493 research outputs found
Preparation and properties of the specific anti-influenza virus transfer factor
Specific anti-influenza virus and normal transfer factors prepared in an experimental animal model, the pig, have been tested for their components, characteristics, and activity of known specificity. Two transfer factors are small molecular mixture which consist entirely or partly of polypeptides and polynucleosides. Moreover, the biological activity of transfer factors could be approved by Rosettes test and specific skin test. The study would lay a foundation for the research and development of other specific transfer factor
Self generated randomness, defect wandering and viscous flow in stripe glasses
We show that the competition between interactions on different length scales,
as relevant for the formation of stripes in doped Mott insulators, can cause a
glass transition in a system with no explicitly quenched disorder. We
analytically determine a universal criterion for the emergence of an
exponentially large number of metastable configurations that leads to a finite
configurational entropy and a landscape dominated viscous flow. We demonstrate
that glassines is unambiguously tied to a new length scale which characterizes
the typical length over which defects and imperfections in the stripe pattern
are allowed to wander over long times.Comment: 17 pages, 9 figure
Removing exogenous information using pedigree data
Management of certain populations requires the preservation of its pure genetic background. When, for different reasons, undesired alleles are introduced, the original genetic conformation must be recovered. The present study tested, through computer simulations, the power of recovery (the ability for removing the foreign information) from genealogical data. Simulated scenarios comprised different numbers of exogenous individuals taking partofthe founder population anddifferent numbers of unmanaged generations before the removal program started. Strategies were based on variables arising from classical pedigree analyses such as founders? contribution and partial coancestry. The ef?ciency of the different strategies was measured as the proportion of native genetic information remaining in the population. Consequences on the inbreeding and coancestry levels of the population were also evaluated. Minimisation of the exogenous founders? contributions was the most powerful method, removing the largest amount of genetic information in just one generation.However, as a side effect, it led to the highest values of inbreeding. Scenarios with a large amount of initial exogenous alleles (i.e. high percentage of non native founders), or many generations of mixing became very dif?cult to recover, pointing out the importance of being careful about introgression events in populatio
Dust in Brown Dwarfs IV. Dust formation and driven turbulence on mesoscopic scales
Dust formation in brown dwarf atmospheres is studied by utilising a model for
driven turbulence in the mesoscopic scale regime. We apply a pseudo-spectral
method where waves are created and superimposed within a limited wavenumber
interval. The turbulent kinetic energy distribution follows the Kolmogoroff
spectrum which is assumed to be the most likely value. Such superimposed,
stochastic waves may occur in a convectively active environment. They cause
nucleation fronts and nucleation events and thereby initiate the dust formation
process which continues until all condensible material is consumed. Small
disturbances are found to have a large impact on the dust forming system. An
initially dust-hostile region, which may originally be optically thin, becomes
optically thick in a patchy way showing considerable variations in the dust
properties during the formation process. The dust appears in lanes and curls as
a result of the interaction with waves, i.e. turbulence, which form larger and
larger structures with time. Aiming on a physical understanding of the
variability of brown dwarfs, related to structure formation in substellar
atmospheres, we work out first necessary criteria for small-scale closure
models to be applied in macroscopic simulations of dust forming astrophysical
systems.Comment: A&A accepted, 20 page
Direct evidence of a sub-stellar companion around CT Cha
In our ongoing search for close and faint companions around T Tauri stars, we
found a very faint (Ks=14.9mag, Ks_0=14.4mag) object, just ~2.67" northwest of
the Chamaeleon star-forming region member CT Cha corresponding to a projected
separation of ~440AU at 165+/-30 pc. We show that CT Cha A and this faint
object form a common proper motion pair from data of the VLT Adaptive Optics
(AO) instrument NACO taken in February 2006 and March 2007 and that the
companion is by >=4 sigma significance not a stationary background object. Our
AO integral field spectroscopy with SINFONI in J, and H+K bands yields a
temperature of 2600+/-250K for the companion and an optical extinction of
A_V=5.2+/-0.8mag, when compared to spectra calculated from Drift-Phoenix model
atmospheres. We demonstrate the validity of the model fits by comparison to
several other well-known young sub-stellar objects. Relative flux calibration
of the bands was achieved using photometry from the NACO imaging data. We
conclude that the CT Cha companion is a very low-mass member of Chamaeleon and
very likely a physical companion to CT Cha, as the probability for a by chance
alignment is <=0.01. Due to a prominent Pa-Beta emission in the J-band,
accretion is probably still ongoing onto the CT Cha companion. From temperature
and luminosity (log(Lbol/Lsun)= -2.68+/-0.21), we derive a radius of
R=2.20+0.81-0.60 R_Jup. We find a consistent mass of M=17+/-6 MJup for the CT
Cha companion from both its luminosity and temperature when placed on
evolutionary tracks. Hence, the CT Cha companion is most likely a wide brown
dwarf companion or possibly even a planetary mass object.Comment: 10 pages, 11 figures, accepted for publication in A&
Dynamical Mean Field Theory for Self-Generated Quantum Glasses
We present a many body approach for non-equilibrium behavior and
self-generated glassiness in strongly correlated quantum systems. It combines
the dynamical mean field theory of equilibrium systems with the replica theory
for classical glasses without quenched disorder. We apply this approach to
study a quantized version of the Brazovskii model and find a self-generated
quantum glass that remains in a quantum mechanically mixed state as T -> 0.
This quantum glass is formed by a large number of competing states spread over
an energy region which is determined within our theory.Comment: 10 pages, 4 figure
Spectroscopy across the brown dwarf/planetary mass boundary - I. Near-infrared JHK spectra
With a uniform VLT SINFONI data set of nine targets, we have developed an
empirical grid of J,H,K spectra of the atmospheres of objects estimated to have
very low substellar masses of \sim5-20 MJup and young ages of \sim1-50 Myr.
Most of the targets are companions, objects which are especially valuable for
comparison with atmosphere and evolutionary models, as they present rare cases
in which the age is accurately known from the primary. Based on the sample
youth, all objects are expected to have low surface gravity, and this study
investigates the critical early phases of the evolution of substellar objects.
The spectra are compared with grids of five different theoretical atmosphere
models. This analysis represents the first systematic model comparison with
infrared spectra of young brown dwarfs. The fits to the full JHK spectra of
each object result in a range of best fit effective temperatures of +/-150-300K
whether or not the full model grid or a subset restricted to lower log(g)
values is used. This effective temperature range is significantly larger than
the uncertainty typically assigned when using a single model grid. Fits to a
single wavelength band can vary by up to 1000K using the different models.
Since the overall shape of these spectra is governed more by the temperature
than surface gravity, unconstrained model fits did not find matches with low
surface gravity or a trend in log(g) with age. This suggests that empirical
comparison with spectra of unambiguously young objects targets (such as these
SINFONI data) may be the most reliable method to search for indications of low
surface gravity and youth. For two targets, the SINFONI data are a second epoch
and the data show no variations in morphology over time. The analysis of two
other targets, AB Pic B and CT Cha B, suggests that these objects may have
lower temperatures, and consequently lower masses, than previously estimated.Comment: 15 pages, 13 figure
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