93,501 research outputs found
NLTE study of scandium in the Sun
We investigate the formation of neutral and singly ionized scandium lines in
the solar photospheres. The research is aimed derive solar (Sc) values for scandium lines, which will later be used in
differential abundance analyses of metal-poor stars. Extensive statistical
equilibrium calculations were carried out for a model atom, which comprises 92
terms for \ion{Sc}{i} and 79 for \ion{Sc}{ii}. Photoionization cross-sections
are assumed to be hydrogenic. Synthetic line profiles calculated from the level
populations according to the NLTE departure coefficients were compared with the
observed solar spectral atlas. Hyperfine structure (HFS) broadening is taken
into account. The statistical equilibrium of scandium is dominated by a strong
underpopulation of \ion{Sc}{i} caused by missing strong lines. It is nearly
unaffected by the variation in interaction parameters and only marginally
sensitive to the choice of the solar atmospheric model. Abundance
determinations using the ODF model lead to a solar Sc abundance of between
and 3.13, depending on the choice of values.
The long known difference between photospheric and meteoritic scandium
abundances is confirmed for the experimental -values.Comment: 10 pages, 6 figures, A&A accepte
Groundstate with Zero Eigenvalue for Generalized Sombrero-shaped Potential in -dimensional Space
Based on an iterative method for solving the goundstate of Schroedinger
equation, it is found that a kind of generalized Sombrero-shaped potentials in
N-dimensional space has groundstates with zero eigenvalue. The restrictions on
the parameters in the potential are discussed.Comment: 8 pages, 3 figure
Correction of the definition of mass-flow parameter in dynamic inflow modelling
No abstract available
Averages of shifted convolutions of
We investigate the first and second moments of shifted convolutions of the
generalised divisor function .Comment: 22 page
Dynamics of spin transport in voltage-biased Josephson junctions
We investigate spin transport in voltage-biased spin-active Josephson
junctions. The interplay of spin filtering, spin mixing, and multiple Andreev
reflection leads to nonlinear voltage dependence of the dc and ac spin current.
We compute the voltage characteristics of the spin current (I_S) for
superconductor-ferromagnet-superconductor (SFS) Josephson junctions. The
sub-harmonic gap structure of I_S(V) is shown to be sensitive to the degree of
spin mixing generated by the ferromagnetic interface, and exhibits a pronounced
even-odd effect associated with spin transport during multiple Andreev
reflection processes. For strong spin mixing both the magnitude and the
direction of the dc spin current can be sensitively controlled by the bias
voltage.Comment: 4 pages, 3 figure
Dynamic Fracturing Simulation of Brittle Material using the Distinct Lattice Spring Method with a Full Rate-Dependent Cohesive Law
A full rate-dependent cohesive law is implemented in the distinct lattice spring method (DLSM) to investigate the dynamic fracturing behavior of brittle materials. Both the spring ultimate deformation and spring strength are dependent on the spring deformation rate. From the simulation results, it is found that the dynamic crack propagation velocity can be well predicted by the DLSM through the implemented full rate-dependent cohesive law. Furthermore, a numerical investigation on dynamic branching is also conducted by using the DLSM cod
Oxygen Isotope Effect on the Spin State Transition in (PrSm)CaCoO
Oxygen isotope substitution is performed in the perovskite cobalt oxide
(PrSm)CaCoO which shows a sharp spin
state transition from the intermediate spin (IS) state to the low spin (LS)
state at a certain temperature. The transition temperature of the spin state
up-shifts with the substitution of by O from the resistivity
and magnetic susceptibility measurements. The up-shift value is 6.8 K and an
oxygen isotope exponent () is about -0.8. The large oxygen isotope
effect indicates strong electron-phonon coupling in this material. The
substitution of O by O leads to a decrease in the frequency of
phonon and an increase in the effective mass of electron (), so that
the bandwidth W is decreased and the energy difference between the different
spin states is increased. This is the reason why the is shifted to high
temperature with oxygen isotopic exchange.Comment: 4 pages, 3 figure
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