9,479 research outputs found
Pulse-Wave Analysis of Optic Nerve Head Circulation Is Significantly Correlated with Kidney Function in Patients with and without Chronic Kidney Disease
Aim. To determine whether there is a significant correlation between the optic nerve head (ONH) circulation determined by laser speckle flowgraphy (LSFG) and kidney function.
Materials. Seventy-one subjects were investigated. The estimated glomerular filtration rate (GFR) and serum creatinine, cystatin C, and urinary albumin excretion were measured. The ONH circulation was determined by an analysis of the pulse wave of LSFG, and this parameter was named blowout time (BOT). Chronic kidney disease (CKD) was defined to be present when the estimated GFR was <60 mL/min per 1.73 m2. Pearson’s correlation coefficients were used to determine the relationship between the BOT and the kidney function. We also examined whether there were significant differences in all parameters in patients with and without CKD. Results. BOT was significantly correlated with the level of creatinine (r=-0.24, P=0.04), the estimated GFR (r=0.42, P=0.0003), cystatin C (r=-0.29, P=0.01), and urinary albumin excretion (r=-0.29, P=0.01). The BOT level in subjects with CKD was significantly lower than that in subjects without CKD (P=0.002). Conclusion. BOT in ONH by LSFG can detect the organ damage such as kidney dysfunction, CKD
Neutrino afterglow from Gamma-Ray Bursts: ~10^{18} eV
We show that a significant fraction of the energy of a gamma-ray burst(GRB)
is probably converted to a burst of 10^{17}-10^{19} eV neutrinos and multiple
GeV gammas that follow the GRB by > 10 s . If, as previously suggested, GRB's
accelerate protons to ~10^{20} eV, then both the neutrinos and the gammas may
be detectable.Comment: Accepted ApJ; added sentence re: sterile neutrinos; related material
at http://www.sns.ias.edu/~jn
Effective reduction of magnetisation losses in copper-plated multifilament coated conductors using spiral geometry
We wound copper-plated multifilament coated conductors spirally on a round core to decouple filaments electromagnetically under ac transverse magnetic fields and measured their magnetisation losses. Although the coated conductors were plated with copper, which connects all filaments electrically and allows current sharing among them, the spiral geometry decoupled filaments similar to the twist geometry, and the magnetisation loss was reduced effectively by the multifilament structure. The measured magnetisation loss of a 4 mm wide, 10-filament coated conductor with a 20 μm thick copper wound spirally on a 3 mm core was only 7% of that of the same 10-filament coated conductor with a straight shape under an ac transverse magnetic field with an amplitude and frequency of 100 mT and 65.44 Hz, respectively. We separated the measured magnetisation losses into hysteresis and coupling losses and discussed the influence of filament width, copper thickness, and core diameter on both losses. We compared the hysteresis losses with the analytical values given by Brandt and Indenbom and compared the coupling losses with the values calculated using a general expression of coupling loss with the coupling time constants and geometry factors
Phase relations of Earth’s core-forming materials
Recent updates on phase relations of Earth’s core-forming materials, Fe alloys, as a function of pressure (P), temperature (T), and composition (X) are reviewed for the Fe, Fe-Ni, Fe-O, Fe-Si, Fe-S, Fe-C, Fe-H, Fe-Ni-Si, and Fe-Si-O systems. Thermodynamic models for these systems are highlighted where available, starting with 1 bar to high-P-T conditions. For the Fe and binary systems, the longitudinal wave velocity and density of liquid alloys are discussed and compared with the seismological observations on Earth’s outer core. This review may serve as a guide for future research on the planetary cores
Ultrafast spin-to-charge conversions of antiferromagnetic (111)-oriented -
Antiferromagnetic - combines outstanding
spin-transport properties with magnons in the terahertz (THz) frequency range.
However, the THz radiation emitted by ultrafast spin-to-charge conversion via
the inverse spin Hall effect remains unexplored. In this study, we measured the
THz emission and transmission of a permalloy/(111)-oriented
- multilayer by THz time-domain spectroscopy.
The spin Hall angle was determined to be approximately constant at 0.024 within
a frequency range of 0.3-2.2 THz, in comparison with the THz spectroscopy of a
permalloy/Pt multilayer. Our results not only demonstrate the potential of
- as a spintronic THz emitter but also provide
insights into the THz spin transport properties of
-.Comment: 11 pages, 5 figure
Magnetic Field Tomography in Nearby Galaxies with the Square Kilometre Array
Magnetic fields play an important role in shaping the structure and evolution
of the interstellar medium (ISM) of galaxies, but the details of this
relationship remain unclear. With SKA1, the 3D structure of galactic magnetic
fields and its connection to star formation will be revealed. A highly
sensitive probe of the internal structure of the magnetoionized ISM is the
partial depolarization of synchrotron radiation from inside the volume.
Different configurations of magnetic field and ionized gas within the
resolution element of the telescope lead to frequency-dependent changes in the
observed degree of polarization. The results of spectro-polarimetric
observations are tied to physical structure in the ISM through comparison with
detailed modeling, supplemented with the use of new analysis techniques that
are being actively developed and studied within the community such as Rotation
Measure Synthesis. The SKA will enable this field to come into its own and
begin the study of the detailed structure of the magnetized ISM in a sample of
nearby galaxies, thanks to its extraordinary wideband capabilities coupled with
the combination of excellent surface brightness sensitivity and angular
resolution.Comment: 11 pages, 1 figure; to appear as part of 'Cosmic Magnetism' in
Proceedings 'Advancing Astrophysics with the SKA (AASKA14)', PoS(AASKA14)10
Finite-source and finite-lens effects in astrometric microlensing
The aim of this paper is to study the astrometric trajectory of microlensing
events with an extended lens and/or source. We consider not only a dark lens
but also a luminous lens as well. We find that the discontinuous finite-lens
trajectories given by Takahashi (2003) will become continuous in the
finite-source regime. The point lens (source) approximation alone gives an
under (over)estimation of the astrometric signal when the size of the lens and
source are not negligible. While the finiteness of the source is revealed when
the lens transits the surface of the source, the finite-lens signal is most
prominent when the lens is very close to the source. Astrometric microlensing
towards the Galactic bulge, Small Magellanic Cloud and M31 are discussed, which
indicate that the finite-lens effect is beyond the detection limit of current
instruments. Nevertheless, it is possible to distinguish between self-lensing
and halo lensing through a (non-)detection of the astrometric ellipse. We also
consider the case where the lens is luminous itself, as has been observed where
a lensing event was followed up with the Hubble Space Telescope. We show that
the astrometric signal will be reduced in a luminous-lens scenario. The
physical properties of the event, such as the lens-source flux ratio, the size
of the lens and source nevertheless can be derived by fitting the astrometric
trajectory.Comment: 12 pages, 12 figures, 1 table, published in MNRA
Origin of Intrinsic Josephson Coupling in the Cuprates and Its Relation to Order Parameter Symmetry: An Incoherent Hopping Model
Experiments on the cuprate superconductors demonstrate that these materials
may be viewed as a stack of Josephson junctions along the c-direction. In this
paper, we present a model which describes this intrinsic Josephson coupling in
terms of incoherent quasiparticle hopping along the c-axis arising from
wave-function overlap, impurity-assisted hopping, and boson-assisted hopping.
We use this model to compute the magnitude and temperature T dependence of the
resulting Josephson critical current j_c (T) for s- and d-wave superconductors.
Contrary to other approaches, d-wave pairing in this model is compatible with
an intrinsic Josephson effect at all hole concentrations and leads to j_c (T)
\propto T at low T. By parameterizing our theory with c-axis resistivity data
from YBCO, we estimate j_c (T) for optimally doped and underdoped members of
this family. Our estimates suggest that further experiments on this compound
would be of great help in elucidating the validity of our model in general and
the pairing symmetry in particular. We also discuss the implications of our
model for LSCO and BSCCO.Comment: 28 pages, REVTEX, 5 compressed PostScript figures. Substantially
expanded and revised from the earlier version. To appear in Physica
Accretion Properties of A Sample of Hard X-ray (<60keV) Selected Seyfert 1 Galaxies
We examine the accretion properties in a sample of 42 hard (3-60keV) X-ray
selected nearby broad-line AGNs. The energy range in the sample is harder than
that usually used in the similar previous studies. These AGNs are mainly
complied from the RXTE All Sky Survey (XSS), and complemented by the released
INTEGRAL AGN catalog. The black hole masses, bolometric luminosities of AGN,
and Eddington ratios are derived from their optical spectra in terms of the
broad H emission line. The tight correlation between the hard X-ray
(3-20keV) and bolometric/line luminosity is well identified in our sample. Also
identified is a strong inverse Baldwin relationship of the H emission
line. In addition, all these hard X-ray AGNs are biased toward luminous objects
with high Eddington ratio (mostly between 0.01 to 0.1) and low column density
(), which is most likely due to the selection effect
of the surveys. The hard X-ray luminosity is consequently found to be strongly
correlated with the black hole mass. We believe the sample completeness will be
improved in the next few years by the ongoing Swift and INTEGRAL missions, and
by the next advanced missions, such as NuSTAR, Simbol-X, and NeXT. Finally, the
correlation between RFe (=optical FeII/H) and disk temperature as
assessed by leads us to
suggest that the strength of the FeII emission is mainly determined by the
shape of the ionizing spectrum.Comment: 28 pages, 7 figures, 2 tables, accepted by A
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