1,513 research outputs found
Time-resolved spectroscopic measurements behind incident and reflected shock waves in air and xenon
Time-resolved spectra have been obtained behind incident and reflected shock waves in air and xenon at initial pressures of 0.1 and 1.0 torr using a rotating drum spectrograph and the OSU (The Ohio State University) arc-driven shock tube. These spectra were used to determine the qualitative nature of the flow as well as for making estimates of the available test time. The (n+1,n) and (n,n) band spectra of N2(+) (1st negative) were observed in the test gas behind incident shock waves in air at p1=1.0 torr and Us=9-10 km/sec. Behind reflected shock waves in air, the continuum of spectra appeared to cover almost the entire wavelength of 2,500-7,000 A for the shock-heated test gas. For xenon, the spectra for the incident shock wave cases for p1=0.1 torr show an interesting structure in which two intensely bright regions are witnessed in the time direction. The spectra obtained behind reflected shock waves in xenon were also dominated by continuum radiation but included strong absorption spectra due to FeI and FeII from the moment the reflected shock passed and on
Exponents of 2-multiarrangements and multiplicity lattices
We introduce a concept of multiplicity lattices of 2-multiarrangements,
determine the combinatorics and geometry of that lattice, and give a criterion
and method to construct a basis for derivation modules effectively.Comment: 14 page
Properties of hadron and quark matter studied with a molecular dynamics
We study the hadron-quark phase transition in a molecular dynamics (MD) of
quark degrees of freedom. The hadron state at low density and temperature, and
the deconfined quark state at high density and temperature are observed in our
model. We investigate the equations of state and draw the phase-diagram at wide
baryon density and temperature range. We also discuss the transport property,
e.g. viscosity, of matter. It is found that the ratio of the shear
viscosity to the entropy density is less than one for quark matter.Comment: Poster presentation at Quark Matter 200
{1122} <1123> Slip System in Magnesium
The slip mode operative in the c-axis compression of magnesium was examined using precisely-oriented single crystals. From recorded stress-strain curves and observations with light and transmission electron microscopes, it was found that (1) the {1122} slip system operates at all temperatures investigated (from room temperature to 500℃), (2) the work hardening rate of this slip system is very high especially below 200℃, (3) the Burgers vector of the dislocation for the slip system is 1/3 , and (4) the dislocation has a strong preference to lie along a basal plane, which means that the edge dislocation is much less mobile than the screw dislocation. The ductility of polycrystalline magnesium is discussed from above observations
Swimming depth of migrating silver eels Anguilla japonica released at seamounts of the West Mariana Ridge, their estimated spawning sites
Five hormone-treated female Japanese silver eels Anguilla japonica were tagged with ultrasonic transmitters and released by submersible in the West Pacific at seamounts of the West Mariana Ridge, their supposed spawning grounds. Four eels were tracked for 60 to 423 min in the vicinity of the seamounts. They did not settle at the seamounts but swam at a mean speed of 0.37 m s-1 into open water above deep ground. Their mean swimming depth ranged from 81 to 172 m. Experiments suggest that pre-matured A. japonica migrate to their spawning grounds in temperate warm water and at shallow depths
Chamber basis of the Orlik-Solomon algebra and Aomoto complex
We introduce a basis of the Orlik-Solomon algebra labeled by chambers, so
called chamber basis. We consider structure constants of the Orlik-Solomon
algebra with respect to the chamber basis and prove that these structure
constants recover D. Cohen's minimal complex from the Aomoto complex.Comment: 16 page
Dynamics of orbital degrees of freedom probed via isotope Sb nuclear quadrupole moments in Sb-substituted iron-pnictide superconductors
Isotope Sb nuclei with large electric quadrupole moments are
applied to investigate the dynamics of orbital degrees of freedom in
Sb-substituted iron(Fe)-based compounds. In the parent compound
LaFe(AsSb)O, the nuclear spin relaxation rate
at Sb sites was enhanced at structural
transition temperature ( 135 K), which is higher than N\'eel
temperature (125 K). The isotope ratio
indicates that the electric quadrupole
relaxation due to the dynamical electric field gradient at Sb site increases
significantly toward . It is attributed to the critically enhanced
nematic fluctuations of stripe-type arrangement of Fe- (or )
orbitals. In the lightly electron-doped superconducting (SC) compound
LaFe(AsSb)(OF), the nematic fluctuations are
largely suppressed in comparison with the case of the parent compound, however,
it remains a small enhancement below 80 K down to the ( 20 K). The
results indicate that the fluctuations from both the spin and orbital degrees
of freedom on the (or ) orbitals can be seen in lightly
electron-doped SC state of LaFeAsO-based compounds. We emphasize that isotope
Sb quadrupole moments are sensitive local probe to identify the
dynamics of orbital degrees of freedom in Fe-pnictides, which provides with a
new opportunity to discuss the microscopic correlation between the
superconductivity and both nematic and spin fluctuations simultaneously even in
the polycrystalline samples.Comment: 7 pages, 4 figures and 1 supplemental fil
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