These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
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

Atom trap trace analysis of krypton isotopes  

SciTech Connect

A new method of ultrasensitive isotope trace analysis has been developed. This method, based on the technique of laser manipulation of neutral atoms, has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton gas sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. This method is free of contamination from other isotopes and elements and can be applied to several different isotope tracers for a wide range of applications. The demonstrated detection efficiency is 1 x 10{sup {minus}7}. System improvements could increase the efficiency by many orders of magnitude.

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

1999-11-17

3

Physicochemical isotope anomalies  

SciTech Connect

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

Esat, T.M. (Australian National Univ., Canberra)

1988-06-01

4

Shape Transitions and Jacobian Instability in Excited Krypton Isotopes  

NASA Astrophysics Data System (ADS)

Shape transitions as a function of angular momentum in even-even krypton isotopes with A = 72-84 have been investigated using the cranked Nilsson-Strutinsky method. The Jacobi shape transition from noncollective oblate to super or hyperdeformed collective prolate or triaxial shape taking place in rotating nuclei as in the case of gravitating rotating stars is studied in krypton isotopes. The cranked Nilsson-Strutinsky method with a method of tuning the angular velocity to get the fixed spins is used in the calculations. Our results show that all the krypton isotopes considered in this study are the good candidates for detecting the Jacobi shape transition. Shape evolutions as a function of spin and temperature with thermal fluctuations are studied using the Landau theory of phase transitions. The constants appearing in the Landau expression for the free energy are determined by using the free energy surfaces at ? = 0 calculated by the Strutinsky method. We show that in the presence of thermal fluctuations, the averaged shapes obtained for the considered isotopes differ from the most probable shapes. The sharp Jacobi transitions are modified due to the effect of thermal fluctuations.

Selvam, V.; Devadhason, D. R. Jayahar; Beula, J. M.

2014-12-01

5

Estimation of neutron-induced spallation yields of krypton isotopes  

NASA Astrophysics Data System (ADS)

A procedure is outlined for estimating cross sections for neutron-induced spallation products relative to those for proton-induced reactions. When combined with known proton spallation systematics, it is demonstrated that cumulative yields for cosmogenically-important stable 84Kr and 86Kr isotopes are ~1.4 and ~2.8 times greater, respectively, for incident neutrons compared to protons at 0.2<=E<=3.0 GeV for nearby medium mass targets. Yields for lighter kryptons are relatively insensitive to the identity of the incident nucleon. NUCLEAR REACTIONS (n, spallation), 0.2<=En<=3.0 GeV, stable Kr product yield estimates from proton spallation systematics.

Karol, Paul J.; Tobin, Michael J.; Shibata, Seiichi

1983-10-01

6

Isotopic anomalies in extraterrestrial grains.  

PubMed

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

Ireland, T R

1996-03-01

7

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

Microsoft Academic Search

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

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

1995-01-01

8

Chromium isotopic anomalies in the Allende meteorite  

NASA Technical Reports Server (NTRS)

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

Papanastassiou, D. A.

1986-01-01

9

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

E-print Network

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

C. R. Cowley; S. Hubrig; F. Castelli

2007-11-15

10

Getrennte Abscheidung der bei der Uranspaltung entstehenden Krypton und Xenon-Isotope  

Microsoft Academic Search

Durch Verwendung hintereinander angebrachter Kohleadsorptionsgefäße, von denen das eine mit fester Kohlensäure + Alkohol, das andere mit flüssiger Luft gekühlt ist, wird unter geeigneten Bedingungen eine quantitative Trennung der bei der Uranspaltung auftretenden Edelgase Krypton und Xenon erreicht. Damit lassen sich deren Umwandlungsprodukte ohne chemische Trennungen leicht rein herstellen.

Otto Hahn; Fritz Strassmann

1940-01-01

11

Barium and neodymium isotopic anomalies in the Allende meteorite  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

12

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

13

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

14

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

15

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

16

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

17

Isotopic anomalies in solar system material - What can they tell us  

Microsoft Academic Search

Three relatively recently discovered anomalies are considered. The goal of isotopic research is to understand what phenomena are responsible for the observed isotopic anomalies, and thereby to determine the initial solar system isotopic composition. Until recently there has been no measured isotopic ratios which could not be understood in the context of reasonable physical or chemical processes acting to alter

D. C. Black

1978-01-01

18

Neutron-rich chromium isotope anomalies in supernova nanoparticles  

E-print Network

Neutron-rich isotopes with masses near that of iron are produced in type Ia and II supernovae. Traces of such nucleosynthesis are found in primitive meteorites in the form of variations in the isotopic abundance of 54Cr, the most neutron-rich stable isotope of chromium. The hosts of these isotopic anomalies must be presolar grains that condensed in the outflows of supernovae, 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 54Cr 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 54Cr-anomalies as nanoparticles, most likely spinels that show large enrichments in 54Cr relative to solar composition (54Cr/52Cr ratio >3.6xsolar). Such large enrichments in 54Cr can only be produced in supernovae. The mineralogy of the gr...

Dauphas, Nicolas; Chen, James; Roskosz, Mathieu; Papanastassiou, Dimitri; Stodolna, Julien; Guan, Yunbin; Ma, Chi; Eiler, John

2010-01-01

19

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

20

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

21

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

22

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

23

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

24

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

PubMed Central

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

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

2014-01-01

25

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

NASA Technical Reports Server (NTRS)

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

Clayton, D. D.

1978-01-01

26

Molybdenum isotope anomalies in meteorites: Constraints on solar nebula evolution and origin of the Earth  

NASA Astrophysics Data System (ADS)

The early evolution of the solar nebula involved substantial transport of mass, resulting in mixing and homogenization of isotopically diverse materials that were contributed to the solar system from multiple stellar nucleosynthetic sources. The efficiency of this mixing, as well as its timescale can be quantified by determining nucleosynthetic isotope variations among meteorites and terrestrial planets. Here we present Mo isotopic data for a wide range of samples, including Ca-Al-rich inclusions, chondrites and differentiated meteorites, as well as martian and terrestrial samples. Most meteorites are depleted in s-process Mo relative to the Earth, and only the IAB-IIICD irons, angrites and martian meteorites have terrestrial Mo isotopic compositions. In contrast, most Ca-Al-rich inclusions are enriched in r-process Mo, but one inclusion is characterized by a large s-process deficit. Molybdenum isotopic anomalies in the bulk meteorites correlate with those in Ru exactly as predicted from nucleosynthetic theory, but no obvious correlation is apparent between Mo and Ni anomalies. Therefore, s-process Mo and Ru seem to be hosted in the same carrier, which must be distinct from the carrier responsible for isotopic anomalies in the Fe-group elements (Ni, Cr, Ti). Furthermore, the isotopic heterogeneity in Mo (and other elements) contrasts with the isotopic homogeneity for Hf and Os, indicating that different s-process carriers once existed in the early solar nebula and that only some of these were heterogeneously distributed. The Mo isotopic anomalies of meteorites and their components decrease over time and with increasing size of the parent bodies, providing evidence for a progressive homogenization of the solar nebula. However, the carbonaceous chondrites exhibit larger Mo anomalies than expected for their age, indicating that they received a greater portion of material from the outer solar system (where homogenization was slow) than other meteorite parent bodies and terrestrial planets. Compared to the meteorites, Earth is enriched in s-process Mo and must have accreted from material distinct from the meteorites. Combined Mo and O isotopic data show that the composition of the Earth cannot be reconstructed by any known combination of meteorites, implying that meteorites may be inappropriate proxies for the isotopic composition of the bulk Earth. This is exemplified by the covariation of 92Mo and 142Nd anomalies in chondrites, showing that the 142Nd deficit of chondrites compared to the accessible Earth may not unequivocally be interpreted as a signature of an early differentiation of the Earth. However, further high precision isotopic data are needed to evaluate the role of chondrites in defining the isotopic composition of the Earth.

Burkhardt, Christoph; Kleine, Thorsten; Oberli, Felix; Pack, Andreas; Bourdon, Bernard; Wieler, Rainer

2011-12-01

27

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

28

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

29

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

30

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

31

Oxygen isotope anomalies of the Sun and the original environment of the Solar system  

E-print Network

We present results from a model of oxygen isotopic anomaly production through selective photodissociation of CO within the collapsing proto-Solar cloud. Our model produces a proto-Sun with a wide range of Delta_17O values depending on the intensity of the ultraviolet radiation field. Dramatically different results from two recent Solar wind oxygen isotope measurements indicate that a variety of compositions remain possible for the solar oxygen isotope composition. However, constrained by other measurements from comets and meteorites, our models imply the birth of the Sun in a stellar cluster with an enhanced radiation field and are therefore consistent with a supernova source for 60Fe in meteorites.

Jeong-Eun Lee; Edwin A. Bergin; James R. Lyons

2008-03-15

32

Carbon isotope anomalies in carbonates of the Karelian series  

NASA Astrophysics Data System (ADS)

Results are presented on carbon isotope distributions in carbonates of the Karelian complex. A highly anomalous isotopic composition was found in carbonate rocks aged from 2.6 to 1.9 b.y. In the stromatolitic carbonates of the Onega water table, delta-(C-13) reaches a value of +18 percent, while the shungite layer of the Zaonega horizon is characterized by a wide dispersion (from +7.9 to -11.8 percent). These data are in good agreement with the known geochemical boundary (about 2.2 b.y. ago) in the history of the earth.

Iudovich, Ia. E.; Makarikhin, V. V.; Medvedev, P. V.; Sukhanov, N. V.

1990-07-01

33

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

34

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

SciTech Connect

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

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

2010-01-01

35

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

NASA Astrophysics Data System (ADS)

Ca-Al-rich inclusions (CAI) are the oldest dated objects formed in the solar system and are pivotal reference points in early solar system chronology. Knowledge of their initial 182Hf/180Hf and 182W/184W is essential, not only for obtaining precise Hf-W ages relative to the start of the solar system, but also to assess the distribution of short-lived radionuclides in the early solar nebula. However, the interpretation of Hf-W data for CAI is complicated by nucleosynthetic W isotope variations. To explore their extent and nature, and to better quantify the initial Hf and W isotope compositions of the solar system, we obtained Hf-W data for several fine- and coarse-grained CAI from three CV3 chondrites. The fine-grained CAI exhibit large and variable anomalies in ?183W (?iW equals 0.01% deviation from terrestrial values), extending to much larger anomalies than previously observed in CAI, and reflecting variable abundances of s- and r-process W isotopes. Conversely, the coarse-grained (mostly type B) inclusions show only small (if any) nucleosynthetic W isotope anomalies. The investigated CAI define a precise correlation between initial ?182W and ?183W, providing a direct empirical means to correct the ?182W of any CAI for nucleosynthetic isotope anomalies using their measured ?183W. After correction for nucleosynthetic W isotope variations, the CAI data define an initial 182Hf/180Hf of (1.018±0.043)×10-4 and an initial ?182W of -3.49±0.07. The Hf-W formation intervals of the angrites D'Orbigny and Sahara 99555 relative to this CAI initial is 4.8±0.6 Ma, in good agreement with Al-Mg ages of these two angrites. This renders a grossly heterogeneous distribution of 26Al in the inner solar system unlikely, at least in the region were CAI and angrites formed.

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

2014-10-01

36

EXTREME OXYGEN AND MAGNESIUM ISOTOPIC ANOMALIES IN PRESOLAR SPINEL GRAINS FROM THE MURRAY CARBONACEOUS METEORITE. F. Gyngard1  

E-print Network

EXTREME OXYGEN AND MAGNESIUM ISOTOPIC ANOMALIES IN PRESOLAR SPINEL GRAINS FROM THE MURRAY spinel grains have been identified in several meteorites by their anomalous O isotopic compositions [1) origin [5]. Magnesium-Al spinel grains allow for relatively precise determination of Mg isotopic ratios

37

Lack of deep air convection in firn at Dome Fuji in the last glacial maximum from precise measurements of krypton isotopes  

NASA Astrophysics Data System (ADS)

Polar ice cores and occluded air provide records of past climate, atmospheric composition and glaciological conditions. In order to establish the age difference between ice and gas records (e.g. Antarctic temperature and CO2), firn densification models with reconstructed temperature and accumulation rate are generally employed for estimating the past firn thickness. However, nitrogen and argon isotopes (15N/14N and 40Ar/36Ar) from the Antarctic interior (Vostok, Dome Fuji, Dome C) for glacial periods have shown significantly smaller gravitational fractionation (equivalent to 30-40 m of firn thickness) than predicted by densification models (e.g. Caillon et al., 2003). This discrepancy may be explained if a deep air convection, which eliminates isotopic fractionation at the top part of firn, was extremely well developed during glacial periods. A modern Antarctic site having deep convective zone (23 m) has been found at a near-zero accumulation area (leeward face of Megadunes) with deep cracks (Severinghaus et al., 2010), although the magnitude is still smaller than hypothesized for the deep ice core sites in glacial maxima. Here we show, by measuring isotopic ratios of krypton (Kr) as well as argon and nitrogen from Dome Fuji ice core, that a thick convective zone was not developed during the last glacial maximum (LGM) at this site. Because heavy noble gases such as Kr and Xe have smaller diffusivities than N2 and Ar, they are less fractionated in deep firn if strong convective mixing exists. We developed a method to simultaneously measure 15N/14N, 40Ar/36Ar and 86Kr/82Kr in ice-core air and applied it to Dome Fuji ice core over the last ~30,000 years including the LGM and current interglacial period (Holocene). When normalized to unit mass difference and corrected for thermal signal by using N2 and Ar isotopic records, the differences between N2 and Kr isotopic ratios are similar for the Holocene and LGM, suggesting that convection zone in LGM was similar to today at this site. The gravitational enrichment in LGM is smaller than those in Holocene, suggesting that firn was thinner in LGM. Revisiting the data from Vostok (Severinghaus et al., AGU 2006 Fall Meeting) and accounting for thermal signal by using Ar isotopes, the inferred convective zone for the penultimate glacial maximum at Vostok is also small. These data imply that firn in Antarctic inland was actually thinner during glacial periods, which is opposite to predicted by firn densification models. Firn densification models produce thicker firn in glacial periods because densification rate is strongly dependent on temperature. Reduced accumulation rate acts to thin the firn and thus partly compensate the effect of temperature. Our data suggest that firn densification rate in coldest and driest conditions are severely underestimated by current models. The origin of this problem may lie in relative contributions of temperature and accumulation rate, or missing physics such as recently proposed effect of dust (Hörhold et al., 2012), on firn densification rates.

Kawamura, K.; Severinghaus, J. P.

2012-12-01

38

Cross sections for the proton-induced production of krypton isotopes from Rb, Sr, Y, and Zr for energies up to 1600 MeV  

NASA Astrophysics Data System (ADS)

The production by proton-induced reactions of stable and long-lived Kr-isotopes from Rb, Sr, Y, and Zr was investigated by using isotope dilution mass spectrometry of targets irradiated at PSI/CH, TSL/S and LNS/F. Cumulative cross sections were determined for energies between 81 and 1600 MeV, between 15.4 and 1600 MeV, and between 70 and 1600 MeV for the target element Rb, Sr, and Y, respectively. For Zr, three energies of 156, 569 and 1200 MeV were investigated. As a by-product, cross sections for the production of short-lived radionuclides from Rb are reported which were measured by ?-spectrometry prior to mass spectrometry. Flux determination and absolute calibration of cross sections was done by the reaction 27Al(p,3p3n) 22Na. The new experimental data are consistent with a large database established during recent years for describing the interactions of cosmic ray protons with matter. They provide a first complete basis for model calculations of cosmogenic krypton in stony meteoroids and planetary surfaces. For the target element Rb we report the first measurements at all. For Sr, only one earlier measurement existed. For Y, our data confirm earlier measurements up to 200 MeV and extend the data set up to 1600 MeV, while for Zr three new energy points complement and check the consistency of the new investigations with earlier work from Bordeaux. The new experimental data are compared with theoretical excitation functions calculated on an a priori basis using the hybrid model of preequilibrium reactions, an intranuclear cascade/evaporation model in form of the HET/KFA2 code and the semi-empirical systematics by Silberberg, Tsao and coworkers. The differences between theories and experiments demonstrate severe shortcomings of the predictive power of existing models and emphasize the importance of experimental determinations if high-quality data are required for applications.

Gilabert, E.; Lavielle, B.; Neumann, S.; Gloris, M.; Michel, R.; Schiekel, Th.; Sudbrock, F.; Herpers, U.

1998-11-01

39

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

PubMed Central

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

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

2013-01-01

40

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

41

Isotopic Anomalies in a Uranium Cluster Formed by Lais  

NASA Astrophysics Data System (ADS)

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

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

42

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

43

Carbon stars and isotopic BA anomalies in meteoritic SiC grains  

NASA Astrophysics Data System (ADS)

New calculations of s-processing in TP-AGB stars of low mass based on an updated compilation of neutron capture cross sections are presented. It is shown how the reproduction of solar abundances for the s-isotopes of Ba requires a special choice of neutron capture cross sections of Ba-136 and Ba-138. It is further shown how agreement between the predictions of He shell nucleosynthesis and the Ba isotopic mixture of the G-component in SiC can be obtained, once C-stars with mean neutron exposures lower than that required to fit the solar main component are considered. Problems related to the interpretation of other isotope anomalies in SiC are also examined.

Gallino, R.; Raiteri, C. M.; Busso, M.

1993-06-01

44

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

SciTech Connect

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

Savarino, J.; Morin, S.; Baroni, M. [Laboratoire de Glaciologie et Geophysique de l'Environnement (LGGE), CNRS-Universite Joseph Fourier Grenoble, 38400 Grenoble (France); Bhattacharya, S. K. [Physical Research Laboratory, Navrangpura, 380009 Ahmedabad (India); Doussin, J.-F. [Laboratoire Interuniversitaire des Systemes Atmospheriques (LISA), CNRS-Universite Paris 7-Denis Diderot, 94010 Creteil (France)

2008-05-21

45

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

PubMed

Atmospheric nitrate shows a large oxygen isotope anomaly (Delta 17 O), characterized by an excess enrichment of 17 O over 18 O, similar to the ozone molecule. Modeling and observations assign this specific isotopic composition mainly to the photochemical steady state that exists in the atmosphere between ozone and nitrate precursors, namely, the nitrogen oxides (NOx=NO+NO2). However, this transfer is poorly quantified and is built on unverified assumptions about which oxygen atoms of ozone are transferred to NO(x), greatly weakening any interpretation of the nitrate oxygen isotopic composition in terms of chemical reaction pathways and the oxidation state of the atmosphere. With the aim to improve our understanding and quantify how nitrate inherits this unusual isotopic composition, we have carried out a triple isotope study of the reaction NO+O3. Using ozone intramolecular isotope distributions available in the literature, we have found that the central atom of the ozone is abstracted by NO with a probability of (8+/-5)%(+/-2 sigma) at room temperature. This result is at least qualitatively supported by dynamical reaction experiments, the non-Arrhenius behavior of the kinetic rate of this reaction, and the kinetic isotope fractionation factor. Finally, we have established the transfer function of the isotope anomaly of O3 to NO2, which is described by the linear relationship Delta 17 O(NO2)=A x Delta 17 O(O3)+B, with A=1.18+/-0.07(+/-1 sigma) and B=(6.6+/-1.5)[per thousand](+/-1 sigma). Such a relationship can be easily incorporated into models dealing with the propagation of the ozone isotope anomaly among oxygen-bearing species in the atmosphere and should help to better interpret the oxygen isotope anomaly of atmospheric nitrate in terms of its formation reaction pathways. PMID:18500861

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

2008-05-21

46

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

47

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 (0.4–3.9‰). The unique O-isotopic composition mechanistically describes the atmospheric heterogeneous chemical reaction on aerosol surfaces. Concomitant laboratory experiments define the transfer of ozone isotopic anomaly to carbonates via hydrogen peroxide formation when O3 reacts with surface adsorbed water. This previously unidentified chemical reaction scenario provides an explanation for production of the isotopically anomalous carbonates found in the SNC (shergottites, nakhlaites, chassignites) Martian meteorites and terrestrial atmospheric carbonates. The anomalous hydrogen peroxide formed on the aerosol surfaces may transfer its O-isotopic signature to the water reservoir, thus producing mass independently fractionated secondary mineral evaporites. The formation of peroxide via heterogeneous chemistry on aerosol surfaces also reveals a previously undescribed oxidative process of utility in understanding ozone and oxygen chemistry, both on Mars and Earth. PMID:21059939

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

2010-01-01

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

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

PubMed

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

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

2013-01-01

50

Hyperfine spectra of the radioactive isotopes Kr81 and Kr85  

NASA Astrophysics Data System (ADS)

Isotope shifts and hyperfine constants are reported for the radioactive isotopes Kr81 and Kr85 and the stable isotope Kr83. The previously unreported nuclear moments of Kr81 were determined to be ?I=-0.909(4) nuclear magneton and Q=+0.630(13) b from the hyperfine constants. This work increases the number of transitions for which Kr85 hyperfine constants and isotope shifts have been measured from 1 to 4. The hyperfine anomaly for krypton reported in the previous measurement of Kr85 hyperfine constants [H. Gerhardt et al., Hyperfine Interact. 9, 175 (1981)] is not supported by this work. The isotope shifts and hyperfine constants of Kr83 measured in this work are in excellent agreement with previous work. Saturation spectroscopy was used to study transitions from krypton's metastable 1s5 state to the 2p9, 2p7, and 2p6 states. In saturation spectra, different line shapes were observed for the even- and odd-mass krypton isotopes. This even- versus odd-line-mass shape difference can be explained using the large cross section that has been reported for collisional transfer of the 1s5 state excitation between krypton atoms. Two-color two-photon laser-induced fluorescence was used to measure the hyperfine spectra of the 1s5-4d'4 transition using the 2p9 state as the intermediate state. This technique proved to be more sensitive than saturation spectroscopy.

Cannon, B. D.

1993-02-01

51

Krypton and xenon in the atmosphere of Venus  

NASA Astrophysics Data System (ADS)

The paper reports a determination by the Pioneer Venus large probe neutral mass spectrometer of upper limits to the concentration of krypton and xenon along with most of their isotopes in the atmosphere of Venus. The upper limit to the krypton mixing ratio is estimated at 47 ppb, with a very conservative estimate at 69 ppb. The probable upper limit to the sum of the mixing ratios of the isotopes Xe-128, Xe-129, Xe-130, Xe-131, and Xe-132 is 40 ppb by volume, with a very conservative upper limit three times this large.

Donahue, T. M.; Hoffman, J. H.; Hodges, R. R.

1981-05-01

52

Pelagic anomalies and isotope signatures of molybdenum in temperate tidal systems  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

53

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

NASA Astrophysics Data System (ADS)

Sulfate aerosols, unlike greenhouse gases, contribute to global cooling by acting as cloud condensation nuclei in the troposphere and by directly reflecting solar radiation in the stratosphere. To understand the long-term effect of natural and anthropogenic sulfate aerosol on the climate cycle, it is critical to obtain a clear picture of the factors controlling the transport and transformation of sulfate aerosols. We have employed both oxygen triple isotopes and sulfur quadruple isotopes on sulfates from Antarctic ice samples to define the oxidation history, long range transport dynamics, and sources of sulfate aerosols over time. The measurements are used to deconvolve the impact of natural and anthropogenic aerosols on the stratospheric sulfate aerosol composition. Sulfate aerosols were extracted from a snow pit at the South Pole (1979-2002) with a high resolution temporal (6 month) record of the winter and summer seasons covering two largest volcanic events, Pinatubo and El-chichon and three largest ENSO events of the century. All three oxygen and four sulfur isotopes were measured on the extracted sulfate (Shaheen et al., 2013). The high temperature pyrolysis (1000oC) of silver sulfate yielded O2 and SO2. The oxygen triple isotopic composition of the O2 gas was used to determine the oxidation history of sulfate aerosol and SO2 gas obtained during this reaction was utilized to measure sulfur quadruple isotopes following appropriate reaction chemistry (Farquhar et al., 2001). The data revealed that oxygen isotope anomalies in Antarctic aerosols (?17O = 0.8-3.7‰) from 1990 to 2001 are strongly linked to the variation in ozone levels in the upper stratosphere/lower stratosphere. The variations in ozone levels are reflective of the intensity of the ENSO events and changes in relative humidity in the atmosphere during this time period. Sulfate concentrations and sulfur quadruple isotopic composition and associated anomalies were used to elucidate the sources of sulfate aerosol to the stratosphere. The new results demonstrate that combined O-triple isotopes and S-quadruple isotopes may help to recognize paleo ENSO events and their impact on the oxidation history of sulfate aerosols. 1. R. Shaheen, M. A., T. Jackson, J. McCabe, J. Savarino, M. H. Thiemens. (2013) A Window to the Paleoclimate- Tales of Volcanoes and El-Ninño Southern Oscillations with the Oxygen Isotope Anomaly of Sulfate Aerosols, Proceedings of the National Academy of Sciences of the United States of America. 2. Farquhar, J., Savarino, J., Airieau, S., and Thiemens, M. H. (2001) Observation of wavelength-sensitive mass-independent sulfur isotope effects during SO2 photolysis: Implications for the early atmosphere, Journal of Geophysical Research-Planets 106, 32829-32839.

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

2013-12-01

54

Investigating atmospheric transport processes using cosmogenic 35S and oxygen isotopic anomaly (?17O) in sulfate  

NASA Astrophysics Data System (ADS)

Sulfate aerosols have been recognized to possess hazardous impact on both climate and human health. Improved understanding of the SO2 residence time and sulfate aerosol transport is needed for assessing its influences on climate. Cosmogenically produced 35S (half-life~87 days)1 measurements have been used to understand the atmospheric transport process, boundary layer dynamics and its effect on the tropospheric SO2 oxidation rate constant. Our method involves determining 35S in gaseous SO2 and aerosol sulfate samples collected twice a week at Scripps Institute of Oceanography Pier (La Jolla, CA) for a year along with the determination of oxygen isotopes in both coarse and fine particle samples. The oxygen isotopes measurement in sulfate and 35S measurements were done by isotope ratio mass spectrometry and low-noise liquid scintillation spectroscopy2, respectively. The data show that 35S activity is significantly different for coarse and fine particles, with the latter possessing higher activity as it is mainly produced from the gas phase oxidation of SO2 at higher altitude. The fluctuation in 35S activity in fine particles indicates mixing of air masses from higher altitude. The coarse particles show nearly constant 35S activity which is either due to the constant uptake rate of SO2 by sea salt aerosol or the coagulation of fine particles together. The normalized activity 35S/S is about 5 times higher in both coarse and fine particles during Santa Ana wind event. Santa Ana wind is characterized by low humidity (<20%) and relatively high temperature and may have an impact on SO2 oxidation. We are investigating the sulfate oxygen isotope signature and the correlation between oxygen anomaly and 35S activity in sulfate. 1. Lal D., P. K. Malhotra, and B. Peters, On the production of radioisotopes in the atmosphere by cosmic radiation and their application in meteorology, J. Atmos. AndTerrest. Phys. 12, 306, 1958 2. Brother, L.A., G. Dominguez, A. Abramian, A. Corbin, Ben Bluen, and M. H. Thiemens, Otimized low-level liquid scintillation spectroscopy of 35S for atmospheric and biogeochemical chemistry applications, Proceedings National Acad. Sci. 107, 5311, 2010

Hill-Falkenthal, J. C.; Pandey, A.; Coupal, E.; Kim, S. D.; Dominguez, G.; Thiemens, M. H.

2010-12-01

55

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

E-print Network

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

Lassen, Jens

1996-01-01

56

Measurements and kinetics modeling of the O2/CO2 dependence of the oxygen-17 isotope anomaly in carbon dioxide  

NASA Astrophysics Data System (ADS)

Ozone formed in the atmosphere and the laboratory is not only unusually enriched in the heavy rare isotopes of oxygen for the small difference in masses for 17O and 18O relative to 16O, but the enrichments are also non-mass-dependent, with a 17O anomaly of ?17O ? 40 per mil (where ?17O = ln17O - 0.52 x ln18O). Unusual kinetic isotope effects in the three-body ozone formation reaction were determined to be the source of the anomalous oxygen isotopic composition (Janssen et al., 1999, Mauersberger et al.,1999). Theoretical work has suggested that the observed non-mass-dependent enrichments emerge from dynamically driven, non-statistical effects resulting from the short lifetime of the rovibrationally excited O3* complex or its collisional stabilization to stable O3, particularly for the symmetric over the asymmetric isotopologues (e.g., Gao and Marcus 2001). Stratospheric CO2 also has an anomalous oxygen isotopic composition that is thought to be transferred from ozone by photolysis to form O(1D) followed by the O(1D)+CO2 isotope exchange reaction, although some have postulated that an additional anomalous isotope effect must also exist in at least one of the other reactions for this system (e.g., Shaheen et al. 2007). To further investigate the anomalous isotopic compositions ofCO2, we have conducted additional photochemical experiments measuring the enrichments of 17O and 18O in CO2 relative to O2 in irradiated mixtures of O2 and CO2. We then compared these and previous results from other laboratories with a photochemical kinetics model using both measured and derived kinetic isotope effects in ozone formation. Our model can quantitatively predict the enrichments and 17O anomaly in both ozone and CO2 without additional non-mass-dependent isotope effects for pressures and O2/CO2 mixing ratios relevant to the stratosphere. However, the model cannot predict the relative enrichments or isotope anomaly in CO2 for our or previous experiments at low O2/CO2 ratios, so a number of additional hypothetical mechanisms that have isotope effects with possible O2/CO2dependences were introduced into the model. While including some of these mechanisms does result in a decrease in the relative enrichments in CO2 as the O2/CO2 ratio decreases, none of the mechanisms in the model can predict the large change observed experimentally. While the underlying mechanism(s) of the O2/CO2 dependence thus remains an open question, the model results also point to additional measurements of the pressure and bath gas dependence of isotope effects in both ozone formation and other reactions in this system that could help to resolve the model-measurement discrepancies at higher pressures and at low O2/CO2 ratios.

Wiegel, A. A.; Boering, K. A.

2012-04-01

57

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

58

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

59

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

60

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, Frédéric

2013-12-01

61

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

62

An ultraviolet laser microprobe for the in situ analysis of multisulfur isotopes and its use in measuring Archean sulfur isotope mass-independent anomalies  

NASA Astrophysics Data System (ADS)

A laser fluorination microprobe system has been constructed for high-accuracy, high-precision multisulfur isotope analysis with improved spatial resolution. The system uses two lasers: (a) a KrF excimer laser for in situ spot analysis by ultraviolet (UV) photoablation with ? = 248 nm and (b) a CO 2 laser for whole-grain analysis of powdered samples by infrared heating at ? = 10.6 ?m. A CO 2 laser is necessary for the analysis of interlaboratory isotope reference materials because they are supplied as powders. The ? 34S and ? 33S compositions of reference materials measured with a CO 2 laser fluorination system agree (±0.2‰, 1?) with the recommended values by the Sulfur Isotope Working Group of the International Atomic Energy Agency (Ding et al., 2001; Taylor, in press). The precision of replicate analyses of powdered sulfide minerals with the CO 2 laser is typically ±0.2‰ (1?) for ? 34S. The in situ fluorination of sulfides with a KrF excimer laser (? = 248 nm) was validated by comparison of measurements of side-by-side laser craters and powders excavated from drill holes. Powders from drill holes were analyzed with the CO 2 laser. In situ laser craters and drill hole powders give the same ? 34S V-CDT and ? 33S V-CDT values within 0.2‰. The ? 34S V-CDT and ? 33S V-CDT values of both powders and in situ analyses are independent of F 2 gas pressure over a range of 15 to 65 torr. No dependence of ? 34S V-CDT and ? 33S V-CDT values on UV laser energy fluence has been observed. Mineral-specific fractionation of sulfur isotopes in analyzing pyrite, sphalerite, galena, troilite, and chalcopyrite has not been observed with a KrF excimer laser (? = 248 nm). Test analyses with an ArF excimer laser (? = 193 nm), however, gave fractionated sulfur isotope ratios. A range of ? 33S anomalies of from - 1.5 to +3.0‰ in Archean samples from the North Pole district, Pilbara Craton, Australia, and from black shale of the Lokamonna Formation, South Africa, were verified by in situ analysis of individual pyrite grains with a KrF excimer laser. These results show that a combination of high-accuracy, high-precision analyses with improved spatial resolution permits locating and analyzing host minerals of non-mass-dependent sulfur isotope anomalies.

Hu, Guixing; Rumble, Douglas; Wang, Pei-ling

2003-09-01

63

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

USGS Publications Warehouse

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

Tatsumoto, M.; Nakamura, Y.

1991-01-01

64

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

65

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 VOC’s, can interact with aerosol surfaces to produce new compounds. Oxygen triple isotopic compositions of atmospheric carbonates have been used for the first time to track heterogeneous chemistry at the aerosol surfaces and to resolve a chemical mechanism that only occurs on particle surfaces. Fine and coarse aerosol samples were collected on filter papers in La Jolla, CA for one week. Aerosol samples were digested with phosphoric acid and released CO2 was purified chromatographically and analyzed for O isotopes after fluorination. Data indicated oxygen isotopic anomaly (?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

66

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.

67

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

68

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

69

Analogue or Anomaly? Ocean Drilling Evidence From Marine Isotope Stage 11  

NASA Astrophysics Data System (ADS)

Ocean Drilling makes it possible to recover high quality sedimentary archives from important earlier geologic intervals, such as Marine Isotope Stage 11 (MIS 11), approximately 400 ky BP. Similar orbital configurations and comparable atmospheric greenhouse gas concentrations have led to the suggestion that MIS 11 is a suitable, possibly the best, geological analogue for the natural development of Holocene and future climate. Yet the anomalously strong climate response during MIS 11 in the absence of strong seasonal insolation changes has long been described as the "the stage 11 problem". Here we review evidence from a number of widely distributed ODP locations indicating that MIS 11 was not likely to have been a "super interglacial" interval characterized by both significantly higher sea-level and global temperatures. We discuss the stability and strength of the meridional overturning circulation as a potential compensator for the limited insolation. We present detailed faunal, ice-rafting, and isotopic records from North Atlantic ODP Sites 980 (55° N, 15° W, 2.2km), 983 (60° N, 24° W, 2.0km), and 984 (61° N, 25° W, 1.6 km) confirm the relative stability of MIS 11 on millennial timescales, and document that the transition to the more characteristic instability of the Pleistocene occurred dramatically and abruptly following the warm interval. In addition, we consider a variety of tuning techniques and apply a new independent dating approach to deep-sea sediment sequences to show that the regional stable warmth of MIS 11 in the North Atlantic long outlasted the elapsed portion of the Holocene. Next, we address the question of possibly higher sea levels during MIS 11 with isotopic evidence from ODP Site 925 (4° N, 43° W, 3.0km) in the Tropical Atlantic, ODP Site 1242 (8° N, 84° W, 1.4km) in the eastern tropical Pacific, and ODP Site 806 (0° N, 159° W, 2.5km) in the western tropical Pacific. Finally, we discuss possible ways to reconcile the apparently conflicting evidence in existing records of sea-level, temperature, and variability during MIS 11.

McManus, J. F.; Oppo, D. W.; Cullen, J. L.; Huybers, P.; Federici, L.

2003-12-01

70

On the origin of the Ca-Ti-Cr isotopic anomalies in the inclusion EK-1-4-1 of the Allende Meteorite  

E-print Network

In the framework of our investigation to explain the nucleosynthesis origin of the correlated Ca-Ti-Cr isotopic anomalies in the Ca-Al-rich ''FUN'' inclusion EK-1-4-1 of the Allende meteorite, the nuclear-physics basis in the neutron-rich N=28 region has been updated by including recent experimental data on beta-decay properties and microscopic predictions of neutron-capture cross sections. Charged-particle and subsequent r-process calculations within an entropy-based approach were performed using a complete reaction network. It is shown that there exist two astrophysical scenarios within which the observed isotopic anomalies can be reproduced simultaneously; one at low entropies (about 10) which confirms the earlier suggestrd Sn Ia mechanism, and another at high entropies (about 150) which could be compatible with the neutrino-wind scenario of a SN II.

K. -L. Kratz; W. Boehmer; C. Freiburghaus; P. Moeller; B. Pfeiffer; T. Rauscher; F. -K. Thielemann

2000-12-11

71

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

72

Krypton-85 in the atmosphere  

E-print Network

Measurement results are presented on 85Kr content in the atmosphere over the European part of Russia in 1971-1995 based on the analysis of the commercial krypton, which is separated from air by industrial plants. Our results are by 15 per cent lower then 85Kr activites observed over West Europe. According our prediction by 2030 85Kr content in the atmosphere over Europe will amount to 1,5-3 Bq in m3 air. Average 85Kr release to the atmosphere from regeneration of spent nuclear fuel (SNF) is estimated, some 180 TBq per a ton SNF. It is advisable to recommence monitoring of 85Kr content within Russia.

A. T. Korsakov; E. G. Tertyshnik

2013-07-09

73

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

NASA Astrophysics Data System (ADS)

We studied Albian-Cenomanian paleoceanic carbonate-siliceous deposits of the Kamchatsky Mys Peninsula (Eastern Kamchatka, Russia). They are deposited in association with pillow-basalts and hyaloclastites. The thickness of the studied section is about 10 m. The deposits are represented mainly by rhythmical intercalation of red-brown radiolarian jaspers, pink nannoplankton limestones as well as siliceous limestones. In the middle and upper parts of the section there are two beds enriched by organic carbon. The largest organic matter contents in this beds amount to 68%. The calculated values of the hydrogen and oxygen indexes indicate that the carbonaceous beds consist of marine organic matter. The accumulation of the carbonaceous beds reflects oxygen depletion in intermediate oceanic waters (ocean anoxic events, OAE). The structure of the studied section emphasizes its similarity to the contemporary deposits recovered by ODP and DSDP sites on Hess and Shatsky Rises. Two orders of rhythmicity were observed in the section. The rhythmicity of the first order (average thickness of a rhythm is 5-7 cm) is an alternation of reddish brown radiolarian jaspers and pink nannofossil limestones. The rhythmicity of the second order is characterized by an increase in thickness of the jasper or limy layer in every 4th-5th rhythm of the first order and marked by an elevation of the silica content in calcareous layers. The rhythmicity formation can be attributed to fluctuation of astronomical parameters (Milankovitch cycles) with periods of 21 and 100 kyr. The character of atmospheric circulation and ocean currents served as transmission link. The section was sampled layerwise and more than 100 samples were taken. The radiolarians were extracted from the samples of jaspers and siliceous limestones lying between carbonaceous beds. The educed radiolarian complexes allowed us to define the age of the deposits as Cenomanian. For more detailed dating of members of the section we have determined contents of carbon and oxygen stable isotopes in limestones and have compared the received results to isotope curves of other regions. In studied section the curve of d13C is characterized by a clearly expressed positive shift at the level of the lower carbonaceous bed. Below it and in the overlapping stratum of siliceous limestone (1 cm thickness) d13C has the values of 1.9-2.1 pro mille and above it d13C increases up to 2.5-3 pro mille. The precise d13C maximum after a sharp shift is correlatable with the form of a d13C curve of the Middle Cenomanian Tethyan sections. Accordingly, it is possible to assert, that the lower carbonaceous bed was formed during the mid-Cenomanian anoxic event (MCE). Gradual increase of d13C in the upper part of our section is similar to change of d13C in Upper Cenomanian fragments of Tethyan sections, i.e. the lower carbonaceous bed corresponds to anoxic event at the Cenomanian/Turonian boundary (OAE2). Neutron activation analysis indicates increased up to 9 ppb concentration of Ir at the bottom of the lower carbonaceous bed (inorganic part of the sample was analyzed comprising 46% of the bulk rock). This anomaly correlates in the studied section with a positive shift of d13C. Taking into account radiolarian age data this allows to correlate the anomaly with the MCE. A source of iridium and other elements of the platinum group could be basalts and hyaloclastites from the eruptions during the sedimentation period. Anoxic conditions promoted deposit enrichment in ore elements. This work was supported by the RFBR (No. 10-05-00065).

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

2012-04-01

74

Krypton based adsorption type cryogenic refrigerator  

NASA Technical Reports Server (NTRS)

Krypton and monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an absorption type refrigerator to improve refrigeration efficiency and operational longevity.

Jones, Jack A. (inventor); Schember, Helene (inventor)

1987-01-01

75

Krypton based adsorption type cryogenic refrigerator  

NASA Technical Reports Server (NTRS)

Krypton and a monolithic porous carbon such as Saran carbon are used respectively as the sorbate and sorbent of an adsorption type refrigerator to improve refrigeration efficiency and operational longevity.

Jones, Jack A. (Inventor); Schember, Helene R. (Inventor)

1989-01-01

76

Seismically triggered anomalies in the isotope signatures of mantle-derived gases detected at degassing sites along two neighboring faults in NW Bohemia, central Europe  

NASA Astrophysics Data System (ADS)

Vogtland and NW Bohemia region is known for its earthquake swarms; the most intensive swarm since 1985/86 occurred in October 2008. To find further indications for the interaction of ascending mantle-derived fluids and the occurrence of earthquake swarms, detailed fortnightly studies of gas compositions (CO2, N2, Ar, He, H2, and CH4) and isotope ratios (?13C, ?15N, and 3He/4He) were carried out between October 2008 and April 2011 at four locations close to the Nový Kostel focal zone and at the Wettinquelle spring (Bad Brambach). From the start of the 2008 earthquake swarm seismically induced isotope-geochemical anomalies were recorded at locations along the Po?atky-Plesná fault zone (PPZ) and were, for the first time, also found at degassing locations on the Mariánské Lázn? fault zone (MLF). Variations were observed in both the temporal and spatial distributions of the anomalies as well in anomaly strengths, probably due to the positions of these fault zones relative to the focal zone, and to differences in fluid migration pathways. Prior to both the 2000 and 2008 swarms, 3He/4He ratios > 6 Ra were recorded at the Bublák mofette. These anomalous pre-seismic 3He/4He ratios suggest that both the 2000 and 2008 swarms may have been associated with the supply of fresh magma from a less degassed reservoir in the lithospheric mantle. The temporal ?13CCO2 pattern from detailed studies at Bublák between 2005 and 2011 indicates progressive magma degassing, as well as seismically induced variations in the ?13C, providing additional support to the interpretation derived from the 3He/4He ratios.

Bräuer, Karin; Kämpf, Horst; Strauch, Gerhard

2014-07-01

77

Late Quaternary stable isotope record and meltwater discharge anomaly events to the south of the Antarctic Polar Front, Drake Passage  

Microsoft Academic Search

Marine isotope stages (MISs) 1 to 5 were identified in the planktonic d 18O record in sediment core DP00-02 just south of the Antarctic Polar Front in the Drake Passage, Antarctica. The oxygen isotope record, based on Neogloboquadrina pachyderma sinistral, is correlated with the contemporaneous global d 18O stratigraphy. Marked deviations from the global climate curve suggest a local\\/regional overprint,

SungHo Bae; HoIl Yoon; Byong-Kwon Park; Yeadong Kim

2003-01-01

78

Introducing krypton NMR spectroscopy as a probe of void space in solids.  

PubMed

A wealth of information about porous materials and their void spaces has been obtained from the chemical shift data in (129)Xe NMR spectroscopy during the past decades. In this contribution, the only NMR active, stable krypton isotope (83)Kr (spin I = (9)/(2)) is explored as a novel probe for porous materials. It is demonstrated that (83)Kr NMR spectroscopy of nanoporous or microporous materials is feasible and straightforward despite the low gyromagnetic ratio and low abundance of the (83)Kr isotope. The (83)Kr line width in most of the studied cases is quadrupolar dominated and field-strength independent. A significant exception was found in calcium-exchanged zeolites where the field dependence of the line width indicates a distribution of isotropic chemical shifts that may be caused by long-range disorder in the zeolite structure. The (83)Kr chemical shifts observed in the investigated materials display a somewhat different behavior than that of their (129)Xe counterparts and should provide a great resource for the verification or refinement of current (129)Xe chemical shift theory. In contrast to xenon, krypton with its smaller atomic radius has been demonstrated to easily penetrate the porous framework of NaA. Chemical shifts and line widths of (83)Kr are moderately dependent on small fluctuations in the krypton loading but differ strongly between some of the studied samples. PMID:15701030

Horton-Garcia, Charlene F; Pavlovskaya, Galina E; Meersmann, Thomas

2005-02-16

79

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

NASA Technical Reports Server (NTRS)

A hypothesis is presented to the effect that the distinctive morphological characteristics and comparatively simple Si isotope systematics identify the platy SiC crystals as a genetically related family, formed around a single isotopically heterogeneous presolar star on an association of related stars. The enrichments in C-13 and the Si isotope systematics of the platy SiC are broadly consistent with theoretical models of nucleosynthesis in low-mass, carbon stars on the ASG. The Si isotope array most plausibly reflects mixing between (Si-28)-rich material, inherited from a previous generation of stars, and material enriched in Si-29 and Si-30, produced in intershell regions by neutron capture during He-burning. The absence of a correlation between the Si and C isotopic compositions of the SiC suggests either episodic condensation of SiC, extending over several thermal pulses, in the atmosphere of a single star, or the derivation of the SiC from several stars characterized by different rates of C-13 production.

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

1991-01-01

80

1, 393412, 2004 Carbon isotope  

E-print Network

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

Boyer, Edmond

81

Hot subdwarf stars in close-up view. IV. Helium abundances and the 3He isotopic anomaly of subdwarf B stars  

NASA Astrophysics Data System (ADS)

Atmospheric parameters and helium abundances of 44 bright subdwarf B stars have been determined. More than half of our sample consists of newly discovered stars from the Edinburgh Cape survey. We showed that effective temperatures and surface gravities can be derived from high resolution echelle spectra with sufficient accuracy. Systematic uncertainties have been determined by comparing the parameters derived from the high resolution data with the ones derived from medium resolution spectra. Helium abundances have been measured with high accuracy. Besides the known correlation of helium abundance with temperature, two distinct sequences in helium abundance have been confirmed. Significant isotopic shifts of helium lines due to an enrichment in 3He have been found in the spectra of 8 subluminous B stars (sdBs). Most of these stars cluster in a small temperature range between 27 000 K and 31 000 K very similar to the known 3He-rich main sequence B stars, which also cluster in such a small strip, but at different temperatures. Both the helium sequences and the isotopic anomaly are discussed. Tables 1 and 2 and Appendix A are available in electronic form at http://www.aanda.org

Geier, S.; Heber, U.; Edelmann, H.; Morales-Rueda, L.; Kilkenny, D.; O'Donoghue, D.; Marsh, T. R.; Copperwheat, C.

2013-09-01

82

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

PubMed

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

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

1991-01-01

83

ISOTOPES  

E-print Network

over ammonia-hydrogen exchange include higher separationAmmonia-hydrogen Exchange This reaction has both a larger separationammonia) fraction with which it is in isotopic equilibrium, necessitating the separation

Lederer, C. Michael

2013-01-01

84

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

NASA Astrophysics Data System (ADS)

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

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

1988-05-01

85

Chromium isotope anomaly in an impactite sample from the El'gygytgyn structure, Russia: Evidence for a ureilite projectile?  

NASA Astrophysics Data System (ADS)

The 3.6 Ma, 18-km-diameter El'gygytgyn impact structure (Arctic Russia) is unique among the currently known terrestrial impact craters in that it is the only one that was formed in acid volcanic rocks. Previous analyses of impactites from El'gygytgyn showed minor enrichments of the siderophile elements, including Ir, which, together with distinct Cr enrichments, gave rise to speculation that an achondritic projectile was involved. We studied the major and trace element composition in samples from the new ICDP drill core obtained near the center of the structure, as well as the chromium isotopic composition of an impact glass sample collected on the surface. Several suevitic breccias from the upper part of the suevite sequence in the drill core show higher Cr and Ni contents compared with felsic volcanic rocks in the lower part of the core and from surface samples. However, it is difficult to unambiguously establish a meteoritic component from trace element data, as input from (rare) mafic target rocks is a possibility. In contrast, the Cr isotopic composition of the impact glass sample yielded a nonterrestrial ?54Cr value of -0.72 ± 0.31 (2 std. err.). This negative ?54Cr is different from known carbonaceous chondrite values (?54Cr of +0.95 to +1.65), but is nearly identical to reported values for ureilites (approximately -0.77). The value is, however, also within analytical error of eucrites (approximately -0.38) and ordinary chondrites (approximately -0.42). Given the chemical signatures found in previous analyses of El'gytgytgyn impactites and the similarity of our Cr isotopic data to ureilites, we suggest that the impacting asteroid could have been an F-type asteroid of mixed composition, similar to the recent Almahata Sitta fall in Sudan.

Foriel, Julien; Moynier, Frederic; Schulz, Toni; Koeberl, Christian

2013-07-01

86

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

87

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

88

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

89

The radioactivity of atmospheric krypton in?1949–1950  

PubMed Central

The chemical element krypton, whose principal source is the atmosphere, had a long-lived radioactive content, in the mid-1940s, of less than 5 dpm per liter of krypton. In the late 1940s, this content had risen to values in the range of 100 dpm per liter. It is now some hundred times higher than the late 1940 values. This radioactivity is the result of the dissolving of nuclear fuel for military and civilian purposes, and the release thereby of the fission product krypton-85 (half-life = 10.71 years, fission yield = 0.2%). The present largest emitter of krypton-85 is the French reprocessing plant at Cap-de-la-Hague. PMID:11607731

Turkevich, Anthony; Winsberg, Lester; Flotow, Howard; Adams, Richard M.

1997-01-01

90

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

NASA Astrophysics Data System (ADS)

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

Pálfy, J.; Zajzon, N.

2012-04-01

91

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 (200±35 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

92

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

93

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

94

The Liquid Krypton Hugoniot at Megabar Pressures  

NASA Astrophysics Data System (ADS)

Krypton is an ideal candidate to study multi-Mbar pressure effects on elements with filled-shell electron configurations. Few experimental data on Kr at high pressures exist, however, with prior Hugoniot data limited to below 1 Mbar. Similar to liquid xenon [1], the current Kr equation of state (EOS) models agree with the data and each other below 1 Mbar, but diverge with increasing pressure. We examine the liquid Kr Hugoniot up to 8 Mbar by using density functional theory (DFT) methods and by performing shock compression experiments on the Sandia Z -- accelerator. Our initial DFT Kr Hugoniot calculations indicated the standard PAW potential is inadequate at the high pressures and temperatures occurring under strong shock compression. A new Kr PAW potential was constructed giving improved scattering properties of the atom at high energies. The Z Hugoniot measurements above 1 Mbar validated the DFT results and the pseudo-potential. The DFT and Z results suggest that the current EOS models require some modifications. [1] S. Root et al., PRL, 105, 085501 (2010). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U. S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Root, Seth; Magyar, Rudy J.; Mattsson, Ann E.; Hanson, David L.; Mattsson, Thomas R.

2011-06-01

95

Kinetic modelling of krypton fluoride laser systems  

SciTech Connect

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

Jancaitis, K.S.

1983-11-01

96

Factors Affecting the Efficiency of Krypton Hall Thrusters  

NASA Astrophysics Data System (ADS)

The use of krypton as a propellant for Hall thrusters is attractive for NASA missions that require both high-specific impulse and high-propellant throughput. Due to its low molecular weight, the theoretical specific impulse for krypton is 20due to the lower sputtering yield and reduced fraction of multiply-charged ions. While investigators at other laboratories have observed reductions in krypton thruster efficiency up to 20evaluations of several NASA Hall thrusters have shown only a 5-10current efforts are focused on measuring the efficiency loss mechanisms of the NASA-173Mv2 operating on krypton through the use of several plume diagnostics. We are deploying gridded Faraday probes, RPA's, and ExB probes to quantify the ion flux, energy, and charge-state. Combined with our past performance evaluations and on-going modeling efforts, we are using the data to guide the development of Hall thrusters designed for krypton. We will present our latest performance and probe measurements and discuss the lessons learned from these investigations.

Hofer, Richard; Peterson, Peter; Manzella, David; Jacobson, David

2004-11-01

97

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

98

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

Microsoft Academic Search

Oxygen self-diffusion coefficients have been measured for three natural diopsidic clinopyroxenes, a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic åkermanite for oxygen fugacities ranging from the NNO to IW buffers. The experiments employed a gas-solid isotopic exchange technique utilizing 99% 18 O-enriched CO-CO 2 gas mixtures to control both the oxygen fugacity and the isotopic composition of

F. J. Ryerson; D. Kevin McKeegan

1994-01-01

99

Determination of Oxygen Self-Diffusion in Akermanite, Anorthite, Diopside, and Spinel: Implications for Oxygen Isotopic Anomalies and the Thermal Histories of Ca-Al-rich Inclusions  

Microsoft Academic Search

Oxygen self-diffusion coefficients have been measured for three natural clinopyroxenes (diopside end member), a natural anorthite, a synthetic magnesium aluminate spinel, and a synthetic akermanite over oxygen fugacities ranging from the NNO to IW buffers. The experiments employed a gas-solid isotopic exchange technique utilizing 99% ^18O-enriched COCO2 gas mixtures to control both the oxygen fugacity and the isotopic composition of

F. J. Ryerson; K. D. McKeegan

1993-01-01

100

Meltwater discharge anomalies in marine isotope stage 3 from a sediment core in the south of Antarctic Polar Front, Drake Passage  

Microsoft Academic Search

Marine isotope stages (MISs) 1 to 5 were identified in the planktonic ?18O record in sediment core DP00-02 just south of the Antarctic Polar Front within the Drake Passage, Antarctica. The oxygen\\u000a isotope record based onNeogloboquadrina pachyderma sinistral is well correlated with the contemporaneous global ?18O stratigraphy. Marked differences from the global climate curve suggest a local\\/regional overprint, particularly during

Sung Ho Bae; Ho Il Yoon; Byong-Kwon Park; Yeadong Kim; Jang Jun Bahk; Hyun Seok Seo

2003-01-01

101

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

102

Ultraviolet Absorption of Solid Argon, Krypton, and Xenon  

Microsoft Academic Search

The absorption spectra of thin films of argon, krypton, and xenon have been measured between 20 and 50°K in the region from 1600 to 900 Å (8 to 14 eV). The spectra show: (a) strong doublets corresponding to the atomic resonance doublets, (b) lines apparently of nonatomic nature, and (c) absorption continua. The experimental results are discussed in terms of

Giancarlo Baldini

1962-01-01

103

Atom Trap, Krypton-81, and Saharan Water  

SciTech Connect

Since radiocarbon dating was first demonstrated in 1949, the field of trace analyses of long-lived cosmogenic isotopes has seen steady growth in both analytical methods and applicable isotopes. The impact of such analyses has reached a wide range of scientific and technological areas. A new method, named Atom Trap Trace Analysis (ATTA), was developed by our group and used to analyze {sup 81}Kr (t{sub 1/2} = 2.3 x 10{sup 5} years, isotopic abundance {approx} 1 x 10{sup -12}) in environmental samples. In this method, individual {sup 81}Kr atoms are selectively captured and detected with a laser-based atom trap. {sup 81}Kr is produced by cosmic rays in the upper atmosphere. It is the ideal tracer for dating ice and groundwater in the age range of 10{sup 4}-10{sup 6} years. As the first real-world application of ATTA, we have determined the mean residence time of the old groundwater in the Nubian Aquifer located underneath the Sahara Desert. Moreover, this method of capturing and probing atoms of rare isotopes is also applied to experiments that study exotic nuclear structure and test fundamental symmetries.

Lu, Zheng-Tian (ANL) [ANL

2005-08-24

104

Anomaly Holography  

E-print Network

We consider, in the effective field theory context, anomalies of gauge field theories on a slice of a five-dimensional, Anti-de Sitter geometry and their four-dimensional, holographic duals. A consistent effective field theory description can always be found, notwithstanding the presence of the anomalies and without modifying the degrees of freedom of the theory. If anomalies do not vanish, the d=4 theory contains additional pseudoscalar states, which are either present in the low-energy theory as physical, light states, or are eaten by (would-be massless) gauge bosons. We show that the pseudoscalars ensure that global anomalies of the four-dimensional dual satisfy the 't Hooft matching condition and comment on the relevance for warped models of electroweak symmetry breaking.

Ben Gripaios; Stephen M. West

2007-04-30

105

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

Microsoft Academic Search

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

F. J. Ryerson; K. D. McKeegan

1994-01-01

106

The ?17O and ?18O measurements of atmospheric sulfate from a coastal and high alpine region: A mass-independent isotopic anomaly  

NASA Astrophysics Data System (ADS)

Atmospheric sulfate extracted from rainwater and aerosols has been sampled from two environments: La Jolla and White Mountain Research Station (WMRS), California. In general, the multiple stable oxygen isotopic analysis of these sulfate samples shows that they possess mass-independent oxygen isotopic compositions, unlike laboratory nonatmospheric standards. As suggested by the recent laboratory findings, the source of mass independent oxygen isotopic composition in sulfate is implied to be aqueous phase S(IV) oxidation by atmospheric H2O2 and O3. The relative S(IV) oxidation contribution by H2O2 and O3, which together generally represent the overall aqueous phase S(IV) oxidation, is estimated utilizing the average 17O enrichment value of La Jolla rainwater sulfate samples as an index. The estimate indicates a relative dominance of the aqueous over gas phase S(IV) oxidation. Although inconclusive owing to small data sets, both La Jolla and WMRS aerosol sulfate samples display seasonal 17O enrichment variations with a maximum in winter and a minimum in summer. Such seasonal isotopic variations are believed to derive from climatic effects that favor aqueous phase S(IV) oxidation in winter compared to summer. The radioactivity measurements of the cosmogenic 35S radionuclide, coupled with double oxygen isotope ratio measurements suggests an atmospheric sulfate contribution from high-altitude air mass (perhaps stratospheric) at WMRS, in particular during late winter/early spring season. The results of this work provide a new way to quantify relative oxidative pathways of S(IV) species in the atmosphere and to improve understanding atmospheric processes associated with sulfate.

Chi-Woo Lee, Charles; Thiemens, Mark H.

2001-08-01

107

Off-gas treatment and krypton disposal in HTGR-fuel element reprocessing  

Microsoft Academic Search

Krypton, tritium and iodine are separated from burner off-gas by CO-liquification and rectification at room tempearture. Krypton is concentrated in the lower boiling fraction, while tritium and iodine are concentrated in the higher boiling fraction (AKUT-process). The dissolver off-gas is decontaminated by a cryogenic process. Based on safety and economy, the disposal of compressed krypton confined in steel cylinders by

M. Laser; H. Beaujean; J. Bohnenstingl; P. Filss; M. Heidendael; S. Mastera; E. Merz; H. Vygen

1972-01-01

108

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.; Möller, L.; Sapart, C. J.; Prokopiou, M.; Sowers, T.; Röckmann, T.; Fischer, H.

2013-05-01

109

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.

110

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b  

E-print Network

Energy of the quasi-free electron in argon, krypton and xenon Xianbo Shi a,b , Luxi Li a,b , C. M ionization measurements of various high-n molecular Rydberg states doped into argon, krypton and xenon, krypton and xenon from the dilute gas up to the density of the triple point liquid, on both critical

Findley, Gary L.

111

X-ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann (*) and C. Marti  

E-print Network

1527 X- ray diffraction of krypton and xenon mixtures adsorbed on graphite T. Ceva, M. Goldmann 1986) Résumé. 2014 En étudiant, par diffraction des rayons X, les mélanges xenon-krypton absorbés sur. Abstract 2014 Mixtures of xenon and krypton adsorbed on graphite at 45 K are studied by X ray diffraction

Boyer, Edmond

112

Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant  

SciTech Connect

For krypton to become a realistic option for Hall thruster operation, it is necessary to understand the performance gap between xenon and krypton and what can be done to reduce it. A floating emissive probe is used with the Plasmadynamics and Electric Propulsion Laboratory's High-speed Axial Reciprocating Probe system to map the internal plasma potential structure of the NASA-173Mv1 Hall thruster [R. R. Hofer, R. S. Jankovsky, and A. D. Gallimore, J. Propulsion Power 22, 721 (2006); and ibid.22, 732 (2006)] using xenon and krypton propellant. Measurements are taken for both propellants at discharge voltages of 500 and 600 V. Electron temperatures and electric fields are also reported. The acceleration zone and equipotential lines are found to be strongly linked to the magnetic-field lines. The electrostatic plasma lens of the NASA-173Mv1 Hall thruster strongly focuses the xenon ions toward the center of the discharge channel, whereas the krypton ions are defocused. Krypton is also found to have a longer acceleration zone than the xenon cases. These results explain the large beam divergence observed with krypton operation. Krypton and xenon have similar maximum electron temperatures and similar lengths of the high electron temperature zone, although the high electron temperature zone is located farther downstream in the krypton case.

Linnell, Jesse A.; Gallimore, Alec D. [Plasmadynamics and Electric Propulsion Laboratory, Department of Aerospace Engineering, University of Michigan, 1919 Green Road B107, Ann Arbor, Michigan 48109 (United States)

2006-09-15

113

A comparative histopathological study of argon and krypton laser irradiations of the human retina  

Microsoft Academic Search

A series of comparative exposures to both argon and krypton lasers have been made at 3 locations in a human retina--the fovea, the macula, and intraretinal vessels. In the fovea argon irradiations resulted in damage to both the inner and outer retinal layers as a result of absorption within the pigment epithelium and the macular pigment, while krypton exposures damaged

J Marshall; A C Bird

1979-01-01

114

Kratom alkaloids and O-desmethyltramadol in urine of a “Krypton” herbal mixture consumer  

Microsoft Academic Search

AimA drug and alcohol withdrawal rehabilitation centre requested an analysis for “Krypton” in urine of a former opiate-addictive woman. She showed an altered clinical picture and behaviour with miosis, itchiness, agitation, and moderate euphoria after 3 months of until than successful treatment. Literature search revealed that “Krypton” is said to contain “Kratom” (leaves of Mitragyna speciosa), but could also contain

Torsten Arndt; Ulrich Claussen; Brunhilde Güssregen; Stefanie Schröfel; Birgit Stürzer; Annika Werle; Gerald Wolf

2011-01-01

115

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

116

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

117

Krypton-81m imaging of the right ventricle  

SciTech Connect

The authors report the development of a method for obtaining right-ventricular radionuclide angiograms using continuous peripheral intravenous infusion of the ultra-short-lived nuclide krypton-81m. This tracer has a half-life of 13 sec, emits a single 190-keV photon, and is extremely insoluble. During infusion into a peripheral vein, Kr-81m achieves stable count rates over the right heart, and it is essentially completely cleared by the lungs during its initial pulmonary transit. Thus no interfering activity is present in the systemic circulation. Initial studies provide excellent data on right-heart anatomy and function.

Horn, M.; Wiztum, K.; Neveu, C.; Perkins, G.; Walsh, B.

1985-01-01

118

The adsorption of argon, krypton and xenon on activated charcoal  

SciTech Connect

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

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

1996-08-01

119

Krypton-85 hydrofracture engineering feasibility and safety evaluation  

SciTech Connect

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

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

1981-07-01

120

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

121

ISOTOPIC COMPOSITION OF PRIMORDIAL XENON  

Microsoft Academic Search

A large excess of Xe¹²⁹ and secondary anomalous abundances for ; many of the other isotopes of xenon were previously reported for the meteorite, ; Richardton. Similar secondary anomalies in xenon are reported for the meteorite ; Murray. For every isotope other than Xe¹²⁹, the ratio of the Murray ; percent abundance to the Richardton percent abundance was the same

J. Reynolds

1960-01-01

122

Mass Independent Isotope Fractionation in Ozone; Cosmochemical Implications  

NASA Astrophysics Data System (ADS)

A possible origin for the mass independent oxygen isotope fractionation identified during the synthesis of ozone is proposed. If correct, it has general implication for the origin of several isotopic anomalies observed in meteorites.

Robert, F.; Reinhardt, P.

2014-09-01

123

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; Möller, Lars; Sapart, Celia; Prokopiou, Markella; Sowers, Todd; Röckmann, Thomas; Fischer, Hubertus

2014-05-01

124

Chiral anomalies and differential geometry  

SciTech Connect

Some properties of chiral anomalies are described from a geometric point of view. Topics include chiral anomalies and differential forms, transformation properties of the anomalies, identification and use of the anomalies, and normalization of the anomalies. 22 references. (WHK)

Zumino, B.

1983-10-01

125

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

SciTech Connect

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

Zhang, Fengkui, E-mail: fengkuizhang@163.com; Kong, Lingyi; Li, Chenliang; Yang, Haiwei; Li, Wei [College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 150001 (China)

2014-11-15

126

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

127

Investigation of many-body forces in krypton and xenon  

SciTech Connect

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

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

1988-10-15

128

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

SciTech Connect

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

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

2014-04-01

129

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

130

Xenon and Krypton Adsorption on Palladium (100) and Electron Stimulated Desorption of Xenon, Krypton, and Argon.  

NASA Astrophysics Data System (ADS)

The adsorption of Xe and Kr on the Pd(100) surface has been studied with thermodynamic, low energy electron diffraction, and work function experiments. Unlike on Ag(111), we observe no 2D island formation for Xe down to 10K. Quantitative measurements of the liquid-like diffraction pattern show that the diffuse ring of intensity increases in diameter, narrows, and becomes more intense continuously with increasing coverage, suggesting repulsive adatom interactions. The isosteric heat vs. coverage gives the average potential energy in the lateral interactions which suggests a steep repulsion at short distances and no attractive well. At high temperatures the results for Kr are similar but there is evidence for island formation near 10K. The isosteric heat indicates a weak attractive interaction. The results are compared with published simulations for hard and soft disks. It is speculated that the additional interadatom repulsion on Pd is due to the direct overlap of the deformed electron distribution in the substrate. Electron stimulated desorption cross sections have been measured for Xe, Kr, and Ar adsorbed on Ag(111). The Xe cross section is less than 10('-4) (ANGSTROM)('2); the Kr cross section is strongly temperature dependent, rising from 0.01 (ANGSTROM)('2) at 10K to 0.18 (ANGSTROM)('2) at 50K; the Ar cross section is 4 (ANGSTROM)('2) and temperature independent. These results are rationalized using a model of the stimulated desorption similar to that proposed by Antoniewicz (Phys. Rev. B21(1980)3811), in which an atom is ionized by the incident beam, accelerates toward its image and is neutralized, desorbing only if the kinetic energy gained is greater than the neutral atom binding energy at the neutralization position. Rather than the effect of the mass on the ion velocity, the most important effect in determining the diverse behavior of the different gases is that the equilibrium position for the heavier gases is farther up the overlap repulsive potential and so in a region of more rapid neutralization. The model identifies several contributions to the isotope effect, predicting it to be temperature dependent. The results are extremely sensitive to the anharmonicity of the holding potential.

Moog, Elizabeth Rahm

1984-06-01

131

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

132

Krypton charge exchange cross sections for Hall effect thruster models  

SciTech Connect

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{sup +} + Kr and Kr{sup 2+} + Kr cross sections. The measurements of symmetric Kr{sup +} + Kr charge exchange are in good agreement with both the calculations including spin-orbit effects and previous measurements. For the symmetric Kr{sup 2+} + 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 Kr{sup 2+} + Kr {yields} Kr{sup +} + Kr{sup +} reaction show an onset near 12 eV, reaching cross sections near constant value of 1.6 A{sup 2} with an exception near 70-80 eV.

Hause, Michael L. [Institute for Scientific Research, Boston College, Chestnut Hill, Massachusetts 02159 (United States); Prince, Benjamin D.; Bemish, Raymond J. [Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, New Mexico 87117 (United States)

2013-04-28

133

FIRST DETECTION OF KRYPTON AND XENON IN A WHITE DWARF  

SciTech Connect

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

2012-07-01

134

Modified effective range analysis of electron scattering from krypton  

NASA Astrophysics Data System (ADS)

The elastic cross sections for electron scattering on krypton from zero energy up to 10 eV have been analyzed by the modified effective range method. A simple model based on the analytical solution of the Schrödinger equation with the polarization potential using explicitly determined scattering phase shifts for the three lowest partial waves describes the elastic differential, integral and momentum transfer cross sections up to the energy threshold of the first inelastic process well. In detail, the contribution of the long-range polarization potential to the scattering phase shift is exactly expressed, while the contribution of the short-range effects is modelled by simple quadratic expressions (the effective range expansions). The effective range parameters are determined empirically by comparison with the latest experimental differential cross sections. Presently, the calculated integral and momentum transfer cross sections are validated against numerous electron scattering experiments and the most recent quantum-mechanical theories. To complete the picture, the two-term Boltzmann analysis is employed to determine the electron transport coefficients; the agreement with the electron swarm experimental data is found to be very good.

Fedus, Kamil

2014-10-01

135

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

136

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

137

Extrinsic photoconductivity in xenon-doped fluid argon and krypton  

NASA Astrophysics Data System (ADS)

Monochromated synchrotron radiation from the DORIS storage ring at DESY was used to excite photoconduction in xenon-doped fluid argon for densities ranging from 0.7 × 10 22 to 2.1 × 10 22 cm -3, in xenon-doped fluid krypton from 1.3 × 10 22 to 1.6 × 10 22 cm -3 as well as in solid Xe/Ar. The measurements yielded directly the ionization energy E Gi of the impurity in the dense medium. Using previous experimental results on the energy V0 of the conduction electron in conjunction with E Gi the polarization energy P+i of a hole trapped at a xenon atom was also determined for the respective density ranges. These experimental P+i values do not agree with theoretical predictions. Combining the E Gi values with results from absorption spectra by Messing et al. led to the determination of the binding energy and effective mass of the Wannier—Mott impurity exciton and indicated that previous assignments of absorption bands in xenon-doped solid argon have to be revised.

Reininger, R.; Steinberger, I. T.; Bernstorff, S.; Saile, V.; Laporte, P.

138

Krypton separation from ambient air for application in collinear fast beam laser spectroscopy.  

PubMed

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 H(2)O and CO(2), 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 N(2), O(2), 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. PMID:22549732

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

2012-07-01

139

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

140

Isentropic Compression of Argon and Krypton Using an MC1 Flux Compression Generator  

SciTech Connect

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 MC1 generator, 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 {Omega}{sup -1}cm{sup -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.

1998-10-18

141

Performance of an accordion electromagnetic calorimeter with liquid krypton and argon  

NASA Astrophysics Data System (ADS)

Test results of a liquid krypton/argon electromagnetic calorimeter with accordion type electrode structure are presented. The test was carried out at the Brookhaven AGS in a negative beam with good electron identification at momenta 5, 10, 15, and 20 GeV/ c. Results on energy resolution, linearity, pointing resolution, and muon response are presented. The results are in good agreement with Monte Carlo calculations. The energy resolution of {6.7%}/{E} was achieved using liquid krypton and {7.7%}/{E} with liquid argon, with a negligible constant term.

Benary, O.; Cleland, W.; Ferguson, I.; Gordeev, A.; Gordon, H.; Kistenev, E.; Kroon, P.; Leltchouk, M.; Lissauer, D.; Ma, H.; Makowiecki, D.; Maslennikov, A.; McCorkle, S.; Onoprienko, D.; Onuchin, A.; Oren, Y.; Panin, V.; Parsons, J. A.; Radeka, V.; Rogers, L.; Rahm, D.; Rescia, S.; Rutherfoord, J.; Seman, M.; Smith, M.; Sondericker, J.; Steiner, R.; Stephani, D.; Stern, E.; Stumer, I.; Takai, H.; Themann, H.; Tikhonov, Y.; Willis, W. J.

1994-05-01

142

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

NASA Astrophysics Data System (ADS)

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

Murphy, Anthony B.; Tam, Eugene

2014-07-01

143

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

SciTech Connect

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

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

2006-12-15

144

Self-organization in dc glow microdischarges in krypton: modelling and experiments  

NASA Astrophysics Data System (ADS)

Self-organized patterns of cathodic spots have been observed in microdischarges operated in xenon, but not in other gases. However, modelling has indicated that it is, in principle, possible to observe the patterns of spots in discharges operated in other gases provided that experimental conditions, in particular pressure, are right. In this work, self-organized patterns of cathodic spots are for the first time observed in dc glow microdischarges operated in a gas other than xenon: krypton. The experiments have been guided by the modelling. According to both the experiment and the modelling, patterns in krypton are similar to those found earlier in xenon, however occur at higher pressures.

Zhu, W.; Niraula, P.; Almeida, P. G. C.; Benilov, M. S.; Santos, D. F. N.

2014-10-01

145

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

146

Backscattering of low energy ions from a gold surface covered by condensed krypton  

Microsoft Academic Search

The energy and angular distributions of neon ions reflected from a polycrystalline gold target covered by condensed krypton atoms were measured. The results obtained suggest that the neutralization effect of the ions which leave the target due to single-scattering can be described by a continuum model assuming that the electronic surface is corrugated. The corrugation may be connected with a

W. Soszka; J. Budzioch; S. Kwasny; M. Soszka

1990-01-01

147

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions  

E-print Network

Amorphization of -Thorium Phosphate Diphosphate (-TPD) irradiated with high energy krypton ions C of nuclear wastes, the -Thorium Phosphate Diphosphate ceramic (-TPD), Th4(PO4)4P2O7, must be resistant as good candidates for nuclear waste immobilization [1-3]. Thorium Phosphate-Diphosphate (-TPD), -Th4(PO4

Paris-Sud XI, Université de

148

An atom trap trace analysis system for measuring krypton contamination in xenon dark matter detectors  

E-print Network

An atom trap trace analysis system for measuring krypton contamination in xenon dark matter contamination in xenon dark matter detectors E. Aprile, T. Yoon,a) A. Loose, L. W. Goetzke, and T. Zelevinsky for the sensitivity achievable with liquid xenon dark matter detectors beyond the current generation. Since Ar and Kr

Zelevinsky, Tanya

149

A Search for Anomalies  

Microsoft Academic Search

Since 1965 I have been culling systematically from the literature of science those observations that challenge reigning paradigms. The tangible result of the thousands of hours spent in libraries has been a series of Sourcebooks, Handbooks, and Catalogs that, at present, describe and evaluate roughly 2,000 anomalies— about one-half of my total collection. Some of these anomalies are truly profound

WILLIAM R. CORLISS

150

Si Isotope Homogeneity of the Solar Nebula  

NASA Astrophysics Data System (ADS)

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

Pringle, Emily A.; Savage, Paul S.; Jackson, Matthew G.; Barrat, Jean-Alix; Moynier, Frédéric

2013-12-01

151

Gravitational Anomaly and Transport  

E-print Network

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

Karl Landsteiner; Eugenio Megias; Francisco Pena-Benitez

2011-03-25

152

Gravitational Anomaly and Transport  

E-print Network

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

Landsteiner, Karl; Pena-Benitez, Francisco

2011-01-01

153

Vascular anomalies in children.  

PubMed

The process of understanding and treating children with vascular anomalies has been hampered by confusing and occasionally incorrect terminology. The most important step when evaluating a maxillofacial vascular anomaly is to determine whether it is a tumor or a malformation. In most cases, this diagnosis can be made by history and physical examination. Selective radiographic imaging is helpful in differentiating vascular malformations or the extent of bony involvement and/or destruction. Children with vascular anomalies should be managed by an interdisciplinary team of trained providers who are committed to following, treating, and studying patients with these complex problems. PMID:22771277

Abramowicz, Shelly; Padwa, Bonnie L

2012-08-01

154

COURBES D'IONISATION DANS LE KRYPTON ET LE XNON PURS RELATIVES AUX RAYONS 03B1 DU POLONIUM  

E-print Network

COURBES D'IONISATION DANS LE KRYPTON ET LE X�NON PURS RELATIVES AUX RAYONS 03B1 DU POLONIUM Par R polonium dans le krypton et le xénon purs. Les parcours trouvés sont : RKr = 3,03 ± 0,01 cm; RXe = 2,17 ± 0 xénon purs relatives aux rayons a du p'olonium. - En utilisant un appareil spécialement construit pour

Paris-Sud XI, Université de

155

Complex lymphatic anomalies.  

PubMed

Complex lymphatic anomalies include several diagnoses with overlapping patterns of clinical symptoms, anatomic location, imaging features, hematologic alterations, and complications. Lymphatic malformations likely arise through anomalous embryogenesis of the lymphatic system. Analysis of clinical, imaging, histologic, and hematologic features is often needed to reach a diagnosis. Aspiration of fluid collections can readily define fluid as chylous or not. The presence of chyle indicates dysfunction at the mesenteric or retroperitoneal level or above the cisterna chyli due to reflux. The imaging patterns of generalized lymphatic anomaly (GLA) and Gorham-Stout disease have been segregated with distinctive bone lesions and peri-osseous features. More aggressive histology (spindled lymphatic endothelial cells), clinical progression, hemorrhage, or moderate hematologic changes should raise suspicion for kaposiform lymphangiomatosis. Biopsy may be needed for diagnosis, though avoidance of rib biopsy is advised to prevent iatrogenic chronic pleural effusion. Lymphangiography can visualize the anatomy and function of the lymphatic system and may identify dysfunction of the thoracic duct in central conducting lymphatic anomalies. Local control and symptom relief are targeted by resection, laser therapy, and sclerotherapy. Emerging data suggest a role for medical therapies for complications of complex lymphatic anomalies. Outcomes include recurrent effusion, infection, pain, fracture, mortality, and rarely, malignancy. Complex lymphatic anomalies present significant diagnostic and therapeutic challenges. Results from a phase 2 study of sirolimus in these and other conditions are expected in 2014. Improved characterization of natural history, predictors of poor outcomes, responses to therapy, and further clinical trials are needed for complex lymphatic anomalies. PMID:25241096

Trenor, Cameron C; Chaudry, Gulraiz

2014-08-01

156

Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure  

NASA Astrophysics Data System (ADS)

The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K 0- overlineK 0 system with an accuracy of 2 × 10 -4 in the parameter Re(?'/?). Decays in two ?0's will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of {?3.5%}/{?E} with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV.

Barr, G. D.; Bruschini, C.; Bocquet, C.; Buchholz, P.; Cundy, D.; Doble, N.; Funk, W.; Gatignon, L.; Gonidec, A.; Hallgren, B.; Kesseler, G.; Lacourt, A.; Laverrière, G.; Linser, G.; Martini, M.; Norton, A.; Schinzel, D.; Seidl, W.; Sozzi, M. S.; Taureg, H.; Vossnack, O.; Wahl, H.; Wertelaers, P.; Weterings, J.; Ziolkowski, M.; Kalinin, A.; Kekelidze, V.; Kozhevnikov, Yu.; Bertolotto, L.; Carassiti, V.; Duclos, J.; Gianoli, A.; Frabetti, P. L.; Savriè, M.; Zeitnitz, O.; Calvetti, M.; Lubrano, P.; Pepe, M.; Calafiura, P.; Cerri, C.; Costantini, F.; Fantechi, R.; Gorini, B.; Mannelli, I.; Marzulli, V.; Bédérède, D.; Debu, P.; Givernaud, A.; Gosset, L.; Heitzmann, J.; Mazzucato, E.; Peyaud, B.; Turlay, R.; Biino, C.; Ceccucci, A.; Maas, P.; Palestini, S.; Cagliari-Cambridge-CERN-Dubna-Edinburgh-Ferrara-Mainz-Orsay-Perugia-Pisa-Saclay-Siegen-Torino-Vienna Collaboration

1996-02-01

157

Resonantly-enhanced harmonic generation and above threshold ionization in krypton  

SciTech Connect

We describe the results of experiments performed in Krypton to observe the effect of an isolated atomic level on harmonic generation at intensities above 10{sup 13} W/cm{sup 2}. We have measured the intensity of harmonics produced as a function of laser intensity and focal conditions as well as recorded the photoelectron energy spectra in complementary experiments. We discuss a simple model fit to our data that describes an atomic level as Stark shifting through resonance. 7 refs., 3 figs.

Crane, J.K.; Allendorf, S.W.; Budil, K.S.; Perry, M.D.

1991-05-14

158

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

159

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

160

Electron-ion recombination rate constants in gaseous and liquid krypton  

Microsoft Academic Search

Electron drift mobilities ?e and electron–ion recombination rate constants kr have been measured by the analysis of transient current induced with the irradiation of an x-ray pulse on gaseous or liquid krypton in a cell as a function of external electric field strength. The effects of an external dc electric field on kr up to 12 mTd (1 Td=10?17 V

Kenji Honda; Kentaro Endou; Hitoshi Yamada; Kyoji Shinsaka; Masatoshi Ukai; Noriyuki Kouchi; Yoshihiko Hatano

1992-01-01

161

Energy of the Quasi-free Electron in Argon and Krypton C. M. Evans1,  

E-print Network

Energy of the Quasi-free Electron in Argon and Krypton C. M. Evans1, and G. L. Findley2, 1 these data, a new local Wigner- Seitz model for the density dependent energy V0(P) of a quasi-free electron/medium polarization energy, and includes the thermal kinetic energy of the quasi-free electron. Using this model, V0(P

Findley, Gary L.

162

Carbon dioxide-krypton separation and radon removal from nuclear-fuel-reprocessing off-gas streams  

SciTech Connect

General Atomic Company (GA) is conducting pilot-plant-scale tests that simulate the treatment of radioactive and other noxious volatile and gaseous constituents of off-gas streams from nuclear reprocessing plants. This paper reports the results of engineering-scale tests performed on the CO/sub 2//krypton separation and radon holdup/decay subsystems of the GA integrated off-gas treatment system. Separation of CO/sub 2/ from krypton-containing gas streams is necessary to facilitate subsequent waste processing and krypton storage. Molecular sieve 5A achieved this separation in dissolver off-gas streams containing relatively low krypton and CO/sub 2/ concentrations and in krypton-rich product streams from processes such as the krypton absorption in liquid carbon dioxide (KALC) process. The CO/sub 2//krypton separation unit is a 30.5-cm-diameter x 1.8-m-long column containing molecular sieve 5A. The loading capacity for CO/sub 2/ was determined for gas mixtures containing 250 ppM to 2.2% CO/sub 2/ and 170 to 750 ppM krypton in either N/sub 2/ or air. Gas streams rich in CO/sub 2/ were diluted with N/sub 2/ to reduce the temperature rise from the heat of adsorption, which would otherwise affect loading capacity. The effluent CO/sub 2/ concentration prior to breakthrough was less than 10 ppM, and the adsorption capacity for krypton was negligible. Krypton was monitored on-line with a time-of-flight mass spectrometer and its concentration determined quantitatively by a method of continuous analysis, i.e., selected-ion monitoring. Radon-220 was treated by holdup and decay on a column of synthetic H-mordenite. The Rn-220 concentration was monitored on-line with flow-through diffused-junction alpha detectors. Single-channel analyzers were utilized to isolate the 6.287-MeV alpha energy band characteristic of Rn-220 decay from energy bands due to daughter products.

Hirsch, P.M.; Higuchi, K.Y.; Abraham, L.

1982-07-01

163

X-ray fluorescence and absorption analysis of krypton in irradiated nuclear fuel  

NASA Astrophysics Data System (ADS)

The analysis of krypton in irradiated uranium dioxide fuel has been successfully achieved by X-ray fluorescence and X-ray absorption. The present study focuses on the analytical challenge of sample and sub-sample production to perform the analysis with the restricted conditions dictated by the radioprotection regulations. It deals also with all potential interferences that could affect the quality of the measurement in fluorescence as well as in absorption mode. The impacts of all dissolved gases in the fuel matrix are accounted for the analytical result quantification. The krypton atomic environment is ruled by the presence of xenon. Other gases such as residual argon and traces of helium or hydrogen are negligible. The results are given in term of density for krypton (?3 nm-3) and xenon (?20 nm-3). The presence of dissolved, interstitial and nano-phases are discussed together with other analytical techniques that could be applied to gain information on fission gas behaviour in nuclear fuels.

Degueldre, Claude; Mieszczynski, Cyprian; Borca, Camelia; Grolimund, Daniel; Martin, Matthias; Bertsch, Johannes

2014-10-01

164

Astrometric solar system anomalies  

SciTech Connect

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

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

2009-01-01

165

Dealing with Ebstein's anomaly.  

PubMed

Ebstein's anomaly is a complex congenital disorder of the tricuspid valve. Presentation in neonatal life and (early) childhood is common. Disease severity and clinical features vary widely and require a patient-tailored treatment. In this review, we describe the natural history of children and adolescents with Ebstein's anomaly, including symptoms and signs presenting at diagnosis. Current classification strategies of Ebstein's anomaly are discussed. We report on diagnostic methods for establishing the severity of disease that might enhance decision on the timing of surgical intervention. Furthermore, we describe different surgical options for severely ill neonates and multiple surgical interventions after infancy. Only with ample knowledge and understanding of the above, this complex and diverse group of patients can be correctly treated in order to improve not only duration, but also quality of life. PMID:24169373

Geerdink, Lianne M; Kapusta, Livia

2014-04-01

166

Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition  

SciTech Connect

Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH{sub 4}) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

Oliveira, M. H. Jr. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas-UNICAMP, C. P. 6165, Campinas, Sao Paulo 13083-970 (Brazil); Institut de Ciencia dels Materials, Universitat de Valencia, E-46071 Valencia (Spain); Viana, G. A.; Marques, F. C. [Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas-UNICAMP, C. P. 6165, Campinas, Sao Paulo 13083-970 (Brazil); Lima, M. M. Jr. de; Cros, A.; Cantarero, A. [Institut de Ciencia dels Materials, Universitat de Valencia, E-46071 Valencia (Spain)

2010-12-15

167

Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH4) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

Oliveira, M. H.; Viana, G. A.; de Lima, M. M.; Cros, A.; Cantarero, A.; Marques, F. C.

2010-12-01

168

182Hf, a new isotope for AMS  

Microsoft Academic Search

The neutron-rich isotope 182Hf with its half-life of 9±2 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

169

Calcium and titanium isotopic fractionations during evaporation  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

170

Venus - Ishtar gravity anomaly  

NASA Technical Reports Server (NTRS)

The gravity anomaly associated with Ishtar Terra on Venus is characterized, comparing line-of-sight acceleration profiles derived by differentiating Pioneer Venus Orbiter Doppler residual profiles with an Airy-compensated topographic model. The results are presented in graphs and maps, confirming the preliminary findings of Phillips et al. (1979). The isostatic compensation depth is found to be 150 + or - 30 km.

Sjogren, W. L.; Bills, B. G.; Mottinger, N. A.

1984-01-01

171

Fetal cardiac anomalies  

Microsoft Academic Search

Fetal cardiac anomalies are increasingly identified during regular obstetric scanning. About 21000 pregnancies will have an abnormality of the four chamber view and a further 11000 will have an abnormality of the great arteries. These cases can then be referred to the specialist in fetal cardiology for further evaluation and counselling. There is a higher rate of chromosomal and other

Lindsey D. Allan

1996-01-01

172

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. Allègre

1988-01-01

173

Electron capture from the krypton M-shell by MeV protons S. Andriamonje (*), J. F. Chemin (*), J. Roturier (*), B. Saboya (*), J. N. Scheurer (*),  

E-print Network

349 Electron capture from the krypton M-shell by MeV protons S. Andriamonje (*), J. F. Chemin section for electron capture from the L-shell to L and M-shells in Siq+-Ar collision, with the charge An experimental and theoretical study of electron capture by protons from a krypton gas jet target in the energy

Paris-Sud XI, Université de

174

JOWRNAL DE PHYSIQUE Colloque C4, supplkment au no 10, Tome 38, octobre 1977, page C4-99 KRYPTON OVERLAYERS ON GRAPHITE :LOW ENERGY ELECTRON  

E-print Network

OVERLAYERS ON GRAPHITE :LOW ENERGY ELECTRON DIFFRACTION AND AUGER ELECTRON SPECTROSCOPY MEASUREMENTS (*) S Btudier I'adsorption de krypton sur la face (0001) du graphite. Les pressions et temperatures de the adsorption of krypton on the (0001) plane of graphite. The pressures and temperatures for two dimensional

Boyer, Edmond

175

PII S0016-7037(02)00965-1 A method for precise measurement of argon 40/36 and krypton/argon ratios in trapped air  

E-print Network

PII S0016-7037(02)00965-1 A method for precise measurement of argon 40/36 and krypton/argon ratios,000 years ago. The krypton/argon ratio can provide a diagnostic of argon leakage out of the bubbles, which the freezing point during core retrieval or storage. Argon leakage may fractionate the remaining 40 Ar/36 Ar

Severinghaus, Jeffrey P.

176

Genetics Home Reference: Peters anomaly  

MedlinePLUS

... the individuals affected with Peters anomaly have low vision early in life and about a quarter are legally blind. Due to a lack of visual stimulation, some individuals develop "lazy eye" (amblyopia). Peters anomaly ...

177

Transmutations and Isotopic shifts in LENR Experiments: An Overview  

E-print Network

Abstract-- This overview presents a brief summary of observations of products of transmutation reactions which occur in a variety of LENR configurations wherein the “host metal ” nuclei react with loaded deuterium or hydrogen, resulting in the formation of new stable elements or isotopes not present prior to an experimental run. Index Terms—Transmutation reactions, Isotopic anomalies, multi-deuteron capture reactions.

Mahadeva Srinivasan

178

Elemental and isotopic composition of the galactic cosmic rays  

Microsoft Academic Search

It is now established that there are important differences in elemental and isotopic abundance between the source matter of galactic cosmic rays and the solar system matter. These large differences (more than a factor of 2 in some cases, in contrast to less than or equal to1% for isotopic anomalies in solar system matter) may become essential clues to the

J A Simpson

1983-01-01

179

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

E-print Network

3/24/2011 1 Outline 1. Isotope Definitions and terms a) Isotopes and isotope ratios. Isotopes fractionation c) Simple illustration with the water cycle 2. CO2 isotopes in photosynthesis a) Photosynthetic discrimination in C3 plants b) C3 vs C4 photosynthesis and the distinction in isotopes c) Measuring isotopic

Saleska, Scott

180

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

181

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas  

SciTech Connect

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

182

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

NASA Technical Reports Server (NTRS)

Cross sections for electron impact ionization of krypton due to ejection of a 3d-shell electron have been calculated using screened hydrogenic and Hartree-Slater wavefunctions for the 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 3d electrons, are widely different in the two approximations. The angular distribution due to the 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

183

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

184

Phase diagram for the domain-wall lattice of krypton on graphite  

NASA Astrophysics Data System (ADS)

We show that the elastic constants of a domain-wall lattice (DWL) such as the incommensurate phase of krypton on graphite can be determined directly from the isothermal variation of its misfit with chemical potential. The stability of the DWL to the creation of free dislocations is analyzed, and the Kosterlitz-Thouless-Halperin-Nelson-Young melting transition is located. At certain coverages, as the temperature is reduced, the DWL is predicted to melt. Because the location of this reentrant fluid transition depends on the substrate corrugation, a still undetermined quantity, experimental studies to locate the transition will help determine the corrugation magnitude.

Shrimpton, Neil D.; Joós, Béla

1990-03-01

185

Electron-Photon Polarization Correlation Study of Neon, Argon and Krypton Excitation by Electron Impact  

NASA Astrophysics Data System (ADS)

The electron impact excitation of the 3s ^' (1/2) ^0_1 state in neon, the 4s^' (1/2) ^0_1 state in argon and the 5s (3/2) ^0_1 state in krypton have been studied using the electron-photon polarization correlation technique. The two linear coherence parameters P_1 and P_2 have been measured and the alignment angle gamma and the linear polarization P ^+_{rm lin} of the angular part of the collisionally induced excited state charge cloud were extracted from the measured P _1 and P_2 parameters. We measured P_1 and P_2 in neon at an impact energy of 50 eV, in argon at impact energies of 50 eV, 40 eV, 30 eV and 25 eV, and in krypton at impact energies of 50 eV and 30 eV and electron scattering angles up to 55^circ in all cases. A comparison with theoretical predictions from first-order perturbative theories such as a Distorted Wave Born Approximation (DWBA) and a First Order Many Body Theory (FOMBT) was made. At 50 eV in neon and argon, the agreement between experiment and theory is generally good at small scattering angles up to 25^circ and somewhat poorer at larger scattering angles. At 50 eV in krypton, the agreement between experiment and theory is generally good at scattering angles up to 40 ^circ. The measurements in argon (40 eV, 30 eV, and 25 eV) generally follow the trend of the theoretical predictions, but it was found that the experimentally measured coherence parameters appear to be shifted towards larger scattering angles compared to the theoretical predictions as the impact energy is decreased. At 30 eV in krypton, very good agreement between experiment and theory was found over the entire range of electron scattering angles (up to 55^circ). The level of agreement between experiment and theory indicates that the DWBA and FOMBT appear to provide a better description of the collision process for a more complex target. We also found that the alignment angle gamma is the parameter which is perhaps least sensitive to the details of the collision.

Zheng, Shuanghai

1993-01-01

186

Relativistic configuration interaction calculations on K? x-ray satellites of krypton  

NASA Astrophysics Data System (ADS)

The multi-configuration Dirac-Fock (MCDF) and relativistic configuration interaction (RCI) methods have been used for computing the transition wavelengths, electric dipole transition probabilities, line strengths and absorption oscillator strengths for the K? x-rays from Kr XXVII to Kr XXXV. The contributions from Breit interaction, finite nuclear mass corrections and quantum electrodynamics corrections to the initial and final levels have been taken into account. The calculated values showed good agreement between these results and recent theoretical and experimental results. These data provide reference values for the level lifetimes, charge state distribution and average charge of krypton plasmas.

Zhang, Li; Jiang, Gang; Hao, Lianghuan; Deng, Banglin

2011-02-01

187

Mass Anomalies on Ganymede  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

188

Yearly Arctic Temperature Anomaly  

NSDL National Science Digital Library

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

Starr, Cindy; Comiso, Josefino

2003-10-23

189

Anomaly, impulsivity, and addiction  

Microsoft Academic Search

There are two behavioral approaches to addiction: rational and irrational. The rational approach assumes that addicts have higher time preference rates and lower risk-aversion coefficients—parameters that are interpreted as impulsive preferences. On the other hand, the irrational approach argues that addiction is a consequence of anomalies such as non-expected utility and hyperbolically discounted utility. This paper integrates these two approaches

Takanori Ida

2010-01-01

190

Easter microplate evolution: Pb isotope evidence  

Microsoft Academic Search

We report on 53 Pb isotope analyses of basalts from 48 dredge stations occupied along the spreading boundaries of the Easter microplate and adjacent East Pacific Rise (EPR). Also included in the study are seven analyses of basalts from Easter and Sala y Gomez islands. A major anomaly is observed on the East Rift, around 27°S, where this ridge is

Barry B. Hanan; Jean-Guy Schilling

1989-01-01

191

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 patient’s age. On the basis of these inherited forms, molecular genetic studies have unraveled a number of inherited mutations giving direct insight into the pathophysiological cause and the molecular pathways that are implicated. Genetic defects have been identified for hereditary haemorrhagic telangiectasia (HHT), inherited cutaneomucosal venous malformation (VMCM), glomuvenous malformation (GVM), capillary malformation - arteriovenous malformation (CM-AVM), cerebral cavernous malformation (CCM) and some isolated and syndromic forms of primary lymphedema. We focus on these disorders, the implicated mutated genes and the underlying pathogenic mechanisms. We also call attention to the concept of Knudson’s double-hit mechanism to explain incomplete penetrance and the large clinical variation in expressivity of inherited vascular anomalies. This variability renders the making of correct diagnosis of the rare inherited forms difficult. Yet, the identification of the pathophysiological causes and pathways involved in them has had an unprecedented impact on our thinking of their etiopathogenesis, and has opened the doors towards a more refined classification of vascular anomalies. It has also made it possible to develop animal models that can be tested for specific molecular therapies, aimed at alleviating the dysfunctions caused by the aberrant genes and proteins. PMID:21095468

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

2010-01-01

192

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

193

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

SciTech Connect

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

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

2012-06-01

194

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

195

Energy of the Quasi-free Electron in Supercritical Krypton near the Critical Point Luxi Li and C. M. Evans  

E-print Network

Energy of the Quasi-free Electron in Supercritical Krypton near the Critical Point Luxi Li and C. M by the quasi-free electron that arises from field ionization of the dopant, and the zero point kinetic energy of the free electron. The overall decrease in the shift of the dopant ionization energy near the critical

Evans, Cherice M.

196

Numerical Shockwave Anomalies  

NASA Astrophysics Data System (ADS)

The reliable simulation of shockwaves is critical in the prediction and study of many phenomena, where abrupt changes in material properties due to shockwaves can greatly affect regions of interest and activate physical mechanisms. When a physical shockwave is formed, it moves through the flow with a certain speed, having some finite width determined by physical dissipation until it encounters some event in its path. For numerical shockwaves, however, a numerical width is enforced, often much greater than the physical width. With this numerical width comes the formation of intermediate states having no direct physical interpretation. Even as the mesh is refined, these intermediate states do not go away; they simply occupy less space. The existence of intermediate states does raise some doubt, however, about how closely a captured shockwave may emulate an ideal discontinuous shockwave, or a real physical one. There are in fact several types of error associated with intermediate shock states such as errors in shock position, spurious waves, or unstable shock behavior. These errors can be classified as numerical shockwave anomalies; they are numerical artifacts formed due to the presence of captured shockwaves within the flow solution. Each numerical shockwave anomaly is directly related to the nonlinearity of the jump conditions and to a resulting ambiguity in sub-cell shock position in a stationary shock. Two new flux functions are developed that do not have this ambiguity. On all of the shock anomalies in one-dimension, both flux functions show improvement on existing methods without smearing or diffusing the shock. They are also shown to perform adequately within a second-order framework and on two-dimensional problems, important for the practicality of the method. While they are still susceptible to many of the problems that occur in Roe's Riemann solver and several other known issues, these methods serve to validate the philosophy and approach taken in this thesis: by enforcing a linear shock structure and unambiguous sub-cell shock position, numerical shockwave anomalies are dramatically reduced.

Zaide, Daniel Wei-Ming

197

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

E-print Network

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 $330 \\pm 200$ ppt.

Ethan Brown; Stephan Rosendahl; Christian Huhmann; Christian Weinheimer; Hans Kettling

2012-12-20

198

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 330±200 ppt.

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

2013-02-01

199

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

NASA Astrophysics Data System (ADS)

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

2012-04-01

200

System for closure of a physical anomaly  

DOEpatents

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

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

2014-11-11

201

WF4 Anomaly Characterization  

NASA Astrophysics Data System (ADS)

A serious anomaly has been found in images from the WF4 CCD in WFPC2. The WF4 CCD bias level appears to have become unstable, resulting in sporadic images with either low or zero bias level. The severity and frequency of the problem is rapidly increasing, and it is possible that WF4 will soon become unusable if no work-around is found. The other three CCDs {PC1, WF2, and WF3} appear to be unaffected and continue to operate properly. The impacts from "low" and "zero" bias are somewhat different, but in both cases the effects are immediately obvious. Images with low bias will tend to have horizontal {x-direction} streaks and stripes with an amplitude of ? about 0.5 DN in WF4. We believe these data should be mostly recoverable with some effort, though at a loss in the detectability of faint targets. "Zero bias" is a much more serious problem and is evidenced by images which are blank in WF4, except for showing occasional cosmic rays, bright targets, and negative pixels from dark subtraction. These images with zero bias are probably unusable for most purposes. Both the CCD gain settings of 7 and 14 are affected. The frequency of the anomaly is rapidly increasing. The first significant instances of low bias appear to have been in late 2004 when a few images were impacted. However, within the last few weeks over half the images are beginning to show the low bias problem. The more serious "zero bias" problem appears to have first occurred in Feb. 2005, but it is also increasing and now impacts 10% to 20% of WFPC2 images. At present there are still many images which appear fine and unaffected, but the situation is quickly evolving. We believe the science impact for most observers will be minimal. Targets are by default placed on either PC1 or WF3 which continue to operate properly. However, observers requiring the full field of view {survey projects, large targets, etc.} will potentially lose one-third of their imaging area. Our understanding of this anomaly is still evolving, and most of the information is tentative. Additional details will be posted on the WFPC2 website as they become available.

Biretta, John

2005-07-01

202

Anomaly Structure of Regularized Supergravity  

NASA Astrophysics Data System (ADS)

On-shell Pauli-Villars regularization of the one-loop divergences of supergravity theories is used to study the anomaly structure of supergravity and the cancellation of field theory anomalies under a U (1 ) gauge transformation and under the T -duality group of modular transformations in effective supergravity theories with three Kähler moduli Ti obtained from orbifold compactification of the weakly coupled heterotic string. This procedure requires constraints on the chiral matter representations of the gauge group that are consistent with known results from orbifold compactifications. Pauli-Villars (PV) regulator fields allow for the cancellation of all quadratic and logarithmic divergences, as well as most linear divergences. If all linear divergences were canceled, the theory would be anomaly free, with noninvariance of the action arising only from Pauli-Villars masses. However there are linear divergences associated with nonrenormalizable gravitino/gaugino interactions that cannot be canceled by PV fields. The resulting chiral anomaly forms a supermultiplet with the corresponding conformal anomaly, provided the ultraviolet cutoff has the appropriate field dependence, in which case total derivative terms, such as Gauss-Bonnet, do not drop out from the effective action. The anomalies can be partially canceled by the four-dimensional version of the Green-Schwarz mechanism, but additional counterterms, and/or a more elaborate set of Pauli-Villars fields and couplings, are needed to cancel the full anomaly, including D -term contributions to the conformal anomaly that are nonlinear in the parameters of the anomalous transformations.

Butter, Daniel; Gaillard, Mary K.

2015-01-01

203

Mass spectrometry and natural variations of iron isotopes.  

PubMed

Although the processes that govern iron isotope variations in nature are just beginning to be understood, multiple studies attest of the virtue of this system to solve important problems in geosciences and biology. In this article, we review recent advances in the geochemistry, cosmochemistry, and biochemistry of iron isotopes. In Section 2, we briefly address the question of the nucleosynthesis of Fe isotopes. In Section 3, we describe the different methods for purifying Fe and analyzing its isotopic composition. The methods of SIMS, RIMS, and TIMS are presented but more weight is given to measurements by MC-ICPMS. In Section 4, the isotope anomalies measured in extraterrestrial material are briefly discussed. In Section 5, we show how high temperature processes like evaporation, condensation, diffusion, reduction, and phase partitioning can affect Fe isotopic composition. In Section 6, the various low temperature processes causing Fe isotopic fractionation are presented. These involve aqueous and biologic systems. PMID:16463281

Dauphas, Nicolas; Rouxel, Olivier

2006-01-01

204

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

205

The solubility of 85Krypton in the regenerating liver of the rat.  

PubMed Central

The accuracy of liver blood flow measurement using the 85Krypton clearance technique depends on the use of an appropriate value for the solubility of 85Kr in liver relative to blood (the partition coefficient, lambda). This factor was studied in the regenerating liver remnant of the rat after a 67% partial hepatectomy, in order to find the influence of the ensuing postoperative fatty infiltration of the liver. There was found to be a rapid increase in lambda from 0-95 in the normal liver to 1-52 in the remnant 7-5 h after operation, followed by a more gradual return to normal levels by 35 h. The results indicate an early increase in the fat content of the liver after 67% hepatectomy and demonstrate that liver blood flow calculated from 85Kr clearance measurements in the early stages of regeneration must take into account the changes in lambda during that time. PMID:871375

Mathie, R. T.; Leiberman, D. P.; Harper, A. M.; Blumgart, L. H.

1977-01-01

206

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

207

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

208

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

209

Tracing the ozone isotopic anomaly transferred to other atmospheric  

E-print Network

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

Einat, Aharonov

210

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

211

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

212

Oxygen Isotope Distribution in the Early Solar System: An Ion Microscopic View of a Big Issue  

Microsoft Academic Search

The discovery of oxygen isotope anomalies changed forever our picture of the early solar system: Allende refractory inclusions were found to have a 4% excess in 16O relative to terrestrial. While originally ascribed to nucleosynthetic addition, these anomalies appear to be best explained by a chemical fractionation mechanism, either a symmetry effect (as in the Earth atmosphere ozone), or photodissociation

T. R. Ireland

2009-01-01

213

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

214

A glacial warm water anomaly in the subantarctic Atlantic Ocean, near the Agulhas Retroflection  

Microsoft Academic Search

ODP Site 1089 is optimally located in order to monitor the occurrence of maxima in Agulhas heat and salt spillage from the Indian to the Atlantic Ocean. Radiolarian-based paleotemperature transfer functions allowed to reconstruct the climatic history for the last 450 kyr at this location. A warm sea surface temperature anomaly during Marine Isotope Stage (MIS) 10 was recognized and

Giuseppe Cortese; Andrea Abelmann; Rainer Gersonde

2004-01-01

215

Gravitational anomaly and transport phenomena.  

PubMed

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

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

2011-07-01

216

On the interference of 86Kr2+ during carbon isotope analysis of atmospheric 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. The effect comes about by the lateral tailing of the peak of doubly charged 86Kr in the neighbouring m/z, 44, 45, and 46 Faraday cups. Accordingly, the introduced bias 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, J.; Seth, B.; Bock, M.; van der Veen, C.; Möller, L.; Sapart, C. J.; Prokopiou, M.; Sowers, T.; Röckmann, T.; Fischer, H.

2013-02-01

217

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

PubMed

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

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

2011-04-01

218

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

Microsoft Academic Search

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

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

2011-01-01

219

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

220

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. PMID:23565017

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

2013-01-01

221

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

222

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

223

Isotope Science and Production  

E-print Network

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

224

Effects of copper nanoparticle inclusions on pressure-induced fluid-polynanocrystalline structural transitions in krypton  

NASA Astrophysics Data System (ADS)

The dependence of nanoscale crystal formation from a noble element fluid on the rate of hydrodynamic compression was explored using molecular dynamics. Results were obtained for pure krypton samples as well as ones containing a cubic- or spherical-shaped fcc copper nanocrystal inclusion for compression rates of 1, 10, and 20 MPa/ps. In the absence of Cu, Kr crystals nucleate with apparently random locations and orientations in the sample; slower compression leads to larger nanocrystal size. The effect of the Cu inclusion is to partially mediate the location, orientation, and size of the formed crystals. The effect is larger for the slower compression rate and when the inclusion is cubic rather than spherical in shape. For sufficiently slow compression, the stress state in the cubic Cu inclusion changes from hydrostatic to non-hydrostatic as a consequence of the formation of extended orthotropic hcp/fcc nanostructures in the Kr. The mechanism of the dynamic stress-induced nanostructural transition is explained qualitatively in terms of known geometric effects on the quasi-static indentation response of crystalline materials.

Chen, Zhen; Jiang, Shan; Sewell, Thomas D.; Gan, Yong; Oloriegbe, Suleiman Y.; Thompson, Donald L.

2014-12-01

225

Status of the Level 0 Trigger Processor of the NA62 Liquid Krypton Electromagnetic Calorimeter  

NASA Astrophysics Data System (ADS)

The NA62 experiment at the CERN SPS aims to measure the Branching Ratio of the ultra-rare decay K^+ rightarrow ?^+?bar?, collecting about 100 events in two years of data taking with a signal to background ratio of 10:1. A hermetic photon veto system has been designed to efficiently reject the ?0 background, one of the main background sources, and the 20-ton liquid krypton calorimeter is a fundamental component of such system in the angular acceptance region 1-10 mrad. In this paper, we present the design of the Level 0 trigger processor that is able to identify electromagnetic clusters in the calorimeter providing information on time, position and energy reconstruction for each cluster. In particular, it is composed of 36 readout boards (TEL62), organized in a three layer parallel system, 108 mezzanines and 215 high-performance FPGAs. The system has been designed to sustain an instantaneous hit rate of 40 MHz, to process data with a latency of about 100 ?s, and to achieve a time resolution of 1.5 ns on the single cluster. Performance and functionality test results of a trigger slice, together with an updated status report of the whole level 0 trigger project, will be presented.

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

2014-06-01

226

Numerical Experiments on Radiative Cooling and Collapse in Plasma Focus Operated in Krypton  

NASA Astrophysics Data System (ADS)

The Plasma Focus has wide-ranging applications due to its intense radiation of SXR, XR, electron and ion beams and fusion neutrons when operated in deuterium. The 5-phase Lee Model code has been developed for the focus operated in various gases including D, D-T, He, Ne, N, O, Ar, Kr and Xe. Radiation-coupled motion is included in the modelling. In this paper we look at the effect of radiation cooling and radiation collapse in krypton. The Pease-Braginskii current is that current flowing in a hydrogen pinch which is just large enough for the Bremsstrahlung to balance Joule heating. This radiation-cooled threshold current for a hydrogen pinch is 1.6 MA. It is known that in gases undergoing line radiation strongly the radiation-cooled threshold current is considerably lowered. We show that the equations of the Lee Model code may be used to compute this lowering. The code also shows the effect of radiation cooling leading to radiative collapse. Numerical experiments based on experimentally fitted model parameters are run to demonstrate a regime in which radiation collapse is observed in Kr at a pinch current of 50-100 kA.

Lee, S.; Saw, S. H.; Ali, Jalil

2013-02-01

227

Impact of high dose krypton ion irradiation on corrosion behavior of laser beam welded zircaloy-4  

SciTech Connect

In order to study the effect of krypton ion irradiation on the aqueous corrosion behavior of laser beam welded zircaloy-4 (LBWZr4), the butt weld joint of zircaloy-4 was made by means of a carbon dioxide laser, subsequently the LBWZr4 samples were irradiated with Kr ions using an accelerator at an energy of 300 keV, with a dose range from 1 x 10{sup 15} to 3 x 10{sup 16} ions/cm{sup 2} at about 150 deg. C. Three-sweep potentiodynamic polarization measurement was employed to evaluate the aqueous corrosion behavior of Kr-irradiated LBWZr4 in a 0.5 M H{sub 2}SO{sub 4} solution. Scanning electron microscopy (SEM) was used to examine the surface topography of the Kr-irradiated LBWZr4 after the potentiodynamic polarization measurement. Transmission electron microscopy was employed to examine the change of microstructures in the irradiated surface. The polarization tests showed that compared with the passive current density of the as-received LBWZr4, the Kr-irradiated LBWZr4 is much lower; however, with the irradiation dose increasing from 1 x 10{sup 15} to 3 x 10{sup 16} ions/cm{sup 2}, the passive current density, closely related to the surface corrosion resistance, increased remarkably. The mechanism of the corrosion behavior transformation was due to the recrystallization of the amorphous phase induced by the lower ion irradiation.

Wan Qian [Department of Engineering Physics, Tsinghua University, Beijing100084 (China)]. E-mail: wanqian99@tsinghua.org.cn; Bai Xinde [Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang Xiangyu [Department of Engineering Physics, Tsinghua University, Beijing100084 (China)

2006-02-02

228

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

229

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

230

Graph anomalies in cyber communications  

SciTech Connect

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

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

2011-01-11

231

Measuring anomaly with algorithmic entropy  

NASA Astrophysics Data System (ADS)

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

Solano, Wanda M.

232

Spacecraft environmental anomalies expert system  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

233

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

234

Ebstein's anomaly: the Broussais approach.  

PubMed

Ebstein's anomaly is rare, but it is the most frequent cause of congenital tricuspid valve anomaly. For many years valve replacement was performed. Conservative techniques are now preferred due to improvement of the results. The goals of surgery are to restore a normal tricuspid valve function, to preserve the right ventricular contractility and to decrease the risk of rhythm disturbances. Basically, the technique is based on mobilization of the anterior leaflet and longitudinal plication of the right ventricle. A bidirectional cavo pulmonary shunt is used in severe cases. Results are correlated with the severity of the disease, the expertise of the surgical team and also with the perioperative management. PMID:24415583

Chauvaud, Sylvain; Carpentier, Alain

2008-01-01

235

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

236

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; Röckmann, Thomas; Savarino, Joël

2014-05-01

237

Vanadium isotopic difference between the silicate Earth and meteorites  

NASA Astrophysics Data System (ADS)

It has been argued that the stable isotopic composition of the element vanadium (V) provides a potential indicator of the effects high-energy irradiation early in Solar System development. Such irradiation would produce enrichment in the minor isotope, 50V compared with the 400 times more abundant 51V (Gounelle et al., 2001; Lee et al., 1998). Here we show that the vanadium isotopic composition of the silicate Earth is enriched in 51V by ?0.8‰ compared with carbonaceous and ordinary chondrites as well as achondrites from Mars and the asteroid 4 Vesta. Although V is depleted by core formation, experiments reveal no isotopic fractionation between metal and silicate that could account for the observed difference in V isotope composition between terrestrial and extraterrestrial materials. Nucleosynthetic provenance of the terrestrial vanadium isotope offset is inconsistent with anomalies of other nucleosynthetically produced isotopes in bulk meteorites, which are more variable than vanadium (Burkhardt et al., 2011; Carlson et al., 2007; Trinquier et al., 2009). Furthermore, V isotopes are unlikely to have been affected by volatilization, parent body alteration or impact erosion of Earth's surface. Therefore, the cause of the isotopic difference is unclear. One possibility is that Earth's isotopically heavier V reflects a deficit in material irradiated during the initial stages of Solar System formation. Whatever the cause, the terrestrial deficit in 50V implies that bulk Earth cannot be entirely reconstructed by mixtures of different meteorites.

Nielsen, Sune G.; Prytulak, Julie; Wood, Bernard J.; Halliday, Alex N.

2014-03-01

238

Solvation of fluoroform and fluoroform-dimethylether dimer in liquid krypton: A theoretical cryospectroscopic study  

NASA Astrophysics Data System (ADS)

A hybrid, sequential statistical physics-quantum mechanical electronic-quantum mechanical nuclei approach has been applied to study the C-H stretching frequencies of bare fluoroform dissolved in liquid krypton under cryogenic conditions (at ˜130 K), as well as upon blue shifting hydrogen bonding interactions with dimethylether in the same solvent. The structure of the liquid at 130 K was generated by Monte Carlo simulations of cryogenic Kr solutions containing either fluoroform or fluoroform and dimethylether molecules. Statistically uncorrelated configurations were appropriately chosen from the equilibrated MC runs and supermolecular clusters containing solute and solvent molecules (either standalone or embedded in the "bulk" part of the solvent treated as a polarizable continuum) were subjected to quantum mechanical electronic (QMel) and subsequent quantum mechanical nuclei (QMnuc) calculations. QMel calculations were implemented to generate the in-liquid 1D intramolecular C-H stretching vibrational potential of the fluoroform moiety and subsequently in the QMnuc phase the corresponding anharmonic C-H stretching frequency was computed by diagonalization techniques. Finally, the constructed vibrational density of states histograms were compared to the experimental Raman bands. The calculated anharmonic vibrational frequency shifts of the fluoroform C-H stretching mode upon interaction with dimethylether in liquid Kr are in very good agreement with the experimental data (20.3 at MP2 level vs. 16.6 cm-1 experimentally). Most of this relatively large frequency blue shift is governed by configurations characterized by a direct C-H⋯O contact between monomers. The second population detected during MC simulations, characterized by reversed orientation of the monomers, has a minor contribution to the spectral appearance. The experimentally observed trend in the corresponding bandwidths is also correctly reproduced by our theoretical approach. Solvation of the fluoroform monomer, according to experiment, results in small C-H stretching frequency red shift (˜-2 cm-1), while our approach predicts a blue shift of about 10 cm-1. By a detailed analysis of the anharmonic C-H stretching frequency dependence on the position of the nearest solvent krypton atom and also by analyzing the vibrational Stark effect induced by the local fluctuating field component parallel to the C-H axis, we have derived several conclusions related to these observations. The frequency vs. C⋯Kr distance dependence shows appreciable fluctuations and even changes in sign at R values close to the maximum of the C⋯Kr radial distribution function, so that most of the first-shell Kr atoms are located at positions at which the CH frequency shifts acquire either small negative or small positive values. It so happens, therefore, that even the actual sign of the frequency shift is strongly dependent on the correct description of the first solvation shell around CF3H by the Monte Carlo method, much more than the other in-liquid properties calculated by similar approaches.

Kohls, Emilija; Mishev, Anastas; Pejov, Ljup?o

2013-08-01

239

Solvation of fluoroform and fluoroform-dimethylether dimer in liquid krypton: a theoretical cryospectroscopic study.  

PubMed

A hybrid, sequential statistical physics-quantum mechanical electronic-quantum mechanical nuclei approach has been applied to study the C-H stretching frequencies of bare fluoroform dissolved in liquid krypton under cryogenic conditions (at ~130 K), as well as upon blue shifting hydrogen bonding interactions with dimethylether in the same solvent. The structure of the liquid at 130 K was generated by Monte Carlo simulations of cryogenic Kr solutions containing either fluoroform or fluoroform and dimethylether molecules. Statistically uncorrelated configurations were appropriately chosen from the equilibrated MC runs and supermolecular clusters containing solute and solvent molecules (either standalone or embedded in the "bulk" part of the solvent treated as a polarizable continuum) were subjected to quantum mechanical electronic (QMel) and subsequent quantum mechanical nuclei (QMnuc) calculations. QMel calculations were implemented to generate the in-liquid 1D intramolecular C-H stretching vibrational potential of the fluoroform moiety and subsequently in the QMnuc phase the corresponding anharmonic C-H stretching frequency was computed by diagonalization techniques. Finally, the constructed vibrational density of states histograms were compared to the experimental Raman bands. The calculated anharmonic vibrational frequency shifts of the fluoroform C-H stretching mode upon interaction with dimethylether in liquid Kr are in very good agreement with the experimental data (20.3 at MP2 level vs. 16.6 cm(-1) experimentally). Most of this relatively large frequency blue shift is governed by configurations characterized by a direct C-H···O contact between monomers. The second population detected during MC simulations, characterized by reversed orientation of the monomers, has a minor contribution to the spectral appearance. The experimentally observed trend in the corresponding bandwidths is also correctly reproduced by our theoretical approach. Solvation of the fluoroform monomer, according to experiment, results in small C-H stretching frequency red shift (~-2 cm(-1)), while our approach predicts a blue shift of about 10 cm(-1). By a detailed analysis of the anharmonic C-H stretching frequency dependence on the position of the nearest solvent krypton atom and also by analyzing the vibrational Stark effect induced by the local fluctuating field component parallel to the C-H axis, we have derived several conclusions related to these observations. The frequency vs. C···Kr distance dependence shows appreciable fluctuations and even changes in sign at R values close to the maximum of the C···Kr radial distribution function, so that most of the first-shell Kr atoms are located at positions at which the CH frequency shifts acquire either small negative or small positive values. It so happens, therefore, that even the actual sign of the frequency shift is strongly dependent on the correct description of the first solvation shell around CF3H by the Monte Carlo method, much more than the other in-liquid properties calculated by similar approaches. PMID:23927267

Kohls, Emilija; Mishev, Anastas; Pejov, Ljup?o

2013-08-01

240

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

241

Gravitational Anomaly and Transport Phenomena  

Microsoft Academic Search

Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity

Karl Landsteiner; Eugenio Megías; Francisco Pena-Benitez

2011-01-01

242

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

243

Development anomalies of the occiput  

Microsoft Academic Search

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

J. Wickenhauser; O. Hochberg

1974-01-01

244

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. PMID:19528640

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

2009-01-01

245

The abundance and isotopic composition of Cd in iron meteorites  

NASA Astrophysics Data System (ADS)

Cadmium is a highly volatile element and its abundance in meteorites may help better understand volatility-controlled processes in the solar nebula and on meteorite parent bodies. The large thermal neutron capture cross section of 113Cd suggests that Cd isotopes might be well suited to quantify neutron fluences in extraterrestrial materials. The aims of this study were (1) to evaluate the range and magnitude of Cd concentrations in magmatic iron meteorites, and (2) to assess the potential of Cd isotopes as a neutron dosimeter for iron meteorites. Our new Cd concentration data determined by isotope dilution demonstrate that Cd concentrations in iron meteorites are significantly lower than in some previous studies. In contrast to large systematic variations in the concentration of moderately volatile elements like Ga and Ge, there is neither systematic variation in Cd concentration amongst troilites, nor amongst metal phases of different iron meteorite groups. Instead, Cd is strongly depleted in all iron meteorite groups, implying that the parent bodies accreted well above the condensation temperature of Cd (i.e., ?650 K) and thus incorporated only minimal amounts of highly volatile elements. No Cd isotope anomalies were found, whereas Pt and W isotope anomalies for the same iron meteorite samples indicate a significant fluence of epithermal and higher energetic neutrons. This observation demonstrates that owing to the high Fe concentrations in iron meteorites, neutron capture mainly occurs at epithermal and higher energies. The combined Cd-Pt-W isotope results from this study thus demonstrate that the relative magnitude of neutron capture-induced isotope anomalies is strongly affected by the chemical composition of the irradiated material. The resulting low fluence of thermal neutrons in iron meteorites and their very low Cd concentrations make Cd isotopes unsuitable as a neutron dosimeter for iron meteorites.

Kruijer, Thomas S.; Sprung, Peter; Kleine, Thorsten; Leya, Ingo; Wieler, Rainer

2013-12-01

246

Neurofibromas with imaging characteristics resembling vascular anomalies.  

PubMed

OBJECTIVE. Although neurofibromas are rare, their initial clinical and imaging presentation can mimic those of vascular anomalies, particularly if the characteristic clinical features of neurofibromatosis are not present. The diagnostic challenges encountered in five cases of histologically proven neurofibromas, initially diagnosed as vascular anomalies, are reviewed and discussed. CONCLUSION. The clinical and imaging differences between neurofibromas and vascular anomalies are detailed with the histopathologic features to better understand why some neurofibromas are diagnosed as vascular anomalies. PMID:25415736

Yilmaz, Sabri; Ozolek, John A; Zammerilla, Lauren L; Fitz, Charles R; Grunwaldt, Lorelei J; Crowley, John J

2014-12-01

247

Barium anomaly preceding K\\/T boundary: possible causes and implications on end Cretaceous events of K\\/T sections in Cauvery basin (India), Israel, NE-Mexico and Guatemala  

Microsoft Academic Search

Maastrichtian–Danian strata of the Cauvery basin as well as selected sections of NE-Mexico, Guatemala and Israel record Ba anomalies, away from the Cretaceous\\/Tertiary boundary (KTB) in addition to common occurrences of geochemical and stable isotopic anomalies across the KTB. Ba anomalies were recorded in monotonous shallow marine sandstones of the Cauvery basin (south India) which contain minor amounts of Ba-orthoclase.

M. Ramkumar; M. Harting; D. Stüben

2005-01-01

248

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. PMID:24014975

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

2013-01-01

249

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  

USGS Publications Warehouse

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 = 3 molal) were analyzed by laser microprobe noble-gas mass spectrometry (lmngms) on neutron-irradiated samples. The concentrations of 36Ar (4.7 ?? 10-8 molal) and 84Kr 1.8 ?? 10-9 molal) in the fluid inclusions are equal to those of fresh surface waters in equilibrium with air at approximately 20 ?? 5??. The mole ratios of Br Cl (1.2 ?? 10-4) and I Cl (1-2 ?? 10-6) are among the lowest measured in any natural waters, similar to those of modern brines formed by dissolution of Permian NaCl-bearing evaporites in southeast New Mexico. 40Ar 36Ar ratios (600) are twice that of air, and indicate that the fluid inclusions had excess radiogenic 40Ar (1.4 ?? 10-5 molal) when trapped. The amount of excess 40Ar appears to be too large to have been acquired with Cl by congruent dissolution of halite-bearing evaporites, and possibly too small to have been acquired with Pb by congruent dissolution of granitic basement rocks with Proterozoic KAr ages. From the lmngms data, combined with published Pb and S isotope data, we infer the following sequence of events in the history of the Hansonburg MVT hydrothermal brine: (1) the brine originated as relatively dilute meteoric water, and it did not gain or lose atmospheric Ar or Kr after recharge; (2) the originally dilute fluid acquired the bulk of its Cl and sulfate in the subsurface after recharge by dissolving halite-bearing Permian? marine evaporites; (3) the high salinity brine then acquired most of its Pb and excess radiogenic 40Ar from interactions with aquifer rocks other than evaporites, possibly clastic sedimentary rocks or basement rocks with Phanerozoic KAr "ages"; and (4) the brine deposited fluorite without having boiled or degassed. ?? 1992.

Böhlke, J.K.; Irwin, J.J.

1992-01-01

250

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

251

Novel sorbent development and evaluation for the capture of krypton and xenon from nuclear fuel reprocessing off-gas stream  

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, Idaho National Laboratory 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. (authors)

Garn, T.G.; Greenhalgh, M.R.; Law, J.D. [Idaho National Laboratory, 1625 N. Fremont Ave., Idaho Falls, ID 83415 (United States)

2013-07-01

252

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

253

Monoamniotic twins discordant for body stalk anomaly.  

PubMed

Abstract Body stalk anomaly is a rare malformation. This anomaly in monozygotic twins is extremely unusual. We describe a case of monoamniotic pregnancy discordant for body stalk anomaly diagnosed at 11 weeks. Ultrasound showed a fetus with a large anterior abdominal wall defect, anomaly of the spine and no evidence of lower extremities and other with a normal morphology. As far as our concern, only three monoamniotic pregnancies discordant for this malformation were reported. Our case represents the fourth reported monoamniotic pregnancy discordant for body stalk anomaly with diagnosis made by ultrasound and the second diagnosed in the first trimester. PMID:24588260

Tavares, Mariana Vide; Domingues, Ana Patrícia; Tavares, Margarida; Fonseca, Etelvina; Moura, Paulo

2015-01-01

254

Echocardiographic Assessment of Ebstein's Anomaly.  

PubMed

Ebstein's anomaly is a complex congenital lesion which primarily involves the tricuspid valve. The tricuspid leaflets are tethered to varying degrees to the right ventricular free wall and the ventricular septum often resulting in significant tricuspid regurgitation and a small functioning right ventricular chamber. Although the septal leaflet originates normally at the right atrioventricular junction, the proximal portion is often completely tethered to the ventricular septum resulting in a misconception and erroneous statements in many publications that its attachment is apically displaced. Although two-dimensional echocardiography represents the primary modality for the diagnosis of this anomaly, three-dimensional echocardiography provides incremental value in characterizing the extent and severity of tethering of individual tricuspid valve leaflets. This information is useful in surgical decision making whether to repair or replace the tricuspid valve. PMID:24888693

Booker, Oscar J; Nanda, Navin C

2015-01-01

255

Anomaly Mediation and Dimensional Transmutation  

E-print Network

We show how a sparticle spectrum characteristic of anomaly mediation can arise from a theory whose Lagrangian contains no explicit mass scale. The scale of supersymmetry breaking is governed by the gravitino mass, which is the vacuum expectation value of the F-term of the conformal compensator field, and the tachyonic slepton problem is resolved by the breaking of a U(1) gauge symmetry at a scale determined by dimensional transmutation.

D. R. T. Jones; G. G. Ross

2006-09-20

256

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

257

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

258

6d, Coulomb branch anomaly matching  

NASA Astrophysics Data System (ADS)

6d QFTs are constrained by the analog of 't Hooft anomaly matching: all anomalies for global symmetries and metric backgrounds are constants of RG flows, and for all vacua in moduli spaces. We discuss an anomaly matching mechanism for 6d theories on their Coulomb branch. It is a global symmetry analog of Green-Schwarz-West-Sagnotti anomaly cancellation, and requires the apparent anomaly mismatch to be a perfect square, . Then ? I 8 is cancelled by making X 4 an electric/magnetic source for the tensor multiplet, so background gauge field instantons yield charged strings. This requires the coefficients in X 4 to be integrally quantized. We illustrate this for theories. We also consider the SCFTs from N small E8 instantons, verifying that the recent result for its anomaly polynomial fits with the anomaly matching mechanism.

Intriligator, Kenneth

2014-10-01

259

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

260

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

261

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

262

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 Earth’s 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

263

Limb anomalies in chromosomal aberrations.  

PubMed

This survey shows that there are at least 6 autosomal and 2 gonosomal aberrations which may produce specific types of limb anomaly in 30%-80% of cases. The "expressivity" of these anomalies covers a wide range within the morphogenetic pattern. No entirely specific malformation type is seen. The most unusual malformation, aplasia of the thumbs with proximal synostosis of the 4th aand 5th metacarpals, is seen in 13q- (13r) but the precise cytogenetic basis is not clear. Aplasia of the thumb associated with synostosis of the 4th and 5th metacarpals was occasionally described before (unilateral [105], bilateral [106] while synostosis only (V or Y shaped) may be due to a dominant [107] or an X-linked recessive gene [108]. Reduction malformations limited to radial heminelia have been noted in 4q- (4r) and in trisomy 18. Although the number of cases is still small the pattern is similar to that of thalidomide embryopathy, radial hemimelia (AD, 17910), cardiodigital syndromes (AD, 14290), and even Fanconi panmyelopathy (AR, 22790). It ranges from hypoplasia of the thenar muscles and thumb to pseudophocomelia which should be clearly distinguished from phocomelia because of the absence of the thumb and frequently of the 2nd and 3rd fingers. Nothing has to be added to the teratologic series published by Müller [58] and, more recently, Willert and Henkel [109], but the distribution of the various manifestations may diverge. Asymmetry in 4q- (4r) is noteworthy. Postaxial polydactyly which is noted in trisomy 13 and trisomy of the terminal portions of the long arm of No. 13 is as variable in distribution and morphology as is observed in families in which the gene (AD, 17420) is transmitted. The question cannot yet be answered whether infrequent anomalies of the limbs which do not fit into the morphologic pattern of these types, eg postaxial polydactyly in + 18 or absence of the radius in + 13 are random. Syndactyly of the 3rd and 4th but also of other digits is a frequent but variable anomaly in triploidy. It is very similar to hereditary zygodactyly (AD, 18590). Peripheral hypoplasia of several digits accompanied by onychodysplasia seems to be a frequent anomaly in 9p+ syndrome. It is similar to that seen in a syndrome with mental deficiency, peculiar facies, and stunted growth [110] in which no chromosomal aberration has been found up to the present. Dysostoses have been frequently noted in gonosomal aberations. Brachymetopodia in XO females maybe confused with pseudo-pseudohypoparathyroidism (XR, 30080) or brachydactyly type E (AD, 11330) when only the lateral metacarpals and/or metatarsals are shortened. However, further studies are needed in order to delineate these syndromes on the basis of different frequencies and radiologic patterns. The radioulnar synostosis noted in cases with supernumerary X chromosomes cannot be distinguished from the inherited anomaly (AD, 17930), but associated anomalies of the hand are uncommon. PMID:322750

Pfeiffer, R A; Santelmann, R

1977-01-01

264

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

SciTech Connect

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

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

2003-12-17

265

Stable isotope studies  

SciTech Connect

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

Ishida, T.

1992-01-01

266

Space Weather, Cosmic Rays, and Satellite Anomalies  

NASA Astrophysics Data System (ADS)

Results are presented of the Satellite Anomaly Project, which aims to improve the methods of safeguarding satellites in the Earth’s magnetosphere from the negative effects of the space environment. Anomaly data from the USSR and Russian “Kosmos” series satellites in the period 1971-1999 are combined into one database, together with similar information on other spacecraft. This database contains, beyond the anomaly information, various characteristics of space weather: geomagnetic activity indices (Ap, AE and Dst), fluxes and fluencies of electrons and protons at different energies, high energy cosmic ray variations and other solar, interplanetary and solar wind data. A comparative analysis of the distribution of each of these parameters relative to satellite anomalies was carried out for the total number of anomalies (about 6000 events), and separately for high altitude orbit satellites ( 5000 events) and low altitude (about 800 events). No relation was found between low and high altitude satellite anomalies. Daily numbers of satellite anomalies, averaged by a superposed epoch method around sudden storm commencements and proton event onsets for high (>1500 km) and low (<1500 km) altitude orbits revealed a big difference in behavior. Satellites were divided into several groups according to their orbital characteristics (altitude and inclination). The relation of satellite anomalies to the environmental parameters was found to be different for various orbits, and this should be taken into account when developing anomaly frequency models. The preliminary anomaly frequency models are presented.

Lev, Dorman

267

Strictly anomaly mediated supersymmetry breaking  

NASA Astrophysics Data System (ADS)

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

Hindmarsh, Mark; Jones, D. R. Timothy

2013-04-01

268

Mass-independent isotope fractionation of Mo, Ru, Cd, and Te  

NASA Astrophysics Data System (ADS)

The variation of the mean charge distribution in the nucleus with the neutron number of different isotopes induces a tenuous shift of the nuclear field. The mass fractionation induced during phase changes is irregular, notably with 'staggering' between odd and even masses, and becomes increasingly non-linear for neutron-rich isotopes. A strong correlation is observed between the deviation of the isotopic effects from the linear dependence with mass and the corresponding nuclear charge radii. We first demonstrated on a number of elements the existence of such mass-independent isotope fractionation in laboratory experiments of solvent extraction with a macrocyclic compound. The isotope ratios were analyzed by multiple-collector inductively coupled plasma mass spectrometry with a typical precision of <100 ppm. The isotopes of odd and even atomic masses are enriched in the solvent to an extent that closely follows the variation of their nuclear charge radii. The present results fit Bigeleisen's (1996) model, which is the standard mass-dependent theory modified to include a correction term named the nuclear field shift effect. For heavy elements like uranium, the mass-independent effect is important enough to dominate the mass-dependent effect. We subsequently set out to compare the predictions of Bigeleisen's theory with the isotopic anomalies found in meteorites. Some of these anomalies are clearly inconsistent with nucleosynthetic effects (either s- or r-processes). Isotopic variations of Mo and Ru in meteorites, especially in Allende (CV3), show a clear indication of nucleosynthetic components. However, the mass-independent anomaly of Ru observed in Murchison (CM2) is a remarkable exception which cannot be explained by the nucleosynthetic model, but fits the nuclear field shift theory extremely well. The abundances of the even atomic mass Te isotopes in the leachates of carbonaceous chondrites, Allende, Murchison, and Orgueil, fit a mass-dependent law well, but the odd atomic mass isotope ^{125}Te clearly deviates from this correlation. The nuclear field shift theory shows that there is no effect on ^{130}Te but that the ^{125}Te anomaly is real. Carbonaceous chondrites do not reveal significant isotope fractionation of Cd isotopes, but a nuclear field shift effect is clearly present in type-3 (unequilibrated) ordinary chondrites. The nuclear field shift effect is temperature dependent and is probably more frequent in nature than commonly thought. It remains, together with nucleosynthetric anomalies, perfectly visible through the normalization of isotopic ratios to a reference value. In meteorites, this effect may originate both during condensation/evaporation processes in the nebular gas and during the metamorphism of the meteorite parent bodies.

Fujii, T.; Moynier, F.; Albarède, F.

2006-12-01

269

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

270

Sea level anomalies exacerbate beach erosion  

NASA Astrophysics Data System (ADS)

level anomalies are intra-seasonal increases in water level forced by meteorological and oceanographic processes unrelated to storms. The effects of sea level anomalies on beach morphology are unknown but important to constrain because these events have been recognized over large stretches of continental margins. Here, we present beach erosion measurements along Onslow Beach, a barrier island on the U.S. East Coast, in response to a year with frequent sea level anomalies and no major storms. The anomalies enabled extensive erosion, which was similar and in most places greater than the erosion that occurred during a year with a hurricane. These results highlight the importance of sea level anomalies in facilitating coastal erosion and advocate for their inclusion in beach-erosion models and management plans. Sea level anomalies amplify the erosive effects of accelerated sea level rise and changes in storminess associated with global climate change.

Theuerkauf, Ethan J.; Rodriguez, Antonio B.; Fegley, Stephen R.; Luettich, Richard A.

2014-07-01

271

Nickel and chromium isotopes in Allende inclusions  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

272

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. PMID:25024805

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

2014-01-01

273

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

SciTech Connect

In this work we study the influence of relativistic effects, in particular spin-orbit coupling, on electronic decay processes in KrXe{sub 2} 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.

Zobel, J. Patrick; Kryzhevoi, Nikolai V., E-mail: Nikolai.Kryzhevoi@pci.uni-heidelberg.de; Pernpointner, Markus, E-mail: Markus.Pernpointner@pci.uni-heidelberg.de [Physikalisch-Chemisches Institut, Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)] [Physikalisch-Chemisches Institut, Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

2014-04-28

274

Anomaly polynomial of general 6D SCFTs  

NASA Astrophysics Data System (ADS)

We describe a method to determine the anomaly polynomials of general 6D mathcal {N}={(2,0)} and mathcal {N}={(1,0)} superconformal field theories (SCFTs), in terms of the anomaly matching on their tensor branches. This method is almost purely field theoretical, and can be applied to all known 6D SCFTs. We demonstrate our method in many concrete examples, including mathcal {N}={(2,0)} theories of arbitrary type and the theories on M5 branes on asymptotically locally Euclidean (ALE) singularities, reproducing the N^3 behavior. We check the results against the anomaly polynomials computed M-theoretically via the anomaly inflow.

Ohmori, Kantaro; Shimizu, Hiroyuki; Tachikawa, Yuji; Yonekura, Kazuya

2014-10-01

275

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

276

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

NASA Technical Reports Server (NTRS)

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

Arrhenius, G.

1983-01-01

277

Photochemical mass-independent sulfur isotopes in achondritic meteorites.  

PubMed

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

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

2005-08-12

278

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

279

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 5×1011 atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently 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

280

Modeling Multiple Time Series for Anomaly Detection  

Microsoft Academic Search

Our goal is to generate comprehensible and accurate models from multiple time series for anomaly detection. The models need to produce anomaly scores in an online man- ner for real-life monitoring tasks. We introduce three algo- rithms that work in a constructed feature space and evaluate them with a real data set from the NASA shuttle program. Our offline and

Philip K. Chan; Matthew V. Mahoney

2005-01-01

281

Disparity : scalable anomaly detection for clusters.  

SciTech Connect

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

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

2008-01-01

282

Uhl's anomaly: a difficult prenatal diagnosis.  

PubMed

Uhl's anomaly is an evolutive disease leading to terminal right ventricular failure. The most difficult differential diagnosis at presentation is the Ebstein disease. We describe the evolution of a foetus with Uhl's anomaly from 21 to 30 weeks of gestation, with progressive reduction in the right ventricular anterior myocardium suggestive of apoptosis, leading to foetal demise. PMID:24784726

Vaujois, Laurence; van Doesburg, Nicolaas; Raboisson, Marie-Josée

2015-03-01

283

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

284

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

285

Magnetic resonance images of neuronal migration anomalies.  

PubMed

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

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

1998-08-01

286

Sources of Near Side Lunar Magnetic Anomalies  

NASA Technical Reports Server (NTRS)

Lunar Prospector magnetometer data has been used to identify a number of nearside magnetic anomalies. Some of the features identified appear to correlate with impact ejecta, supporting a basin ejecta origin to the nearside anomalies. Additional information is contained in the original extended abstract.

Richmond, Nicola C.; Hood, Lon L.; Halekas, J. S.; Mitchell, D. L.; Lin, R. P.; Acuna, M. H.; Binder, A.B.

2002-01-01

287

ChemTeacher: Isotopes  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Isotopes page includes resources for teaching students about the structure and uses of isotopes.

2011-01-01

288

Isotopes and Hydrology  

NSDL National Science Digital Library

This program provides a clickable periodic table that links elements to additional information about their isotopic systems. Information is provided about the isotopes important to hydrology, their applications, how they are measured, and how much it costs for an analysis.

2008-09-29

289

Classical anomalies for spinning particles  

NASA Astrophysics Data System (ADS)

We discuss the phenomenon of classical anomaly. It is observed for 3D Berezin-Marinov (BM), Barducci-Casalbuoni-Lusanna (BCL) and Cortés-Plyushchay-Velázquez (CPV) pseudoclassical spin particle models. We show that quantum mechanically these different models correspond to the same P, T-invariant system of planar fermions, but the quantum system has global symmetries being not reproducible classically in full in any of the models. We demonstrate that the specific U(1) gauge symmetry characterized by the opposite coupling constants of spin s = + {1}/{2} and s = - {1}/{2} states has a natural classical analog in the CPV model but can be reproduced in the BM and BCL models in an obscure and rather artificial form. We also show that the BM and BCL models quantum mechanically are equivalent in any odd-dimensional space-time, but describe different quantum systems in even space-time dimensions.

Gamboa, Jorge; Plyushchay, Mikhail

1998-02-01

290

A New, Principled Approach to Anomaly Detection  

SciTech Connect

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

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

2012-01-01

291

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

292

Trends in hemispheric warm and cold anomalies  

NASA Astrophysics Data System (ADS)

a spatial percentile approach, we explore the magnitude of temperature anomalies across the Northern and Southern Hemispheres. Linear trends in spatial percentile series are estimated for 1881-2013, the most recent 30 year period (1984-2013), and 1998-2013. All spatial percentiles in both hemispheres show increases from 1881 to 2013, but warming occurred unevenly via modification of cold anomalies, producing a reduction in spatial dispersion. In the most recent 30 year period, trends also were consistently positive, with warm anomalies having much larger warming rates than those of cold anomalies in both hemispheres. This recent trend has largely reversed the decrease in spatial dispersion that occurred during the twentieth century. While the period associated with the recent slowdown of global warming, 1998-2013, is too brief to estimate trends reliably, cooling was evident in NH warm and cold anomalies during January and February while other months in the NH continued to warm.

Robeson, Scott M.; Willmott, Cort J.; Jones, Phil D.

2014-12-01

293

An impactor origin for lunar magnetic anomalies.  

PubMed

The Moon possesses strong magnetic anomalies that are enigmatic given the weak magnetism of lunar rocks. We show that the most prominent grouping of anomalies can be explained by highly magnetic extralunar materials from the projectile that formed the largest and oldest impact crater on the Moon: the South Pole-Aitken basin. The distribution of projectile materials from a model oblique impact coincides with the distribution of magnetic anomalies surrounding this basin, and the magnetic properties of these materials can account for the intensity of the observed anomalies if they were magnetized in a core dynamo field. Distal ejecta from this event can explain the origin of isolated magnetic anomalies far from this basin. PMID:22403388

Wieczorek, Mark A; Weiss, Benjamin P; Stewart, Sarah T

2012-03-01

294

An Impactor Origin for Lunar Magnetic Anomalies  

NASA Astrophysics Data System (ADS)

The Moon possesses strong magnetic anomalies that are enigmatic given the weak magnetism of lunar rocks. We show that the most prominent grouping of anomalies can be explained by highly magnetic extralunar materials from the projectile that formed the largest and oldest impact crater on the Moon: the South Pole-Aitken basin. The distribution of projectile materials from a model oblique impact coincides with the distribution of magnetic anomalies surrounding this basin, and the magnetic properties of these materials can account for the intensity of the observed anomalies if they were magnetized in a core dynamo field. Distal ejecta from this event can explain the origin of isolated magnetic anomalies far from this basin.

Wieczorek, Mark A.; Weiss, Benjamin P.; Stewart, Sarah T.

2012-03-01

295

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

296

Zirconium isotope separation  

SciTech Connect

A method of separating zirconium isotopes by converting the zirconium to its iodide salt prior to separation by usual isotope methods is disclosed. After separation the desired isotopes are converted from the salt to the metal by the van Arkel-de Boer iodide process.

Siddall, M.B.

1984-12-11

297

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

298

Refining of atmospheric transport model entries by the globally observed passive tracer distributions of 85krypton and sulfur hexafluoride (SF6)  

Microsoft Academic Search

Our high precision database of the global distribution of SF6 in the troposphere [Maiss et al., 1996] is used in a two-dimensional atmospheric transport model (2D-HD model) to study the behavior of this new tracer in comparison to the classical global atmospheric transport tracer krypton 85. The 2D-HD model grid has been derived from the three-dimensional Hamburg TM2 model with

Ingeborg Levin; Vago Hesshaimer

1996-01-01

299

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

SciTech Connect

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

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

1991-08-01

300

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

NASA Astrophysics Data System (ADS)

We present new precise U-Th ages of well-preserved coral specimens collected from the island of Barbados, West Indies, and the atoll of Mururoa, French Polynesia. Our new data confirm the ages attributed to oxygen isotope stage 7 in the framework of the Milankovitch theory (BERGER, 1978; Mar-TINSON et al., 1987). By using thermal ionization mass spectrometry (TIMS), it is also possible to quantify precisely the 234U /238U ratios in corals. Samples older than 150 kyr B.P. are shown to be characterized by significant excesses of 234U relative to the uranium isotopic composition expected if the corals grew in present-day sea water. Assuming that the 230Th-ingrowth ages are accurate, these anomalies translate into high initial 234U /238U ratios: about 1.2 at 200 kyr and up to 1.5 at about 450 kyr B.P. We propose that the anomalies result from both diagenetic addition and replacement of U and possibly from global changes in the 234U /238U composition of sea water through time. The 234U anomalies cast doubt on the accuracy of the classical 230Th-ingrowth dating method in old corals, and in particular for the use of measured 234U /238U ratios alone to date corals older than 150 kyr.

Bard, Edouard; Fairbanks, Richard G.; Hamelin, Bruno; Zindler, Alan; Chi, Track Hoang

1991-08-01

301

Thermal Infrared Anomalies of Several Strong Earthquakes  

PubMed Central

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

Wei, Congxin; Guo, Xiao; Qin, Manzhong

2013-01-01

302

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. PMID:24455078

Doni, Bharati; Kaswan, Sumita; Rahman, Farzan

2013-01-01

303

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

304

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

305

MG Isotopic Measurement of FIB-Isolated Presolar Silicate Grains  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

306

Tunguska Genetic Anomaly and Electrophonic Meteors  

NASA Astrophysics Data System (ADS)

One of great mysteries of the Tunguska event is its genetic impact. Some genetic anomalies were reported in the plants, insects and people of the Tunguska region. Remarkably, the increased rate of biological mutations was found not only within the epicenter area, but also along the trajectory of the Tunguska Space Body (TSB). At that no traces of radioactivity were found, which could be reliably associated with the Tunguska event. The main hypotheses about the nature of the TSB, a stony asteroid, a comet nucleus or a carbonaceous chondrite, readily explain the absence of radioactivity but give no clues how to deal with the genetic anomaly. A choice between these hypotheses, as far as the genetic anomaly is concerned, is like to the choice between ``blue devil, green devil and speckled devil'', to quote late Academician N.V. Vasilyev. However, if another mysterious phenomenon, electrophonic meteors, is evoked, the origin of the Tunguska genetic anomaly becomes less obscure.

Silagadze, Z. K.

2005-03-01

307

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

308

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

309

Chemical Compositions and Anomalies in Stellar Coronae  

NASA Technical Reports Server (NTRS)

In summary, as the papers cited here and in earlier reports demonstrate, this award has enabled us to obtain a fairly good picture of the abundance anomalies in stellar coronae. The "inverse FIP" effect in very active stars has now been fleshed out as a more complex anomaly depending on FIP, whereas before it appeared only in terms of a general metal paucity, the recent solar abundance assessment of Asplund et a1 will, if correct, challenge some of the older interpretations of coronal abundance anomalies since they imply quite different relative abundances of CNO compared with Fe, Mg and Si. Further investigations have been in into the possibility of modeling some of the recent coronal abundance anomaly results in terms of Alfven wave-driven separation of neutrals and ions in the upper chromosphere. This work still remains in the seed stage, and future funding from a different program will be requested to pursue it further.

Drake, Jeremy; Oliversen, Ronald J. (Technical Monitor)

2005-01-01

310

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

311

Bulk chemical and Hf-W isotopic consequences of incomplete accretion during planet formation  

NASA Astrophysics Data System (ADS)

Late-stage accretion involves collisions which may result in complete or incomplete merging of the two objects, hit-and-run encounters, or mass loss from the target. We use a recent N-body study incorporating these different collision styles (Chambers, J.E. [2013]. Icarus 224, 43-56) to investigate how collision style affects the bulk chemical and isotopic outcomes of terrestrial planet formation. Compared with simulations in which all collisions result in perfect mergers, the variability in modeled silicate mass fraction and tungsten isotope anomaly is larger, especially for lower-mass planets. The final tungsten anomaly also shows a systematic reduction, because the timescale to finish planet growth is longer when incomplete mergers are included. Simulations including incomplete merging can reproduce the observed scatter in both tungsten anomaly and silicate mass fraction of the terrestrial planets.

Dwyer, Christina A.; Nimmo, Francis; Chambers, John E.

2015-01-01

312

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

313

“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

314

Probabilistic anomaly detection in distributed computer networks  

Microsoft Academic Search

Distributed host-based anomaly detection has not yet proven practical due to the ex- cessive computational overhead during training and detection. This paper considers an efficient algorithm for detecting resource anomalies in event streams with either Poisson or long-tailed arrival processes. A form of distributed, lazy evaluation is pre- sented, which uses a model for human-computer interaction based two-dimensional time and

Mark Burgess

2006-01-01

315

CP-violating CFT and trace anomaly  

E-print Network

It is logically possible that the trace anomaly in four dimension includes the Hirzebruch-Pontryagin density in CP violating theories. Although the term vanishes at free conformal fixed points, we realize such a possibility in the holographic renormalization group and show that it is indeed possible. The Hirzebruch-Pontryagin term in the trace anomaly may serve as a barometer to understand how much CP is violated in conformal field theories.

Yu Nakayama

2012-01-26

316

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

317

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

318

Congenital anomaly surveillance in England and Wales.  

PubMed

The National Congenital Anomaly System (NCAS) was set up in 1964, following the thalidomide epidemic, as a monitoring system designed to detect changes in the frequency of reporting of malformations. Its original aim was to detect anomalies reported within 7 days of birth. The NCAS is voluntary at all stages and covers all live- and stillbirths. It has two tiers; a 'passive system' receiving congenital anomaly notifications through a standard paper notification form, known as the SD56, and the congenital anomaly registers that send notifications electronically. Congenital anomalies are classified using the International Classification of Diseases codes and 10 monitoring groups. The Office for National Statistics performs a statistical analysis on a monthly, quarterly and annual basis, using the cumulative sum technique, which is the basis upon which surveillance alerts are raised within the system. The NCAS is now an open database where congenital anomalies can be notified whenever they are detected. The aim of this paper is to describe the current operation and uses of the NCAS based on guidelines for the evaluation of public health surveillance systems published by the Centers for Disease Control and Prevention. PMID:16337977

Misra, T; Dattani, N; Majeed, A

2006-03-01

319

Using Artificial Anomalies to Detect Unknown and Known Network Intrusions  

Microsoft Academic Search

Intrusion detection systems (IDSs) must be capable of detecting new and unknown attacks, or anomalies. We study the problem of building detection models for both pure anomaly detection and combined misuse and anomaly detection (i.e., detection of both known and unknown in- trusions). We propose an algorithm to generate artificial anomalies to coerce the inductive learner into discovering an accurate

Wei Fan; Matthew Miller; Salvatore J. Stolfo; Wenke Lee; Philip K. Chan

2001-01-01

320

Using artificial anomalies to detect unknown and known network intrusions  

Microsoft Academic Search

Intrusion detection systems (IDSs) must be capable of detecting new and unknown attacks, or anomalies. We study the problem of building detection models for both pure anomaly detection and combined misuse and anomaly detection (i.e., detection of both known and unknown intrusions). We show the necessity of artificial anomalies by discussing the failure to use conventional inductive learning methods to

Wei Fan; Matthew Miller; Salvatore J. Stolfo; Wenke Lee; Philip K. Chan

2004-01-01

321

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

322

Osmium Isotope Evidence for an S-Process Carrier in Primitive Chondrites  

NASA Technical Reports Server (NTRS)

The degree of isotopic mixing in the solar nebula and the nature of pre-solar components that have contributed to our solar system remain subjects of vigorous debate. Isotopic anomalies have been identified in Ca-Al inclusions in chondrites [1-4]. This indicates that refractory pre-solar components were not completely homogenized or processed away at the high temperatures experienced by CAIs. Pre-solar grains (SiC, C, etc.) are prevalent in primitive chondrites, and preserve isotopic heterogeneity resulting from the nucleosynthetic processes occurring in the stars from which these grains formed [2,4]. Several recent studies employing precise techniques for measuring Ru, Mo and Zr isotopes in bulk meteorites, have come up with varying conclusions on the degree of effectiveness of nebular mixing on the scale of bulk meteorite material. Some of these studies have reported isotopic anomalies in Mo and Ru [3,5-7], while others have not observed anomalies in Mo, Ru, or Zr [8-10]. Debate over the quality of the data, the normalization techniques employed, the absence or presence of isobaric interferences during the measurements on different types of instruments (e.g. TIMS versus ICP-MS), and other factors, has ensued [11,12].

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

2005-01-01

323

Hybrid isotope separation scheme  

DOEpatents

A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus.

Maya, Jakob (Brookline, MA)

1991-01-01

324

Hybrid isotope separation scheme  

DOEpatents

A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus. 2 figures.

Maya, J.

1991-06-18

325

Isotopes of Pennies  

NSDL National Science Digital Library

This lab activity from Science Netlinks is designed to explain the weighted averages that are used in average atomic mass calculations. Students can be expected to learn that isotopes of an element have different masses; that isotopes are atoms of the same element that have different numbers of neutrons; and that atomic mass is the weighted average of the naturally occurring isotopes of an element.

Netlinks, Science; Science, American A.

326

Isotope Ratio Mass Spectrometry.  

PubMed

Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic, chemical, and biological origins of substances. The ability to determine the source of an organic substance stems from the relative isotopic abundances of the elements which comprise the material. Because the isotope ratios of elements such as carbon, hydrogen, oxygen, sulfur, and nitrogen can become locally enriched or depleted through a variety of kinetic and thermodynamic factors, measurement of the isotope ratios can be used to differentiate between samples which otherwise share identical chemical compositions. Several sample introduction methods are now available for commercial isotope ratio mass spectrometers. Combustion is most commonly used for bulk isotopic analysis, whereas gas and liquid chromatography are predominately used for the real-time isotopic analysis of specific compounds within a mixture. Here, highlights of advances in instrumentation and applications within the last three years are provided to illustrate the impact of this rapidly growing area of research. Some prominent new applications include authenticating organic food produce, ascertaining whether or not African elephants are guilty of night-time raids on farmers' crops, and linking forensic drug and soil samples from a crime scene to a suspected point of origin. For the sake of brevity, we focus this Minireview on the isotope ratio measurements of lighter-elements common to organic sources; we do not cover the equally important field of inorganic isotope ratio mass spectrometry. PMID:19173039

Muccio, Zeland; Jackson, Glen P

2009-02-01

327

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

PubMed

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

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

2015-02-17

328

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

329

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

PubMed

The Waste Isolation Pilot Plant (WIPP) in New Mexico is the first geologic repository for disposal of transuranic nuclear waste from defense-related programs of the US Department of Energy. It is constructed within halite beds of the Permian-age Salado Formation. The Culebra Dolomite, confined within Rustler Formation evaporites overlying the Salado Formation, is a potential pathway for radionuclide transport from the repository to the accessible environment in the human-disturbed repository scenario. Although extensive subsurface characterization and numerical flow modeling of groundwater has been done in the vicinity of the WIPP, few studies have used natural isotopic tracers to validate the flow models and to better understand solute transport at this site. The advent of Atom-Trap Trace Analysis (ATTA) has enabled routine measurement of cosmogenic (81)Kr (half-life 229,000 yr), a near-ideal tracer for long-term groundwater transport. We measured (81)Kr in saline groundwater sampled from two Culebra Dolomite monitoring wells near the WIPP site, and compared (81)Kr model ages with reverse particle-tracking results of well-calibrated flow models. The (81)Kr model ages are ~130,000 and ~330,000 yr for high-transmissivity and low-transmissivity portions of the formation, respectively. Compared with flow model results which indicate a relatively young mean hydraulic age (~32,000 yr), the (81)Kr model ages imply substantial physical attenuation of conservative solutes in the Culebra Dolomite and provide limits on the effective diffusivity of contaminants into the confining aquitards. PMID:24594409

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

2014-05-01

330

Discovery of the Barium Isotopes  

E-print Network

Thirty-eight barium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

A. Shore; A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; M. Thoennessen

2009-08-13

331

Discovery of the barium isotopes  

SciTech Connect

Thirty-eight barium isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Shore, A.; Fritsch, A.; Ginepro, J.Q.; Heim, M.; Schuh, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Thoennessen, M., E-mail: thoennessen@nscl.msu.ed [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)

2010-11-15

332

Discovery of the Vanadium Isotopes  

E-print Network

Twenty-four vanadium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Shore, A; Heim, M; Schuh, A; Thoennessen, M

2009-01-01

333

Discovery of the Vanadium Isotopes  

E-print Network

Twenty-four vanadium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

A. Shore; A. Fritsch; M. Heim; A. Schuh; M. Thoennessen

2009-07-11

334

Discovery of the vanadium isotopes  

SciTech Connect

Twenty-four vanadium isotopes have been observed so far and the discovery of these isotopes is discussed here. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Shore, A.; Fritsch, A.; Heim, M.; Schuh, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Thoennessen, M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States)], E-mail: thoennessen@nscl.msu.edu

2010-07-15

335

Discovery of the Titanium Isotopes  

E-print Network

Twentyfive titanium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

D. Meierfrankenfeld; M. Thoennessen

2009-12-01

336

Discovery of the Calcium Isotopes  

E-print Network

Twenty four calcium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

J. L. Gross; M. Thoennessen

2010-09-08

337

Discovery of the Tungsten Isotopes  

E-print Network

Thirty-five tungsten isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

A. Fritsch; J. Q. Ginepro; M. Heim; A. Schuh; A. Shore; M. Thoennessen

2009-03-25

338

Discovery of the Cadmium Isotopes  

E-print Network

Thirty-seven cadmium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

Amos, S

2009-01-01

339

Discovery of the Cadmium Isotopes  

E-print Network

Thirty-seven cadmium isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

S. Amos; M. Thoennessen

2009-10-22

340

Whole exome sequence analysis of Peters anomaly.  

PubMed

Peters anomaly is a rare form of anterior segment ocular dysgenesis, which can also be associated with additional systemic defects. At this time, the majority of cases of Peters anomaly lack a genetic diagnosis. We performed whole exome sequencing of 27 patients with syndromic or isolated Peters anomaly to search for pathogenic mutations in currently known ocular genes. Among the eight previously recognized Peters anomaly genes, we identified a de novo missense mutation in PAX6, c.155G>A, p.(Cys52Tyr), in one patient. Analysis of 691 additional genes currently associated with a different ocular phenotype identified a heterozygous splicing mutation c.1025+2T>A in TFAP2A, a de novo heterozygous nonsense mutation c.715C>T, p.(Gln239*) in HCCS, a hemizygous mutation c.385G>A, p.(Glu129Lys) in NDP, a hemizygous mutation c.3446C>T, p.(Pro1149Leu) in FLNA, and compound heterozygous mutations c.1422T>A, p.(Tyr474*) and c.2544G>A, p.(Met848Ile) in SLC4A11; all mutations, except for the FLNA and SLC4A11 c.2544G>A alleles, are novel. This is the first study to use whole exome sequencing to discern the genetic etiology of a large cohort of patients with syndromic or isolated Peters anomaly. We report five new genes associated with this condition and suggest screening of TFAP2A and FLNA in patients with Peters anomaly and relevant syndromic features and HCCS, NDP and SLC4A11 in patients with isolated Peters anomaly. PMID:25182519

Weh, Eric; Reis, Linda M; Happ, Hannah C; Levin, Alex V; Wheeler, Patricia G; David, Karen L; Carney, Erin; Angle, Brad; Hauser, Natalie; Semina, Elena V

2014-12-01

341

Intracellular Cadmium Isotope Fractionation  

NASA Astrophysics Data System (ADS)

Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

2011-12-01

342

Geological reasons for change in intensity of linear magnetic anomalies of the Kursk magnetic anomaly  

NASA Technical Reports Server (NTRS)

The geological reasons for fluctuations in the anomalous field intensity along the polar axes were examined. The Kursk magnetic anomaly is used as the basis for the study. A geological-geophysical section was constructed which used the results of the interpretation of gravimagnetic anomalies.

Zhavoronkin, I. A.; Kopayev, V. V.

1985-01-01

343

Thermophysical property anomalies of Baltic seawater  

NASA Astrophysics Data System (ADS)

While the thermodynamic properties of Standard Seawater are very well known, the quantitative effect of sea salt composition anomalies on various properties is difficult to estimate since comprehensive lab experiments with the various natural waters are scarce. Coastal and estuarine waters exhibit significant anomalies which also influence to an unknown amount the routine salinity calculation from conductivity measurements. Recent numerical models of multi-component aqueous electrolytes permit the simulation of physical chemical properties of seawater with variable solute composition. In this paper, the FREZCHEM model is used to derive a Gibbs function for Baltic seawater, and the LSEA_DELS model to provide estimates for the conductivity anomaly relative to Standard Seawater. From additional information such as direct density measurements or empirical salinity anomaly parameterisation, the quantitative deviations of properties between Baltic and Standard Seawater are calculated as functions of salinity and temperature. While several quantities show anomalies that are comparable with their measurement uncertainties and do not demand special improvement, others exhibit more significant deviations from Standard Seawater properties. In particular density and sound speed turn out to be significantly sensitive to the presence of anomalous solute. Suitable general correction methods are suggested to be applied to Baltic Sea samples with known Practical Salinity and, optionally, directly determined density.

Feistel, R.; Marion, G. M.; Pawlowicz, R.; Wright, D. G.

2010-06-01

344

Thermophysical property anomalies of Baltic seawater  

NASA Astrophysics Data System (ADS)

While the thermodynamic properties of Standard Seawater are very well known, the quantitative effect of sea salt composition anomalies on various properties is difficult to estimate since comprehensive lab experiments with the various natural waters are scarce. Coastal and estuarine waters exhibit significant anomalies which also influence to an unknown amount the routine salinity calculation from conductivity measurements. Recent numerical models of multi-component aqueous electrolytes permit the simulation of physical chemical properties of seawater with variable solute composition. In this paper, the FREZCHEM model is used to derive a Gibbs function for Baltic seawater, and the LSEA_DELS model to provide estimates for the conductivity anomaly relative to Standard Seawater. From additional information such as direct density measurements or empirical salinity anomaly parameterisation, the quantitative deviations of properties between Baltic and Standard Seawater are calculated as functions of salinity and temperature. While several quantities show anomalies that are comparable with their measurement uncertainties and do not demand special improvement, others exhibit more significant deviations from Standard Seawater properties. In particular density and sound speed turn out to be significantly sensitive to the presence of anomalous solute. Suitable general correction methods are suggested to be applied to Baltic Sea samples with known Practical Salinity and, optionally, directly determined density.

Feistel, R.; Marion, G. M.; Pawlowicz, R.; Wright, D. G.

2010-11-01

345

New type of anomaly in turbulence.  

PubMed

The turbulent energy flux through scales, ??, remains constant and nonvanishing in the limit of zero viscosity, which results in the fundamental anomaly of time irreversibility. It was considered straightforward to deduce from this the Lagrangian velocity anomaly, ?du(2)/dt?=-4?? at t=0, where u[over ?] is the velocity difference of a pair of particles, initially separated by a fixed distance. Here we demonstrate that this assumed first taking the limit t?0 and then ??0, while a zero-friction anomaly requires taking viscosity to zero first. We find that the limits t?0 and ??0 do not commute if particles deplete (accumulate) in shocks backward (forward) in time on the viscous time scale. We compute analytically the resultant Lagrangian anomaly for one-dimensional Burgers turbulence and find it completely altered: ?du(2)/dt? has different values forward and backward in time. For incompressible flows, on the other hand, we show that the limits commute and the Lagrangian anomaly is still induced by the flux law, apparently due to a homogeneous distribution of fluid particles at all times. PMID:25062187

Frishman, Anna; Falkovich, Gregory

2014-07-11

346

New Type of Anomaly in Turbulence  

NASA Astrophysics Data System (ADS)

The turbulent energy flux through scales, ? ¯, remains constant and nonvanishing in the limit of zero viscosity, which results in the fundamental anomaly of time irreversibility. It was considered straightforward to deduce from this the Lagrangian velocity anomaly, ?du2/dt?=-4? ¯ at t =0, where u ? is the velocity difference of a pair of particles, initially separated by a fixed distance. Here we demonstrate that this assumed first taking the limit t?0 and then ??0, while a zero-friction anomaly requires taking viscosity to zero first. We find that the limits t?0 and ??0 do not commute if particles deplete (accumulate) in shocks backward (forward) in time on the viscous time scale. We compute analytically the resultant Lagrangian anomaly for one-dimensional Burgers turbulence and find it completely altered: ?du2/dt? has different values forward and backward in time. For incompressible flows, on the other hand, we show that the limits commute and the Lagrangian anomaly is still induced by the flux law, apparently due to a homogeneous distribution of fluid particles at all times.

Frishman, Anna; Falkovich, Gregory

2014-07-01

347

Water isotopes in precipitation  

Microsoft Academic Search

Variations of HDO and H218O concentrations are observed in precipitation both on a geographical and on a temporal basis. These variations, resulting from successive isotopic fractionation processes at each phase change of water during its atmospheric cycle, are well documented through the IAEA\\/WMO network. Isotope concentrations are, in middle and high latitudes, linearly related to the annual mean temperature at

J. Jouzel; G. Hoffmann; R. D. Koster; V. Masson

2000-01-01

348

(Carbon isotope fractionation inplants)  

SciTech Connect

The objectives of this research are: To develop a theoretical and experimental framework for understanding isotope fractionations in plants; and to develop methods for using this isotope fractionation for understanding the dynamics of CO{sub 2} fixation in plants. Progress is described.

O'Leary, M.H.

1990-01-01

349

Radioactivity of Astatine Isotopes  

Microsoft Academic Search

A number of new neutron deficient isotopes of astatine have been identified in the mass number range 200 to 209 following the irradiation of bismuth with high energy helium ions. Their alpha-decay properties fall in line with predictions for isotopes in this region with less than 126 neutrons; that is, the alpha-energies increase with decrease in mass number. Because of

G. W. Barton; A. Ghiorso; I. Perlman

1951-01-01

350

The chromium isotopic composition of Almahata Sitta  

NASA Astrophysics Data System (ADS)

Nine ureilitic fragments of the anomalous polymict ureilite Almahata Sitta have been analyzed for their Cr isotopic compositions. All the samples, including both nonmagnetic and magnetic portions, show essentially the same ?54Cr deficit (-0.77 ± 0.10), relative to the terrestrial Cr standard. This contrasts with the variable positive 54Cr anomalies observed for carbonaceous chondrites, but agrees with the values measured for eucrites, diogenites, and mesosiderites (Trinquier et al. 2007). This implies that, contrary to previous suggestions based on O isotopes, ureilites were not derived from any known carbonaceous chondrite parent body. Instead, the Almahata Sitta parent body may have accreted in a nebular region/environment similar to that of the howardite, eucrite, and diogenite (HED) parent body. In addition, the lack of variation in ?54Cr combined with variable O isotopic compositions in the meteorite fragments suggests that whatever process(es) caused the O isotopic heterogeneity of the solar system was probably not responsible for heterogeneity in ?54Cr. The samples show resolvable variations in ?53Cr (0.15-0.41) that are correlated with Mn/Cr ratios, suggesting that live 53Mn was present at the time of formation of Almahata Sitta. The isochron yields an initial 53Mn/55Mn value of 3.1 (±1.1) × 10-6, corresponding to an age of 4563.6 ± (2.2) Ma when related to U-Pb and Mn-Cr data for the D'Orbigny angrite. This age is consistent with the Mn-Cr and Al-Mg ages of two other polymict ureilites (Goodrich et al. 2010). Magmatic activity on the ureilites' parent body seems to have postdated the formation of refractory inclusions by approximately 4-5 Ma.

Qin, Liping; Rumble, Douglas; Alexander, Conel M. O'd.; Carlson, Richard W.; Jenniskens, Peter; Shaddad, Muawia H.

2010-10-01

351

Laser isotope separation  

DOEpatents

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Munich, DE); Boyer, Keith (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM)

1988-01-01

352

Photochemical isotope separation  

DOEpatents

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Robinson, C. Paul (Los Alamos, NM); Jensen, Reed J. (Los Alamos, NM); Cotter, Theodore P. (Los Alamos, NM); Greiner, Norman R. (Los Alamos, NM); Boyer, Keith (Los Alamos, NM)

1987-01-01

353

Photochemical isotope separation  

DOEpatents

A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

1987-04-28

354

Krypton 81m ventilation/perfusion ratios (V/Q) measured in lateral decubitus in pulmonary embolism (P. E. )  

SciTech Connect

In normal subjects lateral decubitis induces in both independent (lower) and nondependent lung (upper), major changes in perfusion, ventilation and V/Q ratios which can be studied with the short life radioisotope Krypton 81m. Regional V/Q are computed from ventilation and perfusion scans, successively obtained with a gamma camera linked to a computer by continuous inhalation or infusion of this gas during tidal breathing. They were displayed as a color coded functional image. To assess the effect of posture on V/Q in P.E. and other diseases which decrease the regional perfusion, 32 patients with unilateral lung diseases were studied in supine posture and both lateral decubitis: 8 with proved P.E., (3 out of them having radiological opacity matching the perfusion defect), 9 with bullous emphysema, 6 with bronchogenic carcinoma, 9 with acute bacterial pneumonia. V/Q were computed in the region of the perfusion defect. In P.E. the mean V/Q was high (1.92 +- 0.6 SD), and did not change whatever the posture. Conversely major changes of V/Q were induced with postural changes in bullous emphysema and lung carcinoma whatever the V/Q in patient supine. In pneumonia low V/Q were observed in supine posture (.73 +- .2). They decreased significantly when the pneumonia was dependent (.53 +- .2 p < 0.02) and increased in the controlateral decubitis (1.07 +- .3, p < 0.001). Since posture has no or little effect on regional V/Q in P.E., it can be used to discriminate P.E., even in the case of radiological opacity, from other unilateral disease inducing perfusion defect.

Meignan, M.; Cinotti, L.; Harf, A.; Oliveira, L.; Simonneau, G.

1984-01-01

355

Search for Al-26 effects in the Allende FUN inclusion C1. [Fractionation and Unknown Nuclear anomalies  

NASA Technical Reports Server (NTRS)

The Mg isotopic composition of major and minor mineral phases in the Allende inclusion C1 is reported. The results are analyzed in order to establish whether the Mg isotopic composition is the same in different phases and whether Al-26 is present in a sample which exhibited fractionation and unknown nuclear (FUN) effects on other elements. It is found that a small Mg-26 excess exists in C1 and is correlated with the Al-27/Mg-24 ratio, indicating that Al-26 was present in C1 together with the more general nuclear anomalies. The results also reveal that isotopic homogeneity of Mg in Mg-rich phases in C1 is evident in both bulk samples and single microscopic crystals.

Esat, T. M.; Lee, T.; Papanastassiou, D. A.; Wasserburg, G. J.

1978-01-01

356

Holographic entanglement entropy and gravitational anomalies  

NASA Astrophysics Data System (ADS)

We study entanglement entropy in two-dimensional conformal field theories with a gravitational anomaly. In theories with gravity duals, this anomaly is holographically represented by a gravitational Chern-Simons term in the bulk action. We show that the anomaly broadens the Ryu-Takayanagi minimal worldline into a ribbon, and that the anomalous contribution to the CFT entanglement entropy is given by the twist in this ribbon. The entanglement functional may also be interpreted as the worldline action for a spinning particle — that is, an anyon — in three-dimensional curved spacetime. We demonstrate that the minimization of this action results in the Mathisson-Papapetrou-Dixon equations of motion for a spinning particle in three dimensions. We work out several simple examples and demonstrate agreement with CFT calculations.

Castro, Alejandra; Detournay, Stephane; Iqbal, Nabil; Perlmutter, Eric

2014-07-01

357

Trace anomalies in chiral theories revisited  

NASA Astrophysics Data System (ADS)

Motivated by the search for possible CP violating terms in the trace of the energy-momentum tensor in theories coupled to gravity we revisit the problem of trace anomalies in chiral theories. We recalculate the latter and ascertain that in the trace of the energy-momentum tensor of theories with chiral fermions at one-loop the Pontryagin density appears with an imaginary coefficient. We argue that this may break unitarity, in which case the trace anomaly has to be used as a selective criterion for theories, analogous to the chiral anomalies in gauge theories. We analyze some remarkable consequences of this fact, that seem to have been overlooked in the literature.

Bonora, Loriano; Giaccari, Stefano; de Souza, Bruno Lima

2014-07-01

358

Interpretation of satellite elevation magnetic anomalies  

NASA Technical Reports Server (NTRS)

The present discussion is based on a study of the magnetic field data obtained with the aid of the magnetic field satellite Magsat, deployed in October 1979, over most of the earth during a 7.5-month mission. Inversions using spherical harmonic coefficients are considered along with the inversion of residual fields. In order to perform the correct operation, it is necessary to add on to the source function produced by the inversion process a magnetization function which has no external field. Such a function is known as an annihilator. The use of the annihilator for Pacific Ocean anomalies is discussed. Attention is given to models of oceanic crustal magnetization, and continental long-wavelength anomalies. It is found that in continental regions the annihilator is also useful if induced magnetizations are thought to be responsible for the long-wavelength anomaly.

Harrison, C. G. A.; Carle, H. M.; Hayling, K. L.

1986-01-01

359

Continental magnetic anomaly constraints on continental reconstruction  

NASA Technical Reports Server (NTRS)

Crustal magnetic anomalies mapped by the MAGSAT satellite for North and South America, Europe, Africa, India, Australia and Antarctica and adjacent marine areas were adjusted to a common elevation of 400 km and differentially reduced to the radial pole of intensity 60,000 nT. These radially polarized anomalies are normalized for differential inclination, declination and intensity effects of the geomagnetic field, so that in principle they directly reflected the geometric and magnetic polarization attributes of sources which include regional petrologic variations of the crust and upper mantle, and crustal thickness and thermal perturbations. Continental anomalies demonstrate remarkably detailed correlation of regional magnetic sources across rifted margins when plotted on a reconstruction of Pangea. Accordingly, they suggest further fundamental constraints on the geologic evolution of the continents and their reconstructions.

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

1985-01-01

360

Detecting data anomalies methods in distributed systems  

NASA Astrophysics Data System (ADS)

Distributed systems became most popular systems in big companies. Nowadays many telecommunications companies want to hold large volumes of data about all customers. Obviously, those data cannot be stored in single database because of many technical difficulties, such as data access efficiency, security reasons, etc. On the other hand there is no need to hold all data in one place, because companies already have dedicated systems to perform specific tasks. In the distributed systems there is a redundancy of data and each system holds only interesting data in appropriate form. Data updated in one system should be also updated in the rest of systems, which hold that data. There are technical problems to update those data in all systems in transactional way. This article is about data anomalies in distributed systems. Avail data anomalies detection methods are shown. Furthermore, a new initial concept of new data anomalies detection methods is described on the last section.

Mosiej, Lukasz

2009-06-01

361

The mineralogy of global magnetic anomalies  

NASA Technical Reports Server (NTRS)

Experimental and analytical data on magnetic mineralogy was provided as an aid to the interpretation of magnetic anomaly maps. An integrated program, ranging from the chemistry of materials from 100 or more km depth within the Earth, to an examination of the MAGSAT anomaly maps at about 400 km above the Earth's surface, was undertaken. Within this framework, a detailed picture of the pertinent mineralogical and magnetic relationships for the region of West Africa was provided. Efforts were directed toward: (1) examining the geochemistry, mineralogy, magnetic properties, and phases relations of magnetic oxides and metal alloys in rocks demonstrated to have originated in the lower crust of upper mantle, (2) examining the assumption that these rocks portray the nature of their source regions; and (3) examining the regional geology, tectonics, gravity field and the MAGSAT anomaly maps for West Africa.

Haggerty, S. E. (principal investigator)

1984-01-01

362

Identifying Anomalies in Gravitational Lens Time Delays  

NASA Astrophysics Data System (ADS)

Gravitational lensing has become a powerful probe of cold dark matter substructure. Earlier work using anomalous flux ratios in four-image quasar lenses has shown that lensing is sensitive to substructure which raises the exciting prospect of constraining the mass function and spatial distribution of dark matter satellites in galaxies. We examine the ability of gravitational lens time delays to reveal complex structure in lens potentials. We use Monte Carlo simulations to determine the range of time delays that can be produced by realistic smooth lens models consisting of isothermal ellipsoid galaxies with tidal shear. We can then identify outliers as "time-delay anomalies." We find evidence for anomalies in close image pairs in the cusp lenses RX J1131-1231 and B1422+231. The anomalies in RX J1131-1231 provide strong evidence for substructure in the lens potential, while at this point the apparent anomalies in B1422+231 mainly indicate that the time delay measurements need to be improved. We also find evidence for time-delay anomalies in larger-separation image pairs in four additional lenses. We suggest that these anomalies are caused by some combination of substructure and a complex lens environment. Our work argues for a large sample of strong lenses with precisely-measured time delays. The first of these objectives will be readily achievable as the next generation of optical and radio telescopes come online, while the second will require a dedicated one-meter class space-based observatory. Meeting these goals will make it possible to examine the properties of dark matter on sub-galactic scales, which is essential for distinguishing among the various dark matter candidates from particle physics. Part of this work was funded by NSF grant AST-0747311. ABC is currently supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Oak Ridge Associated Universities through a contract with NASA.

Congdon, Arthur B.; Keeton, C. R.; Nordgren, C. E.

2009-05-01

363

Electrochemical Isotope Effect and Lithium Isotope Separation Jay R. Black,  

E-print Network

Electrochemical Isotope Effect and Lithium Isotope Separation Jay R. Black, Grant Umeda, Bruce Dunn May 19, 2009; E-mail: akavner@ucla.edu The electrochemical separation of lithium isotopes is of growing interest due to the need for pure 6 Li and 7 Li isotopes in the nuclear industry.1 Here we present

Mcdonough, William F.

364

New type of anomaly in turbulence  

E-print Network

The turbulent energy flux through scales, $\\bar{\\epsilon}$, remains constant and non vanishing in the limit of zero viscosity, which results in the fundamental anomaly of time irreversibility. It was considered straightforward to deduce from this the Lagrangian velocity anomaly, $\\left=-4 \\bar{\\epsilon}$ at $t=0$, where $\\vec{u}$ is the velocity difference of a pair of particles, initially separated by a fixed distance. In this letter we demonstrate that this derivation assumed first taking the limit $t \\to 0$ and then $\

Anna Frishman; Gregory Falkovich

2014-01-23

365

Anomaly matching for the QCD string  

E-print Network

A criterion to be satisfied by a string theory of QCD is formulated in the ultraviolet regime. It arises from the trace anomaly of the QCD stress tensor computed using instantons. It is sensitive to asymptotic freedom. It appears to be related to the trace anomaly of the QCD string. Our current understanding of noncritical strings in physical dimensions is limited, but remarkably, a formal treatment of the bosonic string yields numerical agreement both in magnitude and sign for the gauge group SU(2).

Balakrishna, B S

1993-01-01

366

Holography and Anomaly Matching for Resonances  

E-print Network

We derive a universal relation for the transverse part of triangle anomalies within a class of theories whose gravity dual is described by the Yang-Mills-Chern-Simons theory. This relation provides a set of sum rules involving the masses, decay constants and couplings between resonances, and leads to the formulas for the matrix elements of the vector and axial currents in the presence of the soft electromagnetic field. We also discuss that this relation is valid in real QCD at least approximately. This may be regarded as the anomaly matching for resonances as an analogue of that for the massless excitations in QCD.

Dam T. Son; Naoki Yamamoto

2010-10-04

367

The holomorphic anomaly for open string moduli  

NASA Astrophysics Data System (ADS)

We complete the holomorphic anomaly equations for topological strings with their dependence on open moduli. We obtain the complete system by standard path integral arguments generalizing the analysis of BCOV (Commun. Math. Phys. 165 (1994) 311) to strings with boundaries. We study both the anti-holomorphic dependence on open moduli and on closed moduli in presence of Wilson lines. By providing the compactification à la Deligne-Mumford of the moduli space of Riemann surfaces with boundaries, we show that the open holomorphic anomaly equations are structured on the (real codimension one) boundary components of this space.

Bonelli, Giulio; Tanzini, Alessandro

2007-10-01

368

Radioactive anomaly discrimination from spectral ratios  

DOEpatents

A method for discriminating a radioactive anomaly from naturally occurring radioactive materials includes detecting a first number of gamma photons having energies in a first range of energy values within a predetermined period of time and detecting a second number of gamma photons having energies in a second range of energy values within the predetermined period of time. The method further includes determining, in a controller, a ratio of the first number of gamma photons having energies in the first range and the second number of gamma photons having energies in the second range, and determining that a radioactive anomaly is present when the ratio exceeds a threshold value.

Maniscalco, James; Sjoden, Glenn; Chapman, Mac Clements

2013-08-20

369

Modeling And Detecting Anomalies In Scada Systems  

NASA Astrophysics Data System (ADS)

The detection of attacks and intrusions based on anomalies is hampered by the limits of specificity underlying the detection techniques. However, in the case of many critical infrastructure systems, domain-specific knowledge and models can impose constraints that potentially reduce error rates. At the same time, attackers can use their knowledge of system behavior to mask their manipulations, causing adverse effects to observed only after a significant period of time. This paper describes elementary statistical techniques that can be applied to detect anomalies in critical infrastructure networks. A SCADA system employed in liquefied natural gas (LNG) production is used as a case study.

Svendsen, Nils; Wolthusen, Stephen

370

A new feature in the internal heavy isotope distribution in ozone  

NASA Astrophysics Data System (ADS)

Ozone produced by discharge or photolysis of oxygen has unusually heavy isotopic composition (18O/16O and 17O/16O ratio) which does not follow normal mass fractionation rule: ?17O ˜ 0.52*?18O, expressed as an anomaly ?17O = ?17O - 0.52*?18O. Ozone molecule being an open isosceles triangle can have the heavy isotope located either in its apex or symmetric (s) position or the base or asymmetric (as) position. Correspondingly, one can define positional isotopic enrichment, written as ?18O (s) or ?18O (as) (and similarly for ?17O) as well as position dependent isotope anomaly ?17O (s) and ?17O (as). Marcus and co-workers have proposed a semi-empirical model based in principle on the RRKM model of uni-molecular dissociation but with slight modification (departure from statistical randomness assumption for symmetrical molecules) which explains many features of ozone isotopic enrichment. This model predicts that the bulk isotope anomaly is contained wholly in the asymmetric position and the ?17O (s) is zero. Consequently, ?17O (as) = 1.5 * ?17O (bulk) (named here simply as the "1.5 rule") which has been experimentally confirmed over a range of isotopic enrichment. We now show that a critical re-analysis of the earlier experimental data demonstrates a small but significant departure from this 1.5 rule at the highest and lowest levels of enrichments. This departure provides the first experimental proof that the dynamics of ozone formation differs from a statistical model constrained only by restriction of symmetry. We speculate over some possible causes for the departure.

Bhattacharya, S. K.; Savarino, Joel; Michalski, G.; Liang, Mao-Chang

2014-10-01

371

The relationship between clear sky water vapor and SST anomalies  

NASA Technical Reports Server (NTRS)

The relationship between clear sky water vapor anomalies and the SST anomalies (SSTAs) was investigated with the purpose of providing data for evaluating the clear sky greenhouse effect predicted in many global warming scenarios, by statistically analyzing anomaly data sets of SST and the water vapor anomaly data (obtained by subtracting the mean value of the six years of data for a given month from the observed values). Results show that clear sky water vapor anomalies increase in association with increases in SSTAs. The clear sky water vapor anomalies high in the troposphere were also found to increase with increasing SSTA.

Peterson, Thomas C.; Vonder Haar, Thomas H.

1992-01-01

372

Isotopically controlled semiconductors  

SciTech Connect

The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

Haller, Eugene E.

2006-06-19

373

International Isotope Society  

NSDL National Science Digital Library

The international isotope society (IIS) "aims to encourage the synthesis and applications of isotopes and isotopically labeled compounds to benefit of all." Visitors can find information about upcoming international conferences as well as summaries of past symposiums. The website provides copies of the presentation speeches discussing the activities of award winning scientists. Researchers can find out about the society's low level radioactive waste committee's activities to create a positive public image of the use of radioisotopes in research. An online technical report educates students and teachers about photomultipliers and their applications.

374

Kohn anomaly in phonon driven superconductors  

NASA Astrophysics Data System (ADS)

Anomalies often occur in the physical world. Sometimes quite unexpectedly anomalies may give rise to new insight to an unrecognized phenomenon. In this paper we shall discuss about Kohn anomaly in a conventional phonon-driven superconductor by using a microscopic approach. Recently Aynajian et al.'s experiment showed a striking feature; the energy of phonon at a particular wave-vector is almost exactly equal to twice the energy of the superconducting gap. Although the phonon mechanism of superconductivity is well known for many conventional superconductors, as has been noted by Scalapino, the new experimental results reveal a genuine puzzle. In our recent work we have presented a detailed theoretical analysis with the help of microscopic calculations to unravel this mystery. We probe this aspect of phonon behaviour from the properties of electronic polarizability function in the superconducting phase of a Fermi liquid metal, leading to the appearance of a Kohn singularity. We show the crossover to the standard Kohn anomaly of the normal phase for temperatures above the transition temperature. Our analysis provides a nearly complete explanation of this new experimentally discovered phenomenon. This report is a shorter version of our recent work in JPCM.

Das, M. P.; Chaudhury, R.

2014-08-01

375

Ebstein's anomaly: repair based on functional analysis  

Microsoft Academic Search

Objective: ‘Classical’ repair of Ebstein's anomaly is usually performed with transverse plication of the atrialized chamber. However, the anterior leaflet has restricted motion which is an important factor of the tricuspid valve insufficiency. We studied the long term results of mobilization of the anterior leaflet associated with longitudinal plication of the right ventricule. Methods: From 1980 to July 2002, 191

S Chauvaud; A Berrebi; N d'Attellis; E Mousseaux; A Hernigou; A Carpentier

2003-01-01

376

Anomalies, U(1)' and the MSSM  

Microsoft Academic Search

This Thesis reviews an extension of the MSSM by the addition of an anomalous abelian vector multiplet and contains some original results concerning the phenomenology of an anomalous $Z'$. The review part covers an introduction of the MSSM focusing on its main features, a discussion on the chiral anomalies and how to cancel them in the Standard Model and by

Antonio Racioppi

2009-01-01

377

Dorsal Forebrain Anomaly in Williams Syndrome  

E-print Network

in range to that seen in Down syndrome, show an unusual and uneven neuropsychological profileDorsal Forebrain Anomaly in Williams Syndrome Albert M. Galaburda, MD; J. Eric Schmitt, BS; Scott W. Atlas, MD; Stephan Eliez, MD; Ursula Bellugi, EdD; Allan L. Reiss, MD Background: Williams syndrome (WMS

378

Timing Anomalies in Dynamically Scheduled Microprocessors  

Microsoft Academic Search

Previous timing analysis methods have assumed that the worst-case instruction execution time necessarily cor- responds to the worst-case behavior. We show that this assumption is wrong in dynamically scheduled processors. A cache miss, for example, can in some cases result in a shorter execution time than a cache hit. Many examples of such timing anomalies are provided. We first provide

Thomas Lundqvist; Per Stenström

1999-01-01

379

Locally covariant chiral fermions and anomalies  

NASA Astrophysics Data System (ADS)

We define chiral fermions in the presence of non-trivial gravitational and gauge background fields in the framework of locally covariant field theory. This allows to straightforwardly compute the chiral anomalies on non-compact Lorentzian spacetimes, without recourse to a weak field approximation.

Zahn, Jochen

2015-01-01

380

IPrognosis of Aircraft Anomalies 2010 Phase II  

E-print Network

Technical Abstract A Probabilistic Fatigue Damage Assessment Network (PFDAN) toolkit for Abaqus. It is based on a high fidelity Fatigue Damage Assessment Network (FDAN) which includes 1) a coupled continuumSBIR 30 31 IPrognosis of Aircraft Anomalies 2010 Phase II Proposal A1.12-8884 Probabilistic

381

Gravity anomaly detection: Apollo/Soyuz  

NASA Technical Reports Server (NTRS)

The Goddard Apollo-Soyuz Geodynamics Experiment is described. It was performed to demonstrate the feasibility of tracking and recovering high frequency components of the earth's gravity field by utilizing a synchronous orbiting tracking station such as ATS-6. Gravity anomalies of 5 MGLS or larger having wavelengths of 300 to 1000 kilometers on the earth's surface are important for geologic studies of the upper layers of the earth's crust. Short wavelength Earth's gravity anomalies were detected from space. Two prime areas of data collection were selected for the experiment: (1) the center of the African continent and (2) the Indian Ocean Depression centered at 5% north latitude and 75% east longitude. Preliminary results show that the detectability objective of the experiment was met in both areas as well as at several additional anomalous areas around the globe. Gravity anomalies of the Karakoram and Himalayan mountain ranges, ocean trenches, as well as the Diamantina Depth, can be seen. Maps outlining the anomalies discovered are shown.

Vonbun, F. O.; Kahn, W. D.; Bryan, J. W.; Schmid, P. E.; Wells, W. T.; Conrad, D. T.

1976-01-01

382

Konishi anomalies and curves without adjoints  

Microsoft Academic Search

Generalized Konishi anomaly relations in the chiral ring of N=1 supersymmetric gauge theories with unitary gauge group and chiral matter field in two-index tensor representations are derived. Contrary to previous investigations of related models we do not include matter multiplets in the adjoint representation. The corresponding curves turn out to be hyperelliptic. We also point out equivalences to models with

Karl Landsteiner

2004-01-01

383

The mineralogy of global magnetic anomalies  

NASA Technical Reports Server (NTRS)

The Curie Balance was brought to operational stage and is producing data of a preliminary nature. Substantial problems experienced in the assembly and initial operation of the instrument were, for the most part, rectified, but certain problems still exist. Relationships between the geology and the gravity and MAGSAT anomalies of West Africa are reexamined in the context of a partial reconstruction of Gondwanaland.

Haggerty, S. E. (principal investigator)

1982-01-01

384

Racialised relations in Liverpool: A contemporary anomaly  

Microsoft Academic Search

The city of Liverpool stands out as an anomaly in the mapping of ‘racialised relations’ and the black experience in England. While it shares a number of continuities with other cities, it reveals several structural and cultural features which are absent or significantly at variance with patterns elsewhere. These include extreme residential segregation, a powerful white local sentiment and insular

Stephen Small

1991-01-01

385

Gravitational Anomalies in the Solar System?  

E-print Network

Mindful of the anomalous perihelion precession of Mercury discovered by U. Le Verrier in the second half of the nineteenth century and its successful explanation by A. Einstein with his General Theory of Relativity in the early years of the twentieth century, discrepancies among observed effects in our Solar system and their theoretical predictions on the basis of the currently accepted laws of gravitation applied to known bodies have the potential of paving the way for remarkable advances in fundamental physics. This is particularly important now more than ever, given that most of the Universe seems to be made of unknown substances dubbed Dark Matter and Dark Energy. Should this not be directly the case, Solar system's anomalies could anyhow lead to advancements in cumulative science, as shown to us by the discovery of Neptune in the first half of the nineteenth century. Moreover, investigations in one of such directions can serendipitously enrich the other one as well. The current status of some alleged gravitational anomalies in the Solar system is critically reviewed. They are: a) Possible anomalous advances of planetary perihelia; b) Unexplained orbital residuals of a recently discovered moon of Uranus (Mab); c) The lingering unexplained secular increase of the eccentricity of the orbit of the Moon; d) The so-called Faint Young Sun Paradox; e) The secular decrease of the mass parameter of the Sun; f) The Flyby Anomaly; g) The Pioneer Anomaly; and h) The anomalous secular increase of the astronomical unit

Lorenzo Iorio

2015-01-21

386

Satellite Anomalies from Galactic Cosmic Rays  

Microsoft Academic Search

Anomalies in communication satellite operation have been caused by the unexpected triggering of digital circuits. Interactions with galactic cosmic rays were investigated as a mechanism for a number of these events. The mechanism assumed was the charging of the base-emitter capacitance of sensitive transistors to the turn-on voltage. The calculation of the cosmic ray event rate required the determination of

D. Binder; E. C. Smith; A. B. Holman

1975-01-01

387

Gravitational Anomalies in the Solar System?  

E-print Network

Mindful of the anomalous perihelion precession of Mercury discovered by U. Le Verrier in the second half of the nineteenth century and its successful explanation by A. Einstein with his General Theory of Relativity in the early years of the twentieth century, discrepancies among observed effects in our Solar system and their theoretical predictions on the basis of the currently accepted laws of gravitation applied to known bodies have the potential of paving the way for remarkable advances in fundamental physics. This is particularly important now more than ever, given that most of the Universe seems to be made of unknown substances dubbed Dark Matter and Dark Energy. Should this not be directly the case, Solar system's anomalies could anyhow lead to advancements in cumulative science, as shown to us by the discovery of Neptune in the first half of the nineteenth century. Moreover, investigations in one of such directions can serendipitously enrich the other one as well. The current status of some alleged gravitational anomalies in the Solar system is critically reviewed. They are: a) Possible anomalous advances of planetary perihelia; b) Unexplained orbital residuals of a recently discovered moon of Uranus (Mab); c) The lingering unexplained secular increase of the eccentricity of the orbit of the Moon; d) The so-called Faint Young Sun Paradox; e) The secular decrease of the mass parameter of the Sun; f) The Flyby Anomaly; g) The Pioneer Anomaly; and h) The anomalous secular increase of the astronomical unit

Lorenzo Iorio

2014-12-21

388

Hyperspectral imagery: Clutter adaptation in anomaly detection  

Microsoft Academic Search

Hyperspectral sensors are passive sensors that simultaneously record images for hundreds of contiguous and narrowly spaced regions of the electromagnetic spectrum. Each image corresponds to the same ground scene, thus creating a cube of images that contain both spatial and spectral information about the objects and backgrounds in the scene. In this paper, we present an adaptive anomaly detector designed

Susan M. Schweizer; José M. F. Moura

2000-01-01

389

Ocean response to surface heat anomalies  

SciTech Connect

An ocean general circulation model (OGCM) is used to study the response of ocean heat and mass transport to positive and negative heat flux anomalies at the ocean surface. As expected, tropical and low-latitude mixed layers respond rapidly (e-folding time about 50-70 years) to external forcing, while the response of the high-latitude mixed layer, especially the Southern Ocean and northern North Atlantic, is very slow (e-folding time greater than 300 yr). The overall response is faster for negative than positive heat flux anomaly at the surface. The meridional heat transport changes by 15% in the first 50 yr in the southern high latitudes. Surprisingly, for the next 400-500 yr the change is very small. The analysis shows that the meridional mass transport intensifies in response to a negative surface heat flux anomaly but weakens in response to a positive heat flux anomaly. For example, at model year 100 the North Atlantic Deep Water (NADW) is reduced from about 18 Sv to about 10 Sv for the positive heat flux experiment but increased to about 26 Sv for the negative heat flux experiment.

Jiang, Xingjian; Fung, Inez (NASA. Goddard Inst. for Space Studies, New York, NY (United States))

1994-05-01

390

Ocean response to surface heat anomalies  

NASA Technical Reports Server (NTRS)

An ocean general circulation model (OGCM) is used to study the response of ocean heat and mass transport to positive and negative heat flux anomalies at the ocean surface. As expected, tropical and low-latitude mixed layers respond rapidly (e-folding time about 50-70 years) to external forcing, while the response of the high-latitude mixed layer, especially the Southern Ocean and northern North Atlantic, is very slow (e-folding time greater than 300 yr). The overall response is faster for negative than positive heat flux anomaly at the surface. The meridional heat transport changes by 15% in the first 50 yr in the southern high latitudes. Surprisingly, for the next 400-500 yr the change is very small. The analysis shows that the meridional mass transport intensifies in response to a negative surface heat flux anomaly but weakens in response to a positive heat flux anomaly. For example, at model year 100 the North Atlantic Deep Water (NADW) is reduced from about 18 Sv to about 10 Sv for the positive heat flux experiment but increased to about 26 Sv for the negative heat flux experiment.

Jiang, Xingjian; Fung, Inez

1994-01-01

391

The anomaly data base of screwworm information  

NASA Technical Reports Server (NTRS)

Standard statistical processing of anomaly data in the screwworm eradication data system is possible from data compiled on magnetic tapes with the Univac 1108 computer. The format and organization of the data in the data base, which is also available on dedicated disc storage, are described.

Giddings, L. E.

1976-01-01

392

Psychoeducational Implications of Sex Chromosome Anomalies  

ERIC Educational Resources Information Center

Numerous anomalies involving the sex chromosomes (X or Y) have been documented and their impact on development, learning, and behavior studied. This article reviews three of these disorders, Turner syndrome, Klinefelter syndrome, and Lesch-Nyhan disease. Each of these three is associated with one or more selective impairments or behavioral…

Wodrich, David L.; Tarbox, Jennifer

2008-01-01

393

Interacting topological phases and quantum anomalies  

NASA Astrophysics Data System (ADS)

Since the quantum Hall effect, the notion of topological phases of matter has been extended to those that are well-defined (or: ``protected'') in the presence of a certain set of symmetries, and that exist in dimensions higher than two. In the (fractional) quantum Hall effects (and in ``chiral'' topological phases in general), Laughlin's thought experiment provides a key insight into their topological characterization; it shows a close connection between topological phases and quantum anomalies. Compared to genuine topological phases, symmetry protected topological phases are more fragile and less entangled states of matter, and hence for their characterization we need to sharpen our understanding on how topological properties of the systems manifest themselves in the form of a quantum anomaly. By taking various kinds of symmetry protected topological phases as an example, I will demonstrate that quantum anomalies serve as a useful tool to diagnose (and even define) topological properties of the systems. I will also discuss quantum anomalies play an essential role when developing descriptions of these topological phases in terms bulk and boundary (effective) theories.

Ryu, Shinsei

2013-03-01

394

Pre-seismic geomagnetic anomaly and earthquake location  

NASA Astrophysics Data System (ADS)

Many researchers studied the relationships between appearances of geomagnetic anomalies and their distances to earthquake epicenters or faults. Yet, occasionally some magnetometer stations located nearby earthquake epicenters and/or faults do not observe geomagnetic anomalies. In this paper, a new hybrid system which simultaneously takes the hypocenter and fault plane solution into account is constructed to examine 38 earthquakes interpreted to be associated with geomagnetic anomalies during the period 1988-2001 in Taiwan. The Surface Magnetic Anomaly Reference Tip (SMART) of the new system is used instead of the epicenter or the fault to investigate statistically the distance relationship between the anomalies and the earthquake parameters. Results show that the anomalies gather along the fault and in the belt zone to the SMART. Possible mechanisms causing the anomalies in the two zones are proposed and discussed. Characteristics of the anomaly might shed some light on locations of faults before earthquake occurrences.

Chen, Chieh-Hung; Liu, Jann-Yenq; Lin, Pei-Ying; Yen, Horng-Yuan; Hattori, Katsumi; Liang, Wen-Tzong; Chen, Yuh-Ing; Yeh, Yih-Hsiung; Zeng, Xiaoping

2010-06-01

395

Neutral pion lifetime measurements and the QCD chiral anomaly  

E-print Network

A fundamental property of QCD is the presence of the chiral anomaly, which is the dominant component of the ?[superscript 0]??? decay rate. Based on this anomaly and its small (?4.5%) chiral correction, a prediction of the ...

Bernstein, Aron M.

396

Does Market Learning Explain the Disappearance of the Accrual Anomaly?  

E-print Network

This study investigates whether market learning explains the absence of the accrual anomaly in recent years by examining three conditions associated with the presence of the anomaly in prior research: (i) a differential relation between future...

Keskek, Sami

2012-10-19

397

Perchlorate isotope forensics  

USGS Publications Warehouse

Perchlorate has been detected recently in a variety of soils, waters, plants, and food products at levels that may be detrimental to human health. These discoveries have generated considerable interest in perchlorate source identification. In this study, comprehensive stable isotope analyses ( 37Cl/35Cl and 18O/17O/ 16O) of perchlorate from known synthetic and natural sources reveal systematic differences in isotopic characteristics that are related to the formation mechanisms. In addition, isotopic analyses of perchlorate extracted from groundwater and surface water demonstrate the feasibility of identifying perchlorate sources in contaminated environments on the basis of this technique. Both natural and synthetic sources of perchlorate have been identified in water samples from some perchlorate occurrences in the United States by the isotopic method. ?? 2005 American Chemical Society.

Böhlke, J.K.; Sturchio, N.C.; Gu, B.; Horita, J.; Brown, G.M.; Jackson, W.A.; Batista, J.; Hatzinger, P.B.

2005-01-01

398

Isotopically controlled semiconductors  

SciTech Connect

A review of recent research involving isotopically controlled semiconductors is presented. Studies with isotopically enriched semiconductor structures experienced a dramatic expansion at the end of the Cold War when significant quantities of enriched isotopes of elements forming semiconductors became available for worldwide collaborations. Isotopes of an element differ in nuclear mass, may have different nuclear spins and undergo different nuclear reactions. Among the latter, the capture of thermal neutrons which can lead to neutron transmutation doping, can be considered the most important one for semiconductors. Experimental and theoretical research exploiting the differences in all the properties has been conducted and will be illustrated with selected examples. Manuel Cardona, the longtime editor-in-chief of Solid State Communications has been and continues to be one of the major contributors to this field of solid state physics and it is a great pleasure to dedicate this review to him.

Haller, E.E.

2004-11-15

399

Anomaly Transform method for initializing climate forecas.  

NASA Astrophysics Data System (ADS)

A new approach, an Anomaly Transform method (AT) using a physics based metric, is developed to initialize decadal climate hindcast within the German climate prediction MiKlip project. The method starts from balanced anomaly structures in space and time and between variables derived from control runs and applies an orthogalization to these. Two physics based metric are used to set up the eigen problem (1) the weighted total energy with its zonal, meridional kinetic and available potential energy terms having equal contributions, and (2) the weighted ocean heat content in which a disturbance is applied only to the initial temperature fields. The choice of a reference state defining the anomalies and the selected sequence of anomalies, once on a seasonal timescales and second on an interannual timescales, project a-priori only the slow modes of the ocean physical processes, such that the disturbances grow mainly in the Western Boundary Currents, in the ACC and ENSO regions. An additional set of initial conditions was designed to fit in a least square sense anomalies from the GECCO-2 ocean reanalysis. These sets of AT initial conditions and the MPIOM-ESM coupled model in T63L47/GR15 resolution were used for ensemble experiments and a retrospective forecast. The weighted total energy norm is used to monitor the amplitudes and rates of the fastest growing error modes. The results showed minor dependence of the instability growth on the selected metric but considerable change due to the rescaling coefficients magnitude on the perturbation amplitude. In contrary to similar atmospheric applications, we find an energy conversion from kinetic to available potential energy, which suggests different source of uncertainties mainly associated with changes in density fields.

Romanova, Vanya; Hense, Andreas

2014-05-01

400

Isotope Innovations (Invited)  

NASA Astrophysics Data System (ADS)

During a decade of discovery, the geochemical toolkit available for paleoredox reconstruction expanded dramatically. Notably, high-precision isotope analyses using multiple collector inductively coupled mass spectrometry (MC-ICP-MS) revealed that natural variations in isotope abundances due to isotope fractionation are ubiquitous across the Periodic Table. These variations quickly drew interest as paleoredox proxies because many of these isotope fractionations are driven by redox transformations. However, this potential has not been fully exploited because of the complexities of ancient systems and the need for extensive work in experiments and modern analog environments to calibrate these proxies. To generate the large datasets needed to move beyond "proof of potential" research, technological innovations are required. Two areas should be targeted for near-term progress, in both cases borrowing inspiration from the evolution of methods used to study light stable isotope systems. First, sample preparation is often an analytical bottleneck, especially for non-specialists, and the need for complex, specialized laboratory facilities when preparing samples manually limits the adoption of isotope techniques. This challenge can be addressed by developing and adapting automated ion exchange systems that allow inline or offline sample preparation. Systems that could be a basis for this effort are now becoming commercially available. Second, high precision isotope analysis using mass spectrometry presently requires expert technical support due to the complexities and costs of the instrumentation. Novel mass spectrometer designs are one approach to this challenge. Another is the use of high-resolution laser spectroscopy rather than mass spectrometry for isotope analysis. Concepts and preliminary efforts in these areas will be discussed.

Anbar, A. D.

2013-12-01

401

Woven Coronary Artery Anomaly Associated with Acute Coronary Syndrome  

PubMed Central

The woven coronary artery anomaly is a rare congenital anomaly in which a coronary artery is divided into thin channels that merge again into the distal lumen. Only a few cases of woven coronary artery have been reported in the literature. This anomaly is accepted as a benign condition. We describe a case of acute coronary syndrome in a patient with woven coronary artery anomaly. PMID:24436585

Ayhan, Selim; Ozturk, Serkan; Tekelioglu, Umit Yasar; Ocak, Tarik

2013-01-01

402

182Hf, a new isotope for AMS  

NASA Astrophysics Data System (ADS)

The neutron-rich isotope 182Hf with its half-life of 9+/-2 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 recent stellar events with high neutron fluxes in the vicinity of the Earth. This may be accomplished by finding measurable traces of live 182Hf in suitable terrestrial archives. With accelerator mass spectrometry (AMS) it should be possible to detect minute amounts of 182Hf. We will show that the main interference for the detection, the stable isobar 182W, can be significantly reduced by using HfF5- ions. The AMS detection method of 182Hf and first results from Hf control rods of a recently retired research reactor are presented, which encourage us to search for naturally produced traces of 182Hf on Earth.

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

2004-08-01

403

Atomic data for neutron-capture elements. II. Photoionization and recombination properties of low-charge krypton ions  

NASA Astrophysics Data System (ADS)

We present multi-configuration Breit-Pauli distorted-wave photoionization (PI) cross sections and radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six krypton ions. These were calculated with the AUTOSTRUCTURE code, using semi-relativistic radial wavefunctions in intermediate coupling. Kr has been detected in several planetary nebulae (PNe) and H II regions, and is a useful tracer of neutron-capture nucleosynthesis. PI, RR, and DR data are required to accurately correct for unobserved Kr ions in photoionized nebulae, and hence to determine elemental Kr abundances. PI cross sections have been determined for ground configuration states of Kr0-Kr5+ up to 100 Rydbergs. Our Kr+ PI calculations were significantly improved through comparison with experimental measurements. RR and DR rate coefficients were respectively determined from the direct and resonant PI cross sections at temperatures (101-107)z2 K, where z is the charge. We account for ?n = 0 DR core excitations, and find that DR is the dominant recombination mechanism for all but Kr+ at photoionized plasma temperatures. Internal uncertainties are estimated by comparing results computed with three different configuration-interaction expansions for each ion, and by testing the sensitivity to variations in the orbital radial scaling parameters. The PI cross sections are generally uncertain by 30-50% near the ground state thresholds. Near 104 K, the RR rate coefficients are typically uncertain by less than 10%, while those of DR exhibit uncertainties of factors of 2 to 3, due to the unknown energies of near-threshold autoionizing resonances. With the charge transfer rate coefficients presented in the third paper of this series, these data enable robust Kr abundance determinations in photoionized nebulae for the first time, providing a new tool for studying heavy element enrichments in PNe and for investigating the chemical evolution of trans-iron elements. The calculation results are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/533/A62

Sterling, N. C.

2011-09-01

404

New insights into global patterns of ocean temperature anomalies  

E-print Network

the spatial and temporal characteristics of temperature anomalies related to both coral bleaching and disease spatial patterns in coral bleaching- and disease-related anomalies as well as for designing protected results suggest that temperature anomalies related to coral bleaching and disease are likely to be highly

Bruno, John F.

405

Parametric Methods for Anomaly Detection in Aggregate Traffic  

E-print Network

estimate model parameters in real- time, thus obviating the need for a long training phase or manual detection time and the strength of an anomaly. Additionally, it uses both traffic-rate and packet of packet sizes from the nominal condition is flagged as an anomaly. Our anomaly detection problem is posed

Heidemann, John

406

Five-Year Average Global Temperature Anomalies 1880 - 2010  

NSDL National Science Digital Library

This color-coded map displays a progression of changing five-year average global surface temperatures anomalies from 1880 through 2010. The final frame represents global temperature anomalies averaged from 2006 to 2010. The temperature anomalies are computed relative to the base period 1951-1980.

Schmunk, Robert B.; Hansen, J.; Ruedy, R.; Sato, Mki; Lo, K.; Studio, Nasa/goddard S.

407

Harmonic superspace formalism and the consistent chiral anomaly  

SciTech Connect

The harmonic superspace formalism has been used to construct the consistent chiral anomaly in N = 1, d = 6 supersymmetric Yang-Mills thoery. The expressions of the gauge anomaly ..delta../sub s//sup phi/ and of the supersymmetric anomaly ..delta../sub SUSY//sup phi/ are given together with the consistent condition. 7 refs.

Li, W.

1986-08-01

408

El Nino: Sea Surface Temperature Anomaly and Sea Surface Height Anomaly from Sept. 1996 to Sept. 1997  

NSDL National Science Digital Library

Sea surface height anomaly is presented as topography and sea surface temperature anomaly as color. A similar visualization (animation 1415) presents this same data and includes a pan from the front view to a side view.

Shirah, Greg; Busalacchi, Antonio

1997-09-08

409

The Southeast Indian Ridge: Scale of Source Heterogeneity and Origin of the DUPAL Anomaly  

NASA Astrophysics Data System (ADS)

Results Pb and Hf isotope ratios from 124 basalt glasses sampled at < 10 km intervals along 2000 km of the Southeast Indian Ridge (SEIR) between 86°E and 110°E show bimodal distributions. The bimodality in both Pb and Hf isotope ratios confirms the presence of ancient compositional streaks in the Indian Ocean upper mantle [1]. The density of streaks is well described by a Poisson distribution having a characteristic thickness of ~25 km. Implications Pb isotopes in SEIR basalts all carry a DUPAL [3] isotope signature. Two possible origins for the bimodality and DUPAL signature are: (1) ancient melting that involved garnet fractionation, with subsequent pollution of the upper mantle by continental material during Gondwana breakup; (2) inherited heterogeneity from the early Earth. The later explanation is difficult to reconcile as it requires an input of a non-chondritic Pb composition. Pollution of the asthenosphere by material resulting from interaction of deep mantle hotspot/plumes (e.g. Karoo, Reunion) with the shallow continental lithosphere during the breakup of the Gondwana supercontinent and formation of the Indian Ocean basin adequately accounts for the DUPAL anomaly. [1] Graham et al. (2006) Nature 440, 199-202. [2] Mahoney et al. (2002) J. Petrology 43, 1155-1176. [3] Hart (1984) Nature 309, 753-757.; Histogram for Hf isotopes and bimodal distribution in the ?Hf versus 208*Pb/206*Pb binary projection for 197 SEIR glasses [this work; 1, 2]. The 2 populations overlap. Although the ?Hf means differ by only 1.5 ? units, a t-test shows that the probability the means are equal is infinitesimal (t=18). The statistics derived from this analysis are fully consistent with the discriminant value ?Hf = 11.8 [1].

Hanan, B. B.; Blichert-Toft, J.; Sayit, K.; Agranier, A.; Hemond, C.; Briais, A.; Maia, M. A.; Graham, D. W.; Albarede, F.

2012-12-01

410

Elemental abundance anomalies in the late Cenomanian extinction interval: a search for the source(s)  

USGS Publications Warehouse

Elemental abundances have been measured by neutron activation methods across the Cenomanian-Turonian (late Cretaceous) extinction interval in samples collected from sixteen sites in the Western Interior Basin of North America and from twelve widely separated locations around the globe, including six ODP/DSDP sites. In most Western Interior Basin sites, in Colombia, and in western Europe (weaker), two closely spaced elemental abundance peaks occur in the upper Cenomanian (??? 92 m.y.), spanning the ammonite zones of Sciponoceras gracile through Neocardioceras juddii. Elements with anomalously high concentrations include Sc, Ti, V, Cr, Mn, Co, Ni, Ir, Pt and Au. The lower peak coincides with the disappearance (extinction) of the foraminifer Rotalipora cushmani. In North American sections R. greenhornensis also disappears at or just below this horizon, but in Europe it disappears considerably earlier than R. cushmani. A series of molluscan extinction and speciation or migration events also begins near the stratigraphic level of the lower elemental abundance peak. The well-documented positive ?? 13C excursion begins just before the extinctions and the elemental anomalies, and continues into the lower Turonian, well above the upper anomaly. This carbon isotope excursion has been observed in East European sections where we find little or no evidence of the elemental anomalies, suggesting that the two phenomena may not be tightly coupled. Elemental abundance ratios in the anomalies closely resemble those of Mid-Atlantic Ridge basalt or Hawaiian lava (tholeiitic), but not those of C1 chondrite, black shale, average crustal rocks, or lamproite and kimberlite of roughly similar age in southeastern Kansas. The excess Ir and other siderophiles hint at possible large-body impact(s) for the source. However, we have not located microspherules (other than biogenic calcispheres) or shocked mineral grains in any of our samples. Furthermore, Sc, Ti, V and Mn are not enriched in differentiated Solar-System bodies. Although the weak geochemical signal from comet impact(s) could be masked by the strong terrestrial-like overprint, these anomalies more likely resulted either from intense seafloor spreading activity or merely from increased circulation of deep, metal-rich water associated with the large late Cenomanian through early Turonian eustatic rise and deep-water opening of the South Atlantic. The flooding of continental seaways and margins also could have contributed to the anomalies by preventing much continental detritus from diluting the normal background marine geochemical component. ?? 1993.

Orth, C.J.; Attrep, M., Jr.; Quintana, L.R.; Elder, W.P.; Kauffman, E.G.; Diner, R.; Villamil, T.

1993-01-01

411

Symmetry breaking through Bell-Jackiw anomalies  

Microsoft Academic Search

In models of fermions coupled to gauge fields certain current-conservation laws are violated by Bell-Jackiw anomalies. In perturbation theory the total charge corresponding to such currents seems to be still conserved, but here it is shown that nonperturbative effects can give rise to interactions that violate the charge conservation. One consequence is baryon and lepton number nonconservation in V-A gauge

1976-01-01

412

Risk of Vascular Anomalies With Down Syndrome  

Microsoft Academic Search

ABSTRACT OBJECTIVE. Patients with,Down,syndrome,have,a reduced,risk of developing,solid tumors. This protective effect has been attributed to increased gene dosage from an additional copy of chromosome 21, and elevated expression of endostatin has been implicated. We hypothesized that vascular anomalies, including infantile hemangi- oma, an angiogenesis-dependent vascular tumor, and vascular malformations might be similarly inhibited in patients with Down,syndrome. PATIENTS AND METHODS.

John B. Mulliken; Arin K. Greene; Sendia Kim; Gary F. Rogers; Steven J. Fishman; Bjorn R. Olsen

2010-01-01

413

Konishi Anomalies and Curves without Adjoints  

E-print Network

Generalized Konishi anomaly relations in the chiral ring of N=1 supersymmetric gauge theories with unitary gauge group and chiral matter field in two-index tensor representations are derived. Contrary to previous investigations of related models we do not include matter multiplets in the adjoint representation. The corresponding curves turn out to be hyperelliptic. We also point out equivalences to models with orthogonal or symplectic gauge groups.

Landsteiner, K

2004-01-01

414

Holographic gravitational anomaly and chiral vortical effect  

Microsoft Academic Search

We analyze a holographic model with a pure gauge and a mixed gauge-gravitational Chern-Simons term in the action. These are the holographic implementations of the usual chiral and the mixed gauge-gravitational anomalies in four dimensional field theories with chiral fermions. We discuss the holographic renormalization and show that the gauge-gravitational Chern-Simons term does not induce new divergences. In order to

Karl Landsteiner; Eugenio Megías; Luis Melgar; Francisco Pena-Benitez

2011-01-01

415

Konishi Anomalies and Curves without Adjoints  

E-print Network

Generalized Konishi anomaly relations in the chiral ring of N=1 supersymmetric gauge theories with unitary gauge group and chiral matter field in two-index tensor representations are derived. Contrary to previous investigations of related models we do not include matter multiplets in the adjoint representation. The corresponding curves turn out to be hyperelliptic. We also point out equivalences to models with orthogonal or symplectic gauge groups.

Karl Landsteiner

2004-06-24

416

Fusion and normalization to enhance anomaly detection  

NASA Astrophysics Data System (ADS)

This study examines normalizing the imagery and the optimization metrics to enhance anomaly and change detection, respectively. The RX algorithm, the standard anomaly detector for hyperspectral imagery, more successfully extracts bright rather than dark man-made objects when applied to visible hyperspectral imagery. However, normalizing the imagery prior to applying the anomaly detector can help detect some of the problematic dark objects, but can also miss some bright objects. This study jointly fuses images of RX applied to normalized and unnormalized imagery and has a single decision surface. The technique was tested using imagery of commercial vehicles in urban environment gathered by a hyperspectral visible/near IR sensor mounted in an airborne platform. Combining detections first requires converting the detector output to a target probability. The observed anomaly detections were fitted with a linear combination of chi square distributions and these weights were used to help compute the target probability. Receiver Operator Characteristic (ROC) quantitatively assessed the target detection performance. The target detection performance is highly variable depending on the relative number of candidate bright and dark targets and false alarms and controlled in this study by using vegetation and street line masks. The joint Boolean OR and AND operations also generate variable performance depending on the scene. The joint SUM operation provides a reasonable compromise between OR and AND operations and has good target detection performance. In addition, new transforms based on normalizing correlation coefficient and least squares generate new transforms related to canonical correlation analysis (CCA) and a normalized image regression (NIR). Transforms based on CCA and NIR performed better than the standard approaches. Only RX detection of the unnormalized of the difference imagery in change detection provides adequate change detection performance.

Mayer, R.; Atkinson, G.; Antoniades, J.; Baumback, M.; Chester, D.; Edwards, J.; Goldstein, A.; Haas, D.; Henderson, S.; Liu, L.

2009-05-01

417

Statistical significance of the gallium anomaly  

SciTech Connect

We calculate the statistical significance of the anomalous deficit of electron neutrinos measured in the radioactive source experiments of the GALLEX and SAGE solar neutrino detectors, taking into account the uncertainty of the detection cross section. We found that the statistical significance of the anomaly is {approx}3.0{sigma}. A fit of the data in terms of neutrino oscillations favors at {approx}2.7{sigma} short-baseline electron neutrino disappearance with respect to the null hypothesis of no oscillations.

Giunti, Carlo; Laveder, Marco [INFN, Sezione di Torino, Via P. Giuria 1, I-10125 Torino (Italy); Dipartimento di Fisica 'G. Galilei', Universita di Padova, and INFN, Sezione di Padova, Via F. Marzolo 8, I-35131 Padova (Italy)

2011-06-15

418

An Adaptive Anomaly Detector for Worm Detection  

Microsoft Academic Search

We present an adaptive end-host anomaly detector where a supervised classifier trained as a trac predictor is used to control a time-varying detection threshold. Using real enterprise trac traces for both training and testing, we show that our detector outperforms a fixed-threshold de- tector. This comparison is robust to the choice of o-the- shelf classifier and to a variety of

John Mark Agosta; Carlos Diuk-Wasser; Jaideep Chandrashekar; Carl Livadas

419

OPAD data analysis. [Optical Plumes Anomaly Detection  

NASA Technical Reports Server (NTRS)

Data obtained in the framework of an Optical Plume Anomaly Detection (OPAD) program intended to create a rocket engine health monitor based on spectrometric detections of anomalous atomic and molecular species in the exhaust plume are analyzed. The major results include techniques for handling data noise, methods for registration of spectra to wavelength, and a simple automatic process for estimating the metallic component of a spectrum.

Buntine, Wray L.; Kraft, Richard; Whitaker, Kevin; Cooper, Anita E.; Powers, W. T.; Wallace, Tim L.

1993-01-01

420

Does partial melting explain geophysical anomalies?  

NASA Astrophysics Data System (ADS)

The existence of partial melt is frequently invoked to explain geophysical anomalies such as low seismic wave velocity and high electrical conductivity. I review various experimental and theoretical studies to evaluate the plausibility of this explanation. In order for a partial melt model to work, not only the presence of melt, but also the presence of appropriate amount of melt needs to be explained. Using the mineral physics observations on the influence of melt on physical properties and the physics and chemistry of melt generation and transport, I conclude that partial melt model for the asthenosphere with homogeneous melt distribution does not work. One needs to invoke inhomogeneous distribution of melt if one wishes to explain observed geophysical anomalies by partial melting. However, most of models with inhomogeneous melt distribution are either inconsistent with some geophysical observations or the assumed structures are geodynamically unstable and/or implausible. Therefore partial melt models for the geophysical anomalies of the asthenosphere are unlikely to be valid, and some solid-state mechanisms must be invoked. The situation is different in the deep upper mantle where melt could completely wet grain-boundaries and continuous production of melt is likely by “dehydration melting” at around 410-km. In the ultralow velocity zone in the D? layer, where continuous production of melt is unlikely, easy separation of melt from solid precludes the partial melt model for low velocities and high electrical conductivity unless the melt density is extremely close to the density of co-existing solid minerals or if there is a strong convective current to support the topography of the ULVZ region. Compositional variation such as Fe-enrichment is an alternative cause for the anomalies in the D? layer.

Karato, Shun-ichiro

2014-03-01

421

Multifactor Explanations of Asset Pricing Anomalies  

Microsoft Academic Search

Previous work shows that average returns on common stocks are related to firm characteristics like size, earnings\\/price, cash flow\\/price, book-to-market equity, past sales growth, long-term past return, and short-term past return. Because these patterns in average returns apparently are not explained by the capital asset pricing model, (CAPM), they are called anomalies. The authors find that, except for the continuation

EUGENE F. FAMA; KENNETH R. FRENCH

1996-01-01

422

Statistical Significance of the Gallium Anomaly  

E-print Network

We calculate the statistical significance of the anomalous deficit of electron neutrinos measured in the radioactive source experiments of the GALLEX and SAGE solar neutrino detectors taking into account the uncertainty of the detection cross section. We found that the statistical significance of the anomaly is about 3.0 sigma. A fit of the data in terms of neutrino oscillations favors at about 2.7 sigma short-baseline electron neutrino disappearance with respect to the null hypothesis of no oscillations.

Carlo Giunti; Marco Laveder

2011-03-28

423

Evaluation of anomalies in GLDAS-1996 dataset.  

PubMed

Global Land Data Assimilation System (GLDAS) data are widely used for land-surface flux simulations. Therefore, the simulation accuracy using GLDAS dataset is largely contingent upon the accuracy of the GLDAS dataset. It is found that GLDAS land-surface model simulated runoff exhibits strong anomalies for 1996. These anomalies are investigated by evaluating four GLDAS meteorological forcing data (precipitation, air temperature, downward shortwave radiation and downward longwave radiation) in six large basins across the world (Danube, Mississippi, Yangtze, Congo, Amazon and Murray-Darling basins). Precipitation data from the Global Precipitation Climatology Centre (GPCC) are also compared with GLDAS forcing precipitation data. Large errors and lack of monthly variability in GLDAS-1996 precipitation data are the main sources for the anomalies in the simulated runoff. The impact of the precipitation data on simulated runoff for 1996 is investigated with the Community Atmosphere Biosphere Land Exchange (CABLE) land-surface model in the Yangtze basin, for which area high-quality local precipitation data are obtained from the China Meteorological Administration (CMA). The CABLE model is driven by GLDAS daily precipitation data and CMA daily precipitation, respectively. The simulated daily and monthly runoffs obtained from CMA data are noticeably better than those obtained from GLDAS data, suggesting that GLDAS-1996 precipitation data are not so reliable for land-surface flux simulations. PMID:23579825

Zhou, Xinyao; Zhang, Yongqiang; Yang, Yonghui; Yang, Yanmin; Han, Shumin

2013-01-01

424

Rheologically induced structural anomalies in transpressive regimes  

NASA Astrophysics Data System (ADS)

Local structural anomalies are sometimes found in transpressive regimes. They can be related to strain partitioning processes but in some cases other types of heterogeneities could affect the deformation style. This paper shows that rheological heterogeneities can radically influence the geometry of faults in transpression zones and cause them to be markedly non-planar. In the Marão region of northern Portugal, a zone in which Variscan structures are SW-facing is found within the regional NE-facing geometry. This anomaly is adjacent to a complex shear zone (Mina/Ribeira das Cestas) where the fault plane is curved; however the surrounding material does not show any signs of a related folding event. Detailed field studies, mainly concerning the rheological contrasts between the deformed lithostratigraphic units, show a close relationship between the structural anomaly and the movement along rheological anisotropies. These observations, complemented by experimental deformation of multilayers composed of analogue materials, allow the construction of a generic model. Strain partitioning during the initial stage of the sinistral transpressive Variscan deformation produced the juxtaposition of lithostratigraphic units with strongly different rheological contrasts. Subsequent flattening deformation induced heterogeneous indentation phenomena, producing the non-planar geometry of the complex shear zone. The structural heterogeneities caused could have an important role in the evolution of a transpressive domain.

Coke, C.; Dias, R.; Ribeiro, A.

2003-03-01

425

Thermal Expansion Anomaly Regulated by Entropy  

NASA Astrophysics Data System (ADS)

Thermal expansion, defined as the temperature dependence of volume under constant pressure, is a common phenomenon in nature and originates from anharmonic lattice dynamics. However, it has been poorly understood how thermal expansion can show anomalies such as colossal positive, zero, or negative thermal expansion (CPTE, ZTE, or NTE), especially in quantitative terms. Here we show that changes in configurational entropy due to metastable micro(scopic)states can lead to quantitative prediction of these anomalies. We integrate the Maxwell relation, statistic mechanics, and first-principles calculations to demonstrate that when the entropy is increased by pressure, NTE occurs such as in Invar alloy (Fe3Pt, for example), silicon, ice, and water, and when the entropy is decreased dramatically by pressure, CPTE is expected such as in anti-Invar cerium, ice and water. Our findings provide a theoretic framework to understand and predict a broad range of anomalies in nature in addition to thermal expansion, which may include gigantic electrocaloric and electromechanical responses, anomalously reduced thermal conductivity, and spin distributions.

Liu, Zi-Kui; Wang, Yi; Shang, Shunli

2014-11-01

426

Conformal anomaly of super Wilson loop  

NASA Astrophysics Data System (ADS)

Classically supersymmetric Wilson loop on a null polygonal contour possesses all symmetries required to match it onto non-MHV amplitudes in maximally supersymmetric Yang-Mills theory. However, to define it quantum mechanically, one is forced to regularize it since perturbative loop diagrams are not well defined due to presence of ultraviolet divergences stemming from integration in the vicinity of the cusps. A regularization that is adopted by practitioners by allowing one to use spinor helicity formalism, on the one hand, and systematically go to higher orders of perturbation theory is based on a version of dimensional regularization, known as Four-Dimensional Helicity scheme. Recently it was demonstrated that its use for the super Wilson loop at one loop breaks both conformal symmetry and Poincaré supersymmetry. Presently, we exhibit the origin for these effects and demonstrate how one can undo this breaking. The phenomenon is alike the one emerging in renormalization group mixing of conformal operators in conformal theories when one uses dimensional regularization. The rotation matrix to the diagonal basis is found by means of computing the anomaly in the Ward identity for the conformal boost. Presently, we apply this ideology to the super Wilson loop. We compute the one-loop conformal anomaly for the super Wilson loop and find that the anomaly depends on its Grassmann coordinates. By subtracting this anomalous contribution from the super Wilson loop we restore its interpretation as a dual description for reduced non-MHV amplitudes which are expressed in terms of superconformal invariants.

Belitsky, A. V.

2012-09-01

427

Nuclear material safeguards surveillance and accountancy by isotope correlation techniques  

SciTech Connect

The purpose of this study is to investigate the applicability of isotope correlation techniques (ICT) to the Light Water Reactor (LWR) and the Liquid Metal Fast Breeder Reactor (LMFBR) fuel cycles for nuclear material accountancy and safeguards surveillance. The isotopic measurement of the inventory input to the reprocessing phase of the fuel cycle is the primary direct determination that an anomaly may exist in the fuel management of nuclear material. The nuclear materials accountancy gap which exists between the fabrication plant output and the input to the reprocessing plant can be minimized by using ICT at the dissolver stage of the reprocessing plant. The ICT allows a level of verification of the fabricator's fuel content specifications, the irradiation history, the fuel and blanket assemblies management and scheduling within the reactor, and the subsequent spent fuel assembly flows to the reprocessing plant. The investigation indicates that there exist relationships between isotopic concentration which have predictable, functional behavior over a range of burnup. Several cross-correlations serve to establish the initial core assembly-averaged composition. The selection of the more effective functionals will depend not only on the level of reliability of ICT for verification, but also on the capability, accuracy and difficulty of developing measurement methods. The propagation of measurement errors on the correlation functions and respective sensitivities to isotopic compositional changes have been examined and found to be consistent with current measurement methods.

Persiani, P.J.; Goleb, J.A.; Kroc, T.K.

1981-11-01

428

Presolar isotopic and chemical signatures in hibonite-bearing refractory inclusions from the Murchison carbonaceous chondrite  

NASA Technical Reports Server (NTRS)

The mineralogy and the major-element composition of phases within individual hibonite-bearing inclusions were determined, using SEM with EDAX analysis, for 37 hibonite-bearing inclusions which comprised 26 spinel-hibonite-perovskite inclusions, ten platy hibonite crystal fragments, and one blue hibonite aggregate. Results from all inclusions studied indicated the presence of correlations in hibonite isotopic systematics and chemistry. Namely, no inclusion had both a large Ti-50 anomaly and radiogenic Mg-26, and inclusions that were depleted in the ultrarefractory elements had radiogenic Mg-26 with the exception of those which a had a large Ti-50 anomaly. These features establish a relationship between chemical and isotopic characteristics of the inclusions which must predate their formation. It is suggested that depletions in ultrarefractory elements observed in these inclusions may be a memory of stellar condensation and are not necessarily related to a condensation event in the solar nebula.

Ireland, Trevor R.

1990-01-01

429

Isotope separation apparatus  

DOEpatents

Isotope separation apparatus consisting of a plurality of cells disposed adjacent to each other in an evacuated container. A common magnetic field is established extending through all of the cells. A source of energetic electrons at one end of the container generates electrons which pass through the cells along the magnetic field lines. Each cell includes an array of collector plates arranged in parallel or in tandem within a common magnetic field. Sets of collector plates are disposed adjacent to each other in each cell. Means are provided for differentially energizing ions of a desired isotope by applying energy at the cyclotron resonant frequency of the desired isotope. As a result, the energized desired ions are preferentially collected by the collector plates.

Arnush, Donald (Rancho Palos Verdes, CA); MacKenzie, Kenneth R. (Pacific Palisades, CA); Wuerker, Ralph F. (Palos Verdes Estates, CA)

1980-01-01

430

ENSO cycle and climate anomaly in China  

NASA Astrophysics Data System (ADS)

The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly (SOTA) and the associated anomalous atmospheric circulation over the Asian North Pacific during the El Niño-Southern Oscillation (ENSO) were investigated using National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) atmospheric reanalysis data and simple ocean data simulation (SODA). The relationship between the ENSO and the climate of China was revealed. The main results indicated the following: 1) there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2) during the mature phase of El Niño, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of El Niño, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Niña event causes an opposite, but weaker effect; 3) the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the "atmospheric-bridge", where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper.

Chen, Yongli; Zhao, Yongping; Feng, Junqiao; Wang, Fan

2012-11-01

431

Mass Independent Fractionation of Cadmium Isotopes During Thermal Ionization  

NASA Astrophysics Data System (ADS)

We have previously reported that Cd isotopes exhibit anomalous, non-mass dependent fractionation of odd versus even isotopes when measured by TIMS using silica gel-phosphoric acid activator. The deviation from mass dependent fractionation (MDF) on the odd masses 111 and 113 varies by fractions of a per-cent between runs. The effects cannot be explained by isobaric interferences, but seem, instead, to reflect mass independent fractionation (MIF) of Cd isotopes, much like that recently documented for Hg isotopes in natural systems (Bergquist and Blum, 2007). The absence of comparable Cd isotope anomalies in the ICP torch, and during extreme in-vacuo volatilization of Cd metal (Wombacher et al., 2004) conclusively implicates the silica gel activator in the process. So far, MIF has been documented for Cd, Zn and Pb isotopes when measured using the silica gel technique (Thirlwall, 2000; Schmitt et al., 2006; Manhes and Göpel, 2007). These MIF effects on Cd isotopes might perhaps be related to the non-mass dependence of nuclear volume with mass number, as described by Bigeleisen (1996) - also known as the "nuclear field shift". The MIF caused by the nuclear field shift results is a departure from MDF broadly characterized by a odd-even staggering with mass number. These effects have been quantified by Schauble (2007) who showed that the magnitude of the non-mass dependence for Hg and Tl isotopes lies in the ppm range for some simple reactions. Such MIF effects would appear, overall, far too small to account for our data, which require MIF offsets on the odd masses 111 and 113 approaching a per-cent. Moreover, an in-depth examination along the lines of Fujii et al. (2006) predicts tell-tale offsets for the even-even isotope pairs 114Cd/112Cd and 116Cd/112Cd as well, based upon the theory and the respective nuclear radii, but such accompanying offsets are unequivocally absent in our data. The odd-even isotope effects seen in our runs using silica gel activator are better explained by appealing to the nuclear spin (and magnetic moment) of odd nuclei alone. The "magnetic isotope effect" is a consequence of hyperfine coupling, in which an electron interacts with a nucleus of non-zero magnetic moment - i.e. one that has an odd number of nucleons (Turro, 1983; Buchachenko, 1995, 2001). This is purely a kinetic phenomenon in which the life-time, and thus the outcome, of reaction transition states is altered by the hyperfine splitting present in atoms with odd nuclei. The mechanism by which silica gel activator enhances the thermal ionization of elements such as Cd, Pb and Zn has been outlined by Kessinger and Delmore (2002). The first step involves the in-situ reduction of Cd2+ ions to Cd metal in the molten silica gel-phosphoric acid glass. It is most likely in this step - whereby two electrons are added - that a suitably long-lived transition state exists, during which the magnetic isotope effect enhances (or inhibits) reduction of masses 111 and 113 to metal species compared to those of even isotopes of Cd. The resulting "odd" and "even" populations of Cd-metal in the molten silica gel then cannot be related simply in terms of MDF. Overall, the magnetic isotope effect provides the best explanation of the MIF effects observed for Pb, Cd and Zn during thermal ionization with silica gel activator, and, probably, why the measured fractionation is always biased towards light isotopes.

Abouchami, W.; Galer, S. J.; Feldmann, H.; Schmitt, A. D.

2008-12-01

432

Principles of isotope geology  

Microsoft Academic Search

Discussions of methods of isotope dating using Rb-Sr, K-Ar, ⁴°Ar\\/³⁹Ar, Re-Os, Lu-Hf, K-Ca, U, Tb-Pb, ¹⁴C, common lead, S,O,H, fission track, and U-series disequilibrium are included in respective chapters. Introductory chapters discussing the basics of isotope geology, atomic structure, decay mechanisms and mass spectrometry are included along with two appendices; the geological time scale for the Phanerzoic and a fitting

G Faure

1977-01-01

433

Emission characteristics of an ultraviolet emitter based on mixtures of krypton with low-aggressive halogen carriers pumped by a barrier discharge  

NASA Astrophysics Data System (ADS)

The emission characteristics of a pulse-periodic excilamp with three dielectric barriers based on the 222-nm KrCl( X- B) and 248-nm KrF( X- B) emission bands have been investigated. The working gases of the lamp were mixtures of krypton with low-aggressivity halogen carriers (SF6, CCl4). Optimal compositions of Kr-SF6 and Kr-CCl4 mixtures for obtaining the maximum intensity of the system of 222-nm KrCl( X- B) and 248-nm KrF( X- B) bands have been determined. The results of lamp optimization depending on the parameters of the source of pulse-periodic short-duration barrier discharge are presented.

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

2013-02-01

434

Near-bottom water column anomalies associated with active hydrothermal venting at Aeolian arc volcanoes, Tyrrhenian Sea, Italy  

NASA Astrophysics Data System (ADS)

Hydrothermal deposits such as metalliferous sediments, Fe-Mn crusts, and massive sulfides are common on the submarine volcanoes of the Aeolian arc (Tyrrhenian Sea, Italy), but the extent and style of active hydrothermal venting is less well known. A systematic water column survey in 2007 found helium isotope ratios indicative of active venting at 6 of the 9 submarine volcanoes surveyed plus the Marsili back-arc spreading center (Lupton et al., 2011). Other plume indicators, such as turbidity and temperature anomalies were weak or not detected. In September 2011, we conducted five ROV Hercules dives at Eolo, Enarete, and Palinuro volcanoes during an E/V Nautilus expedition. Additionally, two dives explored the Casoni seamount on the southern flank of Stromboli where a dredge returned apparently warm lava in 2002 (Gamberi, 2006). Four PMEL MAPRs, with temperature, optical backscatter (particles), and oxidation-reduction potential (ORP) sensors, were arrayed along the lowermost 50 m of the Hercules/Argus cable during the dives to assess the relationship between seafloor observations and water column anomalies. Active venting was observed at each of the volcanoes visited. Particle anomalies were weak or absent, consistent with the 2007 CTD surveys, but ORP anomalies were common. Venting at Eolo volcano was characterized by small, localized patches of yellow-orange bacteria; living tubeworms were observed at one location. ORP anomalies (-1 to -22 mv) were measured at several locations, primarily along the walls of the crescent-shaped collapse area (or possible caldera) east of the Eolo summit. At Enarete volcano, we found venting fluids with temperatures up to 5°C above ambient as well as small, fragile iron-oxide chimneys. The most intense ORP anomaly (-140 mv) occurred at a depth of about 495 m on the southeast side of the volcano, with smaller anomalies (-10 to -20 mv) more common as the ROV moved upslope to the summit. At Palinuro volcano, multiple dives located several active sites along the 50-km-long summit. The distribution of ORP anomalies seen during these dives correlates quite well with the locations of anomalous helium samples from 2007. An ORP anomaly of -160 mv was located at the west end of Palinuro where vent fluids up to 54°C were found. Living tubeworms, bacterial mats of various colors and textures, and small chimneys and globular spires coated with iron oxide having bright-green interiors indicative of the iron-rich hydrothermal clay nontronite were found at actively venting areas on Palinuro. ORP anomalies were generally only detected in the near-bottom MAPR mounted on Hercules. In a few locations the MAPRs on Argus (10-30 meters above bottom) and 25 meters above Argus registered anomalies not seen by the MAPR on Hercules indicating active venting nearby, but not observed along the trackline of the ROV. Only the higher-temperature vent site at the west end of Palinuro generated a plume that had an appreciable particle anomaly and rise height (seen by the Argus+25m MAPR). No anomalies were measured by the MAPR located 50 meters above Argus.

Walker, S. L.; Carey, S.; Bell, K. L.; Baker, E. T.; Faure, K.; Rosi, M.; Marani, M.; Nomikou, P.

2012-12-01

435

Climatic significance of isotope ratios  

Microsoft Academic Search

The hydrogen and oxygen isotope ratios of water, which can be measured by Isotope Ratio Mass Spectrometry (IRMS), exhibit climatic dependencies and are commonly exploited in hydrogeology. More generally, the overall carbon or hydrogen isotope ratios of plant organic matter, and in particular of tree-ring cellulose, have been frequently used for climatic reconstruction. However, since many physicochemical and biochemical fractionation

Gérard J. Martin; Maryvonne L. Martin

2003-01-01

436

Colorado Plateau Stable Isotope Laboratory  

NSDL National Science Digital Library

This website, hosted by Northern Arizona University, describes stable isotopes. The site defines stable isotopes and how to measure them, and lists their research applications. Many of the advances in ecology and environmental sciences in the past decade have relied on stable isotopes.

Colorado Plateau Stable Isotope Laboratory (CPSIL); University, Northern A.

437

8, 93479404, 2008 Sulfur isotope  

E-print Network

ACPD 8, 9347­9404, 2008 Sulfur isotope analyses of individual aerosol particles B. Winterholler et the Creative Commons Attribution 3.0 License. Atmospheric Chemistry and Physics Discussions Sulfur isotope