560 research outputs found
Insulin-like growth factor I is an independent coregulatory modulator of natural killer (NK) cell activity.
We aimed to investigate the natural killer (NK) cell activity in
hGH-deficient adults and to analyze the effect of insulin-like growth
factor (IGF)-I in uivo and in vitro on NK cell activity. NK cell activity
was measured in a 4-h nonisotopic assay with europium-labeled and
cryopreserved K-562 cells. NK-cell numbers were measured after
incubation with murine monoclonal CD3 and CD16 antibodies by flow
cytometry analysis. In a cross-sectional study, the basal and interferon-
p (IFN-P) stimulated (1000 IU/ml) NK cell activity of 15 hGHdeficient
patients and 15 age- and sex-matched controls was measured.
The percentages and absolute numbers of CD3./16+ NK-cells
were not significantly different in the patient vs. control group. The
basal and IFN-P stimulated NK cell activity however was significantly
decreased in the patient vs. control group at all effecter/target
(E/T) cell ratios from 12.5-100 (e.g. 17 ? 3 vs. 28 ? 3% lysis without
IFN-P, P < 0.05, and 42 t 4 vs. 57 2 4% lysis with IFN-0, P < 0.05;
both at E/T 50). IGF-I levels of patients and controls showed a significant
positive correlation with NK cell activity (r = 0.37; P < 0.05).
In an IGF-I in vitro study (IGF-I in vitro 250-1250 kg/L), the basal and
IFN-P stimulated NK cell activity of 13 hGH-deficient patients and of
18 normal subjects was significantly enhanced by IGF-I in vitro (e.g.
GH-deficient patients: 9 ? 2 us. 10 2 2% lysis without IFN-P, P < 0.05
and 25 + 4 vs. 30 + 4% lysis with IFN-/3, P < 0.005; and normal
subjects: 15 + 3 vs. 23 ? 3% lysis without IFN-/3, P < 0.001 and 35 2
4 us. 44 + 5% lysis with IFN-P, P < 0.001; both at IGF-I 500 pg/L).
In summary, in our cross-sectional study, adult GH-deficient patients
showed a significantly lower basal and IFN-P stimulated NK cell
activity than matched controls, despite equal NK cell numbers. IGF-I
levels of patients and controls showed a weak positive correlation with
NK cell activity. In an in vitro study, IGF-I significantly enhanced
basal and IFN-P stimulated NK cell activity of hGH-deficient patients
and also of normal subjects. The decreased NK cell activity in GHdeficient
patients may be caused at least in part by low serum IGF-I
levels. IGF-I appears to be an independent coregulatory modulator of
NK cell activity. (Endocrinology 137: 5332-5336, 1996
X-ray Line Emission from the Hot Stellar Wind of theta 1 Ori C
We present a first emission line analysis of a high resolution X-ray spectrum
of the stellar wind of theta 1 Ori C obtained with the High Energy Transmission
grating Spectrometer onboard the Chandra X-ray Observatory. The spectra are
resolved into a large number of emission lines from H- and He-like O, Ne, Mg,
Si, S, Ar and Fe ions. The He-like Fe XXV and Li-like Fe XXIV appear quite
strong indicating very hot emitting regions. From H/He flux ratios, as well as
from Fe He/Li emission measure ratios we deduce temperatures ranging from 0.5
to 6.1 x 10^7 K. The He-triplets are very sensitive to density as well. At
these temperatures the relative strengths of the intercombination and forbidden
lines indicate electron densities well above 10^12 cm^-3. The lines appear
significantly broadened from which we deduce a mean velocity of 770 km/s with a
spread between 400 and 2000 km/s. Along with results of the deduced emission
measure we conclude that the X-ray emission could originate in dense and hot
regions with a characteristic size of less then 4 x 10^10 cm.Comment: 4 pages, 3 figure
Constraint Molecular Dynamics approach to Fermionic systems
We propose a Constraint Molecular Dynamics model for Fermionic system. In
this approach the equations of motion of wave packets for the nuclear many-body
problem are solved by imposing that the one-body occupation probability
can assume only values less or equal to 1. This condition
reflects the Fermionic nature of the studied systems and it is implemented with
a fast algorithm which allows also the study of the heaviest colliding system.
The parameters of the model have been chosen to reproduce the average binding
energy and radii of nuclei in the mass region . Some comparison
to data is given.Comment: 11 pages and 6 figure
The Ionized Stellar Wind in Vela X-1 During Eclipse
We present a first analysis of a high resolution X-ray spectrum of the
ionized stellar wind of Vela X-1 during eclipse. The data were obtained with
the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray
Observatory. The spectrum is resolved into emission lines with fluxes between
0.02 and 1.04x10^4 ph/cm^2/s. We identify lines from a variety of charge
states, including fluorescence lines from cold material, a warm photoionized
wind. We can exclude signatures from collisionally ionized plasmas. For the
first time we identify fluorescence lines from L-shell ions from lower Z
elements. We also detect radiative recombination continua from a kT = 10 eV
(1.2 x 10^5 K) photoionized optically thin gas. The fluorescence line fluxes
infer the existence of optically thick and clumped matter within or outside the
warm photoionized plasma.Comment: 4 pages, 2 figures, accepted by ApJ letter
The value based portfoliomanagement in response to REACh:a manual of different strategies for the chemical industry
The registration, evaluation and authorisation of chemical substances in the context of the European regulation called REACh influence the profit of the chemical industry. If the chemical enterprises want to keep their competitiveness and the availability of products in the Europeanmarket they have to pursue a REACh-strategy. By using a value based portfoliomanagement they are able to analyse their portfolio, to identify profitable and non-profitable strategic business units (SBUs) and to find adequate strategies for each of them
Variational Approach to Real-Time Evolution of Yang-Mills Gauge Fields on a Lattice
Applying a variational method to a Gaussian wave ansatz, we have derived a
set of semi-classical evolution equations for SU(2) lattice gauge fields, which
take the classical form in the limit of a vanishing width of the Gaussian wave
packet. These equations are used to study the quantum effects on the classical
evolutions of the lattice gauge fields.Comment: LaTeX, 12 pages, 5 figures contained in a separate uuencoded file,
DUKE-TH-93-4
Large scale kinematics and dynamical modelling of the Milky Way nuclear star cluster
Within the central 10pc of our Galaxy lies a dense nuclear star cluster
(NSC), and similar NSCs are found in most nearby galaxies. Studying the
structure and kinematics of NSCs reveals the history of mass accretion of
galaxy nuclei. Because the Milky Way (MW) NSC is at a distance of only 8kpc, we
can spatially resolve the MWNSC on sub-pc scales. This makes the MWNSC a
reference object for understanding the formation of all NSCs. We have used the
NIR long-slit spectrograph ISAAC (VLT) in a drift-scan to construct an
integral-field spectroscopic map of the central 9.5 x 8pc of our Galaxy. We use
this data set to extract stellar kinematics both of individual stars and from
the unresolved integrated light spectrum. We present a velocity and dispersion
map from the integrated light and model these kinematics using kinemetry and
axisymmetric Jeans models. We also measure CO bandhead strengths of 1,375
spectra from individual stars. We find kinematic complexity in the NSCs radial
velocity map including a misalignment of the kinematic position angle by 9
degree counterclockwise relative to the Galactic plane, and indications for a
rotating substructure perpendicular to the Galactic plane at a radius of 20" or
0.8pc. We determine the mass of the NSC within r = 4.2pc to 1.4 x 10^7 Msun. We
also show that our kinematic data results in a significant underestimation of
the supermassive black hole (SMBH) mass. The kinematic substructure and
position angle misalignment may hint at distinct accretion events. This
indicates that the MWNSC grew at least partly by the mergers of massive star
clusters. Compared to other NSCs, the MWNSC is on the compact side of the r_eff
- M_NSC relation. The underestimation of the SMBH mass might be caused by the
kinematic misalignment and a stellar population gradient. But it is also
possible that there is a bias in SMBH mass measurements obtained with
integrated light.Comment: 20 pages, 19 Figures, Accepted for publication in A&
Simulating Diffuse Light in Galaxy Clusters
Using N-body simulations, we have modeled the production and evolution of low
surface brightness, diffuse intra-cluster light (ICL) in galaxy clusters. By
creating simulated observations of the clusters we have measured the evolution
of the ICL luminosity throughout the dynamical history of the clusters. We find
that ICL production tends to occur in short, discrete events, which correlate
very strongly with strong, small-scale interactions and accretions between
groups within the clusters.Comment: 5 pages, 2 figures; includes 1 color figure. To appear in ESO
Astrophysics Symposia: "Groups of Galaxies in the Nearby Universe
Observation of lattice waves through observation of the photoluminescence Blinking in InGaN Quantum Well devices
The photoluminescence of III-V wide band-gap semiconductors as InGaN is
characterized by local intensity fluctuations, known as 'blinking points', that
despite decades of research are not yet completely understood. In this letter
we report experimental data and a theoretical interpretation that suggests they
are caused by the interference of thermal vibrations of the Quantum Well
lattice. With far-field optical tests we could observe the lower frequency tail
of these interference waves and study their dynamics as they propagate up to
distances of several tens of microns.Comment: 4 pages, 4 figure
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