Total -ray spectrum in Ho153: From the yrast line into the continuum

The radiation from Ho153 has been measured with Compton-suppressed Ge detectors. At least four components can be identified; the energy and spin removed by each of these have been measured, and their Doppler shifts analyzed. New fine structure is observed in the pre-yrast spectrum which arises from single-particle transitions forming the link between the yrast and continuum cascades. Near the yrast line the single-particle character of the states is preserved, but at higher energies collective modes begin to dominate

Level structure of 153Dy and the competition between collective and few-particle excitation modes in Dy Nuclei

The 153Dy level structure has been studied through the 124Sn(34S, 5n) reaction. The low-spin collective character of 153Dy gives way to single particle yrast configurations at I > 41 2; an I= 47 2 isomer at 5591 ke V shows the single particle character (and overall oblate shape) to be well established at that spin. Nuclear shape charges in Dy nuclei are discussed

Lifetime measurements in 184Pt and the shape coexistence picture

Lifetimes for levels in the yrast band of 184Pt have been measured up to spin 16+ using the recoil distance technique. The B(E2) values exhibit a marked increase in going from spin 2 to 10, consistent with a proposal that two bands of different deformations are mixing at low spin. This provides further support for shape coexistence occuring at low excitation energies in this region

Four-valence-proton yrast states in Er8268150

The level structure of the four-valence-proton N=82 nucleus Er150 has been studied by -ray spectroscopy following reactions of 225-255 MeV Ni58,60 beams on Mo92,94,95 and Nb93 targets. Yrast levels in Er150 are established up to 9.5 MeV excitation energy; they include isomeric levels at 2797, 7372, and 9509 keV. The observed levels up to 5222 keV are interpreted in terms of shell model configurations involving the four valence protons outside the Gd146 core. They include states with dominant seniority two and four configurations h1124, h1123s12, and h1123d32, and octupole excitations. The levels above 5222 keV must involve excitation of the Gd146 core, and they are not interpreted in detail. The energies of the h1124 levels are found to agree reasonably with predictions based on empirical two-body interactions taken from the h1122 spectrum of Dy148. Even better agreement is obtained by taking account also of the known h1123 energies in Ho149. The dependence of E2 transition probabilities in N=82 nuclei on the h112 subshell occupation number is discussed

Evolution of nuclear structure with increasing spin and internal excitation energy in 152Dy

The total γ ray spectrum emitted by 152Dy has been measured in two different reactions and decomposed into its constituent parts. From the measured decay times, multiplicities, multipolarities and spectral shapes, the average decay path has been reconstructed. The yrast single-particle structures have been shown to give way to highly collective bands at internal excitations energies > 1.5 MeV. A model, which takes into account the competition between statistical and collective decay at high spin and temperature, has been used to fit all features of the data, yielding Qt=7.0+2.5-1.5 e b for the collective bands

In Vivo Targeting of Neural Progenitor Cells in Ferret Neocortex by In Utero Electroporation.

Manipulation of gene expression in vivo during embryonic development is the method of choice when analyzing the role of individual genes during mammalian development. In utero electroporation is a key technique for the manipulation of gene expression in the embryonic mammalian brain in vivo. A protocol for in utero electroporation of the embryonic neocortex of ferrets, a small carnivore, is presented here. The ferret is increasingly being used as a model for neocortex development, because its neocortex exhibits a series of anatomical, histological, cellular, and molecular features that are also present in human and nonhuman primates, but absent in rodent models, such as mouse or rat. In utero electroporation was performed at embryonic day (E) 33, a midneurogenesis stage in ferret. In utero electroporation targets neural progenitor cells lining the lateral ventricles of the brain. During neurogenesis, these progenitor cells give rise to all other neural cell types. This work shows representative results and analyses at E37, postnatal day (P) 1, and P16, corresponding to 4, 9, and 24 days after in utero electroporation, respectively. At earlier stages, the progeny of targeted cells consists mainly of various neural progenitor subtypes, whereas at later stages most labeled cells are postmitotic neurons. Thus, in utero electroporation enables the study of the effect of genetic manipulation on the cellular and molecular features of various types of neural cells. Through its effect on various cell populations, in utero electroporation can also be used for the manipulation of histological and anatomical features of the ferret neocortex. Importantly, all these effects are acute and are performed with a spatiotemporal specificity determined by the user