1,907 research outputs found
A family with extrinsic allergic alveolitis caused by wild city pigeons: A case report
We describe a family in which the mother died of unresolved lung disease
and whose 5 children, some of whom had previous signs of asthma, were
subsequently affected by extrinsic allergic alveolitis caused by contact
with wild city pigeon antigens. The children received systemic
corticosteroids for 1 month and inhaled steroids for 24 months, while
antigen exposure was reduced as much as feasible. This was followed by a
quick clinical recovery and a slow normalization of chest radiographs and
pulmonary function indices, especially of diffusion capacity, during a
follow-up of 24 months. Because pigeon-breeder's lung caused by
free-roaming city pigeons has not been previously described, it remains
unclear whether this family developed the disease because of high antigen
exposure or because of increased susceptibility. None of the supposedly
high-risk human leukocyte antigen types were found in the children.
Whether human leukocyte antigen B7 in 1 child played a role in the course
of the illness remains speculative. It is unknown to what extent
pigeon-breeder's lung caused by nondomestic birds remains undetected and
misdiagnosed as difficult or steroid-resistant asthma. The question
remains whether free-roaming city pigeons are indeed a public health risk.
We suggest that atypical outdoor antigens be considered in all patients
with nonresolving chest disease or therapy-resistant asthma
Self-consistent modelling of hot plasmas within non-extensive Tsallis' thermostatistics
A study of the effects of non-extensivity on the modelling of atomic physics
in hot dense plasmas is proposed within Tsallis' statistics. The electronic
structure of the plasma is calculated through an average-atom model based on
the minimization of the non-extensive free energy.Comment: submitted to "Eur. Phys. J. D
Detuning effects in the one-photon mazer
The quantum theory of the mazer in the non-resonant case (a detuning between
the cavity mode and the atomic transition frequencies is present) is written.
The generalization from the resonant case is far from being direct. Interesting
effects of the mazer physics are pointed out. In particular, it is shown that
the cavity may slow down or speed up the atoms according to the sign of the
detuning and that the induced emission process may be completely blocked by use
of a positive detuning. It is also shown that the detuning adds a potential
step effect not present at resonance and that the use of positive detunings
defines a well-controlled cooling mechanism. In the special case of a mesa
cavity mode function, generalized expressions for the reflection and
transmission coefficients have been obtained. The general properties of the
induced emission probability are finally discussed in the hot, intermediate and
cold atom regimes. Comparison with the resonant case is given.Comment: 9 pages, 8 figure
Slave or sibling: a moral reframing the corporate knowledge sharing community
No Abstract Availabl
Quantitative Behavioural Reasoning for Higher-order Effectful Programs: Applicative Distances (Extended Version)
This paper studies the quantitative refinements of Abramsky's applicative
similarity and bisimilarity in the context of a generalisation of Fuzz, a
call-by-value -calculus with a linear type system that can express
programs sensitivity, enriched with algebraic operations \emph{\`a la} Plotkin
and Power. To do so a general, abstract framework for studying behavioural
relations taking values over quantales is defined according to Lawvere's
analysis of generalised metric spaces. Barr's notion of relator (or lax
extension) is then extended to quantale-valued relations adapting and extending
results from the field of monoidal topology. Abstract notions of
quantale-valued effectful applicative similarity and bisimilarity are then
defined and proved to be a compatible generalised metric (in the sense of
Lawvere) and pseudometric, respectively, under mild conditions
Robust H-infinity filtering for 2-D systems with intermittent measurements
This paper is concerned with the problem of robust H∞ filtering for uncertain two-dimensional (2-D) systems with intermittent measurements. The parameter uncertainty is assumed to be of polytopic type, and the measurements transmission is assumed to be imperfect, which is modeled by a stochastic variable satisfying the Bernoulli random binary distribution. Our attention is focused on the design of an H∞ filter such that the filtering error system is stochastically stable and preserves a guaranteed H∞ performance. This problem is solved in the parameter-dependent framework, which is much less conservative than the quadratic approach. By introducing some slack matrix variables, the coupling between the positive definite matrices and the system matrices is eliminated, which greatly facilitates the filter design procedure. The corresponding results are established in terms of linear matrix inequalities, which can be easily tested by using standard numerical software. An example is provided to show the effectiveness of the proposed approac
Observation of Two New N* Peaks in J/psi -> and Decays
The system in decays of is limited to be
isospin 1/2 by isospin conservation. This provides a big advantage in studying
compared with and experiments which mix
isospin 1/2 and 3/2 for the system. Using 58 million decays
collected with the Beijing Electron Positron Collider, more than 100 thousand
events are obtained. Besides two well known
peaks at 1500 MeV and 1670 MeV, there are two new, clear peaks in
the invariant mass spectrum around 1360 MeV and 2030 MeV. They are the
first direct observation of the peak and a long-sought "missing"
peak above 2 GeV in the invariant mass spectrum. A simple
Breit-Wigner fit gives the mass and width for the peak as MeV and MeV, and for the new peak above 2 GeV
as MeV and MeV, respectively
The Transformation from Translucent into Transparent Rare Earth Ions Doped Oxyfluoride Glass-Ceramics with Enhanced Luminescence
Article reporting a scenario where a translucent Er3+−Yb3+ doped oxyfluoride precursor glass-ceramic (P-GC) becomes transparent with increasing crystal size and crystallinity
Nonresonant Three-body Decays of D and B Mesons
Nonresonant three-body decays of D and B mesons are studied. It is pointed
out that if heavy meson chiral perturbation theory (HMChPT) is applied to the
heavy-light strong and weak vertices and assumed to be valid over the whole
kinematic region, then the predicted decay rates for nonresonant charmless
3-body B decays will be too large and especially B^- --> pi^- K^+ K^- greatly
exceeds the current experimental limit. This can be understood as chiral
symmetry has been applied there twice beyond its region of validity. If HMChPT
is applied only to the strong vertex and the weak transition is accounted for
by the form factors, the dominant B^* pole contribution to the tree-dominated
direct three-body B decays will become small and the branching ratio will be of
order 10^{-6}. The decay modes B^- --> (K^- h^+ h^-)_{NR} and bar{B}^0 -->
(bar{K}^0 h^+h^-)_{NR} for h = pi, K are penguin dominated. We apply HMChPT in
two different cases to study the direct 3-body D decays and compare the results
with experiment. Theoretical uncertainties are discussed.Comment: 24 pages, 2 figures. New experimental results of direct 3-body D
decays as Reported at ICHEP2002 are included. To appear in Phys. Re
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