4,705 research outputs found
On the theory of polarization transfer in inhomogeneous magnetized plasmas
Polarization transfer theory in inhomogeneous magnetized plasmas with mode couplin
Larkin-Ovchinnikov-Fulde-Ferrell phase in the superconductor (TMTSF)2ClO4: Theory versus experiment
We consider a formation of the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase
in a quasi-one-dimensional (Q1D) conductor in a magnetic field, parallel to its
conducting chains, where we take into account both the paramagnetic
spin-splitting and orbital destructive effects against superconductivity. We
show that, due to a relative weakness of the orbital effects in a Q1D case, the
LOFF phase appears in (TMTSF)ClO superconductor for real values of its
Q1D band parameters. We compare our theoretical calculations with the recent
experimental data by Y. Maeno's group [S. Yonezawa et al., Phys. Rev. Lett.
\textbf{100}, 117002 (2008)] and show that there is a good qualitative and
quantitative agreement between the theory and experimental data.Comment: 4 pages, 1 figur
Evolution of hepatitis B virus liver disease after hepatic replacement. Practical and theoretical considerations
The morphologic evolution of hepatitis B virus (HBV) liver disease in 45 hepatic allograft recipients who were HBV surface-antigen positive (HBs-Ag+) at the time of liver replacement and who survived for more than 60 days was studied by routine histologic and immunocytochemical analysis of serial pathology specimens. The findings in these patients were compared to a control group of 30 individuals who were immune to the HBV (anti-HBs antibody positive), but required hepatic replacement for other reasons. Eight of the forty-five (18%) HBsAg-positive patients have no serologic evidence of HBV reinfection after transplantation. All 37 remaining patients are reinfected; 21 (47%) developed chronic active hepatitis and/or cirhosis, 3 (7%) developed submassive necrosis, and 6 (14%) developed chronic lobular hepatitis. One patient lost her graft to chronic rejection, despite reinfection with the B virus. Four other patients (9%) developed a chronic carrier state. No long-term follow-up biopsies were available in the remaining two patients. The histologic features associated with dysfunction related to recurrent HBV infection evolved from an acute to chronic phase and were similar to hepatitis B seen in nonallografted livers. Furthermore HBV-related lesions could be separated from rejection using routine histology alone. The only exception to this conclusion was the occurrence of a peculiar HBV-related lesion in two recipients, described herein. Immunohistochemical analysis demonstrated the presence of viral antigens in almost all cases. Hepatic inflammation also was commonly present during HBV disease and consisted mostly of accessory cells and T lymphocytes. Analysis of the effect of major histocompatibility complex matching revealed no clear association between the number of class I or II matches or mismatches and the development, or pattern, of active hepatitis in the allograft. Peculiar pathologic alterations in several of the biopsies and failed allografts after HBV reinfection suggests that, under special circumstances, the B virus may by cytopathic
Two-terminal write-once-read-many-times memory device based on charging-controlled current modulation in Al/Al-Rich Al 2O 3/p-Si diode
A write-once-read-many-times (WORM) memory device was realized based on the charging-controlled modulation in the current conduction of Al/Al-rich Al 2O 3/p-type Si diode. A large increase in the reverse current of the diode could be achieved with a negative charging voltage, e.g., charging at -25 V for 1 ms results in a current increase by about four orders. Memory states of the WORM device could be altered by changing the current conduction with charge trapping in the Al-rich Al 2O 3 layer. The memory exhibited good reading endurance and retention characteristics. © 2011 IEEE.published_or_final_versio
Demystifying construction project time-effort distribution curves: a BIM and non-BIM comparison
MacLeamy's time-effort distribution curves are among the most oft-cited sources for researchers interested in mainstreaming building information modeling (BIM) implementation in the architecture, engineering, and construction (AEC) industry. Succinctly, the curves offer a clever answer to the question: How can BIM benefit AEC processes? However, despite their significant theoretical and practical value, little previous research has been conducted to elaborate the time-effort distribution curves of any real-life projects. This research aims to demystify the time-effort distribution curves through comparison of a representative BIM project and a non-BIM project. Applying a set of innovative approaches, the actual time-effort distribution curves of two public housing construction projects in Hong Kong are produced and analyzed in-depth. The curves vividly show that BIM implementation increases the effort spent at design stage - that is, throughout the architecture and engineering processes - but the extra effort pays off at the building stage. Further, the curves are found to be a useful graphical analytic tool for other purposes, such as adjusting the fee structure among AEC processes and informing improved BIM adoption.postprin
Two-dimensional Vesicle dynamics under shear flow: effect of confinement
Dynamics of a single vesicle under shear flow between two parallel plates is
studied using two-dimensional lattice-Boltzmann simulations. We first present
how we adapted the lattice-Boltzmann method to simulate vesicle dynamics, using
an approach known from the immersed boundary method. The fluid flow is computed
on an Eulerian regular fixed mesh while the location of the vesicle membrane is
tracked by a Lagrangian moving mesh. As benchmarking tests, the known vesicle
equilibrium shapes in a fluid at rest are found and the dynamical behavior of a
vesicle under simple shear flow is being reproduced. Further, we focus on
investigating the effect of the confinement on the dynamics, a question that
has received little attention so far. In particular, we study how the vesicle
steady inclination angle in the tank-treading regime depends on the degree of
confinement. The influence of the confinement on the effective viscosity of the
composite fluid is also analyzed. At a given reduced volume (the swelling
degree) of a vesicle we find that both the inclination angle, and the membrane
tank-treading velocity decrease with increasing confinement. At sufficiently
large degree of confinement the tank-treading velocity exhibits a
non-monotonous dependence on the reduced volume and the effective viscosity
shows a nonlinear behavior.Comment: 12 pages, 8 figure
Lateral migration of a 2D vesicle in unbounded Poiseuille flow
The migration of a suspended vesicle in an unbounded Poiseuille flow is
investigated numerically in the low Reynolds number limit. We consider the
situation without viscosity contrast between the interior of the vesicle and
the exterior. Using the boundary integral method we solve the corresponding
hydrodynamic flow equations and track explicitly the vesicle dynamics in two
dimensions. We find that the interplay between the nonlinear character of the
Poiseuille flow and the vesicle deformation causes a cross-streamline migration
of vesicles towards the center of the Poiseuille flow. This is in a marked
contrast with a result [L.G. Leal, Ann. Rev. Fluid Mech. 12,
435(1980)]according to which the droplet moves away from the center (provided
there is no viscosity contrast between the internal and the external fluids).
The migration velocity is found to increase with the local capillary number
(defined by the time scale of the vesicle relaxation towards its equilibrium
shape times the local shear rate), but reaches a plateau above a certain value
of the capillary number. This plateau value increases with the curvature of the
parabolic flow profile. We present scaling laws for the migration velocity.Comment: 11 pages with 4 figure
A simplified particulate model for coarse-grained hemodynamics simulations
Human blood flow is a multi-scale problem: in first approximation, blood is a
dense suspension of plasma and deformable red cells. Physiological vessel
diameters range from about one to thousands of cell radii. Current
computational models either involve a homogeneous fluid and cannot track
particulate effects or describe a relatively small number of cells with high
resolution, but are incapable to reach relevant time and length scales. Our
approach is to simplify much further than existing particulate models. We
combine well established methods from other areas of physics in order to find
the essential ingredients for a minimalist description that still recovers
hemorheology. These ingredients are a lattice Boltzmann method describing rigid
particle suspensions to account for hydrodynamic long range interactions
and---in order to describe the more complex short-range behavior of
cells---anisotropic model potentials known from molecular dynamics simulations.
Paying detailedness, we achieve an efficient and scalable implementation which
is crucial for our ultimate goal: establishing a link between the collective
behavior of millions of cells and the macroscopic properties of blood in
realistic flow situations. In this paper we present our model and demonstrate
its applicability to conditions typical for the microvasculature.Comment: 12 pages, 11 figure
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