Proton Magnetic Resonance of Western Red Cedar

The potential of proton magnetic resonance techniques, in particular magnetic resonance imaging, for analysis of western red cedar has been investigated. Proton magnetic resonance experiments were carried out on normal sapwood, heartwood and juvenile wood and on rotten juvenile wood from western red cedar logs at a range of hydration levels. Signals from the solid wood and the water were readily distinguishable, and the solid wood signal was characterized by its second moment, which was about 5 x 109 s-2 above the saturation point for all samples and increased by about 20% below the fiber saturation point. The water signal was separated into earlywood tracheid lumen water, latewood tracheid and ray lumen water, and bound water on the basis of spin-spin relaxation times. In the normal log, heartwood and juvenile wood had substantially less water and also shorter spin-spin relaxation times than the sapwood. The rot sample had considerably more water than normal juvenile wood. With proton NMR the sapwood/heartwood boundary of western red cedar can be distinguished easily, but the heartwood/juvenile wood boundary is more difficult to discern. Rot should be identifiable from surrounding normal wood, especially if in heartwood or juvenile wood. With current technology, magnetic resonance imaging facilities can produce cross-sectional images of whole cedar logs; however these images are mainly of earlywood tracheid lumen water and hence show only about 60% of the water in a normal western red cedar log

ΔI=4\Delta I=4 and ΔI=8\Delta I=8 bifurcations in rotational bands of diatomic molecules

It is shown that the recently observed $\Delta I=4$ bifurcation seen in superdeformed nuclear bands is also occurring in rotational bands of diatomic molecules. In addition, signs of a $\Delta I=8$ bifurcation, of the same order of magnitude as the $\Delta I=4$ one, are observed both in superdeformed nuclear bands and rotational bands of diatomic molecules.Comment: LaTex twice, 10 pages and 5 PS figures provided upon demand by the Author

"Beat" patterns for the odd-even staggering in octupole bands from a quadrupole-octupole Hamiltonian

We propose a collective Hamiltonian which incorporates the standard quadrupole terms, octupole terms classified according to the irreducible representations of the octahedron group, a quadrupole-octupole interaction, as well as a term for the bandhead energy linear in K (the projection of angular momentum on the body-fixed z-axis). The energy is subsequently minimized with respect to K for each given value of the angular momentum I, resulting in K values increasing with I within each band, even in the case in which K is restricted to a set of microscopically plausible values. We demonstrate that this Hamiltonian is able to reproduce a variety of ``beat'' patterns observed recently for the odd-even staggering in octupole bands of light actinides.Comment: LaTeX, 20 pages plus 12 figures given in separate .ps file

Staggering behavior of the low lying excited states of even-even nuclei in a Sp(4,R) classification scheme

We implement a high order discrete derivative analysis of the low lying collective energies of even-even nuclei with respect to the total number of valence nucleon pairs N in the framework of F- spin multiplets appearing in a symplectic sp(4,R) classification scheme. We find that for the nuclei of any given F- multiplet the respective experimental energies exhibit a Delta N=2 staggering behavior and for the nuclei of two united neighboring F- multiplets well pronounced Delta N=1 staggering patterns are observed. Those effects have been reproduced successfully through a generalized sp(4,R) model energy expression and explained in terms of the step-like changes in collective modes within the F- multiplets and the alternation of the F-spin projection in the united neighboring multiplets. On this basis we suggest that the observed Delta N=2 and Delta N=1 staggering effects carry detailed information about the respective systematic manifestation of both high order alpha - particle like quartetting of nucleons and proton (neutron) pairing interaction in nuclei.PACS number(s):21.10.Re, 21.60.FwComment: 22 pages and 6 figures changes in the figure caption

DNA Synthesis Generates Terminal Duplications That Seal End-to-End Chromosome Fusions

End-to-end chromosome fusions that occur in the context of telomerase deficiency can trigger genomic duplications. For over 70 years these duplications have been attributed solely to Breakage-Fusion-Bridge cycles. To test this hypothesis, we examined end-to-end fusions isolated from C. elegans telomere replication mutants. Genome level rearrangements revealed fused chromosome ends possessing interrupted terminal duplications accompanied by template switching events. These features are very similar to disease-associated duplications of interstitial segments of the human genome. A model termed Fork Stalling and Template Switching has been proposed previously to explain such duplications, where promiscuous replication of large, non-contiguous segments of the genome occurs. Thus, a DNA synthesis-based process may create duplications that seal end-to-end fusions, in the absence of Breakage-Fusion-Bridge cycles

Analysis of Delta I =2 staggering in nuclear rotational spectra

A method is proposed and tested for the analysis of Delta I=2 staggering observed in nuclear rotational bands. We examine six super- and hyper-deformed bands, among which that of 149Gd and possibly of 147Gd seem to exhibit real staggering. However, we emphasize that the presence of staggering may not necessarily imply the occurrence of bifurcation. It is also shown that a similar staggering seen in normally deformed bands is a manifestation of band crossings. A more extensive analysis is planned.Comment: 15 pages, Revtex, 15 figures (available upon request at [email protected]

Quadrupole and Hexadecapole Correlations in Rotating Nuclei Studied within the Single-j Shell Model

The influence of quadrupole and hexadecapole residual interactions on rotational bands is investigated in a single-j shell model. An exact shell-model diagonalization of quadrupole-plus-hexadecapole interaction can sometimes produce a staggering of energy levels in the yrast bands.Comment: 15 pages, 9 Postscript figures, REVTEX, to be published in PR

Collective Dipole Bremsstrahlung in Fusion Reactions

We estimate the dipole radiation emitted in fusion processes. We show that a classical bremsstrahlung approach can account for both the preequilibrium and the thermal photon emission. We give an absolute evaluation of the pre-equilibrium component due to the charge asymmetry in the entrance channel and we study the energy and mass dependence in order to optimize the observation. This dynamical dipole radiation could be a relevant cooling mechanism in the fusion path. We stress the interest in experiments with the new available radioactive beams.Comment: 4 pages (LATEX), 4 Postscript figures, minor text modification

Staggering effects in nuclear and molecular spectra

It is shown that the recently observed Delta J = 2 staggering effect (i.e. the relative displacement of the levels with angular momenta J, J+4, J+8, ..., relatively to the levels with angular momenta J+2, J+6, J+10, ...) seen in superdeformed nuclear bands is also occurring in certain electronically excited rotational bands of diatomic molecules (YD, CrD, CrH, CoH), in which it is attributed to interband interactions (bandcrossings). In addition, the Delta J = 1 staggering effect (i.e. the relative displacement of the levels with even angular momentum J with respect to the levels of the same band with odd J) is studied in molecular bands free from Delta J = 2 staggering (i.e. free from interband interactions/bandcrossings). Bands of YD offer evidence for the absence of any Delta J = 1 staggering effect due to the disparity of nuclear masses, while bands of sextet electronic states of CrD demonstrate that Delta J = 1 staggering is a sensitive probe of deviations from rotational behaviour, due in this particular case to the spin-rotation and spin-spin interactions.Comment: LaTeX, 16 pages plus 30 figures given in separate .ps files. To appear in the proceedings of the 4th European Workshop on Quantum Systems in Chemistry and Physics (Marly-le-Roi, France, 1999), ed. J. Maruani et al. (Kluwer, Dordrecht

Prompt dipole radiation in fusion reactions

The prompt gamma ray emission was investigated in the 16A MeV energy region by means of the 36,40Ar+96,92Zr fusion reactions leading to a compound nucleus in the vicinity of 132Ce. We show that the prompt radiation, which appears to be still effective at such a high beam energy, has an angular distribution pattern consistent with a dipole oscillation along the symmetry axis of the dinuclear system. The data are compared with calculations based on a collective bremsstrahlung analysis of the reaction dynamics