646 research outputs found
Microscopic HFB+QRPA predictions of dipole strength for astrophysics applications
Large-scale QRPA calculations of the E1 strength are performed on top of HFB
calculations in order to derive the radiative neutron capture cross sections
for the whole nuclear chart. The spreading width of the GDR is taken into
account by analogy with the second-RPA (SRPA) method. The accuracy of HFB+QRPA
model based on various Skyrme forces with different pairing prescription and
parameterization is analyzed. It is shown that the present model allows to
constrain the effective nucleon-nucleon interaction with the GDR data and to
provide quantitative predictions of dipole strengths.Comment: 21 pages, 9 figure
Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. II: Role of the effective mass
We have constructed four new complete mass tables, referred to as HFB-4 to
HFB-7, each one including all the 9200 nuclei lying between the two drip lines
over the range of Z and N>8 and Z<120. HFB-4 and HFB-5 have the isoscalar
effective mass M*_s$ constrained to the value 0.92 M, with the former having a
density-independent pairing, and the latter a density-dependent pairing. HFB-6
and HFB-7 are similar, except that M*_s is constrained to 0.8 M. The rms errors
of the mass-data fits are 0.680, 0.675, 0.686, and 0.676 MeV, respectively,
almost as good as for the HFB-2 mass formula, for which M*_s was unconstrained.
However, as usual, the single-particle spectra depend significantly on M*_s.
This decoupling of the mass fits from the fits to the single-particle spectra
has been achieved only by making the cutoff parameter of the delta-function
pairing force a free parameter. An improved treatment of the center-of-mass
correction was adopted, but although this makes a difference to individual
nuclei it does not reduce the overall rms error of the fit. The extrapolations
of all four new mass formulas out to the drip lines are essentially the same as
for the original HFB-2 mass formula.Comment: 12 pages revtex, 9 eps figures, accepted for publication in Phys.
Rev.
Quantification of Thoracic Aorta Blood Flow by Magnetic Resonance Imaging During Supine Cycling Exercise of Increasing Intensity
Poster presentation from the 16th Annual SCMR Scientific Sessions San Francisco, CA, USA. 31 January - 3 February 2013
Treating a 20 mm Hg Gradient Alleviates Myocardial Hypertrophy in Experimental Aortic Coarctation
Background Children with coarctation of the aorta (CoA) can have a hyperdynamic and remodeled left ventricle (LV) from increased afterload. Literature from an experimental model suggests the putative 20 mm Hg blood pressure gradient (BPG) treatment guideline frequently implemented in CoA studies may permit irreversible vascular changes. LV remodeling from pressure overload has been studied, but data are limited following correction and using a clinically representative BPG. Materials and methods Rabbits underwent CoA at 10 weeks to induce a 20 mm Hg BPG using permanent or dissolvable suture thereby replicating untreated and corrected CoA, respectively. Cardiac function was evaluated at 32 weeks by magnetic resonance imaging using a spoiled cine GRE sequence (TR/TE/FA 8/2.9/20), 14 × 14-cm FOV, and 3-mm slice thickness. Images (20 frames/cycle) were acquired in 6-8 short axis views from the apex to the mitral valve annulus. LV volume, ejection fraction (EF), and mass were quantified. Results LV mass was elevated for CoA (5.2 ± 0.55 g) versus control (3.6 ± 0.16 g) and corrected (4.0 ± 0.44 g) rabbits, resulting in increased LV mass/volume ratio for CoA rabbits. A trend toward increased EF and stroke volume was observed but did not reach significance. Elevated EF by volumetric analysis in CoA rabbits was supported by concomitant increases in total aortic flow by phase-contrast magnetic resonance imaging. Conclusions The indices quantified trended toward a persistent hyperdynamic LV despite correction, but differences were not statistically significant versus control rabbits. These findings suggest the current putative 20 mm Hg BPG for treatment may be reasonable from the LV\u27s perspective
Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. III: Role of particle-number projection
Starting from HFB-6, we have constructed a new mass table, referred to as
HFB-8, including all the 9200 nuclei lying between the two drip lines over the
range of Z and N > 6 and Z < 122. It differs from HFB-6 in that the wave
function is projected on the exact particle number. Like HFB-6, the isoscalar
effective mass is constrained to the value 0.80 M and the pairing is density
independent. The rms errors of the mass-data fit is 0.635 MeV, i.e. better than
almost all our previous HFB mass formulas. The extrapolations of this new mass
formula out to the drip lines do not differ significantly from the previous
HFB-6 mass formula.Comment: 9 pages, 7 figures, accepted for publication in Phys. Rev.
Impurity migration and diffusion during deformation-induced recrystallization of ice
第3回極域科学シンポジウム/第35回極域気水圏シンポジウム 11月29日(木) 国立国語研究所 2階ロビ
Affected by abundant PLTP : the atherogenic role of a lipid transfer protein in transgenic mice
__Abstract__
Atherosclerosis is a progressive disease of the large and medium-sized arteries. The disease
is characterised by endothelial dysfunction, inflammation and the accumulation of fatty
and fibrous substances in the vessel wall, resulting in thickening and loss of elasticity of
the arteries. The word atherosclerosis has been derived from the Greek words "athera",
porridge or gruel, and "skleros", hard or stiff. These words describe the external features
of the lipid-loaded lesions that characterize the disease. Although atherosclerosis has been
discovered in blood vessels of people living more than 3000 years ago, until the end of
the 18th century its prevalence was very rare. During the 20th century, mortality caused
by atherosclerosis strongly increased. Nowadays, complications of atherosclerosis are the
main cause of death in the developed world, and are predicted to be the leading cause of
death worldwide by the year 2020 (Fonarow, 2007).
It is difficult to accurately determine the true frequency of atherosclerosis because it is a
predominantly asymptomatic condition (Kavey et al., 2006). Early atherosclerotic lesions
can already be found in the aorta shortly after birth, increasing in number during childhood.
More advanced lesions begin to develop at an age of approximately 25 years. Generally,
the clinical manifestations of the disease become apparent in the sixth decade of life
Novel Applications of Cardiovascular Magnetic Resonance Imaging-Based Computational Fluid Dynamics Modeling in Pediatric Cardiovascular and Congenital Heart Disease
Cardiovascular diseases (CVDs) afflict many people across the world; thus, understanding the pathophysiology of CVD and the biomechanical forces which influence CVD progression is important in the development of optimal strategies to care for these patients. Over the last two decades, cardiac magnetic resonance (CMR) imaging has offered increasingly important insights into CVD. Computational fluid dynamics (CFD) modeling, a method of simulating the characteristics of flowing fluids, can be applied to the study of CVD through the collaboration of engineers and clinicians. This chapter aims to explore the current state of the CMR-derived CFD, as this technique pertains to both acquired CVD (i.e., atherosclerosis) and congenital heart disease (CHD)
First ice core records of NO3− stable isotopes from Lomonosovfonna, Svalbard
Samples from two ice cores drilled at Lomonosovfonna, Svalbard, covering the period 1957–2009, and 1650–1995, respectively, were analyzed for NO3− concentrations, and NO3− stable isotopes (δ15N and δ18O). Post-1950 δ15N has an average of (−6.9 ± 1.9) ‰, which is lower than the isotopic signal known for Summit, Greenland, but agrees with values observed in recent Svalbard snow and aerosol. Pre-1900 δ15N has an average of (4.2 ± 1.6) ‰ suggesting that natural sources, enriched in the 15 N-isotope, dominated before industrialization. The post-1950 δ18O average of (75.1 ± 4.1) ‰ agrees with data from low and polar latitudes, suggesting similar atmospheric NOy (NOy = NO + NO2 + HNO3) processing pathways. The combination of anthropogenic source δ15N and transport isotope effect was estimated as −29.1 ‰ for the last 60 years. This value is below the usual range of NOx (NOx = NO + NO2) anthropogenic sources which is likely the result of a transport isotope effect of –32 ‰. We suggest that the δ15N recorded at Lomonosovfonna is influenced mainly by fossil fuel combustion, soil emissions and forest fires; the first and second being responsible for the marked decrease in δ15N observed in the post-1950s record with soil emissions being associated to the decreasing trend in δ15N observed up to present time, and the third being responsible for the sharp increase of δ15N around 2000
Including Aortic Valve Morphology in Computational Fluid Dynamics Simulations: Initial Findings and Application to Aortic Coarctation
Computational fluid dynamics (CFD) simulations quantifying thoracic aortic flow patterns have not included disturbances from the aortic valve (AoV). 80% of patients with aortic coarctation (CoA) have a bicuspid aortic valve (BAV) which may cause adverse flow patterns contributing to morbidity. Our objectives were to develop a method to account for the AoV in CFD simulations, and quantify its impact on local hemodynamics. The method developed facilitates segmentation of the AoV, spatiotemporal interpolation of segments, and anatomic positioning of segments at the CFD model inlet. The AoV was included in CFD model examples of a normal (tricuspid AoV) and a post-surgical CoA patient (BAV). Velocity, turbulent kinetic energy (TKE), time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) results were compared to equivalent simulations using a plug inlet profile. The plug inlet greatly underestimated TKE for both examples. TAWSS differences extended throughout the thoracic aorta for the CoA BAV, but were limited to the arch for the normal example. OSI differences existed mainly in the ascending aorta for both cases. The impact of AoV can now be included with CFD simulations to identify regions of deleterious hemodynamics thereby advancing simulations of the thoracic aorta one step closer to reality
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