| 1. |
- Fischer, S. M., et al.
(författare)
-
Alignment delays in the N = Z nuclei Kr-72, Sr-76, and Zr-80
- 2001
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 8713:13
-
Tidskriftsartikel (refereegranskat)abstract
- The ground state rotational bands of the N = Z nuclei Kr-72, Sr-76, and Zr-80 have been extended into the angular momentum region where rotation alignment of particles is normally expected. By measuring the moments of inertia of these bands we have observed a consistent increase in the rotational frequency required to start pair breaking, when compared to neighboring nuclei. Kr-72 shows the most marked effect. It has been widely suggested that these delayed alignments arise from np-pairing correlations. However, alignment frequencies are very sensitive to shape degrees of freedom and normal pairing, so the new experimental observations are still open to interpretation.
|
|
| 2. |
- Kelsall, N. S., et al.
(författare)
-
Testing mean-field models near the N=Z line : gamma-ray spectroscopy of the T-z=1/2 nucleus Kr-73
- 2002
-
Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 65:4
-
Tidskriftsartikel (refereegranskat)abstract
- Excited states in the N=Z+1 nucleus Kr-73 have been investigated using the Ca-40(Ar-36,2pn) and Ca-40(Ca-40,alpha2pn) reactions at 145 and 160 MeV, respectively. gamma rays were detected using the Gammasphere array and events were recorded in coincidence with charged-particle and neutron detectors. The three previously observed bands were extended to high spin, and a new unfavored positive-parity band has been observed. The alignment characteristics and decay properties of the bands are all consistent with large-deformation prolate rotation, with no clear evidence for oblate bands or shape coexistence. This is quite different from neighboring Kr-72,Kr-74, indicating a strong shape-stabilizing role for the valence neutron. The experimental results are compared to extended total Routhian surface, cranked Nilsson Strutinsky, and cranked relativistic mean-field calculations. The results suggest that the paired calculations lack some important physics. Neutron-proton correlations may be the missing ingredient. There is also evidence for an unusual band crossing in the negative-parity bands, which may indicate the presence of T=0 pairing correlations. At high spin all the models can reproduce the experimental data.
|
|
| 3. |
- McDonald, C., et al.
(författare)
-
ELMy H-modes in JET helium-4 plasmas
- 2004
-
Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 46:3, s. 519-534
-
Tidskriftsartikel (refereegranskat)abstract
- ELMy H-modes in helium-4 plasmas provide valuable information on ELMy H-mode physics as well as a possible early low activation operational phase for next-step tokamaks, such as ITER. With this in mind, a series of helium-4 H-mode experiments were performed on JET with pure helium-4 NBI auxiliary heating (up to 12 MW). A set of ELMy H-mode plasmas were produced, in both the Type I ELM regime and a second regime, which showed characteristics similar to the deuterium Type III regime, but with a reverse ELM frequency dependence on power. Sawteeth were also observed, and had similar behaviour to those seen in deuterium. Compared with deuterium plasmas, Type I ELMy H-mode confinement is seen to be 28 +/- 6% poorer in helium-4 plasmas and the L-H power threshold 42 +/- 10% larger. This is the opposite of the behaviour predicted by experimental isotope mass scalings from hydrogenic plasmas.Comparison with a wider hydrogenic database, enables the effects of isotopic charge and mass to be studied independently.
|
|
| 4. |
|
|
| 5. |
- Bäck, Torbjörn, et al.
(författare)
-
First observation of gamma-rays from the proton emitter Au-171
- 2003
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 16:4, s. 489-494
-
Tidskriftsartikel (refereegranskat)abstract
- Gamma-rays from the alpha- and proton-unstable nuclide Au-171 have been observed for the first time. The gamma-rays were correlated with both a proton- and an alpha-particle decay branch, confirming that the nucleus decays by alpha and proton emission from a single (11/2(-)) state. The measurement confirms the previously determined half-lives for these particle decays but the present values are of higher precision. In addition, a longer half-life than determined in previous work was measured for the proton-unstable tentative ground state. The results are discussed in relation to structures in neighbouring nuclei and compared with a Strutinsky-type TRS calculation.
|
|
| 6. |
- Bäck, Torbjörn, et al.
(författare)
-
Spectroscopy of the neutron-deficient nuclide Pt-171
- 2003
-
Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 17:1, s. 1-5
-
Tidskriftsartikel (refereegranskat)abstract
- A number of previously unobserved gamma-rays emitted from the neutron-deficient nuclide Pt-171 have been identified using the recoil decay tagging technique. The level scheme has been updated using information from gamma-gamma coincidences and angular distribution measurements. To further confirm the assignments of the gamma-rays to Pt-171, the events were correlated with the alpha-decay of the daughter nucleus Os-167.
|
|
| 7. |
- Jenkins, S. R., et al.
(författare)
-
Population dynamics of the intertidal barnacle Semibalanus balanoides at three European locations: spatial scales of variability
- 2001
-
Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 217, s. 207-217
-
Tidskriftsartikel (refereegranskat)abstract
- Spatial variability in the population dynamics of the intertidal acorn barnacle Semibalanus balanoides was investigated using a hierarchical sampling programme. Variability in a number of population parameters (size distribution, density, % cover, absolute growth and instantaneous mortality) was determined separately for new recruits and adults over 3 spatial scales. Three locations, SW Ireland, the Isle of Man and the west coast of Sweden, which cover a large part of the European range of this species, were selected to investigate variability over a large spatial scale (100s of kilometres). Two smaller scales, shore (1000s of metres) and site (10s of metres) nested within each location were also used. In addition, temporal variation over two 6 mo periods was also examined in the Isle of Man and Ireland. Most variability for all population parameters occurred over the largest spatial scale (location). This was a direct result of differences between Sweden and the other 2 locations, the Isle of Man and Ireland, which showed highly similar levels of all population parameters. The population of S, balanoides at the Swedish location was characterised by high growth rates, large size, high levels of mortality and a large turnover of bare space. At the spatial scale 'shore', only 1 population parameter, the growth rate of recruits, showed variability. At the smallest scale of 'site', all parameters showed significant variability except growth rate of adults. Calculation of variance components showed that differences between replicates (spatial scale: <0.5 m) accounted for little of the overall variability, in general less than the scales of site and shore. Examination of temporal variability over two 6 mo periods revealed no difference between time periods and no significant interaction between temporal and spatial scales, Thus, there was consistency of spatial variability over time. The potential causes of variability in population parameters of S, balanoides at different spatial scales and the implications for future studies are discussed.
|
|
| 8. |
- Jenkins, S. R., et al.
(författare)
-
Spatial and temporal variation in settlement and recruitment of the intertidal barnacle Semibalanus balanoides (L.) (Crustacea : Cirripedia) over a European scale
- 2000
-
Ingår i: Journal of Experimental Marine Biology and Ecology. - 0022-0981. ; 243:2, s. 209-225
-
Tidskriftsartikel (refereegranskat)abstract
- Variation in the level of settlement and recruitment in the intertidal barnacle Semibalanus balanoides was studied using a hierarchical sampling programme. The effect of three spatial scales, 10s of metres (sites), 1000s of metres (shores) and 100s of kilometres (locations), was determined. The largest spatial scale represented the distance between four widely separated locations, Sweden, the Isle of Man, SW Ireland and SW England, covering a. large part of the range of S. balanoides in Europe. Temporal variation was determined by comparison between two years, 1997 and 1998. The settlement period of S. balanoides varied in length and timing, being earlier and shorter at the most northerly location, Sweden. The duration of settlement showed little difference among shores within locations, but the pattern of settlement did vary. Estimates of total settlement throughout the settlement period and of recruitment at the end of this period both showed substantial variation among locations which was dependent on the year of study. There was little consistency in the ranking of locations between the two years. Recruitment showed significant variation I the lower spatial scales of shore and site. In addition, examination of variance components showed a high degree of variation between replicates within sites in 1997. There was a significant relationship between settlement and recruitment at three of the four locations. Across all locations variation in settlement explained between 29 and 99% of variation in recruitment. However, locations showed distinct differences in the level of post-settlement survival. (C) 2000 Elsevier Science B.V. All rights reserved.
|
|
| 9. |
- Popat, S, et al.
(författare)
-
Variation in the CTLA4/CD28 gene region confers an increased risk of coeliac disease.
- 2002
-
Ingår i: Annals of human genetics. - 0003-4800 .- 1469-1809. ; 66:Pt 2, s. 125-37
-
Tidskriftsartikel (refereegranskat)abstract
- Susceptibility to coeliac disease involves HLA and non-HLA-linked genes. The CTLA4/CD28 gene region encodes immune regulatory T-cell surface molecules and is a strong candidate as a susceptibility locus. We evaluated CTLA4/CD28 in coeliac disease by genetic linkage and association and combined our findings with published studies through a meta-analysis. 116 multiplex families were genotyped across CTLA4/CD28 using eight markers. The contribution of CTLA4/CD28 to coeliac disease was assessed by non-parametric linkage and association analyses. Seven studies were identified that had evaluated the relationship between CTLA4/CD28 and coeliac disease and a pooled analysis of data undertaken. In our study there was evidence for a relationship between variation in the CTLA4/CD28 region and coeliac disease by linkage and association analyses. However, the findings did not attain formal statistical significance (p = 0.004 and 0.039, respectively). Pooling findings with published results showed significant evidence for linkage (504 families) and association (940 families): p values, 0.0001 and 0.0014 at D2S2214, respectively, and 0.0008 and 0.0006 at D2S116, respectively. These findings suggest that variation in the CD28/CTLA4 gene region is a determinant of coeliac disease susceptibility. Dissecting the sequence variation underlying this relationship will depend on further analyses utilising denser sets of markers.
|
|
| 10. |
- Popat, S, et al.
(författare)
-
Genome screening of coeliac disease
- 2002
-
Ingår i: Journal of Medical Genetics. - : BMJ. - 0022-2593 .- 1468-6244. ; 39:5, s. 328-331
-
Tidskriftsartikel (refereegranskat)
|
|
