41 research outputs found
Proton and Neutron Pairing Properties within a mixed volume-surface pairing force using SKI3-HFB Theory
This work aims at a systematic investigations of the pairing properties and
Fermi properties from the proton drip-line to the neutron drip-line. In order
to provide more accurate mass formula with skyrme SKI3 force, the global
descriptive power of the SKI3-HFB model for pairing properties are made in this
study. Systematic Skyrme SKI3-Hartree-Fock-Bogoliubov calculations with a mixed
volume-surface pairing force are carried out to study the ground-state neutron
and proton pairing gap, neutron and proton pairing energy and neutron and
proton Fermi energy for about 2095 even-even nuclei ranging from to . The calculated results of neutron and proton pairing gap
are compared with experimental data using the difference-point formulas
and , and also compared with the
neutron and proton pairing gap of Lipkin-Nogami model. It is shown that the
Skyrme-SKI3 functional with the mixed volume-surface pairing force can be
successfully used for describing the ground-state pairing and Fermi properties
of the investigated nuclei, in particularly the neutron-rich nuclei and the
exotic nuclei near the neutron drip-line. On the other hand, the calculated
neutron and proton pairing gap are in good agreement with the available
experimental values of the neutron and proton pairing gap of the
difference-point formulas and and
with the data of Lipkin-Nogami model over the whole nuclear chart.Comment: 18 pages, 9 figure
Random Phase Approximation with High Orbits Configuration for the Low Lying Negative Parity, T = 0 States in 16O
Particle-Particle Collective Excitations of Sn isotopes
In this paper, energy-level schemes and reduced electric transition strengths of neutron-rich Tin isotopes 102, 110, 116, 120, 122Sn (Z=50) are studied using collective models, that is, particle-particle Tamm-Dancoff Approximation and particle-particle Random Phase Approximation. According to these models, the excited states of closed-core A+2 systems with multipolarity J and isospin T can be described as a linear combination of particle-particle pairs. In our investigation, the low-lying states of the investigated isotopes 102, 110, 116, 120, 122Sn are described by acting two-particle operators on a correlated core 100Sn, 108Sn, 114Sn, 118Sn, and 120Sn, respectively. The Hamiltonian is diagonalized within the model space include {1g7/2, 2d5/2, 2d3/2, 3s1/2 and 1h11/2} orbits, using the matrix elements of neutron-neutron interaction and modified surface delta interaction. The calculated values are checked by using the resultant eigenvalues and eigenvectors to calculate the excitation energies and reduced electric transition strengths. Our calculated results are compared to the available experimental data, and these comparisons led to reasonable agreements. Effective charges are also used to account for the core polarization effect
Estimating the natural and artificial radioactivity in soil samples from some oil sites in Kirkuk-Iraq using high resolution gamma rays spectrometry
The natural and artificial radioactivity in soil samples from some oil sites of Kirkuk-Iraq have been estimated using a gamma spectrometry based on a high purity germanium (HPGe) detector. For this reason, soil samples have been collected from four sites; Henjera, Jabel Boor, Jambor and Qutan. It was found that the specific activity ranged from 7.31 to 63.33 Bq kg−1 for 226Ra, from 3.54 to 42.95 Bq kg−1 for 232Th, from 103.21 to 798.52 Bq kg−1 for 40K and from 0.7 to 9.53 Bq kg−1 for 137Cs. The results have been compared with the worldwide average values. The radium equivalent activity (Raeq), the absorbed gamma dose rate (D), the annual effective dose rate (AEDE), the external hazard (Hex), the internal hazard (Hin) and Gamma radiation representative level Index (Iγ) have also been calculated. The Raeq was 92.173 Bq kg−1, the D was 45.53 nGyh-1, the AEDE outdoor and indoor were 0.0959 and 0.224, respectively, the Hex was 0.242, the Hin was 0.329, and Iγ was 0.680. It has been concluded that no harmful radiation effects have posed to the population who live in the study area. Although, there are some areas where radiation effects have resulted higher than that of the international allowable radiation values
Ground and transition properties of 40Ca and 48Ca nuclei
Properties of the ground states and transitions in 40Ca and 48Ca nuclei are studied using the self-consistent Hartree - Fock and random phase approximation calculations with Skyrme-type interactions: KDE0, SLy4, LNS, RAPT and T6. The purpose of the paper is to obtain the best Skyrme-force parameterizations for description of the experimental data. All the calculated values were compared with the available data. The calculated binding energy per nucleon, charge root mean square, ground charge density distribution and transition strength distribution agree very well with the experimental data. The overall behavior of the calculated transition densities demonstrated the reliability of the method
Isoscalar Giant Octupole Resonance ISGOR of 116Cd using Self-Consistent Skyrme QRPA
Collective models based on the random phase approximation (RPA) are widely used to accurately depict collective modes of response. They can quickly calculate the strength function for the entire nuclear mass range. The quasi-particle random phase approximation (QRPA), which considers the pairing effect, is an enhanced RPA model. It is anticipated that this effect will be significant for open-shell nuclei. In this work, the self-consistent Skyrme Hartree-Fock-Bardeen, Cooper, and Schrieffer (HF-BCS) and QRPA models have been used to study the isoscalar giant octupole resonance (ISGOR) in the 116Cd isotope. Ten Skyrme-type parameters are utilized in the computations since they may be identified by different values of the incompressibility modulus KMN in nuclear matter. The calculated strength distributions and centroid energy are compared with available experimental data. We saw that the strength distributions varied depending on the type of Skyrme-interaction, and we also observed a definite impact of the KNM values on the centroid energy
Hole-Hole Collective Excitations in 106, 112, 130Sn Isotopes
In this paper, energy-level schemes of neutron rich and reduced electric transition strengths of Tin isotopes 106Sn, 112Sn and 130Sn were studied using collective models, i.e., hole-hole Tamm-Dancoff Approximation (hh TDA) and hole-hole Random Phase Approximation (hh RPA). According to these models, the excited states of closed core A-2 systems with multipolarity J and isospin T can be described as a linear combination of hole-hole (hh) pairs. Therefore, in our approach, the low-lying states of the investigated isotopes 106Sn, 112Sn and 130Sn are obtained by acting two-hole operators on a correlated core 108Sn, 114Sn and 132Sn, respectively. The Hamiltonian is diagonalized within the model space include {1g7/2, 2d5/2, 2d3/2, 3s1/2 and 1h11/2} orbits, using the matrix elements of neutron-neutron (N-N) interaction and modified surface delta interaction (MSDI). The hh TDA and hh RPA are checked by using the resultant eigenvalues and eigenvectors to calculate the excitation energies and reduced electric transition strengths. A comparison had been made between our theoretical predictions and the recent available experimental data. Reasonable agreements were obtained from these comparisons
Interhospital Transfer Before Thrombectomy Is Associated With Delayed Treatment and Worse Outcome in the STRATIS Registry (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke).
BACKGROUND: Endovascular treatment with mechanical thrombectomy (MT) is beneficial for patients with acute stroke suffering a large-vessel occlusion, although treatment efficacy is highly time-dependent. We hypothesized that interhospital transfer to endovascular-capable centers would result in treatment delays and worse clinical outcomes compared with direct presentation.
METHODS: STRATIS (Systematic Evaluation of Patients Treated With Neurothrombectomy Devices for Acute Ischemic Stroke) was a prospective, multicenter, observational, single-arm study of real-world MT for acute stroke because of anterior-circulation large-vessel occlusion performed at 55 sites over 2 years, including 1000 patients with severe stroke and treated within 8 hours. Patients underwent MT with or without intravenous tissue plasminogen activator and were admitted to endovascular-capable centers via either interhospital transfer or direct presentation. The primary clinical outcome was functional independence (modified Rankin Score 0-2) at 90 days. We assessed (1) real-world time metrics of stroke care delivery, (2) outcome differences between direct and transfer patients undergoing MT, and (3) the potential impact of local hospital bypass.
RESULTS: A total of 984 patients were analyzed. Median onset-to-revascularization time was 202.0 minutes for direct versus 311.5 minutes for transfer patients (
CONCLUSIONS: In this large, real-world study, interhospital transfer was associated with significant treatment delays and lower chance of good outcome. Strategies to facilitate more rapid identification of large-vessel occlusion and direct routing to endovascular-capable centers for patients with severe stroke may improve outcomes.
CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02239640
Geoeconomic variations in epidemiology, ventilation management, and outcomes in invasively ventilated intensive care unit patients without acute respiratory distress syndrome: a pooled analysis of four observational studies
Background: Geoeconomic variations in epidemiology, the practice of ventilation, and outcome in invasively ventilated intensive care unit (ICU) patients without acute respiratory distress syndrome (ARDS) remain unexplored. In this analysis we aim to address these gaps using individual patient data of four large observational studies. Methods: In this pooled analysis we harmonised individual patient data from the ERICC, LUNG SAFE, PRoVENT, and PRoVENT-iMiC prospective observational studies, which were conducted from June, 2011, to December, 2018, in 534 ICUs in 54 countries. We used the 2016 World Bank classification to define two geoeconomic regions: middle-income countries (MICs) and high-income countries (HICs). ARDS was defined according to the Berlin criteria. Descriptive statistics were used to compare patients in MICs versus HICs. The primary outcome was the use of low tidal volume ventilation (LTVV) for the first 3 days of mechanical ventilation. Secondary outcomes were key ventilation parameters (tidal volume size, positive end-expiratory pressure, fraction of inspired oxygen, peak pressure, plateau pressure, driving pressure, and respiratory rate), patient characteristics, the risk for and actual development of acute respiratory distress syndrome after the first day of ventilation, duration of ventilation, ICU length of stay, and ICU mortality. Findings: Of the 7608 patients included in the original studies, this analysis included 3852 patients without ARDS, of whom 2345 were from MICs and 1507 were from HICs. Patients in MICs were younger, shorter and with a slightly lower body-mass index, more often had diabetes and active cancer, but less often chronic obstructive pulmonary disease and heart failure than patients from HICs. Sequential organ failure assessment scores were similar in MICs and HICs. Use of LTVV in MICs and HICs was comparable (42\ub74% vs 44\ub72%; absolute difference \u20131\ub769 [\u20139\ub758 to 6\ub711] p=0\ub767; data available in 3174 [82%] of 3852 patients). The median applied positive end expiratory pressure was lower in MICs than in HICs (5 [IQR 5\u20138] vs 6 [5\u20138] cm H2O; p=0\ub70011). ICU mortality was higher in MICs than in HICs (30\ub75% vs 19\ub79%; p=0\ub70004; adjusted effect 16\ub741% [95% CI 9\ub752\u201323\ub752]; p<0\ub70001) and was inversely associated with gross domestic product (adjusted odds ratio for a US$10 000 increase per capita 0\ub780 [95% CI 0\ub775\u20130\ub786]; p<0\ub70001). Interpretation: Despite similar disease severity and ventilation management, ICU mortality in patients without ARDS is higher in MICs than in HICs, with a strong association with country-level economic status. Funding: No funding