72 research outputs found
Influenza Virus Vaccination in Germany – Results of the »German Health Update« study (GEDA) 2009
Data on influenza vaccination coverage was collected from the telephone survey GEDA 2009. The analysed data show that vaccine coverage in season 2007/08 in target groups was still low
Anti-Müllerian hormone concentrations in female rabbits and its relation to spay status, pseudopregnancy and ovarian follicle numbers
Anti-Müllerian hormone (AMH), known for its role during foetal sexual differentia- tion, is secreted by the Sertoli cells in males and the granulosa cells in females during post-natal life. As serum AMH concentrations correlate with follicle numbers, AMH is utilized as a marker of ovarian reserve in many species. In dogs and cats, AMH is used as a diagnostic tool to determine spay or neuter status. In the available literature, no research regarding serum AMH levels in rabbits has been published yet. The objec- tives of the present study were to (1) measure serum AMH concentrations in female rabbits and investigate the value of AMH as a diagnostic tool to differentiate between spayed and intact does and (2) relate measured AMH levels to pseudopregnancy and ovarian follicle numbers. For AMH measurement, serum samples were obtained from sexually intact (n = 64) and spayed ( n = 22) female rabbits. Spayed does were of various breeds; intact rabbits were Zika hybrid rabbits. In the intact does, AMH measurement was complemented by determination of progesterone levels, gynae - cological examination and histopathological evaluation of the uterus and ovaries, in- cluding follicle counts. Serum AMH and progesterone concentrations were measured using a human-based chemiluminescence immunoassay (CLIA) and an enzyme-linked fluorescence assay (ELFA), respectively. Depending on progesterone levels, sexually intact does were classified into follicular (n = 52) or luteal phase ( n = 12). Median serum AMH levels were 1.53 ng/ml (range 0.77–3.36 ng/ml) in intact and 0.06 ng/ ml (range ≤0.01–0.23 ng/ml) in spayed does. AMH concentrations between the in- tact and spayed rabbits differed significantly and did not overlap (p < .001). Receiver operating characteristic (ROC) curve analysis yielded a sensitivity and specificity of 100% for a cut-off level of 0.50 ng/ml. Follicular or luteal phase had no significant influence on measured AMH levels (t = 0.061, df = 62, p = .951). While the number of secondary follicles correlated significantly with AMH concentrations (r s = 0.410, p = .001), the number of primary or antral follicles did not ( r s = 0.241, p = .055 and r s = 0.137, p = .281, respectively). In conclusion, a single determination of serum AMH concentrations was adequate to distinguish spayed from intact female rabbits. Among sexually intact individuals, whether does were in follicular or luteal phase had no sig - nificant influence on measured serum AMH concentrations. The relationship between small growing follicles and AMH levels as described in other species could be partially confirmed, as secondary follicles correlated significantly with AM
Double and triple calix[4]arenis connected via the oxygen functions
New macrocyclic molecules are described containing two or three p-tert-butylcalix[4]arene subunits connected via their oxygen atoms. These macrocycles are available by two general methods which are capable of producing assemblies with bridges of varying rigidity and length
Dynamical heterogeneities in a supercooled Lennard-Jones liquid
We present the results of a large scale molecular dynamics computer
simulation study in which we investigate whether a supercooled Lennard-Jones
liquid exhibits dynamical heterogeneities. We evaluate the non-Gaussian
parameter for the self part of the van Hove correlation function and use it to
identify ``mobile'' particles. We find that these particles form clusters whose
size grows with decreasing temperature. We also find that the relaxation time
of the mobile particles is significantly shorter than that of the bulk, and
that this difference increases with decreasing temperature.Comment: 8 pages of RevTex, 4 ps figure
Growth of perturbations in an expanding universe with Bose-Einstein condensate dark matter
We study the growth of perturbations in an expanding Newtonian universe with
Bose-Einstein condensate dark matter. We first ignore special relativistic
effects and derive a differential equation governing the evolution of the
density contrast in the linear regime taking into account quantum pressure and
self-interaction. This equation can be solved analytically in several cases. We
argue that an attractive self-interaction can enhance the Jeans instability and
fasten the formation of structures. Then, we take into account pressure effects
(coming from special relativity) in the evolution of the cosmic fluid and add
the contribution of radiation, baryons and dark energy (cosmological constant).
For a BEC dark matter with repulsive self-interaction (positive pressure) the
scale factor increases more rapidly than in the standard \Lambda CDM model
where dark matter is pressureless while for a BEC dark matter with attractive
self-interaction (negative pressure) it increases less rapidly. We study the
linear development of the perturbations in these two cases and show that the
perturbations grow faster in a BEC dark matter than in a pressureless dark
matter. This confirms a recent result of Harko (2011). Finally, we consider a
"dark fluid" with a generalized equation of state p=(\alpha \rho + k \rho
^2)c^2 having a component p=k \rho ^2 c^2 similar to a BEC dark matter and a
component p=\alpha \rho c^2 mimicking the effect of the cosmological constant
(dark energy). We find optimal parameters that give a good agreement with the
standard \Lambda CDM model assuming a finite cosmological constant
Computer Simulations of Supercooled Liquids and Glasses
After a brief introduction to the dynamics of supercooled liquids, we discuss
some of the advantages and drawbacks of computer simulations of such systems.
Subsequently we present the results of computer simulations in which the
dynamics of a fragile glass former, a binary Lennard-Jones system, is compared
to the one of a strong glass former, SiO_2. This comparison gives evidence that
the reason for the different temperature dependence of these two types of glass
formers lies in the transport mechanism for the particles in the vicinity of
T_c, the critical temperature of mode-coupling theory. Whereas the one of the
fragile glass former is described very well by the ideal version of
mode-coupling theory, the one for the strong glass former is dominated by
activated processes. In the last part of the article we review some simulations
of glass formers in which the dynamics below the glass transition temperature
was investigated. We show that such simulations might help to establish a
connection between systems with self generated disorder (e.g. structural
glasses) and quenched disorder (e.g. spin glasses).Comment: 37 pages of Latex, 11 figures, to appear as a Topical Review article
in J. Phys.: Condens. Matte
Radial structure, inflow and central mass of stationary radiative galaxy clusters
We analyse the radial structure of self-gravitating spheres consisting of multiple interpenetrating fluids, such as the X-ray emitting gas and the dark halo of a galaxy cluster. In these dipolytropic models, the adiabatic dark matter sits in equilibrium, while the gas develops a gradual, smooth, quasi-stationary cooling flow. Both affect and respond to the collective gravitational field. We find that all subsonic, radially continuous, steady solutions require a non-zero minimum central point mass. For Mpc-sized haloes with 7–10 effective degrees of freedom (F2), the minimum central mass is compatible with observations of supermassive black holes. Smaller gas mass influxes enable smaller central masses for wider ranges of F2. The halo comprises a sharp spike around the central mass, embedded within a core of nearly constant density (at 101–102.5 kpc scales), with outskirts that attenuate and naturally truncate at finite radius (several Mpc). The gas density resembles a broken power law in radius, but the temperature dips and peaks within the dark core. A finite minimum temperature occurs due to gravitational self-warming, without cold mass dropout nor needing regulatory heating. X-ray emission from the intracluster medium mimics a β-model plus bright compact nucleus. Near-sonic points in the gas flow are bottlenecks to the allowed steady solutions; the outermost are at kpc scales. These sites may preferentially develop cold mass dropout during strong perturbations off equilibrium. Within the sonic point, the profile of gas specific entropy is flatter than s∝r1/2, but this is a shallow ramp and not an isentropic core. When F2 is large, the inner halo spike is only marginally Jeans stable in the central parsec, suggesting that a large non-linear disturbance could trigger local dark collapse on to the central object
Measurement of the 92,93,94,100Mo(γ,n) reactions by Coulomb Dissociation
The Coulomb Dissociation (CD) cross sections of the stable isotopes 92,94,100Mo and of the unstable isotope 93Mo were measured at the LAND/R3B setup at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of 92,94Mo and 96,98Ru in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction 93Mo(γ,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the 94Mo(γ,n) reaction is presented. Further analysis will complete the experimental database for the (γ,n) production chain of the p-isotopes of molybdenum
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