Direct Evidence for Octupole Deformation in 146^{146}Ba and the Origin of Large E1E1 Moment Variations in Reflection-Asymmetric Nuclei

Despite the more than one order of magnitude difference between the measured dipole moments in $^{144}$Ba and $^{146}$Ba, the strength of the octupole correlations in $^{146}$Ba are found to be as strong as those in $^{144}$Ba with a similarly large value of $B(E3;3^- \rightarrow 0^+)$ determined as 48($^{+21}_{-29}$) W.u. The new results not only establish unambiguously the presence of a region of octupole deformation centered on these neutron-rich Ba isotopes, but also manifest the dependence of the electric dipole moments on the occupancy of different neutron orbitals in nuclei with enhanced octupole strength, as revealed by fully microscopic calculations.Comment: 6 pages, 5 figures, accepted for publication in Phys. Rev. Let

: DDC gene variants in autism

International audienceThough genetic risk factors are important for the development of autism, no specific risk alleles have yet been identified. DOPA decarboxylase (DDC) is involved in both the catecholaminergic and serotonergic pathways and may be considered a functional candidate gene for autism. The present study is the first to test if two new variants of possible functional significance in the DDC gene increase the susceptibility to autism. A total of 90 parent-offspring trios recruited in Denmark and France were investigated using the transmission disequilibrium test (TDT). We found no evidence of linkage disequilibrium between autism and either of the two polymorphisms. Nor did we find linkage disequilibrium between autism and haplotypes of the two variants using a multiallelic TDT. These findings suggest that the DDC gene is unlikely to play a major role in the development of autism in our data set

Analysis of transmission of novel polymorphisms in the somatostatin receptor 5 (SSTR5) gene in patients with autism.

International audienceInfantile autism is a pervasive developmental disorder with a strong genetic component. The mode of inheritance appears to be complex and no specific susceptibility genes have yet been identified. Chromosome 16p13.3 may contain a susceptibility gene based on findings from genome scans and reports of chromosome abnormalities in individuals with autism. The somatostatin receptor 5 (SSTR5) gene is located on chromosome 16p13.3 and is thus a positional candidate gene for autism. SSTR5 may also be a functional candidate gene for autism because somatostatin inhibits growth hormone secretion, and increased growth hormone response has been reported in some individuals with autism. Moreover, the somatostatinergic system interacts with the dopaminergic system, which has been hypothesized to be involved in the etiology of autism; in particular, somatostatin secretion is regulated by dopamine, and the dopamine D2 receptor and the SSTR5 receptor interact to form a receptor complex with enhanced functional activity. In the present study, we tested whether the alleles of twelve new single nucleotide polymorphisms (SNPs) in the SSTR5 gene were preferentially transmitted, using the transmission disequilibrium test (TDT) in a sample of 79 trios with autism (18 from Denmark and 61 from France). Furthermore, we combined four missense SNPs into haplotypes and searched for preferential transmission using the program TRANSMIT. No significant preferential transmission of the alleles and haplotypes of the twelve SNPs was found. Our results do not suggest the SSTR5 gene as a susceptibility gene for autism

Motional narrowing and ergodic bands in excited superdeformed states of 194Hg

International audienceThe Egamma-Egamma coincidence spectra from the electromagnetic decay of excited superdeformed states in 194Hg reveal surprisingly narrow ridges, parallel to the diagonal. 100-150 excited bands are found to contribute to these ridges, which account for nearly all the unresolved E2 decay strength. Comparison with theory suggests that these excited bands have many components in their wavefunctions, yet they display remarkable rotational coherence. This phenomenon can be explained in terms of the combination of shell effects and motional narrowing

Search for Weak Side Branches in the Electromagnetic Decay Paths of the 6526-keV 10+ Isomer in 54Fe

High-spin nuclear isomers in (Formula presented.) nuclei between doubly magic (Formula presented.) Ca and (Formula presented.) Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV (Formula presented.) isomer in (Formula presented.) Fe. The isomer was strongly populated by means of the fusion-evaporation reaction (Formula presented.) Mg((Formula presented.) Ar, (Formula presented.)) (Formula presented.) Fe. The Gammasphere array was used to detect (Formula presented.) -ray cascades emitted from the isomeric state. By means of (Formula presented.) coincidences, weak non-yrast decay branches can be discriminated, with the isomer’s half-life confirmed at (Formula presented.) ns. The yrast (Formula presented.)   (Formula presented.) cross-over transition was interrogated. The observations are compared with shell-model calculations