4,153 research outputs found
Lyapunov 1-forms for flows
In this paper we find conditions which guarantee that a given flow on
a compact metric space admits a Lyapunov one-form lying in a
prescribed \v{C}ech cohomology class . These
conditions are formulated in terms of the restriction of to the chain
recurrent set of . The result of the paper may be viewed as a
generalization of a well-known theorem of C. Conley about the existence of
Lyapunov functions.Comment: 27 pages, 3 figures. This revised version incorporates a few minor
improvement
Evidence for a Bulk Complex Order-Parameter in Y0.9Ca0.1Ba2Cu3O7-delta Thin Films
We have measured the penetration depth of overdoped Y0.9Ca0.1Ba2Cu3O7-delta
(Ca-YBCO) thin films using two different methods. The change of the penetration
depth as a function of temperature has been measured using the parallel plate
resonator (PPR), while its absolute value was obtained from a quasi-optical
transmission measurements. Both sets of measurements are compatible with an
order parameter of the form: Delta*dx2-y2+i*delta*dxy, with Delta=14.5 +- 1.5
meV and delta=1.8 meV, indicating a finite gap at low temperature. Below 15 K
the drop of the scattering rate of uncondensed carriers becomes steeper in
contrast to a flattening observed for optimally doped YBCO films. This decrease
supports our results on the penetration depth temperature dependence. The
findings are in agreement with tunneling measurements on similar Ca-YBCO thin
films.Comment: 11 pages, 4 figure
Insertion of the CXC chemokine ligand 9 (CXCL9) into the mouse hepatitis virus genome results in protection from viral-induced encephalitis and hepatitis.
The role of the CXC chemokine ligand 9 (CXCL9) in host defense following infection with mouse hepatitis virus (MHV) was determined. Inoculation of the central nervous system (CNS) of CXCL9-/- mice with MHV resulted in accelerated and increased mortality compared to wild type mice supporting an important role for CXCL9 in anti-viral defense. In addition, infection of RAG1-/- or CXCL9-/- mice with a recombinant MHV expressing CXCL9 (MHV-CXCL9) resulted in protection from disease that correlated with reduced viral titers within the brain and NK cell-mediated protection in the liver. Survival in MHV-CXCL9-infected CXCL9-/- mice was associated with reduced viral burden within the brain that coincided with increased T cell infiltration. Similarly, viral clearance from the livers of MHV-CXCL9-infected mice was accelerated but independent of increased T cell or NK cell infiltration. These observations indicate that CXCL9 promotes protection from coronavirus-induced neurological and liver disease
Supersymmetry, homology with twisted coefficients and n-dimensional knots
Let be any natural number. Let be any -dimensional knot in
. We define a supersymmetric quantum system for with the following
properties. We firstly construct a set of functional spaces (spaces of
fermionic \{resp. bosonic\} states) and a set of operators (supersymmetric
infinitesimal transformations) in an explicit way. Thus we obtain a set of the
Witten indexes for . Our Witten indexes are topological invariants for
-dimensional knots. Our Witten indexes are not zero in general. If is
equivalent to the trivial knot, all of our Witten indexes are zero. Our Witten
indexes restrict the Alexander polynomials of -knots. If one of our Witten
indexes for an -knot is nonzero, then one of the Alexander polynomials
of is nontrivial. Our Witten indexes are connected with homology with
twisted coefficients. Roughly speaking, our Witten indexes have path integral
representation by using a usual manner of supersymmetric theory.Comment: 10pages, no figure
Evidence of a subenergy gap in the overdoped regime of Y_{1-x}Ca_{x}Ba_{2}Cu_{3}O_{7-\delta} thin films from THz Spectroscopy
We measured the terahertz (THz) complex conductivity of Ca doped
YBa_{2}Cu_{3}O_{7-\delta} thin films in the frequency range of 0.1 to 3 THz (3
to 100 cm^{-1}) and at a temperature range of 20 to 300 K. The films were
measured using both time domain and frequency domain THz methods. We showed
evidence for the existence of a sub-gap in overdoped
Y_{1-x}Ca_{x}Ba_{2}Cu_{3}O_{7-\delta} samples doped with 5% and 10% Ca.
Evidence for the opening of this sub-gap appears as a sharp decrease in the
spectrum of the real part of conductivity at frequencies equivalent to a gap
energy of 1 meV and is more prominent with increased doping. This decrease in
conductivity can be explained by using d-wave pairing symmetry with an
imaginary part of is or id_{xy} which suggests node removal.Comment: 7 pages, 7 figure
Space power distribution system technology. Volume 2: Autonomous power management
Electrical power subsystem requirements, power management system functional requirements, algorithms, power management subsystem, hardware development, and trade studies and analyses are discussed
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