8,727 research outputs found
Progress in the use of adeno-associated viral vectors for gene therapy
The development of safe and efficient gene transfer vectors is crucial for the success of gene therapy trials. A viral vector system promising to meet these requirements is based on the apathogenic adeno-associated virus (AAV-2), a member of the parvovirus family. The advantages of this vector system is the stability of the viral capsid, the low immunogenicity, the ability to transduce both dividing and non-dividing cells, the potential to integrate site specifically and to achieve long-term gene expression even in vivo, and its broad tropism allowing the efficient transduction of diverse organs including the skin. All this makes AAV-2 attractive and efficient for in vitro gene transfer and local injection in vivo. This review covers the progress made in AAV vector technology including the development of AAV vectors based on other serotypes, summarizes the results obtained by AAV targeting vectors and outlines potential applications in the field of cutaneous gene therapy. Copyright (C) 2004 S. Karger AG, Basel
Influence of maneuverability on helicopter combat effectiveness
A computational procedure employing a stochastic learning method in conjunction with dynamic simulation of helicopter flight and weapon system operation was used to derive helicopter maneuvering strategies. The derived strategies maximize either survival or kill probability and are in the form of a feedback control based upon threat visual or warning system cues. Maneuverability parameters implicit in the strategy development include maximum longitudinal acceleration and deceleration, maximum sustained and transient load factor turn rate at forward speed, and maximum pedal turn rate and lateral acceleration at hover. Results are presented in terms of probability of skill for all combat initial conditions for two threat categories
Instanton theory for bosons in disordered speckle potential
We study the tail of the spectrum for non-interacting bosons in a
blue-detuned random speckle potential. Using an instanton approach we derive
the asymptotic behavior of the density of states in d dimensions. The leading
corrections resulting from fluctuations around the saddle point solution are
obtained by means of the Gel'fand-Yaglom method generalized to functional
determinants with zero modes. We find a good agreement with the results of
numerical simulations in one dimension. The effect of weak repulsive
interactions in the Lifshitz tail is also discussed.Comment: 12 pages, 3 figures, revtex
Wave function correlations and the AC conductivity of disordered wires beyond the Mott-Berezinskii law
In one-dimensional disordered wires electronic states are localized at any
energy. Correlations of the states at close positive energies and the AC
conductivity in the limit of small frequency are described by
the Mott-Berezinskii theory. We revisit the instanton approach to the
statistics of wave functions and AC transport valid in the tails of the
spectrum (large negative energies). Applying our recent results on functional
determinants, we calculate exactly the integral over gaussian fluctuations
around the exact two-instanton saddle point. We derive correlators of wave
functions at different energies beyond the leading order in the energy
difference. This allows us to calculate corrections to the Mott-Berezinskii law
(the leading small frequency asymptotic behavior of ) which
approximate the exact result in a broad range of . We compare our
results with the ones obtained for positive energies.Comment: 7 pages, 3 figure
Why does the Jeans Swindle work?
When measuring the mass profile of any given cosmological structure through
internal kinematics, the distant background density is always ignored. This
trick is often refereed to as the "Jeans Swindle". Without this trick a
divergent term from the background density renders the mass profile undefined,
however, this trick has no formal justification. We show that when one includes
the expansion of the Universe in the Jeans equation, a term appears which
exactly cancels the divergent term from the background. We thereby establish a
formal justification for using the Jeans Swindle.Comment: 5 pages, 2 figures, Accepted for publication in MNRAS Letter
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