1,325 research outputs found
Low energy collective modes of deformed superfluid nuclei within the finite amplitude method
Background: The major challenge for nuclear theory is to describe and predict
global properties and collective modes of atomic nuclei. Of particular interest
is the response of the nucleus to a time-dependent external field that impacts
the low-energy multipole and beta-decay strength.
Purpose: We propose a method to compute low-lying collective modes in
deformed nuclei within the finite amplitude method (FAM) based on the
quasiparticle random-phase approximation (QRPA). By using the analytic property
of the response function, we find the QRPA amplitudes by computing the residua
of the FAM amplitudes by means of a contour integration around the QRPA poles
in a complex frequency plane.
Methods: We use the superfluid nuclear density functional theory with Skyrme
energy density functionals, FAM-QRPA approach, and the conventional matrix
formulation of the QRPA (MQRPA).
Results: We demonstrate that the complex-energy FAM-QRPA method reproduces
low-lying collective states obtained within the conventional matrix formulation
of the QRPA theory. Illustrative calculations are performed for the isoscalar
monopole strength in deformed 24Mg and for low-lying K = 0 quadrupole
vibrational modes of deformed Yb and Er isotopes.
Conclusions: The proposed FAM-QRPA approach allows one to efficiently
calculate low-lying collective modes in spherical and deformed nuclei
throughout the entire nuclear landscape, including shape-vibrational
excitations, pairing vibrational modes, and beta-decay rates.Comment: 9 pages, 2 figures, submitted to Phys. Rev.
Nuclear matrix elements of neutrinoless double beta decay with improved short-range correlations
Nuclear matrix elements of the neutrinoless double beta decays of 96Zr,
100Mo, 116Cd, 128Te, 130Te and 136Xe are calculated for the light-neutrino
exchange mechanism by using the proton-neutron quasiparticle random-phase
approximation (pnQRPA) with a realistic nucleon-nucleon force. The g_pp
parameter of the pnQRPA is fixed by the data on the two-neutrino double beta
decays and single beta decays. The finite size of a nucleon, the higher-order
terms of nucleonic weak currents, and the nucleon-nucleon short-range
correlations (s.r.c) are taken into account. The s.r.c. are computed by the
traditional Jastrow method and by the more advanced unitary correlation
operator method (UCOM). Comparison of the results obtained by the two methods
is carried out. The UCOM computed matrix elements turn out to be considerably
larger than the Jastrow computed ones. This result is important for the
assessment of the neutrino-mass sensitivity of the present and future double
beta experiments.Comment: Two figures, to be published in Physical Review C (2007) as a regular
articl
Improved short-range correlations and 0nbb nuclear matrix elements of 76Ge and 82Se
We calculate the nuclear matrix elements of the neutrinoless double beta
() decays of Ge and Se for the light-neutrino
exchange mechanism. The nuclear wave functions are obtained by using realistic
two-body forces within the proton-neutron quasiparticle random-phase
approximation (pnQRPA). We include the effects that come from the finite size
of a nucleon, from the higher-order terms of nucleonic weak currents, and from
the nucleon-nucleon short-range correlations. Most importantly, we improve on
the presently available calculations by replacing the rudimentary Jastrow
short-range correlations by the more advanced unitary correlation operator
method (UCOM). The UCOM corrected matrix elements turn out to be notably larger
in magnitude than the Jastrow corrected ones. This has drastic consequences for
the detectability of decay in the present and future double
beta experiments.Comment: 5 pages, 2 figures, to appear in Physical Review C (Rapid
Communication) 200
Acute ischemic stroke in a university hospital intensive care unit : 1-year costs and outcome
Background and purpose Little is currently known about the cost-effectiveness of intensive care of acute ischemic stroke (AIS). We evaluated 1-year costs and outcome for patients with AIS treated in the intensive care unit (ICU). Materials and methods A single-center retrospective study of patients admitted to an academic ICU with AIS between 2003 and 2013. True healthcare expenditure was obtained up to 1 year after admission and adjusted to consumer price index of 2019. Patient outcome was 12-month functional outcome and mortality. We used multivariate logistic regression analysis to identify independent predictors of favorable outcomes and linear regression analysis to assess factors associated with costs. We calculated the effective cost per survivor (ECPS) and effective cost per favorable outcome (ECPFO). Results The study population comprised 154 patients. Reasons for ICU admission were: decreased consciousness level (47%) and need for respiratory support (40%). There were 68 (44%) 1 year survivors, of which 27 (18%) had a favorable outcome. High age (odds ratio [OR] 0.95, 95% confidence interval [CI] 0.91-0.98) and high hospital admission National Institutes of Health Stroke Scale score (OR 0.92, 95% CI 0.87-0.97) were independent predictors of poor outcomes. Increased age had a cost ratio of 0.98 (95% CI 0.97-0.99) per added year. The ECPS and ECPFO were 115,628euro and 291,210euro, respectively. Conclusions Treatment of AIS in the ICU is resource-intense, and in an era predating mechanical thrombectomy the outcome is often poor, suggesting a need for further research into cost-efficacy of ICU care for AIS patients.Peer reviewe
Instabilities in the Nuclear Energy Density Functional
In the field of Energy Density Functionals (EDF) used in nuclear structure
and dynamics, one of the unsolved issues is the stability of the functional.
Numerical issues aside, some EDFs are unstable with respect to particular
perturbations of the nuclear ground-state density. The aim of this contribution
is to raise questions about the origin and nature of these instabilities, the
techniques used to diagnose and prevent them, and the domain of density
functions in which one should expect a nuclear EDF to be stable.Comment: Special issue "Open Problems in Nuclear Structure Theory" of
Jour.Phys.G - accepted. 7 pages, 2 figure
Effectiveness of clinical exome sequencing in adult patients with difficult-to-diagnose neurological disorders
Objectives Clinical diagnostics in adults with hereditary neurological diseases is complicated by clinical and genetic heterogeneity, as well as lifestyle effects. Here, we evaluate the effectiveness of exome sequencing and clinical costs in our difficult-to-diagnose adult patient cohort. Additionally, we expand the phenotypic and genetic spectrum of hereditary neurological disorders in Finland. Methods We performed clinical exome sequencing (CES) to 100 adult patients from Finland with neurological symptoms of suspected genetic cause. The patients were classified as myopathy (n = 57), peripheral neuropathy (n = 16), ataxia (n = 15), spastic paraplegia (n = 4), Parkinsonism (n = 3), and mixed (n = 5). In addition, we gathered the costs of prior diagnostic work-up to retrospectively assess the cost-effectiveness of CES as a first-line diagnostic tool. Results The overall diagnostic yield of CES was 27%. Pathogenic variants were found for 14 patients (in genes ANO5, CHCHD10, CLCN1, DES, DOK7, FKBP14, POLG, PYROXD1, SCN4A, TUBB3, and TTN) and likely pathogenic previously undescribed variants for 13 patients (in genes ABCD1, AFG3L2, ATL1, CACNA1A, COL6A1, DYSF, IRF2BPL, KCNA1, MT-ATP6, SAMD9L, SGCB, and TPM2). Age of onset below 40 years increased the probability of finding a genetic cause. Our cost evaluation of prior diagnostic work-up suggested that early CES would be cost-effective in this patient group, in which diagnostic costs increase linearly with prolonged investigations. Conclusions Based on our results, CES is a cost-effective, powerful first-line diagnostic tool in establishing the molecular diagnosis in adult neurological patients with variable symptoms. Importantly, CES can markedly shorten the diagnostic odysseys of about one third of patients.Peer reviewe
Nuclear DFT electromagnetic moments in heavy deformed open-shell odd nuclei
Within the nuclear DFT approach, we determined the magnetic dipole and electric quadrupole moments for paired nuclear states corresponding to the proton (neutron) quasiparticles blocked in the p11/2-(n13/2+) intruder configurations. We performed calculations for all deformed open-shell odd nuclei with 63<=Z<=82 and 82<=N<=126. Time-reversal symmetry was broken in the intrinsic reference frame and self-consistent shape and spin core polarizations were established. We determined spectroscopic moments of angular-momentum-projected wave functions and compared them with available experimental data. We obtained good agreement with data without using effective g-factors or effective charges in the dipole or quadrupole operators, respectively. We also showed that the intrinsic magnetic dipole moments, or those obtained for conserved intrinsic time-reversal symmetry, do not represent viable approximations of the spectroscopic ones
- …