5,785 research outputs found
H1-antihistamines for primary mast cell activation syndromes: a systematic review
Background
Primary mast cell activation syndromes (MCAS) are a group of disorders presenting with symptoms of mast cell mediator release.
Objectives
To assess the effectiveness and safety of orally administered H1-antihistamines in the treatment of primary MCAS compared with placebo and other pharmacologic treatments.
Methods
We systematically searched five databases and three trial repositories and contacted an international panel of experts to identify published and unpublished trials.
Results
A total of 36 potentially relevant studies were identified. Of these, five crossover trials, enrolling a total of 71 patients (63 adults), met the eligibility criteria. All five of these studies were judged to be at moderate or high risk of bias. Two studies compared an H1-antihistamine with placebo, two compared two different H1-antihistamines, and one study compared H1- and H2-antihistamines with oral cromolyn sodium. Four of the five randomized controlled trials were historic (reported from 1983–1993), small (enrolling 8–15 patients), and used agents and/or dosing regimens that are now less commonly used in clinical practice (i.e. azelastine, chlorpheniramine, hydroxyzine, and ketotifen). The fifth trial, which enrolled 33 adults with cutaneous and systemic mastocytosis found 4 weeks of treatment with the second-generation H1-antihistamine rupatadine, compared with placebo, resulted in significant improvements in quality of life, symptom control (itching, wheals and flares, flushing, tachycardia, and headache, but not gastrointestinal symptoms), and reduction in itching and whealing after standardized skin provocation to elicit Darier's sign.
Conclusions
There is an urgent need for large, well-designed, double-blind, placebo-controlled randomized trials investigating the effectiveness, cost-effectiveness, and safety of second-generation H1-antihistamines in treatment of primary MCAS
Exact calculation of the ground-state dynamical spin correlation function of a S=1/2 antiferromagnetic Heisenberg chain with free spinons
We calculate the exact dynamical magnetic structure factor S(Q,E) in the
ground state of a one-dimensional S=1/2 antiferromagnet with gapless free S=1/2
spinon excitations, the Haldane-Shastry model with inverse-square exchange,
which is in the same low-energy universality class as Bethe's nearest-neighbor
exchange model. Only two-spinon excited states contribute, and S(Q,E) is found
to be a very simple integral over these states.Comment: 11 pages, LaTeX, RevTeX 3.0, cond-mat/930903
A measurement of cosmic ray deuterium from 0.5–2.9 GeV/nucleon
The rare isotopes ^(2)H and ^(3)He in cosmic rays are believed to originate mainly from the interaction of high energy protons and helium with the galactic interstellar medium. The unique propagation history of these rare isotopes provides important constraints on galactic cosmic ray source spectra and on models for their propagation within the Galaxy. Hydrogen and helium isotopes were measured with the balloon-borne experiment, IMAX, which flew from Lynn Lake, Manitoba in 1992. The energy spectrum of deuterium between 0.5 and 3.2 GeV/nucleon measured by the IMAX experiment as well as previously published results of ^(3)He from the same instrument will be compared with predictions of cosmic ray galactic propagation models. The observed composition of the light isotopes is found to be generally consistent with the predictions of the standard Leaky Box Model derived to fit observations of heavier nucle
Universality in quantum parametric correlations
We investigate the universality of correlation functions of chaotic and
disordered quantum systems as an external parameter is varied. A new, general
scaling procedure is introduced which makes the theory invariant under
reparametrizations. Under certain general conditions we show that this
procedure is unique. The approach is illustrated with the particular case of
the distribution of eigenvalue curvatures. We also derive a semiclassical
formula for the non-universal scaling factor, and give an explicit expression
valid for arbitrary deformations of a billiard system.Comment: LaTeX, 10 pages, 2 figures. Revised version, to appear in PR
A Brownian Motion Model of Parametric Correlations in Ballistic Cavities
A Brownian motion model is proposed to study parametric correlations in the
transmission eigenvalues of open ballistic cavities. We find interesting
universal properties when the eigenvalues are rescaled at the hard edge of the
spectrum. We derive a formula for the power spectrum of the fluctuations of
transport observables as a response to an external adiabatic perturbation. Our
formula correctly recovers the Lorentzian-squared behaviour obtained by
semiclassical approaches for the correlation function of conductance
fluctuations.Comment: 19 pages, written in RevTe
Manifestation of Quantum Chaos in Electronic Band Structures
We use semiconductors as an example to show that quantum chaos manifests
itself in the energy spectrum of crystals. We analyze the {\it ab initio} band
structure of silicon and the tight-binding spectrum of the alloy
, and show that some of their statistical properties obey the
universal predictions of quantum chaos derived from the theory of random
matrices. Also, the Bloch momenta are interpreted as external, tunable,
parameters, acting on the reduced (unit cell) Hamiltonian, in close analogy to
Aharonov-Bohm fluxes threading a torus. They are used in the investigation of
the parametric autocorrelator of crystal velocities. We find that our results
are in good agreement with the universal curves recently proposed by Simons and
coworkers.Comment: 15 pages with 6 Postscript figures included, RevTex-3, CMT-ERM/940
Regularity of higher codimension area minimizing integral currents
This lecture notes are an expanded version of the course given at the
ERC-School on Geometric Measure Theory and Real Analysis, held in Pisa,
September 30th - October 30th 2013. The lectures aim to explain the main steps
of a new proof of the partial regularity of area minimizing integer rectifiable
currents in higher codimension, due originally to F. Almgren, which is
contained in a series of papers in collaboration with C. De Lellis (University
of Zurich).Comment: This text will appear in "Geometric Measure Theory and Real
Analysis", pp. 131--192, Proceedings of the ERC school in Pisa (2013), L.
Ambrosio Ed., Edizioni SNS (CRM Series
Detection of the Sgr A* activity at 3.8 and 4.8 microns with NACO
L'-band (lambda=3.8 microns) and M'-band (lambda=4.8 microns) observations of
the Galactic Center region, performed in 2003 at VLT (ESO) with the adaptive
optics imager NACO, have lead to the detection of an infrared counterpart of
the radio source Sgr A* at both wavelengths. The measured fluxes confirm that
the Sgr A* infrared spectrum is dominated by the synchrotron emission of
nonthermal electrons. The infrared counterpart exhibits no significant short
term variability but demonstrates flux variations on daily and yearly scales.
The observed emission arises away from the position of the dynamical center of
the S2 orbit and would then not originate from the closest regions of the black
hole.Comment: 5 pages, 3 figures, accepted in Astronomy & Astrophysic
Measuring the Lyapunov exponent using quantum mechanics
We study the time evolution of two wave packets prepared at the same initial
state, but evolving under slightly different Hamiltonians. For chaotic systems,
we determine the circumstances that lead to an exponential decay with time of
the wave packet overlap function. We show that for sufficiently weak
perturbations, the exponential decay follows a Fermi golden rule, while by
making the difference between the two Hamiltonians larger, the characteristic
exponential decay time becomes the Lyapunov exponent of the classical system.
We illustrate our theoretical findings by investigating numerically the overlap
decay function of a two-dimensional dynamical system.Comment: 9 pages, 6 figure
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