Possible solution of the Coriolis attenuation problem

The most consistently useful simple model for the study of odd deformed nuclei, the particle-rotor model (strong coupling limit of the core-particle coupling model) has nevertheless been beset by a long-standing problem: It is necessary in many cases to introduce an ad hoc parameter that reduces the size of the Coriolis interaction coupling the collective and single-particle motions. Of the numerous suggestions put forward for the origin of this supplementary interaction, none of those actually tested by calculations has been accepted as the solution of the problem. In this paper we seek a solution of the difficulty within the framework of a general formalism that starts from the spherical shell model and is capable of treating an arbitrary linear combination of multipole and pairing forces. With the restriction of the interaction to the familiar sum of a quadrupole multipole force and a monopole pairing force, we have previously studied a semi-microscopic version of the formalism whose framework is nevertheless more comprehensive than any previously applied to the problem. We obtained solutions for low-lying bands of several strongly deformed odd rare earth nuclei and found good agreement with experiment, except for an exaggerated staggering of levels for K=1/2 bands, which can be understood as a manifestation of the Coriolis attenuation problem. We argue that within the formalism utilized, the only way to improve the physics is to add interactions to the model Hamiltonian. We verify that by adding a magnetic dipole interaction of essentially fixed strength, we can fit the K=1/2 bands without destroying the agreement with other bands. In addition we show that our solution also fits 163Er, a classic test case of Coriolis attenuation that we had not previously studied.Comment: revtex, including 7 figures(postscript), submitted to Phys.Rev.

Derivation and assessment of strong coupling core-particle model from the Kerman-Klein-D\"onau-Frauendorf theory

We review briefly the fundamental equations of a semi-microscopic core-particle coupling method that makes no reference to an intrinsic system of coordinates. We then demonstrate how an intrinsic system can be introduced in the strong coupling limit so as to yield a completely equivalent formulation. It is emphasized that the conventional core-particle coupling calculation introduces a further approximation that avoids what has hitherto been the most time-consuming feature of the full theory, and that this approximation can be introduced either in the intrinsic system, the usual case, or in the laboratory system, our preference. A new algorithm is described for the full theory that largely removes the difference in complexity between the two types of calculation. Comparison of the full and approximate theories for some representative cases provides a basis for the assessment of the accuracy of the traditional approach. We find that for well-deformed nuclei, e.g. 157Gd and 157Tb, the core-coupling method and the full theory give similar results.Comment: revtex, 3 figures(postscript), submitted to Phys.Rev.

Application of the Kerman-Klein method to the solution of a spherical shell model for a deformed rare-earth nucleus

Core-particle coupling models are made viable by assuming that core properties such as matrix elements of multipole and pairing operators and excitation spectra are known independently. From the completeness relation, it is seen, however, that these quantities are themselves algebraic functions of the calculated core-particle amplitudes. For the deformed rare-earth nucleus 158Gd, we find that these sum rules are well-satisfied for the ground state band, implying that we have found a self-consistent solution of the non-linear Kerman-Klein equations.Comment: revtex and postscript, including 1 figure(postscript), submitted to Phys.Rev.Let

Application of a semi-microscopic core-particle coupling method to the backbending in odd deformed nuclei

In two previous papers, the Kerman-Klein-Donau-Frauendorf (KKDF) model was used to study rotational bands of odd deformed nuclei. Here we describe backbending for odd nuclei using the same model. The backbending in the neighboring even nuclei is described by a phenomenological two band model, and this core is then coupled to a large single-particle space, as in our previous work. The results obtained for energies and M1 transition rates are compared with experimental data for 165Lu and for energies alone to the experimental data for 179W. For the case of 165Lu comparison is also made with previous theoretical work.Comment: 16 pages including 8 figure(postscript), submitted to Phys.Rev.

THE 2D:4D RATIO, HANDEDNESS, AND SEX ACROSS THE AGE SPAN

The ratio of the difference between the 2nd and 4th digits of the hand (2D:4D ratio) has been demonstrated to be an indirect indicator of prenatal testosterone levels. Prenatal testosterone has been found to play a role in brain development in utero, and thus may influence lateral asymmetries, such as handedness. Consequently, one of the aims of the current study was to examine relationships between the 2D:4D ratio, hand preference, and hand performance with the factors of sex (males and females), handedness (right handers and left handers), and age considered. A total of 104 participants were tested, 90 right handers and 14 left handers (age range = 5-to-90, mean age = 31.93, SD = 20.18, females = 58). Participants completed the Waterloo Handedness Questionnaire (WHQ) as an indicator of hand preference and the Tapley- Bryden Dot Marking (TBDM) task to evaluate hand performance. Right and left 2D:4D ratios were measured for all participants using Vernier calipers, measured to the nearest 0.01mm. Regardless of age and sex, left handers had significantly reduced hand preference strength and trended in having reduced hand performance differences between the hands. Furthermore, although only significant in the 50+ years age group, it appeared as though males tended to have decreased handedness compared to females. No significant relationships nor main effects were found with regards to the 2D:4D ratios measured, though. Additional testing was conducted including participants with ASD, who have been illustrated to have lower than average 2D:4D ratios, as well as increased hand ambiguity. Relationships were examined between the 2D:4D ratio, hand preference, and hand performance and comparisons were analyzed between neurotypical participants and participants with ASD. A total of 5 participants with ASD were tested, 4 right handers and 1 left hander (age range = 6-to- 36, 5 males). With the small sample size, all relationships were found to be insignificant and were not generalizable. Comparisons did display significant differences in hand performance, where individuals with ASD illustrated greater hand ambiguity. Overall, the study has demonstrated that sex, handedness, and age influence hand preference and hand performance. However, no relationships were found between handedness and the 2D:4D ratios. Moreover, continuing research on hand ambiguity in individuals with ASD could better the understanding of brain lateralization

Perturbative evolution of far off-resonance driven two-level systems: Coherent population trapping, localization, and harmonic generation

The time evolution of driven two-level systems in the far off-resonance regime is studied analytically. We obtain a general first-order perturbative expression for the time-dependent density operator which is applicable regardless of the coupling strength value. In the strong field regime, our perturbative expansion remains valid even when the far off-resonance condition is not fulfilled. We find that, in the absence of dissipation, driven two-level systems exhibit coherent population trapping in a certain region of parameter space, a property which, in the particular case of a symmetric double-well potential, implies the well-known localization of the system in one of the two wells. Finally, we show how the high-order harmonic generation that this kind of systems display can be obtained as a straightforward application of our formulation.Comment: 14 pages, LaTeX, 2 figures, acknowledgments adde

Stabilization with arbitrary laser polarizations

Published versio

Evolving dimensions in medical case reporting

Medical case reports (MCRs) have been undervalued in the literature to date. It seems that while case series emphasize what is probable, case reports describe what is possible and what can go wrong. MCRs transfer medical knowledge and act as educational tools. We outline evolving aspects of the MCR in current practice

Graph Parameters, Universal Obstructions, and WQO

We introduce the notion of universal obstruction of a graph parameter, with respect to some quasi-ordering relation. Universal obstructions may serve as compact characterizations of the asymptotic behavior of graph parameters. We provide order-theoretic conditions which imply that such a characterization is finite and, when this is the case, we present some algorithmic implications on the existence of fixed-parameter algorithms

Intense field stabilization in circular polarization: 3D time-dependent dynamics

We investigate the stabilization of a hydrogen atom in circularly polarized laser fields. We use a time-dependent, fully three dimensional approach to study the quantum dynamics of the hydrogen atom subject to high intensity, short wavelength laser pulses. We find enhanced survival probability as the field is increased under fixed envelope conditions. We also confirm wavepacket dynamics seen in prior time-dependent computations restricted to two dimensions.Comment: 4 pages, 3 figures, submitte