945 research outputs found
Higher Conservation Law for the Multi-Centre Metrics
The multi-centre metrics are a family of euclidean solutions of the empty
space Einstein equations with self-dual curvature. For this full class, we
determine which metrics do exhibit an extra conserved quantity quadraic in the
momenta, induced by a Killing-Stackel tensor. Our results bring to light
several metrics which correspond to classically integrable dynamical systems.
They include, as particular cases, the Eguchi-Hanson and Taub-NUT metrics.Comment: Latex, 16 pages, 0 figur
Comment on Counterintuitive consequence of heating in strongly driven intrinsic junctions of BiSrCaCuO mesas
In a recent paper [Phys.Rev.B 81, 224518 (2010)], C. Kurter et al, analyzed
the effect of strong self-heating in large-area
BiSrCaCuO (Bi-2212) mesa structures. They conclude
that conductance peaks in their mesas occur when mesas are heated to
the superconducting critical temperature . Further on they extrapolate
this statement for all mesas, including much smaller and much better thermally
anchored mesas used in Intrinsic Tunnelling Spectroscopy (ITS). Here I show
that their conclusion does not hold neither for previously reported data, nor
even for their own mesas; the very remote extrapolation to ITS is invalid. I
also point out a number of inconsistencies and misleading references.Comment: 2 page
Further results on non-diagonal Bianchi type III vacuum metrics
We present the derivation, for these vacuum metrics, of the Painlev\'e VI
equation first obtained by Christodoulakis and Terzis, from the field equations
for both minkowskian and euclidean signatures. This allows a complete
discussion and the precise connection with some old results due to Kinnersley.
The hyperk\"ahler metrics are shown to belong to the Multi-Centre class and for
the cases exhibiting an integrable geodesic flow the relevant Killing tensors
are given. We conclude by the proof that for the Bianchi B family, excluding
type III, there are no hyperk\"ahler metrics.Comment: 21 pages, no figure
cutaneous vascular alterations in psoriatic patients treated with cyclosporine
Videocapillaroscopy can be used to assess cutaneous microcirculation modifications in vivo, and therefore allows assessment of variations in the microvascular architecture in psoriatic subjects during treatment. The aim of this study was to observe and quantify the modifications of the superficial capillary bed in psoriatic plaques during treatment with cyclosporin A. Twelve patients with psoriasis vulgaris were treated with an initial dose of 4 mg/kg/day cyclosporin A over a period of 3 months with periodic clinical and capillaroscopic assessments. Clinical resolution of the lesions and a reduction in microcirculatory alterations was observed in 70% of patients, although none returned to a normal capillaroscopic pattern
Bianchi type II,III and V diagonal Einstein metrics re-visited
We present, for both minkowskian and euclidean signatures, short derivations
of the diagonal Einstein metrics for Bianchi type II, III and V. For the first
two cases we show the integrability of the geodesic flow while for the third
case a somewhat unusual bifurcation phenomenon takes place: for minkowskian
signature elliptic functions are essential in the metric while for euclidean
signature only elementary functions appear
Quantum integrability of quadratic Killing tensors
Quantum integrability of classical integrable systems given by quadratic
Killing tensors on curved configuration spaces is investigated. It is proven
that, using a "minimal" quantization scheme, quantum integrability is insured
for a large class of classic examples.Comment: LaTeX 2e, no figure, 35 p., references added, minor modifications. To
appear in the J. Math. Phy
Celestial mechanics of elastic bodies
We construct time independent configurations of two gravitating elastic
bodies. These configurations either correspond to the two bodies moving in a
circular orbit around their center of mass or strictly static configurations.Comment: 16 pages, 2 figures, several typos removed, erratum appeared in
MathZ.263:233,200
A miniprep procedure for isolating genomic DNA from Magnoporthe grisea
We have developed a simple miniprep procedure for the isolation of genomic DNA from the ascomycete Magnaporthe grisea. This pathogen of many grasses, including rice, has a moderate growth rate and produces intermediate to low numbers of conidia when grown in culture. Thus, in our previous DNA preparation procedure we inoculated swirling liquid cultures with mycelium that had been fragmented in a blender rather than with conidia. The mycelium obtained from these cultures was ground in liquid nitrogen for DNA extraction. Though the quantity and quality of DNA obtained by this method is satisfactory, the technique is too laborious for analysis of many strains. We developed the procedure described below to eliminate the need to fragment mycelium in a blender to inoculate cultures and to eliminate the need to grind mycelium in liquid nitrogen for DNA extraction. The new procedure, which relies on the enzymatic removal of cell walls and the lysis of protoplasts, should be readily adaptable to other filamentous fungi with growth characteristics similar to those of M. grisea
Identification of nonlinearity in conductivity equation via Dirichlet-to-Neumann map
We prove that the linear term and quadratic nonlinear term entering a
nonlinear elliptic equation of divergence type can be uniquely identified by
the Dirichlet to Neuman map. The unique identifiability is proved using the
complex geometrical optics solutions and singular solutions
Relativistic Elastostatics I: Bodies in Rigid Rotation
We consider elastic bodies in rigid rotation, both nonrelativistically and in
special relativity. Assuming a body to be in its natural state in the absence
of rotation, we prove the existence of solutions to the elastic field equations
for small angular velocity.Comment: 25 page
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