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- Clark, R M, et al.
(författare)
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Superdeformation in bismuth
- 1996
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:1, s. 117-123
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Tidskriftsartikel (refereegranskat)abstract
- High angular momentum states in Bi-195-197 are populated in two reactions: W-183(F-19,xn)Bi-202-x and Ta-181(Ne-20,xn)Bi-201-x at beam energies of 108 and 123 MeV, respectively. Gamma rays were detected using the Gammasphere array. Three weakly populated rotational sequences have been found. They each have properties characteristic of other superdeformed bands in this mass region. On the basis of cross-bombardment information we believe that one band belongs to each of Bi-195, Bi-196, and Bi-197. The properties of the bands in the odd-Bi nuclei are best reproduced if the odd proton occupies the favored signature of the [651]1/2 orbital, while the band in Bi-196 has this same proton configuration coupled to an additional N=7 (j(15/2)) neutron. The relative behavior of the J((2)) moments of inertia can be qualitatively understood in terms of Pauli-blocking effects.
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| 4. |
- Arft, M, et al.
(författare)
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Responses of tundra plants to experimental warming : Meta-analysis of the international tundra experiment
- 1999
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Ingår i: Ecological Monographs. - 0012-9615 .- 1557-7015. ; 69:4, s. 491-511
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Tidskriftsartikel (refereegranskat)abstract
- The International Tundra Experiment (ITEX) is a collaborative, multisite experiment using a common temperature manipulation to examine variability in species response across climatic and geographic gradients of tundra ecosystems. ITEX was designed specifically to examine variability in arctic and alpine species response to increased temperature. We compiled from one to four years of experimental data from 13 different ITEX sites and used meta-analysis to analyze responses of plant phenology, growth, and reproduction to experimental warming. Results indicate that key phenological events such as leaf bud burst and flowering occurred earlier in warmed plots throughout the study period; however, there was little impact on growth cessation at the end of the season. Quantitative measures of vegetative growth were greatest in warmed plots in the early years of the experiment, whereas reproductive effort and success increased in later years. A shift away from vegetative growth and toward reproductive effort and success in the fourth treatment year suggests a shift from the initial response to a secondary response. The change in vegetative response may be due to depletion of stored plant reserves, whereas the lag in reproductive response may be due to the formation of flower buds one to several seasons prior to flowering. Both vegetative and reproductive responses varied among life-forms; herbaceous forms had stronger and more consistent vegetative growth responses than did woody forms. The greater responsiveness of the herbaceous forms may be attributed to their more flexible morphology and to their relatively greater proportion of stored plant reserves. Finally, warmer, low arctic sites produced the strongest growth responses, but colder sites produced a greater reproductive response. Greater resource investment in vegetative growth may be a conservative strategy in the Low Arctic, where there is more competition for light, nutrients, or water, and there may be little opportunity for successful germination or seedling development. In contrast, in the High Arctic, heavy investment in producing seed under a higher temperature scenario may provide an opportunity for species to colonize patches of unvegetated ground. The observed differential response to warming suggests that the primary forces driving the response vary across climatic zones, functional groups, and through time.
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- Baldsiefen, G, et al.
(författare)
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Shears bands in Pb-193
- 1996
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 54:3, s. 1106-1116
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Tidskriftsartikel (refereegranskat)abstract
- Four bands of enhanced dipole transitions, with weak crossovers, have been observed in Pb-195. Three of these bands are connected to the spherical levels. in addition, the spherical level scheme has been extended. The nuclear spectroscopy was done with the early implementation of GAMMASPHERE and HERA arrays of Get detectors. The nucleus Pb-193 was populated in the Yb-174(Mg-24,5n) reaction at beam energies of 129, 131, and 134 MeV. The experimental results are compared to tilted-axis cranking calculations. The systematical behavior of the dipole bands in the heavier odd-A Pb isotopes, Pb-195,Pb-197,Pb-199,Pb-201, is also discussed.
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- McNabb, D P, et al.
(författare)
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Superdeformation in Po-198
- 1996
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:2, s. R541-R543
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Tidskriftsartikel (refereegranskat)abstract
- The Yb-174(Si-29,5n) reaction at 148 MeV with thin targets was used to populate high-angular momentum states in Po-198. Resulting gamma rays were observed with Gammasphere. A weakly populated superdeformed band of 10 gamma-ray transitions was found and has been assigned to Po-198. This is the first observation of an SD band in the A approximate to 190 region in a nucleus with Z > 83. The J((2))) of the new band is very similar to those of the yrast SD bands in Hg-194 and Pb-196. The intensity profile suggests that this band is populated through states close to where the SD band crosses the yrast line and the angular momentum at which the fission process dominates.
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- Brinkman, M J, et al.
(författare)
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Decay from a superdeformed band in Pb-194
- 1996
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 53:4, s. R1461-R1464
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Tidskriftsartikel (refereegranskat)abstract
- Three experiments using the (174) Yb(Mg-25,5n)Pb-194 reaction have been undertaken at the Early Implementation of Gammasphere to study the decay of known superdeformed states in Pb-194. A single discrete transition with an energy of 2.746(2) MeV carrying 6(2)% of the full superdeformed band intensity has been identified. A discussion of our results and the assignment of the 2.746-MeV transition as a discrete gamma ray directly connecting the superdeformed 8(+) and low-lying 6(+) levels will be presented.
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| 8. |
- FALLON, P, et al.
(författare)
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PROTON AND NEUTRON EXCITATIONS IN SUPERDEFORMED TB-150
- 1995
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Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 52:1, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- Two new superdeformed (SD) bands have been observed in Tb-150 using the reaction P-31 + Sn-124 and the GAMMASPHERE detector array. These new bands are interpreted as being excited SD configurations involving a proton and a neutron particle-hole excitation, respectively. The configurations are discussed in terms of the occupancy of high-N intruder orbitals. These data are used to provide information on (i) the contribution to the dynamic moments of inertia due to the occupation of specific orbitals, (ii) the deformation driving effects of the particle-hole states, and (iii) the consequences of these effects on pairing and band crossings.
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| 11. |
- Fernandez-Mateos, P, et al.
(författare)
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Point mutations and deletion responsible for the Bombay H null and the Reunion H weak blood groups.
- 1998
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Ingår i: Vox sanguinis. - 0042-9007. ; 75:1, s. 37-46
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Definition of the molecular basis of the Reunion and the Bombay red cell and salivary H-deficient phenotypes. METHODS: Sequence and expression of FUT1 and FUT2 genes from H-deficient individuals. Family segregation analysis of the mutations responsible for the fucosyltransferase defects of H, secretor and Lewis systems. RESULTS: The Indian red cell H null Bombay phenotype depends on a new mutation of the FUT1 gene. T725-->G changing Leu242-->Arg. Their salivary nonsecretor phenotype is secondary to a complete deletion of the FUT2 gene. The red cell H weak Reunion phenotype depends on another new mutation of FUT1, C349-->T which induces a change of His117-->Tyr. Their salivary nonsecretor phenotype is due to the known Caucasian inactivating mutation G428-->A. CONCLUSION: Single prevalent FUT1 and FUT2 point mutations and a deletion are responsible for the Indian Bombay H null and the Reunion H weak phenotypes found on Reunion island. This is in contrast with other H-deficient phenotypes where sporadic nonprevalent inactivating mutations are the rule.
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