27,380 research outputs found
Contact urticaria to giraffe hair
Background: Immediate-type hypersensitivity to animal proteins is a common problem in people occupationally exposed to animals. Methods: A 19-year-old female working as a voluntary zookeeper in her off-time suffered from hives on her forearms following contact to the fur of a giraffe. For diagnostic evaluation, skin prick tests, assessment of specific serum IgE antibodies, and basophil activation tests were performed. Results: Skin prick tests with a standard series of common aeroallergens were positive for various pollens. Prick testing with native materials was positive for extracts of hair from two different giraffe subspecies in the patient, but not in control subjects. By CAP-FEIA, no specific serum IgE antibodies to dander of a large variety of animals were found in the patient. In the basophil activation test, expression of the activation marker CD63 was induced by extract of giraffe hair on the cells from the patient, but not on those from unaffected controls. Conclusions: This patient suffers from an `exotic' immediate-type contact allergy to giraffe hair. Copyright (C) 2005 S. Karger AG, Basel
GiRaFFE: An Open-Source General Relativistic Force-Free Electrodynamics Code
We present GiRaFFE, the first open-source general relativistic force-free
electrodynamics (GRFFE) code for dynamical, numerical-relativity generated
spacetimes. GiRaFFE adopts the strategy pioneered by McKinney and modified by
Paschalidis and Shapiro to convert a GR magnetohydrodynamic (GRMHD) code into a
GRFFE code. In short, GiRaFFE exists as a modification of IllinoisGRMHD, a
user-friendly, open-source, dynamical-spacetime GRMHD code. Both GiRaFFE and
IllinoisGRMHD leverage the Einstein Toolkit's highly-scalable infrastructure to
make possible large-scale simulations of magnetized plasmas in strong,
dynamical spacetimes on adaptive-mesh refinement (AMR) grids. We demonstrate
that GiRaFFE passes a large suite of both flat and curved-spacetime code tests
passed by a number of other state-of-the-art GRFFE codes, and is thus ready for
production-scale simulations of GRFFE phenomena of key interest to relativistic
astrophysics.Comment: 23 pages, 4 figures. Consistent with published versio
Early-type objects in NGC6611 and Eagle Nebula
An important question about Be stars is whether Be stars are born as Be stars
or not. It is necessary to observe young clusters to answer this question.
Observations of stars in NGC6611 and the star-formation region of Eagle Nebula
have been carried out with the ESO-WFI in slitless spectroscopic mode and at
the VLT-GIRAFFE. The targets for the GIRAFFE observations were pre-selected
from the literature and our catalogue of emission-line stars (ELS) based on the
WFI study. GIRAFFE observations allowed us to study accurately the population
of the early-type stars with and without emission lines. For this study, we
determined the fundamental parameters of OBA stars. We also studied the status
of the objects (main sequence or pre-main sequence stars) by using IR data,
membership probabilities, and location in HR diagrams. The nature of the
early-type ELS in M16 is derived. The slitless observations with the WFI
clearly indicate a small number of ELS in M16. We observed with GIRAFFE 101 OBA
stars, among them 9 are ELS with circumstellar emission in Halpha. We found
that: W080 could be a new He-strong star, like W601. W301 is a possible
classical Be star, W503 is a mass-transfer eclipsing binary with an accretion
disk, and the other ones are possible Herbig Ae/Be stars. We also found that
the rotational velocities of main sequence B stars are 18% lower than those of
pre-main sequence B stars, in good agreement with theory about the evolution of
rotational velocities. Combining different indications and technics, we found
that 27% of the B-type stars are binaries. We also redetermined the age of
NGC6611 found equal to 1.2--1.8 Myears in good agreement with the most recent
determinations.Comment: Accepted by A&A, english not yet correcte
NGC 362: another globular cluster with a split red giant branch
We obtained FLAMES GIRAFFE+UVES spectra for both first and second-generation
red giant branch (RGB) stars in the globular cluster (GC) NGC 362 and used them
to derive abundances of 21 atomic species for a sample of 92 stars. The
surveyed elements include proton-capture (O, Na, Mg, Al, Si), alpha-capture
(Ca, Ti), Fe-peak (Sc, V, Mn, Co, Ni, Cu), and neutron-capture elements (Y, Zr,
Ba, La, Ce, Nd, Eu, Dy). The analysis is fully consistent with that presented
for twenty GCs in previous papers of this series. Stars in NGC 362 seem to be
clustered into two discrete groups along the Na-O anti-correlation, with a gap
at [O/Na] 0 dex. Na-rich, second generation stars show a trend to be more
centrally concentrated, although the level of confidence is not very high. When
compared to the classical second-parameter twin NGC 288, with similar
metallicity, but different horizontal branch type and much lower total mass,
the proton-capture processing in stars of NGC 362 seems to be more extreme,
confirming previous analysis. We discovered the presence of a secondary RGB
sequence, redder than the bulk of the RGB: a preliminary estimate shows that
this sequence comprises about 6% of RGB stars. Our spectroscopic data and
literature photometry indicate that this sequence is populated almost
exclusively by giants rich in Ba, and probably rich in all s-process elements,
as found in other clusters. In this regards, NGC 362 joins previously studied
GCs like NGC 1851, NGC 6656 (M 22), and NGC 7089 (M 2).Comment: 16 pages, 23 figures, 11 tables, accepted for publication on
Astronomy and Astrophysic
Terzan 8: a Sagittarius-flavoured globular cluster
Massive globular clusters (GCs) contain at least two generations of stars
with slightly different ages and clearly distinct light elements abundances.
The Na-O anticorrelation is the best studied chemical signature of multiple
stellar generations. Low-mass clusters appear instead to be usually chemically
homogeneous. We are investigating low-mass GCs to understand what is the lower
mass limit where multiple populations can form, mainly using the Na and O
abundance distribution. We used VLT/FLAMES spectra of giants in the low-mass,
metal-poor GC Terzan 8, belonging to the Sagittarius dwarf galaxy, to determine
abundances of Fe, O, Na, alpha-, Fe-peak, and neutron-capture elements in six
stars observed with UVES and 14 observed with GIRAFFE. The average metallicity
is [Fe/H]=-2.27+/-0.03 (rms=0.08), based on the six high-resolution UVES
spectra. Only one star, observed with GIRAFFE, shows an enhanced abundance of
Na and we tentatively assign it to the second generation. In this cluster, at
variance with what happens in more massive GCs, the second generation seems to
represent at most a small minority fraction. We discuss the implications of our
findings, comparing Terzan 8 with the other Sgr dSph GCs, to GCs and field
stars in the Large Magellanic Cloud, Fornax, and in other dwarfs galaxies.Comment: 15 pages, 12 figures, 10 tables; accepted for publication on
Astronomy and Astrophysic
The Gaia-ESO Survey: the selection function of the Milky Way field stars
The Gaia-ESO Survey was designed to target all major Galactic components
(i.e., bulge, thin and thick discs, halo and clusters), with the goal of
constraining the chemical and dynamical evolution of the Milky Way. This paper
presents the methodology and considerations that drive the selection of the
targeted, allocated and successfully observed Milky Way field stars. The
detailed understanding of the survey construction, specifically the influence
of target selection criteria on observed Milky Way field stars is required in
order to analyse and interpret the survey data correctly. We present the target
selection process for the Milky Way field stars observed with VLT/FLAMES and
provide the weights that characterise the survey target selection. The weights
can be used to account for the selection effects in the Gaia-ESO Survey data
for scientific studies. We provide a couple of simple examples to highlight the
necessity of including such information in studies of the stellar populations
in the Milky Way.Comment: 18 pages, 19 figures, Accepted for publication in MNRAS (April 25,
2016
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