975 research outputs found
Power-law scaling behaviour of impedance signal time series of healthy subjects at rest
International audienc
Exact Solutions to the Sine-Gordon Equation
A systematic method is presented to provide various equivalent solution
formulas for exact solutions to the sine-Gordon equation. Such solutions are
analytic in the spatial variable and the temporal variable and they
are exponentially asymptotic to integer multiples of as
The solution formulas are expressed explicitly in terms of a real triplet of
constant matrices. The method presented is generalizable to other integrable
evolution equations where the inverse scattering transform is applied via the
use of a Marchenko integral equation. By expressing the kernel of that
Marchenko equation as a matrix exponential in terms of the matrix triplet and
by exploiting the separability of that kernel, an exact solution formula to the
Marchenko equation is derived, yielding various equivalent exact solution
formulas for the sine-Gordon equation.Comment: 43 page
Topological phases for bound states moving in a finite volume
We show that bound states moving in a finite periodic volume have an energy
correction which is topological in origin and universal in character. The
topological volume corrections contain information about the number and mass of
the constituents of the bound states. These results have broad applications to
lattice calculations involving nucleons, nuclei, hadronic molecules, and cold
atoms. We illustrate and verify the analytical results with several numerical
lattice calculations.Comment: 4 pages, 1 figure, version to appear in Phys. Rev. D Rapid
Communication
Numerical analysis of seismic wave amplification in Nice (France) and comparisons with experiments
The analysis of site effects is very important since the amplification of
seismic motion in some specific areas can be very strong. In this paper, the
site considered is located in the centre of Nice on the French Riviera. Site
effects are investigated considering a numerical approach (Boundary Element
Method) and are compared to experimental results (weak motion and
microtremors). The investigation of seismic site effects through numerical
approaches is interesting because it shows the dependency of the amplification
level on such parameters as wave velocity in surface soil layers, velocity
contrast with deep layers, seismic wave type, incidence and damping. In this
specific area of Nice, a one-dimensional (1D) analytical analysis of
amplification does not give a satisfactory estimation of the maximum reached
levels. A boundary element model is then proposed considering different wave
types (SH, P, SV) as the seismic loading. The alluvial basin is successively
assumed as an isotropic linear elastic medium and an isotropic linear
viscoelastic solid (standard solid). The thickness of the surface layer, its
mechanical properties, its general shape as well as the seismic wave type
involved have a great influence on the maximum amplification and the frequency
for which it occurs. For real earthquakes, the numerical results are in very
good agreement with experimental measurements for each motion component.
Two-dimensional basin effects are found to be very strong and are well
reproduced numerically
Characterizing groundwater flow and heat transport in fractured rock using Fiber-Optic Distributed Temperature Sensing
International audienceWe show how fully distributed space-time measurements with Fiber-Optic Distributed Temperature Sensing (FO-DTS) can be used to investigate groundwater flow and heat transport in fractured media. Heat injection experiments are combined with temperature measurements along fiber-optic cables installed in boreholes. Thermal dilution tests are shown to enable detection of cross-flowing fractures and quantification of the cross flow rate. A cross borehole thermal tracer test is then analyzed to identify fracture zones that are in hydraulic connection between boreholes and to estimate spatially distributed temperature breakthrough in each fracture zone. This provides a significant improvement compared to classical tracer tests, for which concentration data are usually integrated over the whole abstraction borehole. However, despite providing some complementary results, we find that the main contributive fracture for heat transport is different to that for a solute tracer
Tolerance induction in memory CD4 T cells requires two rounds of antigen-specific activation
Autoimmune diseases are driven by immune cells that recognize self-tissues. A major goal for treatment strategies for autoimmune diseases is to turn off or tolerize self-reactive immune cells such as CD4 T cells that coordinate tissue damage in many autoimmune diseases. Autoimmune diseases are often diagnosed many years following their onset. The self-reactive CD4 T cells that must be tolerized, therefore, are previously activated or memory CD4 T cells. Little is known about whether tolerance can be induced in memory CD4 T cells. This paper demonstrates that memory CD4 T cells survive initial exposure to tolerance-inducing signals but that a second activation signal leads to cell death. This study has important implications for immunotherapeutic strategies for autoimmune diseases
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