141 research outputs found
Development of Eosinophilic Airway Inflammation and Airway Hyperresponsiveness in Mast Cell–deficient Mice
Mast cells are the main effector cells of immediate hypersensitivity and anaphylaxis. Their role in the development of allergen-induced airway hyperresponsiveness (AHR) is controversial and based on indirect evidence. To address these issues, mast cell–deficient mice (W/W v) and their congenic littermates were sensitized to ovalbumin (OVA) by intraperitoneal injection and subsequently challenged with OVA via the airways. Comparison of OVA-specific immunoglobulin E (IgE) levels in the serum and numbers of eosinophils in bronchoalveolar lavage fluid or lung digests showed no differences between the two groups of mice. Further, measurements of airway resistance and dynamic compliance at baseline and after inhalation of methacholine were similar. These data indicate that mast cells or IgE–mast cell activation is not required for the development of eosinophilic inflammation and AHR in mice sensitized to allergen via the intraperitoneal route and challenged via the airways
The integral monodromy of hyperelliptic and trielliptic curves
We compute the \integ/\ell and \integ_\ell monodromy of every irreducible
component of the moduli spaces of hyperelliptic and trielliptic curves. In
particular, we provide a proof that the \integ/\ell monodromy of the moduli
space of hyperelliptic curves of genus is the symplectic group
\sp_{2g}(\integ/\ell). We prove that the \integ/\ell monodromy of the
moduli space of trielliptic curves with signature is the special
unitary group \su_{(r,s)}(\integ/\ell\tensor\integ[\zeta_3])
Detecting metal-rich intermediate-age globular clusters in NGC4570 using K-band photometry
“The original publication is available at www.springerlink.com”. Copyright Springer. DOI: 10.1007/s10509-009-0093-8Globular cluster systems (GCSs) of most early-type galaxies feature two peaks in their optical colour distributions. Blue-peak globular clusters (GCs) are believed to be old and metal-poor, whereas the ages, metallicities, and the origin of the red-peak GCs are still being debated. We obtained deep K-band photometry and combined it with Hubble Space Telescope observations in g and z to yield a full spectral energy distribution from the optical to the near-infrared. This now allows us to break the age–metallicity degeneracy. We used our evolutionary synthesis models galev for star clusters to compute a large grid of models with different metallicities and a wide range of ages. Comparing these models to our observations revealed a large population of intermediate-age (1–3 Gyr) and metal-rich (≈solar-metallicity) GCs, that will give us further insights into the formation history of this galaxy.Peer reviewe
Optimal prediction for moment models: Crescendo diffusion and reordered equations
A direct numerical solution of the radiative transfer equation or any kinetic
equation is typically expensive, since the radiative intensity depends on time,
space and direction. An expansion in the direction variables yields an
equivalent system of infinitely many moments. A fundamental problem is how to
truncate the system. Various closures have been presented in the literature. We
want to study moment closure generally within the framework of optimal
prediction, a strategy to approximate the mean solution of a large system by a
smaller system, for radiation moment systems. We apply this strategy to
radiative transfer and show that several closures can be re-derived within this
framework, e.g. , diffusion, and diffusion correction closures. In
addition, the formalism gives rise to new parabolic systems, the reordered
equations, that are similar to the simplified equations.
Furthermore, we propose a modification to existing closures. Although simple
and with no extra cost, this newly derived crescendo diffusion yields better
approximations in numerical tests.Comment: Revised version: 17 pages, 6 figures, presented at Workshop on Moment
Methods in Kinetic Gas Theory, ETH Zurich, 2008 2 figures added, minor
correction
Inflation: flow, fixed points and observables to arbitrary order in slow roll
I generalize the inflationary flow equations of Hoffman and Turner to
arbitrary order in slow roll. This makes it possible to study the predictions
of slow roll inflation in the full observable parameter space of tensor/scalar
ratio , spectral index , and running . It also becomes
possible to identify exact fixed points in the parameter flow. I numerically
evaluate the flow equations to fifth order in slow roll for a set of randomly
chosen initial conditions and find that the models cluster strongly in the
observable parameter space, indicating a ``generic'' set of predictions for
slow roll inflation. I comment briefly on the the interesting proposed
correspondence between flow in inflationary parameter space and renormalization
group flow in a boundary conformal field theory.Comment: 16 pages, 7 figures. LaTeX. V4: Fixed important error in numerical
constant in the second-order slow roll expressions for the observables r, n,
and dn/dlog(k). See footnote after Eq. (48). New figures, minor changes to
conclusions. Supersedes version published in Phys. Rev.
Caracterização molecular de estafilococos isolados de vacas com mastite subclínica e ordenhadores
Globular cluster luminosity function as distance indicator
Globular clusters are among the first objects used to establish the distance
scale of the Universe. In the 1970-ies it has been recognized that the
differential magnitude distribution of old globular clusters is very similar in
different galaxies presenting a peak at M_V ~ -7.5. This peak magnitude of the
so-called Globular Cluster Luminosity Function has been then established as a
secondary distance indicator. The intrinsic accuracy of the method has been
estimated to be of the order of ~0.2 mag, competitive with other distance
determination methods. Lately the study of the Globular Cluster Systems has
been used more as a tool for galaxy formation and evolution, and less so for
distance determinations. Nevertheless, the collection of homogeneous and large
datasets with the ACS on board HST presented new insights on the usefulness of
the Globular Cluster Luminosity Function as distance indicator. I discuss here
recent results based on observational and theoretical studies, which show that
this distance indicator depends on complex physics of the cluster formation and
dynamical evolution, and thus can have dependencies on Hubble type, environment
and dynamical history of the host galaxy. While the corrections are often
relatively small, they can amount to important systematic differences that make
the Globular Cluster Luminosity Function a less accurate distance indicator
with respect to some other standard candles.Comment: Accepted for publication in Astrophysics and Space Science. Review
paper based on the invited talk at the conference "The Fundamental Cosmic
Distance Scale: State of the Art and Gaia Perspective", Naples, May 2011. (13
pages, 8 figures
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