8,605 research outputs found
The Dark Matter equation of state through cosmic history
Cold Dark Matter (CDM) is a crucial constituent of the current concordance
cosmological model. Having a vanishing equation of state (EoS), its energy
density scales with the inverse cosmic volume and is thus uniquely described by
a single number, its present abundance. We test the inverse cosmic volume law
for Dark Matter (DM) by allowing its EoS to vary independently in eight
redshift bins in the range and . We use the latest measurements
of the Cosmic Microwave Background radiation from the Planck satellite and
supplement them with Baryon Acoustic Oscillation (BAO) data from the 6dF and
SDSS-III BOSS surveys, and with the Hubble Space Telescope (HST) key project
data. We find no evidence for nonzero EoS in any of the eight redshift bins.
With Planck data alone, the DM abundance is most strongly constrained around
matter-radiation equality (95%
c.l.), whereas its present day value is more weakly constrained (95% c.l.). Adding BAO or HST data does not
significantly change the constraint, while
tightens to (95% c.l.) and
(95% c.l.) respectively. Our results constrain for the first time the level of
"coldness" required of the DM across various cosmological epochs and show that
the DM abundance is strictly positive at all times.Comment: 6 pages, 4 figures, changed color scheme for figure
Efficient numerical diagonalization of hermitian 3x3 matrices
A very common problem in science is the numerical diagonalization of
symmetric or hermitian 3x3 matrices. Since standard "black box" packages may be
too inefficient if the number of matrices is large, we study several
alternatives. We consider optimized implementations of the Jacobi, QL, and
Cuppen algorithms and compare them with an analytical method relying on
Cardano's formula for the eigenvalues and on vector cross products for the
eigenvectors. Jacobi is the most accurate, but also the slowest method, while
QL and Cuppen are good general purpose algorithms. The analytical algorithm
outperforms the others by more than a factor of 2, but becomes inaccurate or
may even fail completely if the matrix entries differ greatly in magnitude.
This can mostly be circumvented by using a hybrid method, which falls back to
QL if conditions are such that the analytical calculation might become too
inaccurate. For all algorithms, we give an overview of the underlying
mathematical ideas, and present detailed benchmark results. C and Fortran
implementations of our code are available for download from
http://www.mpi-hd.mpg.de/~globes/3x3/ .Comment: 13 pages, no figures, new hybrid algorithm added, matches published
version, typo in Eq. (39) corrected; software library available at
http://www.mpi-hd.mpg.de/~globes/3x3
Comparative study of gp130 cytokine effects on corticotroph AtT-20 cells - Redundancy or specificity of neuroimmunoendocrine modulators?
Objective: This comparative in vitro study examined the effects of all known gp130 cytokines on murine corticotroph AtT-20 cell function. Methods: Cytokines were tested at equimolar concentrations from 0.078 to 10 nM. Tyrosine phosphorylation of the signal transducer and activator of transcription ( STAT) 3 and STAT1, the STAT-dependent suppressor of cytokine signaling (SOCS)-3 promoter activity, SOCS-3 gene expression, STAT-dependent POMC promoter activity and adrenocorticotropic hormone ( ACTH) secretion were determined. Results: Leukemia inhibitory factor (LIF), human oncostatin M (OSM) and cardiotrophin (CT)-1 (LIFR/gp130 ligands), as well as ciliary neurotrophic factor ( CNTF) and novel neurotrophin1/B-cell stimulating factor-3 (CNTFRalpha/LIFR/gp130 ligands) are potent stimuli of corticotroph cells in vitro. In comparison, interleukin (IL)-6 (IL-6R/gp130 ligand) and IL-11 (IL-11R/gp130 ligand) exhibited only modest direct effects on corticotrophs, while murine OSM (OSMR/gp130 ligand) showed no effect. Conclusion: (i) CNTFR complex ligands are potent stimuli of corticotroph function, comparable to LIFR complex ligands; (ii) IL-6 and IL-11 are relatively weak direct stimuli of corticotroph function; (iii) differential effects of human and murine OSM suggest that LIFR/gp130 (OSMR type I) but not OSMR/gp130 (OSMR type II) are involved in corticotroph signaling. (iv) CT-1 has the hitherto unknown ability to stimulate corticotroph function, and (v) despite redundant immuno-neuroendocrine effects of different gp130 cytokines, corticotroph cells are preferably activated through the LIFR and CNTFR complexes. Copyright (C) 2004 S. Karger AG, Basel
Real-Time Operating System/360
RTOS has a cost savings advantage for real-time applications, such as those with random inputs requiring a flexible data routing facility, display systems simplified by a device independent interface language, and complex applications needing added storage protection and data queuing
Editorial: E-Learning-Strategien für die Hochschullehre
27.04.2015Â | Sabine Seufert (St. Gallen), Martin Ebner, Michael Kopp (Graz) & Bettina Schlass (Amsterdam
The Influence of Conversation, Low-Dose Alcohol and Driving Experience on the Peripheral Vision System
The peripheral vision system plays a very important role in the orientation system. Its task is to detect information and select the relevant from the irrelevant. Many accidents happen when drivers miss important information because their visual field is reduced. One reason for such a reduction is that the driver focuses his attention on something that has nothing to do with his driving. When the cognitive system has insufficient attention at its command, it compensates by neglecting the peripheral vision system and focusing on the central field of vision. Consequently, every action which needs a high degree of attention poses a potential danger, because it reduces the visual field and may cause an accident
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