Quadrupole correlations and inertial properties of rotating nuclei

The contribution of quantum shape fluctuations to inertial properties of rotating nuclei has been analyzed for QQ-nuclear interaction using the random phase approximation (RPA). The different recipes to treat the cranking mean field plus RPA problem are considered. The effects of the dN=2 quadrupole matrix elements and the role of the volume conservation condition are discussed.Comment: 14 pages, 7 figures, To be published in J. Phys. G: Nucl. Phy

Single Boson Images Via an Extended Holstein Primakoff Mapping

The Holstein-Primakoff mapping for pairs of bosons is extended in order to accommodate single boson mapping. The proposed extension allows a variety of applications and especially puts the formalism at finite temperature on firm grounds. The new mapping is applied to the O(N+1) anharmonic oscillator with global symmetry broken down to O(N). It is explicitly demonstrated that N-Goldstone modes appear. This result generalizes the Holstein-Primakoff mapping for interacting boson as developed in ref.[1].Comment: 9 pages, LaTeX. Physical content unchanged. Unnecessary figure remove

Gamow-Teller transitions and deformation in the proton-neutron random phase approximation

We investigate reliability of Gamow-Teller transition strengths computed in the proton-neutron random phase approximation, comparing with exact results from diagonalization in full $0\hbar\omega$ shell-model spaces. By allowing the Hartree-Fock state to be deformed, we obtain good results for a wide variety of nuclides, even though we do not project onto good angular momentum. We suggest that deformation is as important or more so than pairing for Gamow-Teller transitions.Comment: 8 pages, 5 figures; added references, clarified discussion with regards to stabilit

Self-Consistent Velocity Dependent Effective Interactions

The theory of self-consistent effective interactions in nuclei is extended for a system with a velocity dependent mean potential. By means of the field coupling method, we present a general prescription to derive effective interactions which are consistent with the mean potential. For a deformed system with the conventional pairing field, the velocity dependent effective interactions are derived as the multipole pairing interactions in doubly-stretched coordinates. They are applied to the microscopic analysis of the giant dipole resonances (GDR's) of ${}^{148,154}Sm$, the first excited $2^+$ states of Sn isotopes and the first excited $3^-$ states of Mo isotopes. It is clarified that the interactions play crucial roles in describing the splitting and structure of GDR peaks, in restoring the energy weighted sum rule, and in reducing the values of $B(E\lambda)$.Comment: 35 pages, RevTeX, 7 figures (available upon request), to appear in Phys.Rev.

Amnesia Associated with Bilateral Hippocampal and Bilateral Basal Ganglia Lesions in Anoxia with Stimulant Use

We report a case of a 55-year-old man with ischemic lesions of the bilateral hippocampus and bilateral basal ganglia following a myocardial infarction during an episode of multiple drug use with subsequent anoxia requiring resuscitation. He presented for a neuropsychological evaluation with an anterograde amnesia for both explicit and procedural memory. There are two main points to this case, the unique aspects of the bilateral multifocal lesions and the functional, cognitive impact of these lesions. We hypothesize that his rare focal bilateral lesions of both the hippocampus and basal ganglia are a result of anoxia acting in synergy with his stimulant drug use (cocaine and/or 3,4-methylenedioxy-methamphetamine). Second, his unique lesions produced an explicit and implicit/procedural anterograde amnesia

Inertial parameters and superfluid-to-normal phase transition in superdeformed bands

The quasiclassically exact solution for the second inertial parameter $\cal B$ is found in self-consistent way. It is shown that superdeformation and nonuniform pairing arising from the rotation induced pair density significantly reduce this inertial parameter. The different limiting cases for $\cal B$, which allow to study an interplay between rapid rotation, pairing correlations, and mean field deformation, are considered. The new signature for the transition from pairing to normal phase is suggested in terms of the variation of ${\cal B}/{\cal A}$ versus spin. Experimental data indicate the existence of such transition in the three superdeformed mass regions.Comment: 8 pages, LaTeX, 3 figure

Off-Label Use of Transmucosal Ketamine as a Rapidacting Antidepressant: A Retrospective Chart Review

Objective: This study evaluated the effectiveness and safety of subanesthetic doses of ketamine using an off-label, transmucosal administration route in patients with treatment-resistant depression. Methods: A retrospective chart review was conducted to identify patients who met the inclusion criteria for treatment-resistant major depressive disorder. Seventeen such patients who received subanesthetic doses of ketamine were included. Patient demographics, efficacy (drug refill, clinician notes), side effects, and concurrent medications were assessed. Results: Benefit from low-dose transmucosal ketamine was noted in 76% of subjects (average age 48 years, 88% female), with a dose duration lasting 7–14 days. No notable side effects were noted. The most common classes of concurrent medications to which ketamine was added were serotonin–norepinephrine reuptake inhibitors (59%), stimulants (47%), folate replacement (47%), and benzodiazepines (47%). Conclusion: Our results provide preliminary evidence of the effectiveness and safety of lowdose transmucosal ketamine in treatment-resistant patients. A controlled, prospective pilot study is warranted to validate these findings

Backbending and GammaGamma-Vibrations

We propose that the backbending phenomenon can be explained as a result of the disappearance of collective $gamma$-vibrational mode in the rotating frame. Using a cranking+random phase approximation approach for the modified Nilsson potential + monopole pairing forces, we show that this mechanism is responsible for the backbending in $^{156}$Dy, $^{158}$Er and obtain a good agreement between theoretical and experimental results.Comment: 5 pages, 4 figures, published versio

Many-body correlations in a multistep variational approach

We discuss a multistep variational approach for the study of many-body correlations. The approach is developed in a boson formalism (bosons representing particle-hole excitations) and based on an iterative sequence of diagonalizations in subspaces of the full boson space. Purpose of these diagonalizations is that of searching for the best approximation of the ground state of the system. The procedure also leads us to define a set of excited states and, at the same time, of operators which generate these states as a result of their action on the ground state. We examine the cases in which these operators carry one-particle one-hole and up to two-particle two-hole excitations. We also explore the possibility of associating bosons to Tamm-Dancoff excitations and of describing the spectrum in terms of only a selected group of these. Tests within an exactly solvable three-level model are provided.Comment: 24 pages, 6 figures, to appear in Phys. Rev.

Hermitian boson mapping and finite truncation

Starting from a general, microscopic fermion-to-boson mapping that preserves Hermitian conjugation, we discuss truncations of the boson Fock space basis. We give conditions under which the exact boson images of finite fermion operators are also finite (e.g., a 1+2-body fermion Hamiltonian is mapped to a 1+2-body boson Hamiltonian) in the truncated basis. For the most general case, where the image is not necessarily exactly finite, we discuss how to make practical and controlled approximations.Comment: 12 pages in RevTex with no figures, Los Alamos preprint # LA-UR-94-146