76 research outputs found

    High-spin parity doublets in the nucleus 151 Pm

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    The high-spin-level structure of the nucleus 151Pm has been investigated by in-beam γ-ray spectroscopy using the 150Nd(α, p2N) 151Pm reaction. The observed enhanced E1 transitions with B(E1) of the order of 10-3 W.u. and parity doubling, both features characteristic of a reflection-asymmetric mean field, suggest an octupole deformation in 61151P

    Redescription of Milnesium alpigenum Ehrenberg, 1853 (Tardigrada: Apochela) and a description of Milnesium inceptum sp. nov., a tardigrade laboratory model

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    Intra- and interspecific variability, being at the very core of alpha taxonomy, has been a long-standing topic of debate among tardigrade taxonomists. Early studies tended to assume that tardigrades exhibit wide intraspecific variation. However, with more careful morphological studies, especially those incorporating molecular tools that allow for an independent verification of species identifications based on phenotypic traits, we now recognise that ranges of tardigrade intraspecific variability are narrower, and that differences between species may be more subtle than previously assumed. The taxonomic history of the genus Milnesium, and more specifically that of the nominal species, M. tardigradum described by Doyère in 1840, is a good illustration of the evolution of views on intraspecific variability in tardigrades. The assumption of wide intraspecific variability in claw morphology led Marcus (1928) to synonymise two species with different claw configurations, M. alpigenum and M. quadrifidum, with M. tardigradum. Currently claw configuration is recognised as one of the key diagnostic traits in the genus Milnesium, and the two species suppressed by Marcus have recently been suggested to be valid. In this study, we clarify the taxonomic status of M. alpigenum, a species that for nearly a century was considered invalid. We redescribe M. alpigenum, using a population collected from the locus typicus, by the means of integrative taxonomy, i.e. including light microscopy, scanning electron microscopy, ontogenetic observations, and genetic barcoding. Moreover, the redescription of M. alpigenum allowed us to verify the uncertain taxonomic status of two popular laboratory models that were originally considered to be M. tardigradum; though one was recently reidentified as M. cf. alpigenum. Our analysis showed that both laboratory strains, despite being morphologically and morphometrically nearly identical to M. alpigenum, in fact represent a new species, M. inceptum sp. nov.  The two species, being disnguishable only by statistical morphometry and/or DNA sequences, are the first example of pseudocryptic species in tardigrades. </jats:p

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    An even-odd isotope of ruthenium, 111Ru, is investigated in the framework of the Core-Quasiparticle Coupling model. The energy levels and wave functions of low-lying states are calculated. The only one parameter adjusted to obtain the results in agreement with experimental data is the strength of the core-particle quadrupole-quadrupole interaction. The neighbouring even-even cores, 110Ru and 112Ru, are described by means of the collective “quadrupole plus pairing” model with the Bohr Hamiltonian determined fully from a microscopic theory without any adjustable parameter. Results for 111Ru are compared with a new set of experimental data obtained recently. An importance of the pairing interaction is confirmed. A remarkable agreement of theoretical results and experimental data is obtained for all eight positive- and negative-parity bands delivered by the newest experiment

    Polarisation sensitivity of the CLUSTER detector used in EUROBALL array

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    The linear polarisation sensitivity of the CLUSTER detector used in the EUROBALL III array was measured. Measurements confirm the results of the Monte Carlo simulation. (c) 2005 Elsevier B.V. All rights reserved
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