13,918 research outputs found
Fatal anaphylactic sting reaction in a patient with mastocytosis
We report on a 33-year-old female patient with indolent systemic mastocytosis and urticaria pigmentosa who died of an anaphylactic reaction after a yellow jacket sting. As she had no history of previous anaphylactic sting reaction, there was no testing performed in order to detect hymenoptera venom sensitization. But even if a sensitization had been diagnosed, no venom immunotherapy (VIT) would have been recommended. It is almost certain that VIT would have saved her life and it is most likely that VIT is indicated in some patients with mastocytosis with no history of anaphylactic sting reaction. However, no criteria have been established in order to allow a selection of mastocytosis patients eligible for such a `prophylactic' VIT. Copyright (C) 2008 S. Karger AG, Basel
Monodromy-data parameterization of spaces of local solutions of integrable reductions of Einstein's field equations
For the fields depending on two of the four space-time coordinates only, the
spaces of local solutions of various integrable reductions of Einstein's field
equations are shown to be the subspaces of the spaces of local solutions of the
``null-curvature'' equations constricted by a requirement of a universal (i.e.
solution independent) structures of the canonical Jordan forms of the unknown
matrix variables. These spaces of solutions of the ``null-curvature'' equations
can be parametrized by a finite sets of free functional parameters -- arbitrary
holomorphic (in some local domains) functions of the spectral parameter which
can be interpreted as the monodromy data on the spectral plane of the
fundamental solutions of associated linear systems. Direct and inverse problems
of such mapping (``monodromy transform''), i.e. the problem of finding of the
monodromy data for any local solution of the ``null-curvature'' equations with
given canonical forms, as well as the existence and uniqueness of such solution
for arbitrarily chosen monodromy data are shown to be solvable unambiguously.
The linear singular integral equations solving the inverse problems and the
explicit forms of the monodromy data corresponding to the spaces of solutions
of the symmetry reduced Einstein's field equations are derived.Comment: LaTeX, 33 pages, 1 figure. Typos, language and reference correction
Einstein's equations and the chiral model
The vacuum Einstein equations for spacetimes with two commuting spacelike
Killing field symmetries are studied using the Ashtekar variables. The case of
compact spacelike hypersurfaces which are three-tori is considered, and the
determinant of the Killing two-torus metric is chosen as the time gauge. The
Hamiltonian evolution equations in this gauge may be rewritten as those of a
modified SL(2) principal chiral model with a time dependent `coupling
constant', or equivalently, with time dependent SL(2) structure constants. The
evolution equations have a generalized zero-curvature formulation. Using this
form, the explicit time dependence of an infinite number of
spatial-diffeomorphism invariant phase space functionals is extracted, and it
is shown that these are observables in the sense that they Poisson commute with
the reduced Hamiltonian. An infinite set of observables that have SL(2) indices
are also found. This determination of the explicit time dependence of an
infinite set of spatial-diffeomorphism invariant observables amounts to the
solutions of the Hamiltonian Einstein equations for these observables.Comment: 22 pages, RevTeX, to appear in Phys. Rev.
Active and passively induced experimental autoimmune encephalomyelitis in common marmosets: a new model for multiple sclerosis.
Realization of the mean-field universality class in spin-crossover materials
In spin-crossover materials, the volume of a molecule changes depending on
whether it is in the high-spin (HS) or low-spin (LS) state. This change causes
distortion of the lattice. Elastic interactions among these distortions play an
important role for the cooperative properties of spin-transition phenomena. We
find that the critical behavior caused by this elastic interaction belongs to
the mean-field universality class, in which the critical exponents for the
spontaneous magnetization and the susceptibility are and , respectively. Furthermore, the spin-spin correlation function is a
constant at long distances, and it does not show an exponential decay in
contrast to short-range models. The value of the correlation function at long
distances shows different size-dependences: , , and
constant for temperatures above, at, and below the critical temperature,
respectively. The model does not exhibit clusters, even near the critical
point. We also found that cluster growth is suppressed in the present model and
that there is no critical opalescence in the coexistence region. During the
relaxation process from a metastable state at the end of a hysteresis loop,
nucleation phenomena are not observed, and spatially uniform configurations are
maintained during the change of the fraction of HS and LS. These
characteristics of the mean-field model are expected to be found not only in
spin-crossover materials, but also generally in systems where elastic
distortion mediates the interaction among local states.Comment: 13 pages, 16 figure
High secondary failure rate of rebanding after failed gastric banding
Background: Over the last decade, more than 130,000 laparoscopic adjustable gastric bandings (LAGB) have been performed for the treatment of morbid obesity. Nowadays, longer follow-up data are available in the literature and increasing numbers of late complications and treatment failures of gastric banding have been reported. The aim of the present study was the long-term evaluation of two different rescue operations after failed LAGB: conversion to laparoscopic Roux-en-Y bypass (LRYGB) versus laparoscopic gastric rebanding. Methods: Between January 1997 and November 2002, 74 consecutive patients underwent either laparoscopic gastric rebanding (n = 44) or LRYGB (n = 30) after failed LAGB. There were 14 men and 60 women, with a median age of 42 (23-60) years. The indication for reoperation was an increasing body mass index (BMI) and band-related complications such as pouch dilatation, band slippage, and penetration after LAGB. Rebandings were done by preference during the initial period of the study and LRYGB was the treatment of choice during the latter period. The success of the rescue operation was assessed by postoperative changes in the BMI, improvements of co-morbidities, and the need for further reoperations (secondary failure). The median follow-up was 36 months (range, 24-60 months). Results: Patients who underwent LRYGB had a significantly better weight loss than patients with a rebanding operation (mean −6.1 versus +1.5 BMI points). In addition, the LRYGB patients showed a significantly better control of serum cholesterol during the long term follow-up (−0.6 versus +0.1 mmol/l). Almost half of the patients (45%) in the rebanding group needed a further operative revision, whereas only 20% underwent reoperation after rescue LRYGB. Thus, the secondary failure rate in the rebanding group was significantly higher compared to the bypass group (p = 0.028). Conclusions: The present long-term study confirms our previous finding that LRYGB is a better treatment than rebanding after failed laparoscopic gastric banding regarding weight loss and treatment of co-morbidities. During the long-term follow-up the reoperation rate due to secondary failure became significantly higher in the rebanding group. We therefore recommend that LRYGB should be preferred as rescue procedure after failed laparoscopic adjustable gastric bandin
Infrared receivers for low background astronomy: Incoherent detectors and coherent devices from one micrometer to one millimeter
The status of incoherent detectors and coherent receivers over the infrared wavelength range from one micrometer to one millimeter is described. General principles of infrared receivers are included, and photon detectors, bolometers, coherent receivers, and important supporting technologies are discussed, with emphasis on their suitability for low background astronomical applications. Broad recommendations are presented and specific opportunities are identified for development of improved devices
Constants of motion for vacuum general relativity
The 3+1 Hamiltonian Einstein equations, reduced by imposing two commuting
spacelike Killing vector fields, may be written as the equations of the
principal chiral model with certain `source' terms. Using this
formulation, we give a procedure for generating an infinite number of non-local
constants of motion for this sector of the Einstein equations. The constants of
motion arise as explicit functionals on the phase space of Einstein gravity,
and are labelled by sl(2,R) indices.Comment: 10 pages, latex, version to appear in Phys. Rev. D
Switching dynamics between metastable ordered magnetic state and nonmagnetic ground state - A possible mechanism for photoinduced ferromagnetism -
By studying the dynamics of the metastable magnetization of a statistical
mechanical model we propose a switching mechanism of photoinduced
magnetization. The equilibrium and nonequilibrium properties of the Blume-Capel
(BC) model, which is a typical model exhibiting metastability, are studied by
mean field theory and Monte Carlo simulation. We demonstrate reversible changes
of magnetization in a sequence of changes of system parameters, which would
model the reversible photoinduced magnetization. Implications of the calculated
results are discussed in relation to the recent experimental results for
prussian blue analogs.Comment: 12 pages, 13 figure
Solution generating with perfect fluids
We apply a technique, due to Stephani, for generating solutions of the
Einstein-perfect fluid equations. This technique is similar to the vacuum
solution generating techniques of Ehlers, Harrison, Geroch and others. We start
with a ``seed'' solution of the Einstein-perfect fluid equations with a Killing
vector. The seed solution must either have (i) a spacelike Killing vector and
equation of state P=rho or (ii) a timelike Killing vector and equation of state
rho+3P=0. The new solution generated by this technique then has the same
Killing vector and the same equation of state. We choose several simple seed
solutions with these equations of state and where the Killing vector has no
twist. The new solutions are twisting versions of the seed solutions
- …