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1

Beta Decay Studies of Short Lived Barium Isotopes  

Microsoft Academic Search

The half-lives and relative intensities of several short lived neutron rich isotopes, with atomic numbers between 54 and 57, produced in the spontaneous fission of californium-252 were determined. This was accomplished from the study of the time variation of the K X-ray yields of these isotopes. A transport system which allowed us to study isotopes with half-lives less than 10

Charles Skipwith Bendall

1984-01-01

2

Injection of Short-Lived Isotopes into the Presolar Cloud  

NASA Astrophysics Data System (ADS)

The evidence for short-lived isotopes such as 26 Al and 41 Ca in meteorites requires their production either by irradiation in the solar nebula or by nucleosynthesis in a supernova or other evolved star. In the latter case, nucleosynthesis must be followed promptly by injection of the isotopes into the presolar cloud, a feat presumably accomplished by the same stellar outflow that transported the isotopes to the presolar cloud and possibly triggered its collapse. If their nucleosynthesis occurs deep within an unmixed star, the short-lived isotopes may lag far behind the leading edge of the stellar outflow, perhaps preventing their injection. However, we show that lagging isotopes can be injected into a collapsing protostar with an efficiency similar to that of material in the leading edge of the outflow, because fast-moving isotopes initially far behind (approximately a few parsecs) the leading edge impact and enter the cloud while the injection process is still underway. Isotope injection proceeds through Rayleigh-Taylor-like clumps in the shock-compressed target cloud.

Boss, Alan P.; Foster, Prudence N.

1998-02-01

3

Beta Decay Studies of Short Lived Barium Isotopes  

NASA Astrophysics Data System (ADS)

The half-lives and relative intensities of several short lived neutron rich isotopes, with atomic numbers between 54 and 57, produced in the spontaneous fission of californium-252 were determined. This was accomplished from the study of the time variation of the K X-ray yields of these isotopes. A transport system which allowed us to study isotopes with half-lives less than 10 seconds was developed. Mass assignments were made by comparing the experimental values of the half-lives with known values. A beta K X-ray coincidence technique was used to obtain the barium beta spectrum in coincidence with lanthanum K X -rays. A Kurie plot was performed on the spectrum to determine the beta groups. The probable origin of each beta group was determined through a comparison of the relative intensities of the isotopes and beta groups. Four beta groups probably from the decay of Ba-145 were revealed. The end point energies of these beta groups are 3870 (+OR-) 432 keV, 2772 (+OR-) 112 keV, 1894 (+OR-) 58 keV, and 746 (+OR-) 38 keV. The three lowest energy groups have not been observed before.

Bendall, Charles Skipwith

4

Search for Short Lived Isotopes in Volatile Reactor Fuel Products.  

National Technical Information Service (NTIS)

The volatile radioactive nuclides produced by thermal neutron fissioning of uranium oxide-polyethylene fuel of the AGN-201 Reactor were collected in an evacuated aluminum cylinder. The following constituent isotopes, identified by gamma ray spectrometry, ...

W. D. Fagan

1969-01-01

5

Heavy-ion-induced production and physical preseparation of short-lived isotopes for chemistry experiments  

Microsoft Academic Search

Physical separation of short-lived isotopes produced in heavy-ion-induced fusion reactions is a powerful and well-known method and often applied in investigations of the heaviest elements, called the transactinides (Z?104). By extracting these isotopes from a recoil separator, they can be made available for transport to setups located outside the heavily shielded irradiation position such as chemistry setups. This physical preseparation

Ch. E. Düllmann; C FOLDENIII; K. E. Gregorich; D. C. Hoffman; D. Leitner; G. K. Pang; R. Sudowe; P. M. Zielinski; H. Nitsche

2005-01-01

6

Simulation Studies of Diffusion-Release and Effusive Flow of Short-Lived Radioactive Isotopes  

Microsoft Academic Search

Simulation studies with computer models offer cost effective methods for designing targets and vapor transport systems at Isotope Separator On-Line (ISOL)-based radioactive ion beam facilities. A finite difference code, Diffuse II, was developed at the Oak Ridge National Laboratory (ORNL) for studying diffusion-release of short-lived ion species from the three principal target geometries; results derived by use of the code

Y. Zhang; G. D. Alton; Y. Kawai

2005-01-01

7

Study of short-lived tin isotopes with a laser ion source  

SciTech Connect

A chemically selective laser ion source based on resonance ionization of atoms in a hot cavity was applied for study of short-lived tin isotopes at the heavy ion accelerator UNILAC/GSI. Tin atoms were ionized by a three-step resonance laser excitation of an autoionizing state. Yields of fusion-produced {sup 108}Sn and {sup 108}In isotopes were compared with the plasma ion source FEBIAD-B3. The total efficiency of tin ionization was determined to be 8.5%, whilst the indium isobar ionization was suppressed by a factor of 12. An experimental run on study of decay properties of extremely neutron deficient isotopes {sup 101-103}Sn has been carried out.

Fedoseyev, V. N.; Albus, F.; Kirchner, R.; Klepper, O.; Kluge, H.-J.; Mishin, V. I.; Passler, G.; Roeckl, E.; Scheerer, F.; Schmidt, K.; Trautmann, N. [Institute of Spectroscopy, Russian Academy of Sciences, 142092, Trotzk (Russian Federation); Institut fuer Physik, Universitaet Mainz, D-55029 Mainz (Germany); GSI-Darmstadt, D-64220 Darmstadt (Germany); Institut fuer Physik, Universitaet Mainz, D-55029 Mainz (Germany); Institute of Spectroscopy, Russian Academy of Sciences, 142092, Trotzk (Russian Federation); Institut fuer Physik, Universitaet Mainz, D-55029 Mainz (Germany); GSI-Darmstadt, D-64220 Darmstadt (Germany); Institut fuer Kernchemie, Universitaet Mainz, D-55029 Mainz (Germany); GSI-Darmstadt, D-64220 Darmstadt (Germany); Institut fuer Kernchemie, Universitaet Mainz, D-55029 Mainz (Germany)

1995-04-01

8

Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer  

SciTech Connect

A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for {sup 118}Cs--{sup 137}Cs. A resolving power of over 10{sup 6} and an accuracy of 1.4{times}10{sup {minus}7} have been achieved, corresponding to about 20 keV.

Stolzenberg, H.; Becker, S.; Bollen, G.; Kern, F.; Kluge, H.; Otto, T.; Savard, G.; Schweikhard, L. (Institut fuer Physik, Universitaet Mainz, D-6500 Mainz (Federal Republic of Germany)); Audi, G. (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Laboratoire Rene Bernas, Batiment 108, F-91405 Orsay (France)); Moore, R.B. (Foster Radiation Laboratory, McGill University, Montreal (Canada)); The ISOLDE Collaboration

1990-12-17

9

Simulation and optimization of cyclic activation analysis of short-lived isotopes with 14MeV neutron generator.  

PubMed

A program of simulation and optimization is developed for the case of cyclic activation analysis of short-lived isotopes with 14-MeV neutrons. The background line under the photopeaks of interest is simulated using Zikovsky's model. The reliability of the program is checked on real conditions with a geological reference sample "Soil 5" provided by the IAEA. Optimum experimental conditions (timing parameters, number of cycles) are determined, and corresponding detection limits calculated. A systematic study of short-lived isotopes with half-lives lower than 5 min is done for Soil 5, and the results are discussed. PMID:7710887

Khelifi, R; Idiri, Z; Tobbeche, S

1994-01-01

10

Automated system for neutron activation analysis determination of short lived isotopes at The DOW Chemical Company's TRIGA research reactor  

Microsoft Academic Search

An automated neutron activation analysis (NAA) system for the determination of short lived isotopes was constructed at The DOW Chemical Company's TRIGA Research Reactor in 1993. The NAA group of the Analytical Sciences Laboratory uses the reactor for thousands of analyses each year and therefore automation is important to achieve and maintain high throughput and precision (productivity). This project is

J. J. Zieman; W. L. Rigot; J. D. Romick; T. J. Quinn; C. W. Kocher

1994-01-01

11

Nuclear Moments and Differences in Mean Square Charge Radii of Short-Lived Neon Isotopes by Collinear Laser Spectroscopy  

Microsoft Academic Search

The nuclear moments and charge radii of short-lived neon isotopes were measured by the use of collinear laser spectroscopy at the on-line mass separator ISOLDE at CERN. After a general introduction the semiclassical theory of atomic spectra is given and the relevant properties are calculated for neon. The atomic physics section is followed by a description of the experimental setup

R W Geithner; R Neugart

2002-01-01

12

Precision mass measurements of very short-lived, neutron-rich Na isotopes using a radio-frequency spectrometer  

NASA Astrophysics Data System (ADS)

Mass measurements of high precision have been performed on sodium isotopes out to 30Na using a new technique of radio-frequency excitation of ion trajectories in a homogeneous magnetic field. This method, especially suited to very short-lived nuclides, has allowed us to significantly reduce the uncertainty in mass of the most exotic Na isotopes: a relative error of 5×10-7 was achieved for 28Na having a half-life of only 30.5 ms and 9×10-7 for the weakly produced 30Na. Verifying and minimizing binding energy uncertainties in this region of the nuclear chart is important for clarification of a long-standing problem concerning the strength of the N=20 magic shell closure. These results are the fruit of the commissioning of the new experimental program MISTRAL.

Lunney, D.; Audi, G.; Doubre, H.; Henry, S.; Monsanglant, C.; de Saint Simon, M.; Thibault, C.; Toader, C.; Borcea, C.; Bollen, G.; ISOLDE Collaboration

2001-11-01

13

First Measurement of the Nuclear Carge Radii of Short-Lived Lithium Isotopes  

SciTech Connect

A novel method for the determination of nuclear charge radii of lithium isotopes is presented. Precise laser spectroscopic measurements of the isotope shift in the lithium 2s? 3s transition are combined with highly accurate atomic physics calculation of the mass dependent isotope shift to extract the charge-distribution-sensitive information. This approach has been used to determine the charge radii of 6,7,8,9Li.

Nortershauser, W.; Dax, A ..; Ewald, G; Gotte, S; Kirchner, Rolf; Kluge, H J.; Kuhl, T H.; Sanchez, Rodolfo; Wojtaszek, A.; Bushaw, Bruce A.; Drake, Gordon W. F.; Yan, Z C.; Zimmerman, C.

2006-04-01

14

Isolation of short-lived isotopes of lanthanum and indium by ?-diketonates sublimation  

Microsoft Academic Search

Trace amounts of lanthanum hexafluoroacetylacetonate and indium acetylacetonate were isolated by combination of methods, which includes synthesis of volatile elements -diketonates by nucleophilic ligands exchange and fractional sublimation. This method is useful for produce isotope generators.

A. V. Davidov; M. I. Isenberg; E. V. Fedoseev; S. S. Travnikov

1996-01-01

15

Isotope-shift measurements of stable and short-lived lithium isotopes for nuclear-charge-radii determination  

SciTech Connect

Changes in the mean square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8-ms-lifetime isotope with production rates on the order of only 10 000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope {sup 11}Li at the on-line isotope separators at GSI, Darmstadt, Germany, and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results.

Noertershaeuser, W.; Sanchez, R. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Institut fuer Kernchemie, Universitaet Mainz, D-55099 Mainz (Germany); Ewald, G.; Dax, A.; Goette, S.; Kluge, H.-J.; Kuehl, Th.; Wojtaszek, A. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Behr, J.; Bricault, P.; Dilling, J.; Dombsky, M.; Lassen, J.; Levy, C. D. P.; Pearson, M. [TRIUMF, Vancouver, British Columbia, V6T 2A3 (Canada); Bushaw, B. A. [Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Drake, G. W. F. [Department of Physics, University of Windsor, Windsor, Ontario, N9B 3P4 (Canada); Pachucki, K. [Faculty of Physics, University of Warsaw, PL-00-681 Warsaw (Poland); Puchalski, M. [Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, PL-60-780 Poznan (Poland); Yan, Z.-C. [Department of Physics, University of New Brunswick, Fredericton, New Brunswick, E3B 5A3 (Canada)

2011-01-15

16

Mass measurements of short-lived isotopes in a penning trap  

SciTech Connect

A mass spectrometer has been set up at the on-line isotope separator ISOLDE at CERN/Geneva. Mass-separated radioactive ions are stored in a Penning trap. Their mass is determined by a measurement of the cyclotron frequency in the magnetic field of a superconducting magnet. A resolving power of up to 300.000 and a precision of some 10 keV were determined in case of mass measurements of neutron-deficient RB and Cs isotopes. The resonance of the isobars /sup 88/Sr and /sup 88/Rb were clearly resolved and evidence was obtained for an isomer in /sup 122/Cs.

Kern, F.; Egelhof, P.; Hilberath, T.; Kalinowsky, H.; Kluge, H.h.; Kunz, K.; Schweikhard, L.; Stolzenberg, H.; Moore, R.B.; Audi, G.; and others

1987-12-10

17

Should the Poisson statistical density function be used in the mesurement of short-lived isotopes?  

Microsoft Academic Search

The conditions under which the Poisson statistical density function adequately describes the counting of a radioactive isotope\\u000a are examined and found that for counting processes where ?t?1, where ? is the decay constant and t the counting period, one\\u000a of the fundamental properties, namely the condition of stationarity, is violated rendering application of Poisson statistics\\u000a invalid. The Ruark-Devol statistical density

N. M. Spyrou; J. Foster; M. C. Jones; K. Kouris; I. P. Matthews

1981-01-01

18

Development of radioactive ion beam production systems for Tokai Radioactive Ion Acceleration Complex-High temperature ion source for short-lived isotopes  

NASA Astrophysics Data System (ADS)

We have developed a new ion source system in the isotope separator on-line at Japan Atomic Energy Agency, for separation of short-lived isotopes produced by proton-induced fission of 238U. The ion source system is a forced electron beam induced arc discharge version E type ion source with a target container. We successfully operated this system at 2000 °C as a result of reductions in volume of the ion source and the target container, introduction of heating method by electron bombardment, and improvement to the heat shield. This new ion source system was tested using 238U of 640 mg/cm2 with a proton primary beam of 30 MeV, 350 nA. Release times were measured for Kr, In, and Xe. The values of release times are 2.6 s for Kr, 1.8 s for In, and 4.6 s for Xe. In this work, the ion source system enabled us to mass-separate short-lived isotopes such as 93Kr(T1/2=1.286 s), 129In(T1/2=0.61 s), and 141Xe(T1/2=1.73 s) with intensity of 103 ions/s.

Otokawa, Y.; Osa, A.; Sato, T. K.; Matsuda, M.; Ichikawa, S.; Jeong, S. C.

2010-02-01

19

Li and B isotopic variations in an Allende CAI: Evidence for the in situ decay of short-lived 10Be and for the possible presence of the short-lived nuclide 7Be in the early solar system  

NASA Astrophysics Data System (ADS)

The concentrations and isotopic compositions of lithium, beryllium, and boron, analyzed in situ by ion microprobe in 66 spots of a type B1 Ca-Al-rich inclusion (CAI 3529-41) from the Allende meteorite, are reported. Large variations are observed for both the Li and the B isotopic ratios with 7Li/ 6Li ranging from 9.2 ± 0.22 to 12.22 ± 0.43 (a ?250‰ range in ?7Li values) and 10B/ 11B ranging from 0.2468 ± 0.0057 to 0.4189 ± 0.0493 (a 410‰ range in ?11B values). The very low Li concentrations (<1 ppb) observed in several anorthite and fassaite grains require that a correction for the contribution of spallogenic Li produced during irradiation of the Allende meteoroid by galactic cosmic rays (GCR) be made (after this correction 7Li/ 6Li ranges from 9.2 ± 0.22 to 13.44 ± 0.56, i.e., a ?350‰ range in ?7Li values). In 3529-41, the 10B/ 11B ratios are positively correlated with 9Be/ 11B in a manner indicating the in situ decay of short-lived 10Be (half-life = 1.5 Ma) with a 10Be/ 9Be ratio at the time of formation of the CAI of 8.8 ± 0.6 × 10 -4, which is in agreement with previous findings [McKeegan, K.D., Chaussidon, M., Robert, F., 2000. Incorporation of short-lived 10Be in a calcium-aluminum-rich inclusion from the Allende meteorite. Science289, 1334-1337]. The present detailed investigation demonstrates that only minor perturbations of the 10Be- 10B system are present in 3529-41, contrary to the 26Al/ 26Mg system for which numerous examples of isotopic redistribution following crystallization were observed [Podosek, F.A., Zinner, E.K., MacPherson, G.J., Lundberg, L.L., Brannon, J.C., Fahey, A.J., 1991. Correlated study of initial 87Sr/ 86Sr and Al-Mg systematics and petrologic properties in a suite of refractory inclusions from the Allende meteorite. Geochim. Cosmochim. Acta55, 1083-1110]. Petrographically based criteria were developed to identify within the 66 analyzed spots in 3529-41, those where post-magmatic perturbation of the Li and Be distributions occurred. Li and Be concentrations measured in different analytical spots are compared with those predicted by using experimentally determined partition coefficients according to a model of closed-system crystallization of the CAI melt. These criteria show that 56% of the spots in melilite, 38% in anorthite, and 8% in fassaite suffered post-crystallization perturbations of Li and/or Be distributions. In the remaining spots, which do not show obvious indication of redistribution of Li or Be, the 7Li/ 6Li isotopic variations (corrected for GCR exposure) are positively correlated with 9Be/ 6Li suggesting the in situ decay of now-extinct 7Be. The derived isochron implies that at the time of its formation, the CAI melt had a 7Be/ 9Be ratio of 0.0061 ± 0.0013 and a 7Li/ 6Li ratio of 11.49 ± 0.13. In contrast, all the spots in 3529-41, which do show evidence for post-magmatic redistribution of Li and Be, have relatively constant 7Li/ 6Li, averaging 11.72 ± 0.56, which is consistent with mass balance calculations for Li isotopic homogenization in the CAI after the decay of 7Be. The incorporation of live 7Be in 3529-41 requires, because of the very short half-life of this nuclide (53 days), that it be produced essentially contemporaneously with the formation of the CAI. Therefore, the irradiation processes responsible for production of 7Be must have occurred within the solar accretion disk. Calculations developed in the framework of the x-wind model [Gounelle, M., Shu, F.H., Shang, H., Glassgold, A.E., Rehm, E.K., Lee, T., 2004. The origin of short-lived radionuclides and early Solar System irradiation (abstract). Lunar Planet. Sci.35, 1829] reproduce the 7Be and 10Be abundances observed in 3529-41. The correlated presence of 7Be and 10Be in 3529-41 is thus a strong argument that 10Be, which is observed rather ubiquitously in CAIs, is also a product of irradiation in the early solar system, as might be a significant fraction of other short-lived radionuclides observed in early solar system materials.

Chaussidon, Marc; Robert, François; McKeegan, Kevin D.

2006-01-01

20

Determination of water ages and flushing rates using short-lived radium isotopes in large estuarine system, the Yangtze River Estuary, China  

NASA Astrophysics Data System (ADS)

We investigated the spatial and temporal distribution of naturally-occurring short-lived radium isotopes (224Ra, t1/2 = 3.6 d and 223Ra, t1/2 = 11 d) to examine coastal water mixing dynamics of the third world largest estuary, Yangtze River Estuary (YRE) during two field trips in April 2010 and May 2011. Distributions of the 224Ra/223Ra activity ratios within the YRE area were used to calculate apparent estuarine water ages. Field-derived results were then compared to hydrodynamic assessments obtained by a Lagrangian particle tracking simulation experiment performed using the Princeton Ocean Model (POM). Water ages obtained via both geotracers and particle tracking agree very well. During both field trips an anomalously "younger" water mass (low salinity and higher radium activities) was observed at about 90-170 km offshore distance from the mouth of the river, suggesting an additional terrestrial water source influenced this area. The temporal distribution of the radium isotopes indicated a semi-diurnal tidal pattern in the YRE with relatively constant isotopic composition of less than a 20% variation during our observations. An integrated water flushing rate based on our observations (excluding the additional anomalous source area) was 8.4 km day-1.

Xu, Bo-Chao; Dimova, Natasha T.; Zhao, Liang; Jiang, Xue-Yan; Yu, Zhi-Gang

2013-04-01

21

Beta-decay energies and masses of short-lived isotopes of rubidium, caesium, francium, and radium  

Microsoft Academic Search

Total decay energies have been measured for a number of neutron-deficient Rb and Cs isotopes, as well as for some neutron-rich isotopes of Fr and Ra. Mass separated sources were produced at the ISOLDE on-line separator at CERN. By applying two differentß-? coincidence methods,Q values or their lower limits were determined for76–78Rb,80Rb,121–124Cs,222Fr,224–226Fr,229Ra-229Ac. For many of these nuclei, the atomic mass

L. Westgaard; K. Aleklett; G. Nyman; E. Roeckl

1975-01-01

22

Short-lived radioactivity and magma genesis  

NASA Astrophysics Data System (ADS)

Short-lived decay products of uranium and thorium have half-lives and chemistries sensitive to the processes and time scales of magma genesis, including partial melting in the mantle and magmatic differentiation in the crust. Radioactive disequilibrium between U-238, Th-230, and Ra-226 is widespread in volcanic rocks. These disequilibria and the isotopic composition of thorium depend especially on the extent and rate of melting as well as the presence and composition of vapor during melting. The duration of mantle melting may be several hundred millennia, whereas ascent times are a few decades to thousands of years. Differentiation of most magmas commonly occurs within a few millennia, but felsic ones can be tens of millennia old upon eruption.

Gill, James; Condomines, Michel

1992-09-01

23

Oxygen isotopic and geochemical evidence for a short-lived, high-temperature hydrothermal event in the Chegem caldera, Caucasus Mountains, Russia  

USGS Publications Warehouse

Within the 2.8 Ma Chegem ash-flow caldera (11 ?? 15 km), a single cooling unit of rhyolitic to dacitic welded tuff more than 2 km thick is exposed in deep valleys incised during recent rapid uplift of the Caucasus Mountains. The intracaldera tuff is mineralogically fresh and unaltered, and is overlain by andesite lavas and cut by a resurgent granodiorite intrusion. Major- and trace-element compositions for a 1405-m stratigraphic section of intracaldera tuff display trends of upwardly increasing Na2O, CaO, Al2O3, total Fe, MgO, TiO2, Sr and Zr and decreasing SiO2, K2O and Rb. This mafic-upward zoning (from 76.1 to 69.9% SiO2) reflects an inverted view of the upper part of the source magma chamber. Oxygen isotope studies of 35 samples from this 1405-m section define a striking profile with "normal" igneous ??18O values (+7.0 to +8.5) in the lower 600 m of tuff, much lower ??18O values (-4.0 to +4.3) in a 700-m zone above that and a shift to high ??18O values (+4.4 to -10.9) in the upper 100 m of caldera-fill exposure. Data from two other partial stratigraphic sections indicate that these oxygen isotope systematics are probably a caldera-wide phenomenon. Quartz and feldspar phenocrysts everywhere have "normal" igneous ??18O values of about +8.5 and +7.5, respectively, whereas groundmass and glass ??18O values range from -7.7 to +12.3. Consequently, the ??18O values of coexisting feldspar, groundmass and glass form a steep array in a plot of ??feldspar vs. ??groundmass/glass. Such pronounced disequilibrium between coexisting feldspar and groundmass or glass has never before been observed on this scale. It requires a hydrothermal event involving large amounts of low-18O H2O at sufficiently high temperatures and short enough time (tens of years or less) that glass exchanges thoroughly but feldspar does not. The most likely process responsible for the O depletions at Chegem is a very high temperature (500-600??C), short-lived, vigorous meteoric-hydrothermal event that was focused within the upper 750 m of intracaldera tuff. Mass balance calculations indicate fluid fluxes of = 6 ?? 10-6 mol cm-2 s-1. We believe that the closest historical analogue to this Chegem hydrothermal event is the situation observed in the Valley of Ten Thousand Smokes (Alaska, USA), where hundreds of steam fumaroles with measured temperatures as high as 645??C persisted for 10 to 15 years in the much smaller welded ash-flow tuff sheet (??? 200 m thick) produced by the 1912 Katmai eruption.

Gazis, C.; Taylor, Jr. , H. P.; Hon, K.; Tsvetkov, A.

1996-01-01

24

Evaluation of shelf basin interaction in the western Arctic by use of short-lived radium isotopes: The importance of mesoscale processes  

NASA Astrophysics Data System (ADS)

Shelf basin exchange in the western Arctic was evaluated by use of water-column analyses of 228Ra/226Ra ratios and the first measurements of the short-lived 224Ra (T1/2=3.64 d) in the Arctic. During the 2002 shelf basin interaction (SBI) program, excess 224Ra was detected over the shelf but was not found seaward of the shelf-break. Similarly, the 228Ra/226Ra ratio dropped rapidly from the shelf across the shelf-break. Consequently, the model age gradient (elapsed time since shelf residence) northward across the Chukchi Shelf increased from 1 5 years nearshore to approximately 14 years in surface waters sampled off shelf at the southern margin of the Beaufort Gyre. This steep gradient is consistent with very slow exchange between the Chukchi Shelf and the Beaufort Gyre, whereby Bering Strait inflow is constrained by the Earth's rotation to follow local isobaths and does not easily move into deeper water. The strong dynamic control inhibiting water that enters the system through Bering Strait from flowing north across isobaths also would lead to a long recirculation time of river water emptied into the Beaufort Gyre. Possible mechanisms that can generate cross-shelf currents that break the topographic constraint to follow isobaths, and thereby transport water (and associated properties) off the shelves include wind-induced upwelling/downwelling, meandering jets, and eddies. Evidence of such a process was found during the ICEX project in the Beaufort Sea in April 2003 when excess 224Ra was measured over 200 km from any shelf source. This required an NE offshore flow of ˜40 cm s-1 assuming that the source water derives from the mouth of Barrow Canyon. A weak northeastward flow was measured using an LADCP within the upper 300 m of the ocean, but was of lower speed than required by the 224Raxs at the time of the ICEX occupation.

Kadko, David; Muench, Robin

2005-12-01

25

A Short-lived Lunar Magma Ocean. Implications for the Evolution of the Early Lunar Crust  

Microsoft Academic Search

Complexities in lunar sample geochemistry are not easily explained by the standard models for the evolution of the lunar crust. Evidence from W isotopes for a short-lived magma ocean could help in deciphering these complexities.

C. K. Shearer; H. E. Newsom

1999-01-01

26

Half-lives of some short-lived mass-separated gaseous fission products and their daughters  

Microsoft Academic Search

The half-lives of several short-lived isotopes of Kr, Rb, Sr, Xe, Cs and Ba have been measured using sources of isotopically pure Xe or Kr and multi-scaling selected transitions in the Ge(Li) gamma-ray spectra of their decays. Beta-ray multi-scaling was employed to confirm the gamma-ray multi-scaling results in several cases. The results of the measurements are (in sec) 89Kr, 190.7+\\/-1.4

G. C. Carlson; W. C. Schick; W. L. Talbert; F. K. Wohn

1969-01-01

27

Oxygen isotope evidence for short-lived high-temperature fluid flow in the lower oceanic crust at fast-spreading ridges  

NASA Astrophysics Data System (ADS)

Millimeter-scale amphibole veins in the lower oceanic crust record fracture-controlled fluid flow at high-temperatures but the importance of this fluid flow for the thermal and chemical evolution of the lower oceanic crust is unclear. In the section of lower oceanic crust recovered at Hess Deep from ODP Hole 894G, which formed at the fast-spreading East Pacific Rise, these veins are randomly distributed with an average spacing of ˜ 1 m. We unravel the history of fluid flow through one of these veins by combining in situ O-isotope analyses of wall-rock plagioclase with major element analyses, geothermometry and diffusion modeling. Thermometry indicates vein sealing by amphibole at ˜ 720 °C over a narrow temperature interval (± 20 °C). In situ O-isotope analyses by ion microprobe, with a precision of < 0.5‰, reveal zoning of O-isotopes in plagioclase adjacent to the vein. The zoning profiles can be reproduced using a diffusion model if the duration of O-isotope exchange was ? 100 yr. A similar interval of fluid-rock exchange is suggested by modeling potassium depletion in plagioclase adjacent to the vein. If representative of fracture controlled fluid flow in the lower oceanic crust the limited duration of fluid flow, and its occurrence over a narrow temperature interval, suggest that high-temperature fluid flow in this porosity network does not transport significant heat.

Coogan, Laurence A.; Manning, Craig E.; Wilson, Robert N.

2007-08-01

28

Short-lived radium isotopes on the Scotian Shelf: Unique distribution and tracers of cross-shelf CO2 and nutrient transport  

NASA Astrophysics Data System (ADS)

Radium (Ra) isotopes have become a common tool for investigating mixing rates on continental shelves, and more recently have been used to quantify the release of dissolved compounds enriched in pore-waters into the water column. We present results from Ra sampling of the Scotian Shelf region of the Canadian northwestern Atlantic Ocean, which reveal cross-shelf Ra distributions that are unique compared to other coastal regions. We explain the observations of lower 224Ra activities near the coast, relatively high activities at large distances offshore (>100km), and gradients in both offshore and onshore directions by inferring the regional geomorphology, as well as shelf bathymetry and circulation patterns. Ra gradients are used to calculate individual estimates of eddy diffusion in both the cross-shelf (KX) and vertical (KZ) directions using 1-D eddy diffusion models. Enhanced vertical mixing above offshore banks allows for Ra enrichments in offshore surface waters, while horizontal dispersion of this bank-related signal can transport Ra off the shelf break in surface waters, and towards the shore beneath the surface mixed layer. Similar onshore gradients in CO2 and nutrient species combined with Ra-derived KX values can yield onshore carbon and nutrient fluxes in subsurface waters, which in turn supply the CO2 outgassing from the Scotian Shelf. Our results thus provide constraints for cross-shelf transports of carbon and nutrients on the Scotian Shelf in order to guide mass balance or model based budget approaches in future studies.

Burt, William; Thomas, Helmuth

2013-04-01

29

EVOLUTION OF THE SOLAR NEBULA. IX. GRADIENTS IN THE SPATIAL HETEROGENEITY OF THE SHORT-LIVED RADIOISOTOPES {sup 60}Fe AND {sup 26}Al AND THE STABLE OXYGEN ISOTOPES  

SciTech Connect

Short-lived radioisotopes (SLRIs) such as {sup 60}Fe and {sup 26}Al were likely injected into the solar nebula in a spatially and temporally heterogeneous manner. Marginally gravitationally unstable (MGU) disks, of the type required to form gas giant planets, are capable of rapid homogenization of isotopic heterogeneity as well as of rapid radial transport of dust grains and gases throughout a protoplanetary disk. Two different types of new models of an MGU disk in orbit around a solar-mass protostar are presented. The first set has variations in the number of terms in the spherical harmonic solution for the gravitational potential, effectively studying the effect of varying the spatial resolution of the gravitational torques responsible for MGU disk evolution. The second set explores the effects of varying the initial minimum value of the Toomre Q stability parameter, from values of 1.4 to 2.5, i.e., toward increasingly less unstable disks. The new models show that the basic results are largely independent of both sets of variations. MGU disk models robustly result in rapid mixing of initially highly heterogeneous distributions of SLRIs to levels of {approx}10% in both the inner (<5 AU) and outer (>10 AU) disk regions, and to even lower levels ({approx}2%) in intermediate regions, where gravitational torques are most effective at mixing. These gradients should have cosmochemical implications for the distribution of SLRIs and stable oxygen isotopes contained in planetesimals (e.g., comets) formed in the giant planet region ({approx}5 to {approx}10 AU) compared to those formed elsewhere.

Boss, Alan P., E-mail: boss@dtm.ciw.edu [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

2011-10-01

30

STUDIES OF SHORT-LIVED FISSION PRODUCTS AND THEIR IMPORTANCE TO REACTOR TECHNOLOGY  

Microsoft Academic Search

A systematic study of the decay schemes of some of the important alkali ; metal isotopes was made. Information is available on 17.8-minute Rb⁸⁸, ; 14.9-minute Rb⁸⁹, and 2.6-minute Rb⁹°. The decay characteristics of ; these nuclides show the general features exhibited by all of the short-lived ; fission products studied so far, namely, the short half-lives are related to

G. D. OKelley; E. Eichler; N. R. Johnson

1958-01-01

31

Release of short-lived fission products from intact and defected UOâ fuel elements  

Microsoft Academic Search

The rates of escape of short-lived isotopes of xenon and krypton to the coolant from a deliberately defected UOâ fuel element are at least 100 times greater than the release rates for identical species within an intact element. The enhanced escape is consistent with accelerated transport mechanisms under defect conditions. The rate of escape to the coolant of radioiodines is

Ian J. Hastings; C. E. Laurence Hunt; John J. Lipsett; Roderick D. MacDonald

1984-01-01

32

Half-lives of some Radioactive Isotopes  

Microsoft Academic Search

IN the course of investigations with radioactive isotopes in this Department, anomalous rates of decay have been observed with some isotopes in particular chemical forms. The escape of iodine-131 from evaporated samples of sodium iodide has already been reported by one of us1, and Hevesy2 has reported the escape of carbon-14 from exposed samples of barium carbonate. Anomalies have also

W. K. Sinclair; A. F. Holloway

1951-01-01

33

Analysis of long-lived isotopes by liquid scintillation spectrometry  

SciTech Connect

Neutron production cross sections are reported for reactions leading to long-lived isotopes in fusion reactor materials. Pure elements and separated isotopes were irradiated with 14.6 to 14.8 MeV neutron fluences up to 10 Y n/cmS. Undesired activities were chemically separated and the long-lived activities were measured using both liquid scintillation and x-ray spectrometry. Results are presented for the reactions VWFe(n,2n)VVFe (2.73 y), WUNi(n,2n)WTNi (100 y), WTCu(n,P)WTNi, and WNi(n,2n)VZNi (76,000 y).

Bowers, D.L.; Greenwood, L.R.

1987-01-01

34

Short-Lived Positron Emitter Labeled Radiotracers - Present Status.  

National Technical Information Service (NTIS)

The preparation of labelled compounds is important for the application of positron emission transaxial tomography (PETT) in biomedical sciences. This paper describes problems and progress in the synthesis of short-lived positron emitter ( exp 11 C, exp 18...

J. S. Fowler A. P. Wolf

1982-01-01

35

Overview of the methods for the measurement and interpretation of short-lived radioisotopes and their limits  

NASA Astrophysics Data System (ADS)

The daughter products of the uranium and thorium series consist of several radioactive isotopes with half-lives varying from less than a second to 105 years. Combining their half-live with their geochemical behaviour some of these radioisotopes could be used as tracers and/or chronometers of sedimentary processes. For example, thorium isotopes, and to a lesser extent polonium isotopes are characterized by very low solubility and very high affinity for the surface of particles. Consequently, thorium isotopes can be used to document scavenging and adsorption processes. On the other hand, radium isotopes tend to remain in solution and can be used to document diffusion processes. In the following, we present the analytical methods for the measurement and analysis of the most common short-lived isotopes and throughout their utility in studying sedimentary processes will be illustrated by a few examples of applications. These examples will focus essentially on the applications of short lived thorium isotopes (notably 234Th) and the use of 210Pb as chronometer for recent sedimentary accumulation.

Ghaleb, B.

2009-01-01

36

Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium  

SciTech Connect

Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.

2009-11-01

37

Spontaneous Fission Half Lives of Z = 112 Isotopes  

NASA Astrophysics Data System (ADS)

Barriers and spontaneous fission half lives of superheavy isotopes of Z = 112 (N = 150-190) nucleus are calculated using state dependent ?-pairing and both BCS or Lipkin-Nogami (LN) approach. Four different models of macroscopic part of Strutinsky energy are probed. Results for different macroscopic models combined with ?+LN approach give the half lives well compared to experimental data. The calculations are performed in three dimensional space of deformation parameters ? = {?2, ?4, ?6}. The probability of spontaneous fission has been obtained by dynamical action minimization method.

?ojewski, Z.; Baran, A.

38

Short-lived radionuclides as monitors of early crust-mantle differentiation on the terrestrial planets  

NASA Astrophysics Data System (ADS)

The kinetic energy from large impacts, the gravitational energy released by core formation, and the heat provided by the decay of short-lived radioactive isotopes all drive extensive melting and chemical differentiation of silicate planets/planetesimals during and shortly after their formation. This early differentiation is best preserved on small objects such as the parent bodies of the eucrite and angrite meteorites where silicate melts were produced within 3 million years of solar system formation. The W isotopic composition of some iron meteorites testifies to core segregation on small planetesimals within as little as one million years or less of solar system formation. On larger objects, such as the Moon, Mars and Earth, the evidence for early differentiation provided by long-lived radioisotope systems has been variably overprinted by the continuing differentiation of these objects, but a clear signature of extensive early planet-scale differentiation is preserved in a variety of short-lived radioisotope systems, particularly, I-Pu-Xe, Hf-W and 146Sm- 142Nd. All these systems suggest that global differentiation of planetesimals and the terrestrial planets occurred during the first hundred million years of solar system history. This early processing of the Moon, Mars and Earth, may have fundamentally affected the evolution of these planets and their current internal compositional structure.

Carlson, Richard W.; Boyet, Maud

2009-03-01

39

Beta and Gamma Spectra of Short-Lived Fission Products  

Microsoft Academic Search

Continuous spectra of beta particles and gamma rays emitted in the decay of short-lived fission products have been measured. These spectra, which cover the complete energy range available, can be used for checking results of detailed spectroscopic work on the decay of the nuclides studied. Another application of basic nature is the use of the beta spectra to evaluate the

G. Rudstam; P. I. Johansson; O. Tengblad; P. Aagaard; J. Eriksen

1990-01-01

40

Ultratrace determination of long-lived radioactive isotopes  

NASA Astrophysics Data System (ADS)

A review on the experimental approaches to ultratrace determination of long-lived radioactive isotopes and the broad range of interest of these studies is given. Activities cover a wide variety of fundamental and applied research in the fields of geochemical and environmental studies, cosmochemistry and astrophysics, nuclear and particle physics as well as applications in bio-medical and material sciences. The performances and advantages of Resonance Ionization Mass Spectrometry are worked out and compared to competitive techniques. The history of the high resolution measurements and the present development towards compact, reliable and simplified experimental systems is briefly outlined.

Wendt, K.

1998-12-01

41

Experiments on Controlled Decontamination of Water Mixture of Long-Lived Active Isotopes in Biological Cells  

NASA Astrophysics Data System (ADS)

In this work, the process of direct controlled decontamination of highly active long-lived isotopes by the action of growing microbiological systems has been studied. For the first time the accelerated controlled deactivation of Cs137 isotope was observed.

Vysotskii, Vladimir I.; Odintsov, Alexei; Pavlovich, Vladimir N.; Tashirev, Alexandr B.; Kornilova, Alla A.

2006-02-01

42

Operation of the R2-0 Reactor. Studies of Short-Lived Fission Products by Means of a Isotope-Separator Connected to the R2-0 Reactor. (OSIRIS).  

National Technical Information Service (NTIS)

A short review of the most recent activities at the OSIRIS facility in Studsvik, Sweden. Reports are given by the Nuclear Spectroscopy group and the Nuclear Chemistry Group. (Atomindex citation 09:376882)

G. Rudstam

1977-01-01

43

A Short-lived Metastable State in Titanium46  

Microsoft Academic Search

Benedetti and McGowan1, Mandeville and Scherb2 and Hirzel, Stoll and Wäffler3 have attempted to detect short-lived metastable states of radioactive nuclei by using the method of delayed beta-beta and beta-gamma coincidences. Several decay periods have been detected by these methods. We have examined delayed gamma-gamma coincidences using a method similar to that used by Bunyan et al.4, but with two

B. D. Nag; Sunil Sen; Santimay Chatterjee

1949-01-01

44

Short-lived positron emitter labeled radiotracers - present status  

SciTech Connect

The preparation of labelled compounds is important for the application of positron emission transaxial tomography (PETT) in biomedical sciences. This paper describes problems and progress in the synthesis of short-lived positron emitter (/sup 11/C, /sup 18/F, /sup 13/N) labelled tracers for PETT. Synthesis of labelled sugars, amino acids, and neurotransmitter receptors (pimozide and spiroperidol tagged with /sup 11/C) is discussed in particular. (DLC)

Fowler, J.S.; Wolf, A.P.

1982-01-01

45

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula  

Microsoft Academic Search

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (106 less than or equal to Tau-bar less than or equal to 2 x 107 yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields

G. J. Wasserburg; M. Busso; R. Gallino; C. M. Raiteri

1994-01-01

46

Time-dependence in short-lived volcanic eruption plumes  

NASA Astrophysics Data System (ADS)

Establishing relationships between source conditions and plume evolution is critical for developing accurate, predictive models of volcanic plumes. Such relationships have been derived and successfully applied to field cases for long-duration eruptions with approximately constant source conditions. Similarly useful relationships exist for instantaneous releases. However, equivalent relationships have yet to be developed for time-varying and finite source conditions that drive many short-lived volcanic plumes, despite the fact that such eruptions are frequent in nature. Short-lived plumes have been observed and documented using UV, visible, and IR imaging techniques, as well as satellite and radar measurements. However, the source conditions which generate these plumes are difficult to constrain in the field. Thus, a laboratory investigation of jets and plumes generated by short-duration time-dependent sources was undertaken. Experiments were designed specifically to examine the role of time-dependent source conditions in controlling overall morphology, flow front velocity as a function of time, internal velocity and eddy structure, and entrainment characteristics. In the experimental work presented here, neutrally-buoyant turbulent jets were generated by injecting pressurized water into a tank of still water. Velocity and discharge rate with time were Gaussian-like with durations shorter than jet rise times. Flows had vent Reynolds numbers from 103 to 105 and were documented using flow visualization and particle image velocimetry. Two different flow patterns were observed: isolated vortex rings that separated from a trailing jet and head vortices connected to a trailing stem. The latter was favored as both the vent Reynolds number and the total ejected volume increased. These flows had three main phases of development - an injection phase which occurred while the source was 'on', a transition phase immediately following injection termination, and a final phase during which the flow continued to propagate although the injection had ended. The injection phase was further subdivided into two distinct sub-phases, corresponding to acceleration and deceleration at the vent. Scaling of the results indicate that individual characteristic velocities describe each of the acceleration, deceleration, and transition phases, whereas the final phase behaves like an instantaneous release of momentum, termed a puff. As such, time-dependent source conditions appear to have dominant first-order effects on flow evolution during the injection and transition phases but have little control over the dynamics during the final phase, when instead the total volume injected dominates the dynamics. These results have a number of implications for interpreting dynamics from observations of short-lived volcanic plumes. For example, estimates of vent fluxes from plume observations should be restricted to early 'source on' phases, while later stages of development should provide information about total volume erupted.

Chojnicki, K. N.; Clarke, A. B.; Phillips, J. C.; Adrian, R. J.

2011-12-01

47

Very short-lived Substances as Sources for Stratospheric Bromine  

NASA Astrophysics Data System (ADS)

Halogen-containing gases, when transported into the stratosphere, release chlorine and bromine atoms, which can lead to the destruction of ozone by catalytic cycles. Long-lived anthropogenic source gases like chlorofluorocarbons (CFCs), chlorocarbons, methyl bromide (CH3Br, also with natural sources) and halons are the most important sources for stratospheric halogen. While the budget of stratospheric chlorine is relatively well understood, greater uncertainties are present in terms of quantity and attribution of stratospheric bromine. BrO measurements in the stratosphere indicate abundances of inorganic bromine Bry that cannot be explained by the contribution from the long-lived halons and methyl bromide only. Additional input is expected to be provided by natural very-short-lived substances (VSLS), inorganic product gases and bromine tied to aerosols. We present measurements of all important brominated source gases, including the five most abundant VSLS, in the tropical tropopause layer (TTL) from balloon-borne air samples collected in June 2008 in Teresina (Brazil). The results were used to derive a local budget of organic bromine, which is revealing a considerable contribution from VSLS. We discuss variabilities in the concentrations of VSLS species both in the TTL and in the tropical marine boundary layer to assess the significance of our measurements on a global scale.

Brinckmann, Sven; Engel, Andreas; Bönisch, Harald

2010-05-01

48

Collateral consequences of the inhomogeneous distribution of short-lived radionuclides in the solar nebula  

NASA Astrophysics Data System (ADS)

The presence of several short-lived (now extinct) radionuclides in the early solar system demands that they were synthesized and added to preexisting solar system materials shortly (on a time scale of the order of the relevant radionuclide lifetime) before formation of solar system solids. For diverse reasons it is often suggested that the solar system distributions of these radionuclides were radically heterogeneous, perhaps because of the late addition. Much attention has been given to the astrophysical circumstances that might govern the synthesis and distribution of these short-lived radionuclides, but comparatively little attention has been devoted to the distribution of co-synthesized isotopes. The focus of this paper is a systematic, quantitative evaluation of the collateral consequences in stable and long-lived isotopes which might be expected if short-lived radionuclides, in particular 26Al or 53Mn, were injected at their canonical levels and inhomogeneously distributed in the early solar system. We mix model massive star yields of Meyer et al. (1995) and Woosley and Weaver (1995) into a reservoir of cosmic composition, as tabulated by Anders and Grevesse (1989). To mitigate the effects of systematic deviations that may be present in these mixtures due to uncertainties in model stellar yields, we follow Timmes and Clayton (1996) and also mix into a "renormalized" proxy solar system composition computed from a galactic chemical evolution model based primarily on the stellar yields of Woosley and Weaver (1995). The results are very unfavorable to the likelihood of heterogeneously distributed 26Al derived from supernova ejecta. If a massive star is invoked to account for 26Al, its ejecta must have been rather uniformly distributed, as inferred from the lack of measured collateral anomalies in several elements, notably Ca, Cr and Ni. Conversely, if 26Al were indeed radically heterogeneously distributed, some other nucleosynthetic source, more efficient at producing 26Al, is required. In principle, a similar statement applies to 53Mn, but the situation is more complicated. The inferred anomalies at 53Cr will depend not only on how much 53Mn is added by a heterogeneous component, but also more sensitively on the contributions to the associated stable nuclides, 53Cr, 52Cr and 50Cr. Consideration of predicted collateral anomalies provides no direct support for heterogeneously-distributed supernova-derived 53Mn, but the required quantity of supernova contribution, and thus also the collateral anomalies, are much less for 53Mn than for 26Al. With allowance for model calculation uncertainties, it could be argued that anomalies collateral to heterogeneous 53Mn might be small enough to have evaded detection.

Nichols, Robert H., Jr.; Podosek, Frank A.; Meyer, Brad S.; Jennings, Cristine L.

1999-11-01

49

Spectroscopy of Short-Lived Fission Fragment Isomers  

NASA Astrophysics Data System (ADS)

Fission is a well-known mechanism to populate excited states in neutron-rich isotopes. Fission is also an effective tool for studying isomeric decays, as they are often well-populated and relatively easy to detect. Isomeric states with half-lives in the ˜5 -- 100 ?s range were examined using ^6Li-induced fission on ^232Th. A 45-MeV ^6Li beam from the 88-Inch Cyclotron of LBNL was alternately blocked to provide beam on/off periods to populate and observe the isomeric decays. Fission fragments were tagged using a thin Si detector near the ^232Th target, and coincident gamma rays were detected using six clover and one LEPS HPGe detectors of the LiBerACE array. Several isomers were identified in the A˜95 and A˜140 mass regions, as expected. Numerous isomers were also observed near A˜120, due to the significant contribution from symmetric fission. Characteristics of the induced fission, with observed isomer populations and decays, will be discussed.

Ressler, J. J.; Francy, C. F.; Caggiano, J. A.; Jordan, D. V.; Peplowski, P.; Warren, G. A.

2009-10-01

50

Electron Scattering off Short-Lived Radioactive Nuclei  

NASA Astrophysics Data System (ADS)

We have established a novel method which make electron scattering off short-lived radioactive nuclei come into being. This novel method was named SCRIT (Self-Confining RI ion Target). It was based on the well known "ion trapping" phenomenon in electron storage rings. Stable nucleus, 133Cs, was used as target nucleus in the R&D experiment. The luminosity of interaction between stored electrons and Cs ions was about 1.02(0.06) × 1026 cm-2s-1 at beam current around 80 mA. The angular distribution of elastically scattered electrons from trapped Cs ions was measured. And an online luminosity monitor was used to monitor the change of luminosity during the experiment.

Wang, S.; Emoto, T.; Furukawa, Y.; Ishii, K.; Ito, S.; Koseki, T.; Kurita, K.; Kuwajima, A.; Masuda, T.; Morikawa, A.; Nakamura, M.; Noda, A.; Ohnishi, T.; Shirai, T.; Suda, T.; Takeda, H.; Tamae, T.; Tongu, H.; Wakasugi, M.; Yano, Y.

51

Nondispersive x-ray diagnostics of short lived plasmas  

SciTech Connect

In this NATO Advanced Study Institute, we have discussed in detail the diagnosis of many pulse power machine properties, including their electrical behavior, grounding and shielding, and related data acquisition techniques. The purpose for many of these machines is to create high temperature/high density plasmas and, therefore, the subsequent behavior of these plasmas is of critical concern. The energy density of these plasmas is such that they will naturally radiate in the x-ray regime and thus the diagnosis of their x-ray emission is a crucial measurement of the entire system performance. In this lecture, I describe the general techniques used to perform nondispersive x-ray diagnostics of these short lived plasmas.

Day, R.H.

1983-01-01

52

Senescence Is More Important in the Natural Lives of Long- Than Short-Lived Mammals  

PubMed Central

Background Senescence has been widely detected among mammals, but its importance to fitness in wild populations remains controversial. According to evolutionary theories, senescence occurs at an age when selection is relatively weak, which in mammals can be predicted by adult survival rates. However, a recent analysis of senescence rates found more age-dependent mortalities in natural populations of longer lived mammal species. This has important implications to ageing research and for understanding the ecological relevance of senescence, yet so far these have not been widely appreciated. We re-address this question by comparing the mean and maximum life span of 125 mammal species. Specifically, we test the hypothesis that senescence occurs at a younger age relative to the mean natural life span in longer lived species. Methodology/Principal Findings We show, using phylogenetically-informed generalised least squares models, a significant log-log relationship between mean life span, as calculated from estimates of adult survival for natural populations, and maximum recorded life span among mammals (R2?=?0.57, p<0.0001). This provides further support for a key prediction of evolutionary theories of ageing. The slope of this relationship (0.353±0.052 s.e.m.), however, indicated that mammals with higher survival rates have a mean life span representing a greater fraction of their potential maximum life span: the ratio of maximum to mean life span decreased significantly from >10 in short-lived to ?1.5 in long-lived mammal species. Conclusions/Significance We interpret the ratio of maximum to mean life span to be an index of the likelihood an individual will experience senescence, which largely determines maximum life span. Our results suggest that senescence occurs at an earlier age relative to the mean life span, and therefore is experienced by more individuals and remains under selection pressure, in long- compared to short-lived mammals. A minimum rate of somatic degradation may ultimately limit the natural life span of mammals. Our results also indicate that senescence and modulating factors like oxidative stress are increasingly important to the fitness of longer lived mammals (and vice versa).

Turbill, Christopher; Ruf, Thomas

2010-01-01

53

Short-lived Be and Be In Refractory Inclusions From 7 10  

NASA Astrophysics Data System (ADS)

The source of 26Al [1] and other short-lived radioactive nuclides (e.g. 41Ca or 53Mn) found in Ca-Al-rich refractory inclusions (CAIs) of chondritic meteorites is still controversial between the tenants of an external seeding of the protosolar nebula (e.g. by supernova produced Al) and the tenants of an internal source of 26 26Al within the solar system (e.g. by irradiation processes occurring in the vicinity of the young Sun). The resolution of this issue is of importance for (i) early solar system chronology and for (ii) models of the formation of the solar system. Recently we showed that 10Be, which decays to B with a half-life of 1.5 My, was 10 also incorporated in CAIs during their formation [2]. The incorporation of 10 Be in CAIs is a strong hint for the existence of irradiation processes that may have occurred in the early solar system, producing 10Be and a fraction (or all) of other extinct radioactive nuclides. However, because of its long half life, 10Be could have been produced by spallation reactions taking place in supernovae envelopes and transported into the protosolar nebula. To progress in this debate we have looked for traces of another short-lived isotope of Be, Be which decays to Li 7 7 with a half life of 53 days. Large Li isotopic variations have been found in a few Allende CAIs, with 7Li excesses positively correlated to Be/Li concentration ratios. These observations are best explained by the incorporation of lived Be in 7 CAIs during their formation. The Be/10Be ratio which is deduced for CAIs is of 7 220+/-130, i.e. close within errors to the production ratio modelled for irradiation processes at low energy around the young Sun. Because of its very short half life of 53 days, the presence of Be in CAIs demonstrates that Be (and 7 7 10Be) were produced within the solar system. It is also a strong indication that the formation of CAIs was likely linked in space and time to these irradiation processes. [1] T. Lee, D. Papanastassiou and G. J. Wasserburg (1976) Geophys. Res. Lett., 3, 109-112. [2] K. D. McKeegan, M. Chaussidon, F. Robert (2000) Science 289, 1334-1347.

Allende Meteorite, The

54

Constraints on the Origin of Chondrules and CAIs from Short-Lived and Long-Lived Radionuclides  

SciTech Connect

The high time resolution Pb-Pb ages and short-lived nuclide based relative ages for CAIs and chondrules are reviewed. The solar system started at 4567.2 {+-} 0.6Ma inferred from the high precision Pb-Pb ages of CAIs. Time scales of CAIs ({le}0.1Myr), chondrules (1-3Myr), and early asteroidal differentiation ({ge}3Myr) inferred from {sup 26}Al relative ages are comparable to the time scale estimated from astronomical observations of young star; proto star, classical T Tauri star and week-lined T Tauri star, respectively. Pb-Pb ages of chondrules also indicate chondrule formation occur within 1-3 Myr after CAIs. Mn-Cr isochron ages of chondrules are similar to or within 2 Myr after CAI formation. Chondrules from different classes of chondrites show the same range of {sup 26}Al ages in spite of their different oxygen isotopes, indicating that chondrule formed in the localized environment. The {sup 26}Al ages of chondrules in each chondrite class show a hint of correlation with their chemical compositions, which implies the process of elemental fractionation during chondrule formation events.

Kita, N T; Huss, G R; Tachibana, S; Amelin, Y; Nyquist, L E; Hutcheon, I D

2005-10-24

55

Short telomeres in short-lived males: what are the molecular and evolutionary causes?  

PubMed

Telomere length regulation is an important aspect of cell maintenance in eukaryotes, since shortened telomeres can lead to a number of defects, including impaired cell division. Although telomere length is correlated with lifespan in some bird species, its possible role in aging and lifespan determination is still poorly understood. Here we investigate telomere dynamics (changes in telomere length and attrition rate) and telomerase activity in the ant Lasius niger, a species in which different groups of individuals have evolved extraordinarily different lifespans. We found that somatic tissues of the short-lived males had dramatically shorter telomeres than those of the much longer-lived queens and workers. These differences were established early during larval development, most likely through faster telomere shortening in males compared with females. Workers did not, however, have shorter telomeres than the longer-lived queens. We discuss various molecular mechanisms that are likely to cause the observed sex-specific telomere dynamics in ants, including cell division, oxidative stress and telomerase activity. In addition, we discuss the evolutionary causes of such patterns in ants and in other species. PMID:17346255

Jemielity, Stephanie; Kimura, Masayuki; Parker, Karen M; Parker, Joel D; Cao, Xiaojian; Aviv, Abraham; Keller, Laurent

2007-03-07

56

Yields of short-lived fission products produced following 235U(nth,f)  

NASA Astrophysics Data System (ADS)

Measurements of gamma-ray spectra, following the thermal neutron fission of 235U have been made using a high purity germanium detector at the University of Massachusetts Lowell (UML) Van de Graaff facility. The gamma spectra were measured at delay times ranging from 0.2 s to nearly 10 000 s following the rapid transfer of the fission fragments with a helium-jet system. On the basis of the known gamma transitions, forty isotopes have been identified and studied. By measuring the relative intensities of these transitions, the relative yields of the various precursor nuclides have been calculated. The results are compared with the recommended values listed in the ENDF/B-VI fission product data base (for the lifetimes and the relative yields) and those published in the Nuclear Data Sheets (for the beta branching ratios). This information is particularly useful for the cases of short-lived fission products with lifetimes of the order of fractions of a second or a few seconds. Independent yields of many of these isotopes have rather large uncertainties, some of which have been reduced by the present study.

Tipnis, S. V.; Campbell, J. M.; Couchell, G. P.; Li, S.; Nguyen, H. V.; Pullen, D. J.; Schier, W. A.; Seabury, E. H.; England, T. R.

1998-08-01

57

High-purity isotope production by short-term HFIR irradiations  

Microsoft Academic Search

Techniques and procedures have been developed at the transuranium processing plant to produce quantities of special high-purity isotopes, e.g. ²²⁷Ac, ²⁴²Cm, ²⁵°Cf, ²⁵¹Cf, and ²⁵⁴Cf by short-term irradiation of appropriate target materials in the high flux isotope reactor (HFIR). The general sequences of operations required to produce special isotopes includes (a) purification of the target isotope from other actinides, lanthanides,

J. B. Jr. Knauer; C. W. Alexander; J. E. Bigelow; J. T. Wiggins

1987-01-01

58

Cross Sections Needed for the Interpretation of Long-Lived and Short-Lived Cosmogenic Nuclide Production in Extraterrestrial Materials  

Microsoft Academic Search

Radionuclides produced by cosmic rays in extraterrestrial materials archive information that can be used to determine cosmic-ray fluxes and to study the history of the irradiated object. Long-lived radionuclides give information about the last ~5 Myr; short-lived radionuclides give information about recent events. To calculate the solar cosmic ray (SCR) flux from measured depth profiles for cosmogenic radionuclides produced in

J. M. Sisterson; A. Beverding; K. J. Kim; P. A. J. Englert; A. J. T. Jull; D. J. Donahue; S. Cloudt; C. Castaneda; J. Vincent; M. W. Caffee; C. O. Osazuwa; R. C. Reedy

1995-01-01

59

Long lived isotopes in the Chernobyl radioactive cloud at Cracow  

Microsoft Academic Search

The analysis of the residual -radioactivity in the air filters exposed during the passage of the Chernobyl radioactive could over Cracow area gave data on variation in time of the relative contribution of long lived radioisotopes. Conclusions on transport properties of some elements are deduced from the obtained results.

J. W. Mietelski; R. Broda; J. Sieniawski

1988-01-01

60

Short-lived and long-lived dust devil tracks in the coastal desert of southern Peru  

NASA Astrophysics Data System (ADS)

In the coastal desert of southern Peru, sequential high-resolution satellite images document the presence of short-lived and long-lived dust devil tracks. Dust devil tracks in the study region remain visible for less than 6 months in one area and for more than 4 years in another area. Short-lived tracks are generally darker than the surrounding ground surface. The brightness of long-lived tracks is often equal to that of their surroundings; they become visible due to a brighter edge along their margins. Different modes of formation related to ground surface properties are suggested to explain the differences in persistence and appearance. Dark, short-lived dust devil tracks are ascribed to the removal of silt-sized material from largely sand-sized surface materials. Long-lived tracks with bright margins are ascribed to coarser surface materials and the fallout of sand-sized particles along the track edges. Locating suitable areas on Earth for the study of dust devil tracks and distinguishing between different types of dust devil tracks is expected to further promote terrestrial analogue studies for Martian dust devil streaks.

Hesse, Ralf

2012-08-01

61

Harvard-MIT research program in short-lived radiopharmaceuticals. Final report.  

National Technical Information Service (NTIS)

The Harvard-MIT Research Program in Short-lived Radiopharmaceuticals was established in 1977 to foster interaction among groups working in radiopharmaceutical chemistry at Harvard Medical School, the Massachusetts Institute of Technology, and the Massachu...

S. J. Adelstein

1995-01-01

62

Strategic Trading of Informed Trader with Monopoly on Short and Long-Lived Information  

Microsoft Academic Search

In his seminal paper, Kyle (1985) analyzed a market model with an informed trader who has monopoly on long-lived information. We consider a market with the same participants as in Kyle's, but where the informed trader has monopoly on two types of information, long-lived one and short-lived one. A necessary and sufficient condition for a market equilibrium in the form

Chanwoo Noh; Sungsub Choi

2009-01-01

63

Short-lived isomers in {sup 94}Rb  

SciTech Connect

The medium-spin structure of the neutron-rich, odd-odd nucleus {sup 94}Rb was studied by means of {gamma}-ray spectroscopy. Excited levels were populated in the neutron-induced fission of {sup 235}U and in the spontaneous fission of {sup 252}Cf and {sup 248}Cm. Two isomeric states were found at 1485.2 and 2074.8 keV with half-lives of 18 and 107 ns, respectively. The probable structures of the two isomers involve the fully aligned, proton-neutron configurations [{pi}(g{sub 9/2}) x {nu}(g{sub 7/2})]{sub 8{sup +}} and [{pi}(g{sub 9/2}) x {nu}(h{sub 11/2})]{sub 10{sup -}}, respectively. These new data give information on the single-particle energies in the region.

Tsekhanovich, I.; Dare, J. A.; Smith, A. G.; Varley, B. J. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Simpson, G. S. [Laboratoire de Physique Subatomique et de Cosmologie, F-38026 Grenoble (France); Urban, W.; Soldner, T. [Institut Laue-Langevin, 6 rue J. Horowitz, F-38042 Grenoble (France); Jolie, J.; Linnemann, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln (Germany); Orlandi, R.; Smith, J. F. [University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Scherillo, A. [Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Rzaca-Urban, T.; Zlomaniec, A. [Faculty of Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw (Poland); Dorvaux, O.; Gall, B. J. P.; Roux, B. [Institut de Recherches Subatomiques, CNRS-IN2P3, F-67037 Strasbourg (France)

2008-07-15

64

Search for long-lived isomeric states in neutron-deficient thorium isotopes  

SciTech Connect

The discovery of naturally occurring long-lived isomeric states (t{sub 1/2}>10{sup 8} yr) in the neutron-deficient isotopes {sup 211,213,217,218}Th[A. Marinov et al., Phys. Rev. C 76, 021303(R) (2007)] was reexamined using accelerator mass spectrometry (AMS). Because AMS does not suffer from molecular isobaric background in the detection system, it is an extremely sensitive technique. Despite our up to two orders of magnitude higher sensitivity we cannot confirm the discoveries of neutron-deficient thorium isotopes and provide upper limits for their abundances.

Lachner, J.; Dillmann, I.; Faestermann, T.; Korschinek, G.; Poutivtsev, M.; Rugel, G. [Physik Department E12 and E15, Technische Universitaet Muenchen, D-85748 Garching (Germany)

2008-12-15

65

Search for long-lived isomeric states in neutron-deficient thorium isotopes  

NASA Astrophysics Data System (ADS)

The discovery of naturally occurring long-lived isomeric states (t1/2>108 yr) in the neutron-deficient isotopes Th211,213,217,218 [A. Marinov , Phys. Rev. C 76, 021303(R) (2007)] was reexamined using accelerator mass spectrometry (AMS). Because AMS does not suffer from molecular isobaric background in the detection system, it is an extremely sensitive technique. Despite our up to two orders of magnitude higher sensitivity we cannot confirm the discoveries of neutron-deficient thorium isotopes and provide upper limits for their abundances.

Lachner, J.; Dillmann, I.; Faestermann, T.; Korschinek, G.; Poutivtsev, M.; Rugel, G.

2008-12-01

66

Short-lived radioactivity in the early solar system: The Super-AGB star hypothesis  

NASA Astrophysics Data System (ADS)

The composition of the most primitive solar system condensates, such as calcium-aluminum-rich inclusions (CAIs) and micron-sized corundum grains, show that short-lived radionuclides (SLR), e.g., 26Al, were present in the early solar system. Their abundances require a local or stellar origin, which, however, is far from being understood. We present for the first time the abundances of several SLR up to 60Fe predicted from stars with initial mass in the range approximately 7-11 M?. These stars evolve through core H, He, and C burning. After core C burning they go through a "Super"-asymptotic giant branch (Super-AGB) phase, with the H and He shells activated alternately, episodic thermal pulses in the He shell, a very hot temperature at the base of the convective envelope (approximately 108 K), and strong stellar winds driving the H-rich envelope into the surrounding interstellar medium. The final remnants of the evolution of Super-AGB stars are mostly O-Ne white dwarfs. Our Super-AGB models produce 26Al/27Al yield ratios approximately 0.02-0.26. These models can account for the canonical value of the 26Al/27Al ratio using dilutions with the solar nebula of the order of 1 part of Super-AGB mass per several 102 to several 103 of solar nebula mass, resulting in associated changes in the O-isotope composition in the range ?17O from 3 to 20‰. This is in agreement with observations of the O isotopic ratios in primitive solar system condensates, which do not carry the signature of a stellar polluter. The radionuclides 41Ca and 60Fe are produced by neutron captures in Super-AGB stars and their meteoritic abundances are also matched by some of our models, depending on the nuclear and stellar physics uncertainties as well as the meteoritic experimental data. We also expect and are currently investigating Super-AGB production of SLR heavier than iron, such as 107Pd.

Lugaro, Maria; Doherty, Carolyn L.; Karakas, Amanda I.; Maddison, Sarah T.; Liffman, Kurt; García-Hernández, D. A.; Siess, Lionel; Lattanzio, John C.

2012-12-01

67

Senescence Is More Important in the Natural Lives of Long Than Short-Lived Mammals  

Microsoft Academic Search

BackgroundSenescence has been widely detected among mammals, but its importance to fitness in wild populations remains controversial. According to evolutionary theories, senescence occurs at an age when selection is relatively weak, which in mammals can be predicted by adult survival rates. However, a recent analysis of senescence rates found more age-dependent mortalities in natural populations of longer lived mammal species.

Christopher Turbill; Thomas Ruf

2010-01-01

68

Relatively Long-Lived Dubnium Isotopes and Chemical Identification of Superheavy Elements  

SciTech Connect

The present study has been performed within the framework of experiments aimed at the investigation of chemical properties of long-lived Db isotopes in aqueous solutions. The isocratic anion exchange separations of group V elements in the solutions containing HF have been considered. Parameters of separation of dubnium homologues (Pa, Nb and Ta) in HF/HNO{sub 3} mixed solutions have been optimized. The procedure of separation of group V elements from multicomponent system has been suggested.

Tereshatov, E. E.; Voronyuk, M. G.; Starodub, G. Ya.; Petrushkin, O. V.; Dmitriev, S. N. [Flerov Laboratory of Nuclear Reactions (FLNR), JINR, Dubna RU-141980 (Russian Federation); Bruchertseifer, H. [Paul Scherrer Institute (PSI), Villigen CH-5232 (Switzerland)

2010-04-30

69

Cooling of short-lived, radioactive, highly charged ions with the TITAN cooler Penning trap. Status and perspectives  

NASA Astrophysics Data System (ADS)

TITAN is an on-line facility dedicated to precision experiments with short-lived radioactive isotopes, in particular mass measurements. The achievable resolution on mass measurement, which depends on the excitation time, is limited by the half life of the radioactive ion. One way to bypass this is by increasing the charge state of the ion of interest. TITAN has the unique capability of charge-breeding radioactive ions using an electron-beam ion trap (EBIT) in combination with Penning trap mass spectrometry. However, the breeding process leads to an increase in energy spread, ? E, which in turn negatively influences the mass uncertainty. We report on the development of a cooler Penning trap which aims at reducing the energy spread of the highly charged ions prior to injection into the precision mass measurement trap. Electron and proton cooling will be tested as possible routes. Mass selective cooling techniques are also envisioned.

Simon, V. V.; Delheij, P.; Dilling, J.; Ke, Z.; Shi, W.; Gwinner, G.

2011-07-01

70

Storm time, short-lived bursts of relativistic electron precipitation detected by subionospheric radio wave propagation  

Microsoft Academic Search

In this study we report on ground-based observations of short bursts of relativistic electron precipitation (REP), detected by a subionospheric propagation sensor in Sodankylä, Finland during 2005. In two ~4 hour case study periods from L = 5.2, around local midnight, several hundred short-lived radio wave perturbations were observed, covering a wide range of arrival azimuths. The vast majority (~99%)

Craig J. Rodger; Mark A. Clilverd; David Nunn; Pekka T. Verronen; Jacob Bortnik; Esa Turunen

2007-01-01

71

An Automatic GLPC Apparatus for the Analysis of Organic Compounds Labeled with Short-Lived Radioisotopes  

Microsoft Academic Search

A combined gas-liquid chromatograph, effluent counter, effluent flow-meter, and automatic data collection device is described which can be used for the analysis and assay of gas mixtures containing isotopes of short half-life. The data are collected in a form compatible for computer correction and evaluation. An example using C-containing compounds is given. The device is useful for research with organic

M. J. Welch; R. Withnell; A. P. Wolf

1969-01-01

72

New Half-lives of r-process Zn and Ga Isotopes Measured with Electromagnetic Separation  

NASA Astrophysics Data System (ADS)

The ? decays of neutron-rich nuclei near the doubly magic Ni78 were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of Zn82 (228±10ms), Zn83 (117±20ms), and Ga85 (93±7ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the Ni78 region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A>140 nuclei.

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

2012-09-01

73

New half-lives of r-process Zn and Ga isotopes measured with electromagnetic separation.  

PubMed

The ? decays of neutron-rich nuclei near the doubly magic (78)Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of (82)Zn (228±10??ms), (83)Zn (117±20??ms), and (85)Ga (93±7??ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the (78)Ni region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A>140 nuclei. PMID:23005622

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

2012-09-13

74

Method for net decrease of hazardous radioactive nuclear waste materials. [Thermal neutron irradiation of long-lived radionuclides to produce stable nuclides and short-lived radionuclides  

SciTech Connect

A method of decreasing the amount of relatively long lived fission products in radioactive waste materials in excess of that due to their natural radioactive decay by producing relatively short lived radioactive nuclides and stable nuclides from the relatively long lived fission products is described comprising the steps of: (a) separating the fission products into at least (1) physically separate groups, and (2) relatively short lived fission product radioactive nuclides and stable nuclides; (b) storing the relatively short lived radioactive nuclides and stable nuclides; (c) exposing at least the groups containing Kr/sup 85/, Sr/sup 90/, Zr/sup 93/, Tc/sup 99/, Pd/sup 107/, I/sup 129/, Cs/sup 135/, Sm/sup 151/ + Eu, and actinides, to a high thermal neutron flux for separate, different predetermined periods of time selected in accordance with the long lived fission product nuclide in the corresponding group for inducing predetermined transformations of the relatively long lived fission product nuclides to produce relatively short lived radioactive nuclides and stable nuclides; (d) removing each exposed group containing the produced relatively short lived radioactive nuclides and stable nuclides from the high thermal neutron flux; (e) separating the removed group into (1) the produced short lived radioactive nuclides and stable nuclides, and (2) a plurality of further groups having long lived fission product nuclides respectively corresponding to at least some of the long lived fission product nuclides or the groups of step (a); (f) storing the produced short lived radioactive nuclides and stable nuclides; (g) joining at least one of the further groups to at least one of the groups of step (a) having a corresponding long lived fission product nuclide.

Marriott, R.; Henyey, F.S.; Hochstim, A.R.

1988-01-26

75

Can There Be Short-Period Deterministic Cycles When People Are Long Lived.  

National Technical Information Service (NTIS)

This paper considers whether short-period deterministic cycles can exist in a class of stationary overlapping generations models with long- (but finite-) lived agents. It shows that if agents discount the future positively, then as life spans get large, n...

S. R. Aiyagari

1988-01-01

76

The evolution from birth to decay of a short-lived active region  

Microsoft Academic Search

In the following paper we present results of the analysis of NOAA active region 7968, which was the target of a coordinated observing campaign involving the instruments aboard the Solar and Heliospheric Observatory (SOHO), Yohkoh, and ground-based observatories (Bialków, Pic du Midi, and Huairou). This active region was relatively short-lived, and thus provides a rare example of a region observed

Yuan Yong Deng; Brigitte Schmieder; Cristina H. Mandrini; Josef I. Khan; Pascal Démoulin; Pawel Rudawy

1999-01-01

77

Synthesis of radiopharmaceuticals containing short-lived radionuclides. Progress report, March 1, 1985-February 26, 1986  

SciTech Connect

Methods for the rapid introduction of short-lived radionuclides into agents for use in diagnostic nuclear medicine are reported. Methods to synthesize radioiodinated fatty acids, lipids, and amphetamine derivatives are described. New routes for the introduction of bromine-77, chlorine-34m, and carbon-11 into agents of interest are elaborated. 46 refs.

Kabalka, G.W.

1985-09-01

78

Synthesis of radiopharmaceuticals containing short-lived radionuclides. Comprehensive report, March 1, 1980-February 26, 1986  

SciTech Connect

New methods for the rapid introduction of short-lived radionuclides into agents for use in diagnostic nuclear medicine are reported. Among the new syntheses reported are those for /sup 123/I-labeled fatty acids and steroids, for /sup 11/C-labeled alcohols, for /sup 13/N-labeled amines, and for /sup 15/O-labeled alcohols. 33 refs.

Kabalka, G.W.

1985-09-01

79

Diffusion Experiment By Using The Short-Lived Radiotracer Of 8Li  

NASA Astrophysics Data System (ADS)

For an interdisciplinary application of the short-lived radioactive ion beams available at TRIAC, a non-destructive on-line radiotracer method for diffusion studies in solids has been developed. The experimental method using the ?-emitting radioisotope of 8Li as the Li diffusion tracer in solids is introduced. The overview of the TRIAC, presently being operational for experiments, is briefly presented.

Jeong, S. C.

2006-11-01

80

On non-thermal nucleosynthesis of Short-Lived Radionuclei in the early solar system  

Microsoft Academic Search

The first results from the STARDUST mission revealed that refractory phases formed at a close distance from the nascent Sun have been transported to the comet forming region. Such refractory phases from meteorites (that originate from the asteroid belt), hold the ashes of Short-Lived Radionuclei (SLR) that were alive in the early solar system (ESS). We show that global energetic

Jean Duprat; Vincent Tatischeff

2008-01-01

81

Evidence for Short-Lived ^32Si in Presolar SiC grains of Type C  

NASA Astrophysics Data System (ADS)

Presolar SiC grains of type C have large ^29Si and ^30Si excesses as well as ^32S excesses. We propose that these ^32S excesses originate from the decay of short-lived ^32Si produced by high neutron densities (neutron burst) in core-collapse supernovae.

Zinner, E.; Hoppe, P.; Pignatari, M.

2013-09-01

82

ORGANIC RADIOPHARMACEUTICALS LABELED • WITH ISOTOPES OF SHORT HALF-LIFE I: “C-l-DOPAMINE HYDROCHLORIDE  

Microsoft Academic Search

The preparation of isotopically labeled pharma ceutical and diagnostic agents has seen an almost exponential growth in recent years. The majority of labeled materials available are inorganic compounds or high-molecular-weight organic substances con taiiing a chemisorbed or otherwise bound radioac tive isotope. Essentially all of the commercially available isotopes have half-lives of 6 hr or more. It is our intention

D. R. Christman; P. Wolf

83

Cooling of highly-charged, short-lived ions for precision mass spectrometry at TRIUMF's Ion Trap for Atomic and Nuclear Science  

NASA Astrophysics Data System (ADS)

At TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN), masses of short-lived nuclides are measured accurately and precisely using Penning trap mass spectrometry. The achievable precision is primarily limited by the radioactive lifetime of the nuclides. To boost the precision TITAN has demonstrated that short-lived isotopes can be charge-bred to higher charge states within 10-100 s of ms using an electron beam ion trap. The charge breeding process increases the energy spread of the ions, which in turn affects the precision and the efficiency. A novel cooler Penning trap (CPET) has been developed to trap and cool highly-charged ions using electrons prior to the precision measurement. A discussion of electron cooling and the current status of CPET will be given.

Schultz, B. E.; Chowdhury, U.; Simon, V. V.; Andreoiu, C.; Chaudhuri, A.; Gallant, A. T.; Kwiatkowski, A. A.; Macdonald, T. D.; Simon, M. C.; Dilling, J.; Gwinner, G.

2013-09-01

84

Analyses of new short-lived replacements for HFCs with large GWPs  

NASA Astrophysics Data System (ADS)

this study, we examine the atmospheric lifetimes and Global Warming Potentials (GWPs) for six short-lived potential ozone-depleting substances and high-GWP hydrofluorocarbons (HFCs) replacement compounds and evaluate the potential reduced effects on climate forcing from adopting such compounds. We also examine the potential effects on climate from widespread use of these chemicals. The atmospheric lifetimes of these compounds are each less than 1 month and their 100 year GWPs range from 0.9 to 4.6. The derived GWPs are substantially lower than those in prior published studies, which used simplified estimation techniques that overestimate the GWPs for these short-lived compounds by 61% to 237%. If long-lived HFCs are completely replaced with these substitute compounds, radiative forcing of these short-lived compounds in 2050 will be 0.26 to 0.80 mW m-2, a factor of as much as 1000 smaller than would be the case with the potential growth in the use of the HFCs.

Wuebbles, Donald J.; Wang, Dong; Patten, Kenneth O.; Olsen, Seth C.

2013-09-01

85

Phase-Imaging Ion-Cyclotron-Resonance Measurements for Short-Lived Nuclides  

NASA Astrophysics Data System (ADS)

A novel approach based on the projection of the Penning-trap ion motion onto a position-sensitive detector opens the door to very accurate mass measurements on the ppb level even for short-lived nuclides with half-lives well below a second. In addition to the accuracy boost, the new method provides a superior resolving power by which low-lying isomeric states with excitation energy on the 10-keV level can be easily separated from the ground state. A measurement of the mass difference of Xe130 and Xe129 has demonstrated the great potential of the new approach.

Eliseev, S.; Blaum, K.; Block, M.; Droese, C.; Goncharov, M.; Minaya Ramirez, E.; Nesterenko, D. A.; Novikov, Yu. N.; Schweikhard, L.

2013-02-01

86

Properties of short-living ball lightning produced in the laboratory  

NASA Astrophysics Data System (ADS)

An experimental setup for highly reproducible generation of artificial ball lightnings is implemented. Thousands of floating glowing plasmoids 12-20 cm in diameter are produced. Research facilities for studying the plasmoids are developed. It is found that short-lived ball lightnings live for about 1 s and carry an electric charge. The lightnings are shown to have a complex structure: a central kernel containing a rich variety of hydrated ions and aerosol of decay products is surrounded by a thin negatively charged shell.

Egorov, A. I.; Stepanov, S. I.

2008-06-01

87

Compton suppression spectrometry for analysis of short-lived neutron activation products in foods  

Microsoft Academic Search

Compton suppression spectrometry was used to analyze foods for elements with short-lived neutron activation products (half-lives\\u000a of about 2 minutes to 1.5 days). Analysis conditions were optimized to provide quality assurance analyses for iodine in FDA’s\\u000a Total Diet Study. Iodine mass fractions (0.075 to 2.03 mg\\/kg) were measured in 19 of 42 foods analyzed, with limits of detection\\u000a (LODs) ranging

D. L. Anderson; W. C. Cunningham

2008-01-01

88

First results using a new technology for measuring masses of very short-lived nuclides with very high accuracy: The MISTRAL program at ISOLDE  

SciTech Connect

MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na, Mg, Al, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

Monsanglant, C.; Audi, G.; Conreur, G.; Cousin, R.; Doubre, H.; Jacotin, M.; Henry, S.; Kepinski, J.-F.; Lunney, D.; Saint Simon, M. de; Thibault, C. [CSNSM-IN2P3-CNRS bat 108, F-91405 Orsay-campus (France); Toader, C. [CSNSM-IN2P3-CNRS bat 108, F-91405 Orsay-campus (France); Inst. Atomic Physics, Bucharest (Romania); Bollen, G.; Lebee, G.; Scheidenberger, C. [CERN, EP Division, Geneva (Switzerland); Borcea, C.; Duma, M. [Inst. Atomic Physics, Bucharest (Romania); Kluge, H.-J. [GSI, D-64291 Darmstadt (Germany); Le Scornet, G. [CSNSM-IN2P3-CNRS bat 108, F-91405 Orsay-campus (France); CERN, EP Division, Geneva (Switzerland)

1999-11-16

89

Cross Sections Needed for the Interpretation of Long-Lived and Short-Lived Cosmogenic Nuclide Production in Extraterrestrial Materials  

NASA Astrophysics Data System (ADS)

Radionuclides produced by cosmic rays in extraterrestrial materials archive information that can be used to determine cosmic-ray fluxes and to study the history of the irradiated object. Long-lived radionuclides give information about the last ~5 Myr; short-lived radionuclides give information about recent events. To calculate the solar cosmic ray (SCR) flux from measured depth profiles for cosmogenic radionuclides produced in lunar rocks, accurate and precise cross section values for the production of these radionuclides from all relevant elements are needed. About 98% of SCR and ~87% of galactic cosmic rays (GCR) falling on extraterrestrial materials are protons. Cross section measurements were made using three proton accelerators to cover the energy range ~20 - 500 MeV. Thin target techniques used in the irradiations minimized the number of protons scattered out of the stack and the neutron production within the stack. After irradiation, the short-lived radionuclides e.g. 22Na, 7Be, 24Na, 54Mn, and 56Co were determined using gamma-ray spectroscopy. 14C, 10Be, and 26Al were determined using Accelerator Mass Spectrometry. Our main objective is to measure the production cross sections of long-lived radionuclides. We have reported new cross section values for making 10Be from O and 14C from O, Mg, Al, Si, Fe, and Ni [1,2]. Using these new results, better estimates for the solar proton flux over several time periods in the past were determined [3]. However, no single value for the SCR flux could explain the measured data from different time periods. Further cross section measurements are being made to verify that the values used in these estimates were accurate. Irradiations designed to give good cross section measurements for long-lived radionuclides also give good cross section measurements for short-lived radionuclides. Results will be presented for proton production cross sections of 22Na from Mg, Al and Si, and 54Mn and 56Co from Fe and Ni; some values at low energies were reported previously [4]. These cross sections and other reported measurements [5, 6] will be used to improve the estimates of the recent SCR fluxes from the depth profiles for 22Na measured in lunar rocks [7, 8], and to better understand the SCR cosmogenic radionuclide production observed in Salem [9] and other other extraterrestrial materials. References: [1] Sisterson J. M. et al. (1992) LPS XXIII, 1305. [2] Sisterson J. M. et al. (1995) LPS XXVI, 1309. [3] Rao M. N. et al. (1994) GCA, 58, 4231. [4] Beverding A. M. et al. (1994) USGS Circular 1107, 29. [5] Michel R. and Stueck R. (1984) Proc. LPSC 14th, in JGR, 89, B673. [6] Bodemann R. et al. (1993) Nucl. Instr. Meth. Phys. Res., B82, 9. [7] Reedy R. C. (1977) Proc. LSC 8th, 825. [8] Fruchter J. S. et al. (1982) LPS XIII, 243. [9] Evans J. C. et al. (1987) LPS XVIII, 271.

Sisterson, J. M.; Beverding, A.; Kim, K. J.; Englert, P. A. J.; Jull, A. J. T.; Donahue, D. J.; Cloudt, S.; Castaneda, C.; Vincent, J.; Caffee, M. W.; Osazuwa, C. O.; Reedy, R. C.

1995-09-01

90

Latest Olduvai short-lived reversal episodes recorded in Chinese loess  

NASA Astrophysics Data System (ADS)

A duplicate high-resolution magnetic record was obtained from two parallel loess sections separated by about 300 m near Baoji city, southern Chinese Loess Plateau. This reveals at least eight short-lived reversed polarity episodes in the uppermost part of the Olduvai normal polarity subchronozone. Rock magnetic experiments and anisotropy of low-field magnetic susceptibility confirm that the multiple occurrence of short-lived reversals is not due to rock-magnetic and/or sedimentary causes. Assuming a constant accumulation rate within the Olduvai subchron, the short episode zone was estimated to span about 24-30 ka and 24-31 ka for the two sections, respectively. The duration of each short episode ranges from about 0.3 ka to 2.1 ka. The present results together with previous worldwide observations show that the occurrence of numerous short reversals is peculiar to the latest Olduvai subchron. The geodynamo may have been in an anomalous state at that time.

Yang, Tianshui; Hyodo, Masayuki; Yang, Zhenyu; Ding, Lin; Li, Huidi; Fu, Jianli; Wang, Shubing; Wang, Hongwei; Mishima, Toshiaki

2008-05-01

91

Determination of short-lived radionuclides in fresh fall-out debris for identification of nuclear weapon tests.  

PubMed

Radiochemical procedures for the assay of short-lived fission and activation products are described. They are rapid and quantitative and the radionuclides separated are radiochemically pure. Ratios of some of the short-lived radionuclides obtained by these measurements for selected Chinese and French nuclear tests are given and provide information about the fissile material used in the tests. PMID:18961860

Hingorani, S B; Khandekar, R N; Anand, S J

1976-04-01

92

Efficient adsorption of waterborne short-lived radon decay products by glass fiber filters.  

PubMed

Glass fiber filters of a certain brand were found to be very efficient (retention > 95%) for adsorption of short-lived radon decay products during filtration of water. Carrier-free samples are obtained in a convenient geometry for efficient gross beta counting. Adsorption of "hot atoms" is not disturbed by the presence of "cold" lead ions. Approximate radioactive equilibrium between radon and its short-lived decay products may or may not exist in water at the source, but does exist after 3 h in PET bottles. These bottles are shown to be gas-tight for radon. Calibration of activity concentration in Bq L(-1) (radon gas concentration approximately equilibrium equivalent radon concentration) was performed by several standard procedures. Limit of detection is 2 Bq L(-1) within 10 min (total time) or 10 Bq L(-1) within 5 min for a net signal of 5 times standard deviation. PMID:9003713

von Philipsborn, H

1997-02-01

93

CHARACTERIZATION OF SHORT-LIVED INTERMEDIATES PRODUCED DURING REPLICATION OF BACULOVIRUS DNA  

PubMed Central

SUMMARY In this report the short-lived DNA replication intermediates produced in both uninfected and Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infected Spodoptera frugiperda cells were characterized. The methods used included pulse-labeling of DNA in permiabilized cells, treatment of nascent DNA with Mung bean nuclease, and electrophoresis in neutral and alkaline agarose gels. In contrast to uninfected cells that produced a population of small DNA fragments of about 200 bp, a population of heterogeneous fragments of up to 5 kb with an average size of 1 to 2 kb derived randomly from the virus genome was identified as the short-lived intermediates produced during AcMNPV replication. The intermediates likely include Okazaki fragments derived from the lagging strands in viral replication forks as well as fragments produced during the recombination-dependent replication.

Mikhailov, Victor S.; Rohrmann, George F.

2009-01-01

94

Multimodel projections of climate change from short-lived emissions due to human activities  

Microsoft Academic Search

We use the GISS (Goddard Institute for Space Studies), GFDL (Geophysical Fluid Dynamics Laboratory) and NCAR (National Center for Atmospheric Research) climate models to study the climate impact of the future evolution of short-lived radiatively active species (ozone and aerosols). The models used mid-range A1B emission scenarios, independently calculated the resulting composition change, and then performed transient simulations to 2050

Drew T. Shindell; Hiram Levy; M. Daniel Schwarzkopf; Larry W. Horowitz; Jean-Francois Lamarque; Greg Faluvegi

2008-01-01

95

Efficient adsorption of waterborne short-lived radon decay products by glass fiber filters  

Microsoft Academic Search

Glass fiber filters of a certain brand were found to be very efficient (retention > 95%) for adsorption of short-lived radon decay products during filtration of water. Carrier-free samples are obtained in a convenient geometry for efficient gross beta counting. Adsorption of {open_quotes}hot atoms{close_quotes} is not disturbed by the presence of {open_quotes}cold{close_quotes} lead ions. Approximate radioactive equilibrium between radon and

H. Von Philipsborn; H. von

1997-01-01

96

Diffusion Experiment By Using The Short-Lived Radiotracer Of 8Li  

SciTech Connect

For an interdisciplinary application of the short-lived radioactive ion beams available at TRIAC, a non-destructive on-line radiotracer method for diffusion studies in solids has been developed. The experimental method using the {alpha}-emitting radioisotope of 8Li as the Li diffusion tracer in solids is introduced. The overview of the TRIAC, presently being operational for experiments, is briefly presented.

Jeong, S. C. [Institute of Panicle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan)

2006-11-02

97

Resprouting after disturbance: an experimental study with short-lived monocarpic herbs  

Microsoft Academic Search

We experimentally demonstrated the ability of three short-lived monocarpic species to vegetatively regenerate (resprout) from\\u000a roots after severe disturbance. We assessed the relationship between resprouting ability and (1) timing of injury with respect\\u000a to life-cycle stage (reproductive vs. vegetative plant), life-history mode (annual vs. winter annual) and phenological stage\\u000a (flowering vs. fruiting plant), (2) nutrient availability, and (3) disturbance severity

Jana Martínková; Jitka Klimešová; Stanislav Mihulka

2004-01-01

98

Inductively coupled plasma mass spectrometry for stable isotope metabolic tracer studies of living systems  

SciTech Connect

This dissertation focuses on the development of methods for stable isotope metabolic tracer studies in living systems using inductively coupled plasma single and dual quadrupole mass spectrometers. Sub-nanogram per gram levels of molybdenum (Mo) from human blood plasma are isolated by the use of anion exchange alumina microcolumns. Million-fold more concentrated spectral and matrix interferences such as sodium, chloride, sulfate, phosphate, etc. in the blood constituents are removed from the analyte. The recovery of Mo from the alumina column is 82 {+-} 5% (n = 5). Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is utilized for the quantitative ultra-trace concentration determination of Mo in bovine and human blood samples. The average Mo concentration in reference bovine serum determined by this method is 10.2 {+-} 0.4 ng/g, while the certified value is 11.5 {+-} 1.1 ng/g (95% confidence interval). The Mo concentration of one pool of human blood plasma from two healthy male donors is 0.5 {+-} 0.1 ng/g. The inductively coupled plasma twin quadrupole mass spectrometer (ICP-TQMS) is used to measure the carbon isotope ratio from non-volatile organic compounds and bio-organic molecules to assess the ability as an alternative analytical method to gas chromatography combustion isotope ratio mass spectrometry (GC-combustion-IRMS). Trytophan, myoglobin, and {beta}-cyclodextrin are chosen for the study, initial observation of spectral interference of {sup 13}C{sup +} with {sup 12}C{sup 1}H{sup +} comes from the incomplete dissociation of myoglobin and/or {beta}-cyclodextrin.

Luong, E.

1999-05-10

99

Results from the first national UK inter-laboratory calibration for very short-lived halocarbons  

NASA Astrophysics Data System (ADS)

Very short-lived halocarbons (VSLH) such as CH3I, CH2Br2 and CHBr3 provide an important source of reactive halogens to the atmosphere, however high spatial and seasonal variability in their ambient mixing ratios and sea-air fluxes gives rise to considerable uncertainty in global scale emission estimates. One solution to improve global flux estimates is to combine the multitude of individually published datasets to produce a database of collated global halocarbon observations. Some progress towards this has already been achieved through the HalOcAt (Halocarbons in the Ocean and Atmosphere) database initiative, but the absence of a common calibration scale for very short-lived halocarbons makes it difficult to distinguish true environmental variations from artefacts arising from differences between calibration methodologies. As such, the lack of inter-calibrations for both air and seawater measurements of very short-lived halocarbons has been identified as a major limitation to current estimations of the global scale impact of these reactive trace gases. Here we present the key findings from the first national UK inter-laboratory comparison for calibrations of the halocarbons CH3I, CH2Br2 and CHBr3. The aim of this inter-calibration was to provide transparency between halocarbon calibrations from major UK research institutions, an important step towards enabling all measurements from these institutions to be treated as one coherent integrated dataset for global source term parameterisations.

Jones, C. E.; Andrews, S. J.; Carpenter, L. J.; Hogan, C.; Hopkins, F. E.; Laube, J. C.; Robinson, A. D.; Spain, T. G.; Archer, S. D.; Harris, N. R. P.; Nightingale, P. D.; O'Doherty, S. J.; Oram, D. E.; Pyle, J. A.; Butler, J. H.; Hall, B. D.

2011-05-01

100

Results from the first national UK inter-laboratory calibration for very short-lived halocarbons  

NASA Astrophysics Data System (ADS)

Very short-lived halocarbons (VSLH) such as CH3I, CH2Br2 and CHBr3 provide an important source of reactive halogens to the atmosphere, however high spatial and seasonal variability in their ambient mixing ratios and sea-air fluxes gives rise to considerable uncertainty in global scale emission estimates. One solution to improve global flux estimates is to combine the multitude of individually published datasets to produce a database of collated global halocarbon observations. Some progress towards this has already been achieved through the HalOcAt (Halocarbons in the Ocean and Atmosphere) database initiative, however the absence of a common calibration scale for very short-lived halocarbons makes it difficult to distinguish true environmental variations from artefacts arising from differences between calibration methodologies. As such, the lack of inter-calibrations for both air and seawater measurements of very short-lived halocarbons has been identified as a major limitation to current estimations of the global scale impact of these reactive trace gases. Here we present the key findings from the first national UK inter-laboratory comparison for calibrations of the halocarbons CH3I, CH2Br2 and CHBr3. The aim of this inter-calibration was to provide transparency between halocarbon calibrations from major UK research institutions, an important step towards enabling all measurements from these institutions to be treated as one coherent integrated dataset for global source term parameterisations.

Jones, C. E.; Andrews, S. J.; Carpenter, L. J.; Hogan, C.; Hopkins, F. E.; Laube, J. C.; Robinson, A. D.; Spain, T. G.; Archer, S. D.; Harris, N. R. P.; Nightingale, P. D.; O'Doherty, S. J.; Oram, D. E.; Pyle, J. A.; Butler, J. H.; Hall, B. D.

2011-01-01

101

Activities Study of Short-lived Radioisotopes with a Filippov-type Plasma Focus  

NASA Astrophysics Data System (ADS)

Plasma focus devices are characterized by short-lived dense and hot plasma "pinch" due to the radial compression and electromagnetic acceleration. Through a short period of time, typically a few tens of nanoseconds, the pinched plasma goes through two phases of compression (thermal) and expansion (non-thermal or beam target) that provide necessary conditions for high nuclear reaction rates. If appropriate gas admixture at a desirable pressure is used, the processes can generate short-lived radioisotopes (SLRs) which the level of activities depends on the design and operational parameters. In this paper, the results of simulated theoretical works of two SLRs such as 10B (d, n) 11C and 14N (d, n) 15O are presented using a Filippov-type plasma focus "Dena" as a breeder with the bank energy ranges from 20 to 90 kJ at the repetition rates from 1 to 10 Hz. The admixture gas pressure of 10B and 14 N were taken to be approximately 0.05 of initial working pressure at optimum neutron yield regime. The results obtained are discussed.

Zaeem, Alireza Asle; Mahmood Sadat Kiai, S.; Sedaghatizade, Mahmood; Adlparvar, Shirin; Sheibani, Shahab

2009-09-01

102

The Developing Role of Short-Lived Radionuclides in Nuclear Medicine. A Report of the Task Force on Short-Lived Radionuclides for Medical Applications to the BRH, FDA.  

National Technical Information Service (NTIS)

The report recommends support of research in the methods of production, distribution, biomedical application and cost effectiveness of a number of accelerator produced and short-lived radionuclides by agencies of the Federal Government. These nuclides, al...

1977-01-01

103

Establishing appropriate measures for monitoring aging in birds: comparing short and long lived species  

USGS Publications Warehouse

In order to reveal patterns of reproductive aging in birds we focus on a short lived species, the Japanese quail and the American kestrel, which has a life span of medium length. Quail have been studied extensively in the laboratory as models for understanding avian endocrinology and behavior, and as a subject for toxicological research and testing. In the lab, Japanese quail show age-related deterioration in endocrine, behavioral, and sensory system responses; the American kestrel is relatively long lived and shows moderate evidence of senescence in the oldest birds. Using data collected from captive kestrels at the Patuxent Wildlife Research Center, a database was designed to document selected parameters over the life cycle of the kestrels. Life table data collated from many species indicate that longer lived species of birds show senescence in survival ability but this pattern has not been established for reproductive function. We suggest that useful comparisons among species can be made by identifying stages in reproductive life history, organized on a relative time scale. Preliminary data from quail and kestrels, admittedly only two species, do not yet indicate a pattern of greater reproductive senescence in longer-lived birds.

Ottinger, M.A.; Reed, E.; Wu, J.; Thompson, N.; French, J.B.

2003-01-01

104

Massive stars and short-lived radionuclides in the Solar System  

NASA Astrophysics Data System (ADS)

Short-lived radionuclides (SLRs) are radioactive elements (T1/2 ? 200 Myr) which were present in the nascent solar system and are now extinct. While the initial abundance of SLRs with the longest half-lives (T1/2 ? 3 Myr) is compatible with the expectations of Galactic evolution models, others have a last-minute origin. 7Be, 10Be, 36Cl, and 41Ca probably originated within the protoplanetary disk from the irradiation of gas and dust by energetic particles accelerated by the protoSun. 26Al and 60Fe were probably synthesized by massive stars and added to interstellar gas which will eventually make up the bulk of our solar system. Identifying the detailed mechanisms of 26Al and 60Fe production and mixing will shed a light on the relationship between the Sun formation history and massive stars.

Gounelle, M.

2011-11-01

105

Inter-laboratory comparisons of short-lived gamma-emitting radionuclides in nuclear reactor water.  

PubMed

Inter-laboratory comparisons of gamma-emitting nuclides in nuclear power plant coolant water have been carried out in Finland since 1994. The reactor water samples are taken and prepared by one of the two nuclear power plants and delivered to the participants. Since all the participants get their sample within just a few hours it has been possible to analyse and compare results of nuclides with half-lives shorter than 1h. The total number of short-lived nuclides is 26. All the main nuclides are regularly identified and the activities have been obtained with reasonable accuracy throughout the years. The overall deviation of the results has decreased in 13 years. The effects of true coincidence summing and discrepancies in nuclear data have been identified as potential sources of remaining discrepancies. All the participants have found this type of comparison very useful. PMID:18378157

Klemola, S K

2008-02-21

106

Health co-benefits of mitigating short-lived climate forcers  

NASA Astrophysics Data System (ADS)

Tropospheric ozone and black carbon (BC), a component of fine particulate matter (PM2.5), are associated with premature mortality and disrupt global and regional climate. While attention to their impacts on climate is relatively new, these pollutants have been regulated under health-based standards in the US and elsewhere in the world for decades. Understanding the health benefits of reducing short-lived climate forcers may help inform mitigation strategies, since health will likely continue to drive concern over air quality in the future. Several recent studies have examined the health and climate co-benefits of control measures targeting BC and methane, an ozone precursor. This talk will highlight the health benefits of 14 presently available BC and methane mitigation measures examined in the United Nations Environment Programme/World Meteorological Organization Integrated Assessment of Black Carbon and Ozone. Fully implementing these specific measures is estimated to avoid 1-5 million annual ozone and PM2.5-related premature deaths globally in 2030, >80% of which occur in Asia. BC mitigation measures are estimated to achieve ~98% of the avoided deaths from all measures, due to associated reductions of non-methane ozone precursor and organic carbon emissions and stronger mortality relationships for PM2.5 relative to ozone. These substantial public health co-benefits of mitigating short-lived climate forcers are independent of whether CO2 measures are enacted. Further analyses are needed to improve economic valuation of the varied impacts of short-lived climate forcers and quantify the benefits and costs of these measures in individual countries or regions to support policy decisions made at the national level.

Anenberg, S.

2011-12-01

107

Short-coherence off-axis holographic phase microscopy of live cell dynamics.  

PubMed

We demonstrate a single-shot holographic phase microscope that combines short-coherence laser pulses with an off-axis geometry. By introducing a controlled pulse front tilt, ultrashort pulses are made to interfere over a large field-of-view without loss of fringe contrast. With this microscope, quantitative phase images of live cells can be recorded in a full-field geometry without moving parts. We perform phase imaging of HEK293 cells, to study the dynamics of cell volume regulation in response to an osmotic shock. PMID:23024912

Witte, Stefan; Plau?ka, Andrius; Ridder, Margreet C; van Berge, Laura; Mansvelder, Huibert D; Groot, Marie Louise

2012-08-22

108

Laser generation of proton beams for the production of short-lived positron emitting radioisotopes  

NASA Astrophysics Data System (ADS)

Protons of energies up to 37 MeV have been generated when ultra-intense lasers (up to 1020Wcm-2) interact with hydrogen containing solid targets. These protons can be used to induce nuclear reactions in secondary targets to produce ?+-emitting nuclei of relevance to the nuclear medicine community, namely 11C and 13N via (p,n) and /(p,?) reactions. Activities of the order of 200 kBq have been measured from a single laser pulse interacting with a thin solid target. The possibility of using ultra-intense lasers to produce commercial amounts of short-lived positron emitting sources for positron emission tomography (PET) is discussed.

Spencer, I.; Ledingham, K. W. D.; Singhal, R. P.; McCanny, T.; McKenna, P.; Clark, E. L.; Krushelnick, K.; Zepf, M.; Beg, F. N.; Tatarakis, M.; Dangor, A. E.; Norreys, P. A.; Clarke, R. J.; Allott, R. M.; Ross, I. N.

2001-10-01

109

Coupling a Knudsen reactor with the short lived radioactive tracer 13N for atmospheric chemistry studies  

NASA Astrophysics Data System (ADS)

A Knudsen cell flow reactor was coupled to an online gas phase source of the short-lived radioactive tracer 13N to study the adsorption of nitrogen oxides on ice at temperatures relevant for the upper troposphere. This novel approach has several benefits over the conventional coupling of a Knudsen cell with a mass spectrometer. Experiments at lower partial pressures close to atmospheric conditions are possible. The uptake to the substrate is a direct observable of the experiment. Operation of the experiment in continuous or pulse mode allows to retrieve steady state uptake kinetics and more details of adsorption and desorption kinetics.

Schreiber, S.; Kerbrat, M.; Huthwelker, T.; Birrer, M.; Ammann, M.

2013-03-01

110

Search for a short-lived neutral particle produced in nuclear decay  

Microsoft Academic Search

We report on a search for a short-lived neutral particle phi produced in the decay of the 9.17-MeV J-italic\\/sup ..pi..\\/ = 2\\/sup +\\/ state in ¹⁴N. The experiment is sensitive to decays into an e-italic\\/sup +\\/e⁻ pair with tau\\/sub phi\\/approx. <10⁻¹¹ s. For m-italic\\/sub phi\\/ = 1.7 MeV we place a limit on the branching ratio of GAMMA\\/sub phi\\/\\/GAMMA\\/sub ..gamma..\\/<

M. J. Savage; R. D. McKeown; B. W. Filippone; L. W. Mitchell

1986-01-01

111

Half-lives of several states in isotopes produced in the SF of ^252Cf  

NASA Astrophysics Data System (ADS)

Half-lives (T_1/2) of 15 states in isotopes produced in the SF of ^252Cf have been determined using a new technique. The ^252Cf source was placed inside the Gammasphere, and triple and higher fold coincidence events were recorded. The half-lives and quadrupole deformations of ^104Zr, ^152Ce, and ^158Sm are determined for the first time. Except for ^102Sr, ^104Zr(?_2=0.45(4)) and ^158Sm(?_2=0.46(5)) are the most deformed among medium and heavy nuclei. Large deformation could have its origin in the high spin down-sloping orbitals near Z=38,40,62 and N=40,64,96. These large prolate deformations at ^104Zr and ^158Sm are confirmed by Hartree-Fock-Bogoliubov calculations carried out in the present work. Further, an excited rotational band including seven new ? transitions in ^97Sr was also identified. The band head energy of the 829.8 keV state in ^97Sr has an half-life of 265(27) nsec.

Hwang, J. K.; Ramayya, A. V.; Hamilton, J. H.; Fong, D.; Beyer, C. J.; Gore, P. M.; Jones, E. F.; Teran, E.; Oberacker, V. E.; Umar, A. S.; Luo, Y. X.; Rasmussen, J. O.; Zhu, S. J.; Wu, S. C.; Lee, I. Y.; Fallon, P.; Stoyer, M. A.; Asztalos, S. J.; Ginter, T. N.; Cole, J. D.; Ter-Akopian, G. M.; Donangelo, R.

2003-10-01

112

?-decay half-lives of new neutron-rich rare-earth isotopes 159Pm,162Sm, and 166Gd  

NASA Astrophysics Data System (ADS)

The new neutron-rich rare-earth isotopes 159Pm, 162Sm, and 166Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of 159Pm, 162Sm, and 166Gd were determined to be 1.5 ± 0.2, 2.4 ± 0.5, and 4.8 ± 1.0 s respectively. The partial decay scheme of 166Gd was constructed from ??-coincidence data. A more accurate half-life value of 25.6 ± 2.2 s was obtained for the previously identified isotope 166Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

Ichikawa, S.; Asai, M.; Tsukada, K.; Haba, H.; Nagame, Y.; Shibata, M.; Sakama, M.; Kojima, Y.

2005-06-01

113

Short-lived Absorptive Type III-like Microwave Bursts as a Signature of Fragmented Electron Injections  

Microsoft Academic Search

In this paper, we devote ourselves to interpreting the short-lived absorptive type III-like microwave bursts in the 2006 December 13 flare event observed with high temporal and spectral resolutions (8 ms and 10 MHz) by the Chinese Solar Broadband Radio Spectrometer (SBRS\\/Huairou) at 2.6-3.8 GHz. In the decimeter-centimeter wavelength range, we first present the observations of short-lived bursts represented as

Bin Chen; Yihua Yan

2008-01-01

114

Utilization of a boron irradiation vessel for NAA of short-lived radionuclides in biological and geological materials  

Microsoft Academic Search

A boron nitride irradiation vessel designed for use with a pneumatic tube transfer system has been used to analyze short-lived radionuclides by NAA. Bare and Cd-shielded irradiations on Co, Zr and Au were made to characterize the neutron fluxes in the irradiation position. Bare and BN-shielded irradiations were performed to determine epithermal advantage factors for 16 short-lived reactions and interference

M. D. Glascock; W. Z. Than; W. D. Ehmann

1985-01-01

115

Infection resistance of surface modified catheters with either short-lived or prolonged activity.  

PubMed

It has been suggested that the invasion of microbes into the catheter tract occurs mainly at the time of catheter insertion. To investigate whether the presence of an antimicrobial environment during the initial period after insertion is sufficient to reduce the risk of subsequent catheter colonization and infection, we evaluated the use of benzalkonium chloride-heparin bonded (BZK-hep) central venous catheters, which exhibit short-lived surface antimicrobial activity, using a rat subcutaneous model. Bacterial adherence on these catheters was determined, seven days after challenging the insertion site with 10(6) cfu of Staphylococcus aureus. A chlorhexidine-silver sulphadiazine impregnated catheter (Arrowg+ard), with longer lasting surface antimicrobial activity, and a hydrophilic coated catheter ('Hydrocath'), were evaluated simultaneously for comparison. Unlike Arrowg+ard antiseptic catheters, BZK-hep 'Hydrocath' and control catheters had significant bacterial adherence on their surface. Arrowg+ard catheters were colonized in 19% of the animals compared with 100% in all the other groups (P < 0.05; mean cfu cm-2: control = 1.3 x 10(6), BZK-hep = 4.3 x 10(5), Hydrocath = 2 x 10(5), Arrowg+ard = 71). Our results indicate that catheters with short-lived surface antimicrobial activity are unlikely to provide long-term protection against catheter-related infection. The efficacy of Arrowg+ard catheters may be due to the initial high rate of kill and prolonged antimicrobial activity. PMID:8522776

Sampath, L A; Chowdhury, N; Caraos, L; Modak, S M

1995-07-01

116

Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies  

SciTech Connect

Several short-lived pollutants known to impact Arctic climate may be contributing to the accelerated rates of warming observed in this region relative to the global annually averaged temperature increase. Here, we present a summary of the short-lived pollutants that impact Arctic climate including methane, tropospheric ozone, and tropospheric aerosols. For each pollutant, we provide a description of the major sources and the mechanism of forcing. We also provide the first seasonally averaged forcing and corresponding temperature response estimates focused specifically on the Arctic. The calculations indicate that the forcings due to black carbon, methane, and tropospheric ozone lead to a positive surface temperature response indicating the need to reduce emissions of these species within and outside the Arctic. Additional aerosol species may also lead to surface warming if the aerosol is coincident with thin, low lying clouds. We suggest strategies for reducing the warming based on current knowledge and discuss directions for future research to address the large remaining uncertainties.

Menon, Surabi; Quinn, P.K.; Bates, T.S.; Baum, E.; Doubleday, N.; Fiore, A.M.; Flanner, M.; Fridlind, A.; Garrett, T.J.; Koch, D.; Menon, S.; Shindell, D.; Stohl, A.; Warren, S.G.

2007-09-24

117

Efficient adsorption of waterborne short-lived radon decay products by glass fiber filters  

SciTech Connect

Glass fiber filters of a certain brand were found to be very efficient (retention > 95%) for adsorption of short-lived radon decay products during filtration of water. Carrier-free samples are obtained in a convenient geometry for efficient gross beta counting. Adsorption of {open_quotes}hot atoms{close_quotes} is not disturbed by the presence of {open_quotes}cold{close_quotes} lead ions. Approximate radioactive equilibrium between radon and its short-lived decay products may or may not exist in water at the source, but does exist after 3 b in PET bottles. These bottles are shown to be gas-tight for radon. Calibration of activity concentration in Bq L{sup -1} (radon gas concentration - equilibrium equivalent radon concentration) was performed by several standard procedures. Limit of detection is 2 Bq L{sup - 1} within 10 min (total time) or 10 Bq L{sup -1} within 5 min for a net signal of 5 times standard deviation. 13 refs., 5 figs.

Philipsborn, H. von [Univ. of Regensburg (Germany)

1997-02-01

118

Short-lived organic trace gases in the UT/LS: Results from recent field campaigns.  

NASA Astrophysics Data System (ADS)

The chemistry of the upper troposphere/lower stratosphere can be impacted by delivery of reactive trace gases that are variable in composition and depend on source emissions and transport pathway and time. Because surface emissions include gases with a range of chemical lifetimes, and because different source emissions (e.g. marine boundary layer, anthropogenic emissions, biomass burning) can have different chemical signatures, the composition of the organic trace gases that are found in the UT/LS region have the potential to provide diagnostic information on air mass sources and transport time scales. Further, the role of short-lived organic halogen gases in the UT/LS has been highlighted as a major uncertainty for defining the reactive halogen budget and the chemical boundary conditions for the stratospheric chemistry that affects ozone depletion rates. Recent campaigns in the tropics (TC-4 and AVE missions) and in the extra-tropics (START08) have included the measurement of trace gases from whole air sampling and analysis on the NASA WB-57 or NSF Gulfstream V aircraft. Measurements of a range of halocarbons, hydrocarbons, organic nitrates, and sulfur species were made to examine the role of short-lived organic gases in the UT/LS. This presentation will highlight different aspects of these measurements that deal with transport pathways, transport rates, and halogen budgets.

Atlas, E.; Lueb, R.; Zhu, X.; Pope, L.; Schauffler, S.; Pan, L.; Bowman, K. P.; Blake, D.; Meinardi, S.

2008-12-01

119

Direct detection and reactivity of the short-lived phenyloxenium ion.  

PubMed

Photolysis of protonated phenylhydroxylamine was studied using product analysis, trapping experiments, and laser flash photolysis experiments (UV-vis and TR(3) detection) ranging from the femtosecond to the microsecond time scale. We find that the excited state of the photoprecursor is followed by two species: a longer-lived transient (150 ns) that we assign to the phenoxy radical and a shorter-lived (3-20 ns) transient that we assign to the singlet phenyloxenium ion. Product studies from photolysis of this precursor show rearranged protonated o-/p-aminophenols and solvent water adducts (catechol, hydroquinone) and ammonium ion. The former products can be largely ascribed to radical recombination or ion recombination, while the latter are ascribed to solvent water addition to the phenyloxenium ion. The phenyloxenium ion is apparently too short-lived under these conditions to be trapped by external nucleophiles other than solvent, giving only trace amounts of o-/p-chloro adducts upon addition of chloride trap. Product studies upon thermolysis of this precursor give the same products as those generated from photolysis, with the difference being that the ortho adducts (o-aminophenol, hydroquinone) are formed in a higher ratio in comparison to the photolysis products. PMID:23713909

Hanway, Patrick J; Xue, Jiadan; Bhattacharjee, Ujjal; Milot, Maeia J; Ruixue, Zhu; Phillips, David Lee; Winter, Arthur H

2013-06-07

120

Seeds of alpine plants are short lived: implications for long-term conservation  

PubMed Central

Background and Aims Alpine plants are considered one of the groups of species most sensitive to the direct and indirect threats to ecosystems caused by land use and climate change. Collecting and banking seeds of plant species is recognized as an effective tool for providing propagating material to re-establish wild plant populations and for habitat repair. However, seeds from cold wet environments have been shown to be relatively short lived in storage, and therefore successful long-term seed conservation for alpine plants may be difficult. Here, the life spans of 69 seed lots representing 63 related species from alpine and lowland locations from northern Italy are compared. Methods Seeds were placed into experimental storage at 45 °C and 60 % relative humidity (RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50 % (p50) was determined using probit analysis and used as a measure of relative seed longevity between seed lots. Key Results Across species, p50 at 45 °C and 60 % RH varied from 4·7 to 95·5 d. Seed lots from alpine populations/species had significantly lower p50 values compared with those from lowland populations/species; the lowland seed lots showed a slower rate of loss of germinability, higher initial seed viability, or both. Seeds were progressively longer lived with increased temperature and decreased rainfall at the collecting site. Conclusions Seeds of alpine plants are short lived in storage compared with those from lowland populations/related taxa. The lower resistance to ageing in seeds of alpine plants may arise from low selection pressure for seed resistance to ageing and/or damage incurred during seed development due to the cool wet conditions of the alpine climate. Long-term seed conservation of several alpine species using conventional seed banking methods will be problematic.

Mondoni, Andrea; Probert, Robin J.; Rossi, Graziano; Vegini, Emanuele; Hay, Fiona R.

2011-01-01

121

ACTIVE MEDIA. RESONATORS: Short-lived absorption in excited gadolinium scandium gallium garnet crystals activated with Cr and Nd  

Microsoft Academic Search

An analysis is made of the possibility of reducing short-lived losses in a gadolinium scandium gallium garnet crystal activated with Cr and Nd when these losses are due to the short-wavelength component of the spectrum of the exciting radiation.

Evgeny V. Zharikov; S. P. Nasel'skii; A. I. Ryabov; Ivan A. Shcherbakov

1987-01-01

122

Large Differences in Aging Phenotype between Strains of the Short-Lived Annual Fish Nothobranchius furzeri  

PubMed Central

Background A laboratory inbred strain of the annual fish Nothobranchius furzeri shows exceptionally short life expectancy and accelerated expression of age markers. In this study, we analyze new wild-derived lines of this short-lived species. Methodology/Principal Findings We characterized captive survival and age-related traits in F1 and F2 offspring of wild-caught N. furzeri. Wild-derived N. furzeri lines showed expression of lipofuscin and neurodegeneration at age 21 weeks. Median lifespan in the laboratory varied from to 20 to 23 weeks and maximum lifespan from 25 to 32 weeks. These data demonstrate that rapid age-dependent decline and short lifespan are natural characteristics of this species. The N. furzeri distribution range overlaps with gradients in altitude and aridity. Fish from more arid habitats are expected to experience a shorter survival window in the wild. We tested whether captive lines stemming from semi-arid and sub-humid habitats differ in longevity and expression of age-related traits. We detected a clear difference in age-dependent cognitive decline and a slight difference in lifespan (16% for median, 15% for maximum lifespan) between these lines. Finally, we observed shorter lifespan and accelerated expression of age-related markers in the inbred laboratory strain compared to these wild-derived lines. Conclusions/Significance Owing to large differences in aging phenotypes in different lines, N. furzeri could represent a model system for studying the genetic control of life-history traits in natural populations.

Benedetti, Mauro; Roncaglia, Paola; Cattaneo, Antonino; Domenici, Luciano; Cellerino, Alessandro

2008-01-01

123

Long- and short-lived nuclide constraints on the recent evolution of permafrost soils  

NASA Astrophysics Data System (ADS)

Frozen permafrost ecosystems are particularly sensitive to climate warming, which notably induces a deepening of the active layer (the maximum thawing depth during summer time). As a consequence, geochemical and hydrological fluxes within boreal areas are expected to be significantly affected in the future. Understanding the relationship between environmental changes and permafrost modifications is then a major challenge. This work aims to evaluate in a Siberian watershed the dynamics of the permafrost active layer and their recent modifications by combining a classic study of long-lived nuclides to the study of short-lived nuclides of U and Th decay series. Two soil profiles, located on opposite slopes (north- and south-facing slopes) of the Kulingdakan watershed (Putorana Plateau, Central Siberia), were sampled at several depths within the active layer and (238U), (234U), (232Th), (230Th), (226Ra), (228Ra), (228Th) and (210Pb) were measured on bulk soil samples by TIMS or gamma spectrometry. Our results show that south-facing and north-facing soil profiles are significantly different in terms of evolution of chemical concentrations and nuclide activities; north-facing soil profile is strongly affected by atmospheric inputs whereas long-lived nuclide dynamics within south-facing soil profile are dominated by weathering and exhibit more complex patterns. The amount of above-ground biomass being the single varying parameter between the two slopes of the watershed, we suggest that the structuring of permafrost active layer is very sensitive to vegetation activity and that the functioning of boreal soils will be significantly modified by its development due to more favorable climatic conditions. Moreover, the coupling of long and short-lived nuclides highlights the superimposition of a recent mobilization of chemical elements within soils (<10 years) over a much older soil structure (>8000 years), which can be observed for both soil profiles. The shallowest layer of the north-facing soil profile presents a recent increase of Th leaching that we link to the development of vegetation activity and/or organic matter degradation. In contrast, recent changes within south-facing soil profile affect the deepest part of the active layer, suggesting its deepening as a result of a global warming of Siberian soils.

Bagard, M.; Chabaux, F. J.; Rihs, S.; Pokrovsky, O. S.; Prokushkin, A. S.; Viers, J.

2011-12-01

124

Contribution of very short-lived substances to stratospheric bromine loading: uncertainties and constraints  

NASA Astrophysics Data System (ADS)

Very short-lived substances (VSLS) still represent a major factor of uncertainty in the quantification of stratospheric bromine loading. One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be loss of inorganic bromine (Bry) in the tropical tropopause layer (TTL) due to dehydration. We use sensitivity calculations with a~three-dimensional chemistry transport model comprising a consistent parametrization of convective transport and a comprehensive chemistry scheme to investigate the associated processes. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). The organic bromine source gases as well as the resulting profile of inorganic bromine in the model are consistent with available observations. In contrast to its organic precursors, Bry is assumed to have a~significant sorption capacity regarding sedimenting liquid or frozen particles thus the fraction of intact source gases during their ascent through the TTL is a critical factor. We find that source gas injection is the dominant pathway into the stratosphere, about 50% of CHBr3 and 93% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the interannual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. In principal, the same applies as well to CH2Br2, though it is considerably less responsive due to its longer lifetime. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model, VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. If heterogeneous chemistry is ignored, the HBr/Bry fraction exceeds 50% and about 10% of bromine from VSLS is scavenged. Dehydration plays a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr. In this case, up to 12% of bromine from VSLS is removed. Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%. In conclusion, considering the average abundance of bromine short-lived source gases in convective updrafts of 6 parts per trillion by volume (pptv) we find a most likely contribution of VSLS to stratospheric bromine in the range of 4.5-6 pptv.

Aschmann, J.; Sinnhuber, B.-M.

2012-11-01

125

Contribution of very short-lived substances to stratospheric bromine loading: uncertainties and constraints  

NASA Astrophysics Data System (ADS)

Very short-lived substances (VSLS) still represent a major factor of uncertainty in the quantification of stratospheric bromine loading. One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be loss of inorganic bromine (Bry) in the tropical tropopause layer (TTL) due to dehydration. We use sensitivity calculations with a three-dimensional chemistry transport model comprising a consistent parametrization of convective transport and a comprehensive chemistry scheme to investigate the associated processes. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). The organic bromine source gases as well as the resulting profile of inorganic bromine in the model are consistent with available observations. In contrast to its organic precursors, Bry is assumed to have a significant sorption capacity regarding sedimenting liquid or frozen particles thus the fraction of intact source gases during their ascent through the TTL is a critical factor. We find that source gas injection is the dominant pathway into the stratosphere, about 50% of CHBr3 and 94% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the interannual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. In principle, the same applies as well to CH2Br2, though it is considerably less responsive due to its longer lifetime. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model, VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. If heterogeneous chemistry is ignored, the HBr/Bry fraction exceeds 50% and about 10% of bromine from VSLS is scavenged. Dehydration plays a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr. In this case, up to 12% of bromine from VSLS is removed. Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%. Assuming 6 parts per trillion by volume (pptv) of bromine short-lived source gases in convective updrafts, a value that is supported by observational data, we find a most likely contribution of VSLS to stratospheric bromine in the range of 4.5-6 pptv.

Aschmann, J.; Sinnhuber, B.-M.

2013-02-01

126

New Developments for Isochronous Mass Measurements of Short-Lived Nuclei  

SciTech Connect

The combination of the in-flight separator FRS and the storage-ring ESR at GSI offers unique possibilities for high accuracy mass and lifetime measurements of bare and few-electron fragments. Operating the ESR in the isochronous mode allows for measurements of revolution frequencies of stored ions without cooling. Isochronous Mass Spectrometry (IMS) can be applied to fragments with half-lives as short as several tens of microseconds. Newly developed magnetic rigidity tagging increases the resolving power of IMS to about 500000. IMS can be used to measure masses of nuclei with rates even lower than one ion per day, a property also needed for the purpose of the ILIMA project at the future facility FAIR.

Knoebel, R.; Litvinov, S. A.; Boutin, D.; Chen, L.; Geissel, H.; Litvinov, Yu. A.; Scheidenberger, C.; Winckler, N. [Gesellschaft fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Justus-Liebig-Universitaet Giessen, 35392 Giessen (Germany); Sun, B. [Gesellschaft fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); School of Physics, Peking University, Beijing 100871 (China); Beckert, K.; Beller, P.; Bosch, F.; Brandau, C.; Dimopoulou, C.; Dolinskii, A.; Kozhuharov, C.; Mazzocco, M.; Montes, F.; Muenzenberg, G.; Nociforo, C. [Gesellschaft fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany)] (and others)

2007-02-26

127

Neutron-induced capture cross sections of short-lived actinides with the surrogate reaction method  

NASA Astrophysics Data System (ADS)

Determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2 = 27 d). The 233Pa (n,?) cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p) reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,p?) reaction as a surrogate reaction for the (n,?) predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ?E-E Telescopes will be presented and preliminary results will be discussed.

Aïche, M.; Boutoux, G.; Jurado, B.; Barreau, G.; Matthieu, L.; Czajkowski, S.; Dassie, D.; Haas, B.; Méot, V.; Roig, O.; Gaudefroy, L.; Taieb, J.; Pillet, N.; Faul, T.; Sérot, O.; Bauge, E.; Gunsing, F.

2010-03-01

128

Seasonal Short-Lived Radium Activity in the Venice Lagoon: The Role of Residence Time  

NASA Astrophysics Data System (ADS)

Radium is considered to be an excellent tracer of submarine groundwater discharge (SGD) and, therefore, has been used in many studies of this process in the past decade. Comprehensive surveys of excess 223,224Ra activity were completed in the surface waters of the Venice Lagoon over 6 seasons in order to quantify seasonal variation of SGD into the lagoon. The mass balance of radium found that SGD was 5-26 times greater than total river discharge (35.5 m3 s-1), and that total SGD could differ by almost an order of magnitude pending season. Several possible parameters, which may cause the seasonal variation, were tested. These included precipitation events, average tidal elevation, average tidal excursion, wind speed and direction, yet none provided a satisfactory explanation for the difference. Residence time based on a hydrodynamic model, however, was very strongly correlated with the observed variation. When the average residence time in the lagoon was low (5 days) the SGD was calculated to be 930 m3 s-1 and when the average residence time was high (9 days) the SGD was quantified as 160 m3 s-1. Radioactive decay is already accounted for in the mass balance model and therefore this correlation must be explained by another process. The Venice Lagoon is characterized by low residence time during periods of spring tides and bora or northerly winds, both of which create exceptionally strong currents in the Venice Lagoon. The currents as well as the large tidal excursion which occurs at spring tides drive a recirculation of seawater through the surface sediments, which greatly increases short-lived Ra activity in the surface waters. This evidence suggests, therefore, that short-lived Ra mass balance studies, which are based on a single survey, may under or overestimate the mean annual SGD pending the hydrodynamics of the investigated location.

Rapaglia, J.; Ferrarin, C.; Zaggia, L.; Umgiesser, G.; Zuppi, G.; Manfe', G.

2008-12-01

129

Transfer time and source tracing in the soil - water- -plant system deciphered by the U-and Th-series short-lived nuclides  

NASA Astrophysics Data System (ADS)

Because soils form at the critical interface between the lithosphere and the atmosphere, characterization of the dynamics occurring through this compartment represents an important goal for several scientific fields and/or human activities. However, this issue remains a challenge because soils are complex systems, where a continuous evolution of minerals and organic soil constituents occurs in response to interactions with waters and vegetation. This study aims to investigate the relevance of short-lived nuclides of U- and Th-series to quantify the transfer times and scheme of radionuclides through a soil - water - plant ecosystem. Activities of (226Ra), (228Ra) and (228Th), as well as the long-lived (232Th), were measured by TIMS and gamma-spectrometry in the major compartments of a forested soil section, i.e.: solid soil fractions (exchangeable fraction, secondary phases and inherited primary minerals), waters (seepage soil waters and a spring further down the watershed) and vegetation (fine and coarse roots of beech trees, young and mature leaves). The matching of these nuclides half-live to bio-geochemical processes time-scale and the relatively good chemical analogy of radium with calcium make these isotopes especially suitable to investigate either time or mechanism of transfers within a soil-water-plant system. Indeed, the (228Ra/226Ra) isotopic ratios strongly differ in the range of samples, allowing quantifying the source and duration transfers. Analyses of the various solid soil fractions demonstrate a full redistribution of Ra isotopes between the inherited minerals and secondary soil phases. However, the transfer of these isotopes to the seepage water or to the tree roots does not follow a simple and obvious scheme. Both primary and secondary phases show to contribute to the dissolved radium. However, depending on the season, the tree leaves degradation also produces up to 70% of dissolved radium. Immobilization of a large part of this radium occurs within the first 70cm of the soil layer, either by plant uptake, or adsorption/ precipitation in particular soil layers. Consistently, the Ra isotope ratio in the spring water is similar to the inherited primary soil fraction, suggesting a "deep" (i.e. below the shallow 70cm of soil layer) origin of the exported dissolved radium and the short-scale effect of vegetation cycling onto radium transfer. The radium isotopic ratio in the trees roots does not match the soil exchangeable fraction, nor the seepage waters, but rather the bulk soil, suggesting a large and mixed pool of radium for roots uptake. Decay of 228Ra within the various parts of the trees allows calculating a vegetation cycling duration of about 10 years for this nuclide. Finally an unexpected large amount of unsupported 228Th in the tree leaves can only be explained by a preferential migration of the 228Ac (228Th precursor). The very short life of this nuclide allows therefore assessing that such transport from roots and deposition within stem and leaves take place within 30 hours at the most.

Rihs, S.; Pierret, M.; Chabaux, F.

2011-12-01

130

Harvard-MIT research program in short-lived radiopharmaceuticals. Final report  

SciTech Connect

The Harvard-MIT Research Program in Short-lived Radiopharmaceuticals was established in 1977 to foster interaction among groups working in radiopharmaceutical chemistry at Harvard Medical School, the Massachusetts Institute of Technology, and the Massachusetts General Hospital. To this was added a group at The Childrens Hospital. From these collaborations and building upon the special strengths of the participating individuals, laboratories and institutions, it was hoped that original approaches would be found for the design of new, clinically useful, radiolabeled compounds. The original thrust of this proposal included: (a) examination of the coordination chemistry of technetium as a basis for rational radiopharmaceutical design, (b) development of an ultrashort-lived radionuclide generator for the diagnosis of congenital heart disease in newborns, (c) synthesis of receptor-site-directed halopharmaceuticals, (d) improved facile labeling of complex molecules with positron-emitting radionuclides. The authors` 1986 proposal was oriented toward organs and disease, emphasizing radiolabeled agents that delineate specific functions and the distribution of receptors in brain, heart, and tumors. In 1989, they further refined their purposes and focused on two major aims: (a) synthesis and utilization of neutral technetium and rhenium complexes of high specific activity, and (b) development of new approaches to the radiolabeling of proteins, peptides, immunoglobulins, and their fragments. In 1992, the authors amended this proposal to concentrate their efforts on biologically active peptides and proteins for targeted radiodiagnosis and therapy.

Adelstein, S.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Office of Sponsored Programs

1995-02-01

131

Supernova injection of short-lived radionuclides into the presolar cloud: A feasibility study  

NASA Astrophysics Data System (ADS)

Meteorite inclusions show that the early solar system was radioactive with species of short lifetimes compared to the formation time of the solar system. Transporting the radioactive material from the creation site to the formation site of the sun was expected to take enough time that these species should have decayed to nonexistence. Some special series of events seems necessary to speed the process along. Cameron & Truran (1977) suggested that the source of these short-lived radionuclides could have been a supernova. Numerical hydrodynamic studies have shown that slow shockwaves can inject material into a small, dense cloud core. Most stars are not born in lone dense cores. Thus any core that might have become the solar system was probably shrouded with an envelope that the ejecta from supernova would have had to penetrate along with the intervening interstellar medium. We present numerical hydrodynamic studies using Zeus-2D investigating how a supernova can inject its material into a moderately dense molecular cloud. We model a self-similar explosion colliding with a spherical cloud and examine the results for injection. We have modified Zeus-2D by adding three tracking dyes and changing the effective adiabatic index of the fluid in response to the shock-cloud collision. We find that if the effective adiabatic index of the gas is less than 5/3 then injection can occur, and we describe the basics of the mechanism by which this occurs.

Davis, Keith W.

132

Short-lived protease-serpin complexes: Partial disruption of the rat trypsin active site  

PubMed Central

Serpins inhibit serine proteases by mechanically disrupting the protease active site. The protease first reacts with the serpin's reactive center loop (RCL) to form an acylenzyme. Then the RCL inserts into a ?-sheet in the body of the serpin, translocating the attached protease ?70 Å and deforming the protease active site, thereby trapping the acylenzyme. Loop insertion (?1 s?1) is an order of magnitude slower than hydrolysis of a typical substrate acylenzyme (?50 s?1), indicating that the protease is inhibited during translocation. We have previously trapped a partially translocated covalent complex of rat trypsin and ?1-proteinase inhibitor (EpartI*) resulting from attractive interactions between cationic dyes and anionic rat trypsin. Here, using single pair Förster resonance energy transfer, we demonstrate that EpartI* is a metastable complex that can dissociate to free protease and cleaved serpin (I*) as well as convert to the canonical fully translocated complex EfullI*. The partitioning between these two pathways is pH dependent, with conversion favored at low pH and dissociation favored at high pH. The short lifetime of EpartI* (?3 h at pH 7.4) and the pH dependence of EpartI* dissociation suggest that, unlike in EfullI*, the catalytic triad is intact in EpartI*. These results also demonstrate that interactions between target proteases and the body of the serpin can hinder protease translocation leading to short-lived covalent complexes.

Liu, Lu; Mushero, Nicole; Hedstrom, Lizbeth; Gershenson, Anne

2007-01-01

133

Short-lived effects of a visual inducer during egocentric space perception and manual behavior.  

PubMed

A pitched visual inducer has a strong effect on the visually perceived elevation of a target in extrapersonal space, and also on the elevation of the arm when a subject points with an unseen arm to the target's elevation. The manual effect is a systematic function of hand-to-body distance (Li and Matin Vision Research 45:533-550, 2005): When the arm is fully extended, manual responses to perceptually mislocalized luminous targets are veridical; when the arm is close to the body, gross matching errors occur. In the present experiments, we measured this hand-to-body distance effect during the presence of a pitched visual inducer and after inducer offset, using three values of hand-to-body distance (0, 40, and 70 cm) and two open-loop tasks (pointing to the perceived elevation of a target at true eye level and setting the height of the arm to match the elevation). We also measured manual behavior when subjects were instructed to point horizontally under induction and after inducer offset (no visual target at any time). In all cases, the hand-to-body distance effect disappeared shortly after inducer offset. We suggest that the rapid disappearance of the distance effect is a manifestation of processes in the dorsal visual stream that are involved in updating short-lived representations of the arm in egocentric visual perception and manual behavior. PMID:23653410

Li, Wenxun; Matin, Ethel; Matin, Leonard

2013-07-01

134

First Results Using a New Technology for Measuring Masses of Very Short-Lived Nuclides with Very High Accuracy: the MISTRAL Program at ISOLDE  

SciTech Connect

MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na{clubsuit}, Mg, Al{clubsuit}, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

C. Monsanglant; C. Toader; G. Audi; G. Bollen; C. Borcea; G. Conreur; R. Cousin; H. Doubre; M. Duma; M. Jacotin; S. Henry; J.-F. Kepinski; H.-J. Kluge; G. Lebee; G. Le Scornet; D. Lunney; M. de Saint Simon; C. Scheidenberger; C. Thibault

1999-12-31

135

Hydrogen and Oxygen Isotope Data From the AIRMoN Sampling Network, Central and Eastern USA, Suggest a High Degree of Short-Term Isotopic Variability in Precipitation  

NASA Astrophysics Data System (ADS)

The Atmospheric Integrated Research Monitoring Network (AIRMoN) deposition program consists of an array of precipitation collection stations located throughout the eastern and central United States. At these locations, daily to sub-weekly precipitation sample collection has resulted in an extensive archive of precipitation that allows for analysis on the scale of individual precipitation events. Approximately 500 of these samples collected during 1996-2000 from Florida, Illinois, Ohio, Tennessee, Vermont, and West Virginia have been analyzed for delta D and delta 18 O in order to assess the short-term variability of the isotopic composition of precipitation. The isotopic composition of samples among precipitation events from all locations is highly variable. For example, delta values range by as much as approximately 100 per mil for hydrogen and approximately 12 per mil for oxygen for precipitation events separated by only a few days regardless of geographic location and time of year. There is a weak correlation between temperature at the time of the precipitation event and isotopic value of precipitation at all locations. In general, the long-established trends in isotopic values at different geographic locations are evident in this dataset. For example, on average, the most depleted isotopic values are from locations in the northern and eastern part of the study area, and the most enriched values are from the low latitude sample sites. For individual precipitation events throughout the study area, however, storm source appears to be the primary control of isotopic value rather than temperature. The database that will result from the ongoing isotopic analysis of the complete suite of AIRMoN samples will allow for the examination of both short (daily) and long (decadal) timescale oxygen and hydrogen isotope composition over a wide area of the United States. This dataset will be of benefit to (for example) the study of geographic extent and influence of El Nino/La Nina cycles and other sub-annual to and decadal scale modifications to atmospheric circulation, the back-calculation of storm trajectories, and the temporal variability of climate that may not be evident from traditional climate studies.

Sjostrom, D. J.; Welker, J. M.

2005-12-01

136

Erratum to ``Beta decay half-lives of neutron rich Ti-Co isotopes around /N=40'' [Nucl. Phys. A 660 (1999) 3-19  

NASA Astrophysics Data System (ADS)

The neutron-rich 57-59Ti, 59-62V, 61-64Cr, 63-66Mn, 65-68Fe, 67-70Co have been produced at GANIL via interactions of a 60.4 MeV/u 86Kr34+ with a 58Ni target. They have been separated by the doubly achromatic spectrometer LISE3. Beta-decay half-lives have been determined for all produced nuclei, and subsequent /?-rays have been observed for the most efficiently produced nuclei. The measured half-lives of vanadium and chromium isotopes are compared to QRPA calculations using ground states deformations from the FRDM or ETFSI models. In an astrophysical context, the short half-lives of 58Ti and 64Cr indicate that these nuclei are potential r-process progenitors, after /?-decay, of 58Fe and 64Ni in certain inclusions of meteorites.

Sorlin, O.; Donzaud, C.; Axelsson, L.; Belleguic, M.; Béraud, R.; Borcea, C.; Canchel, G.; Chabanat, E.; Daugas, J. M.; Emsallem, A.; Girod, M.; Guillemaud-Mueller, D.; Kratz, K.-L.; Leenhardt, S.; Lewitowicz, M.; Longour, C.; Lopez, M. J.; de Oliveira Santos, F.; Petizon, L.; Pfeiffer, B.; Pougheon, F.; Saint-Laurent, M. G.; Sauvestre, J. E.

2000-04-01

137

Measurement method of activation cross-sections of reactions producing short-lived nuclei with 14 MeV neutrons  

Microsoft Academic Search

We describe a method for obtaining reliable activation cross-sections in the neutron energy range between 13.4 and 14.9MeV for the reactions producing short-lived nuclei with half-lives between 0.5 and 30min. We noted neutron irradiation fields and measured induced activities, including (1) the contribution of scattered low-energy neutrons, (2) the fluctuation of the neutron fluence rate during the irradiation, (3) the

K. Kawade; H. Sakane; Y. Kasugai; M. Shibata; T. Iida; A. Takahashi; T. Fukahori

2003-01-01

138

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula  

NASA Astrophysics Data System (ADS)

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (106 less than or equal to Tau-bar less than or equal to 2 x 107 yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields of s-process nuclei in the convective He-shell for different neutron exposures tau0 were obtained, and AGB stars were shown to produce several radioactive nuclei (especially Pd-107, Pb-205, Fe-60, Zr-93, Tc-99, Cs-135, and Hf-182) in diferent amounts. Assuming either contamination of the solar nebula from a single AGB star or models for continuous injection and mixing from many stars into the ISM, we calculate the ratios of radioactive to stable nuclei at the epoch of the Sun's formation. The dilution factor between the AGB ejecta and the early solar system matter is obtained by matching the observed Pd-107/Pd-108 and depends on the value of tau0. It is found that small masses MHe of He-shell material (10-4-10-7 solar mass) enriched in s-process nuclei are sufficient to contaminate 1 solar mass of the ISM to produce the Pd-107 found in the early solar system. Predictions are made for all of the other radioactive isotopes. The optimal model to explain several observed radioactive species at different states of the proto-solar nebula involves a single AGB star with a low neutron exposure (tau0 = 0.03 mbarn-1) which contaminated the cloud with a dilution factor of MHe/solar mass approximately 1.5 x 10-4. This will also contribute newly synthesized stable s-process nuclei in the amount of approximately 10-4 of their abundances already present in the proto-solar cloud. Variations in the degree of homogenization (approximately 30%) of the injected material may account for some of the small general isotopic anomalies found in meteorites. It is also found that Fe-60 is produced in small but significant quantities that may be sufficient to explain the observations if the time elapsed delta from the contamination of the ISM to the formation of protoplanetary bodies is not higher than delta = 5 x 106 yr. If delta is longer, up to 10 x 106 yr, this would require the single AGB star to experience enhanced neutron densities (nn approximately 3 x 109n/cu cm) in the s-processing zone in order to compensate for the branching at Fe-59. The alternative model of long-term continuous ejection of matter from many AGB stars does not appear to match the observations. We also estimate the Al-26 production from the H-shell and find that the Al-26 abundance in the early solar system may be readily explained in a self-consistent manner. Moreover, Al-26 from AGB stars may contribute substantially to the galactic Al-26 gamma-source, while no significant gamma-flux from Co-60 (deriving from Fe-60 decay) is to be expected.

Wasserburg, G. J.; Busso, M.; Gallino, R.; Raiteri, C. M.

1994-03-01

139

Uncertainties and constraints regarding the contribution of very short-lived substances to stratospheric bromine loading  

NASA Astrophysics Data System (ADS)

A major factor of uncertainty in the assessment of stratospheric bromine loading is the unclear role of very short-lived substances (VSLS). One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be the loss of inorganic bromine (Bry) in the tropical tropopause layer due to dehydration. Besides the dehydration process itself, transportation pathways and velocities are also of vital importance as they influence the partitioning between mostly insoluble organic source gases and partly soluble inorganic degradation products. To investigate this complex system we employ an extensive set of sensitivity calculations with a three-dimensional chemistry transport model comprising a consistent parameterization of convective transport and a comprehensive chemistry scheme. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2) assuming a fixed and uniform detrainment mixing ratio of 1 pptv each. Despite our simplified approach our model agrees reasonably well with available observations of bromine source and product gases. We find that source gas injection is the dominant pathway for VSLS into the stratosphere; about 50% of CHBr3 and 93% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the inter-annual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model; VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. The loss of inorganic bromine is not very sensitive to moderate changes of the involved parameters such as the abundance of water vapor, sedimentation velocity of particles or ice uptake coefficients. However, dehydration may play a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr (up to 12% loss of bromine from VSLS). Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%.

Aschmann, Jan; Sinnhuber, Björn-Martin

2013-04-01

140

Isotope shifts and nuclear charge radii of krypton isotopes across the N=50 shell closure  

Microsoft Academic Search

Optical isotope shifts have been measured in the 5s[3\\/2]02-5p[3\\/2]2 transition in atomic krypton (lambda=760 nm) using collinear-fast-beam laser spectroscopy. Isotope shifts were determined for the short-lived neutron-rich isotopes 88Kr and 90Kr, as well as for all the stable isotopes between A=78 and 86, thus extending the data in this element, for the first time, beyond the N=50 shell closure. The

H. A. Schuessler; A. Alousi; R. M. Evans; M. Brieger; F. Buchinger; Y. F. Li

1990-01-01

141

beta-decay half-lives of neutron-rich isotopes of Fe, Co, Ni involved in the beginning of the r-process.  

National Technical Information Service (NTIS)

The very neutron-rich Fe- to Ni-isotopes are of interest since they are located at the very beginning of the astrophysical r-process path. The (beta)-decay half-lives of several isotopes, identified in thermal fission of (sup 235)U or (sup 239)Pu, have be...

S. Czajkowski M. Bernas P. Armbruster H. Faust J. P. Bocquet

1992-01-01

142

Beta-decay half-lives of neutron rich Cu and Ni isotopes produced by thermal fission of (sup 235)U and (sup 239)Pu.  

National Technical Information Service (NTIS)

The half-lives of very neutron rich isotopes of Ni and Cu have been measured. The isotopes are produced in very asymmetric thermal fission of (sup 235)U and (sup 239)Pu at the I.L.L. high flux reactor. They are separated by means of the Lohengrin spectrom...

M. Bernas J. L. Sida J. P. Bocquet H. Faust R. Brissot

1989-01-01

143

AGB stars as a source of short-lived radioactive nuclei in the solar nebula  

NASA Astrophysics Data System (ADS)

The purpose is to estimate the possible contribution of some short-lived nuclei to the early solar nebula from asymptotic giant branch (AGB) sources. Low mass (1 to 3 solar mass) AGB stars appear to provide a site for synthesis of the main s process component for solar system material with an exponential distribution of neutron irradiations varies as exp(-tau/tau0) (where tau is the time integrated neutron flux with a mean neutron exposure tau0) for solar abundances with tau0 = 0.28 mb-1. Previous workers estimated the synthesis of key short-lived nuclei which might be produced in AGB stars. While these calculations exhibit the basic characteristics of nuclei production by neutron exposure, there is need for a self-consistent calculation that follows AGB evolution and takes into account the net production from a star and dilution with the cloud medium. Many of the general approaches and the conclusions arrived at were presented earlier by Cameron. The production of nuclei for a star of 1.5 solar mass during the thermal pulsing of the AGB phase was evaluated. Calculations were done for a series of thermal pulses with tau0 = 0.12 and 0.28 mb-1. These pulses involve s nucleosynthesis in the burning shell at the base of the He zone followed by the ignition of the H burning shell at the top of the He zone. After about 10-15 cycles the abundances of the various nuclei in the He zone become constant. Computations of the abundances of all nuclei in the He zone were made following Gallino. The mass of the solar nebula was considered to consist of some initial material of approximately solar composition plus some contributions from AGB stars. The ratios of the masses required from the AGB He burning zone to the ISM necessary to produce the observed value of Pd-107/Pd-108 in the early solar system were calculated and this dilution factor was applied to all other relevant nuclei.

Wasserburg, G. J.; Gallino, R.; Busso, M.; Raiteri, C. M.

1993-03-01

144

Allograft rejection is restrained by short-lived TIM-3+PD-1+Foxp3+ Tregs  

PubMed Central

Tregs play a pivotal role in inducing and maintaining donor-specific transplant tolerance. The T cell immunoglobulin and mucin domain-3 protein (TIM-3) is expressed on many fully activated effector T cells. Along with program death 1 (PD-1), TIM-3 is used as a marker for exhausted effector T cells, and interaction with its ligand, galectin-9, leads to selective death of TIM-3+ cells. We report herein the presence of a galectin-9–sensitive CD4+FoxP3+TIM-3+ population of T cells, which arose from CD4+FoxP3+TIM-3– proliferating T cells in vitro and in vivo and were often PD-1+. These cells became very prominent among graft-infiltrating Tregs during allograft response. The frequency and number of TIM-3+ Tregs peaked at the time of graft rejection and declined thereafter. Moreover, these cells also arise in a tolerance-promoting donor-specific transfusion model, representing a pool of proliferating, donor-specific Tregs. Compared with TIM-3– Tregs, TIM-3+ Tregs, which are often PD-1+ as well, exhibited higher in vitro effector function and more robust expression of CD25, CD39, CD73, CTLA-4, IL-10, and TGF-? but not galectin-9. However, these TIM-3+ Tregs did not flourish when passively transferred to newly transplanted hosts. These data suggest that a heretofore unrecognized graft-infiltrating, short-lived subset of Tregs can restrain rejection.

Gupta, Shipra; Thornley, Thomas B.; Gao, Wenda; Larocca, Rafael; Turka, Laurence A.; Kuchroo, Vijay K.; Strom, Terry B.

2012-01-01

145

Highlighting short-lived excited electronic states with pump-degenerate-four-wave-mixing  

NASA Astrophysics Data System (ADS)

Detection of short-lived transient species is a major challenge in femtosecond spectroscopy, especially when third-order techniques like transient absorption are used. Higher order methods employ additional interactions between light and matter to highlight such transient species. In this work we address numerically and experimentally the detection of ultrafast species with pump-Degenerate Four Wave Mixing (pump-DFWM). In this respect, conclusive identification of ultrafast species requires the proper determination of time-zero between all four laser pulses (pump pulse and the DFWM sequence). This is addressed here under the light of experimental parameters as well as molecular properties: The role of pulse durations, amount of pulse chirp as well as excited state life time is investigated by measuring a row of natural pigments differing mainly in the number of conjugated double bonds (N = 9 to 13). A comparison of the different signals reveals a strikingly unusual behavior of spheroidene (N = 10). Complete analysis of the pump-DFWM signal illustrates the power of the method and clearly assigns the uniqueness of spheroidene to a mixing of the initially excited state with a dark excited electronic state.

Marek, Marie S.; Buckup, Tiago; Southall, June; Cogdell, Richard J.; Motzkus, Marcus

2013-08-01

146

Spatial distribution of brominated very short-lived substances in the eastern Pacific  

NASA Astrophysics Data System (ADS)

Seawater concentrations and distributions of brominated very short-lived substances (BrVSLS), including bromoform (CHBr3), dibromomethane (CH2Br2), bromodichloromethane (CHBrCl2), chlorodibromomethane (CHClBr2), were measured in the upper water column (5-750 m) in the eastern Pacific. Inorganic nutrient, pigment concentrations, and picoplankton cell counts were measured to determine biogeochemical factors that affect the production and distribution of these BrVSLS. Elevated concentrations of BrVSLS were observed in coastal and tropical seawater. Concentration maxima for CHBr3, CH2Br2, and CHClBr2 were observed below the mixed layer, near the subsurface chlorophyll a maxima, which suggest BrVSLS production may be related to photosynthetic biomass production. Our results also suggest that heterotrophic bacteria may also contribute to CH2Br2 and CHBrCl2 production in the water column. The maximum CHBrCl2 concentration was observed at a depth much deeper than the euphotic zone, which suggests sources other than photosynthetic biomass. Elevated CHBrCl2 concentrations in deeper waters were coincident with elevated CHCl3 concentrations, which may be an evidence for successive chlorine substitution of CHBr3 in deeper and older water masses.

Liu, Yina; Yvon-Lewis, Shari A.; Thornton, Daniel C. O.; Campbell, Lisa; Bianchi, Thomas S.

2013-05-01

147

Large-Scale, Short-Lived Subduction of the Western Gneiss Region Ultrahigh-Pressure Terrane  

NASA Astrophysics Data System (ADS)

The Western Gneiss Region (WGR) of Norway includes one of Earth's giant ultrahigh-pressure (UHP) terranes. Understanding the subduction and exhumation of this >60,000 km2 area is relevant to a range of processes, including collisional orogenesis, reworking of the continents, and the global geochemical cycle. Important aspects that remain unanswered include the spatial and temporal style of subduction. Was the crust subducted as smaller slivers one at a time, or as one larger unit, all at the same time? The WGR exhibits consistent ages of ~415-400 Ma, 100+ km along strike, but no ages have been identified at an equivalent distance across strike. To address this issue we have determined the age of one of the easternmost eclogites identified in the WGR, a retrogressed eclogite from Lesja. Seven fractions of this sample were analyzed; six of them yield identical U/Pb ages, however, they are slightly discordant. The seventh fraction is anomalously young and interpreted to have suffered lead loss. A weighted-mean 206Pb/238U age of 408.0 ± 1.7 Ma is obtained from the six older fractions; an age that is within the range of U/Pb, Sm/Nd, and Lu/Hf ages from the western portion of the WGR. The similarity in ages from 100+ km north to south and 100+ km east to west indicate that large portions of the continental crust were subducted in a short-lived event, if not en masse.

Kylander-Clark, A. R.; Hacker, B. R.; Corfu, F.

2006-12-01

148

Simulating Supernova Injection of Short Lived Radionuclides with Consideration of the Solar Birth Environment  

NASA Astrophysics Data System (ADS)

The existence of short-lived radionuclides (SLRNs) in the early solar system above their background galactic abundances is well accepted. Studies into the relative abundances and possible sources for radioisotopes indicate a model with three separate sources for the total abundance of SLRNs: the background galactic value, material from some nearby stellar source, and in-situ creation by the early active Sun. A type II SN may be the most likely source for the stellar component, specifically 60Fe. The geometric details of the stellar birth are largely unknown despite evidence that the presolar cloud was not isolated. From a hydrodynamic perspective, the injection of SLRNs may be difficult because of intervening material between the core and the explosion necessary to slow the shock speed enough that the core is compressed rather than shredded. For the SN component it is vital to understand how SN ejecta can reach a core and whether certain SN/cloud environments are precluded by the hydrodynamics. We present Zeus-2D simulations studying the possibility of SLRN injection into a presolar core that is part of a larger cloud complex.

Davis, Keith W.; Leising, M. D.

2006-12-01

149

Integrated measurements of short-lived 222Rn progeny by rotating filters.  

PubMed

The dependence of the risk from inhalation of radon progeny on their disequilibrium suggests that the measurements of the time-integrated concentrations of each of the short-lived radon progeny are necessary for complete risk estimations. This paper presents a method that, in principle, allows the determination of the integrated specific volume activities in air of each of the radionuclides 218Po, 214Pb, 214Bi, 212Pb, and 212Bi. The method employs thermoluminescence detectors positioned around uniformly rotating filters. Two prototypes that are suitable for practical applications are described and mathematical expressions for data processing are given. Experiments with these "rotating filter dosimeters" were conducted in atmospheres radiologically dominated by 222Rn progeny. The comparison between the results obtained by the proposed method and those given by simultaneously conducted series of instantaneous grab-sampling measurements support the conclusion that the method works for 222Rn progeny. The method can be experimentally extended for 220Rn progeny as well as for unattached fractions. PMID:8387983

Pressyanov, D S; Guelev, M G; Pentchev, O J

1993-05-01

150

Electromagnetic moment investigation of two short-lived isomeric states in118Sb  

NASA Astrophysics Data System (ADS)

Two short-lived isomeric states in118Sb have been investigated by the118Sn( p, n),118Sn( d, 2n) and115In( ?, n) reactions. The TDPAD method on solid and liquid metallic targets was used to measure the electromagnetic moments of these states. The results of the experiments are: 10050_2005_Article_BF01411861_TeX2GIFE1.gif begin{gathered} T_{1/2} = 13.4{text{ }}(3){text{ }}ns I^? = 3^ - {text{ }}g = - 1.254(31){text{ }}|Q| = 0.25{text{ }}(5){text{ }}b, \\ T_{1/2} = 22.8{text{ }}(4){text{ }}ns I^? = 7^ + {text{ }}g = + 0.680(18){text{ }}|Q| > 1.4{text{ }}b. \\ Pure[? 2d_{5/2} ? v1h_{1{text{ }}1/2} ]_{3 - } and[? 1g_{9/2}^{ - 1} ? v2d_{5/2}^{ - 1} ]_{7 + } configurations have been established for the two isomeric states. An experimental evidence concerning the participation of the 1 g {9/2/-1} proton shell-model intruder excitation into the positive parity low-lying level structure of the odd-odd118Sb nucleus was obtained.

Dima, S.; Duma, M.; Ionescu-Bujor, M.; Iord?chescu, A.; Pascovici, G.; Stan-Sion, C.

1985-12-01

151

Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors  

SciTech Connect

The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively localized in vitro on tumor cells that expressed both antigens and were capable of effective tumor localization in in vivo studies.

Adams, Gregory P.

2004-11-24

152

Upper limits for the existence of long-lived isotopes of roentgenium in natural gold  

SciTech Connect

A sensitive search for isotopes of a superheavy element (SHE) in natural gold materials has been performed with accelerator mass spectrometry at the Vienna Environmental Research Accelerator, which is based on a 3-MV tandem accelerator. Because the most likely SHE in gold is roentgenium (Rg, Z = 111), the search concentrated on Rg isotopes. Two different mass regions were explored: (i) For the neutron-deficient isotopes {sup 261}Rg and {sup 265}Rg, abundance limits in gold of 3x10{sup -16} were reached (no events observed). This is in stark contrast to the findings of Marinov et al.[Int. J. Mod. Phys. E 18, 621 (2009)], who reported positive identification of these isotopes with inductively coupled plasma sector field mass spectrometry in the (1-10)x10{sup -10} abundance range. (ii) Theoretical models of SHEs predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. We therefore investigated eight heavy Rg isotopes, {sup A}Rg, A = 289, 290, 291, 292, 293, 294, 295, and 296. For six isotopes no events were observed, setting limits also in the 10{sup -16} abundance range. For {sup 291}Rg and {sup 294}Rg we observed two and nine events, respectively, which results in an abundance in the 10{sup -15} range. However, pileup of a particularly strong background in these cases makes a positive identification as Rg isotopes--even after pileup correction--unlikely.

Dellinger, F.; Kutschera, W.; Forstner, O.; Golser, R.; Priller, A.; Steier, P.; Wallner, A.; Winkler, G. [University of Vienna, Faculty of Physics, Vienna Environmental Research Accelerator (VERA) Laboratory, Waehringer Strasse 17, A-1090 Wien (Austria)

2011-01-15

153

Upper limits for the existence of long-lived isotopes of roentgenium in natural gold  

NASA Astrophysics Data System (ADS)

A sensitive search for isotopes of a superheavy element (SHE) in natural gold materials has been performed with accelerator mass spectrometry at the Vienna Environmental Research Accelerator, which is based on a 3-MV tandem accelerator. Because the most likely SHE in gold is roentgenium (Rg, Z = 111), the search concentrated on Rg isotopes. Two different mass regions were explored: (i) For the neutron-deficient isotopes Rg261 and Rg265, abundance limits in gold of 3×10-16 were reached (no events observed). This is in stark contrast to the findings of Marinov [Int. J. Mod. Phys. EIMPEER0218-301310.1142/S021830130901280X 18, 621 (2009)], who reported positive identification of these isotopes with inductively coupled plasma sector field mass spectrometry in the (1-10)×10-10 abundance range. (ii) Theoretical models of SHEs predict a region of increased stability around the proton and neutron shell closures of Z = 114 and N = 184. We therefore investigated eight heavy Rg isotopes, ARg, A = 289, 290, 291, 292, 293, 294, 295, and 296. For six isotopes no events were observed, setting limits also in the 10-16 abundance range. For Rg291 and Rg294 we observed two and nine events, respectively, which results in an abundance in the 10-15 range. However, pileup of a particularly strong background in these cases makes a positive identification as Rg isotopes—even after pileup correction—unlikely.

Dellinger, F.; Kutschera, W.; Forstner, O.; Golser, R.; Priller, A.; Steier, P.; Wallner, A.; Winkler, G.

2011-01-01

154

Prospect for Using Charge-Coupled Devices in Precise Vertex Detectors for Short-Lived Particle Decays.  

National Technical Information Service (NTIS)

Versions of the vertex detector (VD) with charge coupling devices (CCD) are considered. VD basic characteristics are given. The experimental data on CCD show that VD With CCD is a promising device for experiments on short-lived particles with r < or appro...

S. V. Golovkin V. I. Rykalin

1984-01-01

155

Technical Note: Ensuring consistent, global measurements of short-lived halocarbon gases in the ocean and atmosphere  

Microsoft Academic Search

Short-lived halocarbons are significant sources of reactive halogen in the troposphere and likely the lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the impact of fluxes of these gases on marine boundary layer oxidation and lower stratospheric ozone-depletion processes. Despite the body of literature increasing substantially over recent years, calibration issues complicate comparison

J. H. Butler; T. G. Bell; B. D. Hall; B. Quack; L. J. Carpenter; J. Williams

2009-01-01

156

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere  

Microsoft Academic Search

Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of literature increasing substantially over recent years, calibration issues complicate the comparison of

J. H. Butler; T. G. Bell; B. D. Hall; B. Quack; L. J. Carpenter; J. Williams

2010-01-01

157

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere  

Microsoft Academic Search

Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of liter- ature increasing substantially over recent years, calibration issues complicate the comparison

J. H. Butler; T. G. Bell; B. D. Hall; B. Quack; L. J. Carpenter; J. Williams

2010-01-01

158

Thyroid Cancer in the Marshallese: Relative Risk of Short-Lived Internal Emitters and External Radiation Exposure.  

National Technical Information Service (NTIS)

In a study of the comparative effects of internal versus external irradiation of the thyroid in young people, we determined that the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times less thyroid cance...

E. T. Lessard A. B. Brill W. H. Adams

1985-01-01

159

Genome-wide determination of RNA stability reveals hundreds of short-lived noncoding transcripts in mammals  

PubMed Central

Mammalian genomes produce huge numbers of noncoding RNAs (ncRNAs). However, the functions of most ncRNAs are unclear, and novel techniques that can distinguish functional ncRNAs are needed. Studies of mRNAs have revealed that the half-life of each mRNA is closely related to its physiological function, raising the possibility that the RNA stability of an ncRNA reflects its function. In this study, we first determined the half-lives of 11,052 mRNAs and 1418 ncRNAs in HeLa Tet-off (TO) cells by developing a novel genome-wide method, which we named 5?-bromo-uridine immunoprecipitation chase–deep sequencing analysis (BRIC-seq). This method involved pulse-labeling endogenous RNAs with 5?-bromo-uridine and measuring the ongoing decrease in RNA levels over time using multifaceted deep sequencing. By analyzing the relationship between RNA half-lives and functional categories, we found that RNAs with a long half-life (t1/2 ? 4 h) contained a significant proportion of ncRNAs, as well as mRNAs involved in housekeeping functions, whereas RNAs with a short half-life (t1/2 < 4 h) included known regulatory ncRNAs and regulatory mRNAs. The stabilities of a significant set of short-lived ncRNAs are regulated by external stimuli, such as retinoic acid treatment. In particular, we identified and characterized several novel long ncRNAs involved in cell proliferation from the group of short-lived ncRNAs. We designated this novel class of ncRNAs with a short half-life as Short-Lived noncoding Transcripts (SLiTs). We propose that the strategy of monitoring RNA half-life will provide a powerful tool for investigating hitherto functionally uncharacterized regulatory RNAs.

Tani, Hidenori; Mizutani, Rena; Salam, Kazi Abdus; Tano, Keiko; Ijiri, Kenichi; Wakamatsu, Ai; Isogai, Takao; Suzuki, Yutaka; Akimitsu, Nobuyoshi

2012-01-01

160

The study of short-lived nuclei in the region Z =59–68  

Microsoft Academic Search

ß+ -ray endpoint energies for mass-separated samples of neutron deficient Rare-Earth isotopes have been measured using an intrinsic germanium detector. QEC values have been obtained and new isomeric states have been identified for the first time.

G. D. Alkhazov; K. A. Mezilev; Yu. N. Novikov; N. Ganbaatar; K. Ya. Gromov; V. G. Kalinnikov; A. Potempa; E. Sieniawski; F. Tarkanyi

1983-01-01

161

The study of short-lived nuclei in the region Z=59 68  

Microsoft Academic Search

beta + -ray endpoint energies for mass-separated samples of neutron deficient Rare-Earth isotopes have been measured using an intrinsic germanium detector. QEC values have been obtained and new isomeric states have been identified for the first time.

G. D. Alkhazov; K. A. Mezilev; Yu. N. Novikov; N. Ganbaatar; K. Ya. Gromov; V. G. Kalinnikov; A. Potempa; E. Sieniawski; F. Tarkanyi

1983-01-01

162

Increased Concentrations of Short-Lived Decay-Series Radionuclides in Groundwaters Underneath the Nopal I Uranium Deposit at Pena Blanca, Mexico  

NASA Astrophysics Data System (ADS)

The Nopal I uranium ore deposit at Pena Blanca, Mexico, located at > 200 meters above the groundwater table, provides an ideal natural analog for quantifying the effectiveness of geological barrier for isolation of radioactive waste nuclides from reaching the human environments through ground water transport. To fulfill such natural analog studies, three wells (PB1, PB2, and PB3 respectively) were drilled at the site from the land surface down to the saturated groundwater zone and ground waters were collected from each of these wells through large- volume sampling/in-situ Mn-filter filtration for analyses of short-lived uranium/thorium-series radionuclides. Our measurements from PB1 show that the groundwater standing in the hole has much lower 222Rn activity than the freshly pumped groundwater. From this change in 222Rn activity, we estimate the residence time of groundwater in PB1 to be about 20 days. Our measurements also show that the activities of short-lived radioisotopes of Th (234Th), Ra (228Ra, 224Ra, 223Ra), Rn (222Rn), Pb (210Pb), and Po (210Po) in PB1, PB2, and PB3 are all significantly higher than those from the other wells near the Nopal I site. These high activities provide evidence for the enrichment of long-lived U and Ra isotopes in the groundwater as well as in the associated adsorbed phases on the fractured aquifer rocks underneath the ore deposit. Such enrichment suggests a rapid dissolution of U and Ra isotopes from the uranium ore deposit in the vadose zone and the subsequent migration to the groundwater underneath. A reactive transport model can be established to characterize the in-situ transport of radionuclides at the site. The observed change of 222Rn activity at PB1 also suggests that the measured high radioactivityies in ground waters from the site isare not an artifact of drilling operations. However, further studies are needed to assess if or to what extent the radionuclide migration is affected by the previous mining activities at the site.

Luo, S.; Ku, T.; Todd, V.; Murrell, M. T.; Dinsmoor, J. C.

2007-05-01

163

Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters  

NASA Astrophysics Data System (ADS)

A new method utilizing alpha particles to treat solid tumors is presented. Tumors are treated with interstitial radioactive sources which continually release short-lived alpha emitting atoms from their surface. The atoms disperse inside the tumor, delivering a high dose through their alpha decays. We implement this scheme using thin wire sources impregnated with 224Ra, which release by recoil 220Rn, 216Po and 212Pb atoms. This work aims to demonstrate the feasibility of our method by measuring the activity patterns of the released radionuclides in experimental tumors. Sources carrying 224Ra activities in the range 10-130 kBq were used in experiments on murine squamous cell carcinoma tumors. These included gamma spectroscopy of the dissected tumors and major organs, Fuji-plate autoradiography of histological tumor sections and tissue damage detection by Hematoxylin-Eosin staining. The measurements focused on 212Pb and 212Bi. The 220Rn/216Po distribution was treated theoretically using a simple diffusion model. A simplified scheme was used to convert measured 212Pb activities to absorbed dose estimates. Both physical and histological measurements confirmed the formation of a 5-7 mm diameter necrotic region receiving a therapeutic alpha-particle dose around the source. The necrotic regions shape closely corresponded to the measured activity patterns. 212Pb was found to leave the tumor through the blood at a rate which decreased with tumor mass. Our results suggest that the proposed method, termed DART (diffusing alpha-emitters radiation therapy), may potentially be useful for the treatment of human patients.

Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I.

2007-08-01

164

Polyhalogenated Very Short Live Substances in the Atlantic Ocean, and their Linkages with Ocean Primary Production  

NASA Astrophysics Data System (ADS)

The Halocarbon Air-Sea Transect - Atlantic (HalocAST-A) cruise was conducted aboard FS Polarstern during the ANT-XXVII/1 expedition. The ship departed from Bremerhaven, Germany on October 25th and arrived in Cape Town, South Africa on November 24th in 2010. The HalocAST-A cruise was devoted to studying air-sea fluxes of a suite of halocarbon compounds. Atmospheric mixing ratios and seawater concentrations of the halocarbons were continuously measured with the gas chromatograph - mass spectrometer (GC-MS). This study focuses on the polyhalogenated very short lived substances (VSLSs) such as bromoform (CHBr3), dibromomethane (CH2Br2), chlorodibromomethane (CHClBr2), and bromodichloromethane (CHBrCl2). The goal of this study is to examine the distributions of these compounds and possible relationship between their emissions and oceanic primary production. Therefore, along with the halocarbon concentrations, parameters like dissolved organic carbon concentrations, nutrient concentrations, pigment concentrations, and picoplankton and heterotrophic bacteria counts were also determined. The observed saturation anomalies indicated these VSLSs were supersaturated for almost the entire duration of the cruise. The highest seawater concentrations for these compounds were observed near the Canary Islands. Air mixing ratios were also elevated in this region. The net fluxes for CHBr3, CH2Br2, CHClBr2, and CHBrCl2 were 13.8 nmol m-2 d-1, 4.5 nmol m-2 d-1, 4.5 nmol m-2 d-1 and 1.2 nmol m-2 d-1, respectively. During the HalocAST-A cruise, these compounds exhibit similar trends with total chlorophyll a. Contributions from selected phytoplankton group will be further assessed through the use of individual pigment biomarkers.

Liu, Y.; Yvon-Lewis, S. A.; Hu, L.; Bianchi, T. S.; Campbell, L.; Smith, R. W.

2011-12-01

165

Longitudinal analysis of Plantago: adaptive benefits of iteroparity in a short-lived, herbaceous perennial  

PubMed Central

Theory suggests that iteroparity may confer greater fitness than semelparity in situations in which temporal environmental variation is high and unpredictable. Variable age-specific mortality, density dependence, and other factors may also favor iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater numbers of reproductive years in a study of reproductive schedules in an experimental population of a short-lived polycarpic perennial, Plantago lanceolata. A large experimental population was established that included four cohorts with similar genetic structure. Individuals were censused for mortality, size, and reproduction for seven years. Plants experienced variable numbers of reproductive years, but one or two years were most common (~46.7% of the population reproduced only once). The probability of flowering at least once prior to death was determined strongly by extrinsic, environmental or intrinsic but environmentally influenced variables, including early-life size, cohort, and block, but also varied with a number of interactions involving paternal lineage. Maternal effects explained small but significant components of the variance in the number of reproductive years among individuals in each cohort, while paternal effects were significant in only two cohorts. Number of reproductive years contributed significantly to fitness in this system, more so than all other variables tested, although most of the variation in relative fitness may be attributed ultimately to environmental influences. We suggest that the high proportion of each cohort composed of plants reproducing only once may be due to environmental constraints on either growth or size. Such environmental influences, particularly on early life size, may result in small but important indirect effects on fitness.

Shefferson, Richard P.; Roach, Deborah A.

2010-01-01

166

Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters.  

PubMed

A new method utilizing alpha particles to treat solid tumors is presented. Tumors are treated with interstitial radioactive sources which continually release short-lived alpha emitting atoms from their surface. The atoms disperse inside the tumor, delivering a high dose through their alpha decays. We implement this scheme using thin wire sources impregnated with (224)Ra, which release by recoil (220)Rn, (216)Po and (212)Pb atoms. This work aims to demonstrate the feasibility of our method by measuring the activity patterns of the released radionuclides in experimental tumors. Sources carrying (224)Ra activities in the range 10-130 kBq were used in experiments on murine squamous cell carcinoma tumors. These included gamma spectroscopy of the dissected tumors and major organs, Fuji-plate autoradiography of histological tumor sections and tissue damage detection by Hematoxylin-Eosin staining. The measurements focused on (212)Pb and (212)Bi. The (220)Rn/(216)Po distribution was treated theoretically using a simple diffusion model. A simplified scheme was used to convert measured (212)Pb activities to absorbed dose estimates. Both physical and histological measurements confirmed the formation of a 5-7 mm diameter necrotic region receiving a therapeutic alpha-particle dose around the source. The necrotic regions shape closely corresponded to the measured activity patterns. (212)Pb was found to leave the tumor through the blood at a rate which decreased with tumor mass. Our results suggest that the proposed method, termed DART (diffusing alpha-emitters radiation therapy), may potentially be useful for the treatment of human patients. PMID:17671351

Arazi, L; Cooks, T; Schmidt, M; Keisari, Y; Kelson, I

2007-08-01

167

A LOWER INITIAL ABUNDANCE OF SHORT-LIVED {sup 41}Ca IN THE EARLY SOLAR SYSTEM AND ITS IMPLICATIONS FOR SOLAR SYSTEM FORMATION  

SciTech Connect

The short-lived radionuclide {sup 41}Ca plays an important role in constraining the immediate astrophysical environment and the formation timescale of the nascent solar system due to its extremely short half-life (0.1 Myr). Nearly 20 years ago, the initial ratio of {sup 41}Ca/{sup 40}Ca in the solar system was determined to be (1.41 {+-} 0.14) Multiplication-Sign 10{sup -8}, primarily based on two Ca-Al-rich Inclusions (CAIs) from the CV chondrite Efremovka. With an advanced analytical technique for isotopic measurements, we reanalyzed the potassium isotopic compositions of the two Efremovka CAIs and inferred the initial ratios of {sup 41}Ca/{sup 40}Ca to be (2.6 {+-} 0.9) Multiplication-Sign 10{sup -9} and (1.4 {+-} 0.6) Multiplication-Sign 10{sup -9} (2{sigma}), a factor of 7-10 lower than the previously inferred value. Considering possible thermal processing that led to lower {sup 26}Al/{sup 27}Al ratios in the two CAIs, we propose that the true solar system initial value of {sup 41}Ca/{sup 40}Ca should have been {approx}4.2 Multiplication-Sign 10{sup -9}. Synchronicity could have existed between {sup 26}Al and {sup 41}Ca, indicating a uniform distribution of the two radionuclides at the time of CAI formation. The new initial {sup 41}Ca abundance is 4-16 times lower than the calculated value for steady-state galactic nucleosynthesis. Therefore, {sup 41}Ca could have originated as part of molecular cloud materials with a free decay time of 0.2-0.4 Myr. Alternative possibilities, such as a last-minute input from a stellar source and early solar system irradiation, could not be definitively ruled out. This underscores the need for more data from diverse CAIs to determine the true astrophysical origin of {sup 41}Ca.

Liu, Ming-Chang [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan (China); Chaussidon, Marc [Centre de Recherches Petrographiques et Geochimiques, CNRS, Nancy (France); Srinivasan, Gopalan [Center for Earth Science, Indian Institute of Science, Bangalore (India); McKeegan, Kevin D., E-mail: mcliu@asiaa.sinica.edu.tw [Department of Earth and Space Sciences, UCLA, Los Angeles, CA (United States)

2012-12-20

168

Osteosarcoma risk after simultaneous incorporation of the long-lived radionuclide sup 227 Ac and the short-lived radionuclide sup 227 Th  

SciTech Connect

The effect of injection of 1.85 kBq/kg of the long-lived radionuclide {sup 227}Ac on the induction of osteosarcomas in female NMRI mice by different dose levels (18.5, 74, and 185 kBq/kg) of the short-lived radionuclide {sup 227}Th was investigated. The highest absolute osteosarcoma incidence was observed with the highest doses of {sup 227}Th. Addition of {sup 227}Ac resulted in an additional osteosarcoma incidence only at the lowest dose of {sup 227}Th and did not affect the osteosarcoma incidence resulting from higher doses of {sup 227}Th. The longest times to tumor appearance were observed with {sup 227}Ac alone. The latent period in two different age groups (4 weeks and 10-12 weeks) appeared to be similar following injection with combined doses of {sup 227}Th and {sup 227}Ac but different after injection of each radionuclide alone.

Mueller, W.A.M.; Murray, A.B.; Linzner, U.; Luz, A. (GSF-Institut fuer Pathologie, Neuherberg (Germany, F.R.))

1990-01-01

169

Reduction of short-lived atmospheric pollutant emissions as an alternative strategy for climate-change moderation  

NASA Astrophysics Data System (ADS)

The current state of studies on short-lived atmospheric constituents (greenhouse gases and aerosols) is reviewed. They have short atmospheric lifetimes (from several days to a few years) and can significantly affect the environment and climate. We propose reducing the emissions of these constituents as an alternative to the reduction of man-made carbon dioxide releases. We consider methane, hydrofluorocarbons, tropospheric ozone, and various aerosols (primarily, black carbon); discuss their atmospheric sources and destruction mechanisms; evaluate their content, atmospheric emissions, and climate impacts; and recommend efficient actions for the nearest future.

Karol', I. L.; Kiselev, A. A.; Genikhovich, E. L.; Chicherin, S. S.

2013-09-01

170

Solar system genealogy revealed by extinct short-lived radionuclides in meteorites  

NASA Astrophysics Data System (ADS)

Context. Little is known about the stellar environment and the genealogy of our solar system. Short-lived radionuclides (SLRs, mean lifetime ? shorter than 100 Myr) that were present in the solar protoplanetary disk 4.56 Gyr ago could potentially provide insight into that key aspect of our history, were their origin understood. Aims: Previous models failed to provide a reasonable explanation of the abundance of two key SLRs, 26Al (?26 = 1.1 Myr) and 60Fe (?60 = 3.7 Myr), at the birth of the solar system by requiring unlikely astrophysical conditions. Our aim is to propose a coherent and generic solution based on the most recent understanding of star-forming mechanisms. Methods: Iron-60 in the nascent solar system is shown to have been produced by a diversity of supernovae belonging to a first generation of stars in a giant molecular cloud. Aluminum-26 is delivered into a dense collected shell by a single massive star wind belonging to a second star generation. The Sun formed in the collected shell as part of a third stellar generation. Aluminum-26 yields used in our calculation are based on new rotating stellar models in which 26Al is present in stellar winds during the star main sequence rather than during the Wolf-Rayet phase alone. Our scenario eventually constrains the time sequence of the formation of the two stellar generations that just preceded the solar system formation, along with the number of stars born in these two generations. Results: We propose a generic explanation for the past presence of SLRs in the nascent solar system, based on a collect-injection-and-collapse mechanism, occurring on a diversity of spatial/temporal scales. In that model, the presence of SLRs with a diversity of mean lifetimes in the solar protoplanetary disk is simply the fossilized record of sequential star formation within a hierarchical interstellar medium. We identify the genealogy of our solar system's three star generations earlier. In particular, we show that our Sun was born together with a few hundred stars in a dense collected shell situated at a distance of 5-10 pc from a parent massive star having a mass greater than about 30 solar masses and belonging to a cluster containing ~1200 stars.

Gounelle, M.; Meynet, G.

2012-09-01

171

Fast-neutron activation of long-lived isotopes in enriched Ge  

SciTech Connect

We measured the production of {sup 57}Co, {sup 54}Mn, {sup 68}Ge, {sup 65}Zn, and {sup 60}Co in a sample of Ge enriched in isotope 76 due to high-energy neutron interactions. These isotopes, especially {sup 68}Ge, are critical in understanding background in Ge detectors used for double {beta} decay experiments. They are produced by cosmogenic-neutron interactions in the detectors while they reside on the Earth's surface. These production rates were measured at neutron energies of a few hundred MeV. We compared the measured production to that predicted by cross-section calculations based on CEM03.02. The cross-section calculations overpredict our measurements by approximately a factor of 3 depending on isotope. We then use the measured cosmic-ray neutron flux, our measurements, and the CEM03.02 cross sections to predict the cosmogenic production rate of these isotopes. The uncertainty in extrapolating the cross-section model to higher energies dominates the total uncertainty in the cosmogenic production rate.

Elliott, S. R.; Guiseppe, V. E.; LaRoque, B. H.; Johnson, R. A.; Mashnik, S. G. [Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics, University of Washington, Seattle Washington, 98195 (United States); XCP Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2010-11-15

172

Results of the 2010 National Radiation Protection Institute intercomparison of radon and its short-lived decay product continuous monitors.  

PubMed

During the Sixth European Conference on Protection Against Radon at Home and at Work held in autumn 2010 in Prague, the first intercomparison of continuous radon and its short-lived decay product monitors was organised and held by the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. Eight laboratories submitted eight continuous radon monitors, two electronic monitors, three passive integral systems based on charcoal and three continuous radon short-lived decay product monitors. The intercomparison included exposures to both the radon gas concentration and equivalent equilibrium radon concentration (EEC) under different ambient conditions similar to the ones in dwellings. In particular, the influence of the equilibrium factor F, unattached fraction of EEC f(p) and absolute air humidity were investigated. The results of the radon gas measurements were performed on a calibration level of about 8  kBq m(-3). The results of all monitors were compared with the reference NRPI monitor. PMID:21471124

Jílek, K; Marušiaková, M

2011-04-06

173

Large-Scale Mass Measurements of Short-Lived Nuclides with the Isochronous Mass Spectrometry at GSI  

NASA Astrophysics Data System (ADS)

Precise mass measurements of short-lived exotic nuclei are very important for the understanding of basic nuclear structure physics and astrophysical nucleosynthesis in nature, as well as for the test and the development of theoretical nuclear mass models. At GSI, the Isochronous Mass Spectrometry (IMS) dedicated to mass measurements of short-lived nuclides was developed. In this contribution, the IMS technique is briefly reviewed. Recently, the first large-scale measurement on the 238U fission fragment was done successfully. The measured mass values are in excellent agreement with the recent Penning trap data, however, they show a systematical deviation from the values in the latest atomic mass evaluation. Some representative results from this experiment will be presented, including their impact on nuclear structure physics and astrophysical r-process nucleosynthesis.

Sun, B.; Knöbel, R.; Litvinov, Yu. A.; Nakajima, S.; Geissel, H.; Meng, J.; Beckert, K.; Bosch, F.; Boutin, D.; Brandau, C.; Chen, L.; Cullen, I. J.; Dimopoulou, C.; Fabian, B.; Hausmann, M.; Klepper, O.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S. A.; Mazzocco, M.; Montes, F.; Münzenberg, G.; Musumarra, A.; Nociforo, C.; Nolden, F.; Ohtsubo, T.; Ozawa, A.; Patyk, Z.; Plaß, W. R.; Scheidenberger, C.; Steck, M.; Suzuki, T.; Walker, P. M.; Weick, H.; Winckler, N.; Winkler, M.; Yamaguchi, T.

174

Nucleon-Alpha Particle Disequilibrium and Short-Lived r-Process Radioactivities  

NASA Astrophysics Data System (ADS)

r-Process yields can be extremely sensitive to expansion parameters when a persistent disequilibrium between free nucleons and alpha particles is present. This may provide a natural scenario for understanding the variation of heavy and light r-process isotopes in different r-process events.

Meyer, B. S.; Clayton, D. D.; Chellapilla, S.; The, L.-S.

2002-03-01

175

Age-specific, density-dependent and environment-based mortality of a short-lived perennial herb  

Microsoft Academic Search

Density-independent and density-dependent processes affect plant mortality. Although less well understood, age-specific mortality can also play an important role in plant mortality. The goal of this study was to analyse sev- eral factors accounting for mortality in the Mediterranean short-lived peren- nial herb Lobularia maritima. We followed three cohorts of plants (from emergence to death) during 4 years in field

F. X. Pico ´; J. Retana

2008-01-01

176

An activation analysis system for short-lived radioisotopes including automatic dead-time corrections with a microcomputer  

Microsoft Academic Search

A system based on an IBM-PC microcomputer coupled to a Canberra Series 80 multichannel analyser has been developed for activation analysis with short-lived radioisotopes. The data transfer program can store up to 77 gamma-ray spectra on a floppy disk. A spectrum analysis program, DVC, has been written to determine peak areas interactively, to correct the counting losses, and to calculate

G. Kennedy; J. Marcotte; L. Zikovsky

1987-01-01

177

SProtP: A Web Server to Recognize Those Short-Lived Proteins Based on Sequence-Derived Features in Human Cells  

Microsoft Academic Search

Protein turnover metabolism plays important roles in cell cycle progression, signal transduction, and differentiation. Those proteins with short half-lives are involved in various regulatory processes. To better understand the regulation of cell process, it is important to study the key sequence-derived factors affecting short-lived protein degradation. Until now, most of protein half-lives are still unknown due to the difficulties of

Xiaofeng Song; Tao Zhou; Hao Jia; Xuejiang Guo; Xiaobai Zhang; Ping Han; Jiahao Sha

2011-01-01

178

First Isochronous Time-of-Flight Mass Measurements of Short-Lived Projectile Fragments in the ESR  

SciTech Connect

A new method for precise mass measurements of short-lived hot nuclei is presented. These nuclei were produced via projectile fragmentation, separated with the FRS and injected into the storage ring ESR being operated in the isochronous mode. The revolution time of the ions is measured with a time-of-flight detector sensitive to single particles. This new method allows access to exotic nuclei with half-lives in the microsecond region. First results from this novel method obtained with measurements on neutron-deficient fragments of a chromium primary beam with half-lives down to 50 ms are reported. A precision of {delta}m/m {<=} 5 {center_dot} 10{sup -6} has been achieved.

Stadlmann, J.; Geissel, H.; Hausmann, M.; Nolden, F.; Radon, T.; Schatz, H.; Scheidenberger, C.; Attallah, F.; Beckert, K.; Bosch, F.; Falch, M.; Franczak, B.; Franzke, B.; Kerscher, Th.; Klepper, O.; Kluge, H.J.; Kozhuharov, C.; Loebner, K.E.G.; Muenzenberg, G.; Novikov, Yu.N.; Steck, M.; Sun, Z.; Suemmerer, K.; Weick, H.; Wollnik, H.

2000-12-31

179

Proline-rich tyrosine kinase-2 is critical for CD8 T-cell short-lived effector fate  

PubMed Central

T-cell interactions with antigen-presenting cells are important for CD8 T-cell effector or memory fate determination. The integrin leukocyte function-associated antigen-1 (LFA-1) mediates T-cell adhesion but the contribution of LFA-1–induced signaling pathways to T-cell responses is poorly understood. Here we demonstrate that proline-rich tyrosine kinase-2 (PYK2) deficiency impairs CD8 T-cell activation by synergistic LFA-1 and T-cell receptor stimulation. Furthermore, PYK2 is essential for LFA-1-mediated CD8 T-cell adhesion and LFA-1 costimulation of CD8 T-cell migration. During lymphocytic choriomeningitis virus infection in vivo, PYK2 deficiency results in a specific loss of short-lived effector CD8 T cells but does not affect memory-precursor CD8 T-cell development. Similarly, lack of LFA-1 primarily impairs the generation of short-lived effector cells. Thus, PYK2 facilitates LFA-1–dependent CD8 T-cell responses and promotes CD8 T-cell short-lived effector fate, suggesting that PYK2 may be an interesting therapeutic target to suppress exacerbated CD8 T-cell responses.

Beinke, Soren; Phee, Hyewon; Clingan, Jonathan M.; Schlessinger, Joseph; Matloubian, Mehrdad; Weiss, Arthur

2010-01-01

180

Identification of short-lived long non-coding RNAs as surrogate indicators for chemical stress response.  

PubMed

Abiotic and biotic stressors in human cells are often a result of sudden and/or frequent changes in environmental factors. The molecular response to stress involves elaborate modulation of gene expression and is of homeostatic, ecological, and evolutionary importance. Although attention has primarily focused on signaling pathways and protein networks, long non-coding RNAs (ncRNAs) are increasingly involved in the molecular mechanisms associated with responses to cellular stresses. We identified six novel short-lived long ncRNAs (MIR22HG, GABPB-AS1, LINC00152, IDI2-AS1, SNHG15, and FLJ33630) that responded to chemical stressors (cisplatin, cycloheximide, and mercury (II) oxide) in HeLa Tet-off cells. Our results indicate that short-lived long ncRNAs respond to general and specific chemical stressors. The expression levels of the short-lived long ncRNAs were elevated because of prolonged decay rates in response to chemical stressors and interruption of RNA degradation pathways. We propose that these long ncRNAs have the potential to be surrogate indicators of cellular stress responses. PMID:24036268

Tani, Hidenori; Torimura, Masaki

2013-09-10

181

Use of short half-life cosmogenic isotopes to quantify sediment mixing and transport in karst conduits  

NASA Astrophysics Data System (ADS)

Particulate inorganic carbon (PIC) transport and flux in karst aquifers is poorly understood. Methods to quantify PIC flux are needed in order to account for total inorganic carbon removal (chemical plus mechanical) from karst settings. Quantifying PIC flux will allow more accurate calculations of landscape denudation and global carbon sink processes. The study concentrates on the critical processes of the suspended sediment component of mass flux - surface soil/stored sediment mixing, transport rates and distance, and sediment storage times. The primary objective of the study is to describe transport and mixing with the resolution of single storm-flow events. To quantify the transport processes, short half-life cosmogenic isotopes are utilized. The isotopes 7Be (t1/2 = 53d) and 210Pb (t1/2 = 22y) are the primary isotopes measured, and other potential isotopes such as 137Cs and 241Am are investigated. The study location is at Mammoth Cave National Park within the Logsdon River watershed. The Logsdon River conduit is continuously traversable underground for two kilometers. Background levels and input concentrations of isotopes are determined from soil samples taken at random locations in the catchment area, and suspended sediment collected from the primary sinking stream during a storm event. Suspended sediment was also collected from the downstream end of the conduit during the storm event. After the storm flow receded, fine sediment samples were taken from the cave stream at regular intervals to determine transport distances and mixing ratios along the conduit. Samples were analyzed with a Canberra Industries gamma ray spectrometer, counted for 24 hours to increase detection of low radionuclide activities. The measured activity levels of radionuclides in the samples were adjusted for decay from time of sampling using standard decay curves. The results of the study show that surface sediment mixing, transport and storage in karst conduits is a dynamic but potentially quantifiable process at the storm-event scale.

Paylor, R.

2011-12-01

182

Impact of preindustrial to present-day changes in short-lived pollutant emissions on atmospheric composition and climate forcing  

NASA Astrophysics Data System (ADS)

We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL AM3) and apply it to investigate the net impact of preindustrial (PI) to present (PD) changes in short-lived pollutant emissions (ozone precursors, sulfur dioxide, and carbonaceous aerosols) and methane concentration on atmospheric composition and climate forcing. The inclusion of online troposphere-stratosphere interactions, gas-aerosol chemistry, and aerosol-cloud interactions (including direct and indirect aerosol radiative effects) in AM3 enables a more complete representation of interactions among short-lived species, and thus their net climate impact, than was considered in previous climate assessments. The base AM3 simulation, driven with observed sea surface temperature (SST) and sea ice cover (SIC) over the period 1981-2007, generally reproduces the observed mean magnitude, spatial distribution, and seasonal cycle of tropospheric ozone and carbon monoxide. The global mean aerosol optical depth in our base simulation is within 5% of satellite measurements over the 1982-2006 time period. We conduct a pair of simulations in which only the short-lived pollutant emissions and methane concentrations are changed from PI (1860) to PD (2000) levels (i.e., SST, SIC, greenhouse gases, and ozone-depleting substances are held at PD levels). From the PI to PD, we find that changes in short-lived pollutant emissions and methane have caused the tropospheric ozone burden to increase by 39% and the global burdens of sulfate, black carbon, and organic carbon to increase by factors of 3, 2.4, and 1.4, respectively. Tropospheric hydroxyl concentration decreases by 7%, showing that increases in OH sinks (methane, carbon monoxide, nonmethane volatile organic compounds, and sulfur dioxide) dominate over sources (ozone and nitrogen oxides) in the model. Combined changes in tropospheric ozone and aerosols cause a net negative top-of-the-atmosphere radiative forcing perturbation (-1.05 W m-2) indicating that the negative forcing (direct plus indirect) from aerosol changes dominates over the positive forcing due to ozone increases, thus masking nearly half of the PI to PD positive forcing from long-lived greenhouse gases globally, consistent with other current generation chemistry-climate models.

Naik, Vaishali; Horowitz, Larry W.; Fiore, Arlene M.; Ginoux, Paul; Mao, Jingqiu; Aghedo, Adetutu M.; Levy, Hiram

2013-07-01

183

Comment on ``Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes''  

NASA Astrophysics Data System (ADS)

In their article “Existence of Long-Lived Isomeric States in Naturally-Occuring Neutron-Deficient Th Isotopes” [Phys. Rev. C 76, 021303 (2007)], Marinov fail to demonstrate that basic mass spectrometric protocols, such as abundance sensitivity, linearity, and freedom from possible interferences, have been met. In particular, the claim that four isomeric states of Th have been discovered, using an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS), with abundances from (1-10)×10-11 relative to Th232, cannot be accepted, given the known abundance sensitivities of other sector field mass spectrometers. Accelerator mass spectrometry is the only mass spectrometric methodology capable of measuring relative abundances of the magnitude claimed by Marinov

Barber, R. C.; de Laeter, J. R.

2009-04-01

184

Mood regulation in youth: research findings and clinical approaches to irritability and short-lived episodes of mania like symptoms  

PubMed Central

Purpose of review Mood regulation problems, such as severe chronic irritability or short episodes of mania like symptoms are common, impairing and a topic of intense recent interest to clinicians, researchers and the DSM-5 process. Here we review the most recent findings about these two presentations and discuss approaches to their treatment. Recent findings Longitudinal and genetic findings suggest that chronic irritability should be regarded as a mood problem that is distinct from bipolar disorder. A proportion of children with short (less than 4 days) episodes of mania like symptoms seem to progress to classical (Type I or II) bipolar disorder over time in US clinic samples. In a UK sample, such episodes were independently associated with psychosocial impairment. The evidence base for the treatment of either irritability or short-lived episodes to mania-like symptoms is still small. Clinicians should be cautious with extrapolating treatments from classical bipolar disorder to these mood regulation problems. CBT-based approaches targeting general mood regulation processes may be effective for cases with severe irritability or short episodes of mania like symptoms. Summary There is increasing research evidence for the importance of mood regulation problems in the form of either irritability or short episodes of mania like symptoms in youth. The evidence base for their drug treatment has yet to be developed. CBT-based interventions to modify processes of mood regulation may be a useful and safe intervention for patients with these presentations.

Leigh, Eleanor; Smith, Patrick; Milavic, Gordana; Stringaris, Argyris

2013-01-01

185

Excited states of tryptophan in cod parvalbumin. Identification of a short-lived emitting triplet state at room temperature.  

PubMed Central

The fluorescence and phosphorescence spectra of model indole compounds and of cod parvalbumin III, a protein containing a single tryptophan and no tyrosine, were examined in the time scale ranging from subnanoseconds to milliseconds at 25 degrees C in aqueous buffer. For both Ca- bound and Ca-free parvalbumin and for model indole compounds that contained a proton donor, a phosphorescent species emitting at 450 nm with a lifetime of approximately 20-40 ns could be identified. A longer-lived phosphorescence is also apparent; it has approximately the same absorption and emission spectrum as the short-lived triplet molecule. For Ca parvalbumin, the decay of the long-lived triplet tryptophan is roughly exponential with a lifetime of 4.7 ms at 25 degrees C whereas for N-acetyltryptophanamide in aqueous buffer the decay lifetime was 30 microseconds. In contrast, the lifetime of the long-lived tryptophan species is much shorter in the Ca-free protein compared with Ca parvalbumin, and the decay shows complex nonexponential kinetics over the entire time range from 100 ns to 1 ms. It is concluded that the photochemistry of tryptophan must take into account the existence of two excited triplet species and that there are quenching moieties within the protein matrix that decrease the phosphorescence yield in a dynamic manner for the Ca-depleted parvalbumin. In contrast, for Ca parvalbumin, the tryptophan site is rigid on the time scale of milliseconds.

Sudhakar, K; Phillips, C M; Williams, S A; Vanderkooi, J M

1993-01-01

186

VLA Observations Confirm Origin of Gamma Ray Bursts in Short-Lived Stars  

NASA Astrophysics Data System (ADS)

Radio telescope studies of the fiery afterglow of a Gamma Ray Burst have provided astronomers with the best clues yet about the origins of these tremendous cosmic cataclysms since their discovery more than 30 years ago. Observations with the National Science Foundation's (NSF) Very Large Array (VLA) radio telescope confirm that a blast seen to occur on March 29 had its origin in a star-forming region in a distant galaxy. "There are two leading theories for the causes of Gamma Ray Bursts," said Dale Frail of the NSF National Radio Astronomy Observatory (NRAO) in Socorro, NM. "According to one theory, the blasts occur in the death throes of pairs of old stars. The other requires them to arise from exploding, massive, short-lived stars that still reside within the star-forming gas and dust from which they formed. The VLA studies of the burst show that at least this one almost certainly occurred within a star-forming region. This result also explains why half of the Gamma Ray Burst afterglows are not detected by optical telescopes." Frail heads a VLA observing team including Greg Taylor, also of NRAO, and Shri Kulkarni of Caltech, that reported its findings to the American Astronomical Society meeting in San Diego, CA. The March 29 burst was seen clearly by radio telescopes (the accompanying image is GRB 980329 as seen by the VLA) but only very faintly with optical instruments. "That is extremely important," said Taylor. "This burst was very faint at visible wavelengths, brighter at infrared wavelengths and brighter still at radio wavelengths. This is a clear indication that the exploding object was surrounded by dust. Dust is most commonly found in star-forming regions." This strongly favors one of the two leading theories about Gamma Ray Bursts over the other. One explanation for these tremendously energetic fireballs is that a pair of superdense neutron stars collides. The other is that a single, very massive star explodes in a "hypernova," more powerful than a supernova, at the end of its normal life. The hypernova explosion, scientists believe, would come only a few million years after the giant star was formed, while it is still within the cloud of gas and dust from which it formed. Neutron stars, on the other hand, are formed by supernova explosions that give a "kick" to the resulting neutron star, propelling it at high speeds. An orbiting pair of neutron stars, astronomers think, would collide only after hundreds of millions of years of orbital decay, by which time they would be far away from the gas and dust of their birthplace. "The observations already have provided crucial insight; we intend to continue observing the relic of the March 29 burst with the VLA, and in the coming months, we will gain new information that will help further refine our ideas about these fireballs," Frail said. "We're going to learn about the size and expansion rate of the fireball and test predictions made by the models." "These observations indicate the extraordinary importance of radio astronomy for providing information that can be gained in no other way about one of the major frontier areas of astrophysics," said Hugh Van Horn, Director of the NSF's Division of Astronomical Sciences. The March 29 burst (GRB 980329) was the second such blast to have its afterglow detected at radio wavelengths. Last year, the VLA made the first radio detection of a GRB afterglow, finding radio emission coming from the location of a Gamma Ray Burst on May 8, 1997 (GRB 970508). "Of the world's radio telescopes, only the VLA has the sensitivity and resolving power to quickly detect these radio afterglows of Gamma Ray Bursts and study them in detail over extended periods of time," Taylor said. "Even so, we only see the brightest one-third of them. With upgraded capabilities at the VLA, as planned by NRAO, we will see them all." The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agr

1998-06-01

187

Harvard-MIT research program in short-lived radiopharmaceuticals. Progress report, March 1, 1983-February 29, 1984  

SciTech Connect

This report describes research efforts towards the achievement of a clearer understanding of the solution chemistry of technetium in order to facilitate the design of future clinical agents labeled with Tc-99m, the development of new receptor binding radiopharmaceuticals for the in vivo assessment of insulin receptors and for imaging the adrenal medulla and the brain, the examination of the utility of monoclonal antibodies and liposomes in the design of radiopharmaceuticals for diagnosis and therapy, and the synthesis of short-lived positron-emitting radiopharmaceuticals for transverse imaging of regional physiological processes.

Adelstein, S.J.; Brownell, G.L.

1984-02-01

188

Novel biogenic iodine-containing trihalomethanes and other short-lived halocarbons in the coastal East Atlantic  

Microsoft Academic Search

Reactive halogen photochemistry and its impact on tropospheric oxidant levels have recently attracted intense research interest following the observation of the iodine oxide radical at midlatitudes. During September 1998, short-lived organoiodines including CH3I, C2H5I, CH2ICl, CH2IBr, CH2I2, and the hitherto undetected CHIBr2, as well as the organobromines CHBr3, CH2Br2, CHBr2Cl2, CH3Br, and C2H5Br, were measured in air and seawater at

L. J. Carpenter; G. Malin; P. S. Liss; F. C. Küpper

2000-01-01

189

Effects of Soy-derived diets on plasma and liver lipids, glucose tolerance, and longevity in normal, long-lived and short-lived mice.  

PubMed

We examined the effects of diets based on a low isoflavone or a high isoflavone soy protein isolates in normal, growth-hormone receptor knockout and Ames dwarf, and Prop 1 (df) mice that are hypoinsulinemic, insulin-sensitive, and exceptionally long-lived, as well as in growth hormone transgenic mice that are hyperinsulinemic, insulin-resistant, dyslipidemic, and short-lived. Soybean diets tended to normalize plasma cholesterol levels in dwarf and transgenic mice, while low isoflavone diet reduced plasma triglycerides in most of the examined genotypes. The effects of low isoflavone and high isoflavone diets on the levels of free and esterified cholesterol in the liver were strongly genotype-dependent. Fasting blood glucose levels were reduced and glucose tolerance improved by both low isoflavone and high isoflavone diets in growth hormone-transgenic mice and in their normal siblings. Glucose tolerance was also improved by high-isoflavone diet in growth hormone receptor knockout mice. Lifespan was increased by low isoflavone diet in normal mice from two of the examined stocks. High isoflavone diet increased lifespan in normal animals from one line, but reduced lifespan of normal mice from a different line. We conclude that dietary soy protein intake can improve plasma and hepatic lipid profiles, reduce fasting glucose, enhance capacity for glucose tolerance, and prolong life, but all of these effects are strongly genotype-dependent. PMID:15326565

Bartke, A; Peluso, M R; Moretz, N; Wright, C; Bonkowski, M; Winters, T A; Shanahan, M F; Kopchick, J J; Banz, W J

2004-08-01

190

Alterations in oxygen consumption, respiratory quotient, and heat production in long-lived GHRKO and Ames dwarf mice, and short-lived bGH transgenic mice.  

PubMed

Growth hormone (GH) signaling influences longevity in mice, with decreased GH signaling associated with longer life span and increased GH signaling with shortened life span. A proposed mechanism through which GH signaling influences life span postulates that decreased GH signaling lowers metabolic rate, thus slowing aging by decreasing production of damaging free radicals. The influence of altered GH signaling on metabolism was tested by monitoring oxygen consumption (VO(2)), respiratory quotient (RQ), and heat production in long-lived GH receptor knockout (GHRKO) and Ames dwarf mice, and short-lived bovine GH-overexpressing transgenic (bGH TG) mice. Intriguingly, both GHRKO and Ames dwarf mice have increased VO(2) and heat per gram body weight, and decreased RQ, whereas bGH TG mice have decreased VO(2) and heat per gram body weight and increased RQ. In conclusion, decreased GH signaling associates with increased metabolism per body weight and may beneficially affect mitochondrial flexibility by increasing the capacity for fat oxidation; generally, GH excess produces opposite metabolic effects. PMID:19286975

Westbrook, Reyhan; Bonkowski, Michael S; Strader, April D; Bartke, Andrzej

2009-03-13

191

Alterations in Oxygen Consumption, Respiratory Quotient, and Heat Production in Long-Lived GHRKO and Ames Dwarf Mice, and Short-Lived bGH Transgenic Mice  

PubMed Central

Growth hormone (GH) signaling influences longevity in mice, with decreased GH signaling associated with longer life span and increased GH signaling with shortened life span. A proposed mechanism through which GH signaling influences life span postulates that decreased GH signaling lowers metabolic rate, thus slowing aging by decreasing production of damaging free radicals. The influence of altered GH signaling on metabolism was tested by monitoring oxygen consumption (VO2), respiratory quotient (RQ), and heat production in long-lived GH receptor knockout (GHRKO) and Ames dwarf mice, and short-lived bovine GH-overexpressing transgenic (bGH TG) mice. Intriguingly, both GHRKO and Ames dwarf mice have increased VO2 and heat per gram body weight, and decreased RQ, whereas bGH TG mice have decreased VO2 and heat per gram body weight and increased RQ. In conclusion, decreased GH signaling associates with increased metabolism per body weight and may beneficially affect mitochondrial flexibility by increasing the capacity for fat oxidation; generally, GH excess produces opposite metabolic effects.

Bonkowski, Michael S.; Strader, April D.; Bartke, Andrzej

2009-01-01

192

Atomic mass measurements of short-lived nuclides around the doubly-magic 208Pb  

NASA Astrophysics Data System (ADS)

Accurate atomic mass measurements of neutron-deficient and neutron-rich nuclides around the doubly-magic 208Pb and of neutron-rich cesium isotopes were performed with the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The masses of 145,147Cs, 181,183Tl, 186Tlm, 187Tlm, 196Tlm, 205Tl, 197Pbm, 208Pb, 190 197Bi, 209,215,216Bi, 203,205,229Fr, and 214,229,230Ra were determined. The obtained relative mass uncertainty in the range of 2×10 to 2×10 is not only required for safe identification of isomeric states but also allows mapping the detailed structure of the mass surface. A mass adjustment procedure was carried out and the results included into the Atomic Mass Evaluation. The resulting separation energies are discussed and the mass spectrometric and laser spectroscopic data are examined for possible correlations.

Weber, C.; Audi, G.; Beck, D.; Blaum, K.; Bollen, G.; Herfurth, F.; Kellerbauer, A.; Kluge, H.-J.; Lunney, D.; Schwarz, S.

2008-04-01

193

Rare Isotope Accelerators  

NASA Astrophysics Data System (ADS)

The next frontier for low-energy nuclear physics involves experimentation with accelerated beams of short-lived radioactive isotopes. A new facility, the Rare Isotope Accelerator (RIA), is proposed to produce large amount of these rare isotopes and post-accelerate them to energies relevant for studies in nuclear physics, astrophysics and the study of fundamental interactions at low energy. The basic science motivation for this facility will be introduced. The general facility layout, from the 400 kW heavy-ion superconducting linac used for production of the required isotopes to the novel production and extraction schemes and the highly efficient post-accelerator, will be presented. Special emphasis will be put on a number of technical breakthroughs and recent R&D results that enable this new facility.

Savard, Guy

2002-04-01

194

Short Lived Isomers in sup 211 Rn and sup 210 Rn.  

National Technical Information Service (NTIS)

Mean lives of excited states in sup 211 Rn and sup 210 Rn have been measured. For sup 211 Rn: 8169 keV (tau=3.3(3)ns), 7400 keV (2.1(5)ns), 6101 keV (41(2)ns), 5247 keV (5(2)ns), 3244 keV (3.9(8)ns), 2651 keV (9.6(4)ns). For sup 210 Rn: 8555 keV (2.6(3)ns...

A. R. Poletti G. D. Dracoulis S. J. Poletti A. P. Byrne A. E. Stuchbery

1985-01-01

195

Unusual negative photochromism via a short-lived imidazolyl radical of 1,1'-binaphthyl-bridged imidazole dimer.  

PubMed

We have synthesized a new photochromic compound that exhibits unusual negative photochromism, in which the stable colored species photochemically converts into the metastable colorless species via a short-lived radical. This compound has a 1,1'-binaphthyl moiety bridging the two diphenylimidazole units. Its photochemical properties were investigated by nanosecond laser flash photolysis. The colored species isomerizes to the colorless species upon exposure to visible light and thermally returns to the original colored species within 20 min at room temperature. Moreover, the photodecoloration reaction proceeds via a short-lived radical with a half-life of 9.4 ?s in benzene at room temperature. Both the colored and colorless species show the photoinduced homolytic bond cleavage reaction of the C-N bond between the nitrogen atom of the imidazole ring and the carbon atom of the 1-position of the 1,1'-binaphthyl moiety and that of the C-C bond between each of the carbon atoms of the 2-position of the imidazole ring, respectively, followed by their formation by rapid radical coupling. PMID:23402262

Hatano, Sayaka; Horino, Takeru; Tokita, Atsuhiro; Oshima, Toyoji; Abe, Jiro

2013-02-18

196

Transposon-Mediated Transgenesis in the Short-Lived African Killifish Nothobranchius furzeri, a Vertebrate Model for Aging  

PubMed Central

The African killifish Nothobranchius furzeri is the shortest-lived vertebrate that can be bred in captivity. N. furzeri comprises several wild-derived strains with striking differences in longevity ranging from 3 to 9 months, which makes it a powerful vertebrate model for aging research. The short life cycle of N. furzeri should also facilitate studies on adult traits that are specific to vertebrates. Although progress has been made to generate a genetic linkage map and to start sequencing the genome of N. furzeri, tools to genetically manipulate this species of fish have not yet been developed. Here, we report the first establishment of transgenesis in N. furzeri. We use the Tol2 transposase system to generate transgenic N. furzeri that express green fluorescent protein driven by the Xenopus cytoskeletal actin promoter or the zebrafish heat-shock protein 70 promoter. We successfully generate stable transgenic lines of N. furzeri with germline transmission of integrated transgene. The development of transgenesis in N. furzeri provides a powerful tool to investigate the mechanisms underlying aging and longevity in a short-lived vertebrate model. Transgenesis in this fish will also facilitate the study of other phenotypes, including adult tissue regeneration and cognitive behavior.

Valenzano, Dario Riccardo; Sharp, Sabrina; Brunet, Anne

2011-01-01

197

Short-lived organic trace gases in the UT/LS: Results from recent field campaigns. (Invited)  

NASA Astrophysics Data System (ADS)

Recent research campaigns in the tropics (TC-4 and AVE missions) and in the extra-tropics (START08) have included the measurement of trace gases from whole air sampling on the NASA WB-57 or NSF Gulfstream V aircraft. Measurements of a range of halocarbons, hydrocarbons, organic nitrates, and sulfur species were made during these missions to examine the role of short-lived organic gases in the UT/LS. The trace gas composition of the upper troposphere/lower stratosphere (UT/LS) region depends on emission sources, transport pathways, mixing rates and photochemical processing time. Because surface emissions include gases with a range of chemical lifetimes, and because different source emissions (e.g. marine boundary layer, anthropogenic emissions, biomass burning) can have different chemical signatures, the composition of the organic trace gases that are found in the UT/LS region have the potential to provide diagnostic information on air mass sources and transport time scales. Also, measurement of short-lived organic halogen gases in the UT/LS during these missions provides data to define the reactive halogen budget and the chemical boundary conditions for the stratospheric chemistry that affects ozone depletion rates. This presentation will highlight different aspects of these measurements that deal with transport pathways, transport rates, and halogen budgets.

Atlas, E. L.; Pan, L.; Schauffler, S.; Bowman, K. P.; Blake, D. R.; Meinardi, S.; Stone, D.; Lueb, R.; Zhu, X.; Pope, L.

2009-12-01

198

Production cross sections of short-lived silver radionuclides from natPd(p,xn) nuclear processes  

NASA Astrophysics Data System (ADS)

Production cross-sections of short-lived 103Ag, 104mAg and 104gAg radionuclides from proton-induced reactions on natural palladium (Pd) were measured up to 41 MeV by using a stacked-foil activation technique combined with high resolution ?-ray spectrometry. The present results are compared with the available literature values as well as theoretical data calculated by the TALYS and the ALICE-IPPE computer codes. Note that production cross-sections of the 104mAg radionuclide from natPd(p,xn) processes has been measured here for the first time. Physical thick target yields for the investigated radionuclides were deduced from the respective threshold energy to 41 MeV taking into account that the total energy is absorbed in the targets. Measured data of the short-lived 103Ag radionuclide are noteworthy due to its possible applications as a precursor for the indirect production of widely used therapeutic 103Pd radionuclide via natPd(p,xn)103Ag ? 103Pd processes. On the other hand, the investigated 104Ag radionuclide finds importance due to its potential use as a diagnostic and positron emission tomography (PET) imaging analogue. Above all, measured data will enrich the literature database leading to various applications in science and technology.

Khandaker, Mayeen Uddin; Kim, Kwangsoo; Kim, Guinyun

2012-03-01

199

Short- and long-lived radionuclide particle size measurements in a uranium mine  

SciTech Connect

The radon-222 progeny and long-lived radionuclide measurements were done in a wet underground uranium mine in Saskatchewan, Canada, on Nov. 8-12, 1995. Radon-222 in the mine varied from 2 kBq/m{sup 3} at 90 m below surface to 12 kBq/m{sup 3} in the mining areas, 240 m below surface. Radon-222 progeny activity and potential alpha energy concentration appear affected by the airborne particle number concentration and size distribution. Particle number was up to 200x10{sup 3}/cm{sup 3}. Only an accumulation mode (30-1000 nm) and some bimodal size distributions in this accumulation size range were significant. Diesel particles and combustion particles from burning propane caused a major modal diameter shift to a smaller size range (50-85 nm) compared with previous values (100-200 nm). The high particle number reduced the unattached progeny (0.5-2 nm) to >5%. The nuclei mode (2-30 nm) in this test was nonexistent, and the coarse mode (>1000 nm), except from the drilling areas and on the stopes, was mostly not measurable. Airborne particle total mass and long- lived radionuclide alpha activity concentrations were very low (80- 100 {mu}g/m{sup 3} and 4-5 mBq/m{sup 3}) owing to high ventilation rates. Mass-weighted size distributions were trimodal, with the major mode at the accumulation size region, which accounts for 45-50% of the mass. The coarse model contains the the least mass, about 20%. The size spectra from gross alpha activities were bimodal with major mode in the coarse region (>1000 nm) and a minor accumulation mode in the 50-900 nm size range. These size spectra were different from the {sup 222}Rn progeny that showed a single accumulation mode in the 50- 85 nm size region. The accumulation mode in the long-lived radionuclide size spectrum was not found in previous studies in other uranium mines.

Tu, Keng-Wu; Fisenne, I.M.; Hutter, A.R.

1997-04-01

200

Short-lived Absorptive Type III-like Microwave Bursts as a Signature of Fragmented Electron Injections  

NASA Astrophysics Data System (ADS)

In this paper, we devote ourselves to interpreting the short-lived absorptive type III-like microwave bursts in the 2006 December 13 flare event observed with high temporal and spectral resolutions (8 ms and 10 MHz) by the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou) at 2.6-3.8 GHz. In the decimeter-centimeter wavelength range, we first present the observations of short-lived bursts represented as a number of absorptive ``spikes'' superposed on the type IV continuum that can be connected by fast-drifting lines. The mean drift rate, the instantaneous bandwidth, and the absorption depth of these absorptive spikes are about -12 GHz s-1, 70 MHz, and 40%, respectively. The duration at a single frequency band can be less than the instrument resolution of 8 ms. On the basis of numerical investigations of the loss-cone instability, we suggest that fragmented electron injections with durations of as short as several milliseconds into the loss cone could be the most appropriate mechanism with which to explain the bursts. The length of an electron beam is estimated to be about 400 km, on the basis of the observational results. These injections may be related to the fragmented energy release processes during the flare. We also observe some absorptive type III-like bursts accompanying ordinary type III bursts with reverse drifts. They start at the same frequency, and the starting frequency slowly drifts to the low-frequency region. This could be a signature of propagating bidirectional electron beams originating near the reconnection region.

Chen, Bin; Yan, Yihua

2008-12-01

201

Spatial and Time Coincidence Detection of the Decay Chain of Short-Lived Radioactive Nuclei  

NASA Astrophysics Data System (ADS)

The quantum counting position sensitive pixel detector Timepix with per-pixel energy and time resolution enables to detect radioactive ions and register the consecutive decay chain by simultaneous position-and time-correlation. This spatial and timing coincidence technique in the same sensor is demonstrated by the registration of the decay chain 8He-->? 8Li and 8Li-->?- 8Be-->?+? and by the measurement of the ? decay half-lives. Radioactive ions, selectively obtained from the Lohengrin fission fragment spectrometer installed at the High Flux Reactor of the ILL Grenoble, are delivered to the Timepix silicon sensor where decays of the implanted ions and daughter nuclei are registered and visualized. We measure decay lifetimes in the range >= ?s with precision limited just by counting statistics.

Granja, Carlos; Jakubek, Jan; Köster, Ulli; Platkevic, Michal; Pospisil, Stanislav

2010-08-01

202

The likely presence of nuclides with short half-lives in HD965 and HD101065 (Przybylski's Star)  

NASA Astrophysics Data System (ADS)

Two chemical elements lighter than bismuth have no isotopes with half-lives longer than 5 million years: the 4d-element technetium and the lanthanide promethium. While 98Tc has a half-life of 4.2 106 years, the longest-lived isotope of Pm, 145Pm, has a half-life of only 17.7 years. The presence of either of these elements in upper main sequence stars would pose a serious problem for our understanding of the chemistry of these stars. It is now generally accepted that the chemical anomalies of numerous subtypes of peculiar B, A, and F stars is a superficial phenomenon caused by chemical separation under the competing influences of radiation pressure and gravity. This theory would have to be supplemented should the presence of these unstable species be confirmed. There is substantial evidence to support the presence of PmI and/or II, and TcI, in HD101065, and PmI and/or II in HD965. HD101065 is a notorious object, well known for the strength of its rare-earth spectra relative to the iron group (see url below for data and references). Hubrig, et al. (ASP Conf. Ser. 279, ed. C. A. Tout and W. Van Hamme, p. 365) noted the similarity of HD965 toPrzybylski's star. Identifications of Tc and Pm in these stars are based on wavelength coincidence statistics (WCS Cowley and Hensberge, ApJ 244. 252. 1081)and traditional line-by-line examinations taking into account laboratory intensities, excitation potentials, and wavelength agreement. Wavelength measurements are available at http://www.astro.lsa.umich.edu/users/cowley/. The highest significances are obtained for HD965 and a list of strong PmI and II from the NIST site (Sansonetti and Martin http://physics.nist.gov/PhysRefData/Handbook/index.html). We found 14 of 39 lines within ± 0.02Å, which is a 99.9% confident result. Various tests for PmI and II in HD101065 lead to 99% confidence or better. WCS yields 95-99% confidence for TcI in HD101065.

Cowley, C. R.; Bidelman, W. P.; Hubrig, S.; Mathys, G.; Bord, D. J.

2003-12-01

203

Cross section measurements for neutron-induced reactions off C, Al, SiO2, Si and Au producing relatively short-lived radionuclides at neutron energies between 70 and 160 MeV  

NASA Astrophysics Data System (ADS)

A systematic study was made to measure many cross sections for relevant neutron-induced reactions. This study was motivated by the need to better understand cosmic ray interactions with extraterrestrial materials. The major constituents of meteorites and lunar rocks include oxygen, silicon, and aluminum. The primary aim was to measure cross sections for neutron-induced reactions producing long-lived radionuclides (e.g. 14C) and stable isotopes (e.g. Ne isotopes) but the irradiation conditions allowed cross sections for many reactions producing relatively short-lived radionuclides (e.g. 22Na) to be well measured. Monitor foils used in the irradiations included C, Al, and Au. Quasi-monoenergetic neutron beams were produced by bombarding Be targets with 80, 120 and 160 MeV proton beams at iThemba LABS, South Africa. Two identical target stacks were irradiated in beam lines at 0° and 16° to the incident proton beam direction. The yield at an unique neutron energy was obtained by subtracting the yield measured at 16° (after suitable normalization) from that measured at 0°. The cross sections for the following reactions: 27Al(n,x)22,24Na; natC(n,x)7Be; 197Au(n,x)194,196Au; SiO2(n,x)22Na and natSi(n,x)24Na are reported.

Sisterson, Janet M.

2007-08-01

204

Comparison of distribution and activity of nanoparticles with short interfering DNA (Dbait) in various living systems  

PubMed Central

Introducing small DNA molecules (Dbait) impairs the repair of damaged chromosomes and provides a new method for enhancing the efficiency of radiotherapy in radio-resistant tumors. The radiosensitizing activity is dependent upon the efficient delivery of Dbait molecules into the tumor cells. Different strategies have been compared, to improve this key step. We developed a pipeline of assays to select the most efficient nanoparticles and administration protocols before preclinical assays: (i) molecular analyses of complexes formed with Dbait molecules, (ii) cellular tests for Dbait uptake and activity, (iii) live zebrafish embryo confocal microscopy monitoring for in vivo distribution and biological activity of the nanoparticles and (iv) tumor growth and survival measurement on mice with xenografted tumors. Two classes of nanoparticles were compared, polycationic polymers with linear or branched polyethylenimine (PEI) and covalently attached cholesterol (coDbait). The most efficient Dbait transfection was observed with linear PEI complexes, in vitro and in vivo. Doses of coDbait ten-fold higher than PEI/Dbait nanoparticles, and pretreatment with chloroquine, were required to obtain the same antitumoral effect on xenografted melanoma. However, with a 22-fold lower ‘efficacy dose/toxicity dose' ratio as compared with Dbait/PEI, coDbait was selected for clinical trials.

Berthault, N; Maury, B; Agrario, C; Herbette, A; Sun, J-S; Peyrieras, N; Dutreix, M

2011-01-01

205

Isotopic composition and morphology of living Globorotalia scitula: a new proxy of sub-intermediate ocean carbonate chemistry?  

Microsoft Academic Search

Abundance, isotopic composition and morphological imprints of the planktonic foraminifera Globorotalia scitula (Brady) were closely examined for possible use as a novel reconstruction tool of chemical environments in sub-intermediate depth seawater in the past. Based on the MOCNES plankton tow observation of dwelling depths of G. scitula and the isotopic compositions together with hydrochemistry data, the empirical relations between isotopic

Masashi Itou; Tsuneo Ono; Tadamichi Oba; Shinichiro Noriki

2001-01-01

206

BSE infection of the small short-lived primate Microcebus murinus.  

PubMed

Eleven Microcebus murinus (lemur) primates were intracerebrally or orally infected by bovine spongiform encephalopathy (BSE) or macaque-adapted BSE (MBSE) brain homogenates. In many BSE and MBSE infected lemurs, but not in animals inoculated with normal bovine brain, persistent behavioral changes occurred as early as 3 months, and neurological signs as early as 13 months after infection. Immunohistochemical examination of animals sacrificed during the incubation period revealed an abnormal accumulation of 'prion' protein (PrP) in the intestinal wall, intestinal nervous plexus, mesenteric lymph nodes and spleen, and in the clinical stage, also in the brain. In MBSE-inoculated animals, proteinase K resistance of the PrP (PrPres) was confirmed by Western blot in the spleen and the brain. Obvious signs of neurodegeneration were observed in all infected animals characterized by hyperaggregated and paired-helical filaments-immunoreactive Tau proteins, beta 42-amyloid plaques and astrogliosis. Additionally, PrPres was present in the ganglion cells of the retina in diseased animals after either intracerebrally or oral infection by the BSE or MBSE agent. These results show that the microcebe is susceptible to the BSE infectious agent via intracerebral and oral routes with comparatively short incubation periods compared to simians, and could be a useful animal model to study the pathophysiology of disease transmission in primates. PMID:11862624

Bons, Noëlle; Lehmann, Sylvain; Nishida, Noriyuki; Mestre-Frances, Nadine; Dormont, Dominique; Belli, Patrick; Delacourte, Andre; Grassi, Jacques; Brown, Paul

2002-01-01

207

Production of short-lived positron sources for spin-polarized positron beams using a 35 MeV ?-beam  

NASA Astrophysics Data System (ADS)

Various short-lived positron sources for polarized positron beams have been on-line produced by irradiating nickel, aluminum, and silicon targets for the first time using a 35 MeV alpha beam from the RIKEN AVF cyclotron. The ?+ rays emitted from the targets with wide energy spread are converted to a monochromatic slow positron beam using a 10 ?m tungsten polycrystalline moderator. In the current stage, ~ 104 e+/(s ?A) can be obtained from nickel and aluminum targets, which is in relatively good agreement with the calculated slow positron yield. For silicon, a relatively low slow-positron intensity, ~ 103 e+/(s/?A) was obtained probably due to the charge up effect in the silicon surface during irradiation. For increasing the slow-positron yield loss of fast positrons in the material must be avoided, and as a new means for such improvement it is proposed to use gas targets.

Itoh, Yoshiko; Peng, Z. L.; Goto, Akira; Nakanishi, Noriyoshi; Kase, Masayuki; Lee, K. H.; Ito, Yasuo

1996-02-01

208

Prompt gamma activation analysis (PGAA) and short-lived neutron activation analysis (NAA) applied to the characterization of legacy materials  

SciTech Connect

Without quality historical records that provide the composition of legacy materials, the elemental and/or chemical characterization of such materials requires a manual analytical strategy that may expose the analyst to unknown toxicological hazards. In addition, much of the existing legacy inventory also incorporates radioactivity, and, although radiological composition may be determined by various nuclear-analytical methods, most importantly, gamma-spectroscopy, current methods of chemical characterization still require direct sample manipulation, thereby presenting special problems with broad implications for both the analyst and the environment. Alternately, prompt gamma activation analysis (PGAA) provides a'single-shot' in-situ, non-destructive method that provides a complete assay of all major entrained elemental constituents.1-3. Additionally, neutron activation analysis (NAA) using short-lived activation products complements PGAA and is especially useful when NAA activation surpasses the PGAA in elemental sensitivity.

Firestone, Richard B; English, G.A.; Firestone, R.B.; Perry, D.L.; Reijonen, J.P.; Leung, Ka-Ngo; Garabedian, G.F.; Molnar, G.L.; Revay, Zs.

2008-02-13

209

The short-term impact of protocol biopsies in a live-related renal transplant program using tacrolimus based immunosuppression.  

PubMed

The aim of the study was to assess the impact of protocol biopsies in a live-related renal transplant program using tacrolimus-based immunosuppression in the short term. Eighty-three live-related transplant recipients were randomly allocated to protocol biopsy group (Group I, n = 40) and a control group (Group II, n = 43). Other immunosuppressants in these groups consisted of either mycophenolate mofetil or azathioprine and steroids. Protocol biopsies were conducted in biopsy group at 1, 6, and 12 months post-transplant. The non-biopsy group was followed by serial serum creatinine and biopsies in them were conducted as and when clinically indicated. Both groups were analyzed at 12 months with respect to graft function and survival. The two groups were similar with respect to age, number of dialysis pre-operatively, tacrolimus levels, induction therapy, donor age, and donor glomerular filtration rate. Forty protocol biopsies were conducted at 1 month, 31 at 6 months, and 26 at 12 months. The prevalence of sub-clinical rejection at 1, 6, and 12 months in these biopsies was 17.5%, 11.2%, and 10.3%, respectively. The prevalence of calcineurin inhibitor toxicity during same period was 15%, 15.5%, and 14.4%, respectively. The cumulative rejection rate in Group I and Group II at 12-month follow-up was 10.3% and 11.3% (P = 0.78), respectively, and cumulative calcineurin inhibitor toxicity at 12 months was 14.4% and 9.3% (P = 0.59), respectively, were not statistically significant. There was no difference in graft survival and function at 1 year. Protocol biopsies have a limited role in a well-matched renal transplant program with tacrolimus-based immunosuppression in the short term. However, the long-term impact of protocol biopsies needs further evaluation. PMID:23960339

Guleria, S; Jain, S; Dinda, A K; Mahajan, S; Gupta, S; Mehra, N K

2013-07-01

210

Thyroid cancer in the Marshallese: relative risk of short-lived internal emitters and external radiation exposure  

SciTech Connect

In a study of the comparative effects of internal versus external irradiation of the thyroid in young people, we determined that the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times less thyroid cancer than did the same dose of radiation given externally. We determined this finding for a group of 85 Marshall Islands children, who were less than 10 years of age at the time of exposure and who were accidentially exposed to internal and external thyroid radiation at an average level of 1400 rad. The external risk coefficient ranged between 2.5 and 4.9 cancers per million person-rad-years at risk, and thus, from our computations, the internal risk coefficient for the Marshallese children was estimated to range between 1.0 and 1.4 cancers per million person-rad-years at risk. In contrast, for individual more than 10 years of age at the time of exposure, the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times more thyroid cancer than did the same dose of radiation given externally. The external risk coefficients for the older age groups were reported in the literature to be in the range of 1.0 to 3.3 cancers per million person-rad-years-at risk. We computed internal risk coefficients of 3.3 to 8.1 cancers per million person-rad-years at risk for adolescent and adult groups. This higher sensitivity to cancer induction in the exposed adolescents and adults, is different from that seen in other exposed groups. 14 refs., 8 tabs.

Lessard, E.T.; Brill, A.B.; Adams, W.H.

1985-01-01

211

The short-term impact of protocol biopsies in a live-related renal transplant program using tacrolimus based immunosuppression  

PubMed Central

The aim of the study was to assess the impact of protocol biopsies in a live-related renal transplant program using tacrolimus-based immunosuppression in the short term. Eighty-three live-related transplant recipients were randomly allocated to protocol biopsy group (Group I, n = 40) and a control group (Group II, n = 43). Other immunosuppressants in these groups consisted of either mycophenolate mofetil or azathioprine and steroids. Protocol biopsies were conducted in biopsy group at 1, 6, and 12 months post-transplant. The non-biopsy group was followed by serial serum creatinine and biopsies in them were conducted as and when clinically indicated. Both groups were analyzed at 12 months with respect to graft function and survival. The two groups were similar with respect to age, number of dialysis pre-operatively, tacrolimus levels, induction therapy, donor age, and donor glomerular filtration rate. Forty protocol biopsies were conducted at 1 month, 31 at 6 months, and 26 at 12 months. The prevalence of sub-clinical rejection at 1, 6, and 12 months in these biopsies was 17.5%, 11.2%, and 10.3%, respectively. The prevalence of calcineurin inhibitor toxicity during same period was 15%, 15.5%, and 14.4%, respectively. The cumulative rejection rate in Group I and Group II at 12-month follow-up was 10.3% and 11.3% (P = 0.78), respectively, and cumulative calcineurin inhibitor toxicity at 12 months was 14.4% and 9.3% (P = 0.59), respectively, were not statistically significant. There was no difference in graft survival and function at 1 year. Protocol biopsies have a limited role in a well-matched renal transplant program with tacrolimus-based immunosuppression in the short term. However, the long-term impact of protocol biopsies needs further evaluation.

Guleria, S.; Jain, S.; Dinda, A. K.; Mahajan, S.; Gupta, S.; Mehra, N. K.

2013-01-01

212

Novel biogenic iodine-containing trihalomethanes and other short-lived halocarbons in the coastal East Atlantic  

NASA Astrophysics Data System (ADS)

Reactive halogen photochemistry and its impact on tropospheric oxidant levels have recently attracted intense research interest following the observation of the iodine oxide radical at midlatitudes. During September 1998, short-lived organoiodines including CH3I, C2H5I, CH2ICl, CH2IBr, CH2I2, and the hitherto undetected CHIBr2, as well as the organobromines CHBr3, CH2Br2, CHBr2Cl, CH3Br, and C2H5Br, were measured in air and seawater at and around Mace Head, on the west coast of Ireland. The release rates of organic bromines and iodines from seaweeds were determined from incubations of 10 species of brown, red, and green macroalgae collected in the intertidal or subtidal zones of the rocky shore. For all the brown algae studied, iodine was released mainly as CH2I2. However, for several seaweeds, the novel iodine-containing trihalomethanes CHIBr2 and CHI2Cl represented a significant fraction of the released organic iodine. The macroalgae incubation experiments as well as monitoring of the in situ concentrations in a rock pool indicated that natural halocarbon production by seaweeds was stimulated by incident light. The halocarbon fluxes derived from the seaweed incubations, coupled with published detailed biomass surveys, enabled coastal organohalogen seawater concentrations to be estimated. The CHBr3, CH2Br2, and CHBr2Cl concentrations calculated by this method compared well with coastal surface seawater measurements, implying that macroalgae were the major sources of the polybromomethanes. Measured CH3Br, CH3I, and CH2ICl levels were higher than calculated, which may be due to the existence of additional sources. CH3Br production by macroalgae accounted for less than 10% of measured levels in coastal waters. Short-lived iodocarbons such as CH2I2 and CHIBr2 were depleted in surface seawater compared to calculated levels, implying their photolytic loss within the upper water column.

Carpenter, L. J.; Malin, G.; Liss, P. S.; Küpper, F. C.

2000-12-01

213

Fecal cortisol levels predict breeding but not survival of females in the short-lived rodent, Octodon degus.  

PubMed

The cort-adaptation hypothesis indicates that an association between glucocorticoid (cort) levels and fitness may vary with the extent to which reproduction or breeding effort is a major determinant of cort levels. Support for a context dependent association between cort and fitness comes mostly from relatively long-lived, bird species. We tested the hypothesis that there are gender and context (life-history) specific cort-fitness relationships in degus, a short-lived and generally semelparous social rodent. In particular, we used demographical records on a natural population to estimate adult survival through seasons and years and linked that to records of baseline cort (based on fecal cortisol metabolites). We found no evidence for a direct relationship between baseline cort and adult survival across seasons, and this lack of association was recorded irrespective of sex and life history stage. Yet, cort levels during early lactation predicted the probability that females produce a second litter during the same breeding season, supporting a connection between baseline cort levels and breeding effort. Overall, the differential effects of cort on survival and breeding supported that the extent of cort-fitness relationships depends on the fitness component examined. PMID:23524002

Ebensperger, Luis A; Tapia, Diego; Ramírez-Estrada, Juan; León, Cecilia; Soto-Gamboa, Mauricio; Hayes, Loren D

2013-03-21

214

Short-term outcomes for obese live kidney donors and their recipients1,2,3,4,5,6  

PubMed Central

Background Given the association between obesity and kidney disease, transplant professionals have debated the appropriateness of accepting obese live kidney donors. We hypothesized that compared to normal weight donors, donors with elevated body mass index (BMI) would have 1) more peri-operative re-admissions and re-operations, and 2) a greater rise in blood pressure, greater percent rise in serum creatinine, and a greater loss of estimated glomerular filtration rate (eGFR) following nephrectomy. Methods Retrospective cohort study using Organ Procurement and Transplantation Network data on live donors who donated kidneys from 7/1/2004 –12/31/2005. Results 9319 live donor kidney transplants were performed. After eliminating donors with missing BMI data, 5304 donors were analyzed, among whom 2108 (40.0%) were overweight (25 ? BMI < 30), 944 (17.8%) were obese (30 ? BMI < 35), and 250 (4.7%) were very obese (BMI>=35). Re-admission and re-operation rates did not differ across donor BMI categories. At baseline and at 6 months after nephrectomy, higher BMI was associated with higher blood pressure (p<0.01), but changes in systolic blood pressure from baseline were similar across BMI categories (p=0.40). At six months, decline in eGFR from baseline (p=0.63) and percent change in creatinine (p=0.11) did not differ significantly across groups. Delayed graft function was more common among recipients of kidneys from very obese donors (OR 2.16, CI 1.20 – 3.89, p=0.01), but the rates of recipient allograft failure and mortality across donor BMI groups were similar. Conclusion Short-term follow-up data show good outcomes for donors with elevated BMI and their recipients.

Reese, Peter P.; Feldman, Harold I.; Asch, David A.; Thomasson, Arwin; Shults, Justine; Bloom, Roy D.

2009-01-01

215

Stable Oxygen and Carbon Isotope Characteristics of Live Benthic Foraminifera from the Okhotsk Sea: Effects of Oceanography, Food Supply, and Microhabitat Patterns  

NASA Astrophysics Data System (ADS)

Paleoceanographic studies use benthic foraminiferal stable isotopes as proxies for interpretations of numerous parameters such as past oceanic circulation patterns, food supply, primary productivity, etc. However, only few studies have used live (rose Bengal-stained) populations to reliably calibrate stable isotope characteristics to bottom water and sediment chemistry of the surrounding environment. We report results from a study in the Okhotsk Sea, a region characterized by extreme climatic and oceanographic settings. Not only does this marginal basin of the NW-Pacific experience the southermost extent of seasonal ice cover in the entire Northern Hemisphere, it also shows extremely high primary productivity. These boundary conditions lead many to consider the Okhotsk Sea both as a modern analog for ecological and oceanographic conditions in ocean basins during past and a sensitive recorder of potential future climate change in high latitudes. We compare results of stable oxygen and carbon isotopes from the most abundant taxa to oxygen isotopic compositions of bottom water and carbon isotopes of bottom water DIC, nutrient inventories from the water column and productivity proxy-data from sediment surface profiles (chlorines, TOC, biogenic opal). Multicorer samples from the upper 10 cm at 15 sites were taken from a variety of settings with water depths ranging from less than 100 m to more than 3200 m. Results obtained show a wide range of interspecific carbon isotope values exceeding 2 per mil variability within neighbouring samples. Minimum values occur in deep endobenthic groups like Globobulima spp., whereas species living in a relatively wide depth range like V. sadonica or U. peregrina exhibit intermediate values between -0.7 and -1 per mil. Most measurements conducted to address intraspecific variability remain within a narrow range of less than 0.4 per mil. However, we do observe vertical trends with both increasing and decreasing carbon isotope gradients within the sediment column. Obtained carbon isotope values from both living and dead specimen of widely used the Cibicides spp. group stay within the range of bottom water DIC, with no systematic negative phytodetritus- effect occuring throughout the sample set despite etremely pronounced seasonality in organic matter supply on most sites. Combined with a proxy-dataset about primary productivity, we give an evaluation of benthic-pelagic coupling and the impact on benthic species adaption to the pronounced subarctic seasonal cycle and the strongly pulsed food fluxes to the ocean floor.

Lembke-Jene, L.; Tiedemann, R.; Bubenshchikova, N.; Erlenkeuser, H.; Dullo, W.

2008-12-01

216

Stable Oxygen and Carbon Isotope Characteristics of Live Benthic Foraminifera from the Okhotsk Sea: Effects of Oceanography, Food Supply and Microhabitat Patterns  

NASA Astrophysics Data System (ADS)

Paleoceanographic studies use benthic foraminiferal stable isotopes as proxies for interpretations of numerous parameters such as past oceanic circulation patterns, food supply, primary productivity, etc. However, only few studies have used live (rose Bengal-stained) populations to reliably calibrate stable isotope characteristics to bottom water and sediment chemistry of the surrounding environment. We report data from a study in the Okhotsk Sea, a region characterized by extreme climatic and oceanographic settings. Not only does this marginal basin of the NW-Pacific experience the southermost extent of seasonal ice cover in the entire Northern Hemisphere, it also shows extremely high primary productivity. These boundary conditions lead many to consider the Okhotsk Sea both as a modern analog for ecological and oceanographic conditions in ocean basins during past and a sensitive recorder of potential future climate change in high latitudes. We compare results of stable oxygen and carbon isotopes from the most abundant taxa to oxygen isotopic compositions of bottom water and carbon isotopes of bottom water DIC, nutrient inventories from the water column and productivity proxy-data from sediment surface profiles (chlorines, TOC, biogenic opal). Multicorer samples from the upper 10 cm at 15 sites were taken from a variety of settings with water depths ranging from less than 100 m to more than 3200 m. Results obtained show a wide range of interspecific carbon isotope values exceeding 2 per mil variability within neighbouring samples. Minimum values occur in deep endobenthic groups like Globobulima spp., whereas species living in a relatively wide depth range like V. sadonica or U. peregrina exhibit intermediate values between -0.7 and -1 per mil. Most measurements conducted to address intraspecific variability remain within a narrow range of less than 0.4 per mil. However, we do observe vertical trends with both increasing and decreasing carbon isotope gradients within the sediment column. Obtained carbon isotope values from both living and dead specimen of widely used the Cibicides spp. group stay within the range of bottom water DIC, with no systematic negative phytodetritus-effect occuring throughout the sample set despite etremely pronounced seasonality in organic matter supply on most sites. Combined with a proxy-dataset about primary productivity, we give an evaluation of benthic-pelagic coupling and the impact on benthic species adaption to the pronounced subarctic seasonal cycle and the strongly pulsed food fluxes to the ocean floor.

Lembke-Jene, L.; Tiedemann, R.; Bubenshchikova, N.; Erlenkeuser, H.

2009-04-01

217

Short-lived fission product measurements from >0.1 MeV neutron-induced fission using boron carbide.  

SciTech Connect

A boron carbide shield was designed, custom fabricated, and used to create a fast fission energy neutron spectrum. The fissionable isotopes 233, 235, 238U, 237Np, and 239Pu were separately placed inside of this shield and irradiated under pulsed conditions at the Washington State University 1 MW TRIGA reactor. A unique set of fission product gamma spectra were collected at short times (4 minutes to 1 week) post-fission. Gamma spectra were collected on single-crystal high purity germanium detectors and on Pacific Northwest National Laboratory's (PNNL's) Direct Simultaneous Measurement (DSM) system composed of HPGe detectors connected in coincidence. This work defines the experimental methods used to produce and collect the gamma data, and demonstrates the validity of the measurements. It is important to fully document this information so the data can be used with high confidence for the advancement of nuclear science and non-proliferation applications. The gamma spectra collected in these and other experiments will be made publicly available at https://spcollab.pnl.gov/sites/gammadata or via the link at http://rdnsgroup.pnl.gov. A revised version of this publication will be posted with the data to make the experimental details available to those using the data.

Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce D.; Friese, Judah I.; Kephart, Rosara F.; Kephart, Jeremy D.

2012-02-01

218

Inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS for isotope analysis of long-lived radionuclides  

NASA Astrophysics Data System (ADS)

For a few years now inductively coupled plasma mass spectrometry has been increasingly used for precise and accurate determination of isotope ratios of long-lived radionuclides at the trace and ultratrace level due to its excellent sensitivity, good precision and accuracy. At present, ICP-MS and also laser ablation ICP-MS are applied as powerful analytical techniques in different fields such as the characterization of nuclear materials, recycled and by-products (e.g., spent nuclear fuel or depleted uranium ammunitions), radioactive waste control, in environmental monitoring and in bioassay measurements, in health control, in geochemistry and geochronology. Especially double-focusing sector field ICP mass spectrometers with single ion detector or with multiple ion collector device have been used for the precise determination of long-lived radionuclides isotope ratios at very low concentration levels. Progress has been achieved by the combination of ultrasensitive mass spectrometric techniques with effective separation and enrichment procedures in order to improve detection limits or by the introduction of the collision cell in ICP-MS for reducing disturbing interfering ions (e.g., of 129Xe+ for the determination of 129I). This review describes the state of the art and the progress of ICP-MS and laser ablation ICP-MS for isotope ratio measurements of long-lived radionuclides in different sample types, especially in the main application fields of characterization of nuclear and radioactive waste material, environmental research and health controls.

Becker, J. Sabine

2005-04-01

219

Photonuclear Production of Medical Isotopes  

NASA Astrophysics Data System (ADS)

Every year, more than 20 million people in the United States receive a nuclear medicine procedure. Many of the isotopes needed for these procedures are under-produced. Suppliers of the isotopes are usually located outside the United States, which presents a problem when the desired isotopes have short half-lives. Linear accelerators were investigated as a possible method of meeting isotope demand. Linear accelerators are cheaper, safer, and have lower decommissioning costs compared to nuclear reactors. By using (?,p) reactions, the desired isotope can be separated from the target material due to the different chemical nature of each isotope. Isotopes investigated were Cu-67, In-111, and Lu-111. Using the results the photon flux Monte Carlo simulations, the expected activity of isotopes can be calculated. After samples were irradiated, a high purity germanium detector and signal processing apparatus were used to count the samples. The activity at the time of irradiation stop was then calculated. The uses of medical isotopes will also be presented.

Weinandt, Nick

2011-10-01

220

Petrological and geochemical records of short-lived, high temperature metamorphism during exhumation of the Sulu UHP metamorphic terrane  

NASA Astrophysics Data System (ADS)

The Dabie-Sulu terrane of east-central China is the largest and most well known ultrahigh-pressure (UHP) metamorphic terrane in the world, which has become one of the most important places to study continental subduction-related UHP metamorphism. In the past two decades, numerous petrological, geochemical, petrophysical and tectonophysical studies were carried out in the Dabie-Sulu UHP metamorphic terrane. However, almost all of these studies have focused on UHP metamorphic processes, while only a few studies have focused on the thermal evolution. Here we present a detailed petrological and geochemical study on the southern Sulu UHP eclogites in order to constrain the “hot” exhumation of the Sulu UHP metamorphic terrane. Eclogite-hosted garnet-spinel-corundum-quartz-bearing titanohematite veins near the main hole of the Chinese Continental Scientific Drilling Project (CCSD-MH) are described for the first time in the Sulu UHP metamorphic terrane. A vein composed of titanohematite + ilmenite + hematite + spinel + garnet + corundum + quartz + K-feldspar + albite was studied in detail. The unusual mineral assemblage of garnet + spinel + corundum + quartz implies that this vein could have experienced high temperatures (>900 oC). Although within garnets showed well-defined Mg and Mn diffusion zoning in the rim as a result of the high temperature event, slight Mg and Mn growth zoning was preserved in the core. Thus, we suggest that the Sulu UHP terrane could have experienced a short-lived, high-temperature stage during exhumation. This is consistent with trace element zoning recorded by garnet, omphacite and apatite and much higher temperatures recorded by rutiles and zircons with ages of ~200 Ma in the CCSD-MH eclogites. We speculate that slab breakoff may have caused asthenospheric upwelling, which could have provided a heat pulse for the short-lived, high-temperature metamorphism in the Sulu UHP terrane. Such high temperature stage could have contributed to the overprinting of granulite-facies metamorphism on eclogites and widespread partial melting in the Sulu UHP terrane.

Zong, K.; Liu, Y.; Zhang, X.; Ye, Y.; Gao, C.

2010-12-01

221

Using daily satellite observations to estimate emissions of short-lived air pollutants on a mesoscopic scale  

NASA Astrophysics Data System (ADS)

Emission inventories of air pollutants are crucial information for policy makers and form important input data for air quality models. Using satellite observations for emission estimates has important advantages over bottom-up emission inventories: they are spatially consistent, have high temporal resolution, and enable updates shortly after the satellite data become available. We present a new algorithm specifically designed to use daily satellite observations of column concentrations for fast updates of emission estimates of short-lived atmospheric constituents on a mesoscopic scale (˜25 × 25 km2). The algorithm needs only one forward model run from a chemical transport model to calculate the sensitivity of concentration to emission, using trajectory analysis to account for transport away from the source. By using a Kalman filter in the inverse step, optimal use of the a priori knowledge and the newly observed data is made. We apply the algorithm for NOx emission estimates of East China, using the CHIMERE model on a 0.25 degree resolution together with tropospheric NO2column retrievals of the OMI and GOME-2 satellite instruments. Closed loop tests show that the algorithm is capable of reproducing new emission scenarios. Applied with real satellite data, the algorithm is able to detect emerging sources (e.g., new power plants), and improves emission information for areas where proxy data are not or badly known (e.g., shipping emissions). Chemical transport model runs with the daily updated emission estimates provide better spatial and temporal agreement between observed and simulated concentrations, facilitating improved air quality forecasts.

Mijling, B.; van der A, R. J.

2012-09-01

222

Nutrient Intake From Habitual Oral Diet in Patients With Severe Short Bowel Syndrome Living in the Southeastern United States  

PubMed Central

Background and Aims Little data are published on habitual home oral diet of short bowel syndrome (SBS) patients living in the United States. Methods We assessed habitual macro-and micronutrient intake from oral food and beverages in 19 stable patients with severe SBS who live in the Southeastern United States. Intestinal absorption of energy, fat, nitrogen (N) and carbohydrate (CHO) was determined in a metabolic ward setting. Results We studied 12 women and 7 men, age 48±3 years (mean±SE) receiving chronic PN for 31±8 months following massive small bowel resection (118±25 cm residual small bowel). Patients had intact (N=5), partial (N=9), or no residual colon (N=5). The subjects demonstrated severe malabsorption of energy (59±3% of oral intake), fat (41±5%), N (42±5%) and CHO (76±3%). Average oral energy intake was 2656±242 kcal/day (39±3 kcal/kg/day) and oral protein intake was 1.4 ±0.1 g/kg/d. Oral food/beverage intake constituted 49±4% of total (enteral + parenteral) daily fluid intake, 66±4% of total daily kcal and 58±5% of total daily N intake. Oral fat intake averaged 92±11g/day (? 35% of total oral energy). Oral fluid intake averaged 2712±240 ml/d, primarily from water, soft drinks, sweet tea and coffee. Simple sugars comprised 42±3% of oral CHO intake. Usual dietary intake of multiple micronutrients were below the Recommended Dietary Allowances (RDA) in a large percentage of patients: vitamin A (47%), vitamin D (79%), vitamin E (79%), vitamin K (63%), thiamine (42%), vitamin B6 (68%), vitamin B12 (11%), vitamin C (58%), folate (37%), iron (37%), calcium (63%), magnesium (79%) and zinc (68%). Only 7 patients (37%) were taking oral multivitamin-mineral supplements and only 6 subjects (37%) were taking oral iron and calcium supplements, respectively. Conclusions In these SBS patients living in the Southeastern United States, oral diet provides a significant proportion of daily nutrient intake. However, the types of foods and fluids consumed are likely to worsen malabsorption and increase PN requirements. Oral intake of essential micronutrients was very low in a significant proportion of this cohort of SBS patients.

Fernandez-Estivariz, Concepcion; Luo, Menghua; Umeakunne, Kay; Bazargan, Niloofar; Galloway, John R.; Leader, Lorraine M.; Ziegler, Thomas R.

2008-01-01

223

[Nuclear spin catalysis in nanoreactors of living cells].  

PubMed

There is a great variety of chemical elements with magnetic and nonmagnetic isotopes in living cells. The question arises as to whether living cells can perceive the difference between magnetic and non-magnetic isotopes of chemical elements. It has been shown that bacteria Escherichia coli, which were previously enriched with the magnetic isotope of magnesium, 25Mg, essentially faster adapt to the new growth media in comparison with the cells, which were enriched with the nonmagnetic isotopes, 24Mg or 26Mg. In the experiments with another commonly accepted cell model, yeast Saccharomyces cerevisiae, it has been shown that the magnetic 25Mg, in comparison with the nonmagnetic 24Mg, essentially better stimulates recovery of the cells after short wave UV irradiation. Thus, for the first time, the magnetic isotope effects in vivo have been discovered. These findings reveal the novel, based on the stable magnetic isotopes, ways of control over efficiency and reliability of biological systems. PMID:23755551

Kol'tover, V K

224

Impact of very short-lived halogens on stratospheric ozone abundance and UV radiation in a geo-engineered atmosphere  

NASA Astrophysics Data System (ADS)

The impact of very short-lived (VSL) halogenated source species on the ozone layer and surface erythemal ultraviolet radiation (UVERY) is investigated in the context of geo-engineering of climate by stratospheric sulfur injection. For a projected 2040 model atmosphere, consideration of VSL halogens at their upper limit results in lower ozone columns and higher UVERY due to geo-engineering for nearly all seasons and latitudes, with UVERY rising by 12% and 6% in southern and northern high latitudes, respectively. When VSL halogen sources are neglected, future UVERY increases due to declines in ozone column are nearly balanced by reductions of UVERY due to scattering by the higher stratospheric aerosol burden in mid-latitudes. Consideration of VSL sources at their upper limit tips the balance, resulting in annual average increases in UVERY of up to 5% in mid and high latitudes. Therefore, VSL halogens should be considered in models that assess the impact of stratospheric sulfur injections on the ozone layer.

Tilmes, S.; Kinnison, D. E.; Garcia, R. R.; Salawitch, R.; Canty, T.; Lee-Taylor, J.; Madronich, S.; Chance, K.

2012-11-01

225

Impact of very short-lived halogens on stratospheric ozone abundance and UV radiation in a geo-engineered atmosphere  

NASA Astrophysics Data System (ADS)

The impact of very short-lived (VSL) halogenated source species on the ozone layer and surface erythemal ultraviolet radiation (UVERY) is investigated in the context of geo-engineering of climate by stratospheric sulfur injection. For a projected 2040 model atmosphere, consideration of VSL halogens at their upper limit results in lower ozone columns and higher UVERY due to geo-engineering for nearly all seasons and latitudes, with UVERY rising by 12% and 6% in southern and northern high latitudes, respectively. When VSL halogen sources are neglected, future UVERY increases due to declines in ozone column are nearly balanced by reductions of UVERY due to scattering by the higher stratospheric aerosol burden in mid-latitudes. Consideration of VSL sources at their upper limit tips the balance, resulting in annual average increases in UVERY of up to 5% in mid and high latitudes. Therefore, VSL halogens should be considered in models that assess the impact of stratospheric sulfur injections on the ozone layer.

Tilmes, S.; Kinnison, D. E.; Garcia, R. R.; Salawitch, R.; Canty, T.; Lee-Taylor, J.; Madronich, S.; Chance, K.

2012-08-01

226

Role of Sec61p in the ER-associated degradation of short-lived transmembrane proteins.  

PubMed

Misfolded proteins in the endoplasmic reticulum (ER) are identified and degraded by the ER-associated degradation pathway (ERAD), a component of ER quality control. In ERAD, misfolded proteins are removed from the ER by retrotranslocation into the cytosol where they are degraded by the ubiquitin-proteasome system. The identity of the specific protein components responsible for retrotranslocation remains controversial, with the potential candidates being Sec61p, Der1p, and Doa10. We show that the cytoplasmic N-terminal domain of a short-lived transmembrane ERAD substrate is exposed to the lumen of the ER during the degradation process. The addition of N-linked glycan to the N terminus of the substrate is prevented by mutation of a specific cysteine residue of Sec61p, as well as a specific cysteine residue of the substrate protein. We show that the substrate protein forms a disulfide-linked complex to Sec61p, suggesting that at least part of the retrotranslocation process involves Sec61p. PMID:18573918

Scott, Daniel C; Schekman, Randy

2008-06-23

227

Occurrence of adventitious sprouting in short-lived monocarpic herbs: a field study of 22 weedy species  

PubMed Central

Background and Aims Adventitious sprouting from the hypocotyle and roots in monocarpic herbs has been confirmed in previous experimental studies as a means to avoid bud limitation after severe injury in annual and biennial plants. Data regarding the role of adventitious sprouting in natural populations, however, were lacking. The aim of the present study was to assess whether adventitious sprouting occurs in natural populations and how it is affected by plant size, plant injury, plant cover and environmental characteristics. Methods Data were sampled from 14 037 individual plants from 389 populations belonging to 22 annual and biennial species. Growth parameters were measured in individual plants, species composition and plant cover in communities were evaluated, and environmental characteristics were estimated using Ellenberg indicator values. Key Results It was confirmed that adventitious sprouting occurs in natural populations of all but five species examined. Adventitious sprouting was positively affected by plant size and plant injury. Environmental factors including availability of soil nitrogen were not shown to affect adventitious sprouting. Annual and biennial plants did not differ in sprouting, but upright annuals had a lower number of and longer adventitious shoots than prostrate annuals. Conclusions Adventitious bud formation is used to overcome meristem limitation when stem parts are lost due to injury, and thus resprouting in short-lived monocarps should not be overlooked.

Malikova, Lenka; Smilauer, Petr; Klimesova, Jitka

2010-01-01

228

Technical Note: Ensuring consistent, global measurements of short-lived halocarbon gases in the ocean and atmosphere  

NASA Astrophysics Data System (ADS)

Short-lived halocarbons are significant sources of reactive halogen in the troposphere and likely the lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the impact of fluxes of these gases on marine boundary layer oxidation and lower stratospheric ozone-depletion processes. Despite the body of literature increasing substantially over recent years, calibration issues complicate comparison of results and limit the utility of building larger-scale databases that would enable further development of the science (e.g. sea-air flux quantification, model validation, etc.). With this in mind, thirty-two scientists representing eight nations and from both atmospheric and oceanic halocarbon communities gathered in London in February 2008 to discuss the scientific issues and plan an international effort toward a common calibration scale. Here, we discuss the outputs from this meeting, suggest the compounds that should be targeted initially, identify opportunities for beginning calibration and comparison efforts, and make recommendations for ways to improve the comparability of previous and future measurements.

Butler, J. H.; Bell, T. G.; Hall, B. D.; Quack, B.; Carpenter, L. J.; Williams, J.

2009-05-01

229

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere  

NASA Astrophysics Data System (ADS)

Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of literature increasing substantially over recent years, calibration issues complicate the comparison of results and limit the utility of building larger-scale databases that would enable further development of the science (e.g. sea-air flux quantification, model validation, etc.). With this in mind, thirty-one scientists from both atmospheric and oceanic halocarbon communities in eight nations gathered in London in February 2008 to discuss the scientific issues and plan an international effort toward developing common calibration scales (http://tinyurl.com/c9cg58). Here, we discuss the outputs from this meeting, suggest the compounds that should be targeted initially, identify opportunities for beginning calibration and comparison efforts, and make recommendations for ways to improve the comparability of previous and future measurements.

Butler, J. H.; Bell, T. G.; Hall, B. D.; Quack, B.; Carpenter, L. J.; Williams, J.

2010-01-01

230

Identification of the short-lived Au(N3)42- dianion from its Coulomb explosion products  

NASA Astrophysics Data System (ADS)

In high-energy collisions between Au(N3)4- anions and sodium vapor, electron transfer occurred to produce Au(N3)42- dianions. These were short-lived (sub microsecond) and Coulomb exploded into Au(N3)3- and N3- with a kinetic energy release of 2.6 +/- 0.5 eV. In the product ion spectra, peaks correspond to fragment ions formed from collisionally activated Au(N3)4- parent anions. Loss of one or more N3 or N2 produced AuNn- complexes (n = 1-4, 6, 9-10) whereas complexes with n = 5, 7, and 8 were not detected. These ions can be assigned to gold-nitride-azide complexes Au(N)x(N3)y- (x = 0-2 and y = 0-4). Cationic complexes were measured for n = 1-4 and 6. Sodium vapor collision experiments were also performed for Au(N3)2-, which is generated in situ by the spontaneous reduction of Au(N3)42- and concurrent azide dissociation. In this case there was no clear signature indicative of the formation of a dianion. The formation of dianions cannot be excluded, however, since such ions may decay by electron emission instead of dissociation into two singly charged fragment ions.

Drenck, Kasper; Hvelplund, Preben; McKenzie, Christine J.; Nielsen, Steen Brøndsted

2005-07-01

231

Quantification of radiation dose from short-lived positron emitters formed in human tissue under proton therapy conditions  

NASA Astrophysics Data System (ADS)

The dose distribution in proton therapy is mainly due to primary particles and secondary electrons. The contribution of short-lived ?+ emitters formed in the interactions of protons with the light mass elements C, N and O has hitherto not been considered. We estimated the formation of 11C, 13N and 15O in irradiation of tissue with 200 MeV protons. The integral yields at 150 MeV were compared with a literature phantom measurement. The results for 11C and 15O agreed very well; for 13N, however, appreciable deviation was observed. The activities were also calculated in the region around the Bragg peak as well as over the path length after entrance of the beam. Dose calculations were then done using the medical internal radiation dose (MIRD) formalism. Furthermore, a dose calculation was simulated for a 150 MeV proton beam (2 nA, 2 min) in a brain tumour. The dose deposited by the positron emitters in the Bragg peak region was found to be about 1.5 mGy, i.e. less than 1% of the dose estimated from the electronic interactions of protons. The absorbed dose in the whole brain amounted to 5.5 mGy.

Kettern, K.; Coenen, H. H.; Qaim, S. M.

2009-06-01

232

{beta}-decay half-lives of new neutron-rich rare-earth isotopes {sup 159}Pm,{sup 162}Sm, and {sup 166}Gd  

SciTech Connect

The new neutron-rich rare-earth isotopes {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd produced in the proton-induced fission of {sup 238}U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of {sup 159}Pm, {sup 162}Sm, and {sup 166}Gd were determined to be 1.5 {+-} 0.2, 2.4 {+-} 0.5, and 4.8 {+-} 1.0 s respectively. The partial decay scheme of {sup 166}Gd was constructed from {gamma}{gamma}-coincidence data. A more accurate half-life value of 25.6 {+-} 2.2 s was obtained for the previously identified isotope {sup 166}Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

Ichikawa, S.; Asai, M.; Tsukada, K.; Nagame, Y. [Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan); Haba, H. [Cyclotron Center, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Shibata, M. [Radioisotope Research Center, Nagoya University, Nagoya 464-8603 (Japan); Sakama, M. [Department of Radiological Technology, University of Tokushima, Tokushima 770-8509 (Japan); Kojima, Y. [Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan)

2005-06-01

233

Garnet-spinel-corundum-quartz-bearing titanohematite veins in eclogite from the Sulu ultrahigh-pressure terrane: Imprint of a short-lived, high-temperature metamorphic stage  

NASA Astrophysics Data System (ADS)

Mineral assemblage of spinel + corundum + quartz was reported in the Sulu UHP belt. Unusual spinel + corundum + quartz assemblage implies a high-T condition (>900 °C). Growth zoning preserved in the garnet implies that high-T stage is short-lived. High-T could have induced granulite-facies metamorphism and partial melting.

Zong, Keqing; Liu, Yongsheng; Gao, Changgui; Hu, Zhaochu; Gao, Shan

2011-09-01

234

Beyond reminders: a conceptual framework for using short message service to promote prevention and improve healthcare quality and clinical outcomes for people living with HIV  

Microsoft Academic Search

The availability of effective antiretroviral therapy has altered HIV from being an acute disease to being a chronic, manageable condition for many people living with HIV (PLWH). Because of their ubiquity and flexibility, mobile phones with short message service (SMS) offer a unique opportunity to enhance treatment and prevention for people managing HIV. To date, very few US studies using

Curtis M. Coomes; Megan A. Lewis; Jennifer D. Uhrig; Robert D. Furberg; Jennie L. Harris; Carla M. Bann

2012-01-01

235

Beyond reminders: a conceptual framework for using short message service to promote prevention and improve healthcare quality and clinical outcomes for people living with HIV  

Microsoft Academic Search

The availability of effective antiretroviral therapy has altered HIV from being an acute disease to being a chronic, manageable condition for many people living with HIV (PLWH). Because of their ubiquity and flexibility, mobile phones with short message service (SMS) offer a unique opportunity to enhance treatment and prevention for people managing HIV. To date, very few US studies using

Curtis M. Coomes; Megan A. Lewis; Jennifer D. Uhrig; Robert D. Furberg; Jennie L. Harris; Carla M. Bann

2011-01-01

236

A novel approach based on nanotechnology for investigating the chronic actions of short-lived peptides in specific sites of the brain  

Microsoft Academic Search

This review presents a novel experimental approach for investigating the chronic actions of short-lived peptides in specific sites of the brain. This method combines the advantages of three different techniques: liposome encapsulation, site-specific microinjection and telemetry. First, liposomes can be designed to remain located at the injection site for a long period of time, where they protect encapsulated peptide from

Frédéric Frézard; Neila M. Silva-Barcellos; Robson A. S. dos Santos

2007-01-01

237

Newly designed modifier prolongs the action of short-lived peptides and proteins by allowing their binding to serum albumin.  

PubMed

We found that human serum albumin (HSA) contains a single binding domain for derivatives of long-chain fatty acid (LCFA)-like molecules in which the carboxylate is replaced by sulfonate. Accordingly, we have synthesized 16-sulfo-hexadecanoic acid-N-hydroxysuccinimide ester [HO(3)S-(CH(2))(15)-CONHS], an agent that reacts selectively with the amino side chains of peptides and proteins. A macromolecule containing a single 16-sulfohexadecanoate moiety associating with albumin with a K(a) value of 0.83 ± 0.08 × 10(6) M(-1), a sufficient affinity to extend the actions in vivo of such short-lived peptides and proteins. Subcutaneous administration of insulin-NHCO-(CH(2))(15)-SO(3)(-) into mice facilitated a glucose-lowering effect 4.3 times in duration and 6.6 times in area under the curve (AUC) as compared to an in vitro equipotent amount of Zn(2+)-free insulin. Similarly, subcutaneous and intravenous administration of exendin-4-NHCO-(CH(2))(15)-SO(3)(-) to mice yielded prolonged and stable reduction in glucose level, 5-9-fold longer than that of exendin-4. Also, a single subcutaneous administration of human interferon-?2-[NH-CO-(CH(2))(15)-SO(3)(-)](3) to mice yielded circulating antiviral activity over a period of 40 h. In conclusion, a simple, hydrophilic reagent has been engineered, synthesized, and studied. Its linkage to peptides and proteins in a monomodified fashion yielded hydrophilic, prolonged acting derivatives, due to their acquired ability to associate with serum albumin after administration. PMID:22759320

Shechter, Yoram; Sasson, Keren; Lev-Goldman, Vered; Rubinraut, Sara; Rubinstein, Menachem; Fridkin, Mati

2012-07-17

238

Coastal measurements of short-lived reactive iodocarbons and bromocarbons at Roscoff, Brittany during the RHaMBLe campaign  

NASA Astrophysics Data System (ADS)

Atmospheric concentrations of the volatile reactive iodocarbons C2H5I, 1-C3H7I, 2-C3H7I, CH2ICl, CH2IBr, CH2I2 and bromocarbons CH2Br2 and CHBr3 were determined by GC/MS analysis of marine boundary layer air at Roscoff, Brittany on the northwest coast of France during September 2006. Comparison with other coastal studies suggests that emissions of these trace gases are strongly influenced by site topography, seaweed populations and distribution, as well as tide height. Concentrations of the very short-lived dihalomethanes CH2IBr and CH2I2 in particular showed evidence of tidal dependence, with higher concentrations observed at low tide during maximum exposure of seaweed beds. We also present a limited number of halocarbon concentrations in surface seawater and estimate sea-air fluxes based on simultaneous water and air measurements of these gases. CH2Br2 and CHBr3 were strongly correlated both in air and in seawater, with CH2Br2/CHBr3 ratios of 0.19 in air and 0.06 in water. The combined midday I atom flux from the photolabile diahlomethanes CH2I2, CH2IBr and CH2ICl of ~5×103 molecules cm-3 s-1 is several orders of magnitude lower than the estimated I atom flux from I2 based on coinciding measurements at the same site, which indicates that at Roscoff the major I atom precursor was I2 rather than reactive iodocarbons.

Jones, C. E.; Hornsby, K. E.; Dunk, R. M.; Leigh, R. J.; Carpenter, L. J.

2009-08-01

239

Coastal measurements of short-lived reactive iodocarbons and bromocarbons at Roscoff, Brittany during the RHaMBLe campaign  

NASA Astrophysics Data System (ADS)

Atmospheric concentrations of the volatile reactive iodocarbons C2H5I, 1-C3H7I, 2-C3H7I, CH2ICl, CH2IBr, CH2I2 and bromocarbons CH2Br2 and CHBr3 were determined by GC/MS analysis of marine boundary layer air at Roscoff, Brittany on the northwest coast of France during September 2006. Comparison with other coastal studies suggests that emissions of these trace gases are strongly influenced by site topography, seaweed populations and distribution, as well as wind speed and direction and tide height. Concentrations of the very short-lived dihalomethanes CH2IBr and CH2I2 in particular showed evidence of tidal dependence, with higher concentrations observed at low tide during maximum exposure of seaweed beds. We also present a limited number of halocarbon measurements in surface seawater and estimate sea-air fluxes based on these and simultaneous air measurements. CH2Br2 and CHBr3 were strongly correlated both in air and in seawater, with CH2Br2/CHBr3 ratios of 0.19 in air and 0.06 in water. The combined midday I atom flux from the photolabile diahlomethanes CH2I2, CH2IBr and CH2ICl of ~5×103 molecules cm-3 s-1 is several orders of magnitude lower than the estimated I atom flux from I2 based on coinciding measurements at the same site, which indicates that at Roscoff the major I atom precursor was I2 rather than reactive iodocarbons.

Jones, C. E.; Hornsby, K. E.; Dunk, R. M.; Leigh, R. J.; Carpenter, L. J.

2009-11-01

240

Short- and long-term consequences of individual and territory quality in a long-lived bird.  

PubMed

Site-quality is a major determinant of fitness but its effect can be confounded by individual quality, a relationship that has been little studied in large, long-lived vertebrates. The fitness effects of quality estimates depend on the assumption of co-variation between individual and territory quality and can be framed as five working hypotheses: no effect on fitness, exclusive effect of individual quality, exclusive effect of site quality, and independent or interactive effects of the two. We explored such a framework using a medium-sized raptor, the black kite Milvus migrans, as a model species. Individual and territory quality co-varied, but the strength of the relationship varied across different estimates of individual quality (age, body size, or mass residuals). Short-term production of fledglings was related to the independent effects of both individual and territory quality. However, longer-term production of recruits was related solely to territory quality. The disappearance of individual quality effects over the long-term may be caused by antagonistic selective pressures acting during different stages of the life cycle. Our results contribute to a growing appreciation of the long-term fitness-benefits of advantages experienced in early life and highlight the importance of a long-term perspective in studies assessing the effects of individual and territory quality. In our case study, prioritizing sites for conservation on the basis of territory quality may be a feasible pathway to maintain the viability of the population. However, scenarios where such a method could be inefficient have been previously reported, suggesting caution in its application. More studies are needed to understand the generality of the efficiency of priority-setting approaches based on site quality. PMID:19288137

Sergio, Fabrizio; Blas, Julio; Baos, Raquel; Forero, Manuela G; Donázar, José Antonio; Hiraldo, Fernando

2009-03-14

241

ICV-Transplanted Human Glial Precursor Cells Are Short-Lived Yet Exert Immunomodulatory Effects in Mice with EAE  

PubMed Central

Human glial precursor cells (hGPs) have potential for remyelinating lesions and are an attractive cell source for cell therapy of multiple sclerosis (MS). To investigate whether transplanted hGPs can affect the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS, we evaluated the therapeutic effects of transplanted hGPs together with the in vivo fate of these cells using magnetic resonance imaging (MRI) and bioluminescence imaging (BLI). At 14 days post-EAE induction, mice (n = 19) were intracerebroventricularly (ICV) injected with 5 × 105 hGPs that were magnetically labeled with superparamagnetic iron oxide (SPIO) particles as MR contrast agent and transduced with firefly luciferase for BLI of cell survival. Control mice (n = 18) received phosphate buffered saline (PBS) vehicle only. The severity of EAE clinical disability in the hGP-transplanted group was significantly suppressed (P < 0.05) with concomitant inhibition of ConA and MOG-specific T cell proliferation in the spleen. Astrogliosis was reduced and a lower activity of macrophages and/or microglia was observed in the spinal cord (P < 0.05). On MRI, SPIO signal was detected within the lateral ventricle from 1 day post-transplantation and remained there for up to 34 days. BLI indicated that most cells did not survive beyond 5–10 days, consistent with the lack of detectable migration into the brain parenchyma and the histological presence of an abundance of apoptotic cells. Transplanted hGPs could not be detected in the spleen. We conclude that ICV transplantation of short-lived hGPs can have a remote therapeutic effect through immunomodulation from within the ventricle, without cells directly participating in remyelination.

KIM, HEECHUL; WALCZAK, PIOTR; MUJA, NASER; CAMPANELLI, JAMES T.; BULTE, JEFF W. M.

2013-01-01

242

SHORT-LIVED STAR-FORMING GIANT CLUMPS IN COSMOLOGICAL SIMULATIONS OF z Almost-Equal-To 2 DISKS  

SciTech Connect

Many observed massive star-forming z Almost-Equal-To 2 galaxies are large disks that exhibit irregular morphologies, with Almost-Equal-To 1 kpc, Almost-Equal-To 10{sup 8}-10{sup 10}M{sub o-dot} clumps. We present the largest sample to date of high-resolution cosmological smoothed particle hydrodynamics simulations that zoom-in on the formation of individual M{sub *} Almost-Equal-To 10{sup 10.5}M{sub o-dot} galaxies in Almost-Equal-To 10{sup 12}M{sub o-dot} halos at z Almost-Equal-To 2. Our code includes strong stellar feedback parameterized as momentum-driven galactic winds. This model reproduces many characteristic features of this observed class of galaxies, such as their clumpy morphologies, smooth and monotonic velocity gradients, high gas fractions (f{sub g} Almost-Equal-To 50%), and high specific star formation rates ({approx}>1 Gyr{sup -1}). In accord with recent models, giant clumps (M{sub clump} Almost-Equal-To (5 Multiplication-Sign 10{sup 8}-10{sup 9})M{sub o-dot}) form in situ via gravitational instabilities. However, the galactic winds are critical for their subsequent evolution. The giant clumps we obtain are short-lived and are disrupted by wind-driven mass loss. They do not virialize or migrate to the galaxy centers as suggested in recent work neglecting strong winds. By phenomenologically implementing the winds that are observed from high-redshift galaxies and in particular from individual clumps, our simulations reproduce well new observational constraints on clump kinematics and clump ages. In particular, the observation that older clumps appear closer to their galaxy centers is reproduced in our simulations, as a result of inside-out formation of the disks rather than inward clump migration.

Genel, Shy; Genzel, Reinhard; Foerster Schreiber, Natascha M. [Max Planck Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85748 Garching (Germany); Naab, Thorsten; Oser, Ludwig [Max Planck Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Sternberg, Amiel [Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Johansson, Peter H. [Department of Physics, University of Helsinki, Gustaf Haellstroemin katu 2a, FI-00014 Helsinki (Finland); Dave, Romeel [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Oppenheimer, Benjamin D. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Burkert, Andreas, E-mail: shy@mpe.mpg.de, E-mail: genzel@mpe.mpg.de, E-mail: forster@mpe.mpg.de, E-mail: amiel@wise.tau.ac.il, E-mail: naab@mpa-garching.mpg.de, E-mail: oser@usm.lmu.de, E-mail: burkert@usm.lmu.de, E-mail: phjohans@astro.helsinki.fi, E-mail: rad@as.arizona.edu, E-mail: oppenheimer@strw.leidenuniv.nl [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany)

2012-01-20

243

Continuous on-line chromatography of short lived isotopes of tungsten as homolog of seaborgium (element 106)  

Microsoft Academic Search

Summary. We have studied the sorption of W on anion-ex- change resins from HNO3\\/HF solutions under on-line con- ditions using continuous chromatography with the multi-col- umn technique. Kd values and the charge of the W species were determined. In order to achieve an effective separation of mother (W) and daughter (Ta), also the sorption of Ta from HNO3\\/HF solutions on

G. Pfrepper; R. Pfrepper; A. Kronenberg; Jens Volker Kratz; A. Nähler; W. Brüchle; M. Schädel

2000-01-01

244

Re-Os isotopic evidence for long-lived heterogeneity and equilibration processes in the Earth's upper mantle  

NASA Astrophysics Data System (ADS)

The geochemical composition of the Earth's upper mantle is thought to reflect 4.5 billion years of melt extraction, as well as the recycling of crustal materials. The fractionation of rhenium and osmium during partial melting in the upper mantle makes the Re-Os isotopic system well suited for tracing the extraction of melt and recycling of the resulting mid-ocean-ridge basalt. Here we report osmium isotope compositions of more than 700 osmium-rich platinum-group element alloys derived from the upper mantle. The osmium isotopic data form a wide, essentially gaussian distribution, demonstrating that, with respect to Re-Os isotope systematics, the upper mantle is extremely heterogeneous. As depleted and enriched domains can apparently remain unequilibrated on a timescale of billions of years, effective equilibration seems to require high degrees of partial melting, such as occur under mid-ocean ridges or in back-arc settings, where percolating melts enhance the mobility of both osmium and rhenium. We infer that the gaussian shape of the osmium isotope distribution is the signature of a random mixing process between depleted and enriched domains, resulting from a `plum pudding' distribution in the upper mantle, rather than from individual melt depletion events.

Meibom, Anders; Sleep, Norman H.; Chamberlain, C. Page; Coleman, Robert G.; Frei, Robert; Hren, Michael T.; Wooden, Joseph L.

2002-10-01

245

Application of mass spectrometric techniques for the trace analysis of short-lived iodine-containing volatiles emitted by seaweed.  

PubMed

Knowledge of the composition and emission rates of iodine-containing volatiles from major widespread seaweed species is important for modeling the impact of halogens on gas-phase atmospheric chemistry, new particle formation, and climate. In this work, we present the application of mass spectrometric techniques for the quantification of short-lived iodine-containing volatiles emitted by eight different seaweeds from the intertidal zone of Helgoland, Germany. A previously developed online time-of-flight aerosol mass spectrometric method was used to determine I(2) emission rates and investigate temporally resolved emission profiles. Simultaneously, iodocarbons were preconcentrated on solid adsorbent tubes and quantified offline using thermodesorption-gas chromatography-mass spectrometry. The total iodine content of the seaweeds was determined using microwave-assisted tetramethylammonium hydroxide extraction followed by inductively coupled-plasma mass spectrometry analysis. The highest total iodine content was found in the Laminariales, followed by the brown algae Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, and both red algae Chondrus crispus and Delesseria sanguinea. Laminariales were found to be the strongest I(2) emitters. Time series of the iodine release of Laminaria digitata and Laminaria hyperborea showed a strong initial I(2) emission when first exposed to air followed by an exponential decline of the release rate. For both species, I(2) emission bursts were observed. For Laminaria saccharina und F. serratus, a more continuous I(2) release profile was detected, however, F. serratus released much less I(2). A. nodosum and F. vesiculosus showed a completely different emission behavior. The I(2) emission rates of these species were slowly increasing with time during the first 1 to 2 h until a more or less stable I(2) emission rate was reached. The lowest I(2) emission rates were detected for the red algae C. crispus and D. sanguinea. Total iodocarbon emission rates showed almost the same general trend, however, the total iodocarbon emission rates were about one to two orders of magnitude lower than those of molecular iodine, demonstrating that I(2) is the major iodine containing volatile released by the investigated seaweed species. In addition, a clear dependency of iodocarbon emission from the ozone level (0-150 ppb O(3)) was found for L. digitata. PMID:22227744

Kundel, Michael; Thorenz, Ute R; Petersen, Jan H; Huang, Ru-Jin; Bings, Nicolas H; Hoffmann, Thorsten

2012-01-08

246

Short-Lived Effector CD8 T Cells Induced by Genetically Attenuated Malaria Parasite Vaccination Express CD11c.  

PubMed

Vaccination with a single dose of genetically attenuated malaria parasites can induce sterile protection against sporozoite challenge in the rodent Plasmodium yoelii model. Protection is dependent on CD8(+) T cells, involves perforin and gamma interferon (IFN-?), and is correlated with the expansion of effector memory CD8(+) T cells in the liver. Here, we have further characterized vaccine-induced changes in the CD8(+) T cell phenotype and demonstrated significant upregulation of CD11c on CD3(+) CD8b(+) T cells in the liver, spleen, and peripheral blood. CD11c(+) CD8(+) T cells are predominantly CD11a(hi) CD44(hi) CD62L(-), indicative of antigen-experienced effector cells. Following in vitro restimulation with malaria-infected hepatocytes, CD11c(+) CD8(+) T cells expressed inflammatory cytokines and cytotoxicity markers, including IFN-?, tumor necrosis factor alpha (TNF-?), interleukin-2 (IL-2), perforin, and CD107a. CD11c(-) CD8(+) T cells, on the other hand, expressed negligible amounts of all inflammatory cytokines and cytotoxicity markers tested, indicating that CD11c marks multifunctional effector CD8(+) T cells. Coculture of CD11c(+), but not CD11c(-), CD8(+) T cells with sporozoite-infected primary hepatocytes significantly inhibited liver-stage parasite development. Tetramer staining for the immunodominant circumsporozoite protein (CSP)-specific CD8(+) T cell epitope demonstrated that approximately two-thirds of CSP-specific cells expressed CD11c at the peak of the CD11c(+) CD8(+) T cell response, but CD11c expression was lost as the CD8(+) T cells entered the memory phase. Further analyses showed that CD11c(+) CD8(+) T cells are primarily KLRG1(+) CD127(-) terminal effectors, whereas all KLRG1(-) CD127(+) memory precursor effector cells are CD11c(-) CD8(+) T cells. Together, these results suggest that CD11c marks a subset of highly inflammatory, short-lived, antigen-specific effector cells, which may play an important role in eliminating infected hepatocytes. PMID:23980113

Cooney, Laura A; Gupta, Megha; Thomas, Sunil; Mikolajczak, Sebastian; Choi, Kimberly Y; Gibson, Claire; Jang, Ihn K; Danziger, Sam; Aitchison, John; Gardner, Malcolm J; Kappe, Stefan H I; Wang, Ruobing

2013-08-26

247

Age and isotopic relationships among the angrites Lewis Cliff 86010 and Angra DOS Reis  

Microsoft Academic Search

The paper presents results of a wide-ranging isotopic investigation of the the Antarctic angrite LEW-86010 (LEW), and reassesses the type angrite Angra dos Reis (ADOR) in order to obtain precise radiometric ages and initial Sr isotopic compositions, and to search for the erstwhile presence of the short-lived nuclei Sm-146 and Al-26 via their daughter products. The isotopic compositions of Sm,

G. W. Lugmair; S. J. G. Galer

1992-01-01

248

Comment on 'Electron-induced bond breaking at low energies in HCOOH and glycine: The role of very short-lived {sigma}* anion states'  

SciTech Connect

Recent model calculations by Gallup et al. [Phys. Rev. A79, 042710 (2009)] suggest that low-energy dissociative electron attachment to formic acid can be explained solely in terms of a very short-lived {sigma}* anion state and that no {sigma}*/{pi}* coupling is required. We argue that this interpretation of the experimental data, which is at odds with our earlier study, is flawed.

Rescigno, T. N. [Lawrence Berkeley National Laboratory, Chemical Sciences, Berkeley, California 94720 (United States); Trevisan, C. S. [California Maritime Academy, Vallejo, California 94590 (United States); Orel, A. E. [Department of Applied Science, University of California, Davis, California 95616 (United States)

2009-10-15

249

Neutron Activation analysis for Dy, Hf, Rb, Sc and Se in some Ghanaian cereals and vegetables using short-lived nuclides and Compton suppression spectrometry  

Microsoft Academic Search

A pseudo-cyclic instrumental neutron activation analysis (PCINAA) method has been developed to determine selected elements in various types of cereal and vegetable from Ghana using relatively short-lived nuclides (t1\\/2<80s) and the Compton suppression counting. The samples were irradiated for 10s at the Dalhousie University SLOWPOKE-2 research reactor facility (DUSR) and allowed to decay for 20s, and counted for 40s. The

B. J. B. Nyarko; E. H. K. Akaho; J. J. Fletcher; A. Chatt

2008-01-01

250

On search and identification of short-lived super heavy cosmic-ray nuclei (Z >= 110) by fossil track study of the extraterrestrial crystals: Results and perspectives [II  

NASA Astrophysics Data System (ADS)

The existence of relatively stable super heavy elements (SHE) in Nature was predicted theoretically at the midst of the sixties (Nilsson, Nix, Sobichevsky, see Ref. [1]). Basing on nuclear shell model it was estimated, that double magic nuclei with atomic number 110 <= Z <= 114 and neutron number N = 184, namely, the double ``magic'' closed shells of nuclei can possess the life time at >=103 up to 109 years. Thus, these elements, similarly to Th and U, can survive in the Earth and meteorites since formation of Solar system ~ 4.6 billion years ago. The present project work was drastically stimulated by recent synthesis and discovery of very stable isotopes of SHE in Flerov Laboratory of Nuclear Reactions During 1999-2000 Oganessian and his colleagues succeed in obtaining of a number of rather neutron-rich isotopes of elements 112, 114 and 116 in the reactions of 48Ca with monoisotopic targets of 238U, 244Pu and 248Cm, respectively [2]. The most stable isotope obtained is odd-even nuclear 285112, which possess the life time in between 10-30 min. Still this isotope has only 173 neutrons which is 11 fewer as compared with the magic number N = 184. For the region of known actinide nuclei (Z = 89 - 98) such a neutron difference for the most stable isotopes provides the stabilization factor of 1010 - 1013 in the life time. The discovery of very stable isotope of the new element 112 provides firstly the final unambiguous proof on the existence of new island of very stable SHE nuclei. Now we pointed out that there is no way to get the neutron number N = 184 using present accelerators and target nuclei. The only one way to find out double magic SHE nuclei now is the search for these nuclei in natural samples. The experimental attempts to discover such long-lived SHE nuclei with the life time >=2×108 y in natural samples undertaken during the late sixties up to end of seventies provided some evidence of their existence in a number of both terrestrial samples and meteorites. These experiments were done by the investigation of alpha radioactivity and spontaneous fission activity, which exceeds significantly the effect due to the spontaneous fission of 238U nuclide. Still no decisive information on the existence of SHE in the nature was obtained.

Perelygin, V. P.; Abdullaev, I. G.; Bondar, Yu. V.; Brandt, R.; Chuburkov, Yu. T.; Kashkarov, L. L.; Knyazeva, G. P.; Kravets, L. I.; Spohr, R.; Stetsenko, S. G.; Vater, P.

2003-05-01

251

Re-Os Isotopic Evidence for Long-Lived Heterogeneity and Equilibration Processes in Earth's Upper Mantle  

NASA Astrophysics Data System (ADS)

Compared to other incompatible lithophile isotope systems the Re-Os isotopic system is very well suited for tracing extraction and subduction of Mid-Ocean Ridge Basalt (MORB). During partial melting Re is mildly incompatible whereas Os is strongly compatible resulting in high Re/Os elemental ratios in MORB and correspondingly low Re/Os ratios in the depleted solid residue left behind. As 187Re decays to 187Os the 187Os/188Os ratios of MORB and depleted mantle residue will diverge. MORB develops high, radiogenic 187Os/188Os ratios while the depleted mantle residues develop relatively low, un-radiogenic 187Os/188Os ratios. When MORB is subducted back into the upper mantle re-equilibration with the depleted mantle residue is expected to take place, but the time scales and length scales on which this re-equilibration occurs are poorly constrained. We report osmium isotope compositions of more than 700 mantle-derived Os-rich platinum-group element alloys thought to represent the upper mantle. Our data form a wide, essentially Gaussian distribution demonstrating that, with respect to Re-Os isotope systematics, the upper mantle is extremely heterogeneous. Depleted and enriched domains can remain un-equilibrated on a time scale of billions of years. Effective equilibration between these domains probably requires high degrees of partial melting, such as occur under mid-ocean ridges or in back-arc settings, where percolating melts enhance the mobility of both Os and Re. The Gaussian shape of the Os isotope distribution is a signature of a random mixing process between depleted and enriched domains in a plum-pudding configuration in the upper mantle, rather than the result of individual melt depletion events. Our data lend strong support to the view that secondary metasomatic melt-rock processes define not only the major and trace element chemistry of mantle derived rocks but also their Re-Os isotope systematics. These processes can mask primary melt depletion features related to previous times that the material passed through an upper mantle region with high degrees of partial melting.

Meibom, A.; Sleep, N. H.; Chamberlain, C.; Coleman, R. G.; Frei, R.; Hren, M. T.; Wooden, J. L.

2002-12-01

252

Investigation into the neutron multiplicity of spontaneously fissioning short-lived heavy nuclei at the VASSILISSA separator  

NASA Astrophysics Data System (ADS)

For experiments aimed at the study of the spontaneous fission of transfermium nuclei, improvements in the focal-plane detector system of the VASSILISSA recoil separator have been made. A neutron detector consisting of 54 3He-filled counters has been mounted around the focal-plane detector chamber. A description of the detection system and the results of experiments aimed at investigating the neutron multiplicity of neutron-deficient isotopes of 252No and 244,246Fm are presented.

Svirikhin, A. I.; Gupta, M.; Eremin, A. V.; Izosimov, I. N.; Isaev, A. V.; Kuznetsov, A. N.; Malyshev, O. N.; Mulins, S.; Popeko, A. G.; Sokol, E. A.; Chelnokov, M. L.; Chepihin, V. I.

2012-01-01

253

Climate response to projected changes in short-lived species under an A1B scenario from 2000-2050 in the GISS climate model  

SciTech Connect

We investigate the climate forcing from and response to projected changes in short-lived species and methane under the A1B scenario from 2000-2050 in the GISS climate model. We present a meta-analysis of new simulations of the full evolution of gas and aerosol species and other existing experiments with variations of the same model. The comparison highlights the importance of several physical processes in determining radiative forcing, especially the effect of climate change on stratosphere-troposphere exchange, heterogeneous sulfate-nitrate-dust chemistry, and changes in methane oxidation and natural emissions. However, the impact of these fairly uncertain physical effects is substantially less than the difference between alternative emission scenarios for all short-lived species. The net global mean annual average direct radiative forcing from the short-lived species is .02 W/m{sup 2} or less in our projections, as substantial positive ozone forcing is largely offset by negative aerosol direct forcing. Since aerosol reductions also lead to a reduced indirect effect, the global mean surface temperature warms by {approx}0.07 C by 2030 and {approx}0.13 C by 2050, adding 19% and 17%, respectively, to the warming induced by long-lived greenhouse gases. Regional direct forcings are large, up to 3.8 W/m{sup 2}. The ensemble-mean climate response shows little regional correlation with the spatial pattern of the forcing, however, suggesting that oceanic and atmospheric mixing generally overwhelms the effect of even large localized forcings. Exceptions are the polar regions, where ozone and aerosols may induce substantial seasonal climate changes.

Menon, Surabi; Shindell, Drew T.; Faluvegi, Greg; Bauer, Susanne E.; Koch, Dorothy M.; Unger, Nadine; Menon, Surabi; Miller, Ron L.; Schmidt, Gavin A.; Streets, David G.

2007-03-26

254

Evidence from the waking electroencephalogram that short sleepers live under higher homeostatic sleep pressure than long sleepers  

Microsoft Academic Search

We used the waking electroencephalogram to study the homeostatic sleep regulatory process in human short sleepers and long sleepers. After sleeping according to their habitual schedule, nine short sleepers (sleep duration <6h) and eight long sleepers (>9h) were recorded half-hourly during ?40h of wakefulness in a constant routine protocol. Within the frequency range of 0.25–20.0Hz, spectral power density in the

D. AESCHBACH; T. T. POSTOLACHE; L. SHER; J. R. MATTHEWS; M. A. JACKSON; T. A. WEHR

2001-01-01

255

On the Possibility of Improving the Mean Useful Life of Items by Eliminating Those with Short Lives  

Microsoft Academic Search

When everything possible has been done to produce articles with long lives, there remains the possibility that a further improvement in the articles may be obtained by running them, for some time, under realistic conditions. The fraction that does not fail may have a longer mean remaining life than the original articles. In this paper conditions on the life distribution

G. S. Watson; W. T. Wells

1961-01-01

256

Activation cross-section measurements for producing short-lived nuclei with 14 MeV neutrons—Ge, Pd, Yb  

NASA Astrophysics Data System (ADS)

Activation cross sections for 70Ge(n,p)70Ga, 74Ge(n,p)74Ga, 108Pd(n,p)108Rh, 110Pd(n,?)107Ru, and 174Yb(n,p)174Tm reactions producing short-lived nuclei with half-lives of several minutes were measured in the energy between 13.5 and 14.8 MeV using activation technique in this work. All cross-section values were relatively obtained on the basis of the standard cross section of 93Nb(n,2n)92Nb or 27Al(n,?)24Na, and the neutron energies were measured by the method of cross-sectional ratios for 90Zr(n,2n)89Zr to 93Nb(n,2n)92Nb reactions. Careful attention on corrections was paid to neutron irradiation and induced activities measurement. The measured results were discussed and compared with the previous works.

Lan, Chang-Lin; Fang, Kai-Hong; Xu, Xiao-San; Wang, Qi; Kong, Xiang-Zhong; Liu, Rong; Jiang, Li

2008-07-01

257

Freshly induced short-lived gamma-ray activity as a measure of fission rates in lightly re-irradiated spent fuel  

NASA Astrophysics Data System (ADS)

A new measurement technique has been developed to determine fission rates in burnt fuel, following re-irradiation in a zero-power research reactor. The development has been made in the frame of the LIFE@PROTEUS program at the Paul Scherrer Institute, which aims at characterizing the interfaces between fresh and highly burnt fuel assemblies in modern LWRs.To discriminate against the high intrinsic gamma-ray activity of the burnt fuel, the proposed measurement technique uses high-energy gamma-rays, above 2000 keV, emitted by short-lived fission products freshly produced in the fuel. To demonstrate the feasibility of this technique, a fresh UO2 sample and a 36 GWd/t burnt UO2 sample were irradiated in the PROTEUS reactor and their gamma-ray activities were recorded directly after irradiation.For both fresh and the burnt fuel samples, relative fission rates were derived for different core positions, based on the short-lived 142La (2542 keV), 89Rb (2570 keV), 138Cs (2640 keV) and 95Y (3576 keV) gamma-ray lines. Uncertainties on the inter-position fission rate ratios were mainly due to the uncertainties on the net-area of the gamma-ray peaks and were about 1-3% for the fresh sample, and 3-6% for the burnt one. Thus, for the first time, it has been shown that the short-lived gamma-ray activity, induced in burnt fuel by irradiation in a zero-power reactor, can be used as a quantitative measure of the fission rate. For both fresh and burnt fuel, the measured results agreed, within the uncertainties, with Monte Carlo (MCNPX) predictions.

Kröhnert, H.; Perret, G.; Murphy, M. F.; Chawla, R.

2010-12-01

258

Comparisons of the ecology and stable isotopic compositions of living (stained) benthic foraminifera from the Sulu and South China Seas  

Microsoft Academic Search

Significant differences are observed between living (Rose Bengal stained) deep-sea benthic foraminifera found in 14 box cores (510–4515 m) from the thermospheric (> 10°C) environments of the Sulu Sea and the psychrospheric (<10°C) conditions in the South Ch ina Sea. Gavelinopsis, Bolivinopsis, Astrononion, Osangularia and Ceratobulimina are common taxa in the South China Sea, but are rare to absent in

A. E. Rathburn; B. H. Corliss; K. D. Tappa; K. C. Lohmann

1996-01-01

259

Discovery of Highly Excited Long-Lived Isomers in Neutron-Rich Hafnium and Tantalum Isotopes through Direct Mass Measurements  

SciTech Connect

A study of cooled {sup 197}Au projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides {sup 183,184,186}Hf and {sup 186,187}Ta. The results support the prediction of a strongly favored isomer region near neutron number 116.

Reed, M. W.; Cullen, I. J.; Walker, P. M.; Deo, A. Y.; Kempley, R. S.; Swan, T. P. D. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Litvinov, Yu. A.; Winckler, N. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany); Blaum, K. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Bosch, F.; Dimopoulou, C.; Farinon, F.; Heil, M.; Knoebel, R.; Kozhuharov, C.; Kurcewicz, J.; Kuzminchuk, N.; Litvinov, S.; Nociforo, C.; Nolden, F. [GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, 64291 Darmstadt (Germany)

2010-10-22

260

Bromine and iodine chemistry in a global chemistry-climate model: description and evaluation of very short-lived oceanic sources  

Microsoft Academic Search

The global chemistry-climate model CAM-Chem has been extended to incorporate an expanded bromine and iodine chemistry scheme that includes natural oceanic sources of very short-lived (VSL) halocarbons, gas-phase photochemistry and heterogeneous reactions on aerosols. Ocean emissions of five VSL bromocarbons (CHBr3, CH2Br2, CH2BrCl, CHBrCl2, CHBr2Cl) and three VSL iodocarbons (CH2ICl, CH2IBr, CH2I2) have been parameterised by a biogenic chlorophyll-a (chl-a)

C. Ordóñez; J.-F. Lamarque; S. Tilmes; D. E. Kinnison; E. L. Atlas; D. R. Blake; G. Sousa Santos; G. Brasseur; A. Saiz-Lopez

2011-01-01

261

Crustal reworking during a long-lived magma pulse: 11 m.y. isotopic record from the Aucanquilcha Volcanic Cluster, central Andes  

NASA Astrophysics Data System (ADS)

Since ~11 Ma, successive eruptions from the Aucanquilcha Volcanic Cluster (AVC) in northern Chile document the magmatic evolution of a long-lived subduction system. Situated within the central volcanic zone of the Andes, the AVC is constructed upon remarkably thick (~70 km) crust—a heterogeneous filter through which all central Andean lavas are extensively processed and modified. The 11 m.y. history of the AVC is characterized by sluggish eruption rates from ~11-5 Ma, with an increase in eruptive output between ~5-2.5 Ma, and a return to modest eruption rates from ~2.5 Ma to present. This pattern is attributed to the waxing, climactic, and waning stages of a magmatic ‘pulse’. Eruptive pulsing in the form of long-lived magmatic systems appears to be not uncommon (cf. APVC, Tuolumne, SRMVF), and we exploit the AVC lavas to explore the geochemical signal accompanying the evolution of such a system. More specifically, isotopes (whole rock Sr, Nd, Pb; O from plagioclase) and trace elements of the AVC lavas are employed to investigate the compositional influence of the crustal filter on the production of arc lavas. 87Sr/86Sr of AVC andesite to dacite lavas ranges from 0.70509 to 0.70680, with a broad increase through time. Three analyses from nearby, recently erupted basaltic andesite scoria cones yield relatively high ratios of 0.706347 - 0.706826. 143Nd/144Nd ranges from 0.512262 - 0.512590 (scoria cones: 0.512300 - 0.512323), and decrease through time, consistent with the Sr data. ?18O ranges from 6.47 to 7.47, with the lowest values associated with the onset of AVC volcanism. 206Pb/204Pb ranges from 18.4679 to 18.7039, with a small, but distinguishable, increase through time. Dy/Yb ranges from 1.79 - 3.45 and Sm/Yb ranges from 2.18 - 6.66, with a marked increase from 11 Ma to present. The AVC is situated on the boundary between two distinct Pb domains (Arequipa and Antofalla) of the central Andean crust. The minor fluctuation seen in Pb isotopes through time likely results from the tapping of these two different (and probably stacked) crustal Pb reservoirs. Trends in the Sr and Nd (and to a lesser extent, O) isotopic ratios suggest an increase in the crustal influence (or changing crustal source) with progressive magmatism at the AVC. Increasing Dy/Yb and Sm/Yb (MREE/HREE) ratios through time indicate an increasing role of garnet in the residuum of crustal melting, suggesting an increasing crustal thickness with time. Despite the overall trend toward more crustally contaminated compositions through time, there is a focusing of the isotopic values (at ~low Sr and ~high Nd) during the eruptive flare-up from ~5-2.5 Ma. During this time of high mantle flux, the crustal isotopic signature is likely being diluted in the lavas by mantle components. As the influx from the mantle wanes, the crustal signature becomes more pronounced with successive eruptions. In this sense, the balance between mantle power and thermal maturity of the crust, in addition to crustal character, bears heavily on the compositions of the lavas and the reworked arc crust.

Walker, B. A.; Grunder, A.

2010-12-01

262

Short and long-term consequences of individual and territory quality in a long-lived bird  

Microsoft Academic Search

Site-quality is a major determinant of fitness but its effect can be confounded by individual quality, a relationship that\\u000a has been little studied in large, long-lived vertebrates. The fitness effects of quality estimates depend on the assumption\\u000a of co-variation between individual and territory quality and can be framed as five working hypotheses: no effect on fitness,\\u000a exclusive effect of individual

Fabrizio Sergio; Julio Blas; Raquel Baos; Manuela G. Forero; José Antonio Donázar; Fernando Hiraldo

2009-01-01

263

Site-specific responses to short-term environmental variation are reflected in leaf and phloem-sap carbon isotopic abundance of field grown Eucalyptus globulus.  

PubMed

The carbon isotopic composition (?(13) C) of plant material has been used extensively as an indirect measure of carbon fixation per volume of water used. More recently, the ?(13) C of phloem sap (?(13) C(phl) ) has been used as a surrogate measure of short-term, canopy scale ?(13) C. Using a combination of ?(13) C physiological, structural and chemical indices from leaves and phloem sap of Eucalyptus globulus at sites of contrasting water availability, we sought to identify short-term, canopy scale resource limitations. Results illustrate that ?(13) C(phl) offers valid reflections of short-term, canopy scale values of leaf ?(13) C and tree water status. Under conditions limited by water, leaf and phloem sap photoassimilates differ in (13) C abundance of a magnitude large enough to significantly influence predictions of water use efficiency. This pattern was not detected among trees with adequate water supply indicating fractionation into heterotrophic tissues that may be sensitive to plant water status. Trees employed a range of physiological, biochemical and structural adaptations to acclimate to resource limitation that differed among sites providing a useful context upon which to interpret patterns in ?(13) C. Our results highlight that such easily characterized properties are ideal for use as minimally invasive tools to monitor growth and resilience of plants to variations in resource availability. PMID:22568657

Merchant, Andrew; Buckley, Thomas N; Pfautsch, Sebastian; Turnbull, Tarryn L; Samsa, Glen A; Adams, Mark A

2012-05-29

264

New methodology for Ozone Depletion Potentials of short-lived compounds: n-Propyl bromide as an example  

Microsoft Academic Search

A number of the compounds proposed as replacements for substances controlled under the Montreal Protocol have extremely short atmospheric lifetimes, on the order of days to a few months. An important example is n-propyl bromide (also referred to as 1-bromopropane, CH2BrCH2CH 3 or simplified as 1-C3H7Br or nPB). This compound, useful as a solvent, has an atmospheric lifetime of less

Donald J. Wuebbles; Kenneth O. Patten; Matthew T. Johnson; Rao Kotamarthi

2001-01-01

265

Short-lived vegetational and environmental change during the Preboreal in the Biebrza Upper Basin (NE Poland)  

NASA Astrophysics Data System (ADS)

A pollen diagram from the upper Biebrza basin (NE Poland) shows a conspicuous pollen fluctuation around 9650 BP, which is superimposed on a broader pollen fluctuation correlated with a more open vegetation phase during the Preboreal generally found in Europe. High-resolution pollen analyses indicate a duration of only a few years in which Pinus forests became more open. The resulting niches were partly occupied by Betula trees and partly by Betula shrubs, Artemisia, and Chenopodiaceae. Shortly before the increased opening of the upland vegetation, reed vegetation developed in the valley, in which Sparganium and later Typha became prominent. At the end of the short fluctuation, this reed vegetation diminished. The wetland vegetation development might be partly related to hydrological changes caused by a reduced evapotranspiration of the opened upland forest. The data presented here show that the open vegetation phase of the Preboreal was not of uniform character, but that within its short time span of ca 150 years an even shorter fluctuation of a few years to a few decades occurred. It is unknown whether this is a regionally restricted phenomenon or whether it has an extra-regional character.

de Klerk, Pim; Couwenberg, John; Joosten, Hans

2007-08-01

266

Coronaviruses Hijack the LC3-I-positive EDEMosomes, ER-derived vesicles exporting short-lived ERAD regulators, for replication.  

PubMed

Coronaviruses (CoV), including SARS and mouse hepatitis virus (MHV), are enveloped RNA viruses that induce formation of double-membrane vesicles (DMVs) and target their replication and transcription complexes (RTCs) on the DMV-limiting membranes. The DMV biogenesis has been connected with the early secretory pathway. CoV-induced DMVs, however, lack conventional endoplasmic reticulum (ER) or Golgi protein markers, leaving their membrane origins in question. We show that MHV co-opts the host cell machinery for COPII-independent vesicular ER export of a short-living regulator of ER-associated degradation (ERAD), EDEM1, to derive cellular membranes for replication. MHV infection causes accumulation of EDEM1 and OS-9, another short-living ER chaperone, in the DMVs. DMVs are coated with the nonlipidated LC3/Atg8 autophagy marker. Downregulation of LC3, but not inactivation of host cell autophagy, protects cells from CoV infection. Our study identifies the host cellular pathway hijacked for supplying CoV replication membranes and describes an autophagy-independent role for nonlipidated LC3-I. PMID:20542253

Reggiori, Fulvio; Monastyrska, Iryna; Verheije, Monique H; Calì, Tito; Ulasli, Mustafa; Bianchi, Siro; Bernasconi, Riccardo; de Haan, Cornelis A M; Molinari, Maurizio

2010-06-25

267

Mean Ages and Age Spectra for the Tropical Tropopause Layer From Observations of CO2: Implications for Air Transport and Distributions of Short-Lived Chemical Species  

NASA Astrophysics Data System (ADS)

We present extensive CO2 observations of the TTL as related to the characteristics of TTL structure and transport. The results from the CR-AVE and TC4 missions show that air entering the upper TTL above ~360K retains imprint of the global seasonal cycle derived from the well-measured CO2 at the surface, suggesting that data for CO2 can be used as a principal tool to infer the mean age and age spectrum for the TTL, as in the lower stratosphere (Andrews et al., 2001a, 2001b; Boering et al., 1996; Park et al., 2007). The transport rates in the upper TTL inferred from CO2 are applied to generate vertical distributions in the TTL of short-lived organic halogens, non-methane hydrocarbons and alkyl nitrates, which have potentially major impacts on stratospheric ozone and humidity. New data from the Whole Air Sampler obtained over Central America in August, 2007 demonstrate that direct inputs of these transient tracers are largely limited to altitudes ~2 km below the tropical tropopause, and reactive species are efficiently removed with local lifetimes less than or comparable to the mean age of air in the upper TTL (i.e., ranging from a few days to several months). Interestingly, the observations in the subtropical lowermost stratosphere reveal higher concentrations of these species than at the same isentropic level of the TTL, indicating direct loading by summertime midlatitude convection as one of input pathways of these short-lived species into the stratosphere.

Park, S.; Atlas, E. L.; Jimenez, R.; Daube, B. C.; Gottlieb, E.; Nan, J.; Pfister, L.; Conway, T. J.; Bui, T. P.; Gao, R.; Wofsy, S. C.

2008-12-01

268

Mitochondrial mutations and aging: random drift is insufficient to explain the accumulation of mitochondrial deletion mutants in short-lived animals.  

PubMed

Mitochondrial DNA deletions accumulate over the life course in post-mitotic cells of many species and may contribute to aging. Often a single mutant expands clonally and finally replaces the wild-type population of a whole cell. One proposal to explain the driving force behind this accumulation states that random drift alone, without any selection advantage, is sufficient to explain the clonal accumulation of a single mutant. Existing mathematical models show that such a process might indeed work for humans. However, to be a general explanation for the clonal accumulation of mtDNA mutants, it is important to know whether random drift could also explain the accumulation process in short-lived species like rodents. To clarify this issue, we modelled this process mathematically and performed extensive computer simulations to study how different mutation rates affect accumulation time and the resulting degree of heteroplasmy. We show that random drift works for lifespans of around 100 years, but for short-lived animals, the resulting degree of heteroplasmy is incompatible with experimental observations. PMID:23742009

Kowald, Axel; Kirkwood, Thomas B L

2013-06-07

269

Gold-195m, a new generator-produced short-lived radionuclide for sequential assessment of ventricular performance by first pass radionuclide angiocardiography. [Dogs  

SciTech Connect

The feasibility of performing rapid sequential first pass radionuclide angiocardiography using a new short-lived radiotracer, gold-195m (/sup 195//sup m/Au) half-life 30.5 seconds) was evaluated. This radionuclide emits a 262 keV gamma ray and is the daughter of mercury-195 (/sup 195//sup m/Hg) (half-life 41.6 hours). The prototype table top /sup 195//sup m/Hg//sup 195//sup m/Au generator produced 20 to 25 mCi of /sup 195//sup m/Au in 2 ml of eluate (yield of 40 percent). Four dogs each had 15 to 20 sequential first pass studies performed with /sup 195//sup m/Hg at 3 to 10 minute intervals using a computerized multicrystal gamma camera. During the left ventricular phase, 160,000 to 190,000 counts/s were acquired. The end-diastolic left ventricular region of interest contained 3000 to 6000 counts (background- and decay-corrected). Multiple reproducible values for left ventricular ejection fraction were obtained during stable conditions. During infusion of isoproterenol, rapid increase of left ventricular ejection fraction was demonstrated. Excellent agreement was observed between studies performed with technetium-99m diethylenetriaminepentaacetic acid (/sup 99//sup m/Tc-DTPA) and /sup 195//sup m/Au. This new short-lived radiotracer makes possible rapid sequential assessments of ventricular function at greatly reduced patient exposure to radiation.

Wackers, F.J.; Giles, R.W.; Hoffer, P.B.; Lange, R.C.; Berger, H.J.; Zaret, B.L.

1982-07-01

270

New neutron-deficient isotopes of lanthanum and cerium  

Microsoft Academic Search

The short-lived neutron-deficient isotopes of lanthanum and cerium were produced in the 32S+96, 98Ru reactions and separated according to their masses. Seven isotopes 123-125La and 124-127Ce have been first observed and their half-lives and low-energy gamma-ray data are reported. In addition, low-energy gamma-ray data are given for the 122-125Ba and 127La decays. The beta-decay probabilities for Ce, La and Ba

D. D. Bogdanov; A. V. Demyanov; V. A. Karnaukhov; M. Nowick; L. A. Petrov; J. Voboril; A. Plochocki

1978-01-01

271

Universal Slow RI-Beam Facility at RIKEN RIBF for Laser Spectroscopy of Short-Lived Nuclei  

SciTech Connect

A universal slow RI-beam facility (SLOWRI) for precision atomic spectroscopy is being built at the RIKEN RI-beam factory. The facility will provide a wide variety of low-energy nuclear ions of all elements produced by projectile fragmentation of high-energy heavy-ion beams and thermalized by an RF-carpet ion guide. At prototype SLOWRI, radioactive Be isotope ions produced at 1 GeV were decelerated and cooled in an ion trap down to 1 {mu}eV by employing laser cooling. The ground state hyperfine structures of {sup 7}Be{sup +} and {sup 11}Be{sup +} were measured accurately by laser microwave double resonance spectroscopy. Measurements of the S{sub 1/2}{yields}P{sub 1/2}, P{sub 3/2} transition frequencies of {sup 7,9,10,11}Be{sup +} ions are also in progress aiming at the study of the nuclear charge radii. Other possible experiment at SLOWRI, such as mass spectroscopy, are also discussed.

Wada, M. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, 351-0198 (Japan); Nishina Center for Accelerator Based Science, RIKEN, 2-1 Hirosawa, Wako, 351-0198 Japan (Japan); Takamine, A. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, 351-0198 (Japan); Okada, K. [Department of Physics, Sophia University, 7-1 Kioicho, Chiyoda, Tokyo 102-8554 (Japan); Sonoda, T.; Schury, P.; Kanai, Y.; Kojima, T. M. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, 351-0198 (Japan); Lioubimov, V. [Department of Physics, Texas A and M University, College Station, TX 77843 (United States); Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, 351-0198 Japan (Japan); Yamazaki, Y. [Atomic Physics Laboratory, RIKEN, 2-1 Hirosawa, Wako, 351-0198 Japan (Japan); Graduate School of Arts and Science, University of Tokyo, Meguro, Tokyo 153-8902 (Japan); Yoshida, A.; Kubo, T. [Nishina Center for Accelerator Based Science, RIKEN, 2-1 Hirosawa, Wako, 351-0198 Japan (Japan); Iimura, H. [Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Katayama, I. [Institute of Particle and Nuclear Physics, KEK, Tsukuba, Ibaragi 305-0801 Japan (Japan); Ohtani, S. [Institute for Laser Science, University of Electro-Communications, Chohugaoka, Chohu, Tokyo 182-8585 (Japan); Wollnik, H. [II. Physikalisches Institut, Justus-Liebig-Universitaet Giessem, Giessen (Germany); Schuessler, H. A. [Department of Physics, Texas A and M University, College Station, TX 77843 (United States)

2009-03-17

272

Unattached fraction of short-lived Rn decay products in indoor and outdoor environments: An improved single-screen method and results  

SciTech Connect

The unattached fraction fp of potential alpha energy of short-lived Rn decay products was measured under realistic, natural conditions in different dwellings and in the open atmosphere by a single-screen technique. An improved data evaluation method was developed where the measured activities of {sup 218}Po (RaA) and {sup 214}Pb (RaB) were corrected by the screen-attached activities of {sup 214}Bi ({sup 214}Po) (RaC (RaC')). This method is based on the experimental observation that the {sup 214}Bi ({sup 214}Po) unattached activities are negligible under realistic living conditions and that the size distributions of the aerosol-attached activities of all short-lived Rn daughters are identical. In closed rooms without additional aerosol sources, a mean unattached fraction fp of the potential alpha energy of 0.096 was obtained at a mean aerosol particle concentration of 6100 cm-3 and at a mean equilibrium factor F of 0.30. This mean fp value is about three times higher than the value used in the literature for the radiation exposure calculation of the human public. In closed rooms with additional aerosol sources (cigarette smoke, heating systems, aerosols from a burning candle), the aerosol particle concentrations ranged up to 10(6) cm-3 and the attachment rates, X, increased up to 1000 h-1. The fp values sometimes decreased below the detection limit of 0.005, and the F values increased to as high as 0.77. In the ambient atmosphere in the vicinity of Goettingen, a mean unattached fraction fp of 0.02 and a mean aerosol particle concentration of 3.4 x 10(4) cm-3 were measured at 1 m above the ground. The mean equilibrium factor F was determined to be 0.7.A

Reineking, A.; Porstendoerfer, J. (Universitaet Goettingen (Germany, F.R.))

1990-06-01

273

Seasonal and Short-term Variation of Water Vapor Isotope ratios in Surface Air in Sapporo, Japan  

NASA Astrophysics Data System (ADS)

Stable isotopes of atmospheric water vapor provide information about movement of water and its phase changes in the atmosphere. Surface water vapor's ?D and ?18O measurement was conducted in Sapporo (43.1N, 141.3E), a humid continental site characterized by a warm but not humid summer and a quite cold and snowy winter, in Hokkaido, Japan with a Los Gatos Research's (LGR) Water-Vapor Isotope Analyzer (WVIA, model DLT-100). The observation in Sapporo was carried out in four phases: (I) 28 April 2009 - 25 June 2009; (II) 15 September 2009 - 29 November 2009; (III) 1 April 2010 - 21 May 2010 and (IV) 17 December 2010 - 30 May 2011. In addition, auxiliary data (air temperature, atmospheric pressure, relative humidity, wind speed & direction, etc.) were obtained with an automatic weather station (AWS). Thus, the objective of this study is to investigate the characteristics of ?D and ?18O of atmospheric water vapor near the ground in Sapporo and to explore the meteorological processes that influence ?D and ?18O of atmospheric water vapor at the surface. In general, ?D and ?18O were higher in warm season (PHASES I & III) than in cold season (PHASES II & IV) with almost equal day-to-day ?D variability in both seasons. The lightest ?D (-239.7%) occurs in the month of March/April despite not being the coldest month in Sapporo. This is thought to be due to "rigorous" evaporation due to snow-melting. In addition, over periods of about 1-7days, considerable variations occurred, sometimes exceeding 100% for ?D. These considerable variations were attributable to weather phenomena such as sea-breeze and cold frontal passages. The former causes ?D to increase abruptly while the latter causes an abrupt decrease.

Sunmonu, L. A.; Fujiyoshi, Y.; Muramoto, K.; Kurita, N.

2011-12-01

274

Utilization of short- and medium-lived nuclides for the trace-element characterization of food samples  

SciTech Connect

Food has long been known to play a key role not only in the health status of human beings but also in their social lives. Relationships between food and physical as well as spiritual well-beings have been cited in ancient Chinese, Greek, and Indian literatures. Modern medicine, curative as well as preventive, values the nutritional aspects of food. In this regard, there exists an increasing interest in estimating the average daily intake of biologically important elements through food. Instrumental neutron activation analysis (INAA) is particularly well suited for the simultaneous determinations of major, minor, and trace elements in both individual food items and composite diets. In the present study, emphasis is placed on the development of reliable and rapid INAA methods for measuring concentrations of ten elements of nutritional interest in food samples.

Chatt, A.; McDowell, L.S.; Pegg, D.L.

1986-01-01

275

Temperate carbonate debrites and short-lived earliest Miocene yo-yo tectonics, eastern Taranaki Basin margin, New Zealand  

NASA Astrophysics Data System (ADS)

This study examines two unconformity-bound earliest Miocene temperate shallow-marine limestones at remote Gibson Beach, western North Island, on the eastern margin of Taranaki Basin, New Zealand's only producing hydrocarbon province. The local geology comprises an upper limestone of up to 6 m of spectacular conglomeratic limestone (rudstone; Papakura Limestone) whose pebble- to boulder-sized clasts were derived from cannibalisation of the lower skeletal limestone (bryomol grainstone; Otorohanga Limestone). Multiple lines of evidence require the Otorohanga Limestone to have been well indurated before erosion and clast generation. Cementation occurred from pressure dissolution of calcitic skeletons at burial depths of probably 400 m or more. Subsequent uplift led to local subaerial exposure and karstification of a fault-block cliffed coastline where physical erosion sourced talus limestone debris onto adjacent high-energy pocket beaches. Storm and/or seismic events periodically triggered mass flows of the limestone clasts offshore onto the contemporary mixed siliciclastic-carbonate shelf as channelised carbonate debrites. Lithification of these Papakura Limestone debrites occurred via pressure dissolution, and required a second burial episode. Karst pinnacles preserved on the eroded upper surface of the Papakura Limestone demand uplift again and erosion in a subaerial setting, before subsequent deep burial by Early Miocene siliciclastic shelf sand and turbidite deposits. Strontium isotope dating of brachiopod fossils suggests the two postulated burial-uplift cycles, involving movements up to 400 ± 100 m, occurred very rapidly within several 100 kyr. Speculative drivers of the yo-yo tectonic events are earliest Miocene movements on the nearby major Taranaki Fault thrust in association with regional changes in subduction tectonics at the Australian-Pacific plate boundary, along with pulsed emplacement of obducted gravity slide deposits (Northland Allochthon) onto northern North Island. The two limestones record a previously undocumented degree of eastern Taranaki Basin margin tectonic mobility relevant to a fuller appreciation of petroleum system development in that basin.

Hood, Steven D.; Nelson, Campbell S.

2012-03-01

276

Isotope shifts and nuclear charge radii of krypton isotopes across the N =50 shell closure  

SciTech Connect

Optical isotope shifts have been measured in the 5{ital s}(3/2){sub 2}{sup 0}--5{ital p}(3/2){sub 2} transition in atomic krypton ({lambda}=760 nm) using collinear-fast-beam laser spectroscopy. Isotope shifts were determined for the short-lived neutron-rich isotopes {sup 88}Kr and {sup 90}Kr, as well as for all the stable isotopes between {ital A}=78 and 86, thus extending the data in this element, for the first time, beyond the {ital N}=50 shell closure. The deduced changes in the nuclear charge radii show a decrease of the charge radius with increasing neutron number below {ital N}=50, and a much more rapid increase above it. A preliminary interpretation of the results is given in terms of the droplet model.

Schuessler, H.A.; Alousi, A.; Evans, R.M.; Brieger, M.; Buchinger, F.; Li, Y.F. (Department of Physics, Texas A M University, College Station, TX (USA) Foster Radiation Laboratory, McGill University, Montreal, Quebec (Canada))

1990-09-10

277

DIFFERENCES AND SIMILARITIES IN ANDRA'S ASSESSMENT OF ACTIVITIES CARRIED OUT BY RADIOACTIVE WASTE GENERATORS AND AFFECTING THE QUALITY OF IL-LL SHORT-LIVED WASTE PACKAGES AND HL-IL LONG-LIVED WASTE PACKAGES  

SciTech Connect

In both cases of packages for either low-level and intermediate-level short-lived (LL-IL/SL) or high-level and intermediate-level long-lived (HL-IL/LL) radioactive waste, Andra has defined a quality reference system, manages it, follows up its appropriate implementation in production plants and verifies its effectiveness in production. The purpose of such a reference system is to ensure, in the first case, that waste packages comply with the Centre de l'Aube's acceptance criteria and, in the second case, that the characteristics submitted by the waste generators to Andra as input data for the deep geological repository project reflect the actual production conditions. In that context, the three management steps of the quality reference system include differences due to the fact that HL-IL/SL packages have not been submitted yet to any technical acceptance criterion. Compliance with any such criterion should be the subject of a characterization report during the qualification phase and of a examination during the verification phase. The management of the quality reference system also involves similarities that facilitate the joint work carried out by Andra with the waste generators, especially in the facilities where both package types are produced.

Trentesaux, C.; Cairon, P.; Dumont, J.-N.; Felix, B.; Losada, F.

2003-02-27

278

Neutron activation analysis for Dy, Hf, Rb, Sc and Se in some Ghanaian cereals and vegetables using short-lived nuclides and Compton suppression spectrometry.  

PubMed

A pseudo-cyclic instrumental neutron activation analysis (PCINAA) method has been developed to determine selected elements in various types of cereal and vegetable from Ghana using relatively short-lived nuclides (t1/2<80 s) and the Compton suppression counting. The samples were irradiated for 10 s at the Dalhousie University SLOWPOKE-2 research reactor facility (DUSR) and allowed to decay for 20 s, and counted for 40 s. The process is repeated every 50 s for 4 cycles to quantify Dy, Hf, Rb, Sc and Se through 165mDy, 179Hf, 86mRb, 46mSc, and 77mSe. The detection limits were generally of the order of 1.0 ng g(-1) except for Rb which is about 1 microg g(-1). Both precision and accuracy of the method were found to be good. PMID:18424050

Nyarko, B J B; Akaho, E H K; Fletcher, J J; Chatt, A

2007-10-12

279

{beta}-Decay Half-Lives of Very Neutron-Rich Kr to Tc Isotopes on the Boundary of the r-Process Path: An Indication of Fast r-Matter Flow  

SciTech Connect

The {beta}-decay half-lives of 38 neutron-rich isotopes from {sub 36}Kr to {sub 43}Tc have been measured; the half-lives of {sup 100}Kr, {sup 103-105}Sr, {sup 106-108}Y, {sup 108-110}Zr, {sup 111,112}Nb, {sup 112-115}Mo, and {sup 116,117}Tc are reported here. The results when compared with previous standard models indicate an overestimation in the predicted half-lives by a factor of 2 or more in the A{approx_equal}110 region. A revised model based on the second generation gross theory of {beta} decay better predicts the measured half-lives and suggests a more rapid flow of the rapid neutron-capture process (r-matter flow) through this region than previously predicted.

Nishimura, S.; Li, Z.; Watanabe, H.; Kurata-Nishimura, M.; Baba, H.; Doornenbal, P.; Isobe, T.; Sakurai, H.; Scheit, H.; Steppenbeck, D. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yoshinaga, K. [Department of Physics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sumikama, T.; Miyashita, Y.; Chiba, J.; Nakano, T.; Sugimoto, K.; Takano, S. [Department of Physics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Tachibana, T. [4 Senior High School of Waseda University, Nerima Tokyo 177-0044 (Japan); Yamaguchi, K.; Odahara, A. [Department of Physics, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043 (Japan)

2011-02-04

280

Impact of feeding and short-term temperature stress on the content and isotopic signature of fatty acids, sterols, and alcohols in the scleractinian coral Turbinaria reniformis  

NASA Astrophysics Data System (ADS)

This study assesses the combined effect of feeding and short-term thermal stress on various physiological parameters and on the fatty acid, sterol, and alcohol composition of the scleractinian coral Turbinaria reniformis. The compound-specific carbon isotope composition of the lipids was also measured. Under control conditions (26°C), feeding with Artemia salina significantly increased the symbiont density and chlorophyll content and the growth rates of the corals. It also doubled the concentrations of almost all fatty acid (FA) compounds and increased the n-alcohol and sterol contents. ?13C results showed that the feeding enhancement of FA concentrations occurred either via a direct pathway, for one of the major polyunsaturated fatty acid (PUFA) compounds of the food (18:3n-3 FA), or via an enhancement of photosynthate transfer (indirect pathway), for the other coral FAs. Cholesterol (C27?5) was also directly acquired from the food. Thermal stress (31°C) affected corals, but differently according to their feeding status. Chlorophyll, protein content, and maximal photosynthetic efficiency of photosystem II (PSII) decreased to a greater extent in starved corals. In such corals, FA concentrations were reduced by 33%, (especially C16, C18 FAs, and n-3 PUFA) and the sterol content by 27% (especially the C28?5,22 and C28?5). The enrichment in the ?13C signature of the storage and structural FAs suggests that they were the main compounds respired during the stress to maintain the coral metabolism. Thermal stress had less effect on the lipid concentrations of fed corals, as only FA levels were reduced by 13%, with no major changes in their isotope carbon signatures. In conclusion, feeding plays an essential role in sustaining T. reniformis metabolism during the thermal stress.

Tolosa, I.; Treignier, C.; Grover, R.; Ferrier-Pagès, C.

2011-09-01

281

Application of routine estimation of Pb isotopic ratios by inductively coupled plasma mass spectrometry for studying the Pb origin in hair of children living in polluted areas. A pilot study  

Microsoft Academic Search

The analysis of 204Pb, 206Pb, 207Pb and 208Pb isotope ratios for environmental Pb markers (leaded gasoline, air-borne particulate matter, house window dust) and hair of children was undertaken by the routine quadrupole inductively coupled argon plasma mass spectrometry (Q-ICP-MS). Hair samples collected from 10-year-old children living in Krakow in 1995 and 35 randomly selected children, aged 11, both sexes were

H. Barton; Z. Zachwieja; S. D'Ilio; S. Caroli

2000-01-01

282

Heavy-ion-induced production and preseparation of short-livedisotopes for chemistry experiments  

Microsoft Academic Search

Physical separation of short-lived isotopes produced inheavy-ion-induced fusion reactions is a powerful and well know method andoften applied in investigations of the heaviest elements, called thetransactinides (Z>=104). By extracting these isotopes from a recoilseparator, they can be made available for transport to setups locatedoutside the heavily shielded irradiation position such as chemistrysetups. This physical preseparation technique overcomes many limitationscurrently faced

Christoph E. Dullmann; Charles M. Folden; Kenneth E. Gregorich; Darleane C. Hoffman; Daniela Leitner; Gregory K. Pang; Ralf Sudowe; Peter M. Zielinski; Heino Nitsche

2005-01-01

283

Precise and accurate isotope ratio measurements by ICP-MS.  

PubMed

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target. PMID:11220826

Becker, J S; Dietze, H J

2000-09-01

284

Composition and Trends of Short-Lived Trace Gases in the UT/LS over Europe Observed by the CARIBIC Aircraft  

NASA Astrophysics Data System (ADS)

The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) involves the monthly deployment of an instrument container equipped to make atmospheric measurements from aboard a commercial airliner, and has operated since 2005 from aboard a Lufthansa Airbus 340-600 . Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. Measurements made from the sampling flasks include greenhouse gas (GHG), halocarbon and nonmethane hydrocarbon (NMHC) analysis. CARIBIC flights originate in Frankfurt, Germany with routes to India, East Asia, South America, North America and Africa, and typical aircraft cruising altitudes of 10-12km allow for the monitoring of the upper troposphere/lower stratosphere (UT/LS) along these routes. Data collected during the aircraft’s departure from and return to Frankfurt provide a 4 year time series of near-monthly measurements of the composition of the UT/LS above Europe. Here we present a discussion of the composition of short-lived trace gases in the whole air samples collected above Europe during CARIBIC flights. Over 150 air samples were collected between May 2005 and July 2009, or about 4 samples per month. Of the whole air samples collected, about 45% showed influence by stratospheric air (i.e. very low values of GHG, NMHC and halocarbons, elevated O3, high potential vorticity). The remaining samples were representative of the upper troposphere; back trajectories for these samples indicate that a little over half were collected in air masses that had been in the boundary layer within the previous 8 days. The predominant source regions for these samples were the Gulf of Mexico and continental North America. Owing to their wide range of chemical lifetimes and the varying composition of emissions, short-lived trace gases transported to the UT/LS can be useful indicators of source region, photochemical processing and transport timescales of an air mass. Seasonal and longer-term trends in trace gases and trace gas composition are discussed, as well as composition of air masses having different origins. Additionally, we apply relationships between the different species, particularly the NMHC, to gain a qualitative understanding of photochemical processes occurring during transport from the boundary layer to the upper troposphere over Europe.

Baker, A. K.; Brenninkmeijer, C. A.; Oram, D. E.; O'Sullivan, D. A.; Slemr, F.; Schuck, T. J.

2009-12-01

285

/sup 195m/Au, a new generator-produced short-lived radionuclide for sequential assessment of ventricular performance by first pass radionuclide angiocardiography  

SciTech Connect

The feasibility of performing rapid sequential first pass radionuclide angiocardiography using a new short-lived radiotracer, (/sup 195/mAu) half-life 30.5 seconds) was evaluated. This radionuclide emits a 262 keV gamma ray and is the daughter of (/sup 195/mHg) (half-life 41.6 hours). The prototype tabletop /sup 195/mHg//sup 195/mAu generator produced 20 to 25 mCi of /sup 195/mAu in 2 ml of eluate (yield of 40 percent). The breakthrough of /sup 195/mHg in the eluate was 0.02 percent of the amount of /sup 195/mHg in the generator. The eluate contained 20 microCi of /sup 195/mHg per study, resulting in an estimated human radiation dose of 0.007 rad/study to the whole body and 0.34 rad/study to the kidney. Four dogs each had 15 to 20 sequential first pass studies performed with /sup 1195/mHg at 3 to 10 minute intervals using a computerized multicrystal gamma camera. During the left ventricular phase, 160,000 to 190,000 counts/s were acquired. The end-diastolic left ventricular region of interest contained 3,000 to 6,000 counts (background- and decay-corrected). Multiple reproducible values for left ventricular ejection fraction were obtained during stable conditions. The mean (+/- standard deviation) interstudy variability was 4 +/- 2 percent. During infusion of isoproterenol, rapid increase of left ventricular ejection fraction was demonstrated. Excellent agreement was observed between studies performed with /sup 99m/Tc-DTPA) and /sup 195/mAu. The mean interstudy difference was 4 +/- 3 percent. Thus, sufficiently high yield and dose are obtained from the /sup 195/mHg//sup 195/mAu generator for reliable high count rate first pass determination of left ventricular ejection fraction. This new short-lived radiotracer makes possible rapid sequential assessments of ventricular function at greatly reduced patient exposure to radiation.

Wackers, F.J.; Giles, R.W.; Hoffer, P.B.; Lange, R.C.; Berger, H.J.; Zaret, B.L.

1982-07-01

286

Mapping of quantitative trait loci controlling lifespan in the short-lived fish Nothobranchius furzeri - a new vertebrate model for age research  

PubMed Central

The African annual fish Nothobranchius furzeri emerged as a new model for age research over recent years. Nothobranchius furzeri show an exceptionally short lifespan, age-dependent cognitive/behavioral decline, expression of age-related biomarkers, and susceptibility to lifespan manipulation. In addition, laboratory strains differ largely in lifespan. Here, we set out to study the genetics of lifespan determination. We crossed a short- to a long-lived strain, recorded lifespan, and established polymorphic markers. On the basis of genotypes of 411 marker loci in 404 F2 progeny, we built a genetic map comprising 355 markers at an average spacing of 5.5 cM, 22 linkage groups (LGs) and 1965 cM. By combining marker data with lifespan values, we identified one genome-wide highly significant quantitative trait locus (QTL) on LG 9 (P < 0.01), which explained 11.3% of the F2 lifespan variance, and three suggestive QTLs on LG 11, 14, and 17. We characterized the highly significant QTL by synteny analysis, because a genome sequence of N. furzeri was not available. We located the syntenic region on medaka chromosome 5, identified candidate genes, and performed fine mapping, resulting in a c. 40% reduction of the initial 95% confidence interval. We show both that lifespan determination in N. furzeri is polygenic, and that candidate gene detection is easily feasible by cross-species analysis. Our work provides first results on the way to identify loci controlling lifespan in N. furzeri and illustrates the potential of this vertebrate species as a genetic model for age research.

Kirschner, Jeanette; Weber, David; Neuschl, Christina; Franke, Andre; Bottger, Marco; Zielke, Lea; Powalsky, Eileen; Groth, Marco; Shagin, Dmitry; Petzold, Andreas; Hartmann, Nils; Englert, Christoph; Brockmann, Gudrun A; Platzer, Matthias; Cellerino, Alessandro; Reichwald, Kathrin

2012-01-01

287

What does the oxygen isotope composition of rodent teeth record?  

NASA Astrophysics Data System (ADS)

Oxygen isotope compositions of tooth phosphate (?18Op) were measured in 107 samples defined on the basis of teeth obtained from 375 specimens of extant rodents. These rodents were sampled from pellets collected in Europe from 38°N (Portugal) to 65°N (Finland) with most samples coming from sites located in France and Spain. Large oxygen isotopic variability in ?18Op is observed both at the intra- and inter-species scale within pellets from a given location. This isotopic variability is partly explained by heterochrony in tooth formation related to the short time of mineralization for all rodent species as well as the duration of mineralization that is species-dependent. Consequently, tooth phosphate of rodents records a short seasonal interval in the oxygen isotope compositions of meteoric waters (?18Omw). In addition, inter-species isotopic variability observed in the same pellets suggests behavioural differences implying distinct isotopic compositions for species living in the same location. At the scale of Europe, a robust linear oxygen isotope fractionation equation was determined for Muroidea between the midrange ?18Op values and ?18Omw values: ?18Op=1.21(±0.20)?18Omw+24.76(±2.70) with R2=0.79 (n=9; p<0.0001).

Royer, Aurélien; Lécuyer, Christophe; Montuire, Sophie; Amiot, Romain; Legendre, Serge; Cuenca-Bescós, Gloria; Jeannet, Marcel; Martineau, François

2013-01-01

288

New Scheme for Precision Mass Measurements of Rare Isotopes Produced at RI Beam Factory  

NASA Astrophysics Data System (ADS)

For precision mass measurements of short-lived rare isotopes, a new experimental apparatus, named ``Rare-RI Ring'', has recently been proposed. A unique possibility of the project is discussed, comparing with other experimental techniques. The current status is presented.

Nakajima, S.; Yamaguchi, T.; Suzuki, T.; Yamaguchi, Y.; Fujinawa, T.; Fukunishi, N.; Goto, A.; Ohnishi, T.; Sakurai, H.; Wakasugi, M.; Yano, Y.; Arai, I.; Ozawa, A.; Yasuda, Y.; Kikuchi, T.; Ohtsubo, T.

2008-02-01

289

Isotopic fission product release from nuclear fuel under severe core damage accident conditions  

SciTech Connect

Isotopic fission gas release behavior during SFD tests 1-1, 1-3, and 1-4 is strongly dependent on the pre-test fuel history. For SFD 1-1, where the majority of all the fission products were generated during the preconditioning period, very little difference in isotopic release behavior between short- and long-lived species is predicted. For the SFD 1-3 and 1-4 tests, where the majority of all short-lived fission gases decayed away during the 4-year cooling period, differences between the behavior of long- and short-lived species are predicted. Most of the intragranular fission product release has been shown to be due to a grain-growth/grain-boundary-sweeping mechanism. In addition, fuel liquefaction/dissolution processes can lead to increased release under these degraded-core-accident conditions. These predictions follow the trend of the observed phenomena.

Rest, J.; Osetek, D.J.; Hartwell, J.K.

1985-09-01

290

Some observations on the concentrations of short-lived decay products of radon and thoron in the monsoon rains of Bombay, India  

SciTech Connect

The concentrations of radon decay products /sup 214/Pb(RaB) and /sup 214/Bi(RaC) and thoron daughter /sup 212/Pb(ThB) have been measured in rainfall at Bombay. The presence of short-lived /sup 218/Po(RaA) is indicated in a few samples. The levels of /sup 214/ Pb varied from 300 to 7000 pCi (11-260 Bq) per liter, while the activity ratios of /sup 214/Bi//sup 214/Pb are in the range of 0.5-1.5. From these values of the ratios a cloud drop lifetime, from nucleation to deposition, of 20--60 min is estimated. The concentrations of /sup 212/Pb varied from 2 to 30 pCi (0.075-1.1 Bq) per liter. The levels of radon and thoron daughter products are lower in Bombay summer rainfall compared with other areas due to their reduced concentrations in the maritime monsoon winds. Approximate estimates of scavenging ratios based on the surface air concentrations are 85 +- 65 (1 standard deviation) and 30 +- 20 (1 standard deviation) for radon and thoron daughters, respectively.

Rangarajan, C.; Eapen, C.D.

1985-08-20

291

High viral burden restricts short-lived effector cell number at late times postinfection through increased natural regulatory T cell expansion.  

PubMed

Generating and maintaining a robust CD8(+) T cell response in the face of high viral burden is vital for host survival. Further, balancing the differentiation of effectors along the memory precursor effector cell pathway versus the short-lived effector cell (SLEC) pathway may be critical in controlling the outcome of virus infection with regard to clearance and establishing protection. Although recent studies have identified several factors that have the capacity to regulate effector CD8(+) T cell differentiation-for example, inflammatory cytokines-we are far from a complete understanding of how cells choose the memory precursor effector cell versus SLEC fate following infection. In this study, we have modulated the infectious dose of the poxvirus vaccinia virus as an approach to modulate the environment present during activation and expansion of virus-specific effector cells. Surprisingly, in the face of a high virus burden, the number of SLECs was decreased. This decrease was the result of increased natural regulatory T cells (Tregs) generated by high viral burden, as depletion of these cells restored SLECs. Our data suggest Treg modulation of differentiation occurs via competition for IL-2 during the late expansion period, as opposed to the time of T cell priming. These findings support a novel model wherein modulation of the Treg response as a result of high viral burden regulates late-stage SLEC number. PMID:23589620

Amoah, Samuel; Holbrook, Beth C; Yammani, Rama D; Alexander-Miller, Martha A

2013-04-15

292

Near-infrared laser induced conformational change and UV laser photolysis of glycine in low-temperature matrices: Observation of a short-lived conformer  

NASA Astrophysics Data System (ADS)

The near-infrared spectrum (NIR) of glycine was measured in Ar and Kr matrices. Matrix-isolated glycine was irradiated with NIR laser light at the first OH or NH stretching overtone bands of the three main glycine (ttt/Ip, ccc/IIn, tct/IIIp) conformers. The main conversion paths and their efficiencies are described qualitatively, and it is shown that there are significant differences in the conversion paths in Ar and Kr. In the detailed analysis of these experiments many new, formerly unobserved low-intensity transitions of the three main conformers were identified, and in addition a short-lived (tunneling half-life is 5 ± 2 s) higher energy conformer (ttc/VIp) was observed during the irradiation at the first OH stretching overtone of ttt/Ip. The UV spectrum of glycine was also measured in Ar matrix, and the first two absorption bands of conformers ttt/Ip and ccc/IIn were identified. UV laser irradiation at longer (240 nm) wavelengths promotes rotamerization, while at shorter wavelengths (235 and 213.5 nm) it results in depletion of the different conformers with different rates. Analysis of spectra recorded after UV irradiation showed that the two main photodecomposition processes are decarboxylation and H2O loss, forming methylamine and NH2CHCO, respectively.

Bazsó, Gábor; Magyarfalvi, Gábor; Tarczay, György

2012-10-01

293

The variation of short-lived NOy species around sunrise at mid-latitudes as measured by MIPAS-B and calculated by KASIMA  

NASA Astrophysics Data System (ADS)

Vertical profiles of total reactive nitrogen (NOy = NO2 + HNO3 + ClONO2 + 2N2O5 + HO2NO2) along with the source gas N2O up to 38 km were retrieved from infrared limb emission spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding, Balloonborne version (MIPAS-B) instrument from Aire sur l'Adour (France, 42°N) on April 30, 1999. Three limb sequences of spectra were recorded 1 hour before, at and 3 hours after sunrise, respectively, allowing to investigate the NOy partitioning under night-time and - for the first time with the MIPAS-B instrument - also under day-time conditions and to study the temporal evolution of the short-lived species N2O5 and NO2 around sunrise. The MIPAS-B data are compared to calculations performed with the 3-D chemical transport model KASIMA (Karlsruhe Simulation model of the Middle Atmosphere). This comparison reveals a high degree of confidence in the model for the HNO3/NOy ratio in the whole altitude region and for the N2O5/NOy and NO2/NOy ratios above about 26 km. Below this altitude the N2O5/NOy ratio is significantly underestimated by the model. Also, the MIPAS-B measurement suggests a night-time built up of NO2 which is not reproduced by the model in an altitude region around 22 km.

Stowasser, M.; Oelhaf, H.; Ruhnke, R.; Kleinert, A.; Wetzel, G.; Friedl-Vallon, F.; Kouker, W.; Lengel, A.; Maucher, G.; Nordmeyer, H.; Reddmann, Th.; Fischer, H.

2003-04-01

294

A Discordancy Between Short-Term Sedimentation Rate Using Pb210, Cs137 and Pu and Long-Term Sedimentation Rate Using C-14  

Microsoft Academic Search

Short-lived radionuclides (210Pb, 137Cs, etc) have been successfully utilized to obtain sedimentation rates in freshwater and coastal marine environments over the past 3 decades. Combined use of 210Pb and Pu enable to delineate sedimentation from sediment mixing. However independent validation of short-term accumulation rates using other long-lived isotopes, such as 14C are very limited. We collected a sediment core from

M. Baskaran; T. R. Filley; T. S. Bianchi; K. H. Freeman; P. G. Hatcher

2005-01-01

295

Mass measurements on radioactive isotopes with a Penning trap mass spectrometer  

SciTech Connect

Penning trap mass measurements on short-lived isotopes are performed with the ISOLTRAP mass spectrometer at the radioactive beam facility ISOLDE/CERN. In the last years the applicability of the spectrometer has been considerably extended by the installation of an RFQ trap ion beam buncher and a new cooler Penning trap, which is operated as an isobar separator. These improvements allowed for the first time measurements on isotopes of rare earth elements and on isotopes with Z=80-85. In all cases an accuracy of {delta}m/m{approx_equal}1{center_dot}10{sup -7} was achieved.

Bollen, G. [CERN, Geneva (Switzerland); Ames, F.; Schark, E. [Institut fuer Physik, Universitaet Mainz (Germany); Audi, G.; Lunney, D.; Saint Simon, M. de [CSNSM-IN2P3-CNRS, Orsay (France); Beck, D.; Herfurth, F.; Kluge, H.-J.; Kohl, A.; Schwarz, S. [Gesellschaft fuer Schwerionenforschung GSI, Darmstadt (Germany); Moore, R. B. [McGill University, Montreal (Canada); Szerypo, J. [Institute of Experimental Physics, Warsaw University, Warsaw (Poland)

1999-01-15

296

Repeatability and validation of a short, semi-quantitative food frequency questionnaire designed for older adults living in Mediterranean areas: the MEDIS-FFQ.  

PubMed

The aim of the present work was to evaluate the repeatability and the validity of a short food frequency questionnaire (FFQ) that could be used for older people living in Mediterranean areas. The semi-quantitative FFQ included questions regarding the frequency of consumption of the main food groups and beverages typically consumed in the Mediterranean areas as well as some questions regarding eating habits of older persons. During 2006-2007, for the repeatability assessment (within 10-30 days), 150 individuals (51 +/- 17 yrs, 40% males) were studied, while another 190 individuals (74 +/- 9 yrs, 52% males) were enrolled for the validation purposes. Agreement of the FFQ with the 3-day food records was evaluated using the Bland-Altman method and the Kendall's tau-b coefficient. Repeatability was tested using the Cohen's kappa coefficient. Between 3-day food records and the FFQ, good agreement for alcohol (tau-b = 0.64, p < 0.001) was found, while moderate agreement for food and beverage groups of greens (tau-b = 0.32, p < 0.001), fruits (tau-b = 0.35, p < 0.001), cereals (tau-b = 0.61, p < 0.001), sweets (tau-b = 0.51, p < 0.001), and coffee (tau-b = 0.58, p < 0.001) was observed. Low, but still significant, agreement for fish (tau-b = 0.21, p = 0.001), legumes (tau-b = 0.23, p < 0.001), vegetables (tau-b = 0.23, p < 0.001), pasta (tau-b = 0.25, p < 0.001), potatoes (tau-b = 0.17, p = 0.006) and meat consumption (tau-b = 0.14, p < 0.001) were also found. The FFQ was also valid regarding the estimation of macronutrients and energy intake. Sensitivity analyses by sex, age category ( 75 yrs), and education status showed similar validity of the FFQ in each subgroup, except for elders older than 75 years. The repeatability of the FFQ was fair in all foods tested (Cohen's kappa coefficients varied between 0.15-0.39, p-values < 0.05). The suggested FFQ seems to be a reasonably valid and repeatable measure of dietary intake and can be used in older persons living in the Mediterranean areas. PMID:20711925

Tyrovolas, Stefanos; Pounis, George; Bountziouka, Vassiliki; Polychronopoulos, Evangelos; Panagiotakos, Demosthenes B

2010-07-01

297

Constraining the Time-Scale of Interaction of Sea Ice Sediments and Surface Sea Water in the Arctic Ocean Using Short-Lived Radionuclide Tracers  

NASA Astrophysics Data System (ADS)

We measured the activities of short-lived radionuclides (Th-234, Be-7, Po-210, Pb-210, Cs-137, Th-234, Ra-226 and Ra-228) and concentrations of several elements (Be, Pb, Fe, Al, Co, Ni, Cu and Zn) on a suite of ice-rafted sediments (IRS) collected during BERINGIA-2005 in the Western Arctic Ocean. A suite of water samples were also collected and analyzed for particulate and dissolved Be-7, Po-210, Pb-210, Th-234, Ra-226 and Ra-228. The activities of Be-7 and Pb-210 in the IRS are 1-2 orders of magnitude higher than those reported in the source sediments. Presence of excess Th-234 in the IRS indicates that the removal of Th-234 from surface seawater took place on time scales comparable to the mean-life of Th-234. While the Po-210/Pb-210 activity ratios in the source sediments (1.0) and the atmospheric depositional input (~0.1) are known, varying ratios of 0.78 to 1.0 were found in the IRS. This ratio can be utilized to obtain the residence time of the IRS in sea ice. The activity of Ra-226 and Ra-228 in all the IRS is nearly constant (within a factor of 1.6) and are comparable to the benthic sediments in the source region. The activities of atmospherically-delivered radionuclides, Be-7 and Pb-210, in IRS varied by factors of ~4.5 and 9, respectively, and this variation is attributed to differences in the extent of interaction of surface water with IRS and differences in the mean-lives of these nuclides. While significant enrichment of Be-7 and Pb-210 has been found, there is no enrichment of stable Pb or Be. The Al-normalized enrichment factor for elements measured (Co, Ni, Cu, Zn, Pb and Be) indicate that there is no significant enrichment of these elements, with Al-normalized enrichment factors less than 1.3.

Baskaran, M.; Andersson, P. S.; Jweda, J.; Dahlqvist, R.; Ketterer, M. E.

2007-12-01

298

The distribution of short-lived radioisotopes in the early solar system and the chronology of asteroid accretion, differentiation, and secondary mineralization  

Microsoft Academic Search

We evaluate initial (26Al\\/27Al)I, (53Mn\\/55Mn)I, and (182Hf\\/180Hf)I ratios, together with 207Pb\\/206Pb ages for igneous differentiated meteorites and chondrules from ordinary chondrites for consistency with radioactive decay of the parent nuclides within a common, closed isotopic system, i.e., the early solar nebula. The relative initial isotopic abundances of 26Al, 53Mn, and 182Hf in differentiated meteorites and chondrules are consistent with decay

L. E. Nyquist; T. Kleine; C.-Y. Shih; Y. D. Reese

2009-01-01

299

More evidence for very short-lived substance contribution to stratospheric chlorine inferred from HCl balloon-borne in situ measurements in the tropics  

NASA Astrophysics Data System (ADS)

Volume mixing ratio (vmr) vertical profiles of hydrogen chloride (HCl) are retrieved from in situ measurements performed by a balloon-borne infrared tunable diode laser absorption spectrometer (SPIRALE) during two balloon flights in the tropics (Teresina, Brazil, 5.1° S-42.9° W) in June 2005 and June 2008. HCl vertical profiles obtained from 15 to 31 km are presented and analysed to estimate the contribution of very short-lived substances (VSLS) to total stratospheric chlorine. Both retrieved vertical profiles of HCl from these flights agree very well with each other, with estimated overall uncertainties of 6% on vmr between 23 and 31 km. Upper limits of HCl vmr as low as 20 pptv in June 2008 and 30 pptv in June 2005 are inferred in the upper part of the tropical tropopause layer (TTL). Backward trajectory calculations and such low amounts suggest that the air masses sampled correspond to typical background conditions, i.e. neither influenced by recent tropospheric nor stratospheric air. Taking into account the recently reported VSL source gas measurements obtained in similar conditions (Laube et al., 2008) and the main intermediate degradation product gas COCl2 (Fu et al., 2007), a total VSLS contribution of 85±40 pptv to stratospheric chlorine is inferred. This refines the WMO (2007) estimation of 50 to 100 pptv, which was not taking into account any HCl contribution. In addition, comparisons of HCl measurements between SPIRALE and the Aura MLS satellite instrument in the tropical lower and middle stratosphere lead to a very good agreement. The previous agreement between MLS-deduced upper stratospheric total chlorine content and modelled values including 100 pptv of VSLS (Froidevaux et al., 2006) is thus supported by our present result about the VSLS contribution.

Mébarki, Y.; Catoire, V.; Huret, N.; Berthet, G.; Robert, C.; Poulet, G.

2010-01-01

300

More evidence for very short-lived substance contribution to stratospheric chlorine inferred from HCl balloon-borne in situ measurements in the tropics  

NASA Astrophysics Data System (ADS)

Volume mixing ratio (vmr) vertical profiles of hydrogen chloride (HCl) are retrieved from in situ measurements performed by a balloon-borne infrared tunable diode laser absorption spectrometer (SPIRALE) during two balloon flights in the tropics (Teresina, Brazil, 5.1° S-42.9° W) at three year interval in June 2005 and June 2008. HCl vertical profiles obtained from 15.0 to 31.0 km are presented and analysed to estimate the contribution of very short-lived substances (VSLS) to total stratospheric chlorine. Both retrieved vertical profiles of HCl from these flights globally agree very well with each other, with estimated overall uncertainties of 6% on vmr between 23 and 31 km. Upper limits of HCl vmr as low as (20±20) pptv in June 2008 and (30±30) pptv in June 2005 are inferred in the upper part of the tropical tropopause layer (TTL). Backward trajectory calculations suggest that these low amounts were sampled in air masses corresponding to typical background conditions, i.e. neither influenced by recent tropospheric nor stratospheric air. Taking into account the recently reported VSLS source gas measurements obtained in similar conditions (Laube et al., 2008) and the main intermediate product gas (COCl2), a VSLS contribution of about (85±35 pptv) to total stratospheric chlorine is inferred. This refines the WMO (2007) estimation of 50 to 100 pptv, which was not taking into account any HCl contribution. In addition, comparisons of HCl measurements between SPIRALE and MLS-Aura satellite instrument in the tropical lower and middle stratosphere lead to a very good agreement. Since HCl modelled values derived from a total stratospheric chlorine budget including 100 pptv of VSLS agree with MLS measurements in the upper stratosphere, the consistency between SPIRALE and MLS measurements provides another evidence for this VSLS contribution.

Mébarki, Y.; Catoire, V.; Berthet, G.; Huret, N.; Robert, C.

2009-07-01

301

Voltammetric investigation of DNA damage induced by nitrofurazone and short-lived nitro-radicals with the use of an electrochemical DNA biosensor.  

PubMed

Electrochemical behavior of nitrofurazone (NFZ) was investigated with the use of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The pH-dependence of NFZ was studied at a glassy carbon electrode (GCE) in ethanol/Britton-Robinson buffer (30:70), and short-lived nitro-radicals were generated by the reduction of NFZ at high pHs (>7.0). In the presence of DNA, the DPV peak current of NFZ decreased and the peak potential shifted negatively, which indicated that there was an electrostatic interaction between NFZ and DNA. An electrochemical dsDNA/GCE biosensor was prepared to study the DNA damage produced in the presence NFZ; this process was followed with the use of the Co(phen)(3)(2+) electroactive probe. Also, the oxidation peaks of guanosine (750 mV) and adenosine (980 mV) indicated that DNA damage was related directly to the nitro-radicals. Experiments demonstrated that DNA damage occurred via two different steps while NFZ was metabolized and nitro-radicals were produced. Novel work with AFM on the NFZ/DNA interaction supported the suggestion that in vivo, the nitro-radicals were more cytotoxic than the NFZ molecules. A linear DPV calibration plot was obtained for NFZ analysis at a modified dsDNA/GCE (concentration range: 2.50 × 10(-6)-3.75 × 10(-5) mol L(-1); limit of detection: 8.0 × 10(-7) mol L(-1)), and NFZ was determined successfully in pharmaceutical samples. PMID:22717476

Ni, Yongnian; Wang, Pingping; Kokot, Serge

2012-06-06

302

Concentrated fish oil (Lovaza(R)) extends lifespan and attenuates kidney disease in lupus-prone short-lived (NZBxNZW)F1 mice.  

PubMed

A growing number of reports indicate that anti-inflammatory actions of fish oil (FO) are beneficial against systemic lupus erythematosus (SLE). However, the majority of pre-clinical studies were performed using 5-20% FO, which is higher than the clinically relevant dose for lupus patients. The present study was performed in order to determine the effective low dose of FDA-approved concentrated FO (Lovaza®) compared to the commonly used FO-18/12 (18-Eicosapentaenoic acid [EPA]/12-Docosahexaenoic acid [DHA]). We examined the dose-dependent response of Lovaza® (1% and 4%) on an SLE mouse strain (NZBxNZW)F1 and compared the same with 1% and 4% placebo, as well as 4% FO-18/12, maintaining standard chow as the control. Results show for the first time that 1% Lovaza® extends maximal lifespan (517?d) and 4% Lovaza® significantly extends both the median (502?d) and maximal (600?d) life span of (NZBxNZW)F1 mice. In contrast, FO-18/12 extends only median lifespan (410?d) compared to standard chow diet (301?d). Additionally, 4% Lovaza® significantly decreased anti-dsDNA antibodies, reduced glomerulonephritis and attenuated lipopolysaccharide-induced pro-inflammatory cytokines (IL-1?, IL-6, TNF-?) in splenocytes compared to placebo. 4% Lovaza® was also shown to reduce the expression of inflammatory cytokines, including IL-1?, IL-6 and TNF-?, while increasing renal anti-oxidant enzymes in comparison to placebo. Notably, NF?B activation and p65 nuclear translocation were lowered by 4% Lovaza® compared to placebo. These data indicate that 1% Lovaza® is beneficial, but 4% Lovaza® is more effective in suppressing glomerulonephritis and extending life span of SLE-prone short-lived mice, possibly via reducing inflammation signaling and modulating oxidative stress. PMID:23918873

Halade, Ganesh V; Williams, Paul J; Veigas, Jyothi M; Barnes, Jeffrey L; Fernandes, Gabriel

2013-06-01

303

Living in living cities.  

PubMed

Abstract This article presents an overview of current and potential applications of living technology to some urban problems. Living technology can be described as technology that exhibits the core features of living systems. These features can be useful to solve dynamic problems. In particular, urban problems concerning mobility, logistics, telecommunications, governance, safety, sustainability, and society and culture are presented, and solutions involving living technology are reviewed. A methodology for developing living technology is mentioned, and supraoptimal public transportation systems are used as a case study to illustrate the benefits of urban living technology. Finally, the usefulness of describing cities as living systems is discussed. PMID:23834590

Gershenson, Carlos

2013-07-08

304

Evidence For Three, Short Lived, Geomagnetic Field Excursions Recorded In Postglacial (9-15,000 YBP) Carbonates Of The Tahitian Coral Reef  

NASA Astrophysics Data System (ADS)

A detailed composite record of inclinations and relative paleointensity for Late Quaternary (8-16,000 YBP) coral-reef framework rocks recovered from the island of Tahiti during IODP Expedition 310 yielded reproducible evidence for three, short-lived magnetic field excursions at 10,700±200 YBP, 12,900±200 YBP, and 14,200±200 YBP. Age estimates for these excursions, which are constrained by more than 250 radiocarbon dates from the same cores, make them younger than any other published well-documented and dated excursion from the continents or the continental margins. Samples for paleomagnetic analysis were recovered mainly from the abundant microbialites deposited in the interstices of the macro-coral framework. These carbonate rocks make up more than 60% of the Tahiti Coral Reef and 95% of all magnetic samples. Initial paleomagnetic and rock magnetic studies showed that the microbialites carry a strong and stable natural magnetic remanence with an average value of -30.6° (?95=2.9°) that is not significantly different from Tahiti's expected axial-dipole inclination. Rock magnetic studies indicate that the NRM is carried almost entirely by detrital titanomagnetite grains (<1 ?m to ~20 ?m in grain size) that were derived from the Tahiti volcanic edifice, but the grains were locked-in by biological mediation during biogenic carbonate precipitation. To assess the spatial coherence of the paleomagnetic directions, paleointensities, and the rock magnetic variability of these young excursions, detailed re-sampling of all available material with a clear up-down direction, extending from one normal polarity interval through the recorded excursion to the following normal interval (±1m), was undertaken. In total we obtained inclination and relative paleointensity estimates (based on CHI, ARM, and SIRM) from more then 750 samples. General results of this analysis show that these young magnetic excursions are real and reproducible and often associated with paleointensity lows. NRM demagnetization reveals consistent changes in both inclination and occasionally, where we have intervals with sequential samples from unbroken core segments, declination. The duration of these young excursional events is constrained by the bulk framework rock accumulation rate (5-10 m/ky; 100-200 yrs/m) to timescales of 100's of years. These intriguing new observations have profound implications and may change our ideas about the number and frequency of magnetic excursions.

Platzman, E. S.; Lund, S.; Camoin, G.; Thouveny, N.; Scientific Team IODP Expedition 310

2011-12-01

305

Living Non-Living  

NSDL National Science Digital Library

Fill out your worksheet as you learn more about living and non-living things. 1. First take this pretest to test your knowledge of living and non living things.Beginning Quiz 2. So, you know what is alive and what is not. But why are those things alive or not? Read the information on this site to learn the 7 characteristics that make things ...

Benson, Mrs.

2010-02-23

306

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets  

NASA Astrophysics Data System (ADS)

Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite ( ?D-E), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO 2 performed on six individuals following a diet-switch showed that 70-90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M 1) and second (M 2) lower molars of four lambs as well as on the third lower molar (M 3) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M 1, and 4 months in M 2 and M 3. Portions of enamel in equilibrium with dietary carbon were used to calculate ?D-E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth enamel represent underdetermined systems, our results demonstrate that they can provide useful information about dietary variability if the mineralization process is taken into account.

Zazzo, A.; Balasse, M.; Passey, B. H.; Moloney, A. P.; Monahan, F. J.; Schmidt, O.

2010-06-01

307

Effects of complex carbon addition to soil CO2 efflux and isotopic composition to soils near dead and live piñon pine trees  

NASA Astrophysics Data System (ADS)

We test the hypothesis that soils collected near dead and living pinus edulous (piñon pine) trees should show a difference in their capacities to decompose complex carbon compounds. Since soils near dead trees have a large amount of cellulose and other complex carbon, the soil microbial community should be selected to metabolize cellulose. We collected soils from both live and dead piñon trees, added cellulose to half of the replicates, and placed them in microcosms for incubation. The microcosms were periodically sampled by a trace gas analyzer (TGA100, Campbell Scientific, USA) for CO2 concentration and ?13C and ?18O analysis. We found that CO2 evolution rates from live soils were significantly higher than rates from dead soils (1.1 and 0.6 ug CO2 g-1 soil s-1 respectively); soils with added cellulose displayed higher rates (1.1 and 0.8 and ug CO2 g-1 soil s-1). We did not see any significant differences in ?13C values between treatments, but there was a difference in ?18O between soils treated with cellulose and soils with no cellulose. Soils from both dead and live trees showed an increase in CO2 efflux when cellulose was added; however there was no distinguishable difference in efflux rate between live and dead soils in the cellulose added treatments.

Powers, H.; McDowell, N.; Breecker, D. O.

2010-12-01

308

Determining coastal mixing rates using radium isotopes  

NASA Astrophysics Data System (ADS)

Coastal waters contain elevated dissolved activities of four radium isotopes. These elevated activities arise through desorption of Ra from particle surfaces and the input of submarine groundwaters enriched in Ra. The input of Ra near the coast is balanced by a flux of each Ra isotope toward the open ocean. Two of the Ra isotopes decay almost completely before they reach the edge of the continental shelf; the other two decay hardly at all. These differences in decay rates provide a powerful constraint on models of water movement and mixing on the shelf. These models are used to assess the factors that control the export of radium. Understanding the factors that control the export of radium allows an assessment of physical processes that regulate fluxes of other dissolved constituents in the coastal ocean. In this paper I use observations that were made during vertically stratified conditions in the South Atlantic Bight. Offshore transects of the long-lived 226Ra and 228Ra indicate that eddy diffusion controls their distributions within 50 km of shore. The short-lived 223Ra and 224Ra distributions in this region yield an eddy diffusion coefficient of 360-420 m 2 s -1. The offshore fluxes of 226Ra and 228Ra derived from their across-shelf activity gradients and the eddy diffusion coefficient require a substantial volume of groundwater discharge to balance Ra removal.

Moore, Willard S.

2000-11-01

309

Oxygen Isotope Composition of Stratospheric Carbon Dioxide  

NASA Astrophysics Data System (ADS)

In the stratosphere, carbon dioxide gradually obtains an anomalous oxygen isotope enrichment, which generally increases with altitude. This enrichment has been related to transfer of anomalously fractionated oxygen from ozone to CO2 via a short-lived CO3* complex, which CO2 forms with O(1D) produced in the photolysis of ozone, al- though the precise transfer mechanism is still being debated. We present CO2 and O3 isotope measurements from 8 stratospheric balloon flights at two latitudes that provide now a complete oxygen isotope analysis of both gases. The results show an unambigu- ous, very tight correlation between 17O and 18O in CO2, which passes through the tropospheric values at the tropopause. The large ratio 17O/18O of 1.7 shows a faster transfer of 17 O than of 18 O into CO2 and establishes a standard throughout the lower and middle stratosphere. Ozone isotope transfer can now be treated in models with re- liable atmospheric data. Additional laboratory exchange experiments are being carried out to investigate the oxygen transfer process in detail.

Röckmann, T.; Brenninkmeijer, C. A. M.; Assonov, S. S.; Lämmerzahl, P.; Krankowsky, D.; Mauersberger, K.

310

Mass spectrometry of long-lived radionuclides  

Microsoft Academic Search

The capability of determining element concentrations at the trace and ultratrace level and isotope ratios is a main feature of inorganic mass spectrometry. The precise and accurate determination of isotope ratios of long-lived natural and artificial radionuclides is required, e.g. for their environmental monitoring and health control, for studying radionuclide migration, for age dating, for determining isotope ratios of radiogenic

Johanna Sabine Becker

2003-01-01

311

Short-term changes in carbon-isotope discrimination in the C 3 CAM intermediate Clusia minor L. growing in Trinidad  

Microsoft Academic Search

On-line instantaneous carbon isotope discrimination was measured in conjunction with net uptake of CO2 in leaves of exposed and shaded plants of the C3-CAM intermediate Clusia minor growing under natural conditions in Trinidad. At the end of the rainy season (late January-early February, 1992) C3 photosynthesis predominated although exposed leaves recaptured a small proportion of respiratory CO2 at night for

A. M. Borland; H. Griffiths; M. S. J. Broadmeadow; M. C. Fordham; C. Maxwell

1993-01-01

312

The Effectiveness of Healthy Physical Fitness Programs on People with Intellectual Disabilities Living in a Disability Institution: Six-Month Short-Term Effect  

ERIC Educational Resources Information Center

|Little information is available on the provision of physical fitness and intervention program among people with intellectual disabilities. The aim of this study is to provide information of examining the effectiveness of healthy physical fitness programs on people with intellectual disabilities living in a disability institution. There were 146…

Wu, Chia-Ling; Lin, Jin-Ding; Hu, Jung; Yen, Chia-Feng; Yen, Cheng-Tung; Chou, Yu-Lan; Wu, Po-Hsun

2010-01-01

313

High tandem repeat content in the genome of the short-lived annual fish Nothobranchius furzeri: a new vertebrate model for aging research  

Microsoft Academic Search

BACKGROUND: The annual fish Nothobranchius furzeri is the vertebrate with the shortest known life span in captivity. Fish of the GRZ strain live only three to four months under optimal laboratory conditions, show explosive growth, early sexual maturation and age-dependent physiological and behavioral decline, and express aging related biomarkers. Treatment with resveratrol and low temperature significantly extends the maximum life

Kathrin Reichwald; Chris Lauber; Indrajit Nanda; Jeanette Kirschner; Nils Hartmann; Susanne Schories; Ulrike Gausmann; Stefan Taudien; Markus B Schilhabel; Karol Szafranski; Gernot Glöckner; Michael Schmid; Alessandro Cellerino; Manfred Schartl; Christoph Englert; Matthias Platzer

2009-01-01

314

Manganese and chromium isotopes: Nebular processes and early solar system chronology  

NASA Astrophysics Data System (ADS)

Stable isotopes and short-lived radionuclides are useful for examining nucleosynthetic origins of solar system material, studying mixing processes in the early solar nebula and dating nebular events and secondary processes. Chromium isotopes offer an excellent tool for these studies as chromium has four stable isotopes ( 50 Cr, 52 Cr, 53 Cr and 54 Cr) of which one ( 53 Cr) is the daughter of the short-lived radionuclide 53 Mn (half-life of 3.7 Ma). Chromium isotopes can therefore be used both to examine mixing efficiencies in the early solar nebula using the stable isotope 54 Cr and to date secondary events (such as aqueous alteration in carbonaceous chondrites) using radiogenic 53 Cr. Isotopic anomalies of several neutron-rich nuclides observed in chondrites bear evidence of incomplete mixing in the early solar system. High-precision thermal ionization mass spectrometry (TIMS) can be used to determine 54 Cr isotopic anomalies in the epsilon (parts per 10 4 ) range. Chromium isotopic analyses were performed using bulk samples of carbonaceous chondrites, ordinary chondrites and enstatite chondrites. In this study I report systematic deficits in ordinary chondrites (-0.66 to -1.80 [varepsilon] 54 Cr), excesses in carbonaceous chondrites (+0.29 to +1.66 [varepsilon] 54 Cr) and isotopic compositions in enstatite chondrites that overlap with terrestrial values. These observed differences in [varepsilon] 54 Cr between different chondrite groups suggest that three or more Cr carriers were present in presolar matter and that the solar nebula that produced planetesimals between ~1 and ~3 AU was not isotopically uniform. Radiogenic 53 Cr can be used to date alteration products in carbonaceous chondrites. CM chondrite materials have been modified by several post- accretionary processes. These chondrites contain carbonates and other secondary minerals that are believed to have formed by alteration reactions on the CM parent body. The timescales for the formation of secondary minerals can be quantified using the radioactive decay of 53 Mn to 53 Cr. Here I report measurements of excess 53 Cr in carbonates from the highly aqueously altered CM2.1 chondrites QUE 93005 and ALH 83100. These excesses are correlated with the 53 Mn/ 55 Mn ratio and result from the in situ decay of 53 Mn, a short- lived radioisotope with a half-life of 3.7 Ma. Results from CM chondrites imply that the degree of aqueous alteration is roughly correlated with the age of carbonate formation in CM chondrites of different subtypes and that alteration started contemporaneously or shortly after CAI formation and lasted at least 4 Ma on the CM parent body.

de Leuw, Simone

315

Advantages of Short-Lived Positron-Emitting Radioisotopes for Intracoronary Radiation Therapy with Liquid-Filled Balloons to Prevent Restenosis  

Microsoft Academic Search

Balloon catheters filled with liquid radioisotopes provide excellent dose homogeneity for intracoronary radiation therapy but are as- sociated with risk for rupture or leakage. We hypothesized that the safety of liquid-filled balloons may be improved once positron emitters with half-lives below 2 h are used instead of the high- energy b-emitters 166Ho, 186Re, or 188Re, all of which have a

Hans-Peter Stoll; Gary D. Hutchins; Wendy L. Winkle; Anne T. Nguyen; C. Robert Appledorn; Ingrid Janzen; Hermann Seifert; Christian Rube; Hermann Schieffer; Keith L. March

316

Groundtruthing the CSIA-aerosol technique for estimation of carbon isotopic discrimination of terrestrial photosynthesis  

NASA Astrophysics Data System (ADS)

The carbon isotopic composition of vascular plant-derived leaf wax compounds present in aerosols can potentially provide a highly temporally resolved estimate of terrestrial photosynthetic fractionation of carbon dioxide on ecosystem and larger spatial scales. A central assumption of this approach is that the isotopic signal of the leaf waxes ablated off living vegetation by wind and dust scouring and accumulating in the atmosphere can be linked quantitatively to carbon isotopic fractionation by plant photosynthesis. To test this assumption we conducted a "groundtruthing" study in an Alberta short-grass prairie to assess the constancy of isotopic fractionation between leaf wax compounds and bulk carbon in major C3 and C4 plant species and also the linkage between waxes in bulked biomass and in aerosols collected at the site. We found that the isotopic fractionation factor for leaf waxes in these prairie plants does not vary significantly either among species or during the growing season, and also that the isotopic signal of ablated waxes in the aerosols is consistent with that in the local vegetation. Our results provide additional support for the validity of this novel biomarker-aerosol based approach and also new data needed to constrain the isotopic fractionation factor used to convert the plant wax signal in aerosols to an estimate of carbon isotopic discrimination of terrestrial photosynthesis.

Conte, M. H.; Weber, J. C.; Flanagan, L. P.

2001-05-01

317

ACTIVE MEDIA: Photoinduced short-lived absorption in YSGG:Cr3+:Nd3+ and GSAG:Cr3+:Nd3+ crystals  

Microsoft Academic Search

An investigation was made of the influence of short-wavelength pump radiation on the spectral and luminescence characteristics of GSGG:Cr3+:Nd3+ and GSAG:Cr3+:Nd3+ crystals. A sensitive system was developed for measurement of the induced absorption based on multipass probing of a crystal by laser radiation. Dependences of the induced absorption on the excitation energy and the lifetimes of the photoinduced color centers

M. Kh Ashurov; S. P. Nasel'skii; I. R. Rustamov; Valerii A. Smirnov; A. F. Umyskov; Ivan A. Shcherbakov

1991-01-01

318

Nebular and asteroidal modification of the iron isotope composition of chondritic components  

Microsoft Academic Search

The Fe-isotope signatures (?56FeIRMM and ?57FeIRMM) of twelve chondrules, three Ca-, Al-rich inclusions (CAIs) and multiple matrix aliquots from two type 3 chondrites — Allende (CV3) and Chainpur (LL3) were measured by MC-ICP-MS. The mass-fractionation line for these samples is ?57FeIRMM=(1.45±0.05)·?56FeIRMM?(0.01±0.02) with R2=0.9995. Two processes appear to affect the Fe-isotope composition of these chondritic components. Initially, short-lived high-temperature events within

E. Mullane; S. S. Russell; M. Gounelle

2005-01-01

319

High-accuracy mass measurements of neutron-rich Kr isotopes  

SciTech Connect

The atomic masses of the neutron-rich krypton isotopes {sup 84,86-95}Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes {sup 94}Kr and {sup 95}Kr were measured for the first time. The masses of the radioactive nuclides {sup 89}Kr and {sup 91}Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

Delahaye, P.; Kellerbauer, A. [ISOLDE, CERN, Physics Department, CH-1211 Geneva 23 (Switzerland); Audi, G.; Lunney, D. [CSNSM-CNRS-IN2P3, F-91405 Orsay (France); Blaum, K.; George, S. [Johannes Gutenberg-Universitaet, Institut fuer Physik, D-55099 Mainz (Germany); Gesellschaft fuer Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Carrel, F.; Herfurth, F.; Yazidjian, C. [Gesellschaft fuer Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Herlert, A.; Schweikhard, L. [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, D-17487 Greifswald (Germany); Kluge, H.-J. [Gesellschaft fuer Schwerionenforschung GSI, D-64291 Darmstadt (Germany); Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, D-69120 Heidelberg (Germany)

2006-09-15

320

Heavy-ion-induced production and preseparation of short-livedisotopes for chemistry experiments  

SciTech Connect

Physical separation of short-lived isotopes produced inheavy-ion-induced fusion reactions is a powerful and well know method andoften applied in investigations of the heaviest elements, called thetransactinides (Z>=104). By extracting these isotopes from a recoilseparator, they can be made available for transport to setups locatedoutside the heavily shielded irradiation position such as chemistrysetups. This physical preseparation technique overcomes many limitationscurrently faced in the chemical investigation of transactinides. Here wedescribe the basic principle using relatively short-lived isotopes of thelighter group 4 elements zirconium (Zr) and hafnium (Hf) that are used asanalogs of the lightest transactinide element, rutherfordium (Rf, element104). The Zr and Hf isotopes were produced at the LBNL 88-Inch Cyclotronusing a cocktail of 18O and 50Ti beams and the appropriate targets.Subsequently, the isotopes were physically separated in the BerkeleyGas-filled Separator (BGS) and guided to a Recoil Transfer Chamber (RTC)to transfer them to chemistry setups. The magnetic rigidities of thereaction products in low-pressure helium gas were measured and theiridentities determined with gamma-pectroscopy. Using preseparated isotopeshas the advantages of low background and beam plasma free environment forchemistry experiments. The new possibilities that open up for chemicalinvestigations of transactinide elements are descr ibed. The method canreadily be applied to homologous elements within other groups in theperiodic table.

Dullmann, Christoph E.; Folden III, Charles M.; Gregorich, Kenneth E.; Hoffman, Darleane C.; Leitner, Daniela; Pang, Gregory K.; Sudowe, Ralf; Zielinski, Peter M.; Nitsche, Heino

2005-02-24

321

Assisted Living  

MedlinePLUS

... Bar Home Current Issue Past Issues Feature: Senior Living Assisted Living Past Issues / Summer 2009 Table of Contents For ... t need round-the-clock nursing care. Assisted living facilities provide an alternative. Assisted living is for ...

322

Assisted Living  

MedlinePLUS

... Text Printer Friendly Download Reader Online Chat Assisted Living Assisted living facilities offer a housing alternative for ... to top What is the Cost for Assisted Living? Although assisted living costs less than nursing home ...

323

Living Donation  

MedlinePLUS

... Living Donation Costs Insurance Legislation Living Donation Living organ donation dates back to 1954, when a kidney from ... a deceased donor. To learn more about living organ donation, choose an option below: Facts Types Being a ...

324

Correlated helium-3 and tungsten isotopes in iron meteorites: Quantitative cosmogenic corrections and planetesimal formation times  

Microsoft Academic Search

Core formation in planetesimals can, in principle, be dated using the short-lived 182Hf–182W chronometer. However, it has been predicted that burnout and production of W isotopes by nuclear reactions can substantially modify the compositions in iron meteorites when exposed for several hundred million years (Myr) to galactic cosmic-rays. This may severely limit the use of the Hf–W system for determining

A. Markowski; I. Leya; G. Quitté; K. Ammon; A. N. Halliday; R. Wieler

2006-01-01

325

Neutron Activation Cross Section of Molybdenum Isotopes at 14.8 MeV  

Microsoft Academic Search

The neutron activation cross sections of Mo isotopes have been measured for the 14.8 MeV neutron. The cross sections have been determined with reference to the known A1 (n, ?)Na and the Al(n, p)Mg reactions. The cyclic activation method was employed for the ?-ray measurement of short-lived nuclei. A 55 cm Ge(Li) detector was used for the measurement of ?-ray

Susumu AMEMIYA; Kei-ichi ISHIBASHI; Toshio KATOH

1982-01-01

326

Radium isotope quartet in groundwater as a proxy for identification of aquifer rocks and mechanisms of water-rock interactions: examples from the Negev, Israel  

NASA Astrophysics Data System (ADS)

Many aquifer systems are composed of multiple rock types. Previous attempts to evaluate the specific aquifer rocks that control the groundwater chemistry and possible flow paths within these multiple lithological systems have used major ion chemistry and isotopic tracers (e.g., strontium isotopes). Here we propose an additional isotopic proxy that is based on the distribution of radium isotopes in groundwater. Radium has four radioactive isotopes that are part of the decay chains of uranium-238, thorium-232, and uranium-235. The abundance of radium isotope quartet (226Ra-half life 1600 y; 228Ra-5.6 y; 224Ra-3.6 d; 223Ra-11.4 d) in groundwater reflects the Th/U ratios in the rocks. Investigation of groundwater from the Negev, Israel, enabled us to discriminate between groundwaters flowing in the Lower Cretaceous Nubian Sandstone and the Upper Cretaceous Judea Group carbonate aquifers. Groundwater flowing in the sandstone aquifer has distinguishably high 228Ra/226Ra and 224Ra/223Ra ratios due to the high Th/U ratio in sandstone. In contrast, the predominance of uranium in carbonate rocks results in low 228Ra/226Ra and 224Ra/223Ra ratios in the associated groundwater. We show that the radium activity in groundwater in the two-aquifer systems is correlated with temperature, dissolved oxygen, and salinity. The increase of radium activity is also associated with changes in the isotopic ratios; 228Ra/226Ra ratios increase and decrease in the sandstone and carbonate aquifers, respectively. Given that the dissolution of radium isotopes depends on their decay constants, the use of the four radium isotopes with different decay constants enabled us to distinguish between dissolution (higher abundance of the long-lived isotopes) and recoil (predominance of the short-lived isotopes) processes. In spite of these isotopic fractionations, the radium isotopic discrimination between carbonate and sandstone aquifers is significant.

Vengosh, A.; Pery, N.; Paytan, A.; Haquin, G.; Elhanani, S.; Pankratov, I.

2006-05-01

327

Short-term outcome in living donors for lung transplantation: the role of preoperative computer tomographic evaluations of fissures and vascular anatomy.  

PubMed

Successful living-donor lobar lung transplantation (LDLLT) largely depends on donor outcome. We reviewed our experiences with LDLLT and focused on preoperative computed tomographic evaluations of donors. Twenty-five LDLLTs were performed in Kyoto University. As a routine preoperative assessment, high-resolution chest computed tomography (CT), and three-dimensional (3D)-CT angiography were performed. Preoperative evaluations, surgical procedures, and early postoperative outcomes were reviewed in 43 consecutive LDLLT donors. All donors were discharged home after the donor lobectomies. Severely incomplete fissures were intraoperatively identified in two donors, whose interlobar fissures were mostly not identified by high resolution CT preoperatively. Preoperative 3D-CT angiography was effective for the identification of the branches of the pulmonary artery and vein. Pulmonary arterioplasties were performed with auto pericardial patches in three left donors. The bilateral donors had to be exchanged because of an anomaly of the pulmonary veins in one donor. Small pulmonary arterial branches to the remaining lobes were to be sacrificed in 23 donors (53%). Early postoperative complications were ascertained in seven donors, and five of them presented air leak-related complications. Living donor lobectomies were safely performed with low morbidities in our institution. Preoperative computer tomographic evaluations might be useful in donor lobectomies. PMID:22364276

Chen, Fengshi; Fujinaga, Takuji; Shoji, Tsuyoshi; Kubo, Takeshi; Sonobe, Makoto; Sato, Masaaki; Aoyama, Akihiro; Sato, Toshihiko; Sakai, Hiroaki; Bando, Toru; Date, Hiroshi

2012-02-24

328

PLANETARY-SCALE STRONTIUM ISOTOPIC HETEROGENEITY AND THE AGE OF VOLATILE DEPLETION OF EARLY SOLAR SYSTEM MATERIALS  

SciTech Connect

Isotopic anomalies in planetary materials reflect both early solar nebular heterogeneity inherited from presolar stellar sources and processes that generated non-mass-dependent isotopic fractionations. The characterization of isotopic variations in heavy elements among early solar system materials yields important insight into the stellar environment and formation of the solar system, and about initial isotopic ratios relevant to long-term chronological applications. One such heavy element, strontium, is a central element in the geosciences due to wide application of the long-lived {sup 87}Rb-{sup 87}Sr radioactive as a chronometer. We show that the stable isotopes of Sr were heterogeneously distributed at both the mineral scale and the planetary scale in the early solar system, and also that the Sr isotopic heterogeneities correlate with mass-independent oxygen isotope variations, with only CI chondrites plotting outside of this correlation. The correlation implies that most solar system material formed by mixing of at least two isotopically distinct components: a CV-chondrite-like component and an O-chondrite-like component, and possibly a distinct CI-chondrite-like component. The heterogeneous distribution of Sr isotopes may indicate that variations in initial {sup 87}Sr/{sup 86}Sr of early solar system materials reflect isotopic heterogeneity instead of having chronological significance, as interpreted previously. For example, given the differences in {sup 84}Sr/{sup 86}Sr between calcium aluminum inclusions and eucrites ({epsilon}{sup 84}Sr > 2), the difference in age between these materials would be {approx}6 Ma shorter than previously interpreted, placing the Sr chronology in agreement with other long- and short-lived isotope systems, such as U-Pb and Mn-Cr.

Moynier, Frederic; Podosek, Frank A. [Department of Earth and Planetary Science and McDonnell Center for Space Sciences, Washington University, St. Louis, MO 63130 (United States); Day, James M. D. [Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244 (United States); Okui, Wataru; Yokoyama, Tetsuya [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Bouvier, Audrey [Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455-0231 (United States); Walker, Richard J., E-mail: moynier@levee.wustl.edu, E-mail: fap@levee.wustl.edu, E-mail: jmdday@ucsd.edu, E-mail: rjwalker@umd.edu, E-mail: okui.w.aa@m.titech.ac.jp, E-mail: tetsuya.yoko@geo.titech.ac.jp, E-mail: abouvier@umn.edu [Department of Geology, University of Maryland, College Park, MD 20742 (United States)

2012-10-10

329

Isotopic distributions.  

PubMed

Isotopic information determined by mass spectrometry can be used in a wide variety of applications. Broadly speaking these could be classified as "passive" applications, meaning that they use naturally occurring isotopic information, and "active" applications, meaning that the isotopic distributions are manipulated in some way. The classic passive application is the determination of chemical composition by comparing observed isotopic patterns of molecules to theoretically calculated isotopic patterns. Active applications include isotope exchange experiments of a variety of types, as well as isotope labeling in tracing studies and to provide references for quantitation. Regardless of the type of application considered, the problem of theoretical calculation of isotopic patterns almost invariably arises. This paper reviews a number of application examples and computational approaches for isotopic studies in mass spectrometry. PMID:23666722

Rockwood, Alan L; Palmblad, Magnus

2013-01-01

330

DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE  

SciTech Connect

Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-{pi}BaF{sub 2} scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

Couture, A.; Bond, E.; Bredeweg, T. A.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Agvaanluvsan, U.; Becker, J. A. [Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, CA, 94551 (United States); Baker, J. D. [Idaho National Laboratory, PO Box 1625, Idaho Falls, ID 83415 (United States); Bayarbadrahk, B.; Chyzh, A.; Dashdorj, D. [North Carolina State University, Department of Physics, Raleigh, NC 27695 (United States); Reifarth, R. [Gesellschaft fuer Schwerionenforschung (GSI), Plankstrasse 1, 64291 Darmstadt (Germany)

2009-03-10

331

Spent fuel temperature and age determination from the analysis of uranium and plutonium isotopics  

SciTech Connect

The capability to determine the age (time since irradiation) of spent fuel can be useful for verification and safeguards. While the age of spent fuel can be determined based on measurements of short-lived fission products, these measurements are not routinely done nor generally reported. As an alternative, age can also be determined if the uranium (U) and plutonium (Pu) isotopic values are available. Uranium isotopics are not strongly affected by fuel temperature, and bumup is determined from the {sup 235}U and {sup 236}U isotopic values. Age is calculated after estimating the {sup 241}Pu at the end of irradiation while accounting for the fuel temperature, which is determined from {sup 239}Pu or {sup 240}Pu. Burnup and age determinations are calibrated to reactor models that provide uranium and plutonium isotopics over the range of fuel irradiation. The reactor model must contain sufficient fidelity on details of the reactor type, fuel burnup, irradiation history, initial fuel enrichment and fuel temperature to obtain accurate isotopic calculations. If the latter four are unknown, they can be derived from the uranium and plutonium isotopics. Fuel temperature has a significant affect on the production of plutonium isotopics; therefore, one group cross section reactor models, such as ORIGEN, cannot be used for these calculations. Multi-group cross section set codes, such as Oak Ridge National Laboratory's TRITON code, must be used.

Scott, Mark R [Los Alamos National Laboratory; Eccleston, George W [Los Alamos National Laboratory; Bedell, Jeffrey J [Los Alamos National Laboratory; Lockard, Chanelle M [Los Alamos National Laboratory

2009-01-01

332

DANCEing with the Stars: Measuring Neutron Capture on Unstable Isotopes with DANCE  

NASA Astrophysics Data System (ADS)

Isotopes heavier than iron are known to be produced in stars through neutron capture processes. Two major processes, the slow (s) and rapid (r) processes are each responsible for 50% of the abundances of the heavy isotopes. The neutron capture cross sections of the isotopes on the s process path reveal information about the expected abundances of the elements as well as stellar conditions and dynamics. Until recently, measurements on unstable isotopes, which are most important for determining stellar temperatures and reaction flow, have not been experimentally feasible. The Detector for Advance Neutron Capture Experiments (DANCE) located at the Los Alamos Neutron Science Center (LANSCE) was designed to perform time-of-flight neutron capture measurements on unstable isotopes for nuclear astrophysics, stockpile stewardship, and reactor development. DANCE is a 4-? BaF2 scintillator array which can perform measurements on sub-milligram samples of isotopes with half-lives as short as a few hundred days. These cross sections are critical for advancing our understanding of the production of the heavy isotopes.

Couture, A.; Agvaanluvsan, U.; Baker, J. D.; Bayarbadrahk, B.; Becker, J. A.; Bond, E.; Bredeweg, T. A.; Chyzh, A.; Dashdorj, D.; Fowler, M.; Haight, R. C.; Jandel, M.; Keksis, A. L.; O'Donnell, J. M.; Reifarth, R.; Rundberg, R.; Ullmann, J. L.; Vieira, D. J.; Wouters, J. M.

2009-03-01

333

Soluble CD4 and CD4-Mimetic Compounds Inhibit HIV-1 Infection by Induction of a Short-Lived Activated State  

PubMed Central

Binding to the CD4 receptor induces conformational changes in the human immunodeficiency virus (HIV-1) gp120 exterior envelope glycoprotein. These changes allow gp120 to bind the coreceptor, either CCR5 or CXCR4, and prime the gp41 transmembrane envelope glycoprotein to mediate virus–cell membrane fusion and virus entry. Soluble forms of CD4 (sCD4) and small-molecule CD4 mimics (here exemplified by JRC-II-191) also induce these conformational changes in the HIV-1 envelope glycoproteins, but typically inhibit HIV-1 entry into CD4-expressing cells. To investigate the mechanism of inhibition, we monitored at high temporal resolution inhibitor-induced changes in the conformation and functional competence of the HIV-1 envelope glycoproteins that immediately follow engagement of the soluble CD4 mimics. Both sCD4 and JRC-II-191 efficiently activated the envelope glycoproteins to mediate infection of cells lacking CD4, in a manner dependent on coreceptor affinity and density. This activated state, however, was transient and was followed by spontaneous and apparently irreversible changes of conformation and by loss of functional competence. The longevity of the activated intermediate depended on temperature and the particular HIV-1 strain, but was indistinguishable for sCD4 and JRC-II-191; by contrast, the activated intermediate induced by cell-surface CD4 was relatively long-lived. The inactivating effects of these activation-based inhibitors predominantly affected cell-free virus, whereas virus that was prebound to the target cell surface was mainly activated, infecting the cells even at high concentrations of the CD4 analogue. These results demonstrate the ability of soluble CD4 mimics to inactivate HIV-1 by prematurely triggering active but transient intermediate states of the envelope glycoproteins. This novel strategy for inhibition may be generally applicable to high–potential-energy viral entry machines that are normally activated by receptor binding.

Haim, Hillel; Si, Zhihai; Madani, Navid; Wang, Liping; Courter, Joel R.; Princiotto, Amy; Kassa, Aemro; DeGrace, Marciella; McGee-Estrada, Kathleen; Mefford, Megan; Gabuzda, Dana; Smith, Amos B.; Sodroski, Joseph

2009-01-01

334

Direct Mass Measurements of Short-Lived A=2Z-1 Nuclides {sup 63}Ge, {sup 65}As, {sup 67}Se, and {sup 71}Kr and Their Impact on Nucleosynthesis in the rp Process  

SciTech Connect

Mass excesses of short-lived A=2Z-1 nuclei {sup 63}Ge, {sup 65}As, {sup 67}Se, and {sup 71}Kr have been directly measured to be -46 921(37), -46 937(85), -46 580(67), and -46 320(141) keV, respectively. The deduced proton separation energy of -90(85) keV for {sup 65}As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of {sup 65}As suggest that the majority of the reaction flow passes through {sup 64}Ge via proton capture, indicating that {sup 64}Ge is not a significant rp-process waiting point.

Tu, X. L.; Du, C. M.; Geng, P.; Jin, S. L.; Liu, L. X.; Tang, S. W.; Wang, S. T.; Xu, X.; Yan, X. L.; Ye, R. P.; Zang, Y. D. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)] [Graduate University of Chinese Academy of Sciences, Beijing, 100049 (China); Xu, H. S.; Wang, M.; Zhang, Y. H.; Zhou, X. H.; Yuan, Y. J.; Xia, J. W.; Hu, Z. G.; Huang, W. X.; Liu, Y. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2011-03-18

335

WRF/Chem study of dry and wet deposition of trifluoroacetic acid produced from the atmospheric degradation of a few short-lived HFCs  

NASA Astrophysics Data System (ADS)

HFC-134a (1,1,1,2-tetrafluoroethane) is the prevalent (used in >80% passenger cars and commercial vehicles worldwide) refrigerant in automobile air conditioning units (MACs). With an atmospheric lifetime of ~14 years and a global warming potential (GWP) of 1430 on a 100-year time horizon, HFC-134a does not meet current and expected requirements for MAC refrigerants in many parts of the world. Therefore, substitutes with lower GWP are being sought. One of the simplest way to achieve lower GWP is to use chemicals with shorter atmospheric lifetimes. In this work, we investigate the dry and wet deposition and the rainwater concentration of trifluoroacetic acid (TFA) produced by the atmospheric oxidation of 2,3,3,3-tetrafluoropropene (TFP) and 1,2,3,3,3-pentafluoropropene (PFP). The WRF/Chem model was used to calculate dry and wet TFA deposition over the contiguous USA during the May-September 2006 period that would result from replacing HFC-134a in MACs with a 1:1 molar ratio mixture of 2,3,3,3-tetrafluoropropene (TFP) and 1,2,3,3,3-pentafluoropropene (PFP). The simulation is evaluated by comparing observations of precipitation and sulfate wet deposition at stations of the National Atmospheric Deposition Program (NADP). Simulated precipitation and sulfate wet deposition correlate well with the observations, but exhibit a positive bias for precipitation and a negative bias for sulfate wet deposition. Atmospheric lifetimes of TFP and PFP against oxidation by the hydroxyl radical OH, a prognostic species in WRF/Chem, are ~5 and ~4 days in the simulation, respectively. The model setup allows the attribution of dry and wet TFA deposition to individual source regions (California, Houston, Chicago, and the remaining contiguous USA in this work). TFA deposition is highest in the eastern USA because of numerous large sources and high precipitation in the region. West of the Continental Divide, TFA deposition is significantly lower, and its origin is dominated by emissions from California. Dry deposition of TFA contributes on average with 26% to the total. Rainwater concentrations of TFA, averaged over the five-month simulation period remain at all locations below a threshold of 0.1 mg L-1; this value is considered safe for the aquatic ecosystem. On shorter timescales, TFA rainwater concentrations can reach significantly higher values at locations with very low rainfall rates and comparably low overall TFA deposition, mainly in California and Nevada. While the TFA rainwater concentrations expected from a replacement of HFC-134a with the shorter-lived TFP and PFP appear environmentally safe at most locations, the role of high TFA rainwater concentrations at locations with very low rainfall rates, and washdown of dry deposited TFA require future investigation.

Kazil, J.; McKeen, S. A.; Kim, S.; Ahmadov, R.; Grell, G. A.; Talukdar, R. K.; Ravishankara, A. R.

2011-12-01

336

Probing Isotope Effects in Chemical Reactions Using Single Ions  

SciTech Connect

Isotope effects in reactions between Mg{sup +} in the 3p {sup 2}P{sub 3/2} excited state and molecular hydrogen at thermal energies are studied through single reaction events. From only {approx}250 reactions with HD, the branching ratio between formation of MgD{sup +} and MgH{sup +} is found to be larger than 5. From an additional 65 reactions with H{sub 2} and D{sub 2} we find that the overall fragmentation probability of the intermediate MgH{sub 2}{sup +}, MgHD{sup +}, or MgD{sub 2}{sup +} complexes is the same. Our study shows that few single ion reactions can provide quantitative information on ion-neutral reactions. Hence, the method is well suited for reaction studies involving rare species, e.g., rare isotopes or short-lived unstable elements.

Staanum, Peter F.; Hoejbjerre, Klaus; Drewsen, Michael [QUANTOP - Danish National Research Foundation Centre for Quantum Optics, University of Aarhus, 8000 Aarhus (Denmark); Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus (Denmark); Wester, Roland [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg (Germany)

2008-06-20

337

Production of Cs and Fr isotopes from a high-density UC targets with different grain dimensions  

NASA Astrophysics Data System (ADS)

A UC target material of 11.3±0.5 g/cm^3 uranium density with the grain size of 20 and 5?m manufactured in a form of pills by the method of powder metallurgy has been tested on-line within the temperature range of 1800-2100 ° C . The mass of uranium exposed to the beam was 4-7g. The yields and release rates of Cs and Fr isotopes produced by fission and spallation reactions of 238U by 1GeV protons have been measured. The yields of Cs and Fr isotopes obtained from the tested target materials have been compared, including yields of very short-lived Fr isotopes with half-lives down to 1ms. Temperature-resistant materials (porous graphite and tantalum foil) have been used for the internal-container construction, which holds the UC target pills inside a tungsten external container heated by the resistant heating. The fastest release and the highest efficiency for short-lived isotopes have been obtained for the targets with the internal container manufactured from the tantalum foil. Results of on-line tests of a big mass target (730g of 5?m grain UC target material) have been discussed.

Panteleev, V. N.; Alyakrinskiy, O.; Barbui, M.; Barzakh, A. E.; Fedorov, D. V.; Ivanov, V. S.; Lhersonneau, G.; Mezilev, K. A.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Stroe, L.; Tecchio, L. B.; Tonezzer, M.; Volkov, Yu. M.

2009-12-01

338

Living Well  

MedlinePLUS

... are here: Parkinson's Disease > Living Well Text Size Living Well While living with PD can be challenging there is hope. Hope in the fact, that there ... healthy diet How to navigate daily activities of living like grooming and sleeping. Ways to make your ...

339

Characteristics of Living Things  

NSDL National Science Digital Library

Welcome to an internet program that is all about life. Just what is life? This seems like a strange question. We all know what is meant by the word \\"life\\". But how do we define it? Are all living things alike? In this internet program, you will watch several short movies and some slides. After you see each movie and slide, you will write something about the movie and slide. Our learning goal is to make a list of the traits that all living things have in common. Get out a pencil and a piece of paper. We are off on a great adventure to learn about living things! This first movie is called, \\"Is It Alive?\\" It will help you begin thinking about living things and what they all have in common. Write on your paper: \\"Living Things\\". As you watch this movie, write the names of the things that you think are alive. Copy the ...

Melenson, Richard S.

2005-11-21

340

Precision Penning trap mass measurements of rare isotopes produced by projectile fragmentation  

NASA Astrophysics Data System (ADS)

The low-energy beam and ion trap facility LEBIT at NSCL/MSU is at present the only facility where precision experiments are performed with stopped rare isotope beams produced by fast-beam fragmentation. LEBIT combines high-pressure-gas stopping with advanced ion manipulation techniques to provide brilliant low-energy beams. So far these beams have mainly been used for mass measurements on short-lived rare isotopes with a 9.4T Penning trap mass spectrometer. Recent examples include 70 m Br , located at the proton dripline, 32Si and the iron isotopes 63-65Fe . While the measurement of 32Si helps to solve a long-standing dispute over the validity of the isobaric multiplet mass equation (IMME) for the A = 32 , T = 2 multiplet, the mass measurements of 65 m,g Fe marked the first time a nuclear isomeric state has been discovered by Penning trap mass spectrometry.

Schwarz, S.; Block, M.; Bollen, G.; Campbell, C. M.; Facina, M.; Ferrer, R.; Folden, C. M., III; Kwiatkowski, A. A.; Morrissey, D. J.; Pang, G. K.; Prinke, A. M.; Ringle, R. J.; Savory, J.; Schury, P. H.

2009-12-01

341

Living Vs. Non-Living  

NSDL National Science Digital Library

Fill out your worksheet as you learn more about living and non-living things. 1. First mouse over the objects to see some of the characteristics of living and non living things.Living Nonliving Characteristics 2. So, you know what is alive and what is not. But why are those things alive or not? Read the information on this site to learn the 7 characteristics that make things ...

Benson, Carrie

2012-10-08

342

'Ceratocystis fagacearum' in Living and Dead Texas Live Oaks.  

National Technical Information Service (NTIS)

Ceratocystis fagacearum colonized Texas live oaks (Quercus virginia var. fusiformis) to a depth of 10 annual increments in sapwood, either before or shortly after initial symptom expression. The fungus survived in dead wood up to 12 months after oak wilt ...

R. Lewis

1987-01-01

343

Ehksperimental'noe issledovanie izomernykh sostoyanij nechetno-chetnykh yader (sup 155)(sub 69)Tm, (sup 157)(sub 71)Lu i vozbuzhdennykh sostoyanij nechetnykh izotopov (sup 147,153)(sub 64)Gd. (Experimental research of isomer states of even-odd nuclei Tm(sup 155), Lu(sup 157) and of excited states of odd isotopes Gd(sup 147,153)).  

National Technical Information Service (NTIS)

A complex of physical installations developed for spectroscopic investigations of short-lived isotopes and working on the line of the proton beam of the JINR phasotron is briefly described. The alpha-decay of (sup 155)Tm was investigated. Two components o...

Y. Sajdimov

1993-01-01

344

Charge radii of neon isotopes across the sd neutron shell  

SciTech Connect

We report on the changes in mean square charge radii of unstable neon nuclei relative to the stable {sup 20}Ne, based on the measurement of optical isotope shifts. The studies were carried out using collinear laser spectroscopy on a fast beam of neutral neon atoms. High sensitivity on short-lived isotopes was achieved thanks to nonoptical detection based on optical pumping and state-selective collisional ionization, which was complemented by an accurate determination of the beam kinetic energy. The new results provide information on the structural changes in the sequence of neon isotopes all across the neutron sd shell, ranging from the proton drip line nucleus and halo candidate {sup 17}Ne up to the neutron-rich {sup 28}Ne in the vicinity of the ''island of inversion.'' Within this range the charge radius is smallest for {sup 24}Ne with N=14 corresponding to the closure of the neutron d{sub 5/2} shell, while it increases toward both neutron shell closures, N=8 and N=20. The general trend of the charge radii correlates well with the deformation effects which are known to be large for several neon isotopes. In the neutron-deficient isotopes, structural changes arise from the onset of proton-halo formation for {sup 17}Ne, shell closure in {sup 18}Ne, and clustering effects in {sup 20,21}Ne. On the neutron-rich side the transition to the island of inversion plays an important role, with the radii in the upper part of the sd shell confirming the weakening of the N=20 magic number. The results add new information to the radii systematics of light nuclei where data are scarce because of the small contribution of nuclear-size effects to the isotope shifts which are dominated by the finite-mass effect.

Marinova, K. [Institut fuer Physik, Universitaet Mainz, D-55099 Mainz (Germany); Laboratory of Nuclear Reactions, Joint Institute of Nuclear Research, 141980 Dubna (Russian Federation); Geithner, W.; Kappertz, S.; Kloos, S.; Kotrotsios, G.; Neugart, R.; Wilbert, S. [Institut fuer Physik, Universitaet Mainz, D-55099 Mainz (Germany); Kowalska, M.; Keim, M. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Blaum, K. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Lievens, P. [Laboratorium voor Vaste-Stoffysica en Magnetisme, K.U.Leuven, B-3001 Leuven (Belgium); Simon, H. [Institut fuer Kernphysik, TU Darmstadt, D-64289 Darmstadt (Germany)

2011-09-15

345

Assisted Living  

MedlinePLUS

... but they don't need full-time nursing care. Some assisted living facilities are part of retirement ... change. Assisted living costs less than nursing home care. It is still fairly expensive. Older people or ...

346

Lively Science  

NSDL National Science Digital Library

Maintaining living things in a classroom requires knowledge and preparation. It also requires the proper equipment and space. There are two primary goals in the study of living things: first, we want our students to respect life, and second, we want them to appreciate its complexity in nature. Observing healthy living things in school accomplishes both goals. This chapter describes the appropriate precautions that should be taken into consideration when bringing living organisms into classrooms.

Texley, Juliana; Kwan, Terry

2002-01-01

347

Isotopes in Medicine  

NASA Astrophysics Data System (ADS)

In this paper the different techniques of radionuclide application in medicine will be outlined in some details. The corresponding chemical requirements such as radionuclide purity, pharmaceutical requirements, carrier influence and others will be underlined. An overview will be given on the different production modes of radionuclides based on reactors, small or medium cyclotrons, high-energy particle accelerators and short outlook on future aspects of medical isotope application will be given.

Beyer, Gerd-J.

348

consumer: effect of diet isotopic ratio  

Microsoft Academic Search

Summary 1. Naturally occurring stable isotopes in resources and their consumer allow the estimation of nutritional flows between the two and have been much used to improve our understanding of the nutritional ecology of free-living animals. 2. The difference in isotopic composition between an animal and its diet is represented by a discrimination factor. Carbon and nitrogen flows are estimated

Stéphane Caut; Elena Angulo; Franck Courchamp

349

Chinese disability independent living policy  

Microsoft Academic Search

Despite strong statements on disability rights in Chinese legislation since 1990, independent living policy as experienced by disabled people falls short of the social inclusion goals expected from such a policy commitment. Analysis of empirical research about disabled people's experiences shows that responsibility for independent living rests primarily with disabled people and their families. Only when they have no family

Karen Fisher; Li Jing

2008-01-01

350

Active living for assisted living  

Microsoft Academic Search

In response to a growing need for assistance among our aging population, assisted-living facilities have been designed to fill the widening chasm between community living and nursing care. Although sedentary behavior has been linked to functional limitations and disability, no comprehensive information exists about the social and physical environments and the programming available to promote physical activity in assisted living.

Shannon L Mihalko; Katie L Wickley

2003-01-01

351

Cryogenics for the Rare Isotope Accelerator project  

SciTech Connect

With 600 meters of superconducting accelerator, the Rare Isotope Accelerator (RIA) facility will have an extensive cryogenic system operating at both 2.0 K and 4.4 K. Approximately 250 4.4 K resonators, 200 2.0 K resonators, 160 4.4 K magnets, and several 4.4 K bunchers will be used in a 1.4-GV superconducting CW driver linac. Ion beams ranging from protons (up to 900 MeV) to uranium (up to 400 MeV per nucleon) at beam powers up to 400 kW will be produced. The facility will also have a superconducting linac to accelerate short-lived rare isotopes produced by the driver. This post accelerator is composed of another 100 superconducting resonators and associated superconducting focusing magnets. Liquid helium will also be provided to a variety of experimental instruments including, for example, large superconducting magnetic spectrographs. Overall, the liquid helium refrigerator will need to provide approximately 8.6 kW of cooling at 2.0 K, 4.8 kW at 4.4 K, and 15.3 kW at 35 K for shield cooling. A review of the various loads, cryostats, distribution system, and refrigeration schemes will be presented along with some special needs for reliable operation.

J. R. Specht; W. C. Chronis

2002-05-10

352

IRON-60 HETEROGENEITY AND INCOMPLETE ISOTOPE MIXING IN THE EARLY SOLAR SYSTEM  

SciTech Connect

Short-lived radionuclides (e.g., {sup 26}Al, {sup 53}Mn, {sup 60}Fe, {sup 182}Hf) are widely used to refine the chronology of the early solar system. They provide chronological information, however, only if they were homogeneously distributed in the source region of the objects under scrutiny at the time of their formation. With the high level of precision now achieved on isotopic measurements, very short time intervals can in principle be resolved and a precise evaluation of the initial homogeneity degree becomes increasingly crucial. High-precision nickel isotope data for differentiated meteorites (angrites, ureilites) and chondritic (CB) components allow us to test the initial distribution of radioactive {sup 60}Fe and stable Ni isotopes. Although these meteorites appear to have formed nearly contemporaneously, they yield variable initial {sup 60}Fe/{sup 56}Fe ratios. Besides, the CB metal nodules and ureilite silicates show nucleosynthetic anomalies. The new data presented here do not confirm the recently inferred late injection of {sup 60}Fe into the protoplanetary disk. Instead, live {sup 60}Fe was present, but heterogeneously distributed, from the start of the solar system, revealing an incomplete mixing of material from various nucleosynthetic sources and restricting the use of the {sup 60}Fe-{sup 60}Ni system as a chronometer.

Quitte, Ghylaine [Universite de Lyon (France); Markowski, Agnes [ETH Zurich, Institute for Isotope Geology and Mineral Resources, Clausiusstrasse 25, CH-8092 Zurich (Switzerland); Latkoczy, Christopher [ETH Zurich, D-CHAB, Laboratory of Inorganic Chemistry, Wolfgang-Pauli Strasse 10, CH-8093 Zurich (Switzerland); Gabriel, Aron; Pack, Andreas, E-mail: Ghylaine.Quitte@ens-lyon.f [Geowissenschaftliches Zentrum, Universitaet Goettingen, Goldschmidtstrasse 1, D-37077 Goettingen (Germany)

2010-09-10

353

Fluxes of uranium and thorium series isotopes in the Santa Barbara Basin  

NASA Astrophysics Data System (ADS)

Samples from the MANOP Santa Barbara Basin sediment trap intercomparison were analyzed for the isotopes of uranium, thorium, radium, lead, and polonium. All of the traps showed approximately the same compositions and isotopic ratios, indicating that they trapped similar materials. The 234Th flux via falling particles was very close to the flux predicted from the production and scavenging rates of 234Th from the water column. The 210Pb content of the trapped particles and the surface sediments were the same, however, the measured flux of 210Pb was seven times greater than the predicted flux. Predicted and measured fluxes of 228Th and 210Po were similarly out of balance. To explain this apparent inconsistency, we suggest (as others have done) that the Santa Barbara Basin is an area where scavenging from the water column is intensified and where sediments deposited initially on the margins may be physically remobilized on a short time scale. These two effects increase the apparent area from which the basin derives the longer-lived isotopes but does not increase significantly the supply of the short-lived 234Th.

Moore, Willard S.; Bruland, Kenneth W.; Michel, Jacqueline

1981-05-01

354

Manganese chromium isotope systematics of carbonaceous chondrites  

NASA Astrophysics Data System (ADS)

In this article we present the results of Cr isotope investigations of different types of carbonaceous chondrites and of the pallasite Eagle Station. The 53Cr/ 52Cr ratios in the bulk samples of carbonaceous chondrites are correlated with 55Mn/ 52Cr ratios. The slope of the correlation line yields a 53Mn/ 55Mn ratio of (8.5 ± 1.5) × 10 - 6 at the time of Mn/Cr fractionation. Mapping this ratio onto an absolute time scale yields a time for this event of 4568.1 + 0.8/- 1.1 Ma ago. This time is very similar to the formation age of Efremovka CAIs of 4567.2 ± 0.6 Ma [Y. Amelin, A. N. Krot, I. D. Hutcheon, A. A. Ulyanov, Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions, Science 297 (2002) 1678-1683], to a time of the chondrule formation of 4568 ± 1 Ma ago [L.E. Nyquist, D. Lindstrom, D. Mittlefehldt, C.-Y. Shih, H. Wiesmann, S. Wentworth, R. Martinez, Manganese-chromium formation intervals for chondrules from the Bishunpur and Chainpur meteorites, Meteorit. Planet. Sci. 36 (2001) 911-938], which, most likely, constrains early global high-temperature Mn/Cr fractionation in a nebular setting. The bulk samples of carbonaceous chondrites exhibit clear 54Cr excesses ( 54Cr *) that are correlated with the 53Cr excesses ( 53Cr *) and also with Mn/Cr ratios. One possible explanation of this correlation is that 54Cr * is also radiogenic, like 53Cr *, and was formed by the decay of the short-lived parent radionuclide 54Mn. The very short half-life of 54Mn of 312 days would require that both short-lived radionuclides 53Mn and 54Mn were generated locally in spallation reactions during the early period of an active sun. The alternative and possibly more plausible explanation is the heterogeneous addition of presolar material. The presolar component, enriched in 54Cr, is mostly contained in the matrix of carbonaceous chondrites. The relative amount of matrix decreases in the sequence CI > CM > CO,CV. A large proportion of Mn is associated with the matrix while Cr preferentially resides in the chondrules. Thus, the Mn/Cr ratio also follows the sequence CI > CM > CO > CV and is correlated with 54Cr. The acid-resistant residues of carbonaceous chondrites are characterized by relatively large excesses of 54Cr and moderate deficits of 53Cr. The magnitude of these excesses and deficits decreases in the sequence CI, CM, CV and may imply that Cr in the CM, and CV residues is increasingly more equilibrated with Cr from the rest of the meteorites. The 53Cr/ 52Cr and 54Cr/ 52Cr ratios in the residues are anti-correlated indicating that there are at least two Cr components of possibly presolar origin. All residues have large excesses of the most neutron-rich Ti isotope, 50Ti *. The pattern of 50Ti * does not exactly follow that observed for 54Cr * but it is generally similar. The Cr isotope systematic of the pallasite Eagle Station indicates that the precursor of this meteorite was a CV-type material. The 53Mn- 53Cr system indicates that the Cr isotopes equilibrated in this meteorite 4557.5 ± 0.6 Ma ago.

Shukolyukov, A.; Lugmair, G. W.

2006-10-01

355

Search for unknown isotopes using the JAERI-ISOL  

Microsoft Academic Search

A search for unknown neutron-rich rare-earth isotopes and neutron-deficient americium isotopes was carried out using a gas-jet coupled thermal ion source installed in the JAERI on-line isotope separator (JAERI-ISOL). New isotopes 166Tb and 165Gd produced in the proton-induced fission of 238U were identified. The half-lives were 21 ± 6 s for 166Tb and 10.3 ± 1.6 s for 165Gd. Pu

S. Ichikawa; K. Tsukada; M. Asai; A. Osa; Y. Oura; H. Iimura; Y. Kojima; T. Hirose; I. Nishinaka; Y. Hatsukawa; Y. Nagame; K. Kawade; T. Ohyama; K. Sueki

1997-01-01

356

Independent Living  

ERIC Educational Resources Information Center

A program designed to teach daily living skills to high school students of varying abilities is described. Teaching methods emphasize resource person, field trips, and actual experience; objectives are set in the areas of business, home economics, and social studies to enable students to live responsibly after high school. (AJ)

Atwood, Glenna

1974-01-01

357

Family Living and Personal Living  

NSDL National Science Digital Library

Find links for various projects for Family Living and Personal Living classes. FAMILY LIVING Wayne County Clerk - Marriage License *Travel Planning Sites* Northwest Airlines Amtrak Travelocity Spirit Air Orbitz PERSONAL LIVING (and Parenting): *Alcohol Research* Alcohol and Public Health - CDC MedlinePlus: Alcoholism NIAAA National Institute on Alcohol Abuse and Alcoholism *Birth Control* Health and Wellness Resource Center - - start at this site by typing Birth Control in the search bar on the right of the screen and select "full text articles" and consumer heatlh. It will list a range of birth ...

Schultz, Ms.

2007-11-05

358

Isotopic Analysis of Nitrate in South Pole Snow and Air  

NASA Astrophysics Data System (ADS)

Nitrate is a major component of polar snow as a result of atmospheric deposition. In the atmosphere, OH and O3 control nitrate formation. Therefore, observations of nitrate in polar snow could provide clues to long-term changes in the global oxidation capacity by revealing changes in the short-lived species controlling its formation. While the interpretation of nitrate in snow has proven elusive due to effects from post-depositional processes, the presence of mass independent oxygen isotopic composition in nitrate may provide a means to elucidate the role of oxidants and post-depositional processes. Isotopic analysis of nitrate from a 6 meter snow pit at South Pole suggest the role of post-depositional processing and is compared to instrumental records of surface ozone, total column ozone and surface UV irradiance. Surface nitrate concentrations reached up to 422 ppb while the isotopic values also saw a dramatic rise in the top 10 cm to 33 ‰ that was 8 ‰ higher than the average isotopic composition at depth (25. 7 ‰). This result implicates the role of photochemistry, which has been shown to reduce ? 17O -NO3 upon photolysis (McCabe et al. 2005). Below the surface, ? 17O -NO3 exhibits a three-year cycle that has no clear explanation at this time. When considered along with fluctuations in UV and total column ozone, there is no direct correlation. A yearlong record of nitrate aerosol and surface snow will also be measured to investigate if the isotopic composition of atmospheric nitrate is reflected in the snowpack.

McCabe, J. R.; Savarino, J.; Thiemens, M. H.

2005-12-01

359

Is it living or non living?  

NSDL National Science Digital Library

Once completed, students will have a deeper understanding of what is living and non living. Students will be able to identify the characteristics of non living and living things and will be able to classify them in an environment. Take this pretest to test your knowlege of living and non living things.Beginning Quiz Read this to learn more about living and non living things.Living vs Non Living Things Living things need 7 characteristics of life. Click on this link to learn more about what they are.7 Characteristics of Living Things Living and non living things have different characteristics. Look ...

Aitken, Miss

2009-04-17

360

Orca Live  

NSDL National Science Digital Library

The brainchild of orca biologist Dr. Paul Spong, this Nature Network Web site aims to "relay live sound and images of the orcas in the natural environment of Hanson Island," near Vancouver Island, Canada. Live sound and image feeds are available at 56K and 300K connections, and, by completing a simple registration, visitors will be alerted via email whenever orcas are near the cameras and mikes. Click on Highlights 2000 to see and hear past Web casts of orcas activity. This Web site links to others that relay live images and sounds from animals located around the world.

361

Isotope effects suggest a stepwise mechanism for berberine bridge enzyme.  

PubMed

The flavoprotein Berberine Bridge Enzyme (BBE) catalyzes the regioselective oxidative cyclization of (S)-reticuline to (S)-scoulerine in an alkaloid biosynthetic pathway. A series of solvent and substrate deuterium kinetic isotope effect studies were conducted to discriminate between a concerted mechanism, in which deprotonation of the substrate phenol occurs before or during the transfer of a hydride from the substrate to the flavin cofactor and substrate cyclization, and a stepwise mechanism, in which hydride transfer results in the formation of a methylene iminium ion intermediate that is subsequently cyclized. The substrate deuterium isotope effect of 3.5 on k(red), the rate constant for flavin reduction, is pH-independent, indicating that C-H bond cleavage is rate-limiting during flavin reduction. Solvent isotope effects on k(red) are equal to 1 for both wild-type BBE and the E417Q mutant, indicating that solvent exchangeable protons are not in flight during or before flavin reduction, thus eliminating a fully concerted mechanism as a possibility for catalysis by BBE. An intermediate was not detected by rapid chemical quench or continuous-flow mass spectrometry experiments, indicating that it must be short-lived. PMID:22931234

Gaweska, Helena M; Roberts, Kenneth M; Fitzpatrick, Paul F

2012-09-06

362

Nickel isotopic anomalies in troilite from iron meteorites  

NASA Astrophysics Data System (ADS)

We measured nickel isotopes, via multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), in troilite (FeS) from ten iron meteorites from both non-magmatic (IAB) and magmatic (IIAB, IIIAB, IVA) groups. These are the first reported measurements of 64Ni (the least abundant Ni isotope) in meteoritic sulfides. No excesses of 60Ni from the decay of the short-lived radionuclide 60Fe (t1/2 = 1.49 My) were found in any of the samples. Resolvable deficits in 60Ni were observed in five samples. These deficits are inconsistent with the effects from 60Fe decay, given the Fe/Ni ratios in these troilites. Also, variations were found in 61Ni and 64Ni in several samples. The variations in Ni isotopic compositions of these samples may be due to the preservation of a component within the troilite that is characterized by the nucleosynthetic signature expected for Ni produced either by a type II supernova or by an AGB star.

Cook, David L.; Clayton, Robert N.; Wadhwa, Meenakshi; Janney, Philip E.; Davis, Andrew M.

2008-01-01

363

Isotope effects suggest a stepwise mechanism for Berberine Bridge Enzyme†  

PubMed Central

The flavoprotein Berberine Bridge Enzyme (BBE) catalyzes the regioselective oxidative cyclization of (S)-reticuline to (S)-scoulerine in an alkaloid biosynthetic pathway. A series of solvent and substrate deuterium kinetic isotope effect studies were conducted in order to discriminate between a concerted mechanism in which deprotonation of the substrate phenol occurs before or during hydride transfer from the substrate to the flavin cofactor and substrate cyclization, and a stepwise mechanism, in which hydride transfer results in the formation of a methylene iminium ion intermediate that is subsequently cyclized. The substrate deuterium isotope effect of 3.5 on kred, the rate constant for flavin reduction, is pH-independent, indicating that C-H bond cleavage is rate-limiting during flavin reduction. Solvent isotope effects on kred are one for both wild-type BBE and the E417Q mutant, indicating that solvent exchangeable protons are not in flight during or before flavin reduction, thus eliminating a fully concerted mechanism as a possibility for catalysis by BBE. An intermediate was not detected by rapid chemical quench or continuous-flow mass spectrometry experiments, indicating that it must be short-lived.

Gaweska, Helena M.; Roberts, Kenneth M.; Fitzpatrick, Paul F.

2012-01-01

364

Analysis of the (n,f) Reaction in the Plutonium Isotopes  

NASA Astrophysics Data System (ADS)

This paper describes the modified Hauser-Feshbach formalism used to compute accurately fission cross sections for low-energy neutrons (from a few keV up to 5.5 MeV) in presence of intermediate structure in the second well. Application to the large plutonium isotope family (236 to 244) has been made with in particular reliable predictions of the cross sections of the short-lived nuclides. Special attention is paid to the choice of the model parameters entering in the calculations.

Bouland, Olivier; Lynn, J. Eric; Talou, Patrick

2012-02-01

365

Living Library  

ERIC Educational Resources Information Center

|Living Library, a series of video documents concerned with environmental management, has been used on Texas Tech campus and has been aired commercially to disseminate park and recreation philosophies of notable, contemporary leaders in the field. (MB)|

Mertes, J. D.; And Others

1971-01-01

366

Living Laboratories  

ERIC Educational Resources Information Center

Presented is a review of various methods of keeping live animals, including scorpions, spiders, crabs, crayfish, shrimp, ants, fish, mice, and birds, as well as plants as a school science project/display. (SL)

Mules, B. R.

1976-01-01

367

Living Laboratories  

ERIC Educational Resources Information Center

|Presented is a review of various methods of keeping live animals, including scorpions, spiders, crabs, crayfish, shrimp, ants, fish, mice, and birds, as well as plants as a school science project/display. (SL)|

Mules, B. R.

1976-01-01

368

Assisted Living  

MedlinePLUS

... of residences participating in the research have lower fees and half have higher fees. The rental rate includes the base rent and service fees charged by the assisted living community. While 86. ...

369

Volcano Live  

NSDL National Science Digital Library

Volcano Live contains maps of volcanoes from around the world, a kids' page that provides volcano education links for teachers and students, a volcano glossary, volcano news, links to live video cams of volcanoes, geography and volcano information of countries around the world, and video clips of active volcanoes. There is also information for travelling to volcanoes, a volcano photo section, a section on the destruction of Pompeii, a volcanology section, and volcano safety rules.

Seach, John

370

Short bones  

MedlinePLUS

Short bones in the human body are often cubelike -- the length, width, and height measurements are all about the same. Short bones include the carpal bones (hands, wrist) and tarsal bones (feet, ankles)

371

SHORT STORY: \\  

Microsoft Academic Search

In teaching short story, there are lots of techniques, methods and approaches. One of these methods, especially for the students at the foreign language departments of universities, is literary approaches. Sometimes by abandoning the traditional ways of teaching short story, a trainer may make use of the literary approaches. Analyzing a short story by means of using one or more

Aysel Ünsal

372

Living with fame: Geri and Living with Michael Jackson  

Microsoft Academic Search

This article will examine two recent and contrasting British television documentaries about particular stars\\/celebrities from the world of popular music – Geri (Channel 4, 1999) and Living with Michael Jackson (ITV, 2003). Geri comes from the British documentary film-maker\\/auteur Molly Dineen's journey with Geri Halliwell shortly after she had left the group TheSpice Girls, and Living with Michael Jackson features

Ian Goode

2008-01-01

373

Isotopic Randomness and Maxwell's Demon  

NASA Astrophysics Data System (ADS)

Isotopic disorder in crystals can lead to suppression of thermal conductivity, mobility variations and (weak) Anderson localization on isotopic fluctuations. The latter (AAB, J.ChemPhys.1984) is akin to polaron effect (self-localization due polarization). Possibility of isotopic patterning (IP) increases near melting point (thermally activated isotopic hopping swaps). Crystal near melting threshold become “informationally sensitive” as if its IP is operated by some external Maxwell’s Demon, MD (AAB, URAM J, 2002). At this state short range (e.g. electrostatic inverse square) forces evolve into long-range interactions (due to divergence of order parameter) and information sensitivity can be further amplified by (say) a single fast electron (e.g. beta-particle from decay of 14-C or other radioactive isotope) which may result in cascade of impact ionization events and (short time-scale) enhancement of screening by impact-generated non-equilibrium (non-thermal) electrons. In this state informationally driven (MD-controlled) IP (Eccles effect) can result in decrease of positional entropy signifying emergence of physical complexity out of pure information, similar to peculiar “jinni effect” on closed time loops in relativistic cosmology (R.J.Gott, 2001) or Wheeler’s “it from bit” metaphor. By selecting special IP, MD modifies ergodicity principle in favor of info rich states.

Berezin, Alexander A.

2005-03-01

374

Living and Non-living things  

NSDL National Science Digital Library

This lesson is intended to help students understand the difference between living and non-living things by teaching them the characteristics of living things. Introduction: We know what living things are, right? People are living things, aren't they? Can you think of any other living things? How do you know they are living? Task: If you were asked to explain what the difference between living and non-living things, how would you? This ...

Davies, Mrs.

2010-02-11

375

Semiconductor isotope engineering  

SciTech Connect

Isotopic control of semiconductor crystals offers a wide range of scientific and technical opportunities. We review neutron transmutation doping of natural and isotopically controlled semiconductor structures, special properties of isotope superlattices, the effect of host isotopes on local vibrational modes of low mass impurities, and intrinsic properties which depend on isotope mass and isotopic composition of single crystals.

Haller, E.E.

1993-05-01

376

Positive Lives  

NSDL National Science Digital Library

The Positive Lives project is "a unique international project that photographs and documents the social and emotional impact of the global HIV/AIDS epidemic, illuminating positive human responses to this world crisis." Sponsored by the Levi Strauss Foundation and the Terrence Higgins Trust, the project has sponsored photographers from across the world to photograph various persons living with HIV/AIDS in a host of very different settings. While the project has sponsored a number of various photographic exhibits, this online collection represents a small portion of the work thus far. Using an interactive map of the world, users can click on different geographic areas to view photographic exhibits documenting the lived experience of this condition. In South Africa, visitors can learn about the work and the residents of Nazareth House, which is a children's home in Cape Town taking care of abandoned children with HIV or AIDS. In Edinburgh, visitors are taken through the lives of young drug abusers at the Muirhouse Estate who are also living with either HIV or AIDS. In the words of photographer John Sturrock, "In Muirhouse I witnessed the emotional struggle of people enduring a tragedy..." However, hope is present in these photographic essays as well, as they represent a broad range of emotions.

377

Penning trap mass measurements of rare isotopes produced by projectile fragmentation with LEBIT at NSCL  

NASA Astrophysics Data System (ADS)

The Low-Energy Beam and Ion Trap facility LEBIT at the NSCL at MSU has demonstrated that rare isotopes produced by fast-beam fragmentation can be slowed down and prepared for precision experiments with low-energy beams. High-pressure gas-stopping was combined with advanced ion manipulation techniques to carry out these studies with a high-precision 9.4-Tesla Penning trap mass spectrometer. The spectrometer has been used for a series of high precision mass measurements of short-lived neutron- and proton-rich isotopes during the past year. This paper presents an overview of the LEBIT facility and summarizes the first mass measurement results. The mass measurements of 81Se, where ground and isomeric states have been resolved, and of 80As will be discussed in detail.

Bollen, G.; Bachelet, C.; Block, M.; Davies, D. A.; Facina, M.; Folden, C. M.; Guénaut, C.; Huikari, J.; Kwan, E.; Kwiatowski, A.; Morrissey, D. J.; Pang, G.; Prinke, A.; Ringle, R.; Savory, J.; Schury, P.; Schwarz, S.; Sumithrarachchi, C.; Sun, T.

2007-11-01

378

Homogeneous distribution of 26Al in the solar system from the Mg isotopic composition of chondrules.  

PubMed

The timing of the formation of the first solids in the solar system remains poorly constrained. Micrometer-scale, high-precision magnesium (Mg) isotopic analyses demonstrate that Earth, refractory inclusions, and chondrules from primitive meteorites formed from a reservoir in which short-lived aluminum-26 (26Al) and Mg isotopes were homogeneously distributed at +/-10%. This level of homogeneity validates the use of 26Al as a precise chronometer for early solar system events. High-precision chondrule 26Al isochrons show that several distinct chondrule melting events took place from approximately 1.2 million years (My) to approximately 4 My after the first solids condensed from the solar nebula, with peaks between approximately 1.5 and approximately 3 My, and that chondrule precursors formed as early as 0.87(-0.16)(+0.19) My after. PMID:19696348

Villeneuve, Johan; Chaussidon, Marc; Libourel, Guy

2009-08-21

379

Innovative Lives  

NSDL National Science Digital Library

The Innovative Lives Web Site is offered by the Jerome and Dorothy Lemelson Center for the Study of Invention and Innovation and the Smithsonian Institution. "Innovative Lives counters commonly held stereotypes about inventors by featuring speakers with diverse backgrounds," such as Dr. Patricia Bath, an African-American woman who invented the Laserphaco Probe for the treatment of cataracts and founded the American Institute for the Prevention of Blindness. Over thirty inventors are featured on the site, which gives excellent information about each, telling of their lives and what they have accomplished. Although it is intended for kids, the site will be of interest to anyone looking to learn about many of the most important and unknown contributors to the scientific world.

2002-01-01

380

High-Resolution Isotope Records of the Late Ordovician and Late Carboniferous: A Comparative Perspective on Glacial Carbon and Sulfur Cycles  

NASA Astrophysics Data System (ADS)

Carbonate-associated sulfate (CAS) faithfully tracks the sulfur isotope composition of seawater in both modern and ancient environments. Therefore, analyses of carbonate rocks permit the generation of parallel, high-resolution carbon and sulfur isotope data for seawater spanning geologic history. Our previous work in the early and middle Paleozoic has revealed parallel, short-term (1-4 Myrs) carbon and sulfur isotope excursions. The relationship between the two isotope systems seems to change over time, perhaps tracking longer-term evolution of the marine sulfur reservoir and of the primary loci of carbon burial, including increased burial on land. CAS isotope records therefore have the potential to shed essential mechanistic light on the causes (global versus regional) for carbon isotope excursions observed throughout the geological record. Previous work on the Late Carboniferous and Late Ordovician documented the existence of carbon isotope excursions of varying magnitude during these glacial episodes. The Late Carboniferous glaciations classically show evidence for multiple glacial-interglacial cycles with repeated, low magnitude (1 to 3 per mil) carbon isotope excursions. By contrast, the Late Ordovician was characterized by a short-lived glaciation with a corresponding single 4-6 per mil carbon isotope excursion. The modes and rates of carbon cycling reflected in the differing styles of C isotope behavior are the subject of debate, making these time-slices ideal for the CAS isotope approach. Carbon and sulfur isotope data from Pennsylvanian (Missourian Stage) cyclothems exposed in Kansas City, Missouri, show rapid isotope variability. We have preliminarily attributed these rapid changes to local reservoir effects linked to fluctuating sea level and its relationship to black shale deposition within the midcontinent basin and weathering on the basin margin during lowstands. Other work on the cyclic Carboniferous Bird Spring Formation, Nevada, is also contributing to an improved understanding of the local and global controls on carbon and sulfur cycling during this major glaciation. For comparison, our ongoing work in the Upper Ordovician (Hirnantian Stage) Hanson Creek Formation is exploring carbon-sulfur relationships through the single, large (6 per mil) carbon excursion observed during this glacial episode.

Gill, B. C.; Lyons, T. W.; Saltzman, M. R.

2005-12-01

381

Compelling Research Opportunities using Isotopes  

SciTech Connect

Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1) medicine, pharmaceuticals, and biology, (2) physical sciences and engineering, and (3) national security and other applications. In each area, compelling research opportunities were considered and the subcommittee as a whole determined the final priorities for research opportunities as the foundations for the recommendations. While it was challenging to prioritize across disciplines, our order of recommendations reflect the compelling research prioritization along with consideration of time urgency for action as well as various geopolitical market issues. Common observations to all areas of research include the needs for domestic availability of crucial stable and radioactive isotopes and the education of the skilled workforce that will develop new advances using isotopes in the future. The six recommendations of NSACI reflect these concerns and the compelling research opportunities for potential new discoveries. The science case for each of the recommendations is elaborated in the respective chapters.

None

2009-04-23

382

Lead and strontium isotopic evidence for crustal interaction and compositional zonation in the source regions of Pleistocene basaltic and rhyolitic magmas of the Coso volcanic field, California  

USGS Publications Warehouse

The isotopic compositions of Pb and Sr in Pleistocene basalt, high-silica rhyolite, and andesitic inclusions in rhyolite of the Coso volcanic field indicate that these rocks were derived from different levels of compositionally zoned magmatic systems. The 2 earliest rhyolites probably were tapped from short-lived silicic reservoirs, in contrast to the other 36 rhyolite domes and lava flows which the isotopic data suggest may have been leaked from the top of a single, long-lived magmatic system. Most Coso basalts show isotopic, geochemical, and mineralogic evidence of interaction with crustal rocks, but one analyzed flow has isotopic ratios that may represent mantle values (87Sr/86Sr=0.7036,206Pb/204Pb=19.05,207Pb/204Pb=15.62,208Pb/204Pb= 38.63). The (initial) isotopic composition of typical rhyolite (87Sr/86Sr=0.7053,206Pb/204Pb=19.29,207Pb/204Pb= 15.68,208Pb/204Pb=39.00) is representative of the middle or upper crust. Andesitic inclusions in the rhyolites are evidently samples of hybrid magmas from the silicic/mafic interface in vertically zoned magma reservoirs. Silicic end-member compositions inferred for these mixed magmas, however, are not those of erupted rhyolite but reflect the zonation within the silicic part of the magma reservoir. The compositional contrast at the interface between mafic and silicic parts of these systems apparently was greater for the earlier, smaller reservoirs. ?? 1984 Springer-Verlag.

Bacon, C. R.; Kurasawa, H.; Delevaux, M. H.; Kistler, R. W.; Doe, B. R.

1984-01-01

383

Isotopic abundances - Inferences on solar system and planetary evolution  

NASA Astrophysics Data System (ADS)

For matter that has been removed from a region of nucleosynthetic activity and the effects of interactions with nuclear active particles, the only changes in nuclear abundances that can occur in an isolated system derive from the decay of radioactive nuclei of an element to yield the nucleus of another element. These two related nuclei furnish the absolute chronometers of geologic and cosmic time, through the decay of spontaneously radioactive parent nuclei and the accumulation of daughter nuclei. For systems related to such cosmic processes as the formation of the solar system from the precursor interstellar medium, and involving the very early evolution of the sun, there may arise considerable complexity, due to the intrinsic isotopic heterogeneity of the medium and the presence of short-lived nuclei.

Wasserburg, G. J.

1987-12-01

384

Isotopic generator for bismuth-212 and lead-212 from radium  

DOEpatents

A method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

Atcher, Robert W. (Kensington, MD); Friedman, Arnold M. (Park Forest, IL); Hines, John (Glen Ellyn, IL)

1987-01-01

385

Living Heritage  

NSDL National Science Digital Library

Living Heritage is a website that celebrates New Zealand heritage through the help of the schools and students of New Zealand. The "About Living Heritage" link states that the website is "an online bilingual initiative that enables New Zealand schools to develop and publish an online resource, based on a heritage treasure in their community." Visitors can also read about the five or so groups these stories "Benefit", including New Zealand and the World, in the About Living Heritage link. The "Schools' Stories" link takes visitors to 26 schools' websites produced since 2008, and an archive of 79 schools' websites produced before 2008. By browsing through the stories, visitors can learn about Paddy, the much-loved wandering Airedale who lived on Island Bay in Wellington in the 1930s. The story of Mitiaro High School in the Cook Islands describes how they learned how to build a canoe called a paiere. Finally, a group of Year 1 and 2 students at Russley School write about their discovery that a tree near their school is protected by the city council.

386

Independent Living.  

ERIC Educational Resources Information Center

This issue of "OSERS" addresses the subject of independent living of individuals with disabilities. The issue includes a message from Judith E. Heumann, the Assistant Secretary of the Office of Special Education and Rehabilitative Services (OSERS), and 10 papers. Papers have the following titles and authors: "Changes in the Rehabilitation Act of…

Nathanson, Jeanne H., Ed.

1994-01-01

387

Retiring Lives  

ERIC Educational Resources Information Center

|"Retiring Lives" presents fourteen personal real life stories from people at various stages of retiring. Each author recounts their own story about retiring, bringing together many aspects of the experiences: the social, psychological and practical. These inspirational and illustrated stories will encourage the reader to hold up these experiences…

Carnell, Eileen, Ed.; Lodge, Caroline, Ed.

2009-01-01

388

Living Nanomachines  

Microsoft Academic Search

The living cell is a kind of factory on the microscopic scale, in which an assembly of modular machines carries out, in a spatially and temporally coordinated way, a whole range of activities internal to the cell, including the synthesis of substances essential to its survival, intracellular traffic, waste disposal, and cell division, but also activities related to intercellular communication

M.-F. Carlier; E. Helfer; R. Wade; F. Haraux

2009-01-01

389

Living History  

ERIC Educational Resources Information Center

|John Tinker and Mary Beth Tinker are back in a classroom in their hometown, once again wearing black armbands and drawing attention to a war. Now in their 50s, the siblings are living symbols of constitutional rights for secondary school students. In 1965, they and a handful of others were suspended for wearing black armbands to their public…

Walsh, Mark

2005-01-01

390

Isotopic evidence bearing on Late Triassic extinction events, Queen Charlotte Islands, British Columbia, and implications for the duration and cause of the Triassic/Jurassic mass extinction  

NASA Astrophysics Data System (ADS)

Stable isotope analyses of Late Triassic to earliest Jurassic strata from Kennecott Point in the Queen Charlotte Islands, British Columbia, Canada shows the presence of two distinct and different organic carbon isotope anomalies at the Norian/Rhaetian and Rhaetian/Hettangian (=Triassic/Jurassic) stage boundaries. At the older of these boundaries, which is marked by the disappearance of the bivalve Monotis, the isotope record shows a series of short-lived positive excursions toward heavier values. Strata approaching this boundary show evidence of increasing anoxia. At the higher boundary, marked by the disappearance of the last remaining Triassic ammonites and over 50 species of radiolarians, the isotopic pattern consists of a series of short duration negative anomalies. The two events, separated by the duration of the Rhaetian age, comprise the end-Triassic mass extinction. While there is no definitive evidence as to cause, the isotopic record does not appear similar to that of the impact-caused Cretaceous/Tertiary boundary extinction.

Ward, Peter D.; Garrison, Geoffrey H.; Haggart, James W.; Kring, David A.; Beattie, Michael J.

2004-08-01

391

Hydrogen Isotopes in Beetle Chitin  

Microsoft Academic Search

\\u000a Beetles, one of the most diverse and long-lived animal groups, provide a trove of ecological and palaeoenvironmental information\\u000a largely because their exoskeletons contain chitin, a highly resistant biopolymer which preserves well in the geological record.\\u000a In addition to palaeoenvironmental inferences that can be derived from presence or absence of particular taxa, beetle chitin\\u000a records the hydrogen stable isotope ratios (D\\/H)

Darren R. Gröcke; Maarten van Hardenbroek; Peter E. Sauer; Scott A. Elias

392

Living and non-living things  

NSDL National Science Digital Library

Living things often rely on non-living things to accomplish daily tasks. Living things have several characteristics that non-living things do not, such as the ability to move, eat, breathe, and reproduce. Living things and non-living things can interact even though they do not have the same characteristics.

Olivia Worland (Purdue University;Biological Sciences)

2008-06-25

393

High-power proton linac for transmuting the long-lived fission products in nuclear waste  

SciTech Connect

High power proton linacs are being considered at Los Alamos as drivers for high-flux spallation neutron sources that can be used to transmute the troublesome long-lived fission products in defense nuclear waste. The transmutation scheme being studied provides a high flux (> 10{sup 16}/cm{sup 2}{minus}s) of thermal neutrons, which efficiently converts fission products to stable or short-lived isotopes. A medium-energy proton linac with an average beam power of about 110 MW can burn the accumulated Tc99 and I129 inventory at the DOE's Hanford Site within 30 years. Preliminary concepts for this machine are described. 3 refs., 5 figs., 2 tabs.

Lawrence, G.P.

1991-01-01

394

Live Wires.  

ERIC Educational Resources Information Center

This four-part booklet provides guidance for clergy members interested in establishing or maintaining cooperative relations with local community colleges. Part I presents a metaphorical rationale for these relations; discourages an overemphasis on "presence ministries"; presents ways to initiate short-term exchanges between the college and the…

United Ministries in Education, Valley Forge, PA.

395

Laser Based Techniques for Ultra Trace Isotope Production, Spectroscopy and Detection  

NASA Astrophysics Data System (ADS)

A variety of research activities in the field of fundamental and applied nuclear physics has evolved in the last years using resonantly tuned radiation from powerful lasers. The technique of resonance ionization spectroscopy has delivered outstanding results and found broad acceptance in the last years as a particularly efficient and highly selective method for rare and exotic radioisotope studies. It is used for production, spectroscopy and detection of these species and provides complete isobaric, high isotopic and even some isomeric selection, which altogether is needed for on-line investigation of short lived species far off stability as well as for ultra trace determination. Good overall efficiency pushes the experimental limits of detection in elemental trace analysis down to below 106 atoms per sample, and additionally isotopic selectivity as high as 3 × 1012 has been demonstrated. The widespread potential of resonance ionization techniques is discussed, focusing on the experimental arrangements for applications in selective on-line isotope production, spectroscopy of rare radioisotopes and ultra trace determination of radiotoxic isotopes like 238Pu to 244Pu, 135,137Cs, 89,90Sr or 41Ca in environmental, technical and biomedical samples.

Wendt, Klaus D. A.; Blaum, Klaus; Geppert, Christopher; Müller, Peter; Nörtershäuser, Wilfried; Schmitt, Annette; Schumann, Philipp; Trautmann, Norbert; Bushaw, Bruce A.

2005-04-01

396

Periodic Table Live!  

NSDL National Science Digital Library

Periodic Table Live!, produced by the Division of Chemical Education at the University of Wisconsin-Madison, allows users "to explore a broad range of information about the elements, their reactions, their properties, their structures and their histories." After selecting an element from the periodic table, users can access a myriad of information divided into three sections: Description, Physical, and Atomic. Students can view short videos of many of the elements' reactions with air, water, acids, and bases. The website is equipped with a helpful glossary and images of the elements, scientists, and other related items.

397

Charge breeding rare isotopes for high precision mass measurements: challenges and opportunities  

NASA Astrophysics Data System (ADS)

Ion charge breeding for Penning-trap mass spectrometry has been established as providing a precision increase that scales linearly with the charge state of the ion. Fast and efficient charge breeding is a precondition for the application of this approach to rare isotopes. However, in view of low yields and short half-lives the precision boost is partly compromised by unavoidable ion losses inherent to the charge breeding process. The mass spectrometer TRIUMFs ion trap for atomic and nuclear science is pioneering this field by coupling a Penning trap and an electron beam ion trap to the rare-isotope beam facility ISAC at TRIUMF. Here we present simulations that calculate and maximize the effective precision gain of time-of-flight ion-cyclotron-resonance measurements with highly charged ions of short-lived nuclides. In addition we compare the characteristics of measurements with singly and highly charged ions, and we summarize recent results that explored benefits of charge breeding that go beyond the precision increase.

Simon, M. C.; Macdonald, T. D.; Bale, J. C.; Chowdhury, U.; Eberhardt, B.; Eibach, M.; Gallant, A. T.; Jang, F.; Lennarz, A.; Luichtl, M.; Ma, T.; Robertson, D.; Simon, V. V.; Andreoiu, C.; Brodeur, M.; Brunner, T.; Chaudhuri, A.; Crespo López-Urrutia, J. R.; Delheij, P.; Ettenauer, S.; Frekers, D.; Grossheim, A.; Gwinner, G.; Kwiatkowski, A. A.; Lapierre, A.; Mané, E.; Pearson, M. R.; Ringle, R.; Schultz, B. E.; Dilling, J.

2013-09-01

398

The effects of Snoezelen (multi-sensory behavior therapy) and psychiatric care on agitation, apathy, and activities of daily living in dementia patients on a short term geriatric psychiatric inpatient unit.  

PubMed

A randomized, controlled, single-blinded, between group study of 24 participants with moderate to severe dementia was conducted on a geriatric psychiatric unit. All participants received pharmacological therapy, occupational therapy, structured hospital environment, and were randomized to receive multi sensory behavior therapy (MSBT) or a structured activity session. Greater independence in activities of daily living (ADLs) was observed for the group treated with MSBT and standard psychiatric inpatient care on the Katz Index of Activities of Daily Living (KI-ADL; P = 0.05) than standard psychiatric inpatient care alone. The combination treatment of MSBT and standard psychiatric care also reduced agitation and apathy greater than standard psychiatric inpatient care alone as measured with the Pittsburgh Agitation Scale and the Scale for the Assessment of Negative Symptoms in Alzheimer's Disease (P = 0.05). Multiple regression analysis predicted that within the multi-sensory group, activities of daily living (KI-ADL) increased as apathy and agitation reduced (R2 = 0.42; p = 0.03). These data suggest that utilizing MSBT with standard psychiatric inpatient care may reduce apathy and agitation and additionally improve activities of daily living in hospitalized people with moderate to severe dementia more than standard care alone. PMID:18441625

Staal, Jason A; Sacks, Amanda; Matheis, Robert; Collier, Lesley; Calia, Tina; Hanif, Henry; Kofman, Eugene S

2007-01-01

399

Living with your ileostomy  

MedlinePLUS

... ileostomy - living with; Continent ileostomy - living with; Abdominal pouch - living with; End ileostomy - living with; Ostomy - living ... Waste will pass through the stoma into a pouch that collects it. You will need to learn ...

400

Spontaneous fission of Fm isotopes in the HFB framework  

NASA Astrophysics Data System (ADS)

The multi-dimensional potential energy surface has been calculated for Fm isotopes with A=240-266 in the HFB framework. The spontaneous fission half-lives have been compared with the experimental data.

Warda, M.; Egido, J.; Robledo, L.

2006-07-01

401

Uranium Half-Lives: A Critical Review.  

National Technical Information Service (NTIS)

The experimental data are evaluated and values for the spontaneous fission half-life of exp 238 U and the total half-lives for exp 232 U, exp 233 U, exp 234 U, exp 235 U, exp 236 U, and exp 238 U are recommended. Also the variation of the isotopic abundan...

N. E. Holden

1981-01-01

402

Isotopic and Experimental Constraints on Subsurface U Transport and Fate  

Microsoft Academic Search

U- and Th- series nuclides have provided essential tools for studying weathering and subsurface element transport processes. The radionuclides U, Th, Ra, Rn, and Pb have a range of half-lives and contrasting chemical behaviours, and the isotopic decay systematics that connect the different isotopes can be used to quantify the rates of trace element transport and the extents of interaction

D. Porcelli; S. Strekopytov; S. Shaw; M. Baskaran; D. Hilton; J. Kulongoski

2009-01-01

403

EDUCAUSE Live!  

NSDL National Science Digital Library

Most people know about EDUCAUSE and their work in promoting information technology across higher education, and the EDUCAUSE Live! series fits quite nicely into that mission. Each program in the series consists of an hour-long interactive web seminar, and visitors can interact directly with the host and guests. It is important to register early for each seminar, as they can be quite popular. On the site, visitors can sign up to learn about upcoming programs, and they can also read brief summaries of those events in the near future.

404

New, heavy transuranium isotopes  

SciTech Connect

In this report, we offer our most recent results concerning the decay properties for five new isotopes of Md, No, Lr, and for {sup 258m}Md. In additions to these successful experiments, we have also conducted searches for {sup 263}(105), {sup 264}(105), {sup 272}(109), and superheavy elements from bombardments of {sup 254}Es with heavy ions. {sup 2} An exciting finding in the course of this work is a new fission phenomenon, which we have termed bidmodal fission''. This is described in a subsequent section. The final part summarizes our conclusions based on the unexpectedly long half-lives and surprising fission properties of the heaviest nuclei. 27 refs., 19 figs.

Hulet, E.K.

1990-10-22

405

Neutron capture on Pt isotopes in iron meteorites and the Hf-W chronology of core formation in planetesimals  

NASA Astrophysics Data System (ADS)

The short-lived 182Hf-182W isotope system can provide powerful constraints on the timescales of planetary core formation, but its application to iron meteorites is hampered by neutron capture reactions on W isotopes resulting from exposure to galactic cosmic rays. Here we show that Pt isotopes in magmatic iron meteorites are also affected by capture of (epi)thermal neutrons and that the Pt isotope variations are correlated with variations in 182W/184W. This makes Pt isotopes a sensitive neutron dosimeter for correcting cosmic ray-induced W isotope shifts. The pre-exposure 182W/184W derived from the Pt-W isotope correlations of the IID, IVA and IVB iron meteorites are higher than most previous estimates and are more radiogenic than the initial 182W/184W of Ca-Al-rich inclusions (CAI). The Hf-W model ages for core formation range from +1.6±1.0 million years (Ma; for the IVA irons) to +2.7±1.3 Ma after CAI formation (for the IID irons), indicating that there was a time gap of at least ˜1 Ma between CAI formation and metal segregation in the parent bodies of some iron meteorites. From the Hf-W ages a time limit of <1.5-2 Ma after CAI formation can be inferred for the accretion of the IID, IVA and IVB iron meteorite parent bodies, consistent with earlier conclusions that the accretion of differentiated planetesimals predated that of most chondrite parent bodies.

Kruijer, Thomas S.; Fischer-Gödde, Mario; Kleine, Thorsten; Sprung, Peter; Leya, Ingo; Wieler, Rainer

2013-01-01

406

Attempt to characterize certain organic and mineral substances by their stable isotope composition  

Microsoft Academic Search

The determination of the relative abundance of various stable isotopes--; deuterium, oxygen-18, carbon-13, nitrogen-15, sulphur- 34--can be used to ; characterize the origin of a water body and of an organic or mineral substance in ; the environment. This results from the discovery that isotopic fractioning by ; living organisms occurs. The stable isotope composition of any substance ; reflects,

J. Bripartout; J. C. Fontes; R. Letolle; A. Mariotti; L. Merlivat

1975-01-01

407

From Living Carbocationic to Living Radical Polymerization.  

National Technical Information Service (NTIS)

'Living' carbocationic polymerization is compared to 'living' radical process. Similarities and differences are discussed. 'Living' radical polymerization of vinyl acetate and methyl methacrylate to provide polymers with controlled molecular weights and n...

K. Matyjaszewski

1994-01-01

408

Tungsten isotope evidence from approximately 3.8-Gyr metamorphosed sediments for early meteorite bombardment of the Earth.  

PubMed

The 'Late Heavy Bombardment' was a phase in the impact history of the Moon that occurred 3.8 4.0 Gyr ago, when the lunar basins with known dates were formed. But no record of this event has yet been reported from the few surviving rocks of this age on the Earth. Here we report tungsten isotope anomalies, based on the (182)Hf (182)W system (half-life of 9 Myr), in metamorphosed sedimentary rocks from the 3.7 3.8-Gyr-old Isua greenstone belt of West Greenland and closely related rocks from northern Labrador, Canada. As it is difficult to conceive of a mechanism by which tungsten isotope heterogeneities could have been preserved in the Earth's dynamic crust mantle environment from a time when short-lived (182)Hf was still present, we conclude that the metamorphosed sediments contain a component derived from meteorites. PMID:12140554

Schoenberg, Ronny; Kamber, Balz S; Collerson, Kenneth D; Moorbath, Stephen

2002-07-25

409

American Lives  

NSDL National Science Digital Library

Started as part of the American Culture studies program at Washington University, the American Lives Project is "a new resource for cultural inquiry that allows users to build connections and identify differences between materials." The project brings together oral histories, historical documents, artifacts, sound, and visual media into an online collection that serves as a model for others seeking to do such work. This particular project documents student activism at Washington University from 1964 to 1972. First-time visitors should look at the About area to learn about the design team, the goals of the project, and the technical aspects of this work. Moving on, visitors can click on the How to Use tab for information about examining the collection. Visitors will find protest banners, letters, handouts, photographs by student groups, and links to related media. Also, visitors can create their own curated collections via the My Objects area, which is a great way to highlight items of personal interest. [KMG

410