3,373 research outputs found
Dynamics and symmetries of a field partitioned by an accelerated frame
The canonical evolution and symmetry generators are exhibited for a
Klein-Gordon (K-G) system which has been partitioned by an accelerated
coordinate frame into a pair of subsystems. This partitioning of the K-G system
is conveyed to the canonical generators by the eigenfunction property of the
Minkowski Bessel (M-B) modes. In terms of the M-B degrees of freedom, which are
unitarily related to those of the Minkowski plane waves, a near complete
diagonalization of these generators can be realized.Comment: 14 pages, PlainTex. Related papers on accelerated frames available at
http://www.math.ohio-state.edu/~gerlac
Coulomb field of an accelerated charge: physical and mathematical aspects
The Maxwell field equations relative to a uniformly accelerated frame, and
the variational principle from which they are obtained, are formulated in terms
of the technique of geometrical gauge invariant potentials. They refer to the
transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge
invariant "2+2" decomposition is used to see how the Coulomb field of a charge,
static in an accelerated frame, has properties that suggest features of
electromagnetism which are different from those in an inertial frame. In
particular, (1) an illustrative calculation shows that the Larmor radiation
reaction equals the electrostatic attraction between the accelerated charge and
the charge induced on the surface whose history is the event horizon, and (2) a
spectral decomposition of the Coulomb potential in the accelerated frame
suggests the possibility that the distortive effects of this charge on the
Rindler vacuum are akin to those of a charge on a crystal lattice.Comment: 27 pages, PlainTex. Related papers available at
http://www.math.ohio-state.edu/~gerlac
Quantum Mechanical Carrier of the Imprints of Gravitation
We exhibit a purely quantum mechanical carrier of the imprints of gravitation
by identifying for a relativistic system a property which (i) is independent of
its mass and (ii) expresses the Poincare invariance of spacetime in the absence
of gravitation. This carrier consists of the phase and amplitude correlations
of waves in oppositely accelerating frames. These correlations are expressed as
a Klein-Gordon-equation-determined vector field whose components are the
``Planckian power'' and the ``r.m.s. thermal fluctuation'' spectra. The
imprints themselves are deviations away from this vector field.Comment: 8 pages, RevTex. Html version of this and related papers on
accelerated frames available at http://www.math.ohio-state.edu/~gerlac
Yorkie and JNK Control Tumorigenesis in Drosophila Cells with Cytokinesis Failure
Summary: Cytokinesis failure may result in the formation of polyploid cells, and subsequent mitosis can lead to aneuploidy and tumor formation. Tumor suppressor mechanisms limiting the oncogenic potential of these cells have been described. However, the universal applicability of these tumor-suppressive barriers remains controversial. Here, we use Drosophila epithelial cells to investigate the consequences of cytokinesis failure in vivo. We report that cleavage defects trigger the activation of the JNK pathway, leading to downregulation of the inhibitor of apoptosis DIAP1 and programmed cell death. Yorkie overcomes the tumor-suppressive role of JNK and induces neoplasia. Yorkie regulates the cell cycle phosphatase Cdc25/string, which drives tumorigenesis in a context of cytokinesis failure. These results highlight the functional significance of the JNK pathway in epithelial cells with defective cytokinesis and elucidate a mechanism used by emerging tumor cells to bypass this tumor-suppressive barrier and develop into tumors. : Cytokinesis failure can be tumorigenic. Gerlach et al. show that JNK represses the expansion of those cells. Yorkie, the Drosophila ortholog of YAP and effector of the Hippo pathway, is able to bypass this barrier in cells with cytokinesis defects and cause neoplastic tumors. Keywords: cytokinesis failure, Drosophila, CDC25, cancer, JNK, Hippo pathway, cell cycle, genomic instabilit
Inappropriateness of the Rindler quantization
It is argued that the Rindler quantization is not a correct approach to study
the effects of acceleration on quantum fields. First, the "particle"-detector
approach based on the Minkowski quantization is not equivalent to the approach
based on the Rindler quantization. Second, the event horizon, which plays the
essential role in the Rindler quantization, cannot play any physical role for a
local noninertial observer.Comment: 3 pages, accepted for publication in Mod. Phys. Lett.
Effect of Plasma Irradiation on films
The effect of plasma irradiation is studied systematically on a 4H polytype
(002) oriented stoichiometric film having compressive residual
stress. Plasma irradiation was found to change the orientation to (110) of the
film at certain moderate irradiation distances. A linear decrease in grain size
and residual stress was observed with decreasing irradiation distance (or
increasing ion energy) consistent with both structural and morphological
observations. The direct optical energy gap was found to increase
linearly at the rate with the compressive stress. The
combined data of present compressive stress and from earlier reported tensile
stress show a consistent trend of change with stress. The
iodine-iodine distance in the unit cell could be responsible for the observed
change in with stress.Comment: 13 pages and 10 fi
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