Toward a Consistent Description of the PNC Experiments in A=18-21 Nuclei

The experimental PNC results in $^{18}$F, $^{19}$F, $^{21}$Ne and the current theoretical analysis show a discrepancy . If one interprets the small limit of the experimentally extracted PNC matrix element for $^{21}$Ne as a destructive interference between the isoscalar and the isovector contribution, then it is difficult to understand why the isovector contribution in $^{18}$F is so small while the isoscalar + isovector contribution in $^{19}$F is relatively large. In order to understand the origin of this discrepancy a comparison of the calculated PNC matrix elements was performed. It is shown that the $^{18}$F and $^{21}$Ne matrix elements contain important contributions from 3$\hbar \omega$ and 4$\hbar \omega$ configuration and that the (0+1)$\hbar \omega$ calculations give distorted results.Comment: REVTEX, 16 pages, 1 postscriptum figure uuencoded and appende

On the transition from shell structure to collective behavior : A simplified shell-model study

To study the feasibility of carrying out shell-model calculations in nuclei with active protons and neutrons in different major shells, the following simple idealized model has been studied: (i) Proton and neutron configurations are chosen to be and , so that results for the separate proton and neutron basis states to be used in any approximation scheme can be compared with the results for exact shell-model calculations, (ii) The proton and neutron single-particle energies for these active shells are separately taken to be degenerate. (iii) The two-body interaction is approximated by the simple surface delta interaction (SDI). To effect the severe truncation of the full shell-model space needed to make such a shell-model study possible the separate proton and neutron parts of the shell-model basis are built from a superposition of the favored pair states of the SDI (with J [not equal to] 0, as well as J = 0). In the neutron configuration , for example only three of the 94 shell-model states with Jn = 2 are retained in the truncation scheme. In this highly truncated basis both the energies and the strong B(Ek) values for the transitions from these states to similar favored states with other J-values are within a few percent (or better) of the results of exact shell-model calculations. A truncation of the shell-model space based on such superpositions of favored pair states leads to a manageable shell-model basis (dimensions [less, double equals] 200). (a) The number of states in the separate proton and neutron parts of the basis are small enough (8-13 for the proton space, 15-30 for the neutron space). They are also the key states in the following sense (b) They include the low-lying energy eigenstates of the separate p-p and n-n parts of the interaction (c) They contain most of the collective coherence of the separate proton and neutron configurations. (d) The matrix elements of the n-p part of the interaction between the favored states are in general very large compared with the matrix elements between a favored and an excluded state. The latter effect is studied from several aspects, in particular in terms of sum rules for the matrix elements of the surface multipole operators from which the n-p part of the SDI is built. For most of the low-lying favored states the sum over all favored states gives more than 90 % of the total sum rule for the squares of matrix elements of the surface multipole operators. The results of shell-model calculations in this truncation scheme, with np = 4 or 6, and nn = 4, show many of the features of a quadrupole vibrational spectrum. The presence and exact nature of a 0+ member of the 0+, 2+, 4+ "two-phonon triplet" is dependent on the inclusion of the key favored states with seniorities of 6.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33989/1/0000261.pd

A cross-center smoothness prior for variational Bayesian brain tissue segmentation

Suppose one is faced with the challenge of tissue segmentation in MR images, without annotators at their center to provide labeled training data. One option is to go to another medical center for a trained classifier. Sadly, tissue classifiers do not generalize well across centers due to voxel intensity shifts caused by center-specific acquisition protocols. However, certain aspects of segmentations, such as spatial smoothness, remain relatively consistent and can be learned separately. Here we present a smoothness prior that is fit to segmentations produced at another medical center. This informative prior is presented to an unsupervised Bayesian model. The model clusters the voxel intensities, such that it produces segmentations that are similarly smooth to those of the other medical center. In addition, the unsupervised Bayesian model is extended to a semi-supervised variant, which needs no visual interpretation of clusters into tissues.Comment: 12 pages, 2 figures, 1 table. Accepted to the International Conference on Information Processing in Medical Imaging (2019

Ultra-Widefield Imaging of the Retinal Macrovasculature in Parkinson Disease Versus Controls With Normal Cognition Using Alpha-Shapes Analysis

Purpose: To investigate retinal vascular characteristics using ultra-widefield (UWF) scanning laser ophthalmoscopy in Parkinson disease (PD).Methods: Individuals with an expert-confirmed clinical diagnosis of PD and controls with normal cognition without PD underwent UWF imaging (California, Optos). Patients with diabetes, uncontrolled hypertension, glaucoma, dementia, other movement disorders, or known retinal or optic nerve pathology were excluded. Images were analyzed using Vasculature Assessment and Measurement Platform for Images of the Retina (VAMPIRE-UWF; Universities of Edinburgh and Dundee, UK) software which described retinal vessel width gradient and tortuosity, vascular network fractal dimension, as well as alpha-shape analysis to further characterize vascular morphology [complexity (Opαmin) and spread (OpA)].Results: In the PD cohort, 53 eyes of 38 subjects, and in the control cohort, 51 eyes of 33 subjects were assessed. Eyes with PD had more tortuous retinal arteries in the superotemporal quadrant (p = 0.043). In eyes with PD, alpha-shape analysis revealed decreased OpA, indicating less retinal vasculature spread compared to controls (p = 0.032). Opαmin was decreased in PD (p = 0.044), suggesting increased vascular network complexity. No differences were observed in fractal dimension in any ROI.Conclusions: This pilot study suggests that retinal vasculature assessment on UWF images using alpha-shape analysis reveals differences in retinal vascular network spread and complexity in PD and may be a more sensitive metric compared to fractal dimension.Translational Relevance: Retinal vasculature assessment using these novel methods may be useful in understanding ocular manifestations of PD and the development of retinal biomarkers

Ultra-Widefield Imaging of the Retinal Macrovasculature in Parkinson Disease Versus Controls With Normal Cognition Using Alpha-Shapes Analysis

PURPOSE: To investigate retinal vascular characteristics using ultra-widefield (UWF) scanning laser ophthalmoscopy in Parkinson disease (PD).METHODS: Individuals with an expert-confirmed clinical diagnosis of PD and controls with normal cognition without PD underwent Optos California UWF imaging. Patients with diabetes, uncontrolled hypertension, glaucoma, dementia, other movement disorders, or known retinal or optic nerve pathology were excluded. Images were analyzed using Vasculature Assessment and Measurement Platform for Images of the Retina (VAMPIRE-UWF) software, which describes retinal vessel width gradient and tortuosity, provides vascular network fractal dimensions, and conducts alpha-shape analysis to further characterize vascular morphology (complexity, Opαmin; spread, OpA).RESULTS: In the PD cohort, 53 eyes of 38 subjects were assessed; in the control cohort, 51 eyes of 33 subjects were assessed. Eyes with PD had more tortuous retinal arteries in the superotemporal quadrant (P = 0.043). In eyes with PD, alpha-shape analysis revealed decreased OpA, indicating less retinal vasculature spread compared to controls (P = 0.032). Opαmin was decreased in PD (P = 0.044), suggesting increased vascular network complexity. No differences were observed in fractal dimension in any region of interest.CONCLUSIONS: This pilot study suggests that retinal vasculature assessment on UWF images using alpha-shape analysis reveals differences in retinal vascular network spread and complexity in PD and may be a more sensitive metric compared to fractal dimension.TRANSLATIONAL RELEVANCE: Retinal vasculature assessment using these novel methods may be useful in understanding ocular manifestations of PD and the development of retinal biomarkers.</p

Bonn Potential and Shell-Model Calculations for 206,205,204Pb

The structure of the nuclei 206,205,204Pb is studied interms of shell model employing a realistic effective interaction derived from the Bonn A nucleon-nucleon potential. The energy spectra, binding energies and electromagnetic properties are calculated and compared with experiment. A very good overall agreement is obtained. This evidences the reliability of our realistic effective interaction and encourages use of modern realistic potentials in shell-model calculations for heavy-mass nuclei.Comment: 4 pages, 4 figures, submitted to Physical Review

Retinal Biomarker Discovery for Dementia in an Elderly Diabetic Population

Dementia is a devastating disease, and has severe implications on affected individuals, their family and wider society. A growing body of literature is studying the association of retinal microvasculature measurement with dementia. We present a pilot study testing the strength of groups of conventional (semantic) and texture-based (non-semantic) measurements extracted from retinal fundus camera images to classify patients with and without dementia. We performed a 500-trial bootstrap analysis with regularized logistic regression on a cohort of 1,742 elderly diabetic individuals (median age 72.2). Age was the strongest predictor for this elderly cohort. Semantic retinal measurements featured in up to 81% of the bootstrap trials, with arterial caliber and optic disk size chosen most often, suggesting that they do complement age when selected together in a classifier. Textural features were able to train classifiers that match the performance of age, suggesting they are potentially a rich source of information for dementia outcome classification

Spectroscopic factors for bound s-wave states derived from neutron scattering lengths

A simple and model-independent method is described to derive neutron single-particle spectroscopic factors of bound s-wave states in $^{A+1}Z = ^{A}Z \otimes n$ nuclei from neutron scattering lengths. Spectroscopic factors for the nuclei ^{13}C, ^{14}C, ^{16}N, ^{17}O, ^{19}O, ^{23}Ne, ^{37}Ar, and ^{41}Ar are compared to results derived from transfer experiments using the well-known DWBA analysis and to shell model calculations. The scattering length of ^{14}C is calculated from the ^{15}C_{g.s.} spectroscopic factor.Comment: 9 pages (uses revtex), no figures, accepted for publication in PRC, uuencoded tex-files and postscript-files available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Thermal.u

Patterns within Patterns within the Smart Living Experience

Modern technology is increasingly being employed to create a “smart” living experience. These “smart” technology entities are producing copious of amounts data, which in turn rely on increased storage, distribution and computation capacity to manage the data. Depending on the scenario, the diversity of piecemeal solutions almost reflects the diversity of problems they address. But some solutions can be reapplied. In the field of computing, design patterns can provide a general, reusable solution to commonly recurring problems within a given context through software design. This work seeks to determine the core elements of a technology-independent design pattern format and an open software framework can be developed to capture, share and redeploy existing successful and reusable strategies for commonly encountered smart environment use cases. Applying in areas such as assistive technology, energy management and environmental monitoring. The underpinning notion of this paper is to introduce “how, where and why” a rule set based in “design pattern” format could contribute to describe a general “understanding” of given cases in the smart environment domain, as well as allow different processes to collaborate with each other

Shell Model Monte Carlo studies of neutron-rich nuclei in the 1s-0d-1p-0f shells

We demonstrate the feasibility of realistic Shell-Model Monte Carlo (SMMC) calculations spanning multiple major shells, using a realistic interaction whose bad saturation and shell properties have been corrected by a newly developed general prescription. Particular attention is paid to the approximate restoration of translational invariance. The model space consists of the full sd-pf shells. We include in the study some well-known T=0 nuclei and several unstable neutron-rich ones around N=20,28. The results indicate that SMMC can reproduce binding energies, B(E2) transitions, and other observables with an interaction that is practically parameter free. Some interesting insight is gained on the nature of deep correlations. The validity of previous studies is confirmed.Comment: 22 pages + 7 postscript figure