17 research outputs found
Oscillations of neutrinos and mesons in quantum field theory
This report deals with the quantum field theory of particle oscillations in
vacuum. We first review the various controversies regarding quantum-mechanical
derivations of the oscillation formula, as well as the different
field-theoretical approaches proposed to settle them. We then clear up the
contradictions between the existing field-theoretical treatments by a thorough
study of the external wave packet model. In particular, we show that the latter
includes stationary models as a subcase. In addition, we explicitly compute
decoherence terms, which destroy interferences, in order to prove that the
coherence length can be increased without bound by more accurate energy
measurements. We show that decoherence originates not only in the width and in
the separation of wave packets, but also in their spreading through space-time.
In this review, we neither assume the relativistic limit nor the stability of
oscillating particles, so that the oscillation formula derived with
field-theoretical methods can be applied not only to neutrinos but also to
neutral K and B mesons. Finally, we discuss oscillations of correlated
particles in the same framework.Comment: v2, 124 pages, 10 figures (7 more); updated review of the literature;
complete derivation of the oscillation probability at short and large
distance; more details on the influence of the spreading of the amplitude on
decoherence; submitted to Physics Report
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INTERPRETATION OF THE SURFACE BRIGHTNESS OF PHOBOS
Analysis of disk resolved images of Phobos obtained by the Phobos 2 spacecraft allows us to study the surface scattering law and albedo variations. From low phase angle images we find variations in local geometric albedo 10%, with a correlation length 1km. The scattering law is reasonable well matched by the recent proposed LPI (Lumme et al. 1990a) model, which allows us to deduce a small scale ( 1mm) surface roughness ( 0.5), defined here as the rms. tangent of the local surface normal relative to the mean surface normal in the Duxbury (1991) model of Phobos. This value is very close to what has been found for Mercury and the Moon
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INTERPRETATION OF THE SURFACE BRIGHTNESS OF PHOBOS
Analysis of disk resolved images of Phobos obtained by the Phobos 2 spacecraft allows us to study the surface scattering law and albedo variations. From low phase angle images we find variations in local geometric albedo 10%, with a correlation length 1km. The scattering law is reasonable well matched by the recent proposed LPI (Lumme et al. 1990a) model, which allows us to deduce a small scale ( 1mm) surface roughness ( 0.5), defined here as the rms. tangent of the local surface normal relative to the mean surface normal in the Duxbury (1991) model of Phobos. This value is very close to what has been found for Mercury and the Moon
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SCATTERING OF LIGHT BY STOCHASTICALLY ROUGH PARTICLES
The single particle phase function and the linear polarization for large stochastically deformed spheres have been calculated by Monte Carlo simulation using the geometrical optics approximation. The radius vector of a particle is assumed to obey a bivariate lognormal distribution with three free parameters: mean radius, its standard deviation and the coherence length of the autocorrelation function. All reflections/refractions which include sufficient energy have been included. Real and imaginary parts of the refractive index can be varied without any restrictions. Results and comparisons with some earlier less general theories are presented. Applications of this theory to the photometric properties of atmosphereless bodies and interplanetary dust are discussed
Novel Role for Glutathione S-Transferase π: REGULATOR OF PROTEIN S-GLUTATHIONYLATION FOLLOWING OXIDATIVE AND NITROSATIVE STRESS*
Glutathione S-transferase Pi (GSTπ) is a marker protein in many
cancers and high levels are linked to drug resistance, even when the selecting
drug is not a substrate. S-Glutathionylation of proteins is critical
to cellular stress response, but characteristics of the forward reaction are
not known. Our results show that GSTπ potentiates
S-glutathionylation reactions following oxidative and nitrosative
stress in vitro and in vivo. Mutational analysis indicated
that the catalytic activity of GST is required. GSTπ is itself
redox-regulated. S-Glutathionylation on Cys47 and
Cys101 autoregulates GSTπ, breaks ligand binding interactions
with c-Jun NH2-terminal kinase (JNK), and causes GSTπ multimer
formation, all critical to stress response. Catalysis of
S-glutathionylation at low pK cysteines in proteins is a
novel property for GSTπ and may be a cause for its abundance in tumors and
cells resistant to a range of mechanistically unrelated anticancer drugs