressure-temperature phase diagram of water. We show how simulations for water also show thermodynamic and dynamic anomalies. These anomalies are then demonstrated to be related to two length scales effective potential.

  1. Monitoring of kratom or Krypton intake in urine using GC-MS in clinical and forensic toxicology.

    PubMed

    Philipp, Anika A; Meyer, Markus R; Wissenbach, Dirk K; Weber, Armin A; Zoerntlein, Siegfried W; Zweipfenning, Peter G M; Maurer, Hans H

    2011-04-01

    The Thai medicinal plant Mitragyna speciosa (kratom) is misused as a herbal drug. Besides this, a new herbal blend has appeared on the drugs of abuse market, named Krypton, a mixture of O-demethyltramadol (ODT) and kratom. Therefore, urine drug screenings should include ODT and focus on the metabolites of the kratom alkaloids mitragynine (MG), paynantheine (PAY), speciogynine (SG), and speciociliatine (SC). The aim of this study was to develop a full-scan gas chromatography-mass spectrometry procedure for monitoring kratom or Krypton intake in urine after enzymatic cleavage of conjugates, solid-phase extraction, and trimethylsilylation. With use of reconstructed mass chromatography with the ions m/z 271, 286, 329, 344, 470, 526, 528, and 586, the presence of MG, 16-carboxy-MG, 9-O-demethyl-MG, and/or 9-O-demethyl-16-carboxy-MG could be indicated, and in case of Krypton, with m/z 58, 84, 116, 142, 303, 361, 393, and 451, the additional presence of ODT and its nor metabolite could be indicated. Compounds were identified by comparison with their respective reference spectra. Depending on the plant type, dose, administration route, and/or sampling time, further metabolites of MG, PAY, SG, and SC could be detected. The limits of detection (signal-to-noise ratio of 3) were 100 ng/ml for the parent alkaloids and 50 ng/ml for ODT. As mainly metabolites of the kratom alkaloids were detected in urine, the detectability of kratom was tested successfully using rat urine after administration of a common user's dose of MG. As the metabolism in humans was similar, this procedure should be suitable to prove an intake of kratom or Krypton. PMID:21153588

  2. Monitoring of kratom or Krypton intake in urine using GC-MS in clinical and forensic toxicology

    Microsoft Academic Search

    Anika A. Philipp; Markus R. Meyer; Dirk K. Wissenbach; Armin A. Weber; Siegfried W. Zoerntlein; Peter G. M. Zweipfenning; Hans H. Maurer

    2011-01-01

    The Thai medicinal plant Mitragyna speciosa (kratom) is misused as a herbal drug. Besides this, a new herbal blend has appeared on the drugs of abuse market, named Krypton,\\u000a a mixture of O-demethyltramadol (ODT) and kratom. Therefore, urine drug screenings should include ODT and focus on the metabolites of the kratom alkaloids mitragynine (MG), paynantheine (PAY), speciogynine (SG), and speciociliatine

  3. Radiative Lifetimes of the 1S0 Metastable States of Doubly-Ionized Krypton and Doubly-Ionized Xenon

    Microsoft Academic Search

    Robert Anton Walch

    1988-01-01

    Measurements have been made of the radiative lifetimes of the ^1S_0 excited electronic states in doubly-ionized krypton and xenon. In each case, the radiative transition from the state is magnetic dipole (M1). These states, known as metastable states, possess long lifetimes that are difficult to determine for ionic species since ions react very quickly with their surroundings, undergoing de-excitation or

  4. Probing the Isotopic Composition of Surface Waters Across Isotopic Extremes of Cryogenian Carbonates

    NASA Astrophysics Data System (ADS)

    Bosak, T.; Matys, E. D.; Bird, L. R.; Macdonald, F. A.; Freeman, K. H.

    2012-12-01

    Neoproterozoic carbonate strata record unusually large and positive carbon isotope values (?13Ccarb from 4 to 10 per mil), and stratigraphically extensive large negative carbon isotope excursions (?13Ccarb < -5 per mil). Mechanisms that account for the magnitude, the facies distribution and the global abundance of these isotopically extreme carbonates in Neoproterozoic successions remain poorly understood. Little is also known about organisms and metabolisms that cycled carbon in these carbonate strata, because they rarely contain well-preserved organic-rich fossils. To better understand the cycling of carbon during the deposition of the 715-635 Ma Tayshir member of the Tsagaan Oloom Formation, Mongolia, we analyzed ?13Cfossil of two types of organic fossils that occur in 13C- enriched carbonates (+ 5 to 9.9 per mil) and within 13C-depleted carbonates of the Tayshir anomaly (-3 to -6 per mil). Because these organic microfossils are remarkably similar to the tests of modern planktonic, herbivorous tintinnid ciliates and benthic macroscopic red algae, respectively, they can be used as tracers of organic matter production in surface waters. Fossil tests were extracted by acid maceration, cleaned and analyzed morphologically and microscopically. Their carbon isotopic composition was measured using a nano-scaled elemental analyzer inlet (nano-EA-IRMS), with ±1 per mil analytical precision. To date, we analyzed 12 samples of 100-150 organic tests, representing 3 different fossiliferous parts of the Tayshir anomaly (?13Ccarb < -3 per mil) and 3 different strata predating the Tayshir anomaly (?13Ccarb > +5 per mil), respectively. More samples, including those of fossil algae and tests from the carbonate strata overlying the Tayshir anomaly, are currently being analyzed. Initial data reveal a rather constant isotopic composition of organic carbon in fossil tests (?13Cfossil), with values of -23 ±1 per mil both within 13C-enriched and 13C-depleted carbonates. The isotopic difference between ?13Cfossil and 13C-enriched carbonates is 28 to 30 per mil, suggesting maximal isotopic fractionation by primary producers, and little environmental (or diagenetic) processing of primary photosynthetic carbon. The carbonates of the Tayshir anomaly preserve two organic materials: matrix or bulk carbon characterized by a ?13Corg that covaries with ?13Ccarb, and a small, but morphologically diagnostic component whose ?13Cfossil values do not covary with ?13Ccarb. The stratigraphic thickness (~ 50 m) and isotopic heterogeneity of the organic matter within the Tayshir anomaly (~ 50 m) suggest a prolonged and large contribution of organic carbon remineralization.

  5. Vena Caval Anomalies

    PubMed Central

    Rajakulasingam, Ramyah; Francis, Rohin; Rajakulasingam, Ramanan

    2013-01-01

    Anomalous vena cavae can have significant implications for procedures on the right side of the heart. We report a rare anatomical configuration in a 44-year-old female, which to the best of our knowledge, is the first report of such an association. She had a bicuspid aortic valve in conjunction with a persistent left superior vena cava (PLSVC) draining into the coronary sinus, and a left-sided inferior vena cava (IVC) draining into a left superior vena cava via the hemiazygos vein. Comprehensive assessment of these anomalies is crucial given the widespread use of invasive cardiac procedures. PMID:24404410

  6. Investigating the Reactor Antineutrino Anomaly with Beta Spectroscopy

    NASA Astrophysics Data System (ADS)

    Padgett, Stephen; Scielzo, Nick; Keefer, Greg; Bowden, Nathaniel; Savard, Guy; Clark, Jason; Perez Galvan, Adrian; Caldwell, Shane; Czeszumska, Agnieszka; Yee, Ryan; Norman, Eric

    2014-09-01

    The Reactor Antineutrino Anomaly is a discrepancy between the expected flux of antineutrinos from nuclear reactors and the detected flux. This anomaly is often explained by either the existence of a fourth, sterile neutrino or by incorrect calculations of the predicted number of reactor antineutrinos. Calculations of the expected flux assume that all the fission product ? decays have spectral shapes that are nearly identical to the allowed shape. However, many of the highest energy transitions are first forbidden and may have a different spectral shape, which could alter the predicted antineutrino flux and explain the anomaly. We will perform measurements of the shapes of ? decay spectra on the isotopes that have the biggest impact on the Reactor Antineutrino Anomaly. Those nuclei, starting with 92Rb, will be produced at the CARIBU facility at Argonne National Laboratory and the ? spectra will be measured in plastic scintillators. The energy response of the plastic scintillators will be calibrated by studying the allowed ? decay of 8Li. The Reactor Antineutrino Anomaly is a discrepancy between the expected flux of antineutrinos from nuclear reactors and the detected flux. This anomaly is often explained by either the existence of a fourth, sterile neutrino or by incorrect calculations of the predicted number of reactor antineutrinos. Calculations of the expected flux assume that all the fission product ? decays have spectral shapes that are nearly identical to the allowed shape. However, many of the highest energy transitions are first forbidden and may have a different spectral shape, which could alter the predicted antineutrino flux and explain the anomaly. We will perform measurements of the shapes of ? decay spectra on the isotopes that have the biggest impact on the Reactor Antineutrino Anomaly. Those nuclei, starting with 92Rb, will be produced at the CARIBU facility at Argonne National Laboratory and the ? spectra will be measured in plastic scintillators. The energy response of the plastic scintillators will be calibrated by studying the allowed ? decay of 8Li. This work was supported by U.S. DOE under Contracts DE-AC52-07NA27344 (LLNL), DE-AC02-06CH11357 (ANL) and a Laboratory Directed Research and Development grant at LLNL (14-LW-087).

  7. Lunar Orbit Anomaly

    NASA Astrophysics Data System (ADS)

    Riofrio, L.

    2012-12-01

    Independent experiments show a large anomaly in measurements of lunar orbital evolution, with applications to cosmology and the speed of light. The Moon has long been known to be slowly drifting farther from Earth due to tidal forces. The Lunar Laser Ranging Experiment (LLRE) indicates the Moon's semimajor axis increasing at 3.82 ± .07 cm/yr, anomalously high. If the Moon were today gaining angular momentum at this rate, it would have coincided with Earth less than 2 Gyr ago. Study of tidal rhythmites indicates a rate of 2.9 ± 0.6 cm/yr. Historical eclipse observations independently measure a recession rate of 2.82 ± .08 cm/yr. Detailed numerical simulation of lunar orbital evolution predicts 2.91 cm/yr. LLRE differs from three independent experiments by over12 sigma. A cosmology where speed of light c is related to time t by GM=tc^3 has been suggested to predict the redshifts of Type Ia supernovae, and a 4.507034% proportion of baryonic matter. If c were changing in the amount predicted, lunar orbital distance would appear to increase by an additional 0.935 cm/yr. An anomaly in the lunar orbit may be precisely calculated, shedding light on puzzles of 'dark energy'. In Planck units this cosmology may be summarized as M=R=t.Lunar Recession Rate;

  8. Ce isotope abundance in chondritic and HED meteorites

    NASA Astrophysics Data System (ADS)

    Lee, S.; Asahara, Y.; Tanaka, T.; Lee, S. R.

    2011-12-01

    138La, 136Ce and 138Ce are p-process nuclides, and their isotopic abundances are generally low due to their modes of nucleosynthesis compared with other isotopes of La and Ce (139La, 140Ce and 142Ce). Tanimizu et al. (2004) mentioned that, using the 140Ce/142Ce ratio as the normalizing value, 136Ce isotope abundance could be acted as an indicator of p-process nuclide anomaly for extra-terrestrial materials to understand the nucleosynthetic origins of solar system matter. Then, meteoritic primordial composition of Ce isotope provides useful information related with 138La decay system. Especially, combined Ce/Nd isotope data in geological and cosmological materials enable us the modeling of the light REE profiles of the source material. We measured Ce isotope ratio for fifteen meteorites, using 140Ce/142Ce=7.941 as the normalizing value, in order to compare Ce isotope abundance between chondritic and HED meteorites. Of them, Ce isotope abundances from two chondritic meteorites were deviated from the average abundances of other 13 meteorites. In this report, we will discuss cosmochemical significance of Ce isotope anomaly.

  9. Transuranium isotopes

    SciTech Connect

    Hoffman, D.C.

    1985-12-01

    The needs of the research community for the production of transuranium isotopes, the quantities required, the continuity of production desired, and what a new steady state neutron source would have to provide to satisfy these needs are discussed. Examples of past frontier research which need these isotopes as well as an outline of the proposed Large Einsteinium Activation Program, LEAP, which requires roughly ten times the current production of /sup 254/Es are given. 15 refs., 5 figs., 4 tabs.

  10. Anomaly, Charge Quantization and Family

    E-print Network

    C. Q. Geng

    2001-01-30

    We first review the three known chiral anomalies in four dimensions and then use the anomaly free conditions to study the uniqueness of quark and lepton representations and charge quantizations in the standard model. We also extend our results to theory with an arbitrary number of color. Finally, we discuss the family problem.

  11. Anomalies in the Solar System

    Microsoft Academic Search

    Hansjoerg Dittus

    2008-01-01

    Several observations show unexplained phenomena in our solar system. These observations are e.g. the Pioneer Anomaly, an unexplained constant acceleration of the Pioneer 10 and 11 spacecraft, the Flyby Anomaly, an unexplained increase of the velocity of a series of spacecraft after Earth gravity assists, the recently reported increase of the Astronomical Unit defined by the distance of the planets

  12. Anomaly detection in IP networks

    Microsoft Academic Search

    Marina Thottan; Chuanyi Ji

    2003-01-01

    Network anomaly detection is a vibrant research area. Researchers have approached this problem using various techniques such as artificial intelligence, machine learning, and state machine modeling. In this paper, we first review these anomaly detection methods and then describe in detail a statistical signal processing technique based on abrupt change detection. We show that this signal processing technique is effective

  13. Graph-based anomaly detection

    Microsoft Academic Search

    Caleb C. Noble; Diane J. Cook

    2003-01-01

    Anomaly detection is an area that has received much attention in recent years. It has a wide variety of applications, including fraud detection and network intrusion detection. A good deal of research has been performed in this area, often using strings or attribute-value data as the medium from which anomalies are to be extracted. Little work, however, has focused on

  14. Chiral anomaly in soft collinear effective theory

    E-print Network

    Waalewijn, Wouter Jonathan

    Anomalies have infrared and ultraviolet ingredients, and are often realized in effective theories in a nontrivial way. We study the chiral anomaly in soft collinear effective theory (SCET), where the anomaly equation has ...

  15. Impact of Sampling on Anomaly Detection

    E-print Network

    Chuah, Chen-Nee

    ? ISPs interested in detecting and stopping anomalous traffic early ­ Additional service to stub networks of Sampling on Anomaly Detection ­ Volume Anomaly Detection ­ Portscan Detection ­ Entropy-based Traffic Profiling Towards Accurate Measurements for Anomaly Detection ­ Filtered Sampling ­ Programmable

  16. Anomaly Detection Approaches for Communication Networks

    E-print Network

    Ji, Chuanyi

    Anomaly Detection Approaches for Communication Networks Marina Thottan, Guanglei Liu, Chuanyi Ji Abstract In recent years network anomaly detection has become an important area for both commercial interests as well as academic research. Applications of anomaly detection typically stem from

  17. Graph-Based Anomaly Detection Bill Eberle

    E-print Network

    Eberle, William

    SIAM Southeastern Sectional Annual Meeting #12;Anomaly Detection Challenge: Insider Threats ScenariosGraph-Based Anomaly Detection Bill Eberle Department of Computer Science Tennessee Tech University or leak sensitive information? March 24, 2013 2 #12;Anomaly Detection Challenge: Fraud Detection

  18. Anomaly detection in clinical processes

    PubMed Central

    Huang, Zhengxing; Lu, Xudong; Duan, Huilong

    2012-01-01

    Meaningful anomalies in clinical processes may be related to caring performance or even the patient survival. It is imperative that the anomalies be timely detected such that useful and actionable knowledge of interest could be extracted to clinicians. Many previous approaches assume prior knowledge about the structure of clinical processes, using which anomalies are detected in a supervised manner. For a majority of clinical settings, however, clinical processes are complex, ad hoc, and even unknown a prior. In this paper, we investigate how to facilitate detection of anomalies in an unsupervised manner. An anomaly detection model is presented by applying a density-based clustering method on patient careflow logs. Using the learned model, it is possible to detect whether a particular patient careflow trace is anomalous with respect to normal traces in the logs. The approach has been validated over real data sets collected from a Chinese hospital. PMID:23304307

  19. Effect of Grain Boundaries on Krypton Segregation Behavior in Irradiated Uranium Dioxide

    SciTech Connect

    Billy Valderrama; Lingfeng He; Hunter B. Henderson; Janne Pakarinen; Brian Jaques; Jian Gan; Darryl P. Butt; Todd R. Allen; Michele V. Manuel

    2015-01-01

    Fission products, such as krypton (Kr), are known to be insoluble within UO2, segregating towards grain boundaries, eventually leading to a lowering of the thermal conductivity and fuel swelling. Recent computational studies have identified that differences in grain boundary structure have a significant effect on the segregation behavior of fission products. However, experimental work supporting these simulations is lacking. Atom probe tomography was used to measure the Kr distribution across grain boundaries in UO2. Polycrystalline depleted-UO2 samples was irradiated with 0.7 and 1.8 MeV Kr-ions and annealed to 1000, 1300, and 1600°C for 1 hour to produce a Kr-bubble dominated microstructure. The results of this work indicate a strong dependence of Kr concentration as a function of grain boundary structure. Temperature also influences grain boundary chemistry with greater Kr concentration evident at higher temperatures, resulting in a reduced Kr concentration in the bulk. While Kr migration is active at elevated temperatures, no changes in grain size or texture were observed in the irradiated samples.

  20. Krypton-79m: a new radionuclide for applications in nuclear medicine

    SciTech Connect

    Myers, W.G.; Dahl, J.R.; Graham, M.C.

    1986-09-01

    Krypton-79m emits 130-keV gamma rays in 27 +/- 1% of its disintegrations and decays with a half-life of 50 +/- 3 sec. It is generated readily by bombarding nearly saturated aqueous solutions of bromide salts, or bromoform, with 14-MeV protons. The 79mKr is swept out continuously as it is produced by bubbling helium upward through the liquids. Up to 200 mCi per I are obtained of the resulting mixture of gases. The 79mKr + helium is mixed with about five volumes of air and then driven continuously through a small-bore tube to an Anger scintillation camera located approximately 200 yards away. The rate of flow is adjusted so that the amounts of 13-sec 81mKr and of 35-hr 79Kr are inconsequential at the time and point of use. When the gases are inhaled, good images of the lungs are obtained with an Anger scintillation camera. The trachea and bronchi commonly are revealed also.

  1. Effects of pulmonary inhalation on hyperpolarized krypton-83 magnetic resonance T1 relaxation

    NASA Astrophysics Data System (ADS)

    Stupic, K. F.; Elkins, N. D.; Pavlovskaya, G. E.; Repine, J. E.; Meersmann, T.

    2011-07-01

    The 83Kr magnetic resonance (MR) relaxation time T1 of krypton gas in contact with model surfaces was previously found to be highly sensitive to surface composition, surface-to-volume ratio, and surface temperature. The work presented here explored aspects of pulmonary 83Kr T1 relaxation measurements in excised lungs from healthy rats using hyperpolarized (hp) 83Kr with approximately 4.4% spin polarization. MR spectroscopy without spatial resolution was applied to the ex vivo lungs that actively inhale hp 83Kr through a custom designed ventilation system. Various inhalation schemes were devised to study the influence of anatomical dead space upon the measured 83Kr T1 relaxation times. The longitudinal 83Kr relaxation times in the distal airways and the respiratory zones were independent of the lung inhalation volume, with T1 = 1.3 s and T1 = 1.0 s, depending only on the applied inhalation scheme. The obtained data were highly reproducible between different specimens. Further, the 83Kr T1 relaxation times in excised lungs were unaffected by the presence of up to 40% oxygen in the hp gas mixture. The results support the possible importance of 83Kr as a biomarker for evaluating lung function.

  2. Effects of Pulmonary Inhalation on Hyperpolarized Krypton-83 Magnetic Resonance T1 Relaxation

    PubMed Central

    Stupic, K.F.; Elkins, N.D.; Pavlovskaya, G.E.; Repine, J.E.; Meersmann, T.

    2011-01-01

    The 83Kr magnetic resonance (MR) relaxation time T1 of krypton gas in contact with model surfaces was previously found to be highly sensitive to surface composition, surface to volume ratio, and surface temperature. The current work explored aspects of pulmonary 83Kr T1 relaxation measurements in excised lungs from healthy rats using hyperpolarized (hp) 83Kr with approximately 4.4 % spin polarization. MR spectroscopy without spatial resolution was applied to the ex vivo lungs that actively inhale hp 83Kr through a custom designed ventilation system. Various inhalation schemes were devised to explore the influence of anatomical dead space upon the measured 83Kr T1 relaxation times. The longitudinal 83Kr relaxation times in the distal airways and the respiratory zones were independent of the lung inhalation volume, with T1 = 1.3 s and T1 = 1.0 s, depending only on the applied inhalation scheme. The obtained data was highly reproducible between different specimens. Further, the 83Kr T1 relaxation times in excised lungs were unaffected by the presence of up to 40% oxygen in the hp gas mixture. The results support the possible importance of 83Kr as a biomarker for evaluating lung function. PMID:21628780

  3. A megajoule class krypton fluoride amplifier for single shot, high gain ICF application

    SciTech Connect

    Rose, E.; Hanson, D.; Krohn, B.; McLeod, J.; Kang, M.

    1988-01-01

    A design study is underway to define the optimal architecture for a KrF laser system which will deliver 10 MJ of 248-nm light to an ICF target. We present one approach which incorporates final power amplifiers in the megajoule class, achieving 10 MJ with four final amplifiers. Each double-pass laser amplifier employs two-sided electron-beam pumping of the laser gas medium. Details of the design are based on a Monte-Carlo electron-beam deposition code, a one-dimensional, time-dependent kinetics code, and pulsed power circuit modeling. Linear dimensions of the amplifier's extracted gain volume are 6.25 m in height and length and 5.12 m in width. Each amplifier handles 160 angularly multiplexed laser channels. The one-amagat, krypton-rich laser medium is e-beam pumped at 60-kW cm/sup /minus/3/ (4-MA at3.3-MV) over the 2-microsecond duration of the laser beam pulse train. 5 refs., 4 figs.

  4. Pulsed power considerations for electron beam pumped krypton fluoride lasers for inertial confinement fusion applications

    SciTech Connect

    Rose, E.A.; McDonald, T.E.; Rosocha, L.A.; Harris, D.B.; Sullivan, J.A. (Los Alamos National Lab., NM (USA)); Smith, I.D. (Pulse Sciences, Inc., San Leandro, CA (USA))

    1991-01-01

    The Los Alamos National Laboratory inertial confinement fusion (ICF) program is developing the krypton-fluoride excimer laser for use as an ICF driver. The KrF laser has a number of inherent characteristics that make it a promising driver candidate, such as short wavelength (0.25 {mu}m), broad bandwidth to target (>100 cm{sup {minus}1}), pulse-shaping with high dynamic range, and the potential for high overall efficiency (>5%) and repetitive operation. The large KrF laser amplifiers needed for ICF drivers are electron-beam pumped. A key issue for all laser ICF drivers is cost, and a leading cost component of a KrF laser driver is associated with the pulsed power and electron diode. Therefore, the efficient generation of electron beams is a high priority. The Los Alamos ICF program is investigating pulsed-power and diode designs and technologies to further the development of affordable KrF laser ICF drivers. 12 refs., 8 figs.

  5. Effect of Grain Boundaries on Krypton Segregation Behavior in Irradiated Uranium Dioxide

    NASA Astrophysics Data System (ADS)

    Valderrama, Billy; He, Lingfeng; Henderson, Hunter B.; Pakarinen, Janne; Jaques, Brian; Gan, Jian; Butt, Darryl P.; Allen, Todd R.; Manuel, Michele V.

    2014-12-01

    Fission products, such as krypton (Kr), are known to be insoluble within UO2, segregating toward grain boundaries and eventually leading to a lowering in thermal conductivity and fuel swelling. Recent computational studies have identified that differences in grain boundary structure have a significant effect on the segregation behavior of fission products. However, experimental work supporting these simulations is lacking. Atom probe tomography was used to measure the Kr distribution across grain boundaries in UO2. Polycrystalline depleted UO2 samples were irradiated with 0.7 MeV and 1.8 MeV Kr-ions and annealed to 1000°C, 1300°C, and 1600°C for 1 h to produce a Kr-bubble dominated microstructure. The results of this work indicate a strong dependence of Kr concentration as a function of grain boundary structure. Temperature also influences grain boundary chemistry with greater Kr concentration evident at higher temperatures, resulting in a reduced Kr concentration in the bulk. Although Kr segregation takes place at elevated temperatures, no change in grain size or texture was observed in the irradiated UO2 samples.

  6. 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

  7. Relationship between positive CE anomaly and adsorbed water in Antarctic lunar meteorites

    Microsoft Academic Search

    Hiroyuki Kagi; Kazuya Takahashi

    1998-01-01

    Concentration of adsorbed water in single mineral grains of Antarctic lunar meteorites was determined with micro IR spectroscopy. A relationship was found between the mineral ability to adsorb water and the extent of Ce anomaly in REE pattern precisely determined by the isotope dilution method using a thermal ionization mass spectrometry. Aska(A)-881757, a lunar meteorite from the mare basalt without

  8. Tracing the ozone isotopic anomaly transferred to other atmospheric

    E-print Network

    Einat, Aharonov

    by oceans Far from pollution sources Strong seasonal variations (Temp, light) Antarctic Ice sheet Ice core 2008 #12;The polar regions: Interests Ocean surrounded by continent Close to pollution sources Strong seasonal variations (Temp, light) Greenland Ice sheet Ice core site Arctic Antarctic Continent surrounded

  9. Coordinated Analysis of Isotopic Anomalies in Antarctic Micrometeorites

    NASA Astrophysics Data System (ADS)

    Haenecour, P.; Floss, C.; Wang, A.; Yada, T.

    2014-06-01

    We carry out coordinated analysis (NanoSIMS 50, Auger Nanoprobe, Raman spectroscopy) of presolar grains (silicates, oxides, SiC) and ^15N-enriched carbonaceous matter in fine-grained Antarctic micrometeorites.

  10. Ni Isotopes in the Early Solar System: an Overview

    Microsoft Academic Search

    G. Quitte; A. N. Halliday; A. Markowski; B. Bourdon; B. Meyer; B. Zanda; C. Latkoczy; D. Guenther

    2006-01-01

    The short-lived 60Fe-60Ni chronometer (t1\\/2=1.49 Myrs) can theoretically provide strong constraints on the exact chronology of the earliest events of the solar system, whereas the mass-dependent isotopic fractionation of Ni stable isotopes helps us to better understand the formation processes of meteorites. Nickel is also an interesting element when looking at nucleosynthetic anomalies and thus stellar sources in a close

  11. Reliability of CHAMP Anomaly Continuations

    NASA Technical Reports Server (NTRS)

    vonFrese, Ralph R. B.; Kim, Hyung Rae; Taylor, Patrick T.; Asgharzadeh, Mohammad F.

    2003-01-01

    CHAMP is recording state-of-the-art magnetic and gravity field observations at altitudes ranging over roughly 300 - 550 km. However, anomaly continuation is severely limited by the non-uniqueness of the process and satellite anomaly errors. Indeed, our numerical anomaly simulations from satellite to airborne altitudes show that effective downward continuations of the CHAMP data are restricted to within approximately 50 km of the observation altitudes while upward continuations can be effective over a somewhat larger altitude range. The great unreliability of downward continuation requires that the satellite geopotential observations must be analyzed at satellite altitudes if the anomaly details are to be exploited most fully. Given current anomaly error levels, joint inversion of satellite and near- surface anomalies is the best approach for implementing satellite geopotential observations for subsurface studies. We demonstrate the power of this approach using a crustal model constrained by joint inversions of near-surface and satellite magnetic and gravity observations for Maude Rise, Antarctica, in the southwestern Indian Ocean. Our modeling suggests that the dominant satellite altitude magnetic anomalies are produced by crustal thickness variations and remanent magnetization of the normal polarity Cretaceous Quiet Zone.

  12. Anomaly mediation from unbroken supergravity

    NASA Astrophysics Data System (ADS)

    D'Eramo, Francesco; Thaler, Jesse; Thomas, Zachary

    2013-09-01

    When supergravity (SUGRA) is spontaneously broken, it is well known that anomaly mediation generates sparticle soft masses proportional to the gravitino mass. Recently, we showed that one-loop anomaly-mediated gaugino masses should be associated with unbroken supersymmetry (SUSY). This counterintuitive result arises because the underlying symmetry structure of (broken) SUGRA in flat space is in fact (unbroken) SUSY in anti-de Sitter (AdS) space. When quantum corrections are regulated in a way that preserves SUGRA, the underlying AdS curvature (proportional to the gravitino mass) necessarily appears in the regulated action, yielding soft masses without corresponding goldstino couplings. In this paper, we extend our analysis of anomaly mediation to sfermion soft masses. Already at tree-level we encounter a number of surprises, including the fact that zero soft masses correspond to broken (AdS) SUSY. At one-loop, we explain how anomaly mediation appears when regulating SUGRA in a way that preserves super-Weyl invariance. We find that recent claims in the literature about the non-existence of anomaly mediation were based on a Wilsonian effective action with residual gauge dependence, and the gauge-invariant 1PI effective action contains the expected anomaly-mediated spectrum. Finally, we calculate the sfermion spectrum to all orders, and use supertrace relations to derive the familiar two-loop soft masses from minimal anomaly mediation, as well as unfamiliar tree-level and one-loop goldstino couplings consistent with renormalization group invariance.

  13. Application of stable isotope techniques to characterize CO2 storage sites

    NASA Astrophysics Data System (ADS)

    Barth, J. A. C.; Becker, V.; Myrttinen, A.; Zimmer, M.; Nowak, M.

    2012-04-01

    Injection of CO2 into the subsurface causes geochemical changes of the water and its dissolved load. It also causes stable isotope alterations of dissolved inorganic carbon (DIC). If CO2 is present in large enough amounts, changes of the water isotope composition can also be expected. Therefore, stable isotope alterations provide additional tools to quantify turnover and interaction of the injected CO2. In a first step, the geochemistry and isotope composition of the undisturbed storage site fluids have to be characterized before injection. This implies careful retrieval of samples from depth in order to avoid pressure changes that might alter the isotope ratios of water or DIC. Reservoir fluids were sampled using an open flow-through sampler ('Doppelkugelbüchse', DKB), or a pressure-sealed Positive Displacement Sampler (PDS) and showed that pressure conservation becomes particularly important after injection of CO2 when pressure gradients between atmosphere and formation become more pronounced. Stable carbon isotope differences between the injected CO2 and the already present DIC helped to establish mass balances. These showed that up to 70 % of DIC after injection may consist of added CO2. Stable isotopes also established its own tracer when batches of injected CO2 had different isotope compositions. For instance, at the Ketzin site, a carbon isotope shift of the DIC of about 2 permille was found a few days after changeover of a gas from a different source with a distinct isotope ratio. This breakthrough coincided well with the ones of other implemented tracers (krypton and sulfurhexafluorid). The combination of stable isotopes and conservative tracers have therefore proven to be suitable tools for identifying different sources of CO2. They also help to trace migration behaviour and spreading of injected CO2 in a storage reservoir.

  14. Isotopic homogeneity of iron in the early solar nebula.

    PubMed

    Zhu, X K; Guo, Y; O'Nions, R K; Young, E D; Ash, R D

    2001-07-19

    The chemical and isotopic homogeneity of the early solar nebula, and the processes producing fractionation during its evolution, are central issues of cosmochemistry. Studies of the relative abundance variations of three or more isotopes of an element can in principle determine if the initial reservoir of material was a homogeneous mixture or if it contained several distinct sources of precursor material. For example, widespread anomalies observed in the oxygen isotopes of meteorites have been interpreted as resulting from the mixing of a solid phase that was enriched in 16O with a gas phase in which 16O was depleted, or as an isotopic 'memory' of Galactic evolution. In either case, these anomalies are regarded as strong evidence that the early solar nebula was not initially homogeneous. Here we present measurements of the relative abundances of three iron isotopes in meteoritic and terrestrial samples. We show that significant variations of iron isotopes exist in both terrestrial and extraterrestrial materials. But when plotted in a three-isotope diagram, all of the data for these Solar System materials fall on a single mass-fractionation line, showing that homogenization of iron isotopes occurred in the solar nebula before both planetesimal accretion and chondrule formation. PMID:11460156

  15. Isotope Science and Production

    E-print Network

    Isotope Science and Production 35 years of experience in isotope production, processing. Contact: Kevin John LANL Isotope Program Manager kjohn@lanl.gov 505-667-3602 Sponsored by the Department of Energy National Isotope Program http://www.nuclear.energy.gov/isotopes/nelsotopes2a.html Isotopes

  16. Gravitational anomaly and transport phenomena.

    PubMed

    Landsteiner, Karl; Megías, Eugenio; Pena-Benitez, Francisco

    2011-07-01

    Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid. PMID:21797593

  17. Feature-based anomaly detection

    NASA Astrophysics Data System (ADS)

    Carlotto, Mark J.

    2007-04-01

    A feature-based approach for detecting anomalies in spectral, spatial, temporal, and other domains is described. When the frequency of occurrence is small relative to the background, anomalies such as man-made objects in natural image backgrounds do not form their own clusters, but are instead assigned the nearest background cluster, becoming an outlier (statistical anomaly) in that cluster. Our method clusters data, which may be spectral, spatial, or temporal in nature, into one or more background types and computes the Mahalanobis distance between the data and assigned model (background cluster). The detection of a variety of objects and phenomena in panchromatic and multispectral imagery, and video are illustrated.

  18. Segregation of isotopes of heavy metals due to light-induced drift: results and problems

    E-print Network

    A. Sapar; A. Aret; R. Poolamäe; L. Sapar

    2007-12-20

    Atutov and Shalagin (1988) proposed light-induced drift (LID) as a physically well understandable mechanism to explain the formation of isotopic anomalies observed in CP stars. We generalized the theory of LID and applied it to diffusion of heavy elements and their isotopes in quiescent atmospheres of CP stars. Diffusional segregation of isotopes of chemical elements is described by the equations of continuity and diffusion velocity. Computations of the evolutionary sequences for abundances of mercury isotopes in several model atmospheres have been made using the Fortran 90 program SMART, composed by the authors. Results confirm predominant role of LID in separation of isotopes.

  19. Studies on the photochemical and thermal dissociation synthesis of krypton difluoride

    SciTech Connect

    Kinkead, S.A.; FitzPatrick, J.R.; Foropoulos, J. Jr.; Kissane, R.J.; Purson, J.D.

    1993-08-01

    Like dioxygen difluoride (O{sub 2}F{sub 2}), KrF{sub 2} can be produced by thermal dissociation or photochemical synthesis from the elements; however, the yields are invariably much less than those obtained for O{sub 2}F{sub 2}. For example, while irradiation of liquid O{sub 2}/F{sub 2} mixtures at {minus}196{degrees}C through a sapphire window with an unfiltered 1,000W uv lamp provides in excess of 3g of O{sub 2}F{sub 2} per hour, the yield of KrF{sub 2} under identical circumstances is approximately 125 mg/hr. In this report, the yield of KrF{sub 2} in quartz and Pyrex{trademark} photochemical reactors has been examined as a function of irradiation wavelength, irradiation power, and Kr: F{sub 2} mole ratio. The uv-visible spectrum of KrF{sub 2} has also been recorded for comparison with earlier work, and the quantum yield for photodissociation at two wavelengths determined. The synthesis of KrF{sub 2} using large thermal gradients has also been examined using resistively heated nickel filaments to thermally dissociate the F{sub 2} in close proximity to liquid nitrogen-cooled metal surfaces. As a net result, KrF{sub 2} has been produced in yields in excess of 1.75 g/hr for extended periods in photochemical systems, and 2.3 g/hr for shorter periods in thermally dissociative reactors. This paper summarizes the results of examining parametrically several different types of reactors for efficiency of producing krypton difluoride.

  20. Analysis of neutral active particle loss in afterglow in krypton at 2.6 mbar pressure

    SciTech Connect

    Pejovic, Momcilo M.; Karamarkovic, Jugoslav P.; Ristic, Goran S.; Pejovic, Milic M. [Faculty of Electronic Engineering, University of Nis, P.O. Box 73, 18001 Nis (Serbia); Faculty of Civil Engineering and Architecture, University of Nis, A. Medvedeva 14, 18001 Nis (Serbia); Faculty of Electronic Engineering, University of Nis, P.O. Box 73, 18001 Nis (Serbia)

    2008-01-15

    This paper presents the analysis of the surface recombination and/or de-excitation of neutral active particles in two different volume krypton-filled tubes at pressure of 2.6 mbar with 1 ppm oxygen impurities. The analysis was performed on the basis of secondary electron emission from the cathode induced by positive ions and neutral active particles using the experimental data of electrical breakdown time delay mean value t{sub d} as a function of afterglow period {tau} ('memory curve'). It was shown that the main channel of neutral active particles' loss in afterglow is their recombination and/or de-excitation on the bulb walls. The loss rate increases with the increase of available wall surface per unit of gas volume. It was also shown that in early afterglow (15 ms for the tube with smaller bulb volume and 30 ms for the tube with bigger bulb volume) positive ions are formed in the mutual collisions of neutral active particles, and these ions dominantly influence the secondary electron emission from the cathode. In late afterglow (to 30 s for the tube with smaller bulb volume and to 150 s for the tube with bigger bulb volume) neutral active particles have dominant role in secondary electron emission from the cathode. The probability for this process decreases with the increase of afterglow period as a consequence of the decrease of the concentration of neutral active particles in gas, and this probability is smaller for the tube with smaller bulb volume. The influence of additional electron yield in the electrode gap caused by gamma radiation on breakdown initiation is also analyzed. It is shown that the influence of the neutral active particles in the process of secondary electron emission in the case of gamma radiation is also significant in both early and late afterglow.

  1. Dielectronic recombination and resonant transfer excitation processes for helium-like krypton

    NASA Astrophysics Data System (ADS)

    Hu, Xiao-Li; Qu, Yi-Zhi; Zhang, Song-Bin; Zhang, Yu

    2012-10-01

    The relativistic configuration interaction method is employed to calculate the dielectronic recombination (DR) cross sections of helium-like krypton via the 1s2lnl' (n = 2, 3, ..., 15) resonances. Then, the resonant transfer excitation (RTE) processes of Kr34+ colliding with H, He, H2, and CHx (x = 0-4) targets are investigated under the impulse approximation. The needed Compton profiles of targets are obtained from the Hartree—Fock wave functions. The RTE cross sections are strongly dependent on DR resonant energies and strengths, and the electron momentum distributions of the target. For H2 and H targets, the ratio of their RTE cross sections changes from 1.85 for the 1s2l2l' to 1.88 for other resonances, which demonstrates the weak molecular effects on the Compton profiles of H2. For CHx (x = 0-4) targets, the main contribution to the RTE cross section comes from the carbon atom since carbon carries 6 electrons; as the number of hydrogen increases in CHx, the RTE cross section almost increases by the same value, displaying the strong separate atom character for the hydrogen. However, further comparison of the individual orbital contributions of C(2p, 2s, 1s) and CH4(1t2, 2a1, 1a1) to the RTE cross sections shows that the molecular effects induce differences of about 25.1%, 19.9%, and 0.2% between 2p-1t2, 2s-2a1, and 1s-1a1 orbitals, respectively.

  2. Molecular ion formation in decaying plasmas produced in pure argon and krypton

    NASA Astrophysics Data System (ADS)

    Grössl, M.; Langenwalter, M.; Helm, H.; Märk, T. D.

    1981-02-01

    The formation of molecular ions Ar2+ and Kr2+ in decaying plasmas of the respective rare gases is studied at pressures between 0.2 and 3 Torr at room temperature. Measurements of the decay of He2+ in He are made to test the experimental technique used. The reaction rate coefficient for the process Ar+(2P3/2)+2 Ar?Ar2++Ar is found to be (2.35±0.2)×10-31 cm6 s-1. The corresponding reaction rate coefficient in krypton is found to be (2.2±0.2)×10-31 cm6 s-1. Using a recently proposed reaction model [Helm and Varney (1978)] for the excited fine structure state (2P1/2), the pressure dependence of the reaction rate coefficient describing the destruction Ar+(2P1/2)+2Ar?products is calculated. The pressure dependence and magnitude of the coefficient found are in agreement with the experimental findings of Liu and Conway (1975) for the above process. The process could not be studied experimentally in our system due to the low density of Ar+(2P1/2) in our discharge. The low density is inferred indirectly and the process responsible for the fast removal of the excited ion species in the argon plasma is regarded to be the superelastic collision process with slow plasma electrons Ar+(2P1/2)+e?Ar+(2P3/2)+e+0.18 eV for which a rate coefficient ?10-7 cm3 s-1 is estimated. At late times in the afterglow a significant source of ionization is observed in argon. This source is consistent with ionizing collisions of metastable argon atoms. Its importance increased with pressure since the diffusive loss of metastable atoms becomes insignificant as the pressure is raised.

  3. Classifying sex biased congenital anomalies

    SciTech Connect

    Lubinsky, M.S. [Medical College of Wisconsin and Children`s Hospital, Milwaukee, WI (United States)] [Medical College of Wisconsin and Children`s Hospital, Milwaukee, WI (United States)

    1997-03-31

    The reasons for sex biases in congenital anomalies that arise before structural or hormonal dimorphisms are established has long been unclear. A review of such disorders shows that patterning and tissue anomalies are female biased, and structural findings are more common in males. This suggests different gender dependent susceptibilities to developmental disturbances, with female vulnerabilities focused on early blastogenesis/determination, while males are more likely to involve later organogenesis/morphogenesis. A dual origin for some anomalies explains paradoxical reductions of sex biases with greater severity (i.e., multiple rather than single malformations), presumably as more severe events increase the involvement of an otherwise minor process with opposite biases to those of the primary mechanism. The cause for these sex differences is unknown, but early dimorphisms, such as differences in growth or presence of H-Y antigen, may be responsible. This model provides a useful rationale for understanding and classifying sex-biased congenital anomalies. 42 refs., 7 tabs.

  4. Obstetric consequences of uterovaginal anomalies

    SciTech Connect

    Rock, J.A.; Schlaff, W.D.

    1985-05-01

    This review discusses the diagnosis and classification of utero-vaginal anomalies as well as obstetric considerations in their management. Diagnosis is usually made by hysterosalpingography antepartum. Ultrasonography is also recommended. 40 references, 10 figures, 9 tables.

  5. Kohn anomalies in graphene nanoribbons

    E-print Network

    Dresselhaus, Mildred

    The quantum corrections to the energies of the ? point optical phonon modes (Kohn anomalies) in graphene nanoribbons (NRs) are investigated. We show theoretically that the longitudinal optical (LO) modes undergo a Kohn ...

  6. Spacecraft environmental anomalies expert system

    NASA Astrophysics Data System (ADS)

    Koons, Harry C.; Groney, David J.

    1994-02-01

    An expert system has been developed by The Aerospace Corporation, Space and Environment Technology Center for use in the diagnosis of satellite anomalies caused by the space environment. The expert system is designed to determine the probable cause of an anomaly from the following candidates: surface charging, bulk charging, single-event effects, total radiation dose, and space-plasma effects. Such anomalies depend on the orbit of the satellite, the local plasma and radiation environment (which is highly variable), the satellite-exposure time, and the hardness of the circuits and components in the satellite. The expert system is a rule-based system that uses the Texas Instrument's Personal Consultant Plus expert-system shell. The expert system's knowledgebase includes about 200 rules, as well as a number of databases that contain information on spacecraft and their orbits, previous spacecraft anomalies, and the environment.

  7. More anomalies from fractional branes

    Microsoft Academic Search

    M. Bertolini; P. Di Vecchia; M. Frau; A. Lerda; R. Marotta

    2002-01-01

    In this Letter we show how the anomalies of both pure and matter coupled N=1,2 supersymmetric gauge theories describing the low energy dynamics of fractional branes on orbifolds can be derived from supergravity.

  8. Triangle Anomalies, Thermodynamics, and Hydrodynamics

    E-print Network

    Kristan Jensen

    2012-04-11

    We consider 3+1-dimensional fluids with U(1)^3 anomalies. We use Ward identities to constrain low-momentum Euclidean correlation functions and obtain differential equations that relate two and three-point functions. The solution to those equations yields, among other things, the chiral magnetic conductivity. We then compute zero-frequency functions in hydrodynamics and show that the consistency of the hydrodynamic theory also fixes the anomaly-induced conductivities.

  9. Satellite elevation magnetic anomaly maps

    NASA Technical Reports Server (NTRS)

    Braile, L. W.; Hinze, W. J. (principal investigators)

    1982-01-01

    The problem of inverting 2 deg average MAGSAT scalar anomalies for the region 80 W, 60 E longitude and 40 S, 70 N latitude was attempted on the LARS computer; however, the effort was aborted due to insufficient allocation of CPU-time. This problem is currently being resubmitted and should be implemented shortly for quantitative comparison with free-air gravity anomaly, geothermal, and tectonic data.

  10. Isotopic compositions of rare gases in the carbonaceous chondrites Mokoia and Allende.

    NASA Technical Reports Server (NTRS)

    Manuel, O. K.; Wright, R. J.; Miller, D. K.; Kuroda, P. K.

    1972-01-01

    The isotopic compositions have been measured mass spectrometrically for neon, argon, krypton and xenon released from the carbonaceous chondrites Mokoia and Allende in stepwise heating experiments. The isotopic compositions of rare gases released from the meteorites at different temperatures varied quite considerably. A marked enrichment of Xe129 due to the decay of extinct nuclide I129 was observed in both meteorites. The variations of the isotopic ratios are partly caused by the presence of cosmic-ray spallation and neutron-capture products. In addition, however, a marked trend of mass-dependent variation of the isotopic ratios was observed in this work. The rare gas isotopes released from the meteorites appear to be systematically mass-fractionated relative to the relative abundances of the average carbonaceous chondrite. It seems that this phenomenon can be best explained as due to the fact that there exist reservoirs of two isotopically distinct gases in the meteorites and mixtures of these gases are being released at each temperature fraction.

  11. MAGSAT anomaly map and continental drift

    NASA Technical Reports Server (NTRS)

    Lemouel, J. L. (principal investigator); Galdeano, A.; Ducruix, J.

    1981-01-01

    Anomaly maps of high quality are needed to display unambiguously the so called long wave length anomalies. The anomalies were analyzed in terms of continental drift and the nature of their sources is discussed. The map presented confirms the thinness of the oceanic magnetized layer. Continental magnetic anomalies are characterized by elongated structures generally of east-west trend. Paleomagnetic reconstruction shows that the anomalies found in India, Australia, and Antarctic exhibit a fair consistency with the African anomalies. It is also shown that anomalies are locked under the continents and have a fixed geometry.

  12. Hyperfine Field and Hyperfine Anomalies of Copper Impurities in Iron

    E-print Network

    V. V. Golovko; F. Wauters; S. Cottenier; M. Breitenfeldt; V. De Leebeeck; S. Roccia; G. Soti; M. Tandecki; E. Traykov; S. Van Gorp; D. Zákoucký; N. Severijns

    2011-07-29

    A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving {\\beta}-NMR on oriented nuclei on 59-Cu, 69-Cu, and 71-Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., Bhf(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be 59{\\Delta}69=0.15(9)% and 71{\\Delta}69=0.07(11)%.

  13. FE and MG Isotopic Analyses of Isotopically Unusual Presolar Silicate Grains

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Messenger, S.; Ito, M.; Rahman, Z.

    2011-01-01

    Interstellar and circumstellar silicate grains are thought to be Mg-rich and Fe-poor, based on astronomical observations and equilibrium condensation models of silicate dust formation in stellar outflows. On the other hand, presolar silicates isolated from meteorites have surprisingly high Fe contents and few Mg-rich grains are observed. The high Fe contents in meteoritic presolar silicates may indicate they formed by a non-equilibrium condensation process. Alternatively, the Fe in the stardust grains could have been acquired during parent body alteration. The origin of Fe in presolar silicates may be deduced from its isotopic composition. Thus far, Fe isotopic measurements of presolar silicates are limited to the Fe-54/Fe-56 ratios of 14 grains. Only two slight anomalies (albeit solar within error) were observed. However, these measurements suffered from contamination of Fe from the adjacent meteorite matrix, which diluted any isotopic anomalies. We have isolated four presolar silicates having unusual O isotopic compositions by focused ion beam (FIB) milling and obtained their undiluted Mg and Fe isotopic compositions. These compositions help to identify the grains stellar sources and to determine the source of Fe in the grains.

  14. Persistent and recurrent neovascularization after krypton laser photocoagulation for neovascular lesions of ocular histoplasmosis. Macular Photocoagulation Study Group.

    PubMed

    1989-03-01

    Persistence and recurrence of choroidal neovascularization after initial treatment with laser photocoagulation have been shown to be major contributors to loss of visual acuity. The 144 eyes assigned to krypton red laser photocoagulation in the Ocular Histoplasmosis Study-Krypton Laser were examined to describe persistence and recurrence in these patients. Persistent neovascularization was observed among 23% of treated patients and recurrent neovascularization was observed among an additional 8%. Both persistence and recurrence were accompanied by an increased frequency of severe visual loss. Patients with high blood pressure were more than 2.5 times as likely to have persistent neovascularization as patients without high blood pressure (95% confidence interval = 1.5, 4.8). Eyes in which the neovascular component of the complex was within 200 microns of the center of the foveal avascular zone were twice as likely to have persistent neovascularization (95% confidence interval = 1.2, 4.6). Eyes in which the treatment did not cover the neovascularization completely or did not meet the required level of intensity on the foveal side had a persistence rate approximately three times that of eyes in which the neovascularization was covered completely by intense, confluent burns (95% confidence interval = 1.7, 6.5). This last finding is of particular importance for ophthalmologists who treat similar patients. PMID:2466454

  15. Pristine extraterrestrial material with unprecedented nitrogen isotopic variation.

    PubMed

    Briani, Giacomo; Gounelle, Matthieu; Marrocchi, Yves; Mostefaoui, Smail; Leroux, Hugues; Quirico, Eric; Meibom, Anders

    2009-06-30

    Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (delta(15)N(AIR) = -310 +/- 20 per thousand), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (delta(15)N(AIR) = 4,900 +/- 300 per thousand). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies. PMID:19528640

  16. Pristine extraterrestrial material with unprecedented nitrogen isotopic variation

    PubMed Central

    Briani, Giacomo; Gounelle, Matthieu; Marrocchi, Yves; Mostefaoui, Smail; Leroux, Hugues; Quirico, Eric; Meibom, Anders

    2009-01-01

    Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times that of a typical IDP. Furthermore, an extreme continuum of N isotopic variation is present in this xenolith: from very light N isotopic composition (?15NAIR = ?310 ± 20‰), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (?15NAIR = 4,900 ± 300‰). At the same time, its hydrogen and carbon isotopic compositions exhibit very little variation. This object poses serious challenges for existing models for the origin of light element isotopic anomalies. PMID:19528640

  17. Astrometric solar-system anomalies

    NASA Astrophysics Data System (ADS)

    Anderson, John D.; Nieto, Michael Martin

    2010-01-01

    There are at least four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. Next, a secular change in the astronomical unit AU is definitely a concern. It is reportedly increasing by about 15 cm yr-1. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists, including us, are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is prudent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.

  18. Astrometric Solar-System Anomalies

    E-print Network

    John D. Anderson; Michael Martin Nieto

    2009-08-06

    There are at least four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. Next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr$^{-1}$. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported unexplained increase that is significant at the three-sigma level. It is prudent to suspect that all four anomalies have mundane explanations, or that one or more anomalies are a result of systematic error. Yet they might eventually be explained by new physics. For example, a slightly modified theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation for the excess precession of Mercury's perihelion.

  19. 1. Isotope Definitions and terms a) Isotopes and isotope ratios.

    E-print Network

    Saleska, Scott

    -- The Compensation Point for C3 and C4 differ http://www.steve.gb.com/science/photosynthesis_and_respiration.html Net fractionation c) Simple illustration with the water cycle 2. CO2 isotopes in photosynthesis a) Photosynthetic discrimination in C3 plants b) C3 vs C4 photosynthesis and the distinction in isotopes c) Measuring isotopic

  20. Spacecraft environmental anomalies expert system

    NASA Technical Reports Server (NTRS)

    Koons, H. C.; Gorney, D. J.

    1988-01-01

    A microcomputer-based expert system is being developed at the Aerospace Corporation Space Sciences Laboratory to assist in the diagnosis of satellite anomalies caused by the space environment. The expert system is designed to address anomalies caused by surface charging, bulk charging, single event effects and total radiation dose. These effects depend on the orbit of the satellite, the local environment (which is highly variable), the satellite exposure time and the hardness of the circuits and components of the satellite. The expert system is a rule-based system that uses the Texas Instruments Personal Consultant Plus expert system shell. The completed expert system knowledge base will include 150 to 200 rules, as well as a spacecraft attributes database, an historical spacecraft anomalies database, and a space environment database which is updated in near real-time. Currently, the expert system is undergoing development and testing within the Aerospace Corporation Space Sciences Laboratory.

  1. Graph anomalies in cyber communications

    SciTech Connect

    Vander Wiel, Scott A [Los Alamos National Laboratory; Storlie, Curtis B [Los Alamos National Laboratory; Sandine, Gary [Los Alamos National Laboratory; Hagberg, Aric A [Los Alamos National Laboratory; Fisk, Michael [Los Alamos National Laboratory

    2011-01-11

    Enterprises monitor cyber traffic for viruses, intruders and stolen information. Detection methods look for known signatures of malicious traffic or search for anomalies with respect to a nominal reference model. Traditional anomaly detection focuses on aggregate traffic at central nodes or on user-level monitoring. More recently, however, traffic is being viewed more holistically as a dynamic communication graph. Attention to the graph nature of the traffic has expanded the types of anomalies that are being sought. We give an overview of several cyber data streams collected at Los Alamos National Laboratory and discuss current work in modeling the graph dynamics of traffic over the network. We consider global properties and local properties within the communication graph. A method for monitoring relative entropy on multiple correlated properties is discussed in detail.

  2. Branchial Anomalies: Diagnosis and Management

    PubMed Central

    Azeez, Arun; Thada, Nikhil Dinaker; Rao, Pallavi; Prasad, Kishore Chandra

    2014-01-01

    Objective. To find out the incidence of involvement of individual arches, anatomical types of lesions, the age and sex incidence, the site and side of predilection, the common clinical features, the common investigations, treatment, and complications of the different anomalies. Setting. Academic Department of Otolaryngology, Head and Neck Surgery. Design. A 10 year retrospective study. Participants. 30 patients with clinically proven branchial anomalies including patients with bilateral disease totaling 34 lesions. Main Outcome Measures. The demographical data, clinical features, type of branchial anomalies, and the management details were recorded and analyzed. Results and Observations. The mean age of presentation was 18.67 years. Male to female sex ratio was 1.27?:?1 with a male preponderance. Of the 34 lesions, maximum incidence was of second arch anomalies (50%) followed by first arch. We had two cases each of third and fourth arch anomalies. Only 1 (3.3%) patients of the 30 presented with lesion at birth. The most common pathological type of lesions was fistula (58.82%) followed by cyst. 41.18% of the lesions occurred on the right side. All the patients underwent surgical excision. None of our patients had involvement of facial nerve in first branchial anomaly. All patients had tracts going superficial to the facial nerve. Conclusion. Confirming the extent of the tract is mandatory before any surgery as these lesions pass in relation to some of the most vital structures of the neck. Surgery should always be the treatment option. injection of dye, microscopic removal and inclusion of surrounding tissue while excising the tract leads to a decreased incidence of recurrence. PMID:24772172

  3. Review on possible gravitational anomalies

    E-print Network

    Amador, X E

    2005-01-01

    This is an updated introductory review of 2 possible gravitational anomalies that has attracted part of the Scientific community: the Allais effect that occur during solar eclipses, and the Pioneer 10 spacecraft anomaly, experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to date, no satisfactory conventional explanation exist to these phenomena, and this suggests that possible new physics will be needed to account for them. The main purpose of this review is to announce 3 other new measurements that will be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8) and in Portugal (Oct.15).

  4. Review on possible gravitational anomalies

    E-print Network

    Xavier Amador

    2008-09-03

    This is an updated introductory review of 2 possible gravitational anomalies that has attracted part of the Scientific community: the Allais effect that occur during solar eclipses, and the Pioneer 10 spacecraft anomaly, experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to date, no satisfactory conventional explanation exist to these phenomena, and this suggests that possible new physics will be needed to account for them. The main purpose of this review is to announce 3 other new measurements that will be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8) and in Portugal (Oct.15).

  5. Analysis of DSN software anomalies

    NASA Technical Reports Server (NTRS)

    Galorath, D. D.; Hecht, H.; Hecht, M.; Reifer, D. J.

    1981-01-01

    A categorized data base of software errors which were discovered during the various stages of development and operational use of the Deep Space Network DSN/Mark 3 System was developed. A study team identified several existing error classification schemes (taxonomies), prepared a detailed annotated bibliography of the error taxonomy literature, and produced a new classification scheme which was tuned to the DSN anomaly reporting system and encapsulated the work of others. Based upon the DSN/RCI error taxonomy, error data on approximately 1000 reported DSN/Mark 3 anomalies were analyzed, interpreted and classified. Next, error data are summarized and histograms were produced highlighting key tendencies.

  6. The origin of the 'FUN' anomalies and the high temperature inclusions in the Allende meteorite. [Fractionation and Unknown Nuclear processes

    NASA Technical Reports Server (NTRS)

    Consolmagno, G. J.; Cameron, A. G. W.

    1980-01-01

    The discovery of isotopic anomalies in white inclusions of the meteorite Allende has led to fundamental questions concerning the origin of these anomalies and of the white inclusions themselves. An analysis of the 'FUN' anomalies in the inclusions C1 and EK1-4-1 demonstrates that these isotopic anomalies may be decomposed into individual nucleosynthetic components, which have been subjected to separate mass and component fractionations. There is no evidence that any freshly-synthesized material injected into the primitive solar nebula was of abnormal isotopic composition, or that the FUN anomalies were due to an injection of unusual material. Rather, they show the effects of large mass fractionations and an unusual mixture of normal nucleosynthetic material, likely to be in the form of interstellar grains whose size or chemistry served as a memory for the nucleosynthetic origins of their constituent atoms. Giant gaseous protoplanets, as described for the early solar nebula by Cameron (1978), are a potential site for achieving both mass and component fractionations, and for producing white inclusions in general.

  7. Astrometric Solar-System Anomalies

    Microsoft Academic Search

    John D. Anderson

    2009-01-01

    There are four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it experiences a gain in total orbital energy per unit mass (Anderson et al., Phys. Rev. Lett. 100, 091102). This amounts to a net velocity increase of 13.5

  8. Astrometric solar-system anomalies

    Microsoft Academic Search

    John D. Anderson; Michael Martin Nieto

    2010-01-01

    There are at least four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. Next, a secular change in the astronomical unit AU is definitely a concern. It

  9. Coral can have growth anomalies

    EPA Science Inventory

    Coral growth anomalies (GAs) are changes in the coral cells that deposit the calcium carbonate skeleton. They usually appear as raised areas of the skeleton and tissue that are different from the surrounding normal areas on the same colony. The features include abnormal shape a...

  10. Development anomalies of the occiput

    Microsoft Academic Search

    J. Wickenhauser; O. Hochberg

    1974-01-01

    Four patients with classical features of bathrocephalism are described. Three further patients with developmental anomalies of the occiput are described and these are contrasted with those having classical bathrocephalism. The distinction between the two groups is emphasised. Reference is made to cases described in the pediatric literature which appears at times to depart from the traditional norms and classical notation.

  11. Anomaly detection from hyperspectral imagery

    Microsoft Academic Search

    D. W. J. Stein; S. G. Beaven; L. E. Hoff; E. M. Winter; A. P. Schaum; A. D. Stocker

    2002-01-01

    We develop anomaly detectors, i.e., detectors that do not presuppose a signature model of one or more dimensions, for three clutter models: the local normal model, the global normal mixture model, and the global linear mixture model. The local normal model treats the neighborhood of a pixel as having a normal probability distribution. The normal mixture model considers the observation

  12. Anomalies, Unitarity, and Quantum Irreversibility

    Microsoft Academic Search

    Damiano Anselmi

    1999-01-01

    The trace anomaly in external gravity is the sum of three terms at criticality: the square of the Weyl tensor, the Euler density and ?R, with coefficients, properly normalized, called c, a, and a?, the latter being ambiguously defined by an additive constant. Considerations about unitarity and positivity properties of the induced actions allow us to show that the total

  13. Local gravity anomalies produced by dislocation sources.

    USGS Publications Warehouse

    Savage, J.C.

    1984-01-01

    Dilatancy, in general, does not correspond to the absence of a free air anomaly, as might be suggested by the special case of a spherical source of dilatation. For two-dimensional models a cylindrical source of dilatation produces no free air gravity anomaly, dip-slip faulting produces no Bouguer anomaly, and open cracks produce a Bouguer anomaly equal to that which would be produced had the material within the crack been mined out without deforming the solid. -from Author

  14. Lorentz Accelerations in the Earth Flyby Anomaly

    Microsoft Academic Search

    Justin A. Atchison; Mason A. Peck

    2010-01-01

    Mission engineers have detected an unexpected anomaly on six spacecraft during low-altitude gravity-assist maneuvers around Earth. This Earth flyby anomaly involves an acceleration that, to date, researchers cannot account for based on known forces or errors in measurement or modeling. This paper evaluates Lorentz accelerations associated with spacecraft electrostatic charging as a possible explanation for the Earth flyby anomaly. This

  15. Payload Content based Network Anomaly Detection

    Microsoft Academic Search

    Sandeep A. Thorat; Amit K. Khandelwal; Bezawada Bruhadeshwar; K. Kishore

    2008-01-01

    We present payload content based network anomaly detection, we call as PCNAD. PCNAD is an improvement to PAYL system which is considered one of the complete systems for payload based anomaly detection. PAYL takes into consideration the entire payload for profile calculation and effectively for anomaly detection. Payload length is very high on port numbers like 21 and 80. Hence

  16. Diagnosing network-wide traffic anomalies

    Microsoft Academic Search

    Anukool Lakhina; Mark Crovella; Christophe Diot

    2004-01-01

    Anomalies are unusual and significant changes in a network's traffic levels, which can often span multiple links. Diagnosing anomalies is critical for both network operators and end users. It is a difficult problem because one must extract and interpret anomalous patterns from large amounts of high-dimensional, noisy data.In this paper we propose a general method to diagnose anomalies. This method

  17. Spectrum of anomalies in Fanconi anaemia

    Microsoft Academic Search

    A Glanz; F C Fraser

    1982-01-01

    The frequency of various anomalies was compared in probands with Fanconi anaemia and their affected sibs. As probands are usually ascertained because of a 'characteristic' array of physical anomalies, the frequencies of these specific anomalies may be overestimated in probands, whereas their affected sibs may provide a more accurate estimate. The frequencies of growth retardation, skin hyperpigmentation, radial ray deformities,

  18. Detecting BGP Anomalies with Wavelet Jianning Mai

    E-print Network

    Chuah, Chen-Nee

    Detecting BGP Anomalies with Wavelet Jianning Mai ECE Department, UC Davis jnmai@ece.ucdavis.edu Abstract--In this paper, we propose a BGP anomaly detection framework called BAlet that delivers both property and earlier success in applying it for network anomaly detection motivate us to apply the same

  19. Anomaly Detection and Localization in Crowded Scenes

    E-print Network

    Vasconcelos, Nuno M.

    Anomaly Detection and Localization in Crowded Scenes Weixin Li, Student Member, IEEE, Vijay that the latter achieves state-of- the-art anomaly detection results. Index Terms--Video analysis, surveillance, anomaly detection, crowded scene, dynamic texture, center-surround saliency Ç 1 INTRODUCTION SURVEILLANCE

  20. CONCURRENT ATMOSPHERE-LAND-OCEAN ANOMALIES

    E-print Network

    Kalnay, Eugenia

    deviation can be used as threshold Duration of this anomaly A standard deviation with respect to the annual and 850hPa RV anomalies. #12;Annual number (contours) and average life span (shades) Geographical anomalies that exceeded one quarter of the standard deviation (w.r.t. the annual cycle) we counted

  1. Communication: Electron transfer mediated decay enabled by spin-orbit interaction in small krypton/xenon clusters

    NASA Astrophysics Data System (ADS)

    Zobel, J. Patrick; Kryzhevoi, Nikolai V.; Pernpointner, Markus

    2014-04-01

    In this work we study the influence of relativistic effects, in particular spin-orbit coupling, on electronic decay processes in KrXe2 clusters of various geometries. For the first time it is shown that inclusion of spin-orbit coupling has decisive influence on the accessibility of a specific decay pathway in these clusters. The radiationless relaxation process is initiated by a Kr 4s ionization followed by an electron transfer from xenon to krypton and a final second ionization of the system. We demonstrate the existence of competing electronic decay pathways depending in a subtle way on the geometry and level of theory. For our calculations a fully relativistic framework was employed where omission of spin-orbit coupling leads to closing of two decay pathways. These findings stress the relevance of an adequate relativistic description for clusters with heavy elements and their fragmentation dynamics.

  2. Effective potential for e-argon and e-krypton scattering by DCS and minimization at intermediate energies

    SciTech Connect

    Paikeday, J.M.

    1999-12-01

    The differential scattering cross section (DCS) for electrons scattered elastically by argon and krypton atoms is studied using a model potential. In the present study, the long-range polarization potential is represented by an energy-dependent function and the short-range part is constructed from the nonrelativistic Hartree-Fock wave function of the target atom. The computed differential cross section obtained using the approximate effective interaction potential for electrons scattered by neon and argon atoms in their ground state is compared with available published results. In the present study, the parameters contained in the energy-dependent effective potential are determined by the minimization of the DCS with respect to angle {theta} and the incident energy. The resulting DCS in the angular range 2{degree} {lt} {theta} {lt} 178{degree} is found to be in good agreement with the available experimental and theoretical results in the intermediate energy range.

  3. Stable isotope studies

    SciTech Connect

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  4. Correlated Nitrogen and Carbon Anomalies in an Anhydrous Interplanetary Dust Particle - Implications for Extraterrestrial Organic Matter Accreted by the Prebiotic Earth

    SciTech Connect

    Floss, C; Stadermann, F J; Bradley, J P; Dai, Z; Bajt, S; Graham, G

    2003-12-17

    Given the ubiquitous presence of H and N isotopic anomalies in interplanetary dust particles (IDPs) and their probable association with carbonaceous material, the lack of similar isotopic anomalies in C has been a major conundrum. We report here the first observation of correlated N and C isotopic anomalies in organic matter within an anhydrous IDP. The {sup 15}N composition of the anomalous region is the highest seen to date in an IDP and is accompanied by a moderate depletion in {sup 13}C. Our observations establish the presence of hetero-atomic organic compounds of presolar origin among the constant flux of carbonaceous material accreting to the terrestrial planets within IDPs. Theoretical models suggest that low temperature formation of organic compounds in cold interstellar molecular clouds does produce C and N fractionations, but it remains to be seen if these models can reproduce the specific effects we observe here.

  5. BY DEFINITION UNDEFINED: ADVENTURES IN ANOMALY (AND ANOMALOUS CHANGE) DETECTION

    E-print Network

    Theiler, James

    BY DEFINITION UNDEFINED: ADVENTURES IN ANOMALY (AND ANOMALOUS CHANGE) DETECTION James Theiler Los for the detection of anomalies and anomalous changes in hyperspectral imagery. The technical emphasis in anomaly. In general, the detection of anomalies is complicated by the fact that anomalies are rare and that anomalies

  6. Grains of anomalous isotopic composition from novae

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.; Hoyle, F.

    1976-01-01

    The effects of grain formation in nova ejecta are studied in order to model the optical and infrared luminosities schematically and to identify the anomalies of isotopic composition that should be present in large abundance in these grains. The large carbon concentration makes rapid and efficient grain formation possible and accounts for the peculiar luminosities observed in Nova Serpentis 1970. In the anticipated range of nova conditions, rapid addition of hot protons during the outburst produces large overabundances of C-13, O-18, Na-22, Al-26, Si-30, and perhaps others. Anomalous C-14 is expected subsequent to the C-13(alpha, n)O-16 reaction, and will be trapped in grains formed by subsequent atmospheric loss. Each of these anomalies may have been detected on the moon (due to accretion of interstellar dust) or in carbonaceous chondrites. Perhaps nova grains are responsible.

  7. Relationship between positive CE anomaly and adsorbed water in Antarctic lunar meteorites

    NASA Astrophysics Data System (ADS)

    Kagi, Hiroyuki; Takahashi, Kazuya

    1998-09-01

    Concentration of adsorbed water in single mineral grains of Antarctic lunar meteorites was determined with micro IR spectroscopy. A relationship was found between the mineral ability to adsorb water and the extent of Ce anomaly in REE pattern precisely determined by the isotope dilution method using a thermal ionization mass spectrometry. Aska(A)-881757, a lunar meteorite from the mare basalt without Ce anomaly, showed no trace of IR absorption due to adsorbed water. On the contrary, Yamato(Y)-791197-109, Y-86032-98, Y-86032-95, Y-791197- 115 and Y-82192-55A from the lunar highland exhibiting positive Ce anomaly showed IR absorption due to adsorbed water in some of their minerals. The detected water would be a terrestrial origin, because it was not structurally bound and easy to exchange judging from the spectral band shape. The contrast in concentration of adsorbed water between the lunar highland and the mare basalt derived from a difference in the density of micro fracture in mineral grain. Average concentrations of adsorbed water in the lunar highland meteorites were 3.8 mg/cm3 for pyroxene and olivine, and 1.7 mg/cm3 for plagioclase, respectively. This contrast between minerals is noteworthy because it has been known that Ce anomaly of pyroxene and olivine is larger than that of plagioclase both for Antarctic lunar meteorites and some lunar rocks. Furthermore, more adsorbed water was detected for minerals in meteorite exhibiting larger Ce anomaly. The present observations demonstrated that the extent of Ce anomaly correlated with the concentration of adsorbed water, which suggests that active mineral surface resulting in adsorption of water could be a trace of interaction forming Ce anomaly. Terrestrial weathering on Antarctica and REE fractionation on the Moon were discussed for possible origins of the Ce anomaly.

  8. Apollo experience report: Flight anomaly resolution

    NASA Technical Reports Server (NTRS)

    Lobb, J. D.

    1975-01-01

    The identification of flight anomalies, the determination of their causes, and the approaches taken for corrective action are described. Interrelationships of the broad range of disciplines involved with the complex systems and the team concept employed to ensure timely and accurate resolution of anomalies are discussed. The documentation techniques and the techniques for management of anomaly resolution are included. Examples of specific anomalies are presented in the original form of their progressive documentation. Flight anomaly resolution functioned as a part of the real-time mission support and postflight testing, and results were included in the postflight documentation.

  9. Developing a new, passive diffusion sampler suite to detect helium anomalies associated with volcanic unrest

    NASA Astrophysics Data System (ADS)

    Dame, Brittany E.; Solomon, D. Kip; Evans, William C.; Ingebritsen, Steven E.

    2015-03-01

    Helium (He) concentration and 3He/4He anomalies in soil gas and spring water are potentially powerful tools for investigating hydrothermal circulation associated with volcanism and could perhaps serve as part of a hazards warning system. However, in operational practice, He and other gases are often sampled only after volcanic unrest is detected by other means. A new passive diffusion sampler suite, intended to be collected after the onset of unrest, has been developed and tested as a relatively low-cost method of determining He-isotope composition pre- and post-unrest. The samplers, each with a distinct equilibration time, passively record He concentration and isotope ratio in springs and soil gas. Once collected and analyzed, the He concentrations in the samplers are used to deconvolve the time history of the He concentration and the 3He/4He ratio at the collection site. The current suite consisting of three samplers is sufficient to deconvolve both the magnitude and the timing of a step change in in situ concentration if the suite is collected within 100 h of the change. The effects of temperature and prolonged deployment on the suite's capability of recording He anomalies have also been evaluated. The suite has captured a significant 3He/4He soil gas anomaly at Horseshoe Lake near Mammoth Lakes, California. The passive diffusion sampler suite appears to be an accurate and affordable alternative for determining He anomalies associated with volcanic unrest.

  10. Anomaly detection and diagnosis in Grid environments.

    SciTech Connect

    Yang, L.; Liu, C.; Schopf, J. M.; Foster, I.; Mathematics and Computer Science; Univ. of Chicago; Microsoft Corp.

    2007-01-01

    Identifying and diagnosing anomalies in application behavior is critical to delivering reliable application-level performance. In this paper we introduce a strategy to detect anomalies and diagnose the possible reasons behind them. Our approach extends the traditional window-based strategy by using signal-processing techniques to filter out recurring, background fluctuations in resource behavior. In addition, we have developed a diagnosis technique that uses standard monitoring data to determine which related changes in behavior may cause anomalies. We evaluate our anomaly detection and diagnosis technique by applying it in three contexts when we insert anomalies into the system at random intervals. The experimental results show that our strategy detects up to 96% of anomalies while reducing the false positive rate by up to 90% compared to the traditional window average strategy. In addition, our strategy can diagnose the reason for the anomaly approximately 75% of the time.

  11. Satellite GN and C Anomaly Trends

    NASA Technical Reports Server (NTRS)

    Robertson, Brent; Stoneking, Eric

    2003-01-01

    On-orbit anomaly records for satellites launched from 1990 through 2001 are reviewed to determine recent trends of un-manned space mission critical failures. Anomalies categorized by subsystems show that Guidance, Navigation and Control (GN&C) subsystems have a high number of anomalies that result in a mission critical failure when compared to other subsystems. A mission critical failure is defined as a premature loss of a satellite or loss of its ability to perform its primary mission during its design life. The majority of anomalies are shown to occur early in the mission, usually within one year from launch. GN&C anomalies are categorized by cause and equipment type involved. A statistical analysis of the data is presented for all anomalies compared with the GN&C anomalies for various mission types, orbits and time periods. Conclusions and recommendations are presented for improving mission success and reliability.

  12. Survey of Anomaly Detection Methods

    SciTech Connect

    Ng, B

    2006-10-12

    This survey defines the problem of anomaly detection and provides an overview of existing methods. The methods are categorized into two general classes: generative and discriminative. A generative approach involves building a model that represents the joint distribution of the input features and the output labels of system behavior (e.g., normal or anomalous) then applies the model to formulate a decision rule for detecting anomalies. On the other hand, a discriminative approach aims directly to find the decision rule, with the smallest error rate, that distinguishes between normal and anomalous behavior. For each approach, we will give an overview of popular techniques and provide references to state-of-the-art applications.

  13. Anomalies and Discrete Chiral Symmetries

    SciTech Connect

    Creutz, M.

    2009-09-07

    The quantum anomaly that breaks the U(1) axial symmetry of massless multi-flavored QCD leaves behind a discrete flavor-singlet chiral invariance. With massive quarks, this residual symmetry has a close connection with the strong CP-violating parameter theta. One result is that if the lightest quarks are degenerate, then a first order transition will occur when theta passes through pi. The resulting framework helps clarify when the rooting prescription for extrapolating in the number of flavors is valid.

  14. Astrometric Solar-System Anomalies

    NASA Astrophysics Data System (ADS)

    Anderson, John D.

    2009-05-01

    There are four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it experiences a gain in total orbital energy per unit mass (Anderson et al., Phys. Rev. Lett. 100, 091102). This amounts to a net velocity increase of 13.5 mm/s for the NEAR spacecraft at a closest approach of 539 km, 3.9 mm/s for the Galileo spacecraft at 960 km, and 1.8 mm/s for the Rosetta spacecraft at 1956 km. Next, I suggest the change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm/yr (Krasinsky and Brumberg, Celes. Mech. & Dynam. Astron. 90, 267). The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions (Anderson et al., Phys. Rev. D 65, 082004). Some, including me, are convinced this effect is of concern, but many are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction in both the Earth and Moon. However, there is a reported increase that is about three times larger than expected (J. G. Williams, DDA/AAS Brouwer Award Lecture, Halifax, Nova Scotia 2006). We suspect that all four anomalies have mundane explanations. However, the possibility that they will be explained by a new theory of gravitation is not ruled out, perhaps analogous to Einstein's 1916 explanation of the excess precession of Mercury's perihelion.

  15. Astrometric Solar-System Anomalies

    Microsoft Academic Search

    Sergei Klioner; P. Kenneth Seidelmann

    2009-01-01

    There are at least four unexplained anomalies connected with astrometric\\u000adata. Perhaps the most disturbing is the fact that when a spacecraft on a flyby\\u000atrajectory approaches the Earth within 2000 km or less, it often experiences a\\u000achange in total orbital energy per unit mass. Next, a secular change in the\\u000aastronomical unit AU is definitely a concern. It

  16. Columbus Payloads Flow Rate Anomalies

    NASA Technical Reports Server (NTRS)

    Quaranta, Albino; Bufano, Gaetana; DePalo, Savino; Holt, James M.; Szigetvari, Zoltan; Palumberi, Sergio; Hinderer, S.

    2011-01-01

    The Columbus Active Thermal Control System (ATCS) is the main thermal bus for the pressurized racks working inside the European laboratory. One of the ATCS goals is to provide proper water flow rate to each payload (P/L) by controlling actively the pressure drop across the common plenum distribution piping. Overall flow measurement performed by the Water Pump Assembly (WPA) is the only flow rate monitor available at system level and is not part of the feedback control system. At rack activation the flow rate provided by the system is derived on ground by computing the WPA flow increase. With this approach, several anomalies were raised during these 3 years on-orbit, with the indication of low flow rate conditions on the European racks FSL, BioLab, EDR and EPM. This paper reviews the system and P/Ls calibration approach, the anomalies occurred, the engineering evaluation on the measurement approach and the accuracy improvements proposed, the on-orbit test under evaluation with NASA and finally discusses possible short and long term solutions in case of anomaly confirmation.

  17. Astrometric Solar-System Anomalies

    E-print Network

    Anderson, John D

    2009-01-01

    There are at least four unexplained anomalies connected with astrometric data. Perhaps the most disturbing is the fact that when a spacecraft on a flyby trajectory approaches the Earth within 2000 km or less, it often experiences a change in total orbital energy per unit mass. Next, a secular change in the astronomical unit AU is definitely a concern. It is increasing by about 15 cm yr$^{-1}$. The other two anomalies are perhaps less disturbing because of known sources of nongravitational acceleration. The first is an apparent slowing of the two Pioneer spacecraft as they exit the solar system in opposite directions. Some astronomers and physicists are convinced this effect is of concern, but many others are convinced it is produced by a nearly identical thermal emission from both spacecraft, in a direction away from the Sun, thereby producing acceleration toward the Sun. The fourth anomaly is a measured increase in the eccentricity of the Moon's orbit. Here again, an increase is expected from tidal friction ...

  18. Congenital Anomalies of the Limbs

    PubMed Central

    Gingras, G.; Mongeau, M.; Moreault, P.; Dupuis, M.; Hebert, B.; Corriveau, C.

    1964-01-01

    As a preparatory step towards the development of a complete habilitation program for children with congenital limb anomalies associated with maternal ingestion of thalidomide, the medical records of all patients with congenital limb anomalies referred to the Rehabilitation Institute of Montreal in the past decade were studied, and an examination and a thorough reassessment were made of 41 patients (21 males and 20 females). The medical and prosthetic aspects were dealt with in Part I of this paper. Part II describes, in a joint report, the results of psychiatric, psychological and educational assessments. There was no evidence of major emotional disorder in any of the patients, although conflicts were intensified by the presence of the physical anomaly. No relation was found between intelligence, emotional adjustment and disability. The patient's attitude towards his disability and prosthesis is definitely influenced by the degree of parental acceptance of the handicap and by the character of the emotional undertones in the total environment. In order to favour the occurrence of the healthiest modes of development in these children, the authors believe that the medical profession should be made fully aware of the physical and emotional problems which may arise after the birth of a deformed child. It is considered very important that the mother should receive psychotherapeutic support as soon as possible after the child is born. PMID:14174527

  19. Nickel and chromium isotopes in Allende inclusions

    NASA Technical Reports Server (NTRS)

    Birck, J. L.; Lugmair, G. W.

    1988-01-01

    High-precision nickel and chromium isotopic measurements were carried out on nine Allende inclusions. It is found that Ni-62, Ni-64, excesses are present in at least three of the samples. The results suggest that the most likely mechanism for the anomalies is a neutron-rich statistical equilibrium process. An indication of elevated Ni-60 is found in almost every inclusion measured. This effect is thought to be related to the decay of now extinct Fe-60. An upper limit of 1.6 X 10 to the -6th is calculated for the Fe-60/Fe-56 ratio at the time these Allende inclusions crystallized.

  20. Condensation of solids in space. Isotope fractionation in the model system C-O

    NASA Technical Reports Server (NTRS)

    Arrhenius, G.

    1983-01-01

    The reported chemical fractionation of a single isotope O-16 under simulated space conditions provides the first experimental proof for the hypothesis that the oxygen isotopic anomaly (and other similar anomalies) seen in meteorites is a product of chemical fractionation in interstellar or circumstellar space. Work proposed on this subject was discontinued because a peer review determined that such effects could not possibly exist and that continued support of this project would be a wasted effort. A bibliography is included of articles generated during research in this area.

  1. On the equatorial anomaly of the ionospheric total electron content near the northern anomaly crest region

    SciTech Connect

    Huang, Y.; Cheng, K.; Chen, S. (Telecommunication Training Institute, Ministry of Communications, Taipei, Taiwan (TW))

    1989-10-01

    Daily contour charts of the ionospheric total electron content in latitude versus local time coordinates have been used to study the behavior of the development of the equatorial anomaly around the northern anomaly crest region. The daily development of the equatorial anomaly shows quite large day-to-day variabilities not only on magnetically disturbed days but also on quiet days. The daily maximum anomaly crest moves poleward as the magnitude of the total electron content of the daily maximum anomaly crest increases. The increase of the equatorial electrojet strength also results in a poleward movement of the anomaly crest. No significant correlation exists between the anomaly crest and the magnetic {ital Ap} index. The monthly mean diurnal development of the equatorial anomaly shows a remarkable seasonal difference, with the anomaly largest in equinoxes and slightly larger in winter than in summer. {copyright} American Geophysical Union 1989

  2. ISHM Anomaly Lexicon for Rocket Test

    NASA Technical Reports Server (NTRS)

    Schmalzel, John L.; Buchanan, Aubri; Hensarling, Paula L.; Morris, Jonathan; Turowski, Mark; Figueroa, Jorge F.

    2007-01-01

    Integrated Systems Health Management (ISHM) is a comprehensive capability. An ISHM system must detect anomalies, identify causes of such anomalies, predict future anomalies, help identify consequences of anomalies for example, suggested mitigation steps. The system should also provide users with appropriate navigation tools to facilitate the flow of information into and out of the ISHM system. Central to the ability of the ISHM to detect anomalies is a clearly defined catalog of anomalies. Further, this lexicon of anomalies must be organized in ways that make it accessible to a suite of tools used to manage the data, information and knowledge (DIaK) associated with a system. In particular, it is critical to ensure that there is optimal mapping between target anomalies and the algorithms associated with their detection. During the early development of our ISHM architecture and approach, it became clear that a lexicon of anomalies would be important to the development of critical anomaly detection algorithms. In our work in the rocket engine test environment at John C. Stennis Space Center, we have access to a repository of discrepancy reports (DRs) that are generated in response to squawks identified during post-test data analysis. The DR is the tool used to document anomalies and the methods used to resolve the issue. These DRs have been generated for many different tests and for all test stands. The result is that they represent a comprehensive summary of the anomalies associated with rocket engine testing. Fig. 1 illustrates some of the data that can be extracted from a DR. Such information includes affected transducer channels, narrative description of the observed anomaly, and the steps used to correct the problem. The primary goal of the anomaly lexicon development efforts we have undertaken is to create a lexicon that could be used in support of an associated health assessment database system (HADS) co-development effort. There are a number of significant byproducts of the anomaly lexicon compilation effort. For example, (1) Allows determination of the frequency distribution of anomalies to help identify those with the potential for high return on investment if included in automated detection as part of an ISHM system, (2) Availability of a regular lexicon could provide the base anomaly name choices to help maintain consistency in the DR collection process, and (3) Although developed for the rocket engine test environment, most of the anomalies are not specific to rocket testing, and thus can be reused in other applications.

  3. Methods and limitations of 'clumped' CO2 isotope (Delta47) analysis by gas-source isotope ratio mass spectrometry.

    PubMed

    Huntington, K W; Eiler, J M; Affek, H P; Guo, W; Bonifacie, M; Yeung, L Y; Thiagarajan, N; Passey, B; Tripati, A; Daëron, M; Came, R

    2009-09-01

    The geochemistry of multiply substituted isotopologues ('clumped-isotope' geochemistry) examines the abundances in natural materials of molecules, formula units or moieties that contain more than one rare isotope (e.g. (13)C(18)O(16)O, (18)O(18)O, (15)N(2), (13)C(18)O(16)O(2) (2-)). Such species form the basis of carbonate clumped-isotope thermometry and undergo distinctive fractionations during a variety of natural processes, but initial reports have provided few details of their analysis. In this study, we present detailed data and arguments regarding the theoretical and practical limits of precision, methods of standardization, instrument linearity and related issues for clumped-isotope analysis by dual-inlet gas-source isotope ratio mass spectrometry (IRMS). We demonstrate long-term stability and subtenth per mil precision in 47/44 ratios for counting systems consisting of a Faraday cup registered through a 10(12) ohm resistor on three Thermo-Finnigan 253 IRMS systems. Based on the analyses of heated CO(2) gases, which have a stochastic distribution of isotopes among possible isotopologues, we document and correct for (1) isotopic exchange among analyte CO(2) molecules and (2) subtle nonlinearity in the relationship between actual and measured 47/44 ratios. External precisions of approximately 0.01 per thousand are routinely achieved for measurements of the mass-47 anomaly (a measure mostly of the abundance anomaly of (13)C-(18)O bonds) and follow counting statistics. The present technical limit to precision intrinsic to our methods and instrumentation is approximately 5 parts per million (ppm), whereas precisions of measurements of heterogeneous natural materials are more typically approximately 10 ppm (both 1 s.e.). These correspond to errors in carbonate clumped-isotope thermometry of +/-1.2 degrees C and +/-2.4 degrees C, respectively. PMID:19621330

  4. Photochemical mass-independent sulfur isotopes in achondritic meteorites.

    PubMed

    Rai, Vinai K; Jackson, Teresa L; Thiemens, Mark H

    2005-08-12

    Sulfides from four achondrite meteorite groups are enriched in 33S (up to 0.040 per mil) as compared with primitive chondrites and terrestrial standards. Stellar nucleosynthesis and cosmic ray spallation are ruled out as causes of the anomaly, but photochemical reactions in the early solar nebula could produce the isotopic composition. The large 33S excess present in oldhamite from the Norton County aubrite (0.161 per mil) suggests that refractory sulfide minerals condensed from a nebular gas with an enhanced carbon-oxygen ratio, but otherwise solar composition is the carrier. The presence of a mass-independent sulfur effect in meteorites argues for a similar process that could account for oxygen isotopic anomalies observed in refractory inclusions in primitive chondrites. PMID:16099982

  5. Barium isotopes in Allende meteorite: evidence against an extinct superheavy element

    Microsoft Academic Search

    R. S. Lewis; E. Anders; T. Shimamura; G. W. Lugmair

    1983-01-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10¹¹ atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently

  6. Barium isotopes in Allende meteorite - Evidence against an extinct superheavy element

    NASA Technical Reports Server (NTRS)

    Lewis, R. S.; Anders, E.; Shimamura, T.; Lugmair, G. W.

    1983-01-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10 to the 11th atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

  7. Barium isotopes in allende meteorite: evidence against an extinct superheavy element.

    PubMed

    Lewis, R S; Anders, E; Shimamura, T; Lugmair, G W

    1983-12-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10(11) atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis. PMID:17776244

  8. First-principles theory of anharmonicity and the inverse isotope effect in superconducting palladium-hydride compounds.

    PubMed

    Errea, Ion; Calandra, Matteo; Mauri, Francesco

    2013-10-25

    Palladium hydrides display the largest isotope effect anomaly known in the literature. Replacement of hydrogen with the heavier isotopes leads to higher superconducting temperatures, a behavior inconsistent with harmonic theory. Solving the self-consistent harmonic approximation by a stochastic approach, we obtain the anharmonic free energy, the thermal expansion, and the superconducting properties fully ab initio. We find that the phonon spectra are strongly renormalized by anharmonicity far beyond the perturbative regime. Superconductivity is phonon mediated, but the harmonic approximation largely overestimates the superconducting critical temperatures. We explain the inverse isotope effect, obtaining a -0.38 value for the isotope coefficient in good agreement with experiments, hydrogen anharmonicity being mainly responsible for the isotope anomaly. PMID:24206514

  9. Strictly anomaly mediated supersymmetry breaking

    NASA Astrophysics Data System (ADS)

    Hindmarsh, Mark; Jones, D. R. Timothy

    2013-04-01

    We consider an extension of the minimal supersymmetric Standard Model with anomaly mediation as the only source of supersymmetry breaking, and the tachyonic slepton problem solved by a gauged U(1) symmetry. The extra gauge symmetry is broken at high energies in a manner preserving supersymmetry, while also introducing both the seesaw mechanism for neutrino masses, and the Higgs ?-term. We call the model strictly anomaly mediated supersymmetry breaking. We present typical spectra for the model and compare them with those from so-called minimal anomaly mediated supersymmetry breaking. We find a Standard Model-like Higgs of mass 125 GeV with a gravitino mass of 140 TeV and tan??=16. However, the muon anomalous magnetic moment is 3? away from the experimental value. The model naturally produces a period of hybrid inflation, which can exit to a false vacuum characterized by large Higgs vacuum expectation values, reaching the true ground state after a period of thermal inflation. The scalar spectral index is reduced to approximately 0.975, and the correct abundance of neutralino dark matter can be produced by decays of thermally produced gravitinos, provided the gravitino mass (and hence the Higgs mass) is high. Naturally light cosmic strings are produced, satisfying bounds from the cosmic microwave background. The complementary pulsar timing and cosmic ray bounds require that strings decay primarily via loops into gravitational waves. Unless the loops are extremely small, the next generation pulsar timing array will rule out or detect the string-derived gravitational radiation background in this model.

  10. Earth Flyby and Pioneer Anomalies

    E-print Network

    Gerrard, M B

    2008-01-01

    Applying Newtonian dynamics in five dimensions rather than four, to a universe that is closed, isotropic and expanding, suggests that under certain circumstances an additional and previously unidentified acceleration can arise affecting the four dimensional motion of spacecraft. The reported acceleration anomalies from several Earth flybys and from the Pioneer spacecrafts are in reasonable agreement with the predicted values of this additional acceleration. Equations governing this additional acceleration have been derived from first principles, without the introduction of free parameters or new constants and without amendment to the law of gravity.

  11. Hot Flow Anomalies at Venus

    NASA Technical Reports Server (NTRS)

    Collinson, G. A.; Sibeck, David Gary; Boardsen, Scott A.; Moore, Tom; Barabash, S.; Masters, A.; Shane, N.; Slavin, J.A.; Coates, A.J.; Zhang, T. L.; Sarantos, M.

    2012-01-01

    We present a multi-instrument study of a hot flow anomaly (HFA) observed by the Venus Express spacecraft in the Venusian foreshock, on 22 March 2008, incorporating both Venus Express Magnetometer and Analyzer of Space Plasmas and Energetic Atoms (ASPERA) plasma observations. Centered on an interplanetary magnetic field discontinuity with inward convective motional electric fields on both sides, with a decreased core field strength, ion observations consistent with a flow deflection, and bounded by compressive heated edges, the properties of this event are consistent with those of HFAs observed at other planets within the solar system.

  12. Chiral and gravitational anomalies in any dimension

    SciTech Connect

    Delbourgo, R.; Matsuki, T.

    1985-06-01

    Gravitational contributions to the chiral anomaly in 4N space-time dimensions as well as the purely gravitational anomaly in 4N-2 dimensions are expressed in terms of the Riemann--Christoffel tensor. Using this formula, we give a simple proof that if N > or = 4 there is no way to cancel the gravitational anomalies using fields of spin- 1/2 , - (3)/(2) , and -1.

  13. ?-Wars episode I: the phantom anomaly

    Microsoft Academic Search

    Ken Intriligator; Jason Kumar

    2002-01-01

    As pointed out, chiral non-commutative theories exist, and examples can be constructed via string theory. Gauge anomalies require the matter content of individual gauge group factors, including U(1) factors, to be non-chiral. All “bad” mixed gauge anomalies, and also all “good” (e.g., for ?0???) ABJ type flavor anomalies, automatically vanish in non-commutative gauge theories. We interpret this as being analogous

  14. Tellurium isotopic composition of the early solar system—A search for effects resulting from stellar nucleosynthesis, 126Sn decay, and mass-independent fractionation

    Microsoft Academic Search

    Manuela A. Fehr; Mark Rehkämper; Alex N. Halliday; Uwe Wiechert; Bodo Hattendorf; Detlef Günther; Shuhei Ono; Jennifer L. Eigenbrode; Douglas Rumble

    2005-01-01

    New precise Te isotope data acquired by multiple collector inductively coupled plasma mass spectrometry (MC-ICPMS) are presented for selected extraterrestrial and terrestrial materials. Bulk samples of carbonaceous, ordinary and enstatite chondrites as well as the metal and sulfide phases of iron meteorites were analyzed to search for nucleosynthetic isotope anomalies and to find evidence of formerly live 126Sn, which decays

  15. doi:10.1016/S0016-7037(00)00059-0 Mass-independent isotope effects in Archean (2.5 to 3.8 Ga) sedimentary sulfides

    E-print Network

    ) Abstract--We report sulfur isotope anomalies with 33 S, the deviation from a mass-dependent fractionation processes fractionate isotopes because of the relative mass differences of the isotopomers rigorous theoretical treatment leads to the definition of an equilibrium mass-dependent fractionation line

  16. Discovery of mass anomalies on Ganymede.

    PubMed

    Anderson, John D; Schubert, Gerald; Jacobson, Robert A; Lau, Eunice L; Moore, William B; Palguta, Jennifer L

    2004-08-13

    We present the discovery of mass anomalies on Ganymede, Jupiter's third and largest Galilean satellite. This discovery is surprising for such a large icy satellite. We used the radio Doppler data generated with the Galileo spacecraft during its second encounter with Ganymede on 6 September 1996 to model the mass anomalies. Two surface mass anomalies, one a positive mass at high latitude and the other a negative mass at low latitude, can explain the data. There are no obvious geological features that can be identified with the anomalies. PMID:15310898

  17. Satellite Magnetic Anomalies of Africa and Europe

    NASA Technical Reports Server (NTRS)

    Hinze, W. J.; Vonfrese, R. R. B. (principal investigators); Olivier, R.

    1984-01-01

    Preliminary MAGSAT scalar magnetic anomaly data of Africa, Europe, and adjacent marine areas were reduced to the pole assuming a constant inducing Earth's magnetic field of 60,000 nT. This process leads to a consistent anomaly data set free from marked variations in directional and intensity effects of the Earth's magnetic field over this extensive region. The resulting data are correlated with long wave length-pass filtered free-air gravity anomalies; regional heat flow, and tectonic data to investigate magatectonic elements and the region's geologic history. Magnetic anomalies are related to both ancient as well as more recent Cenozoic structural features.

  18. Conscious and unconscious detection of semantic anomalies.

    PubMed

    Hannon, Brenda

    2015-07-01

    When asked What superhero is associated with bats, Robin, the Penguin, Metropolis, Catwoman, the Riddler, the Joker, and Mr. Freeze? people frequently fail to notice the anomalous word Metropolis. The goals of this study were to determine whether detection of semantic anomalies, like Metropolis, is conscious or unconscious and whether this detection is immediate or delayed. To achieve these goals, participants answered anomalous and nonanomalous questions as their reading times for words were recorded. Comparisons between detected versus undetected anomalies revealed slower reading times for detected anomalies-a finding that suggests that people immediately and consciously detected anomalies. Further, comparisons between first and second words following undetected anomalies versus nonanomalous controls revealed some slower reading times for first and second words-a finding that suggests that people may have unconsciously detected anomalies but this detection was delayed. Taken together, these findings support the idea that when we are immediately aware of a semantic anomaly (i.e., immediate conscious detection) our language processes make immediate adjustments in order to reconcile contradictory information of anomalies with surrounding text; however, even when we are not consciously aware of semantic anomalies, our language processes still make these adjustments, although these adjustments are delayed (i.e., delayed unconscious detection). PMID:25624136

  19. Anomaly-free sets of fermions

    SciTech Connect

    Batra, Puneet; /Argonne; Dobrescu, Bogdan A.; /Fermilab; Spivak, David; /UC, Berkeley, Math. Dept.

    2005-10-01

    We present new techniques for finding anomaly-free sets of fermions. Although the anomaly cancellation conditions typically include cubic equations with integer variables that cannot be solved in general, we prove by construction that any chiral set of fermions can be embedded in a larger set of fermions which is chiral and anomaly-free. Applying these techniques to extensions of the Standard Model, we find anomaly-free models that have arbitrary quark and lepton charges under an additional U(1) gauge group.

  20. ?-Wars episode I: the phantom anomaly

    NASA Astrophysics Data System (ADS)

    Intriligator, Ken; Kumar, Jason

    2002-01-01

    As pointed out, chiral non-commutative theories exist, and examples can be constructed via string theory. Gauge anomalies require the matter content of individual gauge group factors, including U(1) factors, to be non-chiral. All "bad" mixed gauge anomalies, and also all "good" (e.g., for ?0? ??) ABJ type flavor anomalies, automatically vanish in non-commutative gauge theories. We interpret this as being analogous to string theory, and an example of UV/IR mixing: non-commutative gauge theories automatically contain "closed string", Green-Schwarz fields, which cancel these anomalies.

  1. Alternative isotope enrichment processes

    SciTech Connect

    Terry, J.W.

    1983-01-01

    Alternative processes such as gas centrifugation, plasma separation, and laser excited separation are evaluated for use at the ORNL Stable Isotope Enrichment Facility. The applicabiliy of each process to the isotopic enrichment of the calutron feed material and to the selective production of isotopes is determined. The process energy demands are compared to those of the existing facilities. The isotopic enrichment of the feed material prior to a first-pass through the calutrons can result in a significant saving in energy.

  2. Electrochemical isotope effect and lithium isotope separation.

    PubMed

    Black, Jay R; Umeda, Grant; Dunn, Bruce; McDonough, William F; Kavner, Abby

    2009-07-29

    A large electrochemical isotopic effect is observed upon the electrodeposition of lithium from solutions of propylene carbonate producing isotopically light metal deposits. The magnitude of fractionation is controlled by the applied overpotential and is largest close to equilibrium. Calculated partition function ratios for tetrahedrally coordinated lithium complexes and metallic lithium predict an equilibrium fractionation close to that measured experimentally. PMID:19580315

  3. Earth Flyby and Pioneer Anomalies

    E-print Network

    M. B. Gerrard; T. J. Sumner

    2010-04-09

    Applying Newtonian dynamics in five dimensions rather than four, to a universe that is closed, isotropic and expanding,suggests that under certain circumstances an additional and previously unidentified acceleration, a_A, can arise affecting the four dimensional motion of spacecraft. The two cases of this acceleration being either real or virtual are considered. In the real case, simple estimates of a_A are shown to be in partial agreement with reported acceleration anomalies from several Earth flybys and from the Pioneer spacecraft. However, these estimates do not fully reconcile with radio Doppler tracking data. The virtual case, by contrast, appears to overcome these and other difficulties with the real case, and is discussed in an addendum. Furthermore, the virtual case has an altitude dependence which makes detection of any anomaly unlikely above ~2000 km. Equations governing this additional acceleration have been derived from first principles, without the introduction of free parameters or new constants and without amendment to the law of gravity.

  4. Anomaly Detection over Noisy Data using Learned Probability Distributions

    Microsoft Academic Search

    Eleazar Eskin

    2000-01-01

    Traditional anomaly detection techniques focus on detecting anomalies in new data after training on normal (or clean) data. In this paper we present a technique for detecting anomalies without training on normal data. We present a method for detecting anomalies within a data set that contains a large number of normal elements and relatively few anomalies. We present a mixture

  5. Challenging the Supremacy of Traffic Matrices in Anomaly Detection

    E-print Network

    Challenging the Supremacy of Traffic Matrices in Anomaly Detection Augustin Soule Thomson Fernando-wide anomaly detection techniques pro- posed in the literature define an anomaly as a statistical outlier- bones. Then, a network-wide anomaly detection method is applied to each formalism. All anomalies

  6. VIDEO ANOMALY DETECTION IN SPATIOTEMPORAL CONTEXT , Junsong Yuan2

    E-print Network

    Tsaftaris, Sotirios

    VIDEO ANOMALY DETECTION IN SPATIOTEMPORAL CONTEXT Fan Jiang1 , Junsong Yuan2 , Sotirios A are detected as anomalies. Experiments on real traffic video prove that the detected video anomalies are defined as anomaly. Despite the success of clustering-based approaches for anomaly detection

  7. Depth of principal mass anomalies contributing to the earth's geoidal undulations and gravity anomalies

    Microsoft Academic Search

    Carl Bowin

    1983-01-01

    To help decipher the distribution of the principal mass anomalies within the earth, an analysis is made of the earth's potential field by simultaneously considering both gravity and geoid anomalies. Ancillary knowledge about the earth from astronomical, angular momentum, seismological, and plate tectonic studies aids in deciding between deep or broad shallow?mass anomalies as the causative source of certain potential

  8. Isotopically controlled semiconductors

    SciTech Connect

    Haller, Eugene E.

    2001-12-21

    Semiconductor bulk crystals and multilayer structures with controlled isotopic composition have attracted much scientific and technical interest in the past few years. Isotopic composition affects a large number of physical properties, including phonon energies and lifetimes, bandgaps, the thermal conductivity and expansion coefficient and spin-related effects. Isotope superlattices are ideal media for self-diffusion studies. In combination with neutron transmutation doping, isotope control offers a novel approach to metal-insulator transition studies. Spintronics, quantum computing and nanoparticle science are emerging fields using isotope control.

  9. Generation of Radixenon Isotopes

    SciTech Connect

    McIntyre, Justin I.; Bowyer, Ted W.; Hayes, James C.; Heimbigner, Tom R.; Morris, Scott J.; Panisko, Mark E.; Pitts, W. K.; Pratt, Sharon L.; Reeder, Paul L.; Thomas, Charles W.

    2003-06-30

    Pacific Northwest National Laboratory has developed an automated system for separating Xe from air and can detect the following radioxenon isotopes, 131mXe, 133mXe, 133Xe, and 135Xe. This report details the techniques used to generate the various radioxenon isotopes that are used for the calibration of the detector as well as other isotopes that have the potential to interfere with the fission produced radioxenon isotopes. Fission production is covered first using highly enriched uranium followed by a description and results from an experiment to produce radioxenon isotopes from neutron activation of ambient xenon.

  10. Thulium anomalies and rare earth element patterns in meteorites and Earth: Nebular fractionation and the nugget effect

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Pourmand, Ali

    2015-08-01

    This study reports the bulk rare earth element (REEs, La-Lu) compositions of 41 chondrites, including 32 falls and 9 finds from carbonaceous (CI, CM, CO and CV), enstatite (EH and EL) and ordinary (H, L and LL) groups, as well as 2 enstatite achondrites (aubrite). The measurements were done in dynamic mode using multi-collector inductively coupled plasma mass spectrometers (MC-ICPMS), allowing precise quantification of mono-isotopic REEs (Pr, Tb, Ho and Tm). The CI-chondrite-normalized REE patterns (LaN/LuN; a proxy for fractionation of light vs. heavy REEs) and Eu anomalies in ordinary and enstatite chondrites show more scatter in more metamorphosed (petrologic types 4-6) than in unequilibrated (types 1-3) chondrites. This is due to parent-body redistribution of the REEs in various carrier phases during metamorphism. A model is presented that predicts the dispersion of elemental and isotopic ratios due to the nugget effect when the analyzed sample mass is limited and elements are concentrated in minor grains. The dispersion in REE patterns of equilibrated ordinary chondrites is reproduced well by this model, considering that REEs are concentrated in 200 ?m-size phosphates, which have high LaN/LuN ratios and negative Eu anomalies. Terrestrial rocks and samples from ordinary and enstatite chondrites display negative Tm anomalies of ?-4.5% relative to CI chondrites. In contrast, CM, CO and CV (except Allende) show no significant Tm anomalies. Allende CV chondrite shows large excess Tm (?+10%). These anomalies are similar to those found in group II refractory inclusions in meteorites but of much smaller magnitude. The presence of Tm anomalies in meteorites and terrestrial rocks suggests that either (i) the material in the inner part of the solar system was formed from a gas reservoir that had been depleted in refractory dust and carried positive Tm anomalies or (ii) CI chondrites are enriched in refractory dust and are not representative of solar composition for refractory elements. A new reference composition relevant to inner solar system bodies (CI?) is calculated by subtracting 0.15% of group II refractory inclusions to CI. The observed Tm anomalies in ordinary and enstatite chondrites and terrestrial rocks, relative to carbonaceous chondrites, indicate that material akin to carbonaceous chondrites must have represented a small fraction of the constituents of the Earth. Tm anomalies may be correlated with Ca isotopic fractionation in bulk planetary materials as they are both controlled by addition or removal of refractory material akin to fine-grained group II refractory inclusions.

  11. Potential of metal-organic frameworks for separation of xenon and krypton.

    PubMed

    Banerjee, Debasis; Cairns, Amy J; Liu, Jian; Motkuri, Radha K; Nune, Satish K; Fernandez, Carlos A; Krishna, Rajamani; Strachan, Denis M; Thallapally, Praveen K

    2015-02-17

    CONSPECTUS: The total world energy demand is predicted to rise significantly over the next few decades, primarily driven by the continuous growth of the developing world. With rapid depletion of nonrenewable traditional fossil fuels, which currently account for almost 86% of the worldwide energy output, the search for viable alternative energy resources is becoming more important from a national security and economic development standpoint. Nuclear energy, an emission-free, high-energy-density source produced by means of controlled nuclear fission, is often considered as a clean, affordable alternative to fossil fuel. However, the successful installation of an efficient and economically viable industrial-scale process to properly sequester and mitigate the nuclear-fission-related, highly radioactive waste (e.g., used nuclear fuel (UNF)) is a prerequisite for any further development of nuclear energy in the near future. Reprocessing of UNF is often considered to be a logical way to minimize the volume of high-level radioactive waste, though the generation of volatile radionuclides during reprocessing raises a significant engineering challenge for its successful implementation. The volatile radionuclides include but are not limited to noble gases (predominately isotopes of Xe and Kr) and must be captured during the process to avoid being released into the environment. Currently, energy-intensive cryogenic distillation is the primary means to capture and separate radioactive noble gas isotopes during UNF reprocessing. A similar cryogenic process is implemented during commercial production of noble gases though removal from air. In light of their high commercial values, particularly in lighting and medical industries, and associated high production costs, alternate approaches for Xe/Kr capture and storage are of contemporary research interest. The proposed pathways for Xe/Kr removal and capture can essentially be divided in two categories: selective absorption by dissolution in solvents and physisorption on porous materials. Physisorption-based separation and adsorption on highly functional porous materials are promising alternatives to the energy-intensive cryogenic distillation process, where the adsorbents are characterized by high surface areas and thus high removal capacities and often can be chemically fine-tuned to enhance the adsorbate-adsorbent interactions for optimum selectivity. Several traditional porous adsorbents such as zeolites and activated carbon have been tested for noble gas capture but have shown low capacity, selectivity, and lack of modularity. Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are an emerging class of solid-state adsorbents that can be tailor-made for applications ranging from gas adsorption and separation to catalysis and sensing. Herein we give a concise summary of the background and development of Xe/Kr separation technologies with a focus on UNF reprocessing and the prospects of MOF-based adsorbents for that particular application. PMID:25479165

  12. Krypton-81 in groundwater of the Culebra Dolomite near the Waste Isolation Pilot Plant, New Mexico

    NASA Astrophysics Data System (ADS)

    Sturchio, Neil C.; Kuhlman, Kristopher L.; Yokochi, Reika; Probst, Peter C.; Jiang, Wei; Lu, Zheng-Tian; Mueller, Peter; Yang, Guo-Min

    2014-05-01

    The Waste Isolation Pilot Plant (WIPP) in New Mexico is the first geologic repository for disposal of transuranic nuclear waste from defense-related programs of the US Department of Energy. It is constructed within halite beds of the Permian-age Salado Formation. The Culebra Dolomite, confined within Rustler Formation evaporites overlying the Salado Formation, is a potential pathway for radionuclide transport from the repository to the accessible environment in the human-disturbed repository scenario. Although extensive subsurface characterization and numerical flow modeling of groundwater has been done in the vicinity of the WIPP, few studies have used natural isotopic tracers to validate the flow models and to better understand solute transport at this site. The advent of Atom-Trap Trace Analysis (ATTA) has enabled routine measurement of cosmogenic 81Kr (half-life 229,000 yr), a near-ideal tracer for long-term groundwater transport. We measured 81Kr in saline groundwater sampled from two Culebra Dolomite monitoring wells near the WIPP site, and compared 81Kr model ages with reverse particle-tracking results of well-calibrated flow models. The 81Kr model ages are ~ 130,000 and ~ 330,000 yr for high-transmissivity and low-transmissivity portions of the formation, respectively. Compared with flow model results which indicate a relatively young mean hydraulic age (~ 32,000 yr), the 81Kr model ages imply substantial physical attenuation of conservative solutes in the Culebra Dolomite and provide limits on the effective diffusivity of contaminants into the confining aquitards.

  13. Spectral Methods for Magnetic Anomalies

    NASA Astrophysics Data System (ADS)

    Parker, R. L.; Gee, J. S.

    2013-12-01

    Spectral methods, that is, those based in the Fourier transform, have long been employed in the analysis of magnetic anomalies. For example, Schouten and MaCamy's Earth filter is used extensively to map patterns to the pole, and Parker's Fourier transform series facilitates forward modeling and provides an efficient algorithm for inversion of profiles and surveys. From a different, and perhaps less familiar perspective, magnetic anomalies can be represented as the realization of a stationary stochastic process and then statistical theory can be brought to bear. It is vital to incorporate the full 2-D power spectrum, even when discussing profile data. For example, early analysis of long profiles failed to discover the small-wavenumber peak in the power spectrum predicted by one-dimensional theory. The long-wavelength excess is the result of spatial aliasing, when energy leaks into the along-track spectrum from the cross-track components of the 2-D spectrum. Spectral techniques may be used to improve interpolation and downward continuation of survey data. They can also evaluate the reliability of sub-track magnetization models both across and and along strike. Along-strike profiles turn out to be surprisingly good indicators of the magnetization directly under them; there is high coherence between the magnetic anomaly and the magnetization over a wide band. In contrast, coherence is weak at long wavelengths on across-strike lines, which is naturally the favored orientation for most studies. When vector (or multiple level) measurements are available, cross-spectral analysis can reveal the wavenumber interval where the geophysical signal resides, and where noise dominates. One powerful diagnostic is that the phase spectrum between the vertical and along-path components of the field must be constant 90 degrees. To illustrate, it was found that on some very long Project Magnetic lines, only the lowest 10% of the wavenumber band contain useful geophysical signal. In this case the spectra and cross spectra show that the source of the noise is instability in the gyro platform. Spectral techniques should always be applied to vector data in order to avoid overinterpretation of short-wavelength features.

  14. Axial anomaly of QED in a strong magnetic field and noncommutative anomaly

    E-print Network

    N. Sadooghi; A. Jafari Salim

    2006-10-07

    The Adler-Bell-Jackiw (ABJ) anomaly of a 3+1 dimensional QED is calculated in the presence of a strong magnetic field. It is shown that in the regime with the lowest Landau level (LLL) dominance a dimensional reduction from D=4 to D=2 dimensions occurs in the longitudinal sector of the low energy effective field theory. In the chiral limit, the resulting anomaly is therefore comparable with the axial anomaly of a two dimensional massless Schwinger model. It is further shown that the U(1) axial anomaly of QED in a strong magnetic field is closely related to the ``nonplanar'' axial anomaly of a conventional noncommutative QED.

  15. Finding Hyperspectral Anomalies Using Multivariate Outlier Detection

    Microsoft Academic Search

    Timothy E. Smetek; Kenneth W. Bauer

    2007-01-01

    This research demonstrates the adverse implications of using non-robust statistical methods for detecting anomalies in hyperspectral image data, and proposes the use of multivariate outlier detection methods as an alternative detection strategy. Existing outlier detection methods are adapted for use in a hyperspectral image context, and their performance is compared to the benchmark RX detector and a cluster-based anomaly detector.

  16. Anomaly Detection and Reconstruction From Random Projections

    Microsoft Academic Search

    James E. Fowler; Qian Du

    2012-01-01

    Compressed-sensing methodology typically employs random projections simultaneously with signal acquisition to accomplish dimensionality reduction within a sensor device. The effect of such random projections on the preservation of anomalous data is investigated. The popular RX anomaly detector is derived for the case in which global anomalies are to be identified directly in the random-projection domain, and it is determined via

  17. Limb anomalies in the CHARGE association

    Microsoft Academic Search

    P Meinecke; A Polke; P Schmiegelow

    1989-01-01

    We report a male infant with iris coloboma, choanal atresia, postnatal retardation of growth and psychomotor development, genital anomaly, ear anomaly, and anal atresia. In addition, there was cutaneous syndactyly and nail hypoplasia of the second and third fingers on the right and hypoplasia of the left second finger nail. Comparable observations have rarely been reported and possibly represent genetic

  18. Are Flyby Anomalies an ASTG Phenomenon?

    Microsoft Academic Search

    G. G. Nyambuya

    2008-01-01

    This reading expounds with expediency on the recently proposed Azimuthally Symmetric Theory of Gravitation (ASTG) set-up earlier. At its inspection, it was demonstrated that the ASTG is capable (among others solar anomalies) of explaining the precession of the perihelion of solar planets. In the present, we show that the ASTG is capable of explaining the puzzling observations of flyby anomalies,

  19. Revisiting Gravitational Anomalies and a Potential Solution

    Microsoft Academic Search

    P. A. Murad

    2009-01-01

    Gravitational anomalies require investigation and resolution to understand the space environment if man is to travel beyond trans-lunar or trans-Mars region. This paper will provide a framework for further and more detailed evaluations. These anomalies include, a slight change in the sun's gravitational attraction observed by two Pioneer probes based upon trajectory deviations detected after being in flight for over

  20. Photodiode and photomultiplier areal sensitivity anomalies

    NASA Technical Reports Server (NTRS)

    Youngbluth, O., Jr.

    1977-01-01

    Several silicon photodiodes and photomultipliers were tested to determine signal variations as a light spot was scanned over the photosensitive surface of these detectors. Qualitative and quantitative data is presented to demonstrate the areal sensitivity anomalies. These anomalies are related back to the fabrication techniques of the manufacturers.

  1. Magnetic resonance images of neuronal migration anomalies.

    PubMed

    Jaw, T S; Sheu, R S; Liu, G C; Chou, M S

    1998-08-01

    Neuronal migration anomalies are a spectrum of brain malformations caused by insults to migrating neuroblasts during the sixth week to fifth month of gestation. To study the characteristics of MRI findings in migration anomalies, MR images of 36 patients (28 children and 8 adults) with migration anomalies were evaluated. Five patients had lissencephaly, eight had pachygyria, twelve had schizencephaly, six had heterotopias of gray matter, three had hemimegalencephaly, and two had polymicrogyria. The frequency of migration anomalies was 0.51% of all cranial MRI studies and 1.21% of pediatric cranial MRI studies at our hospital. The major clinical presentations of these patients were seizure (64%), development delay (42%), motor deficits (42%) and mental retardation (25%). Twenty-five patients (69%) associated with other brain anomalies, including: other migration anomalies in 12 cases (33%), absence of the septum pellucidum in 10 cases (28%), Dandy-Walker malformation/variant in 5 cases, arachnoid cyst in 4 cases, agenesis of the corpus callosum in 3 cases, holoprosencephaly in 2 cases, mega cisterna magna in 1 case and cephalocele in 1 case. Some of them presented with multiple complicated anomalies. As MR imaging provides superb gray-white matter distinction, details of cortical anatomy and multiplanar capability, it can clearly delineate the detail morphologic changes of the brain caused by neuronal migration disorders as well as the associated anomalies. PMID:9780601

  2. Proactive anomaly detection using distributed intelligent agents

    Microsoft Academic Search

    Marina Thottan; Chuanyi Ji

    1998-01-01

    Proactive network anomaly detection is crucial to provide quality of service guarantees for future networks. We characterize a set of proactively detectable anomalies in terms of the management information base variables. The time series data obtained from these variables are analyzed by an intelligent agent, which is a simple and lightweight signal processor. The agent provides real-time proactive alarms that

  3. A Classification Framework for Anomaly Detection

    Microsoft Academic Search

    Ingo Steinwart; Don R. Hush; Clint Scovel

    2005-01-01

    One way to describe anomalies is by saying that anomalies are not concentrated. This leads to the problem of finding level sets for the data generating density. We interpret this learning problem as a binary classification problem and compare the corresponding classification risk with the standard performance measure for the density level problem. In particular it turns out that the

  4. Information-Theoretic Measures for Anomaly Detection

    Microsoft Academic Search

    Wenke Lee; Dong Xiang

    2001-01-01

    Anomaly detection is an essential component of the pro- tection mechanisms against novel attacks. In this pa- per, we propose to use several information-theoretic mea- sures, namely, entropy, conditional entropy, relative condi- tional entropy, information gain, and information cost for anomaly detection. These measures can be used to describe the characteristics of an audit data set, suggest the appro- priate

  5. Sensitivity of PCA for traffic anomaly detection

    Microsoft Academic Search

    Haakon Ringberg; Augustin Soule; Jennifer Rexford; Christophe Diot

    2007-01-01

    Detecting anomalous traffic is a crucial part of managing IP networks. In recent years, network-wide anomaly de- tection based on Principal Component Analysis (PCA) has emerged as a powerful method for detecting a wide vari- ety of anomalies. We show that tuning PCA to operate effectively in practice is difficult and requires more robust techniques than have been presented thus

  6. Anomaly detection and classification for hyperspectral imagery

    Microsoft Academic Search

    Chein-I. Chang; Shao-Shan Chiang

    2002-01-01

    Anomaly detection becomes increasingly important in hyperspectral image analysis, since hyperspectral imagers can now uncover many material substances which were previously unresolved by multispectral sensors. Two types of anomaly detection are of interest and considered in this paper. One was previously developed by Reed and Yu to detect targets whose signatures are distinct from their surroundings. Another was designed to

  7. Anomaly intrusion detection in wireless sensor networks

    Microsoft Academic Search

    Vijay Bhuse; Ajay Gupta

    2006-01-01

    We propose lightweight methods to detect anomaly intrusions in wireless sensor networks (WSNs). The main idea is to reuse the already available system information that is generated at various layers of a network stack. To the best of our knowledge, this is the first such approach for anomaly intrusion detection in WSNs.

  8. Disparity : scalable anomaly detection for clusters.

    SciTech Connect

    Desai, N.; Bradshaw, R.; Lusk, E.

    2008-01-01

    In this paper, we describe disparity, a tool that does parallel, scalable anomaly detection for clusters. Disparity uses basic statistical methods and scalable reduction operations to perform data reduction on client nodes and uses these results to locate node anomalies. We discuss the implementation of disparity and present results of its use on a SiCortex SC5832 system.

  9. Benchmarking Anomaly-Based Detection Systems

    Microsoft Academic Search

    Roy A. Maxion; Kymie M. C. Tan

    2000-01-01

    Anomaly detection is a key element of intrusion- detection and other detection systems in which pertur- bations of normal behavior suggest the presence of in- tentionally or unintentionally induced attacks, faults, defects, etc. Because most anomaly detectors are based on probabilistic algorithms that exploit the intrinsic structure, or regularity, embedded in data logs, a fun- damental question is whether or

  10. Video Behavior Profiling for Anomaly Detection

    Microsoft Academic Search

    Tao Xiang; Shaogang Gong

    2008-01-01

    This paper aims to address the problem of modelling video behaviour captured in surveillance videos for the applications of online normal behaviour recognition and anomaly detection. A novel framework is developed for automatic behaviour profiling an d online anomaly sampling\\/detection without any manual labelling of the training dataset. The framework consists of the following key components: (1) A compact and

  11. Overgrowth syndromes with complex vascular anomalies.

    PubMed

    Uller, Wibke; Fishman, Steven J; Alomari, Ahmad I

    2014-08-01

    Management of overgrowth syndromes with complex vascular anomalies is challenging. Careful analysis of the various clinical features by an interdisciplinary team of physicians experienced in this field is paramount to proper diagnostic and therapeutic approaches. In this article, we focus on the spectrum of the clinical presentation and the management strategies of the most common overgrowth syndromes with complex vascular anomalies. PMID:25241100

  12. Anomaly Detection for Cybersecurity of the Substations

    Microsoft Academic Search

    Chee-Wooi Ten; Junho Hong; Chen-Ching Liu

    2011-01-01

    Cybersecurity of the substations in a power system is a major issue as the substations become increasingly dependent on computer and communication networks. This paper is concerned with anomaly detection in the computer network environment of a substation. An anomaly inference algorithm is proposed for early detection of cyber-intrusions at the substations. The potential sce- nario of simultaneous intrusions launched

  13. Topological Anomaly Detection Performance with Multispectral Polarimetric Imagery

    E-print Network

    Gartley, Michael G.

    Topological Anomaly Detection Performance with Multispectral Polarimetric Imagery M.G. Gartley, W to anomaly detection, which leverages topology theory, applied to spectral polarimetric imagery. Detection and Topolog- ical Anomaly Detection (TAD) approaches. We will also present detailed results examining

  14. Gravitational Anomalies in Noncommutative Field Theory

    E-print Network

    Sendic Estrada-Jimenez; Hugo Garcia-Compean; Carlos Soto-Campos

    2004-04-14

    Gravitational axial and chiral anomalies in a noncommutative space are examined through the explicit perturbative computation of one-loop diagrams in various dimensions. The analysis depend on how gravity is coupled to noncommutative matter fields. Delbourgo-Salam computation of the gravitational axial anomaly contribution to the pion decay into two photons, is studied in detail in this context. In the process we show that the two-dimensional chiral pure gravitational anomaly does not receive noncommutative corrections. Pure gravitational chiral anomaly in 4k+2 dimensions with matter fields being chiral fermions of spin-1/2 and spin-3/2, is discussed and a noncommutative correction is found in both cases. Mixed anomalies are finally considered in both cases.

  15. Detecting Flow Anomalies in Distributed Systems

    E-print Network

    Chua, Freddy Chong Tat; Huberman, Bernardo A

    2014-01-01

    Deep within the networks of distributed systems often contain anomalies that affect its efficiency and performance. These anomalies are difficult to detect because the distributed systems may not have sufficient sensors to monitor the flow of traffic within the interconnected nodes of the networks. Without early detection and making corrections, these anomalies may aggravate over time and could possibly cause disastrous outcomes in the system in the unforeseeable future. Using only coarse-grained information from the two end points of network flows, we propose a network transmission model and a localization algorithm, to detect the location of anomalies and rank them using a proposed metric within distributed systems. We evaluate our approach on passengers' records of an urbanized city's public transportation system and correlate our findings with passengers' postings on social media microblogs. Our experiments show that the metric derived using our localization algorithm gives a better ranking of anomalies a...

  16. A New, Principled Approach to Anomaly Detection

    SciTech Connect

    Ferragut, Erik M [ORNL; Laska, Jason A [ORNL; Bridges, Robert A [ORNL

    2012-01-01

    Intrusion detection is often described as having two main approaches: signature-based and anomaly-based. We argue that only unsupervised methods are suitable for detecting anomalies. However, there has been a tendency in the literature to conflate the notion of an anomaly with the notion of a malicious event. As a result, the methods used to discover anomalies have typically been ad hoc, making it nearly impossible to systematically compare between models or regulate the number of alerts. We propose a new, principled approach to anomaly detection that addresses the main shortcomings of ad hoc approaches. We provide both theoretical and cyber-specific examples to demonstrate the benefits of our more principled approach.

  17. Regional magnetic anomaly constraints on continental rifting

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Olivier, R.; Bentley, C. R.

    1985-01-01

    Radially polarized MAGSAT anomalies of North and South America, Europe, Africa, India, Australia and Antarctica demonstrate remarkably detailed correlation of regional magnetic lithospheric sources across rifted margins when plotted on a reconstruction of Pangea. These major magnetic features apparently preserve their integrity until a superimposed metamorphoric event alters the magnitude and pattern of the anomalies. The longevity of continental scale magnetic anomalies contrasts markedly with that of regional gravity anomalies which tend to reflect predominantly isostatic adjustments associated with neo-tectonism. First observed as a result of NASA's magnetic satellite programs, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans. Accordingly, satellite magnetic observations provide a further tool for investigating continental drift to compliment other lines of evidence in paleoclimatology, paleontology, paleomagnetism, and studies of the radiometric ages and geometric fit of the continents.

  18. Magnesium isotopic variations in hibonite from the Murchison meteorite - An ion microprobe study

    NASA Technical Reports Server (NTRS)

    Macdougall, J. D.; Phinney, D.

    1979-01-01

    Ion microprobe measurements show that some hibonite crystals from refractory-rich inclusions in Murchison contain isotopically anomalous Mg. The observed effects include: (1) the largest mass fractionation ever observed in nature for this element, about 10% per mass unit; (2) small Mg-26 excesses; (3) isotopic variability on a scale of microns or less in individual grains. These observations are corroborative evidence for the primitiveness of the Murchison inclusions. More importantly, they indicate that the types of Mg isotopic anomalies previously observed in Allende and Leoville inclusions are not confined to CV meteorites.

  19. Triangle Anomalies from Einstein Manifolds

    E-print Network

    Sergio Benvenuti; Leopoldo A. Pando Zayas; Yuji Tachikawa

    2006-07-20

    The triangle anomalies in conformal field theory, which can be used to determine the central charge a, correspond to the Chern-Simons couplings of gauge fields in AdS under the gauge/gravity correspondence. We present a simple geometrical formula for the Chern-Simons couplings in the case of type IIB supergravity compactified on a five-dimensional Einstein manifold X. When X is a circle bundle over del Pezzo surfaces or a toric Sasaki-Einstein manifold, we show that the gravity result is in perfect agreement with the corresponding quiver gauge theory. Our analysis reveals an interesting connection with the condensation of giant gravitons or dibaryon operators which effectively induces a rolling among Sasaki-Einstein vacua.

  20. Hot Flow Anomalies at Venus

    NASA Astrophysics Data System (ADS)

    Collinson, G. A.; Sibeck, D. G.; Masters, A.; Shane, N.; Slavin, J. A.; Coates, A. J.; Zhang, T.; Boardsen, S. A.; Moore, T. E.; Barabash, S.

    2011-12-01

    We present a multi-instrument study of a Hot Flow Anomaly (HFA) observed by the Venus Express spacecraft in the Venutian foreshock, expanding on an initial study by Slavin et al [2009] that employed magnetometer observations of an HFA-like event during the flyby of NASA's Messenger spacecraft. Whilst the Messenger events were indicative of an HFA, they were unable to demonstrate the unambiguous signatures of plasma heating or deflection due to the paucity of data. We examine the complex internal structure of a Venutian HFA on the 22nd of March 2008, incorporating both Venus Express magnetometer and ASPERA plasma observations to demonstrate the presence of plasma heating within one such event. Centered on an interplanetary discontinuity and bounded by shock, the properties of this event are consistent with those of HFA's observed at other planets within the Solar System. Finally, we present a discussion of the implications of an HFA on the planet Venus.

  1. Polaronic and Nonadiabatic Phase Diagram from Anomalous Isotope Effects M. Capone,2

    E-print Network

    Cappelluti, Emmanuele

    Polaronic and Nonadiabatic Phase Diagram from Anomalous Isotope Effects P. Paci,1 M. Capone,2 E and of the dressed phonon frequency are sizable also far away from the polaronic crossover and mark the importance, not related to polaronic features, where the IEs attain their largest anomalies. DOI: 10.1103/PhysRevLett.94

  2. Uranium-234 anomalies in corals older than 150,000 years

    SciTech Connect

    Bard, E. (CNRS-CEA, Gif-sur-Yvette (France) Columbia Univ., Palisades, NY (United States)); Fairbanks, R.G.; Zindler, A. (Columbia Univ., Palisades, NY (United States)); Hamelin, B. (Columbia Univ., Palisades, NY (United States) Univ. Aix-Marseille III (France)); Hoang, C.T. (CNRS-CEA, Gif-sur-Yvette (France))

    1991-08-01

    The authors present new precise U-Th ages of well-preserved coral specimens collected from the island of Barbados, West Indies, and the atoll of Mururoa, French Polynesia. Their new data confirm the ages attributed to oxygen isotope stage 7 in the framework of the Milankovitch theory. By using thermal ionization mass spectrometry (TIMS), it is also possible to quantify precisely the [sup 234]U/[sup 238]U ratios in corals. Samples older than 150 kyr B.P. are shown to be characterized by significant excesses of [sup 234]U relative to the uranium isotopic composition expected if the corals grew in present-day sea water. Assuming that the [sup 230]Th-ingrowth ages are accurate, these anomalies translate into high initial [sup 234]U/[sup 238]U ratios: about 1.2 at 200 kyr and up to 1.5 at about 450 kyr B.P. They propose that the anomalies result from both diagenetic addition and replacement of U and possibly from global changes in the [sup 234]U/[sup 238]U composition of the sea water through time. The [sup 234]U anomalies cast doubt on the accuracy of the classical [sup 230]Th-ingrowth dating method in old corals, and in particular for the use of measured [sup 234]U/[sup 238]U ratios alone to date corals older than 150 kyr.

  3. The prevalence of congenital anomalies in Europe.

    PubMed

    Dolk, Helen; Loane, Maria; Garne, Ester

    2010-01-01

    EUROCAT (European Surveillance of Congenital Anomalies) is the network of population-based registers of congenital anomaly in Europe, with a common protocol and data quality review, covering 1.5 million annual births in 22 countries. EUROCAT recorded a total prevalence of major congenital anomalies of 23.9 per 1,000 births for 2003-2007. 80% were livebirths. 2.5% of livebirths with congenital anomaly died in the first week of life. 2.0% were stillbirths or fetal deaths from 20 weeks gestation. 17.6% of all cases were terminations of pregnancy following prenatal diagnosis (TOPFA). Thus, congenital anomalies overwhelmingly concern children surviving the early neonatal period, who have important medical, social or educational needs. The prevalence of chromosomal anomalies was 3.6 per 1,000 births, contributing 28% of stillbirths/fetal deaths from 20 weeks gestation with congenital anomaly, and 48% of all TOPFA. Congenital heart defects (CHD) were the most common non-chromosomal subgroup, at 6.5 per 1,000 births, followed by limb defects (3.8 per 1,000), anomalies of urinary system (3.1 per 1,000) and nervous system defects (2.3 per 1,000). In 2004, perinatal mortality associated with congenital anomaly was 0.93 per 1,000 births, and TOPFA 4.4 per 1,000 births, with considerable country variation. Primary prevention of congenital anomalies in the population based on controlling environmental risk factors is a crucial policy priority, including preconceptional care and whole population approaches. PMID:20824455

  4. Isotopic and chemical systematics of river waters

    SciTech Connect

    Goldstein, S.J.

    1987-01-01

    The isotopic composition of Nd and Sr and the concentration of the rare earth elements (REE), Rb, and Sr are reported for the dissolved and suspended load of rivers from North America, Australia, Japan, the Philippines, South America, and Pakistan. Nd and light REE are mobilized in solution in rivers of low pH, whereas Sr concentrations are generally determined by the degree of chemical weathering of source rocks. The REE pattern of the dissolved load of rivers is sensitive to pH, with heavy REE enrichments and negative Ce anomalies for alkaline rivers. The isotopic composition of Nd and Sr in the dissolved load of rivers is mainly controlled by the age of materials in a drainage basin and preferential weathering of marine precipitates. Rivers appear to be the dominant source of these elements in the oceans. Estuarine removal processes lower the actual river flux of dissolved REE to the oceans by 70% for the light REE and 40% for the heavy REE. A Sr isotopic mass balance for modern seawater yields a hydrothermal water of 2.9 x 10/sup 16/ g/yr. Suspended load data directly reflect the Sm-Nd isotopic systematics and REE systematics of upper continental crust exposed to weathering. Average Sm-Nd parameters estimated for the upper crust are: Sm = 5.7 ppm. Nd = 30.0 ppm, epsilon/sub Nd/ = -15.4, and T/sub DM//sup Nd/ = 2.0 Ga. An overall relationship between epsilon/sub Nd/ and /sup 87/Sr//sup 86/Sr in river suspended loads directly reflects the relationship of these parameters in upper crust and suggests that crustal additions have become progressively depleted in incompatible elements through time. The implications of these data for interpretation of the record of Nd and Sr isotopes and REE abundances in ancient erosion products are briefly discussed.

  5. Effect of pressure on the Raman anomaly of zinc-blende CuBr and Raman spectra of high-pressure phases

    E-print Network

    Weinstein, Benard.A.

    recently at- tracted attention and were studied experimentally1­6 and in theoretical work.7­10 Usually­22 However, detailed Raman studies of CuBr as a function of isotopic composition6 have revealed that the LO composition. Two explanations for Raman anomalies in copper halides have been discussed, in particular

  6. 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.

  7. How does sea ice influence the isotopic composition of Arctic precipitation?

    NASA Astrophysics Data System (ADS)

    Faber, Anne-Katrine; Vinther, Bo; Sjolte, Jesper; Anker Pedersen, Rasmus

    2015-04-01

    Stable water isotope records from Greenland ice cores have been used extensively to reconstruct regional past climate variations. Measurements of vapor and snow samples on the Greenland ice sheet have shown that the isotopic composition of precipitation is an integrated signal of several regional climate variables rather than a unique proxy for local changes in temperature. In order to improve our knowledge of past climate changes an improved understanding of the regional climate variations on the isotope signal is essential. Here we investigate the influence of variations in sea ice cover on the isotopic composition of precipitation in present-day Arctic. We use the model isoCAM3, an isotope-equipped version of the National Center for Atmospheric Research Community Atmosphere Model version 3. Four simulations and one control simulation are performed with prescribed SSTs and sea ice using ERA-Interim data. Each of the four runs simulates the atmospheric and isotopic response to Arctic oceanic conditions for selected years within the satellite era (1979-2013). Results show that the isotopic composition of Arctic precipitation is sensitive to changes in sea ice extent, with reduced ice extent causing more enriched isotopes and vice versa. Results also show that different configurations of sea ice cover yield different distributions of the isotopic response. However, the effects of the sea ice anomalies on the modeled isotope ratios in precipitation over the Greenland ice sheet are negligible.

  8. Unexpected variations in the triple oxygen isotope composition of stratospheric carbon dioxide

    PubMed Central

    Wiegel, Aaron A.; Cole, Amanda S.; Hoag, Katherine J.; Atlas, Elliot L.; Schauffler, Sue M.; Boering, Kristie A.

    2013-01-01

    We report observations of stratospheric CO2 that reveal surprisingly large anomalous enrichments in 17O that vary systematically with latitude, altitude, and season. The triple isotope slopes reached 1.95 ± 0.05(1?) in the middle stratosphere and 2.22 ± 0.07 in the Arctic vortex versus 1.71 ± 0.03 from previous observations and a remarkable factor of 4 larger than the mass-dependent value of 0.52. Kinetics modeling of laboratory measurements of photochemical ozone–CO2 isotope exchange demonstrates that non–mass-dependent isotope effects in ozone formation alone quantitatively account for the 17O anomaly in CO2 in the laboratory, resolving long-standing discrepancies between models and laboratory measurements. Model sensitivities to hypothetical mass-dependent isotope effects in reactions involving O3, O(1D), or CO2 and to an empirically derived temperature dependence of the anomalous kinetic isotope effects in ozone formation then provide a conceptual framework for understanding the differences in the isotopic composition and the triple isotope slopes between the laboratory and the stratosphere and between different regions of the stratosphere. This understanding in turn provides a firmer foundation for the diverse biogeochemical and paleoclimate applications of 17O anomalies in tropospheric CO2, O2, mineral sulfates, and fossil bones and teeth, which all derive from stratospheric CO2. PMID:23940331

  9. The molecular physics of photolytic fractionation of sulfur and oxygen isotopes in planetary atmospheres (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, M. S.; Schmidt, J. A.; Hattori, S.; Danielache, S.; Meusinger, C.; Schinke, R.; Ueno, Y.; Nanbu, S.; Kjaergaard, H. G.; Yoshida, N.

    2013-12-01

    Atmospheric photochemistry is able to produce large mass independent anomalies in atmospheric trace gases that can be found in geological and cryospheric records. This talk will present theoretical and experimental investigations of the molecular mechanisms producing photolytic fractionation of isotopes with special attention to sulfur and oxygen. The zero point vibrational energy (ZPE) shift and reflection principle theories are starting points for estimating isotopic fractionation, but these models ignore effects arising from isotope-dependent changes in couplings between surfaces, excited state dynamics, line densities and hot band populations. The isotope-dependent absorption spectra of the isotopologues of HCl, N2O, OCS, CO2 and SO2 have been examined in a series of papers and these results are compared with experiment and ZPE/reflection principle models. Isotopic fractionation in planetary atmospheres has many interesting applications. The UV absorption of CO2 is the basis of photochemistry in the CO2-rich atmospheres of the ancient Earth, and of Mars and Venus. For the first time we present accurate temperature and isotope dependent CO2 absorption cross sections with important implications for photolysis rates of SO2 and H2O, and the production of a mass independent anomaly in the Ox reservoir. Experimental and theoretical results for OCS have implications for the modern stratospheric sulfur budget. The absorption bands of SO2 are complex with rich structure producing isotopic fractionation in photolysis and photoexcitation.

  10. Isotopic noble gas signatures released from medical isotope production facilities--simulations and measurements.

    PubMed

    Saey, Paul R J; Bowyer, Theodore W; Ringbom, Anders

    2010-09-01

    Radioxenon isotopes play a major role in confirming whether or not an underground explosion was nuclear in nature. It is then of key importance to understand the sources of environmental radioxenon to be able to distinguish civil sources from those of a nuclear explosion. Based on several years of measurements, combined with advanced atmospheric transport model results, it was recently shown that the main source of radioxenon observations are strong and regular batch releases from a very limited number of medical isotope production facilities. This paper reviews production processes in different medical isotope facilities during which radioxenon is produced. Radioxenon activity concentrations and isotopic compositions are calculated for six large facilities. The results are compared with calculated signals from nuclear explosions. Further, the outcome is compared and found to be consistent with radioxenon measurements recently performed in and around three of these facilities. Some anomalies in measurements in which (131m)Xe was detected were found and a possible explanation is proposed. It was also calculated that the dose rate of the releases is well below regulatory values. Based on these results, it should be possible to better understand, interpret and verify signals measured in the noble gas measurement systems in the International Monitoring of the Comprehensive Nuclear-Test-Ban Treaty. PMID:20447828

  11. Hamiltonian Anomalies from Extended Field Theories

    NASA Astrophysics Data System (ADS)

    Monnier, Samuel

    2015-05-01

    We develop a proposal by Freed to see anomalous field theories as relative field theories, namely field theories taking value in a field theory in one dimension higher, the anomaly field theory. We show that when the anomaly field theory is extended down to codimension 2, familiar facts about Hamiltonian anomalies can be naturally recovered, such as the fact that the anomalous symmetry group admits only a projective representation on the Hilbert space, or that the latter is really an abelian bundle gerbe over the moduli space. We include in the discussion the case of non-invertible anomaly field theories, which is relevant to six-dimensional (2, 0) superconformal theories. In this case, we show that the Hamiltonian anomaly is characterized by a degree 2 non-abelian group cohomology class, associated to the non-abelian gerbe playing the role of the state space of the anomalous theory. We construct Dai-Freed theories, governing the anomalies of chiral fermionic theories, and Wess-Zumino theories, governing the anomalies of Wess-Zumino terms and self-dual field theories, as extended field theories down to codimension 2.

  12. Thermal infrared anomalies of several strong earthquakes.

    PubMed

    Wei, Congxin; Zhang, Yuansheng; Guo, Xiao; Hui, Shaoxing; Qin, Manzhong; Zhang, Ying

    2013-01-01

    In the history of earthquake thermal infrared research, it is undeniable that before and after strong earthquakes there are significant thermal infrared anomalies which have been interpreted as preseismic precursor in earthquake prediction and forecasting. In this paper, we studied the characteristics of thermal radiation observed before and after the 8 great earthquakes with magnitude up to Ms7.0 by using the satellite infrared remote sensing information. We used new types of data and method to extract the useful anomaly information. Based on the analyses of 8 earthquakes, we got the results as follows. (1) There are significant thermal radiation anomalies before and after earthquakes for all cases. The overall performance of anomalies includes two main stages: expanding first and narrowing later. We easily extracted and identified such seismic anomalies by method of "time-frequency relative power spectrum." (2) There exist evident and different characteristic periods and magnitudes of thermal abnormal radiation for each case. (3) Thermal radiation anomalies are closely related to the geological structure. (4) Thermal radiation has obvious characteristics in abnormal duration, range, and morphology. In summary, we should be sure that earthquake thermal infrared anomalies as useful earthquake precursor can be used in earthquake prediction and forecasting. PMID:24222728

  13. A Procedure to Simultaneously Determine the Calcium, Chromium, and Titanium Isotopic Compositions of Astromaterials

    NASA Technical Reports Server (NTRS)

    Tappa, M. J.; Simon, J. I; Jordan, M. K.; Young, E. D.

    2015-01-01

    Many elements display both linear (mass-dependent) and non-linear (mass-independent) isotope anomalies (relative to a common reservoir). In early Solar System objects, with the exception of oxygen, mass-dependent isotope anomalies are most commonly thought to result from phase separation processes such as evaporation and condensation, whereas many mass-independent isotope anomalies likely reflect radiogenic ingrowth or incomplete mixing of presolar components in the proto-planetary disk. Coupling the isotopic characterization of multiple elements with differing volatilities in single objects may provide information regarding the location, source material, and/or processes involved in the formation of early Solar System solids. Here, we follow up on the work presented in, and detail new procedures developed to make high-precision multi-isotope measurements of Calcium, Chromium, and Titanium with small or limited amounts of sample using thermal ionization mass spectrometry and multi-collector ICP-MS, and characterize a suite of chondritic and terrestrial standards.

  14. Coupled W-Os-Pt isotope systematics in IVB iron meteorites: In situ neutron dosimetry for W isotope chronology

    NASA Astrophysics Data System (ADS)

    Wittig, N.; Humayun, M.; Brandon, A. D.; Huang, S.; Leya, I.

    2013-01-01

    Tungsten isotope compositions of magmatic iron meteorites yield ages of differentiation that are within ±2 Ma of the formation of CAIs, with the exception of IVB irons that plot to systematically less radiogenic compositions yielding erroneously old ages. Secondary neutron capture due to galactic cosmic ray (GCR) irradiation is known to lower the ?182W of iron meteorites, adequate correction of which requires a measure of neutron dosage which has not been available, thus far. The W, Os and Pt isotope systematics of 12 of the 13 known IVB iron meteorites were determined by MC-ICP-MS (W, Os, Pt) and TIMS (Os). On the same dissolutions that yield precise ?182W, stable Os and Pt isotopes were determined as in situ neutron dosimeters for empirical correction of the ubiquitous cosmic-ray induced burn-out of 182W in iron meteorites. The W isotope data reveal a main cluster with ?182W of ˜-3.6, but a much larger range than observed in previous studies including irons (Weaver Mountains and Warburton Range) that show essentially no cosmogenic effect on their ?182W. The IVB data exhibits resolvable negative anomalies in ?189Os (-0.6?) and complementary ?190Os anomalies (+0.4?) in Tlacotepec due to neutron capture on 189Os which has approximately the same neutron capture cross section as 182W, and captures neutrons to produce 190Os. The least irradiated IVB iron, Warburton Range, has ?189Os and ?190Os identical to terrestrial values. Similarly, Pt isotopes, which are presented as ?192Pt, ?194Pt and ?196Pt range from +4.4? to +53?, +1.54? to -0.32? and +0.73? to -0.20?, respectively, also identify Tlacotepec and Dumont as the most GCR-damaged samples. In W-Os and W-Pt isotope space, the correlated isotope data back-project toward a 0-epsilon value of ?192Pt, ?189Os and ?190Os from which a pre-GCR irradiation ?182W of -3.42±0.09 (2?) is derived. This pre-GCR irradiation ?182W is within uncertainty of the currently accepted CAI initial ?182W. The Pt and Os isotope correlations in the IVB irons are in good agreement with a nuclear model for spherical irons undergoing GCR spallation, although this model over-predicts the change of ?182W by ˜2×, indicating a need for better W neutron capture cross section determinations. A nucleosynthetic effect in ?184W in these irons of -0.14±0.08 is confirmed, consistent with the presence of Mo and Ru isotope anomalies in IVB irons. The lack of a non-GCR Os isotope anomaly in these irons requires more complex explanations for the production of W, Ru and Mo anomalies than nebular heterogeneity in the distribution of s-process to r-process nuclides.

  15. Transport of electron beams and stability of optical windows in high-power e-beam-pumped krypton fluoride lasers

    NASA Astrophysics Data System (ADS)

    Zvorykin, V. D.; Arlantsev, S. V.; Bakaev, V. G.; Rantsev, O. V.; Sergeev, P. B.; Sychugov, G. V.; Tserkovnikov, A. Yu.

    2001-10-01

    Two of the key issues of a krypton fluoride (KrF) laser driver for inertial fusion energy are the development of long life, high transparency pressure foils (to isolate vacuum in the electron beam diode from a working gas in the laser chamber), and the development of durable, stable, optical windows. Both of these problems have been studied on the single-pulse e-beam-pumped KrF laser installation GARPUN. We have measured the transport of electron beams (300 keV, 50 kA, 100 ns, 10 × 100 cm) through aluminum-beryllium and titanium foils and compared them with Monte Carlo numerical calculations. It was shown that 50-[mu]m thickness Al-Be and 20-[mu]m Ti foils had equal transmittance. However, in contrast to Ti foil, whose surface was strongly etched by fluorine, no surface modification nor fatal damages were observed for Al-Be foils after [similar]1000 laser shots and protracted fluorine exposure. We also measured the 8% reduction in the transmission of CaF2 windows under irradiation by scattered electrons when they were set at 8.5 cm apart from the e-beam-pumped region. However an applied magnetic field of [similar]0.1 T significantly reduced electron scattering both across and along the laser cell at typical pumping conditions with 1.5 atm pressure working gas. Thus the e-beam-induced absorption of laser radiation in optical windows might be fully eliminated in an e-beam-pumping scheme with magnetic field guiding.

  16. Krypton 81m ventilation/perfusion ratios (V/Q) measured in lateral decubitus in pulmonary embolism (P. E. )

    SciTech Connect

    Meignan, M.; Cinotti, L.; Harf, A.; Oliveira, L.; Simonneau, G.

    1984-01-01

    In normal subjects lateral decubitis induces in both independent (lower) and nondependent lung (upper), major changes in perfusion, ventilation and V/Q ratios which can be studied with the short life radioisotope Krypton 81m. Regional V/Q are computed from ventilation and perfusion scans, successively obtained with a gamma camera linked to a computer by continuous inhalation or infusion of this gas during tidal breathing. They were displayed as a color coded functional image. To assess the effect of posture on V/Q in P.E. and other diseases which decrease the regional perfusion, 32 patients with unilateral lung diseases were studied in supine posture and both lateral decubitis: 8 with proved P.E., (3 out of them having radiological opacity matching the perfusion defect), 9 with bullous emphysema, 6 with bronchogenic carcinoma, 9 with acute bacterial pneumonia. V/Q were computed in the region of the perfusion defect. In P.E. the mean V/Q was high (1.92 +- 0.6 SD), and did not change whatever the posture. Conversely major changes of V/Q were induced with postural changes in bullous emphysema and lung carcinoma whatever the V/Q in patient supine. In pneumonia low V/Q were observed in supine posture (.73 +- .2). They decreased significantly when the pneumonia was dependent (.53 +- .2 p < 0.02) and increased in the controlateral decubitis (1.07 +- .3, p < 0.001). Since posture has no or little effect on regional V/Q in P.E., it can be used to discriminate P.E., even in the case of radiological opacity, from other unilateral disease inducing perfusion defect.

  17. Oxygen anomaly in near surface carbon dioxide reveals deep stratospheric intrusion

    PubMed Central

    Liang, Mao-Chang; Mahata, Sasadhar

    2015-01-01

    Stratosphere-troposphere exchange could be enhanced by tropopause folding, linked to variability in the subtropical jet stream. Relevant to tropospheric biogeochemistry is irreversible transport from the stratosphere, associated with deep intrusions. Here, oxygen anomalies in near surface air CO2 are used to study the irreversible transport from the stratosphere, where the triple oxygen isotopes of CO2 are distinct from those originating from the Earth’s surface. We show that the oxygen anomaly in CO2 is observable at sea level and the magnitude of the signal increases during the course of our sampling period (September 2013-February 2014), concordant with the strengthening of the subtropical jet system and the East Asia winter monsoon. The trend of the anomaly is found to be 0.1‰/month (R2?=?0.6) during the jet development period in October. Implications for utilizing the oxygen anomaly in CO2 for CO2 biogeochemical cycle study and stratospheric intrusion flux at the surface are discussed. PMID:26081178

  18. Signatures of cross-tropopause exchange seen in the oxygen anomaly in CO2

    NASA Astrophysics Data System (ADS)

    Liang, M. C.; Mahata, S.

    2014-12-01

    Stratospheric signals, such as oxygen anomaly in CO2, are distinct from those originated from the Earth's surface. The stratospheric anomaly in CO2 was explained as a result of the exchange reaction between CO2 and O3 via the excited state oxygen atom O(1D), produced by the UV photolysis of O3. The subsequent large scale circulation (Brewer-Dobson circulation) and synoptic eddy mixing bring the anomalous CO2 to the surface, providing another opportunity for studying biogeochemical cycles involving CO2. Here, we show that the oxygen anomaly in CO2 increases during the course of our sampling period (September 2013-February 2014), concordant with the strengthening of winter monsoon and subtropical jet system. The interaction between winter monsoon and jet system could efficiently enhance the vertical mixing between upper troposphere/lower stratosphere and the lower troposphere. Moreover, an attempt to the mid-troposphere CO2 anomaly is also made. We report for the first time the triple oxygen isotope composition of CO2 in the middle troposphere collected by the CARRIBIC phase one mission. A clear correlation of D17O in CO2 with N2O mixing ratios is observed which confirms the incursion of stratospheric air to the mid-tropospheric region. This is also supported by the compact correlation with O3 mixing ratios.

  19. Oxygen anomaly in near surface carbon dioxide reveals deep stratospheric intrusion.

    PubMed

    Liang, Mao-Chang; Mahata, Sasadhar

    2015-01-01

    Stratosphere-troposphere exchange could be enhanced by tropopause folding, linked to variability in the subtropical jet stream. Relevant to tropospheric biogeochemistry is irreversible transport from the stratosphere, associated with deep intrusions. Here, oxygen anomalies in near surface air CO2 are used to study the irreversible transport from the stratosphere, where the triple oxygen isotopes of CO2 are distinct from those originating from the Earth's surface. We show that the oxygen anomaly in CO2 is observable at sea level and the magnitude of the signal increases during the course of our sampling period (September 2013-February 2014), concordant with the strengthening of the subtropical jet system and the East Asia winter monsoon. The trend of the anomaly is found to be 0.1‰/month (R(2)?=?0.6) during the jet development period in October. Implications for utilizing the oxygen anomaly in CO2 for CO2 biogeochemical cycle study and stratospheric intrusion flux at the surface are discussed. PMID:26081178

  20. Non-standard symmetries and quantum anomalies

    SciTech Connect

    Visinescu, Anca; Visinescu, Mihai [Depart. Theoretical Physics National Institute for Physics and Nuclear Engineering P.O. Box MG-6, Magurele, Bucharest (Romania)

    2008-08-31

    Quantum anomalies are investigated on curved spacetimes. The intimate relation between Killing-Yano tensors and non-standard symmetries is pointed out. The gravitational anomalies are absent if the hidden symmetry is associated to a Killing-Yano tensor. The axial anomaly in a background gravitational field is directly related with the index of the Dirac operator. In the Dirac theory on curved spaces, Killing-Yano tensors generate Dirac-type operators involved in interesting algebraic structures. The general results are applied to the 4-dimensional Euclidean Taub-NUT space.

  1. Magnetic and gravity anomalies in the Americas

    NASA Technical Reports Server (NTRS)

    Braile, L. W.; Hinze, W. J.; Vonfrese, R. R. B. (principal investigators)

    1981-01-01

    The cleaning and magnetic tape storage of spherical Earth processing programs are reported. These programs include: NVERTSM which inverts total or vector magnetic anomaly data on a distribution of point dipoles in spherical coordinates; SMFLD which utilizes output from NVERTSM to compute total or vector magnetic anomaly fields for a distribution of point dipoles in spherical coordinates; NVERTG; and GFLD. Abstracts are presented for papers dealing with the mapping and modeling of magnetic and gravity anomalies, and with the verification of crustal components in satellite data.

  2. Triangle anomaly in Weyl semi-metals

    E-print Network

    Gokce Basar; Dmitri E. Kharzeev; Ho-Ung Yee

    2014-01-08

    Weyl semimetals possess massless chiral quasi-particles, and are thus affected by the triangle anomalies. We discuss the features of the chiral magnetic and chiral vortical effects specific to Weyl semimetals, and then propose three novel phenomena caused by the triangle anomalies in this material: 1) anomaly cooling; 2) charge transport by soliton waves as described by the Burgers' equation, and 3) the shift of the BKT phase transition of superfluid vortices coupled to Weyl fermions. In addition, we establish the conditions under which the chiral magnetic current exists in real materials.

  3. [Diagnosis and management of vascular anomalies].

    PubMed

    Philandrianos, C; Degardin, N; Casanova, D; Petit, P; Bartoli, J-M; Bardot, J; Magalon, G

    2011-06-01

    Vascular anomalies are a complex pathological group. They are especially difficult to study because of confusion in the terminology used. The classification developed by the International Society for the Study of Vascular Anomalies (ISSVA) in 1996 allows using a common scientific language. There are two groups of lesions: vascular tumor and vascular malformation. The management of these anomalies is difficult and must involve an interdisciplinary approach including specialists in plastic surgery, radiology, pediatry and dermatology. We propose a simplified approach for the management of these pathologies. This approach is coming from the experience of Marseille (France) multidisciplinary team. PMID:21689587

  4. Anomaly-induced charges in baryons

    NASA Astrophysics Data System (ADS)

    Eto, Minoru; Hashimoto, Koji; Iida, Hideaki; Ishii, Takaaki; Maezawa, Yu

    2012-06-01

    We study the Skyrme model of baryons with quantum chiral anomaly of QCD in magnetic backgrounds, and suggest a possible induction of a novel structure of electric charge inside the baryons. Due to the anomaly-induced gauged Wess-Zumino term ˜(?0+multipion)E?·B?, the Skyrmions giving a local pion condensation ?(?0+multipion)??0 would produce a local charge source, in the background magnetic field B??0. Since the appearance of the total additional electric charge on the baryon looks unrealistic and surprising, we discuss the validity of our detailed evaluation of the anomaly effects.

  5. Anomaly Detection in Dynamic Networks

    SciTech Connect

    Turcotte, Melissa [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-10-14

    Anomaly detection in dynamic communication networks has many important security applications. These networks can be extremely large and so detecting any changes in their structure can be computationally challenging; hence, computationally fast, parallelisable methods for monitoring the network are paramount. For this reason the methods presented here use independent node and edge based models to detect locally anomalous substructures within communication networks. As a first stage, the aim is to detect changes in the data streams arising from node or edge communications. Throughout the thesis simple, conjugate Bayesian models for counting processes are used to model these data streams. A second stage of analysis can then be performed on a much reduced subset of the network comprising nodes and edges which have been identified as potentially anomalous in the first stage. The first method assumes communications in a network arise from an inhomogeneous Poisson process with piecewise constant intensity. Anomaly detection is then treated as a changepoint problem on the intensities. The changepoint model is extended to incorporate seasonal behavior inherent in communication networks. This seasonal behavior is also viewed as a changepoint problem acting on a piecewise constant Poisson process. In a static time frame, inference is made on this extended model via a Gibbs sampling strategy. In a sequential time frame, where the data arrive as a stream, a novel, fast Sequential Monte Carlo (SMC) algorithm is introduced to sample from the sequence of posterior distributions of the change points over time. A second method is considered for monitoring communications in a large scale computer network. The usage patterns in these types of networks are very bursty in nature and don’t fit a Poisson process model. For tractable inference, discrete time models are considered, where the data are aggregated into discrete time periods and probability models are fitted to the communication counts. In a sequential analysis, anomalous behavior is then identified from outlying behavior with respect to the fitted predictive probability models. Seasonality is again incorporated into the model and is treated as a changepoint model on the transition probabilities of a discrete time Markov process. Second stage analytics are then developed which combine anomalous edges to identify anomalous substructures in the network.

  6. Isotopes of Pennies

    NSDL National Science Digital Library

    Science Netlinks

    This lab activity from Science Netlinks is designed to explain the weighted averages that are used in average atomic mass calculations. Students can be expected to learn that isotopes of an element have different masses; that isotopes are atoms of the same element that have different numbers of neutrons; and that atomic mass is the weighted average of the naturally occurring isotopes of an element.

  7. Hybrid isotope separation scheme

    DOEpatents

    Maya, J.

    1991-06-18

    A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus. 2 figures.

  8. Isotope Ratio Mass Spectrometry.

    PubMed

    Muccio, Zeland; Jackson, Glen P

    2009-02-01

    Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic, chemical, and biological origins of substances. The ability to determine the source of an organic substance stems from the relative isotopic abundances of the elements which comprise the material. Because the isotope ratios of elements such as carbon, hydrogen, oxygen, sulfur, and nitrogen can become locally enriched or depleted through a variety of kinetic and thermodynamic factors, measurement of the isotope ratios can be used to differentiate between samples which otherwise share identical chemical compositions. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. Here, highlights of advances in instrumentation and applications within the last three years are provided to illustrate the impact of this rapidly growing area of research. Some prominent new applications include authenticating organic food produce, ascertaining whether or not African elephants are guilty of night-time raids on farmers' crops, and linking forensic drug and soil samples from a crime scene to a suspected point of origin. For the sake of brevity, we focus this Minireview on the isotope ratio measurements of lighter-elements common to organic sources; we do not cover the equally important field of inorganic isotope ratio mass spectrometry. PMID:19173039

  9. Data Mining for Anomaly Detection

    NASA Technical Reports Server (NTRS)

    Biswas, Gautam; Mack, Daniel; Mylaraswamy, Dinkar; Bharadwaj, Raj

    2013-01-01

    The Vehicle Integrated Prognostics Reasoner (VIPR) program describes methods for enhanced diagnostics as well as a prognostic extension to current state of art Aircraft Diagnostic and Maintenance System (ADMS). VIPR introduced a new anomaly detection function for discovering previously undetected and undocumented situations, where there are clear deviations from nominal behavior. Once a baseline (nominal model of operations) is established, the detection and analysis is split between on-aircraft outlier generation and off-aircraft expert analysis to characterize and classify events that may not have been anticipated by individual system providers. Offline expert analysis is supported by data curation and data mining algorithms that can be applied in the contexts of supervised learning methods and unsupervised learning. In this report, we discuss efficient methods to implement the Kolmogorov complexity measure using compression algorithms, and run a systematic empirical analysis to determine the best compression measure. Our experiments established that the combination of the DZIP compression algorithm and CiDM distance measure provides the best results for capturing relevant properties of time series data encountered in aircraft operations. This combination was used as the basis for developing an unsupervised learning algorithm to define "nominal" flight segments using historical flight segments.

  10. Mineral associations and character of isotopically anomalous organic material in the Tagish Lake carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Zega, Thomas J.; Alexander, Conel M. O.'D.; Busemann, Henner; Nittler, Larry R.; Hoppe, Peter; Stroud, Rhonda M.; Young, Andrea F.

    2010-10-01

    We report a coordinated analytical study of matrix material in the Tagish Lake carbonaceous chondrite in which the same small (?20 ?m) fragments were measured by secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS), and X-ray absorption near-edge spectroscopy (XANES). SIMS analysis reveals H and N isotopic anomalies (hotspots), ranging from hundreds to thousands of nanometers in size, which are present throughout the fragments. Although the differences in spatial resolution of the SIMS techniques we have used introduce some uncertainty into the exact location of the hotspots, in general, the H and N isotopic anomalies are spatially correlated with C enrichments, suggesting an organic carrier. TEM analysis, enabled by site-specific extraction using a focused-ion-beam scanning-electron microscope, shows that the hotspots contain an amorphous component, Fe-Ni sulfides, serpentine, and mixed-cation carbonates. TEM imaging reveals that the amorphous component occurs in solid and porous forms, EDS indicates that it contains abundant C, and EELS and XANES at the C K edge reveal that it is largely aromatic. This amorphous component is probably macromolecular C, likely the carrier of the isotopic anomalies, and similar to the material extracted from bulk samples as insoluble organic matter. However, given the large sizes of some of the hotspots, the disparity in spatial resolution among the various techniques employed in our study, and the phases with which they are associated, we cannot entirely rule out that some of the isotopic anomalies are carried by inorganic material, e.g., sheet silicates. The isotopic composition of the organic matter points to an initially primitive origin, quite possibly within cold interstellar clouds or the outer reaches of the solar protoplanetary disk. The association of organic material with secondary phases, e.g., serpentine and carbonates, suggests that the organic matter was susceptible to parent-body processing, and thus, isotopic dilution.

  11. A chemical and isotopic study of hibonite-rich refractory inclusions in primitive meteorites

    SciTech Connect

    Hinton, R.W.; Davis, A.M.; Scatena-Wachel, D.E.; Grossman, L.; Draus, R.J. (Univ. of Chicago, IL (USA))

    1988-11-01

    The ion microprobe has been used to determine the concentrations of a number of trace elements and the isotopic compositions of Ca and Mg in seven hibonite-rich refractory inclusions. Hibonite in every inclusion analyzed shows the effect of REE partitioning with other solid or liquid phases, in which hibonite is enriched in light over heavy REE compared to other coexisting phases. This partitioning causes Cl chondrite-normalized enrichments to drop by factors of 4 to 22 from lanthanum to lutetium. Fractionations due to gas-solid partitioning of REE are sometimes superimposed on the pattern produced by partitioning between condensed phases. Two inclusions, HAL and DH-H1, show evidence for formation in extremely oxidizing environments and their Ca is mass fractionated in favor of the heavy isotopes by 7 and 12{per thousand}/amu, respectively. Two corundum-hibonite inclusions show evidence of extremely high temperature gas-solid fractionation, such that the more volatile light REE are depleted as a group relative to the more refractory heavy REE. Hibonite preserves the largest nuclear isotope anomalies in Ti found to date, but there does not seem to be a simple relationship between chemical composition, isotopic mass fractionation and the sign and magnitude of nuclear isotopic anomalies in hibonite-rich inclusions. One possibility for producing a variety of chemical compositions and degrees of mass fractionation while preserving nuclear isotope anomalies is by multiple cycles of condensation and evaporation in a turbulent protoplanetary accretion disk. These cycles could also occur in a presolar nebula with large non-axisymmetric temperature and pressure distributions. Nuclear anomalies are most likely to be preserved in hibonite because hibonite is the most refractory major phase to occur commonly in meteorites.

  12. Discovery of the Titanium Isotopes

    E-print Network

    D. Meierfrankenfeld; M. Thoennessen

    2010-09-08

    Twentyfive titanium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  13. Discovery of the Indium Isotopes

    E-print Network

    S. Amos; M. Thoennessen

    2010-09-08

    Thirty-eight indium isotopes (A = 98-135) have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  14. Discovery of the Einsteinium Isotopes

    Microsoft Academic Search

    A. Bury; A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; A. Shore; M. Thoennessen

    2009-01-01

    Seventeen einsteinium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  15. Discovery of the Gold Isotopes

    E-print Network

    A. Schuh; A. Fritsch; J. Q. Ginepro; M. Heim; A. Shore; M. Thoennessen

    2009-03-10

    Thirty-six gold isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  16. Discovery of the Calcium Isotopes

    E-print Network

    J. L. Gross; M. Thoennessen

    2010-09-08

    Twenty four calcium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  17. Discovery of the Cadmium Isotopes

    E-print Network

    S. Amos; M. Thoennessen

    2009-10-22

    Thirty-seven cadmium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  18. Discovery of the Tin Isotopes

    E-print Network

    S. Amos; M. Thoennessen

    2010-09-08

    Thirty-eight tin isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  19. Discovery of the Mercury Isotopes

    E-print Network

    D. Meierfrankenfeld; M. Thoennessen

    2010-09-08

    Forty mercury isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  20. Discovery of the Barium Isotopes

    E-print Network

    A. Shore; A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; M. Thoennessen

    2009-08-13

    Thirty-eight barium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  1. Discovery of the Iron Isotopes

    E-print Network

    A. Schuh; A. Fritsch; M. Heim; A. Shore; M. Thoennessen

    2009-09-01

    Twenty-eight iron isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  2. Discovery of the Tungsten Isotopes

    E-print Network

    A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; A. Shore; M. Thoennessen

    2009-03-25

    Thirty-five tungsten isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  3. Discovery of the Einsteinium Isotopes

    E-print Network

    A. Bury; A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; A. Shore; M. Thoennessen

    2010-09-08

    Seventeen einsteinium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  4. Discovery of the Cobalt Isotopes

    E-print Network

    T. Szymanski; M. Thoennessen

    2009-09-04

    Twenty-six cobalt isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  5. Discovery of the Vanadium Isotopes

    E-print Network

    A. Shore; A. Fritsch; M. Heim; A. Schuh; M. Thoennessen

    2009-07-11

    Twenty-four vanadium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  6. Discovery of the Calcium Isotopes

    E-print Network

    Gross, J L

    2010-01-01

    Twenty four calcium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  7. Classifying gauge anomalies through symmetry-protected trivial orders and classifying gravitational anomalies through topological orders

    NASA Astrophysics Data System (ADS)

    Wen, Xiao-Gang

    2013-08-01

    In this paper, we systematically study gauge anomalies in bosonic and fermionic weak-coupling gauge theories with gauge group G (which can be continuous or discrete) in d space-time dimensions. We show a very close relation between gauge anomalies for gauge group G and symmetry-protected trivial (SPT) orders (also known as symmetry-protected topological (SPT) orders) with symmetry group G in one-higher dimension. The SPT phases are classified by group cohomology class Hd+1(G,R/Z). Through a more careful consideration, we argue that the gauge anomalies are described by the elements in Free[Hd+1(G,R/Z)]?H??d+1(BG,R/Z). The well known Adler-Bell-Jackiw anomalies are classified by the free part of Hd+1(G,R/Z) (denoted as Free[Hd+1(G,R/Z)]). We refer to other kinds of gauge anomalies beyond Adler-Bell-Jackiw anomalies as non-ABJ gauge anomalies, which include Witten SU(2) global gauge anomalies. We introduce a notion of ?-cohomology group, H??d+1(BG,R/Z), for the classifying space BG, which is an Abelian group and include Tor[Hd+1(G,R/Z)] and topological cohomology group Hd+1(BG,R/Z) as subgroups. We argue that H??d+1(BG,R/Z) classifies the bosonic non-ABJ gauge anomalies and partially classifies fermionic non-ABJ anomalies. Using the same approach that shows gauge anomalies to be connected to SPT phases, we can also show that gravitational anomalies are connected to topological orders (i.e., patterns of long-range entanglement) in one-higher dimension.

  8. New perspective on Aptian carbon isotope stratigraphy: Data from delta13C records of terrestrial organic matter

    Microsoft Academic Search

    Atsushi Ando; Takeshi Kakegawa; Reishi Takashima; Tsunemasa Saito

    2002-01-01

    Carbon isotope analyses were performed on detrital woody materials in Aptian (mid- Cretaceous) marine sediments of central Hokkaido, northern Japan. A positive delta13Cwood excursion (from -25.40\\/00 to -21.80\\/00) following a remarkable negative isotope shift is recognized in the early Aptian, and a small positive anomaly is also found in the latest Aptian. This delta13Cwood profile is exactly in phase with

  9. Relaxing Lorentz invariance in general perturbative anomalies

    SciTech Connect

    Salvio, A. [Institut de Theorie des Phenomenes Physiques, EPFL, CH-1015 Lausanne (Switzerland)

    2008-10-15

    We analyze the role of Lorentz symmetry in the perturbative nongravitational anomalies for a single family of fermions. The theory is assumed to be translational-invariant, power-counting renormalizable and based on a local action, but is allowed to have general Lorentz violating operators. We study the conservation of global and gauge currents associated with general internal symmetry groups and find, by using a perturbative approach, that Lorentz symmetry does not participate in the clash of symmetries that leads to the anomalies. We first analyze the triangle graphs and prove that there are regulators for which the anomalous part of the Ward identities exactly reproduces the Lorentz-invariant case. Then we show, by means of a regulator independent argument, that the anomaly cancellation conditions derived in Lorentz-invariant theories remain necessary ingredients for anomaly freedom.

  10. The two pioneers anomalies and universal rotation

    NASA Astrophysics Data System (ADS)

    Berman, Marcelo Samuel

    2011-12-01

    We show how to prove the two Pioneers Anomalies by means of the Godlowski et al. (arXiv:astro-ph/0404329, 2004) idea for a rotating General Relativistic Universe. The so-called clock effect is calculated.

  11. Design and Implementation of an Anomaly Detector

    SciTech Connect

    Bagherjeiran, A; Cantu-Paz, E; Kamath, C

    2005-07-11

    This paper describes the design and implementation of a general-purpose anomaly detector for streaming data. Based on a survey of similar work from the literature, a basic anomaly detector builds a model on normal data, compares this model to incoming data, and uses a threshold to determine when the incoming data represent an anomaly. Models compactly represent the data but still allow for effective comparison. Comparison methods determine the distance between two models of data or the distance between a model and a point. Threshold selection is a largely neglected problem in the literature, but the current implementation includes two methods to estimate thresholds from normal data. With these components, a user can construct a variety of anomaly detection schemes. The implementation contains several methods from the literature. Three separate experiments tested the performance of the components on two well-known and one completely artificial dataset. The results indicate that the implementation works and can reproduce results from previous experiments.

  12. Understanding Magnetic Anomalies and Their Significance.

    ERIC Educational Resources Information Center

    Shea, James H.

    1988-01-01

    Describes a laboratory exercise testing the Vine-Matthews-Morley hypothesis of plate tectonics. Includes 14 questions with explanations using graphs and charts. Provides a historical account of the current plate tectonic and magnetic anomaly theory. (MVL)

  13. Chiral anomalies, higher dimensions, and differential geometry

    Microsoft Academic Search

    Bruno Zumino; Wu Yong-Shi; A. Zee

    1984-01-01

    We determine the abelian and non-abelian chiral anomalies in 2n-dimensional spacetime by a differential geometric method which enables us to obtain the anomalies without having to calculate Feynman diagrams, as has been done by Frampton and Kephart. The advantage of this method is that the construction automatically satisfies the Wess-Zumino consistency condition, a condition which has direct physical interpretation. We

  14. 't Hooft Anomaly Matching for Discrete Symmetries

    E-print Network

    Csaba Csaki; Hitoshi Murayama

    1998-05-12

    We show how to extend the 't Hooft anomaly matching conditions to discrete symmetries. We check these discrete anomaly matching conditions on several proposed low-energy spectra of certain strongly interacting gauge theories. The excluded examples include the proposed chirally symmetric vacuum of pure N=1 supersymmetric Yang-Mills theories, certain non-supersymmetric confining theories and some self-dual N=1 supersymmetric theories based on exceptional groups.

  15. Revisiting Gravitational Anomalies and a Potential Solution

    Microsoft Academic Search

    P. A. Murad

    2009-01-01

    Gravitational anomalies require investigation and resolution to understand the space environment if man is to travel beyond trans-lunar or trans-Mars region. This paper will provide a framework for further and more detailed evaluations. These anomalies include, a slight change in the sun’s gravitational attraction observed by two Pioneer probes based upon trajectory deviations detected after being in flight for over

  16. The Anomaly Structure of Regularized Supergravity

    E-print Network

    Daniel Butter; Mary K. Gaillard

    2014-10-22

    On-shell Pauli-Villars regularization of the one-loop divergences of supergravity theories is used to study the anomaly structure of supergravity and the cancellation of field theory anomalies under a $U(1)$ gauge transformation and under the T-duality group of modular transformations in effective supergravity theories with three K\\"ahler moduli $T^i$ obtained from orbifold compactification of the weakly coupled heterotic string. This procedure requires constraints on the chiral matter representations of the gauge group that are consistent with known results from orbifold compactifications. Pauli-Villars regulator fields allow for the cancellation of all quadratic and logarithmic divergences, as well as most linear divergences. If all linear divergences were canceled, the theory would be anomaly free, with noninvariance of the action arising only from Pauli-Villars masses. However there are linear divergences associated with nonrenormalizable gravitino/gaugino interactions that cannot be canceled by PV fields. The resulting chiral anomaly forms a supermultiplet with the corresponding conformal anomaly, provided the ultraviolet cut-off has the appropriate field dependence, in which case total derivative terms, such as Gauss-Bonnet, do not drop out from the effective action. The anomalies can be partially canceled by the four-dimensional version of the Green-Schwarz mechanism, but additional counterterms, and/or a more elaborate set of Pauli-Villars fields and couplings, are needed to cancel the full anomaly, including D-term contributions to the conformal anomaly that are nonlinear in the parameters of the anomalous transformations.

  17. “Great Salinity Anomalies” in the North Atlantic

    Microsoft Academic Search

    Igor M. Belkin; Sydney Levitus; John Antonov; Svend-Aage Malmberg

    1998-01-01

    We revisited the “Great Salinity Anomaly” of the 1970s (GSA'70s; Dickson et al., 1988) and documented the newly identified “Great Salinity Anomaly” of the 1980s (hence termed GSA'80s), both propagated around the North Atlantic in a similar fashion. The advective mechanism, initially proposed to explain the observed sequence of low-salinity, low-temperature events during the GSA'70s, apparently holds also for the

  18. Viscosity anomaly in core-softened liquids

    E-print Network

    Yu. D. Fomin; V. N. Ryzhov

    2013-03-18

    The present article presents a molecular dynamics study of several anomalies of core-softened systems. It is well known that many core-softened liquids demonstrate diffusion anomaly. Usual intuition relates the diffusion coefficient to shear viscosity via Stockes-Einstein relation. However, it can break down at low temperature. In this respect it is important to see if viscosity also demonstrates anomalous behavior.

  19. Anomaly-Based Hyperspectral Image Compression

    Microsoft Academic Search

    Qian Du; Wei Zhu; James E. Fowler

    2008-01-01

    We propose a new lossy compression algorithm for hyperspectral images, which is based on spectral principal component analysis (PCA), followed by JPEG2000 (JP2K). The approach employs an anomaly-removal model in the compression process to preserve anomalous pixels. Results on two different hyperspectral image scenes show that the new algorithm not only provides good post-compression anomaly-detection performance but also improves rate-distortion

  20. ANOMALY-BASED HYPERSPECTRAL IMAGE COMPRESSION

    Microsoft Academic Search

    Qian Du; Wei Zhu; James E. Fowler

    2009-01-01

    We propose a new lossy compression algorithm for hyperspectral images, which is based on spectral principal component analysis (PCA), followed by JPEG2000 (JP2K). The approach employs an anomaly-removal model in the compression process to preserve anomalous pixels. Results on two different hyperspectral image scenes show that the new algorithm not only provides good post-compression anomaly-detection performance but also improves rate-

  1. Temporal accumulations of extreme daily meantemperature anomalies

    Microsoft Academic Search

    P. Domonkos

    2001-01-01

    Summary  ?Statistical characteristics of accumulated extreme low and high daily mean temperatures have been investigated for Hungary.\\u000a Temperature extremes over periods of a few weeks were studied using 96-year temperature records. Temperature is defined as\\u000a extreme in the lowest or highest five percent of the empirical distribution of anomalies. Recurrence frequencies of extreme\\u000a anomalies were computed at 1, 2,…, 75 days

  2. CP-violating CFT and trace anomaly

    E-print Network

    Yu Nakayama

    2012-01-26

    It is logically possible that the trace anomaly in four dimension includes the Hirzebruch-Pontryagin density in CP violating theories. Although the term vanishes at free conformal fixed points, we realize such a possibility in the holographic renormalization group and show that it is indeed possible. The Hirzebruch-Pontryagin term in the trace anomaly may serve as a barometer to understand how much CP is violated in conformal field theories.

  3. Contribution of anomalies detection and analysis on traffic engineering

    E-print Network

    Owezarski, Philippe

    , and much more. Traffic anomalies, anomaly profile, overlay network routing I. INTRODUCTION Assuring QualityContribution of anomalies detection and analysis on traffic engineering Sílvia Farraposo DEI ESTG--In this paper we present a methodology for detecting traffic anomalies. To accomplish that, and as a demarcation

  4. On the Anomalies and Schwinger Terms in Noncommutative Gauge Theories

    Microsoft Academic Search

    F. Ardalan; H. Arfaei; N. Sadooghi

    2006-01-01

    Invariant (nonplanar) anomaly of noncommutative QED is reexamined in this paper. It is found that just as in ordinary gauge theory UV regularization is needed to discover anomalies, in noncommutative case, in addition, an IR regularization is also required to exhibit the existence of invariant anomaly. Thus resolving the controversy in the value of invariant anomaly, an expression for the

  5. i\\ai"GIIS... Apollo 15 Anomalies Investigation PAGE

    E-print Network

    Rathbun, Julie A.

    ' ·~ i\\ai"GIIS... Apollo 15 Anomalies Investigation PAGE 1 OF /~-........Divl·lan DATE 10/11/71 The purpose of this ATM is to review and status the BxA effort with respect to the Apollo 15 Anomalies t '-· :·~· . . !· ·'··..'· ~· : #12;Apollo 15 Anomalies Investigation TABLE OF CONTENTS Anomalies 1. UHT/Subpackage #2 Interface 2

  6. Consistent and covariant anomalies in gauge and gravitational theories

    Microsoft Academic Search

    William A. Bardeen; Bruno Zumino

    1984-01-01

    The gauge structure of anomalies and the related currents is analyzed in detail. We construct the covariant forms for both the currents and the anomalies for general gauge theories in even-dimensional space-time. The results are then extended to determine the structure of gravitational anomalies. These can always be interpreted as anomalies for local Lorentz transformations.

  7. Effect of sampling rate and monitoring granularity on anomaly detectability

    E-print Network

    Rejaie, Reza

    Effect of sampling rate and monitoring granularity on anomaly detectability Keisuke Ishibashi of anomalies to be detected. We show that by changing the measurement granularity, we can detect anomalies even and victim of the detected anomaly. On the other hand, the latter method gives rich information but lacks

  8. Multi-criteria Anomaly Detection using Pareto Depth Analysis

    E-print Network

    Hero, Alfred O.

    Multi-criteria Anomaly Detection using Pareto Depth Analysis Ko-Jen Hsiao, Kevin S. Xu, Jeff Calder, often referred to as anomaly detection. In most anomaly detection algorithms, the dissimilarity between in the linear combina- tion. In this paper, we introduce a novel non-parametric multi-criteria anomaly detection

  9. Using Artificial Anomalies to Detect Unknown and Known Network Intrusions

    Microsoft Academic Search

    Wei Fan; Matthew Miller; Salvatore J. Stolfo; Wenke Lee; Philip K. Chan

    2001-01-01

    Intrusion detection systems (IDSs) must be capable of detecting new and unknown attacks, or anomalies. We study the problem of building detection models for both pure anomaly detection and combined misuse and anomaly detection (i.e., detection of both known and unknown in- trusions). We propose an algorithm to generate artificial anomalies to coerce the inductive learner into discovering an accurate

  10. An Efficient Cache-Based Access Anomaly Detection Scheme

    Microsoft Academic Search

    Sang Lyul Min; Jong-Deok Choi

    1991-01-01

    One of the important issues in parallel program debugging is an efficient detection ofaccess anomalies caused by uncoordinated access to shared variables. On-the-fly detection of access anomalies has the major advantage that it reports only actual anomalies during execution while static analysis methods report all the potential anomalies, many of which cannot actually materialize during execution. It also has the

  11. Group Anomaly Detection using Flexible Genre Models Liang Xiong

    E-print Network

    Schneider, Jeff

    Group Anomaly Detection using Flexible Genre Models Liang Xiong Machine Learning Department and interesting phenomena. In this paper, we study the group anomaly detection problem. Unlike traditional anomaly and turbulence data, and show that it is superior to existing approaches in detecting group anomalies. 1

  12. Congenital anomaly surveillance in England and Wales.

    PubMed

    Misra, T; Dattani, N; Majeed, A

    2006-03-01

    The National Congenital Anomaly System (NCAS) was set up in 1964, following the thalidomide epidemic, as a monitoring system designed to detect changes in the frequency of reporting of malformations. Its original aim was to detect anomalies reported within 7 days of birth. The NCAS is voluntary at all stages and covers all live- and stillbirths. It has two tiers; a 'passive system' receiving congenital anomaly notifications through a standard paper notification form, known as the SD56, and the congenital anomaly registers that send notifications electronically. Congenital anomalies are classified using the International Classification of Diseases codes and 10 monitoring groups. The Office for National Statistics performs a statistical analysis on a monthly, quarterly and annual basis, using the cumulative sum technique, which is the basis upon which surveillance alerts are raised within the system. The NCAS is now an open database where congenital anomalies can be notified whenever they are detected. The aim of this paper is to describe the current operation and uses of the NCAS based on guidelines for the evaluation of public health surveillance systems published by the Centers for Disease Control and Prevention. PMID:16337977

  13. Non-mass dependent isotope fractionation in Ozone

    NASA Astrophysics Data System (ADS)

    Robert, F.; Reinhardt, P.

    2012-04-01

    In clear contradiction with the usual isotopic fractionation (1) a non mass dependent fractionation of oxygen isotopes was reported (2) in the refractory minerals of the carbonaceous chondrites. Although this effect seems ubiquitous in the first solids at the origin of solar system oxides, its origin is still in debate. Another non-mass dependent isotopic effect was then reported for the oxygen isotopic composition of ozone produced in the laboratory (3) as well as in the stratosphere (4-5). Numerous interpretations of this effect have been proposed but no consensus has been reached up to now (6-7). The generally accepted theory is based on a modification of the standard RRKM model of unimolecular dissociation (8) where a parameter ? is adjusted for taking into account mass-independent effects without further assumptions. If this parameter is propagated to all mass dependent isotopic fractionation factors between the different isotopomers of ozone, most observations are then reproduced numerically. The aim of the present work is to propose a possible origin for ?. We will show that the quantum mechanical principle according to which identical isotopes can be treated as indistinguishable particles, may be at the origin of the isotope effect. The scattering of O + O2 ? O3*? O + O2 is modeled in a thermal gas with an activated complex O3* that is eventually stabilized in the form of ozone, depending on its lifetime. In order to illustrate the consequences of this principle, all calculations were performed in classical mechanics for 16O i.e. by neglecting the differences in the masses of the different isotopes. For a given lifetime range, the averaged lifetimes for complexes formed by reactions involving distinguishable (such as 16O + mOnO) or indistinguishable (such as 16O + 16O16O) isotopes cannot be strictly equal. We then ascribe the non mass dependent isotopic fractionation factor ? to the ratio of these lifetimes. The experimental data obtained for ozone are reproduced astonishingly well with this hypothesis. Since this effect is not restricted to ozone or to oxygen isotopes, it could have played a role in several isotopic anomalies found in meteorites.

  14. Detecting isotopic ratio outliers

    SciTech Connect

    Bayne, C.K.; Smith, D.H.

    1985-01-01

    An alternative method is proposed for improving isotopic ratio estimates. This method mathematically models pulse-count data and uses iterative reweighted Poisson regression to estimate model parameters to calculate the isotopic ratios. This computer-oriented approach provides theoretically better methods than conventional techniques to establish error limits and to identify outliers. 6 refs., 3 figs., 3 tabs.

  15. Radioactivity of Astatine Isotopes

    Microsoft Academic Search

    G. W. Barton; A. Ghiorso; I. Perlman

    1951-01-01

    A number of new neutron deficient isotopes of astatine have been identified in the mass number range 200 to 209 following the irradiation of bismuth with high energy helium ions. Their alpha-decay properties fall in line with predictions for isotopes in this region with less than 126 neutrons; that is, the alpha-energies increase with decrease in mass number. Because of

  16. (Carbon isotope fractionation inplants)

    SciTech Connect

    O'Leary, M.H.

    1990-01-01

    The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

  17. Photochemical isotope separation

    DOEpatents

    Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

    1987-01-01

    A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

  18. Laser isotope separation

    DOEpatents

    Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Munich, DE); Boyer, Keith (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM)

    1988-01-01

    A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

  19. On the Anomalies and Schwinger Terms in Noncommutative Gauge Theories

    E-print Network

    F. Ardalan; H. Arfaei; N. Sadooghi

    2006-01-05

    Invariant (nonplanar) anomaly of noncommutative QED is reexamined. It is found that just as in ordinary gauge theory UV regularization is needed to discover anomalies, in noncommutative case, in addition, an IR regularization is also required to exhibit existence of invariant anomaly. Thus resolving the controversy in the value of invariant anomaly, an expression for the unintergrated anomaly is found. Schwinger terms of the current algebra of the theory are derived.

  20. A new feature in the internal heavy isotope distribution in ozone

    NASA Astrophysics Data System (ADS)

    Bhattacharya, S. K.; Savarino, Joel; Michalski, G.; Liang, Mao-Chang

    2014-10-01

    Ozone produced by discharge or photolysis of oxygen has unusually heavy isotopic composition (18O/16O and 17O/16O ratio) which does not follow normal mass fractionation rule: ?17O ˜ 0.52*?18O, expressed as an anomaly ?17O = ?17O - 0.52*?18O. Ozone molecule being an open isosceles triangle can have the heavy isotope located either in its apex or symmetric (s) position or the base or asymmetric (as) position. Correspondingly, one can define positional isotopic enrichment, written as ?18O (s) or ?18O (as) (and similarly for ?17O) as well as position dependent isotope anomaly ?17O (s) and ?17O (as). Marcus and co-workers have proposed a semi-empirical model based in principle on the RRKM model of uni-molecular dissociation but with slight modification (departure from statistical randomness assumption for symmetrical molecules) which explains many features of ozone isotopic enrichment. This model predicts that the bulk isotope anomaly is contained wholly in the asymmetric position and the ?17O (s) is zero. Consequently, ?17O (as) = 1.5 * ?17O (bulk) (named here simply as the "1.5 rule") which has been experimentally confirmed over a range of isotopic enrichment. We now show that a critical re-analysis of the earlier experimental data demonstrates a small but significant departure from this 1.5 rule at the highest and lowest levels of enrichments. This departure provides the first experimental proof that the dynamics of ozone formation differs from a statistical model constrained only by restriction of symmetry. We speculate over some possible causes for the departure.

  1. 126Xe Anomaly in Lunar Regolith Samples: A Possible Explanation

    NASA Astrophysics Data System (ADS)

    Begemann, F.; Mathew, K. J.

    1995-09-01

    Lunar regolith samples exposed to solar radiation have been extensively studied to obtain the isotopic composition of the solar noble gases implanted into them [1, 2]. Regolithic Xe in these samples has been shown to be a mixture of a primary solar wind component with components produced in situ by cosmic ray spallation, by neutron capture reactions on I, and also by decay of extinct radionuclides (cf. e.g. [3]). In addition an essentially monoisotopic contribution at 126Xe has been observed to be present in at least some samples, its relative proportion varying from sample to sample [3]. A possible origin of this excess from the reaction 127I(n,2n)126I, followed by beta- -decay to 126Xe was suggested [3] but after considering the required iodine abundances this mechanism of production was argued against. We propose that the low energy proton reaction with Te, viz. 126Te(p,n)126I(beta-,gamma)126Xe could explain this anomaly. Since the threshold for this reaction is low (< 3 MeV) the abundant low energy protons on the lunar surface might be able to account for this anomaly. Moreover, because the same reaction on 128Te will produce 128Xe this might also account for the "rough correlation between excess 126Xe and excess 128Xe" [3]. According to available cross section data for proton energies between 10 MeV and 20 MeV the production ratio 126Xe/128Xe from (p,n)-reactions acting on natural Te is 0.8 which translates into a ratio delta 126Xe/ delta 128Xe of about 16. In order to look into the feasibility of this reaction to explain the size of the 126Xe anomaly we have irradiated Te targets with 4, 10, 14, and 17 MeV protons. Data will be presented for the cross sections that will allow to estimate whether the product (proton dose x tellurium content x cross section) yields the observed excesses. References: [1] Wieler R. et al. (1986) GCA, 50, 1997-2017. [2] Benkert J.-P. et al. (1993) JGR Planets, 98, 13147-13162. [3] Pepin R. O. et al. (1995) GCA, submitted.

  2. Electrochemical Isotope Effect and Lithium Isotope Separation Jay R. Black,

    E-print Network

    Mcdonough, William F.

    Electrochemical Isotope Effect and Lithium Isotope Separation Jay R. Black, Grant Umeda, Bruce Dunn May 19, 2009; E-mail: akavner@ucla.edu The electrochemical separation of lithium isotopes is of growing interest due to the need for pure 6 Li and 7 Li isotopes in the nuclear industry.1 Here we present

  3. Constraints on the origin and relative timing of the Trezona ?13C anomaly below the end-Cryogenian glaciation

    NASA Astrophysics Data System (ADS)

    Rose, Catherine V.; Swanson-Hysell, Nicholas L.; Husson, Jon M.; Poppick, Laura N.; Cottle, John M.; Schoene, Blair; Maloof, Adam C.

    2012-02-01

    The Neoproterozoic Era was punctuated by the 'Sturtian' (~ 710 million years ago) and 'Marinoan' (~ 635 million years ago) low-latitude glaciations. Carbonates preceding the younger Marinoan glacial succession record an ~ 18‰ negative shift in the ?13C of carbonate around the world. This 'Trezona' isotopic anomaly is the largest ?13C shift in Earth history and its origin and timing remain controversial. The ?13C anomaly could record a dramatic reorganization of Earth's carbon cycle and be linked causally to the initiation of Marinoan ice-house conditions. Alternatively, the ?13C anomaly might record secondary fluid alteration following carbonate deposition. Here we document dropstones within the carbonate sediments immediately below the Marinoan glacial diamictite in South Australia. Advancing ice sheets caused soft-sediment deformation of the beds below the glacial diamictite, as well as subglacial erosion of the carbonates beneath, showing that the Trezona ?13C values must have been acquired before glaciation. Although these stratigraphic relationships do not provide a specific mechanism to explain the Trezona ?13C anomaly, they do require that the nadir of the Trezona ?13C anomaly was recorded prior to local glacier advance and long before late-stage burial diagenesis could have occurred. Furthermore, the ?13C recovery in the Trezona Formation toward 0‰ was synchronous with the appearance of icebergs in the tropics.

  4. An ˜1500 year history of El Niño Southern Oscillation rainfall anomalies and land use for the Isthmus of Panama from speleothem calcite

    NASA Astrophysics Data System (ADS)

    Lachniet, M. S.; Burns, S. J.; Piperno, D. R.; Asmerom, Y.; Polyak, V. P.

    2003-12-01

    The history of the El Niño Southern Oscillation (ENSO) over the past two millennia remains poorly constrained. To document further the tropical paleoclimatic response to ENSO, we present a precisely-dated (180 B.C. to 1310 A.D.), high-resolution ( ˜3 yr / sample), cave calcite isotopic time series from the Isthmus of Panama, a region that experiences ENSO-forced rainfall anomalies. We show evidence for rapid and dramatic rainfall variation in southern Central America, as inferred from stalagmite ? 18O isotope stratigraphy. Isthmian convective rainfall from 550 A.D. to 1300 A.D. was both less intense and more variable than the period 180 B.C. to 550 A.D. Speleothem growth spanned the interval of the Classic Maya Collapse (750 - 950 A.D.), and provides additional evidence for dry anomalies at this time. Carbon isotopes document changing vegetation from native rainforest to grasslands and/or maize, a period of soil erosion associated with pre-Colombian agriculture, and final forest recovery. We suggest that ENSO-forced sea surface temperature anomalies in the eastern equatorial Pacific Ocean resulted in isthmian rainfall anomalies over much of the past two millennia. Our data suggest that El Niño events are associated with decreased isthmian rainfall, and that increased ENSO activity results in generally drier and more variable conditions.

  5. Search for Al-26 effects in the Allende FUN inclusion C1. [Fractionation and Unknown Nuclear anomalies

    NASA Technical Reports Server (NTRS)

    Esat, T. M.; Lee, T.; Papanastassiou, D. A.; Wasserburg, G. J.

    1978-01-01

    The Mg isotopic composition of major and minor mineral phases in the Allende inclusion C1 is reported. The results are analyzed in order to establish whether the Mg isotopic composition is the same in different phases and whether Al-26 is present in a sample which exhibited fractionation and unknown nuclear (FUN) effects on other elements. It is found that a small Mg-26 excess exists in C1 and is correlated with the Al-27/Mg-24 ratio, indicating that Al-26 was present in C1 together with the more general nuclear anomalies. The results also reveal that isotopic homogeneity of Mg in Mg-rich phases in C1 is evident in both bulk samples and single microscopic crystals.

  6. Geological reasons for change in intensity of linear magnetic anomalies of the Kursk magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Zhavoronkin, I. A.; Kopayev, V. V.

    1985-01-01

    The geological reasons for fluctuations in the anomalous field intensity along the polar axes were examined. The Kursk magnetic anomaly is used as the basis for the study. A geological-geophysical section was constructed which used the results of the interpretation of gravimagnetic anomalies.

  7. On the equatorial anomaly of the ionospheric total electron content near the northern anomaly crest region

    Microsoft Academic Search

    Yinn-Nien Huang; Kang Cheng; Sen-Wen Chen

    1989-01-01

    The behavior of the equatorial anomaly in the ionospheric total electron content (TEC) around the northern anomaly crest region was studied, using the differential Doppler data from the U.S. Navy Navigation Satellite System and the Faraday rotation data from the Japanese geostationary satellite ETS 2 to construct the ionospheric TEC contour charts for each day from October 1, 1985 to

  8. Distribution of branchial anomalies in a paediatric Asian population

    PubMed Central

    Teo, Neville Wei Yang; Ibrahim, Shahrul Izham; Tan, Kun Kiaang Henry

    2015-01-01

    INTRODUCTION The objective of the present study was to review the distribution and incidence of branchial anomalies in an Asian paediatric population and highlight the challenges involved in the diagnosis of branchial anomalies. METHODS This was a retrospective chart review of all paediatric patients who underwent surgery for branchial anomalies in a tertiary paediatric hospital from August 2007 to November 2012. The clinical notes were correlated with preoperative radiological investigations, intraoperative findings and histology results. Branchial anomalies were classified based on the results of the review. RESULTS A total of 28 children underwent surgery for 30 branchial anomalies during the review period. Two children had bilateral branchial anomalies requiring excision. Of the 30 branchial anomalies, 7 (23.3%) were first branchial anomalies, 5 (16.7%) were second branchial anomalies, 3 (10.0%) were third branchial anomalies, and 4 (13.3%) were fourth branchial anomalies (one of the four patients with fourth branchial anomalies had bilateral branchial anomalies). In addition, seven children had 8 (26.7%) branchial anomalies that were thought to originate from the pyriform sinus; however, we were unable to determine if these anomalies were from the third or fourth branchial arches. There was inadequate information on the remaining 3 (10.0%) branchial anomalies for classification. CONCLUSION The incidence of second branchial anomalies appears to be lower in our Asian paediatric population, while that of third and fourth branchial anomalies was higher. Knowledge of embryology and the related anatomy of the branchial apparatus is crucial in the identification of the type of branchial anomaly. PMID:25917471

  9. Axial anomaly of QED in a strong magnetic field and noncommutative anomaly

    SciTech Connect

    Sadooghi, N. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Institute for Studies in Theoretical Physics and Mathematics (IPM), School of Physics, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Jafari Salim, A. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of)

    2006-10-15

    The Adler-Bell-Jackiw (ABJ) anomaly of a 3+1 dimensional QED is calculated in the presence of a strong magnetic field. It is shown that in the regime with the lowest Landau level (LLL) dominance a dimensional reduction from D=4 to D=2 dimensions occurs in the longitudinal sector of the low energy effective field theory. In the chiral limit, the resulting anomaly is therefore comparable with the axial anomaly of a two-dimensional massless Schwinger model. It is further shown that the U{sub A}(1) anomaly of QED in a strong magnetic field is closely related to the nonplanar axial anomaly of a conventional noncommutative U(1) gauge theory.

  10. Effects of Longwave Cloud Radiative Forcing Anomalies on the Atmospheric Response to Equatorial Pacific Sea Surface Temperature Anomalies

    NASA Technical Reports Server (NTRS)

    Chen, M.; Cess, Robert D.; Zhang, Ming-Hua

    1995-01-01

    The latest version of the National Center for Atmospheric Research community climate model (CCM2) has been used to investigate cloud radiative forcing (CRF) anomalies associated with equatorial Pacific sea surface temperature (SST) anomalies and the effects of the longwave CRF (LWCRF) anomalies on the atmospheric response to the SST anomalies. The SST anomalies cause large CRF anomalies, both longwave and shortwave, as well as latent heat anomalies at low latitudes on a global scale. The relative magnitude of the simulated longwave and shortwave CRF anomalies is consistent with the result of the Earth Radiation Budget Experiment (ERBE), implying that cloud height and cloud radiative properties such as emissivity and reflectivity are well simulated by the model. The LWCRF anomaly strongly enhances the precipitation anomaly in the whole tropical belt. The positive (negative) LWCRF anomaly warms (cools) the troposphere and destabilizes (stabilizes) the upper troposphere. The LWCRF anomaly enhances the Southern Oscillation and the related Walker circulation anomaly. The effects of the LWCRF anomaly are essential to the northern hemispheric extratropical circulation anomaly, the Pacific/North American pattern.

  11. Isotope separation by solar photoionization

    Microsoft Academic Search

    Mariella

    1982-01-01

    Isotope separation, particularly separation of isotopes of lithium, is achieved by exposing a beam of atoms to radiation that selectively excites atoms of a particular isotope without exciting atoms of other isotopes of that element. The excited atoms are ionized by solar radiation and the ions attracted to an ion collector plate maintained at a negative potential. The atoms not

  12. The Hubble Space Telescope attitude observer anomaly

    NASA Astrophysics Data System (ADS)

    Van Arsdall, Morgan M.; Ramsey, Patrick R.; Swain, Scott R.

    2006-06-01

    In mid-2004, the Hubble Space Telescope (HST) began experiencing occasional losses of lock during Fine Guidance Sensor (FGS) guide star acquisitions, threatening a potential loss of science. These failures were associated with an increasing disparity between the FGS-derived estimates of gyro bias calculated in orbit day and those calculated in orbit night. Early efforts to mitigate the operational effects of this Attitude Observer Anomaly (AOA) succeeded; however, the magnitude of the anomaly continued to increase at a linear rate and operational problems resumed in mid-2005. Continued analysis led to an additional on-orbit mitigation strategy that succeeded in reducing the AOA signature. Before the investigation could be completed, HST began operations under the life-extending Two Gyro Science mode. This eliminated both the operational effects of and the visibility into the AOA phenomenon. Possible causes of the anomaly at the vehicle system level included component hardware failures, flight software errors in control law processing, distortion of the telescope optical path, and deformation of vehicle structure. Although the mechanism of the AOA was not definitively identified, the Anomaly Review Board (ARB) chartered to investigate the anomaly concluded that the most likely root cause lies within one of HST's 6 rate-integrating gyroscopes. This paper provides a summary of the initial paths of investigation, the analysis and testing performed to attempt to isolate the source, and a review of the findings of the ARB. The possibility of future operational impacts and available methods of on-orbit mitigation are also addressed.

  13. Multidetector CT urography of renal fusion anomalies.

    PubMed

    Türkvatan, Aysel; Olçer, Tülay; Cumhur, Turhan

    2009-06-01

    Renal fusion anomalies, in which both kidneys are fused togeher in early embyronic life, are rarely encountered. Once a fused kidney is diagnosed or suspected, further laboratory and imaging evaluation should be performed to assess the status of the kidneys and to look for treatable causes of renal pathology. The early dignosis of potential complications that can accompany this anomaly must be made in order to prevent permanent renal damage. The advantage of multidetector computed tomographic (MDCT) urography is its ability to depict the normal urinary tract anatomy, including both the renal parenchyma, and collecting structures and ureters. MDCT urography is helpful to screen for the presence of stones, hydronephrosis or masses. Additionally, it provides information about the vascular supply of the fused kidneys. Therefore, MDCT urography enables a comprehensive evaluation of patients with renal fusion anomalies in a single examination. Especially three-dimensional reformatted images can provide good delineation of congenital fusion anomalies of the kidney. In this study we report our experience with MDCT urography for the anatomic demonstration of renal fusion anomalies. PMID:19517383

  14. Hyperbolic Orbits and the Planetary Flylby Anomaly

    NASA Technical Reports Server (NTRS)

    Wilson, T.L.; Blome, H.J.

    2009-01-01

    Space probes in the Solar System have experienced unexpected changes in velocity known as the flyby anomaly [1], as well as shifts in acceleration referred to as the Pioneer anomaly [2-4]. In the case of Earth flybys, ESA s Rosetta spacecraft experienced the flyby effect and NASA s Galileo and NEAR satellites did the same, although MESSENGER did not possibly due to a latitudinal property of gravity assists. Measurements indicate that both anomalies exist, and explanations have varied from the unconventional to suggestions that new physics in the form of dark matter might be the cause of both [5]. Although dark matter has been studied for over 30 years, there is as yet no strong experimental evidence supporting it [6]. The existence of dark matter will certainly have a significant impact upon ideas regarding the origin of the Solar System. Hence, the subject is very relevant to planetary science. We will point out here that one of the fundamental problems in science, including planetary physics, is consistency. Using the well-known virial theorem in astrophysics, it will be shown that present-day concepts of orbital mechanics and cosmology are not consistent for reasons having to do with the flyby anomaly. Therefore, the basic solution regarding the anomalies should begin with addressing the inconsistencies first before introducing new physics.

  15. A new automated method for measuring noble gases and their isotopic ratios in water samples

    NASA Astrophysics Data System (ADS)

    Stanley, Rachel H. R.; Baschek, Burkard; Lott, Dempsey E.; Jenkins, William J.

    2009-05-01

    A method is presented for precisely measuring all five noble gases and their isotopic ratios in water samples using multiple programmed multistage cryogenic traps in conjunction with quadrupole mass spectrometry and magnetic sector mass spectrometry. Multiple automated cryogenic traps, including a two-stage cryotrap used for removal of water vapor, an activated charcoal cryotrap used for helium separation, and a stainless steel cryotrap used for neon, argon, krypton, and xenon separation, allow reproducible gas purification and separation. The precision of this method for gas standards is ±0.10% for He, ±0.14% for Ne, ±0.10% for Ar, ±0.14% for Kr, and ±0.17% for Xe. The precision of the isotopic ratios of the noble gases in gas standards are ±1.9‰ for 20Ne/22Ne, ±2.0‰ for 84Kr/86Kr, ±2.5‰ for 84Kr/82Kr, ±0.9‰ for 132Xe/129Xe, and ±1.3‰ for 132Xe/136Xe. The precision of this method for water samples, determined by measurement of duplicate pairs, is ±1% for He, ±0.9% for Ne, ±0.3% for Ar, ±0.3% for Kr, and ±0.2% for Xe. An attached magnetic sector mass spectrometer measures 3He/4He with precisions of ±0.1% for air standards and ±0.14% for water samples.

  16. Platinum stable isotopes in ferromanganese crust and nodules

    NASA Astrophysics Data System (ADS)

    Corcoran, Loretta; Seward, Terry; Handler, Monica R.

    2015-04-01

    Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (< ±1) in the stable isotopic composition of marine platinum, raising the potential of adding platinum to the growing arsenal of paleoceanographic tracers. A method has been developed to measure the platinum isotopic composition using double spike MC-ICPMS analysis [2]and applied to a global suite of modern Fe-Mn crust and nodules. Combining synchrotron XAFS analyses of platinum adsorbed onto Fe-Mn oxide and oxyhydroxide surfaces to determine oxidation state and bonding environment, with platinum stable isotopic measurements allowing us to evaluate both platinum incorporation onto these sediments and the associated degree of platinum isotopic fractionation. Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

  17. Systematic study of sulfur isotopic composition in iron meteorites and the occurrence of excess S-33 and S-36

    NASA Technical Reports Server (NTRS)

    Gao, Xia; Thiemens, Mark H.

    1991-01-01

    The paper concentrates on isotopic measurements of sulfur in different sulfur-carrier phases: troilite inclusions, Fe-Ni alloy, and schreibersite (possibly including daubreelite). Variations in S-34 isotope ratio are observed in some troilite inclusions, and no evidence of nucleosynthetic sulfur isotopic anomalies are found in the troilite inclusions. Excesses of S-33 and S-36 are observed in both FeNi alloy and schreibersite of Grant, Santa Clara, Tlacotepec, and Gibeon, with schreibersite possessing the greater magnitude of presumably spallogenic S-33 and S-36. It is concluded that the magnitude of the observed fractionation is consistent with troilite dissociation and/or vaporization following a collisional impact.

  18. 'T hooft anomaly matching for QCD

    SciTech Connect

    Terning, John

    1998-03-03

    I present a set of theories which display non-trivial 'tHooft anomaly matching for QCD with F flavors. The matching theories arenon-Abelian gauge theories with "dual" quarks and baryons, rather thanthe purely confining theories of baryons that 't Hooft originallysearched for. The matching gauge groups are required to have an Fpm 6dimensional representation. Such a correspondence is reminiscent ofSeiberg's duality for supersymmetric (SUSY) QCD, and these theories arecandidates for non-SUSY duality. However anomaly matching by itself isnot sufficiently restrictive, and duality for QCD cannot be establishedat present. At the very least, the existence of multiple anomaly matchingsolutions should provide a note of caution regarding conjectured non-SUSYdualities.

  19. Are Flyby Anomalies an ASTG Phenomenon?

    E-print Network

    G. G. Nyambuya

    2010-05-07

    This reading expounds with expediency on the recently proposed Azimuthally Symmetric Theory of Gravitation (ASTG) set-up earlier. At its inspection, it was demonstrated that the ASTG is capable (among others solar anomalies) of explaining the precession of the perihelion of solar planets. In the present, we show that the ASTG is capable of explaining the puzzling observations of flyby anomalies, i.e. the anomalous asymptotic speed increases of the osculating hyperbolic speed excess. It is shown that these flyby anomalies occur naturally in the ASTG. We derive the empirical formula proposed by Anderson et al. in 2008, which up to now has no physical or foundational basis except that experience suggest it. If the ASTG model is correct, then for the first time the Anderson et al. formula is given a physical meaning.

  20. Elastic anomalies of anorthite: Molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Noritake, Fumiya; Kawamura, Katsuyuki; Matsukage, Kyoko N.

    2015-07-01

    We investigated the elastic anomalies of anorthite using molecular dynamics simulations in which the temperature and pressure induced P 1 bar / I 1 bar phase transitions were reproduced. The resulting changes in structure were investigated as functions of pressure and temperature. It was found that the temperature-induced elastic anomaly is caused by two different thermal expansion behaviors of atomic motion, that is, increased distance between nearest neighbor atoms and increased Si-O-Al angle. Furthermore, the pressure-induced elastic anomaly was found to be caused by a decrease in the Si-O-Al angle in six-membered rings, which is similar to the cases of vitreous silica or acidic silicate liquids.

  1. The mineralogy of global magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Haggerty, S. E. (principal investigator)

    1984-01-01

    Experimental and analytical data on magnetic mineralogy was provided as an aid to the interpretation of magnetic anomaly maps. An integrated program, ranging from the chemistry of materials from 100 or more km depth within the Earth, to an examination of the MAGSAT anomaly maps at about 400 km above the Earth's surface, was undertaken. Within this framework, a detailed picture of the pertinent mineralogical and magnetic relationships for the region of West Africa was provided. Efforts were directed toward: (1) examining the geochemistry, mineralogy, magnetic properties, and phases relations of magnetic oxides and metal alloys in rocks demonstrated to have originated in the lower crust of upper mantle, (2) examining the assumption that these rocks portray the nature of their source regions; and (3) examining the regional geology, tectonics, gravity field and the MAGSAT anomaly maps for West Africa.

  2. Trace anomalies in chiral theories revisited

    E-print Network

    Loriano Bonora; Stefano Giaccari; Bruno Lima de Souza

    2014-08-29

    Motivated by the search for possible CP violating terms in the trace of the energy-momentum tensor in theories coupled to gravity we revisit the problem of trace anomalies in chiral theories. We recalculate the latter and ascertain that in the trace of the energy-momentum tensor of theories with chiral fermions at one-loop the Pontryagin density appears with an imaginary coefficient. We argue that this may break unitarity, in which case the trace anomaly has to be used as a selective criterion for theories, analogous to the chiral anomalies in gauge theories. We analyze some remarkable consequences of this fact, that seem to have been overlooked in the literature.

  3. Detecting data anomalies methods in distributed systems

    NASA Astrophysics Data System (ADS)

    Mosiej, Lukasz

    2009-06-01

    Distributed systems became most popular systems in big companies. Nowadays many telecommunications companies want to hold large volumes of data about all customers. Obviously, those data cannot be stored in single database because of many technical difficulties, such as data access efficiency, security reasons, etc. On the other hand there is no need to hold all data in one place, because companies already have dedicated systems to perform specific tasks. In the distributed systems there is a redundancy of data and each system holds only interesting data in appropriate form. Data updated in one system should be also updated in the rest of systems, which hold that data. There are technical problems to update those data in all systems in transactional way. This article is about data anomalies in distributed systems. Avail data anomalies detection methods are shown. Furthermore, a new initial concept of new data anomalies detection methods is described on the last section.

  4. Anomaly Detection for Discrete Sequences: A Survey

    SciTech Connect

    Chandola, Varun [ORNL; Banerjee, Arindam [University of Minnesota; Kumar, Vipin [University of Minnesota

    2012-01-01

    This survey attempts to provide a comprehensive and structured overview of the existing research for the problem of detecting anomalies in discrete/symbolic sequences. The objective is to provide a global understanding of the sequence anomaly detection problem and how existing techniques relate to each other. The key contribution of this survey is the classification of the existing research into three distinct categories, based on the problem formulation that they are trying to solve. These problem formulations are: 1) identifying anomalous sequences with respect to a database of normal sequences; 2) identifying an anomalous subsequence within a long sequence; and 3) identifying a pattern in a sequence whose frequency of occurrence is anomalous. We show how each of these problem formulations is characteristically distinct from each other and discuss their relevance in various application domains. We review techniques from many disparate and disconnected application domains that address each of these formulations. Within each problem formulation, we group techniques into categories based on the nature of the underlying algorithm. For each category, we provide a basic anomaly detection technique, and show how the existing techniques are variants of the basic technique. This approach shows how different techniques within a category are related or different from each other. Our categorization reveals new variants and combinations that have not been investigated before for anomaly detection. We also provide a discussion of relative strengths and weaknesses of different techniques. We show how techniques developed for one problem formulation can be adapted to solve a different formulation, thereby providing several novel adaptations to solve the different problem formulations. We also highlight the applicability of the techniques that handle discrete sequences to other related areas such as online anomaly detection and time series anomaly detection.

  5. The relationship between clear sky water vapor and SST anomalies

    NASA Technical Reports Server (NTRS)

    Peterson, Thomas C.; Vonder Haar, Thomas H.

    1992-01-01

    The relationship between clear sky water vapor anomalies and the SST anomalies (SSTAs) was investigated with the purpose of providing data for evaluating the clear sky greenhouse effect predicted in many global warming scenarios, by statistically analyzing anomaly data sets of SST and the water vapor anomaly data (obtained by subtracting the mean value of the six years of data for a given month from the observed values). Results show that clear sky water vapor anomalies increase in association with increases in SSTAs. The clear sky water vapor anomalies high in the troposphere were also found to increase with increasing SSTA.

  6. Isotopically controlled semiconductors

    SciTech Connect

    Haller, E.E.

    2004-11-15

    A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

  7. Perchlorate isotope forensics

    USGS Publications Warehouse

    Böhlke, J.K.; Sturchio, N.C.; Gu, B.; Horita, J.; Brown, G.M.; Jackson, W.A.; Batista, J.; Hatzinger, P.B.

    2005-01-01

    Perchlorate has been detected recently in a variety of soils, waters, plants, and food products at levels that may be detrimental to human health. These discoveries have generated considerable interest in perchlorate source identification. In this study, comprehensive stable isotope analyses ( 37Cl/35Cl and 18O/17O/ 16O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. In addition, isotopic analyses of perchlorate extracted from groundwater and surface water demonstrate the feasibility of identifying perchlorate sources in contaminated environments on the basis of this technique. Both natural and synthetic sources of perchlorate have been identified in water samples from some perchlorate occurrences in the United States by the isotopic method. ?? 2005 American Chemical Society.

  8. Radioactive anomaly discrimination from spectral ratios

    DOEpatents

    Maniscalco, James; Sjoden, Glenn; Chapman, Mac Clements

    2013-08-20

    A method for discriminating a radioactive anomaly from naturally occurring radioactive materials includes detecting a first number of gamma photons having energies in a first range of energy values within a predetermined period of time and detecting a second number of gamma photons having energies in a second range of energy values within the predetermined period of time. The method further includes determining, in a controller, a ratio of the first number of gamma photons having energies in the first range and the second number of gamma photons having energies in the second range, and determining that a radioactive anomaly is present when the ratio exceeds a threshold value.

  9. Flyby anomaly and Lense-Thirring effect

    NASA Astrophysics Data System (ADS)

    Hackmann, Eva; Laemmerzahl, Claus

    The flyby anomaly is a shift in the Doppler data of Earth-flybys of various spacecraft. This shift can be interpreted as an anomalous velocity change in the range of a few mm/s which could not be explained so far. We analyse the general relativistic influence of the rotation of the Earth on a test particle on a hyperbolic orbit, the well known Lense-Thirring effect, using analytical methods. The results are applied to some spacecraft orbits where a flyby anomaly was detected.

  10. Congenital cytomegalovirus infection and finger anomaly

    PubMed Central

    I?ikay, Sedat; Yilmaz, Kutluhan

    2013-01-01

    Congenital cytomegalovirus (CMV) infection is the most common cause of intrauterine infection. It affects the central nervous system and causes microcephaly, hydrocephalus, mental retardation, hearing disorder, chorioretinitis and rarely finger anomalies. We present the case of a 4-month-old girl with an agenesis of the middle finger and syndactyly of the fourth and fifth fingers as a result of congenital CMV; this is the first such case in the literature. Here, congenital CMV infection is examined along with finger anomalies. PMID:23761501

  11. The GSI Time Anomaly: Facts and Fiction

    E-print Network

    Carlo Giunti

    2009-05-28

    The claims that the GSI time anomaly is due to the mixing of neutrinos in the final state of the observed electron-capture decays of hydrogen-like heavy ions are refuted with the help of an analogy with a double-slit experiment. It is a consequence of causality. It is shown that the GSI time anomaly may be caused by quantum beats due to the existence of two coherent energy levels of the decaying ion with an extremely small energy splitting (about $6\\times10^{-16} \\text{eV}$) and relative probabilities having a ratio of about 1/99.

  12. The GSI Time Anomaly:. Facts and Fiction

    NASA Astrophysics Data System (ADS)

    Giunti, Carlo

    2011-10-01

    The claims that the GSI time anomaly is due to the mixing of neutrinos in the final state of the observed electron-capture decays of hydrogen-like heavy ions are refuted with the help of an analogy with a double-slit experiment. It is a consequence of causality. It is shown that the GSI time anomaly may be caused by quantum beats due to the existence of two coherent energy levels of the decaying ion with an extremely small energy splitting (about 6 × 10-16eV) and relative probabilities having a ratio of about 1/99.

  13. Techniques for interpretation of geoid anomalies

    NASA Technical Reports Server (NTRS)

    Chapman, M. E.

    1979-01-01

    For purposes of geological interpretation, techniques are developed to compute directly the geoid anomaly over models of density within the earth. Ideal bodies such as line segments, vertical sheets, and rectangles are first used to calculate the geoid anomaly. Realistic bodies are modeled with formulas for two-dimensional polygons and three-dimensional polyhedra. By using Fourier transform methods the two-dimensional geoid is seen to be a filtered version of the gravity field, in which the long-wavelength components are magnified and the short-wavelength components diminished.

  14. The source of marine magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Harrison, Christopher G. A.

    1987-01-01

    The Vine-Matthews hypothesis (1963) is examined. This hypothesis suggests that oceanic rocks become polarized in the direction of the magnetic field at the time of their formation, thus recording the polarity history of the earth's magnetic field. This produces the lineated magnetic anomalies on either side of the midoceanic ridge crests. The strength of these magnetic anomalies is studied to determine the strength of magnetization. Indirect determinations of the magnetization intensity of the oceanic crust and direct observations of the oceanic crust are compared. It is found that the average magnetization of a 6-km thick oceanic crust is 1.18 A/m.

  15. Isotope Innovations (Invited)

    NASA Astrophysics Data System (ADS)

    Anbar, A. D.

    2013-12-01

    During a decade of discovery, the geochemical toolkit available for paleoredox reconstruction expanded dramatically. Notably, high-precision isotope analyses using multiple collector inductively coupled mass spectrometry (MC-ICP-MS) revealed that natural variations in isotope abundances due to isotope fractionation are ubiquitous across the Periodic Table. These variations quickly drew interest as paleoredox proxies because many of these isotope fractionations are driven by redox transformations. However, this potential has not been fully exploited because of the complexities of ancient systems and the need for extensive work in experiments and modern analog environments to calibrate these proxies. To generate the large datasets needed to move beyond "proof of potential" research, technological innovations are required. Two areas should be targeted for near-term progress, in both cases borrowing inspiration from the evolution of methods used to study light stable isotope systems. First, sample preparation is often an analytical bottleneck, especially for non-specialists, and the need for complex, specialized laboratory facilities when preparing samples manually limits the adoption of isotope techniques. This challenge can be addressed by developing and adapting automated ion exchange systems that allow inline or offline sample preparation. Systems that could be a basis for this effort are now becoming commercially available. Second, high precision isotope analysis using mass spectrometry presently requires expert technical support due to the complexities and costs of the instrumentation. Novel mass spectrometer designs are one approach to this challenge. Another is the use of high-resolution laser spectroscopy rather than mass spectrometry for isotope analysis. Concepts and preliminary efforts in these areas will be discussed.

  16. New Isotopes of Einsteinium

    Microsoft Academic Search

    Bernard G. Harvey; Alfred Chetham-Strode; Albert Ghiorso; Gregory R. Choppin; Stanley G. Thompson

    1956-01-01

    The new isotopes E249, E250, E251, and E252 were produced by bombardment of Bk249 with helium ions. A recoil method was used to separate the bombardment products from the target material, so that the target could be used repeatedly. Approximate excitation functions for the formation of the einsteinium isotopes were measured as well as their half-lives, alpha-particle energies, and electron-capture

  17. Osmium isotopes in ophiolites

    Microsoft Academic Search

    Jean-Marc Luck; Claude J. Allegre

    1991-01-01

    The present study reports Re and Os concentrations and Os isotropic composition for ultramafic samples from ophiolites. Present-day Os-187\\/Os-186 for the upper mantle is found to be constrained, for the time being, around 1.05-1.06. The mantle evolution curve for osmium isotopes through time, when associated with recent Os isotopic determinations from the literature for Archaean samples, shows a 'chondritic' Re-187\\/Os-196

  18. Resonantly-enhanced, four-photon ionization of krypton at laser intensities exceeding 10/sup 13/ W/cm/sup 2/

    SciTech Connect

    Perry, M.D.; Landen, O.L.; Campbell, E.M.

    1987-12-01

    The yield of singly- and multiply- charged ions of krypton and xenon is presented as a function of laser intensity and frequency. The measurements were performed using the second harmonic output of a well-characterized, tunable picosecond dye laser in the range 285 to 310 nm at laser intensities from 1 x 10/sup 12/ to 10/sup 14/ W/cm/sup 2/. Enhancement of the Kr/sup +/ yield by two orders of magnitude by three-photon resonant, four-photon ionization is observed in the vicinity of the 4d'(5/2)/sub 3/ and the 4d(3/2)/sub 1/ intermediate states. A model incorporating line shifts and widths scaling linearly with intensity is in good agreement with the experimental results.

  19. Getting to the Source of the High Isotopic Values of Ethiopian Precipitation

    NASA Astrophysics Data System (ADS)

    Levin, N. E.; Cerling, T. E.

    2007-12-01

    Oxygen and deuterium isotopic values of meteoric waters from Ethiopia are unusually high when compared to waters from other high-elevation settings in Africa and worldwide. These high values are well-documented; however, the climate processes responsible the isotopic anomaly in Ethiopian waters have not been thoroughly investigated. Current explanations for the isotopic composition of Ethiopian waters invoke very different moisture transport paths. One model suggests that Ethiopian rainfall originates in the Congo Basin where transpiration returns water to the atmosphere without isotopic differentiation. Another model suggests that Ethiopian rainfall originates in the Indian Ocean and travels westward where the first condensation of ocean moisture in Ethiopia yields precipitation with an isotopic composition close to that of ocean water. Here we present additional isotopic data from Ethiopian waters, use products from the Tropical Rainfall Monitoring Mission (TRMM) and National Centers for Environmental Prediction (NCEP) reanalysis project to evaluate wind directions during precipitation events in Ethiopia, and revisit the question of where the high isotopic values of Ethiopian precipitation originate. Isotopic analyses from more than 250 waters collected in the highlands and rift valleys of Ethiopia all yield values greater than -4 per mil and -22 per mil (VSMOW) for oxygen-18 and deuterium isotopes respectively, which are consistent with results from previous studies of Ethiopian waters. The TRMM and NCEP data show that the majority of low-level winds during precipitation events in Ethiopia are westerly and suggest that the moisture source for Ethiopian rainfall is transpired water from the Congo Basin. We propose that transport of transpired moisture from the Congo Basin is responsible for the high isotopic values of Ethiopian meteoric waters and present a general model for the isotopic and climate dynamics of rainfall in the region.

  20. Zirconium and Molybdenum in Individual Circumstellar Graphite Grains: New Isotopic Data on the Nucleosynthesis of Heavy Elements

    SciTech Connect

    Nicolussi, G.K. [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)] [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States); [Materials Science and Chemistry Divisions, Argonne National Laboratory, Argonne, IL 60439 (United States); Pellin, M.J. [Materials Science and Chemistry Divisions, Argonne National Laboratory, Argonne, IL 60439 (United States)] [Materials Science and Chemistry Divisions, Argonne National Laboratory, Argonne, IL 60439 (United States); Lewis, R.S.; Davis, A.M. [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)] [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States); Clayton, R.N. [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)] [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States); [Department of Chemistry, University of Chicago, Chicago, IL 60637 (United States); [Department of the Geophysical Sciences, University of Chicago, Chicago, IL 60637 (United States); Amari, S. [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)] [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States); [McDonnell Center for the Space Sciences, Washington University, St Louis, MO 63130 (United States)

    1998-09-01

    We have analyzed 32 individual graphite grains from the Murchison meteorite for their Mo and/or Zr isotopic compositions by resonant ionization mass spectrometry. Enormous isotopic anomalies were observed in some of these grains for both elements. The data for Zr revealed the largest isotopic anomalies, with {sup 96}Zr/{sup 94}Zr ratios ranging from 0.074 times to 10 times the solar value. The isotopic data on Mo show one population of graphite grains with close-to-terrestrial Mo composition in all isotopes and five grains with an {ital s}-process nucleosynthesis signature, i.e., correlated depletions in the {ital p}- and {ital r}-process isotopes. For eight grains we were able to measure both Mo and Zr isotopic compositions. Three of these eight graphite grains have {ital s}-process isotopic characteristics for both Zr and Mo, which suggests low-mass, thermally pulsed asymptotic giant branch stars as their origin. Four grains are puzzling, since they have nearly normal Mo compositions but significant anomalies in Zr, in particular, large depletions or enhancements in the {sup 96}Zr/{sup 94}Zr ratio. Two of these grains have extraordinary enrichments in {sup 96}Zr, with {sup 96}Zr/{sup 94}Zr ratios 10.4 {plus_minus} 1.3 and 2.5 {plus_minus} 0.3 times the solar system value. These enrichments are suggestive of the {ital r}-process, implying that these grains condensed from the ejecta of core-collapse supernovae, but these enrichments could also be made by the {ital s}-process if the neutron density were unusually high. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}