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

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.

Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. IX: Constraint of pairing force to 1S0^1S_0 neutron-matter gap

In this latest of our series of Skyrme-HFB mass models, HFB-16, we introduce the new feature of requiring that the contact pairing force reproduce at each density the $^1S_0$ pairing gap of neutron matter as determined in microscopic calculations with realistic nucleon-nucleon forces. We retain the earlier constraints on the Skyrme force of reproducing the energy-density curve of neutron matter, and of having an isoscalar effective mass of $0.8M$ in symmetric infinite nuclear matter at the saturation density; we also keep the recently adopted device of dropping Coulomb exchange. Furthermore, the correction term for the spurious energy of collective motion has a form that is known to favour fission barriers that are in good agreement with experiment. Despite the extra constraints on the effective force, we have achieved a better fit to the mass data than any other mean field model, the rms error on the 2149 measured masses of nuclei with $N$ and $Z \ge$ 8 having been reduced to 0.632 MeV; the improvement is particularly striking for the most neutron-rich nuclei. Moreover, it turns out that even with no flexibility at all remaining for the pairing force, the spectral pairing gaps that we find suggest that level densities in good agreement with experiment should be obtained. This new force is thus particularly well-suited for astrophysical applications, such as stellar nucleosynthesis and neutron-star crusts.Comment: 38 pages, 9 figures accepted for publication in Nuclear Physics

Micro-deformation of the NEEM ice core: implications for stratigraphic interpretation

第2回極域科学シンポジウム　氷床コアセッション 11月16日（水） 国立極地研究所 2階大会議

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

Nuclear energy density functional from chiral pion-nucleon dynamics: Isovector terms

We extend a recent calculation of the nuclear energy density functional in the framework of chiral perturbation theory by computing the isovector surface and spin-orbit terms: (\vec \nabla \rho_p- \vec \nabla \rho_n)^2 G_d(\rho)+ (\vec \nabla \rho_p- \vec \nabla \rho_n)\cdot(\vec J_p-\vec J_n) G_{so(\rho)+(\vec J_p-\vec J_n)^2 G_J(\rho) pertaining to different proton and neutron densities. Our calculation treats systematically the effects from $1\pi$-exchange, iterated $1\pi$-exchange, and irreducible $2\pi$-exchange with intermediate $\Delta$-isobar excitations, including Pauli-blocking corrections up to three-loop order. Using an improved density-matrix expansion, we obtain results for the strength functions $G_d(\rho)$, $G_{so}(\rho)$ and $G_J(\rho)$ which are considerably larger than those of phenomenological Skyrme forces. These (parameter-free) predictions for the strength of the isovector surface and spin-orbit terms as provided by the long-range pion-exchange dynamics in the nuclear medium should be examined in nuclear structure calculations at large neutron excess.Comment: 12 pages, 5 figure

Recrystallization studies from deformation experiments on artificial and natural ice: experimental set-up and preliminary results

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

Self-consistent calculations within the Extended Theory of Finite Fermi Systems

The Extended Theory of Finite Fermi Systems(ETFFS) describes nuclear excitations considering phonons and pairing degrees of freedom, using experimental single particle energies and the effective Landau-Migdal interaction. Here we use the Skyrme interactions in order to extend the range of applicability of the ETFFS to experimentally not yet investigated short-lived isotopes. We find that Skyrme interactions which reproduce at the mean field level both ground state properties and nuclear excitations are able to describe the spreading widths of the giant resonances in the new approach, but produce shifts of the centroid energies. A renormalization of the Skyrme interactions is required for approaches going beyond the mean field level.Comment: 7 pages, 5 figures, corrected typo

Low-energy dipole excitations towards the proton drip-line: doubly magic 48Ni

The properties of the low-energy dipole response are investigated for the proton-rich doubly magic nucleus $^{48}$Ni, in a comparative study of two microscopic models: fully self-consistent Relativistic Random-Phase Approximation(RRPA) based on the novel density-dependent meson-exchange interactions, and Continuum Random-Phase Approximation(CRPA) using Skyrme-type interactions with the continuum properly included. Both models predict the existence of the low-energy soft mode, i.e. the proton pygmy dipole resonance (PDR), for which the transition densities and RPA amplitudes indicate the dynamics of loosely bound protons vibrating against the rest of the nucleons. The CRPA analysis indicates that the escape width for the proton PDR is rather large, as a result of the coupling to the continuum.Comment: 12 pages, 3 figures, accepted for publication in Phys. Lett.

First Experiences with the New Law on DUID in Belgium: Alcohol and Medicines in Drug Negative Cases

Abstract In March 1999 a new law prohibiting driving while impaired by illegal drugs was introduced in Belgium. The legal procedure consists of a) a field impairment test, b) a urine immunoassay for 4 drug groups and c) ultimate proof by plasma analysis (GC-MS with fixed cut-offs). Over about two years the analysis of 896 blood samples revealed the presence of illicit drug(s) above cut-off in 85% of the cases. For the 15% &quot;false positives&quot; (failed impairment test and positive urine assay without confirmation in plasma) we investigated the possible reasons for impaired behavior. The presence of alcohol and psychoactive medication stands for an important number of our &apos;false positives&apos;. The results adduce arguments for introducing psychotropic medicines in our traffic law. Our findings further suggest that false positive cases can be reduced by minimizing the delay before blood sampling and optimizing sample preservation. Harmonization of the strategy for detection and penalization of impaired drivers (alcohol and/or drugs) is highly recommended. Introduction In March 1999 a new law on driving under the influence of illegal drugs was introduced in Belgium. The legal procedure is a three-step process: a) a field impairment test, i.e. the assessment of external signs of the presence of drugs by a standardized test battery, b) an onsite immunoassay for amphetamines, cannabinoids, cocaine metabolites or opiates in urine and c) blood sampling for plasma GC/MS analysis with the following analytical cut-offs: THC (tetrahydrocannabinol) 2 ng/mL, free morphine 20 ng/mL, amphetamine, MDMA (ecstasy), MDEA, MBDB, benzoylecgonine (BE) or cocaine 50 ng/mL. The urine test resp. the plasma analysis are performed on the condition that the driver fails the preceding test(s) (1,2). In 2000-2001 the analysis of 896 blood samples revealed the presence of one or more illicit drug(s) above cut-off in 85% of the cases (2). We investigated the 15% &apos;false positives&apos;, i.e. cases where the driver failed the field impairment test and the urine immunoassay test was positive for at least one drug group, but where the plasma GC-MS analysis revealed no prohibited drug above cut-off. In such cases the full legal procedure for driving under the influence of illicit drugs was completed but the driver was not fined or penalized