3,200 research outputs found
VLBI Observations of Water Masers in the Circumstellar Envelope of IRC+60169
Water masers around an AGB star, IRC+60169, were observed at four epochs
using the Japanese VLBI networks. The distribution of the maser features is
limited in a thick-shell region, which has inner and outer expansion velocities
of 7 km/s and 14 km/s at radii of 25 mas and 120 mas, respectively. The
distribution of the red-shifted features exhibits a ring-like structure, the
diameter of which is 30 mas, and corresponds to the inner radius of the maser
shell. This implies that dense gas around the star obscures red-shifted
emission. Although a position--radial velocity diagram for the maser features
is consistent with a spherical shell model, the relative proper motions do not
indicate an expansion motion of the shell. A remarkable property has been found
that is a possible periodic change of the alignment pattern of water maser
spots.Comment: 9 pages including 7 figures, to appear in PASJ, Vol. 54, No.
Real-time simulation of jet engines with digital computer. 1: Fabrication and characteristics of the simulator
The fabrication and performance of a real time jet engine simulator using a digital computer are discussed. The use of the simulator in developing the components and control system of a jet engine is described. Comparison of data from jet engine simulation tests with actual engine tests was conducted with good agreement
Efficient implementation of the nonequilibrium Green function method for electronic transport calculations
An efficient implementation of the nonequilibrium Green function (NEGF)
method combined with the density functional theory (DFT) using localized
pseudo-atomic orbitals (PAOs) is presented for electronic transport
calculations of a system connected with two leads under a finite bias voltage.
In the implementation, accurate and efficient methods are developed especially
for evaluation of the density matrix and treatment of boundaries between the
scattering region and the leads. Equilibrium and nonequilibrium contributions
in the density matrix are evaluated with very high precision by a contour
integration with a continued fraction representation of the Fermi-Dirac
function and by a simple quadratureon the real axis with a small imaginary
part, respectively. The Hartree potential is computed efficiently by a
combination of the two dimensional fast Fourier transform (FFT) and a finite
difference method, and the charge density near the boundaries is constructed
with a careful treatment to avoid the spurious scattering at the boundaries.
The efficiency of the implementation is demonstrated by rapid convergence
properties of the density matrix. In addition, as an illustration, our method
is applied for zigzag graphene nanoribbons, a Fe/MgO/Fe tunneling junction, and
a LaMnOSrMnO superlattice, demonstrating its applicability to a wide
variety of systems.Comment: 20 pages, 11 figure
Type-1.5 Superconductors
We demonstrate the existence of a novel superconducting state in high quality
two-component MgB2 single crystalline superconductors where a unique
combination of both type-1 (kappa_1 0.707)
superconductor conditions is realized for the two components of the order
parameter. This condition leads to a vortex-vortex interaction attractive at
long distances and repulsive at short distances, which stabilizes
unconventional stripe- and gossamer-like vortex patterns that we have
visualized in this type-1.5 superconductor using Bitter decoration and also
reproduced in numerical simulations.Comment: accepted in Phys. Rev. Let
Static and Dynamic Phases for Vortex Matter with Attractive Interactions
Exotic vortex states with long range attraction and short range repulsion
have recently been proposed to arise in superconducting hybrid structures and
multi-band superconductors. Using large scale simulations we examine the static
and dynamic properties of such vortex states interacting with random and
periodic pinning. In the absence of pinning this system does not form patterns
but instead completely phase separates. When pinning is present there is a
transition from inhomogeneous to homogeneous vortex configurations similar to a
wetting phenomenon. Under an applied drive, a dynamical dewetting process can
occur from a strongly pinned homogeneous state into pattern forming states. We
show that a signature of the exotic vortex interactions under transport
measurements is a robust double peak feature in the differential conductivity
curves.Comment: 5 pages, 4 postscript figure
High energy electrons beyond 100 GEV observed by emulsion chamber
Much efforts have been expended to observe the spectrum of electrons in the high energy region with large area emulsion chambers exposed at balloon altitudes, and now 15 electrons beyond 1 TeV have been observed. The observed integral flux at 1 TeV is (3.24 + or - 0.87)x10(-5)/sq m sec sr. The statistics of the data around a few hundred GeV are also improving by using new shower detecting films of high sensitivity. The astrophysical significance of the observed spectrum are discussed for the propagation of electrons based on the leaky box and the nested leaky box model
Quasi-Particle Spectra, Charge-Density-Wave, Superconductivity and Electron-Phonon Coupling in 2H-NbSe2
High-resolution photoemission has been used to study the electronic structure
of the charge density wave (CDW) and superconducting (SC) dichalcogenide, 2H-
NbSe2. From the extracted self-energies, important components of the
quasiparticle (QP) interactions have been identified. In contrast to previously
studied TaSe2, the CDW transition does not affect the electronic properties
significantly. The electron-phonon coupling is identified as a dominant
contribution to the QP self-energy and is shown to be very anisotropic
(k-dependent) and much stronger than in TaSe2.Comment: 4 pages, 3 figures, minor changes, to appear in PR
Lessons From The Molecular Biology Of Neonatal Hyperbilirubinaemia.
Neonatal jaundice is the most common condition requiring medical attention in the newborn period. It has been classically attributed to a number of more or less common causes. The causes are classically divided in two main groups. The first group is comprising of conditions
associated with an increase in break down of red blood cells such as Rhesus incompatibility, ABO blood group incompatibility, G6PD deficiency, birth trauma and polycythaemia. A second group consists of conditions in which the excretion of bilirubin is diminished such as
breast feeding jaundice, breast milk jaundice, Gilbert syndrome or the more severe Crigler Najjar syndrome.
Many babies however get jaundice
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