Science.gov

Sample records for neodymium isotopic anomalies

  1. 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.

  2. Neodymium isotopic variations in seawater

    NASA Technical Reports Server (NTRS)

    Piepgras, D. J.; Wasserburg, G. J.

    1980-01-01

    Direct measurement of the isotopic composition of Nd in the Atlantic agree with the Nd content in ferromanganese sediments and differ from the observed amounts in the Pacific samples. These data indicate the existence of distinctive differences in the isotopic composition of Nd in the waters of major oceans; the average values determined from seawater and ferromanganese sediments are considerably lower than in sources with oceanic mantle affinities showing that the REE in the oceans is dominated by continental sources. The Nd isotopic variations in seawater are applied to relate the residence time of Nd and mixing rates between the oceans.

  3. Boundary processes traced by neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Jeandel, C.; Lacan, F.

    2003-04-01

    Continental margins have been identified as preferential sites for removing of reactive elements from the ocean, on the base of U-series measurements (more specifically 231Pa/230Th). This process is called boundary scavenging (Bacon, 1988). Five years of neodymium isotopes data in water masses along the ocean margins (Indonesia, Papua New Guinea, Greenland-Scotland ridge and Labrador Sea) suggests that Nd is transferred from the sediments to the ocean but the reverse also occurs via the so-called boundary scavenging. These processes are only detectable by isotopic ratio measurements because they affect the isotopic signature of the water mass coming in contact with the margin, without changing its concentration. They can involve much higher fluxes than net input processes: for example, the modification of the AAIW signature along the Papua New Guinea slope involves exchange processes only (Lacan and Jeandel, 2001). Since we suspect that such processes not only affect the Nd oceanic chemistry but also the chemical fate of other reactive elements in the ocean, we suggest that the concept of boundary scavenging should be extended to "boundary exchange".

  4. Physicochemical isotope anomalies

    SciTech Connect

    Esat, T.M.

    1988-06-01

    Isotopic composition of refractory elements can be modified, by physical processes such as distillation and sputtering, in unexpected patterns. Distillation enriches the heavy isotopes in the residue and the light isotopes in the vapor. However, current models appear to be inadequate to describe the detailed mass dependence, in particular for large fractionations. Coarse- and fine-grained inclusions from the Allende meteorite exhibit correlated isotope effects in Mg both as mass-dependent fractionation and residual anomalies. This isotope pattern can be duplicated by high temperature distillation in the laboratory. A ubiquitous property of meteoritic inclusions for Mg as well as for most of the other elements, where measurements exist, is mass-dependent fractionation. In contrast, terrestrial materials such as microtektites, tektite buttons as well as lunar orange and green glass spheres have normal Mg isotopic composition. A subset of interplanetary dust particles labelled as chondritic aggregates exhibit excesses in {sup 26}Mg and deuterium anomalies. Sputtering is expected to be a dominant mechanism in the destruction of grains within interstellar dust clouds. An active proto-sun as well as the present solar-wind and solar-flare flux are of sufficient intensity to sputter significant amounts of material. Laboratory experiments in Mg show widespread isotope effects including residual {sup 26}Mg excesses and mass dependent fractionation. It is possible that the {sup 26}Mg excesses in interplanetary dust is related to sputtering by energetic solar-wind particles. The implication if the laboratory distillation and sputtering effects are discussed and contrasted with the anomalies in meteoritic inclusions the other extraterrestrial materials the authors have access to.

  5. Do foraminifera accurately record seawater neodymium isotope composition?

    NASA Astrophysics Data System (ADS)

    Scrivner, Adam; Skinner, Luke; Vance, Derek

    2010-05-01

    Palaeoclimate studies involving the reconstruction of past Atlantic meridional overturning circulation increasingly employ isotopes of neodymium (Nd), measured on a variety of sample media (Frank, 2002). In the open ocean, Nd isotopes are a conservative tracer of water mass mixing and are unaffected by biological and low-temperature fractionation processes (Piepgras and Wasserburg, 1987; Lacan and Jeandel, 2005). For decades, benthic foraminifera have been widely utilised in stable isotope and geochemical studies, but have only recently begun to be exploited as a widely distributed, high-resolution Nd isotope archive (Klevenz et al., 2008), potentially circumventing the difficulties associated with other methods used to recover past deep-water Nd isotopes (Klevenz et al., 2008; Rutberg et al., 2000; Tachikawa et al., 2004). Thus far, a single pilot study (Klevenz et al., 2008) has indicated that core-top sedimentary benthic foraminifera record a Nd isotope composition in agreement with the nearest available bottom seawater data, and has suggested that this archive is potentially useful on both millennial and million-year timescales. Here we present seawater and proximal core-top foraminifer Nd isotope data for samples recovered during the 2008 "RETRO" cruise of the Marion Dufresne. The foraminifer samples comprise a depth-transect spanning 3000m of the water column in the Angola Basin and permit a direct comparison between high-resolution water column and core-top foraminiferal Nd isotope data. We use these data to assess the reliability of both planktonic and benthic foraminifera as recorders of water column neodymium isotope composition. Frank, M., 2002. Radiogenic isotopes: Tracers of past ocean circulation and erosional input, Rev. Geophys., 40 (1), 1001, doi:10.1029/2000RG000094. Klevenz, V., Vance, D., Schmidt, D.N., and Mezger, K., 2008. Neodymium isotopes in benthic foraminifera: Core-top systematics and a down-core record from the Neogene south Atlantic

  6. 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

  7. Isotope enrichment by frequency-tripled temperature tuned neodymium laser photolysis of formaldehyde

    DOEpatents

    Marling, John B.

    1977-01-01

    Enrichment of carbon, hydrogen and/or oxygen isotopes by means of isotopically selective photo-predissociation of formaldehyde is achieved by irradiation provided by a frequency-tripled, temperature tuned neodymium laser.

  8. Titanium isotopic anomalies in meteorites

    NASA Astrophysics Data System (ADS)

    Neimeyer, S.; Lugmair, G. W.

    1984-07-01

    Studies of Ti isotopic compositions have shown that virtually every Ca-Al-rich Allende inclusion contains anomalous Ti. The present investigation is concerned with the results of a study of Ti isotopic compositions in meteorites. One objective of the study is to evaluate the possibility of a relation between oxygen and Ti anomalies, while another objective is to explore questions regarding the origin of the Ti anomalies. A summary of the major experimental findings of the study of Ti isotopic compositions is also presented. It is noted that an assessment of the implications of the Ti results favors a chemical memory type of model in which products from various nucleosynthetic sources survive in mineral grains. Isotopic heterogeneities are then preserved due to incomplete mixing and/or equilibriation with the bulk of solar system matter. Strong arguments are found to exist against a pure late supernova injection model.

  9. Titanium isotopic anomalies in meteorites

    NASA Technical Reports Server (NTRS)

    Niemeyer, S.; Lugmair, G. W.

    1984-01-01

    Studies of Ti isotopic compositions have shown that virtually every Ca-Al-rich Allende inclusion contains anomalous Ti. The present investigation is concerned with the results of a study of Ti isotopic compositions in meteorites. One objective of the study is to evaluate the possibility of a relation between oxygen and Ti anomalies, while another objective is to explore questions regarding the origin of the Ti anomalies. A summary of the major experimental findings of the study of Ti isotopic compositions is also presented. It is noted that an assessment of the implications of the Ti results favors a chemical memory type of model in which products from various nucleosynthetic sources survive in mineral grains. Isotopic heterogeneities are then preserved due to incomplete mixing and/or equilibriation with the bulk of solar system matter. Strong arguments are found to exist against a pure late supernova injection model.

  10. Neodymium isotope evidence for a chondritic composition of the Moon.

    PubMed

    Rankenburg, K; Brandon, A D; Neal, C R

    2006-06-01

    Samarium-neodymium isotope data for six lunar basalts show that the bulk Moon has a 142Nd/144Nd ratio that is indistinguishable from that of chondritic meteorites but is 20 parts per million less than most samples from Earth. The Sm/Nd formation interval of the lunar mantle from these data is 215(-21)(+23) million years after the onset of solar system condensation. Because both Earth and the Moon likely formed in the same region of the solar nebula, Earth should also have a chondritic bulk composition. In order to mass balance the Nd budget, these constraints require that a complementary reservoir with a lower 142Nd/144Nd value resides in Earth's mantle. PMID:16741118

  11. Origin of the Sudbury Complex by meteoritic impact: Neodymium isotopic evidence

    USGS Publications Warehouse

    Faggart, B.E., Jr.; Basu, A.R.; Tatsumoto, M.

    1985-01-01

    Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 ?? 21 ?? 106 years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.

  12. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

  13. Chromium isotopic anomalies in the Murchison meteorite

    NASA Astrophysics Data System (ADS)

    Esat, T. M.; Ireland, T. R.

    1989-02-01

    The abundances of chromium isotopes, in refractory inclusions from the Allende meteorite, show wide-spread anomalies. The chromium isotope anomalies are similar in pattern to the anomalies discovered in Ca and Ti. The largest effects occur at the neutron-rich isotopes Ca-48, Ti-50 and Cr-54. Individual Cr-rich pink spinels, from the Murchison meteorite, exhibit large and variable excesses in Cr-53 and Cr-54 including the largest Cr-53 anomaly so far reported. Magnesium isotopes, in Murchison Cr-poor blue spinels, also show variable anomalies in Mg-26 including mass-dependent fractionation favoring the lighter isotopes. The Cr-53, Cr-54 and Mg-26 anomalies in Murchison spinels are indicative of a heterogeneous distribution of magnesium and chromium isotopes in the early solar nebula and require a contribution from several nucleosynthetic components in addition to physicochemical processing.

  14. Hafnium and Neodymium Isotopes in Atlantic Ocean Waters

    NASA Astrophysics Data System (ADS)

    Rickli, J.; Frank, M.; Halliday, A.

    2007-12-01

    Neodymium isotopic compositions (ICs) have been established as a tracer of water masses in the present and past oceans since the late 1970s. Hafnium isotopes share the capability of tracing water masses and in combination with Nd isotopes provide information on continental weathering regimes. Whereas Nd released during weathering reflects the bulk Nd IC of the weathered lithology, the released Hf is more radiogenic than the weathered lithology. This effect is due to highly variable Lu/Hf--ratios in rock--forming minerals ("zircon effect") and as a consequence physical weathering apparently leads to more congruent weathering of Hf than chemical weathering does. Our understanding of the Hf IC of seawater to date has been derived (with the exception of some as yet unpublished data from the Arctic and Pacific oceans (Zimmermann et al., in prep.)) from ferromanganese crusts and nodules, since Hf concentrations in seawater are low and have until recently hampered direct measurements of Hf IC of seawater. We present IC for the dissolved Hf and Nd in Atlantic seawater. Samples were taken mainly on a transect from the Bay of Biscay to Cape Town (RV Polarstern cruise ANT XXIII/1 in 2005). A few additional samples are from the Labrador Sea and the Drake Passage. Hafnium and Nd were pre--concentrated by iron co--precipitation from 60 to 140 liters of filtered (0.45 μm) seawater. Separation of Hf and Nd followed previously established ion chromatographic procedures. Hafnium and Nd ICs were measured by MC--ICPMS (Nu Plasma) with a 2σ external reproducibility of 0.65 and 0.3 ǎrepsilon--units, respectively. Sample sizes varied but were in most cases larger than 3ng of Hf. Surface seawater as well as deep water samples extending to ~5,000 m, plot on the "seawater array" defined previously from measurements of ferromanganese crusts and nodules. Surface seawater ICs are quite uniform for Hf ranging from ǎrepsilonHf = 0 to +2 at most sampling sites on the Atlantic transect. In the

  15. Rare earth elements and neodymium isotopes in world river sediments revisited

    NASA Astrophysics Data System (ADS)

    Bayon, G.; Toucanne, S.; Skonieczny, C.; André, L.; Bermell, S.; Cheron, S.; Dennielou, B.; Etoubleau, J.; Freslon, N.; Gauchery, T.; Germain, Y.; Jorry, S. J.; Ménot, G.; Monin, L.; Ponzevera, E.; Rouget, M.-L.; Tachikawa, K.; Barrat, J. A.

    2015-12-01

    Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world's major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results confirmed earlier assumptions that river sediments do not generally exhibit any significant grain-size dependent Nd isotopic variability. Most sediments from rivers draining old cratonic areas, sedimentary systems and volcanic provinces displayed similar Nd isotopic signatures in both clay and silt fractions, with ΔεNd(clay-silt) < |1|. A subtle decoupling of Nd isotopes between clays and silts was identified however in a few major river systems (e.g. Nile, Mississippi, Fraser), with clays being systematically shifted towards more radiogenic values. This observation suggests that preferential weathering of volcanic and/or sedimentary rocks relative to more resistant lithologies may occur in river basins, possibly leading locally to Nd isotopic decoupling between different size fractions. Except for volcanogenic sediments, silt fractions generally displayed homogeneous REE concentrations, exhibiting relatively flat shale-normalized patterns. However, clay fractions were almost systematically characterized by a progressive enrichment from the heavy to the light REE and a positive europium (Eu) anomaly. In agreement with results from previous soil investigations, the observed REE fractionation between clays and silts

  16. Robustness of fossil fish teeth for seawater neodymium isotope reconstructions under variable redox conditions in an ancient shallow marine setting

    NASA Astrophysics Data System (ADS)

    Huck, Claire E.; van de Flierdt, Tina; Jiménez-Espejo, Francisco J.; Bohaty, Steven M.; Röhl, Ursula; Hammond, Samantha J.

    2016-03-01

    Fossil fish teeth from pelagic open ocean settings are considered a robust archive for preserving the neodymium (Nd) isotopic composition of ancient seawater. However, using fossil fish teeth as an archive to reconstruct seawater Nd isotopic compositions in different sedimentary redox environments and in terrigenous-dominated, shallow marine settings is less proven. To address these uncertainties, fish tooth and sediment samples from a middle Eocene section deposited proximal to the East Antarctic margin at Integrated Ocean Drilling Program Site U1356 were analyzed for major and trace element geochemistry, and Nd isotopes. Major and trace element analyses of the sediments reveal changing redox conditions throughout deposition in a shallow marine environment. However, variations in the Nd isotopic composition and rare earth element (REE) patterns of the associated fish teeth do not correspond to redox changes in the sediments. REE patterns in fish teeth at Site U1356 carry a typical mid-REE-enriched signature. However, a consistently positive Ce anomaly marks a deviation from a pure authigenic origin of REEs to the fish tooth. Neodymium isotopic compositions of cleaned and uncleaned fish teeth fall between modern seawater and local sediments and hence could be authigenic in nature, but could also be influenced by sedimentary fluxes. We conclude that the fossil fish tooth Nd isotope proxy is not sensitive to moderate changes in pore water oxygenation. However, combined studies on sediments, pore waters, fish teeth, and seawater are needed to fully understand processes driving the reconstructed signature from shallow marine sections in proximity to continental sources.

  17. Zinc Isotope Anomalies in bulk Chondrites

    NASA Astrophysics Data System (ADS)

    Savage, P. S.; Boyet, M.; Moynier, F.

    2014-09-01

    This study is the first to demonstrate that Zn isotope anomalies are present in bulk primitive meteorites, consistent with the injection of material derived from a neutron-rich supernova source into the solar nebula.

  18. 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.

  19. Isotopic anomalies - Chemical memory of Galactic evolution

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.

    1988-01-01

    New mechanisms for the chemical memory of isotopic anomalies are proposed which are based on the temporal change during the chemical evolution of the Galaxy of the isotopic composition of the mean ejecta from stars. Because of the differing temporal evolution of primary and secondary products of nucleosynthesis, the isotopic composition of the bulk interstellar medium changes approximately linearly with time, and thus any dust component having an age different from that of average dust will be isotopically anomalous. Special attention is given to C, O, Mg, Si, and isotopically heavy average-stellar condensates of SiC.

  20. Cerium and Neodymium Isotope Fractionation in Geochemical Samples

    NASA Astrophysics Data System (ADS)

    Ohno, T.; Ishibashi, T.

    2014-12-01

    The study of naturally occurring isotopic variations of rare earth elements (REE) has a potentially significant influence in geochemical research fields with other traditional studies of REE. One of the key features of REE are their chemical similarities and gradual changes of ionic radius, which may make the isotopic variation of REE a potential tool to understand the mechanisms of isotopic fractionation in nature. Among the REE, geochemical and physicochemical features of Ce could be anomalous, because Ce could be present as the tetravalent (+IV) state as well as the common trivalent (+III) state of other REE. Since the oxidation state of Ce can change by reflecting the redox conditions of the environment, the measured differences in the degree of isotopic fractionation between Ce and other REE can provide unique information about the redox conditions. In this study, we developed a new analytical method to determine the mass-dependent isotopic fractionations of Ce and Nd in geochemical samples. The reproducibility of the isotopic ratio measurements on 142Ce/140Ce, 146Nd/144Nd and 148Nd/144Nd were 0.08‰ (2SD, n=25), 0.06‰ (2SD, n=39) and 0.12‰ (2SD, n=39), respectively. The present technique was applied to determine the variations of the Ce and Nd isotopic ratios for five geochemical reference materials (igneous rocks, JB-1a and JA-2; sedimentary rocks, JMn-1, JCh-1 and JDo-1). The resulting ratios for two igneous rocks (JB-1a and JA-2) and two sedimentary rocks (JMn-1 and JCh-1) did not vary significantly among the samples, whereas the Ce and Nd isotope ratios for the carbonate samples (JDo-1) were significantly higher than those for igneous and sedimentary rock samples. The 1:1 simple correlation between δ142Ce and δ146Nd indicates that there were no significant difference in the degree of isotopic fractionation between the Ce and Nd. This suggests that the isotopic fractionation for Ce found in the JDo-1 could be induced by physicochemical processes

  1. Mechanisms of magma generation beneath hawaii and mid-ocean ridges: uranium/thorium and samarium/neodymium isotopic evidence.

    PubMed

    Sims, K W; Depaolo, D J; Murrell, M T; Baldridge, W S; Goldstein, S J; Clague, D A

    1995-01-27

    Measurements of uranium/thorium and samarium/neodymium isotopes and concentrations in a suite of Hawaiian basalts show that uranium/thorium fractionation varies systematically with samarium/neodymium fractionation and major-element composition; these correlations can be understood in terms of simple batch melting models with a garnet-bearing peridotite magma source and melt fractions of 0.25 to 6.5 percent. Midocean ridge basalts shows a systematic but much different relation between uranium/thorium fractionation and samarium/neodymium fractionation, which, although broadly consistent with melting of a garnet-bearing peridotite source, requires a more complex melting model. PMID:17788786

  2. Neodymium and lead isotope evidence for enriched early Archean crust in North America

    NASA Technical Reports Server (NTRS)

    Bowring, Samuel A.; Housh, Todd B.; Isachsen, Clark E.; Podosek, Frank A.; King, Janet E.

    1989-01-01

    Neodymium and lead isotope measurements and uranium-lead zircon geochronology from Archaean gneisses of the Slave Province in the Northwest Territories of Canada are reported. The gneisses contain zircons with cores older than 3.842 Gyr and an epsilon(Nd) (3.7 Gyr) of - 4.8. This is the oldest reported chondritic model age for a terrestrial sample and provides evidence for strongly enriched pre-3.8-Gyr crust, a reservoir complementary to the depleted mantle already in existence by 3.8 Gyr before the present.

  3. Neodymium isotopic studies of Precambrian banded iron formations

    SciTech Connect

    Pimentel-Klose, M.R.

    1986-01-01

    The isotopic composition of Nd is reported for 11 different Precambrian BIFs and suggests a trend of increasingly positive epsilon/sub Nd/(T) values with age. This trend is interpreted to reflect isotopic variations in precambrian sea water. The Urucum and the Gunflint BIFs, both younger than 1.8 AE, yield negative epsilon/sub Nd/(T) values, between -4.6 and -1.1. The remaining BIFs, with ages between 1.85 and 3.4 AE, have predominantly positive values, between -0.7 and +4.0. The low UXSm/ UUNd ratio in BIFs is inconsistent with their REE being derived from rivers draining large proportions of greenstones. The positive, mantle-like values of BIFs older than 1.8 AE contrasts strongly with the negative, continental-like values of Phanerozoic sea water. Therefore, the REE budget of the oceans during most of the Precambrian was probably dominated by the hydrothermal circulation of sea water through MORBs and not by river waters, as today. A one order of magnitude higher hydrothermal contribution of Nd is suggested by the data for the Early Precambrian. This is most likely due to a higher hydrothermal water to river water flux ratio and/or a higher Nd concentration in hotter hydrothermal waters (>375 C) during this period. The large hydrothermal contribution of REE during the Early Precambrian can be explained best if the temperature of sea water fluxing through MORBs was higher than today. Experiments investigating the interaction between sea water and basalt have shown that the concentration of iron might have been about 20 times larger if the temperature of interaction was about 425 C. Such hot hydrothermal solutions could have been the most important source of iron in Precambrian BIFs.

  4. Carbon and Neodymium Isotopic Fingerprints of Atlantic Deep Ocean Circulation During the Warm Pliocene

    NASA Astrophysics Data System (ADS)

    Riesselman, C. R.; Scher, H.; Robinson, M. M.; Dowsett, H. J.; Bell, D. B.

    2012-12-01

    Earth's future climate may resemble the mid-Piacenzian Age of the Pliocene, a time when global temperatures were sustained within the range predicted for the coming century. Surface and deep water temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm surface temperature anomaly in the mid-Piacenzian (3.264 - 3.025 Ma), accompanied by increased evaporation. The anomaly is detected in deep waters at 46°S, suggesting enhanced meridional overturning circulation and more southerly penetration of North Atlantic Deep Water (NADW) during the PRISM interval. However deep water temperature proxies are not diagnostic of water mass and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy investigation of Atlantic deep ocean circulation during the warm mid-Piacenzian, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic composition of fossil fish teeth (ɛNd) as a proxy for water mass source and mixing. This reconstruction utilizes both new and previously published data from DSDP and ODP cores along equatorial (Ceara Rise), southern mid-latitude (Walvis Ridge), and south Atlantic (Meteor Rise/Agulhas Ridge) depth transects. Additional end-member sites in the regions of modern north Atlantic and Southern Ocean deep water formation provide a Pliocene baseline for comparison. δ13C throughout the Atlantic basin is remarkably homogenous during the PRISM interval. δ13C values of Cibicidoides spp. and C. wuellerstorfi largely range between 0‰ and 1‰ at North Atlantic, shallow equatorial, southern mid-latitude, and south Atlantic sites with water depths from 2000-4700 m; both depth and latitudinal gradients are generally small (~0.3‰). However, equatorial

  5. Neodymium and carbon isotopic fingerprints of warm Pliocene circulation throughout the deep Atlantic

    NASA Astrophysics Data System (ADS)

    Riesselman, C. R.; Scher, H. D.; Dowsett, H. J.; Robinson, M. M.

    2013-12-01

    The mid-Piacenzian age of the Pliocene is the most recent interval in Earth's history to sustain global warmth within the range predicted for the 21st century. To understand this interval, the USGS PRISM Project has developed a reconstruction of global conditions at 3.264-3.025 Ma, which includes a significant North Atlantic warm SST anomaly coupled with increased evaporation. Warm anomalies are also detected in the deep ocean as far as 46°S, suggesting that enhanced meridional overturning circulation may have been responsible for more southerly penetration of North Atlantic Deep Water (NADW). However, deep temperature proxies are not diagnostic of water mass, and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy synthesis of Atlantic deep ocean circulation during the PRISM interval, using the neodymium isotopic composition (ɛNd) of fossil fish teeth as a proxy for water mass source and the δ13C of benthic foraminifera as a proxy for water mass age. This reconstruction utilizes both new and previously published data from 11 DSDP and ODP sites in the North Atlantic (Site 610) and along depth transects from equatorial Ceara Rise, southern mid-latitude Walvis Ridge, and south Atlantic Meteor Rise/Agulhas Ridge. Published data from ferromanganese crusts constrain Pliocene Antarctic deep waters at ~ ɛNd = -8, distinct from the less radiogenic ɛNd = -11.5 that characterizes Pliocene northern component water (NCW). These values fingerprint northern and southern sources throughout the Atlantic basin. Pliocene fish teeth from Site 610 (2400 m water depth) and from four Ceara Rise sites (3000-4300 m) preserve distinctly North Atlantic ɛNd. When averaged across the PRISM interval, mean values for these five sites range from ɛNd = -10.97 to -10.25, and the Pliocene depth transect closely mirrors the structure of the modern column, indicating

  6. Constraints on ocean circulation at the Paleocene-Eocene Thermal Maximum from neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Abbott, April N.; Haley, Brian A.; Tripati, Aradhna K.; Frank, Martin

    2016-04-01

    Global warming during the Paleocene-Eocene Thermal Maximum (PETM) ˜ 55 million years ago (Ma) coincided with a massive release of carbon to the ocean-atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role of changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites to reconstruct past deep-ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth Nd isotopes and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for initiation and recovery of the ocean-atmosphere system associated with the PETM.

  7. 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.

  8. From the subtropics to the central equatorial Pacific Ocean: Neodymium isotopic composition and rare earth element concentration variations

    NASA Astrophysics Data System (ADS)

    Grenier, MéLanie; Jeandel, Catherine; Lacan, FrançOis; Vance, Derek; Venchiarutti, CéLia; Cros, Alexandre; Cravatte, Sophie

    2013-02-01

    Neodymium isotopic compositions (ɛNd) and rare earth element (REE) concentrations were measured for filtered surface to deep waters (112 samples) in the Southern Tropical Pacific. The relatively detailed picture of these tracer distributions allowed us to refine the areas where oceanic ɛNd variations occur. ɛNd values increase for most of the water masses flowing from Samoa to the Solomon Sea and in the Papua New Guinea (PNG) area, as already observed. Furthermore, water masses arriving from the eastern equatorial Pacific (200-550 m depth) also revealed radiogenic values, possibly acquired in the vicinity of the South American coasts and Galapagos Islands. These ɛNd variations affect the whole water column. The most likely process causing such variations is "boundary exchange" between the numerous radiogenic slopes/margins located in this area and seawater flowing past. Dissolution of atmospheric deposition and/or diffuse streaming of volcanic ash are also suggested to explain the radiogenic ɛNd observed at the surface in the PNG area. Interestingly, a positive europium (Eu) anomaly characterizes the normalized REE patterns of most of the studied water masses. This anomaly is consistent with the REE patterns of sediment and rock samples that are potential sources for the local waters. Such consistency reinforces the hypothesis that lithogenic sources play a major role in the oceanic REE budget, thanks to "boundary exchange." The data set presented here is a good basis for further sampling that will be realized in the framework of the ongoing GEOTRACES program (www.geotraces.org).

  9. Rhenium-osmium and samarium-neodymium isotopic systematics of the stillwater complex

    USGS Publications Warehouse

    Lambert, D.D.; Morgan, J.W.; Walker, R.J.; Shirey, S.B.; Carlson, R.W.; Zientek, M.L.; Koski, M.S.

    1989-01-01

    Isotopic data for the Stillwater Complex, Montana , which formed about 2700 Ma (million years ago), were obtained to evaluate the role of magma mixing in the formation of strategic platinum-group element (PGE) ore deposits. Neodymium and osmium isotopic data indicate that the intrusion formed from at least two geochemically distinct magmas. Ultramafic affinity (U-type) magmas had initial ??Nd of -0.8 to -3.2 and a chondritic initial 187Os/186Os ratio of ???0.88, whereas anorthositic affinity (A-type) magmas had ??Nd of -0.7 to +1.7 and an initial 187Os/186Os ratio of ???1.13. These data suggest that U-type magmas were derived from a lithospheric mantle source containing recycled crustal materials whereas A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The Nd and Os isotopic data also suggest that Os, and probably the other PGEs in ore horizons such as the J-M Reef, was derived from A-type magmas. The Nd and Os isotopic heterogeneity observed in rocks below the J-M Reef also suggests that A-type magmas were injected into the Stillwater U-type magma chamber at several stages during the development of the Ultramafic series.

  10. Constraints on ocean circulation at the Paleocene-Eocene Thermal Maximum from neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Abbott, A. N.; Haley, B. A.; Tripati, A. K.; Frank, M.

    2015-06-01

    Global warming during the Paleocene Eocene Thermal Maximum (PETM) ~55 million years ago (Ma) coincided with a massive release of carbon to the ocean-atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role for changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites and comparing data with published data from fossil fish debris to reconstruct past deep ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for global recovery of the ocean-atmosphere system after the PETM.

  11. How Well Do Neodymium Isotopes Trace AMOC Mixing? A Test in the Southwest Atlantic

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Goldstein, S. L.; Pena, L.; Hartman, A. E.; Rijkenberg, M. J. A.; De Baar, H. J. W.

    2014-12-01

    Neodymium (Nd) isotope ratios are used to trace past AMOC circulation, based on observations that seawater Nd isotope ratios effectively "fingerprint" water masses, and that over long water mass transport distances in deep seawater they reflect values expected from water mass mixing. Over the past several years, studies have increasingly focused on the potential of external addition of Nd along water mass transport paths (for example through "boundary exchange" with particulates or addition from groundwaters), thus challenging the idea that Nd isotopes behave "quasi-conservatively" in the oceans. The SW Atlantic, with the major water masses involved in the AMOC (southward flowing NADW, northward flowing AAIW and AABW), is arguably the best place on Earth to evaluate how well Nd isotopes trace water mass mixing, in order to clarify its value for following the AMOC through time. We will report Nd isotope ratios of seawater collected on the SW Atlantic meridional transect of the NIOZ West Atlantic GEOTRACES Cruise Leg 3 (RRS James Cook 057), which sampled seawater profiles and the sediment surface at 18 stations between 0-50°S. Most stations are sampled in the open ocean, providing a test of whether Nd isotopes show quasi-conservative mixing systematics away from continental margins. The cruise section also provides several opportunities to test the potential effects of external Nd input. For example, it transects the continental shelf in the far south, the Rio Grande Rise, volcanic seamounts, and the major geological age boundaries of South America. It also crosses the major Southern Hemisphere wind zones, allowing us to test the impacts of aeolian input, and inputs from major rivers (Parana-Paraguay, Sao Francisco, Amazon). All of these features have the potential to modify the seawater Nd isotope ratios, allowing us to determine if they add significant external Nd.

  12. Variations in the neodymium and strontium isotopic composition and REE content of molluscan shells from the Cretaceous Western Interior seaway

    SciTech Connect

    Whittaker, S.G.; Kyser, T.K. )

    1993-08-01

    Rare earth element concentrations, [epsilon][sub ND](T) values, and strontium isotopic compositions of mollusc shells were used to trace variations in the neodymium and strontium isotopic composition of the epicontinental Late Cretaceous Western Interior seaway of North America. Rare earth element patterns are different in aragonite and calcite produced by the molluscs endemic to the seaway, indicating that either mineralogical control or possibly scavenging by organic films associated with the different phases of biogenic carbonate resulted in differential partitioning of the REEs from seawater during shell formation. The biogenic carbonate also may contain REEs associated with Fe-flocs trapped in the shells during growth, but these flocs cannot result in different REE patterns of aragonite and calcite produced by the molluscs. The neodymium isotopic composition of the Western Interior seaway is inferred to have varied 13 [epsilon]-units over 20 My as a result of incursions of seawater from the Arctic Ocean and Gulf of Mexico, river influx from tectonically active terranes, benthic diagenetic fluxes, and volcanic ash falls. Ash from a variety of volcanic centers in western North America was significant in producing rapid and marked changes in [sup 143]Nd/[sup 144]Nd ratios of the seaway, and abrupt regional variations in neodymium isotopic composition of the seaway make the construction of an accurate neodymium isotope evolution curve difficult for this basin. Strontium isotopic compositions of the mollusc shells indicate the [sup 87]Sr/[sup 86]Sr ratio of the Western Interior seaway was generally similar to contemporaneous oceans, although, periodically, the basin had strontium isotopic compositions distinct from contemporaneous seawater. 58 refs., 7 figs., 3 tabs.

  13. Neodymium isotopes in Archean seawater and implications for the marine Nd cycle in Earth's early oceans

    NASA Astrophysics Data System (ADS)

    Alexander, Brian W.; Bau, Michael; Andersson, Per

    2009-06-01

    Published neodymium (Nd) isotopic data for Archean iron-formations (IF) suggest that, overall, seawater throughout the Archean typically displayed 143Nd/ 144Nd close to bulk Earth values, with ЄNd( t) between - 1.5 and + 2.5. Neodymium isotopic ratios in seawater during deposition of the ~ 3.8 Isua (Greenland) IF likely displayed positive ЄNd(3.8 Ga) of + 2.5, as suggested by IF-G, an Isua reference IF that is considered the best archive for Early Archean seawater. Seawater 143Nd/ 144Nd ratios dominated by radiogenic Nd (positive ЄNd( t)) seem to have persisted for much of the Archean, as IF from the Pietersburg greenstone belt, South Africa, suggest seawater ЄNd(2.95 Ga) ≥ + 1. However, similarly aged (~ 2.9 Ga) IFs from South Africa indicate that significant variations in seawater 143Nd/ 144Nd occurred, and clearly show influences from isotopically distinct crustal sources. These variations are apparently related to depositional environment, with cratonic margin, shallow-water IFs possessing a continental ЄNd( t) of - 3, while IFs associated with sub-aqueous mafic volcanics display more radiogenic, positive ЄNd( t) values. Such variation in seawater 143Nd/ 144Nd is not possible in an isotopically well-mixed ocean, and similar to today, it appears that marine Nd cycling in the Archean produced water masses with distinct Nd isotopic ratios. Since the presence of banded iron-formations requires a reducing Archean ocean capable of transporting Fe, metal-oxide precipitation and scavenging processes near deep sea hydrothermal vent systems would not have scavenged mantle Nd, i.e., Nd sourced from alteration of oceanic crust. We propose that bulk anoxic seawater prior to 2.7 Ga possessed relatively constant positive ЄNd( t) of + 1 to + 2, whereas local shallow-water masses associated with exposed evolved crust could possess distinctly different, lower ЄNd( t).

  14. Hafnium and neodymium isotope composition of seawater and filtered particles from the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Stichel, T.; Frank, M.; Haley, B. A.; Rickli, J.; Venchiarutti, C.

    2009-12-01

    Radiogenic hafnium (Hf) and neodymium (Nd) isotopes have been used as tracers for past continental weathering regimes and ocean circulation. To date, however, there are only very few data available on dissolved Hf isotope compositions in present-day seawater and there is a complete lack of particulate data. During expedition ANTXXIV/3 (February to April 2008) we collected particulate samples (> 0.8 µm), which were obtained by filtrations of 270-700 liters of water. The samples were separated from the filters, completely dissolved, and purified for Nd and Hf isotope determination by TIMS and MC-ICPMS, respectively. In addition, we collected filtered (0.45 µm) seawater samples (20-120 liters) to determine the dissolved isotopic composition of Hf and Nd. The Hf isotope composition of the particulate fraction in the Drake Passage ranged from 0 to -28 ɛHf and is thus similar to that observed in core top sediments from the entire Southern Ocean in a previous study. The most unradiogenic and isotopically homogenous Hf isotope compositions in our study were found near the Antarctic Peninsula. Most of the stations north of the Southern Antarctic Circumpolar Front (SACC) show a large variation in ɛHf between 0 and -23 within the water column of one station and between the stations. The locations at which these Hf isotope compositions were measured are mostly far away from the potential source areas. Nd, in contrast, was nearly absent throughout the entire sample set and the only measurable ɛNd data ranged from 0 to -7, which is in good agreement with the sediment data in that area. The dissolved seawater isotopic compositions of both Hf and Nd show only minor variance (ɛHf = 4.2 to 4.7 and ɛNd = -8.8 to -7.6, respectively). These patterns in Hf isotopes and the nearly complete absence of Nd indicates that the particulate fraction does not contain a lot of terrigeneous material but is almost entirely dominated by biogenic opal. The homogenous and relatively radiogenic

  15. Osmium and neodymium isotopic constraints on the temporal and spatial evolution of Siberian flood basalt sources

    USGS Publications Warehouse

    Horan, M.F.; Walker, R.J.; Fedorenko, V.A.; Czamanske, G.K.

    1995-01-01

    Picrites from the Gudchikhinsky suite, the oldest rocks examined, have ??Os of +5.3 to +6.1 and ??Nd of +3.7 to +4.0. The osmium and neodymium isotopic compositions of these rocks are similar to some modern ocean-island basalts (OIB), consistent with their derivation from an mantle plume. Picrites from the stratigraphically higher Tuklonsky suite have similar ??Os of +3.4 to +6.5, but ??Nd of -0.9 to -2.6. The similar ??Os, but lower ??Nd , suggest that some magmas from the same OIB-type, mantle source were contaminated by lithospheric components. A differentiated ankaramite flow, associated with the top of the stratigraphically higher Morongovsky suite, has ??Os of +9.8 to +10.2 and ??Nd of +1.3 to +1.4. The higher ??Os may indicate that the plume source was heterogeneous with respect to osmium isotopic composition, consistent with osmium isotopic measurements in rocks from other plume sources. Mg-rich, alkaline rocks (meymechites) from the Guli area that erupted much nearer the end of the flood-basalt event have ??Os of -1.2 to -2.6 and ??Nd of +3.7 to +4.9. These rocks were probably produced by low degrees of partial melting of mantle after the main stages of flood-basalt production. -from Authors

  16. Europium, Samarium, and Neodymium Isotopic Fractions in Metal-Poor Stars

    NASA Astrophysics Data System (ADS)

    Roederer, Ian U.; Lawler, James E.; Sneden, Christopher; Cowan, John J.; Sobeck, Jennifer S.; Pilachowski, Catherine A.

    2008-03-01

    We have derived isotopic fractions of europium (Eu), samarium (Sm), and neodymium (Nd) in two metal-poor giants with differing neutron-capture nucleosynthetic histories. These isotopic fractions were measured from new very high resolution (R~120,000), high signal-to-noise (S/N~160-1000) spectra obtained with the 2dCoudé spectrograph of McDonald Observatory's 2.7 m Smith telescope. Synthetic spectra were generated using recent high-precision laboratory measurements of hyperfine and isotopic subcomponents of several transitions of these elements and matched quantitatively to the observed spectra. We interpret our isotopic fractions by the nucleosynthesis predictions of the stellar model, which models s-process nucleosynthesis in the physical conditions expected in a low-mass, thermally-pulsing star on the AGB, and the classical method, which assumes that s-process nucleosynthesis can be approximated by a steady neutron flux impinging upon Fe-peak seed nuclei. These two approaches predict the relative contributions to the Solar System n-capture abundances from the s- and r-processes and, by extension, the relative contributions of these two process to material in metal-poor stars. Our Eu isotopic fraction in HD 175305 is consistent with an r-process origin by the classical method and is consistent with both an r-process and s-process origin by the stellar model. Our Sm isotopic fraction in HD 175305 is consistent with a predominantly r-process origin by both methods, and our Sm isotopic fraction in HD 196944 is consistent with a pure s-process origin by both methods as well. Our Nd isotopic fractions in both stars are consistent with either r-process and s-process origins by both methods. The Eu and Sm isotopic fraction estimates argue for an r-process origin for the rare-earth elements in HD 175305 and an s-process origin for them in HD 196944, in excellent agreement with previous studies of the elemental abundance distributions in these stars. This study for the

  17. Neodymium and strontium isotopic constraints on soil sources in Barbados, West Indies

    NASA Astrophysics Data System (ADS)

    Borg, Lars E.; Banner, Jay L.

    1996-11-01

    Neodymium and strontium isotopic compositions and Sm/Nd ratios are used to constrain the sources of silicate-rich soils developed on uplifted Pleistocene coral-reef limestones on Barbados, West Indies. The geographic and geologic setting of Barbados facilitates the application of these tracers to the evaluation of the following soil sources: (1) Pleistocene reef limestone regolith, (2) Tertiary carbonate rocks, sandstones, and mudstones that are exposed in northeastern Barbados, (3) volcanic ash erupted from the Lesser Antilles arc, (4) Saharan dust transported by trade winds, and (5) fertilizer. The soils have ɛNd values that range from -6.6 to -1.9, 87Sr /86Sr values of 0.70890 to 0.71067, and Sm/Nd ratios of 0.223-0.260. The Pleistocene limestone component is the most significant source of Sr in the soils and a negligible source of Nd. Comparison of Sm and Nd concentrations and neodymium isotopic compositions of soil samples that are weathered to varying extents indicates that Sm and Nd are relatively unfractionated and retained in the soils during weathering. ɛNd and Sm/Nd variations in the soils, therefore, primarily reflect the compositions and proportions of the silicate sources. Mass balance calculations based on SmNd systematics require that the silicate soil components contain between 30-85% volcanic ash, with the remaining silicate fraction comprised of old, continentally-derived sediment. In contrast to Sm and Nd, Sr is mobilized and removed from the soils during weathering. Strontium from volcanic and carbonate sources is preferentially removed relative to continental silicate sources. The strontium isotopic compositions of the soils, therefore, reflect the combined effects of the degree of weathering and the compositions and proportions of the soil sources. Mass balance calculations indicate that at least 35-60% of the initial Sr in the soils has been removed by weathering. These results illustrate (1) the utility of radiogenic isotopes in

  18. Holocene fluctuations of neodymium isotope ratios in eastern Fram Strait sediments - An indication for deepwater variability?

    NASA Astrophysics Data System (ADS)

    Werner, K.; Frank, M.; Teschner, C.; Zieringer, M.; Spielhagen, R. F.

    2012-04-01

    The Fram Strait as the only deep water connection of the world's oceans to the Arctic plays a substantial role for the heat influx to the Arctic Ocean and controls freshening of the Nordic Seas through Arctic sea ice export. Large amounts of warm and saline Atlantic Water derived from the North Atlantic Drift transport most of the heat through eastern Fram Strait to the Arctic basin, resulting in year-round ice-free conditions. Arctic sea ice and cold and fresh waters exit the western part of the strait southward along the Greenland shelf. However, little is still known about the water mass transport at intermediate and bottom water depths in the Fram Strait. High-resolution Holocene sediment sequences from the Western Svalbard margin have been investigated for its neodymium isotope ratios stored in ferromanganese oxyhydroxide coatings of the sediment to derive information on the source of bottom seawater passing the site. The radiogenic isotope data are compared to a multitude of proxy indicators for the climatic and oceanographic variability in the eastern Fram Strait during the past 8,500 years. In order to obtain a calibration of the Nd isotope compositions extracted from sediments to modern bottom water mass signatures in the area, a set of core top and water samples from different water depths in the Fram Strait was additionally investigated for its present-day Nd isotope signatures. A significantly higher inflow of deepwater produced in the Nordic Seas to the core site is inferred for the earlier periods of the Holocene. Cooler surface water conditions and increased sea ice abundances during the late Holocene coincide with more radiogenic Nd isotope ratios likely resembling the neoglacial trend of the northern North Atlantic.

  19. The identification of meteorite inclusions with isotope anomalies

    NASA Astrophysics Data System (ADS)

    Papanastassiou, D. A.; Brigham, C. A.

    1989-03-01

    Ca-Al refractory inclusions with characteristic chemical and mineralogical compositions show an enhanced occurrence of 20 pct of isotope anomalies reflecting unknown nucleosynthetic effects for O and Mg. The anomalies are characterized by large isotope fractionation in Mg, apparent deficits in Mg-26/Mg-24, and large correlated effects for isotopes of Ca, Ti, and Cr. These isotope patterns define exotic components depleted in the most neutron-rich isotopes of Ca, Ti, and Cr, or components depleted in isotopes produced in explosive O and Si burning. An opaque assemblage within one of the inclusions yields isotope anomalies in Cr similar to the bulk inclusion and must be intrinsically part of the inclusion and not a trapped, foreign grain aggregate.

  20. 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 μ84Sr 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 μ84Sr patterns across leaching samples for individual chondrites differed from one another. The highest μ84Sr 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 μ84Sr 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 μ84Sr-ɛ54Cr 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 μ84Sr and ɛ54Cr values, whereas carbonaceous chondrites and noncarbonaceous meteorites had intermediate and the lowest μ84Sr and ɛ54Cr values, respectively. The positive trend was interpreted as resulting from global thermal processing in which sublimation of high μ84Sr and ɛ54Cr carriers generated the excess μ84Sr and ɛ54Cr signatures in CAIs, while noncarbonaceous planetesimals accreted from materials that underwent significant thermal processing and thus had relatively low μ84Sr and ɛ54Cr 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

  1. Coupled isotopic systematics of surface cerium and neodymium in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Tazoe, H.; Obata, H.; Gamo, T.

    2011-04-01

    Trace metals are known to be essential elements in marine ecosystems. Radiogenic isotopes of neodymium (Nd) have been used as tracers in many recent oceanic trace metal studies, although, among rare earth elements, cerium (Ce) isotopes might be an interesting complementary tracer for particle reactive and lithogenic metals such as manganese. This study determined the 138Ce/142Ce ratios in surface waters of the Pacific Ocean and its surrounding marginal seas: the Sulu Sea, the South China Sea, the East China Sea, and the South Australian Basin. The 138Ce/142Ce and 143Nd/144Nd data are discussed in terms of the sources of rare earth elements and elemental fractionation between Ce and Nd in the marine environment. In the Western North Pacific Central Water, East China Sea, and South China Sea, isotopic compositions of Ce (ɛCe = +0.7 to 1.4) are most affected by radiogenic Ce of continental origin. In contrast, less radiogenic isotopic compositions of Ce (ɛCe = -0.4 to +0.3) in the Pacific Equatorial Water were observed locally near volcanic islands such as New Guinea Island, suggesting the influence of mantle-derived Ce. Compared with Nd, the isotopic composition of Ce showed a heterogeneous distribution in a given surface water mass, reflecting the importance of local sources. Variations of isotopic compositions and concentrations of Ce in the western Equatorial Pacific and the East China Sea suggest that lithogenic Ce is supplied and scavenged by particle-dissolved interaction near the margins. Radiogenic Ce in the Western North Pacific Central Water, which is more continental-like than Nd isotopes, suggests direct input by atmospheric dust into the North Pacific Ocean. The isotopic distribution of Ce is sensitive to aeolian supply to the surface waters of the open ocean. This unique feature indicates that the 138Ce/142Ce ratio can be a useful chemical tracer for lithogenic trace elements such as iron and manganese, which have short oceanic residence time.

  2. Past Hydrological Variability in the Congo Basin inferred from Neodymium Isotopes

    NASA Astrophysics Data System (ADS)

    Bayon, G.

    2015-12-01

    Major events of vegetation changes and soil erosion occurred in Central Africa during the last few millennia, at a time when the first farmers settled in the rainforest. The palaeoclimatic context in which these environmental changes took place still remains poorly constrained. Improving our knowledge on the drivers of past hydrological variability in Central Africa is important to further evaluate the relative role of climate versus humans in shaping late Holocene African landscapes. In this study, we have used neodymium (Nd) isotopes in a marine sediment core to reconstruct the composition of the sediment load exported from the Congo Basin during the Holocene. Core KZR23 was recovered at 2200 m water depth from within the Congo submarine canyon and is characterized by high sedimentation rates (about 2m/kyr), thereby allowing reconstruction of past river sediment discharge at an unprecedented high temporal resolution. A suite of river particulate samples collected from the main tributaries within the Congo watershed was analyzed in order to tag each major sub-basin with the characteristic geochemical and Nd isotopic signatures of its source region. In parallel, an annual series of suspended particles sampled on a monthly basis at the Congo River ORE-HYBAM station (Brazzaville) was also analyzed to characterize the seasonality of sediment provenance in relation with present hydrological cycle. Using Nd isotopes as tracers for sediment provenance together and other proxy data for past erosion, vegetation and rainfall patterns (i.e. bulk sediment radiocarbon data, pollens, biomarkers, compound-specific isotope analyses), we will provide a more comprehensive picture of past hydrological variability in the Congo Basin for the Holocene period.

  3. Reduced North Atlantic Deep Water flux to the glacial Southern Ocean inferred from neodymium isotope ratios

    PubMed

    Rutberg; Hemming; Goldstein

    2000-06-22

    The global circulation of the oceans and the atmosphere transports heat around the Earth. Broecker and Denton suggested that changes in the global ocean circulation might have triggered or enhanced the glacial-interglacial cycles. But proxy data for past circulation taken from sediment cores in the South Atlantic Ocean have yielded conflicting interpretations of ocean circulation in glacial times--delta13C variations in benthic foraminifera support the idea of a glacial weakening or shutdown of North Atlantic Deep Water production, whereas other proxies, such as Cd/Ca, Ba/Ca and 231Pa/230Th ratios, show little change from the Last Glacial Maximum to the Holocene epoch. Here we report neodymium isotope ratios from the dispersed Fe-Mn oxide component of two southeast Atlantic sediment cores. Both cores show variations that tend towards North Atlantic signatures during the warm marine isotope stages 1 and 3, whereas for the full glacial stages 2 and 4 they are closer to Pacific Ocean signatures. We conclude that the export of North Atlantic Deep Water to the Southern Ocean has resembled present-day conditions during the warm climate intervals, but was reduced during the cold stages. An increase in biological productivity may explain the various proxy data during the times of reduced North Atlantic Deep Water export. PMID:10879531

  4. Mineralogy of the mid-ocean-ridge basalt source from neodymium isotopic composition of abyssal peridotites.

    PubMed

    Salters, Vincent J M; Dick, Henry J B

    2002-07-01

    Inferring the melting process at mid-ocean ridges, and the physical conditions under which melting takes place, usually relies on the assumption of compositional similarity between all mid-ocean-ridge basalt sources. Models of mantle melting therefore tend to be restricted to those that consider the presence of only one lithology in the mantle, peridotite. Evidence from xenoliths and peridotite massifs show that after peridotite, pyroxenite and eclogite are the most abundant rock types in the mantle. But at mid-ocean ridges, where most of the melting takes place, and in ophiolites, pyroxenite is rarely found. Here we present neodymium isotopic compositions of abyssal peridotites to investigate whether peridotite can indeed be the sole source for mid-ocean-ridge basalts. By comparing the isotopic compositions of basalts and peridotites at two segments of the southwest Indian ridge, we show that a component other than peridotite is required to explain the low end of the (143)Nd/(144)Nd variations of the basalts. This component is likely to have a lower melting temperature than peridotite, such as pyroxenite or eclogite, which could explain why it is not observed at mid-ocean ridges. PMID:12097907

  5. The effect of particulate dissolution on the neodymium (Nd) isotope and Rare Earth Element (REE) composition of seawater

    NASA Astrophysics Data System (ADS)

    Pearce, Christopher R.; Jones, Morgan T.; Oelkers, Eric H.; Pradoux, Catherine; Jeandel, Catherine

    2013-05-01

    The exchange of material between particulates and seawater along the continental margins, a process commonly referred to as boundary exchange, is thought to play a significant role in controlling the neodymium (Nd) isotope and Rare Earth Element (REE) composition of the oceans. This study provides experimental verification of this concept by quantifying the effect of particulate dissolution in seawater on dissolved ɛNd and REE compositions. Three closed-system experiments were performed using basaltic particulate material of riverine, estuarine and marine origin. The release of Nd from this basaltic material increased the ɛNd composition of seawater in all three experiments, with a ɛNd value close to that of the associated sediment being achieved within 80 days in all experiments. Mass balance indicates that up to 0.4% of Nd from the particulate phase was released to the seawater over the duration of these experiments, and that the rate of release varied according to particulate origin and surface area. Progressive variations in the PAAS normalised REE patterns, as well as the Eu and Ce anomalies and La/Yb ratio, demonstrate that REEs were also transferred from the basaltic particulates to seawater during the experiments. Despite evidence for the release of REEs from the particulate material, dissolved REE abundances decreased during the experiments, and are thought to reflect incorporation into the REE-phosphate mineral rhabdophane. Together these experimental results confirm that elemental release from basaltic sediments on the ocean margins is a significant marine flux that can have a major control on the composition of seawater.

  6. Titanium isotopic anomalies in chondrules from carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Niemeyer, S.

    1988-02-01

    Isotopic analyses of Ti from a suite of eight Allende chondrules were conducted to determine whether any relationship exists between the composition and structure of a chondrule and the Ti isotopic patterns. Four of the eight chondrules displayed well-resolved anomalies with respect to Ti-50/Ti-46 ratio, which ranged from a Ti-50 deficit of two epsilon-units to a T-50 excess of nine epsilon-units. No clear link was found between the structure of the chondrules and the Ti anomalies (although the chondrule with by far the largest Ti isotopic anomaly was also Al-rich, suggesting that there might exist a complicated relationship between the degree of refractory enrichment and the magnitude of Ti isotopic anomalies.

  7. Denmark Strait water circulation traced by heterogeneity in neodymium isotopic compositions

    NASA Astrophysics Data System (ADS)

    Lacan, Francois; Jeandel, Catherine

    2004-01-01

    Seawater neodymium isotopic composition ( ɛNd) and rare earth element (REE) concentrations were measured along four hydrologic sections within the East Greenland Current (EGC), between the Fram and the Denmark Straits, during summer 1999. EGC intermediate waters, between 77°N and 70°N, displaying similar hydrological characteristics as Denmark Strait Overflow Water (DSOW), had very constant REE characteristics and ɛNd value of -10.9. This constancy reveals the absence of lithogenic input, from the East Greenland margin, into intermediate waters in this area, corroborating previous dissolved aluminum data. The DSOW was characterized by ɛNd=-8.4±1.4. This value can be explained by the imprint of lithogenic formations, mainly basaltic, bordering the Denmark Strait on the intermediate waters described above. However, granitic Precambrian formations seem to contribute, although more slightly, to defining the DSOW Nd signature. This double influence could explain the heterogeneity of the Denmark Strait waters. These results provide a better understanding of the DSOW Nd signature, allowing a better use of this tracer in the study of present and past North Atlantic Deep Water dynamics. Atlantic Water was present at a station located at the mouth of Nansen Fjord, on the western side of Denmark Strait. We suggest that this water reaches the fjord intermittently as isolated water lenses or eddies detached from the northward flowing branch of the Irminger current.

  8. A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Piotrowski, Alexander M.; Galy, Albert; McCave, I. Nicholas

    2012-08-01

    The use of neodymium (Nd) isotopes to reconstruct past water mass mixing relies upon the quasi-conservative behaviour of this tracer, whereas recent studies in the modern oceans have suggested that boundary exchange, involving the addition of Nd from ocean margin sediments, may be an important process in the Nd cycle. Here we suggest that the relative importance of water mass advection versus boundary exchange can be assessed where the deep western boundary current in the Indian Ocean flows past the Madagascan continental margin; a potential source of highly unradiogenic Nd. Foraminiferal coatings and bulk sediment reductive leachates are used to reconstruct bottom water Nd isotopic composition (εNd) in 8 Holocene age coretops, with excellent agreement between the two methods. These data record spatial variability of ∼4 εNd units along the flow path of Circumpolar Deep Water; εNd≈-8.8 in the deep southern inflow upstream of Madagascar, which evolves towards εNd≈-11.5 offshore northern Madagascar, whereas εNd≈-7.3 where deep water re-circulates in the eastern Mascarene Basin. This variability is attributed to boundary exchange and, together with measurements of detrital sediment εNd, an isotope mass balance suggests a deep water residence time for Nd of ≤400 yr along the Madagascan margin. Considering deglacial changes, a core in the deep inflow upstream of Madagascar records εNd changes that agree with previous reconstructions of the Circumpolar Deep Water composition in the Southern Ocean, consistent with a control by water mass advection and perhaps indicating a longer residence time for Nd in the open ocean away from local sediment inputs. In contrast, sites along the Madagascan margin record offset εNd values and reduced glacial-interglacial variability, underlining the importance of detecting boundary exchange before inferring water mass source changes from Nd isotope records. The extent of Madagascan boundary exchange appears to be unchanged

  9. Some key issues in isotopic anomalies - Astrophysical history and aggregation

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1982-01-01

    Astrophysical history, particularly that period extending from stellar nucleosynthesis events to the formation of meteorites, is discussed as the key element for the understanding of isotopic anomalies in meteorites. The bulk homogeneity of the interstellar medium is considered, and it is argued that, despite the presence of spatial inhomogeneities due to different nucleosynthesis rates in different parts of the galaxy and supernova ejecta, a cosmic chemical memory of nucleosynthesis patterns, rather than an inhomogeneous injection, is the source of isotopic anomalies. According to this view, volatility patterns and some isotopic patterns are mapped onto a grain-size spectrum, and the FUN systematics may be explained by interstellar sputtering. Furthermore, meteoritic He and Ne abundances are inferred to be presolar, and the ubiquitous titanium isotopic anomalies are explained by processes of chemical fixation and condensation in varying environments.

  10. Zinc isotope anomalies. [in Allende meteorite

    NASA Technical Reports Server (NTRS)

    Volkening, J.; Papanastassiou, D. A.

    1990-01-01

    The Zn isotope composition in refractory-element-rich inclusions of the Allende meteorite are determined. Typical inclusions contain normal Zn. A unique inclusion of the Allende meteorite shows an excess for Zn-66 of 16.7 + or - 3.7 eu (1 eu = 0.01 percent) and a deficit for Zn-70 of 21 + or - 13 eu. These results indicate the preservation of exotic components even for volatile elements in this inclusion. The observed excess Zn-66 correlates with excesses for the neutron-rich isotopes of Ca-48, Ti-50, Cr-54, and Fe-58 in the same inclusion.

  11. Zinc isotope anomalies in Allende meteorite inclusions

    NASA Technical Reports Server (NTRS)

    Loss, R. D.; Lugmair, G. W.

    1990-01-01

    The isotopic compositions of Zn, Cr, Ti, and Ca have been measured in a number of CAIs from the Allende meteorite. The aim was to test astrophysical models which predict large excesses of Zn-66 to accompany excesses in the neutron-rich isotopes of Ca, Ti, Cr, and Ni. Some of the CAIs show clearly resolved but small excesses for Zn-66 which are at least an order of magnitude smaller than predicted. This result may simply reflect the volatility and chemical behavior of Zn as compared to the other (more refractory) anomalous elements found in these samples. Alternatively, revision of parameters and assumptions used for the model calculations may be required.

  12. 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).

  13. 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

  14. A spectacular nitrogen isotope anomaly in Bencubbin

    NASA Technical Reports Server (NTRS)

    Prombo, C. A.; Clayton, R. N.

    1985-01-01

    Results of isotopic measurements on an unusual stony-iron meteorite named Bencubbin, which was found in Western Australia in 1930, are reported. Nitrogen from both the metallic and stony parts of the Bencubbin meteorite was analyzed, and in both materials large excesses of (15)N were found, resulting in values of the (14)N/(15)N abundance ratios as low as 137. That is, (15)N is enriched in Bencubbin by about a factor of two relative to terrestrial nitrogen. This is the largest (15)N enrichment of any known natural material. The effect is so large that chemical processes are probably inadequate to account for it. Nuclear processes which may be responsible for the anomalous isotope abundance are discussed.

  15. 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.

  16. Palladium Isotopic Evidence for Nucleosynthetic and Cosmogenic Isotope Anomalies in IVB Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Mayer, Bernhard; Wittig, Nadine; Humayun, Munir; Leya, Ingo

    2015-08-01

    The origin of ubiquitous nucleosynthetic isotope anomalies in meteorites may represent spatial and/or temporal heterogeneity in the sources that supplied material to the nascent solar nebula, or enhancement by chemical processing. For elements beyond the Fe peak, deficits in s-process isotopes have been reported in some (e.g., Mo, Ru, W) but not all refractory elements studied (e.g., Os) that, among the iron meteorites, are most pronounced in IVB iron meteorites. Palladium is a non-refractory element in the same mass region as Mo and Ru. In this study, we report the first precise Pd isotopic abundances from IVB irons to test the mechanisms proposed for the origin of isotope anomalies. First, this study determined the existence of a cosmogenic neutron dosimeter from the reaction 103Rh(n, β-)104Pd in the form of excess 104Pd, correlated with excess 192Pt, in IVB irons. Second, all IVB irons show a deficit of the s-process only isotope 104Pd (\\varepsilon 104Pd = -0.48 ± 0.24), an excess of the r-only isotope 110Pd (\\varepsilon 110Pd = +0.46 ± 0.12), and no resolvable anomaly in the p-process 102Pd (\\varepsilon 102Pd = +1 ± 1). The magnitude of the Pd isotope anomaly is about half that predicted from a uniform depletion of the s-process yields from the correlated isotope anomalies of refractory Mo and Ru. The discrepancy is best understood as the result of nebular processing of the less refractory Pd, implying that all the observed nucleosynthetic anomalies in meteorites are likely to be isotopic relicts. The Mo-Ru-Pd isotope systematics do not support enhanced rates of the 22Ne(α,n)25Mg neutron source for the solar system s-process.

  17. Iron isotope anomalies. [in carbonaceous meteorites

    NASA Technical Reports Server (NTRS)

    Voelkening, J.; Papanastassiou, D. A.

    1989-01-01

    Precise determinations of the Fe isotope abundances yield identical results for a terrestrial standard and for samples of carbonaceous meteorites. Fe-54/Fe-56 = 0.062669; Fe-57/Fe-56 = 0.023261 + or - 0.000002; and Fe-58/Fe-56 = 0.0031132 + or - 0.0000011 are found. Refractory element-rich inclusions from the Allende carbonaceous meteorite yield hints of deficits in Fe-57/Fe-56 of up to -3.9 + or - 2.6 parts in 10,000 and a hint of excess in Fe-58/Fe-56 of up to 27 + or - 11 parts in 10,000. One special (FUN) inclusion shows a large excess of 2.9 percent, uniquely attributable to Fe-58. This excess correlates with large excesses in the same inclusion in the neutron-rich isotopes Ca-48, Ti-50 and Cr-54. These results strengthen the evidence for an exotic nucleosynthetic component produced by neutron-rich, statistical equilibrium burning, and injected into the interstellar medium.

  18. Neodymium isotope analyses after combined extraction of actinide and lanthanide elements from seawater and deep-sea coral aragonite

    NASA Astrophysics Data System (ADS)

    Struve, Torben; van de Flierdt, Tina; Robinson, Laura F.; Bradtmiller, Louisa I.; Hines, Sophia K.; Adkins, Jess F.; Lambelet, Myriam; Crocket, Kirsty C.; Kreissig, Katharina; Coles, Barry; Auro, Maureen E.

    2016-01-01

    Isotopes of the actinide elements protactinium (Pa), thorium (Th), and uranium (U), and the lanthanide element neodymium (Nd) are often used as complementary tracers of modern and past oceanic processes. The extraction of such elements from low abundance matrices, such as seawater and carbonate, is however labor-intensive and requires significant amounts of sample material. We here present a combined method for the extraction of Pa, Th, and Nd from 5 to 10 L seawater samples, and of U, Th, and Nd from <1 g carbonate samples. Neodymium is collected in the respective wash fractions of Pa-Th and U-Th anion exchange chromatographies. Regardless of the original sample matrix, Nd is extracted during a two-stage ion chromatography, followed by thermal ionization mass spectrometry (TIMS) analysis as NdO+. Using this combined procedure, we obtained results for Nd isotopic compositions on two GEOTRACES consensus samples from Bermuda Atlantic Time Series (BATS), which are within error identical to results for separately sampled and processed dedicated Nd samples (ɛNd = -9.20 ± 0.21 and -13.11 ± 0.21 for 15 and 2000 m water depths, respectively; intercalibration results from 14 laboratories: ɛNd = -9.19 ± 0.57 and -13.14 ± 0.57). Furthermore, Nd isotope results for an in-house coral reference material are identical within analytical uncertainty for dedicated Nd chemistry and after collection of Nd from U-Th anion exchange chromatography. Our procedure does not require major adaptations to independently used ion exchange chromatographies for U-Pa-Th and Nd, and can hence be readily implemented for a wide range of applications.

  19. Dynamic intermediate ocean circulation in the North Atlantic during Heinrich Stadial 1: A radiocarbon and neodymium isotope perspective

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Crocket, Kirsty C.; Flierdt, Tina; Robinson, Laura F.; Adkins, Jess F.

    2014-11-01

    The last deglaciation was characterized by a series of millennial-scale climate events that have been linked to deep ocean variability. While often implied in interpretations, few direct constraints exist on circulation changes at mid-depths. Here we provide new constraints on the variability of deglacial mid-depth circulation using combined radiocarbon and neodymium isotopes in 24 North Atlantic deep-sea corals. Their aragonite skeletons have been dated by uranium-series, providing absolute ages and the resolution to record centennial-scale changes, while transects spanning the lifetime of a single coral allow subcentennial tracer reconstruction. Our results reveal that rapid fluctuations of water mass sourcing and radiocarbon affected the mid-depth water column (1.7-2.5 km) on timescales of less than 100 years during the latter half of Heinrich Stadial 1. The neodymium isotopic variability (-14.5 to -11.0) ranges from the composition of the modern northern-sourced waters towards more radiogenic compositions, suggesting the presence of a greater southern-sourced component at some times. However, in detail, simple two-component mixing between well-ventilated northern-sourced and radiocarbon-depleted southern-sourced water masses cannot explain all our data. Instead, corals from ~15.0 ka and ~15.8 ka may record variability between southern-sourced intermediate waters and radiocarbon-depleted northern-sourced waters, unless there was a major shift in the neodymium isotopic composition of the northern end-member. In order to explain the rapid shift towards the most depleted radiocarbon values at ~15.4 ka, we suggest a different mixing scenario involving either radiocarbon-depleted deep water from the Greenland-Iceland-Norwegian Seas or a southern-sourced deep water mass. Since these mid-depth changes preceded the Bolling-Allerod warming and were apparently unaccompanied by changes in the deep Atlantic, they may indicate an important role for the intermediate ocean in

  20. More on Ru Endemic Isotope Anomalies in Meteorites

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    We reported last year on endemic isotope anomalies for Ru in iron meteorites, pallasites, ordinary chondrites, and on a whole-rock sample of Allende. We have extended the Ru measurements to more meteorites, to refractory Ca-Al-rich inclusions (CAI) from Allende, and to a whole rock sample of Murchison (CM2). In a companion abstract we report on new measurements for the Mo isotopes, in some of the same samples. There has been a renewed interest in searching for isotope anomalies in this nuclide region, as Ru and Mo include many isotopes from r-, s-, and p-process nucleosynhesis. Furthermore, the Ru and Mo p-process isotopes show atypically high abundances, which have been hard to explain through the standard nucleosynthetic processes. Effects are possible in Ru-98 and Ru-99 from Tc-98 (with a poorly known t(sub 1/2)=4.2 to 10Ma) and from Tc-99 (t(sub 1/2)=0.21Ma). Natural Tc is now extinct on Earth due to the short half-lives, but may have been present in the early solar system. Both radiogenic and general isotope anomalies are important in understanding the processes for the formation of the early solar system. The current emphasis on Ru and Mo is also the result of the development of Negative-ion Thermal Ionization Mass Spectrometry and of Multiple-Collector, Inductively-Coupled-Mass-Spectrometry. We have also developed specific chemical siparation techniques for Ru, which eliminated mass interference effects.

  1. NEUTRON-RICH CHROMIUM ISOTOPE ANOMALIES IN SUPERNOVA NANOPARTICLES

    SciTech Connect

    Dauphas, N.; Remusat, L.; Papanastassiou, D. A.; Guan, Y.; Ma, C.; Eiler, J. M.; Chen, J. H.; Roskosz, M.; Stodolna, J.

    2010-09-10

    Neutron-rich isotopes with masses near that of iron are produced in Type Ia and II supernovae (SNeIa and SNeII). Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of {sup 54}Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of SNe, offering the opportunity to study the nucleosynthesis of iron-peak nuclei in ways that complement spectroscopic observations and can inform models of stellar evolution. However, despite almost two decades of extensive search, the carrier of {sup 54}Cr anomalies is still unknown, presumably because it is fine grained and is chemically labile. Here, we identify in the primitive meteorite Orgueil the carrier of {sup 54}Cr anomalies as nanoparticles (<100 nm), most likely spinels that show large enrichments in {sup 54}Cr relative to solar composition ({sup 54}Cr/{sup 52}Cr ratio >3.6 x solar). Such large enrichments in {sup 54}Cr can only be produced in SNe. The mineralogy of the grains supports condensation in the O/Ne-O/C zones of an SNII, although a Type Ia origin cannot be excluded. We suggest that planetary materials incorporated different amounts of these nanoparticles, possibly due to late injection by a nearby SN that also delivered {sup 26}Al and {sup 60}Fe to the solar system. This idea explains why the relative abundance of {sup 54}Cr and other neutron-rich isotopes vary between planets and meteorites. We anticipate that future isotopic studies of the grains identified here will shed new light on the birth of the solar system and the conditions in SNe.

  2. Neutron-poor Nickel Isotope Anomalies in Meteorites

    NASA Astrophysics Data System (ADS)

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Russell, Sara; Elliott, Tim

    2012-10-01

    We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as ɛ60Ni58/61, ɛ62Ni58/61, and ɛ64Ni58/61, or the parts per ten thousand deviations from a terrestrial reference, the NIST SRM 986 standard, of the 58Ni/61Ni internally normalized 60Ni/61Ni, 62Ni/61Ni, and 64Ni/61Ni ratios. The chondrites show a range of 0.15, 0.29, and 0.84 in ɛ60Ni58/61, ɛ62Ni58/61, and ɛ64Ni58/61 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 ɛ62Ni58/61 and ɛ64Ni58/61, 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 58Ni. We also determined to high precision (~10 ppm per AMU) the mass-dependent fractionation of two meteorite samples which span the range of ɛ62Ni58/61 and ɛ64Ni58/61. These analyses show that "absolute" ratios of 58Ni/61Ni vary between these two samples whereas those of 62Ni/61Ni and 64Ni/61Ni do not. Thus, Ni isotopic differences seem most likely explained by variability in the neutron-poor 58Ni, and not correlated anomalies in the neutron-rich isotopes, 62Ni and 64Ni. 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

  3. NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES

    SciTech Connect

    Steele, Robert C. J.; Coath, Christopher D.; Regelous, Marcel; Elliott, Tim; Russell, Sara

    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

  4. On isotopic anomalies in samarium. [in Allende meteorite

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1979-01-01

    The solar isotopic composition of Sm is decomposed into s, r, and p components. The anomaly pattern discovered by Lugmair et al. (1978) in EK1-04 Allende inclusion can be presented as a fractionation of the average s-pattern from the average r-pattern. This representation requires a fractionation of 0.029%/(amu) and either (1) a 0.42% deficiency of s relative to r and a 0.15% deficiency of p relative to r, or (2) a 0.42% excess of r relative to s and a 0.27% excess of p relative to s. The nature of this anomaly suggest a systematic physical fractionation of r, s, and p nuclei from each other in the initial condition leading to EK1-04. A neighboring supernova injection would not be expected to produce this anomaly.

  5. Wolf-Rayet Stars and the Isotopic Anomaly Connection

    NASA Astrophysics Data System (ADS)

    Arnould, M.; Paulus, G.; Meynet, G.

    1993-07-01

    Isotopic anomalies are now known to be carried by high-temperature inclusions of primitive meteorites that formed from solar reservoirs out of equilibrium with the rest of the solar nebula, as well as by various types of grains (diamond, graphite, SiC) that are considered to be of circumstellar origin, and have survived the process of incorporation into the solar system (see e.g. [1] for a recent review). Such anomalies provide new clues to many important astrophysical problems, and raise the question of their nucleosynthetic origin. In fact, they offer the exciting perspective of confronting abundance observations with nucleosynthesis models for a very limited number of events, even possibly a single one. This situation is in marked contrast with the one encountered when trying to understand the bulk solar system composition. Up to now, Red Giant stars, massive mass loosing objects (of the Wolf-Rayet type), novae or supernovae have been proposed as possible contributors to the observed anomalies. In this paper, we revisit the role that could possibly be played in that respect by Wolf-Rayet (WR) stars. Wolf-Rayet stars are appealing isotopic anomaly contributors for many reasons. In particular (1) they are observed to loose mass at very large rates that can exceed 10^-5M solar masses yr^-l, the ejected material being contaminated with the products of hydrogen and helium burning, and (2) certain WR stars are known to make dust episodically in their winds [e.g., 2]. In addition, the role of WR stars would be well in line with the "bing-bang" model for the isotopic anomalies promoted by Reeves [3]. The aim of this contribution is to extent and update previous calculations [4,5] of the isotopic anomalies that could be carried by the wind of WR stars of various masses and initial compositions during different phases of their evolution, those anomalies possibly loading circumstellar WR grains. The calculation of the WR wind composition is performed on grounds of detailed

  6. Seawater-derived neodymium isotope records in the Chukchi Sea, western Arctic Ocean during Holocene: implications for oceanographic circulation

    NASA Astrophysics Data System (ADS)

    Lee, Borom; Nam, Seung-Il; Huh, Youngsook; Lee, Mi Jung

    2015-04-01

    Changes in oceanographic circulation in the Artic have a large influence on the global oceanic and climate system of the Earth through the geological times. In particular, freshwater input from the North Pacific to the western Arctic Ocean affects the Atlantic meridional overturning circulation (AMOC) after the opening of the Bering Strait. Seawater-derived neodymium isotope in marine sediments has been used as a proxy to trace the origin of water masses and oceanic circulation system. The global average residence time of Nd is shorter than the global ocean mixing time and dissolved Nd in seawater behaves quasi-conservatively. In the modern Arctic Ocean, the Nd isotope distribution is dominated by Atlantic source water, although the circum-Arctic riverine discharge and Pacific-derived waters also have noticeable impacts. In this study, we investigated seawater-derived neodymium isotope records from a sediment core recovered from the Chukchi Sea to understand the changes in hydrograhic circulation of the western Arctic during the Holocene. A gravity core, ARA02B 01A, was collected on the northern shelf of the Chukchi Sea (73°37.8939'N, 166°30.9838'W, ca. 111 m in water depth) during the RV Araon expedition in 2011. To obtain seawater-derived Nd records, we extracted Fe-Mn oxide coatings as an authigenic fraction from bulk sediments by leaching with acid-reducing solution after removing carbonate by leaching with acetic acid. Our preliminary results might show a general pattern of increasing radiogenic ɛNd values through Holocene intervals. Therefore, it implies that ɛNd results may be related with variations in the intensity of Bering Strait inflow during the last ~9.31 ka BP. The radiogenic trend was strongly pronounced from the late Holocene (ɛNd -7.23; ca. 8.84 ka BP) to the middle Holocene (ɛNd -4.78; ca. 6.18 ka BP) and vaguely during the middle Holocene. After 4.13 ka BP, ɛNd values were increased again from -4.86 to -4.03 at 0.57 ka BP. But 87Sr/86Sr

  7. Mass Fractionation Laws, Mass-Independent Effects, and Isotopic Anomalies

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Schauble, Edwin A.

    2016-06-01

    Isotopic variations usually follow mass-dependent fractionation, meaning that the relative variations in isotopic ratios scale with the difference in mass of the isotopes involved (e.g., δ17O ≈ 0.5×δ18O). In detail, however, the mass dependence of isotopic variations is not always the same, and different natural processes can define distinct slopes in three-isotope diagrams. These variations are subtle, but improvements in analytical capabilities now allow precise measurement of these effects and make it possible to draw inferences about the natural processes that caused them (e.g., reaction kinetics versus equilibrium isotope exchange). Some elements, in some sample types, do not conform to the regularities of mass-dependent fractionation. Oxygen and sulfur display a rich phenomenology of mass-independent fractionation, documented in the laboratory, in the rock record, and in the modern atmosphere. Oxygen in meteorites shows isotopic variations that follow a slope-one line (δ17O ≈ δ18O) whose origin may be associated with CO photodissociation. Sulfur mass-independent fractionation in ancient sediments provides the tightest constraint on the oxygen partial pressure in the Archean and the timing of Earth's surface oxygenation. Heavier elements also show departures from mass fractionation that can be ascribed to exotic effects associated with chemical reactions such as magnetic effects (e.g., Hg) or the nuclear field shift effect (e.g., U or Tl). Some isotopic variations in meteorites and their constituents cannot be related to the terrestrial composition by any known process, including radiogenic, nucleogenic, and cosmogenic effects. Those variations have a nucleosynthetic origin, reflecting the fact that the products of stellar nucleosynthesis were not fully homogenized when the Solar System formed. Those anomalies are found at all scales, from nanometer-sized presolar grains to bulk terrestrial planets. They can be used to learn about stellar

  8. MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS

    SciTech Connect

    Aleon, Jerome

    2010-10-20

    Isotopic fractionation and mixing calculations compared with coupled hydrogen and nitrogen isotopic composition of organic molecules from primitive chondrites, interplanetary dust particles (IDPs), and comets C/1995 O1 (Hale-Bopp) and 81P/Wild2 reveal that meteoritic and cometary organic matter contains three different isotopic components of different origins. (1) A major component of carbonaceous chondrites, IDPs, and comets Hale-Bopp and Wild2 shows correlated H and N isotopic compositions attributable to isotope exchange between an organic matter of solar composition and a reservoir formed by ion-molecule reactions at T < 25 K under conditions where competing reactions are strongly inhibited, possibly in the final evolutionary stages of the presolar cloud core, or more likely in the coldest outer regions of the solar protoplanetary disk. (2) In carbonaceous chondrites, IDPs, and comet Wild2, this component is mixed with a {sup 15}N-rich component having identical {sup 15}N and D enrichments relative to the protosolar gas. Temperatures > 100 K deduced from the low D/H ratio and an anti-correlation between the abundance of this component and meteoritic age indicate a late origin in the solar protoplanetary disk. N{sub 2} self-shielding and the non-thermal nucleosynthesis of {sup 15}N upon irradiation are possible but unlikely sources of this component, and a chemical origin is preferred. (3) An interstellar component with highly fractionated hydrogen isotopes and unfractionated nitrogen isotopes is present in ordinary chondrites. A dominantly solar origin of D and {sup 15}N excesses in primitive solar system bodies shows that isotopic anomalies do not necessarily fingerprint an interstellar origin and implies that only a very small fraction of volatile interstellar matter survived the events of solar system formation.

  9. Influence of the Central American Seaway and Drake Passage on ocean circulation and neodymium isotopes: A model study

    NASA Astrophysics Data System (ADS)

    Pfister, Patrik L.; Stocker, Thomas F.; Rempfer, Johannes; Ritz, Stefan P.

    2014-12-01

    The sensitivity of the neodymium isotopic composition (ɛNd) to tectonic rearrangements of seaways is investigated using an Earth System Model of Intermediate Complexity. The shoaling and closure of the Central American Seaway (CAS) is simulated, as well as the opening and deepening of Drake Passage (DP). Multiple series of equilibrium simulations with various intermediate depths are performed for both seaways, providing insight into ɛNd and circulation responses to progressive throughflow evolutions. Furthermore, the sensitivity of these responses to the Atlantic Meridional Overturning Circulation (AMOC) and the neodymium boundary source is examined. Modeled ɛNd changes are compared to sediment core and ferromanganese (Fe-Mn) crust data. The model results indicate that the North Atlantic ɛNd response to the CAS shoaling is highly dependent on the AMOC state, i.e., on the AMOC strength before the shoaling to shallow depths (preclosure). Three scenarios based on different AMOC forcings are discussed, of which the model-data agreement favors a shallow preclosure (Miocene) AMOC (˜6 Sv). The DP opening causes a rather complex circulation response, resulting in an initial South Atlantic ɛNd decrease preceding a larger increase. This feature may be specific to our model setup, which induces a vigorous CAS throughflow that is strongly anticorrelated to the DP throughflow. In freshwater experiments following the DP deepening, ODP Site 1090 is mainly influenced by AMOC and DP throughflow changes, while ODP Site 689 is more strongly influenced by Southern Ocean Meridional Overturning Circulation and CAS throughflow changes. The boundary source uncertainty is largest for shallow seaways and at shallow sites.

  10. Isotopically distinct reservoirs in the solar nebula: Isotope anomalies in Vigarano meteorite inclusions

    NASA Technical Reports Server (NTRS)

    Loss, R. D.; Lugmair, G. W.; Davis, A. M.; Macpherson, G. J.

    1994-01-01

    The isotopic compositions of Mg, Ca, Ti, Cr, Zn, Sr, Ba, Nd, and Sm were measured in four relatively unaltered refractory inclusions from the Vigarano carbonaceous chondrite meteorite. Three of the inclusions (USNM 1623-2, 1623-3, and 1623-8) show similar Mg, Ca, Ti, and Cr isotopic compositions to those found in most inclusions in the Allende carbonaceous chondrite. This indicates that these Vigarano inclusions sampled the same isotopic reservoirs as the majority of the Allende inclusions that isotope signatures in the latter were not significantly modified by the secondary alteration that permeates most Allende inclusions. In contrast, inclusion 1623-5 has large deficits in Mg-26, Ca-48, and Ti-50 and small but distinct Cr-54, Zn-66, Sr-84, Ba-135, Ba-137, and Sm-144 anomalies. The magnitudes of these unusual anomalies in the refractory elements are within analytical uncertainty of those found in the Allende 'FUN" inclusion C1, yet 1623-5 has a very different bulk chemical composition from C1. The fact that 1623-5 and C1 have identical isotopic anomalies yet have significantly distinct major and trace element contents provide convincing evidence for the presence of isotopically distinct reservoirs in the early solar system.

  11. Neodymium Magnets.

    ERIC Educational Resources Information Center

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  12. Variability of neodymium isotopes associated with planktonic foraminifera in the Pacific Ocean during the Holocene and Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Hu, Rong; Piotrowski, Alexander M.; Bostock, Helen C.; Crowhurst, Simon; Rennie, Victoria

    2016-08-01

    The deep Pacific Ocean holds the largest oceanic reservoir of carbon which may interchange with the atmosphere on climatologically important timescales. The circulation of the deep Pacific during the Last Glacial Maximum (LGM), however, is not well understood. Neodymium (Nd) isotopes of ferromanganese oxide coatings precipitated on planktonic foraminifera are a valuable proxy for deep ocean water mass reconstruction in paleoceanography. In this study, we present Nd isotope compositions (εNd) of planktonic foraminifera for the Holocene and the LGM obtained from 55 new sites widely distributed in the Pacific Ocean. The Holocene planktonic foraminiferal εNd results agree with the proximal seawater data, indicating that they provide a reliable record of modern bottom water Nd isotopes in the deep Pacific. There is a good correlation between foraminiferal εNd and seawater phosphate concentrations (R2 = 0.80), but poorer correlation with silicate (R2 = 0.37). Our interpretation is that the radiogenic Nd isotope is added to the deep open Pacific through particle release from the upper ocean during deep water mass advection and aging. The data thus also imply the Nd isotopes in the Pacific are not likely to be controlled by silicate cycling. In the North Pacific, the glacial Nd isotopic compositions are similar to the Holocene values, indicating that the Nd isotope composition of North Pacific Deep Water (NPDW) remained constant (-3.5 to -4). During the LGM, the southwest Pacific cores throughout the water column show higher εNd corroborating previous studies which suggested a reduced inflow of North Atlantic Deep Water to the Pacific. However, the western equatorial Pacific deep water does not record a corresponding radiogenic excursion, implying reduced radiogenic boundary inputs during the LGM probably due to a shorter duration of seawater-particle interaction in a stronger glacial deep boundary current. A significant negative glacial εNd excursion is evident in

  13. Titanium isotopic anomalies in hibonites from the Murchison carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Ireland, T. R.; Compston, W.; Heydegger, H. R.

    1985-09-01

    The isotopic compositions of titanium in eight grains of hibonite (CaAl12O19) from the carbonaceous chondrite Murchison have been determined by high precision secondary ion mass spectrometry using an ion microprobe. The titanium in the hibonites varies greatly in Ti-50 from about -42 to +8 permil (relative to terrestrial) with smaller (up to 4 permil), but clearly resolvable, effects in Ti-46 and Ti-48. These results confirm the presence of widespread negative anomalies suggested by the results of Hutcheon et al. (1983) on hibonites from Murchison. The magnitude of these variations seems explicable only in terms of nucleogenic processes which produced extremely variable titanium isotopic abundances in the hibonite source materials. The hibonites evidently did not participate to the same extent as most material in the mixing and homogenisation processes that accompanied the formation and later evolution of the solar system.

  14. Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe-oxide (Fe-P-REE) systems

    NASA Astrophysics Data System (ADS)

    Gleason, James D.; Marikos, Mark A.; Barton, Mark D.; Johnson, David A.

    2000-03-01

    Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium isotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, ɛ Nd for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of the same age (ɛ Nd = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, ɛ Nd for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks (-1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks (ɛ Nd = -2.0 to -4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar ɛ Nd (-1.7 to -2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with ɛ Nd = -2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.

  15. Neodymium, strontium, and lead isotopes in the Maloin Ranch Pluton, Wyoming: Implications for the origin of evolved rocks at anorthosite margins

    SciTech Connect

    Kolker, A.; Hanson, G.N. ); Frost, C.D. ); Geist, D.J. )

    1991-08-01

    Neodymium, strontium, and lead isotopic data are used in this study to investigate the origin of chemically evolved rocks in the Maloin Ranch Pluton, a composite body that borders and intrudes the Laramie Anorthosite. In the Maloin Ranch Pluton, these include ferrodiorite at the base of the intrusion, overalain progressively by fine-grained monzonite, monzosyenite, and porphyritic granite. Biotite gabbro and fine-grained granitic dikes are present locally at various levels of this sequence. The origin of the evolved rocks and their possible relation to associated anorthositic bodies has been much debated. In the Maloin Ranch Pluton, each rock type has distinct isotopic characteristics which, together with trace-element data previously reported, suggest different source characteristics for each member. Strontium and neodymium isotopic data for Maloin Ranch ferrodiorite and Laramie anorthositic rocks show considerable overlap, consistent with a comagmatic relation. Biotite gabbro is chemically and isotopically the most primitive rock type in the Maloin Ranch Pluton. The data suggest that biotite gabbro has a mantle source, but has undergone extensive fractionation in the crust. The authors' results suggest that the remainder (and bulk) of the intrusion formed by partial melting of the lower crust due to the emplacement of the Laramie Anorthosite. Trace-element and isotopic characteristics of the fine-grained monzonite are explained by partial melting of mantle-dervied lower crust, added to the margin of the Archean Wyoming craton at about 1.8 Ga. Neodymium, strontium, and lead isotope data for Maloin Ranch monzosyenite and porphyritic granite also suggest a lower crustal source.

  16. Neodymium isotopes in flood basalts from the Siberian Platform and inferences about their mantle sources

    PubMed Central

    DePaolo, D. J.; Wasserburg, G. J.

    1979-01-01

    The initial isotopic compositions of Nd and Sr in basalts from the Central Siberian Plateau and other major continental flood basalts are reported. The continental flood basalts appear to be the product of partial melting of mantle sources that consist of relatively primitive undifferentiated material and are clearly distinct from midocean ridge basalts, which sample mantle reservoirs that have been modified by extraction of continental crust earlier in earth history. These observations provide fundamental constraints on models of mantle structure and dynamics. Isotopic effects of crustal contamination are clearly recognizable in some continental flood basalts, but these effects can be distinguished from isotopic patterns inherited from the mantle magma sources. PMID:16592671

  17. Vertical Stratification Changes During the Last Deglaciation Based on Foraminiferal Neodymium and Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Piotrowski, A. M.; Noble, T. L.; Roberts, N. L.; Yu, J.

    2011-12-01

    Reorganizations of the vertical structure of the ocean are believed to have occurred during major climate transitions. Some studies utilizing nutrient tracers have suggested that North Atlantic intermediate and deep ocean circulation changed together during the last deglaciation, in a manner consistent with reorganizations of the global thermohaline circulation (Rickaby and Elderfield, 2005). A strong vertical gradient in carbon isotopes, or chemocline, existed at ~2.5 km-bsl the glacial South Atlantic sector of the Southern Ocean, which may have been due to different intermediate and deep water sourcing (Hodell et al., 2003). We present new Nd isotope records from globally-distributed intermediate sites in the North Atlantic, South Atlantic, and Pacific Ocean, comparing them to Nd isotope records from proximal deep sites to examine whether there is a global coherency to changes in intermediate and deep water mass sourcing. Comparison of Nd isotopes from vertical transects in the ocean also allows us to address an important geochemical debate about REE cycling in the ocean; whether long-distance horizontal advection or local boundary exchange from sediments plays a more important role in labelling the Nd isotopic composition of seawater. Down-slope vertical transport of sediments from the continental shelf to the deep ocean should mean that under conditions where boundary exchange is dominant, intermediate and deep waters will be labelled with similar Nd isotopic compositions and it will also cause them to covary together through time. We show that the Nd isotopic composition of intermediate depth cores in the South Atlantic and Pacific sectors of the Southern Ocean record small changes of ~1 epsilon unit or less during the deglaciation. As is the case with C isotopes, a stronger vertical Nd isotope gradient existed in the South Atlantic during the last glacial. Nd and C isotopes changed together at intermediate-depth ODP Site 1088 in the South Atlantic in a manner

  18. Neodymium isotopic composition and concentration in the western North Atlantic Ocean: Results from the GEOTRACES GA02 section

    NASA Astrophysics Data System (ADS)

    Lambelet, Myriam; van de Flierdt, Tina; Crocket, Kirsty; Rehkämper, Mark; Kreissig, Katharina; Coles, Barry; Rijkenberg, Micha J. A.; Gerringa, Loes J. A.; de Baar, Hein J. W.; Steinfeldt, Reiner

    2016-03-01

    The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data for Nd isotopes and concentrations from twelve seawater depth profiles, which follow the flow path of North Atlantic Deep Water (NADW) from its formation region in the North Atlantic to the northern equatorial Atlantic. Samples were collected during two cruises constituting the northern part of the Dutch GEOTRACES transect GA02 in 2010. The results show that the different water masses in the subpolar North Atlantic Ocean, which ultimately constitute NADW, have the following Nd isotope characteristics: Upper Labrador Sea Water (ULSW), εNd = -14.2 ± 0.3; Labrador Sea Water (LSW), εNd = -13.7 ± 0.9; Northeast Atlantic Deep Water (NEADW), εNd = -12.5 ± 0.6; Northwest Atlantic Bottom Water (NWABW), εNd = -11.8 ± 1.4. In the subtropics, where these source water masses have mixed to form NADW, which is exported to the global ocean, upper-NADW is characterised by εNd values of -13.2 ± 1.0 (2sd) and lower-NADW exhibits values of εNd = -12.4 ± 0.4 (2sd). While both signatures overlap within error, the signature for lower-NADW is significantly more radiogenic than the traditionally used value for NADW (εNd = -13.5) due to the dominance of source waters from the Nordic Seas (NWABW and NEADW). Comparison between the concentration profiles and the corresponding Nd isotope profiles with other water mass properties such as salinity, silicate concentrations, neutral densities and chlorofluorocarbon (CFC) concentration provides novel insights into the geochemical cycle of Nd and reveals that different processes are necessary to account for the observed Nd characteristics in the subpolar and subtropical gyres and throughout the vertical water column. While our data set

  19. Strontium and neodymium isotopes in hot springs on the East Pacific Rise and Guaymas Basin

    NASA Technical Reports Server (NTRS)

    Piepgras, D. J.; Wasserburg, G. J.

    1985-01-01

    Solutions collected from 21 deg N, East Pacific Rise (Epr) and Guaymas Basin, Gulf of California, are analyzed for Nd isotopic composition and Sm and Nd concentrations. The results indicate extensive but not complete isotopic exchange with Sr in the depleted oceanic crust and that Sr concentrations in these solutions are buffered. In contrast, the Nd data exhibit a wide range in isotopic composition and concentration between vents. Many samples show substantial contributions from MORB, but all have isotopic compositions below MORB, in spite of enrichments in Nd up to 100 times seawater. It is shown that the fluids must exchange Nd with a sedimentary reservoir having an isotopic composition less than Pacific seawater. Low-temperature reactions with metalliferous sediments on the flanks of the EPR may provide such a source. Using a simple box method, estimates of the hydrothermal fluxes of Nd are compared to fluxes which are necessary to maintain a radiogenic isotopic composition of about -3 in the Pacific against the influx of Antarctic waters. It is concluded that erosion from island arcs is the main source of radiogenic Nd in the Pacific.

  20. Neodymium isotopic study of rare earth element sources and mobility in hydrothermal Fe oxide (Fe-P-REE) systems

    SciTech Connect

    Gleason, J.D.; Marikos, M.A.; Barton, M.D.; Johnson, D.A.

    2000-03-01

    Rare earth element (REE)-enriched, igneous-related hydrothermal Fe-oxide hosted (Fe-P-REE) systems from four areas in North America have been analyzed for their neodymium iosotopic composition to constrain REE sources and mobility in these systems. The Nd isotopic results evidence a common pattern of REE concentration from igneous sources despite large differences in age (Proterozoic to Tertiary), tectonic setting (subduction vs. intraplate), and magmatic style (mafic vs. felsic). In the Middle Proterozoic St. Francois Mountains terrane of southeastern Missouri, {epsilon}{sub Nd} for Fe-P-REE (apatite, monazite, xenotime) deposits ranges from +3.5 to +5.1, similar to associated felsic to intermediate igneous rocks of the same age ({epsilon}{sub Nd} = +2.6 to +6.2). At the mid-Jurassic Humboldt mafic complex in western Nevada, {epsilon}{sub Nd} for Fe-P-REE (apatite) mineralization varies between +1.1 and +2.4, similar to associated mafic igneous rocks ({minus}1.0 to +3.5). In the nearby Cortez Mountains in central Nevada, mid-Jurassic felsic volcanic and plutonic rocks ({epsilon}{sub Nd} = {minus}2.0 to {minus}4.4) are associated with Fe-P-REE (apatite-monazite) mineralization having similar {epsilon}{sub Nd}({minus}1.7 to {minus}2.4). At Cerro de Mercado, Durango, Mexico, all assemblages analyzed in this Tertiary rhyolite-hosted Fe oxide deposit have identical isotopic compositions with {epsilon}{sub Nd} = {minus}2.5. These data are consistent with coeval igneous host rocks being the primary source of REE in all four regions, and are inconsistent with a significant contribution of REE from other sources. Interpretations of the origin of these hydrothermal systems and their concomitant REE mobility must account for nonspecialized igneous sources and varied tectonic settings.

  1. The distribution of neodymium isotopes and concentrations in the Eastern Equatorial Pacific: Water mass advection versus particle exchange

    NASA Astrophysics Data System (ADS)

    Grasse, Patricia; Stichel, Torben; Stumpf, Roland; Stramma, Lothar; Frank, Martin

    2012-11-01

    The radiogenic isotope composition of the Rare Earth Element (REE) neodymium (Nd) is a powerful water mass proxy for present and past ocean circulation. The processes controlling the Nd budget of the global ocean are not quantitatively understood and in particular source and sink mechanisms are still under debate. In this study we present the first full water column data set of dissolved Nd isotope compositions and Nd concentrations for the Eastern Equatorial Pacific (EEP), where one of the globally largest Oxygen Minimum Zones (OMZ) is located. This region is of particular interest for understanding the biogeochemical cycling of REEs because anoxic conditions may lead to release of REEs from the shelf, whereas high particle densities and fluxes potentially remove the REEs from the water column. Data were obtained between 1°40‧N and 16°S along a nearshore and an offshore transect. Near surface zonal current bands, such as the Equatorial Undercurrent (EUC) and the Subsurface Countercurrent (SSCC), which are supplying oxygen-rich water to the OMZ are characterized by radiogenic Nd isotope signatures (εNd=-2). Surface waters in the northernmost part of the study area are even more radiogenic (εNd=+3), most likely due to release of Nd from volcanogenic material. Deep and bottom waters at the southernmost offshore station (14°S) are clearly controlled by advection of water masses with less radiogenic signatures (εNd=-7) originating from the Southern Ocean. Towards the equator, however, the deep waters show a clear trend towards more radiogenic values of up to εNd=-2. The northernmost station located in the Panama basin shows highly radiogenic Nd isotope signatures in the entire water column, which indicates that particle scavenging, downward transport and release processes play an important role. This is supported by relatively low Nd concentrations in deep waters (3000-6000 m) in the EEP (20 pmol/kg) compared to locations in the Northern and Central Pacific

  2. Precise Measurement of Stable Neodymium Isotopes of Geological Materials by Using MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Ma, J.; Wei, G.; Liu, Y.; Ren, Z.; Xu, Y.

    2013-12-01

    A method has developed to determine high-precision high precision stable Nd isotopes in geological materials by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) using sample-standard-bracketing (SSB) mode. Nd was pre-concentrated and purifed and through a two column ion-exchange chromatographic procedure, yeilding a recovery of >96% for Nd with the interferences such as Ce and Sm being removed to cause little influence on the stable Nd isotopic compositions. The internal precision for the stable Nd isotopic compositions, ɛ142Nd, ɛ145Nd, ɛ146Nd and ɛ148Nd were generally better than ×0.2 (2SEM: standard error of the mean), and the external precision were generally better than ×0.2 (1SD: standard deviation) for ɛ142Nd, ɛ145Nd and ɛ146Nd, and better than ×0.5 (1SD) for ɛ148Nd estimated by the long-term results of the Nd standard solutions, such as La Jolla, Nd-GIG and NIST 3135a. Such precision id comparable to those by double spike method. Our measured ɛ142Nd, ɛ145Nd, ɛ146Nd and ɛ148Nd results of La Jolla are indentical to those by double spike method winthin analytical error. Thus, our method can provide comparable results for stable Nd isotopes to those by double spike method, but free from the inconvenience of calibrationg double spikes. This provides a more convenient means for studying stabe Nd isotopes in geological processes. By using this method, the stable Nd isotopic compositions for a series of international rock standard references were measured.

  3. Rhenium-osmium and samarium-neodymium isotopic systematics of the Stillwater complex

    NASA Technical Reports Server (NTRS)

    Lambert, David D.; Shirey, Steven B.; Carlson, Richard W.; Morgan, John W.; Walker, Richard J.

    1989-01-01

    The role of magma mixing in the formation of strategic platinum-group element ore deposits is examined using isotopic data from the Stillwater Complex, Montana. Nd and Os isotopic data show that the intrusion formed from at least two distinct magmas: ultramafic (U-type) affinity magmas and anorthositic (A-type) affinity magmas. The U-type magmas formed from a lithospheric mantle source containing recycled crustal materials and the A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The results also suggest that the platinum-group element ore deposits were derived from A-type magmas which were injected into the U-type magma chamber at several stages during the development of the ultramafic series.

  4. Deformation studies in the extremely neutron-deficient praseodymium, neodymium and promethium isotopes

    SciTech Connect

    Breitenbach, J.; Braga, R.A.; Wood, J.L. ); Semmes, P.B. . Dept. of Physics); Kormicki, J. . Dept. of Physics)

    1992-01-01

    Several experiments were performed at the UNISOR isotope separator facility at HHIRF at the Oak Ridge National Laboratory on the [beta][sup +]/EC decay of neutron-deficient rare earth isotopes. Data for the three decay chains [sup 137]Eu [yields] [sup 137]Sm [yields] [sup 137]Pm [yields] [sup 137]Nd, [sup 135]Sm [yields] [sup 135]Pm [yields] [sup 135]Nd and [sup 133]Sm [yields] [sup 133]Pm [yields] [sup 133]Nd were obtained consisting of multiscaled spectra of [gamma] rays, x rays, and conversion electrons, as well as [gamma][gamma]t, X[gamma]t, e[gamma]t and eXt coincidences. Gamma rays associated with the decay of [sup 133]Sm and [sup 133]Pm were observed for the first time. The decay of a new low-spin (1/2,3/2) isomeric state, with a half life around 70 sec was seen in [sup 133]Nd. Systematics and particle-rotor calculations are discussed.

  5. Deformation studies in the extremely neutron-deficient praseodymium, neodymium and promethium isotopes

    SciTech Connect

    Breitenbach, J.; Braga, R.A.; Wood, J.L.; Semmes, P.B.; Kormicki, J.

    1992-12-31

    Several experiments were performed at the UNISOR isotope separator facility at HHIRF at the Oak Ridge National Laboratory on the {beta}{sup +}/EC decay of neutron-deficient rare earth isotopes. Data for the three decay chains {sup 137}Eu {yields} {sup 137}Sm {yields} {sup 137}Pm {yields} {sup 137}Nd, {sup 135}Sm {yields} {sup 135}Pm {yields} {sup 135}Nd and {sup 133}Sm {yields} {sup 133}Pm {yields} {sup 133}Nd were obtained consisting of multiscaled spectra of {gamma} rays, x rays, and conversion electrons, as well as {gamma}{gamma}t, X{gamma}t, e{gamma}t and eXt coincidences. Gamma rays associated with the decay of {sup 133}Sm and {sup 133}Pm were observed for the first time. The decay of a new low-spin (1/2,3/2) isomeric state, with a half life around 70 sec was seen in {sup 133}Nd. Systematics and particle-rotor calculations are discussed.

  6. Implications for post-comminution processes in subglacial suspended sediment using coupled radiogenic strontium and neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Clinger, Anna E.; Aciego, Sarah M.; Stevenson, Emily I.; Arendt, Carli A.; Robbins, Mark J.

    2016-04-01

    Enhanced physical weathering rates in subglacial systems promote high levels of comminution, transport, and deposition of fine-grained sediment within the subglacial drainage network. The impact of shifts in sediment loads from variations in meltwater flux, and their effects on downstream ecosystems, remains poorly quantified and places a fundamental importance on our ability to characterize subglacial depositional environments. Here, for the first time, we assess the seasonal evolution of the subglacial suspended sediment using coupled radiogenic strontium (87Sr/86Sr) and neodymium (143Nd/144Nd) isotopic ratios with elemental ratios and in situ measurements. Weathering rates in fluvial and riverine systems have been traditionally assessed using radiogenic isotopic tracers: 143Nd/144Nd ratios relate to the crustal age whereas 87Sr/86Sr ratios relate to age and preferential mineral dissolution. Thus relative shifts in these ratios will allow us to characterize distinct sediment transport networks. We apply this technique to the Lemon Creek Glacier (LCG), Alaska, USA, and to the Athabasca Glacier (AG), Alberta, CA. At the LCG, the 143Nd/144Nd values range from εNd of - 4.6 (0.9) to - 8.7 (0.2), which suggests a poorly mixed sediment flux. However, the greatest period of variability may correlate with the drainage of a supraglacial lake and suggests caution should be exerted in time-scale 143Nd/144Nd provenance studies that may be affected by climatic disturbances. In contrast, limited variation is observed within the AG 143Nd/144Nd seasonal record. A consistent, direct relation between the Rb/Sr elemental ratio and the 87Sr/86Sr ratio proves interesting as it enables us to unravel incongruent weathering trends in the radiogenic Sr record. Correlation between the 87Sr/86Sr and total discharge suggests that the process is partially controlled by mantling of the bedrock, which can be detected using post-comminution ages. While the subglacial structure may be enabled by

  7. The isotopic homogeneity in the early solar system: Revisiting the CAI oxygen isotopic anomaly

    NASA Astrophysics Data System (ADS)

    Ozima, M.; Yamada, A.

    2009-12-01

    Since the first discovery of the mass-independently fractionated oxygen isotopes in anhydrous, high temperature Ca-Al rich inclusion minerals in carbonaceous meteorites (CAIs) by Clayton et al. (1), their common occurrence in primitive meteorites has generally been regarded to reflect some fundamental process prevalent in the early solar nebula. The CAI oxygen isotopic composition is uniquely characterized by (i) large mass independent isotopic fractionation and (ii) their isotopic data in an oxygen three isotope plot (δ17O - δ18O (δ17O ≡ {(17O/16O)/(17O/16O)SMOW - 1} × 1000) yield nearly a straight line with a slope 1.0. In establishing these characteristics, ion microprobe analyses has played a central role, especially an isotopic mapping technique (isotopography) was crucial (e.g., 2). The extraordinary oxygen isotopic ratio in CAIs is widely attributed to the self-shielding absorption of UV radiation in CO, one of the dominant chemical compounds in the early solar nebula (3). However, the self-shielding scenario necessarily leads to the unusual prediction that a mean solar oxygen isotopic composition differs from most of planetary bodies including Earth, Moon, and Mars. If the self-shielding process were indeed responsible to the CAI oxygen isotopic anomaly, this would require a fundamental revision of the current theory of the origin of the solar system, which generally assumes the initial total vaporization of nebula material to give rise to isotopic homogenization. The GENESIS mission launched in 2001(4), which collected oxygen in the solar wind was hoped to resolve the isotopic composition of the Sun. However, because of difficulties in correcting for instrumental and more importantly for intrinsic isotopic fractionation between the SW and the Sun, a final answer is yet to be seen (5). Here, we show on the basis of the oxygen isotopic fractionation systematics that the self shielding hypothesis cannot explain the key characteristics of the CAI oxygen

  8. Combination of Silicon and Neodymium Isotopes for a better understanding of past changes in bioproductivity and water mass mixing in the upwelling area off Peru

    NASA Astrophysics Data System (ADS)

    Grasse, P.; Ehlert, C.; Frank, M.; Stramma, L.

    2010-12-01

    The Peru coastal upwelling area is characterized by one of the most pronounced Oxygen Minimum Zones (OMZ). Oxygen concentrations are controlled by consumption through decomposition of organic matter versus ventilation via ocean circulation. Surface productivity is a function of both nutrient supply and upwelling intensity. The isotopic composition of Neodymium (Nd) is a powerful proxy for the reconstruction of past ocean circulation due to its intermediate oceanic residence time and the fact that it is independent of biological fractionation. This is in contrast to Silicon (Si) isotopes, which are fractionated during utilization in a way that the lighter Si isotopes are preferentially incorporated into the diatom frustules. The upwelling area off Peru is mainly influenced by water masses from the Central Pacific, which show more radiogenic values (ɛNd = -2), than water masses from the Northern Pacific (ɛNd = -5 to -3) or water masses from the south, which carry an unradiogenic Nd isotope signature originating from the Southern Ocean (ɛNd = -8 to -9). Upwelled Waters on the shelf are mainly supplied from the Equatorial Under Current (EUC) a strong southward flowing water mass originating in the western pacific. Therefore the δ30Si signal of diatoms is mainly influenced by the isotopic signal of the EUC. Past changes in the hydrography therefore would also influence the Si isotopic signal of this productivity proxy independent of silicic acid utilization. For a better understanding of the influence of water mass mixing on the isotopic signatures in the coastal upwelling area and the OMZ, we directly compare the Nd isotope signatures with dissolved stable Silicon isotope data. The information obtained from the unique combination of the biologically influenced Si isotopes and the Nd isotopes will lead to a better understanding of reconstruction of past ocean circulation and productivity.

  9. Deformation in the neutron-deficient rare earth isotopes: Radioactive decay scheme studies in the neodymium, promethium, and samarium isotopes

    SciTech Connect

    Breitenbach, J.B.

    1993-12-31

    Several experiments were performed at the UNISOR isotope separator facility at HHIRF at the Oak Ridge National Laboratory on the {beta}{sup +}/EC decay of neutron-deficient rare earth isotopes. Data for the decay chain {sup 133}Sm {yields} {sup 133}Pm {yields} {sup 133}Nd was obtained, consisting of multiscaled spectra of {gamma} rays, X rays, and conversion electrons, as well as {gamma}{gamma}t, X{gamma}t, e{gamma}t and eXt coincidences. Gamma rays associated with the decay of {sup 133}Sm and {sup 133}Pm were observed for the first time. The decay of a new low-spin (1/2) isomeric state, with a half life of about 70 sec was established for {sup 133}Nd. The level schemes for {sup 133}Nd and {sup 133}Pr were constructed. An M3 and two E1 isomers are established in {sup 133}Nd and an E3 isomer is confirmed in {sup 133}Pr. The energy level systematics for the nuclear region bounded by Z {ge} 58 and N {le} 78 is discussed. Theoretical interpretations are based on the particle-plus-triaxial rotor model calculations. In the framework of these calculations, the {beta}{sub 2} deformation is moderate for these nuclei ({beta}{sub 2} {approx} 0.20-0.25). A sudden onset of strong deformation is not observed, in contrast with the theoretical predictions by Leander and Moeller [Lea82].

  10. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere

    PubMed Central

    Shaheen, Robina; Abaunza, Mariana M.; Jackson, Teresa L.; McCabe, Justin; Savarino, Joël; Thiemens, Mark H.

    2014-01-01

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984–2001) showed the highest S-isotopic anomalies (Δ33S = +1.66‰ and Δ36S = +2‰) in a nonvolcanic (1998–1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997–1998)-induced changes in troposphere–stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ36S = −0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere. PMID:25092338

  11. Large sulfur-isotope anomaly in nonvolcanic sulfate aerosol and its implications for the Archean atmosphere.

    PubMed

    Shaheen, Robina; Abaunza, Mariana M; Jackson, Teresa L; McCabe, Justin; Savarino, Joël; Thiemens, Mark H

    2014-08-19

    Sulfur-isotopic anomalies have been used to trace the evolution of oxygen in the Precambrian atmosphere and to document past volcanic eruptions. High-precision sulfur quadruple isotope measurements of sulfate aerosols extracted from a snow pit at the South Pole (1984-2001) showed the highest S-isotopic anomalies (Δ(33)S = +1.66‰ and Δ(36)S = +2‰) in a nonvolcanic (1998-1999) period, similar in magnitude to Pinatubo and Agung, the largest volcanic eruptions of the 20th century. The highest isotopic anomaly may be produced from a combination of different stratospheric sources (sulfur dioxide and carbonyl sulfide) via SOx photochemistry, including photoexcitation and photodissociation. The source of anomaly is linked to super El Niño Southern Oscillation (ENSO) (1997-1998)-induced changes in troposphere-stratosphere chemistry and dynamics. The data possess recurring negative S-isotope anomalies (Δ(36)S = -0.6 ± 0.2‰) in nonvolcanic and non-ENSO years, thus requiring a second source that may be tropospheric. The generation of nonvolcanic S-isotopic anomalies in an oxidizing atmosphere has implications for interpreting Archean sulfur deposits used to determine the redox state of the paleoatmosphere. PMID:25092338

  12. A major and trace element and strontium, neodymium, and osmium isotopic study of a thick pyroxenite layer from the Beni Bousera Ultramafic Complex of northern Morocco

    NASA Astrophysics Data System (ADS)

    Kumar, Niraj; Reisberg, Laurie; Zindler, Alan

    1996-04-01

    Major and trace element concentrations and strontium, neodymium, and osmium isotopic compositions were determined for a series of samples from a thick, symmetrically zoned pyroxenite layer from the Beni Bousera massif. The two main rock types included in the layer, garnet pyroxenites and websterites, have distinct, well-defined elemental and isotopic compositions. The websterites are, in most respects, more refractory than the garnet pyroxenites, but, surprisingly, are more enriched in the highly incompatible elements. The observed characteristics can be explained by formation of the layer by crystal deposition along a magma conduit at medium to high pressures, given that the source and composition of the magma varies with time. Re-Os model ages for three samples of different lithology converge to about 1.3 b.y., which is interpreted as the age of formation of the layer. In contrast, Sm-Nd model ages from the layer are mutually conflicting or indeterminate, largely due to the similarity between the measured neodymium isotopic ratios and that of the depleted mantle. On the other hand, the Sm-Nd model age obtained from an extremely depleted peridotite ( 143Nd/ 144Nd = 0.51391) located about 30 m from the layer falls within error of the Re-Os ages, providing support for an extensive magmatic event at about that time. This same age was obtained by several techniques from the closely related Ronda Ultramafic Complex of southern Spain. This may suggest that the mantle lithosphere currently exposed along the southern margin of Spain and the northern margin of Morocco has been linked for over a billion years.

  13. Hafnium and neodymium isotopes in surface waters of the eastern Atlantic Ocean: Implications for sources and inputs of trace metals to the ocean

    NASA Astrophysics Data System (ADS)

    Rickli, J.; Frank, M.; Baker, A. R.; Aciego, S.; de Souza, G.; Georg, R. B.; Halliday, A. N.

    2010-01-01

    We present hafnium (Hf) and neodymium (Nd) isotopic compositions and concentrations in surface waters of the eastern Atlantic Ocean between the coast of Spain and South-Africa. These data are complemented by Hf and Nd isotopic and concentration data, as well as rare earth element (REE) concentrations, in Saharan dust. Hafnium concentrations range between a maximum of 0.52 pmol/kg in the area of the Canary Islands and a minimum value of 0.08 pmol/kg in the southern Angola Basin. Neodymium concentrations also show a local maximum in the area of the Canary Islands (26 pmol/kg) but are even higher between ˜20°N and ˜4°N reaching maximum concentrations of 35 pmol/kg. These elevated concentrations provide evidence of inputs from weathering of the Canary Islands and from the partial dissolution of dust from the Sahara/Sahel region. The inputs from ocean island weathering are also reflected in radiogenic Hf and Nd isotopes. The Hf isotopic compositions of dust samples themselves are highly variable, ranging between ɛHf = -20 and -0.6. The combined Hf and Nd isotopic compositions of dust plot close to the "terrestrial array" during periods of appreciable dust load in the atmosphere. During low atmospheric dust loading combined Hf and Nd isotopic compositions similar to seawater are observed. Most of the variability can be explained in terms of variable degrees of zircon loss from the dust samples, which in turn is linked to sorting during atmospheric transport to the eastern Atlantic Ocean and possibly presorting by sedimentary redistribution on the continent. In addition, increasing relative proportions of radiogenic clay minerals with decreasing grain size may contribute to the radiogenic Hf isotopic compositions observed. While the Nd isotopic composition in the surface ocean reflects the Nd isotopic composition of the Saharan dust adjacent to the Sahara/Sahel region, the release of Hf from that dust appears to be incongruent and results in surface ocean Hf isotopic

  14. Neodymium isotope constraints on provenance, dispersal, and climate-driven supply of Zambezi sediments along the Mozambique Margin during the past ˜45,000 years

    NASA Astrophysics Data System (ADS)

    van der Lubbe, H. J. L.; Frank, Martin; Tjallingii, Rik; Schneider, Ralph R.

    2016-01-01

    Marine sediments deposited off the Zambezi River that drains a considerable part of the southeast African continent provide continuous records of the continental climatic and environmental conditions. Here we present time series of neodymium (Nd) isotope signatures of the detrital sediment fraction during the past ˜45,000 years, to reconstruct climate-driven changes in the provenance of clays deposited along the Mozambique Margin. Coherent with the surface current regime, the Nd isotope distribution in surface sediments reveals mixing of the alongshore flowing Zambezi suspension load with sediments supplied by smaller rivers located further north. To reconstruct past changes in sediment provenances, Nd isotope signatures of clays that are not significantly fractionated during weathering processes have been obtained from core 64PE304-80, which was recovered just north of the Zambezi mouth at 1329 m water depth. Distinctly unradiogenic clay signatures (ɛNd values <-14.2) are found during the Last Glacial Maximum, Heinrich Stadial 1, and Younger Dryas. In contrast, the Nd isotope record shows higher, more radiogenic isotope signatures during Marine Isotope Stage 3 and between ˜15 and ˜5 ka BP, the latter coinciding with the timing of the northern hemisphere African Humid Period. The clay-sized sediment fraction with the least radiogenic Nd isotope signatures was deposited during the Holocene, when the adjacent Mozambique Shelf became completely flooded. In general, the contribution of the distinctly unradiogenic Zambezi suspension load has followed the intensity of precession-forced monsoonal precipitation and enhanced during periods of increased southern hemisphere insolation and high-latitude northern hemispheric climate variability.

  15. 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.

  16. Endemic Ru Isotopic Anomalies in Iron Meteorites and in Allende

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    Small variations for Mo isotopes have been observed recently in the Allende meteorite and in iron meteorites, mesosiderites, and pallasites, using ICPMS. Large effects for Mo have been reported for leaches of Orgueil and in SiC and graphite from Murchison. Variations for Mo in bulk Allende and in Murchison have also been presented by NTIMS. Effects in Ru isotopes can define further the preserved exotic r, s, and p contributions in this mass region, and possible effects in Ru-98 and Ru-99 from Tc-98 (4.2 Ma half-life) and Tc-99 (0.21 Ma half-life). Previous attempts at determination of Ru isotopes yielded no resolved effects. The present work represents a substantial improvement in precision over the earlier work. Chemical and mass spectrometric analytical techniques are presented to determine the Ru isotope compositions in terrestrial standards and in meteorites.

  17. Carbon Isotopic tests on the Origins of the Shuram Anomaly from the San Juan Fm., Peru

    NASA Astrophysics Data System (ADS)

    Hodgin, E. B.

    2015-12-01

    Carbon isotope anomalies are associated with perturbations to the carbon cycle that offer insight into the geochemical evolution of the Earth. The largest Carbon isotope anomaly in earth history is the Shuram, which remains poorly understood in spite of being linked to the oxygenation of earth, the rise of metazoans, and a complete reorganization of the carbon cycle. From a basin transect of the carbonate-dominated San Juan Formation in southern Peru, we present evidence for the first clear example of the Shuram isotope anomaly in South America. Unique to this succession are ~140 meters of organic-rich black shale within the anomaly, containing as much as 4% TOC. Preliminary data from the organic-rich black shales of the San Juan Fm. confirm that δ13Corg is relatively invariant and does not covary with δ13Ccarb. These observations are consistent with other Shuram sections and support various models: an exogenous carbon source, an enlarged dissolved organic carbon pool, as well as authigenic carbonate production in organic-rich anoxic sediments. Critical tests of these models have been complicated by a paucity of organics in Shuram facies worldwide. Further analyses of the robust organics from the Shuram facies of the San Juan Fm. therefore hold promise in shedding light on the origin of the Shuram isotope anomaly and critical earth history events to which it has been linked.

  18. Anomalies.

    ERIC Educational Resources Information Center

    Online-Offline, 1999

    1999-01-01

    This theme issue on anomalies includes Web sites, CD-ROMs and software, videos, books, and additional resources for elementary and junior high school students. Pertinent activities are suggested, and sidebars discuss UFOs, animal anomalies, and anomalies from nature; and resources covering unexplained phenonmenas like crop circles, Easter Island,…

  19. 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.

  20. Deep Ocean Circulation and Nutrient Contents from Atlantic-Pacific Gradients of Neodymium and Carbon Isotopes During the Last 1 Ma

    NASA Astrophysics Data System (ADS)

    Piotrowski, A. M.; Elderfield, H.; Howe, J. N. W.

    2014-12-01

    The last few million years saw changing boundary conditions to the Earth system which set the stage for bi-polar glaciation and Milankovich-forced glacial-interglacial cycles which dominate Quaternary climate variability. Recent studies have highlighted the relative importance of temperature, ice volume and ocean circulation changes during the Mid-Pleistocene Transition at ~900 ka (Elderfield et al., 2012, Pena and Goldstein, 2014). Reconstructing the history of global deep water mass propagation and its carbon content is important for fully understanding the ocean's role in amplifying Milankovich changes to cause glacial-interglacial transitions. A new foraminiferal-coating Nd isotope record from ODP Site 1123 on the deep Chatham Rise is interpreted as showing glacial-interglacial changes in the bottom water propagation of Atlantic-sourced waters into the Pacific via the Southern Ocean during the last 1 million years. This is compared to globally-distributed bottom water Nd isotope records; including a new deep western equatorial Atlantic Ocean record from ODP Site 929, as well as published records from ODP 1088 and Site 1090 in the South Atlantic (Pena and Goldstein, 2014), and ODP 758 in the deep Indian Ocean (Gourlan et al., 2010). Atlantic-to-Pacific gradients in deep ocean neodymium isotopes are constructed for key time intervals to elucidate changes in deep water sourcing and circulation pathways through the global ocean. Benthic carbon isotopes are used to estimate deep water nutrient contents of deep water masses and constrain locations and modes of deep water formation. References: Elderfield et al. Science 337, 704 (2012) Pena and Goldstein, Science 345, 318 (2014) Gourlan et al., Quaternary Science Reviews 29, 2484-2498 (2010)

  1. Strontium, neodymium, and lead isotopic and trace-element signatures of the East indonesian sediments: provenance and implications for banda arc magma genesis

    NASA Astrophysics Data System (ADS)

    Vroon, P. Z.; van Bergen, M. J.; Klaver, G. J.; White, W. M.

    1995-06-01

    We present new trace-element and Sr-Nd-Pb isotope data for 127 surface sediments and five sediments from DSDP Site 262, distributed along and across the arc-continent collision region of the Banda Arc, East Indonesia. The results are used to evaluate the role of subducted continental material (SCM) in the genesis of the Banda Arc magmas and to assess the extent to which geochemical and isotopic signatures of SCM are controlled by sediment provenance. In the surface sediments lead and neodymium isotope ratios are variable: 206Pb/ 204Pb = 18.65-19.57; 143Nd/ 144Nd = 0.51230-0.51190, with an increase in lead isotope ratios and a decrease in the 143Nd/ 144Nd ratio from northeast to southwest along the Banda Arc. DSDP Site 262 sediments, farthest to the west in the Timor Trough, overlap with the surface sediments and have 206Pb/ 204Pb = 18.89-19.23 and 143Nd/ 144Nd = 0.51200-0.51220. In contrast, the trace-element ratios and REE patterns of the sediments do not show systematic along-arc variations and largely overlap with estimated values for Upper Continental Crust, Post Archean Australian Shale (PAAS), and ODP Site 765 sediments from the Argo Abyssal Plain. From the combined isotopic and trace-element ratios in the terrigenous fraction of the sediments four major provenance areas can be distinguished: North New Guinea + Seram, South New Guinea, Timor, and northern Australia. The lead isotopic variations in the shelf and wedge sediments along the Banda Arc are parallel to similar variations in the volcanics; this is considered to be strong evidence for the incorporation of subducted continental material in the arc magmas. The trace-element characteristics of both the volcanics and the sediments are also consistent with the involvement of sediments in the Banda Arc magma genesis. The hinterland of the sediments is responsible for isotopic signatures created in the Banda Arc mantle through recent subduction. This suggests that some of the mantle heterogeneities that are

  2. 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

  3. Isotopic anomalies in organic nanoglobules from Comet 81P/Wild 2: Comparison to Murchison nanoglobules and isotopic anomalies induced in terrestrial organics by electron irradiation

    NASA Astrophysics Data System (ADS)

    De Gregorio, Bradley T.; Stroud, Rhonda M.; Nittler, Larry R.; Alexander, Conel M. O.'D.; Kilcoyne, A. L. David; Zega, Thomas J.

    2010-08-01

    Nanoglobules are a form of organic matter found in interplanetary dust particles and primitive meteorites and are commonly associated with 15N 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 15N anomaly (δ 15N = 1120‰). Associated, non-globular, organic matter from this track is less enriched in 15N 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 ( sbnd C tbnd N) and carboxyl ( sbnd COOH) functional groups. It is significantly enriched in D (δD = 1000‰) but has a terrestrial 15N/ 14N ratio. Experiments indicate that similar D enrichments, unaccompanied by 15N 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 15N enrichment and highly aromatic chemistry analogous to the Track 80 globule and the other only moderately enriched in 15N 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

  4. Carbon dioxide and oxygen isotope anomalies in the mesosphere and stratosphere

    SciTech Connect

    Thiemens, M.H.; Jackson, T.; Zipf, E.C.

    1995-11-10

    Isotopic ({delta}{sup 17}O and {delta}{sup 18}O) measurements of stratospheric and mesospheric carbon dioxide (CO{sub 2}) and oxygen (O{sub 2}), along with trace species concentrations (N{sub 2}O, CO, and CO{sub 2}), were made in samples collected from a rocket-borne cryogenic whole air sampler. A large mass-independent isotopic anomaly was observed in CO{sub 2}, which may in part derive from photochemical coupling to ozone (O{sub 3}). The data also require an additional isotopic fractionation process, which is presently unidentified. Mesospheric O{sub 2} isotope ratios differed from those in the troposphere and stratosphere. The cause of this isotopic variation in O{sub 2} is presently unknown. The inability to account for these observations represents a fundamental gap in the understanding of the O{sub 2} chemistry in the stratosphere and mesosphere. 28 refs., 2 figs., 1 tab.

  5. Isotopic Anomalies in a Uranium Cluster Formed by Lais

    NASA Astrophysics Data System (ADS)

    van de Walle, J.; Tarento, R. J.; Joyes, P.

    A study of a Au-U liquid alloy ion source (LAIS) where uranium is enriched in its lighter element (20% 235U, 80% 238U) has been performed by high resolution mass spectrometry. Monoatomic species Au+, Au2+, U2+, U3+ and polyatomic species Au+n, Up+n, AunU+ are observed. The monoatomic results are well explained by the Kingham postionization process. Au+n and AunU+ species present an interesting odd-even effect characteristic of monovalent elements. The main result of this preliminary letter is a heteroisotope anomaly which appears in U+2, U+3 and U4+3 emission where only homoisotopes are detected. A similar phenomenon was reported for Cu+2 and Ge+2 in a previous work and was attributed to a higher state of excitation of emitted heteroisotope aggregates which explode as they fly to the collector.1,2

  6. Oxygen Isotope Anomalies in Orgueil Corundum: Confirmation of Presolar Origin

    NASA Astrophysics Data System (ADS)

    Huss, G. R.; Hutcheon, I. D.; Fahey, A. J.; Wasserburg, G. J.

    1993-07-01

    In a study of Mg isotopes in oxide grains from an Orgueil SiC-spinel-rich residue, [1] reported a corundum grain with ^26Mg*/^27Al = 8.9 x 10^-4, a value ~18 times greater than the canonical 5 x 10^-5 value characteristic of refractory phases formed in the solar nebula. Comparable ratios had previously been found only in carbon-rich interstellar materials, SiC and graphite, [2] leading [1] to suggest that Orgueil corundum B is a pre-solar oxide grain. Subsequently, [3] discovered Murchison corundum 83-5 with a sirnilar ^26Mg*/^27Al of 8.7 x 10^-4; the very unusual oxygen isotope composition (delta^17O = 1072 +- 59 per mil, delta^18O = -244 per mil) led [3] to conclude 83-5 is an interstellar oxide grain. The Panurge ion probe was used to determine ^170/^160 and ^180/^160 ratios in 27 Orgueil oxide grains--16 corundum, 2 hibonite, and 9 spinel--and in 6 Allende spinels. Orgueil corundum B has an extreme ^17O excess (delta^17O = 1394 +- 178 per mil (2sigma(mean)) and a hint of an ^18O depletion (delta^18O = -65 +- 64 per mil) (Fig. 1). The extraordinary enrichments in ^26Mg* and ^17O identify Orgueil B as an interstellar oxide grain. Orgueil B and Murchison 83-5 have remarkably similar O- and Mg-isotope compositions. Red giant stars are enriched in ^17O with ^17O/^18O >~ 1 [4], suggesting these stars are a likely source of the interstellar corundum. Production of ^26Al during H-burning in AGB stars also appears to account for the ^26Mg* excess [5,6]. Condensation of corundum in the circumstellar envelope must occur before dredge up of processed material from the stellar interior decreases ^17O/^16O and creates a C-rich atmosphere. The oxygen isotope compositions of the remaining oxide grains fall into three groups (Fig. 1). All but six corundums and one Orgueil spinel exhibit ^16O excesses and lie along the ^16O-mixing line with compositions similar to those of corundum and spinel from Murchison LS, LU, and CFO(sub)c [7]. Data from Allende spinels cluster about a

  7. Calcium-48 isotopic anomalies in bulk chondrites and achondrites: Evidence for a uniform isotopic reservoir in the inner protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Chen, James H.; Zhang, Junjun; Papanastassiou, Dimitri A.; Davis, Andrew M.; Travaglio, Claudia

    2014-12-01

    Thermal ionization mass spectrometry (TIMS) was used to measure the calcium isotopic compositions of carbonaceous, ordinary, enstatite chondrites as well as eucrites and aubrites. We find that after correction for mass-fractionation by internal normalization to a fixed 42Ca/44Ca ratio, the 43Ca/44Ca and 46Ca/44Ca ratios are indistinguishable from terrestrial ratios. In contrast, the 48Ca/44Ca ratios show significant departure from the terrestrial composition (from -2 ε in eucrites to +4 ε in CO and CV chondrites). Isotopic anomalies in ε48Ca correlate with ε50Ti: ε 48Ca=(1.09±0.11)×ε 50Ti+(0.03±0.14). Further work is needed to identify the carrier phase of 48Ca-50Ti anomalies but we suggest that it could be perovskite and that the stellar site where these anomalies were created was also responsible for the nucleosynthesis of the bulk of the solar system inventory of these nuclides. The Earth has identical 48Ca isotopic composition to enstatite chondrites (EH and EL) and aubrites. This adds to a long list of elements that display nucleosynthetic anomalies at a bulk planetary scale but show identical or very similar isotopic compositions between enstatite chondrites, aubrites, and Earth. This suggests that the inner protoplanetary disk was characterized by a uniform isotopic composition (IDUR for Inner Disk Uniform Reservoir), sampled by enstatite chondrites and aubrites, from which the Earth drew most of its constituents. The terrestrial isotopic composition for 17O, 48Ca, 50Ti, 62Ni, and 92Mo is well reproduced by a mixture of 91% enstatite, 7% ordinary, and 2% carbonaceous chondrites. The Earth was not simply made of enstatite chondrites but it formed from the same original material that was later modified by nebular and disk processes. The Moon-forming impactor probably came from the same region as the other embryos that made the Earth, explaining the strong isotopic similarity between lunar and terrestrial rocks.

  8. Determination of mass-dependent isotopic fractionation of cerium and neodymium in geochemical samples by MC-ICPMS.

    PubMed

    Ohno, Takeshi; Hirata, Takafumi

    2013-01-01

    We have developed a new analytical method to determine the mass-dependent isotopic fractionations on Ce and Nd in geochemical samples. Mass discrimination effects on Ce and Nd were externally corrected by normalizing (149)Sm/(147)Sm and (153)Eu/(151)Eu, being 0.92124 and 1.0916, respectively based on an exponential law. The reproducibility of the isotopic ratio measurements on (142)Ce/(140)Ce, (146)Nd/(144)Nd and (148)Nd/(144)Nd were 0.08‰ (2SD, n = 25), 0.06‰ (2SD, n = 39) and 0.12‰ (2SD, n = 39), respectively. The present technique was applied to determine the variations of the Ce and Nd isotopic ratios for five geochemical reference materials (igneous rocks, JB-1a and JA-2; sedimentary rocks, JMn-1, JCh-1 and JDo-1). The resulting ratios for two igneous rocks (JB-1a and JA-2) and two sedimentary rocks (JMn-1 and JCh-1) did not vary significantly among the samples, whereas the Ce and Nd isotope ratios for the carbonate samples (JDo-1) were significantly higher than those for igneous and sedimentary rock samples. The 1:1 simple correlation between δ(142)Ce and δ(146)Nd indicates that there were no significant difference in the degree of isotopic fractionation between the Ce and Nd. This suggests that the isotopic fractionation for Ce found in the JDo-1 could be induced by geochemical or physicochemical processes without changing the oxidation status of Ce, since the redox-reaction can produce larger isotopic fractionation than the reactions without changing the oxidation state. The variations in the Ce and Nd isotope ratios for geochemical samples could provide new information concerning the physico-chemical processes of the sample formation. PMID:23303084

  9. 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 δ17O and δ18O 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, λMDF(H2O) = 0.529 ± 0.003 [2σ standard error (SE)], was determined from 27 CLP samples collected in 2003−2005. An oxygen isotopic anomaly of Δ17O = 76 ± 16 ppm (2σ 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 Δ17O 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 Δ17O 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 (2σ SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

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

    PubMed

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

    2013-09-24

    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 δ(17)O and δ(18)O 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, λMDF(H2O) = 0.529 ± 0.003 [2σ standard error (SE)], was determined from 27 CLP samples collected in 2003-2005. An oxygen isotopic anomaly of Δ(17)O = 76 ± 16 ppm (2σ 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 Δ(17)O 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 Δ(17)O 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 (17)Oexcess of 45 ± 5 ppm (2σ SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

  11. Post-eruptive alteration of silicic ignimbrites and lavas, Gran Canaria, Canary Islands - Strontium, neodymium, lead, and oxygen isotopic evidence

    NASA Technical Reports Server (NTRS)

    Cousens, Brian L.; Spera, Frank J.; Dobson, Patrick F.

    1993-01-01

    The isotopic composition of lavas from oceanic islands provides important information about the composition and evolution of the earth's mantle. Isotopic analyses of Miocene comenditic, pantelleritic, and trachyphonolitic ignimbrites and lavas from the Canary islands were performed. Results provide evidence for posteruptive mobility of Rb and Sr during low temperature postemplacement interaction with circulating ground water. Calculated Sr isotope ratios define a magmatic trend in the stratigraph section. 87Sr/86Sr ratios in hydrated vitrophyte and devitrified matrix separates indicate significant posteruptive interaction with meteoric water starting soon after deposition. This process extends patchily through the entire pyroclastic flow and may be ongoing. 87Sr/86Sr ratios determined by whole rock analysis of silicic rocks from oceanic islands are suspect and should not be incorporated into mantle tracer studies. Anorthoclase phenocrysts are resistant to these processes and may produce useful data.

  12. Neodymium, strontium and chromium isotopic studies of the LEW86010 and Angra dos Reis meteorites and the chronology of the angrite parent body

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Bansal, B.; Wiesmann, H.; Shih, C.-Y.

    1994-01-01

    Neodymium, stontium, and chromium isotopic studies of the LEW86010 angrite established its absolute age and the formation interval between its crystallization and condensation of Allende CAIs from the solar nebula. Pyroxene and phosphate were found to contain approximately 8% of its Sm and Nd inventory. A conventional Sm-147-Nd-143 isochron yielded an age of 4.53 +/- 0.04 Ga (2 sigma and Epsilon(sub Nd sup 143)) = 0.45 +/- 1.1. An Sm-146-Nd-142 isochron gives initial Sm-146/Sm-144 = 0.0076 +/- 0.0009 and Epsilon (sub Nd sup 142) = -2.5 +/- 0.4. The Rb-Sr analyses give initial Sr-87/Sr-86 Iota(sub Sr sup 87) = 0.698972 +/- 8 and 0.698970 +/- 18 for LEW and ADOR, respectively, relative to Sr-87/Sr-86 = 0.71025 for NBS987. The difference, Delta Iota(sub Sr Sup 87), between Iota (sub sr sup 87) for the angrites and literature values for Allende CAIs, corresponds to approximately Ma of growth in a solar nebula with a CI chondrite value of Rb-87/Sr-86 = 0.91, or approximately 5 Ma in a nebula with solar photospheric Rb-87/Sr-86 = 1.51. Excess Cr-53 from extinct Mn-53(t(sub 1/2) = 3.7 Ma)in LEW86010 corresponds to initial Mn-53/Mn-55 = 4.4 +/- 1.0 x 10(exp -5) for the inclusions as previously reported by the Paris group (Birck and Allegre, 1988). The Sm-146/Sm-144 value found for LEW86010 corresponds to solar system initial (Sm-146/Sm-144) = 0.0080 +/- 0.0009 for crystallization 8 Ma after Allende, the difference between Pb-Pb ages of angrites and Allende, or 0.0086 +/- 0.0009 for crystallation 18 Ma after Allende, using the Mn-Cr formation interval. The isotopic data are discussed in the context of a model in which an undifferentiated 'chondritic' parent body formed from the solar nebula approximately Ma after Allende CAIs and subsequently underwent differentiation accompanied by loss of volatiles. Parent bodies with Rb/Sr similar to that of CI, CM, or CO chondrites could satisfy the Cr and Sr isotopic systematics. If the angrite parent body had Rb/Sr similar to that of

  13. Neodymium and strontium isotopic study of Australasian tektites - New constraints on the provenance and age of target materials

    NASA Technical Reports Server (NTRS)

    Blum, Joel D.; Papanastassiou, D. A.; Wasserburg, G. J.; Koeberl, C.

    1992-01-01

    The Nd and Sr isotopic compositions of Australasian tectites (including two flanged Australian tectites, two low-SiO2 Muong Nong-type tectites, and three high-SiO2 Muong Nong-type tectites) and the Nd, Sm, Sr, and Rb concentrations were investigated by isotope-dilution thermal ionization mass spectrometry, and the Sm-Nd and Rb-Sr isotope systematics were used to study the characteristics of the parental material. It is shown that the Nd and Sr isotopic data provide evidence that all Australasian tektites were derived from a single sedimentary formation with a narrow range of stratigraphic ages close to 170 Ma. It is suggested that all of the Australasian tektites were derived from a single impact event and that the australites represent the upper part of a melt sheet ejected at high velocity, whereas the indochinites represent melts formed at a lower level in the target material distributed closer to the area of the impact.

  14. The sp-process and Allende isotope anomalies in calcium and titanium

    NASA Astrophysics Data System (ADS)

    Harris, M. J.

    1983-01-01

    The goal of the study described here is to show that partial nuclear destruction of the Ca isotopes can reproduce the EK-1-4-1 pattern and can simultaneously produce the Ti anomaly observed in that inclusion. The parameterized approach adopted here yields little information about a likely stellar site. Considerations of time scale and proton density, however, both point to a hydrostatic O burning zone, with which the required s-process-like initial composition is compatible. The temperatures involved, however, are considerably lower than those estimated by Arnett (1977) and Weaver, Zimmerman, and Woosley (1978). It is found that slow proton captures on nuclei with Z between 18 and 25 at temperatures in the range where T9 ranges from 1.25 to 1.7 can reproduce the Ca isotopic anomaly in Allende Ca-Al-rich FUN inclusion EK-1-4-1. It is noted that at T9 = 1.55, the required proton exposure approximately reproduces the Ek-1-4-1 Ti anomaly also. Under these conditions, the production of long-lived Ca-41 and Mn-53, as well as of an anomaly in Cr, is predicted.

  15. Post-eruptive alteration of silicic ignimbrites and lavas, Gran Canaria, Canary Islands: Strontium, neodymium, lead, and oxygen isotopic evidence

    SciTech Connect

    Cousens, B.L. ); Spera, F.J. ); Dobson, P.F. )

    1993-02-01

    Isotopic analyses of Miocene comenditic, pantelleritic, and trachyphonolitic ignimbrites and lavas from Gran Canaria, Canary Islands, provide evidence for posteruptive mobility of Rb, Sr, and O. Calculated initial [sup 87]Sr/[sup 86]Sr ratios in whole-rock samples from basaltic lavas and feldspar mineral separates from ignimbrites define a magmatic trend in the stratigraphic section, from ratios of 0.70340 at the base of the Mogan Formation to 0.70305 in the lower Fataga Formation. However, calculated apparent initial [sup 87]Sr/[sup 86]Sr ratios in hydrated vitrophyre and devitrified matrix separates range from 0.7035 to 0.7090. [delta][sup 18]O ratios in basalts and feldspars vary little, from +5.7 to +6.1, yet range from +6.5 to +15.0 in the ignimbrite matrices. In contrast to the Sr and O isotope ratios, Pb and Nd isotope ratios are identical within analytical error in feldspars and their silicic ignimbrite matrices. Sequential leaching experiments and the oxygen data suggest that low-temperature, posteruptive interaction with meteoric water, perhaps containing a small seawater component, has modified Rb and Sr concentrations in the matrices, such that calculated apparent initial [sup 87]Sr/[sup 86]Sr ratios are not those of the magmas when they were erupted. Mobilization of Rb and Sr must occur significantly after eurption. Nd and Pb isotope systems appear to be unaffected by this process. Therefore, [sup 87]Sr/[sup 86]Sr ratios determined by whole rock analysis of silicic rocks from hotspot-type oceanic islands are suspect and should not be incorporated into mantle tracer studies, although analysis of phenocrysts may produce useful data. 40 refs., 5 figs., 3 tabs.

  16. Actual timing of neodymium isotopic variations recorded by Fe-Mn crusts in the western North Atlantic

    USGS Publications Warehouse

    Burton, K.W.; Lee, D.-C.; Christensen, J.N.; Halliday, A.N.; Hein, J.R.

    1999-01-01

    Hydrogenetic ferromanganese (Fe-Mn) crusts from the western North Atlantic record variations in the Nd and Pb isotopic composition of Cenozoic deep water preserved during their growth. The timing and cause of the most striking change have been the subject of debate. Some have proposed that the shift took place after 4 Ma in response to the closure of the Panama gateway. Others have argued that the major change in isotope composition occurred as early as 8 Ma. This study presents high-resolution Nd isotope records for crusts previously dated using 10Be/9Be chronology. These data confirm that the shifts in Nd occurred after 4 Ma, consistent with a likely relationship with the closure of the Central American Isthmus and intensification of Northern Hemisphere Glaciation, and in accordance with changes seen in other physical and chemical records. These results illustrate the need for both a robust chronological framework and high-resolution records before a reliable paleoceanographic interpretation can be made of the variations recorded by Fe-Mn crusts.

  17. Sulfur and Hydrogen Isotope Anomalies in Organic Compounds from the Murchison Meteorite

    NASA Technical Reports Server (NTRS)

    Cooper, G. W.; Thiemens, M. H.; Jackson, T.; Chang, Sherwood

    1996-01-01

    Isotopic measurements have been made on organic sulfur and phosphorus compounds recently discovered in the Murchison meteorite. Carbon, hydrogen and sulfur measurements were performed on individual members of the organic sulfur compounds, alkyl sulfonates; and carbon and hydrogen measurements were made on bulk alkyl phosphonates. Cooper and Chang reported the first carbon isotopic measurements of Murchison organic sulfonates, providing insight into the potential synthetic mechanisms of these and, possibly, other organic species. Hydrogen isotopic measurements of the sulforiates now reveal deuterium excesses ranging from +660 to +2730 %. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of dense molecular clouds. Measurements of the sulfur isotopes provide further constraints on the origin and mechanism of formation of these organic molecules. Recently, there has been growing documentation of sulfur isotopic anomalies in meteoritic material. Thiemens and Jackson have shown that some bulk ureilites possess excess S-33 and Thiemens et al. have reported excess S-33 in an oldhamite separate from the Norton County meteorite. Rees and Thode reported a large S-33 excess in an Allende acid residue, however, attempts to verify this measurements have been unsuccessful, possibly due to the heterogeneous nature of the carrier phase. With the recognition that sulfur isotopes may reflect chemistry in the protosolar nebula or the precursor molecular cloud, identification of potential carriers is of considerable interest. In the present study, the stable isotopes of sulfur were measured in methane sulfonic acid extracted from the Murchison meteorite. The isotopic composition was found to be: (delta)S-33 = 2.48 %, (delta)S-34 = 2.49 % and (delta)S-36 = 6.76 %. Based upon analysis of more than 60 meteoritic and numerous terrestrial samples, the mass fractionation lines are

  18. Nucleosynthetic W isotope anomalies and the Hf-W chronometry of Ca-Al-rich inclusions

    NASA Astrophysics Data System (ADS)

    Kruijer, Thomas S.; Kleine, Thorsten; Fischer-Gödde, Mario; Burkhardt, Christoph; Wieler, Rainer

    2014-10-01

    Ca-Al-rich inclusions (CAI) are the oldest dated objects formed in the solar system and are pivotal reference points in early solar system chronology. Knowledge of their initial 182Hf/180Hf and 182W/184W is essential, not only for obtaining precise Hf-W ages relative to the start of the solar system, but also to assess the distribution of short-lived radionuclides in the early solar nebula. However, the interpretation of Hf-W data for CAI is complicated by nucleosynthetic W isotope variations. To explore their extent and nature, and to better quantify the initial Hf and W isotope compositions of the solar system, we obtained Hf-W data for several fine- and coarse-grained CAI from three CV3 chondrites. The fine-grained CAI exhibit large and variable anomalies in ε183W (εiW equals 0.01% deviation from terrestrial values), extending to much larger anomalies than previously observed in CAI, and reflecting variable abundances of s- and r-process W isotopes. Conversely, the coarse-grained (mostly type B) inclusions show only small (if any) nucleosynthetic W isotope anomalies. The investigated CAI define a precise correlation between initial ε182W and ε183W, providing a direct empirical means to correct the ε182W of any CAI for nucleosynthetic isotope anomalies using their measured ε183W. After correction for nucleosynthetic W isotope variations, the CAI data define an initial 182Hf/180Hf of (1.018±0.043)×10-4 and an initial ε182W of -3.49±0.07. The Hf-W formation intervals of the angrites D'Orbigny and Sahara 99555 relative to this CAI initial is 4.8±0.6 Ma, in good agreement with Al-Mg ages of these two angrites. This renders a grossly heterogeneous distribution of 26Al in the inner solar system unlikely, at least in the region were CAI and angrites formed.

  19. Sulfur and Hydrogen Isotope Anomalies in Organic Compounds from the Murchison Meteorite

    NASA Astrophysics Data System (ADS)

    Cooper, G. W.; Thiemens, M. H.; Jackson, T.; Chang, S.

    1995-09-01

    Carbon, hydrogen and sulfur isotopic measurements have been made on individual members of a recently discovered class of organic sulfur compounds, alkyl sulfonates, in the Murchison meteorite. Cooper and Chang (1) reported the first carbon isotopic measurements of Murchison organic sulfonates, providing insight into potential synthetic mechanisms of these, and possibly other, organic species. Hydrogen isotopic measurements of the sulfonates now reveal deuterium excesses ranging from +660 to +2730 per mil. The deuterium enrichments indicate formation of the hydrocarbon portion of these compounds in a low temperature astrophysical environment consistent with that of dense molecular clouds. Measurement of the sulfur isotopes provide further constraints on the origin and mechanism of formation of these organic molecules. Recently, there has been growing documentation of sulfur isotopic anomalies in meteoritic material. Thiemens and Jackson (2) have shown that some bulk ureilites possess excess 33S and Thiemens et al. (3) have reported excess 33S in an oldhamite separate from Norton County. Rees and Thode (4) reported a large 33S excess in an Allende acid residue, however, attempts to verify this measurement have been unsuccessful, possibly due to the heterogeneous nature of the carrier phase. With the recognition that sulfur isotopes may reflect nebular chemistry, identification of potential carriers is of considerable interest. In the present study the three stable isotopes of sulfur were measured in methane sulfonate extracted from the Murchison meteorite. The isotopic composition was found to be delta 33S=2.48, delta 34S=2.49 and delta 36S = 6.76 per mil. Based upon analysis of more than 60 meteoritic, and numerous terrestrial samples, the mass fractionation lines are defined by 33Delta = delta 33S-0.50 delta 34S and 36Delta = delta 36S -1.97 delta 34S. From these relations a 33Delta = 1.24 per mil and 36Delta = 0.89 per mil is observed. These anomalies

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    This letter reports the discovery of an unusual Allende inclusion that is rich in hibonite, Ca(Al, Ti, Mg)12O19, the most refractory and possibly the most primitive major oxide mineral from the solar nebula. The Mg and Ca isotopic compositions of this hibonite-rich inclusion are studied in order to investigate the distribution of Al-26 in the solar system and to extend the search for isotopic anomalies. The Mg results indicate that no Mg isotopic anomalies are present, that the initial Al-26/Al-27 ratio for the inclusion when it crystallized was less than 200 billionths, and that the Mg mass-fractionation effect in the inclusion must be less than about 20 per mil/amu for the hibonite and 10 per mil/amu for other phases. The Ca studies reveal that large Ca mass-fractionation effects of about 7.5 per mil/amu are present and that additional small 'nonlinear' effects of presumably nuclear origin at a level of about 1 to 2 per mil are present in at least Ca-42. A plausible model for the evolution of the hibonite-rich inclusion is outlined.

  1. Oxygen Isotope Anomaly in the Carbonate Fractions of Aerosols and its Potential to Assess Urban Pollution

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abramian, A.; Dominguez, G.; Jackson, T.; Thiemens, M. H.

    2008-12-01

    = 0.887) was observed between oxygen isotope anomaly (Δ17O) in the carbonate fraction of coarse aerosols and urban index, indicating that the isotope anomaly of carbonates can be used as a proxy for urban pollution. Additionally, controlled laboratory experiments to understand the origin of isotope anomaly in the carbonate fraction of aerosols will be discussed.

  2. Hibonite-bearing microspherules - A new type of refractory inclusions with large isotopic anomalies

    NASA Technical Reports Server (NTRS)

    Ireland, T. R.; Fahey, A. J.; Zinner, E. K.

    1991-01-01

    This paper presents petrographic description as well as results on the major- and trace-element chemistry and on Mg, Ca, and Ti isotopic compositions of three refractory inclusions, including 3413-1/31 inclusion from Lance and Murchison 7-228 and 7-753, the mineralogy of which is dominated by the oxide minerals spinel, hibonite, and perovskite. The microspherules examined seem to constitute a separate class of refractory inclusions, characterized by a distinct morphology and mineralogy; large excesses of Ca-48 and Ti-50, and Mg-26 depletions. It is suggested that this type of inclusions must have formed early, prior to the dilution of isotopic anomalies by mixing processes, and in an area characterized by excesses of Ca-48 and Ti-50, depletions of Mg-26, and a lack of Al-26.

  3. Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars.

    PubMed

    Shaheen, R; Abramian, A; Horn, J; Dominguez, G; Sullivan, R; Thiemens, Mark H

    2010-11-23

    The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess (17)O (0.4-3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O(3) reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

  4. Detection of oxygen isotopic anomaly in terrestrial atmospheric carbonates and its implications to Mars

    PubMed Central

    Shaheen, R.; Abramian, A.; Horn, J.; Dominguez, G.; Sullivan, R.; Thiemens, Mark H.

    2010-01-01

    The debate of life on Mars centers around the source of the globular, micrometer-sized mineral carbonates in the ALH84001 meteorite; consequently, the identification of Martian processes that form carbonates is critical. This paper reports a previously undescribed carbonate formation process that occurs on Earth and, likely, on Mars. We identified micrometer-sized carbonates in terrestrial aerosols that possess excess 17O (0.4–3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O3 reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

  5. The NO+O{sub 3} reaction: A triple oxygen isotope perspective on the reaction dynamics and atmospheric implications for the transfer of the ozone isotope anomaly

    SciTech Connect

    Savarino, J.; Morin, S.; Baroni, M.; Bhattacharya, S. K.; Doussin, J.-F.

    2008-05-21

    Atmospheric nitrate shows a large oxygen isotope anomaly ({delta} {sup 17}O), characterized by an excess enrichment of {sup 17}O over {sup 18}O, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NO{sub x}=NO+NO{sub 2}). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NO{sub x}, greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO+O{sub 3}. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8{+-}5)%({+-}2{sigma}) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O{sub 3} to NO{sub 2}, which is described by the linear relationship {delta} {sup 17}O(NO{sub 2})=Ax{delta} {sup 17}O(O{sub 3})+B, with A=1.18{+-}0.07({+-}1{sigma}) and B=(6.6{+-}1.5) per mille ({+-}1{sigma}). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways.

  6. The NO +O3 reaction: A triple oxygen isotope perspective on the reaction dynamics and atmospheric implications for the transfer of the ozone isotope anomaly

    NASA Astrophysics Data System (ADS)

    Savarino, J.; Bhattacharya, S. K.; Morin, S.; Baroni, M.; Doussin, J.-F.

    2008-05-01

    Atmospheric nitrate shows a large oxygen isotope anomaly (ΔO17), characterized by an excess enrichment of O17 over O18, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NOx=NO+NO2). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NOx, greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO +O3. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8±5)%(±2σ) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O3 to NO2, which is described by the linear relationship ΔO17(NO2)=A ×ΔO17(O3)+B, with A =1.18±0.07(±1σ) and B =(6.6±1.5)‰(±1σ). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways.

  7. Cerium anomaly across the mid-Tournaisian carbon isotope excursion (TICE)

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Morales, D. C.; Maharjan, D. K.

    2015-12-01

    The Early Mississippian (ca. 359-345 Ma) represents one of the most important greenhouse-icehouse climate transitions in Earth history. Closely associated with this critical transition is a prominent positive carbon isotope excursion (δ13C ≥ +5‰) that has been documented from numerous stratigraphic successions across the globe. This δ13C excursion, informally referred to as the TICE (mid-Tournaisian carbon isotope excursion) event, has been interpreted as resulting from enhanced organic carbon burial, with anticipated outcomes including the lowering of atmospheric CO2 and global cooling, the growth of continental ice sheets and sea-level fall, and the increase of ocean oxygenation and ocean redox changes. The casual relationship between these events has been addressed from various perspectives but not yet clearly demonstrated. To document the potential redox change associated with the perturbation of the carbon cycle, we have analyzed rare earth elements (REE) and trace elements across the TICE in two sections across a shallow-to-deep water transect in the southern Great Basin (Utah and Nevada), USA. In both sections, the REE data show a significant positive cerium (Ce) anomaly (Ce/Ce* = Ce/(0.5La+0.5Pr)). Prior to the positive δ13C shift, most Ce/Ce* values are around 0.3 (between 0.2 and 0.4). Across the δ13C peak, Ce/Ce* values increase up to 0.87, followed by a decrease back to 0.2~0.3 after the δ13C excursion (Figure 1). The positive Ce anomaly is best interpreted as recording expansion of oxygen minimum zone and anoxia resulted from increased primary production. This is consistent with a significant increase of nitrogen isotopes (δ15N) across the δ13C peak. Integration of the carbon, nitrogen, and REE data demonstrates a responsive earth systems change linked to the perturbation of the Early Mississippian carbon cycle.

  8. Heavy-ion isotopic anomalies in He-3 rich solar particle events

    NASA Astrophysics Data System (ADS)

    Mason, G. M.; Mazur, J. E.; Halmilton, D. C.

    1994-04-01

    We have measured the approximately 1 MeV/nucleon heavy-ion mass composition during a series of (3)He-rich solar particle events during 1992 July using the University of Maryland instrument on the SAMPEX spacecraft. In addition to enhancements of He-3/He-4 of approximately 103 to 104 larger than coronal values, these events also showed typical enhancements of heavy nuclei of up to a factor of approximately 10 compared with large solar particle events. Over the energy range of approximately 0.4 - 4.0 MeV/nucleon the spectra of both he isotopes as well as heavier ions C, N, O, Ne, Mg, Si, S, Ca+Ar, and Fe were found to be power laws in enegy per nucleon with nearly identical spectral indices, indicating that both the He and heavier ions were accelerated by the same mechanism. We obtain upper limits of approximately 15 for possible enrichments of neutron-rich isotopes of C, N, O, and Fe compared to large solar particle events; however, we find Ne-22/Ne-20 = 0.29 +/- 0.10, an enhancement of a factor of 3-4 compared with large solar particle event abundances. We also find evidence of enrichments of approximately 2-3 for Mg-25/Mg-24 and Mg-26/Mg-24, although the uncertainties are large. Thus while at least one of the heavy elements shows isotopic enhancements of neutron-rich isotopes, the mechanisms that produce the extremely large He-3 enrichments apparently do not produce similarly dramatic isotopic anomalies in the heavy nuclei. These observations constrain possible acceleration models and may indicate that the particles are energized in solar coronal locations enhanced in heavy ions.

  9. Large isotopic anomalies of Si, C, N and noble gases in interstellar silicon carbide from the Murray meteorite

    NASA Astrophysics Data System (ADS)

    Zinner, E.; Ming, T.; Anders, E.

    1987-12-01

    Primitive meteorites contain several noble gas components with anomalous isotopic compositions which imply that they - and their solid 'carrier' phases - are of exotic, pre-solar origin. The authors found that minor fractions of the Murray meteorite contain two minerals not previously seen in meteorites: silicon carbide and an amorphous Si-O phase. They report ion microprobe analyses of these phases which reveal very large isotopic anomalies in silicon, nitrogen and carbon, exceeding the highest anomalies previously measured by factors of up to ≡50. It is concluded that these phases are circumstellar grains from carbon-rich stars, whose chemical inertness allowed them to survive in exceptionally well-preserved form.

  10. Strong water isotopic anomalies in the martian atmosphere: probing current and ancient reservoirs.

    PubMed

    Villanueva, G L; Mumma, M J; Novak, R E; Käufl, H U; Hartogh, P; Encrenaz, T; Tokunaga, A; Khayat, A; Smith, M D

    2015-04-10

    We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth's ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep. PMID:25745065

  11. Strong water isotopic anomalies in the martian atmosphere: Probing current and ancient reservoirs

    NASA Astrophysics Data System (ADS)

    Villanueva, G. L.; Mumma, M. J.; Novak, R. E.; Käufl, H. U.; Hartogh, P.; Encrenaz, T.; Tokunaga, A.; Khayat, A.; Smith, M. D.

    2015-04-01

    We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth’s ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep.

  12. Strong Water Isotopic Anomalies in the Martian Atmosphere: Probing Current and Ancient Reservoirs

    NASA Technical Reports Server (NTRS)

    Villanueva, G. L.; Mumma, M. J.; Novak, R. E.; Käufl, H. U.; Hartogh, P.; Encrenaz, T.; Tokunaga, A.; Khayat, A.; Smith, M. D.

    2015-01-01

    We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth's ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep.

  13. 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; Simon, Justin I.; DePaolo, Donald J.; Meyer, Bradley S. E-mail: fap@levee.wustl.ed E-mail: Justin.I.Simon@NASA.go E-mail: mbradle@clemson.ed

    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.

  14. 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 e

  15. Delineating the effect of El-Nino Southern Oscillations using oxygen and sulfur isotope anomalies of sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abaunza Quintero, M. M.; Jackson, T.; McCabe, J.; Savarino, J. P.; Thiemens, M. H.

    2013-12-01

    Sulfate aerosols, unlike greenhouse gases, contribute to global cooling by acting as cloud condensation nuclei in the troposphere and by directly reflecting solar radiation in the stratosphere. To understand the long-term effect of natural and anthropogenic sulfate aerosol on the climate cycle, it is critical to obtain a clear picture of the factors controlling the transport and transformation of sulfate aerosols. We have employed both oxygen triple isotopes and sulfur quadruple isotopes on sulfates from Antarctic ice samples to define the oxidation history, long range transport dynamics, and sources of sulfate aerosols over time. The measurements are used to deconvolve the impact of natural and anthropogenic aerosols on the stratospheric sulfate aerosol composition. Sulfate aerosols were extracted from a snow pit at the South Pole (1979-2002) with a high resolution temporal (6 month) record of the winter and summer seasons covering two largest volcanic events, Pinatubo and El-chichon and three largest ENSO events of the century. All three oxygen and four sulfur isotopes were measured on the extracted sulfate (Shaheen et al., 2013). The high temperature pyrolysis (1000oC) of silver sulfate yielded O2 and SO2. The oxygen triple isotopic composition of the O2 gas was used to determine the oxidation history of sulfate aerosol and SO2 gas obtained during this reaction was utilized to measure sulfur quadruple isotopes following appropriate reaction chemistry (Farquhar et al., 2001). The data revealed that oxygen isotope anomalies in Antarctic aerosols (Δ17O = 0.8-3.7‰) from 1990 to 2001 are strongly linked to the variation in ozone levels in the upper stratosphere/lower stratosphere. The variations in ozone levels are reflective of the intensity of the ENSO events and changes in relative humidity in the atmosphere during this time period. Sulfate concentrations and sulfur quadruple isotopic composition and associated anomalies were used to elucidate the sources of

  16. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization.

    PubMed

    Salim, Michael A; Willow, Soohaeng Yoo; Hirata, So

    2016-05-28

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  17. Ice Ih anomalies: Thermal contraction, anomalous volume isotope effect, and pressure-induced amorphization

    NASA Astrophysics Data System (ADS)

    Salim, Michael A.; Willow, Soohaeng Yoo; Hirata, So

    2016-05-01

    Ice Ih displays several anomalous thermodynamic properties such as thermal contraction at low temperatures, an anomalous volume isotope effect (VIE) rendering the volume of D2O ice greater than that of H2O ice, and a pressure-induced transition to the high-density amorphous (HDA) phase. Furthermore, the anomalous VIE increases with temperature, despite its quantum-mechanical origin. Here, embedded-fragment ab initio second-order many-body perturbation (MP2) theory in the quasiharmonic approximation (QHA) is applied to the Gibbs energy of an infinite, proton-disordered crystal of ice Ih at wide ranges of temperatures and pressures. The quantum effect of nuclei moving in anharmonic potentials is taken into account from first principles without any empirical or nonsystematic approximation to either the electronic or vibrational Hamiltonian. MP2 predicts quantitatively correctly the thermal contraction at low temperatures, which is confirmed to originate from the volume-contracting hydrogen-bond bending modes (acoustic phonons). It qualitatively reproduces (but underestimates) the thermal expansion at higher temperatures, caused by the volume-expanding hydrogen-bond stretching (and to a lesser extent librational) modes. The anomalous VIE is found to be the result of subtle cancellations among closely competing isotope effects on volume from all modes. Consequently, even ab initio MP2 with the aug-cc-pVDZ and aug-cc-pVTZ basis sets has difficulty reproducing this anomaly, yielding qualitatively varied predictions of the sign of the VIE depending on such computational details as the choice of the embedding field. However, the temperature growth of the anomalous VIE is reproduced robustly and is ascribed to the librational modes. These solid-state MP2 calculations, as well as MP2 Born-Oppenheimer molecular dynamics, find a volume collapse and a loss of symmetry and long-range order in ice Ih upon pressure loading of 2.35 GPa or higher. Concomitantly, rapid softening of

  18. O-16 excesses in Murchison and Murray hibonites - A case against a late supernova injection origin of isotopic anomalies in O, Mg, Ca, and Ti

    NASA Technical Reports Server (NTRS)

    Fahey, A. J.; Goswami, J. N.; Mckeegan, K. D.; Zinner, E. K.

    1987-01-01

    Ion probe measurements of the oxygen isotopic composition of seven hibonite samples from the CM chondrites Murchison and Murray are reported. All samples show large O-16 excesses relative to terrestrial oxygen. The data for all samples plot along the carbonaceous chondrite O-16-rich mixing line and show no evidence for isotopic mass fractionation effects characteristic of FUN inclusions. These hibonites have the largest Ca-48 and Ti-50 isotopic anomalies found to date; thus there is no intrinsic relationship between anomalies of a nucleosynthetic origin and isotopic mass fractionation effects. The large O-16 excess seen in the sample with the largest measured Ca-48 and Ti-50 depletions argues against a late injection of exotic material from a nearby supernova as a source for the isotopic anomalies.

  19. 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.

  20. 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.

  1. ISOTOPIC ANOMALIES IN PRIMITIVE SOLAR SYSTEM MATTER: SPIN-STATE-DEPENDENT FRACTIONATION OF NITROGEN AND DEUTERIUM IN INTERSTELLAR CLOUDS

    SciTech Connect

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

    2012-09-20

    Organic material found in meteorites and interplanetary dust particles is enriched in D and {sup 15}N. 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 {sup 15}N 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 {sup 15}N enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, {sup 15}N enrichment. By considering the spin-state dependence in ion-molecule reactions involving the ortho and para forms of H{sub 2}, we show that ammonia and related molecules can exhibit such a wide range of fractionation for both {sup 15}N and D in dense cloud cores. We also show that while the nitriles, HCN and HNC, contain the greatest {sup 15}N enrichment, this is not expected to correlate with extreme D enrichment. These calculations therefore support the view that solar system {sup 15}N 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.

  2. Isotopic anomaly in peat nitrogen is a probable trace of acid rains caused by 1908 Tunguska bolide

    NASA Astrophysics Data System (ADS)

    Kolesnikov, E. M.; Kolesnikova, N. V.; Boettger, T.

    1998-02-01

    In peat sampled at the Tunguska Cosmic Body (TCB) explosion area, the sharp increase of the N concentration (about three-fold) and the positive N isotopic anomaly (δ 15N = + 3.5‰, see eqn) have for the first time been revealed. In contrast with the C and H effects observed earlier which were clearly limited to the epicentre area (Kolesnikov et al., 1997 in press), the same N effect has also been shown in peat sampled near the Vanavara settlement, 65 km south of the explosion epicentre. A clear connection of the observed anomalies in peat to the 1908 permafrost boundary, synchronism of the changes of δ 15N and the N concentration and also good agreement with data on the K/T boundary deposits allow us to connect the observed effects to acid rain fall-out after passage and an explosion of the TCB.

  3. Zinc isotopic composition of iron meteorites: Absence of isotopic anomalies and origin of the volatile element depletion

    NASA Astrophysics Data System (ADS)

    Chen, Heng; Nguyen, Bach Mai; Moynier, Frédéric

    2013-12-01

    High-precision Zn isotopic compositions measured by MC-ICP-MS are documented for 32 iron meteorites from various fractionally crystallized and silicate-bearing groups. The δ66Zn values range from -0.59‰ up to +5.61‰ with most samples being slightly enriched in the heavier isotopes compared with carbonaceous chondrites (0 < δ66Zn < 0.5). The δ66Zn versus δ68Zn plot of all samples defines a common linear fractionation line, which supports the hypothesis that Zn was derived from a single reservoir or from multiple reservoirs linked by mass-dependent fractionation processes. Our data for Redfields fall on a mass fractionation line and therefore refute a previous claim of it having an anomalous isotopic composition due to nonmixing of nucleosynthetic products. The negative correlation between δ66Zn and the Zn concentration of IAB and IIE is consistent with mass-dependent isotopic fractionation due to evaporation with preferential loss of lighter isotopes in the vapor phase. Data for the Zn concentrations and isotopic compositions of two IVA samples demonstrate that volatile depletion in the IVA parent body is not likely the result of evaporation. This is important evidence that favors the incomplete condensation origin for the volatile depletion of the IVA parent body.

  4. Strontium and neodymium isotopic variations in early Archean gneisses affected by middle to late Archean high-grade metamorphic processes: West Greenland and Labrador

    NASA Technical Reports Server (NTRS)

    Collerson, K. D.; Mcculloch, M. T.; Bridgwater, D.; Mcgregor, V. R.; Nutman, A. P.

    1986-01-01

    Relicts of continental crust formed more than 3400 Ma ago are preserved fortuitously in most cratons. The cratons provide the most direct information about crust and mantle evolutionary processes during the first billion years of Earth history. In view of their polymetamorphic character, these terrains are commonly affected by subsequent tectonothermal events. Hence, their isotope systematics may be severely disturbed as a result of bulk chemical change or local isotopic homogenization. This leads to equivocal age and source information for different components within these terrains. The Sr and Nd isotopic data are presented for early Archean gneisses from the North Atlantic Craton in west Greenland and northern Labrador which were affected by younger metamorphic events.

  5. A strontium and neodymium isotopic study of Apollo 17 high-Ti mare basalts - Resolution of ages, evolution of magmas, and origins of source heterogeneities

    NASA Technical Reports Server (NTRS)

    Paces, James B.; Neal, Clive R.; Taylor, Lawrence A.; Nakai, Shun'ichi; Halliday, Alex N.

    1991-01-01

    The geochronological and compositional differences between previously identified magma types (A, B1, B2, and C) were investigated using high-precision Rb-Sr and Sm-Nd isotopic data for a set of Apollo 17 high-Ti mare basalt samples chosen to span the range of each of the magma types. These data, combined with previously reported geochemical ages, suggest that Apollo 17 volcanism was initially dominated by an eruption of Type B basalts. Data obtained from new whole-rock Sr and Nd isotopic analyses exhibited distinct differences in initial Sr and Nd isotopic compositions between Types A, B1, B2, and C basalts and were found to be consistent with existing petrogenetic models.

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

    SciTech Connect

    Burkhardt, Christoph; Wieler, Rainer; Kleine, Thorsten; Dauphas, Nicolas

    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.

  7. Oxygen and neodymium isotope evidence for source diversity in Cretaceous anorogenic granites from Namibia and implications for A-type granite genesis

    NASA Astrophysics Data System (ADS)

    Trumbull, A.-type granite genesis R. B.; Harris, C.; Frindt, S.; Wigand, M.

    2004-03-01

    Many of the early Cretaceous intrusive complexes in the Damaraland of west-central Namibia are silicic in composition. Although all have trace element characteristics typical for the so-called A-type granites, major differences in alkali/aluminum ratios and isotopic compositions require diverse magma sources. This paper presents Nd and O isotope data from the five largest silicic complexes (Paresis, Erongo, Brandberg, Cape Cross, Gross Spitzkoppe) that provide new constraints on the nature of crustal and mantle sources involved, and their relative proportions. The Paresis complex has an isotopic signature ( δ18O=+9‰, ɛNd 130 Ma=-21) indicating a crustal component similar to Mesoproterozoic gneisses of the Angola craton. The other complexes have isotope variations ( δ18O from +8.1‰ to +10.7‰ and ɛNd 130 Ma from -1 to -9) that can be explained by a binary mixing model between a mantle and crustal component. More importantly, this same mixing line also fits the Nd-O isotope variations reported from the mafic Okenyenya and Messum complexes, and from rhyodacites in the southern Etendeka volcanic sequence. The uniformity of the crustal component implied by this mixing model suggests lower crustal material, in contrast to the geologic complexity of the Neoproterozoic Damara Belt presently exposed at the surface. This is consistent with the isotopic data, and we interpret the crustal component to be lower crustal metametasediments that were dehydrated and perhaps melt-depleted by generation of the S-type granites, which are widespread in the Damara Belt. The mantle component is interpreted to be dominated by the Tristan mantle plume, but some involvement of depleted mantle material is needed to explain all of the isotope data. The data rule out any significant role for enriched, subcontinental mantle lithosphere. All silicic Damaraland complexes, as well as the Etendeka rhyodacites, classify as A-type granites despite their proven source diversity. This means

  8. 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.

  9. Strontium and neodymium isotopic study of Libyan Desert Glass: Inherited Pan-African age signatures and new evidence for target material

    NASA Astrophysics Data System (ADS)

    Schaaf, P.; Müller-Sohnius, D. M.

    2002-04-01

    Libyan Desert Glass (LDG) is an impact-related, natural glass of still unknown target material. We have determined Rb-Sr and Sm-Nd isotopic ratios from seven LDG samples and five associated sandstones from the LDG strewn field in the Great Sand Sea, western Egypt. Planar deformation features were recently detected in quartz from these sandstones. 87Sr/86Sr ratios and e-Nd values for LDG range between 0.71219 and 0.71344, and between -16.6 and -17.8, respectively, and hence are distinct from the less radiogenic 87Sr/86Sr ratios of 0.70910-0.71053 and e-Nd values from -6.9 to -9.6 for the local sandstones from the LDG strewn field. Previously published isotopic ratios from the Libyan BP and Oasis crater sandstones are generally incompatible with our LDG values. LDG formation undoubtedly occurred at 29 Ma, but neither the Rb-Sr nor the Sm-Nd isotopic system were rehomogenised during the impact event, as we can deduce from Pan-African ages of ~540 Ma determined from the regression lines from a total of 14 LDG samples from this work and the literature. Together with similar Sr and Nd isotopic values for LDG and granitoid rocks from northeast Africa west of the Nile, these findings point to a sandy matrix target material for the LDG derived from a Precambrian crystalline basement, ruling out the Cretaceous sandstones of the former "Nubian Group" as possible precursors for LDG.

  10. Neodymium, strontium, and oxygen isotopic variations in the crust of the western United States: Origin of Proterozoic continental crust and tectonic implications

    SciTech Connect

    Bennett, V.C.

    1989-01-01

    Initial Nd isotopic ratios of crystalline rocks from an area of about 1.5 {times} 10{sup 6} km{sup 2} of the western United States have been determined in order to map Precambrian age province boundaries and thus document the growth and modification of the North American continent in the Proterozoic. Three age provinces have been delineated. It is demonstrated that large regions of Early Proterozoic continental crust were formed with anomalous isotopic compositions ({sup 143}Nd/{sup 144}Nd ratios lower than Early Proterozoic depleted-mantle). The variations in the initial {epsilon}{sub Nd} and {delta}{sup 18}O values correlate with each other, and correspond to the previously determined Nd isotopic provinces. The Pelona, Rand, Chocolate Mountain and Orocopia Schists are represented by 15 lithologically and structurally similar schist bodies exposed along the San Andreas and Garlock faults in southern California. The grayschists have measured {epsilon}{sub Nd} values from -1.7 to -11.7 with depleted-mantle model ages of 0.9 to 1.7 Ga. The Nd isotopic compositions can be modeled as variable mixtures of Early Proterozoic continental crust with a Mesozoic are component. The measured {sup 87}Sr/{sup 86}Sr ratios are from 0.7087 to 0.7129 and reflect the presence of an old continental source. Independent of age, the high initial {epsilon}{sub Nd} values ({sup +}9 {plus minus} 1.5) are consistent with derivation at an oceanic spreading center, either at a MORB or in a back-arc basin environment. The presence of both Early Proterozoic continental detritus and a younger sedimentary component in the grayschist protolith, and the MORB affinity of the metabasalts are compatible with formation of the protoliths of the Pelona and related schists in a Mesozoic basin adjacent to the southwestern United States continental margin.

  11. Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species

    NASA Astrophysics Data System (ADS)

    Morin, S.; Sander, R.; Savarino, J.

    2010-12-01

    The isotope anomaly (Δ17O) of secondary atmospheric species such as nitrate (NO3-) or hydrogen peroxyde (H2O2) has potential to provide useful constrains on their formation pathways. Indeed, the Δ17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ17O in the atmosphere. Interpreting variations of Δ17O in secondary species requires an in-depth understanding of the Δ17O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. We present results from numerical simulations carried out using the atmospheric chemistry box model (CAABA/MECCA) to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NOx and HOx. Δ17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the classical mass-balance equation, through the implementation of various sets of hypotheses pertaining to the transfer of Δ17O during chemical reactions. The model confirms that diurnal variations in Δ17O of NOx are well predicted by the photochemical steady-state relationship during the day, but that at night a different approach must be employed (i.e. "fossilization" of the Δ17O of NOx as soon as the photolytical lifetime of NOx drops below ca. 5 min). We quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H2O2 under the various environmental conditions analyzed, which is of particular relevance to larger-scale implementations of Δ17O where high computational costs cannot be afforded.

  12. 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

  13. Oxygen Isotopic Anomaly in Terrestrial Atmospheric Carbonates and its Implications to Understand the Role of Water on Mars

    NASA Astrophysics Data System (ADS)

    Thiemens, M. H.; Shaheen, R.

    2010-12-01

    Mineral aerosols produced from wind-blown soils are an important component of the earth system and comprise about 1000-3000 Tg.yr-1 compared to 400 Tg.yr-1 of secondary aerosols (e.g. carbonaceous substances, organics, sulfate and nitrates). Aerosols have important consequences for health, visibility and the hydrological cycle as they provide reactive surfaces for heterogeneous chemical transformation that may influence gas phase chemistry in the atmosphere. Tropospheric ozone produced in a cascade of chemical reactions involving NOx and VOC’s, can interact with aerosol surfaces to produce new compounds. Oxygen triple isotopic compositions of atmospheric carbonates have been used for the first time to track heterogeneous chemistry at the aerosol surfaces and to resolve a chemical mechanism that only occurs on particle surfaces. Fine and coarse aerosol samples were collected on filter papers in La Jolla, CA for one week. Aerosol samples were digested with phosphoric acid and released CO2 was purified chromatographically and analyzed for O isotopes after fluorination. Data indicated oxygen isotopic anomaly (Δ17O = δ17O - 0.524 δ18O) ranging from 0.9 to 3.9 per mill. Laboratory experiments revealed that adsorbed water on particle surfaces facilitates the interaction of the gaseous CO2 and O3 with formation of anomalous hydrogen peroxide and carbonates. This newly identified chemical reaction scenario provides a new explanation for production of the isotopically anomalous carbonates found in the SNC Martian meteorites and terrestrial atmospheric carbonates and it also amplifies understanding of water related processes on the surface of Mars. The formation of peroxide via this heterogeneous reaction on aerosols surface suggests a new oxidative process of utility in understanding ozone and oxygen chemistry both at Mars and Earth.

  14. Neodymium isotopes and concentrations in Caribbean seawater: Tracing water mass mixing and continental input in a semi-enclosed ocean basin

    NASA Astrophysics Data System (ADS)

    Osborne, Anne H.; Haley, Brian A.; Hathorne, Ed C.; Flögel, Sascha; Frank, Martin

    2014-11-01

    We present the first full water column Nd isotope (εNd) and concentration data for Caribbean seawater, as well as for stations close to the Orinoco River mouth and in the Florida Straits. The surface inflow into the southeastern Caribbean via the Guyana Current is characterized by an εNd signature of -10.9, which is a consequence of the mixing of relatively unradiogenic εNd signatures (-13.6) supplied by the Orinoco River with contributions from the Amazon River (∼-10). Despite the proximity to land, sub-surface and intermediate waters within the Caribbean largely retain the εNd signatures of their source water masses in the Atlantic. In contrast, the deep waters of the Caribbean show εNd signatures at least 3 εNd units more radiogenic than the inflowing Upper North Atlantic Deep Water (UNADW). A εNd shift from -13 to -9.7 can be explained by addition of radiogenic Nd to the deep Caribbean through weathering inputs from land. However, in order to balance such large shifts in εNd with at the same time modest increases in Nd concentrations, Nd must also be removed from seawater within the basin. It is suggested that the long residence time of deep waters in the Caribbean allows significant interaction of seawater with sinking particles and seafloor sediments resulting in more radiogenic values. These findings have implications for the use of εNd as a proxy for paleocirculation in restricted basins, in which the residence times of the deep waters are long.

  15. Simulation of the diurnal variations of the oxygen isotope anomaly (Δ17O) of reactive atmospheric species

    NASA Astrophysics Data System (ADS)

    Morin, S.; Sander, R.; Savarino, J.

    2011-04-01

    The isotope anomaly (Δ17O) of secondary atmospheric species such as nitrate (NO3-) or hydrogen peroxide (H2O2) has potential to provide useful constrains on their formation pathways. Indeed, the Δ17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero Δ17O in the atmosphere. Interpreting variations of Δ17O in secondary species requires an in-depth understanding of the Δ17O of their precursors taking into account non-linear chemical regimes operating under various environmental settings. This article reviews and illustrates a series of basic concepts relevant to the propagation of the Δ17O of ozone to other reactive or secondary atmospheric species within a photochemical box model. We present results from numerical simulations carried out using the atmospheric chemistry box model CAABA/MECCA to explicitly compute the diurnal variations of the isotope anomaly of short-lived species such as NOx and HOx. Using a simplified but realistic tropospheric gas-phase chemistry mechanism, Δ17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the mass-balance equations, through the implementation of various sets of hypotheses pertaining to the transfer of Δ17O during chemical reactions. The model results confirm that diurnal variations in Δ17O of NOx predicted by the photochemical steady-state relationship during the day match those from the explicit treatment, but not at night. Indeed, the Δ17O of NOx is "frozen" at night as soon as the photolytical lifetime of NOx drops below ca. 10 min. We introduce and quantify the diurnally-integrated isotopic signature (DIIS) of sources of atmospheric nitrate and H2O2, which is of particular relevance to larger-scale simulations of Δ17O where high computational costs cannot be afforded.

  16. Tales of volcanoes and El-Niño southern oscillations with the oxygen isotope anomaly of sulfate aerosol

    PubMed Central

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L.; McCabe, Justin; Savarino, Joel; Thiemens, Mark H.

    2013-01-01

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth’s system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980–2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher ∆17O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and ∆17O = 3.3‰, OEI = 11 and ∆17O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that ∆17O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  17. Tales of volcanoes and El-Nino southern oscillations with the oxygen isotope anomaly of sulfate aerosol.

    PubMed

    Shaheen, Robina; Abauanza, Mariana; Jackson, Teresa L; McCabe, Justin; Savarino, Joel; Thiemens, Mark H

    2013-10-29

    The ability of sulfate aerosols to reflect solar radiation and simultaneously act as cloud condensation nuclei renders them central players in the global climate system. The oxidation of S(IV) compounds and their transport as stable S(VI) in the Earth's system are intricately linked to planetary scale processes, and precise characterization of the overall process requires a detailed understanding of the linkage between climate dynamics and the chemistry leading to the product sulfate. This paper reports a high-resolution, 22-y (1980-2002) record of the oxygen-triple isotopic composition of sulfate (SO4) aerosols retrieved from a snow pit at the South Pole. Observed variation in the O-isotopic anomaly of SO4 aerosol is linked to the ozone variation in the tropical upper troposphere/lower stratosphere via the Ozone El-Niño Southern Oscillations (ENSO) Index (OEI). Higher (17)O values (3.3‰, 4.5‰, and 4.2‰) were observed during the three largest ENSO events of the past 2 decades. Volcanic events inject significant quantities of SO4 aerosol into the stratosphere, which are known to affect ENSO strength by modulating stratospheric ozone levels (OEI = 6 and (17)O = 3.3‰, OEI = 11 and (17)O = 4.5‰) and normal oxidative pathways. Our high-resolution data indicated that (17)O of sulfate aerosols can record extreme phases of naturally occurring climate cycles, such as ENSOs, which couple variations in the ozone levels in the atmosphere and the hydrosphere via temperature driven changes in relative humidity levels. A longer term, higher resolution oxygen-triple isotope analysis of sulfate aerosols from ice cores, encompassing more ENSO periods, is required to reconstruct paleo-ENSO events and paleotropical ozone variations. PMID:23447567

  18. Purification of cerium, neodymium and gadolinium for low background experiments

    NASA Astrophysics Data System (ADS)

    Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2014-01-01

    Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search), 136Ce (2β+ candidate with one of the highest Q2β). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides) was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  19. Isotope systematics of Li, Sr, Nd, and volatiles in Indian Ocean MORBs of the Rodrigues Triple Junction: Constraints on the origin of the DUPAL anomaly

    NASA Astrophysics Data System (ADS)

    Nishio, Yoshiro; Nakai, Shun'ichi; Ishii, Teruaki; Sano, Yuji

    2007-02-01

    The DUPAL anomaly, a radiogenic isotope anomaly discovered in the Indian Ocean mantle, has been interpreted as due to a large-scale mantle heterogeneity. To provide new constraints on the DUPAL origin, we analyzed isotope ratios of Li, Sr, and Nd in fresh N-MORB glasses recovered from the Rodrigues Triple Junction in the Indian Ocean, and from the North Atlantic. The Li isotopic compositions of the Indian Ocean DUPAL N-MORBs were comparable to those of the North Atlantic non-DUPAL N-MORBs. The source of the DUPAL signature in Indian Ocean MORBs and the E-MORB-type enriched mantle source have quite different Li isotopic compositions. The 143Nd/ 144Nd values of both sources are significantly lower than those of the North Atlantic N-MORBs. The δ 7Li values of most oceanic island basalts with similar low 143Nd/ 144Nd signatures are also higher than those of the North Atlantic N-MORBs, except for several Koolau lavas. The Li isotope results support the recent proposal that significant amounts of recycled lower continental crust might produce the radiogenic isotope signatures of the Indian Ocean DUPAL source.

  20. Silver isotopic anomalies in iron meteorites - Cosmic-ray production and other possible sources

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.

    1980-01-01

    Sources of excess Ag-107 observed in iron meteorites are investigated with emphasis on reactions of cosmic-ray particles with palladium. Cross sections for the production of the silver isotopes from palladium by energetic cosmic-ray particles are estimated to calculate spallogenic production rates relative to that of Mn-53 from iron. The upper limits for the production rates of Ag-107 and Ag-109 by energetic galactic cosmic-ray particles are 690 and 270 atoms/min/kg(Pd), respectively, and the maximum rate for making excess Ag-107 by spallation reactions is 400 atoms/min/kg(Pd). The excess Ag-107 cannot be produced by a long exposure to cosmic-ray particles, and because it is harder to make the amount of Pd-107 observed in the iron meteorites by an early intense proton irradiation than it is to make the Al-26 observed in other meteorites, it is concluded that the excess Ag-107 is due to the decay of nucleosynthetic Pd-107 in the iron meteorites.

  1. Evolution, Abundance and Biocalcification of Calcareous Nannoplankton During the Aptian (Early Cretaceous): Causes and Consequences for C Isotopic Anomalies, Climate Changes and the Carbon Cycle.

    NASA Astrophysics Data System (ADS)

    Erba, E.

    2005-12-01

    The mid Cretaceous is marked by extreme greenhouse conditions, coeval with emplacement of large igneous provinces, C isotopic anomalies, major changes in structure and composition of the oceans, and accelerated rates in the evolutionary history of calcareous plankton. The Aptian is a crucial interval to decipher links between biotic evolution and environmental pressure: it is appealing for understanding nannofloral biocalcification and feedbacks in the carbonate system and in the global carbon cycle. Ontong Java, Manihiki and Kerguelen Plateaus formed in the Aptian affecting the ocean-atmosphere system with excess CO2, changes in Ca2+ and Mg2+ concentrations, and varying nutrient cycling. Two large C isotopic anomalies are associated with episodes of prolonged high primary productivity, changes in alkality, global warming and cooling, anoxia, speciations and extinctions in planktonic communities. Nannofossil diversity, abundance and biocalcification are quantified in continuous, complete, pelagic sections to derive biosphere-geosphere interactions at short and long time scales. The early Aptian C isotopic anomaly interrupts a speciation episode in calcareous nannoplankton paralleled by a drastic reduction in nannofossil paleofluxes culminating in the nannoconid crisis preceding the Oceanic Anoxic Event 1a and the negative C isotopic spike linked to clathrate melting presumably triggered by the thermal maximum at the onset of the mid Cretaceous greenhouse climate. No extinctions are recorded. In the early late Aptian resumption of nannoconid production and appearance of several taxa are coeval with a return to normal C isotopic values. The occurrence of calpionellids and diversified planktonic foraminifers indicate successful biocalcification and restoration of the thermocline. In the late Aptian a drop in nannofossil abundance and accelerated extinction rates are associated with another C isotopic excursion under cool conditions possibly due to a prolonged volcanic

  2. 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 (δ15N-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 δ15N-NO3- and N* values were as high as 17‰ and as low as -18 μmol N L-1, respectively, at depths around 250 m east of 115°W, but were as low as 5‰ and as high as +1 μmol N L-1, respectively, in subsurface waters west of 170°W. The relationships among NO3- concentrations, N* values, δ15N-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-δ15N-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 δ15N-NO3- and N* values, as well as Trichodesmium abundances and size-specific nitrogen fixation rates at the surface, suggest that the low-δ15N-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 δ15N 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.

  3. Global Neoproterozoic (Sturtian) post-glacial sulfide-sulfur isotope anomaly recognised in Namibia

    NASA Astrophysics Data System (ADS)

    Gorjan, Paul; Walter, Malcolm R.; Swart, Roger

    2003-02-01

    The Neoproterozoic Earth experienced at least two, probably global, glaciations. Each glaciation was superceded by deposition of a layer of carbonate ('cap-carbonate') that has a distinctive lithology and depletion in 13C ( δ13C carbonate ˜ -5‰). The ˜700 Ma Sturtian glaciation is followed by deposition of a cap-carbonate and post-glacial succession which contain bacterially produced sulfides extremely enriched in 34S (average δ34S sulfide ˜ +30‰) with maximum values up to +60‰. This level of 34S enrichment in sulfides is unique to the Sturtian post-glacial succession and recognised in Australia, Canada, and China. In the Neoproterozoic of the Nama Basin, Namibia, the Gobabis Member is the basal unit of the Court Formation, which overlies the glacial Blaubeker Formation. δ13C carbonate analyses from the Gobabis Member range from -5.2 to -2.2‰ (average = -3.7‰; n = 10). δ34S sulfide ranges from +16.1 to +61.1‰ (average = +37.6‰; n = 8). These results are consistent with a Sturtian age for the Blaubeker Formation and overlying Gobabis Member, which have previously been interpreted as Sturtian. The sulfur isotopic results are comparable with δ34S sulfide in Sturtian post-glacial units of Australia, Canada and China. This adds to the evidence for correlation of the Blaubeker Formation with Sturtian glaciations on other continents. The cause of such elevated δ34S sulfide is enigmatic. Geochemical evidence suggests the sulfide was not formed from low sulfate waters nor in euxinic conditions, which discounts any known modern analogue. 34S enrichment in sulfides is therefore postulated to be caused by enrichment of 34S in contemporaneous seawater ( δ34S sulfate up to +60‰?). The rise in seawater δ34S sulfate is considered to be the result of intense bacterial sulfate reduction in an anoxic ocean during the Sturtian glaciation.

  4. Carbon isotope curve and iridium anomaly in the Albian-Cenomanian paleoceanic deposits of the Eastern Kamchatka

    NASA Astrophysics Data System (ADS)

    Savelyev, D. P.; Savelyeva, O. L.; Palechek, T. N.; Pokrovsky, B. G.

    2012-04-01

    determined contents of carbon and oxygen stable isotopes in limestones and have compared the received results to isotope curves of other regions. In studied section the curve of d13C is characterized by a clearly expressed positive shift at the level of the lower carbonaceous bed. Below it and in the overlapping stratum of siliceous limestone (1 cm thickness) d13C has the values of 1.9-2.1 pro mille and above it d13C increases up to 2.5-3 pro mille. The precise d13C maximum after a sharp shift is correlatable with the form of a d13C curve of the Middle Cenomanian Tethyan sections. Accordingly, it is possible to assert, that the lower carbonaceous bed was formed during the mid-Cenomanian anoxic event (MCE). Gradual increase of d13C in the upper part of our section is similar to change of d13C in Upper Cenomanian fragments of Tethyan sections, i.e. the lower carbonaceous bed corresponds to anoxic event at the Cenomanian/Turonian boundary (OAE2). Neutron activation analysis indicates increased up to 9 ppb concentration of Ir at the bottom of the lower carbonaceous bed (inorganic part of the sample was analyzed comprising 46% of the bulk rock). This anomaly correlates in the studied section with a positive shift of d13C. Taking into account radiolarian age data this allows to correlate the anomaly with the MCE. A source of iridium and other elements of the platinum group could be basalts and hyaloclastites from the eruptions during the sedimentation period. Anoxic conditions promoted deposit enrichment in ore elements. This work was supported by the RFBR (No. 10-05-00065).

  5. Neodymium-doped glasses for waveguide lasers

    NASA Astrophysics Data System (ADS)

    Church, Kenneth H.; Zanoni, Raymond; Sapak, David L.; Hayden, Joseph S.

    1994-10-01

    We report recent results from our work on the fabrication of neodymium waveguide lasers. Several neodymium doped glasses. APG-1, LG-680, BK 7 and S 3 made by Schott Glass Technologies, Inc. were studied as candidates for use as waveguide lasers. It was found that S 3, a standard ophthalmic glass, had the best ion-exchange properties of any of the glasses studied. A waveguide laser was successfully made using the neodymium doped S 3 glass.

  6. Q-Switching in a Neodymium Laser

    ERIC Educational Resources Information Center

    Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis

    2012-01-01

    We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

  7. Widespread tungsten isotope anomalies and W mobility in crustal and mantle rocks of the Eoarchean Saglek Block, northern Labrador, Canada: Implications for early Earth processes and W recycling

    NASA Astrophysics Data System (ADS)

    Liu, Jingao; Touboul, Mathieu; Ishikawa, Akira; Walker, Richard J.; Graham Pearson, D.

    2016-08-01

    Well-resolved 182W isotope anomalies, relative to the present mantle, in Hadean-Archean terrestrial rocks have been interpreted to reflect the effects of variable late accretion and early mantle differentiation processes. To further explore these early Earth processes, we have carried out W concentration and isotopic measurements of Eoarchean ultramafic rocks, including lithospheric mantle rocks, meta-komatiites, a layered ultramafic body and associated crustal gneisses and amphibolites from the Uivak gneiss terrane of the Saglek Block, northern Labrador, Canada. These analyses are augmented by in situ W concentration measurements of individual phases in order to examine the major hosts of W in these rocks. Although the W budget in some rocks can be largely explained by a combination of their major phases, W in other rocks is hosted mainly in secondary grain-boundary assemblages, as well as in cryptic, unidentified W-bearing 'nugget' minerals. Whole rock W concentrations in the ultramafic rocks show unexpected enrichments relative, to elements with similar incompatibilities. By contrast, W concentrations are low in the Uivak gneisses. These data, along with the in situ W concentration data, suggest metamorphic transport/re-distribution of W from the regional felsic rocks, the Uivak gneiss precursors, to the spatially associated ultramafic rocks. All but one sample from the lithologically varied Eoarchean Saglek suite is characterized by generally uniform ∼ + 11 ppm enrichments in 182W relative to Earth's modern mantle. Modeling shows that the W isotopic enrichments in the ultramafic rocks were primarily inherited from the surrounding 182W-rich felsic precursor rocks, and that the W isotopic composition of the original ultramafic rocks cannot be determined. The observed W isotopic composition of mafic to ultramafic rocks in intimate contact with ancient crust should be viewed with caution in order to plate constraints on the early Hf-W isotopic evolution of the

  8. 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. ); McKeegan, K.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 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.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    A hypothesis is presented to the effect 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 on an association of related stars. The enrichments in C-13 and the Si isotope systematics of the platy SiC are broadly consistent with theoretical models of nucleosynthesis in low-mass, carbon stars on the ASG. The Si isotope array most plausibly reflects mixing between (Si-28)-rich material, inherited from a previous generation of stars, and material enriched in Si-29 and Si-30, produced in intershell regions by neutron capture during He-burning. 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 the derivation of the SiC from several stars characterized by different rates of C-13 production.

  10. Simulation of the diurnal variations of the isotope anomaly (?17O) of reactive trace gases (NOx, HOx) and implications for the ?17O of nitrate.

    NASA Astrophysics Data System (ADS)

    Morin, Samuel; Sander, Rolf; Savarino, Joël.

    2010-05-01

    The isotope anomaly of secondary atmospheric species such as nitrate (NO3-) has potential to provide useful constrains on their formation pathways. Indeed, the ?17O of their precursors (NOx, HOx etc.) differs and depends on their interactions with ozone, which is the main source of non-zero ?17O in the atmosphere. Interpreting variations of ?17O in nitrate requires an in-depth understanding of the ?17O of its precursors taking into account non-linear chemical regimes operating under various environmental settings. In addition, the role of isotope exchange reactions must be carefully accounted for. To investigate the relevance of various assessments of the isotopic signature of nitrate production pathways that have recently been proposed in the literature, an atmospheric chemistry box model (MECCA, Sander et al., 2005, ACP)) was used to explicitly compute the diurnal variations of the isotope anomaly of NOx, HOx under several conditions prevailing in the marine boundary layer. ?17O was propagated from ozone to other species (NO, NO2, OH, HO2, RO2, NO3, N2O5, HONO, HNO3, HNO4, H2O2) according to the classical mass-balance equation applied at each time step of the model (30 seconds typically). The model confirms that diurnal variations in ?17O of NOx are well predicted by the photochemical steady-state relationship introduced by Michalski et al. (2003, GRL) during the day, but that at night a different approach must be employed (e.g. « fossilization » of the ?17O of NOx as soon as the photochemical lifetime of NOx drops below ca. 5 minutes). The model also allows to evaluate the impact on ?17O of NOx and nitrate of the frequently made simplifying assumption that ?17O(HOx)=0 permil, with and without mass-independent fractionation during the H+O2-HO2 reaction. Recommendations for the modeling of ?17O of nitrate will be given, based on the extensive model work carried out. In addition, the link between diurnal variations of the ?17O of nitrate precursors and seasonal

  11. 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

    NASA Astrophysics Data System (ADS)

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

    1993-07-01

    anomalies observed in CAIBs and/or yield improbably long or unrealistically intense thermal histories relative to both current theoretical models of nebular evolution and inferences from other isotopic systems. The failure of these simple models, coupled with recent observations of "disturbed" Mg isotopic abundances and petrographic features in anorthite and melilite indicative of alteration and recrystallization [5,6], suggests that the oxygen isotopic compositions of these phases may have also been modified by alteration and recrystallization during 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 a reliable indicator of the oxygen isotopic composition of precursor material that formed CAIBs. References: [1] Connolly C. and Muehlenbachs K. (1988) GCA, 52, 1585-1592. [2] Elphick S. C. et al. (1988) Contrib. Mineral. Petrol., 100, 490-495. [3] Reddy K. P. and Cooper A. R. (1981) J. Am. Ceram. Soc., 64, 368-371. [4] Yunmoto H. et al. (1989) GCA, 53, 2387-2394. [5] Podosek F. A. et al. (1991) GCA, 55, 1083-1110. [6] MacPherson G. J. and Davis A. M. (1993) GCA, 57, 231-243.

  12. Isotopic anomalies of Ne, Xe, and C in meteorites. I - Separation of carriers by density and chemical resistance

    NASA Technical Reports Server (NTRS)

    Ming, Tang; Lewis, Roy S.; Anders, Edward; Grady, M. M.; Wright, I. P.

    1988-01-01

    The carriers of presolar noble gases were studied by isotopically analyzing 19 separates from the Murray and Murchison C2 chondrites for Ne, Xe, C, and N. It is found that the carriers of Ne-E(H) and Xe-S are resistant to HCl, HF, boiling HClO4, and CrO3-H2SO4, and thus must be either diamond or some resistant carbide or oxide. The carrier of Ne-E(L) may be some form of amorphous carbon with delta C13 of about +340 percent. A new carbon component, C theta, found as 0.2-2-micron inclusions in Murchison spinel, is amorphous and contains little or no noble gas. A new heavy nitrogen component is found which has an abundance of about 1 ppm in the bulk meteorite, combusts at 450-500 C, and may be associated wtih isotopically normal carbon or with C-alpha.

  13. Isotopic anomalies of Ne, Xe, and C in meteorites. I - Separation of carriers by density and chemical resistance

    NASA Astrophysics Data System (ADS)

    Ming, T.; Lewis, R. S.; Anders, E.; Grady, M. M.; Wright, I. P.; Pillinger, C. T.

    1988-05-01

    The carriers of presolar noble gases were studied by isotopically analyzing 19 separates from the Murray and Murchison C2 chondrites for Ne, Xe, C, and N. It is found that the carriers of Ne-E(H) and Xe-S are resistant to HCl, HF, boiling HClO4, and CrO3-H2SO4, and thus must be either diamond or some resistant carbide or oxide. The carrier of Ne-E(L) may be some form of amorphous carbon with delta C13 of about +340 percent. A new carbon component, C theta, found as 0.2-2-micron inclusions in Murchison spinel, is amorphous and contains little or no noble gas. A new heavy nitrogen component is found which has an abundance of about 1 ppm in the bulk meteorite, combusts at 450-500 C, and may be associated wtih isotopically normal carbon or with C-alpha.

  14. Neodymium Isotope Variability at the Grain Scale in the Sub-Continental Lithospheric Mantle: NdO+ Analyses of Individual Clinopyroxene Grains (<5 ng Nd aliquots) from a Kilbourne Hole Harzburgitic Xenolith.

    NASA Astrophysics Data System (ADS)

    Harvey, J.; Honn, D.; Baxter, E. F.; Warren, J. M.; Hammond, S.; Walshaw, R.

    2014-12-01

    It is evident that at scales of 102 to 10-2 m there is significant isotopic heterogeneity in the mantle that is not always reflected in primitive melts. The "Os isotopic gap"[1] is one such manifestation of this phenomenon but a similar offset exists between the Nd isotope composition of abyssal peridotites and the mid-ocean ridge basalts that they are inferred to have produced[2]. This study takes advantage of recent advances in the analysis of Nd isotopes as NdO+[3,4] which permit the precise analysis of single clinopyroxene grains (<1 mg mass; <5 ng Nd) from a continental harzburgitic xenolith from Kilbourne Hole, NM. Analyses of aggregates of clinopyroxenes from 5 Kilbourne Hole xenoliths reveal a wide range of 143Nd/144Nd (0.513011 ± 28 to 0.513615 ±19)[5]. This study demonstrates significant grain-to-grain isotopic heterogeneity at a scale of 10-2 m (143Nd/144Nd = 0.513089 ± 78 to 0.513364 ± 74) which (i) is equivalent to the range of values for Pacific MORB[6] and (ii) is more primitive than local basalts with an asthenospheric signature[7]. This suggests that small-scale refractory domains exist within the mantle which are either not sampled during partial melting or whose presence is obscured by the melting of higher volumes of more fusible material. Ref:[1]Alard et al. (2005) Nature 436, 1005-1008 [2]Warren et al. (2009) JGR 114, B12203, doi:10.1029/2008JB006186 [3]Harvey and Baxter (2009) Chem. Geol. 258, 251-257 [4]Honn et al. (2013) AGU Fall abstr. V33-2722 [5]Harvey et al. (2012) J. Petrol. 53, 1709-1742 [6]Hofmann (1997) Nature 385, 219-229 [7]Thompson et al. (2005) J. Petrol. 46, 1603-1643

  15. 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 ɛ 54Cr vs. ɛ 50Ti and ɛ 54Cr vs. Δ 17O reveal a fundamental dichotomy among planetary materials. The "carbonaceous" chondrites, by virtue of high ɛ 50Ti and high ɛ 62Ni, as well as, especially for any given Δ 17O, high ɛ 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 Δ 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 ɛ 54Cr vs. ɛ 50Ti and ɛ 54Cr vs. Δ 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 ɛ 50Ti vs. ɛ 54Cr and Δ 17O vs. ɛ 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

  16. Rb-Sr whole-rock and mineral ages, K-Ar, 40Ar/39Ar, and U-Pb mineral ages, and strontium, lead, neodymium, and oxygen isotopic compositions for granitic rocks from the Salinian Composite Terrane, California:

    USGS Publications Warehouse

    Kistler, R.W.; Champion, D.E.

    2001-01-01

    This report summarizes new and published age and isotopic data for whole-rocks and minerals from granitic rocks in the Salinian composite terrane, California. Rubidium-strontium whole-rock ages of plutons are in two groups, Early Cretaceous (122 to 100 Ma) and Late Cretaceous (95 to 82 Ma). Early Cretaceous plutons occur in all granitic rock exposures from Bodega Head in the north to those from the Santa Lucia and Gabilan Ranges in the central part of the terrane. Late Cretaceous plutons have been identified in the Point Reyes Peninsula, the Santa Lucia and the Gabilan Ranges, and in the La Panza Range in the southern part of the terrane. Ranges of initial values of isotopic compositions are 87Sr/86Sr, 0.7046-0.7147, δ18O, +8.5 to +12.5 per mil, 206Pb/204Pb, 18.901-19.860, 207Pb/204Pb, 15.618-15.814, 208Pb/204Pb, 38.569- 39.493, and εNd, +0.9 to -8.6. The initial 87Sr/86Sr=0.706 isopleth is identified in the northern Gabilan Range and in the Ben Lomond area of the Santa Cruz Mountains, in Montara Mountain, in Bodega Head, and to the west of the Farallon Islands on the Cordell Bank. This isotopic boundary is offset about 95 miles (160km) by right-lateral displacements along the San Gregorio-Hosgri and San Andreas fault systems.

  17. Search for extinct natural radioactivity of Pb205 via thallium-isotope anomalies in chondrites and lunar soil.

    NASA Technical Reports Server (NTRS)

    Huey, J. M.; Kohman, T. P.

    1972-01-01

    Thallium and Pb204 contents were determined by stable-isotope-dilution analysis in 16 chondrites, one achondrite, and Apollo 11 and 12 lunar fines. Meteoritic thallium contents vary over a large range, 0.02 to 100 ppb, corresponding to the fact that thallium is a highly fractionated volatile element. Lunar thallium contents are less than 5 ppb. The Tl205/Tl203 ratio was determined in most of the samples, with precision ranging from 0.03% to several percent depending mainly on the amount of thallium present. No variations from the terrestrial ratio were observed. The chondritic isochron slope for Pb205 (13.8-m.y. half-life) is less than or equal to 0.00009 (99% confidence level), corresponding to an interval of at least 60 m.y. and possibly exceeding 120 m.y. between the termination of s-process nucleosynthesis and the lead-thallium fractionations.

  18. Determination of the hyperfine structure constants of the 87Rb and 85Rb 4 D5 /2 state and the isotope hyperfine anomaly

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Liu, Huifeng; Yang, Guang; Yang, Baodong; Wang, Junmin

    2014-11-01

    The hyperfine structure (hfs) splittings of the 4 D5 /2 state for two isotopes of 87Rb and 85Rb atoms are measured based on double-resonance optical pumping spectra in a 5 S1 /2-5 P3 /2-4 D5 /2 ladder-type atomic system. The frequency calibration is performed by employing a wideband fiber-pigtailed phase-type electro-optic modulator together with a Fabry-Pérot cavity to cancel the error arising from nonlinear frequency scanning. The hfs magnetic dipole constant A of the 4 D5 /2 state is determined to be -16.801 ± 0.005 MHz for 87Rb and -4.978 ± 0.004 MHz for 85Rb . The hfs electric quadrupole constant B of the 4 D5 /2 state is determined to be 3.645 ± 0.030 MHz for 87Rb and 6.560 ± 0.052 MHz for 85Rb . The values of A and B for the 87Rb4 D5 /2 state are twice as accurate as previous work with thermal atoms using a femtosecond laser comb and the values of A and B for the 85Rb4 D5 /2 state are 3 times and 25 times more accurate than previous work in laser-cooled atoms using Fabry-Pérot interferometer, respectively. According to this high precision of the hfs constants and the previously measured nuclear g factors of the two isotopes, the value of the d -electron hyperfine anomaly 87Δ85(4 D5 /2 ) is derived to be -0.0041 ± 0.0009.

  19. Tracing the composition and origin of fluids at an ancient hydrocarbon seep (Hollard Mound, Middle Devonian, Morocco): A Nd, REE and stable isotope study

    NASA Astrophysics Data System (ADS)

    Jakubowicz, M.; Dopieralska, J.; Belka, Z.

    2015-05-01

    For the first time, Nd isotope signatures combined with rare earth element (REE) concentrations were used in investigations of ancient seep carbonates. The study was performed on the fossil hydrocarbon seep deposit of the Middle Devonian Hollard Mound (eastern Anti-Atlas, Morocco), where Nd isotopes, REE concentrations, and carbon and oxygen isotope ratios were measured to investigate the origin, former migration pathways and composition of fluids. Relatively high εNd values compared to local Eifelian seawater, as well as consistently appearing positive Eu anomalies in MREE-enriched shale-normalized REE patterns of the seep carbonates provided evidence for interaction between the seeping fluids and the Lower Devonian basaltic volcaniclastics underlying the studied seep deposit. Strongly reducing conditions and increased temperature of methane formation could have constituted an additional factor in the Eu-enrichment of the investigated carbonate phases. The presence of exclusively negative Ce anomalies in these carbonates is in line with observations of other workers that seep limestones may not necessarily display positive Ce anomalies indicative of precipitation under anoxic conditions. The negative Ce anomalies are attributed here to mixing between anoxic pore waters and oxic, Ce-depleted seawater, necessary to enable carbonate precipitation at seeps. The methane-rich fluids ascended most likely from below the volcaniclastic unit and inherited the enriched εNd signatures and positive Eu anomalies due to fluid-rock interactions during their seepage to the seafloor. The carbon isotope data are most consistent with thermogenic origin of methane, although contribution of abiotic and biogenic methane sources cannot be excluded. Our results indicate that neodymium isotope and rare earth element analyses constitute one of the most valuable tools for reconstructing former fluid migration patterns. The study shows also that Nd isotopes and Eu anomalies can serve as

  20. Strontium, neodymium, and lead isotopic evidence for the interaction of post-suhduction asthenospheric potassic mafic magmas of the Highwood Mountains, Montana, USA, with ancient Wyoming craton lithospheric mantle

    NASA Astrophysics Data System (ADS)

    O'Brien, Hugh E.; Irving, Anthony J.; McCallum, I. S.; Thirlwall, Matthew F.

    1995-11-01

    The Eocene potassic mafic rocks of the Highwood Mountains in Montana, USA, share many petrographic, major element, and trace element characteristics with potassic rocks erupted in Recent arcs, including Italy, Indonesia, and western Mexico. However, isotopic compositions of the Highwood samples (radiogenic 87Sr/86Sr of 0.707 to 0.709, unradiogenic ɛNd of -11 to -20, unradiogenic 206Pb/204Pb of 16 to 18) are very different from those of their more modern counterparts, and, as for most other magmas emplaced into the Archean/Proterozoic Wyoming Province, must reflect the influence of ancient, geochemically extreme lithologies in their petrogenesis. The most primitive Highwood minettes and leucitites (8-14 wt% MgO) have high K 20 (4.6 to 8.2 wt%) and Ba (2000-5000 ppm), yet are relatively depleted in TiO 2, Nb, and Ta. Although the Highwood magmas ascended through thick Precambrian crust, their very high trace element contents coupled with their primitive compositions indicate that crustal assimilation was negligible. Instead, it is proposed that the distinctive isotopic and trace element characteristics of the Highwood magmas were acquired by assimilation of lithospheerc mantle by ascending asthenospheric melts. Alternative models suggesting derivation of these and other Wyoming Province magmas by direct melting of lithospheric mantle are rejected on the basis of thermal constraints and the extreme isotopic compositions of mantle xenoliths, including a glimmerite-veined harzburgite, sampled by one of the Highwood minettes. The isotopic and trace element systematics can be modeled by mixing one or more ancient metasomatized mantle components with a dominantly asthenospheric component that has ɛNd near or greater than zero (as observed for many Wyoming Province kimberlitic-alnöitic magmas and for Recent potassic arc magmas that have not traversed ancient lithosphere). The voluminous Eocene mafic magmatism throughout central Montana may have been triggered by

  1. 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; Yoneda, Shigekazu

    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.

  2. 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.

  3. 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.

  4. Electrolysis of neodymium oxide. Final report for the period August 19, 1991 through February 28, 1997

    SciTech Connect

    Keller, R.; Larimer, K.T.

    1997-05-01

    The objective of this research was to develop an electrolytic process for the continuous and economic production of neodymium alloys from neodymium oxide. The electrolysis of neodymium oxide continued to show promise for implementation as a low-cost process to produce high- quality neodymium or neodymium-iron alloy.

  5. Stable Isotope Anomalies and Low Chloride Concentrations in Pore Water of CH4-Rich Sediments at the Tanegashima Mud Volcano, Japan

    NASA Astrophysics Data System (ADS)

    Nakayama, N.; Tsunogai, U.; Ashi, J.; Gamo, T.

    2004-12-01

    Pore water from sediments collected at a Tanegashima mud volcano was analyzed for δ 13C (PDB) of dissolved CH4 together with other chemical components, Cl- and SO42-, and the δ 18O and δ D (SMOW). The Tanegashima mud volcanoes are located at the water depths from 1400 m to 1800 m, off Tanegashima island between Ryukyu trench and Ryukyu arc of Japan. It is situated at the end of south-western convergent plate boundary on Nankai-trough, which forms a part of Philippine Sea plate subducting under Eurasian plate. This cruise was conducted as a part of the JNOC (Japan National Oil Corporation) geochemical survey by R/V Hakurei-maru II. The concentrations of CH4 were generally higher than 100 micro-mol/kg. Its highest concentration (715 micro-mol/kg) was found in the crest core of a mud volcano. The δ 13C values ranged from -32 to -50 ‰ . C2H6 was detected only in the pore waters collected from the vicinity of the crest of the mud volcano. The highest δ 13C (around -22 ‰ ) and low C1/C2 concentration ratios (less than 100) were measured at the crest site, supporting the thermogenical production of methane. Other geochemical anomalies were also observed in the crest pore water. The concentrations of Cl- in the pore water at this site were extremely depleted to a minimum of 350 mmol/kg. The Cl- anomaly has not been previously reported for pore water from mud volcanoes around Japan. An endmember of isotopic composition of the fluid is estimated to be +12 ‰ for δ 18O and -40 ‰ for δ D. From these results we conclude that the most likely process to reduce pore water salinity is primarily the mixing of clay mineral dehydration water with seawater. The thermogenic methane found in the crest pore waters of the Tanegashima mud volcano may be brought from the depths of sediments due to the migration of fluid evolved by mineral the dehydration process.

  6. Radio-Purification of Neodymium Chloride

    SciTech Connect

    Hans, S.; Yeh, M.; Cumming, J. B.; Hahn, R. L.

    2011-04-27

    Organometallic liquid scintillator becomes one of the man detection mediums for neutrino experiment. Liquid-liquid extraction is the method of choice for loading metallic ions of interest into the organic solvents at BNL. High purity of all starting materials is essential for the optimization of synthesis. A newly developed 'self-scavenging' technique was applied to purify undesired radioisotopes from the starting metal compound and found to effectively remove thorium and such containments from the neodymium chloride for SNO+.

  7. Quenching of neodymium fluorescence by molecular hydrogen

    SciTech Connect

    Prohaska, J.D.; Machewirth, D.P.; Snitzer, E.

    1995-04-01

    We show that the hydrogen-loading technique used to enhance a fiber`s ultraviolet photosensitivity for writing Bragg gratings can lead to quenching of the lasing ion`s fluorescence. The neodymium fluorescence and radiative lifetimes are measured for the untreated fiber, the hydrogen-loaded fiber, and the postannealed fiber. We show that postannealing can be used to remove the unreacted hydrogen molecules from the fiber laser and restore the radiative lifetime to near that of its original value.

  8. Hawaiian imprint on dissolved Nd and Ra isotopes and rare earth elements in the central North Pacific: Local survey and seasonal variability

    NASA Astrophysics Data System (ADS)

    Fröllje, Henning; Pahnke, Katharina; Schnetger, Bernhard; Brumsack, Hans-Jürgen; Dulai, Henrietta; Fitzsimmons, Jessica N.

    2016-09-01

    Dissolved neodymium isotopes (143Nd/144Nd, expressed as εNd) and rare earth elements (REEs) have the potential to trace the provenance of lithogenic material as well as water masses. The central North Pacific is poorly investigated with respect to its Nd isotope signature and REE cycling, and little is known about the contributions of volcanic islands, such as Hawaii, relative to dust input from Asian deserts to the surface water REE budgets. Here we present dissolved Nd isotope and REE data along with long-lived radium isotope activities from Hawaii Ocean Time-Series Station ALOHA and coastal waters from Oahu, sampled for a GEOTRACES process study in February 2011. The data are supplemented with seasonal samples from ALOHA. Our results show a clear influence of the Hawaiian Islands on the coastal ocean and surface waters at ALOHA during February, expressed by higher surface water Ra activities, radiogenic surface εNd (εNd = +1.4 to -1.0), and elevated Eu anomalies (Eu/Eu∗ ⩾ 1.3). Seasonal cycles of Asian dust deposition most likely contribute to the seasonal εNd variability of surface waters at ALOHA, as suggested by more negative εNd and the lack of Eu anomalies in summer. Neodymium isotopes in the intermediate and deep water column at ALOHA trace typical North Pacific water masses, such as North Pacific Intermediate Water and North Pacific Deep Water. We suggest that a radiogenic εNd excursion in 1000-2000 m water depth, observed in various North Pacific profiles, is controlled by advection of a modified Upper Circumpolar Deep Water or North Equatorial Pacific Intermediate Water. We further present an updated average εNd signature of -3.5 ± 0.5 for North Pacific Deep Water and show that REE patterns of deep waters at ALOHA are dominantly controlled by vertical processes.

  9. CAMPing by the sea: Evidence for synchrony of volcanism and the end-Triassic extinction and carbon isotope anomaly from a marine Triassic-Jurassic boundary section

    NASA Astrophysics Data System (ADS)

    Pálfy, J.; Zajzon, N.

    2012-04-01

    The end-Triassic extinction (ETE) is one of the five largest Phanerozoic mass extinctions, associated with and likely triggered by rapid and severe environmental change. Volcanism in the Central Atlantic Magmatic Province (CAMP) has been proposed as the main trigger, but direct evidence for this linkage is scarce. To help constrain scenarios for the Triassic-Jurassic boundary (TJB) events, we obtained a temporally highly resolved, multidisciplinary dataset from the Kendlbachgraben section in the Northern Calcareous Alps in Austria. The section belongs to the same paleogeographic unit (Eiberg Basin) and share similar stratigraphies with the newly selected base Jurassic GSSP at Kuhjoch. The topmost beds of the Rhaetian Kössen Formation yielded an REE pattern that differs from all other levels in an enrichment of heavy REEs, hinting at some minor contribution from mantle-derived magmatic material to the sedimentary basin. Micromineralogy of the same bed revealed pseudomorphs of altered, euhedral pyroxene and amphibole crystals. Their well-faceted morphology excludes any terrestrial weathering and transport, but is consistent with their origin from air-fallen distal mafic volcanic ash. Peculiar spherical or rounded grains, altered to illite/aluminoceladonite were also observed, likely representing altered volcanic glass. The dominant clay mineral of this bed is low- to medium-charged smectite, accompanied by vermiculite, both typical alteration products of mafic rocks. These features from a bed deposited very near to the TJB are interpreted as direct evidence of CAMP volcanism, immediately preceding the main extinction event and the initial negative carbon isotope anomaly. Clay mineralogy of the Rhaetian-Hettangian Kendlbach Formation (overlying the Kössen Formation) reveals a kaolinite-dominated interval at the base of the formation, followed by an illite-dominated interval. Thus a hot and humid period may have characterized the TJB, in agreement with a previously

  10. Holonomy anomalies

    SciTech Connect

    Bagger, J.; Nemeschansky, D.; Yankielowicz, S.

    1985-05-01

    A new type of anomaly is discussed that afflicts certain non-linear sigma models with fermions. This anomaly is similar to the ordinary gauge and gravitational anomalies since it reflects a topological obstruction to the reparametrization invariance of the quantum effective action. Nonlinear sigma models are constructed based on homogeneous spaces G/H. Anomalies arising when the fermions are chiral are shown to be cancelled sometimes by Chern-Simons terms. Nonlinear sigma models are considered based on general Riemannian manifolds. 9 refs. (LEW)

  11. Holmium laser pumped with a neodymium laser

    SciTech Connect

    Bowman, S.R.; Rabinovich, W.S.

    1991-07-30

    This patent describes a solid-state laser device. It comprises a holmium laser having a first host material doped with an amount of holmium ions sufficient to produce an output laser emission at about 3 {mu}m when the holmium ions in the holmium laser are pumped by a pump beam at a wavelength of about 1.1 {mu}m; and neodymium laser pump source means for supplying a pump beam to pump the holmium ions in the holmium laser at a wavelength of about 1.1 {mu}m.

  12. Neodymium-142 evidence for Hadean mafic crust.

    PubMed

    O'Neil, Jonathan; Carlson, Richard W; Francis, Don; Stevenson, Ross K

    2008-09-26

    Neodymium-142 data for rocks from the Nuvvuagittuq greenstone belt in northern Quebec, Canada, show that some rock types have lower 142Nd/144Nd ratios than the terrestrial standard (epsilon142Nd = -0.07 to -0.15). Within a mafic amphibolite unit, 142Nd/144Nd ratios correlate positively with Sm/Nd ratios and produce a 146Sm-142Nd isochron with an age of 4280(-81)(+53) million years. These rocks thus sample incompatible-element-enriched material formed shortly after Earth formation and may represent the oldest preserved crustal section on Earth. PMID:18818357

  13. Embedded of neodymium oxide nanoclusters in silica

    NASA Astrophysics Data System (ADS)

    Duhan, S.; Aghamkar, P.; Singh, M.; Kishore, N.

    2007-06-01

    The solgel process successfully prepared Nd IIO 3 / SiO II nanocomposites. After drying in air at 85°C for three days, samples were heat treated, in air, at 750, 950, 1150 and 1250°C. Characterizations were made by, Infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Mechanisms of neodymium oxide nano clusters formation in the densified silica matrix with respect to thermal treatment are discussed. XRD profiles confirm the crystallinity of the nanoclusters. The size of the nanoclusters was found in the range 15-30nm.

  14. 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.

  15. Stellar neutron capture cross sections of the Nd isotopes

    SciTech Connect

    Wisshak, K.; Voss, F.; Kaeppeler, F.; Kazakov, L.; Reffo, G.

    1998-01-01

    The neutron capture cross sections of {sup 142}Nd, {sup 143}Nd, {sup 144}Nd, {sup 145}Nd, {sup 146}Nd, and {sup 148}Nd have been measured in the energy range from 3 to 225 keV at the Karlsruhe 3.75 MV Van de Graaff accelerator. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction by bombarding metallic Li targets with a pulsed proton beam. Capture events were registered with the Karlsruhe 4{pi} Barium Fluoride Detector. The cross sections were determined relative to the gold standard. The experiment was difficult due to the small cross sections of the even isotopes at or near the magic neutron number N=82, and also since the isotopic enrichment of some samples was comparably low. The necessary corrections for capture of scattered neutrons and for isotopic impurities could be determined reliably thanks to the high efficiency and the spectroscopic quality of the BaF{sub 2} detector, resulting in a consistent set of (n,{gamma}) cross sections for the six stable neodymium isotopes involved in the s process with typical uncertainties of 1.5{endash}2{percent}. From these data, Maxwellian averaged cross sections were calculated between kT=10 and 100 keV. The astrophysical implications of these results were investigated in an s-process analysis, which deals with the role of the s-only isotope {sup 142}Nd for the N{sub s}{l_angle}{sigma}{r_angle} systematics near the magic neutron number N=82, the decomposition of the Nd abundances into the respective r-, s-, and p-process components, and the interpretation of isotopic anomalies in meteoritic material. {copyright} {ital 1998} {ital The American Physical Society}

  16. Correlated nucleosynthetic isotopic variability in Cr, Sr, Ba, Sm, Nd and Hf in Murchison and QUE 97008

    NASA Astrophysics Data System (ADS)

    Qin, Liping; Carlson, Richard W.; Alexander, Conel M. O.'D.

    2011-12-01

    Acid leaching of the primitive C-chondrite Murchison and O-chondrite QUE 97008 reveal nucleosynthetic anomalies in Cr, Sr, Ba, Nd, Sm and Hf. The anomalies in all but Cr and Sm are best explained by variable additions of pure s-process nuclides to a background nebular composition slightly enriched in r-process isotopes compared to average Solar System material. Leaching leaves a residue in Murchison that is strongly enriched in s-process nuclides with depletions of over 0.1% in 135Ba and seven parts in 10,000 in 84Sr. If there are p-process anomalies in these two elements, they are lost in the variability caused by different r-, s-process contributions to the normalizing isotopes. The concentration and isotope systematics are consistent with the Ba and Sr isotopic composition in the Murchison residue being strongly influenced by s-process-rich presolar SiC. In general, the nucleosynthetic isotope anomalies are 2- to 5-fold smaller in QUE 97008 than in Murchison. The different magnitudes of isotope anomalies are similar to the difference in matrix abundance between CM and O chondrites consistent with the suggestion that the carriers of nucleosynthetically anomalous material preferentially reside in the matrix and that some of this material has been distributed throughout the O-chondrite minerals as a result of thermal metamorphism. Neodymium, Sm and Hf display variable s-, r-process nuclide abundances as in Ba and Sr, but the anomalies are much smaller (e.g. ɛ 148Nd, ɛ 148Sm = -5.7, 2.1, respectively, in Murchison and -0.43, 0.16, respectively in QUE 97008 residues). After correcting Nd and Sm for s-, r-process variability, Sm in whole rock chondrites shows variable relative abundances of the p-process isotope 144Sm that correlate weakly with 142Nd suggesting that the direct p-process contribution to 142Nd is small (˜7-9%). Nucleosynthetic variability in Nd explains the range in 142Nd/ 144Nd seen between C and O, E-chondrites, but not the difference between

  17. Luminescence from chromium-neodymium-doped lithium niobate

    NASA Astrophysics Data System (ADS)

    Mahpoud, S.; Chamiel, N.; Weiss, A. M.; Rosenbluh, M.; Herman, A.; Shoham, A.; Lipavsky, B.; Rotman, S. R.

    1999-10-01

    Luminescence from chromium-neodymium-doped lithium niobate (LiNbO 3) was experimentally measured to determine the degree of non-radiative energy transfer between chromium and neodymium ions. Evidence is presented for two different time constants for emission from chromium ions in the material, indicating that non-radiative transfer does occur. Differences between quasi-continuous pumping and pulsed excitation are discussed.

  18. 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)…

  19. Neodymium neutron transmission and capture measurements and development of a new transmission detector

    NASA Astrophysics Data System (ADS)

    Barry, Devin P.

    Neodymium is a 235U fission product and is important in reactor neutronic calculations. The aim of this thesis is to improve upon the existing neutron cross section data of neodymium. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made at the 25-m flight station with a 16-segment Nal multiplicity detector, and the transmission measurements were performed at 15-m and 25-m flight stations, respectively, with 6Li glass scintillation detectors. After the data were collected and reduced, resonance parameters were determined by simultaneously fitting the transmission and capture data with the multilevel R-matrix Bayesian code SAMMY. The resonance parameters for all naturally occurring neodymium isotopes were deduced within the energy range of 1.0 eV to 500 eV. The resulting resonance parameters were used to calculate the capture resonance integral with this energy region and were compared to calculations obtained when using the resonance parameters from ENDF-B/VI. The RPI parameters gave a resonance integral value of 32 +/- 1 barns that is approximately 7% lower than that obtained with the ENDF-B/VI parameters. The current measurements significantly reduce the statistical uncertainties on the resonance parameters when compared with previously published parameters. This thesis also explains the resolution function in detail and discusses its importance when fitting experimental data to extract resonance parameters. More accurate resolution function parameters were determined for epithermal transmission and capture measurements by fitting well known resonances in Uranium-238. Improved transmission bare-bounce target in-beam photomultiplier tube (PMT) resolution function parameters were found and compared to those used previously at the RPI LINAC and a marked improvement in the quality of the fits is shown. In addition

  20. Electrolytic production of neodymium metal from a molten chloride electrolyte

    SciTech Connect

    Chambers, M.F.; Murphy, J.E.

    1991-01-01

    This paper reports that the U.S. Bureau of Mines conducted experiments on electrowinning of neodymium metal by using a molten-metal cathode at 650{degrees} C and an electrolyte of 50 mol pet NdCl, (neodymium chloride) and 50 mol pet KCl (potassium chloride). The molten-metal cathodes were alloys of magnesium and zinc or magnesium and cadmium. Current efficiencies were 90 pct with a Mg-Zn cathode and 80 pct with a Mg-Cd cathode. The Mg-Cd cathode was easily separated from the electrolyte. In contrast, the Mg-Zn cathode tended to mix with the electrolyte, making separation difficult. The cathode metals were separated from the neodymium by distillation at 1,100{degrees} C under a vacuum of 10{sup {minus}4} torr. Neodymium metal of 99.9 + purity was recovered from the Mg-Cd alloy cathode after 30 min distillation time. The neodymium recovered from the Mg-Zn system contained almost 2 pct Zn after vacuum distillation. Continuous operation using the Mg-Cd alloy cathode was demonstrated.

  1. The interplay between particulate and dissolved neodymium in the Western North Atlantic: First insights and interpretations

    NASA Astrophysics Data System (ADS)

    Stichel, T.; Kretschmer, S.; Lambelet, M.; van de Flierdt, T.; Rutgers van der Loeff, M.; Rijkenberg, M. J. A.; Gerringa, L. J.; De Baar, H. J. W.

    2014-12-01

    Dissolved neodymium (Nd) isotopes (expressed as ɛNd) have been widely used as a water mass tracer to reconstruct paleo ocean circulation. However, the marine geochemical cycle of Nd is not well understood. Unclear input mechanisms, scarcity of available data, and observed decoupling between dissolved ɛNd and Nd concentration patterns ([Nd]) are only a few of the unresolved issues. The latter is often referred to as the Nd paradox(e.g. Goldstein and Hemming 2003). Here we revisit this paradox with an unprecedented data set on particulate Nd isotope and concentration data from five stations along the Dutch GEOTRACES transect GA02 in the western North and equatorial Atlantic Ocean (cruises 64PE319 and 64PE321 from April to July 2010). Particulates were collected with in-situ pumps on 0.8 µm Supor filters and subjected to a total digestion procedure in the home laboratory. The particulates collected farthest north (Irminger Sea and Labrador Sea) show a strong affinity to the nearby land masses in their Nd isotope composition: Very negative values (ɛNd ≈-20) are observed in the Labrador Sea, which is surrounded by old continental rocks. More positive values of up to ɛNd ≈-4 are found east of Greenland probably derived from the Nansen Fjord Formation's basaltic rocks. In these two areas the particulate ɛNd is offset from dissolved Nd isotopes by up to 7.7 ɛ-units, but reveals a similar vertical distribution. Further downstream of the flow path of the North Atlantic Deep Water, dissolved and particulate Nd isotopic compositions in the water column seem to merge and become indistinguishable from one another south of Bermuda (BATS station). This seems to indicate that particulate and dissolved fractions exchange with increasing distance from source regions and age of water masses. Neodymium concentrations in particulates [pNd] are low (KD<5%) and invariant. However, most stations show a significant increase in [pNd] close to the seafloor, where [pNd] nearly

  2. Statistical clumped isotope signatures

    PubMed Central

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  3. Statistical clumped isotope signatures.

    PubMed

    Röckmann, T; Popa, M E; Krol, M C; Hofmann, M E G

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  4. New high-strength neodymium phosphate laser glass

    SciTech Connect

    Galagan, B I; Glushchenko, I N; Denker, B I; Kalachev, Yu L; Mikhailov, Viktor A; Sverchkov, S E; Shcherbakov, Ivan A; Kuleshov, N V

    2009-12-31

    A high-strength neodymium laser glass (SNLG) based on an alumoborophosphate composition is developed and synthesised; its physicochemical, spectral, luminescent, and lasing characteristics are studied. It is found that the chemical stability and thermal resistance of the new glass are considerably higher than the corresponding characteristics of known neodymium-doped phosphate laser glasses. Investigations of lasing upon longitudinal diode pumping showed that, due to the higher thermal resistance, the new glass allows one to obtain output powers twice as high as those of industrial GLS22 glass. (active media)

  5. Nanowatt threshold, alumina sensitized neodymium laser integrated on silicon

    PubMed Central

    Maker, Ashley J.; Armani, Andrea M.

    2013-01-01

    Low threshold lasers based on rare-earth elements have enabled numerous scientific discoveries and innovations in industry. However, pushing the threshold into the sub-microwatt regime has been stymied by a fundamental material phenomenon. Specifically, rare earth dopants form clusters which quench emission and reduce efficiency. Here, we fabricate resonant cavity lasers from neodymium-doped silica films containing alumina. The alumina prevents the clustering of the Neodymium, enabling the lasers to achieve thresholds of 530nanoWatts at room temperature. PMID:24216946

  6. 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

  7. Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary

    PubMed Central

    Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jérôme; van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine

    2015-01-01

    Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ɛNd values are shifted from the dissolved Nd river endmember (−8.9) to values typical of river suspended matter (−10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments. PMID:26158849

  8. Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary.

    PubMed

    Rousseau, Tristan C C; Sonke, Jeroen E; Chmeleff, Jérôme; van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine

    2015-01-01

    Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ɛNd values are shifted from the dissolved Nd river endmember (-8.9) to values typical of river suspended matter (-10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments. PMID:26158849

  9. Efficient wide-aperture neodymium glass rod amplifiers

    SciTech Connect

    Potemkin, A K; Zhurin, K A; Kirsanov, A V; Kopelovich, E A; Kuznetsov, M V; Kuz'min, A A; Flat, F A; Khazanov, Efim A; Shaikin, A A

    2011-06-30

    Amplifiers based on neodymium phosphate glass rods 60 - 100 mm in diameter are experimentally studied. The amplifiers are pumped by INP-16/250 tubular flash lamps placed in a universal pump cavity with a two-section mirror reflector. A compact high-voltage capacitive energy storage with a preionisation circuit was developed to supply the lamps. (lasers)

  10. Marine vs. local control on seawater Nd-isotope ratios at the northwest coast of Africa during the late Cretaceous-early Eocene

    NASA Astrophysics Data System (ADS)

    Kocsis, L.; Gheerbrant, E.; Mouflih, M.; Cappetta, H.; Ulianov, A.; Chiaradia, M.

    2013-12-01

    At the northwest corner of Africa excellent conditions existed for phosphate formation (i.e., stable upwelling system) during the late Cretaceous-early Eocene. This is probably in relation to stable tectonic evolution of shallow epicontinental basins at a passive continental margin and to their paleogeographic situation between the Atlantic and Tethys marine realms. To better comprehend paleoceanic conditions in this area, radiogenic isotope ratios (87Sr/86Sr and 143Nd/144Nd) and trace element compositions of fossil biogenic apatite are investigated from Maastrichtian to Ypresian shallow marine phosphorite deposits in Morocco (Ouled Abdoun and Ganntour Basins). Rare earth elements (REE) distributions in the fossils are compatible with early diagenetic marine pore fluid represented by negative Ce-anomaly and heavy REE enrichment. An overall shift in Ce-anomaly is apparent with gradually lower values in younger fossils along three distinct assemblages that correspond to Maastrichtian, Danian-Thanetian and Ypresian periods. The temporal change can be interpreted as presence of gradually more oxygenated seawater in the basins. Strontium isotopic ratios of the fossils follow the global Sr-evolution curve. However, the latest Cretaceous and the oldest Paleocene fossils yielded slightly higher ratios than the global ocean, which could reflect minor diagenetic alteration. Neodymium isotopic ratios are quite even along the phosphate series with ɛNd(t) values ranges from -6.8 to -5.8. These values are higher than those reported for average North Atlantic deep water and Tethyan seawater (e.g., Stille et al., 1996; Thomas et al., 2003). For the origin of the stable, high 143Nd/144Nd we propose three main hypotheses: (1) contribution of continental Nd-source, (2) locally controlled deep water Nd-isotope ratios near the coast from where upwelling originated in the area and (3) possible surface marine water contribution from the Pacific across the Atlantic. Stille, P., Steinmann

  11. Materials flow analysis of neodymium, status of rare earth metal in the Republic of Korea.

    PubMed

    Swain, Basudev; Kang, Leeseung; Mishra, Chinmayee; Ahn, JoongWoo; Hong, Hyun Seon

    2015-11-01

    Materials flow analysis of neodymium, status of rare earth elements (REEs) in the Republic of Korea has been investigated. Information from various resources like the Korean Ministry of Environment, Korea international trade association, United Nations Commodity Trade Statistics Database and from individual industry were collected and analyzed for materials flow analysis of neodymium. Demand of neodymium in the Republic of Korea for the year 2010 was 409.5 tons out of which the majority of neodymium, i.e., 68.41% was consumed by domestic electronics industry followed by medical appliances manufacturing (13.36%). The Republic Korea is one of the biggest consumer and leading exporter of these industrial products, absolutely depends on import of neodymium, as the country is lacking natural resources. The Republic of Korea has imported 325.9 tons of neodymium permanent magnet and 79.5 tons of neodymium containing equipment parts mainly for electronics, medical appliances, and heavy/light vehicles manufacturing industry. Out of which 95.4 tons of neodymium permanent magnet get exported as an intermediate product and 140.6 tons of neodymium in the form of consumable products get exported. Worldwide the neodymium is at the high end of supply chain critical metal because of increasing demand, scarcity and irreplaceable for technological application. To bring back the neodymium to supply stream the recycling of end of life neodymium-bearing waste can be a feasible option. Out of total domestic consumption, only 21.9 tons of neodymium have been collected and subsequently recycled. From material flow analysis, the requirement for an efficient recycling system and element-wise material flow management for these REEs in the Republic of Korea were realized and recommended. PMID:26210233

  12. Gauge anomalies, gravitational anomalies, and superstrings

    SciTech Connect

    Bardeen, W.A.

    1985-08-01

    The structure of gauge and gravitational anomalies will be reviewed. The impact of these anomalies on the construction, consistency, and application of the new superstring theories will be discussed. 25 refs.

  13. ANOMALY STRUCTURE OF SUPERGRAVITY AND ANOMALY CANCELLATION

    SciTech Connect

    Butter, Daniel; Gaillard, Mary K.

    2009-06-10

    We display the full anomaly structure of supergravity, including new D-term contributions to the conformal anomaly. This expression has the super-Weyl and chiral U(1){sub K} transformation properties that are required for implementation of the Green-Schwarz mechanism for anomaly cancellation. We outline the procedure for full anomaly cancellation. Our results have implications for effective supergravity theories from the weakly coupled heterotic string theory.

  14. The elliptic anomaly

    NASA Technical Reports Server (NTRS)

    Janin, G.; Bond, V. R.

    1980-01-01

    An independent variable different from the time for elliptic orbit integration is used. Such a time transformation provides an analytical step-size regulation along the orbit. An intermediate anomaly (an anomaly intermediate between the eccentric and the true anomaly) is suggested for optimum performances. A particular case of an intermediate anomaly (the elliptic anomaly) is defined, and its relation with the other anomalies is developed.

  15. Reconstruction of the West Pacific ENSO precipitation anomaly using the compound-specific hydrogen isotopic record of marine lake sediments of Palau

    NASA Astrophysics Data System (ADS)

    Smittenberg, R. H.; Sachs, J. P.; Dawson, M. N.

    2004-12-01

    There is still much uncertainty whether the El Niño Southern Oscillation (ENSO) will become stronger or more frequent in a warming global climate. A principal reason for this uncertainty stems from a glaring lack of paleoclimate data in the equatorial Pacific, which hampers model validation. To partly resolve this data deficiency, sediments of three marine anoxic lakes were cored in Palau, an island group that lies in the heart of the West Pacific Warm Pool. The lakes contain seawater that seeps through fissures in the surrounding karst, and they are permanently stratified due to fresh water input provided by the year-round wet climate (map 1970-2000 = 3.7m). During ENSO events, however, the islands suffer from drought. The surface water hydrogen isotopic compositions in the lakes are sensitive to the relative proportions of D-depleted rainwater and D-enriched seawater, and are therefore sensitive to ENSO events. The lake surface water H/D values are recorded by algal and bacterial biomarkers that are preserved well in the highly organic and anoxic sediments, which accumulate relatively fast (mean 1 mm/yr). Ongoing down core measurement will eventually result in a precipitation proxy record of the islands. To obtain endmember D/H values, a comprehensive set of water samples from sea, lakes and rain water was obtained, as well as suspended particulate matter. Higher plant biomarker D/H values derived from the jungle vegetation surrounding the lakes may render supporting climatic proxy data, being influenced by evapotranspiration. Some lakes are inhabited by millions of jellyfish (Mastigias) that live in symbiosis with zooxanthellae. The jellyfish of one of the investigated lakes disappeared completely after the last large ENSO event in 1998 (returning in 2000-01), and a correlation is suggested. To reconstruct the history of jellyfish occurrence, jellyfish and sedimentary lipids were extracted and compared. In addition to a possible ENSO proxy record, this

  16. Neodymium-YAG laser vitreolysis in sickle cell retinopathy

    SciTech Connect

    Hrisomalos, N.F.; Jampol, L.M.; Moriarty, B.J.; Serjeant, G.; Acheson, R.; Goldberg, M.F.

    1987-08-01

    Six patients with proliferative sickle cell retinopathy and vitreous bands were treated with the neodymium-YAG (Nd-YAG) laser to accomplish lysis of avascular traction bands or to clear the media in front of the macula. Transection of bands was possible in five of the six cases but in two of these the effect was only partial. Three cases were satisfactorily treated with the Nd-YAG laser application alone, two eventually required conventional vitreoretinal surgery, and one patient's condition stabilized despite failure of the treatment. Complications from the treatment occurred in three cases and included subretinal (choroidal) hemorrhage, preretinal hemorrhage, microperforation of a retinal vein, and focal areas of damage to the retinal pigment epithelium. Neodymium-YAG vitreolysis may be a useful modality in carefully selected patients with proliferative sickle cell retinopathy, but potentially sight-threatening complications may occur.

  17. Treatment of benign urethral strictures using a sapphire tipped neodymium:YAG laser.

    PubMed

    Smith, J A

    1989-11-01

    Sapphire tips increase the energy density and cutting effect of a neodymium:YAG laser. Sapphire tipped neodymium:YAG laser fibers were used to perform urethrotomy in 24 men with benign urethral strictures. The cutting effect was inadequate in 10 patients. Of the 24 patients 16 (67%) had a recurrent stricture within 1 year. Sapphire tipped neodymium:YAG laser fibers offer no apparent advantage over cold knife urethrotomy for treatment of benign urethral strictures. PMID:2810498

  18. Additive-pulse modelocking of non-cw neodymium lasers

    NASA Astrophysics Data System (ADS)

    Heinz, P.; Reuther, A.; Laubereau, A.

    1993-03-01

    Passive modelocking of several flash-lamp pumped neodymium lasers with electro-optic amplitude stabilization is demonstrated using a nonlinear Michelson interferometer. Improved performance is reported for the GSGG- YLF- and glass-laser as compared to the nonlinear absorber, with shorter pulse durations and smaller amplitude fluctuations, e.g. 5 μJ pulses for 460 ± 20 fs for Nd:glass. Evidence is obtained for multi-selfstability of the pulse energy.

  19. [Neodymium magnet injury causing nasal fracture: a case report].

    PubMed

    Aykan, Andaç; Güzey, Serbülent; Avşar, Sedat; Öztürk, Serdar

    2015-05-01

    In parallel with technological developments, small size but strong magnets are commonly used in modern devices. In terms of foreign body injuries, magnet injuries are quite rare. However, due to their unique characteristics, there are some difficulties in their management. The magnetic field generated by the magnet affects the surgical instruments and make treatment difficult. In this case report, a nasal injury due to neodymium magnet and our alternative approach for its management was reported. PMID:26033660

  20. Complexation of di-amides of dipicolinic acid with neodymium

    SciTech Connect

    Lapka, J.L.; Paulenova, A.

    2013-07-01

    Di-amides have undergone significant studies as possible ligands for use in the partitioning of trivalent minor actinides and lanthanides. The binding affinities of three isomeric ligands with neodymium in acetonitrile solution have been investigated. The stability constants of the metal-ligand complexes formed between different isomers of N,N'-diethyl-N,N'- ditolyl-di-picolinamide (EtTDPA) and trivalent neodymium in acetonitrile have been determined by spectrophotometric and calorimetric methods. Each isomer of EtTDPA has been found to be capable of forming three complexes with trivalent neodymium, Nd(EtTDPA), Nd(EtTDPA){sub 2}, and Nd(EtTDPA){sub 3}. Values from spectrophotometric and calorimetric titrations are within reasonable agreement with each other. The order of stability constants for each metal:ligand complex decreases in the order Et(m)TDPA > Et(p)TDPA > Et(o)TDPA. The obtained values are comparable to other di-amidic ligands obtained under similar system conditions and mirror previously obtained solvent extraction data for EtTDPA at low ionic strengths. (authors.

  1. Samarium-neodymium evolution of meteorites

    NASA Technical Reports Server (NTRS)

    Prinzhofer, A.; Papanastassiou, D. A.; Wasserburg, G. J.

    1992-01-01

    The feasibility of using Sm-147 and Sm-146 as chronometers was investigated using Sm-Nd data obtained on three meteorites: Ibitira, Morristown, and Acapulco. The results of isotope analyses demonstrate the presence of in situ decay of short-lived Sm-146 in these meteorites with initial abundances of Sm-146/Sm-144 between 0.009 and 0.007 in different meteorites. Precisely defined Sm-147/Nd-143 internal isochrons were obtained yielding ages equal to 4.46 +/-0.02 AE for Ibitira, 4.47 +/-0.02 AE for Morristown, and 4.60 +/-0.03 AE for Acapulco. However, detailed examination of the coupled Sm-147/Nd-143 and Sm-146/Nd-142 parent-daughter systematics and of initial Nd-143/Nd-144 values indicated the presence of inconsistencies in the data in spite of the precise isochrons, indicating the need for care in the interpretation of the parent-daughter systematics, even when they appear well behaved.

  2. High resolution neodymium characterization along the Mediterranean Sea margins: implications for ɛNd modeling.

    NASA Astrophysics Data System (ADS)

    Ayache, Mohamed; Dutay, Jean-claude; Arsouze, Thomas; Jeandel, Catherine; Revillon, Sidonie

    2016-04-01

    An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (ɛNd) was realized in order to establish a new database and a map (using a high resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done, in order to improve this dataset in key areas (e.g Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lions, (ɛNd values -11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high resolution regional oceanic model (1/12° of horizontal resolution), ɛNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides the opportunity to study in more details the processes governing the Nd isotope distribution in the marine environment. This work highlights that a significant interannual variability of ɛNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in Nd IC at intermediate depths that could be noticeable in the Western part of the basin. This highlights that the temporal and geographical variations of ɛNd could represent an interesting insight of Nd as a quasi-conservative tracer of water masses in the Mediterranean Sea, in particular in the context of paleo-oceanographic applications, i.e. to explore if EMT-type signatures occurred in the past (Roether et al., 2014, Gacic et al., 2011).

  3. Constraints on the neodymium (Nd) oceanic cycle in the Mediterranean Sea using a high resolution coupled model

    NASA Astrophysics Data System (ADS)

    Ayache, Mohamed; Jeandel, Catherine; Dutay, Jean-claude; Arsouze, Thomas

    2015-04-01

    Neodymium isotopic composition (Nd IC) is a tracer of oceanic circulation and lithogenic inputs to the ocean. An extensive compilation of published Nd isotopic values was realized in order to establish a database and a map of ɛNd and Nd concentrations characterizing all the Mediterranean margins. This was built based on different kinds of samples: riverine solid discharge deposited on the shelf, sedimentary material collected along the margins and geological material above or close to an oceanic margin (following Jeandel et al., 2007). The margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lions (Nd IC values between -11.5 and -10), to radiogenic values around the Aegean and the Levantine sub-basins (Nd IC up to +6). Such West-East variation was also observed in the seawater data, which are becoming more radiogenic along the eastward circulation in the Mediterranean Sea (Tachikawa et al., 2004). The Nd budget proposed by these authors raised the hypothesis that the exchange of Nd along the margins could play a significant role in driving the oceanic distribution of this tracer. On a more global scale, it was further demonstrated and modelled that dissolved/particulate exchanges between continental margin sediments and open ocean (termed boundary exchange, BE), could be the dominant source-sink terms that determine the distribution of neodymium isotopes in the global ocean (Lacan and Jeandel, 2005a, Arsouze et al 2009). But this global scale study with it low-resolution configuration ORCA2 (2° of horizontal resolution) could not resolve many local and regional-scale features Our purpose is to test this hypothesis for the first time in the Mediterranean Sea by using a high resolution regional coupled model (1/12° of horizontal resolution). In a first approach we considered that boundary exchange is the only term governing Nd distribution in the Mediterranean Sea (other sources have been neglected). This aimed to validate the "Boundary

  4. Effect of transscleral neodymium: YAG cyclophotocoagulation on intraocular lenses

    SciTech Connect

    Blomquist, P.H.; Gross, R.L.; Koch, D.D. )

    1990-03-01

    A neodymium: YAG laser operating in the thermal mode was used to irradiate isolated intraocular lenses (IOLs) and to perform transscleral cyclophotocoagulation on pseudophakic autopsy eyes to investigate the potential damage to IOL haptics such irradiation may cause. In the isolated IOLs, 70 mJ of energy deformed and partially melted both polymethylmethacrylate (PMMA) and polypropylene haptics. One of the capsular-fixated PC-IOL haptics in an autopsy eye partially melted when irradiated with the maximum energy level (8.8 J), with the aiming beam focused 1 mm posterior to the limbus and maximal posterior focus offset.

  5. Local immunity in treating skin melanoma by neodymium pulsed laser

    NASA Astrophysics Data System (ADS)

    Moskalik, Konstantin G.

    1997-06-01

    The number and correlation of skin stroma cells was studied on mice C57B1 with the subcutaneously transplanted melanoma B16 which was exposed to neodymium pulsed laser radiation. Within 1-5 days after the exposure the total number of the free skin stroma cells was found to increase in the periphery from the radiation epicenter and the number of lymphocytes, macrophages and leucocytes tended to grow. Lymphoid infiltration was also revealed in the preparations of the epithelized wound and cicatrix on the skin melanoma sites in the patients who had undergone pulsed laser radiation therapy.

  6. Urethral strictures treatment with neodymium:YAG laser.

    PubMed

    Silber, N

    1992-04-01

    A total of 14 patients with stricture of the urethra underwent treatment with Nd:YAG (neodymium:YAG) laser irradiation. A new 800-micron hemispherical optical quartz fiber was used in contact technique to produce linear incisions in the scarred tissue. Within 11.2 months, median of follow up, there was improvement in the obstructive voiding symptoms in all the patients. One patient who still had mild stricture in the first follow-up cystoscopy was managed successfully with second treatment. Endoscopic application of laser energy in the contact mode facilitates the immediate vaporization and disintegration of the fibrous area and secondary reepithelization of the urethra without scarring. PMID:10171965

  7. Lymphatic Anomalies Registry

    ClinicalTrials.gov

    2016-07-26

    Lymphatic Malformation; Generalized Lymphatic Anomaly (GLA); Central Conducting Lymphatic Anomaly; CLOVES Syndrome; Gorham-Stout Disease ("Disappearing Bone Disease"); Blue Rubber Bleb Nevus Syndrome; Kaposiform Lymphangiomatosis; Kaposiform Hemangioendothelioma/Tufted Angioma; Klippel-Trenaunay Syndrome; Lymphangiomatosis

  8. Incorporation of Cerium and Neodymium in Uranyl Phases

    SciTech Connect

    Kim, C W.; Wronkiewicz, David J.; Finch, R J.; Buck, Edgar C.

    2006-07-15

    The potential for incorporating rare earth elements (REE) into/onto crystalline compounds has been evaluated by precipitating uranyl phases from aqueous solutions containing either cerium or neodymium. These REEs serve both as monitors for evaluating the potential repository behavior of REE radionuclides, and as surrogate elements for actinides (e.g., Ce4 and Nd3 for Pu4 and Am3, respectively). The present experiments examined the behavior of REE in the presence of ianthinite Formula Not Shown, becquerelite (Ca(UO2)6O4(OH)6(H2O)8), and other uranyl hydroxide compounds commonly noted as alteration products during the corrosion of UO2, spent nuclear fuel, and naturally occurring uraninite. The results of these experiments demonstrate that significant quantities of both cerium (Kd=1020) and neodymium (Kd=840) are incorporated within the uranium alteration phases and suggest that ionic substitution and/or adsorption to the uranyl phases can play a key role in the limiting the mobility of REE (and by analogy, actinide elements) in a nuclear waste repository.

  9. Microscale neodymium distribution in sedimentary planktonic foraminiferal tests and associated mineral phases

    NASA Astrophysics Data System (ADS)

    Tachikawa, Kazuyo; Toyofuku, Takashi; Basile-Doelsch, Isabelle; Delhaye, Thomas

    2013-01-01

    Neodymium isotopic ratios recorded in calcareous foraminiferal tests (shells) and associated authigenic minerals were used to trace past water masses, although the origin of preserved Nd signals is still a matter of debate. We determined, for the first time, the microscale Nd distribution in two planktonic foraminifera species (Globigerinoides ruber and Neogloboquadrina dutertrei) and coexisting authigenic minerals from two selected time slices (15.6 and 129 kyr) of a marine sediment core in the Panama Basin. Elemental mapping of Nd, Ca, Fe, Mn, and Si was performed using NanoSIMS ion probe and electron probe microanalysis (EPMA) on uncleaned tests together with scanning electron microscopy (SEM) imagery. EPMA and SEM images revealed the presence of Fe-rich framboidal minerals inside test pores and inner chambers, particularly in the old samples. The young sample presented Fe- and Mn-rich patches on the inner test wall. The Nd intensity in Fe-Mn-rich patches and in some framboids was much higher than in foraminiferal calcite, where the Nd distribution was randomly heterogeneous with no systematic features such as an ontogenic Nd-rich layer or species-specific differences. The relationship between Nd, Fe, and Mn confirmed a significant role of Fe-Mn oxides as a Nd carrier. The high Nd enrichment in some framboids could be explained by Nd adsorption onto oxidized surface of Fe sulfides particles rather than direct incorporation. Since the authigenic precipitates are major Nd carrier phases, the Nd isotopic signals in sedimentary foraminiferal tests likely reflect bottom/pore water values rather than surface water ones.

  10. 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.

  11. Recycling potential of neodymium: the case of computer hard disk drives.

    PubMed

    Sprecher, Benjamin; Kleijn, Rene; Kramer, Gert Jan

    2014-08-19

    Neodymium, one of the more critically scarce rare earth metals, is often used in sustainable technologies. In this study, we investigate the potential contribution of neodymium recycling to reducing scarcity in supply, with a case study on computer hard disk drives (HDDs). We first review the literature on neodymium production and recycling potential. From this review, we find that recycling of computer HDDs is currently the most feasible pathway toward large-scale recycling of neodymium, even though HDDs do not represent the largest application of neodymium. We then use a combination of dynamic modeling and empirical experiments to conclude that within the application of NdFeB magnets for HDDs, the potential for loop-closing is significant: up to 57% in 2017. However, compared to the total NdFeB production capacity, the recovery potential from HDDs is relatively small (in the 1-3% range). The distributed nature of neodymium poses a significant challenge for recycling of neodymium. PMID:25029356

  12. Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

    DOEpatents

    Keller, Rudolf; Larimer, Kirk T.

    1998-01-01

    A method of producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage.

  13. Nd-isotopic evidence for the origin of the Sudbury complex by meteoritic impact

    NASA Technical Reports Server (NTRS)

    Faggart, B. E.; Basu, A. R.; Tatsumoto, M.

    1985-01-01

    A Neodymium isotopic investigation was undertaken in order to determine the possibility that the Sudbury geological structure in Ontario, Canada was formed by meteoritic impact. Conclusive evidence points to the melting of crustal rocks by way of meteoritic impact in the forming of the Sudbury structure.

  14. Implications of isotope data for the origin of the moon

    NASA Technical Reports Server (NTRS)

    Turcotte, D. L.; Kellogg, L. H.

    1986-01-01

    Lunar isotope data are studied in terms of lunar reservoir models. An analysis is performed to determine how the samarium-neodymium and rubidium-strontium systems evolve in terms of a two-reservoir model. Isotope data from lunar rocks show much more variability than similar data from terrestrial rocks. The midocean ridge basalts yield consistent isotope signatures on a worldwide basis suggesting that vigorous mantle convection has mixed and homogeneized the upper mantle beneath the lithosphere plates. The variability of the lunar data is taken as evidence for distinct source regions which in effect support a relatively cool origin of the moon.

  15. A new contact neodymium: YAG laser for cyclophotocoagulation

    SciTech Connect

    Iwach, A.G.; Drake, M.V.; Hoskins, H.D. Jr.; Schuster, B.L.; Vassiliadis, A.; Crawford, J.B.; Hennings, D.R. )

    1991-06-01

    A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.

  16. Segmental irradiation of the bladder with neodymium YAG laser irradiation

    SciTech Connect

    McPhee, M.S.; Mador, D.R.; Tulip, J.; Ritchie, B.; Moore, R.; Lakey, W.H.

    1982-11-01

    The Neodymium YAG laser energy source can be readily adapted for cystoscopic use by some simple modifications of existing urologic equipment. Both the fiberoptic resectoscope and a deflecting cystourethroscope have been adapted for this purpose. Fixation of the fiber tip 1 cm. from the target and use of a divergent beam of 36 degrees allows the delivery of standardized dosage to a relatively large bladder tissue volume. Animal experiments involving 35 mongrel dogs established that repetitive overlapping doses of 200 joules ech can successfully treat a large area of bladder resulting in a full thickness bladder wall injury. This technique has been used in 4 high risk patients with infiltrating bladder cancer without adverse sequelae. The ability to reliably produce a full thickness lesion may give this modality a therapeutic advantage over conventional cautery techniques especially for the treatment of residual infiltrative carcinoma.

  17. α-uranium phase in compressed neodymium metal

    NASA Astrophysics Data System (ADS)

    Chesnut, Gary N.; Vohra, Yogesh K.

    2000-02-01

    The light rare-earth metal, neodymium, has been studied up to 155 GPa in a diamond-anvil cell using energy dispersive x-ray diffraction with a synchrotron source. The pressures were calibrated using copper as an internal x-ray pressure standard. A phase transformation from a monoclinic phase (C2/m, 4 atoms/cell) to an orthorhombic α-U phase (Cmcm, 4 atoms/cell) was observed at 113+/-6 GPa without any observable volume collapse. The observation of α-U phase in Nd and, previously, in cerium and praseodymium clearly establishes this phase in light rare-earth metals. Our equation of state measurements suggest that delocalization of the f shell in Nd occurs without any volume collapse unlike Ce and Pr.

  18. [Kimmerle's anomaly and stroke].

    PubMed

    Barsukov, S F; Antonov, G I

    1992-10-01

    The anomaly of cranio-vertebral area can frequently be the reason of acute cerebrovascular disorders in vertebro-basilar field. The frequent C1 pathology in the Kimmerle's anomaly. The anatomic studies has shown that 30% of people had this type of anomaly. This pathology can lead to severe vascular diseases of cerebrum because of the squeezing effect upon vertebral arteries in the zone of osteal ponticulus of the rear arch of atlas. PMID:1481402

  19. Taussig-Bing Anomaly

    PubMed Central

    Konstantinov, Igor E.

    2009-01-01

    Taussig-Bing anomaly is a rare congenital heart malformation that was first described in 1949 by Helen B. Taussig (1898–1986) and Richard J. Bing (1909–). Although substantial improvement has since been achieved in surgical results of the repair of the anomaly, management of the Taussig-Bing anomaly remains challenging. A history of the original description of the anomaly, the life stories of the individuals who first described it, and the current outcomes of its surgical management are reviewed herein. PMID:20069085

  20. Microscale Demonstration of the Paramagnetism of Liquid Oxygen with a Neodymium Magnet

    ERIC Educational Resources Information Center

    Mattson, Bruce

    2007-01-01

    A microscale classroom demonstration of the paramagnetic behavior of various samples of liquid oxygen with neodymium magnet is being presented. The experiment should be done with extreme caution, as liquid oxygen reacts violently with organic matters.

  1. Description of the traction characteristics of the neodymium compensators of the automatic vibration isolations

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.; Panchenko, Y. V.; Gurov, M. G.

    2016-04-01

    In this paper the method of calculation of neodymium magnets was presented. The calculation of the neodymium magnets characteristics and stiffness correctors of the vibration isolator according to the requirements for vibration isolation devices with stiffness compensators was performed. This research has been performed with the support of the President scholarship for young scientists, order No. 184 of Ministry of education and science of the Russian Federation of the 10th of March 2015.

  2. Competing Orders and Anomalies.

    PubMed

    Moon, Eun-Gook

    2016-01-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation "laws" could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the 't Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

  3. Competing Orders and Anomalies

    NASA Astrophysics Data System (ADS)

    Moon, Eun-Gook

    2016-08-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed.

  4. Competing Orders and Anomalies

    PubMed Central

    Moon, Eun-Gook

    2016-01-01

    A conservation law is one of the most fundamental properties in nature, but a certain class of conservation “laws” could be spoiled by intrinsic quantum mechanical effects, so-called quantum anomalies. Profound properties of the anomalies have deepened our understanding in quantum many body systems. Here, we investigate quantum anomaly effects in quantum phase transitions between competing orders and striking consequences of their presence. We explicitly calculate topological nature of anomalies of non-linear sigma models (NLSMs) with the Wess-Zumino-Witten (WZW) terms. The non-perturbative nature is directly related with the ’t Hooft anomaly matching condition: anomalies are conserved in renormalization group flow. By applying the matching condition, we show massless excitations are enforced by the anomalies in a whole phase diagram in sharp contrast to the case of the Landau-Ginzburg-Wilson theory which only has massive excitations in symmetric phases. Furthermore, we find non-perturbative criteria to characterize quantum phase transitions between competing orders. For example, in 4D, we show the two competing order parameter theories, CP(1) and the NLSM with WZW, describe different universality class. Physical realizations and experimental implication of the anomalies are also discussed. PMID:27499184

  5. Isotopic microanalysis of returned comet nucleus samples

    NASA Technical Reports Server (NTRS)

    Zinner, Ernst

    1989-01-01

    If isotopic measurements of interplanetary dust particles (IDPs) and primitive meteorites can serve as a guide to the isotopic analysis of returned comet nucleus material, an essential requirement will be the capability for microanalysis. The reason is that in both types of extraterrestrial samples large isotopic heterogeneities on a small spatial scale have become apparent once it was possible to measure isotopes in small samples. In the discovery of large isotopic anomalies the ion microprobe has played a significant role because of its high spatial resolution for isotopic ratio measurements. The largest isotopic anomalies in C, N, O, Mg, Si, Ca and Ti found to date were measured by ion microprobe mass spectrometry. The most striking examples are D/H measurements in IDPs and isotopic measurements of C, N and Si in SiC from the CM chondrites Murray and Murchison.

  6. Dating scheelite stages: A strontium, neodymium, lead approach from the Felbertal tungsten deposit, Central Alps, Austria

    NASA Astrophysics Data System (ADS)

    Eichhorn, Roland; Höll, Rudolf; Jagout, Emil; Schärer, Urs

    1997-12-01

    New Sm-Nd, Rb-Sr, and Pb-Pb isotope data of scheelites and their host rocks from the Felbertal scheelite deposit (Central Tauern Window, Eastern Alps, Austria) are presented. The oldest stage 1 scheelites are rarely preserved. They plot together with recrystallized stage 2 scheelite porphyroblasts on a Sm-Nd isochron of 581 ± 105 Ma. This Sm-Nd age is regarded as the time of the primary tungsten mineralization. Our interpretation is enhanced by a (within error limits) similar age of 517 ± 114 Ma derived from a 207Pb/ 206Pb scheelite isochron and a date of 517 ± 130 Ma obtained from two co-genetic relics (a clinopyroxene and a tschermakitic amphibole) within a metapyroxenite. The stage 2 scheelite blastesis was possibly triggered by an still unassured Ordovician "Caledonian" metamorphism and further promoted by a Carboniferous granitoid intrusion and a Variscan metamorphism without an isotopic reset. Both yellowish-fluorescent, Mo-bearing stage 1 and stage 2 scheelites were formed under oxidizing, alkaline conditions, which obviously did not promote REE fractionation and did not disturb the original Sm-Nd isotopic system. This evidently was not the case during younger remobilizations in Late Variscan and Alpine metamorphic times when stage 3 (319 ± 34 Ma) and stage 4 (29 ± 17 Ma) scheelites formed. Both stages consist of bluish-fluorescent, Mopoor to Mo-free scheelites that reveal significant REE depletion and fractionation, probably due to repeated corrosion and re-precipitation under more reducing neutral to slightly acidic conditions. The source and mechanism of deposition of the primary tungsten mineralization are deduced from five facts: (1) the radiogenic strontium isotopic data of stage 1 scheelites ( 87Sr/86Sr = 0.726-0.730 ) occurring together with normal crustal neodymium isotopic compositions ( ɛCHURt + 1 = -3.8 to -7.3), (2) unusually high U concentrations up to 74 ppm in stage 1 scheelites, (3) a sudden 87Sr increase between the formation of

  7. Müllerian anomalies.

    PubMed

    Gell, Jennifer S

    2003-11-01

    The reproductive organs in both males and females consist of gonads, internal ductal structures, and external genitalia. Normal sexual differentiation is dependent on the genetic sex determined by the presence or absence of the Y chromosome at fertilization. Testes develop under the influence of the Y chromosome and ovaries develop when no Y chromosome is present. In the absence of testes and their normal hormonal products, sexual differentiation proceeds along the female pathway, resulting in a normal female phenotype. Anatomic gynecologic anomalies occur when there is failure of normal embryologic ductal development. These anomalies include congenital absence of the vagina as well as defects in lateral and vertical fusion of the Müllerian ducts. Treatment of müllerian anomalies begins with the correct identification of the anomaly and an understanding of the embryologic origin. This includes evaluation for other associated anomalies such as renal or skeletal abnormalities. After correct identification, treatment options include nonsurgical as well as surgical intervention. This chapter serves to review the embryology and development of the reproductive system and to describe common genital tract anomalies. Details of surgical or nonsurgical correction of these anomalies are presented. PMID:14724770

  8. Behavioral economics without anomalies.

    PubMed Central

    Rachlin, H

    1995-01-01

    Behavioral economics is often conceived as the study of anomalies superimposed on a rational system. As research has progressed, anomalies have multiplied until little is left of rationality. Another conception of behavioral economics is based on the axiom that value is always maximized. It incorporates so-called anomalies either as conflicts between temporal patterns of behavior and the individual acts comprising those patterns or as outcomes of nonexponential time discounting. This second conception of behavioral economics is both empirically based and internally consistent. PMID:8551195

  9. Extraction of seawater-derived neodymium from different phases of deep sea sediments by selective leaching

    NASA Astrophysics Data System (ADS)

    Blaser, P.; Lippold, J. A.; Frank, N.; Gutjahr, M.; Böhm, E.

    2014-12-01

    In order to deduce reliable information about the interaction of the oceans with the climate system as a whole in the past, the reconstruction of water mass circulation is crucial. The analysis of seawater-derived neodymium isotopes (143Nd/144Nd, expressed as ɛNd) in marine sediments provides a unique proxy for deep water provenance in particular in the Atlantic [1]. The ɛNd signature and thus the mixing proportion of the local bottom water masses is archived in authigenic phases in the sediment. Obtaining seawater ɛNd from authigenic accretions bound to foraminiferal tests has lately become the preferred since most reliable method [2]. Attempts have also been made to extract the Nd-rich authigenic metal fraction by leaching it off the bulk sediment and thereby use this proxy with less effort, in the highest possible resolution and in sediments where foraminifera are not sufficiently present. However, often other sedimentary components are also leached in the process and contaminate the extracted Nd [3,4]. In this project several core-top and older sediments across the Atlantic have been leached in ten consecutive steps with either dilute buffered acetic acid or an acid-reductive solution. The leachates were analysed on their elemental and Nd isotope compositions, as well as rare earth element (REE) distributions. By graduating the total leaching procedure into smaller stages the results display which processes take place in the course of sediment leaching in the laboratory and which components of the sediment are most reactive. Thus, they help to better evaluate the quality of sediment leaches for ɛNd analysis. Clearly, organic calcite acts as a fast reacting buffer and at the point where its amount is sufficiently reduced the leaching of other components commences and the Nd concentration peaks. Corruption of the extracted ɛNd signal by non-authigenic sources in many cases occured early in the leaching sequence, indicating that only very cautious leaching

  10. Effect Of Neodymium Substitution In Structural Characteristics Of Magnesium Ferrite

    SciTech Connect

    Thankachan, Smitha; Binu, P. J.; Xavier, Sheena; Mohammed, E. M.

    2011-10-20

    The effect of Nd{sup 3+} substitution on the structural properties of Magnesium ferrite was studied in the series MgNd{sub x}Fe{sub 2-x}O{sub 4}, where x = 0 to 0.3 in steps of 0.05. The series was prepared by sol-gel technique which is one of the novel technique to prepare nanosized samples. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till x = 0.2. From x0 = .25, a secondary phase of iron neodymium oxide appears along with the spinel phase. Particle size calculation shows the prepared samples are in the 9nm to 11 nm regime. Lattice parameter was found to increase with concentration of Nd. XRD and FTIR analysis confirmed spinel structure of the prepared samples. XRF result shows the expected composition of prepared samples. The frequency dependence of the dielectric constant in the range 100 Hz--120MHz was also studied

  11. Power neodymium-glass amplifier of a repetitively pulsed laser

    SciTech Connect

    Vinogradov, Aleksandr V; Gaganov, V E; Garanin, Sergey G; Zhidkov, N V; Krotov, V A; Martynenko, S P; Pozdnyakov, E V; Solomatin, I I

    2011-11-30

    A neodymium-glass diode-pumped amplifier with a zigzag laser beam propagation through the active medium was elaborated; the amplifier is intended for operation in a repetitively pulsed laser. An amplifier unit with an aperture of 20 Multiplication-Sign 25 mm and a {approx}40-cm long active medium was put to a test. The energy of pump radiation amounts to 140 J at a wavelength of 806 nm for a pump duration of 550 {mu}s. The energy parameters of the amplifier were experimentally determined: the small-signal gain per pass {approx}3.2, the linear gain {approx}0.031 cm{sup -1} with a nonuniformity of its distribution over the aperture within 15%, the stored energy of 0.16 - 0.21 J cm{sup -3}. The wavefront distortions in the zigzag laser-beam propagation through the active element of the amplifier did not exceed 0.4{lambda} ({lambda} = 0.63 {mu}m is the probing radiation wavelength).

  12. Laser self-doubling in neodymium yttrium aluminum borate

    NASA Astrophysics Data System (ADS)

    Lu, Bao-Sheng; Wang, Jun; Pan, Heng-Fu; Jiang, Min-Hua; Liu, En-Quan

    1989-12-01

    The nonlinear effects of neodymium yttrium aluminum borate Nd(x)Y(1-x)Al3(BO3)4 (NYAB) crystal powder samples with different Nd(3+) mole percentages are reported. The optimum X values for the growth of NYAB crystals with high optical homogeneity has been determined. The performance of laser self-frequency doubling from 1.06-0.53 micron has been realized, for the first time, in a 5 x 3 x 3 cu mm NYAB crystal. The Nd(3+) ions in crystal show weak absorption at 0.53 micron. The threshold energy is measured to be less than 2 mJ; the output energy of green light at 0.53 micron is more than 5 mJ and the conversion efficiency is over 10 percent. The experiments show that the performance is improved if the optical path length is increased and the cavity design is improved. The refractive indices n(0) and n(e) of the crystal have been measured by the prism method at different wavelengths. The phase-matching angles of Types I and II have been obtained by solving equations for the phase-matching angles. The results are in good agreement with the experimental values. The nonlinear coefficient d(11) of the NYAB crystal has been measured to be 4 x 10 to the-9th esu.

  13. LASERS: Efficient neodymium-doped gadolinium gallium garnet crystal laser

    NASA Astrophysics Data System (ADS)

    Doroshenko, Maxim E.; Osiko, Vyacheslav V.; Sigachev, V. B.; Timoshechkin, M. I.

    1991-07-01

    An investigation was made of the stimulated emission parameters of a laser utilizing a gadolinium gallium garnet crystal doped with neodymium ions (YAG:Nd) at the 1.062 μm wavelength. The free-running efficiency was the highest so far achieved for flashlamp-pumped lasers utilizing unsensitized garnets. For an active element 8 mm in diameter and 120 mm long the absolute efficiency was 5.4% and the differential efficiency was 5.9%. The average free-running power was 170 W. A comparison was made of the optical powers of thermal lenses in cylindrical GGG:Nd and YAG:Nd active elements and this was found to be 2.4 times higher for a GGG:Nd crystal at the same pump powers. It was shown that by using traditional methods of compensating for the thermal lens in cylindrical active elements, it is possible to develop pulsed GGG:Nd crystal lasers having an average output power higher than 100 W, an efficiency of ~ 4%, and an angular divergence of less than 10 mrad.

  14. Dielectric and impedance spectroscopic studies of neodymium gallate

    NASA Astrophysics Data System (ADS)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T. P.

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO3 (NGO), synthesized by the sol-gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  15. Laboratory and clinical experience with neodymium:YAG laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kabalin, John N.

    1996-05-01

    Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

  16. Dual diaphragmatic anomalies.

    PubMed

    Padmanabhan, Arjun; Thomas, Abin Varghese

    2016-01-01

    Although diaphragmatic anomalies such as an eventration and hiatus hernia are commonly encountered in incidental chest X-ray imaging, the presence of concomitant multiple anomalies is extremely rare. This is all the more true in adults. Herein, we present the case of a 75-year-old female, while undergoing a routine chest X-ray imaging, was found to have eventration of right hemidiaphragm along with a hiatus hernia as well. PMID:27625457

  17. Dual diaphragmatic anomalies

    PubMed Central

    Padmanabhan, Arjun; Thomas, Abin Varghese

    2016-01-01

    Although diaphragmatic anomalies such as an eventration and hiatus hernia are commonly encountered in incidental chest X-ray imaging, the presence of concomitant multiple anomalies is extremely rare. This is all the more true in adults. Herein, we present the case of a 75-year-old female, while undergoing a routine chest X-ray imaging, was found to have eventration of right hemidiaphragm along with a hiatus hernia as well.

  18. Anomalies and entanglement entropy

    NASA Astrophysics Data System (ADS)

    Nishioka, Tatsuma; Yarom, Amos

    2016-03-01

    We initiate a systematic study of entanglement and Rényi entropies in the presence of gauge and gravitational anomalies in even-dimensional quantum field theories. We argue that the mixed and gravitational anomalies are sensitive to boosts and obtain a closed form expression for their behavior under such transformations. Explicit constructions exhibiting the dependence of entanglement entropy on boosts is provided for theories on spacetimes with non-trivial magnetic fluxes and (or) non-vanishing Pontryagin classes.

  19. On isostatic geoid anomalies

    NASA Technical Reports Server (NTRS)

    Haxby, W. F.; Turcotte, D. L.

    1978-01-01

    In regions of slowly varying lateral density changes, the gravity and geoid anomalies may be expressed as power series expansions in topography. Geoid anomalies in isostatically compensated regions can be directly related to the local dipole moment of the density-depth distribution. This relationship is used to obtain theoretical geoid anomalies for different models of isostatic compensation. The classical Pratt and Airy models give geoid height-elevation relationships differing in functional form but predicting geoid anomalies of comparable magnitude. The thermal cooling model explaining ocean floor subsidence away from mid-ocean ridges predicts a linear age-geoid height relationship of 0.16 m/m.y. Geos 3 altimetry profiles were examined to test these theoretical relationships. A profile over the mid-Atlantic ridge is closely matched by the geoid curve derived from the thermal cooling model. The observed geoid anomaly over the Atlantic margin of North America can be explained by Airy compensation. The relation between geoid anomaly and bathymetry across the Bermuda Swell is consistent with Pratt compensation with a 100-km depth of compensation.

  20. Electrolytic production of neodymium metal from a molten chloride electrolyte. Rept. of Investigations/1991

    SciTech Connect

    Chambers, M.F.; Murphy, J.E.

    1991-01-01

    Electrowinning of neodymium metal was accomplished by using a molten-metal cathode at 650 C and an electrolyte of 50 mol pct neodymium chloride-50 mol pct potassium chloride. The molten-metal cathodes were alloys of magnesium and zinc or magnesium and cadmium. Current efficiencies were 90 pct with a Mg/Zn cathode and 80 pct with a Mg-Cd cathode. The Mg-Cd cathode was easily separated from the electrolyte. In contrast, the Mg-Zn cathode tended to mix with the electrolyte, making separation difficult. The cathode metals were separated from the neodymium by distillation at 1,100 C under a vacuum of 10 to the -3rd power torr. Neodymium metal of 99.9+ purity was recovered from the Mg-Cd alloy cathode after 30 min distillation time. The neodymium recovered from the Mg-Zn system contained almost 2 pct Zn after vacuum distillation. Continuous operation using the Mg-Cd alloy cathode was demonstrated.

  1. A multi-isotopic and trace element investigation of the Cretaceous-Tertiary boundary layer at Stevns Klint, Denmark - inferences for the origin and nature of siderophile and lithophile element geochemical anomalies

    NASA Astrophysics Data System (ADS)

    Frei, Robert; Frei, Karin M.

    2002-10-01

    Os, Sr, Nd and Pb isotope data were collected from a profile across the Cretaceous-Tertiary (K-T) boundary layer at Stevns Klint, Denmark. ɛNd [ T=65 Ma] values from within the boundary layer (Fish Clay) are lower by ˜1 ɛ unit than those of the underlying Maastrichtian limestone and the overlying Danian chalk sequences. Systematic profile-upward changes of Pb, Sr and Os isotopic compositions and concentrations in the boundary layer cannot be accounted for by in situ growth of daughter products since the sedimentation of the Fish Clay. While Os, Nd and Pb isotopes indicate the admixing of less radiogenic components to the Fish Clay, Sr isotopes show elevated radiogenic values in the boundary layer, relative to the carbonate sequences beneath and above it. The sudden change in lithophile (e.g., Sr, Pb and Nd) isotope compositions at the base of the Fish Clay and profile-upward trends of 87Sr/ 86Sr and 206Pb/ 204Pb ratios towards those of the overlying Danian chalk are interpreted to reflect recovery from enhanced, acid rain-induced continental (local?) weathering input to the seawater. However, a continental crustal source is invalid for the siderophile element Os. In the light of evidence from chromium isotopes for a cosmic origin of the platinum group elements (PGEs) and certain moderately siderophile elements (Cr, Ni, Co, V) in K-T boundary sediments, including Stevns Klint [Shukolyukov and Lugmair, Science 282 (1998) 927-929], and supported by the finding of projectile debris [Bauluz et al., Earth Planet. Sci. Lett. 182 (2000) 127-136] and the occurrence of abundant Ni-rich spinel at many K-T sites [Robin et al., Nature 363 (1993) 615-617; Kyte, Nature 396 (1998) 237-239], we favor to explain the sudden drop of 187Os/ 188Os ratios from 0.210 to 0.160 at the K-T boundary to derive from global fall-out of extraterrestrial matter. The present 186Os/ 188Os ratio of 0.119836±0.000004 measured in the basal layer of the Fish Clay is within the uncertainty a

  2. Reactivity of neodymium carriers in deep sea sediments: Implications for boundary exchange and paleoceanography

    NASA Astrophysics Data System (ADS)

    Wilson, David J.; Piotrowski, Alexander M.; Galy, Albert; Clegg, Josephine A.

    2013-05-01

    The dissolved neodymium (Nd) isotopic distribution in the deep oceans is determined by continental weathering inputs, water mass advection, and boundary exchange between particulate and dissolved fractions. Reconstructions of past Nd isotopic variability may therefore provide evidence on temporal changes in continental weathering inputs and/or ocean circulation patterns over a range of timescales. However, such an approach is limited by uncertainty in the mechanisms and importance of the boundary exchange process, and the challenge in reliably recovering past seawater Nd isotopic composition (ɛNd) from deep sea sediments. This study addresses these questions by investigating the processes involved in particulate-solution interactions and their impact on Nd isotopes. A better understanding of boundary exchange also has wider implications for the oceanic cycling and budgets of other particle-reactive elements. Sequential acid-reductive leaching experiments at pH ˜2-5 on deep sea sediments from the western Indian Ocean enable us to investigate natural boundary exchange processes over a timescale appropriate to laboratory experiments. We provide evidence that both the dissolution of solid phases and exchange processes influence the ɛNd of leachates, which suggests that both processes may contribute to boundary exchange. We use major element and rare earth element (REE) data to investigate the pools of Nd that are accessed and demonstrate that sediment leachate ɛNd values cannot always be explained by admixture between an authigenic component and the bulk detrital component. For example, in core WIND 24B, acid-reductive leaching generates ɛNd values between -11 and -6 as a function of solution/solid ratios and leaching times, whereas the authigenic components have ɛNd ≈ -11 and the bulk detrital component has ɛNd ≈ -15. We infer that leaching in the Mascarene Basin accesses authigenic components and a minor radiogenic volcanic component that is more reactive

  3. Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

    DOEpatents

    Keller, R.; Larimer, K.T.

    1998-09-22

    A method is described for producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage. 4 figs.

  4. Electrowinning of neodymium from a molten oxide-fluoride electrolyte. Report of investigations/1994

    SciTech Connect

    Dysinger, D.K.; Murphy, J.E.

    1994-01-01

    Neodymium metal of 99.8 percent purity was prepared by electrolysis of Nd2O3 salts dissolved in a molten fluoride electrolyte. The metal was electrowon in a molten state at current efficiencies of 50 to 60 percent. Oxygen and carbon were the major impurities detected in the product. During operation of the small scale laboratory cell, a number of technical problems including anode effect, low oxide solubility in the electrolyte, high neodymium metal solubility, reactivity of the metal with the cell materials, and back reaction of the metal with the anode gases were encountered. Approaches to improve cell operation and prospects for commercial adoption of the electrolytic production of neodymium metal are discussed.

  5. Particle-hole and particle-particle correlations in neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Ponomarev, V. Yu.; Pignanelli, M.; Blasi, N.; Bontempi, A.; Bordewijk, J. A.; De Leo, R.; Graw, G.; Harakeh, M. N.; Hofer, D.; Hofstee, M. A.; Micheletti, S.; Perrino, R.; van der Werf, S. Y.

    Excited states in 140, 142, 144, 146Nd nuclei, up to an excitation energy of about 5 MeV, were investigated by (p,t) experiments performed with a good energy resolution. These data, together with proton and deuteron scattering data from a previous experiment, are compared with Quasi-Particle Phonon Model evaluations, in which the competition between particle-hole and particle-particle residual interactions is considered. The B(Eλ) distributions are satisfactorily reproduced. The 146, 148Nd(p,t) reaction data are well accounted for, while difficulties are found in reproducing those for 142, 144Nd(p,t). Limitations and improvements of the model are discussed.

  6. Sources of continental crust: neodymium isotope evidence from the sierra nevada and peninsular ranges.

    PubMed

    Depaolo, D J

    1980-08-01

    Granitic rocks from batholiths of the Sierra Nevada and Peninsular Ranges exhibit initial (143)Nd/(144)Nd ratios that vary over a large range and correlate with (87)Sr/(86)Sr ratios. The data suggest that the batholiths represent mixtures of materials derived from (i) chemically depleted mantle identical to the source of island arcs and (ii) old continental crust, probably sediments or metasediments with a provenance age of approximately 1.6 x 10(9) years. These conclusions are consistent with a model for continental growth whereby new crustal additions are repeatedly extracted from the same limited volume of the upper mantle, which has consequently become depleted in elements that are enriched in the crust. There is little evidence that hydrothermally altered, subducted oceanic crust is a primary source of the magmas. PMID:17821189

  7. Recent Progress in the Development of Neodymium Doped Ceramic Yttria

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Edwards, Chris; Trivedi, Sudhir B.; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra; Kear, Bernard

    2007-01-01

    Solid-state lasers play a significant role in providing the technology necessary for active remote sensing of the atmosphere. Neodymium doped yttria (Nd:Y2O3) is considered to be an attractive material due to its possible lasing wavelengths of aprrox.914 nm and approx.946 nm for ozone profiling. These wavelengths when frequency tripled can generate UV light at approx.305 nm and approx.315 nm, which is particularly useful for ozone sensing using differential absorption lidar technique. For practical realization of space based UV transmitter technology, ceramic Nd:Y2O3 material is considered to possess great potential. A plasma melting and quenching method has been developed to produce Nd3+ doped powders for consolidation into Nd:Y2O3 ceramic laser materials. This far-from-equilibrium processing methodology allows higher levels of rare earth doping than can be achieved by equilibrium methods. The method comprises of two main steps: (a) plasma melting and quenching to generate dense, and homogeneous doped metastable powders, (b) pressure assisted consolidation of these powders by hot isostatic pressing to make dense nanocomposite ceramics. Using this process, several 1" x 1" ceramic cylinders have been produced. The infrared transmission of undoped Y2O3 ceramics was as high as approx.75% without anti-reflection coating. In the case of Nd:Y2O3 ceramics infrared transmission values of approx.50% were achieved. Furthermore, Nd:Y2O3 samples with dopant concentrations of up to approx.2 at. % were prepared without significant emission quenching.

  8. Treatment of urethral diseases with neodymium:YAG laser.

    PubMed

    Bloiso, G; Warner, R; Cohen, M

    1988-08-01

    Over a thirty-month period, a wide variety of common urethral problems were treated on an ambulatory basis, with the neodymium:yttrium-aluminum garnet (Nd:YAG) laser. When used discriminately, laser treatment appears to be an effective modality for the management of selected urethral strictures. Thus far, excellent results have been obtained in 30 of 31 cases of short strictures where laser urethrotomy was performed as the first stricture procedure (average follow-up 10 months). Furthermore, in a series of 36 cases of secondary bladder neck contractures, all of the evaluated patients responded well (average follow-up 7 months). Good results were obtained in only 11 of 48 complicated strictures (average follow-up 14 months). However, while most of these extensive strictures were not eradicated, laser therapy generally produced a documented clinical improvement, comparable to urethrotomy or dilatation, in 15 of these cases. A series of 24 condylomata involving the urethra were treated satisfactorily, with no recurrences (average follow-up 13 months). Laser treatment also has been used successfully for the management of several urethral caruncles, urethral polyps, two meatal hemangiomas, one urethral carcinoma, and a distal duplicated urethra. Recently, the Nd:YAG laser has been applied to the prostatic urethra with vaporization of obstructing median bar hyperplasia. Favorable results have been achieved in 5 of 6 cases treated with a newly developed technique that utilizes direct laser contact. Retrograde ejaculation has not been encountered in these patients (average follow-up 6 months). All of these procedures have been accomplished in the office, largely without urethral catheterization. Lidocaine jelly occasionally supplemented with intravenous sedation provided satisfactory anesthesia. PMID:3400132

  9. Effect of fulvic acid on neodymium uptake by goethite.

    PubMed

    Armstrong, Christopher R; Wood, Scott A

    2012-12-01

    Experimental studies of the interaction of aqueous neodymium (Nd), Suwannee River fulvic acid (FA), and solid phase goethite were conducted. Results from blank systems (individual Nd and FA), binary systems (Nd-goethite, FA-goethite, and Nd-FA), and ternary systems (Nd-FA-goethite) at 0.1 mol/kg and 25°C are reported. In the binary Nd-goethite system a classic sorption edge is observed, whereby virtually all Nd is removed from solution above the goethite point of zero charge (PZC). Similarly, the binary FA-goethite system exhibits strong FA sorption; However in this system near complete removal of FA from solution is observed below the goethite PZC. In the binary Nd-FA system, both aqueous Nd and FA feature a sharp decrease in concentration at ca. pH 9. Various experiments in the ternary system were conducted. For all concentrations, FA enhanced Nd sorption below the goethite PZC, attributed to the formation of a Type B ternary surface complex (mineral-ligand-metal ion). Notably, the 100 ppm FA ternary system showed anomalously high dissolved Nd in solution above the PZC (i.e., Nd sorption suppression) and a concomitant increase in goethite dissolution (∼9 ppm total Fe(3+) observed above circa pH 9.5). Our results suggest that Nd-FA complexation plays a key role in Nd uptake by goethite, and that this process is largely governed by pH: Whereas at pHs below the goethite PZC, Nd-FA complexation facilitates Nd sorption, above the PZC, and particularly at elevated FA concentrations, the formation of aqueous Nd-FA complexes suppresses Nd removal. Moreover, under these conditions, goethite dissolution may also play a role in mitigating Nd uptake by goethite. PMID:22958855

  10. Astrometric solar system anomalies

    SciTech Connect

    Nieto, Michael Martin; 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{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.

  11. About Isotopic Composition of Oil and Bitumoids of the South-Tatarian Arch

    NASA Astrophysics Data System (ADS)

    Gottikh, R.; Pisotskiy, B.; Plotnikova, I.

    2009-04-01

    The area of study is located in the eastern part of the East European Platform. The territory of investigation is confined to the central portion of the Volga-Ural Antecline. Within the last decade a number of scientific publications emphasizing a leading role of deep fluids in the genesis of hydrocarbons increased significantly. Among the evidences of participation of deep fluids in formation of oil accumulations are the results of geochemical studies. The long-term study of micro-elemental composition of oil suggests the presence of a wide range of metals in oil. Both the presence and composition of these metals could not be related to rocks of the sedimentary cover. For example, sometimes the abundances of volatile chalcophile and dispersed elements characteristic of basal and ultrabasic rocks (Hg, Au, Ag, Cu, Re, Se, As, et al.) are ten to hundred times higher than the Earth's crust Clarke values. Moreover, oil contains high-charge and high-ionic lithophilous elements (U, Th, REE, Zr et al.) characteristic of alkaline and ultra-alkaline rock complexes (Gottikh et al., 2008). In addition platinoids, among which palladium is predominating, are found in oil. Palladium is commonly predominating over the total of Ru+Ir+Rh. Interrelation between these components is controlling the geochemical classification of oil provinces by platinum metal specialization. The presence of chromium, cuprum, nickel and cobalt in oil in addition to platinoids is indicator of the chemical and metallogeny features of platform hyperbasites (Marakushev et al., 2004). Of much importance is the presence of a sharply defined positive europium anomaly in hondrite-normalized distribution of rare elements in oil that is unusual for host rocks, formation water and organic material (Vinokurov et al., 2000). Finally, the inconsistence of isotopic composition of neodymium and strontium enclosed by oil and the isotopic composition of bitumoids of probable oil source rocks is found (Gottikh et al

  12. Unusual mercury isotopic compositions in aqueous environment

    NASA Astrophysics Data System (ADS)

    Chen, J.; Hintelmann, H.; Zheng, W.; Feng, X.; Cai, H.; Wang, Z.; Yuan, S.

    2014-12-01

    Preliminary studies have demonstrated both mass-dependent fractionation (MDF) and mass-independent fractionation (MIF) of Hg isotopes in natural samples. Laboratory experiments showed that photochemical reduction of inorganic mercury (iHg) and methylmercury (MMHg) and liquid-vapour evaporation could produce MIF of odd Hg isotopes. This was thought to cause the MIF actually observed in aquatic organisms. Although isotopic measurements of Hg in aqueous environment would give direct evidence, little data was reported for surface water samples. Recent work reported, unexpectedly, positive MIF of odd Hg isotopes in both precipitation and ambient air, in contrast with the prediction of laboratory experiments and measurements of Hg accumulated in lichens . Intriguingly, MIF of even-mass Hg isotope (200Hg) was also recently determined in the atmosphere. In contrast with the now mainstream observation of odd Hg isotope anomaly that has several theoretical explanations, the hitherto mysterious even Hg isotope anomalies were neither reported in laboratory experiments, nor predicted by isotope fractionation mechanisms, highlighting the importance of further study on Hg isotopes in variable systems. Our measurements of lichens and lake water samples from different countries show for the first time significant Δ200Hg in surface terrestrial reservoirs, realizing a direct connection of even Hg isotope anomaly in the terrestrial reservoirs to the atmospheric deposition, and fulfilling the gap of Δ200Hg between the atmosphere and the terrestrial receptors. The specific odd Hg isotope compositions determined in lake waters also support the atmosphere contribution, and may be directly linked to the high Δ199Hg values largely determined and manifested on the top of aqueous food web. Our data show that the watershed Hg input is another contributing source, rather than the in-lake processes, to explain the lacustrine Hg isotope anomalies. Interestingly, lake sediments are isotopically

  13. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions

    USGS Publications Warehouse

    Basu, A.R.; Tatsumoto, M.

    1979-01-01

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 ?? 106 to 1300 ?? 106 years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. Copyright ?? 1979 AAAS.

  14. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions.

    PubMed

    Basu, A R; Tatsumoto, M

    1979-07-27

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 x 10(6) to 1300 x 10(6) years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. PMID:17790851

  15. Equilibrium distribution of lanthanum, neodymium, and thorium between lithium chloride melt and liquid bismuth

    NASA Astrophysics Data System (ADS)

    Zagnit'ko, A. V.; Ignat'ev, V. V.

    2013-04-01

    The distribution of lanthanum, neodymium, and thorium between a lithium chloride melt and liquid bismuth with additions of lithium as a reducing agent are investigated at 650°C. Equilibrium values of their distribution constants are measured. It is shown that in contrast to neodymium and lanthanum, thorium cannot be extracted from bismuth into lithium chloride. This allows us to propose an efficient scheme for separating lanthanides and thorium in a system for the extraction of fuel salts in molten-salt nuclear reactors.

  16. Epitaxial neodymium-doped sapphire films, a new active medium for waveguide lasers.

    PubMed

    Kumaran, Raveen; Webster, Scott E; Penson, Shawn; Li, Wei; Tiedje, Thomas; Wei, Peng; Schiettekatte, Francois

    2009-11-01

    Epitaxial films of neodymium-doped sapphire have been grown by molecular beam epitaxy on R-, A-, and M-plane sapphire substrates. The emission spectrum features sharp lines consistent with single-site doping of the Nd(3+) ion into the host crystal. This material is believed to be a nonequilibrium phase, inaccessible by conventional high-temperature growth methods. Neodymium-doped sapphire has a promising lasing line at 1096 nm with an emission cross section of 11.9x10(-19) cm(2), similar to the 1064 nm line of Nd:YVO(4). PMID:19881593

  17. Thermal and Isotopic Anomalies when pd Cathodes are Electrolyzed in Electrolytes Containing Th-Hg Salts Dissolved at Micromolar Concentration in C2H5OD/D2O Mixtures

    NASA Astrophysics Data System (ADS)

    Celani, F.; Spallone, A.; Righi, E.; Trenta, G.; Catena, C.; D'Agostaro, G.; Quercia, P.; Andreassi, V.; Marini, P.; di Stefano, V.; Nakamura, M.; Mancini, A.; Sona, P. G.; Fontana, F.; Gamberale, L.; Garbelli, D.; Falcioni, F.; Marchesini, M.; Novaro, E.; Mastromatteo, U.

    2005-12-01

    Discussed in this paper is the evolution of work that started by using the M. Fleischmann and S. Pons method and ended by using thin palladium wires electrolyzed in an electrolyte consisting of slightly acidic heavy alcohol-water solution containing thorium (Th) and mercury (Hg) salts at micromolar concentrations. The resulting large and dynamic loading of the Pd wires was studied. The recent use of thorium instead of strontium resulted in thermal anomalies and detection of new elements in larger amounts. The results with Sr are qualitatively in agreement with what was found by Y. Iwamura (Mitsubishi Heavy Industries) using multilayers of Pd-CaO-Pd-Sr in flowing deuterium gas. Most results seem to be in agreement with a "multi-body resonance fusion of deuterons" model recently developed by A.Takahashi (Osaka University).

  18. QCD trace anomaly

    SciTech Connect

    Andersen, Jens O.; Leganger, Lars E.; Strickland, Michael; Su, Nan

    2011-10-15

    In this brief report we compare the predictions of a recent next-to-next-to-leading order hard-thermal-loop perturbation theory (HTLpt) calculation of the QCD trace anomaly to available lattice data. We focus on the trace anomaly scaled by T{sup 2} in two cases: N{sub f}=0 and N{sub f}=3. When using the canonical value of {mu}=2{pi}T for the renormalization scale, we find that for Yang-Mills theory (N{sub f}=0) agreement between HTLpt and lattice data for the T{sup 2}-scaled trace anomaly begins at temperatures on the order of 8T{sub c}, while treating the subtracted piece as an interaction term when including quarks (N{sub f}=3) agreement begins already at temperatures above 2T{sub c}. In both cases we find that at very high temperatures the T{sup 2}-scaled trace anomaly increases with temperature in accordance with the predictions of HTLpt.

  19. Modeling the Pioneer anomaly

    NASA Astrophysics Data System (ADS)

    Leibovitz, Jacques

    2007-04-01

    Scientists continue their attempts to model the observed Pioneer anomaly (PA) as an artifact of measurement or of equipment operation. Scientists also explore ``new physics'' as a possible explanation, but they have eliminated dark matter (DM). Here, the main arguments used to eliminate DM are refuted and then the anomaly is modeled by application of Newton laws to the observed macroscopic properties of DM. Around a central mass M, the modeling predicts a DM distribution that produces the PA at short distances (R smaller than 188 AU) from a star like the Sun, and a flat rotation curve at sufficiently large distances from the center of a galaxy. Below about 188 AU from the Sun, the modeling predicts that the anomaly may be expressed as PA = 8.3E-8 [R̂(-2)] -- 1 cm (s)̂(-2). It shows that the anomaly remains fairly constant down to 5 AU, decreases significantly from 5 AU to 1 AU where it becomes zero and changes sign below a distance of 1 AU, then increases rapidly in magnitude as R decreases in that range. Verifiable tests are proposed. Some related topics for future research are proposed.

  20. Magnetoresistance and magnetic ordering in praseodymium and neodymium hexaborides

    SciTech Connect

    Anisimov, M. A.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Samarin, N. A.; Filipov, V. B.; Shitsevalova, N. Yu.; Kuznetsov, A. V.; Sluchanko, N. E.

    2009-11-15

    The magnetoresistance {Delta}{rho}/{rho} of single-crystal samples of praseodymium and neodymium hexaborides (PrB{sub 6} and NdB{sub 6}) has been measured at temperatures ranging from 2 to 20 K in a magnetic field of up to 80 kOe. The results obtained have revealed a crossover of the regime from a small negative magnetoresistance in the paramagnetic state to a large positive magnetoresistive effect in magnetically ordered phases of the PrB{sub 6} and NdB{sub 6} compounds. An analysis of the dependences {Delta}{rho}(H)/{rho} has made it possible to separate three contributions to the magnetoresistance for the compounds under investigation. In addition to the main negative contribution, which is quadratic in the magnetic field (-{Delta}{rho}/{rho} {proportional_to} H{sup 2}), a linear positive contribution ({Delta}{rho}/{rho} {proportional_to} H) and a nonlinear ferromagnetic contribution have been found. Upon transition to a magnetically ordered state, the linear positive component in the magnetoresistance of the PrB{sub 6} and NdB{sub 6} compounds becomes dominant, whereas the quadratic contribution to the negative magnetoresistance is completely suppressed in the commensurate magnetic phase of these compounds. The presence of several components in the magnetoresistance has been explained by assuming that, in the antiferromagnetic phases of PrB{sub 6} and NdB{sub 6}, ferromagnetic nanoregions (ferrons) are formed in the 5d band in the vicinity of the rareearth ions. The origin of the quadratic contribution to the negative magnetoresistance is interpreted in terms of the Yosida model, which takes into account scattering of conduction electrons by localized magnetic moments of rare-earth ions. Within the approach used, the local magnetic susceptibility {chi}{sub loc} has been estimated. It has been demonstrated that, in the temperature range T{sub N} < T < 20 K, the behavior of the local magnetic susceptibility {chi}{sub loc} for the compounds under investigation can

  1. Demonstrating and Measuring Relative Molar Magnetic Susceptibility Using a Neodymium Magnet

    ERIC Educational Resources Information Center

    Malerich, Charles; Ruff, Patricia K.; Bird, Aubrey

    2004-01-01

    An easy-to-see method for demonstrating and measuring the magnetic force between paramagnetic substance and a rare earth magnet is presented. The readily available trapezoid-shaped neodymium magnet and a low cost, easy-to-set-up, portable apparatus are used in the experiments.

  2. Neodymium YAG lasers. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Mauk, S. C.

    1980-01-01

    Various aspects of neodymium yag lasers are discussed in approximately 267 citations. Laser materials and outputs, laser mode locking; crystal, fiber, and nonlinear optics, optical pumping communications, energy conversion efficiency, and laser applications are covered. Pulsed, continuous wave, solid state, Q switched, infrared, and dye lasers are included.

  3. Measurement of the gain in a disk amplification stage with neodymium phosphate glass active elements

    SciTech Connect

    Voronich, Ivan N; Galakhov, I V; Garanin, Sergey G; Eroshenko, V A; Zaretskii, Aleksei I; Zimalin, B G; Ignat'ev, Ivan V; Kirdyashkin, M Yu; Kirillov, G A; Osin, Vladimir A; Rukavishnikov, N N; Sukharev, Stanislav A; Sharov, Oleg A; Charukhchev, Aleksandr V

    2003-06-30

    The measuring technique is described and time-resolved measurements of the small-signal gain as a function of the pump energy in a disk amplification stage with neodymium phosphate glass active elements in the 'Luch' facility are presented. The distribution of the gain over the amplifier aperture in the horizontal plane is measured. (lasers)

  4. Attainment of a high gain in a disk amplifying stage with neodymium phosphate glass elements

    SciTech Connect

    Voronich, Ivan N; Garanin, Sergey G; Zaretskii, Aleksei I; Ignat'ev, Ivan V; Kirillov, G A; Murugov, Vasilii M; Osin, Vladimir A; Sukharev, Stanislav A; Charukhchev, Aleksandr V

    2004-06-30

    An efficient reflecting coating made of a MIRO foil with an oxide layer is fabricated, which enhances the reflection of radiation of pump lamps in the head of a high-power neodymium laser and allows a gain g{sub 0}=5x10{sup -2} cm{sup -1} to be achieved. (lasers)

  5. Praseodymium Nitrate and Neodymium Complexation with Organophosphorus Reagents in Supercritical Carbon Dioxide Solvent

    SciTech Connect

    Robert V. Fox; R. Duane Ball; Peter de B. Harrington; Harry W. Rollins; John G. Jolley; Chien M. Wai

    2004-11-01

    Complex formation reactions of praseodymium nitrate hexahydrate, and neodymium nitrate hexahydrate salts with tri-n-butyl phosphate (TBP) and several other neutral organophosphorus reagents were investigated in supercritical carbon dioxide. The concentration of the metal complexes in the supercritical fluid (SCF) phase was determined using UV-Vis and luminescence spectroscopies. The stoichiometry of the complexes was determined using the mole-ratio method. Extraction equilibrium constants were calculated from the spectral data using least-squares regression and hard-equilibria models. UV-Vis absorbance data indicate that praseodymium nitrate and neodymium nitrate both form 1:4 lanthanide–tributyl phosphate complexes in supercritical carbon dioxide at 308 K. The conditional extraction coefficients for those two systems were calculated to be log Kex=7.45±0.06 for the praseodymium system and log Kex=7.52±0.03 for the neodymium system. For comparison, neodymium nitrate complexation reactions with tri-n-butyl phosphate and tributyl phosphite (TBPO3) were studied in hexane under ambient conditions. UV-Vis data indicate that a 1:4 neodymium–tributyl phosphate complex is formed in hexane with a conditional extraction coefficient of log Kex=3.4±0.2. Tributyl phosphite forms a 1:8 complex with neodymium in hexane with a conditional extraction coefficient of log Kex=11.0±0.1. Neodymium nitrate was titrated with other organophosphorus reagents, tributyl phosphite and tributyl phosphine oxide (TBPO), in supercritical carbon dioxide to investigate differences between neutral oxygen donor ligands and neutral phosphorus donor ligands. UV-Vis and luminescence data indicate that neodymium nitrate forms a 1:8 complex with tributyl phosphite and a 1:5 complex with tributyl phosphine oxide, compared to a 1:4 complex with tri-n-butyl phosphate. The conditional extraction coefficient for the 1:8 neodymium–tributyl phosphite system was calculated as log Kex=21.4±0.2 from UV

  6. Anomaly discrimination in hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Yu; Paylor, Drew; Chang, Chein-I.

    2014-05-01

    Anomaly detection finds data samples whose signatures are spectrally distinct from their surrounding data samples. Unfortunately, it cannot discriminate the anomalies it detected one from another. In order to accomplish this task it requires a way of measuring spectral similarity such as spectral angle mapper (SAM) or spectral information divergence (SID) to determine if a detected anomaly is different from another. However, this arises in a challenging issue of how to find an appropriate thresholding value for this purpose. Interestingly, this issue has not received much attention in the past. This paper investigates the issue of anomaly discrimination which can differentiate detected anomalies without using any spectral measure. The ideas are to makes use unsupervised target detection algorithms, Automatic Target Generation Process (ATGP) coupled with an anomaly detector to distinguish detected anomalies. Experimental results show that the proposed methods are indeed very effective in anomaly discrimination.

  7. Si isotope homogeneity of the solar nebula

    SciTech Connect

    Pringle, Emily A.; Savage, Paul S.; Moynier, Frédéric; Jackson, Matthew G.; Barrat, Jean-Alix E-mail: savage@levee.wustl.edu E-mail: moynier@ipgp.fr E-mail: Jean-Alix.Barrat@univ-brest.fr

    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.

  8. Antler anomalies in tule elk

    USGS Publications Warehouse

    Gogan, Peter J.P.; Jessup, David A.; Barrett, Reginald H.

    1988-01-01

    Antler anomalies were evident in tule elk (Cervus elaphus nannodes) within 1 yr of reintroduction to Point Reyes, California (USA). These anomalies are consistent with previously described mineral deficiency-induced anomalies in cervids. The elk were judged deficient in copper. Low levels of copper in soils and vegetation at the release site, exacerbated by possible protein deficiency due to poor range conditions, are postulated as likely causes of the antler anomalies.

  9. Microbeam titanium isotopic analysis by resonance ionization mass spectrometry

    SciTech Connect

    Spiegel, D.R.; Davis, A.M.; Clayton, R.N. . Enrico Fermi Inst.); Pellin, M.J.; Calaway, W.F.; Burnett, J.W.; Coon, S.R.; Young, C.E.; Gruen, D.M. )

    1991-01-01

    The importance of isotopic anomalies in refractory inclusions in meteorites is well established. Measurements of the anomalies using conventional mass spectrometry are often rendered difficult, however, by isobarically interfering isotopes: for example, {sup 48}Ti and {sup 48}Ca. Resonance ionization mass spectrometry (RIMS) can substantially reduce isobaric interferences in a number of systems. We have employed RIMS for the in situ detection of Ti atoms sputtered from pure Ti metal and from several terrestrial oxides containing both Ti and Ca. Tunable lasers were employed to resonantly ionize neutral Ti atoms. We have chosen Ti specifically because of the importance of Ti isotopic anomalies in cosmochemistry.

  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. Isotopic and trace-element constraints on mantle and crustal contributions to Siberian continental flood basalts, Noril'sk area, Siberia

    USGS Publications Warehouse

    Wooden, J.L.; Czamanske, G.K.; Fedorenko, V.A.; Arndt, N.T.; Chauvel, C.; Bouse, R.M.; King, B.-S.W.; Knight, R.J.; Siems, D.F.

    1993-01-01

    We present a tightly controlled and comprehensive set of analytical data for the 250-Ma Siberian flood-basalt province. Consideration of major- and trace-element compositions, along with strontium, lead and neodymium isotopic compositions, strongly supports earlier Russian subdivision of this magmatism into three magmatic cycles, giving rise to three assemblages of eleven basalt suites in the ascending order Ivakinsky-Gudchikhinsky, Khakanchansky-Nadezhdinsky and Morongovsky-Samoedsky. Geochemical and isotopic discontinuities of varying magnitude characterize most of the boundaries between the eleven recognized basalt suites in the Noril'sk area. Although we conclude that the dominant volume of erupted magma originated from an asthenospheric mantle plume, none of the lavas is interpreted to directly represent asthenospheric melts, which would have been far more magnesian. On the basis of thermal considerations, we consider it unlikely that vast volumes of basaltic melt were produced directly from the continental lithospheric mantle beneath the Siberian craton. Moreover, there is little evidence from mantle xenoliths that the geochemical signatures of such melts would correspond to those of the Siberian flood basalts. Studies of melt migration lead us to conclude that transport of asthenospheric melt through the lithospheric mantle would be rapid, by fracture propagation. Lavas from the Gudchikhinsky suite have negligible Ta-Nb anomalies and positive ??{lunate}Nd values and their parental magmas presumably interacted little with the continental lithospheric mantle or crust. All other lavas have negative Ta-Nb anomalies and lower ??{lunate}Nd values that we attribute to interaction with continental crust. The model that we have developed requires discrete contributions from the plume and complex processing of all erupted magmas in the continental crust. The earliest magmas represent small percentages of melt formed in equilibrium with garnet. Over time, the

  12. Hypercharged anomaly mediation.

    PubMed

    Dermísek, Radovan; Verlinde, Herman; Wang, Lian-Tao

    2008-04-01

    We show that, in string models with the minimal supersymmetric standard model residing on D-branes, the bino mass can be generated in a geometrically separated hidden sector. Hypercharge mediation thus naturally teams up with anomaly mediation. The mixed scenario predicts a distinctive yet viable superpartner spectrum, provided that the ratio alpha between the bino and gravitino mass lies in the range 0.05 < or = |alpha| < or = 0.25 and m(3/2) > or = 35 TeV. We summarize some of the experimental signatures of this scenario. PMID:18517937

  13. Satellite magnetic anomalies over subduction zones - The Aleutian Arc anomaly

    NASA Technical Reports Server (NTRS)

    Clark, S. C.; Frey, H.; Thomas, H. H.

    1985-01-01

    Positive magnetic anomalies seen in MAGSAT average scalar anomaly data overlying some subduction zones can be explained in terms of the magnetization contrast between the cold subducted oceanic slab and the surrounding hotter, nonmagnetic mantle. Three-dimensional modeling studies show that peak anomaly amplitude and location depend on slab length and dip. A model for the Aleutian Arc anomaly matches the general trend of the observed MAGSAT anomaly if a slab thickness of 7 km and a relatively high (induced plus viscous) magnetization contrast of 4 A/m are used. A second source body along the present day continental margin is required to match the observed anomaly in detail, and may be modeled as a relic slab from subduction prior to 60 m.y. ago.

  14. 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.

  15. Meteoritic Ce-138/Ce-142 ratio and its evolution

    NASA Astrophysics Data System (ADS)

    Shimizu, H.; Tanaka, T.; Masuda, A.

    1984-01-01

    Cerium isotope ratios were determined for Juvinas, Pasamonte and ALH-78132 eucrites and the Jilin (H4) chondrite. Neodymium isotope ratios and abundances of lanthanum, cerium, neodymium and samarium were also determined for these meteorites. The La-Ce isotopic system, coupled with the Sm-Nd system, provides a new isotope tracer for geo- and cosmo-chemical samples, especially for samples having a Ce anomaly in the rare-earth element patterns.

  16. The XXXXY Chromosome Anomaly

    PubMed Central

    Zaleski, Witold A.; Houston, C. Stuart; Pozsonyi, J.; Ying, K. L.

    1966-01-01

    The majority of abnormal sex chromosome complexes in the male have been considered to be variants of Klinefelter's syndrome but an exception should probably be made in the case of the XXXXY individual who has distinctive phenotypic features. Clinical, radiological and cytological data on three new cases of XXXXY syndrome are presented and 30 cases from the literature are reviewed. In many cases the published clinical and radiological data were supplemented and re-evaluated. Mental retardation, usually severe, was present in all cases. Typical facies was observed in many; clinodactyly of the fifth finger was seen in nearly all. Radiological examination revealed abnormalities in the elbows and wrists in all the 19 personally evaluated cases, and other skeletal anomalies were very frequent. Cryptorchism is very common and absence of Leydig's cells may differentiate the XXXXY chromosome anomaly from polysomic variants of Klinefelter's syndrome. The relationship of this syndrome to Klinefelter's syndrome and to Down's syndrome is discussed. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15 PMID:4222822

  17. Trace anomaly driven inflation

    NASA Astrophysics Data System (ADS)

    Hawking, S. W.; Hertog, T.; Reall, H. S.

    2001-04-01

    This paper investigates Starobinsky's model of inflation driven by the trace anomaly of conformally coupled matter fields. This model does not suffer from the problem of contrived initial conditions that occurs in most models of inflation driven by a scalar field. The universe can be nucleated semiclassically by a cosmological instanton that is much larger than the Planck scale provided there are sufficiently many matter fields. There are two cosmological instantons: the four sphere and a new ``double bubble'' solution. This paper considers a universe nucleated by the four sphere. The AdS/CFT correspondence is used to calculate the correlation function for scalar and tensor metric perturbations during the ensuing de Sitter phase. The analytic structure of the scalar and tensor propagators is discussed in detail. Observational constraints on the model are discussed. Quantum loops of matter fields are shown to strongly suppress short scale metric perturbations, which implies that short distance modifications of gravity would probably not be observable in the cosmic microwave background. This is probably true for any model of inflation provided there are sufficiently many matter fields. This point is illustrated by a comparison of anomaly driven inflation in four dimensions and in a Randall-Sundrum brane-world model.

  18. Automated anomaly detection processor

    NASA Astrophysics Data System (ADS)

    Kraiman, James B.; Arouh, Scott L.; Webb, Michael L.

    2002-07-01

    Robust exploitation of tracking and surveillance data will provide an early warning and cueing capability for military and civilian Law Enforcement Agency operations. This will improve dynamic tasking of limited resources and hence operational efficiency. The challenge is to rapidly identify threat activity within a huge background of noncombatant traffic. We discuss development of an Automated Anomaly Detection Processor (AADP) that exploits multi-INT, multi-sensor tracking and surveillance data to rapidly identify and characterize events and/or objects of military interest, without requiring operators to specify threat behaviors or templates. The AADP has successfully detected an anomaly in traffic patterns in Los Angeles, analyzed ship track data collected during a Fleet Battle Experiment to detect simulated mine laying behavior amongst maritime noncombatants, and is currently under development for surface vessel tracking within the Coast Guard's Vessel Traffic Service to support port security, ship inspection, and harbor traffic control missions, and to monitor medical surveillance databases for early alert of a bioterrorist attack. The AADP can also be integrated into combat simulations to enhance model fidelity of multi-sensor fusion effects in military operations.

  19. Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

    SciTech Connect

    Rosal, Blanca del; Pérez-Delgado, Alberto; Rocha, Ueslen; Martín Rodríguez, Emma; Jaque, Daniel; Misiak, Małgorzata; Bednarkiewicz, Artur; Vanetsev, Alexander S.; Orlovskii, Yurii; Jovanović, Dragana J.; Dramićanin, Miroslav D.; Upendra Kumar, K.; Jacinto, Carlos; Navarro, Elizabeth; and others

    2015-10-14

    The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF{sub 3}:Nd{sup 3+}, SrF{sub 2}:Nd{sup 3+}, NaGdF{sub 4}: Nd{sup 3+}, NaYF{sub 4}: Nd{sup 3+}, KYF{sub 4}: Nd{sup 3+}, GdVO{sub 4}: Nd{sup 3+}, and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a “universal” optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymium-doped nanoparticle to be preferentially used in each case.

  20. Neodymium-doped barium borate glasses as fluorescent concentrators for the infrared spectral range

    NASA Astrophysics Data System (ADS)

    Dyrba, Marcel; Wiegand, Marie-Christin; Ahrens, Bernd; Schweizer, Stefan

    2012-06-01

    Neodymium-doped barium borate glasses are investigated for their potential as fluorescent concentrators for the near infrared spectral range. Additional doping of the glasses with silver oxide and subsequent heat treatment leads to a reduction of the doped silver ions and to the formation of metallic silver nanoparticles. The formation of the silver nanoparticles is indicated by a broad surface plasmon-related extinction band at approximately 410 nm. The influence of the silver nanoparticles on the fluorescence properties is investigated.

  1. Long-Pulsed Neodymium-Doped Yttrium Aluminum Garnet Laser for Glomuvenous Malformations in Adolescents.

    PubMed

    Trost, Jaren; Buckley, Colin; Smidt, Aimee C

    2015-01-01

    Currently there exist few reported cases where lasers are used successfully to treat glomuvenous malformations in adolescents. In the two cases described here, we provide evidence that the long-pulsed neodymium-doped yttrium aluminum garnet laser is an effective and safe alternative treatment for these lesions. Our case series is unique because it focuses on adolescents, the population that most often seeks treatment for this dermatologic condition. PMID:26138991

  2. Neodymium(III) Complexation by Amino-Carbohydrates via a Ligand-Controlled Hydrolysis Mechanism

    SciTech Connect

    Levitskaia, Tatiana G.; Chen, Yongsheng; Fulton, John L.; Sinkov, Sergey I.

    2011-07-28

    Chelation of neodymium-III Nd(III) by D-glucosamine (DGA) and chitosan was investigated in solution at near-physiological pH and ionic strength. This research demonstrates the first example of the lanthanide ion heteroleptic hydroxo-carbohydrate complex in solution. It was demonstrated that DGA and chitosan suppressed formation of polynuclear Nd(III) species at elevated pH.

  3. Quantum anomalies in dense matter

    SciTech Connect

    Son, D.T.; Zhitnitsky, Ariel R.

    2004-10-01

    We consider the effects of quantum anomalies involving the baryon current for high-density matter. In the effective Lagrangian, the anomaly terms describe the interaction of three light fields: the electromagnetic photons A{sub {mu}}, neutral light Nambu-Goldstone bosons ({pi}, {eta}, {eta}{sup '}), and the superfluid phonon. The anomaly induced interactions lead to a number of interesting phenomena which may have phenomenological consequences observable in neutron stars.

  4. Crystallization of neodymium-rich phases in silicate glasses developed for nuclear waste immobilization

    NASA Astrophysics Data System (ADS)

    Caurant, D.; Majerus, O.; Loiseau, P.; Bardez, I.; Baffier, N.; Dussossoy, J. L.

    2006-08-01

    Glass-ceramics containing neodymium-rich crystalline phases can be obtained by crystallization of silicate glasses (nucleation + crystal growth heat treatments) or by controlled cooling of melts. Such materials could be envisaged as durable matrices for conditioning minor actinides- and Pu-rich nuclear wastes if the partitioning ratio of the wastes between crystalline phase and residual glass is high (principle of double containment barrier). In radioactive waste forms, Nd would be partially substituted by actinides and neutron absorbers (Gd). In this work, two silicate glass compositions leading to efficient nucleation and crystallization of either zirconolite (Ca 1- xNd xZrTi 2- xAl xO 7, x < 1) or apatite (Ca 2Nd 8Si 6O 26) in their bulk were studied as potential waste forms. The effect of the method used to prepare glass-ceramics (controlled cooling from the melt or nucleation + crystal growth from the glass) on both the microstructure and the structure of the neodymium-rich crystalline phase was studied. The highest number of zirconolite or apatite crystals in the bulk was obtained using the nucleation + crystal growth method. However, the percentage of neodymium incorporated in zirconolite crystals remained too small to make realistic the use of such materials for the conditioning of actinides in comparison with more durable bulk ceramics.

  5. Structural and optical properties of calcium neodymium hexaaluminates single crystals, potential laser materials

    NASA Astrophysics Data System (ADS)

    Alablanche, S.; Kahn-Harari, A.; Thery, J.; Viana, B.; Vivien, D.; Dexpert-Ghys, J.; Faucher, M.

    1992-05-01

    The structural and optical properties of calcium-neodymium hexaaluminates crystals Ca 1- xNd xMg x Al 12- xO 19 (labeled Ca 1- xNd x) with a magnetoplumbite (MP) structure are investigated. The floating zone method is used to grow single crystals in the composition range 0.1 ≤ x ≤ 0.7, although for high calcium content, the melting of the compounds is no longer congruent. The X-ray structural determination, optical absorption at 4 K, and ESR investigation agree in the localization of Nd 3+ at the regular large cations site of the MP structure with axial ( D3 h) symmetry. A set of crystal field and free ion parameters which fits the absorption spectrum of Nd 3+ in this site is calculated. When x increases, Nd 3+ ions tend to occupy also a second site with lower symmetry. Moreover some anomalous behavior observed in the absorption and ESR spectra at high neodymium concentration may be related to Nd 3+-Nd 3+ ion pairing. Fluorescence intensity and lifetime measurements as a function of the x value are reported. There is evidence of strong cross-relaxation between neighboring neodymium ions for high x values. The results obtained for the Ca 1- xNd x compounds can be extended to other series in which Nd 3+ is replaced by another lanthanide ion. Preliminary investigations have been performed with Pr 3+ and are also reported.

  6. Single crystal growth and characterization of lanthanum-neodymium oxalate octahydrate

    NASA Astrophysics Data System (ADS)

    Want, Basharat

    2011-11-01

    Single crystals of mixed lanthanum-neodymium oxalates are grown by gel diffusion method using agar gel as a medium of growth. The crystals grow in the agar gel with hexagonal morphology having (001), (110) and (010) as habit faces. Single crystal X-ray diffraction results show that the crystals belong to monoclinic system with cell parameters; a=10.344(2) Å, b=9.643(6) Å, c=11.721(2) Å, β=118.7 (2)° , bearing the space group P2/c. Fourier transform infrared spectrum of the crystals indicates the presence of water and other functional groups associated with the oxalate ions. Thermogravimetric and differential thermal analysis support the presence of 8H 2O molecules attached to the lanthanum-neodymium crystal lattice. The thermal decomposition in the nitrogen atmosphere leads to the formation of mixed lanthanum-neodymium oxide as the final product. Energy dispersive analysis of X-rays along with elemental analysis suggests the stoichiometry of the gel grown crystals to be La 1.5Nd 0.5(C 2O 4) 3·8H 2O.

  7. Rare Upper Airway Anomalies.

    PubMed

    Windsor, Alanna; Clemmens, Clarice; Jacobs, Ian N

    2016-01-01

    A broad spectrum of congenital upper airway anomalies can occur as a result of errors during embryologic development. In this review, we will describe the clinical presentation, diagnosis, and management strategies for a few select, rare congenital malformations of this system. The diagnostic tools used in workup of these disorders range from prenatal tests to radiological imaging, swallowing evaluations, indirect or direct laryngoscopy, and rigid bronchoscopy. While these congenital defects can occur in isolation, they are often associated with disorders of other organ systems or may present as part of a syndrome. Therefore workup and treatment planning for patients with these disorders often involves a team of multiple specialists, including paediatricians, otolaryngologists, pulmonologists, speech pathologists, gastroenterologists, and geneticists. PMID:26277452

  8. Genetics of lymphatic anomalies

    PubMed Central

    Brouillard, Pascal; Boon, Laurence; Vikkula, Miikka

    2014-01-01

    Lymphatic anomalies include a variety of developmental and/or functional defects affecting the lymphatic vessels: sporadic and familial forms of primary lymphedema, secondary lymphedema, chylothorax and chylous ascites, lymphatic malformations, and overgrowth syndromes with a lymphatic component. Germline mutations have been identified in at least 20 genes that encode proteins acting around VEGFR-3 signaling but also downstream of other tyrosine kinase receptors. These mutations exert their effects via the RAS/MAPK and the PI3K/AKT pathways and explain more than a quarter of the incidence of primary lymphedema, mostly of inherited forms. More common forms may also result from multigenic effects or post-zygotic mutations. Most of the corresponding murine knockouts are homozygous lethal, while heterozygotes are healthy, which suggests differences in human and murine physiology and the influence of other factors. PMID:24590274

  9. Nolen-Schiffer anomaly

    SciTech Connect

    Pieper, S.C.; Wiringa, R.B.

    1995-08-01

    The Argonne v{sub 18} potential contains a detailed treatment of the pp, pn and nn electromagnetic potential, including Coulomb, vacuum polarization, Darwin Foldy and magnetic moment terms, all with suitable form factors and was fit to pp and pn data using the appropriate nuclear masses. In addition, it contains a nuclear charge-symmetry breaking (CSB) term adjusted to reproduce the difference in the experimental pp and nn scattering lengths. We have used these potential terms to compute differences in the binding energies of mirror isospin-1/2 nuclei (Nolen-Schiffer [NS] anomaly). Variational Monte Carlo calculations for the {sup 3}He-{sup 3}H system and cluster variational Monte Carlo for the {sup 15}O-{sup 15}N and {sup 17}F-{sup 17}O systems were made. In the first case, the best variational wave function for the A = 3 nuclei was used. However, because our {sup 16}O wave function does not reproduce accurately the {sup 16}O rms radius, to which the NS anomaly is very sensitive, we adjusted the A = 15 and A = 17 wave functions to reproduce the experimental density profiles. Our computed energy differences for these three systems are 0.757 {plus_minus} .001, 3.544 {plus_minus} .018 and 3.458 {plus_minus} .040 MeV respectively, which are to be compared with the experimental differences of 0.764, 3.537, and 3.544 MeV. Most of the theoretical uncertainties are due to uncertainties in the experimental rms radii. The nuclear CSB potential contributes 0.066, 0.188, and 0.090 MeV to these totals. We also attempted calculations for A = 39 and A = 41. However, in these cases, the experimental uncertainties in the rms radius make it impossible to extract useful information about the contribution of the nuclear CSB potential.

  10. Identification of isotopically primitive interplanetary dust particles: A NanoSIMS isotopic imaging study

    SciTech Connect

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

    2005-09-02

    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 {sup 15}N, including the largest {sup 15}N enrichments ({approx}1300 {per_thousand}) observed in IDPs to date. A number of the IDPs also contain larger regions with more modest enrichments in {sup 15}N, leading to average bulk N isotopic compositions that are {sup 15}N-enriched in these IDPs. Although C isotopic compositions are normal in most of the IDPs, two {sup 15}N-rich N-hotspots have correlated {sup 13}C anomalies. CN{sup -}/C{sup -} ratios suggest that most of the {sup 15}N-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 {sup 17}O and {sup 18}O 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  12. Seismic data fusion anomaly detection

    NASA Astrophysics Data System (ADS)

    Harrity, Kyle; Blasch, Erik; Alford, Mark; Ezekiel, Soundararajan; Ferris, David

    2014-06-01

    Detecting anomalies in non-stationary signals has valuable applications in many fields including medicine and meteorology. These include uses such as identifying possible heart conditions from an Electrocardiography (ECG) signals or predicting earthquakes via seismographic data. Over the many choices of anomaly detection algorithms, it is important to compare possible methods. In this paper, we examine and compare two approaches to anomaly detection and see how data fusion methods may improve performance. The first approach involves using an artificial neural network (ANN) to detect anomalies in a wavelet de-noised signal. The other method uses a perspective neural network (PNN) to analyze an arbitrary number of "perspectives" or transformations of the observed signal for anomalies. Possible perspectives may include wavelet de-noising, Fourier transform, peak-filtering, etc.. In order to evaluate these techniques via signal fusion metrics, we must apply signal preprocessing techniques such as de-noising methods to the original signal and then use a neural network to find anomalies in the generated signal. From this secondary result it is possible to use data fusion techniques that can be evaluated via existing data fusion metrics for single and multiple perspectives. The result will show which anomaly detection method, according to the metrics, is better suited overall for anomaly detection applications. The method used in this study could be applied to compare other signal processing algorithms.

  13. Medical management of vascular anomalies.

    PubMed

    Trenor, Cameron C

    2016-03-01

    We have entered an exciting era in the care of patients with vascular anomalies. These disorders require multidisciplinary care and coordination and dedicated centers have emerged to address this need. Vascular tumors have been treated with medical therapies for many years, while malformations have been historically treated with endovascular and operative procedures. The recent serendipitous discoveries of propranolol and sirolimus for vascular anomalies have revolutionized this field. In particular, sirolimus responses are challenging the dogma that vascular malformations are not biologically active. While initially explored for lymphatic anomalies, sirolimus is now being used broadly throughout the spectrum of vascular anomalies. Whether medical therapies are reserved for refractory patients or used first line is currently dependent on the experience and availability of alternative therapies at each institution. On the horizon, we anticipate new drugs targeting genes and pathways involved in vascular anomalies to be developed. Also, combinations of medications and protocols combining medical and procedural approaches are in development for refractory patients. PMID:27607327

  14. Congenital Anomalies of the Nose.

    PubMed

    Funamura, Jamie L; Tollefson, Travis T

    2016-04-01

    Congenital anomalies of the nose range from complete aplasia of the nose to duplications and nasal masses. Nasal development is the result of a complex embryologic patterning and fusion of multiple primordial structures. Loss of signaling proteins or failure of migration or proliferation can result in structural anomalies with significant cosmetic and functional consequences. Congenital anomalies of the nose can be categorized into four broad categories: (1) aplastic or hypoplastic, (2) hyperplastic or duplications, (3) clefts, and (4) nasal masses. Our knowledge of the embryologic origin of these anomalies helps dictate subsequent work-up for associated conditions, and the appropriate treatment or surgical approach to manage newborns and children with these anomalies. PMID:27097134

  15. Correlated Nitrogen And Carbon Anomalies In An Anhydrous Interplanetary Dust Particles

    SciTech Connect

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

    2003-10-31

    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 from an anhydrous non-cluster 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. 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.

  16. System for closure of a physical anomaly

    DOEpatents

    Bearinger, Jane P; Maitland, Duncan J; Schumann, Daniel L; Wilson, Thomas S

    2014-11-11

    Systems for closure of a physical anomaly. Closure is accomplished by a closure body with an exterior surface. The exterior surface contacts the opening of the anomaly and closes the anomaly. The closure body has a primary shape for closing the anomaly and a secondary shape for being positioned in the physical anomaly. The closure body preferably comprises a shape memory polymer.

  17. Binning of satellite magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Goyal, H. K.; Vonfrese, R. R. B.; Hinze, W. J.

    1985-01-01

    Crustal magnetic anomaly signals over satellite orbits were simulated to investigate numerical averaging as an anomaly estimator. Averaging as an anomaly estimator involves significant problems concerning spatial and amplitude smoothing of the satellite magnetic observations. The results of simulations suggest that the error of numerical averaging constitutes a small and relatively minor component of the total error-budget of higher orbital anomaly estimates, whereas for lower orbital estimates numerical averaging error increases substantially. As an alternative to numerical averaging, least-squares collocation was investigated and observed to produce substantially more accurate anomaly estimates, particularly as the orbital elevation of prediction was decreased towards the crustal sources. In contrast to averaging, collocation is a significantly more resource-intensive procedure to apply because of the practical, but surmountable problems related to establishing and inverting the covariance matrix for accurate anomaly prediction. However, collocation may be much more effectively used to exploit the anomaly details contained in the lower orbital satellite magnetic data for geologic analysis.

  18. 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.

  19. s-Process Os isotope enrichment in ureilites by planetary processing

    NASA Astrophysics Data System (ADS)

    Goderis, S.; Brandon, A. D.; Mayer, B.; Humayun, M.

    2015-12-01

    Ubiquitous nucleosynthetic isotope anomalies relative to the terrestrial isotopic composition in Mo, Ru, and other elements are known from both bulk chondrites and differentiated meteorites, but Os isotope ratios reported from such meteorites have been found to be indistinguishable from the terrestrial value. The carriers of s- and r-process Os must thus have been homogeneously distributed in the solar nebula. As large Os isotope anomalies are known from acid leachates and residues of primitive chondrites, the constant relative proportions of presolar s- and r-process carriers in such chondrites must have been maintained during nebular processes. It has long been assumed that partial melting of primitive chondrites would homogenize the isotopic heterogeneity carried by presolar grains. Here, ureilites, carbon-rich ultramafic achondrites dominantly composed of olivine and low-Ca pyroxene, are shown to be the first differentiated bulk Solar System materials for which nucleosynthetic Os isotope anomalies have been identified. These anomalies consist of enrichment in s-process Os heterogeneously distributed in different ureilites. Given the observed homogeneity of Os isotopes in all types of primitive chondrites, this Os isotope variability among ureilites must have been caused by selective removal of s-process-poor Os host phases, probably metal, during rapid localized melting on the ureilite parent body. While Mo and Ru isotope anomalies for all meteorites measured so far exhibit s-process deficits relative to the Earth, the opposite holds for the Os isotope anomalies in ureilites reported here. This might indicate that the Earth preferentially accreted olivine-rich restites and inherited a s-process excess relative to smaller meteorite bodies, consistent with Earth's high Mg/Si ratio and enrichment of s-process nuclides in Mo, Ru, and Nd isotopes. Our new Os isotope results imply that caution must be used when applying nucleosynthetic isotope anomalies as provenance

  20. Improving of the operation efficiency of the vehicle due to using of the neodymium magnets inside the vibration isolation devices

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.

    2015-09-01

    In this paper the isolation suspension with stiffness compensator based on neodymium magnets is suggested. It was found that the passive vibration isolators not completely sufficient of modern requirement of the vibration isolation. It was determined that the neodymium magnets with the same initial parameters are most effective in comparison with DC current electromagnets. The mathematical model of the vibration isolation suspension has been developed. In this research the traction characteristics for given magnets are presented. Also the design of the vibration isolation suspension with compensator of the stiffness based on neodymium magnets has been developed. This research has been performed under support of the President scholarship for young scientists under the order of Russian Federation Ministry of the education and science No 184 from 10th of March 2015.

  1. Atmospheric Methane Growth Anomalies, 2007 - Present

    NASA Astrophysics Data System (ADS)

    Lowry, D.; Dlugokencky, E. J.; Fisher, R. E.; Nisbet, E. G.; Lanoiselle, M.; France, J.

    2012-12-01

    Several marked growth anomalies in atmospheric methane have occurred since 2007. In particular there has been sustained growth in methane in the Southern Hemisphere. This southern growth anomaly is among the larger excursions in the global methane record so far occurring in the 21st century, yet in contrast to Arctic emission, it has had little attention. The increase in methane began in 2007 and continued through early-2012. In the zonal average from the Equator to 30°S, annual increases reached 7.9 ppb/yr in 2007, remained at 7.0 ppb/yr in 2008, fell to around 2.5 ppb/yr in 2009, then increased to 7.9 ppb/yr in 2010. To consider one specific site, recent data from Ascension Island (which samples South Atlantic air almost exclusively) suggests growth of ~11 ppb/yr from July 2010 to July 2011 (winter to winter) falling to 8 ppb/yr over Jan 2011 - Jan 2012 (summer to summer). Isotopic data for 2011 show 13C enrichments and depletions that may suggest inputs from tropical / subtropical fire and wetland sources, respectively. Despite the size of the southern anomaly, there has been virtually no discussion of its causes. Several possibilities exist: some or all may have occurred: 1) that methane emission from southern wetland (late wet season) and fire (dry season) sources increased sharply during this period; 2) that the southern OH methane sink has decreased; 3) that changes in atmospheric circulation patterns have increased inter-hemispheric transport. It is possible that a major factor was high La Nina rainfall in key areas draining into wetlands in southern tropical Africa and Latin America. Tropical methane sources emit roughly 200 Tg methane annually to the atmosphere, nearly two-fifths of the global budget. Thus changes in tropical sources, if sustained on this scale, can have global significance. However the observational network generally is so sparse in the tropics that identifying causes of methane growth events is more akin to guesswork than evidence

  2. CONTROL OF LASER RADIATION PARAMETERS: New nanosecond polymer passive switch for neodymium lasers

    NASA Astrophysics Data System (ADS)

    Bezrodnyi, V. I.; Vovk, L. V.; Derevyanko, Nadezhda A.; Ishchenko, Aleksandr A.; Karabanova, L. V.; Mushkalo, I. L.

    1995-03-01

    A new nanosecond passive switch for neodymium lasers was developed on the basis of a highly elastic polyurethane matrix with an optical strength of 1200 MW cm-2, containing a photostable organic dye NOK. The switch was investigated under various Q-switching conditions in YAG, GSGG : Cr : Nd, and yttrium aluminate crystal lasers. Nanosecond single giant pulses and bursts of pulses were generated. The service life was 2×106 pulses at a single point of the switch. The energy of giant single pulses was 0.9 J. Repetition of single pulses at 50 Hz was possible.

  3. Laser amplifier based on a neodymium glass rod 150 mm in diameter

    SciTech Connect

    Shaykin, A A; Fokin, A P; Soloviev, A A; Kuzmin, A A; Shaikin, I A; Burdonov, K F; Khazanov, E A; Charukhchev, A V

    2014-05-30

    A unique large-aperture neodymium glass rod amplifier is experimentally studied. The small-signal gain distribution is measured at different pump energies. The aperture-averaged gain is found to be 2.3. The stored energy (500 J), the maximum possible pump pulse repetition rate, and the depolarisation in a single pulse and in a series of pulses with a repetition rate of one pulse per five minutes are calculated based on the investigations performed. It is shown that the use of this amplifier at the exit of the existing laser can increase the output pulse energy from 300 to 600 J. (lasers)

  4. Bi-phasic titanium dioxide nanoparticles doped with nitrogen and neodymium for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Gomez, Virginia; Bear, Joseph C.; McNaughter, Paul D.; McGettrick, James D.; Watson, Trystan; Charbonneau, Cecile; O'Brien, Paul; Barron, Andrew R.; Dunnill, Charles W.

    2015-10-01

    Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with ``Janus-like'' characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co-doped particles under white light.Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with ``Janus-like'' characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co

  5. Retinal detachment as a complication of neodymium: yttrium aluminum garnet laser cyclophotocoagulation.

    PubMed

    Geyer, O; Neudorfer, M; Lazar, M

    1993-05-01

    We report a traction retinal detachment that developed within one month of transscleral neodymium: yttrium aluminum garnet (Nd:YAG) laser cyclophotocoagulation, a previously unreported complication of the new cyclodestructive procedure. A 17-year-old boy was referred to our department with uncontrolled aphakic glaucoma OD after having undergone cyclocryotherapy twice. Three treatments with transscleral Nd:YAG cyclophotocoagulation were done over nine months to lower his intraocular pressure. Hypotony and traction retinal detachment occurred after the third laser treatment and was managed successfully by vitrectomy with a fluid-gas exchange. Thus, the possibility of this additional complication should be remembered when doing transscleral Nd:YAG cyclophotocoagulation. PMID:8517586

  6. Classifying sex biased congenital anomalies

    SciTech Connect

    Lubinsky, M.S.

    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.

  7. Genetics Home Reference: Peters anomaly

    MedlinePlus

    ... the anterior segment is abnormal, leading to incomplete separation of the cornea from the iris or the ... anomaly type I is characterized by an incomplete separation of the cornea and iris and mild to ...

  8. 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.

  9. Satellite elevation magnetic anomaly maps

    NASA Technical Reports Server (NTRS)

    Braile, L. W.; Hinze, W. J. (Principal Investigator)

    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. Anodic behavior of alloys in the systems aluminum-scandium(yttrium, praseodymium, neodymium) in a neutral medium

    SciTech Connect

    Ganiev, I.N.; Yunusov, I.; Krasnoyarskii, V.V.

    1988-03-10

    The authors investigated the influence of scandium, yttrium, praseodymium, and neodymium on the anodic behavior of aluminum in a 3% sodium chloride solution by a potentiodynamic method which provided information over a time interval during which the state of the electrode surface and the composition of the solution remained essentially unchanged. Data were derived for electrochemical and pitting corrosion for different alloy contents and compositions. Results were analyzed for aluminum-scandium, aluminum-yttrium, aluminum-praseodymium, and aluminum-neodymium binary systems.

  11. Aeromagnetic anomalies over faulted strata

    USGS Publications Warehouse

    Grauch, V.J.S.; Hudson, Mark R.

    2011-01-01

    High-resolution aeromagnetic surveys are now an industry standard and they commonly detect anomalies that are attributed to faults within sedimentary basins. However, detailed studies identifying geologic sources of magnetic anomalies in sedimentary environments are rare in the literature. Opportunities to study these sources have come from well-exposed sedimentary basins of the Rio Grande rift in New Mexico and Colorado. High-resolution aeromagnetic data from these areas reveal numerous, curvilinear, low-amplitude (2–15 nT at 100-m terrain clearance) anomalies that consistently correspond to intrasedimentary normal faults (Figure 1). Detailed geophysical and rock-property studies provide evidence for the magnetic sources at several exposures of these faults in the central Rio Grande rift (summarized in Grauch and Hudson, 2007, and Hudson et al., 2008). A key result is that the aeromagnetic anomalies arise from the juxtaposition of magnetically differing strata at the faults as opposed to chemical processes acting at the fault zone. The studies also provide (1) guidelines for understanding and estimating the geophysical parameters controlling aeromagnetic anomalies at faulted strata (Grauch and Hudson), and (2) observations on key geologic factors that are favorable for developing similar sedimentary sources of aeromagnetic anomalies elsewhere (Hudson et al.).

  12. Overgrowth syndromes with vascular anomalies.

    PubMed

    Blei, Francine

    2015-04-01

    Overgrowth syndromes with vascular anomalies encompass entities with a vascular anomaly as the predominant feature vs those syndromes with predominant somatic overgrowth and a vascular anomaly as a more minor component. The focus of this article is to categorize these syndromes phenotypically, including updated clinical criteria, radiologic features, evaluation, management issues, pathophysiology, and genetic information. A literature review was conducted in PubMed using key words "overgrowth syndromes and vascular anomalies" as well as specific literature reviews for each entity and supportive genetic information (e.g., somatic mosaicism). Additional searches in OMIM and Gene Reviews were conducted for each syndrome. Disease entities were categorized by predominant clinical features, known genetic information, and putative affected signaling pathway. Overgrowth syndromes with vascular anomalies are a heterogeneous group of disorders, often with variable clinical expression, due to germline or somatic mutations. Overgrowth can be focal (e.g., macrocephaly) or generalized, often asymmetrically (and/or mosaically) distributed. All germ layers may be affected, and the abnormalities may be progressive. Patients with overgrowth syndromes may be at an increased risk for malignancies. Practitioners should be attentive to patients having syndromes with overgrowth and vascular defects. These patients require proactive evaluation, referral to appropriate specialists, and in some cases, early monitoring for potential malignancies. Progress in identifying vascular anomaly-related overgrowth syndromes and their genetic etiology has been robust in the past decade and is contributing to genetically based prenatal diagnosis and new therapies targeting the putative causative genetic mutations. PMID:25937473

  13. Isotope separation

    DOEpatents

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  14. Optical properties of a binuclear neodymium complex in phosphorus oxychloride for liquid laser

    NASA Astrophysics Data System (ADS)

    Zhang, Guofang; She, Jiangbo; Han, Kai; Nie, Rongzhi; Li, Dongdong; Peng, Bo

    2015-11-01

    A novel binuclear neodymium complex Nd(CF3COO)3·(Ph3PO)2 (Ph3PO: triphenylphosphine oxide) with high stimulated emission cross-section was presented. The molecular structure of the complex was characterized by single-crystal X-ray diffraction. The optical properties of the complex in liquid medium were studied. From the absorption and luminescence spectra, the Judd-Ofelt parameters of Nd(CF3COO)3·(Ph3PO)2 in phosphorus oxychloride were obtained. Based on the crystal structure, the effects of crystal field and bonding valence properties on three intensity parameters Ωt(t = 2, 4, 6) and emission cross-section were analyzed in detail. The emission cross-section of 4F3/2 → 4I11/2 fluorescence transition (2.78 × 10-20 cm2) of the new neodymium compound was higher than those of other Nd(III) complexes and even comparable with some laser glasses.

  15. Neodymium doped hydroxyapatite theranostic nanoplatforms for colon specific drug delivery applications.

    PubMed

    Victor, Sunita Prem; Paul, Willi; Vineeth, V M; Komeri, Remya; Jayabalan, Muthu; Sharma, Chandra P

    2016-09-01

    Theranostic nanoplatforms integrate therapeutic payloads with diagnostic agents, and help monitor therapeutic response. In this regard, stimuli responsive nanoplatforms further favour combinatorial therapeutic approach that can considerably improve efficacy and specificity of treatment. Herein, we present the engineering of a smart theranostic nanoplatform based on neodymium doped hydroxyapatite (HAN). The presence of neodymium endows the HAN nanoplatforms with near-infrared fluorescence capability. These HAN nanoparticles were then subsequently modified with alginic acid (HANA) to confer pH responsiveness to the synthesized nanoplatforms delivering them to the colon after oral administration. These nanoplatforms possessing optimum size, needle shaped morphology and negative zeta potential, are conducive to cellular internalization. On excitation at 410nm they exhibit near infrared emission at 670nm unraveling their theranostic capabilities. Cytotoxic effects systematically assessed using MTT and live dead assays reveal excellent viability. Raman microscopic imaging technique used to visualize uptake in HeLa cells demonstrate increased uptake from 4 to 16h, with growing cluster size and localization in the cytoplasm. Moreover the concomitant presence of alginic acid manifested advantages of augmented loading and pH dependent release profiles of the model drug, 4 acetyl salicylic acid (4ASA). We could thus establish a theranostic system for early tumour detection, targeted tumour therapy and monitoring of colon cancer that can be administered via the oral route. PMID:27281239

  16. Preparation of carbon nanotube-neodymium oxide composite and research on its catalytic performance

    SciTech Connect

    Zhao Lei; Wang Zhihua; Han Dongmei; Tao Dongliang; Guo Guangsheng

    2009-05-06

    Carbon Nanotube-Neodymium Oxide (CNT-Nd{sub 2}O{sub 3}) composite was prepared by using acid treated carbon nanotubes (CNTs) and neodymium nitrate in the presence of sodium dodecyl sulfate and ammonia liquid. Techniques of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) are used to characterize the morphology, structure, composition and catalytic property of the CNT-Nd{sub 2}O{sub 3} composite. The experimental results show that the Nd{sub 2}O{sub 3} nanoparticles, which have an average diameter of about 30-40 nm, are loaded on the surface of carbon nanotube. Compared with pure Nd{sub 2}O{sub 3} nanorods, the CNT-Nd{sub 2}O{sub 3} composite can catalyze the thermal decomposition of ammonium perchlorate more effectively. The sampling methods of the experimental samples made a difference on the catalytic experiment results, and the best catalytic result was obtained when de-ionized water served as the solvent of ammonium perchlorate.

  17. First clinical experience with a Q-switched neodymium:YAG laser for urinary calculi.

    PubMed

    Hofmann, R; Hartung, R; Schmidt-Kloiber, H; Reichel, E

    1989-02-01

    Animal studies using a high intensity nanosecond pulsed neodymium:YAG laser did not reveal any serious tissue damage. Following these investigations patient treatment was begun in June 1987. Laser energy of a neodymium:YAG laser with an 8 nsec. pulse duration and a repetition rate of up to 50 Hz. was coupled into a flexible 600 resp. 400 micron. quartz fiber. Laser-induced breakdown was created with 35 to 50 mJ. at the fiber tip, resulting in a shock wave that disintegrated the calculus into tiny fragments. A total of 56 patients with 58 calculi (54 ureteral and 4 kidney stones) was treated from June 1987 to March 1988. Of the calculi 48 could be fragmented completely, while 6 others were reduced to a size small enough to be removed with forceps. Four stones composed of calcium oxalate monohydrate could not be disintegrated. The combination of laser stone disintegration with flexible ureterorenoscopy implies the possibility of an atraumatic, 1-step procedure for fragmentation of ureteral and kidney calculi. PMID:2563297

  18. Investigation of Carboxylic Acid-Neodymium Conversion Films on Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Cui, Xiufang; Liu, Zhe; Lin, Lili; Jin, Guo; Wang, Haidou; Xu, Binshi

    2015-01-01

    The new carboxylic acid-neodymium anhydrous conversion films were successfully prepared and applied on the AZ91D magnesium alloy surface by taking absolute ethyl alcohol as solvent and four kinds of soluble carboxylic acid as activators. The corrosion resistance of the coating was measured by potentiodynamic polarization test in 3.5 wt.% NaCl solution in pH 7.0. The morphology, structure, and constituents of the coating were observed by scanning electron microscope, energy dispersivespectrum, x-ray photoelectron spectrum, and Fourier infrared spectrometer. Results show that corrosion resistance properties of samples coated with four different anhydrous conversion films were improved obviously. The corrosion potential increased, corrosion current density decreased, and polarization resistance increased. Among these four kinds of conversion films the one added with phytic exhibits the best corrosion resistant property. The mechanism of anhydrous-neodymium conversion film formation is also analyzed in this paper. It reveals that the gadolinium conversion coating is mainly composed of stable Nd2O3, MgO, Mg(OH)2, and carboxylate of Nd. And that the sample surface is rich in organic functional groups.

  19. Toward Baseline Software Anomalies in NASA Missions

    NASA Technical Reports Server (NTRS)

    Layman, Lucas; Zelkowitz, Marvin; Basili, Victor; Nikora, Allen P.

    2012-01-01

    In this fast abstract, we provide preliminary findings an analysis of 14,500 spacecraft anomalies from unmanned NASA missions. We provide some baselines for the distributions of software vs. non-software anomalies in spaceflight systems, the risk ratings of software anomalies, and the corrective actions associated with software anomalies.

  20. 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.

  1. Rapid, quantitative analysis of americium, curium and plutonium isotopes in Hanford samples using extraction chromatography and precipitation plating

    SciTech Connect

    Kaye, J.H.; Strebin, R.S.; Orr, R.D.

    1994-04-01

    Recently developed methods for the rapid, quantitative analysis of americium (Am), curium (Cm), and plutonium (Pu) isotopes in Hanford soil, sludge, and waste-tank samples are described. After dissolution, dilutions are made as necessary based on alpha-energy analysis of a small aliquot of the original solution. isotopic tracers are then added and Am-Cm and Pu are separated by extraction chromatography, coprecipitated with neodymium fluoride, and counted. Examples of alpha spectra are given, and results obtained for Hanford sludge samples are presented.

  2. Non-relativistic scale anomalies

    NASA Astrophysics Data System (ADS)

    Arav, Igal; Chapman, Shira; Oz, Yaron

    2016-06-01

    We extend the cohomological analysis in arXiv:1410.5831 of anisotropic Lifshitz scale anomalies. We consider non-relativistic theories with a dynamical critical exponent z = 2 with or without non-relativistic boosts and a particle number symmetry. We distinguish between cases depending on whether the time direction does or does not induce a foliation structure. We analyse both 1 + 1 and 2 + 1 spacetime dimensions. In 1 + 1 dimensions we find no scale anomalies with Galilean boost symmetries. The anomalies in 2 + 1 dimensions with Galilean boosts and a foliation structure are all B-type and are identical to the Lifshitz case in the purely spatial sector. With Galilean boosts and without a foliation structure we find also an A-type scale anomaly. There is an infinite ladder of B-type anomalies in the absence of a foliation structure with or without Galilean boosts. We discuss the relation between the existence of a foliation structure and the causality of the field theory.

  3. Experimental Anomalies in Neutrino Physics

    NASA Astrophysics Data System (ADS)

    Palamara, Ornella

    2014-03-01

    In recent years, experimental anomalies ranging in significance (2.8-3.8 σ) have been reported from a variety of experiments studying neutrinos over baselines less than 1 km. Results from the LSND and MiniBooNE short-baseline νe /νe appearance experiments show anomalies which cannot be described by oscillations between the three standard model neutrinos (the ``LSND anomaly''). In addition, a re-analysis of the anti-neutrino flux produced by nuclear power reactors has led to an apparent deficit in νe event rates in a number of reactor experiments (the ``reactor anomaly''). Similarly, calibration runs using 51Cr and 37Ar radioactive sources in the Gallium solar neutrino experiments GALLEX and SAGE have shown an unexplained deficit in the electron neutrino event rate over very short distances (the ``Gallium anomaly''). The puzzling results from these experiments, which together may suggest the existence of physics beyond the Standard Model and hint at exciting new physics, including the possibility of additional low-mass sterile neutrino states, have raised the interest in the community for new experimental efforts that could eventually solve this puzzle. Definitive evidence for sterile neutrinos would be a revolutionary discovery, with implications for particle physics as well as cosmology. Proposals to address these signals by employing accelerator, reactor and radioactive source experiments are in the planning stages or underway worldwide. In this talk some of these will be reviewed, with emphasis on the accelerator programs.

  4. Origin of the DUPAL anomaly in mantle xenoliths of Patagonia (Argentina) and geodynamic consequences

    NASA Astrophysics Data System (ADS)

    Mazzucchelli, Maurizio; Cipriani, Anna; Hémond, Christophe; Zanetti, Alberto; Bertotto, Gustavo Walter; Cingolani, Carlos Alberto

    2016-04-01

    The sub-continental lithospheric mantle of South America has been known for some time to carry the DUPAL isotope anomaly as seen in volcanics from the Paraná volcanic province. However, this has not allowed discriminating whether the DUPAL anomaly is a primary feature of the mantle source or acquired during the upwelling and emplacement of the primary magmas. We discovered mantle xenoliths from the Tres Lagos location in Patagonia that carry evidence of percolation by metasomatic melts that imparted the DUPAL isotope anomaly signature. We discuss a model that requires four isotope components (LCC, EM2, HIMU and DM) to account for the Sr, Nd and Pb isotope variability of our samples. We propose that upwelling of hot astenosphere during the Miocene could have triggered the melting of the LCC and EM2 components carrying the DUPAL anomaly, previously entrained in the subcontinental mantle by subduction. These ascending melts would have then metasomatised the local SCLM characterised by DMM and HIMU geochemical affinity generating the hybrid DUPAL-bearing mantle sampled by the Tres Lagos xenoliths.

  5. Measuring anomaly with algorithmic entropy

    NASA Astrophysics Data System (ADS)

    Solano, Wanda M.

    Anomaly detection refers to the identification of observations that are considered outside of normal. Since they are unknown to the system prior to training and rare, the anomaly detection problem is particularly challenging. Model based techniques require large quantities of existing data are to build the model. Statistically based techniques result in the use of statistical metrics or thresholds for determining whether a particular observation is anomalous. I propose a novel approach to anomaly detection using wavelet based algorithmic entropy that does not require modeling or large amounts of data. My method embodies the concept of information distance that rests on the fact that data encodes information. This distance is large when little information is shared, and small when there is greater information sharing. I compare my approach with several techniques in the literature using data obtained from testing of NASA's Space Shuttle Main Engines (SSME)

  6. 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.

  7. Graph anomalies in cyber communications

    SciTech Connect

    Vander Wiel, Scott A; Storlie, Curtis B; Sandine, Gary; Hagberg, Aric A; Fisk, Michael

    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.

  8. Boundary terms of conformal anomaly

    NASA Astrophysics Data System (ADS)

    Solodukhin, Sergey N.

    2016-01-01

    We analyze the structure of the boundary terms in the conformal anomaly integrated over a manifold with boundaries. We suggest that the anomalies of type B, polynomial in the Weyl tensor, are accompanied with the respective boundary terms of the Gibbons-Hawking type. Their form is dictated by the requirement that they produce a variation which compensates the normal derivatives of the metric variation on the boundary in order to have a well-defined variational procedure. This suggestion agrees with recent findings in four dimensions for free fields of various spins. We generalize this consideration to six dimensions and derive explicitly the respective boundary terms. We point out that the integrated conformal anomaly in odd dimensions is non-vanishing due to the boundary terms. These terms are specified in three and five dimensions.

  9. 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

  10. The questa magmatic system: Petrologic, chemical and isotopic variations in cogenetic volcanic and plutonic rocks of the latir volcanic field and associated intrusives, northern New Mexico

    SciTech Connect

    Johnson, C.M.

    1986-01-01

    Field, chemical and isotopic data demonstrate that nearly all igneous rocks at Questa resulted from interactions between mantle-derived parental magmas and the crust. Strontium, neodymium and lead isotope ratios of early andesites to rhyolites (28 to 26 Ma) indicate that these magmas assimilated > 25% lower crust. Injection of basaltic magmas extensively modified the strontium and neodymium but not the lead isotope compositions of the lower crust. Eruption of comendite magmas and the peralkaline Amalia Tuff 26 Ma is correlated with inception of regional extension. Lead isotope ratios identify different sources for the metaluminous granites and the peralkaline rocks. 26 Ma metaluminous granite to granodiorite intrusions have chemical and isotopic compositions to those of the precaldera intermediate-composition rocks, and are interpreted as representing the solidified equivalents of the precaldera magmatic episode. However, both conventional and ion-microprobe isotopic data prohibit significant assimilation of crustal rocks at the level of exposure, suggesting that the plutons were emplaced a relatively crystal-rich mushes which did not have sufficient heat to assimilate country rocks. This suggest that in some cases plutonic rocks are better than volcanic rocks in representing the isotopic compositions of their source regions, because the assimilation potential of crystal-rich magmas is significantly less than that of largely liquid magmas.

  11. Ru isotope heterogeneity in the solar protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Fischer-Gödde, Mario; Burkhardt, Christoph; Kruijer, Thomas S.; Kleine, Thorsten

    2015-11-01

    Nucleosynthetic isotope anomalies in bulk chondrites and differentiated meteorites reflect variable proportions of isotopically diverse presolar components in bulk planetary bodies, but the origin of these heterogeneities is not well understood. Here, the Ru isotope composition of a comprehensive suite of iron meteorites and bulk samples of ordinary, enstatite and carbonaceous chondrites, as well as acid leachates and an insoluble residue of the Allende chondrite are examined using newly developed multi-collector inductively coupled plasma mass spectrometry techniques. Except for IAB iron meteorites and enstatite chondrites, all investigated meteorites show well-resolved Ru isotope anomalies. Of these, within-group Ru isotopic variations observed for samples from a given chemical group of iron meteorites reflect secondary neutron capture induced Ru isotope shifts during prolonged cosmic ray-exposure. After correction of these cosmogenic effects using Pt isotopes as a neutron-dose monitor, the remaining Ru isotope anomalies are nucleosynthetic in nature and are consistent with a deficit in s-process Ru in iron meteorite parent bodies. Similarly, Ru isotope anomalies in bulk ordinary and carbonaceous chondrites also reflect a deficiency in s-process Ru. The sequential dissolution of Allende reveals the presence of an HF-soluble s-process carrier, which is either an unidentified presolar phase or a component that incorporated s-process Ru liberated from SiC grains during nebular or parent body processes. We show that varying proportions of the s-process carrier identified in Allende resulted in the correlated Ru isotope anomalies observed for bulk meteorites, and that all meteorites (except possibly IAB irons and enstatite chondrites) are depleted in this s-process component relative to Ru from the Earth's mantle. Bulk meteorites exhibit correlated Ru and Mo isotope anomalies, reflecting variable deficits of a common s-process component, but some iron meteorites and

  12. Genetic basis for vascular anomalies.

    PubMed

    Kirkorian, A Yasmine; Grossberg, Anna L; Püttgen, Katherine B

    2016-03-01

    The fundamental genetics of many isolated vascular anomalies and syndromes associated with vascular anomalies have been elucidated. The rate of discovery continues to increase, expanding our understanding of the underlying interconnected molecular pathways. This review summarizes genetic and clinical information on the following diagnoses: capillary malformation, venous malformation, lymphatic malformation, arteriovenous malformation, PIK3CA-related overgrowth spectrum (PROS), Proteus syndrome, SOLAMEN syndrome, Sturge-Weber syndrome, phakomatosis pigmentovascularis, congenital hemangioma, verrucous venous malformation, cutaneomucosal venous malformation, blue rubber bleb nevus syndrome, capillary malformation-arteriovenous malformation syndrome, Parkes-Weber syndrome, and Maffucci syndrome. PMID:27607321

  13. Boundary anomalies and correlation functions

    NASA Astrophysics Data System (ADS)

    Huang, Kuo-Wei

    2016-08-01

    It was shown recently that boundary terms of conformal anomalies recover the universal contribution to the entanglement entropy and also play an important role in the boundary monotonicity theorem of odd-dimensional quantum field theories. Motivated by these results, we investigate relationships between boundary anomalies and the stress tensor correlation functions in conformal field theories. In particular, we focus on how the conformal Ward identity and the renormalization group equation are modified by boundary central charges. Renormalized stress tensors induced by boundary Weyl invariants are also discussed, with examples in spherical and cylindrical geometries.

  14. Environmental Hf-Nd isotopic decoupling in World river clays

    NASA Astrophysics Data System (ADS)

    Bayon, Germain; Skonieczny, Charlotte; Delvigne, Camille; Toucanne, Samuel; Bermell, Sylvain; Ponzevera, Emmanuel; André, Luc

    2016-03-01

    The hafnium and neodymium radiogenic isotope systems behave differently during Earth surface processes, causing a wide dispersion of Hf and Nd isotopic compositions in sediments and other sedimentary rocks. The decoupling between Hf and Nd isotopes in sediments is generally attributed to a combination of preferential sorting of zircon during sediment transport and incongruent weathering processes on continents. In this study, we analysed size-fractions of sediment samples collected near the mouth of 53 rivers worldwide to better understand the factors controlling the distribution of Hf and Nd isotopes in sediments. Our results for rivers draining old cratonic areas and volcanic provinces demonstrate that both granite and basalt weathering can lead to significant grain-size dependent Hf isotopic variability. While silt-size fractions mainly plot along the Terrestrial Array, World river clays are systematically shifted towards more radiogenic Hf isotopic compositions, defining together with published data a new Clay Array (εHf = 0.78 ×εNd + 5.23). The Hf-Nd isotope decoupling observed in volcanogenic sediments is best explained by selective alteration of Lu-rich mineral phases (e.g. olivine) and preferential enrichment of resistant unradiogenic minerals, such as spinel and ilmenite, in silt fractions. We also show that the extent to which World river clays deviate from the Clay Array (ΔεHf clay) is not linked to the presence of zircons. Instead, it correlates positively with weathering indices and climatic parameters (temperature, rainfall) of the corresponding drainage basins. Overall, these findings demonstrate that the distribution of Hf-Nd isotopes in clay-size sediments is related to a large extent to weathering conditions on continents, although the precise mechanisms controlling this relationship remain unclear. We finally propose that the Hf-Nd isotope pair proxy could be used in palaeoenvironmental studies to provide semi-quantitative information on

  15. Photoacoustic spectroscopy study of neodymium complexes with alanine, valine, phenylalanine and tryptophan.

    PubMed

    Yang, Yuetao; Zhang, Shuyi

    2003-04-01

    Neodymium complexes with amino acids: Nd(Ala)(3)Cl(3).3H(2)O, Nd(Val)(3)Cl(3).3H(2)O, Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O (Ala: L-alanine, Val: L-valine, Phe: L-phenylalanine, Trp: L-tryptophan) are synthesized and their photoacoustic (PA) spectra are reported. The nephelauxetic ratio beta, bonding parameter b(1/2) and Sinha parameter delta are calculated based on their PA spectra. The variation of these parameters and correlation of them with the nature of metal-ligand bonding are discussed. The PA intensity analysis of the f-f transitions of neodymium ion is carried out by calculating the intensity branching vector. The environmental effect on the f-f transitions of neodymium ion is also studied. The branching vectors of the f-f transitions of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O are similar, which indicates the perturbation of the two ligand fields is similar. The branching vectors of energy levels 4G(5/2)+(2)G(7/2) of Nd(Phe)Cl(3).5H(2)O and Nd(Trp)(3)Cl(3).3H(2)O increase remarkably compared with those of Nd(Ala)(3)Cl(3).3H(2)O and Nd(Val)(3)Cl(3).3H(2)O. As the degree of covalency increases, the oscillator strength of the hypersensitive transition exhibits a corresponding increase. The relaxation process of Nd(Ala)(3)Cl(3).3H(2)O is established through its PA and electron absorption spectroscopy (EAS). A method used to resolve the PA amplitude spectrum is suggested. With the phase spectrum, PA absorption bands of Nd(Trp)(3)Cl(3).3H(2)O are resolved well in the region of ligand absorption. PMID:12659889

  16. IUPAC Project: Terminology and definition of quantities related to the isotope distribution in elements with more than two stable isotopes

    NASA Astrophysics Data System (ADS)

    Kaiser, J.; Angert, A.; Bergquist, B.; Brand, W.; Ono, S.; Röckmann, T.; Savarino, J.

    2012-04-01

    The objective of IUPAC Project 2009-046-2-200 (http://www.iupac.org/web/ins/2009-046-2-200) is to define terminology and to identify the most suitable definitions of quantities that characterise the isotope distribution in elements with more than two stable isotopes, including so-called mass-independent fractionation, non-mass dependent fractionation, isotope anomaly, 17O excess, etc. Most atmospheric oxygen-bearing species show deviations in their triple oxygen isotope ratios from mass-dependent fractionation (MDF) relationships predicted by the theories of Urey, Bigeleisen and Mayer. Similar deviations have also been found in sulphur and other elements with more than two stables isotopes (e.g. Hg, Cd, Zn), often preserved in non-atmospheric reservoirs, including rocks, minerals, soils, ice and waters. Despite the ubiquity of this type of isotope anomaly, there has never been an attempt to clearly define the terminology and physical quantities used to measure these anomalies and the processes that lead to their formation. Terms like mass-independent fractionation, non-mass dependent fractionation, isotope anomaly, isotope excess etc. have been used in the historic and recent literature, but are often not carefully distinguished. The realisation that MDF comprises a range of possible relationships between the isotopes of one element led to further complications because it meant that apparent isotope anomalies could be created by a combination of different MDF processes. At the moment, at least four different definitions to quantify isotope anomalies are being used. Furthermore, coefficients used in these definitions vary, which makes the comparison of data from different sources very difficult, even for experts. A consistent set of recommendations on how to express and quantify the isotope distribution in elements with more than two stable isotopes is highly warranted. From our experience as academic teachers, we are woefully aware how impenetrable the field is for

  17. Observational manifestations of anomaly inflow

    SciTech Connect

    Boyarsky, Alexey; Shaposhnikov, Mikhail

    2005-10-15

    In theories with chiral couplings, one of the important consistency requirements is that of the cancellation of a gauge anomaly. In particular, this is one of the conditions imposed on the hypercharges in the standard model. However, anomaly cancellation condition of the standard model looks unnatural from the perspective of a theory with extra dimensions. Indeed, if our world were embedded into an odd-dimensional space, then the full theory would be automatically anomaly-free. In this paper we discuss the physical consequences of anomaly noncancellation for effective 4-dimensional field theory. We demonstrate that in such a theory parallel electric and magnetic fields get modified. In particular, this happens for any particle possessing both electric charge and magnetic moment. This effect, if observed, can serve as a low energy signature of extra dimensions. On the other hand, if such an effect is absent or is very small, then from the point of view of any theory with extra dimensions it is just another fine-tuning and should acquire theoretical explanation.

  18. Thermal anomalies in stressed Teflon.

    NASA Technical Reports Server (NTRS)

    Lee, S. H.; Wulff, C. A.

    1972-01-01

    In the course of testing polytetrafluoroethylene (Teflon) as a calorimetric gasketing material, serendipity revealed a thermal anomaly in stressed film that occurs concomitantly with the well-documented 25 C transition. The magnitude of the excess energy absorption - about 35 cal/g - is suggested to be related to the restricted thermal expansion of the film.

  19. 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...

  20. Numerical anomalies mimicking physical effects

    NASA Astrophysics Data System (ADS)

    Menikoff, R.

    Numerical simulations of flows with shock waves typically use finite-difference shock-capturing algorithms. These algorithms give a shock a numerical width in order to generate the entropy increase that must occur across a shock wave. For algorithms in conservation form, steady-state shock waves are insensitive to the numerical dissipation because of the Hugoniot jump conditions. However, localized numerical errors occur when shock waves interact. Examples are the 'excess wall heating' in the Noh problem (shock reflected from rigid wall), errors when a shock impacts a material interface or an abrupt change in mesh spacing, and the start-up error from initializing a shock as a discontinuity. This class of anomalies can be explained by the entropy generation that occurs in the transient flow when a shock profile is formed or changed. The entropy error is localized spatially but under mesh refinement does not decrease in magnitude. Similar effects have been observed in shock tube experiments with partly dispersed shock waves. In this case, the shock has a physical width due to a relaxation process. An entropy anomaly from a transient shock interaction is inherent in the structure of the conservation equations for fluid flow. The anomaly can be expected to occur whenever heat conduction can be neglected and a shock wave has a non-zero width, whether the width is physical or numerical. Thus, the numerical anomaly from an artificial shock width mimics a real physical effect.

  1. Hyperfine Anomalies in Fr: Boundaries of the Spherical Single Particle Model

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    We have measured the hyperfine splitting of the 7 P1 /2 state at the 100 ppm level in Fr isotopes (206g,206m,207,209,213,221Fr) near the closed neutron shell (N =126 in 213Fr). The measurements in five isotopes and a nuclear isomeric state of francium, combined with previous determinations of the 7 S1 /2 splittings, reveal the spatial distribution of the nuclear magnetization, i.e., the Bohr-Weisskopf effect. We compare our results with a simple shell model consisting of unpaired single valence nucleons orbiting a spherical nucleus, and find good agreement over a range of neutron-deficient isotopes (207-213Fr). Also, we find near-constant proton anomalies for several even-N isotopes. This identifies a set of Fr isotopes whose nuclear structure can be understood well enough for the extraction of weak interaction parameters from parity nonconservation studies.

  2. Hyperfine Anomalies in Fr: Boundaries of the Spherical Single Particle Model.

    PubMed

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

    2015-07-24

    We have measured the hyperfine splitting of the 7P_{1/2} state at the 100 ppm level in Fr isotopes (^{206g,206m,207,209,213,221}Fr) near the closed neutron shell (N=126 in ^{213}Fr). The measurements in five isotopes and a nuclear isomeric state of francium, combined with previous determinations of the 7S_{1/2} splittings, reveal the spatial distribution of the nuclear magnetization, i.e., the Bohr-Weisskopf effect. We compare our results with a simple shell model consisting of unpaired single valence nucleons orbiting a spherical nucleus, and find good agreement over a range of neutron-deficient isotopes (^{207-213}Fr). Also, we find near-constant proton anomalies for several even-N isotopes. This identifies a set of Fr isotopes whose nuclear structure can be understood well enough for the extraction of weak interaction parameters from parity nonconservation studies. PMID:26252677

  3. Influence of the Mediterranean outflow on the isotopic composition of neodymium in waters of the North Atlantic

    NASA Technical Reports Server (NTRS)

    Piepgras, D. J.; Wasserburg, G. J.

    1983-01-01

    Measurements of the Nd-143/Nd-144 ratio, expressed as epsilon-Nd(0), made in sea water samples obtained at depths from 0 to 4850 m at stations 95, 101, and 30 of North-Atlantic cruise 109-1 of the RV Atlantis II are reported and analyzed. In the 1000-m sample at station 95, determined by salinity, O2, PO4, NO3, SiO2, potential-temperature, and pressure profiles to correspond to the core of the Mediterranean outflow, an epsilon-Nd(0) value of -9.8 + or - 0.6 was found, a significant increase over the layers above and below, where epsilon-Nd(0) is about -12. Mixing estimations give a value for pure Mediterranean waters of approximately -6; continental drainage or volcanic deep-sea sediments are considered possible sources for this more radiogenic Nd. The epsilon-Nd(0) peak in the western North Atlantic (station 30) is found at the surface, and the deep waters are less radiogenic than in the eastern North Atlantic, suggesting multiple Nd sources. Possible origins and distribution mechanisms are discussed.

  4. Extraction chromatography of neodymium by an organophosphorous extractant supported on various polymeric resins

    SciTech Connect

    Takigawa, D.Y.

    1993-04-01

    Fifteen resins coated with dihexyl-N,N-diethylcarbamoylmethyl phosphonate (CMP) were studied for their extraction of neodymium (Nd) in 4.0 and 7.0 M nitric acid. Resin properties, such as chemical composition and physical morphology, which can influence Nd extraction as well as subsequent resin regeneration (Nd stripping), were identified. Hydrophilic or polar resins coated with CMP efficiently extracted the Nd. Resins initially washed free of residual monomer and solvent before CMP coating outperformed their untreated counterparts. The macroporous styrene-divinylbenzene hydrophobic resins that were high in surface area were less effective supports compared with hydrophilic microporous Aurorez, polybenzimidazole (PBI) and macroporous Amberlite polyacrylic resins. Only one resin, Duolite C-467, showed no measurable improvement in Nd extraction with CMP coating. CMP-coated Aurorez PBI, a microporous and hydrophilic polymeric resin with an average surface area, showed the best overall efficiency for Nd removal and resin regeneration.

  5. Detection of Neodymium in APOGEE H-band Spectra and its Application to Chemical Tagging

    NASA Astrophysics Data System (ADS)

    Hasselquist, Sten; Shetrone, Matthew D.; Smith, Verne V.; Holtzman, Jon A.; Lawler, James E.; Ivans, Inese I.; Majewski, Steven R.; Schiavon, Ricardo P.; Zasowski, Gail; Nidever, David L.; Hearty, Fred; Allende-Prieto, Carlos; Beers, Timothy C.; García Pérez, Ana; Sobeck, Jennifer; Apogee Team

    2015-01-01

    We report the successful detection of the rare earth element Neodymium (Nd) in the high-resolution, H-band spectra from the SDSS III Apache Point Observatory Galactic Evolution Experiment (APOGEE). Using the Nd II transition at 16058.014 angstroms, we have detected significant Nd enhancements in all stars observed by APOGEE belonging to the Sagittarius (Sgr) Dwarf Spheroidal (dSph) galaxy. Because Sgr is known to be enhanced in heavy s-process elements such as Nd, we can use this feature to identify and chemically tag Sgr stream members that have been observed in the Galactic halo by APOGEE. We also use this feature to characterize rare earth element abundance variations in clusters observed by APOGEE.

  6. Vacuum Ultraviolet Field Emission Lamp Consisting of Neodymium Ion Doped Lutetium Fluoride Thin Film as Phosphor

    PubMed Central

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd3+ : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd3+ : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region. PMID:25302320

  7. Current status and future outlook for bonded neodymium permanent magnets (invited)

    NASA Astrophysics Data System (ADS)

    Croat, J. J.

    1997-04-01

    Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing range of computer peripheral, office automation, and consumer electronic applications and now constitute the fastest growing segment of the permanent magnet market. The current status of these materials will be reviewed. Included is a brief overview of the manufacture of these magnetically isotropic magnets and a discussion of their unique properties and features from the perspective of both bonded magnet producer and user. Major applications are discussed as are some of the factors that will drive the market for these materials in the future. New technical developments, including the status and outlook for anisotropic bonded materials, high remanance isotropic materials and high temperature bonded magnets will also be discussed.

  8. Spectroscopic Properties of Neodymium-Doped Yttrium Orthovanadate Single Crystals with High-Resolution Measurement

    NASA Astrophysics Data System (ADS)

    Sato, Yoichi; Taira, Takunori

    2002-10-01

    The absorption and fluorescence spectra of the neodymium-doped yttrium orthovanadate (Nd:YVO4) single crystal were investigated carefully. For the 808.8-nm absorption cross section, the published values varied between 18.4 and 25.6 × 10-20 cm2 for π-polarization. The authors evaluated this spectroscopic parameter with high resolution at 0.5 nm, and discovered 48.4 cm-1 at 808.8 nm even for the absorption of 1 at.% Nd3+-ion-doped YVO4 single crystal. This value is 1.3 times larger than the well-known value, and confirms that Nd:YVO4 is very suitable for microchip lasers, and that certain laser characteristics of Nd:YVO4 of previous works should be re-evaluated.

  9. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    NASA Astrophysics Data System (ADS)

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-01

    Gallium oxide and more particularly β-Ga2O3 matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  10. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    SciTech Connect

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-15

    Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  11. 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 (δ13Ccarb from 4 to 10 per mil), and stratigraphically extensive large negative carbon isotope excursions (δ13Ccarb < -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 δ13Cfossil 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 (δ13Ccarb < -3 per mil) and 3 different strata predating the Tayshir anomaly (δ13Ccarb > +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 (δ13Cfossil), with values of -23 ±1 per mil both within 13C-enriched and 13C-depleted carbonates. The

  12. Evidence of magnetic isotope effects during thermochemical sulfate reduction

    PubMed Central

    Oduro, Harry; Harms, Brian; Sintim, Herman O.; Kaufman, Alan J.; Cody, George; Farquhar, James

    2011-01-01

    Thermochemical sulfate reduction experiments with simple amino acid and dilute concentrations of sulfate reveal significant degrees of mass-independent sulfur isotope fractionation. Enrichments of up to 13‰ for 33S are attributed to a magnetic isotope effect (MIE) associated with the formation of thiol-disulfide, ion-radical pairs. Observed 36S depletions in products are explained here by classical (mass-dependent) isotope effects and mixing processes. The experimental data contrasts strongly with multiple sulfur isotope trends in Archean samples, which exhibit significant 36S anomalies. These results support an origin other than thermochemical sulfate reduction for the mass-independent signals observed for early Earth samples. PMID:21997216

  13. 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.

  14. Isotopic chirality

    SciTech Connect

    Floss, H.G.

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  15. 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.

  16. Large negative Ti-50 anomalies in refractory inclusions from the Murchison carbonaceous chondrite - Evidence for incomplete mixing of neutron-rich supernova ejecta into the solar system

    NASA Technical Reports Server (NTRS)

    Hinton, Richard W.; Davis, Andrew M.; Scatena-Wachel, Debra E.

    1987-01-01

    An ion microprobe was used to measure Ti-50 variations in hibonite-rich inclusions from the Murchison chondrite. Both deficits and excesses of the isotope were found, depending on the inclusion being scanned. The anomalies were not correlated with the mineralogy, chemical composition, other isotopic anomalies of Ti, etc. The lack of correlations indicates that the cosmic chemical memory model (Clayton, 1981) cannot explain the observed variations. The Ti-50 concentrations may have originated when a supernova explosion triggered the collapse of a molecular cloud that formed the solar system. The solar system Ti-50 anomalies were from the cloud, not the progenitor star.

  17. 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

  18. Anomaly constraints on monopoles and dyons

    SciTech Connect

    Csaki, Csaba; Shirman, Yuri; Terning, John

    2010-06-15

    Fermions with magnetic charges can contribute to anomalies. We derive the axial anomaly and gauge anomalies for monopoles and dyons, and find eight new gauge anomaly cancellation conditions in a general theory with both electric and magnetic charges. As a by-product, we also extend the Zwanziger two-potential formalism to include the {theta} parameter, and elaborate on the condition for CP invariance in theories with fermionic dyons.

  19. Loop anomalies in the causal approach

    NASA Astrophysics Data System (ADS)

    Grigore, Dan-Radu

    2015-01-01

    We consider gauge models in the causal approach and study one-loop contributions to the chronological products and the anomalies they produce. We prove that in order greater than 4 there are no one-loop anomalies. Next we analyze one-loop anomalies in the second- and third-order of the perturbation theory. We prove that the even parity contributions (with respect to parity) do not produce anomalies; for the odd parity contributions we reobtain the well-known result.

  20. The Palladium Isotopic Composition in Iron Meteorites

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Papanastassiou, D. A.

    2005-01-01

    Ru, Mo and Pd are very useful indicators for the identification of nucleosynthetic components. We have developed techniques for Pd isotopes, in an effort to check the extent of isotopic effects in this mass region and for a Pt-group element which is less refractory than Ru. Stable Pd isotopes are produced by the process only (102Pd), the s-process only (104Pd), the process only (Pd-110) and by both the r- and s-processes (Pd-105, Pd-106, Pd-108). Kelly and Wasserburg reported a hint of a shift in 102Pd (approx. 25(epsilon)u; 1(epsilon)u (triple bonds) 0.01%) in Santa Clara. Earlier searches for Mo and Ru isotopic anomalies were either positive or negative.

  1. Isotopic comparison of K/T boundary impact glass with melt rock from the Chicxulub and Manson impact structures

    NASA Astrophysics Data System (ADS)

    Blum, Joel D.; Chamberlain, C. P.; Hingston, Michael P.; Koeberl, Christian; Marin, Luis E.; Schuraytz, Benjamin C.; Sharpton, Virgil L.

    1993-07-01

    Strontium, neodymium, and oxygen isotopic compositions are reported for core samples of impact melt rock recovered from drill holes into the Chicxulub and Manson craters, which are candidate source craters for the catastrophic impact that occurred at the boundary between the Cretaceous and Tertiary periods (K/T boundary). The data are compared with previously published isotopic data from impact glasses from the K/T boundary of the Beloc formation in Haiti. It is found that the Chicxulub melt rocks are isotopically indistinguishable from the K/T impact glass, supporting the hypothesis that Chicxulub is a source crater for the K/T catastrophe. In contrast, the Manson melt rocks have a clearly different isotopic composition.

  2. 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.

  3. Model selection for anomaly detection

    NASA Astrophysics Data System (ADS)

    Burnaev, E.; Erofeev, P.; Smolyakov, D.

    2015-12-01

    Anomaly detection based on one-class classification algorithms is broadly used in many applied domains like image processing (e.g. detection of whether a patient is "cancerous" or "healthy" from mammography image), network intrusion detection, etc. Performance of an anomaly detection algorithm crucially depends on a kernel, used to measure similarity in a feature space. The standard approaches (e.g. cross-validation) for kernel selection, used in two-class classification problems, can not be used directly due to the specific nature of a data (absence of a second, abnormal, class data). In this paper we generalize several kernel selection methods from binary-class case to the case of one-class classification and perform extensive comparison of these approaches using both synthetic and real-world data.

  4. Inter-annual Variations and Trend Analyses of Precipitation and Vapor Isotopes with a Global Isotope Circulation Model and Observations

    NASA Astrophysics Data System (ADS)

    Yoshimura, K.; Oki, T.

    2006-12-01

    An atmosphere, land, sea surface, and river-coupled global isotope circulation model has been developed and it successfully reproduced spatial distribution of precipitation and vapor isotopes as well as those of "real" daily to inter-annual cycles provided by GNIP. A relationship between ENSO and simulated isotope ratio anomaly shows significant signals in DJF. They show lows in Greenland, southern USA and center of the Pacific, and highs in the northern North America, South America, and center of Asia in El Nino periods. Mostly vice versa in La Nina periods. In low latitude zones, it corresponds with the anomaly variations of precipitation amount, but in high latitudes, isotopes show original information on complex water circulation. Further investigation will be done by the presentation. Long-term trends of anomaly of precipitation isotopes are interesting, too. The observation show significant increase of precipitation isotope ratio over west Europe and the simulation agrees with it. Very simply speaking, when hydrologic cycle is enhanced, precipitation isotope will be increased, because the residence time of vapor becomes shorter. The trends in GNIP and the model is well agreed with Dirmeyer and Brubaker's (2006) finding the increase trend of recycling ratio in Northern Hemisphere. GNIP, we often regard it as "already understood", still has unknown to be tackled with.

  5. Pigmentary anomalies and hearing loss.

    PubMed

    Toriello, Helga V

    2011-01-01

    A number of syndromes that include hearing loss in the phenotype also have pigmentary anomalies as a component manifestation. One of the most common of these is Waardenburg syndrome, which includes hypopigmentation and sensorineural hearing loss in the phenotype. There are four types of Waardenburg syndrome, distinguishable from each other by clinical findings. However, there are several other syndromes which include not only hypopigmentation, but also hyperpigmentation in the phenotype. This paper serves as a review of many of these syndromes. PMID:21358185

  6. Cloacal anomaly with bladder tumor

    PubMed Central

    Seth, Amlesh; Ram, Ishwar

    2013-01-01

    A rare case of squamous cell carcinoma of bladder occurring in a 36-year-old female with persistent cloacal anomaly who presented with frequency, urgency, dysuria, and recurrent urinary tract infection is reported. Contrast Enhanced Computed Tomography with three dimensional reconstruction showed presence of bladder tumor and persistent cloaca. She underwent pelvic exenteration and wet colostomy. Histopathologic findings revealed locally advanced moderately differentiated squamous cell carcinoma. PMID:23956519

  7. Prenatal diagnosis of cloacal anomaly.

    PubMed

    Cacciaguerra, S; Lo Presti, L; Di Leo, L; Grasso, S; Gangarossa, S; Di Benedetto, V; Di Benedetto, A

    1998-02-01

    The authors present a case of prenatal diagnosis of cloacal anomaly, characterized by the presence of oligohydramnios and cystic pelvic mass with changing features during observation. Postnatal study confirmed the presence of a recto-cloacal fistula, with a high confluence of the urinary, genital and intestinal systems. Both parents had a chromosome 9 inversion (p11q13), but the child was chromosomally normal. PMID:9561584

  8. 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.

  9. Circum-Antarctic Nd isotope variability during the last 30 kyrs

    NASA Astrophysics Data System (ADS)

    Struve, T.; van de Flierdt, T.; Hines, S. K.; Burke, A.; Adkins, J. F.; Robinson, L. F.; Crocket, K. C.; Auro, M. E.

    2014-12-01

    The modern Southern Ocean is a key area for the global ocean circulation as wind-driven mixing, upwelling and redistribution of water masses in the Antarctic Circumpolar Current (ACC) all have a significant impact on the properties and flow patterns of global water masses. It has been suggested that the Southern Ocean plays a critical role in oceanographic and climatic changes observed on glacial-interglacial timescales, in particular with respect to carbon sequestration between the deep ocean and the atmosphere. For the purpose of unravelling Southern Ocean water mass composition at intermediate depth during the past 30 kyrs, we here utilise the Nd isotopic composition of the aragonitic skeletons of solitary deep-sea corals. These corals were collected from two locations, the Drake Passage and the area south of Tasmania, and from water depths between 300 and 1750 m. Modern coral specimen were calibrated against nearby seawater. Neodymium was collected from the wash fraction of the anion-exchange column, which represents the first step in preparing samples for precise U-series dating. Subsequent Nd separation utilised a two-stage ion chromatography (RE-spec/cation exchange and Ln-spec resins). Isotopic analyses were performed as NdO+ on a Triton TIMS using a TaF5 activator on W filaments yielding 2σ external reproducibilities of ~20 ppm. (Sub-) millenial scale deep-sea coral neodymium isotope results from the Drake Passage suggest that the modern homogenous ACC neodymium isotopic composition of ɛNd≈ -8 is a very recent feature. During the past 30 kyrs Nd isotope variability on the order of two epsilon units are observed at intermediate water depths as well as repeated changes in water column stratification. We will discuss our new results in the context of other Southern Ocean records, as well as preliminary Nd isotope data from glacial to deglacial deep-sea corals from south of Tasmania in order to constrain the last glacial to deglacial circum-Antarctic Nd

  10. 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.

  11. Compact, efficient, scalable neodymium laser co-doped with activator ions and pumped by visible laser diodes

    NASA Astrophysics Data System (ADS)

    Scheps, Richard

    1994-02-01

    Efficient, low threshold laser emission from a laser crystal doped with chromium and neodymium ions is obtained when pumped by visible laser diodes in the range of 610 nm to 680 nm. A typical laser Cr,Nd:GSGG crystal having an extraordinarily broad absorption bandwidth allows high pump efficiencies when using visible laser diodes, particularly in comparison to the Nd:YAG laser. The broad absorption bandwidth tolerance of the Cr,Nd:GSGG crystal to the pumping wavelengths allows visible diode pumping of the neodymium transition without regard to the wavelength of the visible diodes. Longitudinal or end-pumping to take advantage of the emission properties of the visible laser diodes, a nearly hemispherical laser resonator configuration and other co-doped Cr,Nd laser host materials are disclosed.

  12. Canadian Network for Isotopes in Precipitation (CNIP)and Isotope Climatology and Hydroclimatology in Canada

    NASA Astrophysics Data System (ADS)

    Birks, S. J.; Edwards, T. W.; Gibson, J. J.

    2002-12-01

    The distribution of stable isotopes in precipitation provides fundamental information about the partitioning of the global atmospheric water budget, and hence about key aspects of Earth's climate, that cannot be discerned using other means. Although continuing demand exists for monitoring of isotopes in precipitation to define isotopic input functions for local hydrologic studies or for calibration of isotopic indicators of paleoclimate, based on longterm averages and climatological norms, awareness is also growing of the significant value of the monthly snapshots of the precipitation isotope field provided by the IAEA/WMO Global Network for Isotopes in Precipitation and its affiliated national networks as benchmark maps of the ongoing and dynamic evolution of the global water cycle. An initiative within the Canadian Network for Isotopes in Precipitation program includes development of a spatial and temporal database incorporating Canadian data to create a gridded isotope overlay compatible with gridded pressure and flux field data from the NCAR/CDAS Re-analysis Project. This database includes interpolated fields of our current best approximations of climatological isotopic means in addition to the original monthly data for the period 1997-2000. Studies are underway to test the sensitivity of the isotope-climate signal in precipitation to changes in these parameters utilizing perturbations in local climate arising from the El Nino/Southern Oscillation (ENSO). Intriguing results have been obtained from preliminary studies incorporating pressure and flux field data for the 1997-98 El Nino with CNIP isotope overlays. The strongest climate anomalies were found during the winter following the 1997 El Nino event, consistent with the expected strengthening of the Pacific North American pattern during this period. Comparisons of the isotopic fields with climate fields illustrate the complexity and dynamic nature of isotope climate not evident in time-series of data from

  13. New isotopic clues to solar system formation

    NASA Technical Reports Server (NTRS)

    Lee, T.

    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 of planetary objects, which indicates that isotopic heterogeneities caused by the incomplete mixing of distinct nucleosynthesis components permeate the entire solar system. These new results have major implications for cosmochronology, nucleosynthesis theory, star formation, planetary heating, and the genetic relationship between different planetary bodies

  14. Neodymium glass laser with a pulse energy of 220 J and a pulse repetition rate of 0.02 Hz

    SciTech Connect

    Kuzmin, A A; Kulagin, O V; Khazanov, Efim A; Shaykin, A A

    2013-07-31

    A compact neodymium glass laser with a pulse energy of 220 J and a record-high pulse repetition rate of 0.02 Hz (pulse duration 30 ns) is developed. Thermally induced phase distortions are compensated using wave phase conjugation. The integral depolarisation of radiation is decreased to 0.4% by using linear compensation schemes. The second harmonic of laser radiation can be used for pumping Ti : sapphire multipetawatt complexes. (letters)

  15. Global anomalies and effective field theory

    NASA Astrophysics Data System (ADS)

    Golkar, Siavash; Sethi, Savdeep

    2016-05-01

    We show that matching anomalies under large gauge transformations and large diffeomorphisms can explain the appearance and non-renormalization of couplings in effective field theory. We focus on thermal effective field theory, where we argue that the appearance of certain unusual Chern-Simons couplings is a consequence of global anomalies. As an example, we show that a mixed global anomaly in four dimensions fixes the chiral vortical effect coefficient (up to an overall additive factor). This is an experimentally measurable prediction from a global anomaly. For certain situations, we propose a simpler method for calculating global anomalies which uses correlation functions rather than eta invariants.

  16. Stable platinum isotope measurements in presolar nanodiamonds by TEAMS.

    PubMed

    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 (198)Pt/(195)Pt 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

  17. 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

  18. ISOTOPE SEPARATORS

    DOEpatents

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  19. How Large is the Mass Independent O-17 Anomaly in the Atmosphere?

    NASA Astrophysics Data System (ADS)

    Luz, B.; Angert, A.; Barkan, E.; Bender, M. L.

    2002-12-01

    The isotopic composition of atmospheric oxygen is controlled by biological mechanisms, the hydrological cycle and stratospheric photochemistry. The biological mechanisms include photosynthetic oxygen production of identical isotopic composition as the substrate water and oxygen uptake by various mechanisms with mass dependent fractionation. Fractionation in the hydrological cycle is also mass dependent. In contrast, stratospheric photochemistry also removes oxygen, but fractionates the isotopic composition of the remaining gas in a mass-independent way. As a result atmospheric oxygen becomes anomalous (O-17 depleted) with respect to oxygen of the global atmosphere that would have been produced in the absence of stratospheric photochemistry. For estimating the magnitude of this anomaly, it is necessary to know the triple isotope fractionations of the relevant global processes. In the present research we carried out experiments in order to determine the ratio between the discriminations against O-17 and O-18 in dark respiration and in photorespiration. The obtained values are 0.518 and 0.506 respectively, and are different than in meteoric water fractionation (0.525). Assuming that the latter value applies to leaf-water (the substrate of all terrestrial photosynthesis), we estimate the magnitude of the anomaly as 258 permeg. This figure is significantly larger than 117 permeg estimated from stratospheric mass balance. Alternatively, by talking the 117 permeg value as representative of the anomaly, we calculate the ratio between the discriminations against O-17 and O-18 in leaf water as 0.511. Clearly, if we are to correctly estimate the atmospheric anomaly, careful determination of the triple isotope composition of global leaf-water is a prerequisite.

  20. 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.

  1. Trends in environmentally induced spacecraft anomalies

    NASA Technical Reports Server (NTRS)

    Wilkinson, Daniel C.

    1989-01-01

    The Spacecraft Anomaly Data Base was useful in identifying trends in anomaly occurrence. Trends alone do not provide quantitative testimony to a spacecraft's reliability, but they do indicate areas that command closer study. An in-depth analysis of a specific anomaly can be expensive and difficult without access to the spacecraft. Statistically verified anomaly trends can provide a good reference point to begin anomaly analysis. Many spacecraft experience an increase in anomalies during the period of several days centered on the solar equinox, a period that is also correlated with sun eclipse at geostationary altitude and an increase in major geomagnetic storms. Increase anomaly occurrence can also be seen during the local time interval between midnight and dawn. This local time interval represents a region in Earth's near space that experiences an enhancement in electron plasma density due to a migration from the magnetotail during or following a geomagnetic substorm.

  2. Evaluating United States and world consumption of neodymium, dysprosium, terbium, and praseodymium in final products

    NASA Astrophysics Data System (ADS)

    Hart, Matthew

    This paper develops scenarios of future rare-earth-magnet metal (neodymium, dysprosium, terbium, and praseodymium) consumption in the permanent magnets used in wind turbines and hybrid electric vehicles. The scenarios start with naive base-case scenarios for growth in wind-turbine and hybrid-electric-vehicle sales over the period 2011 to 2020, using historical data for each good. These naive scenarios assume that future growth follows time trends in historical data and does not depend on any exogenous variable. Specifically, growth of each technological market follows historical time trends, and the amount of rare earths used per unit of technology remains fixed. The chosen reference year is 2010. Implied consumptions of the rare earth magnet metals are calculated from these scenarios. Assumptions are made for the material composition of permanent magnets, the market share of permanent-magnet wind turbines and vehicles, and magnet weight per unit of technology. Different scenarios estimate how changes in factors like the material composition of magnets, growth of the economy, and the price of a substitute could affect future consumption. Each scenario presents a different method for reducing rare earth consumption and could be interpreted as potential policy choices. In 2010, the consumption (metric tons, rare-earth-oxide equivalent) of each rare-earth-magnet metal was as follows. Total neodymium consumption in the world for both technologies was 995 tons; dysprosium consumption was 133 tons; terbium consumption was 50 tons; praseodymium consumption was zero tons. The base scenario for wind turbines shows there could be strong, exponential growth in the global wind turbine market. New U.S. sales of hybrid vehicles would decline (in line with the current economic recession) while non-U.S. sales increase through 2020. There would be an overall increase in the total amount of magnetic rare earths consumed in the world. Total consumption of each rare earth in the short

  3. Molybdenum Isotopes in Some Iron Meteorites

    NASA Astrophysics Data System (ADS)

    Qi, L.; Masuda, A.

    1992-07-01

    Measurement of all seven stable Mo isotopes in iron meteorites has been continued for study of possible direct evidences for processes of nucleosynthesis in the pre-solar stage and information on extinct radioactive nuclides. Mo in iron meteorite was extracted by using recently developed chemical separation method [1], then loaded on 5 pass zone refined Re ribbon. Molybdenum isotope analysis was performed [2] in a VG SECTOR 54-30 thermal ionization mass spectrometer using a Faraday collector in peak jumping mode. The measured ratios of Mo were normalized provisionally to ^94Mo/^98Mo = 0.3802. Particular caution was drawn on the isobaric interferences of Zr, Ru, etc., which were negligible as a result. A small but distinct anomaly of Mo isotopes was found in Acuna iron meteorite. The normalized data show a growth trend from ^92Mo to ^97Mo, and this increment decreased suddenly at ^98Mo, then slightly increased at ^100Mo. The isotope variations might be explained as a result of excess s-process component (^95Mo to ^98Mo) contained in the sample. Gibeon suggested that isotopic anomalies at ^92Mo, ^95Mo, and ^97Mo are about -3-epsilon, -1.2-epsilon, and -0.5-epsilon respectively. It is difficult to give a perfect explanation to the observed data at present. However, it is interesting to note that ^92Mo (N=50) has a closed shell and only ^95Mo and ^97Mo are even-odd nuclides in all seven stable Mo isotopes and the 30-keV Maxwellian-averaged neutron capture cross sections for ^95Mo and ^97Mo are about 3 times bigger than others [3]. The depletions at ^95Mo and ^97Mo might be attributed to the higher cross section for their destruction by (n, gamma) reaction. The apparent opposite aberrations are found for Odessa iron. We reported anomalies of Mo isotopes in a specimen of Sikhote-Alin iron meteorite [4,5]. Further investigations have shown that the isotopic compositions of Mo in this iron are heterogeneous and that the "general anomaly" of Mo isotopes is related with the

  4. 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.

  5. Anomaly detection for internet surveillance

    NASA Astrophysics Data System (ADS)

    Bouma, Henri; Raaijmakers, Stephan; Halma, Arvid; Wedemeijer, Harry

    2012-06-01

    Many threats in the real world can be related to activity of persons on the internet. Internet surveillance aims to predict and prevent attacks and to assist in finding suspects based on information from the web. However, the amount of data on the internet rapidly increases and it is time consuming to monitor many websites. In this paper, we present a novel method to automatically monitor trends and find anomalies on the internet. The system was tested on Twitter data. The results showed that it can successfully recognize abnormal changes in activity or emotion.

  6. 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. L.; Sarantos, M.; Boardsen, S.; Moore, T. E.; Barabash, S.

    2012-04-01

    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.

  7. Space Weather, Cosmic Rays, and Satellite Anomalies

    NASA Astrophysics Data System (ADS)

    Lev, Dorman

    Results are presented of the Satellite Anomaly Project, which aims to improve the methods of safeguarding satellites in the Earth’s magnetosphere from the negative effects of the space environment. Anomaly data from the USSR and Russian “Kosmos” series satellites in the period 1971-1999 are combined into one database, together with similar information on other spacecraft. This database contains, beyond the anomaly information, various characteristics of space weather: geomagnetic activity indices (Ap, AE and Dst), fluxes and fluencies of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried out for the total number of anomalies (about 6000 events), and separately for high altitude orbit satellites ( 5000 events) and low altitude (about 800 events). No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and low (<1500 km) altitude orbits revealed a big difference in behavior. Satellites were divided into several groups according to their orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found to be different for various orbits, and this should be taken into account when developing anomaly frequency models. The preliminary anomaly frequency models are presented.

  8. A new solid-state, frequency-doubled neodymium-YAG photocoagulation system.

    PubMed

    Jalkh, A E; Pflibsen, K; Pomerantzeff, O; Trempe, C L; Schepens, C L

    1988-06-01

    We have developed a solid-state laser system that produces a continuous green monochromatic laser beam of 532 nm by doubling the frequency of a neodymium-YAG laser wavelength of 1064 nm with a potassium-titamyl-phosphate crystal. Photocoagulation burns of equal size and intensity were placed in two rabbit eyes with the solid-state laser system and the regular green argon laser system, respectively, using the same slit-lamp mode of delivery. Histologic findings of lesion sections revealed no important differences between the two systems. In theory, the longer wavelength of the solid-state laser offers the advantages of less scattering in ocular media, higher absorption by oxyhemoglobin, and less absorption by macular xanthophyll than the 514-nm wavelength of the regular green argon laser. The solid-state laser has impressive technical advantages: it contains no argon-ion gas tube that wears out and is expensive to replace; it is much more power efficient, and thus considerably smaller and compact; it is sturdier and easily movable; it does not require external cooling; it uses a 220-V monophasic alternating current; and it requires little maintenance. PMID:3370017

  9. Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems.

    PubMed

    Lumetta, Gregg J; Sinkov, Sergey I; Krause, Jeanette A; Sweet, Lucas E

    2016-02-15

    The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO(-) anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions. PMID:26815878

  10. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications.

    PubMed

    Zacchia, Nicholas A; Valentine, Megan T

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy. PMID:26026529

  11. Neodymium:yttrium-aluminium-garnet laser for excision of pulmonary nodules: an institutional review.

    PubMed

    Moghissi, Keyvan; Dixon, Kate

    2009-03-01

    Eighty patients amongst 850 undergoing pulmonary surgery with the use of neodymium:yttrium-aluminium-garnet (Nd:YAG) laser had a solitary pulmonary nodule (< or = 50 mm) on chest radiography, which was confirmed or suspected pre-operatively to be primary lung cancer. All patients had a mini-thoracotomy to expose the lesion. They then had Nd:YAG laser to excise the nodule locally. There was no hospital mortality. Six patients had non-fatal post-operative complications. Pathologically, 46 patients had primary lung cancer and ten had secondary lung cancer. Twenty-four others had benign lesions. Mean hospital stay was 5.5 days. Post-operative reduction of forced vital capacity (FVC) and forced expiratory volume in one second (FEV(1)) was 14% and 13% (mean), respectively. Thirty-seven patients with primary lung cancer were followed up for between 12 months and 60 months. Mean survival time of these patients was 39 months (s.d. 13 months). It was concluded that Nd:YAG laser for pulmonary nodular lesions should be considered for a selected group of patients unsuitable for standard resection. PMID:18214573

  12. Clinical comparison of semiconductor diode versus neodymium: YAG non-contact cyclo photocoagulation.

    PubMed Central

    Ulbig, M W; McHugh, D A; McNaught, A I; Hamilton, A M

    1995-01-01

    AIMS--The advent of diode lasers has allowed their use in transscleral cyclo photocoagulation for refractory glaucoma. A trial was performed to compare the ocular hypotensive and inflammatory effects of cyclo photocoagulation using a continuous wave diode (810 nm) and a free running neodymium:yttrium aluminium garnet (Nd:YAG) laser (1064 nm). METHODS--Forty patients with refractory glaucoma were randomised to receive either diode or Nd:YAG therapy. The intraocular pressure (IOP) and inflammatory response to treatment were monitored over 3 months. RESULTS--There was no significant laser related difference in the effect on IOP after one treatment. There was, however, a difference in effect in retreatments with the IOP lowering effect significantly less, but equally sustained in diode retreatment patients. Severe postoperative complications such as hyphaema or fibrinous anterior uveitis only occurred in the Nd:YAG group. CONCLUSION--The degree and duration of the ocular hypotensive response to cyclo photocoagulation appears to be related to the available power output of the system used, and the extent of tissue damage. Images PMID:7626573

  13. Neodymium:YAG laser treatment of lower leg telangiectasia: a new minimally invasive approach.

    PubMed

    Iannitti, Tommaso; Lonardi, Roberto; Rottigni, Valentina; Palmieri, Beniamino

    2012-09-01

    The aim of this study was to validate the safety and effectiveness of a new therapeutic procedure for the treatment of lower leg telangiectasia without clinical vein insufficiency. A group of 20 healthy women aged between 24 and 47 years (mean±sem 37.05 ± 1.47) with lower leg telangiectasia without clinical vein insufficiency, previously investigated by echo colour Doppler sonography, were recruited and were treated with neodymium:YAG laser (mean±sem 2.5 ± 0.11 sessions). Good or excellent results were obtained in 16 patients and the improvements were statistically significant (p < 0.01). Out of the 20 patients, 16 were satisfied with the procedure. We strongly support laser treatment of lower leg telangiectasia since it allows injection of chemicals to be avoided, and changes the stromal microarchitecture rearranging the fibroblast network into a more resistant pattern reducing the likelihood of relapse. PMID:22205469

  14. Analysis of a 10 megawatt space-based solar-pumped neodymium laser system

    NASA Technical Reports Server (NTRS)

    Kurweg, U. H.

    1984-01-01

    A ten megawatt solar-pumped continuous liquid laser system for space applications is examined. It is found that a single inflatable mirror of 434 m diameter used in conjunction with a conical secondary concentrator is sufficient to side pump a liquid neodymium lasant in an annular tube of 6 m length and 1 m outer and 0.8 m inner diameter. About one fourth of intercepted radiation converging on the laser tube is absorbed and one fifth of this radiation is effective in populating the upper levels. The liquid lasant is flowed through the annular laser cavity at 1.9 m/s and is cooled via a heat exchanger and a large radiator surface comparable in size to the concentrating mirror. The power density of incident light within the lasant of approximately 68 watt/cu cm required for cw operation is exceeded in the present annular configuration. Total system weight corresponds to 20,500 kg and is thus capable of being transported to near Earth orbit by a single shuttle flight.

  15. High-mobility thin film transistors with neodymium-substituted indium oxide active layer

    SciTech Connect

    Lin, Zhenguo; Lan, Linfeng Xiao, Peng; Sun, Sheng; Li, Yuzhi; Song, Wei; Gao, Peixiong; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2015-09-14

    Thin-film transistors (TFTs) with neodymium-substituted indium oxide (InNdO) channel layer were demonstrated. The structural properties of the InNdO films as a function of annealing temperature have been analyzed using X-ray diffraction and transmission electron microscopy. The InNdO thin films showed polycrystalline nature when annealed at 450 °C with a lattice parameter (cubic cell) of 10.255 Å, which is larger than the cubic In{sub 2}O{sub 3} film (10.117 Å). The high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy showed that no Nd{sub 2}O{sub 3} clusters were found in the InNdO film, implying that Nd was incorporated into the In{sub 2}O{sub 3} lattice. The InNdO TFTs annealed at 450 °C exhibited more excellent electrical properties with a high mobility of 20.4 cm{sup 2} V{sup −1} s{sup −1} and better electric bias stability compared to those annealed at 300 °C, which was attributed to the reduction of the scattering centers and/or charge traps due to the decrease of the |Nd3d{sub 5/2}{sup 5}4f{sup 4}O2p{sup −1}〉 electron configuration.

  16. Near-infrared electroluminescence at room temperature from neodymium-doped gallium nitride thin films

    SciTech Connect

    Kim, Joo Han; Holloway, Paul H.

    2004-09-06

    Strong near-infrared (NIR) electroluminescence (EL) at room temperature from neodymium (Nd)-doped gallium nitride (GaN) thin films is reported. The Nd-doped GaN films were grown by radio-frequency planar magnetron cosputtering of separate GaN and metallic Nd targets in a pure nitrogen ambient. X-ray diffraction data did not identify the presence of any secondary phases and revealed that the Nd-doped GaN films had a highly textured wurtzite crystal structure with the c-axis normal to the surface of the film. The EL devices were fabricated with a thin-film multilayered structure of Al/Nd-doped GaN/Al{sub 2}O{sub 3}-TiO{sub 2}/indium-tin oxide and tested at room temperate. Three distinct NIR EL emission peaks were observed from the devices at 905, 1082, and 1364 nm, arising from the radiative relaxation of the {sup 4}F{sub 3sol2} excited-state energy level to the {sup 4}I{sub 9sol2}, {sup 4}I{sub 11sol2}, and {sup 4}I{sub 13sol2} levels of the Nd{sup 3+} ion, respectively. The threshold voltage for all the three emission peaks was {approx}150 V. The external power efficiency of the fabricated EL devices was {approx}1x10{sup -5} measured at 40 V above the threshold voltage.

  17. Endoscopic management of post-traumatic prostatic and supraprostatic strictures using Neodymium-YAG laser.

    PubMed

    Nabi, Ghulam; Dogra, Prem Nath

    2002-12-01

    We assessed the feasibility, efficacy and long-term results of endoscopic management using Neodymium-YAG (Nd-YAG) laser as a day care procedure in patients with post-traumatic supraprostatic and prostatic strictures. Three patients with post-traumatic prostatic and supraprostatic obliterative strictures underwent Nd-YAG laser core through urethrotomy as a day care procedure. Patient age ranged between 12 and 14 years. Mean duration of injury was 16 months. The length of stricture was assessed by bi-directional endoscopy prior to the procedure in all cases. Core through procedure was carried out using Nd-YAG laser under the guidance of a cystoscope placed antegradely. Patients were discharged on the same day with urethral catheter. Foley catheters were removed at 6 weeks. Nd-YAG laser core through procedure was carried out successfully in all cases with negligible blood loss in a mean time of 48 min. There were no intraoperative or postoperative complications. Patients were discharged on the same day. Follow-up cystogram was conducted at 6 weeks and urethroscopy at months. At a mean follow-up of 23 months, patients were asymptomatic and voiding well. Nd-YAG laser core through urethrotomy is a safe and effective procedure. It is a less invasive alternative to more complex urethroplasty procedures for patients with post-traumatic prostatic and supraprostatic strictures. It can be carried out as a day care procedure in carefully selected patients and has no complications. PMID:12492959

  18. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    SciTech Connect

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  19. Optical properties of Lead bismuth borate glasses doped with neodymium oxide.

    PubMed

    Farouk, M; Abd El-Maboud, A; Ibrahim, M; Ratep, A; Kashif, I

    2015-10-01

    Neodymium doped Lead bismuth borate glasses with the composition of 25PbO-25Bi2O3-50B2O3:xNd2O3, where x=0.5, 1, 1.5 and 2 mol%, have been prepared by melt quenching technique. The behavior of the density and molar volume allows concluding that, addition of Nd2O3 leads to the formation of non-bridging oxygen. Rare earth ion parameters have been calculated and studied. The optical band gap (Eg), and band tails (Ee) were determined. Judd-Ofelt theory for the intensity analysis of induced electric dipole transitions has been applied to the measured oscillator strengths of the absorption bands to determine the three phenomenological intensity parameters Ω2, Ω4 and Ω6 for glass. It was observed that the deviation parameters, rms, was found to be 0.56:0.58(×10(-6)). The estimated Judd-Ofelt parameters were found to be Nd2O3concentration dependent. The hypersensitive transition, (4)I9/2→(4)G5/2+(2)G7/2, is closely related to Ω2 parameter. PMID:25965518

  20. Crystal and Electronic Study of Neodymium-Substituted CuFeO2 Oxide

    NASA Astrophysics Data System (ADS)

    Ozkendir, Osman Murat

    2016-06-01

    Neodymium-substituted CuFeO2 samples were investigated according to their crystal and electronic properties via the general formula Nd x Cu1- x FeO2. The crystal structure analysis results revealed polycrystalline formations in the sample and a change in crystalline sizes with the substituted heavy fermion "Nd." Increasing the Nd amount in the sample was determined to cause a disturbance on the Cu-Fe planes that supports the formation of crystal structures with low crystal symmetries such as monoclinic or triclinic geometries. To obtain the background mechanisms of the crystal properties, the X-ray absorption fine structure spectroscopy technique was used to study the electronic properties of the samples. Prominent changes in the crystal structures due to 4 f electrons' contributions from the substituted Nd atoms as the main "role player" in the phase transitions were determined. The Nd atoms were observed as the key element guiding the entire phenomenon as a result of their large size and narrow 4 f levels. Also, magnetic properties of the samples were tested at room temperature and without an applied magnetic field by X-ray magnetic circular dichroism study due to previous studies that reported the parent oxide CuFeO2 to have magnetic ordering at T N = 11 K (-262 °C). Except the sample for x = 1.0 (NdFeO3), no magnetic ordering was observed at room temperature; i.e., all of the samples showed paramagnetic behaviors.

  1. Optical radiation hazards of laser welding processes. Part 1: Neodymium-YAG laser.

    PubMed

    Rockwell, R J; Moss, C E

    1983-08-01

    High power laser devices are being used for numerous metalworking processes such as welding, cutting and heat treating. Such laser devices are totally enclosed either by the manufacturer or the end-user. When this is done, the total laser system is usually certified by the manufacturer following the federal requirements of the Code of Federal Regulations (CFR) 1040.10 and 10.40.11 as a Class I laser system. Similarly, the end-user may also reclassify an enclosed high-power laser into the Class I category following the requirements of the American National Standards Institute (ANSI) Z-136.1 (1980) standard. There are, however, numerous industrial laser applications where Class IV systems are required to be used in an unenclosed manner. In such applications, there is concern for both ocular and skin hazards caused by direct and scattered laser radiation, as well as potential hazards caused by the optical radiation created by the laser beam's interaction with the metal (i.e. the plume radiation). Radiant energy measurements are reported for both the scattered laser radiation and the resultant plume radiations which were produced during typical unenclosed Class IV Neodymium-YAG laser welding processes. Evaluation of the plume radiation was done with both radiometric and spectroradiometric measurement equipment. The data obtained were compared to applicable safety standards. PMID:6688700

  2. Planar waveguides in neodymium-doped calcium niobium gallium garnet crystals produced by proton implantation

    NASA Astrophysics Data System (ADS)

    Chun-Xiao, Liu; Meng, Chen; Li-Li, Fu; Rui-Lin, Zheng; Hai-Tao, Guo; Zhi-Guang, Zhou; Wei-Nan, Li; She-Bao, Lin; Wei, Wei

    2016-04-01

    In this work, the fabrication and optical properties of a planar waveguide in a neodymium-doped calcium niobium gallium garnet (Nd:CNGG) crystal are reported. The waveguide is produced by proton (H+) implantation at 480 keV and a fluence of 1.0×1017 ions/cm2. The prism-coupling measurement is performed to obtain the dark mode of the waveguide at a wavelength of 632.8 nm. The reflectivity calculation method (RCM) is used to reconstruct the refractive index profile. The finite-difference beam propagation method (FD-BPM) is employed to calculate the guided mode profile of the waveguide. The stopping and range of ions in matter 2010 (SRIM 2010) code is used to simulate the damage profile induced by the ion implantation. The experimental and theoretical results indicate that the waveguide can confine the light propagation. Project supported by the National Natural Science Foundation of China (Grant Nos. 11405041, 61405240, 61077070, 61177086, 51002181, and 61177084), the Scientific Research Starting Foundation for New Teachers of Nanjing University of Posts and Telecommunications (NUPTSF) (Grant No. NY214159), and the Research Center of Optical Communications Engineering & Technology, Jiangsu Province, China (Grant No. ZSF0401).

  3. Laser treatment of a neodymium magnet and analysis of surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Rizwan, M.; Kassas, M.

    2016-08-01

    Laser treatment of neodymium magnet (Nd2Fe14B) surface is carried out under the high pressure nitrogen assisting gas. A thin carbon film containing 12% WC carbide particles with 400 nm sizes are formed at the surface prior to the laser treatment process. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools. The corrosion resistance of the laser treated surface is analyzed incorporating the potentiodynamic tests carried out in 0.05 M NaCl+0.1 M H2SO4 solution. The friction coefficient of the laser treated surface is measured using the micro-scratch tester. The wetting characteristics of the treated surface are assessed incorporating the sessile water drop measurements. It is found that a dense layer consisting of fine size grains and WC particles is formed in the surface region of the laser treated layer. Corrosion resistance of the surface improves significantly after the laser treatment process. Friction coefficient of laser treated surface is lower than that of the as received surface. Laser treatment results in superhydrophobic characteristics at the substrate surface. The formation of hematite and grain size variation in the treated layer slightly lowers the magnetic strength of the laser treated workpiece.

  4. Highly efficient neodymium:yttrium aluminum garnet laser end pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Sipes, D. L.

    1985-01-01

    In recent experiments, 80-mW CW power in a single mode has been achieved from a neodymium:yttrium aluminum garnet (Nd:YAG) laser with only 1 W of electrical power input to a single semiconductor laser array pump. This corresponds to an overall efficiency of 8 percent, the highest reported CW efficiency for a Nd:YAG laser. A tightly focused semiconductor laser end pump configuration is used to achieve high pumping intensities (on the order of 1 kW/sq cm), which in turn causes the photon to photon conversion efficiency to approach the quantum efficiency (76 percent for Nd:YAG at 1.06 microns pumped at 0.810 micron). This is achieved despite the dual-lobed nature of the pump. Through the use of simple beam-combining schemes (e.g., polarization coupling and multireflection point pumping), output powers over 1 W and overall electrical to optical efficiencies as high as 10 percent are expected.

  5. Power scaling of diode-pumped neodymium yttrium aluminum borate laser

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    1991-01-01

    Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

  6. Conductivity Anomalies in Central Europe

    NASA Astrophysics Data System (ADS)

    Neska, Anne

    2016-01-01

    This paper is a review of studies which, by applying the magnetotelluric, geomagnetic deep sounding, and magnetovariational sounding methods (the latter refers to usage of the horizontal magnetic tensor), investigate Central Europe for zones of enhanced electrical conductivity. The study areas comprise the region of the Trans-European Suture Zone (i.e. the south Baltic region and Poland), the North German Basin, the German and Czech Variscides, the Pannonian Basin (Hungary), and the Polish, Slovakian, Ukrainian, and Romanian Carpathians. This part of the world is well investigated in terms of data coverage and of the density of published studies, whereas the certainty that the results lead to comprehensive interpretations varies within the reviewed literature. A comparison of spatially coincident or adjacent studies reveals the important role that the data coverage of a distinct conductivity anomaly plays for the consistency of results. The encountered conductivity anomalies are understood as linked to basin sediments, asthenospheric upwelling, large differences in lithospheric age, and—this concerns most of them, which all concentrate in the middle crust—tectonic boundaries that developed during all mountain building phases that have taken place on the continent.

  7. Limits on conservative behavior of Nd isotopes in seawater assessed from analysis of fish teeth from Pacific core tops

    NASA Astrophysics Data System (ADS)

    Horikawa, Keiji; Martin, Ellen E.; Asahara, Yoshihiro; Sagawa, Takuya

    2011-10-01

    Neodymium (Nd) isotopes have become an accepted water mass tracer for paleoceanographic reconstructions; however, high rates of radiogenic Nd input from volcanic islands/arcs in the western equatorial Pacific (WEP) and the subarctic North Pacific (SANP) can significantly alter the isotopic composition of ambient seawaters, leading to questions about the conservative nature of Nd isotopes in the Pacific. Here we present the first comprehensive study of Nd isotopes preserved in core-top fossil fish teeth/debris from 31 sites in the Pacific to define the vertical and horizontal distributions of seawater Nd isotopes and to test the reliability of Nd isotopes as a water mass tracer in the Pacific. We found that Nd isotopic values of northward-flowing Lower Circumpolar Deep Water (LCDW) are significantly modified in the western-central equatorial Pacific and the SANP as a result of local radiogenic inputs from young circum-Pacific island arcs. Consequently, 'modified LCDW' with ~-5 ɛ Nd is created in the central equatorial Pacific, while recirculated North Pacific Deep Water (NPDW) acquires a radiogenic Nd isotope value (~-2 ɛ Nd) in the SANP. Nd isotopic ratios of fish teeth/debris in the central North Pacific plotted against salinity (or phosphate concentration) from the overlying bottom water produce a mixing envelope between modified LCDW and NPDW, indicating that these Nd isotopic values represent the southern- and northern-sourced end member values for the central North Pacific and that mixing of these water masses defines vertical profiles of Nd isotopes in this region. In the eastern equatorial Pacific (EEP) three water masses (modified LCDW, NPDW SANP, and NPDW western Pacific) combine to produce Nd isotopic values that reflect this conservative mixture. Therefore, Nd isotopes behave as a conservative water mass tracer in the central North Pacific and the EEP, but high rates of lithogenic inputs from young circum-Pacific island arcs compromise the conservative

  8. Changes of charge radii and hyperfine interactions of the Dy isotopes

    NASA Astrophysics Data System (ADS)

    Clark, D. L.; Greenlees, G. W.

    1982-10-01

    A continuous wave dye laser and a thermal atomic beam were used to measure the optical isotope shifts and hyperfine splittings for the 5547 Å, 5639 Å, 5652 Å, 5974 Å, and the 5989 Å transition of the seven stable isotopes of dysprosium. The hyperfine splitting of the odd-A isotopes has been analyzed using the formalism of Sanders and Beck and the hyperfine anomaly has been extracted. Comparison with calculations using Nilsson wave functions is presented. The isotope shift measurements have been analyzed with published electronic and muonic x-ray isotope shifts to yield δ values and some estimates of the specific mass shift constant. NUCLEAR STRUCTURE 156-164Dy. Measured optical isotope shifts and hyperfine splittings. Deduced δ, A(4f126s 6p), B(4f126s 6p), and the hyperfine anomaly. Laser spectroscopy on atomic beams.

  9. 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.

  10. Minor congenital anomalies and ataxic cerebral palsy.

    PubMed Central

    Miller, G

    1989-01-01

    The incidence of minor congenital anomalies was examined in 36 patients with ataxic cerebral palsy, in unaffected family members, and in 100 unrelated control subjects. None of the control subjects or family members had more than four anomalies, and 25 of 36 (69%) of the patients had more than four. The distribution of anomalies differed considerably, with 60% of the index cases having seven or more, and 94% of the controls having three or less. The number occurring in the patients was significantly more than in their relatives. Of the 25 patients with more than four anomalies, 16 (64%) had undergone potentially adverse perinatal or early postnatal events. Thus minor congenital anomalies were considerably more frequent in those with ataxic cerebral palsy than in related or unrelated control subjects. These anomalies may be markers of early prenatal factors that contributed to the adverse outcome either directly or by predisposing to perinatal difficulties. PMID:2751330

  11. Sea level anomalies exacerbate beach erosion

    NASA Astrophysics Data System (ADS)

    Theuerkauf, Ethan J.; Rodriguez, Antonio B.; Fegley, Stephen R.; Luettich, Richard A.

    2014-07-01

    Sea level anomalies are intra-seasonal increases in water level forced by meteorological and oceanographic processes unrelated to storms. The effects of sea level anomalies on beach morphology are unknown but important to constrain because these events have been recognized over large stretches of continental margins. Here, we present beach erosion measurements along Onslow Beach, a barrier island on the U.S. East Coast, in response to a year with frequent sea level anomalies and no major storms. The anomalies enabled extensive erosion, which was similar and in most places greater than the erosion that occurred during a year with a hurricane. These results highlight the importance of sea level anomalies in facilitating coastal erosion and advocate for their inclusion in beach-erosion models and management plans. Sea level anomalies amplify the erosive effects of accelerated sea level rise and changes in storminess associated with global climate change.

  12. Acardiac anceps: a rare congenital anomaly

    PubMed Central

    Nigam, Aruna; Agarwal, Rohini; Saxena, Pikee; Barla, Jaya

    2014-01-01

    Acardiac twin is a rare congenital anomaly and is exclusively associated with monochorionic twin pregnancies. The abnormalities occur due to abnormal communication between the two fetuses in the form of arterioarterial and venovenous communications, resulting in a grossly abnormal acardiac twin with reduction anomalies mainly of the upper body and gross oedema. Since no two acardiac twins are alike, this case report will add to the acardiac twin anomaly spectrum. PMID:24717594

  13. The Mars Rover Spirit FLASH anomaly

    NASA Technical Reports Server (NTRS)

    Reeves, Glenn E.; Neilson, Tracy C.

    2005-01-01

    The Mars Exploration Rover 'Spirit' suffered a debilitating anomaly that prevented communication with Earth for several anxious days. With the eyes of the world upon us, the anomaly team used each scrap of information, our knowledge of the system, and sheer determination to analyze and fix the problem, then return the vehicle to normal operation. This paper will discuss the Spirit FLASH anomaly, including the drama of the investigation, the root cause and the lessons learned from the experience.

  14. Galilean anomalies and their effect on hydrodynamics

    NASA Astrophysics Data System (ADS)

    Jain, Akash

    2016-03-01

    We study flavor and gravitational anomalies in Galilean theories coupled to torsional Newton-Cartan backgrounds. We establish that the relativistic anomaly inflow mechanism with an appropriately modified anomaly polynomial can be used to generate these anomalies. Similar to the relativistic case, we find that Galilean anomalies also survive only in even dimensions. Further, these anomalies only effect the flavor and rotational symmetries of a Galilean theory; in particular, the Milne boost symmetry remains nonanomalous. We also extend the transgression machinery used in relativistic fluids to Galilean fluids, and use it to determine how these anomalies affect the constitutive relations of a Galilean fluid. Unrelated to the Galilean fluids, we propose an analogue of the off-shell second law of thermodynamics for relativistic fluids, to include torsion and a conserved spin current in the vielbein formalism. Interestingly, we find that even in the absence of spin current and torsion the entropy currents in the two formalisms are different: while the usual entropy current gets a contribution from the gravitational anomaly, the entropy current in the vielbein formalism does not have any anomaly-induced part.

  15. The magnetic anomaly of the Ivreazone

    NASA Technical Reports Server (NTRS)

    Albert, G.

    1979-01-01

    A magnetic field survey was made in the Ivreazone in 1969/70. The results were: significant anomaly of the vertical intensity is found. It follows the basic main part of the Ivrea-Verbano zone and continues to the south. The width of the anomaly is about 10 km, the maximum measures about +800 gamma. The model interpretation shows that possibly the anomaly belongs to an amphibolitic body, which in connection with the Ivrea-body was found by deep seismic sounding. Therefore, the magnetic anomaly provides further evidence for the conception that the Ivrea-body has to be regarded as a chip of earthmantle material pushed upward by tectonic processes.

  16. Initial scalar magnetic anomaly map from Magsat

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Phillips, J. D.; Horner, R. J.

    1982-01-01

    Magsat data acquired during the November 1979-June 1980 mission was used to derive a scalar magnetic anomaly map covering +50 to -50 deg geographic latitude, and the separation of anomaly fields from core and external fields was accomplished by techniques developed for POGO satellite data. Except in the Atlantic and Pacific at latitudes south of -15 deg, comparison of the Magsat map with its POGO data-derived counterpart shows basic anomaly patterns to be reproducible, and higher resolution due to Magsat's lower measurement altitude. Color-coded scalar anomaly maps are presented for both satellites.

  17. Conscious and unconscious detection of semantic anomalies.

    PubMed

    Hannon, Brenda

    2015-01-01

    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

  18. Satellite Magnetic Anomalies of Africa and Europe

    NASA Technical Reports Server (NTRS)

    Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator); 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.

  19. Consistent anomalies of the induced W gravities

    NASA Astrophysics Data System (ADS)

    Abud, Mario; Ader, Jean-Pierre; Cappiello, Luigi

    1996-02-01

    The BRST anomaly which may be present in the induced Wn gravity quantized on the light-cone is evaluated in the geometrical framework of Zucchini. The cocycles linked by the cohomology of the BRST operator to the anomaly are straightforwardly calculated thanks to the analogy between this formulation and the Yang-Mills theory. We give also a conformally covariant formulation of these quantities including the anomaly, which is valid on arbitrary Riemann surfaces. The example of the W3 theory is discussed and a comparison with other candidates for the anomaly available in the literature is presented.

  20. 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

  1. 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.

  2. Oculoauriculovertebral spectrum and cerebral anomalies.

    PubMed Central

    Schrander-Stumpel, C T; de Die-Smulders, C E; Hennekam, R C; Fryns, J P; Bouckaert, P X; Brouwer, O F; da Costa, J J; Lommen, E J; Maaswinkel-Mooy, P D

    1992-01-01

    We report on three Dutch children with a clinical diagnosis of oculoauriculovertebral spectrum (OAVS) and hydrocephalus. The clinical features are compared to 15 published cases of OAVS and hydrocephalus. Several other cerebral abnormalities were present in the whole group. About half of the cases had cleft lip/palate, anophthalmia/microphthalmia, or a cardiac defect. Mental retardation was found in five of the surviving 11 patients and early death occurred in one-third. We compared the cases with OAVS and hydrocephalus with published reports of OAVS and other cerebral anomalies and found no significant clinical differences. However, the clinical characteristics were clearly more severely expressed than generally found in patients with OAVS. Children with OAVS and more severe clinical features, especially anophthalmia/microphthalmia and cleft lip/palate, seem to be at an increased risk for cerebral malformations and for mental retardation. Images PMID:1583660

  3. Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest

    USGS Publications Warehouse

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

    2015-01-01

    Helium (He) concentration and 3 He/ 4 He anomalies in soil gas and spring water are potentially powerful tools for investigating hydrothermal circulation associated with volca- nism 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 concen- tration 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 3 He/ 4 He 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 con- centration 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 3 He/ 4 He 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.

  4. Progress update on IUPAC Project 2009-046-2-200: Terminology and definition of quantities related to the isotope distribution in elements with more than two stable isotopes

    NASA Astrophysics Data System (ADS)

    Kaiser, Jan; Angert, Alon; Bergquist, Bridget; Brand, Willi; Ono, Shuhei; Röckmann, Thomas; Savarino, Joël

    2014-05-01

    The objective of IUPAC Project 2009-046-2-200 (http://www.iupac.org/web/ins/2009-046-2-200) is to define terminology and to identify the most suitable definitions of quantities that characterise the isotope distribution in elements with more than two stable isotopes, including so-called mass-independent fractionation, non-mass dependent fractionation, isotope anomaly, 17O excess, etc. Most atmospheric oxygen-bearing species show deviations in their triple oxygen isotope ratios from mass-dependent fractionation (MDF) relationships predicted by the theories of Urey, Bigeleisen and Mayer. Similar deviations have also been found in sulphur and other elements with more than two stables isotopes (e.g. Hg, Cd, Zn), often preserved in non-atmospheric reservoirs, including rocks, minerals, soils, ice and waters. Despite the ubiquity of this type of isotope anomaly, there has never been an attempt to clearly define the terminology and physical quantities used to measure these anomalies and the processes that lead to their formation. Terms like mass-independent fractionation, non-mass dependent fractionation, isotope anomaly, isotope excess etc. have been used in the historic and recent literature, but are often not carefully distinguished. The realisation that MDF comprises a range of possible relationships between the isotopes of one element led to further complications because it meant that apparent isotope anomalies could be created by a combination of different MDF processes. At the moment, at least four different definitions to quantify isotope anomalies are being used. Furthermore, coefficients used in these definitions vary, which makes the comparison of data from different sources very difficult, even for experts. A consistent set of recommendations on how to express and quantify the isotope distribution in elements with more than two stable isotopes is highly warranted. From our experience as academic teachers, we are woefully aware how impenetrable the field is for

  5. Mantle metasomatism above subduction zones: Trace-element and radiogenic isotope characteristics of peridotite xenoliths from Batan Island (Philippines)

    SciTech Connect

    Vidal, Ph. ); Dupuy, C. ); Maury, R.; Richard, M. )

    1989-12-01

    Trace-element abundances and radiogenic isotope ratios have been determined for a suite of upper mantle-derived xenoliths collected from Pliocene-Quaternary andesitic lavas on Batan Island, northernmost Philippines. The xenoliths exhibit mineralogical changes and large ion lithophile enrichment indicative of metasomatism involving H{sub 2}O-rich fluids. Strontium and neodymium isotopes in the xenoliths are not totally consistent with those in host lavas, but a common signature is indicated by the fact that all samples plot below the mantle array. The flux of fluids in the mantle wedge probably occurred over a long period of time. The flux induced large but variable changes in mineral and trace and isotopic compositions, and ultimately resulted in the melting of the peridotites and production of island-arc lavas.

  6. Seawater osmium isotope evidence for a middle Miocene flood basalt event in ferromanganese crust records

    USGS Publications Warehouse

    Klemm, V.; Frank, M.; Levasseur, S.; Halliday, A.N.; Hein, J.R.

    2008-01-01

    Three ferromanganese crusts from the northeast, northwest and central Atlantic were re-dated using osmium (Os) isotope stratigraphy and yield ages from middle Miocene to the present. The three Os isotope records do not show evidence for growth hiatuses. The reconstructed Os isotope-based growth rates for the sections older than 10??Ma are higher than those determined previously by the combined beryllium isotope (10Be/9Be) and cobalt (Co) constant-flux methods, which results in a decrease in the maximum age of each crust. This re-dating does not lead to significant changes to the interpretation of previously determined radiogenic isotope neodymium, lead (Nd, Pb) time series because the variability of these isotopes was very small in the records of the three crusts prior to 10??Ma. The Os isotope record of the central Atlantic crust shows a pronounced minimum during the middle Miocene between 15 and 12??Ma, similar to a minimum previously observed in two ferromanganese crusts from the central Pacific. For the other two Atlantic crusts, the Os isotope records and their calibration to the global seawater curve for the middle Miocene are either more uncertain or too short and thus do not allow for a reliable identification of an isotopic minimum. Similar to pronounced minima reported previously for the Cretaceous/Tertiary and Eocene/Oligocene boundaries, possible interpretations for the newly identified middle Miocene Os isotope minimum include changes in weathering intensity and/or a meteorite impact coinciding with the formation of the No??rdlinger Ries Crater. It is suggested that the eruption and weathering of the Columbia River flood basalts provided a significant amount of the unradiogenic Os required to produce the middle Miocene minimum. ?? 2008 Elsevier B.V.

  7. Development of an empirical kinetic model for sonocatalytic process using neodymium doped zinc oxide nanoparticles.

    PubMed

    Khataee, Alireza; Vahid, Behrouz; Saadi, Shabnam; Joo, Sang Woo

    2016-03-01

    The degradation of Acid Blue 92 (AB92) solution was investigated using a sonocatalytic process with pure and neodymium (Nd)-doped ZnO nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The 1% Nd-doped ZnO nanoparticles demonstrated the highest sonocatalytic activity for the treatment of AB92 (10 mg/L) with a degradation efficiency (DE%) of 86.20% compared to pure ZnO (62.92%) and sonication (45.73%) after 150 min. The results reveal that the sonocatalytic degradation followed pseudo-first order kinetics. An empirical kinetic model was developed using nonlinear regression analysis to estimate the pseudo-first-order rate constant (kapp) as a function of the operational parameters, including the initial dye concentration (5-25 mg/L), doped-catalyst dosage (0.25-1 g/L), ultrasonic power (150-400 W), and dopant content (1-6% mol). The results from the kinetic model were consistent with the experimental results (R(2)=0.990). Moreover, DE% increases with addition of potassium periodate, peroxydisulfate, and hydrogen peroxide as radical enhancers by generating more free radicals. However, the addition of chloride, carbonate, sulfate, and t-butanol as radical scavengers declines DE%. Suitable reusability of the doped sonocatalyst was proven for several consecutive runs. Some of the produced intermediates were also detected by GC-MS analysis. The phytotoxicity test using Lemna minor (L. minor) plant confirmed the considerable toxicity removal of the AB92 solution after treatment process. PMID:26584992

  8. Effect of neodymium substitution on structural and ferroelectric properties of BNT ceramics

    SciTech Connect

    Pal, Vijayeta; Dwivedi, R.K.; Thakur, O.P.

    2014-03-01

    Graphical abstract: - Highlights: • First time, we synthesized (Bi{sub 1−x}Nd{sub x}){sub 0.5}Na{sub 0.5}TiO{sub 3} system by semi wet technique. • Grain size reduced with doping and Nd acts as an inhibitor in the grain growth. • Specimen with x = 0.02 exhibits excellent ferroelectric properties at RT. • P–E loops show the co-existence of polar and non polar regions around ‘T{sub d}’. - Abstract: Polycrystalline specimens of (Bi{sub 1−x}Nd{sub x}){sub 0.5}Na{sub 0.5}TiO{sub 3} (BNNT) ceramic system with compositions x ≤ 0.04 were synthesized by semi-wet technique using ethylene glycol precursor. Structural and electrical properties were investigated in detail to observe the effect of neodymium (Nd) substitution in BNT system. XRD patterns for all the specimens showed single phase formation with rhombohedral structure. Field emission scanning electron micrographs (FE-SEM) revealed that the grain growth was inhibited significantly with Nd content. The temperature dependence behaviour of dielectric constant revealed that the depolarisation temperature ‘T{sub d}’ decreases whereas temperature of maximum dielectric constant ‘T{sub m}’ increases with Nd concentration. The piezoelectric charge coefficient (d{sub 33}) showed maxima at x = 0.02 and well defined ferroelectric behaviour was observed for all the samples.

  9. Indicated preterm birth for fetal anomalies.

    PubMed

    Craigo, Sabrina D

    2011-10-01

    Between 2% and 3% of pregnancies are complicated by fetal anomalies. For most anomalies, there is no advantage to late preterm or early-term delivery. The risks of maternal or fetal complication are specific for each anomaly. Very few anomalies pose potential maternal risk. Some anomalies carry ongoing risks to the fetus, such as an increased risk of fetal death, hemorrhage, or organ damage. In a limited number of select cases, the advantages of late preterm or early-term birth may include avoiding an ongoing risk of fetal death related to the anomaly, allowing delivery in a controlled setting with availability of subspecialists and allowing direct care for the neonate with organ injury. The optimal gestational age for delivery cannot be determined for all pregnancies complicated by fetal anomalies. For most pregnancies complicated by anomalies, there is no change to obstetrical management regarding timing of delivery. For those that may benefit from late preterm or early-term delivery, variability exists such that each management plan should be individualized. PMID:21962626

  10. Anomalies of Nuclear Criticality, Revision 6

    SciTech Connect

    Clayton, E. D.; Prichard, Andrew W.; Durst, Bonita E.; Erickson, David; Puigh, Raymond J.

    2010-02-19

    This report is revision 6 of the Anomalies of Nuclear Criticality. This report is required reading for the training of criticality professionals in many organizations both nationally and internationally. This report describes many different classes of nuclear criticality anomalies that are different than expected.

  11. Homogeneous liquid-liquid extraction of neodymium(III) by choline hexafluoroacetylacetonate in the ionic liquid choline bis(trifluoromethylsulfonyl)imide.

    PubMed

    Onghena, Bieke; Jacobs, Jeroen; Van Meervelt, Luc; Binnemans, Koen

    2014-08-14

    The ionic liquid choline bis(trifluoromethylsulfonyl)imide, [Chol][Tf2N], was used for the extraction of neodymium(III), in combination with choline hexafluoroacetylacetonate, [Chol][hfac], as the extractant. The binary mixture of [Chol][Tf2N] and water shows temperature-dependent phase behavior, with an upper critical solution temperature of 72 °C. A novel extraction technique, homogeneous liquid-liquid extraction (HLLE), was applied to this solvent system. HLLE is based on the use of thermomorphic solvent mixtures and has the advantage of forming a homogeneous phase during mixing. Extraction is not kinetically hindered by an interface and the extraction equilibrium is reached faster than in the case of heterogeneous mixing in conventional solvent extraction. Several extraction parameters were studied for the extraction of neodymium(III) with [Chol][hfac]: temperature, pH, extractant concentration and loading of the ionic liquid phase. A speciation study was performed to determine the stoichiometry of the extracted neodymium(III) complex and a plausible extraction mechanism is proposed. Neodymium is extracted as a tetrakis hexafluoroacetylacetonate complex with one choline cation as counter ion. The crystal structure of the extracted complex showed the presence of a coordination bond between the choline counter ion and the neodymium(III) center, resulting in a coordination number of nine. The stripping of the loaded neodymium and the influence of acid and extractant concentrations on the phase behavior of the [Chol][Tf2N]-H2O system were investigated. PMID:24938933

  12. Large-mode-area single-mode-output Neodymium-doped silicate glass all-solid photonic crystal fiber

    PubMed Central

    Li, Wentao; Chen, Danping; Qinling, Zhou; Hu, Lili

    2015-01-01

    We have demonstrated a 45 μm core diameter Neodymium-doped all-solid silicate glass photonic crystal fiber laser with a single mode laser output. The structure parameters and modes information of the fiber are both demonstrated by theoretical calculations using Finite Difference Time Domain (FDTD) method and experimental measurements. Maximum 0.8 W output power limited by launched pump power has been generated in 1064 nm with laser beam quality factor M2 1.18. PMID:26205850

  13. Diode pumped neodymium doped ASL (Sr1-xLax-yNdyMgxAl12-xO19) laser

    NASA Astrophysics Data System (ADS)

    Zheng, Lihe; Loiseau, Pascal; Aka, Gérard

    2013-07-01

    Blue laser based on Neodymium doped strontium lanthanum magnesium aluminoxide (Sr1-xLax-yNdyMgxAl12-xO19) single crystal were constructed by second harmonic generation. Output power of 1.72 W at 900nm was obtained under 792nm laser diode pump. Intra cavity second harmonic generation were performed with non linear crystal LBO leading to output power of 76.6 mW at 450nm with absorbed power of 13.7 W and average absorption efficiency of 61% in Nd:ASL crystal.

  14. Morphologic and histologic changes in canine temporomandibular joint tissues following arthroscopic guided neodymium:YAG laser exposure

    SciTech Connect

    Bradrick, J.P.; Eckhauser, M.L.; Indresano, A.T. )

    1989-11-01

    A neodymium:yttrium aluminum garnet (Nd:YAG) laser beam was introduced by a quartz fiber passed arthroscopically into the superior joint space of the temporomandibular joints (TMJ) of five mongrel dogs, with one joint serving as a control without laser wounds. Immediate postoperative death and examination of the disc grossly and histologically revealed different patterns for contact and noncontact burn wounds. The wounds exhibited signs of thermal coagulation necrosis similar to those reported in other tissues. The potential implications of the adaptation of the Nd:YAG laser to TMJ arthroscopic surgery are discussed.

  15. Barbados Corals as Recorders of Amazon River Salinity Anomalies

    NASA Astrophysics Data System (ADS)

    Greer, L.; Telfeyan, K.; Arienzo, M. M.; Rosenberg, A. D.; Waite, A. J.; Swart, P. K.

    2010-12-01

    Low salinity plumes of Amazon and Orinoco sourced water have previously been detected around the island of Barbados. Barbados corals may therefore have the potential to record salinity anomalies governed by natural, climate-related, and anthropogenic changes in the Amazon and Orinoco Basin watersheds beyond the recent historic record. In order to determine whether Barbados corals record salinity variations associated with local or Amazon/Orinoco sourced signals, multiple specimens of Montastraea sp. and Siderastrea sp. coral skeletons were analyzed for stable C and O isotope and Sr/Ca variations. Corals were collected from the northwest, central-west, and southwest regions of the island to determine degree of salinity signal heterogeneity over a 5-6 year period at approximately monthly resolution. Four separate published paleotemperature equations were used to assess the importance of temperature on stable oxygen isotope composition. In situ temperature measurements obtained from NOAA show an annual sea surface temperature (SST) cycle of approximately 4 degrees Celsius off Barbados. If governed solely by SST, stable isotope data from all 8 corals in this study indicate a significantly greater annual temperature range of approximately 6 degrees Celsius. This suggests that salinity related fluctuations in oxygen isotopic composition of water are an important influence on the geochemistry of Barbados corals. Some regional differences in geochemical composition of corals were apparent. Corals from the southwest of Barbados showed the clearest sub-annual isotope signal, better correlations with mean annual SST measurements, and lowest mean salinity of the regions. Corals from the central-west and northwest showed distinctly higher mean, but more variable, salinity than corals from the south. Stable carbon isotope data from southwest corals also best potentially reflect the Suess Effect. Montastraea sp. corals generally show a higher paleotemperature offset from in situ

  16. 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.

  17. Global magnetic anomaly and aurora of Neptune

    NASA Technical Reports Server (NTRS)

    Cheng, Andrew F.

    1990-01-01

    The large offset and tilt of Neptune's dipole magnetic field combine to create a global magnetic anomaly, analogous to but much more important than earth's South Atlantic Anomaly. Energetic particle precipitation loss within the Neptune anomaly creates 'atmospheric drift shadows' within which particle fluxes are greatly reduced. The energetic particle dropout observed by Voyager near closest approach occurred near the predicted times when Voyager passed within the atmospheric drift shadow. Extremely soft, structured bursts of ions and electrons within the drift shadow may result from plasma wave-induced pitch angle scattering of trapped particles confined near the magnetic equator. The dropout does not necessarily imply that Voyager passed through an earth-like discrete auroral zone, as earlier reported. The ion and electron fluxes observed within the dropout period correspond to particles that must precipitate to Neptune's atmosphere within the anomaly region. This anomaly precipitation can account for a major portion of the ultraviolet emissions previously identified as Neptune aurora.

  18. A New, Principled Approach to Anomaly Detection

    SciTech Connect

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

    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.

  19. 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.

  20. 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 (δ15NAIR = −310 ± 20‰), similar to that inferred for the solar nebula, to the heaviest ratios measured in any solar system material (δ15NAIR = 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

  1. 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

  2. Structure of Hot Flow Anomaly

    NASA Astrophysics Data System (ADS)

    Shestakov, A.; Vaisberg, O. L.

    2012-12-01

    Hot Flow Anomalies (HFAs) were first discovered in 1980s. These are active processes of hot plasma bulks formation that usually occur at planetary bow shocks. Though HFA were studied for long time it is still not clear if they are reforming structures and what defines particular internal structure of HFA. Our study is based on the Interball Tail Probe data. We used 10-sec measurements of complex plasma analyzer SCA-1 and 1-second magnetic field measurements, and ELECTRON spectrometer 2-dimensional measurements with 3,75-sec temporal resolution. Five anomalies that were observed on the basis of well resolved structure for which we obtained displacement velocity along bow shock, flow velocities within HFA, and estimated the size. We checked if main criteria of HFA formation were fulfilled for each case. The following criteria were satisfied: motional electric field direction was directed toward current sheet at least at one side of it, bow shock was quasi-perpendicular at least at one side of HFA, and angle between current sheet normal and solar wind velocity was large. Convection velocities of plasma within HFA were calculated by subtracting average velocity from measured ion convection velocities along spacecraft trajectory through anomaly. These convection velocities viewed in coordinate system of shock normal and calculated IMF current sheet normal clearly show separation of HFA region in 3 parts: leading part, narrow central part, and trailing part. Ion velocity distributions confirm this triple structure of HFA. Thomsen et al. [1986] identified the region within HFA that they called "internal recovery". It looks like central region that we call narrow central part. Vaisberg et al. [1999] discussed separation of HFA into 2 distinct parts that correspond to leading and trailing parts. Judging from plasma convection pattern within HFAs we assumed that "internal recovery" region is the source of energy and momentum around interplanetary current sheet crossing. HFA

  3. Anomaly Detection in Dynamic Networks

    SciTech Connect

    Turcotte, Melissa

    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

  4. Persistently strong Indonesian Throughflow during marine isotope stage 3: evidence from radiogenic isotopes

    NASA Astrophysics Data System (ADS)

    Stumpf, Roland; Kraft, Steffanie; Frank, Martin; Haley, Brian; Holbourn, Ann; Kuhnt, Wolfgang

    2015-03-01

    The Indonesian Throughflow (ITF) connects the western Pacific Ocean with the eastern Indian Ocean, thus forming one of the major near surface current systems of the global thermohaline circulation. The intensity of the ITF has been found to be sensitive to changes in global ocean circulation, fluctuations in sea level, as well as to the prevailing monsoonal conditions of the Indonesian Archipelago and NW Australia. This study presents the first reconstruction of ITF dynamics combining radiogenic isotope compositions of neodymium (Nd), strontium (Sr), and lead (Pb) of the clay-size detrital fraction to investigate changes in sediment provenance, and paleo seawater Nd signatures extracted from the planktonic foraminifera and authigenic Fe-Mn oxyhydroxide coatings of the marine sediments focussing on marine isotope stage 3 (MIS3). Sediment core MD01-2378 was recovered within the framework of the International Marine Global Change Study (IMAGES) and is located in the area of the ITF outflow in the western Timor Sea (Scott Plateau, 13° 04.95‧ S and 121° 47.27‧ E, 1783 m water depth). In order to produce reliable seawater signatures, several extraction methods were tested against each other. The results of the study show that at this core location the extraction of surface water Nd isotope compositions from planktonic foraminifera is complicated by incomplete removal of contributions from Fe-Mn oxyhydroxides carrying ambient bottom water signatures. The bottom water Nd isotope signatures reliably obtained from the sediment coatings (average ɛNd = -5.0) document an essentially invariable water mass composition similar to today throughout the entire MIS3. The radiogenic Nd, Sr, and Pb isotope records of the clay-sized detrital fraction suggest that the Indonesian Archipelago rather than NW Australia was the main particle source at the location of core MD01-2378, and thus indicating a persistently strong ITF during MIS3. Furthermore, the variations of the detrital

  5. Collie Eye Anomaly in Switzerland.

    PubMed

    Walser-Reinhardt, L; Hässig, M; Spiess, B

    2009-12-01

    In this retrospective study, the results of 3'527 eye examinations in 6 different breeds affected with Collie Eye Anomaly (CEA) over a period of 8 years (1999 - 2007) are described. CEA was divided into three main ophthalmoscopic features, a) choroidal hypoplasia (CRH), b) CRH and coloboma and c) coloboma alone. Of the 101 Smooth Collies 8.9 % showed signs of CRH, whereas 36.9 % of Rough Collies were affected with CRH, 2.8 % with CRH and coloboma and 0.38 % with coloboma alone. Choroidal hypoplasia was present in 13.1 %, CRH and coloboma in 1.8 % and coloboma alone in 0.2 % of the Shetland Sheepdogs. Only one Australian Shepherd dog had CRH, while 0.7 % of the Border Collies were affected with CRH. None of the Nova Scotia Duck Tolling Retrievers were affected with CEA. There were no statistically significant differences in the occurrence of CEA between males and females, nor was there any relation between coat colors. Significant differences could be shown between dogs younger or older than 8 weeks at first examination. CEA was more often diagnosed in dogs younger than 8 weeks within the Rough Collie and Shetland Sheepdog. PMID:19946851

  6. 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.

  7. Vitellointestinal Duct Anomalies in Infancy

    PubMed Central

    Kadian, Yogender Singh; Verma, Anjali; Rattan, Kamal Nain; Kajal, Pardeep

    2016-01-01

    Background: Vitellointestinal duct (VID) or omphalomesenteric duct anomalies are secondary to the persistence of the embryonic vitelline duct, which normally obliterates by weeks 5–9 of intrauterine life. Methods: This is a retrospective analysis of a total of 16 patients of symptomatic remnants of vitellointestinal duct from period of Jan 2009 to May 2013. Results: Male to female ratio (M:F) was 4.3:1 and mean age of presentation was 2 months and their mode of presentation was: patent VID in 9 (56.25%) patients, umbilical cyst in 2(12.25%), umbilical granuloma in 2 (12.25%), and Meckel diverticulum as content of hernia sac in obstructed umbilical hernia in 1 (6.25%) patient. Two patients with umbilical fistula had severe electrolyte disturbance and died without surgical intervention. Conclusion: Persistent VID may have varied presentations in infancy. High output umbilical fistula and excessive bowel prolapse demand urgent surgical intervention to avoid morbidity and mortality. PMID:27433448

  8. Hot Flow Anomaly Structure Analysis

    NASA Astrophysics Data System (ADS)

    Shestakov, A.; Vaisberg, O. L.

    2010-12-01

    Hot Flow Anomaly observed on Interball-Tail on 03.14.1996 is investigated. The normal to the interplanetary current sheet interacting with bow shock was determined in assumption of tangential discontinuity. Calculated motional electric field was directed towards current sheet. The bow shock before HFA arrival to the spacecraft was quasi-perpendicular, and was quasi-parallel after HFA passage. Respectively, of the shocks, bracketing HFA, were quasi-perpendicular before HFA passage and quasi-parallel after it. With averaged velocity of plasma within the body of HFA and duration of HFA observation we determined its size in normal to the current sheet direction as ~ 2.5 RE. HFA consists of two regions separated by thin layer with different plasma characteristics. Convection of plasma within HFA, as observed along spacecraft trajectory by subtracting averaged velocity from observed velocities, show that plasma in each of two regions is moving from separating layer. It indicates that separating layer is the site of energy deposition from interaction of the solar wind with ions reflected from the shock. This is confirmed by analysis of ion velocity distributions in this layer.

  9. Thermal Infrared Anomalies of Several Strong Earthquakes

    PubMed Central

    Wei, Congxin; Guo, Xiao; Qin, Manzhong

    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

  10. Congenital basis of posterior fossa anomalies

    PubMed Central

    Cotes, Claudia; Bonfante, Eliana; Lazor, Jillian; Jadhav, Siddharth; Caldas, Maria; Swischuk, Leonard

    2015-01-01

    The classification of posterior fossa congenital anomalies has been a controversial topic. Advances in genetics and imaging have allowed a better understanding of the embryologic development of these abnormalities. A new classification schema correlates the embryologic, morphologic, and genetic bases of these anomalies in order to better distinguish and describe them. Although they provide a better understanding of the clinical aspects and genetics of these disorders, it is crucial for the radiologist to be able to diagnose the congenital posterior fossa anomalies based on their morphology, since neuroimaging is usually the initial step when these disorders are suspected. We divide the most common posterior fossa congenital anomalies into two groups: 1) hindbrain malformations, including diseases with cerebellar or vermian agenesis, aplasia or hypoplasia and cystic posterior fossa anomalies; and 2) cranial vault malformations. In addition, we will review the embryologic development of the posterior fossa and, from the perspective of embryonic development, will describe the imaging appearance of congenital posterior fossa anomalies. Knowledge of the developmental bases of these malformations facilitates detection of the morphological changes identified on imaging, allowing accurate differentiation and diagnosis of congenital posterior fossa anomalies. PMID:26246090

  11. 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

  12. A Nd Isotopic Composition Modeling Approach of the Oceanic Thermohaline Circulation Change During LGM

    NASA Astrophysics Data System (ADS)

    Arsouze, T.; Dutay, J.; Lacan, F.; Jeandel, C.; Alkama, R.; Kageyama, M.; Piotrowski, A.

    2006-12-01

    The role of thermohaline circulation in climate change has been a matter of debate for a long time. Proxies of past ocean circulation such as δ13C or 231Pa/230Th suggest a relationship between North Atlantic Deep Water (NADW) strength and rapid climate change. Neodymium isotopic composition (Nd IC) is a quasi conservative geochemical tracer of water masses in the ocean interior and thus can be used as a proxy for NADW. Seawater Nd IC being recorded in marine sediments, this proxy is used to infer paleo-circulations on various time scales. Recent studies of Nd IC records, in the ferromanganese oxide components of a South Atlantic core, confirm the close relation between thermohaline circulation and North Atlantic climate changes through the last deglaciation (Piotrowski et al., 2004). Our purpose here is to model the Nd IC during the LGM and the Holocene with the Ocean Global Circulation Model NEMO, in the ORCA2 (2°) configuration. The explicit simulation of this proxy in the model allows to investigate and quantify the circulation change that corresponds to the Nd isotopic composition variation recorded in the sediments. We consider that the main source of Nd into the ocean is the interaction between water masses and continental margins (Boundary Exchange process; (Lacan and Jeandel, 2005). Boundary exchange is parameterized using a relaxing term (Arsouze et al., 2006). Simulated Nd IC distributions are evaluated by comparison with available records for the LGM and Holocene. References: Arsouze, T., Dutay, J.-C., Lacan, F. and Jeandel, C., 2006. Modeling the neodymium isotopic composition with a global ocean circulation model Chemical Geology, in press. Lacan, F. and Jeandel, C., 2005. Neodymium isotopes as a new tool for quantifying exchange fluxes at the continent - ocean interface. Earth and Planetary Science Letters, 232(3-4): 245-257. Piotrowski, A.M., Goldstein, S.L., Hemming, S.R. and Fairbanks, R.G., 2004. Intensification and variability of ocean

  13. Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt

    NASA Astrophysics Data System (ADS)

    Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

    2013-02-01

    The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

  14. Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

    PubMed

    Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

    2015-01-01

    Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. PMID:25278442

  15. Synthesis and thermal stability studies of a series of metastable Dion–Jacobson double-layered neodymium-niobate perovskites

    SciTech Connect

    Josepha, Elisha A.; Farooq, Sara; Mitchell, Cinnamon M.; Wiley, John B.

    2014-08-15

    The Dion–Jacobson double-layered perovskite, RbNdNb{sub 2}O{sub 7}, is used as a precursor to synthesize the series ANdNb{sub 2}O{sub 7} (A=H, Li, Na, K, NH{sub 4}, Ag), and (MCl)NdNb{sub 2}O{sub 7} (M=Mn, Fe, Cu) through ion-exchange reactions ≤400 °C. Thermal stability studies indicated that most of these compounds are metastable. A combination of X-ray powder diffraction and differential thermal analysis were used to determine various low temperature decomposition pathways; these pathways were very dependent on the interlayer species. Overall the ANdNb{sub 2}O{sub 7} series was found to be less stable than the corresponding lanthanides, ALaNb{sub 2}O{sub 7}. - Graphical abstract: A new series of topochemically-prepared metastable neodymium-containing layered perovskites are studied. - Highlights: • A series of new layered neodymium containing perovskites were synthesized by ion exchange. • Products were studied by variable temperature X-ray diffraction and thermal analysis. • Most of the series are metastable showing exothermic transitions on decomposition. • The Nd compounds are less stable due to the smaller size of the Nd relative to La.

  16. Cathodic processes of neodymium(iii) in LiF-NdF3-Nd2O3 melts.

    PubMed

    Huang, Chao; Liu, Xiaolong; Gao, Yuan; Liu, Shizhe; Li, Bing

    2016-08-15

    In this paper, cyclic voltammetry and square wave voltammetry are applied to characterize the cathode processes of neodymium ions on a W electrode in LiF-NdF3 melts with or without the metal Nd. The results indicate that neodymium ions in the LiF-NdF3 (2 wt%) melt are reduced in two steps, i.e. Nd(3+) → Nd(2+) and Nd(2+) → Nd(0), corresponding to starting reduction potentials of 0.35 V vs. Li(+)/Li and 0.1 V vs. Li(+)/Li, respectively. The Nd(3+) → Nd(2+) process is controlled by mass transfer and the Nd(2+) → Nd(0) process is controlled by both an interfacial step and mass transfer. But in the LiF-NdF3 melt with excess metal Nd equilibrium, the kinetics of the above two processes are controlled by mass transfer. After potentiostatic electrolysis at 0.35 V in the LiF-NdF3-Nd2O3 melt NdF2 is formed on the Mo cathode, and metallic Nd is obtained by potentiostatic electrolysis at 0.1 V in the LiF-NdF3-Nd2O3-Nd melt, which validates the above electrochemical reduction results. PMID:27197114

  17. Neodymium-YAG laser iridotomy in the treatment and prevention of angle closure glaucoma. A review of 373 eyes.

    PubMed

    Tomey, K F; Traverso, C E; Shammas, I V

    1987-04-01

    The records of 271 consecutive patients (373 eyes) who underwent neodymium-YAG laser iridotomy at our institution over a period of 12 months were reviewed. The majority of eyes (60.5%) were treated for chronic primary angle closure glaucoma, 23.3% had prophylactic iridotomy for occludable angles, 7.8% were treated for acute angle closure glaucoma, 3.2% required iridotomy for the relief of iris bombé secondary to anterior uveitis, and the rest (5.2%) were treated for miscellaneous causes of secondary angle closure. Laser iridotomy, with or without medical treatment, obviated further surgical treatment in most categories of eyes. Visual acuity remained unchanged or improved in the great majority (92%) of cases over the period of follow-up (range, two to 12 months; median, four months). Visual deterioration in 8% of eyes was attributed to the usual causes, such as normal cataract progression, but none was believed to be related to the laser treatment. This article discusses the advantages of the neodymium-YAG laser (over argon) for performing iridotomies. PMID:3566599

  18. Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum.

    PubMed

    Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Suh, Sangwon; Shigetomi, Yosuke; Oshita, Yuko

    2014-01-01

    This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows. PMID:24387330

  19. Analysis of Renal Anomalies in VACTERL Association

    PubMed Central

    Cunningham, Bridget K.; Khromykh, Alina; Martinez, Ariel F.; Carney, Tyler; Hadley, Donald W.; Solomon, Benjamin D.

    2014-01-01

    VACTERL association refers to a combination of congenital anomalies that can include: Vertebral anomalies, Anal atresia, Cardiac malformations, Tracheo-Esophageal fistula with esophageal atresia, Renal anomalies (typically structural renal anomalies), and Limb anomalies. We conducted a description of a case series to characterize renal findings in a cohort of patients with VACTERL association. Out of the overall cohort, 48 patients (with at least 3 component features of VACTERL and who had abdominal ultrasound performed) met criteria for analysis. Four other patients were additionally analyzed separately, with the hypothesis that subtle renal system anomalies may occur in patients who would not otherwise meet criteria for VACTERL association. Thirty-three (69%) of the 48 patients had a clinical manifestation affecting the renal system. The most common renal manifestation (RM) was vesicoureteral reflux (VUR) in addition to a structural defect (present in 27%), followed by unilateral renal agenesis (24%), and then dysplastic/multicystic kidneys or duplicated collected system (18% for each). Twenty-two (88%) of the 25 patients with a structural RM had an associated anorectal malformation. Individuals with either isolated lower anatomic anomalies, or both upper and lower anatomic anomalies were not statistically more likely to have a structural renal defect than those with isolated upper anatomic anomalies (p=0.22, p=0.284 respectively). Given the high prevalence of isolated VUR in our cohort, we recommend a screening VCUG or other imaging modality be obtained to evaluate for VUR if initial renal US shows evidence of obstruction or renal scarring, as well as ongoing evaluation of renal health. PMID:25196458

  20. Considerations in the Interpretation of Cosmological Anomalies

    NASA Astrophysics Data System (ADS)

    Peiris, Hiranya V.

    2014-05-01

    Anomalies drive scientific discovery - they are associated with the cutting edge of the research frontier, and thus typically exploit data in the low signal-to-noise regime. In astronomy, the prevalence of systematics - both ``known unknowns'' and ``unknown unknowns'' - combined with increasingly large datasets, the widespread use of ad hoc estimators for anomaly detection, and the ``look-elsewhere'' effect, can lead to spurious false detections. In this informal note, I argue that anomaly detection leading to discoveries of new physics requires a combination of physical understanding, careful experimental design to avoid confirmation bias, and self-consistent statistical methods. These points are illustrated with several concrete examples from cosmology.

  1. Crustal structure interpreted from magnetic anomalies

    NASA Technical Reports Server (NTRS)

    Phillips, Jeffrey D.; Reynolds, Richard L.; Frey, Herbert

    1991-01-01

    This review, discusses publications during the last quadrennium (1987-1990) that used aeromagnetic data, marine magnetic data, satellite magnetic data, and rock magnetic and petrologic data to provide information on the sources of magnetic anomalies. The publications reviewed reflect increased integration of rock magnetic property and petrologic studies with magnetic anomaly interpretation studies, particularly in deep crustal magnetization, exploration for hydrocarbons, and inversion of marine magnetic anomalies. Interpretations of aeromagnetic data featuring image display techniques and using the horizontal gradient method for locating magnetization boundaries became standard.

  2. Magnetic and gravity anomalies in the Americas

    NASA Technical Reports Server (NTRS)

    Braile, L. W.; Hinze, W. J.; Vonfrese, R. R. B. (Principal Investigator)

    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.

  3. Non-standard symmetries and quantum anomalies

    SciTech Connect

    Visinescu, Anca; Visinescu, Mihai

    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.

  4. Generation of acoustic waves by focused infrared neodymium-laser radiation

    NASA Astrophysics Data System (ADS)

    Ward, Barry

    1991-02-01

    When the radiation from a sufficiently powerful pulsed laser is focused into the transparent gaseous, liquid or solid media, dielectric breakdown may occur around the beam waist giving rise to a short-lived high-temperature plasma which quickly heats the surrounding material. As a consequence of various energy-coupling mechanisms, this phenomenon causes the emission of one or more high-frequency ultrasonic acoustic waves whose speeds of propagation are dependent upon the physical properties of the host medium. In the high-speed photographic studies described, the 1.06 micron near-infrared radiation from an 8-ns, 10-mJ Q-switched Nd:YAG laser is focused in or onto a variety of fluid and solid materials. The rapid variations in density around the resulting plasma events are visualized using a Mach-Zehnder interferometer with a sub-nanosecond dye-laser light source and a video-imaging system. Calculations of the corresponding transient pressure distributions are then enacted from the digitally-recorded interferograms using a semi-automatic procedure under the control of a personal computer. Measurements of position, displacement, and velocity are also carried out using the same optical apparatus in schlieren and focused shadowgraph high-speed photographic measurements. The experimental work outlined in the following chapters is divided into three broad fields of interest. In the first of these, a study of the laser-generation of spherical shock waves in atmospheric air is carried out. In the second, the neodymium-laser beam is focused onto different solid-fluid interfaces resulting in the formation of bulk longitudinal and shear waves and surface acoustic waves. The interactions of these waves with various obstacles and defects are investigated with reference to their application to non-destructive testing. In the third and most important field, a detailed study of the dynamics of laser-induced cavitation bubbles in water is carried out. With regard to the associated

  5. Formation, structural and optical characterization of neodymium doped-zinc soda lime silica based glass

    NASA Astrophysics Data System (ADS)

    Zamratul, M. I. M.; Zaidan, A. W.; Khamirul, A. M.; Nurzilla, M.; Halim, S. A.

    New glass system of neodymium - doped zinc soda lime silica glass has been synthesized for the first time by melt-quenching of glass waste soda lime silica (SLS) with zinc oxide (ZnO) as precursor glass and Nd2O3 as dopant. In order to examine the effect of Nd3+ on the structural and optical properties, the prepared sample of structure [(ZnO)0.5(SLS)0.5](Nd2O3)x (x = 0, 1, 2, 3, 4 and 5 wt%) was characterized through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy (UV-Vis) and the photoluminescence (PL). XRD pattern justifies the amorphous nature of synthesized glasses. FTIR spectroscopy has been used to observe the structural evolution of ZnO4 and SiO4 groups. The UV-Vis-NIR absorption spectra reveals seven peaks centered at excitation of electron from ground state 4I9/2 to 4D3/2 + 4D5/2 (∼360 nm), 2G9/2 + 2D3/2 + 2P3/2(∼470 nm), 2K13/2 + 4G7/2 + 4G9/2 (∼523 nm), 4G5/2 + 2G7/2 (∼583 nm), 4F9/2 (∼678 nm), 4S3/2 + 4F7/2 (∼748 nm) and 4F5/2 + 2H9/2 (∼801 nm). PL spectra under the excitation of 800 nm display four emission bands centered at 531 nm, 598 nm, 637 nm and 671 nm corresponding to 4G7/2 → 4I9/2, (4G7/2 → 4I11/2, 4G5/2 → 4I9/2), (4G5/2 → 4I11/2) and (4G7/2 → 4I13/2, 4G5/2 → 4I11/2) respectively.

  6. 87Sr/86Sr anomalies in Late Cretaceous-Early Tertiary strata of the Cauvery basin, south India: Constraints on nature and rate of environmental changes across K-T boundary

    NASA Astrophysics Data System (ADS)

    Ramkumar, Mu; Stüben, Doris; Berner, Zsolt; Schneider, Jens

    2010-02-01

    The Ariyalur-Pondicherry sub-basin of the Cauvery basin comprises a near complete stratigraphic record of Upper Cretaceous-Lower Tertiary periods. Earlier studies have documented variations of clay mineral assemblages, change in microtexture of siliciclasts and many geochemical and stable isotopic anomalies far below the Cretaceous-Tertiary boundary (KTB) in these strata. This paper documents the occurrences of two positive 87Sr/86Sr anomalies preceding K-T boundary in this basin and discusses plausible causes. Analysis of trace elemental and stable isotopic profiles, sedimentation history, petrography and mineralogy of the rocks reveal that while both the anomalies may be due to increased detrital influx caused by sea level and climatic changes, the second anomaly might have been influenced by Deccan volcanism which in turn predated KTB. Record of such anomalies preceding K-T boundary supports the view of multi-causal step-wise extinction of biota across KTB.

  7. From the subtropics to the equator in the Southwest Pacific: Continental material fluxes quantified using neodymium data along modeled thermocline water pathways

    NASA Astrophysics Data System (ADS)

    Grenier, Mélanie; Jeandel, Catherine; Cravatte, Sophie

    2014-06-01

    The southwestern tropical Pacific, part of a major pathway for waters feeding the Equatorial Undercurrent, is a region of important geochemical enrichment through land-ocean boundary exchange. Here we develop an original method based on the coupling between dynamical modeling and geochemical tracer data to identify regions of enrichment along the water pathways from the subtropics to the equator, and to allow a refined quantification of continental material fluxes. Neodymium data are interpreted with the help of modeled Lagrangian trajectories of an Ocean General Circulation Model. We reveal that upper and lower thermocline waters have different pathways together with different geochemical evolutions. The upper thermocline waters entering the Solomon Sea mainly originate from the central subtropical gyre, enter the Coral Sea in the North Vanuatu Jet and likely receive radiogenic neodymium from the basaltic island margins encountered along their route. The lower thermocline waters entering the Solomon Sea mainly originate from northeast of New Zealand and enter the Coral Sea in the North Caledonian Jet. Depletion of their neodymium content likely occurs when flowing along the Australian and Papua coasts. Downstream from the Solomon Sea, waters flowing along the Papua New Guinea margins near the Sepik river mouth become surprisingly depleted in their neodymium content in the upper thermocline while enriched in the lower thermocline. This coupled approach is proposed as strong support to interpret the origin of the equatorial Pacific natural fertilization through a better understanding of the circulation, important objectives of the international GEOTRACES and SPICE programs, respectively.

  8. Method for separating isotopes

    DOEpatents

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  9. 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.

  10. 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)

  11. Magnetosheath Flow Anomalies in 3-D

    NASA Technical Reports Server (NTRS)

    Vaisberg, O. L.; Burch, J. L.; Smirnov, V. N.; Avanov, L. A.; Moore, T. E.; Waite, J. H., Jr.; Skalsky, A. A.; Borodkova, N. L.; Coffey, V. N.; Gallagher, D. L.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Measurements of the plasma and magnetic field with high temporal resolution on the Interball Tail probe reveal many flow anomalies in the magnetosheath. They are usually seen as flow direction and number density variations, accompanied by magnetic field discontinuities. Large flow anomalies with number density variations of factor of 2 or more and velocity variations of 100 km/s or more are seen with periodicity of about I per hour. The cases of flow anomalies following in succession are also observed, and suggest their decay while propagating through the magnetosheath. Some magnetospheric disturbances observed in the outer magnetosphere after the satellite has crossed the magnetopause on the inbound orbit suggest their association with magnetosheath flow anomalies observed in the magnetosheath prior to magnetopause crossing.

  12. Tunguska Genetic Anomaly and Electrophonic Meteors

    NASA Astrophysics Data System (ADS)

    Silagadze, Z. K.

    2005-03-01

    One of great mysteries of the Tunguska event is its genetic impact. Some genetic anomalies were reported in the plants, insects and people of the Tunguska region. Remarkably, the increased rate of biological mutations was found not only within the epicenter area, but also along the trajectory of the Tunguska Space Body (TSB). At that no traces of radioactivity were found, which could be reliably associated with the Tunguska event. The main hypotheses about the nature of the TSB, a stony asteroid, a comet nucleus or a carbonaceous chondrite, readily explain the absence of radioactivity but give no clues how to deal with the genetic anomaly. A choice between these hypotheses, as far as the genetic anomaly is concerned, is like to the choice between ``blue devil, green devil and speckled devil'', to quote late Academician N.V. Vasilyev. However, if another mysterious phenomenon, electrophonic meteors, is evoked, the origin of the Tunguska genetic anomaly becomes less obscure.

  13. Lunar magnetic anomalies and surface optical properties

    NASA Astrophysics Data System (ADS)

    Hood, L. L.; Schubert, G.

    1980-04-01

    Consideration is given to the influence of lunar magnetic anomalies on the darkening of the lunar surface by solar wind ion bombardment. It is shown that lunar magnetic anomalies with dipole moments much greater than 5 x 10 to the 13th gauss cu cm will strongly deflect the typical solar wind, producing local plasma voids at the lunar surface. Direct measurements of lunar magnetic fields have shown most lunar magnetic fields to have moments below this level, with the exception of anomalies detected in the areas of the Reiner Gamma albedo feature, the Van de Graaff-Aitken region and Mare Marginis. Such magnetic anomalies are shown to be capable of accounting for the higher albedo and swirl-like morphology f these features by the deflection and focusing incident solar wind ions, which tend to darken the surface upon impact.

  14. Flyby Anomaly Test Integrating Multiple Approaches (FATIMA)

    NASA Technical Reports Server (NTRS)

    Levit, Creon; Jaroux, Belgacem Amar

    2014-01-01

    FATIMA is a mission concept for a small satellite to investigate the flyby anomaly - a possible velocity increase that has been observed in some earlier satellites when they have performed gravitational swingy maneuvers of the earth.

  15. Reduction of satellite magnetic anomaly data

    NASA Technical Reports Server (NTRS)

    Slud, E. V.; Smith, P. J.; Langel, R. A.

    1984-01-01

    Analysis of global magnetic anomaly maps derived from satellite data is facilitated by inversion to the equivalent magnetization in a constant thickness magnetic crust or, equivalently, by reduction to the pole. Previous inversions have proven unstable near the geomagnetic equator. The instability results from magnetic moment distributions which are admissible in the inversion solution but which make only small contribution to the computed values of anomaly field. Their admissibility in the solution could result from noisy or incomplete data or from small poorly resolved anomalies. The resulting magnetic moments are unrealistically large and oscillatory. Application of the method of principal components (e.g. eigenvalue decomposition and selective elimination of less significant eigenvectors) is proposed as a way of overcoming the instability and the method is demonstrated by applying it to the region around the Bangui anomaly in Central Africa.

  16. US Aeromagnetic and Satellite Magnetic Anomaly Comparisons

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W. (Principal Investigator); Sexton, J. L.

    1984-01-01

    Scalar aeromagnetic data obtained by the U.S. Naval Oceanographic Office (NOO) Vector Magnetic Survey of the conterminous U.S. were screened for periods of intense diurnal magnetic activity and reduced to anomaly form, filtered, and continued upward. A number of correlations between the NOO, POGO and preliminary MAGSAT data are evident at satellite elevations, including a prominent transcontinental magnetic high which extends from the Anadarko Basin to the Cincinnati Arch. The transcontinental magnetic high is breached by negative anomalies located over the Rio Grande Rift and Mississippi River Aulacogen. Differentially reduced-to-pole NOO and POGO magnetic anomaly data show that the transcontinental magnetic high corresponds to a well-defined regional trend of negative free-air gravity and enhanced crustal thickness anomalies.

  17. Geologic analysis of averaged magnetic satellite anomalies

    NASA Technical Reports Server (NTRS)

    Goyal, H. K.; Vonfrese, R. R. B.; Ridgway, J. R.; Hinze, W. J.

    1985-01-01

    To investigate relative advantages and limitations for quantitative geologic analysis of magnetic satellite scalar anomalies derived from arithmetic averaging of orbital profiles within equal-angle or equal-area parallelograms, the anomaly averaging process was simulated by orbital profiles computed from spherical-earth crustal magnetic anomaly modeling experiments using Gauss-Legendre quadrature integration. The results indicate that averaging can provide reasonable values at satellite elevations, where contributing error factors within a given parallelogram include the elevation distribution of the data, and orbital noise and geomagnetic field attributes. Various inversion schemes including the use of equivalent point dipoles are also investigated as an alternative to arithmetic averaging. Although inversion can provide improved spherical grid anomaly estimates, these procedures are problematic in practice where computer scaling difficulties frequently arise due to a combination of factors including large source-to-observation distances ( 400 km), high geographic latitudes, and low geomagnetic field inclinations.

  18. Method of Mapping Anomalies in Homogenous Material

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

    2016-01-01

    An electrical conductor and antenna are positioned in a fixed relationship to one another. Relative lateral movement is generated between the electrical conductor and a homogenous material while maintaining the electrical conductor at a fixed distance from the homogenous material. The antenna supplies a time-varying magnetic field that causes the electrical conductor to resonate and generate harmonic electric and magnetic field responses. Disruptions in at least one of the electric and magnetic field responses during this lateral movement are indicative of a lateral location of a subsurface anomaly. Next, relative out-of-plane movement is generated between the electrical conductor and the homogenous material in the vicinity of the anomaly's lateral location. Disruptions in at least one of the electric and magnetic field responses during this out-of-plane movement are indicative of a depth location of the subsurface anomaly. A recording of the disruptions provides a mapping of the anomaly.

  19. Renal Anomalies Associated with Ectopic Neurohypophysis

    PubMed Central

    Özen, Samim; Şişmek, Damla Gökşen; Önder, Asan; Darcan, Şükran

    2011-01-01

    Objective: Although the etiology of ectopic neurohypophysis that leads to pituitary hormone deficiencies is not yet clearly understood, birth trauma or genetic factors have been considered responsible. Concurrent cranial and extracranial congenital anomalies have been reported in such cases. The aim of the present study was to investigate the frequency of renal anomalies in nonsyndromic cases with ectopic neurohypophysis. Methods: We retrospectively evaluated the medical records of 20 patients with ectopic neurohypophysis who were followed up between January 1990 and December 2007 in a tertiary University Hospital. Results: Renal anomalies were identified in three (15%) cases including unilateral renal agenesis in one case, renal hypoplasia in one case, and double collecting system and unilateral renal agenesis in one case. Conclusions: In the present study, the increased frequency of renal anomalies in cases of ectopic neurohypophysis was highlighted, and it was emphasized that there might be common genetic factors that lead to such associations. Conflict of interest:None declared. PMID:21750632

  20. 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.