525 research outputs found
Simultaneous Identification of the Diffusion Coefficient and the Potential for the Schr\"odinger Operator with only one Observation
This article is devoted to prove a stability result for two independent
coefficients for a Schr\"odinger operator in an unbounded strip. The result is
obtained with only one observation on an unbounded subset of the boundary and
the data of the solution at a fixed time on the whole domain
Global convergence for Inverse Problems
A globally convergent numerical method for a multidimensional Coefficient Inverse Problem for a hyperbolic equation is presented. It is shown that this technique provides a good starting point for the finite element adaptive method (adaptivity). This leads to a natural two-stage numerical procedure, which synthesizes both these methods
Thermoacoustic tomography with an arbitrary elliptic operator
Thermoacoustic tomography is a term for the inverse problem of determining of
one of initial conditions of a hyperbolic equation from boundary measurements.
In the past publications both stability estimates and convergent numerical
methods for this problem were obtained only under some restrictive conditions
imposed on the principal part of the elliptic operator. In this paper
logarithmic stability estimates are obatined for an arbitrary variable
principal part of that operator. Convergence of the Quasi-Reversibility Method
to the exact solution is also established for this case. Both complete and
incomplete data collection cases are considered.Comment: 16 page
A global Carleman estimate in a transmission wave equation and application to a one-measurement inverse problem
We consider a transmission wave equation in two embedded domains in ,
where the speed is in the inner domain and in the outer
domain. We prove a global Carleman inequality for this problem under the
hypothesis that the inner domain is strictly convex and . As a
consequence of this inequality, uniqueness and Lip- schitz stability are
obtained for the inverse problem of retrieving a stationary potential for the
wave equation with Dirichlet data and discontinuous principal coefficient from
a single time-dependent Neumann boundary measurement
Attaching zanamivir to a polymer markedly enhances its activity against drug-resistant strains of influenza a virus
Effects of the commercial drug zanamivir (Relenzaâą) covalently attached to poly-l-glutamine on the infectivity of influenza A viruses are examined using the plaque reduction assay and binding affinity to viral neuraminidase (NA). These multivalent drug conjugates exhibit (i) up to a 20,000-fold improvement in anti-influenza potency compared with the zanamivir parent against human and avian viral strains, including both wild-type and drug-resistant mutants, and (ii) superior neuraminidase (NA) inhibition constants, especially for the mutants. These findings provide a basis for exploring polymer-attached inhibitors as more efficacious therapeutics, particularly against drug-resistant influenza strains.National Institutes of Health (U.S.) (Grant Number U01-AI074443)FundacioÌn RamoÌn Areces. Postdoctoral Fellowshi
Complete determination of the reflection coefficient in neutron specular reflection by absorptive non-magnetic media
An experimental method is proposed which allows the complete determination of
the complex reflection coefficient for absorptive media for positive and
negative values of the momenta. It makes use of magnetic reference layers and
is a modification of a recently proposed technique for phase determination
based on polarization measurements. The complex reflection coefficient
resulting from a simulated application of the method is used for a
reconstruction of the scattering density profiles of absorptive non-magnetic
media by inversion.Comment: 14 pages, 4 figures, reformulation of abstract, ref.12 added,
typographical correction
Inversion of Randomly Corrugated Surfaces Structure from Atom Scattering Data
The Sudden Approximation is applied to invert structural data on randomly
corrugated surfaces from inert atom scattering intensities. Several expressions
relating experimental observables to surface statistical features are derived.
The results suggest that atom (and in particular He) scattering can be used
profitably to study hitherto unexplored forms of complex surface disorder.Comment: 10 pages, no figures. Related papers available at
http://neon.cchem.berkeley.edu/~dan
Effect of Liposome Characteristics and Dose on the Pharmacokinetics of Liposomes Coated with Poly(amino acid)s
Long-circulating liposomes, such as PEG-liposomes, are frequently studied for drug delivery and diagnostic purposes. In our group, poly(amino acid) (PAA)-based coatings for long-circulating liposomes have been developed. These coatings provide liposomes with similar circulation times as compared to PEG-liposomes, but have the advantage of being enzymatically degradable. For PEG-liposomes it has been reported that circulation times are relatively independent of their physicochemical characteristics. In this study, the influence of factors such as PAA grafting density, cholesterol inclusion, surface charge, particle size, and lipid dose on the circulation kinetics of PAA-liposomes was evaluated after intravenous administration in rats. Prolonged circulation kinetics of PAA-liposomes can be maintained upon variation of liposome characteristics and the lipid dose given. However, the use of relatively high amounts of strongly charge-inducing lipids and a too large mean size is to be avoided. In conclusion, PAA-liposomes represent a versatile drug carrier system for a wide variety of applications
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