77 research outputs found
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
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A Non-Perturbative Treatment of the Pion in the Linear Sigma-Model
Using a non-perturbative method based on the selfconsistent Quasi-particle
Random-Phase Approximation (QRPA) we describe the properties of the pion in the
linear -model. It is found that the pion is massless in the chiral
limit, both at zero- and finite temperature, in accordance with Goldstone's
theorem.Comment: To appear in Nucl.Phys. A, 16 pages, 2 Postscript figure
Intentional Foreign Body Ingestion: A Complex Case of Pica
Intentional ingestion of foreign objects, a form of self-injurious behavior, is rarely discussed in the medical literature but often requires extensive evaluation, management, and resources. It can be especially problematic for gastroenterologists, who are often consulted for removal of the foreign body. Pica is the psychiatric diagnosis for intentional ingestion of nonnutritive objects and is most commonly seen in prison inmates and those diagnosed with intellectual disability or psychiatric illness. This case report presents a challenging case of pica, highlighting the complexity involved in diagnosis and the need for early psychiatric intervention. It also aims to provide a general review of the literature and practical recommendations to assist with managing this form of self-injurious behavior in the inpatient setting. Collaborative efforts among specialties in addition to primary prevention are vital to successful management of these patients
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 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
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
Intracellular delivery and ultrasonic activation of folate receptor-targeted phase-change contrast agents in breast cancer cells in vitro
Breast cancer is a diverse and complex disease that remains one of the leading causes of death among women. Novel, outside-of-the-box imaging and treatment methods are needed to supplement currently available technologies. In this study, we present evidence for the intracellular delivery and ultrasound-stimulated activation of folate receptor (FR)-targeted phase-change contrast agents (PCCAs) in MDA-MB-231 and MCF-7 breast cancer cells in vitro. PCCAs are lipid-coated, perfluorocarbon-filled particles formulated as nanoscale liquid droplets capable of vaporization into gaseous microbubbles for imaging or therapy. Cells were incubated with 1:1 decafluorobutane (DFB) / octafluoropropane (OFP) PCCAs for 1 hour, imaged via confocal microscopy, exposed to ultrasound (9 MHz, MI = 1.0 or 1.5), and imaged again after insonation. FR-targeted PCCAs were observed intracellularly in both cell lines, but uptake was significantly greater (p < 0.001) in MDA-MB-231 cells (93.0% internalization at MI = 1.0, 79.5% at MI = 1.5) than MCF-7 cells (42.4% internalization at MI = 1.0, 35.7% at MI = 1.5). Folate incorporation increased the frequency of intracellular PCCA detection 45-fold for MDA-MB-231 cells and 7-fold for MCF-7 cells, relative to untargeted PCCAs. Intracellularly activated PCCAs ranged from 500 nm to 6 microns (IQR = 800 nm – 1.5 microns) with a mean diameter of 1.15 ± 0.59 (SD) microns. The work presented herein demonstrates the feasibility of PCCA intracellular delivery and activation using breast cancer cells, illuminating a new platform toward intracellular imaging or therapeutic delivery with ultrasound
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 , the first excited
states of Sn isotopes and the first excited 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 .Comment: 35 pages, RevTeX, 7 figures (available upon request), to appear in
Phys.Rev.
RPA vs. exact shell-model correlation energies
The random phase approximation (RPA) builds in correlations left out by
mean-field theory. In full 0-hbar-omega shell-model spaces we calculate the
Hartree-Fock + RPA binding energy, and compare it to exact diagonalization. We
find that in general HF+RPA gives a very good approximation to the ``exact''
ground state energy. In those cases where RPA is less satisfactory, however,
there is no obvious correlation with properties of the HF state, such as
deformation or overlap with the exact ground state wavefunction.Comment: 6 pages, 7 figures, submitted to Phys Rev
Backbending and -Vibrations
We propose that the backbending phenomenon can be explained as a result of
the disappearance of collective -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 Dy, Er and obtain a good agreement
between theoretical and experimental results.Comment: 5 pages, 4 figures, published versio
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