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1

METEORITIC KRYPTON AND BARIUM VERSUS THE GENERAL ISOTOPIC ANOMALIES IN METEORITIC XENON  

Microsoft Academic Search

General isotopic anomalies in meteoritic xenon are described in detail. ; Where superior isotopic analyses exist, the xenon anomalies appear to be the same ; for all meteorites. In other cases there is fair evidence that the xenon ; examined is a mixture of meteoritic and contaminating atmospheric xenon. Two ; superior krypton analyses for carbonaceous chondrites show no anomalies

D. Krummenacher; C. M. Merrihue; R. O. Pepin; J. H. Reynolds

1962-01-01

2

Isotopic thermal diffusion of krypton  

NASA Astrophysics Data System (ADS)

Isotopic thermal diffusion factors have been determined for krypton in the temperature range from 243.0 K up to 777.5 K. A theoretical comparison is reported for the exponential-six model and two sets of parameters are discussed. Some references are also made for several multiparametric models.

Cunha, M. urea; Laranjeira, M. F.

1985-12-01

3

Isotopic Thermal-Diffusion Factor for Krypton  

Microsoft Academic Search

The isotopic thermal-diffusion factor ?0 for krypton has been determined over a temperature range of 242 to 643K. An artificial mixture of krypton isotopes containing about 14% 82Kr and 10% 86Kr was utilized in this study in conjunction with a 10-tube swing separator, ?0 being obtained from the concentration changes in these two isotopes only. A least-squares fitting procedure yields

R. Paul; W. W. Watson

1966-01-01

4

A Redetermination of the Relative Abundances of the Isotopes of Neon, Krypton, Rubidium, Xenon, and Mercury  

Microsoft Academic Search

A careful redetermination of isotopic abundance ratios in neon, krypton, rubidium, xenon, and mercury has been made. The mass spectrometer employed was calibrated for mass discriminative effects with a synthetic argon isotope mixture made from essentially pure samples of A36 and A40. The present results together with those obtained from an earlier study on carbon, nitrogen, oxygen, argon, and potassium

Alfred O. Nier

1950-01-01

5

Chromium isotopic anomalies in the Murchison meteorite  

NASA Astrophysics Data System (ADS)

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.

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

1989-02-01

6

Production of Krypton and Xenon Isotopes by Galactic Protons  

NASA Astrophysics Data System (ADS)

The production of krypton from target elements Rb (Rb(sub)2SO(sub)4), Sr (SrF(sub)2), Y, Zr, and of xenon in Ba (Ba glass), La (LaF(sub)3) is studied in a simulation experiment of the galactic cosmic-ray proton bombardment of stony meteoroids in space [1,2]. This investigation is part of the experiment LNS 172 by which a 50-cm-diameter artificial meteoroid (gabbro) was isotropically irradiated at Saturne with 1.6 GeV protons. Measurements of krypton production vs. depth are now complete in the four investigated target elements. In the ^81Kr-^83Kr dating method, the production ratio P(sub)81/P(sub)83 can be evaluated from the cosmogenic spectrum of krypton in the meteorite according to the formula: P(sub)81/P(sub)83=0.95[(^80Kr/^83Kr)(sub)c+(^82Kr/^83Kr)(sub)c]/2 [3] where (^80Kr/^83Kr)(sub)c and (^82Kr/^83Kr)c represent the measured cosmogenic ratios assuming no contribution from (n,gamma) nuclear reactions on Br. Applying this formula to this experiment, a good agreement with the measured production ratio is obtained for Zr and Y targets. On the other hand, this formula overestimates the measured production ratio by 6% for Sr and 15% for Rb. Taking a mean composition of ordinary chondrites [4], the production ratio ^81Kr/^83Kr decreases from the surface to the center by 4% but the value calculated with the formula still exceeds the measured ratio by 7%. The ratio ^78Kr/^83Kr also shows a decrease by 10% from the surface to the center. Variation by 20% of the concentration of target elements can change this ratio by 10%, but, for the same variation, dependence on the target chemistry is less than 4% for ^81Kr/^83Kr. For Xe, depth profiles of production in Ba and La are reported. Production of ^126Xe shows a steep increase from the surface to center by a factor of 1.5 for Ba and of 2 for La. All the production ratios also increase from the surface to the center except ^124Xe/^126Xe, which is decreasing and ^136Xe/^126Xe, which is almost constant. This work was partially supported by C.N.R.S., by IN2P3, and by INSU (Programme National de Planetologie). References: [1] Michel R. et al (1991) Meteoritics, 26, 372a. [2] Gilabert et al. (1992) Meteoritics, 27, 223. [3] Marti K. (1967) Phys. Rev. Lett., 18, 264-266. [4] Wasson J. T. and Kallemeyn G. W. (1988) Phil. Trans. R. Soc., A325, 535-544.

Gilabert, E.; Lavielle, B.; Simonoff, G. N.; Rosel, R.; Herpers, U.; Schnatz-Buttgen, M.; Lupke, M.; Michel, R.

1993-07-01

7

Isotopic anomalies - Chemical memory of Galactic evolution  

NASA Technical Reports Server (NTRS)

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.

Clayton, Donald D.

1988-01-01

8

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

SciTech Connect

Phase 1 studies focused on the annealing (transient melting) of silicon and germanium targets with a krypton-fluoride (KrF) excimer laser. A suitable target of a semiconducting material--as a means of storing noble gas atoms--is a key component of a device called the RISTRON for counting isotopes of a noble gas. A means for isotopic selective counting of atoms such as 39Ar for ocean water circulation studies and 81Kr for groundwater and ice-cap dating would be of considerable interest to earth scientists. In the RISTRON, ions are created by resonance ionization of neutral krypton atoms released from one of the targets by pulsed laser melting, and these ions are implanted in a second target after isotopic enrichment. The studies evaluated the space charge or plasma effects created as an undesirable by-product of the annealing of a semiconductor with a pulsed excimer laser. The studies showed that the space charge produced when either silicon or germanium is annealed with a KrF laser can be removed with modest electric fields in less than one microsecond.

Hurst, G.S.

1988-08-25

9

Determination of the Natural Abundances of Krypton and Xenon Isotopes Using Mass Spectrometry: A Demonstration of Isotopes and the Basis of Atomic Mass  

Microsoft Academic Search

This paper describes the use of a gas chromatograph-mass spectrometer to demonstrate the existence of isotopes to students in an introductory chemistry course. Fragmentation reactions are avoided through the use of a noble gas (krypton or xenon) as the analyte. Students are able to readily identify the naturally occurring isotopes of the noble gas, and the quantitative mass spectrometric data

David N. Blauch; Merlyn D. Schuh; Felix A. Carroll

2002-01-01

10

The identification of meteorite inclusions with isotope anomalies  

NASA Astrophysics Data System (ADS)

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.

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

1989-03-01

11

Models for Interpreting Tungsten Isotope Anomalies in the Earth's Crust  

NASA Astrophysics Data System (ADS)

There have been several reports of positive tungsten isotope anomalies of about +15 ppm in rocks from Nuvvuagittuq (4.3 Ga), Isua (3.8 Ga) and Kostomuksha (2.8 Ga) that challenge models of differentiation and mantle mixing. Here, we employ constraints from experimental partitioning of W between metal and silicate, and from partial melting models, to evaluate the production and preservation of these W isotope anomalies in the Earth's earliest crust. We will also provide a revised interpretation of the Kostomuksha W isotope anomalies based on flow differentiation and metamorphism of komatiites. Two sets of models are produced. Model Set 1: Because D(metal-silicate) for W diminishes with increasing depth, the deep mantle has a higher W abundance, and a lower Hf/W ratio and consequently evolves a negative anomaly in W while the upper mantle evolves a complementary positive anomaly. Subsequent solid-state convection (4.55-2.8 Ga) mixes away the complementary W isotope anomalies to yield the modern mantle null value. This set of models predicts that the complementary negative anomalies in W should eventually be discovered in ancient magmatic rocks of deep mantle origin such as komatiites. Model Set 2: Tungsten is significantly more incompatible (like U, Th and Ba) than Hf, the latter being similar in compatibility to Sm. Our results show that extraction of low-degree partial melts (<2%) leaving a Hadean depleted mantle that can have Sm/Nd~20% higher than chondrites also creates a f(Hf/W)~2-3, sufficient to generate the anomalies observed in Archean rocks. These models increase Hf/W and Sm/Nd ratios in a correlated fashion explaining the tendency of positive W isotope anomalies to occur in rocks with positive Nd isotope anomalies. Recycling of the complementary Hadean crust would result in negative anomalies in later plume lavas, while partitioning of W into an enriched "hidden reservoir" would not. Nd isotope anomalies indicate a melting event around 35-75 Ma after solar system formation, the upper end of which is consistent with our models of Hf/W fractionation, that also yield a depleted mantle composition consistent with DMM. Production of the anomalies is accompanied by the need to preserve the anomalies. We argue that the most effective means of preserving the W isotope anomalies is by crustal storage, and we hypothesize that W is efficiently recycled back to juvenile crust during subduction zone processing. Eventually, the addition of juvenile W from the mantle will dilute the positive W isotope anomalies stored in the early crust. The amount of juvenile W required to be added is about a factor of 4 or more, and it is likely that this occurred during the late Archean crustal growth phase (2.5 Ga), so that positive W isotope anomalies are not likely to occur in much younger rocks. A secular decline in crustal W isotope anomalies is predicted.

Humayun, M.; Brandon, A. D.; Righter, K.

2012-12-01

12

Zinc isotope anomalies. [In Allende meteorite  

SciTech Connect

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. 32 refs.

Volkening, J.; Papanastassiou, D.A. (California Institute of Technology, Pasadena (USA))

1990-07-01

13

Zinc isotope anomalies in Allende meteorite inclusions  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

14

Zinc isotope anomalies. [in Allende meteorite  

NASA Technical Reports Server (NTRS)

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.

Volkening, J.; Papanastassiou, D. A.

1990-01-01

15

Endemic Mo Isotopic Anomalies in Iron and Carbonaceous Meteorites  

NASA Technical Reports Server (NTRS)

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).

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

2004-01-01

16

The longevity of the South Pacific isotopic and thermal anomaly  

USGS Publications Warehouse

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

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

1991-01-01

17

Isotopic anomalies from neutron reactions during explosive carbon burning  

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

18

A few remarks regarding the major isotope anomalies in meteorites  

NASA Astrophysics Data System (ADS)

Clayton et al. (1973) have studied oxygen isotopic ratios in some inclusions of Allende, and found values which are very different from those obtained in terrestrial samples. The anomalies were interpreted as being related to the admixture of pure 0-16 carried by interstellar grains. The discovery made by Clayton et al. appears to be a strong argument in favor of the possibility that the formation of the solar system might have been initiated by the explosion of a nearby supernova. However, it has now been found that the observed isotope variation pattern might have been caused also by processes not related to nuclear effects. Attention is also given to neon anomalies, and the magnesium isotopic patterns. The implications of the observed data are discussed.

Audouze, J.

1984-06-01

19

Isotopic anomalies in high Z elements: Uranium  

SciTech Connect

Uranium in terrestrial volcanic ejecta from mantle-related sources has been analyzed mass spectrometrically. The objective was to seek supporting evidence for or refutation isotopic variations reported by Fried et al. (1985) for some such samples. The possibility that terrestrial U is not of constant isotopic composition is extraordinary. If true, mechanisms for creating the variation must be sought and the lack of homogenization within the earth addressed. Samples of 100 grams or more were processed in order to minimize reagent and environmental (laboratory) blank interference and to permit isolation of large amounts (several to tens of ..mu..g) of U for the mass spectrometer (MS) measurements, which utilizes aliquots of /approximately/1 ..mu..g. Aliquants from four volcanic samples gave data which indicate enrichments of /sub 235/U ranging from 0.2% to 5.9% in the 235/238 ratio relative normal uranium ratios. These relative enrichments are consistent with, and in some cases, higher than the 0.18% enrichment reported by Fried et al. (1985) for two volcanic lava samples. However, we were not able to reproduce their results on the Kilauea lava for which they report 0.18% /sup 235/U enrichment. The relative error in our MS ratios is 0.05% -- 0.07%. 1 tab.

Jovanovic, S.; Reed, G.W. Jr.; Essling, A.M.; Rauh, E.G.; Graczyk, D.G.

1989-03-01

20

NEUTRON-RICH CHROMIUM ISOTOPE ANOMALIES IN SUPERNOVA NANOPARTICLES  

SciTech Connect

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.

Dauphas, N. [Origins Laboratory, Department of the Geophysical Sciences and Enrico Fermi Institute, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States); Remusat, L.; Papanastassiou, D. A.; Guan, Y.; Ma, C.; Eiler, J. M. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Chen, J. H. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Roskosz, M.; Stodolna, J., E-mail: dauphas@uchicago.ed [Unite Materiaux et Transformations, Universite de Lille 1, CNRS UMR 8207, 59655 Villeneuve d'Ascq (France)

2010-09-10

21

More on Ru Endemic Isotope Anomalies in Meteorites  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

22

Neutron-poor Nickel Isotope Anomalies in Meteorites  

NASA Astrophysics Data System (ADS)

We present new, mass-independent, Ni isotope data for a range of bulk chondritic meteorites. The data are reported as ?60Ni58/61, ?62Ni58/61, and ?64Ni58/61, 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 ?60Ni58/61, ?62Ni58/61, and ?64Ni58/61 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 ?62Ni58/61 and ?64Ni58/61, 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 ?62Ni58/61 and ?64Ni58/61. 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 that the Ni isotopic variability of the solar system cannot be explained by mixing with a component of bulk stellar ejecta from either SN II, Wolf-Rayet or, an asymptotic giant branch source and is unlikely to result from bulk mixing of material from an SN Ia. However, variable admixture of material from the Si/S zone of an SN II can create all the characteristics of Ni isotope variations in solar system materials. Moreover, these characteristics can also be provided by an SN II with a range of masses from 15 to 40 M ?, showing that input from SN II is a robust source for Ni isotope variations in the solar system. Correlations of Ni isotope anomalies with O, Cr, and Ti isotope ratios and Pb/Yb in bulk meteorites suggest that the heterogeneous distribution of isotopic anomalies in the early solar system likely resulted from nebular sorting of chemically or physically different materials bearing different amounts of isotopes synthesized proximally to the collapse of the protosolar nebula.

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

2012-10-01

23

NEUTRON-POOR NICKEL ISOTOPE ANOMALIES IN METEORITES  

SciTech Connect

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

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

2012-10-10

24

On isotopic anomalies in samarium. [in Allende meteorite  

NASA Technical Reports Server (NTRS)

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.

Clayton, D. D.

1979-01-01

25

Isotopic anomalies and proton irradiation in the early solar system  

NASA Technical Reports Server (NTRS)

Nuclear cross sections relevant to the various isotopic-abundance anomalies found in solar-system objects are evaluated in an attempt to set constraints on the hypothesized mechanism of irradiation of forming planetesimals by energetic protons from the young sun. A power-law proton spectrum is adopted, attention is restricted to proton energies less than about 20 MeV, and average cross sections are calculated for several reactions that might be expected to lead to the observed anomalies. The following specific anomalies are examined in detail: Al-26, Na-22, Xe-126, I-129, Kr-80, V-50, Nb-92, La-138, Ta-180, Hg-196, K-40, Ar-36, O-17, O-18, N-15, C-13, Li, Be, and B. It is suggested that the picture of presolar-grain carriers accounts for the facts more naturally than do irradiation models.

Clayton, D. D.; Dwek, E.; Woosley, S. E.

1977-01-01

26

Wolf-Rayet Stars and the Isotopic Anomaly Connection  

NASA Astrophysics Data System (ADS)

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 stellar evolutionary models that incorporate extended nuclear reaction networks, as well as recent improvements in our knowledge of various basic physical ingredients, like mass loss rates, opacities, or nuclear reaction rates. Results will be presented for various radionuclides with lifetimes in excess of ~10^5 yr, which are considered to be responsible for certain observed anomalies, or which could lead to anomalies that remain unobserved at present. Isotopic patterns for the elements ranging from carbon to lead will also be presented. Those predictions will be confronted with existing data, or will help unravel cases of potential interest for further laboratory quest. References: [1] Harper C. L. Jr. (1992) In Nuclei in the Cosmos II (F. Kappeler and K. Wisshak, eds.), 113-126, IOP Publ. Co. [2] Williams P. M. et al. (1992) Mon. Not. R. Astron. Soc., 258, 461-475. [3] Reeves H. (1978) In Protostars and Planets (T. Gehrels, ed.), 339-426, Univ. of Arizona. [4] Arnould M. and Prantzos N. (1986) In Nucleosynthesis and Its Implications on Nuclear and Particle Physics, (J. Audouze and N. Mathieu, eds.), 363-372, Reidel. [5] Meynet G. and Arnould M. (1993) In Origin and Evolution of the Elements (N. Prantzos et al., eds.), Cambridge, in press.

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

1993-07-01

27

MULTIPLE ORIGINS OF NITROGEN ISOTOPIC ANOMALIES IN METEORITES AND COMETS  

SciTech Connect

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.

Aleon, Jerome, E-mail: Jerome.Aleon@csnsm.in2p3.f [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CSNSM-CNRS-IN2 P3, Bat 104, Orsay Campus 91405 (France)

2010-10-20

28

Relationships Among Isotopic Compositions of Solar-System Xenon and Krypton  

NASA Astrophysics Data System (ADS)

A remarkably large number of isotopically different trapped Xe and Kr compositions have been measured in meteorite carrier phases or inferred to exist in the early solar system. For Xe these include a group here collectively termed "Q-type" Xe: Xe-Q, Xe-P1, OC (ordinary chondrite)-Xe, AVCC (average carbonaceous chondrite)-Xe, and ureilite Xe (e.g., Kenna and Novo Urei), all of which have been put forward at one time or another as candidates for "primordial" solar-system Xe. Presolar meteoritic diamonds contain a second and different suite of isotopically distinct compositions: Xe-P3, Xe-HL, and Xe-P6e ("exotic"). Another, Xe-S, is prominent in interstellar silicon carbide. Each of these is accompanied in its carrier by a corresponding Kr composition. In addition an originally inferred but now detected composition called U-Xe is a promising primordial parent for nonradiogenic terrestrial Xe; both U-Xe and its associated Kr, Kr-1, appear to be present in solar wind (SW) Xe and Kr. Such an extensive and isotopically diverse set of compositions might well be expected from nucleosynthetic theory. The possibility explored here, however, is that some of them are not truly independent, but may instead reflect fractionation or mixing of a smaller subset of primary components.

Pepin, R. O.

1996-03-01

29

Evolution of deformation in the neutron-rich krypton isotopes: The Kr96 nucleus  

NASA Astrophysics Data System (ADS)

The energy of the first excited 2+ state in Kr96 was measured as 241 keV. The nucleus was produced in the fission of U238 induced by a 954-MeV Xe136 beam and prompt ? rays were observed using the clover array CLARA in coincidence with fission products identified with the PRISMA spectrometer. The evolution of the quadrupole collectivity in the Kr isotopes with N?50 is discussed by comparison with that from the Rb to Mo isotones and with predictions of various theoretical calculations.

M?rginean, N.; Bucurescu, D.; Ur, C. A.; Mihai, C.; Corradi, L.; Farnea, E.; Filipescu, D.; Fioretto, E.; Ghi??, D.; Guiot, B.; Grska, M.; Ionescu-Bujor, M.; Iord?chescu, A.; Jelavi?-Malenica, D.; Lenzi, S. M.; Mason, P.; M?rginean, R.; Mengoni, D.; Montagnoli, G.; Napoli, D. R.; Pascu, S.; Pollarolo, G.; Recchia, F.; Stefanini, A. M.; Silvestri, R.; Sava, T.; Scarlassara, F.; Szilner, S.; Zamfir, N. V.

2009-08-01

30

The relationship between interstellar dust and the isotopic anomalies in meteorites  

NASA Technical Reports Server (NTRS)

Work on the ways in which the isotopic anomalies found in meteorites can be regarded as the chemical memory of even larger anomalies found in interstellar dust is outlined. This approach constitutes one theory of the isotopic anomalies, standing in contrast to the idea of a spatial inhomogeneity in the early solar system owing to inhomogeneous admixture from a neighboring supernova. The four mechanisms of isotopic chemical memory in interstellar dust are: (1) thermal condensation within expanding events of nucleosynthesis; (2) different isotopic mappings onto the grain size spectrum; (3) dust components of differing age; and (4) isotope-dependent interstellar chemistry. Specific examples of each mechanism are given to illustrate how each may have contributed to known isotopic anomalies.

Clayton, D. D.

1988-01-01

31

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

NASA Astrophysics Data System (ADS)

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 (?17O - ?18O (?17O ? {(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 isotopic fractionation, that is, a slope = 1.0 linear array in an oxygen three isotope plot ?17O - ?18O. Therefore, the prediction of the self-shielding hypothesis that the solar oxygen isotopic composition must be different from planetary objects is not supported by the CAI oxygen isotopic data, and we think that the general homogeneity of isotopic composition in the early solar nebula is still a valid assumption. References [1] Clayton R.N. et al, Science, 182, 485-88, 1973. [2] Yurimoto H. et al. Applied Surface Science, 793, 203-204, 2003. [3] Clayton R., Nature 415, 317, 2002. [4] Burnett D.S. et al., Space Science Review, 105, 509-543, 2003. [5] McKeegan K. et al. 2009. Abstract #2494. 40th LPSC, 2009. [5] Wieler R. Meteoritics & Planetary Science, 44, A218, 2009. [|#22#|

Ozima, M.; Yamada, A.

2009-12-01

32

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids.  

National Technical Information Service (NTIS)

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/hydroge...

G. W. Cooper M. H. Thiemens S. Chang T. L. Jackson

1997-01-01

33

Geologic Age Distributon of Sulfur Isotope Anomalies: Data from a new UV and IR laser microprobe  

Microsoft Academic Search

The age distribution of mass-independent, sulfur isotope fractionation anomalies reported by Farquhar et al (2000) has attracted much interest. The distribution, as originally published, showed Archean sulfide and sulfate minerals with anomalies ranging from D33S = -1.3 to +2.0 permil (D33S = d33S-0.515*d34S; for mass dependent fractionation (MDF), D33S = 0.0; for mass independent fractionation (MIF), D33S not = 0.0).

D. Rumble; A. Bekker; J. Farquhar; H. D. Holland; G. Hu; S. Maruyama; S. Ono; H. Ohmoto; M. Rosing; Y. Ueno; B. A. Wing

2002-01-01

34

Nitrogen Isotopic Anomalies in a Hydrous Interplanetary Dust Particle  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

35

Endemic Ru Isotopic Anomalies in Iron Meteorites and in Allende  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

36

A local proton irradiation model for isotopic anomalies in the solar system  

NASA Technical Reports Server (NTRS)

An attempt is made to explain the O-16 and Al-26 anomalies observed in solar-system bodies in the framework of a local irradiation model wherein a small amount of solar system matter of normal isotopic composition was irradiated by energetic protons from the primeval sun. Several isotopic constraints are summarized with which the model should be consistent, and a proton energy distribution and fluence and a target elemental composition are chosen such that the extraordinary component produced by irradiation satisfies the constraints. Detailed attention is given to the relevant oxygen reactions, Al-26 production, and effects of proton irradiation on isotopes of Mg, Ca, and Ba. A scenario is outlined which satisfies all the constraints. Consequences of the model are discussed with respect to the isotopic anomalies observed in Allende inclusions.

Lee, T.

1978-01-01

37

Noble gas anomalies and synthesis of the chemical elements  

NASA Astrophysics Data System (ADS)

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

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

1980-06-01

38

Anomalies.  

ERIC Educational Resources Information Center

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,

Online-Offline, 1999

1999-01-01

39

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Astrophysics Data System (ADS)

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.

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

1997-08-01

40

Sulfur and hydrogen isotope anomalies in meteorite sulfonic acids.  

PubMed

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. PMID:9262469

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

1997-08-22

41

Sulfur and Hydrogen Isotope Anomalies in Meteorite Sulfonic Acids  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

42

Carbon dioxide and oxygen isotope anomalies in the mesosphere and stratosphere  

SciTech Connect

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.

Thiemens, M.H.; Jackson, T. [Univ. of California, La Jolla, CA (United States); Zipf, E.C. [Univ. of Pittsburgh, PA (United States)] [and others

1995-11-10

43

Cosmic rays and isotopic anomalies in the early solar system  

Microsoft Academic Search

A mixture of freshly synthesized elements and old debris formed in earlier events located in a region not far from the site of a supernova explosion must have received a total time-integrated cosmic-ray flux such that the isotopic compositions of many of the elements were altered appreciably by the proton- and neutron-induced reactions. Such an 'early' irradiation model of the

P. K. Kuroda

1980-01-01

44

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

PubMed

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 (8230'N), where there is downward transport of stratospheric air to the polar troposphere, and were analyzed for ?(17)O and ?(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, ?MDF(H2O) = 0.529 0.003 [2? standard error (SE)], was determined from 27 CLP samples collected in 2003-2005. An oxygen isotopic anomaly of ?(17)O = 76 16 ppm (2? SE) was found in water vapor samples from Alert relative to CLP. We propose that the positive oxygen isotope anomalies observed at Alert originated from stratospheric ozone, were transferred to water in the stratosphere, and subsequently mixed with tropospheric water at high latitudes as the stratospheric air descended into the troposphere. On the basis of this ground signal, the average ?(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 ?(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 (2? SE) relative to Vienna Standard Mean Ocean Water. PMID:24009339

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

2013-09-24

45

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

NASA Astrophysics Data System (ADS)

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.

Harris, M. J.

1983-01-01

46

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

NASA Technical Reports Server (NTRS)

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 defined by Delta-33 = (delta)S-33 -0.50(delta)S-34 and Delta-36 = (delta)s-36 - 1.97 (delta)S-34. From these relationships Delta-33 = 1.24 % and Delta-36 = 0.89 % are observed. These anomalies, particularly the Delta-33, lie well outside the range of analytical uncertainty. They are the largest observed in any meteoritic component and the first found in an organosulfur compound. As discussed by Thiemens and Jackson, due to it's position on the periodic chart, sulfur undergoes chemically induced mass independent isotopic fractionations as does oxygen. Experiments by Mauersberger et. al. show that in such processes, the magnitude of fractionation for the different isotopically substituted species varies with mass and angular momentum; thus, anomalies are expected for both S-33 and S-36, but not necessarily of the same magnitude. Laboratory experiments have also confirmed that chemically produced, mass independent fractionations are mediated by molecular symmetry factors. A chemical source of fractionation requires that the sulfur isotopic anomaly was established in the gas phase, probably in reactions involving symmetric CS2. The discovery of an anomalous sulfur isotopic composition in a specific molecule containing excess deuterium is an important advance in the understanding of the cosmochemistry of sulfur. This evidence suggests that methanesulfonic acid was synthesized by interstellar processes. Further measurements and details of possible synthesis and fractionation mechanisms will be presented.

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

1996-01-01

47

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

NASA Astrophysics Data System (ADS)

Mineral dust is emitted into the atmosphere from arid regions in Asia yearly, accounting for ~36% of global aerosol emissions, 5900 Tg yr-1 [IPCC 2007]. Increasing anthropogenic emissions and persistent dust emissions not only have reduced the air quality in Asia itself, but are also affecting the pollutant deposition into the Pacific Ocean and air quality in downwind areas. The carbonate component of mineral dust (calcite (CaCO3) and dolomite (CaMg(CO3)2) is particularly reactive and can comprise as much as 30% of the total mineral dust aerosol, depending on the source region [Claquin et al., 1999]. Carbonate can affect atmospheric chemical processes and aerosol characteristics because the acid neutralizing capacity of this species facilitates the heterogeneous conversion of sulphate and nitrate. Understanding heterogeneous reactions occurring on the surface of aerosol particles will lead to a better understanding of the fate and transport of molecules in the troposphere as well as to resolve their role in air quality and pollution. The primary goal of this work is to develop an isotope methodology for carbonates that can be used as a chemical marker for the origin of polluted air plumes and chemical transformation during the long range transport of air masses. We will discuss the carbon and oxygen isotope composition of the CO2 released from the fine (< 1 ?m) and coarse (> 1 ?m) particles collected at two different sites [Mt. Soledad (800 ft) and Scripps Pier, La Jolla, California] and its possible utility as a tracer to identify the long-range transport of aerosol from local pollution events. The degree of urban influence of sampled air parcels at each site was quantified through back-trajectory analysis of NOAA HYSPLIT output data. Interestingly, the isotopes of oxygen did not follow standard mass dependent relationship (?17O ~ 0.52 ?18O) rather have excess 17O (?17O = ?17O- 0.52?18O) ranging from 0.9 to 3.9 per mil. A highly significant correlation (r2= 0.887) was observed between oxygen isotope anomaly (?17O) 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.

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

2008-12-01

48

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

PubMed

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

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

2010-11-23

49

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

PubMed Central

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 (0.43.9). 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.

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

2010-01-01

50

Arctic Eocene isotopic anomaly: unusual temperature\\/rainfall isotope relationship and a stormy world  

Microsoft Academic Search

During an extended time period covering the early to middle Eocene (55-40 Ma), high-biomass deciduous conifer forests existed above 78oN latitude. Geochemical proxies have revealed the basic climate parameters in the Arctic region during this period: 1. soil carbonate delta18O values imply a mean annual temperature = 13.2 +\\/- 2.0 oC; 2. isotopes in pedogenic carbonate and alkenones, as well

L. O. Sternberg; K. Emanuel; M. Huber; H. Jahren; D. C. Noone

2009-01-01

51

Developing hyperpolarized krypton-83 for nuclear magnetic resonance spectroscopy and magnetic resonance imaging  

Microsoft Academic Search

This dissertation discusses the production of highly nonequilibrium nuclear spin polarization, referred to as hyperpolarization or hp, in the nuclear spin I = 9\\/2 noble gas isotope krypton-83 using spin exchange optical pumping (SEOP). This nonequilibrium polarization yields nuclear magnetic resonance (NMR) signals that are enhanced three or more orders of magnitude above those of thermally polarized krypton and enables

Zackary I. Cleveland

2008-01-01

52

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

Microsoft Academic Search

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 (?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.,

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

1998-01-01

53

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

NASA Technical Reports Server (NTRS)

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

Sabu, D. D.

1974-01-01

54

Krypton Ion Thruster Performance  

NASA Technical Reports Server (NTRS)

Preliminary data were obtained from a 30 cm ion thruster operating on krypton propellant over the input power range of 0.4 to 5.5 kW. The data presented are compared and contrasted to the data obtained with xenon propellant over the same input power envelope. Typical krypton thruster efficiency was 70 percent at a specific impulse of approximately 5000 s, with a maximum demonstrated thrust to power ratio of approximately 42 mN/kW at 2090 s specific impulse and 1580 watts input power. Critical thruster performance and component lifetime issues were evaluated. Order of magnitude power throttling was demonstrated using a simplified power-throttling strategy.

Patterson, Michael J.; Williams, George J.

1992-01-01

55

Condensed krypton scintillators  

Microsoft Academic Search

Liquid and solid krypton have been studied as scintillators. Attenuation length for Kr scintillation light was determined to be about 1m, after the Kr was purified by a hot Ca-getter and by a Ti discharge purifier in liquid phase. Two detectors (75 and 51 in size, respectively) were tested as stop-counters in a time-of-flight experiment using 1-2 GeV\\/c particle beams

D. Yu. Akimov; A. I. Bolozdynya; D. L. Churakov; A. V. Koutchenkov; V. F. Kuzichev; V. N. Lebendenko; I. A. Rogovsky; M. Chen; V. Yu. Chepel; V. V. Sushkov

1993-01-01

56

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

SciTech Connect

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.

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

2010-07-20

57

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

58

The Dupal isotope anomaly in the Paleo-Asian sub-oceanic mantle: Nd-Sr-Pb isotope evidence from ophiolites in Northern China  

NASA Astrophysics Data System (ADS)

It has been suggested that the Dupal isotope anomaly in the mantle (Hart, Nature 309, 1984) can be traced in the Paleozoic ophiolites from the Paleo-Asian Ocean (PAO) that were formed during the break up of the Rodinia Supercontinent between 1000 and 300 Ma (Dobrestove et al., Int. Geo. Rev. 37, 1995). New Sr, Nd and high-precision Pb isotope data for mafic rocks from the ophiolites in the East (370Ma) and West (300Ma) Junggar blocks of the Altaids terrane in China, which belongs to the southern branch of the PAO, combined with published data suggest that the PAO crust and related arc magmas indeed have a Dupal-like isotope signature. In general, the samples have high 208Pb/206Pb for given 206Pb/204Pb ratios (i.e., positive ?8/4 values), similar to Indian Ocean MORB. Data also seem to indicate that the basalts and gabbros from West Junggar ophiolites have an enriched-MORB trace element signature whereas those from East Junggar ophiolites have a signature transitional between MORB-like and arc-like compositions. The new samples have higher ?8/4 than those from the early-Paleozoic (570Ma) Paleo-Asian ophiolites from Agardagh Tes-Chem, which belongs to the northern branch of the PAO (Pfnder et al., Contrib. Mineral. Petrol. 143, 2002). Thus, the combined results indicate that the Dupal isotope signature of the Paleo-Asian ophiolites became stronger with time and from north to south. Moreover, the results lend support to the idea that the Dupal isotope anomaly existed prior to the opening of the Indian Ocean and was probably present throughout the whole PAO. Such a long period of existence and large-scale distribution indicate that the Dupal isotope anomaly may not simply be an attribute of certain mantle domain, but a reflection of a mantle process as well.

Liu, X.; Castillo, P. R.; Xu, J.; Hou, Q.

2009-12-01

59

Dupal anomaly in existence 115 Ma ago: Evidence from isotopic study of the Kerguelen Plateau (South Indian Ocean)  

SciTech Connect

The Kerguelen Plateau (South Indian Ocean), whose oldest age has been dated as early Cretaceous, shows geochemical and isotopic features characteristic of OIB-type magmatism. It is probably related to the early stages of activity of the Kerguelen hot spot which is also responsible for the Ninetyeast Ridge. It shows all evidence of being an oceanic plateau with an impressive volume of magmatism. The Nd-Sr isotopic systematics of the Plateau basalts show a large spread of values comparable to the systematics shown by the basalts from the Kerguelen Islands. However, while the archipelago basalts have Pb isotopic variations almost within analytical errors, the Plateau basalts show large Pb isotopic variations which overlap the whole range observed amongst Indian Ocean ridge basalts. Contamination of a deep, enriched OIB-type plume, i.e., the Kerguelen hot spot with characteristic Dupal signature, by a depleted, MORB-type reservoir can account for both the trace-element and isotopic geochemistry of the Kerguelen Plateau basalts. This indicates the existence of the Dupal anomaly already 115 Ma ago. In addition, evidence for its involvement in the genesis of Indian Ocean basalts occurs throughout time, including the present day. This favors the hypothesis of a deep-seated source for this major geochemical anomaly which is then probably responsible for the special features of the Indian Ocean.

Weis, D.; Mennessier, J.P. (Universite Libre de Bruxelles (Belgium)); Bassias, Y. (Laboratoire de Geologie du Museum National d'Histoire Naturelle, Paris (France)); Gautier, I. (Universite Libre de Bruxelles (Belgium) Universite Pierre et Marie Curie, Paris (France))

1989-08-01

60

Calcium Isotopic Anomalies in the Allende CAIs and the Angrite Angra dos Reis  

NASA Astrophysics Data System (ADS)

Both negative 48Ca and 50Ti anomalies of the Angrite Angra dos Reis was identified in this study, and the result supported previous study of correlated negative 54Cr and 50Ti anomalies in achondrites.

Chen, H. W.; Chen, J. C.; Lee, T.; Shen, J. J.

2010-03-01

61

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

62

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

63

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

SciTech Connect

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.

Wirstroem, Eva S.; Cordiner, Martin A.; Charnley, Steven B.; Milam, Stefanie N., E-mail: ewirstrom@gmail.com [Astrochemistry Laboratory and Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Greenbelt, MD 20770 (United States)

2012-09-20

64

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

NASA Astrophysics Data System (ADS)

Organic material found in meteorites and interplanetary dust particles is enriched in D and 15N. 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 [1]. Theoretical models of interstellar fractionation at low temperatures predict large enrichments in both D and 15N 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 15N enrichment does not correlate with one in D, and that some D-enriched primitive material displays little, if any, 15N 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 15N and D in dense cloud cores. We also show that while the nitriles, HCN and HNC, contain the greatest 15N enrichment, this is not expected to correlate with extreme D enrichment. These calculations therefore support the view that Solar System 15N 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] Mumma, M. J. and Charnley, S.B. (2011), ARA&A, 49, 471.

Charnley, Steven B.; Wirstrom, E. S.; Cordiner, M. A.; Milam, S. N.

2012-10-01

65

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

NASA Astrophysics Data System (ADS)

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 (? 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 ? 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.

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

1998-02-01

66

Isotopic composition of xenon and krypton in silicate-graphite inclusions of the El Taco, Campo del Cielo, IAB iron meteorite  

NASA Astrophysics Data System (ADS)

Noble gases, extracted by temperature-stepped pyrolysis from acid-resistant silicate, schreibersite, and graphite residues of inclusions from the IAB iron meteorite El Taco (Campo del Cielo), have been analyzed for their isotopic composition. The concentrations of spallogenic (light) gases agree with previous data on adjacent specimens. Nominal feldspar and pyroxene fractions have lost up to 80% of their 3He during, or towards the end of, the exposure of El Taco to the cosmic radiation. In olivine the 3Ne/21Ne and NePNe ratios are as low as 2.18 0.01 and 1.09 0.03, respectively, presumably because the silicates were irradiated within a FeNi matrix under extremely heavy shielding. Argon, Kr, and Xe in the silicates are dominated by a trapped "planetary" component with 100 ? 36Ar/132Xe ? 700 and 1.7? 84Kr/132Xe ? 2.2 . Xenon released from the silicates at extraction temperatures > 1000C is isotopically close to ureilite Xe, while the high- T Xe from graphite and schreibersite is unlike any of the presently well-established types of Xe. The isotopic composition of this Xe can be generated as a mixture of mass-fractionated U?Xe, with light isotopes depleted by (2.2 0.1) % per atomic mass unit, and 244Pu?Xe. The fission component, 10% in the case of 136Xe, is not due to in situ-production; it must have been added prior to incorporation of the Xe into the El Taco parent body and presumably underwent the mass fractionation process together with U?Xe. From the silicates 127I( n, ?)-produced 128Xe ? and radiogenic 129Xe ? are released together, with the same 128Xe?/129Xe? ratio in nominal olivine, pyroxene, and feldspar although the maximum release from pyroxene occurs about 300C higher than from feldspar. From this the cooling rate of silicates for the temperature range 1500-1200C is deduced to be ?100C per million years. The 80Kr/82Kr ratio of 79,81Br( n, ?)-produced 80,82Kr is 2.86 0.04, in agreement with the value found in inclusions of the IAB Linwood but higher than observed in almost all stone meteorites.

Mathew, K. J.; Begemann, F.

1995-11-01

67

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

NASA Astrophysics Data System (ADS)

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 ?66Zn values range from -0.59 up to +5.61 with most samples being slightly enriched in the heavier isotopes compared with carbonaceous chondrites (0 < ?66Zn < 0.5). The ?66Zn versus ?68Zn 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 ?66Zn 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.

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

2013-12-01

68

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

SciTech Connect

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.

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

2012-07-01

69

A Theoretical Investigation of Isotopic Anomalies of Xenon in Terrestrial and Extra-Terrestrial Samples.  

National Technical Information Service (NTIS)

The abundance and isotopic composition of noble gases in meteorites is discussed in relation to the composition of the early solar system. Carbonaceous chondrites contain a unique Xenon-X, which is rich in heavy and light isotopes. Variations in the occur...

D. D. Sabu

1977-01-01

70

Liquid-krypton scintillation calorimeter  

SciTech Connect

An electromagnetic scintillation calorimeter using liquid krypton or xenon as the working medium has been built. The calorimeter consists of 45 tapered light-collecting cells with dimensions of (2.1 X 2.1) X 40 X (4.15 X 4.15) cm made from aluminum-coated mylar film 50 {mu}m thick. The light from each cell is detected by photomultipliers. The calorimeter filled with liquid krypton was exposed to a beam of secondary particles with a momentum of 400 MeV/c from the ITEP accelerator. The results of the first test are given.

Akimov, D.Yu.; Afonas`ev, V.N.; Bolozdynya, A.I. [Institute of Experimental and Theoretical Physics, Moscow (Russian Federation)

1995-01-01

71

In-Beam Gamma-Ray Spectroscopy of KRYPTON-80 and SELENIUM-70 and Coulomb Excitation Studies of Light Mass Neodymium Isotopes.  

NASA Astrophysics Data System (ADS)

The levels of ('80)Kr have been investigated using in-beam (gamma)-spectroscopy techniques via the ('70)Zn(('12)C,2n)('80)Kr reaction with 38.4 MeV ('12)C ions. The energies, relative intensities and angular distributions of the (gamma)-rays were measured. The proposed level scheme shows four bands; three of even-parity and one of odd-parity. Two-quasi -particle-plus-rotor calculations for ('80)Kr suggest that the even-parity band built on the (8('+)) state at 3701.6 keV has primarily a proton (g(,9/2))('2) configuration and the odd-parity band built on the 5('-) state at 2861.0 keV has an essentially pure two-quasi-proton (f(,5/2),g(,9/2))5(' -) configuration. The observed back-bending in the Yrast band is attributed to the crossing of the ground band and the excited positive-parity band. The level structure of ('70)Se was studied via ('58)Ni(('14)N,pn)('70)Se reaction at a beam energy of 38 MeV. Measurements were made of (gamma)-ray angular distributions and (gamma)-(gamma) coincidence spectra, (gamma)-ray angular distributions and (gamma)-(gamma) directional correlations. Level energies, decay modes, spins and parities, (gamma)-ray radiative admixtures and (gamma)-ray branching ratios were deduced. The levels in the Yrast band through 8('+), a second 0('+), state at 2011.2 keV, and a 3('-) state at 2519.2 keV are some of the new results obtained from the present investigation. The moment-of-inertia plot show a break around 6('+) for the Yrast levels, which is attributed to band crossing. IBA calculations were performed, and the results show good agreement with the experimental values. Coulomb excitation studies of even-even Nd isotopes have been done by using ((alpha),(alpha)') experiments. Semi -classical codes were used to determine the E2 and/ or E4 moments (in case of ('150)Nd).

Ahmed, Abuzeid Younis

72

NOx cycle and the tropospheric ozone isotope anomaly: an experimental investigation  

NASA Astrophysics Data System (ADS)

The oxygen isotope composition of nitrogen oxides (NOx) in the atmosphere is a useful tool for understanding the oxidation of NOx into nitric acid / nitrate in the atmosphere. A set of experiments was conducted to examine change in isotopic composition of NOx due to NOx-O2-O3 photochemical cycling. At low NOx / O2 mixing ratios, NOx became progressively and nearly equally enriched in 17O and 18O over time until it reached a steady state with ?17O values of 39.3 1.9 and ?18O values of 84.2 4, relative to the isotopic composition of the initial O2 gas. As the mixing ratios were increased, the isotopic enrichments were suppressed by isotopic exchange between O atoms, O2, and NOx. A kinetic model was developed to simulate the observed data and it showed that the isotope effects occurring during O3 formation play a dominant role in controlling NOx isotopes and, in addition, secondary kinetic isotope effects or isotope exchange reactions are also important during NOx cycling. The data and model were consistent with previous studies which showed that the NO + O3 reactions occur mainly via the transfer of the terminal atoms of O3. The model predicts that under tropospheric concentrations of NOx and O3, the timescale of NOx-O3 isotopic equilibrium ranges from hours (for ppbv NOx / O2 mixing ratios) to days (for pptv mixing ratios) and yields steady state ?17O and ?18O values of 45 and 117 respectively (relative to Vienna Standard Mean Ocean Water (VSMOW)) in both cases. Under atmospheric conditions when O3 has high concentrations, the equilibrium between NOx and O3 should occur rapidly (h) but this equilibrium cannot be reached during polar winters and/or nights if the NOx conversion to HNO3 is faster. The experimentally derived rate coefficients can be used to model the major NOx-O3 isotopologue reactions at various pressures and in isotope modeling of tropospheric nitrate.

Michalski, G.; Bhattacharya, S. K.; Girsch, G.

2014-05-01

73

Experimental Investigation of Continuous-Wave Laser Ionization of Krypton  

SciTech Connect

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

Cannon, Bret D.; Shannon, Robert F.

2001-10-30

74

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

NASA Astrophysics Data System (ADS)

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 VOCs, 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 (?17O = ?17O - 0.524 ?18O) 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.

Thiemens, M. H.; Shaheen, R.

2010-12-01

75

Communication: On the isotope anomaly of nuclear quadrupole coupling in molecules  

NASA Astrophysics Data System (ADS)

The dependence of the nuclear quadrupole coupling constants (NQCC) on the interaction between electrons and a nucleus of finite size is theoretically analyzed. A deviation of the ratio of the NQCCs obtained from two different isotopomers of a molecule from the ratio of the corresponding bare nuclear electric quadrupole moments, known as quadrupole anomaly, is interpreted in terms of the logarithmic derivatives of the electric field gradient at the nuclear site with respect to the nuclear charge radius. Quantum chemical calculations based on a Dirac-exact relativistic methodology suggest that the effect of the changing size of the Au nucleus in different isotopomers can be observed for Au-containing molecules, for which the predicted quadrupole anomaly reaches values of the order of 0.1%. This is experimentally detectable and provides an insight into the charge distribution of non-spherical nuclei.

Filatov, Michael; Zou, Wenli; Cremer, Dieter

2012-10-01

76

Carbon isotope anomaly in the major plant C1 pool and its global biogeochemical implications  

NASA Astrophysics Data System (ADS)

We report that the most abundant C1 units of terrestrial plants, the methoxyl groups of pectin and lignin, have a unique carbon isotope signature exceptionally depleted in 13C. Plant-derived C1 volatile organic compounds (VOCs) are also anomalously depleted in 13C compared with Cn+1 VOCs. The results confirm that the plant methoxyl pool is the predominant source of biospheric C1 compounds of plant origin such as methanol, chloromethane and bromomethane. Furthermore this pool, comprising ca 2.5% of carbon in plant biomass, could be an important substrate for methanogenesis and thus be envisaged as a possible source of isotopically light methane entering the atmosphere. Our findings have significant implications for the use of carbon isotope ratios in elucidation of global carbon cycling. Moreover methoxyl groups could act as markers for biological activity in organic matter of terrestrial and extraterrestrial origin.

Keppler, F.; Kalin, R. M.; Harper, D. B.; McRoberts, W. C.; Hamilton, J. T. G.

77

Carbon isotope anomaly in the major plant C1 pool and its global biogeochemical implications  

NASA Astrophysics Data System (ADS)

We report that the most abundant C1 units of terrestrial plants, the methoxyl groups of pectin and lignin, have a unique carbon isotope signature exceptionally depleted in 13C. Plant-derived C1 volatile organic compounds (VOCs) are also anomalously depleted in 13C compared with Cn+1 VOCs. The results confirm that the plant methoxyl pool is the predominant source of biospheric C1 compounds of plant origin such as methanol, chloromethane and bromomethane. Furthermore this pool, comprising ca. 2.5% of carbon in plant biomass, represents an important substrate for methanogenesis and could be a significant source of isotopically light methane entering the atmosphere. Our findings have significant implications for the use of carbon isotope ratios in elucidation of global carbon cycling. Moreover methoxyl groups could act as markers for biological activity in organic matter of terrestrial and extraterrestrial origin.

Keppler, F.; Kalin, R. M.; Harper, D. B.; McRoberts, W. C.; Hamilton, J. T. G.

2004-08-01

78

The Magnetic Moment of K40 and the Hyperfine Structure Anomaly of the Potassium Isotopes  

Microsoft Academic Search

The nuclear magnetic moment and atomic hyperfine splitting of the rare K40 isotope have been measured by the atomic beam magnetic resonance technique. Detection of K40 atoms, from a source of normal potassium, was achieved by employing a conventional surface ionization detector as the ion source for a mass spectrometer, and by utilizing an electron multiplier to count the K40

J. T. Eisinger; B. Bederson; B. T. Feld

1952-01-01

79

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

NASA Astrophysics Data System (ADS)

Post-Paleozoic carbon isotope variations constructed from time-series analyses of calcareous microfossils generally pale in comparison with the extreme variations recorded in Paleozoic and Proterozoic aged successions. The latter are primarily preserved in fine-grained inorganic carbonates, which due to their great antiquity and potential for diagenetic alteration have been viewed by some as imperfect recorders of seawater chemistry. In part, this bias stems from the study of Modern carbonate platforms, where significant carbon isotope variations result from vital effects, bioturbation, and sea grass aeration of sediments. In addition, the open framework of biotic reefs allows for the infiltration of diagenetic fluids through lithified platforms. None of these biological issues, however, applies to Proterozoic carbonate accumulations, which are generally fine-grained and pervasively cemented. While geochemical tests of diagenetic alteration have been used for Proterozoic samples (e.g., ?18O, ??13C, and Mn/Sr), they have been variably applied and appear as moving targets from basin to basin, if reported at all. Greatest confidence in the validity of carbon isotope trends come from stratigraphic measurements that reveal smooth ?13C variations, and the comparative analysis of multiple, broadly equivalent basins. For both the Neoproterozoic and the Paleoproterozoic these show profound changes in carbon isotope distribution with time, especially related to widespread paleoclimatic and biotic events. High resolution stratigraphic and geochemical studies of carbonate and co-existing organic matter in post-glacial Neoproterozoic cap carbonates from Namibia and Brazil, and of Ediacaran aged successions in the western USA, South China, and elsewhere provide new insight into extremes of the ancient carbon cycle. On the one hand, the standard model of proportional fluxes is consistent with detailed observations of the cap carbonates. However, there is also strong evidence for carbon limitation to photoautotrophs in the immediate glacial aftermath, and of an unusually strong surface-to-deep ?13C gradient. On the other hand, the standard model is difficult to reconcile with the > -10 carbon isotope excursions in the Ediacaran Period. These require an additional source of 13C depleted alkalinity, which based on the invariance of the organic carbon isotope record support the idea that Proterozoic seawater was buffered by a proportionally larger DOC pool until very near the end of the eon.

Kaufman, A. J.

2008-12-01

80

Extreme hydrogen, oxygen and carbon isotope anomalies in the pore waters and carbonates of the sediments and basalts from the Norwegian Sea: Methane and hydrogen from the mantle  

SciTech Connect

D/H ratios in the pore waters of the sediments from the Norwegian Sea decrease as a function of depth to values as low as {minus}14{per thousand}. Oxygen isotope ratios in the pore waters and carbon and oxygen isotope ratios in carbonates both in the sediments and basalts are low. Extensive alteration of basalt has been given as the explanation for the low oxygen isotope ratios. Material balance calculations suggest that alteration of volcanic material and oxidation of organic matter cannot explain the hydrogen and carbon isotope anomalies. Arguments are presented suggesting that methane and hydrogen from the mantle are oxidized to carbon dioxide and water by sulfate and ferric iron in the basaltic crust to yield the low hydrogen and carbon isotope ratios.

Lawrence, J.R. (Univ. of Houston, University Park, TX (USA)); Taviani, M. (Instituto di Geologia Marina, del C.N.R., Bologna (Italy))

1988-08-01

81

Source of Nitrogen Isotope Anomaly in HCN in the Atmosphere of Titan  

Microsoft Academic Search

The 14N\\/15N ratio for N2 in the atmosphere of Titan was recently measured to be a factor of 2 higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N2, computed quantum-mechanically, and show that the difference in the ratio of 14N\\/15N between N2 and HCN

Mao-Chang Liang; Alan N. Heays; Brenton R. Lewis; Stephen T. Gibson; Yuk L. Yung

2007-01-01

82

Source of Nitrogen Isotope Anomaly in HCN in the Atmosphere of Titan  

Microsoft Academic Search

The14N\\/15N ratio for N2 in the atmosphere of Titan was recently measured to be a factor of two higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N2, computed quantum-mechanically, and show that the difference in the ratio of 14N\\/15N between N2 and HCN can

Mao-Chang Liang; Alan N. Heays; Brenton R. Lewis; Stephen T. Gibson; Yuk L. Yung

2007-01-01

83

Stratigraphic investigations of carbon isotope anomalies and Neoproterozoic ice ages in Death Valley, California  

Microsoft Academic Search

An unusual richness of biogeochemical events is recorded in Neoproterozoic- Cambrian strata of the Death Valley re- gion, California, United States. Eight neg- ative carbon isotope (d13C) excursions are found in carbonate units between 1.08 Ga and the Precambrian\\/Cambrian boundary; four of these excursions occur in carbonates that contain textural features similar to those found globally in postglacial ''cap carbonates''

Frank A. Corsetti; Alan J. Kaufman

2003-01-01

84

A striking nitrogen isotope anomaly in the Bencubbin and Weatherford meteorites  

NASA Technical Reports Server (NTRS)

The stony-iron meteorites Bencubbin and Weatherford contain nitrogen with a ratio of nitrogen-15 to nitrogen-14 larger than normal by as much as a factor of 2. The excess nitrogen-15 may be due either to a nucleosynthetic origin or to extreme isotopic fractionation. In the former case, it may reflect failure to homogenize nitrogen-15 produced in nova explosions. In the latter case, it may reflect chemical processing at temperatures below 40 K in a presolar molecular cloud.

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

1985-01-01

85

Tales of volcanoes and El-Ni?o southern oscillations with the oxygen isotope anomaly of sulfate aerosol  

PubMed Central

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 Earths 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 (19802002) 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-Nio 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.

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

2013-01-01

86

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

PubMed

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-Nio 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

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

2013-10-29

87

Design documentation: Krypton encapsulation preconceptual design  

SciTech Connect

US EPA regulations limit the release of Krypton-85 to the environment from commercial facilities after January 1, 1983. In order to comply with these regulations, Krypton-85, which would be released during reprocessing of commercial nuclear fuel, must be collected and stored. Technology currently exists for separation of krypton from other inert gases, and for its storage as a compressed gas in steel cylinders. The requirements, which would be imposed for 100-year storage of Krypton-85, have led to development of processes for encapsulation of krypton within a stable solid matrix. The objective of this effort was to provide preconceptual engineering designs, technical evaluations, and life cycle costing data for comparison of two alternate candidate processes for encapsulation of Krypton-85. This report has been prepared by The Ralph M. Parsons Company for the US Department of Energy.

Knecht, D.A. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

1994-10-01

88

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

NASA Astrophysics Data System (ADS)

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

Moynier, F.; Fujii, T.; Albarde, F.

2009-12-01

89

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)

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 winter or reversed greenhouse conditions resulting from a draw-down of carbon dioxide after accelerated weathering and massive burial of organic carbon-rich sediments in the oceans.

Erba, E.

2005-12-01

90

Physicochemical formation conditions of banded iron formations and high-grade iron ores in the region of the Kursk Magnetic Anomaly: Evidence from isotopic data  

Microsoft Academic Search

The oxygen and carbon isotopic compositions of minerals from banded iron formations (BIFs) and high-grade ore in the region\\u000a of the Kursk Magnetic Anomaly (KMA) were determined in order to estimate the temperature of regional metamorphism and the\\u000a nature of rock-and ore-forming solutions. Magnetite and hematite of primary sedimentary or diagenetic origin have ?18O within the range from +2 to

V. I. Belykh; E. I. Dunai; I. P. Lugovaya

2007-01-01

91

Atmospheric Krypton and Xenon Measurements from Mars Science Laboratory  

NASA Astrophysics Data System (ADS)

The heavy noble gases krypton and xenon are important tracers of planetary processes from accretion to differentiation and to atmospheric escape. Their abundance and stable isotopic ratios are also indicative of sources as well. The Sample Analysis at Mars (SAM) investigation on the Curiosity rover has measured the Martian atmosphere and reported on the volume mixing ratio of its major constituents (Mahaffy et al., 2013). Here we report the abundance and isotopic ratios of Kr and Xe in the atmosphere of Mars as obtained by semi-static operation of the SAM quadrupole mass spectrometer. Viking provided the first in situ detection of these gases (Owen et al, 1977), suggesting upper limits of 300 ppb for Kr and 80 ppb for Xe, based upon calibration gases with terrestrial isotopic abundances. The abundances of individual isotopes as well as their ratios to one another have been derived from martian meteorite samples by many investigators (e.g., Becker & Pepin, 1984; Bogard & Garrison, 1998). The SAM heavy noble gas data complement the argon isotopic data reported in Mahaffy et al., 2013. Becker, R. H., & Pepin, R. O. (1984). The case for a Martian origin of the shergottites: Nitrogen and noble gases in EETA 79001. Earth and Planetary Science Letters, 69(2), 225-242. Bogard, D. D., & Garrison, D. H. (1998). Relative abundances of argon, krypton, and xenon in the Martian atmosphere as measured in Martian meteorites. Geochimica et cosmochimica acta, 62(10), 1829-1835. Mahaffy, et al., (2013) Abundance and isotopic composition of gases in the martian atmosphere from the Curiosity rover. Science 341, 263-266 Owen, T. et al.,(1977). The composition of the atmosphere at the surface of Mars. Journal of Geophysical research, 82(28), 4635-4639.

Conrad, P. G.; Malespin, C. A.; Franz, H.; Manning, H. L.; Trainer, M. G.; Wong, M. H.; Brunner, A.; Atreya, S. K.; Pepin, R. O.; Jones, J. H.; Owen, T. C.; Mahaffy, P. R.

2013-12-01

92

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

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.

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

1994-09-01

93

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

Microsoft Academic Search

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

Sabu

1977-01-01

94

Mineralogical characterization of a unique material having heavy oxygen isotope anomaly in matrix of the primitive carbonaceous chondrite Acfer 094  

Microsoft Academic Search

We report the mineral compositions and micro-texture of the isotopically anomalous (?17,18OSMOW?+180) FeSNiO material recently discovered in matrix of the primitive carbonaceous chondrite Acfer 094 [Sakamoto N., Seto Y., Itoh S., Kuramoto K., Fujino K., Nagashima K., Krot A. N. and Yurimoto H. (2007) Oxygen isotope evidence for remnants of the early solar system primordial water. Science317, 231233]. Synchrotron radiation

Yusuke Seto; Naoya Sakamoto; Kiyoshi Fujino; Takashi Kaito; Tetsuo Oikawa; Hisayoshi Yurimoto

2008-01-01

95

SST Anomalies + Wind Anomalies  

NSDL National Science Digital Library

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

Shirah, Greg; Allen, Jesse; Adamec, David

2003-02-03

96

Theoretical Investigation of Isotopic Anomaly of Xenon in Carbonaceous Chondrites and Other Terrestrial and Extra-Terrestrial Samples.  

National Technical Information Service (NTIS)

The composition of Xe released from carbonaceous chondrites between 600 and 1000 C, particularly its isotopic trapped forms, is analyzed. Data show trapped Xe to have the following forms: Xe-124, 126, 130, 131, 132, 134, and 136. Attempts were also made t...

D. D. Sabu

1974-01-01

97

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

98

Limits to the sensitivity of living benthic foraminifera to pore water carbon isotope anomalies in methane vent environments  

NASA Astrophysics Data System (ADS)

13C depletions in the carbon isotopic composition of benthic foraminiferal tests preserved in the stratigraphic record have been interpreted as an active incorporation of methane-derived carbon. Understanding the extent to which these isotope excursions reflect basin-wide fluxes of methane carbon to bottom waters versus a local supply of methane carbon within the sediments in which benthic foraminifera live, or a postmortem diagenetic imprint is critical to the interpretation of ?13C paleoceanographic proxies. Here we evaluate the impact of chemical gradients measured in pore waters adjacent to active methane vents on carbon assimilation by living benthic foraminifera and show that those living near methane vents do not assimilate the distinctly 13C depleted methane-derived dissolved inorganic carbon into their tests from the pore water in which they were found. Our observations can be explained by the recently articulated physiological limits imposed on deep-sea fauna by low-oxygen and high-pCO2 environments. Understanding the importance of the different processes involved in the observed disequilibrium between the carbon isotopic composition of the benthic forams and the pore waters where they were found has important implications on the reliability of carbon isotopic composition of benthic foraminifera for paleoceanographic reconstructions. In particular, the observation on the inhospitability of these environments for benthic foraminifera at least for reproduction and growth raises the issue on the overprint either in the late adult stages of foraminifera that grew in a different neighboring environment or during early diagenesis in these geochemically active environments.

Herguera, J. C.; Paull, C. K.; Perez, E.; Ussler, W.; Peltzer, E.

2014-03-01

99

Mineralogical characterization of a unique material having heavy oxygen isotope anomaly in matrix of the primitive carbonaceous chondrite Acfer 094  

NASA Astrophysics Data System (ADS)

We report the mineral compositions and micro-texture of the isotopically anomalous (? 17,18O SMOW +180) Fe-S-Ni-O material recently discovered in matrix of the primitive carbonaceous chondrite Acfer 094 [Sakamoto N., Seto Y., Itoh S., Kuramoto K., Fujino K., Nagashima K., Krot A. N. and Yurimoto H. (2007) Oxygen isotope evidence for remnants of the early solar system primordial water. Science317, 231-233]. Synchrotron radiation X-ray diffraction and transmission electron microscopy studies indicate that this material consists of the symplectitically intergrown magnetite (Fe 3O 4) and pentlandite (Fe 5.7Ni 3.3S 8) with magnetite/pentlandite volume ratio of 2.3. Magnetite forms column-shaped grains (10-30 nm in diameter and 100-200 nm in length); pentlandite occurs as worm-shaped grains or aggregates of grains 100-300 nm in size between magnetite crystals. Although both the X-ray diffraction and electron energy loss spectra support identification of iron oxide as magnetite, the electron diffraction patterns show that magnetite has a weak 3-fold superstructure, possibly due to ordering of vacancies. We infer that the isotopically anomalous symplectite formed by sulfurization and oxidization of metal grains either in the solar nebula or on an icy planetesimal. The intersite cation distribution of pentlandite suggests that timescale of oxidation was no longer than 1000 years.

Seto, Yusuke; Sakamoto, Naoya; Fujino, Kiyoshi; Kaito, Takashi; Oikawa, Tetsuo; Yurimoto, Hisayoshi

2008-06-01

100

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

NASA Astrophysics Data System (ADS)

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

Strashnov, I.; Gilmour, J. D.

2014-06-01

101

Anomalous Oxygen and Krypton Abundances in Interstellar Gas  

NASA Technical Reports Server (NTRS)

The primary objective of this program was to obtain FUSE observations of the interstellar H2 absorption toward a sample of stars observed with the HST STIS spectrograph as part of the ISM SNAP Survey. This Survey was designed to produce a database of high quality, high resolution W spectra from which interstellar gas-phase elemental abundances could be derived for large portions of the Galaxy. In particular, oxygen and krypton were chosen as excellent tracers for measuring the homogeneity of the interstellar gas due to their weak depletion into dust grains. The gas-phase 0 and Kr abundances relative to total hydrogen column density had previously been shown with HST GHRS measurements to be essentially constant in the local Milky Way. One of the main motivations of the ISM SNAP Survey was to determine if this constancy held at greater distances and in denser sightlines (where depletion into dust could be a possibility). The initial ISM SNAP STIS observations indicated a number of sightlines with unusual 0 and Kr abundances relative to the measured H I column densities. Since the appropriate benchmark for accurate abundance comparisons is the total hydrogen column density (H I plus H2), FUSE observations of interstellar H2 were carried out in these sightlines in order to determine if they represent cases of true abundance anomalies.

Meyer, David M.

2004-01-01

102

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

NASA Astrophysics Data System (ADS)

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

Lee, Chang

2013-04-01

103

Physicochemical formation conditions of banded iron formations and high-grade iron ores in the region of the Kursk Magnetic Anomaly: Evidence from isotopic data  

NASA Astrophysics Data System (ADS)

The oxygen and carbon isotopic compositions of minerals from banded iron formations (BIFs) and high-grade ore in the region of the Kursk Magnetic Anomaly (KMA) were determined in order to estimate the temperature of regional metamorphism and the nature of rock-and ore-forming solutions. Magnetite and hematite of primary sedimentary or diagenetic origin have ?18O within the range from +2 to 6. During metamorphism, primary iron oxides, silicates, and carbonates were involved in thermal dissociation and other reactions to form magnetite with ?18O = +6 to +11. As follows from a low ?18Oav = -3.5 of mushketovite (magnetite pseudomorphs after hematite) in high-grade ore, this mineral was formed as a product of hematite reduction by organic matter. The comparison of ?18O of iron oxides, siderite, and quartz from BIFs formed at different stages of the evolution of the Kursk protogeosyncline revealed specific sedimentation (diagenesis) conditions and metamorphism of the BIFs belonging to the Kursk and Oskol groups. BIF of the Oskol Group is distinguished by a high ?18O of magnetite compared to other Proterozoic BIFs. Martite ore differs from host BIF by a low ?18O = -0.2 to -5.9. This implies that oxygen from infiltration water was incorporated into the magnetite lattice during the martite formation. Surface water penetrated to a significant depth through tectonic faults and fractures.

Belykh, V. I.; Dunai, E. I.; Lugovaya, I. P.

2007-04-01

104

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

SciTech Connect

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.

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

2012-02-20

105

Hyperpolarized Krypton-83 as a MRI Contrast Agent  

NASA Astrophysics Data System (ADS)

Hyperpolarized krypton-83 (I = 9/2) yields NMR signal enhancements [1] of 1200 to 4500 times that of thermal equilibrium value depending on the composition of the optical pumping gas mixture. The quadrupolar relaxation of krypton-83 provides surface sensitive contrast in MRI [2] and yields information about surface hydrophobicity [3], surface-to-volume ratio, surface temperature, and surface hydration. These characteristics make hp krypton-83 MRI a promising technique for materials science applications and medical diagnosis. Experimental hp krypton-83 results in model systems with biomedically relevant coatings (e.g. lung surfactant and cigarette tar) are presented. Additionally, preliminary results from hp krypton-83 in excised rodent lungs are discussed. (1) ZI Cleveland, et al., Chem. Phys., 2006. 124(4) 044311. (2) GE Pavlovskaya, et al., Proc. Natl. Acad. Sci. U.S.A.,2005. 102: 18275-18279. (3) KF Stupic, et al., Solid State Nucl. Magn. Reson., 2006. 29: 79-84.

Cleveland, Zackary; Pavlovskaya, Galina; Stupic, Karl; Repine, John; Meersmann, Thomas

2007-03-01

106

?-decay study of neutron-rich bromine and krypton isotopes  

NASA Astrophysics Data System (ADS)

Short-lived neutron-rich nuclei including 93Br, 93Kr, and 94Kr were produced in proton-induced fission of 238U at the Holifield Radioactive Ion Beam Facility in Oak Ridge. Their ? decay was studied by means of a high-resolution online mass separator and ?-? spectroscopy methods. The half-life of T1/2 = 152(8) ms and ?-delayed branching ratio of Pn = 53-8+11% measured for 93Br differs from the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half-life of 94Kr T1/2 = 227(14) ms and both the half-life of T1/2 = 1.298(54) s and ?-delayed branching ratio of Pn = 1.9-0.2+0.6% of 93Kr are in very good agreement with literature values. The decay properties of 93Br include previously unreported ? transitions following ?-delayed neutron emission.

Miernik, K.; Rykaczewski, K. P.; Grzywacz, R.; Gross, C. J.; Stracener, D. W.; Batchelder, J. C.; Brewer, N. T.; Cartegni, L.; Fija?kowska, A.; Hamilton, J. H.; Hwang, J. K.; Ilyushkin, S. V.; Jost, C.; Karny, M.; Korgul, A.; Krlas, W.; Liu, S. H.; Madurga, M.; Mazzocchi, C.; Mendez, A. J., II; Miller, D.; Padgett, S. W.; Paulauskas, S. V.; Ramayya, A. V.; Surman, R.; Winger, J. A.; Woli?ska-Cichocka, M.; Zganjar, E. F.

2013-07-01

107

RISK: A Resonance Ionization Mass Spectrometer for Krypton  

NASA Astrophysics Data System (ADS)

A resonance ionization mass spectrometer for krypton (RISK) has been developed. Atoms are released by a step-heating and ionized by pulsed tunable lasers. The sensitivity below 1000 atoms is demonstrated by detecting 81Kr in noncumulate eucrite Stannern.

Strashnov, I.; Blagburn, D. J.; Gilmour, J. D.

2010-03-01

108

Numerical investigation of the Krypton Large IMpulse Thruster  

NASA Astrophysics Data System (ADS)

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

Kurzyna, Jacek

2014-05-01

109

Spectra of heliumlike krypton from tokamak fusion test reactor plasmas  

SciTech Connect

Krypton has been injected into ohmically-heated TFTR plasmas with peak electron temperatures of 6 key to study the effects of krypton on the plasma performance and to investigate the emitted krypton line radiation, which is of interest for future-generation tokamaks such as ITER, both as a diagnostic of the central ion temperature and for the control of energy release from the plasma by radiative cooling. The emitted radiation was monitored with a bolometer array, an X-ray pulse height analysis system, and a high-resolution Johann-type crystal spectrometer; and it was found to depend very sensitively on the electron temperature profile. Satellite spectra of heliumlike krypton, KrXXXV, near 0.95 [Angstrom] including lithiumlike, berylliumlike and boronlike features were recorded in second order Bragg reflection. Radiative cooling and reduced particle recycling at the plasma edge region were observed as a result of the krypton injection for all investigated discharges. The observations are in reasonable agreement with modeling calculations of the krypton ion charge state distribution including radial transport.

Bitter, M.; Hsuan, H.; Bush, C.; Cohen, S.; Cummings, C.J.; Grek, B.; Hill, K.W.; Schivell, J.; Zarnstorff, M. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Beiersdorfer, P.; Osterheld, A. (Lawrence Livermore National Lab., CA (United States)); Smith, A. (Lock Haven Univ., Lock Haven, PA (United States)); Fraenkel, B. (Hebrew Univ., Jerusalem (Israel))

1993-04-01

110

Spectra of heliumlike krypton from tokamak fusion test reactor plasmas  

SciTech Connect

Krypton has been injected into ohmically-heated TFTR plasmas with peak electron temperatures of 6 key to study the effects of krypton on the plasma performance and to investigate the emitted krypton line radiation, which is of interest for future-generation tokamaks such as ITER, both as a diagnostic of the central ion temperature and for the control of energy release from the plasma by radiative cooling. The emitted radiation was monitored with a bolometer array, an X-ray pulse height analysis system, and a high-resolution Johann-type crystal spectrometer; and it was found to depend very sensitively on the electron temperature profile. Satellite spectra of heliumlike krypton, KrXXXV, near 0.95 {Angstrom} including lithiumlike, berylliumlike and boronlike features were recorded in second order Bragg reflection. Radiative cooling and reduced particle recycling at the plasma edge region were observed as a result of the krypton injection for all investigated discharges. The observations are in reasonable agreement with modeling calculations of the krypton ion charge state distribution including radial transport.

Bitter, M.; Hsuan, H.; Bush, C.; Cohen, S.; Cummings, C.J.; Grek, B.; Hill, K.W.; Schivell, J.; Zarnstorff, M. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Beiersdorfer, P.; Osterheld, A. [Lawrence Livermore National Lab., CA (United States); Smith, A. [Lock Haven Univ., Lock Haven, PA (United States); Fraenkel, B. [Hebrew Univ., Jerusalem (Israel)

1993-04-01

111

Sulfur mass-independent fractionation during photolysis and photoexcitation of SO2 and CS2 and implications to the source reactions for Archean sulfur isotope anomaly  

NASA Astrophysics Data System (ADS)

Signatures of sulfur mass-independent fractionations (S-MIF) in Archean sedimentary rocks provide critical constraints on the atmospheric oxygen level of an early atmosphere and documents fundamental difference in early sulfur biogeochemical cycle from that of today. Archcean sulfide and sulfate minerals often yield correlated relationships among ?34S, ?33S and ?36S values. Our goal is to use this S-MIF pattern to pinpoint the S-MIF source reaction(s), and to constrain early atmospheric conditions beyond the oxygen level. Such an effort may lead to a new hypothesis about the cause of the Great Oxidation Event at 2.4 Billion years ago. We will present new results of laboratory photochemical experiments that are designed to calibrate the pattern of S-MIF during the photochemistry of SO2 and CS2 as a function of UV spectrum regions, partial pressure of SO2 and CS2 (0.1 mbar and above) and total N2 pressure (0.25 to 1.0 bar). Both SO2 and CS2 exhibit high energy absorption band (190 to 220 nm) that leads to direct photolysis (SO2 ? SO + O or CS2 ? CS + S), and low energy band (>240 nm for SO2 and 280 nm for CS2) that excites molecules to low lying electronic states under dissociation thresholds. Broadband UV light sources (Xenon or Deuterium arc lamps) are used in combination with a series of bandpass (20035 nm), longpass (250 or 280 nm) filters to isolate specific electronic transitions. Excited state SO2 is trapped by acetylene and excited state CS2 polymerizes in the reactor, and are collected for sulfur isotope ratio analysis. Although SO2 photolysis under 190 to 220 nm is thought to be the main Archean S-MIF source reaction, its S-MIF is characterized by high ?34S values (up to 140 ) and relatively low ?36S/?33S values (-3.3 to -5.9) compared to Archean data (-0.9 to -1.5). Strong pSO2 dependence suggests S-MIF is primarily due to isotopologue self-shielding at least under our experimental conditions. In contrast, SO2 photoexciation under >250 nm produces large positive anomaly in both ?33S and ?36S (up to 100 ) even in optically thin conditions, suggesting quantum dynamic origin of the S-MIF. Brown polymer material produced under photolysis and photoexciation of CS2 also yield S-MIF but isotope patterns are different from those of SO2 photochemistry and different from Archean pattern. If SO2 photolysis and photoexcitation are the main source of Archean S-MIF, the different ?36S/?33S values can be linked to the different magnitude of contributions from SO2 photolysis and photoexciation. For example, increased contribution of photoexciation band is expected under a thick organic haze layer that attenuates high energy UV and chemically traps excited state SO2.

Ono, S.; Whitehill, A. R.; Oduro, H. D.

2012-12-01

112

Bangui Anomaly  

NASA Technical Reports Server (NTRS)

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.

Taylor, Patrick T.

2004-01-01

113

Partitioning of krypton-85 in liquid scintillation cocktail  

SciTech Connect

Krypton is one of the noble gases. As such, it forms compounds only with exceptionally strong oxidizing agents. The concentration of krypton in air is 1.139 parts per million by volume. In general, its behavior is best described as that of an ideal gas. Krypton-85 is the longest lived of the common radioactive noble gases with a half life of 10.72 years. Gamma radiation at 513.990 keV has an intensity of only 0.434%. Most decay is {beta}{sup -} emission with a maximum energy of 687.0 keV and an average energy of 251.4 keV. The analytical chemistry of krypton-85 is driven by these factors. High concentrations may be gamma counted directly. Low levels are typically determined by more sensitive techniques such as liquid scintillation counting (LSC) where detection limits on the order of 1 picocurie (pCi) are routinely achieved. For a 5 standard cubic centimeter (scc) sample, this represents a concentration of 0.2 pCi/scc, well below the DOE Air Immersion Derived Concentration Guideline (G) of 3 pCi/scc. As a gas, krypton in a sealed LSC vial distributes itself between the liquid phase and the gas phase. Some past work has used gamma counting at levels many orders of magnitude greater than those now achievable by LSC to study the distribution of krypton. This effect is of interest in the analytical chemistry of krypton-85 because geometrical considerations influence how much of the material in the gas phase decays generating particles which then impact the liquid phase where they may be counted.

Hohorst, F.A.; Sherlock, M.A.

1994-12-01

114

Krypton and xenon in lunar fines  

NASA Technical Reports Server (NTRS)

Data from grain-size separates, stepwise-heated fractions, and bulk analyses of 20 samples of fines and breccias from five lunar sites are used to define three-isotope and ordinate intercept correlations in an attempt to resolve the lunar heavy rare gas system in a statistically valid approach. Tables of concentrations and isotope compositions are given.

Basford, J. R.; Dragon, J. C.; Pepin, R. O.; Coscio, M. R., Jr.; Murthy, V. R.

1973-01-01

115

Krypton assay in xenon at the ppq level using a gas chromatographic system and mass spectrometer  

NASA Astrophysics Data System (ADS)

We have developed a new method to measure krypton traces in xenon at unprecedented low concentrations. This is a mandatory task for many near-future low-background particle physics detectors. Our system separates krypton from xenon using cryogenic gas chromatography. The amount of krypton is then quantified using a mass spectrometer. We demonstrate that the system has achieved a detection limit of 8 ppq (parts per quadrillion) and present results of distilled xenon with krypton concentrations below 1 ppt.

Lindemann, Sebastian; Simgen, Hardy

2014-02-01

116

An atom trap trace analysis (ATTA) system for measuring ultra-low contamination by krypton in xenon dark matter detectors  

NASA Astrophysics Data System (ADS)

The XENON dark matter experiment aims to detect hypothetical weakly interacting massive particles (WIMPs) scattering off nuclei within its liquid xenon (LXe) target. The trace 85Kr in the xenon target undergoes beta-decay with a 687 keV end point and 10.8 year halflife, which contributes background events and limits the sensitivity of the experiment. In order to achieve the desired sensitivity, the contamination by krypton is reduced to the part per trillion (ppt) level by cryogenic distillation. The conventional methods are not well suited for measuring the krypton contamination at such a low level. In this work, we have developed an atom trap trace analysis (ATTA) device to detect the ultra-low krypton concentration in the xenon target. This project was proposed to the National Science Foundation (NSF) as a Major Research Instrumentation (MRI) development [Aprile and Zelevinsky, 2009] and is funded by NSF and Columbia University. The ATTA method, originally developed at Argonne National Laboratory, uses standard laser cooling and trapping techniques, and counts single trapped atoms. Since the isotopic abundance of 85Kr in nature is 1.5 x 10-11, the 85Kr/Xe level is expected to be 10-23, which is beyond the capability of our method. Thus we detect the most abundant (57%) isotope 84Kr, and infer the 85Kr contamination from their known abundances. To avoid contamination by krypton, the setup is tested and optimized with 40 Ar which has a similar cooling wavelength to 84Kr. Two main challenges in this experiment are to obtain a trapping efficiency high enough to detect krypton impurities at the ppt level, and to achieve the resolution to discriminate single atoms. The device is specially designed and adjusted to meet these challenges. After achieving these criteria with argon gas, we precisely characterize the efficiency of the system using Kr-Xe mixtures with known ratios, and find that 90 minutes are required to trap one 84Kr atom at the 1-ppt Kr/Xe contamination. This thesis describes the design, construction, and experimental results of the ATTA project at Columbia University.

Yoon, Tae Hyun

117

INTEGRAL AND SPECTRAL CHARACTERISTICS OF ATON STATIONARY PLASMA THRUSTER OPERATING ON KRYPTON AND XENON  

Microsoft Academic Search

The integral characteristics of an ATON (1) stationary plasma thruster operating on xenon and krypton are investigated. It is shown that, with krypton, the thrust at the same mass flow rate of the working gas is greater and the efficiency is somewhat lower than those with xenon. An efficiency of ~60% was achieved with krypton for the specific impulse attaining

A. I. Bugrova; A. I. Morozov; A. S. Lipatov; A. M. Bishaev; V. K. Kharchevnikov; M. V. Kozintseva

118

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

119

The solubility of krypton in liquid cadmium and indium  

Microsoft Academic Search

In a previous paper (Johnson and Shuttleworth 1959) experimental measurements of the solubility of krypton in the tetravalent liquid metals lead and tin were found to agree quite well with values estimated from the surface energies of the liquid metals. This work has now been extended to divalent cadmium and trivalent indium, and the estimated solubilities are in reasonable agreement

G. W. Johnson

1961-01-01

120

Mobility of atomic hydrogen in solid krypton and xenon  

Microsoft Academic Search

Atomic hydrogen is produced in xenon and krypton matrix by in situ x-ray induced photolysis of the dopants water, butane, acetone, or methane and trapped interstitially forming the caged hydrogen with characteristic VUV absorption bands. Their thermal bleaching as investigated between 8 K and 45 K cannot be described by a first-order process. A random walk model is introduced considering

J. Eberlein; Martin Creuzburg

1997-01-01

121

ATTA - A New Method of Ultrasensitive Trace-Isotope Analysis  

Microsoft Academic Search

We have developed a new method of ultrasensitive trace-isotope analysis based upon the technique of laser manipulation of neutral atoms [1]. This new method allows us to count individual 85Kr and 81Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10-11 and 10-13, respectively. Isotope analysis of 81Kr can be used to date polar

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

2000-01-01

122

Peters' Anomaly  

PubMed Central

While conducting medical aid in Mozambique, a 41 year old African male presented to our eye clinic complaining of visual impairment. The male was found to have Peters anomaly type 2, a rare congenital ocular malformation leading to sensory amblyopia and glaucoma.

Sault, Robert W.; Sheridan, Jeffrey

2013-01-01

123

DOWN'S ANOMALY.  

ERIC Educational Resources Information Center

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)

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

124

Ebstein's anomaly.  

PubMed

Ebstein's anomaly is a rare congenital heart disease, accounting for less than 1% of all congenital heart diseases, characterized by a wide clinical, electrocardiographic, echocardiographic, anatomic and prognostic polymorphism. The disease can be fatal since birth or may remain asymptomatic until adulthood, sometimes being associated with septal defects, transposition of great vessels, preexcitation syndromes, or left ventricular noncompaction. The genetic changes underlying this syndrome are not fully known, but in the cases associating left ventricular nonompaction a mutation in MYH7 gene encoding the beta-myosin heavy chain was recently detected. The authors present 2 cases of Ebstein's anomaly with different onset and course and discuss the current clinical, electrocardiographic and echocardiographic criteria used for prognostic stratification of Ebstein disease in relation to international literature. PMID:24502034

Dima-Cozma, Corina; Cojocaru, Doina-Clementina; Chiriac, Silvia; Negru, R; Mitu, F

2013-01-01

125

Global characteristics of an ATON stationary plasma thruster operating with krypton and xenon  

Microsoft Academic Search

The global characteristics of an ATON stationary plasma thruster operating on xenon and krypton are investigated. It is shown\\u000a that, with krypton, the thrust at the same mass flow rate of the working gas is greater and the efficiency is somewhat lower\\u000a than those with xenon. An efficiency of ?60% was achieved with krypton for the specific impulse attaining 3000

A. I. Bugrova; A. S. Lipatov; A. I. Morozov; L. V. Solomatina

2002-01-01

126

The solubility of krypton in liquid lead, tin and silver  

Microsoft Academic Search

By means of radioactive Kr the solubility of krypton in liquid lead and liquid tin has been measured. In the temperature range 800c to 1300c for lead and 1100c to 1300c for tin the Ostwald coefficient r (volume of gas dissolved in unit volume of metal) varies with temperature according to the empirical relation and the thermodynamic equation where 1\\/a

G. W. Johnson; R. Shuttleworth

1959-01-01

127

Shortwave krypton-bromine excimer low-pressure lamp  

NASA Astrophysics Data System (ADS)

The emission characteristics are reported for a small short-wavelength (UV) lamp filled with a krypton-bromine mixture and pumped by longitudinal glow discharge at a 100-mm distance between electrodes in a quartz tube with an internal diameter of 14 mm. The emission spectrum is formed by the resonance atomic lines of bromine (163.3 and 157.6 nm) and the molecular lines of bromine (Br2) and krypton bromide (KrBr). An increase in the partial pressure of bromine in the working mixture from 50 to 270 Pa is accompanied by a decrease in the intensity of emission lines due to atomic bromine and leads to the formation of VUV-UV continuum based on the molecular bands due to Br2 and KrBr. The operation regime was optimized with respect to the glow discharge current and the gas mixture pressure and composition. The optimum partial pressure of krypton is within 500-800 Pa, and that of bromine vapor is within 100-250 Pa. The average total VUV-UV output radiation power reached 5 W at an efficiency of 8-10%.

Shuaibov, A. K.; Grabovaya, I. A.

2006-12-01

128

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

NASA Astrophysics Data System (ADS)

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

Schmitt, J.; Seth, B.; Bock, M.; van der Veen, C.; Mller, L.; Sapart, C. J.; Prokopiou, M.; Sowers, T.; Rckmann, T.; Fischer, H.

2013-05-01

129

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

Code of Federal Regulations, 2010 CFR

...Self-luminous products containing tritium, krypton-85 or promethium-147...self-luminous products containing tritium, krypton-85, or promethium-147...application for a license to transfer tritium, krypton-85, or promethium-147...product. (iv) Solubility in water and body fluids of the...

2009-01-01

130

32.8-nm X-ray laser produced in a krypton cluster jet  

NASA Astrophysics Data System (ADS)

We have interpreted the well-known experimental quantum yield data for a 32.8-nm X-ray laser operating at the 3d94d (J = 0) 3d94p (J = 1) transition of Kr8+ with the use of gaseous krypton or a krypton cluster jet. Proceeding from our model we propose a novel scheme for the 32.8-nm laser produced in a krypton cluster jet. The quantum yield is shown to saturate for a plasma length of ~300 ?m, a krypton ion density nKr ~ (4 9) 1019 cm-3, and an electron temperature Te ~ 5000 eV. In this case, the energy conversion coefficient amounts to ~5 10-3 of the pump pulse energy. We propose the experimental setup for producing a highefficiency subpicosecond X-ray laser in a krypton cluster jet.

Ivanova, E. P.; Vinokhodov, A. Yu

2013-12-01

131

Krypton gas cylinders as a source of radiation.  

PubMed

A standard 40 foot shipping container with a cargo of pressurized krypton gas in 159 steel cylinders, which had triggered a radiation alarm, was investigated to address radiation safety and illicit nuclear trafficking concerns. The investigation included contamination and dose rate measurements as well as in situ high resolution gamma spectroscopy. The dose rate measurements gave a maximum value of 0.07 microSv h(-1) above background (0.08 to 0.11 microSv h(-1)) on the cylinder surface and no detectable increase above background at distances of 1 m and higher. Contamination monitor readings showed a similar relative increase (plus 8 cpm) above background (about 12 cpm) to the dose rate readings. Quantitative gamma spectroscopy revealed a contamination of the gas with 85Kr at a level of 3.5 x 10(5) Bq kg(-1). This value was found to be consistent with analytical and numerical estimates based on current data for atmospheric 85Kr, which is captured from ambient air together with stable krypton during the production process. This incident demonstrates an apparent lack of radiation-related knowledge by those who handle krypton gas, as well as by border control personnel and emergency responders. We therefore propose to improve labeling and documentation standards for such shipments. This effort may be facilitated by introducing the new category of "technically enhanced artificial radioactive material," or "TEARM" (similar to the existing "naturally occurring radioactive material" or "NORM" and "technically enhanced naturally occurring radioactive material" or "TENORM" categories). PMID:20539125

Fischer, Helmut W; Bielefeld, Tom; Hettwig, Bernd

2010-07-01

132

Gauge Anomalies, Gravitational Anomalies, and Superstrings.  

National Technical Information Service (NTIS)

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. (ERA citation 11:021380)

W. A. Bardeen

1985-01-01

133

Krypton-81m ventilation scanning: acute respiratory disease  

SciTech Connect

From experience with 700 patients undergoing ventilation and perfusion lung scanning with krypton-81m/technetium-99m technique, 34 patients suffering from nonembolic acute respiratory disease were selected for review. In 16 patients with pneumonia, all had defects of ventilation corresponding to, or larger than, the radiologic consolidation. In 13 patients there was some preservation of perfusion in the consolidated region. In two of the three patients with matched defects, the pneumonia was of long standing. In seven patients with collapse or atelectasis and in 11 patients with acute reversible bronchial obstruction and normal volume lungs, a similar pattern or ventillation and perfusion was observed.

Lavender, J.P. (Royal Postgraduate Medical School, London, England); Irving, H.; Armstrong, J.D. II

1981-02-01

134

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)

There is still much uncertainty whether the El Nio 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 information will contribute to a better understanding of the lake system and ecology of the jellyfish, providing a better basis for conservation efforts.

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

2004-12-01

135

Photoassociation spectroscopy of purely long-range krypton molecules  

NASA Astrophysics Data System (ADS)

Photoassociation spectra for purely long-range (PLR) krypton molecules are both computed and measured. The photoassociation laser is tuned just red of the 5s[3/2]2-5p[5/2]2 transition at 810.6 nm, over a frequency range in which fourteen different PLR potential wells support hundreds of vibrational bound states. In the experiment, laser light is directed into a cloud of magneto-optically trapped 84Kr atoms, and the emission of both ultraviolet photons and ions is monitored. Peaks in these signals are observed for laser frequencies within 200 MHz of the atomic resonance. Ongoing work is aimed at improving the experimental signal and understanding the degree of agreement between empirical data and computed molecular spectra.

Smith, Z.; Banister, J.; Norman, R.; Hoogeboom, K.; Walhout, M.

2009-11-01

136

The NA62 liquid Krypton calorimeter's new readout system  

NASA Astrophysics Data System (ADS)

The NA62 experiment [1] at CERN SPS (Super Proton Synchrotron) accelerator aims at studying Kaon decays with high precision. The high resolution Liquid Krypton (LKr) calorimeter, built for the NA48 [2] experiment, is a crucial part of the experiment photon-veto system; to cope with the new requirements, the back-end electronics of the LKr had to be completely renewed. Due to the huge number of the calorimeter readout channels ( ~ 14 K) and the maintenance requirement over 10 years of the experiment lifetime, the decision to sub-contract the development and production to industry was taken in 2011. This paper presents the primary test results of the Calorimeter REAdout Module (CREAM) [3] prototype delivered by the manufacturer in March 2013. All essential features, analog performance, data processing and readout, are covered.

Ceccucci, A.; Fantechi, R.; Farthouat, P.; Lamanna, G.; Rouet, J.; Ryjov, V.; Venditti, S.

2014-01-01

137

The NA62 Liquid Krypton calorimeter readout module  

NASA Astrophysics Data System (ADS)

The NA62 experiment [1] at CERN SPS (Super Proton Synchrotron) accelerator will be focused on precision tests of the Standard Model via studies of ultra-rare decays of charged kaons. The high resolution Liquid Krypton (LKr) calorimeter of the former NA48 experiment [2], together with other detectors, will provide a photon-veto with hermetic coverage from zero out to large angles from the decay region. The old backend electronics [3] does not satisfy the NA62 specifications and the study of a new readout system began in 2008. This paper presents the Calorimeter REAdout Module (CREAM), an upgrade project for the backend part of the LKr data acquisition chain [3]. The CREAMs will provide 40 MHz sampling of 13248 calorimeter channels, data buffering during the SPS spill, zero suppression, and programmable trigger sums for the experiment trigger processor.

Ceccucci, A.; Fantechi, R.; Farthouat, P.; Lamanna, G.; Ryjov, V.

2011-12-01

138

Krypton spectroscopy diagnosis of high temperature implosions. Semiannual report  

SciTech Connect

This report covers observation of K-shell krypton lines, determination of temperature by line-intensity ratio, mixing diagnosis based on high-opacity Kr lines, and a method for measuring the escape factor. High-temperature implosions are planned for the OMEGA Upgrade experimental program. By using relatively thin shell targets, temperatures >> 1 keV at modest compressed densities (1-5 g/cm{sup 3}) are predicted. Goal is to demonstrate that by adding a small admixture of Kr (0.01 atm) to the fuel, the temperature can be diagnosed through the spectrum of He-like (Kr{sup +34}) and H-like (Kr{sup 35+}) lines. By increasing the fill pressure, resonant Kr lines become opaque through self absorption and relative intensities can be used to diagnose shell-fuel mixing.

NONE

1995-12-31

139

Immobilization of Krypton-85 in Zeolite 5A and Porous Glass.  

National Technical Information Service (NTIS)

This report demonstrates the technical and economic feasibility for immobilizing krypton-85 by high pressure/high temperature encapsulation in zeolite 5A or thirsty Vyco porous glass. Data are presented to show how process conditions affect the encapsulat...

A. B. Christensen J. A. DelDebbio D. A. Knecht J. E. Tanner S. C. Cossel

1981-01-01

140

Ionization EM calorimetry with accordion electrodes and liquid krypton or argon.  

National Technical Information Service (NTIS)

The results of a study and tests of a liquid krypton/argon electromagnetic calorimeter with accordion electrode structure are briefly summarized. This includes the calorimeter response to electrons and muons, energy, pointing and timing resolution, and a ...

V. Radeka

1993-01-01

141

Electron-Ion-Coincidence Measurements for K-Shell Excited Free Krypton Clusters  

Microsoft Academic Search

The decay processes of inner-core excited krypton atom and free krypton clusters up to = 1640, being the average cluster size, have been studied by means of electron ion coincidence (EICO) measurements utilizing hard X-ray. Unlike the soft X-ray absorption measurements, highly charged daughter ions are observed. With increasing cluster size, the relative abundance of the multiply charged ions decreases

Kiyonobu Nagaya; Makoto Yao; Hitoshi Murakami; Arata Mori; Yoshinori Ohmasa; Hiroaki Kajikawa

2006-01-01

142

Photolytic separation of isotopes in cryogenic solution  

DOEpatents

Separation of carbon isotopes by photolysis of CS.sub.2 in cryogenic solutions of nitrogen, krypton and argon with 206 nm light from an iodine resonance lamp is reported. The spectral distribution of the ultraviolet absorption depends on solvent. Thus, in liquid nitrogen the photolytic decomposition rate of .sup.13 CS.sub.2 is greater than that of .sup.12 CS.sub.2 (because the absorption of 206 nm radiation is greater for .sup.13 CS.sub.2), whereas in liquid krypton and liquid argon the reverse is true. The shift in ultraviolet spectrum is a general phenomenon readily characterized as a function of solvent polarizability, and exhibits behavior similar to that for vibrational transitions occurring in the infrared.

Freund, Samuel M. (Santa Fe, NM); Maier, II, William B. (Los Alamos, NM); Holland, Redus F. (Los Alamos, NM); Beattie, Willard H. (Los Alamos, NM)

1985-01-01

143

SST Anomalies + Wind Anomalies (with dates)  

NSDL National Science Digital Library

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

Shirah, Greg; Allen, Jesse; Adamec, David

2003-02-03

144

A search for isotopic anomalies in uranium  

NASA Astrophysics Data System (ADS)

The U-238/U-235 ratios for nine bulk chondritic meteorites and a terrestrial basalt were measured. The total range in U-238/U-235 determined for both total meteorites and for acid leaches was from 137.2 terrestrial U. The typical errors in a single determination are plus or minus 6 per thousand (2 sigma m) for a 2 ng U sample from a chondrite. Taking the extreme values of delta U-235 for each measurement the maximum amount of excess U-235 that can be allowed to be present ranges from 200 million to 2 billion atoms per gram of bulk meteorite. These results do not support the claims of variations in U-238/U-235 at the percentage levels or number of excess U-235 atoms in some of the same meteorites as reported by several other previous workers.

Chen, J. H.; Wasserburg, G. J.

1980-04-01

145

Finite-size effects in molecular dynamics simulations: Intermediate scattering function and velocity of sound. III. Theory and application to a model krypton fluid  

NASA Astrophysics Data System (ADS)

We describe a method for obtaining the intermediate scattering function I(Q,t) from a computer simulation: it is an extension of our earlier calculation [Salacuse, Denton, and Egelstaff, Phys. Rev. E 53, 2382 (1996)] for the t-->0 limit. We use this approach to obtain I(Q,t) for low Q and t from molecular dynamics (MD) simulations of a model krypton fluid whose atoms interact via a truncated Aziz pair potential, and the results are compared over their range of validity to I(Q,t) determined by the standard MD method and also by a time expansion approach. In its range of validity our approach is much more efficient than the standard MD method; however, it covers a restricted range of t due to the movement of density fluctuations (sound waves) through the simulated fluid which produces an anomaly in the time behavior of I(Q,t). By analyzing I(Q=0,t) the velocity of sound in the simulation is determined, and the results compare favorably with published experimental results for the sound velocity of liquid krypton.

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

2001-11-01

146

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

PubMed Central

Hyperpolarized (hp) 129Xe and hp 83Kr for magnetic resonance imaging (MRI) are typically obtained through spin-exchange optical pumping (SEOP) in gas mixtures with dilute concentrations of the respective noble gas. The usage of dilute noble gases mixtures requires cryogenic gas separation after SEOP, a step that makes clinical and preclinical applications of hp 129Xe MRI cumbersome. For hp 83Kr MRI, cryogenic concentration is not practical due to depolarization that is caused by quadrupolar relaxation in the condensed phase. In this work, the concept of stopped flow SEOP with concentrated noble gas mixtures at low pressures was explored using a laser with 23.3 W of output power and 0.25 nm linewidth. For 129Xe SEOP without cryogenic separation, the highest obtained MR signal intensity from the hp xenon-nitrogen gas mixture was equivalent to that arising from 15.51.9% spin polarized 129Xe in pure xenon gas. The production rate of the hp gas mixture, measured at 298 K, was 1.8 cm3/min. For hp 83Kr, the equivalent of 4.40.5% spin polarization in pure krypton at a production rate of 2 cm3/min was produced. The general dependency of spin polarization upon gas pressure obtained in stopped flow SEOP is reported for various noble gas concentrations. Aspects of SEOP specific to the two noble gas isotopes are discussed and compared with current theoretical opinions. A non-linear pressure broadening of the Rb D1 transition was observed and taken into account for the qualitative description of the SEOP process.

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

2012-01-01

147

Magnetic Anomalies over Iceland  

Microsoft Academic Search

An aeromagnetic survey of Iceland reveals broad anomalies of large amplitude over zones of recent volcanic activity. The source of the anomalies is ascribed to large masses of basalt that have been coherently remagnetized by intrusive heating. A simple correlation of the Icelandic anomalies with those of the ocean floor therefore appears unjustified.

P. H. Serson; W. Hannaford; G. V. Haines

1968-01-01

148

Magnetic Anomalies over Iceland.  

PubMed

An aeromagnetic survey of Iceland reveals broad anomalies of large amplitude over zones of recent volcanic activity. The source of the anomalies is ascribed to large masses of basalt that have been coherently remagnetized by intrusive heating. A simple correlation of the Icelandic anomalies with those of the ocean floor therefore appears unjustified. PMID:17836657

Serson, P H; Hannaford, W; Haines, G V

1968-10-18

149

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

150

Analysis of spacecraft anomalies  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

151

Discovery of Cadmium, Indium, and Tin Isotopes  

NASA Astrophysics Data System (ADS)

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

Amos, Stephanie; Thoennessen, Michael

2009-10-01

152

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

153

Anomaly detection using topology  

NASA Astrophysics Data System (ADS)

In this paper we present a new topology-based algorithm for anomaly detection in dimensionally large datasets. The motivating application is hyperspectral imaging where the dataset can be a collection of ~ 106 points in Rk, representing the reflected (or radiometric) spectra of electromagnetic radiation. The algorithm begins by building a graph whose edges connect close pairs of points. The background points are the points in the largest components of this graph and all other points are designated as anomalies. The anomalies are ranked according to their distance to the background. The algorithm is termed Topological Anomaly Detection (TAD). The algorithm is tested on hyperspectral imagery collected with the HYDICE sensor which contains targets of known reflectance and spatial location. Anomaly maps are created and compared to results from the common anomaly detection algorithm RX. We show that the TAD algorithm performs better than RX by achieving greater separation of the anomalies from the background for this dataset.

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

2007-04-01

154

First Detection of Krypton and Xenon in a White Dwarf  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

155

Radioactive Iodine and Krypton Control for Nuclear Fuel Reprocessing Facilities  

SciTech Connect

The removal of volatile radionuclides generated during used nuclear fuel reprocessing in the US is almost certain to be necessary for the licensing of a reprocessing facility in the US. Various control technologies have been developed, tested, or used over the past 50 years for control of volatile radionuclide emissions from used fuel reprocessing plants. The US DOE has sponsored, since 2009, an Off-gas Sigma Team to perform research and development focused on the most pressing volatile radionuclide control and immobilization problems. In this paper, we focus on the control requirements and methodologies for 85Kr and 129I. Numerous candidate technologies have been studied and developed at laboratory and pilot-plant scales in an effort to meet the need for high iodine control efficiency and to advance alternatives to cryogenic separations for krypton control. Several of these show promising results. Iodine decontamination factors as high as 105, iodine loading capacities, and other adsorption parameters including adsorption rates have been demonstrated under some conditions for both silver zeolite (AgZ) and Ag-functionalized aerogel. Sorbents, including an engineered form of AgZ and selected metal organic framework materials (MOFs), have been successfully demonstrated to capture Kr and Xe without the need for separations at cryogenic temperatures.

N. R. Soelberg; J. D. Law; T. G. Garn; M. Greenhalgh; R. T. Jubin; P. Thallapally; D. M. Strachan

2013-08-01

156

First Detection of Krypton and Xenon in a White Dwarf  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

157

Inertial Fusion Target Physics Advantages with the Krypton Fluoride Laser  

NASA Astrophysics Data System (ADS)

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

Obenschain, Stephen

2010-11-01

158

Krypton charge exchange cross sections for Hall effect thruster models  

NASA Astrophysics Data System (ADS)

Following discharge from a Hall effect thruster, charge exchange occurs between ions and un-ionized propellant atoms. The low-energy cations produced can disturb operation of onboard instrumentation or the thruster itself. Charge-exchange cross sections for both singly and doubly charged propellant atoms are required to model these interactions. While xenon is the most common propellant currently used in Hall effect thrusters, other propellants are being considered, in particular, krypton. We present here guided-ion beam measurements and comparisons to semiclassical calculations for Kr+ + Kr and Kr2+ + Kr cross sections. The measurements of symmetric Kr+ + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr2+ + Kr reaction, we present cross section measurements for center-of-mass energies between 1 eV and 300 eV, which spans energies not previously examined experimentally. These cross section measurements compare well with a simple one-electron transfer model. Finally, cross sections for the asymmetric Kr2+ + Kr --> Kr+ + Kr+ reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A?2 with an exception near 70-80 eV.

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

2013-04-01

159

Krypton Separation from Ambient Air for Application in Collinear Fast Beam Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

A portable apparatus for the separation of krypton from environmental air samples was tested. The apparatus is based on the cryogenic trapping of gases at liquid nitrogen temperature followed by controlled releases at higher temperatures. The setup consists of a liquid nitrogen trap for the removal of H2O and CO2, followed by charcoal-filled coils that sequentially collect and release krypton and other gases providing four stages of gas chromatography to achieve separation and purification of krypton from mainly N2, O2, and Ar. Residual reactive gases remaining after the final stage of chromatography are removed with a hot Ti sponge getter. A thermal conductivity detector is used to monitor the characteristic elution times of the various components of condensed gases in the traps during step-wise warming of the traps from liquid nitrogen temperatures to 0 C, and then to 100 C. This allows optimizing the switching times of the valves between the stages of gas chromatography so that mainly krypton is selected and loaded to the next stage while exhausting the other gases using a He carrier. A krypton separation efficiency of ~80 % was determined using a quadrupole mass spectrometer.

Mohamed, Tarek; Strohaber, James; Nava, Ricardo; Kolomenskii, Alexandre; Thonnard, Norbert; Schuessler, Hans A.

2012-07-01

160

The generalized Bouguer anomaly  

Microsoft Academic Search

This paper states on the new concept of the generalized Bouguer anomaly (GBA) that is defined upon the datum level of an arbitrary elevation. Discussions are particularly focused on how to realize the Bouguer anomaly that is free from the assumption of the Bouguer reduction density rhoB, namely, the rhoB-free Bouguer anomaly, and on what is meant by the rhoB-free

Kyozo Nozaki

2006-01-01

161

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

Microsoft Academic Search

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

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

2000-01-01

162

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

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

163

Adsorption of krypton on a gold surface studied by the ICISS method  

NASA Astrophysics Data System (ADS)

Adsorption of krypton atoms on the cold surface of a polycrystalline gold target in the presence of ion bombardment was studied by the ICISS method. It was shown that the distance between the first adsorption submonolayer and the gold substrate is 2 0.8 , and it is smaller than for typical physisorption of rare gases on metals. Probably, the adsorption proceeds in two stages. In the first stage a lowering of the target temperature leads to physical adsorption therefore an increase of the krypton concentration in the vicinity of the surface takes place. In the second stage, under ion bombardment the krypton atoms are displaced nearer to the gold substrate. This means that the character of bonds between adatoms and substrate changes from a van der Waals type to a more complex type, for example, with participation of metallic bonds.

Soszka, W.

1991-06-01

164

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

165

Anomalies in Political Economy  

Microsoft Academic Search

Results in cognitive psychology and experimental economics indicate that under identifiable conditions individuals do not act in an economically rational way. These results are important for Political Economy. Anomalies appear in the behaviour of voters, politicans and administrators. Economic markets do not fully eliminate anomalies in the aggregation process. It is shown that political aggregation by democracy, bargaining or bureaucracy

Bruno S. Frey; Reiner Eichenberger

1991-01-01

166

Filtering Marine Magnetic Anomalies  

Microsoft Academic Search

When marine magnetic anomalies can be adequately modeled by two-dimensional magnetic structures within one or more plane layers, many interesting manipulations of both models and anomalies are linear filtering operations [Dean, 1958; Bott, 1967; Black and Scollar, 1969; Schouten, 1971]. Linear filters can be applied quickly and accurately by using the fast Fourier transform algorithm [Cooley and Tukey, 1965]. We

Hans Schouten; Keith McCamy

1972-01-01

167

Yields and isomeric ratio of xenon and krypton isotopes from thermal neutron fission of 235U  

Microsoft Academic Search

The experimental cumulative yields of 85Krm, 87Kr, 88Kr, 133Xeg, 135Xem, and 135Xeg and the independent isomeric yield of 133Xem in the thermal neutron fission of 235U have been measured by the gas chromatographic method. The independent yields of 133Xeg, 135Xem, and 135Xeg were deduced with the aid of 133I and 135I data. The isomeric yield ratios of 133Xe and 135Xe

S. S. Hsu; J. T. Lin; C. M. Yang; Y. W. Yu

1981-01-01

168

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

SciTech Connect

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

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

2013-01-01

169

Photoionization Study of Diatomic-Ion Formation in Argon, Krypton, and Xenon  

Microsoft Academic Search

Ionization current at wavelengths of discrete absorption lines of five resonance series of argon, krypton, and xenon has been observed in the vacuum ultraviolet. This ionization is due to a collision process between electronically excited and ground-state atoms resulting in formation of a diatomic ion and an electron. Using the helium and argon continuum light sources, it was possible to

Robert E. Huffman; Daniel H. Katayama

1966-01-01

170

Mass Spectrometric Observation of Ions Formed During Shock Wave Heating of Gaseous Krypton and Xenon.  

National Technical Information Service (NTIS)

Mass spectrometric observation of ions sampled directly from shock waves in krypton and xenon at 3600 to 7800 K shows that the principal ion is usually Kr+ or Xe+. Appreciable quantities of impurity ions have also been identified, and it is shown that the...

R. A. Creswell M. A. DiValentin J. E. Dove

1966-01-01

171

Experimental Studies on the Krypton Absorption in Liquid CO sub 2 (KALC) Process.  

National Technical Information Service (NTIS)

Results are presented for a series of experiments to quantify krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing off-gas by the KALC process. The Experimental Engineering Section Off-Gas Decontamination Facility used in the ca...

R. W. Glass H. W. R. Beaujean V. L. Fowler T. M. Gilliam D. J. Inman

1976-01-01

172

Cross sections for electron-impact excitation out of the metastable levels of krypton  

NASA Astrophysics Data System (ADS)

We have measured cross sections for electron-impact excitation out of the metastable levels of krypton into seven of the ten levels of the 4p^55p configuration. Two sources of metastable krypton atoms are used: a hollow cathode discharge, and a fast beam target formed via near-resonant charge exchange between a 2.5 keV krypton ion beam and a cesium vapor. Both sources produce targets with a mixture of atoms in the ^1P0 ground state and ^3P0 and ^3P2 metastable levels. The high number of ground state atoms emerging from the hollow cathode discharge limits measurements with this source to electron beam energies below the threshold for ground state excitation (<11 eV). Patterns in the sizes and energy dependencies of the cross sections will be compared to our previous work on excitation out of the ground state of krypton(J. E. Chilton, et al.), Phys. Rev. A. 62, 032714 (2000). and the metastable levels of other heavy rare gas atoms(J. B. Boffard, et al.), Phys Rev. A 59, 2749 (1999)..

Boffard, John B.; Stone, Tom; Larsen, M.; Anderson, L. W.; Lin, Chun C.

2002-05-01

173

Energy-momentum structure of the krypton valence shell by electron-momentum spectroscopy.  

National Technical Information Service (NTIS)

Momentum distributions and spectroscopic factors are obtained in a high resolution electron-momentum spectroscopy study of krypton at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in good agreement with the results of calculatio...

R. Nicholson S. W. Braidwood I. E. McCathy E. Weigold M. J. Brunger

1996-01-01

174

Charge-Changing Cross Sections from the Fragmentation of Relativistic Krypton and Silver Nuclei  

Microsoft Academic Search

The fragmentation of ultraheavy nuclei is of great interest in cosmic ray and nuclear physics. The charge -changing cross sections are measured for the fragmentation of krypton and silver nuclei on targets of hydrogen, polyethylene, lithium, carbon, aluminum, copper, tin, and lead at energies from 450 to 1500 MeV\\/nucleon. The detector system used in these measurements and the method used

Bjorn Steven Nilsen

1994-01-01

175

Purification of krypton-xenon mixture from fluorine-containing gases  

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

176

Anomalies on orbifolds  

SciTech Connect

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

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

2001-03-16

177

Short root anomaly.  

PubMed

A case of generalised short root anomaly is described. All permanent teeth had abnormally short roots, associated with microdontia, hypodontia and a dens invaginatus. Members of the patient's family were similarly affected. PMID:2261278

Edwards, D M; Roberts, G J

1990-11-10

178

The chlamydial anomaly clarified?  

PubMed

Getting visible: A new method to label bacterial cell walls shows the presence of functional peptidoglycan in the important pathogen Chlamydia trachomatis. This might clarify the long-standing paradox of the "chlamydial anomaly". PMID:24891214

Mohammadi, Tamimount; Breukink, Eefjan

2014-07-01

179

SADM potentiometer anomaly investigations  

NASA Astrophysics Data System (ADS)

During the last 3 years Contraves Space have been developing a Low Power (1-2kW) Solar Array Drive Mechanism (SADM) aimed at small series production. The mechanism was subjected to two test programmes in order to qualify the SADM to acceptable levels. During the two test programmes, anomalies were experienced with the Potentiometers provided by Eurofarad SA and joint investigations were undertaken to resolve why these anomalies had occurred. This paper deals with the lessons learnt from the failure investigation on the two Eurofarad (rotary) Potentiometer anomaly. The Rotary Potentiometers that were used were fully redundant; using two back to back mounted "plastic tracks". It is a pancake configuration mounted directly to the shaft of the Slip Ring Assembly at the extreme in-board end of the SADM. It has no internal bearings. The anomaly initially manifested itself as a loss of performance in terms of linearity, which was first detected during Thermal Vacuum testing. A subsequent anomaly manifested itself by the complete failure of the redundant potentiometer again during thermal vacuum testing. This paper will follow and detail the chain of events following this anomaly and identifies corrective measures to be applied to the potentiometer design and assembly process.

Wood, Brian; Mussett, David; Cattaldo, Olivier; Rohr, Thomas

2005-07-01

180

Meteoritic Sulfur Isotopic Analysis  

NASA Technical Reports Server (NTRS)

Funds were requested to continue our program in meteoritic sulfur isotopic analysis. We have recently detected a potential nucleosynthetic sulfur isotopic anomaly. We will search for potential carriers. The documentation of bulk systematics and the possible relation to nebular chemistry and oxygen isotopes will be explored. Analytical techniques for delta(sup 33), delta(sup 34)S, delta(sup 36)S isotopic analysis were improved. Analysis of sub milligram samples is now possible. A possible relation between sulfur isotopes and oxygen was detected, with similar group systematics noted, particularly in the case of aubrites, ureilites and entstatite chondrites. A possible nucleosynthetic excess S-33 has been noted in bulk ureilites and an oldhamite separate from Norton County. High energy proton (approximately 1 GeV) bombardments of iron foils were done to experimentally determine S-33, S-36 spallogenic yields for quantitation of isotopic measurements in iron meteorites. Techniques for measurement of mineral separates were perfected and an analysis program initiated. The systematic behavior of bulk sulfur isotopes will continue to be explored.

Thiemens, Mark H.

1996-01-01

181

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

Code of Federal Regulations, 2010 CFR

Self-luminous products containing tritium, krypton-85 or promethium-147: Requirements for license to manufacture, process, produce, or initially transfer. 32.22 Section 32.22 Energy NUCLEAR REGULATORY...

2010-01-01

182

Krypton Absorption in Liquid CO sub 2 (Kalc): Campaign II in the Experimental Engineering Section off-Gas Decontamination Facility.  

National Technical Information Service (NTIS)

Results are presented for the second major campaign for quantifying krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing off-gas by the KALC process. The Experimental Engineering Section Off-Gas Decontamination Facility used in ...

R. W. Glass H. W. R. Beaujean V. L. Fowler T. M. Gilliam D. J. Inman

1976-01-01

183

X-ray absorption and de-excitation processes of krypton clusters studied by the XAFS-PEPICO synchronous measurements  

Microsoft Academic Search

XAFS-PEPICO synchronous measurement has been applied to free neutral krypton clusters to study the x-ray absorption and de-excitation processes of clusters. The PEPICO measurements for krypton atom reveal that the highly charged daughter ions of Krz+ (z = 311) are generated as a result of the deexcitation process. As the cluster size increases, the Kr+, Kr2+ and Kr3+ daughter ion,

K Nagaya; A Mori; H Murakami; M Yao; Y Ohmasa; H Kajikawa; K Kobayashi; Y Kajihara; A Chiba; Y Nishikawa; M Ishii; Y Fujii; E Hayata

2005-01-01

184

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

Microsoft Academic Search

The authors characterize continuous-wave operation of a chromium-doped forsterite (Cr4+:Mg2SiO4) laser using krypton ion, Ti:sapphire, and Nd:YAG lasers as pump sources. Measurements were made pumping at 647 nm and 676 nm with the krypton ion laser, between 690 and 1010 nm with the Ti:sapphire laser, and at 1.06 ?m with the Nd:YAG laser. Threshold pump powers and slope efficiencies are

Timothy J. Carrig; Clifford R. Pollock

1993-01-01

185

Nonlinear optical processes in xenon and krypton studied by two-color multiphoton ionization  

SciTech Connect

Multiphoton ionization (MPI) and third-harmonic generation (THG) in xenon and krypton have been studied via three-photon resonance with the xenon 6s'(1/2)/sub 1//sup 0/ and krypton 5s((3/2)/sub 1//sup 0/ states. A second, tunable dye laser is used to couple these states to higher-lying even-parity states. Observations are reported regarding the third-harmonic related cancellation of the intermediate s-state population and the mechanisms of population of the final states. Effects of the four-photon resonance on THG are detailed. Changes induced by the second laser reduce THG in normally favorable regions and enable it in otherwise forbidden regions. Striking effects in the MPI spectra due to the changes induced in THG are reported.

Blazewicz, P.R.; Miller, J.C.

1988-09-15

186

Photochemistry of the ozone-water complex in cryogenic neon, argon, and krypton matrixes.  

PubMed

The photochemistry of ozone-water complexes and the wavelength dependence of the reactions were studied by matrix isolation FTIR spectrometry in neon, argon, and krypton matrixes. Hydrogen peroxide was formed upon the irradiation of UV light below 355 nm. Quantitative analyses of the reactant and product were performed to evaluate the matrix cage effect of the photoreaction. In argon and krypton matrixes, a bimolecular O((1)D) + H2O ? H2O2 reaction was found to occur to form hydrogen peroxide, where the O((1)D) atom generated by the photolysis of ozone diffused in the cryogenic solids to encounter water. In a neon matrix, hydrogen peroxide was generated through intracage photoreaction of the ozone-water complex, indicating that a neon matrix medium is most appropriate to study the photochemistry of the ozone-water complex. PMID:24252115

Tsuge, Masashi; Tsuji, Kazuhide; Kawai, Akio; Shibuya, Kazuhiko

2013-12-12

187

Experimental determination of the scattering length for positron scattering from krypton  

NASA Astrophysics Data System (ADS)

We report the first experimentally supported determination of the scattering length for positron scattering from krypton. Our result of -10.3 1.5 a.u. compares favourably with that from a convergent close coupling calculation performed as a part of this investigation (-9.5 a.u.), and also with an earlier many body theory calculation of -10.1 a.u. from Gribakin and Ludlow [Phys. Rev. A 70, 032720 (2004)] and a polarized-orbital result of -10.4 a.u. from McEachran et al. [J. Phys. B 13, 1281 (1980)]. The present experimental scattering length supports the existence of a low-lying positron-krypton virtual state (Surko et al. [J. Phys. B 38, R57 (2005)]) at an energy ? = 0.13 eV.

Zecca, A.; Chiari, L.; Trainotti, E.; Fursa, D. V.; Bray, I.; Brunger, M. J.

2011-10-01

188

Neutron production with mixture of deuterium and krypton in Sahand Filippov type plasma focus facility  

NASA Astrophysics Data System (ADS)

This Letter reports the order of magnitude enhancement in neutron yield from Sahand plasma focus device with krypton seeded deuterium operation. The highest average neutron yield of 2.210 neutrons per shot was achieved at 1.00 Torr deuterium with 3% krypton which is higher than the best average neutron yield of 3.1810 neutrons per shot for pure deuterium operation. Estimation of average neutron energy showed that the maximum and minimum average energies are 2.980.6MeV at 16 kV in 0.25 Torr deuterium with 3% Kr and 2.070.2MeV at 18 kV operation in 0.5 Torr deuterium with 3% Kr, respectively. The anisotropy of neutron emission from Sahand DPF showed that the neutrons are produced mainly by beam-target mechanisms.

Mohammadi, M. A.; Sobhanian, S.; Rawat, R. S.

2011-08-01

189

Demonstrate the removal efficiency and capacity of MOF materials for krypton recovery  

SciTech Connect

Metal organic framework materials (MOFs) were developed and tested in support of the U.S. Department of Energy Office of Nuclear Energy, Fuel Cycle Technology Separations and Waste Forms Campaign. Specifically, materials are being developed for the removal of xenon (Xe) and krypton (Kr) from gaseous products of nuclear fuel reprocessing unit operations. Two metal organic framework structures were investigated in greater detail to demonstrate the removal efficiency and capacity of MOF materials for krypton recovery. Our two bed breakthrough measurements on NiDOBDC and FMOFCu indicate these materials can capture and separate parts per million levels of Xe and Kr from air. The removal efficiency and adsorption capacity for Kr on these two MOFs were further increased upon removal of Xe upfront.

Thallapally, Praveen K.; Liu, Jian; Strachan, Denis M.

2013-08-23

190

High-Power Krypton Hall Thruster Technology Being Developed for Nuclear-Powered Applications  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center has been performing research and development of moderate specific impulse, xenon-fueled, high-power Hall thrusters for potential solar electric propulsion applications. These applications include Mars missions, reusable tugs for low-Earth-orbit to geosynchronous-Earth-orbit transportation, and missions that require transportation to libration points. This research and development effort resulted in the design and fabrication of the NASA-457M Hall thruster that has been tested at input powers up to 95 kW. During project year 2003, NASA established Project Prometheus to develop technology in the areas of nuclear power and propulsion, which are enabling for deep-space science missions. One of the Project-Prometheus-sponsored Nuclear Propulsion Research tasks is to investigate alternate propellants for high-power Hall thruster electric propulsion. The motivation for alternate propellants includes the disadvantageous cost and availability of xenon propellant for extremely large scale, xenon-fueled propulsion systems and the potential system performance benefits of using alternate propellants. The alternate propellant krypton was investigated because of its low cost relative to xenon. Krypton propellant also has potential performance benefits for deep-space missions because the theoretical specific impulse for a given voltage is 20 percent higher than for xenon because of krypton's lower molecular weight. During project year 2003, the performance of the high-power NASA-457M Hall thruster was measured using krypton as the propellant at power levels ranging from 6.4 to 72.5 kW. The thrust produced ranged from 0.3 to 2.5 N at a discharge specific impulse up to 4500 sec.

Jacobson, David T.; Manzella, David H.

2004-01-01

191

Measurement of electron-impact excitation cross sections out of the metastable levels of krypton  

Microsoft Academic Search

We have measured cross sections for electron-impact excitation out of the metastable levels of krypton into selected levels of the 4p^55p configuration (2pn in Paschen's notation). For measurements at low electron energies (<11 eV), a hollow cathode discharge is used as the source of metastable atoms. For measurements at high energies (11 to 500 eV), the metastable atoms are formed

Tom Stone; John B. Boffard; L. W. Anderson; Chun C. Lin

2001-01-01

192

High-pressure equation of state for solid krypton from interatomic potentials  

Microsoft Academic Search

The pressure-volume isotherm for krypton at 300 K is evaluated by the Monte Carlo method using pair and three-body potentials. The pair potentials used are that of Aziz and Slaman and a slightly modified version of their potential which gives better agreement with high-energy scattering data. The three-body potentials considered are the Axilrod-Teller interaction and the first-order three-body exchange interaction

J. A. Barker

1988-01-01

193

High-pressure equations of state of krypton and xenon by a statistical mechanical theory  

Microsoft Academic Search

We present statistical mechanical calculations for krypton and xenon, employing accurate pair potentials with and without condensed-phase modifications. A unique feature of the present work is that solid- and fluid-phase thermodynamic properties are both computed within a single framework, using our recently developed hard-sphere perturbation theory. Results are applied to analyze experimental fluid, solid, and fluidsolid transition data, ranging up

Jae Hyun Kim; Taikyue Ree; Francis H. Ree

1989-01-01

194

High-pressure equations of state of krypton and xenon by a statistical mechanical theory  

Microsoft Academic Search

We present statistical mechanical calculations for krypton and xenon, employing accurate pair potentials with and without condensed-phase modifications. A unique feature of the present work is that solid- and fluid-phase thermodynamic properties are \\/ital both\\/ computed within a \\/ital single\\/ framework, using our recently developed hard-sphere perturbation theory. Results are applied to analyze experimental fluid, solid, and fluid--solid transition data,

Jae Hyun Kim; Taikyue Ree; Francis H. Ree

1989-01-01

195

RF sputtering of epitaxial lead chalcogenide films in argon and krypton plasma  

Microsoft Academic Search

The measurements of sputtering etch rates for monocrystalline (1 1 1)-oriented epitaxial films of semiconductor binary compounds PbTe, PbSe, PbS in RF high-density low-pressure inductively coupled argon and krypton plasma were performed. Films with 1-5 m thickness were grown on Si(1 1 1) and BaF2(1 1 1) substrates using molecular beam epitaxy. Sputtering was carried out with the energy of

S. P. Zimin; I. I. Amirov; E. S. Gorlachev

2011-01-01

196

Krypton and Xenon Losses in Low-Pressure Air Separation Rectification Units  

Microsoft Academic Search

There are over 40 types of Russian air-separation plant (ASP) [1]. From the viewpoint of the economics of extracting krypton Kr and xenon Xe, the main interest attaches to ASP producing gaseous oxygen at a level of not less than 3000 m 3 \\/h, which may be termed high-production plant. Such plant uses a low-pressure cycle with an air expansion

A. M. Arkharov; M. Yu. Savinov; V. L. Bondarenko; A. S. Bronshtein

2003-01-01

197

Experimental studies on the krypton absorption in liquid CO (KALC) process  

Microsoft Academic Search

Results are presented for a series of experiments to quantify krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing off-gas by the KALC process. The Experimental Engineering Section Off-Gas Decontamination Facility used in the campaign provides engineering-scale experiments with nominal gas and liquid flows of 5 scfm and 0.5 gpm respectively. Equilibrium and nonequilibrium mass transfer experiments for the CO--O--Kr system

R. W. Glass; H. W. R. Beaujean; V. L. Fowler; T. M. Gilliam; D. J. Inman; D. M. Levins

1976-01-01

198

Thermodynamic and molecular properties of gas hydrates from mixtures containing methane, argon, and krypton  

Microsoft Academic Search

Because hydrate formation in pipelines, processing operations, and reservoirs is generally undesirable, studies of gas-hydrate thermodynamics, particularly examinations of conditions where a second hydrate phase or a hydrocarbon-rich phase exists in addition to the water, hydrate, and gas phases, are important to the natural gas industry. In this study, analysts used experimental methane-krypton and methane-argon hydrate data to generate chemical-potential,

G. D. Holder; G. Corbin; K. D. Papadopoulos

1980-01-01

199

Multielectron coincidence study of the double Auger decay of 3d-ionized krypton  

Microsoft Academic Search

Multielectron coincidence data for triple ionization of krypton have been recorded above the 3d ionization threshold at two photon energies (140 and 150 eV). Three principal transition pathways have been observed, two involving double Auger transitions from Kr+, and one involving single Auger transitions from Kr2+ created by direct single-photon double ionization. The decay of the 3d9 2D5\\/2,3\\/2 states in

E. Andersson; S. Fritzsche; P. Linusson; L. Hedin; J. H. D. Eland; J.-E. Rubensson; L. Karlsson; R. Feifel

2010-01-01

200

Multielectron coincidence study of the double Auger decay of 3d-ionized krypton  

Microsoft Academic Search

Multielectron coincidence data for triple ionization of krypton have been recorded above the 3d ionization threshold at two photon energies (140 and 150 eV). Three principal transition pathways have been observed, two involving double Auger transitions from Kr{sup +}, and one involving single Auger transitions from Kr{sup 2+} created by direct single-photon double ionization. The decay of the 3d D2,3\\/2}

E. Andersson; L. Hedin; J.-E. Rubensson; L. Karlsson; R. Feifel; S. Fritzsche; P. Linusson; J. H. D. Eland

2010-01-01

201

Charge Distributions of Krypton Ions Following PhotoIonization in the M Shell  

Microsoft Academic Search

Charge distributions of krypton ions that result from ionization in the M shell by x rays have been measured with a magnetic mass spectrometer. X-ray energies ranged from 100 to 1400 eV. The following results are derived from the charge spectra: (a) In filling a hole in the 3d shell, an Auger process which generates two continuum electrons competes strongly

Manfred O. Krause; Thomas A. Carlson

1966-01-01

202

Experimental determination of tetrafluoromethane and hexafluoroethane accumulation in khrom-3 kryptonxenon mixture producing equipment  

Microsoft Academic Search

Experimental data are provided on perfluorocarbon accumulation from atmospheric air in an industrial facility in Ukraine in\\u000a the process of air treatment in a modern air-fractionating plant with production of kryptonxenon mixture. Comparison of the\\u000a obtained data with the calculated values supports the proposition put forward by these authors regarding the crucial contribution\\u000a of adsorption processes to the final outcome

V. L. Bondarenko; N. P. Losyakov; V. B. Vorotyntsev; V. A. Mamrenko; Ya. V. Dzyuzyura; A. A. Vinnik

2010-01-01

203

Superstrings, anomalies and unification  

SciTech Connect

This volume contains the lectures covering the main lines of developments in the presently most active field of particle physics: string field theory, anomalies, unification and physics beyond the Planck length. The lectures are generally pedagogical in style, designed at the postdoctoral level, but at the same time they introduce one to the most recent results in the field.

Martinis, M.; Andric, I.

1987-01-01

204

Ca isotope variations in Allende  

NASA Technical Reports Server (NTRS)

Ca-isotope measurements of Allende Ca-Al-rich inclusions (CAIs), together with those on an apatite-enriched fraction from Orgueil, indicate the existence of widespread excesses on the neutron-rich isotope Ca-48. Isotopic anomalies are noted in 7 out of 11 CAIs analyzed. This abundance of isotopic excesses places Ca alongside Ti and O, although no clear correlation has yet been found between Ca-48 and Ti-50, which are thought to be coproduced by neutron-rich nucleosynthetic processes within stars. It is suggested that the higher volatility of Ca, by comparison with Ti compounds, led to a variable dilution with isotopically normal Ca in vaporization and recondensation processes in stellar envelopes, the interstellar medium, and/or the solar nebula.

Jungck, M. H. A.; Shimamura, T.; Lugmair, G. W.

1984-01-01

205

Isotopic Biogeochemistry.  

National Technical Information Service (NTIS)

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 micr...

J. M. Hayes

1985-01-01

206

Isotope Separation.  

National Technical Information Service (NTIS)

Separation of isotopes is treated in a general way, with special reference to the production of enriched uranium. Uses of separated isotopes are presented quickly. Then basic definitions and theoretical concepts are explained: isotopic effects, non statis...

J. Ravoire

1978-01-01

207

Ferret Workflow Anomaly Detection System.  

National Technical Information Service (NTIS)

The Ferret workflow anomaly detection system project 2003-2004 has provided validation and anomaly detection in accredited workflows in secure knowledge management systems through the use of continuous, automated audits. A workflow, process, or procedure,...

T. J. Smith S. Bryant

2005-01-01

208

Space Weather and Satellite Anomalies  

Microsoft Academic Search

Results 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, are presented. Anomaly data from the \\

Lev Dorman; N. Iucci; A. E. Levitin; A. V. Belov; E. A. Eroshenko; N. G. Ptitsyna; G. Villoresi; G. V. Chizhenkov; L. I. Gromova; M. Parisi; M. I. Tyasto; V. G. Yanke

2010-01-01

209

Algebraic Structure of Chiral Anomalies.  

National Technical Information Service (NTIS)

I will describe first the algebraic aspects of chiral anomalies, exercising however due care about the topological delicacies. I will illustrate the structure and methods in the context of gauge anomalies and will eventually make contact with results obta...

R. Stora

1985-01-01

210

Global Climate Highlights and Anomalies  

NSDL National Science Digital Library

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

1999-01-01

211

Yukawa textures and anomalies  

Microsoft Academic Search

We augment the Minimal Supersymmetric Standard Model with a gauged family-dependent U(1) to reproduce Yukawa textures compatible with experiment. In the simplest model with one extra chiral electroweak singlet field, acceptable textures require this U(1) to be anomalous. The cancellation of its anomalies by a generic Green-Schwarz mechanism requires sin2?w = 38 at the string scale, suggesting a supersting a

Pierre Bintruy; Pierre Ramond

1995-01-01

212

Penile anomalies in adolescence.  

PubMed

This article considers the impact and outcomes of both treatment and underlying condition of penile anomalies in adolescent males. Major congenital anomalies (such as exstrophy/epispadias) are discussed, including the psychological outcomes, common problems (such as corporal asymmetry, chordee, and scarring) in this group, and surgical assessment for potential surgical candidates. The emergence of new surgical techniques continues to improve outcomes and potentially raises patient expectations. The importance of balanced discussion in conditions such as micropenis, including multidisciplinary support for patients, is important in order to achieve appropriate treatment decisions. Topical treatments may be of value, but in extreme cases, phalloplasty is a valuable option for patients to consider. In buried penis, the importance of careful assessment and, for the majority, a delay in surgery until puberty has completed is emphasised. In hypospadias patients, the variety of surgical procedures has complicated assessment of outcomes. It appears that true surgical success may be difficult to measure as many men who have had earlier operations are not reassessed in either puberty or adult life. There is also a brief discussion of acquired penile anomalies, including causation and treatment of lymphoedema, penile fracture/trauma, and priapism. PMID:21399858

Wood, Dan; Woodhouse, Christopher

2011-01-01

213

Complex vascular anomalies.  

PubMed

The classification system for vascular anomalies now used by experts worldwide comprises two distinct disease entities that differ in their biologic and pathologic features: vascular tumors and vascular malformations. Vascular tumors include infantile and congenital hemangiomas, tufted angiomas, and kaposiform hemangioendotheliomas. Infantile hemangiomas, the most common vascular anomaly, generally have a predetermined life cycle (proliferation and subsequent involution). GLUT-1, a glucose transporter, is a marker for these specific lesions during all phases of development. Vascular malformations are classified according to their vascular tissue of origin and include capillary, venous, arteriovenous, lymphatic, and mixed malformations. Complex lymphatic malformations and complex mixed malformations, which may have most vascular components, are the most difficult vascular malformations to successfully treat. These lesions are present at birth and often expand or grow in response to trauma, infection, or hormonal changes. Imaging advancements have enabled more accurate assessments and improved management of vascular anomalies. In addition, many lesions are now being managed with targeted pharmacologic therapy. Propranolol and steroids are used for complex or disfiguring tumors, and new anti-angiogenesis inhibitors such as sirolimus are selectively used to treat lymphatic and venous lymphatic malformations that are poorly responsive to sclerotherapy, embolization, and surgical excision. Multimodal therapies are often essential for complex lesions and require the combined expertise of an interdisciplinary team. PMID:23989523

Azizkhan, Richard G

2013-10-01

214

Pathogenesis of Vascular Anomalies  

PubMed Central

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

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

2010-01-01

215

Groundwater age structure and palaeo hydrogeology over a 500 kyr time scale revealed from Krypton 81and a multiple tracer study: Great Artesian Basin  

NASA Astrophysics Data System (ADS)

We report on the most comprehensive set of krypton -81 data to be analysed so far. Our study site is on the western margin of the Great Artesian Basin (GAB). The study area is focused on the western margin of the GAB between the Finke River system in the Northern Territory and the iconic Dalhousie springs in South Australia. This represents the direction of groundwater flow from recharge to discharge through the Dalhousie spring complex. Because of its vast size and the potential for large regional flow systems to occur, the GAB has been considered an ideal basin to test emerging groundwater dating techniques such as Cl-36 and He-4. However both of these techniques are subjected to large degrees of uncertainty, as they require a detailed understanding of different sources and sinks of these two isotopes. Contrasting this Kr-81 is considered to be an ideal tracer as it contains only one source, the atmosphere with no or at most minimal sub surface production. For the first time we have provided a comprehensive suite of analyse not only of Cl-36, He-4, C-14, Ar-39, stable isotopes of the water molecule and noble gases but also, Kr-85 and Kr-81. Our results indicate a spectrum of 'groundwater ages' ranging from modern as indicated by thermonuclear C-14 and Ar-39 up to hundreds of thousands of years as indicated by Kr-81, Cl-36 and He-4. The data set indicates a wide range of stable isotopes of the water molecule as well as variability in noble gas recharge temperatures that suggest that not only has this region been subjected to changes in climate in the recharge zone but also testaments to a changes in the dominate direction of rainfall indicated by a change in recharge mechanism at the beginning of the Holocene. As suggested previously this groundwater flow transect may represent an ideal 'type section' for testing new and emerging environmental tracers in hydrogeology.

Love, A. J.; Purtschert, R.; Jiang, W.; Lu, Z.; Tosaki, Y.; Fulton, S.; Wohling, D.; Shand, P.; Broder, L.; Aeschbach, W.; Rousseau=Gueutin, P.

2013-12-01

216

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

PubMed

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

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

2014-01-01

217

Satellite magnetic anomalies over subduction zones - The Aleutian Arc anomaly  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

218

Hypercharged anomaly mediation.  

PubMed

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

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

2008-04-01

219

[First branchial cleft anomalies].  

PubMed

First branchial cleft anomalies are congenital rare lesions that can sometimes be difficult to diagnose. During the normal embryonic development the outer ear canal derives from the first branchial cleft. Abnormal development can result in production of a cyst, sinus or fistula with recurring infections. Early and correct diagnosis is necessary for the correct choice of surgical set-up in which identification and preservation of the facial nerve is an important step. A case of first branchial cleft sinus is presented with further discussion of classification, diagnostics and treatment. PMID:18489895

Nikoghosyan, Gohar; Krogdahl, Annelise; Godballe, Christian

2008-05-12

220

Angular distribution of Auger electrons due to 3d-shell ionization of krypton  

NASA Technical Reports Server (NTRS)

Cross sections for electron impact ionization of krypton due to ejection of a 3rd shell electron have been calculated using screened hydrogenic and Hartree-Slater wave functions for target atom. While the total ionization cross sections in the two approximations are within 10% of each other, the Auger electron angular distribution, related to cross sections for specific magnetic quantum numbers of the 3rd electrons, is widely different in the two approximations. The angular distribution due to Hartree-Slater approximation is in excellent agreement with measurement. The physical reason for the discrepancies in the two approximations is explained.

Omidvar, K.

1977-01-01

221

Effects of three-body interactions on the structure and thermodynamics of liquid krypton  

NASA Astrophysics Data System (ADS)

Large-scale molecular dynamics simulations are performed to predict the structural and thermodynamic properties of liquid krypton using a potential energy function based on the two-body potential of Aziz and Slaman plus the triple-dipole Axilrod-Teller (AT) potential. By varying the strength of the AT potential we study the influence of three-body contribution beyond the triple-dipole dispersion. It is seen that the AT potential gives an overall good description of liquid Kr, though other contributions such as higher order three-body dispersion and exchange terms cannot be ignored.

Jakse, N.; Bomont, J. M.; Bretonnet, J. L.

2002-05-01

222

Large S-33 Anomalies in Late Archean Carbonacous Shales  

Microsoft Academic Search

Multi-sulfur isotope ratios (34S\\/33S\\/32S) were determined on sulfides extracted from two late Archean carbonaceous shale units, the Mt. McRae shale (~2.5 Ga) and the Jeerinah formation (~2.7 Ga), from the Hamersley Basin, Western Australia by using the CO2-laser fluorination line at the Geophisical Laboratory. We have measured the largest Delta33S anomaly yet reported for a terrestrial sample on sulfides from

S. Ono; D. Rumble; A. Pavlov; P. Kharecha; J. F. Kasting

2002-01-01

223

54Cr Anomalies in the Orgueil Carbonaceous Chondrite  

Microsoft Academic Search

Cr in CI meteorites displays isotopic anomalies in a unique pattern [1-3]. Etching of bulk Orgueil in relatively mild reactants (CH3COOH and dilute HNO3) dissolves most (>80%) of the Cr along with most of other major cations (Mg, Ca, Fe, Ni, Al). The Cr thus dissolved is deficient in 54Cr by about 6 epsilon-units (using 50Cr\\/52Cr normalization). Much of the

F. A. Podosek; U. Ott; J. C. Brannon; T. J. Bernatowicz; C. R. Neal

1995-01-01

224

Lunar Orbit Anomaly  

NASA Astrophysics Data System (ADS)

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

Riofrio, L.

2012-12-01

225

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

PubMed

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

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

2010-03-28

226

Supergravity theories, anomalies and compactification  

SciTech Connect

This book is a collection of reprints on the structure of Poincare, anti-de Sitter and conformal supergravity theories in one to eleven dimensions, their anomalies and compactification. Each chapter contains introductory comments and an extensive list of references. Contents: Vol. 1: Representations of Supersymmetry in Various Dimensions; Poincare and ADS Supergravity Theories in Various Dimensions; Anomalies in Supergravity Theories. Vol. 2: Compactification of Supergravity Theories; Conformal Supergravity Theories in Various Dimensions; Anomalies in Conformal Supergravity Theories.

Salam, A.; Sezgin, E.

1986-01-01

227

Vaginal surgery for congenital anomalies.  

PubMed

Congenital anomalies of the vagina may be isolated to the vagina or be part of a more complex Mullerian tract anomaly with possible fertility concerns. Patient age, complete assessment of the anomaly before surgery, and the psychologic implications for the patient are important components of the initial evaluation and treatment planning. Imaging, including magnetic resonance imaging, should be used to assess the extent of the anomaly and possibly other organ systems involved. Surgeries for imperforate hymen, longitudinal septum, and low thin transverse septum are relatively straightforward. More complicated surgeries should be performed by a specialized surgical team. PMID:20142648

Quint, Elisabeth H; McCarthy, Jenifer D; Smith, Yolanda R

2010-03-01

228

Atmospheric circulation controls on precipitation isotope-climate relations in western Canada  

Microsoft Academic Search

delta18O and delta2H time-series of monthly composite precipitation (July 1975-June 1982) for three stations located in western Canada were examined to characterize the influence of atmospheric circulation on modern isotope-climate relations in the region. Spatially coherent trends in long-term isotope and temperature anomalies were evident among the three stations, with isotope and temperature anomalies showing the strongest correlations when weighted

S. J. Birks; T. W. D. Edwards

2009-01-01

229

Molybdenum Evidence for Inherited Planetary Scale Isotope Heterogeneity of the Protosolar Nebula  

Microsoft Academic Search

Isotope anomalies provide important information about early solar system evolution. Here we report molybdenum isotope abundances determined in samples of various meteorite classes. There is no fractionation of molybdenum isotopes in our sample set within 0.10\\/00 and no contribution from the extinct radionuclide 97Tc at mass 97 (97Tc\\/92Mo<310-6). Instead, we observe clear anomalies in bulk iron meteorites, mesosiderites, pallasites, and

N. Dauphas; B. Marty; L. Reisberg

2002-01-01

230

Four-body interaction energy for compressed solid krypton from quantum theory  

NASA Astrophysics Data System (ADS)

The importance of the four-body contribution in compressed solid krypton was first evaluated using the many-body expansion method and the coupled cluster theory with full single and double excitations plus perturbative treatment of triples. All different four-atom clusters existing in the first- and second-nearest neighbor shells of face-centered cubic krypton were considered, and both self-consistent-field Hartree-Fock and correlation parts of the four-body interaction were accurately determined from the ambient conditions up to eightfold volume compression. We find that the four-body interaction energy is negative at compression ratio lower than 2, where the dispersive forces play a dominant role. With increasing the compression, the four-body contribution becomes repulsive and significantly cancels the over-softening effects of the three-body potential. The obtained equation of state (EOS) was compared with the experiments and the density-functional theory calculations. It shows that combination of the four-body effects with two- and three-body interactions leads to an excellent agreement with EOS measurements throughout the whole experimental range 0-130 GPa, and extends the prediction to 300 GPa.

Tian, Chunling; Wu, Na; Liu, Fusheng; Saxena, Surendra K.; Zheng, Xingrong

2012-07-01

231

Short wavelength laser calculations for electron pumping in neon-like krypton (Kr XXVII)  

NASA Technical Reports Server (NTRS)

Calculations of electron impact collision strengths and spontaneous radiative decay rates are made for neon-like krypton (Kr XXVII) for the 2s2 2p6, 2s2 2p5 3s, 2s2 2p5 3p, and 2s2 2p5 3d configurations. From these atomic data, the level populations as a function of the electron density are calculated at two temperatures, 1 x 10 to the 7th K and 3 x 10 to the 7th K. An analysis of level populations reveals that a volume of krypton in which a significant number of the ions are in the Kr XXVII degree of ionization can produce a significant gain in transition between the 2s2 2p5 3s and 2s2 2p5 3p configurations. At an electron density of 1 x 10 to the 19th/cu cm the plasma length has to be of the order of 1 m; at a density of 1 x 10 to the 21st/cu cm the length is reduced to approximately 0.5 cm; and at an electron density of 1 x 10 to the 22nd/cu cm the length of the plasma is further reduced to approximately 1 mm.

Feldman, U.; Bhatia, A. K.; Suckewer, S.

1983-01-01

232

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

PubMed

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

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

2011-05-01

233

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

234

182Hf, a new isotope for AMS  

Microsoft Academic Search

The neutron-rich isotope 182Hf with its half-life of 92 million years was alive in the early solar system and has been used to study the early development of the Earth and the Moon through isotopic anomalies of its stable decay product 182W. In addition, 182Hf may also complement a few other radionuclides in the million-year half-life range to trace relatively

Christof Vockenhuber; Max Bichler; Robin Golser; Walter Kutschera; Alfred Priller; Peter Steier; Stephan Winkler

2004-01-01

235

Neon isotopes in submarine basalts  

Microsoft Academic Search

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

Philippe Sarda; Thomas Staudacher; Claude J. Allgre

1988-01-01

236

Isotopic Paleotemperatures.  

National Technical Information Service (NTIS)

The temperature dependence of oxygen-isotope fractionation in the system carbon dioxide-water-calcium carbonate was proposed by Urey as a basis for determining the temperature of precipitation of the carbonate by measuring its oxygen-isotope composition. ...

C. Emiliani

1966-01-01

237

Genetics of lymphatic anomalies.  

PubMed

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

Brouillard, Pascal; Boon, Laurence; Vikkula, Miikka

2014-03-01

238

Discharges of krypton from Sellafield, 1951-1997, and the resultant doses to members of the public  

Microsoft Academic Search

The radionuclide , which has a half-life of 10.72 years, is produced, almost exclusively, by reprocessing operations during which the fission product is released from irradiated nuclear fuel by chemical dissolution. Reprocessing plants at Sellafield, in Cumbria, have released the noble gas to atmosphere since operations commenced in 1952. Historically, krypton discharges were classified for security reasons, although these have

D. Jackson; C. H. Zimmerman; J. Gray

1998-01-01

239

Soft X-ray Emission Optimization Studies with Krypton and Xenon Gases in Plasma Focus Using Lee Model  

NASA Astrophysics Data System (ADS)

The X-ray emission properties of krypton and xenon plasmas are numerically investigated using corona plasma equilibrium model. Numerical experiments have been investigated on various low energy plasma focus devices with Kr and Xe filling gases using Lee model. The Lee model was applied to characterize and to find the optimum combination of soft X-ray yields (Ysxr) for krypton (~4 ) and xenon (~3 ) plasma focus. These combinations give Ysxr = 0.018 J for krypton, and Ysxr = 0.5 J for xenon. Scaling laws on Kr and Xe soft X-ray yields, in terms of storage energies E0, peak discharge current Ipeak and focus pinch current Ipinch were found over the range from 2.8 to 900 kJ. Soft X-ray yields scaling laws in terms of storage energies were found to be as and for Kr and Xe, respectively, (E0 in kJ and Ysxr in J) with the scaling showing gradual deterioration as E0 rises over the range. The maximum soft X-ray yields are found to be about 0.5 and 27 J from krypton and xenon, respectively, for storage energy of 900 kJ. The optimum efficiencies for soft X-ray yields (0.0002 % for Kr) and (0.0047 % for Xe) are with capacitor bank energies of 67.5 and 225 kJ, respectively.

Akel, Mohamad

2013-10-01

240

Transport of atmospheric trace gases to the water table: Implications for groundwater dating with chlorofluorocarbons and krypton 85  

Microsoft Academic Search

Chlorofluorocarbons and krypton 85 are trace gases whose atmospheric concentrations have been increasing over the past few decades. As they are soluble in water, they have been used as groundwater age indicators over timescales ranging from a few years to a few decades. In this paper we show that the time lag for transport of these atmospheric trace gases through

P. G. Cook; D. K. Solomon

1995-01-01

241

Adsorptive Separation of Krypton-85 in Reprocessing Plant in Consideration of Gas Impurities and a Xenon-Preseparation.  

National Technical Information Service (NTIS)

After loading at low temperatures and following desorption on activated charcoal krypton is separated out of waste gas. In a compact pilot plant a high degree of retention is achieved. The components in waste gas like methane, carbondioxid, laughing gas a...

G. Assmann

1986-01-01

242

Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Bromine and Krypton  

SciTech Connect

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of bromine and krypton (34 {le} Z {le} 37, 40 {le} N {le} 47).

Hoffman, R; Dietrich, F; Bauer, R; Kelley, K; Mustafa, M

2004-07-23

243

Anomaly detection in crowded scenes  

Microsoft Academic Search

A novel framework for anomaly detection in crowded scenes is presented. Three properties are identified as important for the design of a localized video representation suitable for anomaly detection in such scenes: (1) joint modeling of appearance and dynamics of the scene, and the abilities to detect (2) temporal, and (3) spatial abnormalities. The model for normal crowd behavior is

Vijay Mahadevan; Weixin Li; Viral Bhalodia; Nuno Vasconcelos

2010-01-01

244

Supergravity theories, anomalies and compactification  

Microsoft Academic Search

This book is a collection of reprints on the structure of Poincare, anti-de Sitter and conformal supergravity theories in one to eleven dimensions, their anomalies and compactification. Each chapter contains introductory comments and an extensive list of references. Contents: Vol. 1: Representations of Supersymmetry in Various Dimensions; Poincare and ADS Supergravity Theories in Various Dimensions; Anomalies in Supergravity Theories. Vol.

A. Salam; E. Sezgin

1986-01-01

245

Anomaly detection in clinical processes  

PubMed Central

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

Huang, Zhengxing; Lu, Xudong; Duan, Huilong

2012-01-01

246

Emission characteristics of pulse-periodic barrier-discharge plasma in a mixture of krypton with argon and liquid freon vapor  

NASA Astrophysics Data System (ADS)

Radiation of a nanosecond barrier discharge in a mixture of krypton, argon, and carbon-tetrachloride vapor is studied in the spectral range of 150-300 nm. The plasma radiation spectra and the dependences of the intensities of the 258 nm Cl2( D' ? A'), 222 nm KrCl( B ? X), and 175 nm ArCl( B ? X) bands on the partial pressure of liquid freon vapor, argon, and krypton, as well as on the discharge excitation conditions, are studied. The optimal compositions of gas mixtures for creating a broadband UV-VUV emitter based on the band system of argon chloride, krypton chloride, and chlorine molecule are determined.

Shuaibov, A. K.; Minya, A. I.; Gritsak, R. V.; Gomoki, Z. T.

2014-02-01

247

In situ measurements of krypton in xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed  

NASA Astrophysics Data System (ADS)

A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of 330200 ppt.

Brown, E.; Rosendahl, S.; Huhmann, C.; Weinheimer, C.; Kettling, H.

2013-02-01

248

Isotopic composition of waters from Ethiopia and Kenya: Insights into moisture sources for eastern Africa  

Microsoft Academic Search

Oxygen and deuterium isotopic values of meteoric waters from Ethiopia are unusually high when compared to waters from other high-elevation settings in Africa and worldwide. These high values are well documented; however, the climatic processes responsible for the isotopic anomalies in Ethiopian waters have not been thoroughly investigated. We use isotopic data from waters and remote data products to demonstrate

Naomi E. Levin; Edward J. Zipser; Thure E. Cerling

2009-01-01

249

Isotopic Compositions of Cometary Matter Returned by Stardust  

Microsoft Academic Search

Hydrogen, carbon, nitrogen, and oxygen isotopic compositions are heterogeneous among comet 81P\\/Wild 2 particle fragments; however, extreme isotopic anomalies are rare, indicating that the comet is not a pristine aggregate of presolar materials. Nonterrestrial nitrogen and neon isotope ratios suggest that indigenous organic matter and highly volatile materials were successfully collected. Except for a single 17O-enriched circumstellar stardust grain, silicate

McKeegan Kevin D; Alon Jerome; Bradley John; Brownlee Donald; Busemann Henner; Butterworth Anna; Chaussidon Marc; Fallon Stewart; Floss Christine; Gilmour Jamie; Gounelle Matthieu; Graham Giles; Guan Yunbin; Heck Philipp R; Hoppe Peter; Hutcheon Ian D; Huth Joachim; Ishii Hope; Ito Motoo; Jacobsen Stein B; Kearsley Anton; Leshin Laurie A; Liu Ming-Chang; Lyon Ian; Marhas Kuljeet; Marty Bernard; Matrajt Graciela; Meibom Anders; Messenger Scott; Mostefaoui Smail; Mukhopadhyay Sujoy; Nakamura-Messenger Keiko; Nittler Larry; Palma Russ; Pepin Robert O; Papanastassiou Dimitri A; Robert Franois; Schlutter Dennis; Snead Christopher J; Stadermann Frank J; Stroud Rhonda; Tsou Peter; Westphal Andrew; Young Edward D; Ziegler Karen; Zimmermann Laurent; Ernst Zinner

2006-01-01

250

Isotopic perspectives on the western Himalayan syntaxis  

Microsoft Academic Search

The western syntaxis has been characterised as a structural and metamorphic anomaly within the Himalaya, resulting from extreme Neogene exhumation and associated partial melting. However, an integration of detailed fieldwork with whole-rock isotopic data indicates that all the major tectonic units observed along the arc of the orogen also occur in the syntaxis. Most of the rocks exposed by the

T. W. Argles; G. L. Foster; A. G. Whittington; M. T. George

2003-01-01

251

Isotopic composition and concentration of sulfur in carbonaceous chondrites  

NASA Technical Reports Server (NTRS)

New sulfur isotopic ratio measurements are reported for seven carbonaceous chondrites. Newly developed procedures permit measurement of delta S-33, delta S-34, and delta S-36 at precisions significantly greater than previously reported. A search for S-36 nucleosynthetic anomalies coproduced with anomalies in, for example, Ti-50 and Ca-48 was negative. The high endemic sulfur concentration probably dilutes any S-36 anomaly, and separation of individual sulfur phases may be needed to identify S-36 carrier phases. Large internal isotopic variations are observed, deriving from parent body and possibly nebular processes. Chondrule separates from Allende demonstrate isotopic compositions which vary as a function of diameter. High-temperature gas-solid exchange and a two-component mixing model may account for the observations. High-resolution isotopic data and structural information are reported for organic sulfur compounds separated by chemical extractions. The insoluble organics appear to be of either aliphatic or alicyclic structure and are dominant phases.

Gao, Xia; Thiemens, Mark H.

1993-01-01

252

Reliability of CHAMP Anomaly Continuations  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

253

Binning of satellite magnetic anomalies  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

254

Reactor antineutrino anomaly  

SciTech Connect

Recently, new reactor antineutrino spectra have been provided for {sup 235}U, {sup 239}Pu, {sup 241}Pu, and {sup 238}U, increasing the mean flux by about 3%. To a good approximation, this reevaluation applies to all reactor neutrino experiments. The synthesis of published experiments at reactor-detector distances <100 m leads to a ratio of observed event rate to predicted rate of 0.976{+-}0.024. With our new flux evaluation, this ratio shifts to 0.943{+-}0.023, leading to a deviation from unity at 98.6% C.L. which we call the reactor antineutrino anomaly. The compatibility of our results with the existence of a fourth nonstandard neutrino state driving neutrino oscillations at short distances is discussed. The combined analysis of reactor data, gallium solar neutrino calibration experiments, and MiniBooNE-{nu} data disfavors the no-oscillation hypothesis at 99.8% C.L. The oscillation parameters are such that |{Delta}m{sub new}{sup 2}|>1.5 eV{sup 2} (95%) and sin{sup 2}(2{theta}{sub new})=0.14{+-}0.08 (95%). Constraints on the {theta}{sub 13} neutrino mixing angle are revised.

Mention, G.; Fechner, M. [CEA, Irfu, SPP, Centre de Saclay, F-91191 Gif-sur-Yvette (France); Lasserre, Th.; Cribier, M. [CEA, Irfu, SPP, Centre de Saclay, F-91191 Gif-sur-Yvette (France); Astroparticule et Cosmologie APC, 10 rue Alice Domon et Leonie Duquet, 75205 Paris cedex 13 (France); Mueller, Th. A.; Lhuillier, D.; Letourneau, A. [CEA, Irfu, SPhN, Centre de Saclay, F-91191 Gif-sur-Yvette (France)

2011-04-01

255

Anomaly inflow and thermal equilibrium  

NASA Astrophysics Data System (ADS)

Using the anomaly inflow mechanism, we compute the flavor/Lorentz non-invariant contribution to the partition function in a background with a U(1) isometry. This contribution is a local functional of the background fields. By identifying the U(1) isometry with Euclidean time we obtain a contribution of the anomaly to the thermodynamic partition function from which hydrostatic correlators can be efficiently computed. Our result is in line with, and an extension of, previous studies on the role of anomalies in a hydrodynamic setting. Along the way we find simplified expressions for Bardeen-Zumino polynomials and various transgression formulae.

Jensen, Kristan; Loganayagam, R.; Yarom, Amos

2014-05-01

256

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

PubMed

Thermophoresis is the movement of molecules caused by a temperature gradient. Here we report the results of a study of thermophoresis using non-equilibrium molecular dynamics simulations of a confined argon-krypton fluid subject to two different temperatures at thermostated walls. The resulting temperature profile between the walls is used along with the Soret coefficient to predict the concentration profile that develops across the channel. We obtain the Soret coefficient by calculating the mutual diffusion and thermal diffusion coefficients. We report an appropriate method for calculating the transport coefficients for binary systems, using the Green-Kubo integrals and radial distribution functions obtained from equilibrium molecular dynamics simulations of the bulk fluid. Our method has the unique advantage of separating the mutual diffusion and thermal diffusion coefficients, and calculating the sign and magnitude of their individual contributions to thermophoresis in binary mixtures. PMID:24116632

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

2013-10-14

257

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

NASA Astrophysics Data System (ADS)

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

Kim, I.; Quevedo, H. J.; Feldman, S.; Bang, W.; Serratto, K.; McCormick, M.; Aymond, F.; Dyer, G.; Bernstein, A. C.; Ditmire, T.

2013-12-01

258

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

259

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

SciTech Connect

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

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

2013-12-15

260

The pair correlation function of krypton in the critical region: theory and experiment  

NASA Astrophysics Data System (ADS)

We present the results of high-precision measurements of the structure factor S(k) of krypton in the near-critical region of the liquid - vapour phase transition for values of k ranging from 1.5 up to 0953-8984/9/42/003/img15. The experimental results are compared with a theoretical calculation based on the hierarchical reference theory (HRT) with an accurate potential which includes two- and three-body contributions. The theory is based on a new implementation of HRT in which we avoid the use of hard spheres as a reference system. With this soft-core formulation we find a generally good agreement with experiments both at large k, where S(k) probes the short-range correlations, as well as at small k, where critical fluctuations become dominant. Also, for the density derivative of the pair correlation function there is an overall good agreement between theory and experiment.

Barocchi, F.; Chieux, P.; Fontana, R.; Magli, R.; Meroni, A.; Parola, A.; Reatto, L.; Tau, M.

1997-10-01

261

Mercury-free emitter pumped by a krypton fluoride molecule pulse-periodic barrier discharge  

NASA Astrophysics Data System (ADS)

The characteristics of a pulsed-periodic short-barrier-discharge emitter operating at wavelength ? = 248 nm KrF( X- B) are investigated. The operating mixtures of the UV lamp are low-aggressive krypton-sulfur hexafluoride (SF6) mixtures at a total pressure in the range 1-50 kPa and a SF6 partial pressure of 0.1-0.4 kPa. The spectral characteristics of the plasma are studied, and the 248 nm KrF( X-B) band luminosity is optimized in terms of the operating mixture composition, pump voltage, and pulse repetition rate. The mean power of UV emission from the lateral surface of the cylindrical lamp is estimated.

Shuaibov, A. K.; Gomoki, Z. T.; Minya, A. I.; Shevera, I. V.; Dzhupina, Ya. Yu.

2012-02-01

262

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

SciTech Connect

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

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

2002-03-31

263

X-Ray absorption spectroscopy investigations of the hydrophobic hydration of krypton at high pressure  

NASA Astrophysics Data System (ADS)

The development of third-generation synchrotron radiation sources has created considerable opportunities for the investigation of systems under extreme sample conditions of pressure and temperature. This paper presents the application of a recently developed pressure cell and pressurization and circulation system to the investigation of the hydrophobic hydration of noble gases by X-ray absorption spectroscopy. This system operates in the pressure range from 1 bar to 1 kbar, and allows for mixing of gaseous and liquid components and the control of the ultimate gas in liquid concentration. First results demonstrate the remarkable resilience of the first hydration shell of a nonpolar solute (krypton) to the application of pressure in the 150 bar to 700 bar range. These results suggest questioning the conclusions of some recent computer simulations, in particular with regards to the potential impact of such studies on our understanding of pressure induced protein denaturation.

Bowron, D. T.; Weigel, R.; Filipponi, A.; Roberts, M. A.; Finney, J. L.

264

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

PubMed

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

Patrykiejew, A; Soko?owski, S

2012-04-14

265

Comparative characteristics of high-pressure arc radiation in argon, krypton and xenon atmospheres  

NASA Astrophysics Data System (ADS)

Axisymmetric, high-pressure arcs in argon, krypton and xenon atmospheres, were theoretically modelled, and their radiation characteristics was calculated numerically using the equations of heat and radiation transfer. The coefficients of radiative absorption for these three gases were calculated both for the continuum spectra and selected spectral lines, for an arc pressure of 15 atm. In the case of the high-frequency region, ngr geq khgr0/h, where ngr is the frequency, h is Planck's constant and khgr0 is the first ionization energy, a black body radiation distribution was assumed, due to a high absorption coefficient, while for low-frequency radiation, ngr les khgr0/h, the radiation intensity as a function of the frequency is calculated. The radial temperature distribution as well as electrical conductivity and degree of ionization were derived for arc currents in the range 1200-7500 A, in arc plasma confined in a transparent tube of radius R = 0.01 m. The radiative power Wrad in a spectral range of (6-30) 103 with an arc current of ap1200 A was ap3 106 W m-1 for each of the examined gases, while for an arc current ap7500 A, it was ap17 106 W m-1 for krypton and ap13 106 W m-1 for xenon. The relative arc radiation efficiency, Wrad/WJoule, with an arc current of ap 1200 A, was largest for argon (35%) and smallest for xenon (18%), while at 7500 A the relative arc radiation efficiency for all the examined gases was ap5%. The calculated arc radiation spectra are also presented.

Gidalevich, E.; Goldsmith, S.; Boxman, R. L.

2004-08-01

266

Pacific Temperature Anomalies with Graph  

NSDL National Science Digital Library

This animation shows the El Nino-La Nina Sea Surface Temperature Anomaly from January 1997 through July 1999. A graph inset shows the global average sea surface temperature fluctuation during this time period.

Shirah, Greg; Bridgman, Tom; Starr, Cindy; Busalacchi, Antonio; Schultz, Peter

2003-08-30

267

A global magnetic anomaly map  

NASA Technical Reports Server (NTRS)

A subset of Pogo satellite magnetometer data has been formed that is suitable for analysis of crustal magnetic anomalies. Through the use of a thirteenth-order field model fit to these data, magnetic residuals have been calculated over the world to latitude limits of plus or minus 50 deg. These residuals, averaged over 1-degree latitude-longitude blocks, represent a detailed global magnetic anomaly map derived solely from satellite data. The occurrence of these anomalies on all individual satellite passes independent of local time and their decay as altitude increases imply a definite internal origin. Their wavelength structure and their correlation with known tectonic features further suggest that these anomalies are primarily of geologic origin and have their sources in the lithosphere.

Regan, R. D.; Davis, W. M.; Cain, J. C.

1975-01-01

268

Spacecraft environmental anomalies expert system  

NASA Astrophysics Data System (ADS)

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

Koons, Harry C.; Groney, David J.

1994-02-01

269

Vaginal Anomalies: Fusion and Duplication  

MedlinePLUS

... dolor sit amet, consectetur adipiscing elit. Vaginal Abnormalities: Fusion and Duplication Having two of everything may be ... if your child's doctor diagnoses an "anomaly of fusion and duplication." What causes vaginal fusion and duplication? ...

270

Classifying sex biased congenital anomalies  

SciTech Connect

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.

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

1997-03-31

271

Obstetric consequences of uterovaginal anomalies  

SciTech Connect

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

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

1985-05-01

272

The puzzle of silicon, titanium, and magnesium anomalies in meteoritic silicon carbide grains  

NASA Astrophysics Data System (ADS)

An astrophysical interpretation of the silicon, titanium, and magnesium isotope anomalies measured in the mainstream population of single silicon carbide (SiC) grains extracted from carbonaceous meteorites is presented. The condensation site of the grains is envisaged in the cool atmospheres of carbon stars. The Si isotope anomalies show a general linear correlation between Si-29/Si-28 aand Si-30/Si-28, whose slope cannot be explained only by s-processing in the He-burning shell and dilution with material of solar composition from the envelope. We suggest a multiple star scenario in which the SiC grains form in stellar envelopes with slightly nonsolar initial Si isotope composition and metallicities from one-half solar to solar. The initial Si abundances are inferred from considerations of galactic chemical evolution, coupling spectroscopic observations of abundances in stars of different metal content with current predictions of stellar nucleosynthesis. The isotopes Si-29 and Si-30 are assumed to be entirely produced by short-lived massive stars exploding as supernovae, which also contribute approximately 70% of the solar Si-28 abundance, the remaining approximately 30% coming from long-lived stars, evolving in binary systems, and leading to supernovae of Type Ia. More detailed calculations of the Si isotopes yields from stars of various mass and initial metallicity are, however, required, and a better understanding of how the nucleosynthetic ejecta by supernovae are well homogenized with the interstellar matter. Even the Ti isotope anomalies in SiC grains cannot be explained as only an s-process signature. The linear correlation shown by Ti and Si anomalies indicates that a similar approach can be used to interpret the Ti anomalies as a mixture of a pure s-component and of a variable nonsolar isotopic composition initially present in the envelope of carbon stars. The question of the large abundance of extinct Al-26 in many SiC grains is also considered. We find that the production of Al-26 in the H shell of thermally pulsing AGB stars, although followed by substantial consumption by neutron captures during He thermal pulses, can account for the high Al-26/Al-27 ratios. The spread of carbon anomalies is interpreted as a consequence of an initial spread of C-12/C-13 as observed in M stars and of the subsequent enrichment in C-12 of the envelope during thermal pulses. Finally, the nitrogen isotope anomalies are discussed.

Gallino, Roberto; Raiteri, Claudia M.; Busso, Maurizio; Matteucci, Francesca

1994-08-01

273

A SEARCH FOR {sup 70}Zn ANOMALIES IN METEORITES  

SciTech Connect

No {sup 70}Zn isotopic anomalies have been detected in primitive meteorites to a level of precision of less than 40 parts per million (2{sigma}). Any pre-existing nucleosynthetic anomaly on {sup 70}Zn was averaged out by mixing in the solar nebula before planetary accretion in the solar system. Because neutron-rich nuclides {sup 70}Zn and {sup 60}Fe are produced by similar nucleosynthetic processes in core-collapse supernovae, the homogeneity of {sup 70}Zn in meteorites limits the possible heterogeneity of extinct {sup 60}Fe radioactivity in the early solar system. Assuming that Fe and Zn have not been decoupled during incorporation into the solar system, the homogeneity of the {sup 70}Zn/{sup 64}Zn ratio measured here implies that the {sup 60}Fe/{sup 56}Fe ratio was homogenized to less than 15% dispersion before the formation of planetary bodies. The lack (Zn, Ni, Fe) or presence (Ti, Cr) of neutron-rich isotopic anomalies in the iron mass region may be controlled by the volatility of presolar carriers in the nebula.

Moynier, Frederic; Podosek, Frank A. [Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130 (United States); Dauphas, Nicolas [Origins Laboratory, Department of Geophysical Sciences and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)], E-mail: moynier@levee.wustl.edu, E-mail: fap@levee.wustl.edu, E-mail: dauphas@uchicago.edu

2009-08-01

274

Electrical, optical, and structural characteristics of ITO thin films by krypton and oxygen dual ion-beam assisted evaporation at room temperature  

Microsoft Academic Search

Transparent conducting tin-doped indium oxide (ITO) thin films on polycarbonate and glass substrates were deposited without substrate heating and post-deposition annealing using a dual ion-beam assisted evaporation technique, where the bombardment of the growing film surfaces during electron beam evaporation was done using krypton (varied ion flux, JKr+, and grid acceleration voltage, Va, of the krypton ion source) and oxygen

H. J. Kim; J. W. Bae; J. S. Kim; K. S. Kim; Y. C. Jang; G. Y. Yeom; N.-E. Lee

2000-01-01

275

Satellite elevation magnetic anomaly maps  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

276

Mullerian duct anomalies: MR imaging  

Microsoft Academic Search

Mullerian duct anomalies (MDAs) are rare, affecting approximately 1% of all women and about 3% of women with poor reproductive\\u000a outcomes. These congenital anomalies usually result from one of the following categories of abnormalities of the mullerian\\u000a ducts: failure of formation (no development or underdevelopment) or failure of fusion of the mullerian ducts. The American\\u000a Fertility Society (AFS) classification of

Leonardo Marcal; Maria Angela Nothaft; Francisco Coelho; Richard Volpato; Revathy Iyer

277

Coordinated Analysis of Isotopic Anomalies in Antarctic Micrometeorites  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

278

Yields and isomeric ratio of xenon and krypton isotopes from thermal neutron fission of ²³⁵U  

Microsoft Academic Search

The experimental cumulative yields of ⁸⁵Kr\\/sup m\\/, ⁸⁷Kr, ⁸⁸Kr, ¹³³Xe\\/sup g\\/, ¹³⁵Xe\\/sup m\\/, and ¹³⁵Xe\\/sup g\\/ and the independent isomeric yield of ¹³³Xe\\/sup m\\/ in the thermal neutron fission of ²³⁵U have been measured by the gas chromatographic method. The independent yields of ¹³³Xe\\/sup g\\/, ¹³⁵Xe\\/sup m\\/, and ¹³⁵Xe\\/sup g\\/ were deduced with the aid of ¹³³I and ¹³⁵I data.

S. S. Hsu; J. T. Lin; C. M. Yang; Y. W. Yu

1981-01-01

279

Spatio-temporal carbon isotope variation during the Ediacaran period in South China and its impact on bio-evolution  

Microsoft Academic Search

The Ediacaran period is characterized by the extremely negative carbon isotope anomalies and great biotic evolution in Earth\\u000a history. At least four negative carbon isotope anomalies have been reported from this interval in South China so far. It is\\u000a traditionally argued that the isotope variations can be used as a useful tool for global correlation of Ediacaran succession;\\u000a however, more

XinQiang Wang; XiaoYing Shi

2009-01-01

280

MAGSAT anomaly map and continental drift  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

281

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

SciTech Connect

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

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

1993-11-01

282

Krypton absorption in liquid CO (KALC): Campaign II in the Experimental Engineering Section Off-Gas Decontamination facility  

Microsoft Academic Search

Results are presented for the second major campaign for quantifying ; krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing ; off-gas by the KALC process. The Experimental Engineering Section Off-Gas ; Decontamination Facility used in the campaign provides engineering-scale ; experiments with nominal gas and liquid flows of 5 scfm and 0.5 gpm respectively. ; Equilibrium and nonequilibrium mass transfer

R. W. Glass; H. W. R. Beaujean; V. L. Fowler; T. M. Gilliam; D. J. Inman; D. M. Levins

1976-01-01

283

Krypton absorption in liquid CO (KALC): Campaign III in the Experimental Engineering Section Off-Gas Decontamination Facility  

Microsoft Academic Search

Results are presented for the third major campaign for quantifying krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing off-gas by the KALC process. The Experimental Engineering Section Off-Gas Decontamination Facility used in the campaign provides engineering-scale experiments with nominal gas and liquid flows of 5 scfm and 0.5 gpm, respectively. Mass transfer experiments for the CO--O--Kr system are described for

T. M. Gilliam; V. L. Fowler; D. J. Inman

1977-01-01

284

Krypton absorption in liquid CO (KALC): Campaign II in the Experimental Engineering Section Off-Gas Decontamination facility  

Microsoft Academic Search

Results are presented for the second major campaign for quantifying krypton removal from simulated High-Temperature Gas-Cooled Reactor reprocessing off-gas by the KALC process. The Experimental Engineering Section Off-Gas Decontamination Facility used in the campaign provides engineering-scale experiments with nominal gas and liquid flows of 5 scfm and 0.5 gpm respectively. Equilibrium and nonequilibrium mass transfer experiments for the CO--O--Kr system

R. W. Glass; H. W. R. Beaujean; V. L. Fowler; T. M. Gilliam; D. J. Inman; D. M. Levins

1976-01-01

285

Investigation of the combined adsorption of krypton, xenon, and water vapor of the off-gas of atomic power stations  

Microsoft Academic Search

A radiochromatogra phic system of purifying the off-gas from the short-lived krypton, xenon, and iodine nuclides is presently used in Russian atomic power stations and in foreign atomic power stations equipped with the aid of the USSR. The basic elements of the system are filter-adsorbers filled with activated carbon and a drying unit [1-3]. Dynamic adsorption and radioactive decay in

I. E. Nakhutin; D. V. Ochkin; S. A. Tret'yak

1980-01-01

286

Alberta Congenital Anomalies Surveillance System.  

PubMed Central

The Alberta Congenital Anomalies Surveillance System was started in 1966 in response to the thalidomide tragedy earlier in the decade. It was one of four provincial surveillance systems on which the federal government relied for baseline statistics of congenital anomalies. The government now collects data from six provinces and one territory. The Alberta Congenital Anomaly Surveillance System originally depended on three types of notification to the Division of Vital Statistics, Department of Health, Government of Alberta: birth notice and certificates of death and stillbirth; increased sources of ascertainment have greatly improved data quality. We present the data for 1980-86 and compare the prevalence rates of selected anomalies with the rates from three other surveillance systems. Surveillance systems do not guarantee that a new teratogen will be detected, but they are extremely valuable for testing hypotheses regarding causation. At the very least they provide baseline data with which to compare any deviation or trend. For many, if not most, congenital anomalies total prevention is not possible; however, surveillance systems can be used to measure progress in prevention.

Lowry, R B; Thunem, N Y; Anderson-Redick, S

1989-01-01

287

Elastic anomalies of UGe2  

NASA Astrophysics Data System (ADS)

We have performed the ultrasonic sound velocity measurement on the single crystal of UGe2 in the temperature range 4.2-120 K at ambient pressure, focusing attention on the elastic behavior around the characteristic temperature T*?30 K. In the elastic constants for three modes c11, c55 and c66, all modes show the hardening with a kink at the Curie temperature as decreasing temperatures. We found the elastic anomaly related to T* in the longitudinal c11 mode. However, the anomaly around T* is very broad. Therefore, this result may suggest that T* is not related to a phase boundary of some second-order phase transition. On the other hand, no clear anomaly was observed around T* in the transverse c55 and c66 modes.

Kuwahara, K.; Sakai, T.; Kohgi, M.; Haga, Y.; ?nuki, Y.

2007-03-01

288

Lunar and Planetary Science XXXV: Isotopes in Meteorites  

NASA Technical Reports Server (NTRS)

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.

2004-01-01

289

Second order transport from anomalies  

NASA Astrophysics Data System (ADS)

We study parity odd transport at second order in derivative expansion for a non-conformal charged fluid. We see that there are 27 parity odd transport coefficients, of which 12 are non-vanishing in equilibrium. We use the equilibrium partition function method to express 7 of these in terms of the anomaly, shear viscosity, charge diffusivity and thermodynamic functions. The remaining 5 are constrained by 3 relations which also involve the anomaly. We derive Kubo formulae for 2 of the transport coefficients and show these agree with that derived from the equilibrium partition function.

Bhattacharyya, Sayantani; David, Justin R.; Thakur, Somyadip

2014-01-01

290

Analysis of DSN software anomalies  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

291

A primitive plume neon component in MORB: The Shona ridge-anomaly, South Atlantic (5152S)  

Microsoft Academic Search

We report on He and Ne isotopes in basaltic glasses from eight dredge stations occupied over the Shona gravity and topographic anomaly high on the Mid-Atlantic Ridge around 5152S. The results indicate the presence of a primitive, little degassed, 3He-rich mantle component. 3He4He ratios correlate positively with the bathymetric and gravity anomaly, with values ranging from 12.5 to 6.4 times

Manuel Moreira; Thomas Staudacher; Philippe Sarda; Jean-Guy Schilling; Claude Jean Allgre

1995-01-01

292

Isotopic Paleoclimatology  

NASA Astrophysics Data System (ADS)

Paleotemperature scales were calculated by H. C. Urey and others in the 1950s to assess past temperatures, and later work using the stable isotopes of oxygen, hydrogen, and carbon employed standards such as Peedee belemnite (PDB) and Standard Mean Ocean Water (SMOW). Subsequently, subjects as diverse as ice volume and paleotemperatures, oceanic ice and sediment cores, Pleistocene/Holocene climatic changes, and isotope chronostratigraphy extending back to the Precambrian were investigated.

Bowen, R.

293

Measurement of krypton-85 in air at Clonskeagh, Dublin 1993-1997.  

PubMed

The existence of 85Kr in the air is primarily due to the reprocessing of nuclear fuel. The two major reprocessing plants in the western world are at La Hague in France and Sellafield in the UK. Prior to the commissioning of THORP at Sellafield in 1994, a programme to monitor the concentration of 85Kr in air at Clonskeagh, Dublin was commenced. While results for the measurements over the period 1993-1997 indicate that the concentration of 85Kr in the air is increasing, it has not been possible to link any particular measurement result to a krypton release from the Sellafield site. The concentration of 85Kr in air, at the existing level, does not present a significant radiological hazard. Exposure to 85Kr, which is an inert gas, results mainly in small doses to the skin. A mean annual concentration of 1.34 Bq m(-3) was calculated for 1997 which would result in a skin dose of 0.55 microSv for the year to the exposed skin of an individual. PMID:9594112

Howett, D; O'Colmin, M

1998-03-01

294

Theory of attosecond transient-absorption spectroscopy of krypton for overlapping pump and probe pulses  

NASA Astrophysics Data System (ADS)

We present a fully ab initio calculations for attosecond transient absorption spectroscopy of atomic krypton with overlapping pump and probe pulses. Within the time-dependent configuration interaction singles (TDCIS) approach, we describe the pump step (strong-field ionization using a near-infrared pulse) as well as the probe step (resonant electron excitation using an extreme-ultraviolet pulse) from first principles. We extend our TDCIS model and account for the spin-orbit splitting of the occupied orbitals. We discuss the spectral features seen in a recent attosecond transient absorption experiment [A. Wirth , ScienceSCIEAS0036-807510.1126/science.1210268 334, 195 (2011)]. Our results support the concept that the transient absorption signal can be directly related to the instantaneous hole population even during the ionizing pump pulse. Furthermore, we find strong deformations in the absorption lines when the overlap of pump and probe pulses is maximum. These deformations can be described by relative phase shifts in the oscillating ionic dipole. We discuss possible mechanisms contributing to these phase shifts. Our finding suggests that the nonperturbative laser dressing of the entire N-electron wave function is the main contributor.

Pabst, Stefan; Sytcheva, Arina; Moulet, Antoine; Wirth, Adrian; Goulielmakis, Eleftherios; Santra, Robin

2012-12-01

295

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

SciTech Connect

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

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

1991-01-01

296

Multielectron coincidence study of the double Auger decay of 3d-ionized krypton  

SciTech Connect

Multielectron coincidence data for triple ionization of krypton have been recorded above the 3d ionization threshold at two photon energies (140 and 150 eV). Three principal transition pathways have been observed, two involving double Auger transitions from Kr{sup +}, and one involving single Auger transitions from Kr{sup 2+} created by direct single-photon double ionization. The decay of the 3d{sup 9} {sup 2}D{sub 5/2,3/2} states in Kr{sup +} has been analyzed in some detail and is found to be strongly dominated by cascade processes where two electrons with well-defined energies are emitted. The decay paths leading to the 4s{sup 2}4p{sup 3} {sup 4}S, {sup 2}D, and {sup 2}P states of Kr{sup 3+} are analyzed and energies of seven intermediate states in Kr{sup 2+} are given. A preliminary investigation of the decay paths from Kr{sup +} 3d{sup 9}4p{sup 5}nl shake-up states has also been carried out.

Andersson, E.; Hedin, L.; Rubensson, J.-E.; Karlsson, L.; Feifel, R. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Fritzsche, S. [Department of Physics, P.O. Box 3000, Fin-90014 University of Oulu (Finland); GSI Helmholtzzentrum fuer Schwerionenforschung, D-64291 Darmstadt (Germany); Linusson, P. [Department of Physics, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Eland, J. H. D. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom)

2010-10-15

297

Determination of regional esophageal transit in children by means of krypton-8 1m  

SciTech Connect

Radionuclide methods using Tc-99m have been developed in the last few years for the assessment of the esophageal transit. The method is physiologic, easy to perform and giving thus interesting informations concerning the severity of the disease as well as the effect of the applied treatment. In children, however, one is limited by radiation protection considerations, and the results are often of poor quality due to the low count rate. Furthermore, the risk of external contamination and the impossibility of repeating the test constitute significant disadvantages, particularly in young children. These problems are completely avoided by using Krypton-8lm diluted in a glucose solution. For each swallowing about 8 mCi of Kr-8 lm are administered. Sixty one-second frames are recorded and several parameters of regional transit can be extracted in a few minutes, using time activity curves and parametric images. The test is very sensitive in detecting minor regional transit alterations. The reproducibility of the test is good and phenomenons like intercurrent gastro-esophageal reflux or asynergic peristaltic waves can easily be detected. The test has been applied to 52 children, aged 1 week to 19 years, and provided helpful information concerning the localization and the importance of transit abnormalities in caustic and peptic esophagitis, postoperative cases (atresia or antireflux plasty) and in patients with neuromuscular disorders.

Piepsz, A.; Ham, H.R.; Georges, B.; Delaet, M.H.; Cadranel, S.

1984-01-01

298

Mass Independent Isotope Effects and Their Occurrence in Nature  

NASA Astrophysics Data System (ADS)

It has been nearly 20 years since the discovery of a chemically produced mass independent isotope effect by Thiemens and Heidenreich. Subsequent to that time there has been a great deal of progress in developing a physical chemical theory to account for the effect. In particular, recent work by R. Marcus and colleagues has advanced understanding of the effect considerably. There are now many know examples of mass independent isotopic compositions in nature, in fact, with the exception of water, all atmospheric molecules possess mass independent oxygen isotopic compositions. This includes O2, O3, CO2, H2O2, N2O, CO, and atmospheric aerosol sulfate and nitrate. In addition, sulfur in aerosol sulfate is mass independently fractionated and it is now known that the anomalies are preserved in Miocene Volcanic samples, Namibian desert sulfate, Pre-Cambrium sulfate and sulfide (sulfur isotopes), and sulfates from the Antarctic dry valleys. Polar ice samples are also known to preserve the mass independent isotopic anomalies. In addition, secondary minerals from the SNC Martian meteorites possess both sulfur and oxygen isotopic anomalies which are used to understand atmospheric-regolithic coupling. In all cases where mass independent isotopic compositions have been observed, understanding of the particular cycle has been advanced.

Thiemens, M. H.

2002-12-01

299

Mass independent isotope fractionation in ozone  

NASA Astrophysics Data System (ADS)

In the present paper it is proposedwithout a formal physical demonstrationthat the probability to select the lifetime of an activated complex possibly yielding ozone and formed by reactions involving distinguishable isotopes is not equal to the probability to select the lifetime of the same complex but formed by reaction involving indistinguishable isotopes. The origin of this effect is supposed to be linked to the quantum mechanical principle according to which it is not permitted, in a scattering process, to separate the probabilities describing the recoil from the incident particle, if the two particles are indistinguishable. We ascribe the mass independent isotopic fractionation factor to the lifetime ratio of the complexes formed by reactions involving distinguishable and indistinguishable isotopes. In order to illustrate the consequences of this principle, all the accompanying scattering calculations of O+O2?O3*?O+O2 were performed in a thermal gas with oxygen isotopes having the same mass (16 amu). It is numerically shown that the origin of the experimentally observed mass-independent isotope fractionation in ozone is well accounted for within this single assumption. The effect is a priori not restricted to ozone or to oxygen isotopes and may have played a role in several other isotopic anomalies found in meteorites.

Reinhardt, Peter; Robert, Franois

2013-04-01

300

Dispersive Derivation of Triangle Anomaly.  

National Technical Information Service (NTIS)

A straightforward generalization of the results of some previous treatments, in which the Adler-Bell-Jachiw triangle anomaly has been recovered with the help of dispersion relation is presented. The absorptive part of the VVA triangle diagram with the ext...

J. Horejsi

1985-01-01

301

Anomaly-specified virtual dimensionality  

NASA Astrophysics Data System (ADS)

Virtual dimensionality (VD) has received considerable interest where VD is used to estimate the number of spectral distinct signatures, denoted by p. Unfortunately, no specific definition is provided by VD for what a spectrally distinct signature is. As a result, various types of spectral distinct signatures determine different values of VD. There is no one value-fit-all for VD. In order to address this issue this paper presents a new concept, referred to as anomaly-specified VD (AS-VD) which determines the number of anomalies of interest present in the data. Specifically, two types of anomaly detection algorithms are of particular interest, sample covariance matrix K-based anomaly detector developed by Reed and Yu, referred to as K-RXD and sample correlation matrix R-based RXD, referred to as R-RXD. Since K-RXD is only determined by 2nd order statistics compared to R-RXD which is specified by statistics of the first two orders including sample mean as the first order statistics, the values determined by K-RXD and R-RXD will be different. Experiments are conducted in comparison with widely used eigen-based approaches.

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

2013-09-01

302

Lunar rocks and thermal anomalies  

Microsoft Academic Search

Recent microwave and infrared spectral observations of several of the large bright-rayed craters on the moon suggest that the thermal anomalies in these craters are produced by large rocks, boulders, and exposed rock strata. The data for the crater Tycho can be simulated by a surface consisting of 16% loose rocks of I-meter size and 4% exposed rock strata. A

David Buhl

1971-01-01

303

Satellite Elevation Magnetic Anomaly Maps.  

National Technical Information Service (NTIS)

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 curr...

L. W. Braile W. J. Hinze

1982-01-01

304

A Global Magnetic Anomaly MAP.  

National Technical Information Service (NTIS)

A subset of POGO satellite magnetometer data has been formed that is suitable for analysis of crustal magnetic anomalies. Using a thirteenth order field model, fit to these data, magnetic residuals have been calculated over the world to latitude limits of...

R. D. Regan W. M. Davis J. C. Cain

1974-01-01

305

Factor Analysis Based Anomaly Detection  

Microsoft Academic Search

We propose a novel anomaly detection algorithm based on factor analysis and Mahalanobis distance. Factor analysis is used to uncover the latent structure (dimensions) of a set of variables. It reduces attribute space from a larger number of variables to a smaller number of factors. The Mahalanobis distance is used to determine the \\

Ningning Wu; Jing Zhang

2003-01-01

306

Astrometric Solar-System Anomalies  

Microsoft Academic Search

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

John D. Anderson

2009-01-01

307

Numerical anomalies mimicking physical effects  

SciTech Connect

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.

Menikoff, R.

1995-09-01

308

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...

309

Monitoring smartphones for anomaly detection  

Microsoft Academic Search

In this paper we demonstrate how to monitor a smartphone running Symbian OS in order to extract features that de- scribe the state of the device and can be used for anomaly detection. These features are sent to a remote server, be- cause running a complex intrusion detection system (IDS) on this kind of mobile device still is not feasible,

Aubrey-derrick Schmidt; Frank Peters; Florian Lamour; Sahin Albayrak

2008-01-01

310

Archaeological Anomalies in the Bahamas  

Microsoft Academic Search

Controversial claims have been made for the presence of anom- alous underwater archaeological sites in the Bahamas by a number of in- vestigators. The proponents emphasize extraordinary explanations for the anomalies and tend to bypass the scientific journals in favor of popular presentations with little scientific rigor. The skeptics debunk selected claims for some of the sites, do not adequately

DOUGLAS G. RICHARDS

1988-01-01

311

The Palladium Isotopic Composition in Iron Meteorites  

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

312

Ce isotope abundance in chondritic and HED meteorites  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

313

Oxygen Isotopic Compositions of Fulgurites  

NASA Astrophysics Data System (ADS)

Two occurrences of vitreous rocks (fulgurites) that have resulted from the fusion of Etnean lavas, have been ascribed to the result of lightning striking the basalts and melting fresh volcanic rocks [1]. Rapidly quenched melts appear as tubular cavities that preserve the path of the discharge. Glass droplets (D <= 500 micrometers) are always dispersed around the fused lava tube and show several petrographic similarities with chondrules found in ordinary chondrites (presence of melilite, radiating skeletal fassaite, etc). In this process, high temperatures (T>1800 K) have probably been reached during timescales <=10 sec. Because it has been suggested that lightning discharges may have played an important role in the formation of chondrules [2], we have analyzed the oxygen isotope compositions of these fulgurites (our experimental protocol is described elsewhere [3]). The glass (free from any contamination from the unmelted basalt) is 1.5o/oo depleted in ^18O relative to its measured initial isotopic composition (delta^18O = +5.6o/oo); most of the data define a mass-dependent fractionation relationship (i.e. delta^17O = 0.52 x delta^18O). Therefore the data clearly do not reproduce the oxygen isotope anomaly defined for meteorites, which has a slope of 1 in the diagram delta^17O versus delta^18O (i.e. delta^17O = 1.0 x delta^18O). Nevertheless, it should be noted that some glass samples scatter around this canonical value of 0.52 with minor departures from a purely mass-dependent fractionation. If these results are confirmed by additional determinations (now in progress) on the separated glassy droplets, the following conclusions can be proposed: 1) lightning discharges do not yield oxygen isotope anomalies similar to those measured in chondrules and 2) an isotope exchange between hot chondrules and their parent nebular gas--presumably "anomalous" in its oxygen isotopes-- seems difficult to achieve within the duration of the rapid cooling of the melt. This last point is illustrated by the fact that no marked isotope exchange with atmospheric molecular oxygen is detectable. REFERENCES: 1] CLOCCHIATTI R. Eur. J. Mineral., 2, p. 479-494 (1990). 2] WHIPPLE F.L. Science 153, 54-56 (1966). 3] ROBERT F., REJOU-MICHEL A. & JAVOY M. Earth Planet. Sci. Lett. 108, 1-9 (1992).

Robert, F.; Javoy, M.

1992-07-01

314

Ferret Workflow Anomaly Detection System, Final Report.  

National Technical Information Service (NTIS)

The Ferret workflow anomaly detection system project (203-2044) has provided validation and anomaly detection in accredited workflows in secure knowledge management systems through the use of continuous automated audits. A workflow, process, or procedure ...

T. J. Smith S. Bryant

2005-01-01

315

Semiparametric Model for Hyperspectral Anomaly Detection.  

National Technical Information Service (NTIS)

Using hyperspectral (HS) technology, this paper introduces an autonomous scene anomaly detection approach based on the asymptotic behavior of a semiparametric model under a multisample testing and minimum-order statistic scheme. Scene anomaly detection ha...

D. Rosario

2012-01-01

316

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS.  

PubMed

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

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

2013-01-01

317

Stable platinum isotope measurements in presolar nanodiamonds by TEAMS  

PubMed Central

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.

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

2013-01-01

318

Eustachian tube duplication: a unique anomaly.  

PubMed

Very few eustachian tube anomalies have been published in the literature and have consisted of descriptions of diverticula, hypoplasia/aplasia, fistula, or aberrant associated musculature. We present a girl with a novel anomaly consisting of a eustachian tube duplication that originates in the nasopharynx and exits posterior to a microtic and atretic ear. We review the literature on eustachian tube anomalies and also consider the derivation of this anomaly. PMID:24751751

Hoesli, Rebecca Chow; Johnson, Jason; Meyer, Anna; Green, Glenn

2014-07-01

319

Geophysical Anomalies and Earthquake Prediction  

NASA Astrophysics Data System (ADS)

Finding anomalies is easy. Predicting earthquakes convincingly from such anomalies is far from easy. Why? Why have so many beautiful geophysical abnormalities not led to successful prediction strategies? What is earthquake prediction? By my definition it is convincing information that an earthquake of specified size is temporarily much more likely than usual in a specific region for a specified time interval. We know a lot about normal earthquake behavior, including locations where earthquake rates are higher than elsewhere, with estimable rates and size distributions. We know that earthquakes have power law size distributions over large areas, that they cluster in time and space, and that aftershocks follow with power-law dependence on time. These relationships justify prudent protective measures and scientific investigation. Earthquake prediction would justify exceptional temporary measures well beyond those normal prudent actions. Convincing earthquake prediction would result from methods that have demonstrated many successes with few false alarms. Predicting earthquakes convincingly is difficult for several profound reasons. First, earthquakes start in tiny volumes at inaccessible depth. The power law size dependence means that tiny unobservable ones are frequent almost everywhere and occasionally grow to larger size. Thus prediction of important earthquakes is not about nucleation, but about identifying the conditions for growth. Second, earthquakes are complex. They derive their energy from stress, which is perniciously hard to estimate or model because it is nearly singular at the margins of cracks and faults. Physical properties vary from place to place, so the preparatory processes certainly vary as well. Thus establishing the needed track record for validation is very difficult, especially for large events with immense interval times in any one location. Third, the anomalies are generally complex as well. Electromagnetic anomalies in particular require some understanding of their sources and the physical properties of the crust, which also vary from place to place and time to time. Anomalies are not necessarily due to stress or earthquake preparation, and separating the extraneous ones is a problem as daunting as understanding earthquake behavior itself. Fourth, the associations presented between anomalies and earthquakes are generally based on selected data. Validating a proposed association requires complete data on the earthquake record and the geophysical measurements over a large area and time, followed by prospective testing which allows no adjustment of parameters, criteria, etc. The Collaboratory for Study of Earthquake Predictability (CSEP) is dedicated to providing such prospective testing. Any serious proposal for prediction research should deal with the problems above, and anticipate the huge investment in time required to test hypotheses.

Jackson, D. D.

2008-12-01

320

Anomaly Resolution in the International Space Station  

NASA Technical Reports Server (NTRS)

Topics include post flight 2A status, groundrules, anomaly resolution, Early Communications Subsystem anomaly and resolution, Logistics and Maintenance plan, case for obscuration, case for electrical short, and manual fault isolation, and post mission analysis. Photographs from flight 2A.1 are used to illustrate anomalies.

Evans, William A.

2000-01-01

321

Bouger Gravity Anomaly Map of South America.  

National Technical Information Service (NTIS)

The Bouguer Anomaly Map of South America is a contoured representation of one degree x one degree mean Bouguer gravity anomaly values. Some of these mean anomaly values are computed directly using observed gravity data held by the DOD Gravity Library. Oth...

C. W. Beierle G. L. Breville J. R. Sanders J. T. Voss L. E. Wilcox

1973-01-01

322

Lunar Bouguer gravity anomalies - Imbrian age craters  

Microsoft Academic Search

The Bouguer gravity of mass anomalies associated with four Imbrian age craters, analyzed in the present paper, are found to differ considerably from the values of the mass anomalies associated with some young lunar craters. Of the Imbrian age craters, only Piccolomini exhibits a negative gravity anomaly (i.e., a low density region) which is characteristic of the young craters studied.

J. Dvorak; R. J. Phillips

1978-01-01

323

Local gravity anomalies produced by dislocation sources  

Microsoft Academic Search

Rundle (1979) and Walsh and Rice (1979) have shown that the change in the vertical component of gravity is proportional to uplift for a spherical source of dilation and for slip on an infinitely long dip-slip fault. In the first case, no free air gravity anomaly is produced and in the second case no Bouguer gravity anomaly. Gravity anomalies due

J. C. Savage

1984-01-01

324

Limb Body Wall Complex: A Rare Anomaly  

PubMed Central

We present autopsy findings of a case of limb body wall complex (LBWC). The fetus had encephalocele, genitourinary agenesis, skeletal anomalies and body wall defects. The rare finding in our case is the occurrence of both cranial and urogenital anomalies. The presence of complex anomalies in this fetus, supports embryonal dysplasia theory of pathogenesis for LBWC.

Chikkannaiah, Panduranga; Dhumale, Hema; Kangle, Ranjit; Shekar, Rosini

2013-01-01

325

Limb body wall complex: a rare anomaly.  

PubMed

We present autopsy findings of a case of limb body wall complex (LBWC). The fetus had encephalocele, genitourinary agenesis, skeletal anomalies and body wall defects. The rare finding in our case is the occurrence of both cranial and urogenital anomalies. The presence of complex anomalies in this fetus, supports embryonal dysplasia theory of pathogenesis for LBWC. PMID:24014975

Chikkannaiah, Panduranga; Dhumale, Hema; Kangle, Ranjit; Shekar, Rosini

2013-01-01

326

The Scatter in Tropical Average Precipitation Anomalies  

Microsoft Academic Search

Tropical mean precipitation anomalies ^P9& for 3-month averages appear quite scattered in relation to tropical average sea surface temperature (SST) anomalies ^& , based on examination of a number of observational T9 s datasets and of atmospheric general circulation model (GCM) results. Even though SST is locally important for determining precipitation, for a given warm SST anomaly, the tropical average

HUI S UA; NDJ. DAVID NEELIN

2003-01-01

327

Spectrum of anomalies in Fanconi anaemia  

Microsoft Academic Search

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

A Glanz; F C Fraser

1982-01-01

328

Developmental venous anomaly: MR and angiographic features.  

PubMed

Developmental venous anomaly (DVA) is probably the most common anomaly of the intracranial vasculature. DVAs consist of multiple, radially oriented dilated medullary veins that converge into a transcerebral vein. We describe the imaging findings of this vascular anomaly in different patients and the role of different imaging modalities. PMID:24765765

Faure, M; Voormolen, M; Van der Zijden, T; Parizel, P M

2014-01-01

329

Diagnosing network-wide traffic anomalies  

Microsoft Academic Search

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

Anukool Lakhina; Mark Crovella; Christophe Diot

2004-01-01

330

A signal analysis of network traffic anomalies  

Microsoft Academic Search

Identifying anomalies rapidly and accurately is critical to the efficient operation of large computer networks. Accurately characterizing important classes of anomalies greatly facilitates their identification; however, the subtleties and complexities of anomalous traffic can easily confound this process. In this paper we report results of signal analysis of four classes of network traffic anomalies: outages, flash crowds, attacks and measurement

Paul Barford; Jeffery Kline; David Plonka; Amos Ron

2002-01-01

331

Structural, chemical, and isotopic microanalytical investigations of graphite from supernovae  

Microsoft Academic Search

We report the results of coordinated ion microprobe and transmission electron microscope (TEM) studies of presolar graphites from the KE3 separate (1.651.72 g\\/cm3) of the Murchison CM2 meteorite. Isotopic analysis of individual graphites (112 ?m) with the ion microprobe shows many to have large 18O excesses combined with large silicon isotopic anomalies, indicative of a supernova (SN) origin. Transmission electron

T. Kevin Croat; Thomas Bernatowicz; Sachiko Amari; Scott Messenger; FRANK J. STADERMANN

2003-01-01

332

Ni Isotopes in the Early Solar System: an Overview  

Microsoft Academic Search

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

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

2006-01-01

333

Anomaly clustering in hyperspectral images  

NASA Astrophysics Data System (ADS)

The topological anomaly detection algorithm (TAD) differs from other anomaly detection algorithms in that it uses a topological/graph-theoretic model for the image background instead of modeling the image with a Gaussian normal distribution. In the construction of the model, TAD produces a hard threshold separating anomalous pixels from background in the image. We build on this feature of TAD by extending the algorithm so that it gives a measure of the number of anomalous objects, rather than the number of anomalous pixels, in a hyperspectral image. This is done by identifying, and integrating, clusters of anomalous pixels via a graph theoretical method combining spatial and spectral information. The method is applied to a cluttered HyMap image and combines small groups of pixels containing like materials, such as those corresponding to rooftops and cars, into individual clusters. This improves visualization and interpretation of objects.

Doster, Timothy J.; Ross, David S.; Messinger, David W.; Basener, William F.

2009-05-01

334

Studies on the photochemical and thermal dissociation synthesis of krypton difluoride  

SciTech Connect

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

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

1993-08-01

335

Anomalies and Discrete Chiral Symmetries  

SciTech Connect

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.

Creutz, M.

2009-09-07

336

Astrometric Solar-System Anomalies  

NASA Astrophysics Data System (ADS)

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

Anderson, John D.

2009-05-01

337

Cloacal anomaly with bladder tumor  

PubMed Central

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.

Seth, Amlesh; Ram, Ishwar

2013-01-01

338

Surgical treatment of cloacal anomalies  

Microsoft Academic Search

From 19891998 14 patients were treated with cloacal anomalies: 5 typical cloacas (PC), 5 posterior cloacas, and 4 cloacal\\u000a exstrophies (CE); 12 underwent surgery. Four typical cloacas were resolved with posterior sagittal anorectovagino-urethroplasty\\u000a (PSARVUP), whereas in the 5th total urogenital mobilization (TUM) was used. Three PCs were managed with transanorectal TUM\\u000a and 2 with anterior TUM without opening the anal

Z. D. Krstic; M. Lukac; R. Lukac; Z. Smoljanic; V. Vukadinovic; D. Varinac

2001-01-01

339

Monitoring Smartphones for Anomaly Detection  

Microsoft Academic Search

In this paper we demonstrate how to monitor a smartphone running Symbian operating system and Windows Mobile in order to extract\\u000a features for anomaly detection. These features are sent to a remote server because running a complex intrusion detection system\\u000a on this kind of mobile device still is not feasible due to capability and hardware limitations. We give examples on

Aubrey-derrick Schmidt; Frank Peters; Florian Lamour; Christian Scheel; Seyit Ahmet amtepe; Sahin Albayrak

2009-01-01

340

Imaging of mllerian duct anomalies.  

PubMed

The mllerian ducts are paired embryologic structures that undergo fusion and resorption in utero to give rise to the uterus, fallopian tubes, cervix, and upper two-thirds of the vagina. Interruption of normal development of the mllerian ducts can result in formation of mllerian duct anomalies (MDAs). MDAs are a broad and complex spectrum of abnormalities that are often associated with primary amenorrhea, infertility, obstetric complications, and endometriosis. MDAs are commonly associated with renal and other anomalies; thus, identification of both kidneys is important. However, MDAs are not associated with ovarian anomalies. Hysterosalpingography (HSG) is routinely used in evaluation of infertility. Because a key component of MDA characterization is the external uterine fundal contour, HSG is limited for this purpose. Patients suspected of having an MDA are often initially referred for pelvic ultrasonography (US). Magnetic resonance (MR) imaging is typically reserved for complex or indeterminate cases. MR imaging is the imaging standard of reference because it is noninvasive, does not involve ionizing radiation, has multiplanar capability, allows excellent soft-tissue characterization, and permits a greater field of interrogation than does US. Use of MR imaging for evaluation of MDAs reduces the number of invasive procedures and related costs by guiding management decisions. PMID:23065173

Behr, Spencer C; Courtier, Jesse L; Qayyum, Aliya

2012-10-01

341

Columbus Payloads Flow Rate Anomalies  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

342

On the role of the II(1/2g) state in spontaneous dissociation of krypton and xenon dimer ions  

NASA Astrophysics Data System (ADS)

We have measured kinetic-energy-release distributions (KERD) for spontaneous dissociation of electronically excited dimer ions of krypton and xenon, formed by electron impact ionization of neutral precursors. The data cannot be reconciled by decay of the strongly bound II(1/2u) state that successfully explains dissociation of Ne2+ and Ar2+. Instead, the KERD is dominated by contributions from the weakly bound II(1/2g) state that has so far escaped a convincing experimental characterization. The present data can be utilized to assess the accuracy of ab initio potential energy curves of this state.

Fedor, J.; Echt, O.; G?uch, K.; Matt-Leubner, S.; Scheier, P.; Mrk, T. D.

2007-04-01

343

Magsat scalar anomaly distribution - The global perspective  

NASA Technical Reports Server (NTRS)

It is established that geographic coincidences exist between high-altitude Magsat scalar anomalies and major geologic and tectonic structures, with oceanic abyssal plains overlain by negative anomalies agreeing well in spatial extent and position and submarine platforms lying beneath positive scalar anomalies. In addition, geographic coincidence is found in the continents between many high-latitude positive anomalies and shields and cratons in North America, Eurasia and Australia. While these correlations are qualitative, they serve to identify regions for detailed study. The global distribution of anomalies provides a basis for comparative study which will be enhanced when reduced-to-pole versions of the Magsat data become available.

Frey, H.

1982-01-01

344

Regularization schemes and the multiplicative anomaly  

NASA Astrophysics Data System (ADS)

Elizalde, Vanzo, and Zerbini have shown that the effective action of two free Euclidean scalar fields in flat space contains a `multiplicative anomaly' when ?-function regularization is used. This is related to the Wodzicki residue. I show that there is no anomaly when using a wide range of other regularization schemes and that the anomaly can be removed by an unusual choice of renormalization scales. I define new types of anomalies and show that they have similar properties. Thus multiplicative anomalies encode no novel physics. They merely illustrate some dangerous aspects of ?-function and Schwinger proper time regularization schemes.

Evans, T. S.

1999-06-01

345

Satellite GN and C Anomaly Trends  

NASA Technical Reports Server (NTRS)

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.

Robertson, Brent; Stoneking, Eric

2003-01-01

346

Trends in environmentally induced spacecraft anomalies  

NASA Technical Reports Server (NTRS)

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.

Wilkinson, Daniel C.

1989-01-01

347

Anomaly detection and diagnosis in Grid environments.  

SciTech Connect

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

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

2007-01-01

348

Congenital anomalies in the baboon (Papio spp.)  

PubMed Central

Background A comprehensive survey of the prevalence of congenital anomalies in baboons has not been previously reported. We report the congenital anomalies observed over a 26-year period in a large captive baboon colony. Methods A computer search was performed for all baboon congenital anomalies identified at necropsy and recorded on necropsy submissions. Results We identified 198 congenital anomalies in 166 baboons from 9,972 necropsies (1.66% of total necropsies). The nervous, urogenital, musculoskeletal, and cardiovascular systems were most commonly affected. The most common organs affected were the brain, bone, heart, testicle, kidney, penis, aorta, and skeletal muscle. The most frequent congenital anomalies were blindness, seizures, and hydrocephalus. Conclusions The baboon has an overall frequency of congenital anomalies similar to humans and other nonhuman primates. Although the most frequently affected systems are similar, congenital anomalies involving the digestive system appear to be less common in the baboon.

Fox, Benjamin; Owston, Michael A.; Kumar, Shyamesh; Dick, Edward J.

2011-01-01

349

Osmium isotope evidence for an s-process carrier in primitive chondrites.  

PubMed

Osmium extracted from unequilibrated bulk chondrites has isotope anomalies consistent with an insoluble s-process carrier, termed Os(i) here. Osmium from metamorphosed bulk chondrites does not have isotope anomalies, implying that the Os(i) carrier was destroyed by metamorphism. The isotopic homogeneity of metamorphosed bulk chondrites is consistent with extremely effective mixing of presolar grains from varied sources in the nebula. Osmium in the Os(i) carrier is likely from nucleosynthetic sites with a neutron density about two to four times as high as that of the average solar s-process Os. PMID:16109878

Brandon, A D; Humayun, M; Puchtel, I S; Leya, I; Zolensky, M

2005-08-19

350

Size estimation of cylindrical uniform pores on solid surfaces by adsorption of n-butylbenzene vapor and krypton gas  

SciTech Connect

The sizes of cylindrical uniform pores on solid surfaces were estimated by experiments on adsorption of n-butylbenzene vapor and krypton gas with anodized aluminum and silicon plates as samples. All adsorption isotherms had significant hysteresis loops due to capillary condensation, which showed the apparent pore volume of the samples. The adsorption isotherm of krypton used in the BET method gave total surface area, including the inside surface area of pores, and the isotherm of n-butylbenzene vapor gave the outer surface area excluding the inside pore surface area using the ''gradient method.'' Thus, uniform pore size was calculated from the apparent pore volume and the total inside area of the pores. Pore sizes agreed well with those expected under anodizing conditions for the aluminum samples. The adsorptive pressure at which capillary condensation began or was released from the pore was consistent with the capillary-condensation pressure calculated by the Kelvin equation. A significant finding was that capillary condensation ended, for cylindrical pores closed at one end on anodized aluminum and silicon samples, at a relative pressure corresponding to the square root of the initial relative pressure of capillary condensation. It was found that uniform pore size could be estimated at from 150 to 1.7 nm, using adsorption/desorption hysteresis of the adsorption isotherms of n-butylbenzene vapor.

Nonaka, A. (Univ. of Tsukuba (Japan). Inst. of Applied Physics)

1994-10-01

351

Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams  

SciTech Connect

The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

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

2013-10-01

352

Novel Sorbent Development and Evaluation for the Capture of Krypton and Xenon from Nuclear Fuel Reprocessing Off-Gas Streams  

SciTech Connect

The release of volatile radionuclides generated during Used Nuclear Fuel reprocessing in the US will most certainly need to be controlled to meet US regulatory emission limits. A US DOE sponsored Off-Gas Sigma Team has been tasked with a multi-lab collaborative research and development effort to investigate and evaluate emissions and immobilization control technologies for the volatile radioactive species generated from commercial Used Nuclear Fuel (UNF) Reprocessing. Physical Adsorption technology is a simpler and potential economical alternative to cryogenic distillation processes that can be used for the capture of krypton and xenon and has resulted in a novel composite sorbent development procedure using synthesized mordenite as the active material. Utilizing the sorbent development procedure, INL sigma team members have developed two composite sorbents that have been evaluated for krypton and xenon capacities at ambient and 191 K temperature using numerous test gas compositions. Adsorption isotherms have been generated to predict equilibration and maximum capacities enabling modeling to support process equipment scale-up.

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

2013-09-01

353

Survival of children born with congenital anomalies  

PubMed Central

Aim: To describe the survival to age 5 years of children born with congenital anomalies. Methods: Between 1980 and 1997, 6153 live born cases of congenital anomaly were diagnosed and registered by the population based Glasgow Register of Congenital Anomalies. They were retrospectively followed to assess their survival status from birth up to the age of 5 years. Results: The proportions of all live born infants with congenital anomalies surviving to the end of the first week, and first and fifth year were 94%, 89%, and 88%, respectively. Survival to age 5, the end point of follow up, was significantly poorer for infants with chromosomal anomalies (48%) compared to neural tube defects (72%), respiratory system anomalies (74%), congenital heart disease (75%), nervous system anomalies (77%), and Down's syndrome (84%). Conclusion: Although almost 90% of all live born infants with congenital anomalies survive to 5 years, there are notable variations in survival between anomaly types. Our findings should be useful for both clinicians and geneticists to assess the prognosis of congenital anomalies. This information is also important for affected families and for the planning of health care needs for this high risk population.

Dastgiri, S; Gilmour, W; Stone, D

2003-01-01

354

Congenital Stapes Anomalies with Normal Eardrum  

PubMed Central

Objectives A non-progressive and conductive hearing loss with normal eardrum, but no history of trauma and infection, is highly suggestive of a congenital ossicular malformation. Among ossicular anomalies, stapes anomaly is the most common. The purpose of this study is to describe patterns of stapes anomaly and to analyze its surgical outcome with special reference to its patterns. Methods We conducted a retrospective case review. The subjects comprised 66 patients (76 ears) who were decisively confirmed by the exploratory tympanotomy as congenital stapes anomalies without any anomalies of the tympanic membrane and external auditory canal. The preoperative and postoperative audiological findings, temporal bone computed tomography scan, and operative findings were analyzed. Results There were 16 anomalous patterns of stapes among which footplate fixation was the most common anomaly. These 16 patterns were classified into 4 types according to the status of stapes footplate. Successful hearing gain was achieved in 51 out of 76 ears (67.1%) after surgical treatment. Conclusion Footplate fixation was usually bilateral, whereas stapes anomalies associated with other ossicular anomaly were usually unilateral. The success of the surgical treatment of stapes anomaly might depend on its developmental status of the footplate. Stapes anomalies were detected without any fixed patterns, therefore, it is quite possible to detect a large variety of patterns in future.

Park, Hun Yi; Han, Dong Hee; Lee, Jong Bin; Han, Nam Soo; Choung, Yun-Hoon

2009-01-01

355

Prenatal ultrasound and urological anomalies.  

PubMed

Prenatal ultrasound is an integral part of caring for pregnant women in the United States. Although surprisingly few data exist to support the clinical benefit of screening ultrasound during pregnancy, its use continues to rise. Urologic anomalies are among the most commonly identified, with overall detection sensitivity approaching 90%. Prenatal hydronephrosis is the most frequently identified finding and predicting postnatal pathology based on its presence can be difficult. As the degree of fetal hydronephrosis increases so does the risk of true urinary tract pathology. Diagnoses that require more urgent care include causes of lower urinary tract obstruction and bladder and cloacal exstrophy. PMID:22857826

Clayton, Douglass B; Brock, John W

2012-08-01

356

Congenital Anomalies of the Breast  

PubMed Central

Poland syndrome is a combination of chest wall deformity and absent or hypoplastic pectoralis muscle and breast associated with shortening and brachysyndactyly of the upper limb. Clinical presentation varies widely; therefore, reconstructive procedures have to be adapted to the deformity, ranging from chest wall stabilization or augmentation, dynamic muscle transfer, nipple and areola repositioning, and breast augmentation using prosthesis or autologous tissue transfer. Other congenital breast anomalies include supernumerary nipple and areola (polythelia) and breast (polymastia), which can generally be found on the embryonic mammary ridge. Absence of the nipple, areola (athelia), or the breast tissue (amastia) is less frequent.

Caouette-Laberge, Louise; Borsuk, Daniel

2013-01-01

357

Hot Flow Anomalies at Venus  

NASA Technical Reports Server (NTRS)

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.

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

358

FE and MG Isotopic Analyses of Isotopically Unusual Presolar Silicate Grains  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

359

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)

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 young researchers at the moment because of the lack of consistency and the lack of understanding between different groups. This project seeks to alleviate this.

Kaiser, Jan; Angert, Alon; Bergquist, Bridget; Brand, Willi; Ono, Shuhei; Rckmann, Thomas; Savarino, Jol

2014-05-01

360

Isotope fractionation  

NASA Astrophysics Data System (ADS)

A rash of new controversy has emerged around the subject of mass-independent isotope fractionation effects, particularly in the case of the oxygen isotopes. To be sure, the controversy has been around for awhile, but it has been given new impetus by the results of a recent study by Mark H. Thiemens and John E. Heidenreich III of the University of California, San Diego (Science, March 4, 1983).Gustav Arrhenius has been trying to convince the planetary science community that chemical effects in isotope fractionation processes could explain observations in meteorites that appear to be outside of the traditionally understood mass-dependent fractionations (G. Arrhenius, J . L. McCrumb, and N. F. Friedman, Astrophys. Space Sci, 65, 297, 1974). Robert Clayton had made the basic observations of oxygen in carbonaceous chondrites that the slope of the ?17 versus ?18 line was 1 instead of the slope of characteristic of terrestrial rocks and lunar samples (Ann. Rev. Nucl. Part. Sci., 28, 501, 1978). The mass-independent effects were ascribed to the apparent contribution of an ancient presolar system component of O16.

Bell, Peter M.

361

Multiphoton Ionization of Krypton and Xenon: An Investigation of the Autoionizing Region Between the P/sub 1/2/ and P/sub 3/2/ Thresholds.  

National Technical Information Service (NTIS)

Four- and five-photon ionization of krypton has been investigated in the autoionizing region between the P/sub 1/2/ and P/sub 3/2/ ionization limits with a high-powered pulsed tunable dye laser and a static ionization cell. For the four-photon case, the n...

J. A. D. Stockdale, T. Efthimiopoulos, C. Fotakis, P. R. Blazewicz

1986-01-01

362

Anomalies associated with Axenfeld-Rieger syndrome  

Microsoft Academic Search

Background: To detect the associated anomalies in patients with Axenfeld-Rieger syndrome is clinically important, because\\u000a early treatment for such anomalies is crucial to both visual and systemic development. This study was conducted to clarify\\u000a the associated anomalies in the syndrome.? Methods: We evaluated 21 patients with Axenfeld-Rieger syndrome encountered at\\u000a Nagoya City University Hospital over a 16-year period. Patients who

Hironori Ozeki; Shoichiro Shirai; Kozo Ikeda; Yuichiro Ogura

1999-01-01

363

Pancake kidney: A rare developmental anomaly  

PubMed Central

There are many developmental anomalies of the kidney. Pancake kidney is one of the rarest types of renal ectopia. We report a case of pancake kidney which was detected incidentally while treating a female patient for a urinary tract infection. Although urinary system anomalies often coexist with malformations of other organs and systems, no associated anomalies could be detected in this case. Pancake kidney is usually managed by surgery, but this case was managed conservatively without any complication.

Tiwari, Alok Kumar; Choudhary, Anil Kumar; Khowal, Hemant; Chaudhary, Poras; Arora, Mohinder. P.

2014-01-01

364

Bouguer anomaly map of New Zealand  

Microsoft Academic Search

The Bouguer map of New Zealand exhibits two major negative gravity anomalies. The Rangitikei-Waiapu Anomaly, which intersects tne axial ranges of the North Island, indicates a crustal downwarp which is not in isostatic equilibrium. This anomaly is closely parallel to the zone of intense seismicity, to the Taupo-White Island volcanic belt, to the Kaimanawa-Huiarau-Raukumara Ranges, to the thick Upper Pliocene

E. I. Robertson; W. I. Reilly

1958-01-01

365

The Mars Rover Spirit FLASH anomaly  

NASA Technical Reports Server (NTRS)

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.

Reeves, Glenn E.; Neilson, Tracy C.

2005-01-01

366

Uhl's anomaly in a domestic shorthair cat.  

PubMed

A 2-year-old, neutered male, domestic shorthair cat was presented for investigation of dyspnea and episodic weakness. Clinical and ultrasonographic features were consistent with right ventricular cardiomyopathy. Pathological findings documented Uhl's anomaly. Although rare, Uhl's anomaly should be a differential diagnosis for cats with right-sided congestive heart failure. In particular, Uhl's anomaly could be misdiagnosed as arrhythmogenic right ventricular cardiomyopathy due to the similarity of clinical and echocardiographic findings. PMID:21041339

Quintavalla, Cecilia; Bossolini, Elena; Rubini, Giuseppe; Tursi, Massimiliano

2010-01-01

367

Chiral and gravitational anomalies in any dimension  

SciTech Connect

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

Delbourgo, R.; Matsuki, T.

1985-06-01

368

The magnetic anomaly of the Ivreazone  

NASA Technical Reports Server (NTRS)

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.

Albert, G.

1979-01-01

369

Dysmenorrhea due to a rare mllerian anomaly.  

PubMed

Mllerian duct anomalies may produce reproductive failure like abortion and preterm birth, or obstetric problems like malpresentation, retained placenta, etc., or they may be asymptomatic. Unicornuate uterus with a noncommunicating functional rudimentary horn is a type of mllerian anomaly that results in obstruction to menstrual blood flow, leading to endometriosis and dysmenorrhea. Though the majority of cases of dysmenorrhea in adolescents are primary in nature and require only reassurance and symptomatic management, it is important to be aware of rare causes such as mllerian anomalies so that these cases can be properly managed. Hence, we present this case report, with interesting illustrations, so as to increase awareness regarding these anomalies. PMID:22037089

Agarwal, M; Das, A; Singh, A S

2011-01-01

370

Initial scalar magnetic anomaly map from Magsat  

NASA Technical Reports Server (NTRS)

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.

Langel, R. A.; Phillips, J. D.; Horner, R. J.

1982-01-01

371

Anomaly-free sets of fermions  

SciTech Connect

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

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

2005-10-01

372

Pristine extraterrestrial material with unprecedented nitrogen isotopic variation  

PubMed Central

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

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

2009-01-01

373

Pristine extraterrestrial material with unprecedented nitrogen isotopic variation.  

PubMed

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

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

2009-06-30

374

Absolute measurements of isotope amount ratios on gases  

NASA Astrophysics Data System (ADS)

The power of the theoretical formalisms based on concepts from kinetic gas theory described in Part I of this series, is demonstrated in isotope measurement results obtained for three different gases: CO2, SiF4 gas highly enriched in the 28Si isotope and a high purity neon gas of natural isotopic composition. The measurement procedure as described in this paper enables to detect various (small) anomalies in the gas mass spectrometer during the ion current measurements thus creating the opportunity to correct for themE Using these concepts which govern the isotope fractionation of the gas in the mass spectrometer and performing a calibration by means of synthesized values for isotope amount ratios, SI traceable values in terms of the derived measurement unit mol/mol can be obtained.

Valkiers, S.; Varlam, M.; Berglund, M.; Taylor, P.; Gonfiantini, R.; de Bivre, P.

2008-01-01

375

Spectral Methods for Magnetic Anomalies  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

376

MAWILab: combining diverse anomaly detectors for automated anomaly labeling and performance benchmarking  

Microsoft Academic Search

Evaluating anomaly detectors is a crucial task in traffic monitoring made particularly difficult due to the lack of ground truth. The goal of the present article is to assist researchers in the evaluation of detectors by providing them with labeled anomaly traffic traces. We aim at automatically finding anomalies in the MAWI archive using a new methodology that combines different

Romain Fontugne; Pierre Borgnat; Patrice Abry; Kensuke Fukuda

2010-01-01

377

Oculoauriculovertebral spectrum and cerebral anomalies.  

PubMed Central

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

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

378

One Million Years of Groundwater History Revealed by Atom Trap Trace Analysis of Krypton81  

Microsoft Academic Search

The ultra-trace detection of the long-lived isotope ^81Kr (t_1\\/2=230 ky) with Atom Trap Trace Analysis (ATTA) has been applied for the first time to determine the age of ancient groundwater. ATTA, a highly selective atom-counting method based on laser manipulation of neutral atoms, can now be used routinely to determine ^81Kr\\/Kr at the natural level of 10-12 and below [1].

Peter Mueller

2004-01-01

379

Resolving Bouguer anomalies in continentsA new approach  

Microsoft Academic Search

Nature of anomalies present in free air gravity and their corresponding anomalies in Bouguer gravity over continents are analysed in light of isostatic compensation of topographic masses. These anomalies are classified into regional, residual and local and criteria are evolved to identify them. The regional anomaly corresponds to regional topography that is compensated. The local anomaly is related to local

D. V. Subba Rao

1996-01-01

380

Resolving Bouguer anomalies in continents-A new approach  

Microsoft Academic Search

Nature of anomalies present in free air gravity and their corresponding anomalies in Bouguer gravity over continents are analyzed in light of isostatic compensation of topographic masses. These anomalies are classified into regional, residual and local and criteria are evolved to identify them. The regional anomaly corresponds to regional topography that is compensated. The local anomaly is related to local

D. V. Subba Rao

1996-01-01

381

Anomaly Detection over Noisy Data using Learned Probability Distributions  

Microsoft Academic Search

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

Eleazar Eskin

2000-01-01

382

Bouguer Gravity Anomaly Map of Africa.  

National Technical Information Service (NTIS)

A Bouguer Gravity Anomaly Map of Africa has been compiled using only terrestrial data. The map is a contoured representation of one degree x one degree mean anomaly values. Some one degree x one degree values are computed by conventional or statistical me...

J. R. Sanders L. E. Wilcox R. L. Slettene R. S. Blouse

1973-01-01

383

Local Gravity Anomalies Produced by Dislocation Sources  

Microsoft Academic Search

Gravity anomalies due to other dislocation sources in three dimensions are as follows: For strike-slip faulting the ratio of the gravity change to uplift depends upon position; however, the gravity change contours are roughly similar to those corresponding to a zero free air gravity anomaly. Nor is the ratio constantfor dip-slip faulting except for the two special cases of dip

J. C. Savage

1984-01-01

384

A REINTRODUCTION TO ANOMALIES OF CRITICALITY  

Microsoft Academic Search

In 1974, a small innocuous document was submitted to the American Nuclear Society's Criticality Safety Division for publication that would have lasting impacts on this nuclear field The author was Duane Clayton, manager of the Battelle Pacific Northwest National Laboratory's Critical Mass Lab, the world's preeminent reactor critical experimenter with plutonium solutions. The document was entitled, 'Anomalies of Criticality'. 'Anomalies...'

PUIGH RJ

2009-01-01

385

Trends in Environmentally Induced Spacecraft Anomalies.  

National Technical Information Service (NTIS)

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 spec...

D. C. Wilkinson

1989-01-01

386

Anomaly Detection for Cybersecurity of the Substations  

Microsoft Academic Search

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

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

2011-01-01

387

On Gravity Prediction Using Mean Anomalies.  

National Technical Information Service (NTIS)

The efficiency of prediction of mean gravity anomalies for areas of 1 degree x 1 degree, 2 degree x 2 degree, 5 degree x 5 degree, and 10 degree x 10 degree from known mean anomalies is studied. The least standard prediction error is found to be about 1/2...

E. Groten

1965-01-01

388

American depository receipts and calendar anomalies  

Microsoft Academic Search

This is the first study to examine the presence of calendar anomalies in American Depository Receipts (ADR) returns. Existing literature has documented several calendar anomalies in US and foreign markets. ADRs, however, represent a unique class of securities because they represent the ownership of stock of a foreign firm, but they are traded on US markets. We use the Standard

Janie Casello Bouges; Ravi Jain; Yash R. Puri

2009-01-01

389

Fermi Surface of Lead from Kohn Anomalies  

Microsoft Academic Search

The dispersion relations for phonons in lead determined by neutron spectrometry exhibit a large number of Kohn anomalies, which may all be related to the Fermi surface in a consistent manner by considering both electron transitions diametrically across the Fermi surface and nondiametral transitions between points with parallel tangent planes. Factors affecting the size and shape of anomalies are reviewed.

R. Stedman; L. Almqvist; G. Nilsson; G. Raunio

1967-01-01

390

Mining anomalies using traffic feature distributions  

Microsoft Academic Search

The increasing practicality of large-scale flow capture makes it possible to conceive of traffic analysis methods that detect and identify a large and diverse set of anomalies. However the challenge of effectively analyzing this massive data source for anomaly diagnosis is as yet unmet. We argue that the distributions of packet features (IP addresses and ports) observed in flow traces

Anukool Lakhina; Mark Crovella; Christophe Diot

2005-01-01

391

Information-Theoretic Measures for Anomaly Detection  

Microsoft Academic Search

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

Wenke Lee; Dong Xiang

2001-01-01

392

Understanding Anomalies to Extract Vacuum Energy  

Microsoft Academic Search

Recent Russian literature contains some interesting speculations of potentially wide applicability regarding the physical vacuum. These investigations examined and applied a theory to various anomalies to try and understand what these events may represent. Data were collected by Dmitriev to quantify these events and identify commonalties that indicate the anomalies might have a natural origin. Dyatlov created theories on the

P. A. Murad

2004-01-01

393

Anomalies of Nuclear Criticality, Revision 6  

SciTech Connect

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.

Clayton, E. D.; Prichard, Andrew W.; Durst, Bonita E.; Erickson, David; Puigh, Raymond J.

2010-02-19

394

Order of magnitude enhancement in neutron emission with deuterium-krypton admixture operation in miniature plasma focus device  

SciTech Connect

The effect of varied concentrations of deuterium-krypton (D{sub 2}-Kr) admixture on the neutron emission of a fast miniature plasma focus device was investigated. It was found that a judicious concentration of Kr in D{sub 2} can significantly enhance the neutron yield. The maximum average neutron yield of (1{+-}0.27)x10{sup 4} n/shot for pure D{sub 2} filling at 3 mbars was enhanced to (3.14{+-}0.4)x10{sup 5} n/shot with D{sub 2}+2% Kr admixture operation, which represents a >30-fold increase. More than an order of magnitude enhancement in the average neutron yield was observed over the broader operating range of 1-4 mbars for D{sub 2}+2% Kr and D{sub 2}+5% Kr admixtures.

Verma, Rishi; Lee, P.; Lee, S.; Springham, S. V.; Tan, T. L.; Rawat, R. S. [NSSE, National Institute of Education, Nanyang Technological University, 1 Nanyang Walk, Singapore 637616 (Singapore); Krishnan, M. [Alameda Applied Sciences Corporation, San Leandro, California 94577 (United States)

2008-09-08

395

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

PubMed

In this work we study the influence of relativistic effects, in particular spin-orbit coupling, on electronic decay processes in KrXe2 clusters of various geometries. For the first time it is shown that inclusion of spin-orbit coupling has decisive influence on the accessibility of a specific decay pathway in these clusters. The radiationless relaxation process is initiated by a Kr 4s ionization followed by an electron transfer from xenon to krypton and a final second ionization of the system. We demonstrate the existence of competing electronic decay pathways depending in a subtle way on the geometry and level of theory. For our calculations a fully relativistic framework was employed where omission of spin-orbit coupling leads to closing of two decay pathways. These findings stress the relevance of an adequate relativistic description for clusters with heavy elements and their fragmentation dynamics. PMID:24784242

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

2014-04-28

396

Use of FPGA embedded processors for fast cluster reconstruction in the NA62 liquid krypton electromagnetic calorimeter  

NASA Astrophysics Data System (ADS)

The goal of the NA62 experiment at the CERN SPS is the measurement of the Branching Ratio of the very rare kaon decay K+??+ ? bar nu with a 10% accuracy by collecting 100 events in two years of data taking. An efficient photon veto system is needed to reject the K+??+ ?0 background and a liquid krypton electromagnetic calorimeter will be used for this purpose in the 1-10 mrad angular region. The L0 trigger system for the calorimeter consists of a peak reconstruction algorithm implemented on FPGA by using a mixed parallel architecture based on soft core Altera NIOS II embedded processors together with custom VHDL modules. This solution allows an efficient and flexible reconstruction of the energy-deposition peak. The system will be totally composed of 36 TEL62 boards, 108 mezzanine cards and 215 high-performance FPGAs. We describe the design, current status and the results of the first performance tests.

Badoni, D.; Bizzarri, M.; Bonaiuto, V.; Checcucci, B.; De Simone, N.; Federici, L.; Fucci, A.; Paoluzzi, G.; Papi, A.; Piccini, M.; Salamon, A.; Salina, G.; Santovetti, E.; Sargeni, F.; Venditti, S.

2014-01-01

397

Lunar Bouguer gravity anomalies - Imbrian age craters  

NASA Technical Reports Server (NTRS)

The Bouguer gravity of mass anomalies associated with four Imbrian age craters, analyzed in the present paper, are found to differ considerably from the values of the mass anomalies associated with some young lunar craters. Of the Imbrian age craters, only Piccolomini exhibits a negative gravity anomaly (i.e., a low density region) which is characteristic of the young craters studied. The Bouguer gravity anomalies are zero for each of the remaining Imbrian age craters. Since, Piccolomini is younger, or at least less modified, than the other Imbrian age craters, it is suggested that the processes responsible for the post-impact modification of the Imbrian age craters may also be responsible for removing the negative mass anomalies initially associated with these features.

Dvorak, J.; Phillips, R. J.

1978-01-01

398

Regional magnetic anomaly constraints on continental rifting  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

399

Dental anomalies in patients with Down syndrome.  

PubMed

The purpose of the present study was to evaluate the incidence of dental anomalies in Brazilian patients with Down syndrome. A sample with 49 panoramic x-rays of syndromic patients aged 3 to 33 years (22 male and 27 female) was used. The characteristics of dental anomalies were observed in the panoramic radiographs in both the primary and permanent dentition, according to the ICD (International Classification of Diseases). The corresponding tables and percentile analysis were elaborated. There was a high incidence of syndromic patients with different types of anomalies, such as taurodontism (50%), proven anodontia (20.2%), suspected anodontia (10.7%), conic teeth (8.3%) and impacted teeth (5.9%). In conclusion, patients with Down syndrome presented a high incidence of dental anomalies and, in most cases, the same individual presented more than one dental anomaly. PMID:18278307

de Moraes, Mari Eli Leonelli; de Moraes, Luiz Cesar; Dotto, Gustavo Nogara; Dotto, Patrcia Pasquali; dos Santos, Luis Roque de Arajo

2007-01-01

400

Structure of Hot Flow Anomaly  

NASA Astrophysics Data System (ADS)

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 formation mechanisms presume that HFA is formed when particles are reflected on bow shock, get swept by motional electric field and are injected back into the area. We tried to calculate the balance of energy in solar wind and within HFA to estimate what amount of reflected particles is needed for "internal recovery" area to be the real energy source. These estimations suggest that this energy balance is nearly fulfilled in 4 of 5 analyzed HFAs, and does not hold for one HFA. This energy balance may be in favor of quasi-stationary nature of HFA structure. References Thomsen, M. F., J. T. Gosling, S. A. Fuselier, S. J. Bame, and C. T. Russell (1986), Hot, diamagnetic cavities upstream from the Earth's bow shock, J. Geophys. Res., 91(A3), 2961-2973, doi:10.1029/JA091iA03p02961. Vaisberg, O.L., J.H.Waite, L.Avanov, V.N.Smirnov, D.Dempsey J.L.Burch and A.A.Skalsky, HFA-like signatures observed with Interball-Tail spacecraft, in: Solar Wind Nine, ed. By S.R.Habbal, R.Esser, J.V.Hollweg, and P.A.Isenberg, AIP 1-56396-865-7, 1999, pp. 551-554.

Shestakov, A.; Vaisberg, O. L.

2012-12-01

401

Presolar graphite from the Murchison meteorite: An isotopic study  

NASA Astrophysics Data System (ADS)

We studied presolar graphite grains from four density fractions, KE3 (1.65-1.72 g/cm3), KFA1 (2.05-2.10 g/cm3), KFB1 (2.10-2.15 g/cm3), and KFC1 (2.15-2.20 g/cm3), extracted from the Murchison (CM2) meteorite, with the ion microprobe. One of the most interesting features of presolar graphite is that isotopic features depend on density. There are grains with 15N and 18O excesses, Si isotopic anomalies, high 26Al/27Al ratios (0.1), and Ca and Ti isotopic anomalies, including the initial presence of short-lived 41Ca and 44Ti. These isotopic features are qualitatively explained by nucleosynthesis in core collapse supernovae. We estimate that 76%, 50%, 7% and 1% of the KE3, KFA1, KFB1 and KFC1 grains, respectively, are supernova grains. We performed 3- and 4-zone supernova mixing calculations to reproduce the C, O (18O/16O) and Al isotopic ratios of the KE3 grains, using 15 M? model calculations by Rauscher et al. (2002). Isotopic ratios of grains with high 12C/13C ratios (>200) can be reproduced, whereas those of grains with ratios ?200 are hard to explain if we assume that graphite grains form in C-rich conditions.

Amari, Sachiko; Zinner, Ernst; Gallino, Roberto

2014-05-01

402

Associated nonurinary congenital anomalies among infants with congenital anomalies of kidney and urinary tract (CAKUT).  

PubMed

Infants with congenital anomalies of kidney and urinary tract (CAKUT) often have other associated anomalies. The purpose of this investigation was to assess the prevalence and the types of associated anomalies in CAKUT in a defined population from northeastern France. The associated anomalies in CAKUT were collected in all livebirths, stillbirths and terminations of pregnancy during 26 years in 346,831 consecutive births of known outcome in the area covered by our population based registry of congenital anomalies. Of the 1678 infants with CAKUT born during this period (prevalence at birth of 48.4 per 10,000), 563 (34%) had associated anomalies. There were 119 (7%) patients with chromosomal abnormalities including 33 trisomies 18 (2%), and 168 (10%) nonchromosomal recognized dysmorphic conditions. There were no predominant recognized dysmorphic conditions, but VA(C)TER(L) association (3%). However, other recognised dysmorphic conditions were registered including Meckel-Gruber syndrome (2%), and prune belly syndrome (1%). Two hundred seventy six (16%) of the patients had multiple congenital anomalies, non syndromic, non chromosomal (MCA). Anomalies in the musculoskeletal, the digestive, the cardiovascular and the central nervous systems were the most common other anomalies. Prenatal diagnosis was obtained in 71% of dysmorphic syndromes with CAKUT. In conclusion the overall prevalence of associated anomalies, which was one in three infants, emphasizes the need for a thorough investigation of infants with CAKUT. The most commonly associated major nonurinary anomalies involved the musculoskeletal system, followed by the digestive, the cardiovascular and the central nervous systems. A routine screening for other anomalies may be considered in infants and in fetuses with CAKUT. One should be aware that the anomalies associated with CAKUT can be classified into a recognizable anomaly syndrome or pattern in one out of six infants with CAKUT. PMID:24821302

Stoll, Claude; Dott, Beatrice; Alembik, Yves; Roth, Marie-Paule

2014-07-01

403

Triple oxygen isotope variations in sedimentary rocks  

NASA Astrophysics Data System (ADS)

Relatively large (?0.2) 17O anomalies in the geologic record have been used to recognize atmospheric processes such as photochemical reactions and to trace changes in the partial pressures of O2 and CO2 in Earths atmosphere through time. However, recent oxygen isotope measurements of terrestrial rocks, minerals and waters also reveal common, smaller (but statistically significant) deviations from a single mass-dependent fractionation line. These subtle anomalies have been explained through differences in mass-dependent isotopic fractionations for various equilibrium and kinetic mechanisms. Here we present triple oxygen isotope data on sedimentary silica and oxides, including Archean and Phanerozoic cherts, and iron formations. The distribution of data reflects the mass fractionation laws of low-temperature precipitation reactions during growth of authigenic minerals, variation in ?17O of the waters from which sedimentary minerals precipitate, and equilibrium exchange after initial authigenic formation. We use these results to illustrate the potential for small, mass-dependent variations in ?17O values of sedimentary rocks to provide constraints on the environmental and climatic conditions in which they formed.

Levin, Naomi E.; Raub, Timothy D.; Dauphas, Nicolas; Eiler, John M.

2014-08-01

404

A Correlation Study Relating Spacecraft Anomalies to Environmental Data.  

National Technical Information Service (NTIS)

An environmental data program was initiated so that the operational environment for geosynchronous orbiting DSCS satellites could be specified at times of satellite anomalies. The anomalies studied included uncommanded logic reset anomalies, spinup anomal...

C. P. Pike M. H. Bunn

1976-01-01

405

The 129Xe Anomaly in MORB: Gone with the Wind?  

NASA Astrophysics Data System (ADS)

I have performed replicate crushing experiments on two glass MORB (East Pacific Rise and Mid Atlantic Ridge) in which previous whole-rock melting experiments showed ^40Ar/^36Ar ratios ranging up to ~15,000, indicating efficient trapping of gases from the mantle [1,2]. I loaded nearly a gram of mm-sized pieces and crushed varying portions of them under vacuum, transferring the released gases directly into the mass spectrometer and obtaining more than 20 separate aliquots. Though the Xe/Ar ratio was higher than atmospheric in all aliquots, indicating the presence of mantle xenon, none of the data show any excess ^129Xe from the decay of ^129I early in earth history. It is clear that some terrestrial xenon contains the anomaly [3], but it is not at all clear that the MORB source region does, though some models of mantle and atmospheric evolution rely heavily on this result [4]. I have gone through the literature, and find a diversity of results. Four papers, all from the same laboratory, present clear evidence of the anomaly [4-7], five others do not [8-12], and one straddles the fence [1]. The situation is complicatedby the ubiquitous presence in MORB of a component withatmospheric-like rare gas isotopic ratios. I shall discuss the attempts of various workers to separate these components, and the probability that a true anomaly exists in all or in some MORB source regions, by comparing Xe isotopic data obtained through stepwise heating, total fusion, or crushing experiments, with other pertinent ratios. "I have forgot much, Cynara, gone with the wind; Have flung roses, roses riotously with the throng." References: [1] Fisher D. E. (1986) GCA, 50, 2531-2541. [2] Fisher D. E. (1985) JGR, 90, B2, 1801-1807. [3] Boulos M. S. and Manuel O. K. (1971) Science, 174, 837-840. [4] Allegre C. J. (1983) Nature, 303, 762-766. [5] Staudacher T. and Allegre C. J. (1982) EPSL, 60, 389-406. [6] Staudacher T. (1989) EPSL, 96, 119- 133. [7] Marty B. (1989) EPSL, 94, 45-56. [8] Fisher D. E., EPSL, for publ. [9] Hiyagon H. (1992) GCA, 56, 1301-1316. [10] Ozima M. and Zashu S. (1983) EPSL, 62, 24-40. [11] Takaoka N. and Nagao K. (1978) Nature, 276, 491-492. [12] Kirsten T. and Richter H. (1981) Meteoritics, 16, 341.

Fisher, D. E.

1993-07-01

406

Hyperspectral anomaly detection beyond RX  

NASA Astrophysics Data System (ADS)

The basic multivariate anomaly detector ("the RX algorithm") of Kelly and Reed remains little altered after nearly 30 years and performs reasonably well with hyperspectral imagery. However, better performance can be achieved in spectral applications by recognizing a deficiency in the hypothesis test that generates RX. The problem is commonly associated with the improved performance that results from deleting several high-variance clutter dimensions before applying RX, a procedure not envisioned in the original algorithm. There is, moreover, a better way to enhance detection than simply deleting the offending subspace. Instead of invoking the "additive target" model, one can exploit expected differences in spectral variability between target and background signals in the clutter dimensions. Several methods are discussed for achieving detection gain using this principle. Two of these are based on modifications to the RX hypothesis test. One results in Joint Subspace Detection, the other in an algorithm with a similar form but which does not postulate a clutter subspace. Each of these modifies the RX algorithm to incorporate clutter-dependent weights, including "anti-RX" terms in the clutter subspace. A newer approach is also described, which effects a nonlinear suppression of false alarms that are detected by an RX-type algorithm, employed as a preprocessor. Both techniques rely ultimately on the incorporation of simple spectral phenomenology into the detection process.

Schaum, A. P.

2007-04-01

407

The free-convective anomaly.  

PubMed

Persons exposed to high temperature, or to equivalent environmental factors, have quantifiable reactions, such as reducing the resistance to both heat and moisture flow in skin tissues and clothing needed to maintain thermal equilibrium. The one-to-one relationship between this resistance in the walking person and temperature, with the other factors neutral, is the basis for the apparent temperature scale and the derived heat index. When this approach is taken to assess the thermal environment for a still person exposed to heat in still air, there is a zone of ambient conditions in which there are three solutions to the heat-balance equation. Extraordinary thermal stress occurs, depending slightly on other conditions, at ambient temperatures near 41 degrees C, especially at high humidity, because of the difficulty in carrying sweat vapor from the person when free convection is minimal. This anomaly is examined for a range of ambient vapor pressures and extra radiation. The rapid rise in heat stress when ambient temperature just exceeds body temperature in still conditions may explain the severity of some observed distress. PMID:10409558

Steadman, R G

1999-07-01

408

Data Mining for Anomaly Detection  

NASA Technical Reports Server (NTRS)

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.

Biswas, Gautam; Mack, Daniel; Mylaraswamy, Dinkar; Bharadwaj, Raj

2013-01-01

409

Grains of anomalous isotopic composition from novae  

NASA Technical Reports Server (NTRS)

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

Clayton, D. D.; Hoyle, F.

1976-01-01

410

Variations of the isotopic composition of sulfur in enstatite and ordinary chondrites  

NASA Technical Reports Server (NTRS)

High-precision sulfur isotopic analyses (delta S-33, delta S-34, and delta S-36) of bulk ordinary and enstatite chondrites demonstrate that systematic variations exist. The average delta S-34 values are -0.26 +/- 0.07, -0.02 +/- 0.06, and 0.49 +/- 0.16 percent for enstatite and ordinary and carbonaceous chondrites, respectively. Isotopic variations of different sample specimens of primitive meteorites, e.g., Qingzhen and Abee, were observed which may be attributed to heterogeneity in the early solar nebula. Sulfur isotopic fractionations in both bulk samples and mineral separates are mass-dependent, and no nuclear isotopic anomalies were detected. The sulfur isotopic compositions of both mineral and density separates were measured. The sulfur isotopic compositions of separated chondrules from Chainpur and Bjurbole are reported. Significant isotopic difference for the chondrules from the bulk meteorite are noted for both meteorites.

Gao, Xia; Thiemens, Mark H.

1993-01-01

411

Prevalence of dental anomalies in Indian population  

PubMed Central

Objectives: Developmental anomalies of the dentition are not infrequently observed by the dental practitioner. The aim of the present study was to determine the prevalence of dental anomalies in the Indian population. Study Design: A retrospective study of 4133 panoramic radiographs of patients, who attended the Department of Oral Medicine and Radiology, Jodhpur Dental College General Hospital between September 2008 to December 2012 was done. The ages of the patients ranged from 13 to 38 years with a mean age of 21.8 years. The orthopantomographs (OPGs) and dental records were examined for any unusual finding such as congenitally missing teeth, impactions, ectopic eruption, supernumerary teeth, odontoma, dilacerations, taurodontism, dens in dente, germination and fusion, among others. Results: 1519 (36.7%) patients had at least one dental anomaly. The congenitally missing teeth 673 (16.3%) had the highest prevalence, followed by impacted teeth 641 (15.5%), supernumerary teeth 51 (1.2%) and microdontia 41 (1.0%). Other anomalies were found at lower prevalence ranging from transposition 7 (0.1%) to ectopic eruption 30 (0.7%). Conclusion: The most prevalent anomaly in the Indian population was congenitally missing teeth (16.3%), and the second frequent anomaly was impacted teeth (15.5%), whereas, macrodontia, odontoma and transposition were the least frequent anomalies, with a prevalence of 0.2%, 0.2% and 0.1% respectively. While the overall prevalence of these anomalies may be low, the early diagnosis is imperative for the patient management and treatment planning. Key words:Dental anomaly, prevalence, panoramic radiography.

Doni, Bharati; Kaswan, Sumita; Rahman, Farzan

2013-01-01

412

Isotope modeling of nitric acid formation in the atmosphere: Testing the importance of NO oxidation, heterogeneous reactions, and nighttime chemistry  

Microsoft Academic Search

Atmospheric nitrate (NO3-atm = HNO3 and particulate nitrate) is the primary sink of NOx and its isotopic composition can yield important information about oxidation pathways. In particular oxygen isotope anomalies, the 17O excess (Delta17O values), have potential to determine the relative importance of NOx oxidation pathways (OH, NO3 or N2O5). We have developed a new isotope tracer model to test

G. Michalski; F. Xu

2009-01-01

413

Systematic study of sulfur isotopic composition in iron meteorites and the occurrence of excess S-33 and S-36  

Microsoft Academic Search

The paper concentrates on isotopic measurements of sulfur in different sulfur-carrier phases: troilite inclusions, Fe-Ni alloy, and schreibersite (possibly including daubreelite). Variations in S-34 isotope ratio are observed in some troilite inclusions, and no evidence of nucleosynthetic sulfur isotopic anomalies are found in the troilite inclusions. Excesses of S-33 and S-36 are observed in both FeNi alloy and schreibersite of

Xia Gao; Mark H. Thiemens

1991-01-01

414

Regional magnetic anomaly constraints on continental breakup  

SciTech Connect

Continental lithosphere magnetic anomalies mapped by the Magsat satellite are related to tectonic features associated with regional compositional variations of the crust and upper mantle and crustal thickness and thermal perturbations. These continental-scale anomaly patterns when corrected for varying observation elevation and the global change in the direction and intensity of the geomagnetic field show remarkable correlation of regional lithospheric magnetic sources across rifted continental margins when plotted on a reconstruction of Pangea. Accordingly, these anomalies provide new and fundamental constraints on the geologic evolution and dynamics of the continents and oceans.

von Frese, R.R.B.; Hinze, W.J.; Olivier, R.; Bentley, C.R.

1986-01-01

415

Ion time-of-flight spectroscopy: krypton charge-state spectra as a function of photon excitation energy near the K edge  

SciTech Connect

In this experiment, we have recorded the charge state distribution resulting from atomic rearrangement following the creation of the inner shell vacancies in krypton atoms. Intense, highly collimated, monochromatic and tunable x-ray radiation available at the CHESS synchrotron radiation facility at Cornell was used to photoionize krypton atoms in a gas jet target, and a time-of-flight spectrometer was used to record the ions in different charge states formed after photoionization. Charge state spectra were recorded at below, at the peak in the K edge and above the edge. Below the edge, charge states +4 to +7 were observed with appreciable intensity, while at, and above the edge, the charge states ranged from +4 to +10.

Hastings, J.B.; Kostroun, V.O.

1982-01-01

416

Brine history indicated by argon, krypton, chlorine, bromine, and iodine analyses of fluid inclusions from the Mississippi Valley type lead-fluorite-barite deposits at Hansonburg, New Mexico  

Microsoft Academic Search

Argon, krypton, chlorine, bromine, and iodine were measured in a homogeneous population of high-salinity hydrothermal fluid inclusions from the Tertiary-age Mississippi Valley-type (MVT) lead-fluorite-barite deposits at Hansonburg, New Mexico to establish new types of evidence for the history of both the fluid and the major dissolved salts. Noble gases and halogens in fluid inclusions containing 10-10-10-9 L of brine (Cl

J. K. Bhlke; J. J. Irwin

1992-01-01

417

Pacific Temperature Anomalies with Color Key  

NSDL National Science Digital Library

This animation shows the El Nino-La Nina Sea Surface Temperature Anomaly from January 1997 through July 1999. A color bar is displayed below the data. This animation is a minor revision of animation ID 790.

Shirah, Greg; Starr, Cindy; Busalacchi, Antonio; Schultz, Peter

2004-02-09

418

Magnetosheath Flow Anomalies in 3-D  

NASA Technical Reports Server (NTRS)

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.

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

419

The Pioneer anomaly and the holographic scenario  

NASA Astrophysics Data System (ADS)

In this paper we discuss the recently obtained relation between the Verlinde's holographic model and the first phenomenological Modified Newtonian dynamics. This gives also a promising possible explanation to the Pioneer anomaly.

Gin, Jaume

2012-01-01

420

Reduction of satellite magnetic anomaly data  

NASA Technical Reports Server (NTRS)

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.

Slud, E. V.; Smith, P. J.; Langel, R. A.

1984-01-01

421

Design and Implementation of an Anomaly Detector  

SciTech Connect

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.

Bagherjeiran, A; Cantu-Paz, E; Kamath, C

2005-07-11

422

Understanding Magnetic Anomalies and Their Significance.  

ERIC Educational Resources Information Center

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)

Shea, James H.

1988-01-01

423

Compressive Hyperspectral Imaging and Anomaly Detection.  

National Technical Information Service (NTIS)

We have developed and applied successfully new algorithms for hyperspectral imagery. These include compressive sensing, anomaly detection, target detection, endmember detection, unmixing and change detection. These were tested on data provided by AFRL wit...

K. Kelly P. Thiyanarantnam S. Chen S. Osher W. Yin

2013-01-01

424

Anomaly Detection in Gamma-Ray Vehicle Spectra with Principal Components Analysis and Mahalanobis Distances  

SciTech Connect

The goal of primary radiation monitoring in support of routine screening and emergency response is to detect characteristics in vehicle radiation signatures that indicate the presence of potential threats. Two conceptual approaches to analyzing gamma-ray spectra for threat detection are isotope identification and anomaly detection. While isotope identification is the time-honored method, an emerging technique is anomaly detection that uses benign vehicle gamma ray signatures to define an expectation of the radiation signature for vehicles that do not pose a threat. Newly acquired spectra are then compared to this expectation using statistical criteria that reflect acceptable false alarm rates and probabilities of detection. The gamma-ray spectra analyzed here were collected at a U.S. land Port of Entry (POE) using a NaI-based radiation portal monitor (RPM). The raw data were analyzed to develop a benign vehicle expectation by decimating the original pulse-height channels to 35 energy bins, extracting composite variables via principal components analysis (PCA), and estimating statistically weighted distances from the mean vehicle spectrum with the mahalanobis distance (MD) metric. This paper reviews the methods used to establish the anomaly identification criteria and presents a systematic analysis of the response of the combined PCA and MD algorithm to modeled mono-energetic gamma-ray sources.

Tardiff, Mark F.; Runkle, Robert C.; Anderson, K. K.; Smith, L. E.

2006-01-23

425

Principal Component-based Anomaly Detection Scheme  

Microsoft Academic Search

In this chapter, a novel anomaly detection scheme that uses a robust principal component classifier (PCC) to handle computer\\u000a network security problems is proposed. An intrusion predictive model is constructed from the major and minor principal components\\u000a of the normal instances, where the difference of an anomaly from the normal instance is the distance in the principal component\\u000a space. The

Mei-ling Shyu; Shu-ching Chen; Kanoksri Sarinnapakorn; Liwu Chang

2006-01-01

426

Potter syndrome with an unusual cardiac anomaly  

PubMed Central

Potter syndrome is a congenital anomaly characterised by bilateral renal agenesis, pulmonary hypoplasia, cardiac, skeletal abnormalities and maternal oligohydramnios. Here we report a case of Potter syndrome with bilateral renal agenesis, pulmonary hypoplasia and complete transposition of the great vessels, which had been identified during a post-mortem examination. Although cardiac anomalies are known to exist with Potter syndrome, complete transposition of the great vessels has not been reported in the literature.

Prabhu, Savit; Sigamani, Elanthenral; Das, Prasenjit; Sasi, Arun; Safaya, Rajni

2009-01-01

427

ANOMALY-BASED HYPERSPECTRAL IMAGE COMPRESSION  

Microsoft Academic Search

We propose a new lossy compression algorithm for hyperspectral images, which is based on spectral principal component analysis (PCA), followed by JPEG2000 (JP2K). The approach employs an anomaly-removal model in the compression process to preserve anomalous pixels. Results on two different hyperspectral image scenes show that the new algorithm not only provides good post-compression anomaly-detection performance but also improves rate-

Qian Du; Wei Zhu; James E. Fowler

2009-01-01

428

Anomaly-Based Hyperspectral Image Compression  

Microsoft Academic Search

We propose a new lossy compression algorithm for hyperspectral images, which is based on spectral principal component analysis (PCA), followed by JPEG2000 (JP2K). The approach employs an anomaly-removal model in the compression process to preserve anomalous pixels. Results on two different hyperspectral image scenes show that the new algorithm not only provides good post-compression anomaly-detection performance but also improves rate-distortion

Qian Du; Wei Zhu; James E. Fowler

2008-01-01

429

Great Salinity Anomalies in the North Atlantic  

Microsoft Academic Search

We revisited the Great Salinity Anomaly of the 1970s (GSA'70s; Dickson et al., 1988) and documented the newly identified Great Salinity Anomaly of the 1980s (hence termed GSA'80s), both propagated around the North Atlantic in a similar fashion. The advective mechanism, initially proposed to explain the observed sequence of low-salinity, low-temperature events during the GSA'70s, apparently holds also for the

Igor M. Belkin; Sydney Levitus; John Antonov; Svend-Aage Malmberg

1998-01-01

430

[Comparative study on diode laser (680 nm) and krypton laser mild photocoagulation--histological findings and therapeutic outcome for diabetic maculopathy].  

PubMed

A histopathological study of macaca monkey retina-choroid was carried out for one month after mild photocoagulation with a diode laser (680 nm) and a krypton laser (647 nm). Both lasers produced the same damage to the outer layer of retina and to the melanocytes of 1/3 of the inner choroid. Mild focal photocoagulation was done for 6 patients (12 eyes) with diabetic maculopathy. The patients were 41 to 67 years old, suffering from diabetes mellitus for 5 to 25 years. The grade of their retinopathy was Fukuda's classification AI, AII, and BI. AII eyes were tested before and 3-6 months after photocoagulation for corrected visual acuity, fluorescein angiography, and visual field sensitivity by Octopus automated static perimetry. Visual acuity was stable in all cases. Central sensitivity was better in 2 eyes and unchanged in 4 eyes in both types of laser photocoagulation. In cases of total loss, one eye was improved, 4 eyes were unchanged and one eye was worsened by diode laser photocoagulation and one eye was improved, 2 eyes were unchanged and 3 eyes were worsened by krypton laser photocoagulation. The diode laser (680 nm) might be as useful for ophthalmic laser treatment as the krypton laser. PMID:8905966

Okuyama, M; Okisaka, S; Nakagami, T; Sai, Y; Mizukawa, A; Ito, M; Ohta, Y

1996-09-01

431

Multidimensional Radiation Emission and Absorption Processes in a Large Diameter Krypton Gas Puff Z-Pinch Plasma on the ZR Simulator  

NASA Astrophysics Data System (ADS)

In a hot and dense plasma environment, such as that expected to be produced in a large diameter krypton gas puff load implosion on the ZR simulator, the radiation plays a significant and influential role on the time and space evolution of the plasma. An investigation of the multidimensional radiation emission, absorption, and transfer processes as well as their effects on the energetics & dynamics of the krypton Z-pinch plasma on the simulator, is made using the mach2 2D radiation MHD code. The incorporation of the dynamical domain tabular collisional radiative equilibrium (DDTCRE) radiation transport model [Y. K. Chong, et. al., ICOPS 2005, Monterey, CA.] into mach2 affords a realistic description of the self-consistent non-local non-LTE ionization dynamics & radiation transport physics in a computationally efficient manner. An extensive krypton atomic structure model including the M-, L-, and K-shells forms the basis for the transport model. In addition, the K- and L-shell radiation yield and power signatures, as well as their spectral & spatial characteristics are highlighted through a detailed postprocess analysis of the plasma during various stages of the implosion process using the AXSTRAN 2D non-LTE radiation ionization dynamics code & the SPECAM 3D multifrequency non-LTE spectra/image synthesizer code. *Work supported by DTRA.

Chong, Y.; Thornhill, J. W.; Clark, R. W.; Dasgupta, A.; Apruzese, J. P.; Davis, J.

2006-10-01

432

Classifying gauge anomalies through symmetry-protected trivial orders and classifying gravitational anomalies through topological orders  

NASA Astrophysics Data System (ADS)

In this paper, we systematically study gauge anomalies in bosonic and fermionic weak-coupling gauge theories with gauge group G (which can be continuous or discrete) in d space-time dimensions. We show a very close relation between gauge anomalies for gauge group G and symmetry-protected trivial (SPT) orders (also known as symmetry-protected topological (SPT) orders) with symmetry group G in one-higher dimension. The SPT phases are classified by group cohomology class Hd+1(G,R/Z). Through a more careful consideration, we argue that the gauge anomalies are described by the elements in Free[Hd+1(G,R/Z)]?H??d+1(BG,R/Z). The well known Adler-Bell-Jackiw anomalies are classified by the free part of Hd+1(G,R/Z) (denoted as Free[Hd+1(G,R/Z)]). We refer to other kinds of gauge anomalies beyond Adler-Bell-Jackiw anomalies as non-ABJ gauge anomalies, which include Witten SU(2) global gauge anomalies. We introduce a notion of ?-cohomology group, H??d+1(BG,R/Z), for the classifying space BG, which is an Abelian group and include Tor[Hd+1(G,R/Z)] and topological cohomology group Hd+1(BG,R/Z) as subgroups. We argue that H??d+1(BG,R/Z) classifies the bosonic non-ABJ gauge anomalies and partially classifies fermionic non-ABJ anomalies. Using the same approach that shows gauge anomalies to be connected to SPT phases, we can also show that gravitational anomalies are connected to topological orders (i.e., patterns of long-range entanglement) in one-higher dimension.

Wen, Xiao-Gang

2013-08-01

433

Statistics and Dynamics of Persistent Anomalies.  

NASA Astrophysics Data System (ADS)

Persistent anomalies with recurrent spatial patterns play an important role in the atmosphere's low-frequency variability. We establish a connection between statistical and dynamical methods of description and prediction of persistent anomalies. This is done by computing and analyzing the empirical orthogonal functions (EOFs) in a simple deterministic model, on the one hand, and in Southern Hemisphere geopotential heights, on the other.The dynamical model is governed by the fully nonlinear, equivalent-barotropic vorticity equation on the sphere, with simplified forcing, dissipation and topography. Model solutions exhibit persistent anomalies identifiable with blocked, zonal and wave-train anomalies in Northern Hemisphere atmospheric data. Flow structures similar to the patterns above occur as high-variance EOFs of this nonlinear model.The Southern Hemisphere data we analyze consist in gridded daily maps of 500 mb heights from June 1972 to July 1983. Two types of persistent anomalies appear in this time series, both having a strong wavenumber-three component; they differ by the value of the constant phase of this wave and by the strength of the wavenumber-one component. The first two EOFs bear a striking resemblance to these two patterns.We conclude that the dynamical interpretation of EOFs is their pointing from the time mean to the most populated regions of the system's phase space. Pursuing this interpretation, we introduce a Markov-chain formulation of transitions from one persistent anomaly regime to another, and discuss the implications for long-range forecasting.

Mo, Kingtse C.; Ghil, Michael

1987-03-01

434

Manganese-chromium isotope systematics and the development of the early solar system  

NASA Astrophysics Data System (ADS)

High-precision measurements of the chromium isotope compositions of samples from meteorites reveal anomalies in the Cr-53/Cr-52 ratio which are believed to arise from in situ decay of the extinct short-lived nuclide Mn-53. The decay of Mn-53 to Cr-53 in the early solar system provides an additional chronometer with which to constrain the formation times of the small planetary bodies from which the meteorites originated. A comparison of chromium and titanium isotope anomalies shows them to be imperfectly correlated, bearing witness to the complexity of early solar system processes.

Birck, J.-L.; Allegre, C. J.

1988-02-01

435

Clustering and Recurring Anomaly Identification: Recurring Anomaly Detection System (ReADS)  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the Recurring Anomaly Detection System (ReADS). The Recurring Anomaly Detection System is a tool to analyze text reports, such as aviation reports and maintenance records: (1) Text clustering algorithms group large quantities of reports and documents; Reduces human error and fatigue (2) Identifies interconnected reports; Automates the discovery of possible recurring anomalies; (3) Provides a visualization of the clusters and recurring anomalies We have illustrated our techniques on data from Shuttle and ISS discrepancy reports, as well as ASRS data. ReADS has been integrated with a secure online search

McIntosh, Dawn

2006-01-01

436

54-Cr Anomalies in the Orgueil Carbonaceous Chondrite  

NASA Astrophysics Data System (ADS)

Cr in CI meteorites displays isotopic anomalies in a unique pattern [1-3]. Etching of bulk Orgueil in relatively mild reactants (CH3COOH and dilute HNO3) dissolves most (>80%) of the Cr along with most of other major cations (Mg, Ca, Fe, Ni, Al). The Cr thus dissolved is deficient in 54Cr by about 6 epsilon-units (using 50Cr/52Cr normalization). Much of the remaining Cr is released in further etching in HCl; this Cr has stronger excesses of 54Cr, up to around 100epsilon. Dissolution of the residues in more aggressive reactants yields Cr with smaller excesses of 54Cr. There are no known correlating anomalies in other elements or even in 53Cr. Although no Cr carrier in Orgueil has isotopically normal Cr, mass balance calculations indicate approximately normal Cr in the whole rock. We have previously suggested that these results could be most simply explained by postulating one carrier phase, relatively rich in Cr and bearing strong excess 54Cr, presumably from neutron-rich nuclear statistical equilibrium nucleosynthesis. This phase would have to be soluble in HCl but resistant to parent body aqueous alteration. In this interpretation the 54Cr-deficiency in most of the Cr is understandable in terms of mixing of all the nucleosnthetic sources contributing to solar normal except for that in the postulated carrier phase. Qualitatively similar but more subdued isotopic effects occur in CM meteorites and are very subdued or absent in CV and CO meteorites[1]. If the parent bodies for these classes originally contained the same postulated phase in comparable abundance, the implication is that the 54Cr-enriched carrier phase is also not resistant to the thermal processing experienced by these classes. Interstellar grains bearing Cr from specific nucleosynthetic events would be expected to be much more anomalous than any samples yet observed; we thus lack evidence to determine whether the carrier is itself a type of interstellar grain (in which case all observations to date reflect major dilution with more nearly normal Cr) or whether it is a solar nebula product preferentially incorporating such interstellar grains. In either case, the implicated interstellar grain type is clearly different from the types already known and isolated (diamond, graphite, carbides, oxides), all of which are chemically and thermally resistant to nebular processing. We have examined fractions of Orgueil separated from a CH3COOH/HNO3 residue by a teflon-coated magnetic stirring bar. For both fractions HCl treatment yields Cr more strongly enriched in 54Cr (by about 200epsilon) than any previously observed. Evidently this procedure is ineffective in separating the carrier (or there is more than one carrier); the magnetite which comprises most of the magnetic fraction is apparently just a dilutant. SEM/EDX analysis of the various etch residues (and untreated bulk) for Orgueil reveals the presence of small (mostly submicron) Cr-rich grains (Cr and O, often with significant Fe and/or Mn). Quantitative abundance determination of such grains is difficult, nor can we be confident about their disappearance or persistence in HCl etching, but such grains could account for the observed isotopic effects if they are very enriched in 54Cr. Preliminary ion probe measurements on the non-magnetic fraction of Orgueil indicate that most Cr-rich spots have normal Cr within errors but that some have large 54Cr enrichments (at least tens of percent). One such grain may have a truly radical Cr isotopic composition. References: [1] Rotaru M. et al. (1992) Nature, 358, 465-470. [2] Ott U. et al. (1994) LPSC XXV, 1033-1034. [3] Podosek F. A. et al. (1994) Meteoritics, 29, 519.

Podosek, F. A.; Ott, U.; Brannon, J. C.; Bernatowicz, T. J.; Neal, C. R.

1995-09-01

437

New views of the spherical Bouguer gravity anomaly  

Microsoft Academic Search

This paper presents a number of new concepts concerning the gravity anomaly. First, it identifies a distinct difference between a surface (2-D) gravity anomaly (the difference between actual gravity on one surface and normal gravity on another surface) and a solid (3-D) gravity anomaly defined in the fundamental gravimetric equation. Second, it introduces the `no topography' gravity anomaly (which turns

P. Vancek; R. Tenzer; L. E. Sjberg; Z. Martinec; W. E. Featherstone

2004-01-01

438

A new method for gravity anomaly distortion correction  

Microsoft Academic Search

Using gravity anomaly covariance function based on second-order Gaussian Markov gravity anomaly potential model, the state equation of gravity anomaly signal is obtained in marine gravimetry. Combined with the system state equation and the measurement equation, a new method of cascade Kalman filter is proposed and applied to the correction of gravity anomaly distortion. In the signal processing procedure, inverse

Liye Zhao; Hongsheng Li

2008-01-01

439

Persistent anomalies of the extratropical Northern Hemisphere wintertime circulation - Structure  

NASA Technical Reports Server (NTRS)

A study identifying horizontal and vertical structures of low patterns occurring with persistent 500 mb height anomalies in the central North Pacific, eastern North Atlantic, and northern Soviet Union regions is presented. The flow patterns of positive and negative anomalies are compared. The relationship between persistent anomalies and small recurrent anomaly patterns is examined. The temporal fluctuations of the persistent patterns are analyzed.

Dole, R. M.

1986-01-01

440

Isotopic and geochemical precursors of earthquakes and volcanic eruptions  

NASA Astrophysics Data System (ADS)

Radon 222 seems to be one of the most promising precursors and is the tracer for which more data are available: according to statistics elaborated in China, 70% of earthquakes are preceded by radon anomalies detectable in soil, air and/or in groundwater. Also other changes of the fluid chemical composition and variations of (sup 3)He/(sup 4)He, (sup 2)H/(sup 1)H, (sup 13)C/(sup 12)C, (sup 18)O/(sup 16)O isotopic ratios have been detected. Among these indicators one can mention variations in concentration and/or isotopic ratios of hydrogen, helium, carbon, oxygen, neon, radon, radium, and uranium.

1993-11-01

441

Polaronic and nonadiabatic phase diagram from anomalous isotope effects.  

PubMed

Isotope effects (IEs) are powerful tools to probe directly the dependence of many physical properties on lattice dynamics. In this Letter we investigate the onset of anomalous IEs in the spinless Holstein model by employing the dynamical mean field theory. We show that the isotope coefficients of the electron effective mass and of the dressed phonon frequency are sizable also far away from the polaronic crossover and mark the importance of nonadiabatic lattice fluctuations. We draw a nonadiabatic phase diagram in which we identify a novel crossover, not related to polaronic features, where the IEs attain their largest anomalies. PMID:15698295

Paci, P; Capone, M; Cappelluti, E; Ciuchi, S; Grimaldi, C; Pietronero, L

2005-01-28

442

Radionuclide imaging of rare congenital renal fusion anomalies.  

PubMed

Demonstration of a congenital renal anomaly plays an important role in the treatment of patients with renal infection. These patients are prone to infections because of coexisting urinary tract anomalies such as duplicated ureter, ureter opening anomalies, and urinary stasis. Assessment of renal parenchymal damage resulting from acute or chronic renal infection is the primary indication for radionuclide imaging with Tc-99m DMSA. In addition, this technique allows congenital anomalies to be identified. The authors review congenital renal fusion anomalies identified in children through Tc-99m DMSA imaging. They conclude that Tc-99m DMSA imaging can reveal important diagnostic information about various congenital anomalies, including fusion anomalies. PMID:12592127

Volkan, Bilge; Ceylan, Emel; Kiratli, Pinar Ozgen

2003-03-01

443

Argon, krypton, and xenon in the bulk solar wind as collected by the Genesis mission  

NASA Astrophysics Data System (ADS)

We present bulk solar wind isotopic and elemental ratios for Ar, Kr, and Xe averaged from up to 14 individual analyses on silicon targets exposed to the solar wind for 2.3 years during NASA's Genesis mission. All averages are given with 1 ? standard errors of the means and include the uncertainties of our absolute calibrations. The isotopic ratios 86Kr/ 84Kr and 129Xe/ 132Xe are 0.303 0.001 and 1.06 0.01, respectively. The elemental ratios 36Ar/ 84Kr and 84Kr/ 132Xe are 2390 120 and 9.9 0.3, respectively. Average fluxes of 84Kr and 132Xe in the bulk solar wind in atoms/(cm 2 s) are 0.166 0.009 and 0.017 0.001, respectively. The flux uncertainties also include a 2% uncertainty for the determination of the extracted areas. The bulk solar wind 36Ar/ 38Ar ratio of 5.50 0.01 and the 36Ar flux of 397 11 atoms/(cm 2 s) determined from silicon targets agree well with the 36Ar/ 38Ar ratio and the 36Ar flux determined earlier on a different type of target by Heber et al. (2009). A comparison of the solar wind noble gas/oxygen abundance ratios with those in the solar photosphere revealed a slight enrichment of Xe and, within uncertainties a roughly uniform depletion of Kr-He in the solar wind, possibly related to the first ionization potentials of the studied elements. Thus, the solar wind elemental abundances He-Kr display within uncertainties roughly photospheric compositions relative to each other. A comparison of the Genesis data with solar wind heavy noble gas data deduced from lunar regolith samples irradiated with solar wind at different times in the past reveals uniform 36Ar/ 84Kr ratios over the last 1-2 Ga but an increase of the 84Kr/ 132Xe ratio of about a factor of 2 during the same time span. The reason for this change in the solar wind composition remains unknown.

Vogel, Nadia; Heber, Veronika S.; Baur, Heinrich; Burnett, Donald S.; Wieler, Rainer

2011-06-01

444

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

445

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

NASA Astrophysics Data System (ADS)

Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 51011 atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

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

1983-12-01

446

Aggregation and Thresholding Schemes for Anomaly-Based Approaches  

Microsoft Academic Search

Anomaly-based approaches often require multiple profiles and models in order to characterize different aspects of normal behaviors.\\u000a In particular, anomaly scores of audit events are obtained by aggregating several local anomaly scores. Remarkably, most works\\u000a focus on profile\\/model definition while critical issues of anomaly measuring, aggregating and thresholding are dealt with\\u000a simplistically. This paper addresses the issue of anomaly scoring

Salem Benferhat; Karim Tabia

447

Three-Body Forces and the Limit of Oxygen Isotopes  

SciTech Connect

The limit of neutron-rich nuclei, the neutron drip line, evolves regularly from light to medium-mass nuclei except for a striking anomaly in the oxygen isotopes. This anomaly is not reproduced in shell-model calculations derived from microscopic two-nucleon forces. Here, we present the first microscopic explanation of the oxygen anomaly based on three-nucleon forces that have been established in few-body systems. This leads to repulsive contributions to the interactions among excess neutrons that change the location of the neutron drip line from {sup 28}O to the experimentally observed {sup 24}O. Since the mechanism is robust and general, our findings impact the prediction of the most neutron-rich nuclei and the synthesis of heavy elements in neutron-rich environments.

Otsuka, Takaharu [Department of Physics, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan, 48824 (United States); Suzuki, Toshio [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3, Tokyo 156-8550 (Japan); Holt, Jason D.; Schwenk, Achim [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Akaishi, Yoshinori [RIKEN Nishina Center, Hirosawa, Wako-shi, Saitama 351-0198 (Japan)

2010-07-16