15,166 research outputs found
Sampling Artifact in Volume Weighted Velocity Measurement.--- II. Detection in simulations and comparison with theoretical modelling
Measuring the volume weighted velocity power spectrum suffers from a severe
systematic error, due to imperfect sampling of the velocity field from
inhomogeneous distribution of dark matter particles/halos in simulations or
galaxies with velocity measurement. This "sampling artifact" depends on both
the mean particle number density and the intrinsic large scale
structure (LSS) fluctuation in the particle distribution. (1) We report robust
detection of this sampling artifact in N-body simulations. It causes %
underestimation of the velocity power spectrum at h/Mpc for samples with
(Mpc/h). This systematic underestimation
increases with decreasing and increasing . Its dependence on the
intrinsic LSS fluctuations is also robustly detected. (2) All these findings
are expected by our theoretical modelling in paper I \cite{Zhang14}. In
particular, the leading order theoretical approximation agrees quantitatively
well with simulation result for (Mpc/h). Furthermore, we provide an ansatz to take high order
terms into account. It improves the model accuracy to % at
h/Mpc over 3 orders of magnitude in and over typical
LSS clustering from to . (3) The sampling artifact is determined by
the deflection field, which is straightforwardly available in both
simulations and data of galaxy velocity. Hence the sampling artifact in the
velocity power spectrum measurement can be self-calibrated within our
framework. By applying such self-calibration in simulations, it becomes
promising to determine the {\it real} large scale velocity bias of
halos with % accuracy, and that of lower mass halos by
better accuracy. ...[abridged]Comment: 11 pages, 11 figures. More arguments added, match the PRD accepted
versio
The anti-sepsis activity of the components of Huanglian Jiedu Decoction with high lipid A-binding affinity
Huanglian Jiedu Decoction (HJD), one of the classic recipes for relieving toxicity and fever, is a common method for treating sepsis in China. However, the effective components of HJD have not yet been identified. This experiment was carried out to elucidate the effective components of HJD against sepsis. Thus, seven fractions from HJD were tested using a biosensor to test their affinity for lipid A. The components obtained that had high lipid A-binding fractions were further separated, and their affinities to lipid A were assessed with the aid of a biosensor. The levels of LPS in the blood were measured, and pathology experiments were conducted. The LPS levels and mRNA expression analysis of TNF-α and IL-6 of the cell supernatant and animal tissue were evaluated to investigate the molecular mechanisms. Palmatine showed the highest affinity to lipid A and was evaluated by in vitro and in vivo experiments. The results of the in vitro and in vivo experiments indicated that the levels of LPS, TNF-α and IL-6 of the palmatine group were significantly lower than those of the sepsis model group (p \u3c 0.01). The group treated with palmatine showed strong neutralizing LPS activity in vivo. The palmatine group exhibited stronger protective activity on vital organs compared to the LPS-induced animal model. This verifies that HJD is a viable treatment option for sepsis given that there are multiple components in HJD that neutralize LPS, decrease the release of IL-6 and TNF-α induced by LPS, and protect vital organs
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