7,306 research outputs found
The incidence of portal vein thrombosis at liver transplantation
The incidence of portal vein thrombosis was examined in 885 patients who received orthotopic liver transplantations for various end‐stage liver diseases between 1989 and 1990. The thrombosis was classified into four grades. Grade 1 was thrombosis of intrahepatic portal vein branches, grade 2 was thrombosis of the right or left portal branch or at the bifurcation, grade 3 was partial obstruction of the portal vein trunk, and grade 4 was complete obstruction of the portal vein trunk. Among the 849 patients without previous portosystemic shunt, 14 patients (1.6%) had grade 1, 27 patients (3.2%) had grade 2, 27 patients (3.2%) had grade 3 and 49 patients (5.8%) had grade 4 portal vein thrombosis. The incidence of portal vein thrombosis was highest (34.8%) in the patients with hepatic malignancy in the cirrhotic liver, followed by those with Budd‐Chiari syndrome (22.2%) and postnecrotic cirrhosis of various causes (15.7%). The patients with encephalopathy, ascites, variceal bleeding, previous splenectomy and small liver had significantly higher incidences of portal vein thrombosis than the others. The total incidence of portal vein thrombosis among the 36 patients with previous portosystemic shunt was 38.9%, which was significantly higher than that (13.8%) of those without shunt. (HEPATOLOGY 1992;16;1195–1198.) Copyright © 1992 American Association for the Study of Liver Disease
Current induced magnetization reversal on the surface of a topological insulator
We study dynamics of the magnetization coupled to the surface Dirac fermions
of a three di- mensional topological insulator. By solving the
Landau-Lifshitz-Gilbert equation in the presence of charge current, we find
current induced magnetization dynamics and discuss the possibility of mag-
netization reversal. The torque from the current injection depends on the
transmission probability through the ferromagnet and shows nontrivial
dependence on the exchange coupling. The mag- netization dynamics is a direct
manifestation of the inverse spin-galvanic effect and hence another ferromagnet
is unnecessary to induce spin transfer torque in contrast to the conventional
setup.Comment: 4 pages, 4 figure
Dynamics of magnetization on the topological surface
We investigate theoretically the dynamics of magnetization coupled to the
surface Dirac fermions of a three dimensional topological insulator, by
deriving the Landau-Lifshitz-Gilbert (LLG) equation in the presence of charge
current. Both the inverse spin-Galvanic effect and the Gilbert damping
coefficient are related to the two-dimensional diagonal conductivity
of the Dirac fermion, while the Berry phase of the ferromagnetic
moment to the Hall conductivity . The spin transfer torque and the
so-called -terms are shown to be negligibly small. Anomalous behaviors
in various phenomena including the ferromagnetic resonance are predicted in
terms of this LLG equation.Comment: 4+ pages, 1 figur
Growth rates of lava domes with respect to viscosity of magmas
In the discussion of lava dome formation, viscosity of magma plays an important role. Measurements of viscosity
of magmas in field and laboratory are briefly summarized. The types of lava dome emplacements are classified
into two, squeeze- and spine-type, by kinetic processes. The squeeze-type is the formation of a dome as a
result of squeezes of magma through conduits and the latter is solidified magma forced to ascend by underlying
fluid magma. An important parameter in the formation of such lava domes is their growth rates. Lava domes of
squeeze-type are governed by the Hagen-Poiseuille Law which involves their viscosoties and other eruption parameters.
At present, the real viscosity of magmas at the site of lava dome is still inaccessible. In order to avoid
uncertainty in viscosity of magmas, a conception of «macroscopic viscosity» is proposed, which involves effects
of chemical components, mainly SiO2 and volatile material, crystals and temperature, and their changes with
time. Lava dome formations during the 20th century are briefly examined and their growth rates are estimated.
The relationship between the growth rates and the SiO2 content of the magma is statistically studied, and the
macroscopic viscosity is empirically expressed as a function of SiO2 content. The linearity between the two parameters
is reasonably interpreted. This means that formation processes of lava domes are dominantly controlled
by macroscopic viscosity of magma
Spin-current absorption by inhomogeneous spin-orbit coupling
We investigate the spin-current absorption induced by an inhomogeneous
spin-orbit coupling due to impurities in metals. We consider the system with
spin currents driven by the electric field or the spin accumulation. The
resulting diffusive spin currents, including the gradient of the spin-orbit
coupling strength, indicate the spin-current absorption at the interface, which
is exemplified with experimentally relevant setups.Comment: 13 pages, 5 figure
Charge transport in two dimensional electron gas/superconductor junctions with Rashba spin-orbit coupling
We have studied the tunneling conductance in two dimensional electron gas /
insulator / superconductor junctions in the presence of Rashba spin-orbit
coupling (RSOC). It is found that for low insulating barrier the tunneling
conductance is suppressed by the RSOC while for high insulating barrier it is
almost independent of the RSOC. We also find the reentrant behavior of the
conductance at zero voltage as a function of RSOC for intermediate insulating
barrier strength. The results are essentially different from those predicted in
ferromagnet / superconductor junctions. The present derivation of the
conductance is applicable to arbitrary velocity operator with off-diagonal
components.Comment: 8 pages, 6 figure
Theory of Josephson effect in chiral p-wave superconductor / diffusive normal metal / chiral p-wave superconductor junctions
We study the Josephson effect between chiral p-wave superconductor /
diffusive normal metal (DN) / chiral p-wave superconductor (CP/DN/CP) junctions
using quasiclassical Green's function formalism with proper boundary
conditions. The px+ipy-wave symmetry of superconducting order parameter is
chosen which is believed to be a pairing state in Sr2RuO4. It is shown that the
Cooper pairs induced in DN have an odd-frequency spin-triplet s-wave symmetry,
where pair amplitude is an odd function of Matsubara frequency. Despite the
peculiar symmetry properties of the Cooper pairs, the behavior of the Josephson
current is rather conventional. We have found that the current phase relation
is almost sinusoidal and the Josephson current is proportional to exp(-L/xi),
where xi is the coherence length of the Cooper pair in DN and L is the length
of DN. The Josephson current between CP / diffusive ferromagnet metal (DF) / CP
junctions is also calculated. It is shown that the 0-pi transition can be
realized by varying temperature or junction length L similar to the case of
conventional s-wave junctions. These results may serve as a guide to study
superconducting state of Sr2RuO4.Comment: 9 pages, 9 figure
Arterial Mycotic Aneurysm and Rupture: A Potentially Fatal Complication of Pancreas Transplantation in Diabetes Mellitus
• Mycotic aneurysm at the site of a Carrel patch arterial anastomosis occurred in four patients who had undergone whole pancreas transplantation 2.5 to 14.5 months previously. In all patients, the graft had been removed, leaving the Carrel patch on the iliac artery. The aneurysms ruptured into the intestine or the extraperitoneal space. The ruptures were sudden and life-threatening in three of four cases. This diagnosis must be suspected in patients with a history of pancreas transplantation in the immediate or distant past if they present with unexplained hypotension, cardiac arrest, or gastrointestinal tract bleeding. © 1989, American Medical Association. All rights reserved
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