3,884 research outputs found
Intrinsic alignments in the cross-correlation of cosmic shear and CMB weak lensing
We demonstrate that the intrinsic alignment of galaxies with large-scale
tidal fields sources an extra contribution to the recently-detected
cross-correlation of galaxy shear and weak lensing of the microwave background.
The extra term is the analogy of the 'GI' term in standard cosmic shear
studies, and results in a reduction in the amplitude of the cross-correlation.
We compute the intrinsic alignment contribution in linear and non-linear
theory, and show that it can be at roughly the 15% level for the CFHT Stripe 82
redshift distribution, if the canonical amplitude of intrinsic alignments is
assumed. The new term can therefore potentially reconcile the apparently low
value of the measured cross-correlation with standard LCDM. We discuss various
small-scale effects in the signal and the dependence on the source redshift
distribution. We discuss the exciting possibility of self-calibrating intrinsic
alignments with a joint analysis of cosmic shear and weak lensing of the
microwave backgroundComment: 5 pages, 4 figures; Published by MNRAS Letters. Minor corrections to
match the published versio
The impact of our local environment on cosmological statistics
We conduct a thorough investigation into the possibility that residing in an
overdense region of the Universe may induce bias in measurements of the
large-scale structure. We compute the conditional correlation function and
angular power spectrum of density and lensing fluctuations while holding the
local spherically averaged density fixed and show that for Gaussian fields this
has no effect on the angular power at . We identify a range of scales
where a perturbative approach allows analytic progress to be made, and we
compute leading-order conditional power spectra using an Edgeworth expansion
and second-order perturbation theory. We find no evidence for any significant
bias to cosmological power spectra from our local density contrast. We show
that when smoothed over a large region around the observer, conditioning on the
local density typically affects density power spectra by less than a percent at
cosmological distances, below cosmic variance. We find that while typical
corrections to the lensing angular power spectrum can be at the 10% level on
the largest angular scales and for source redshifts , for the
typical redshifts targeted by upcoming wide imaging surveys the corrections are
sub-percent and negligible, in contrast to previous claims in the literature.
Using an estimate of the local spherically averaged density from a composite
galaxy redshift catalogue we find that the corrections from conditioning on our
own local density are below cosmic variance and subdominant to other non-linear
effects. We discuss the potential implications of our results for cosmology and
point out that a measurement of the local density contrast may be used as a
consistency test of cosmological models.Comment: 20 pages, 10 figures. Added new Figure 9 showing (mild) dependence on
smoothing scale. Minor changes to match version published in Physical Review
Garlic Inhibits Inflammation during Dengue Infection
Dengue virus (DENV) is a mosquito-borne flavivirus that causes significant human disease and mortality in the tropics and subtropics. There has been a recent global trend of increased epidemic activity, and DENV infection is considered a serious emerging health problem worldwide. A relatively unexplored approach to develop new treatments for dengue virus infection and the prevention of severe disease development is through investigation of natural medicines. Inflammation plays both beneficial and harmful roles during the host response to dengue virus infection. Several studies have proposed that it is the oxidative stress response induced by dengue virus infection that is responsible for triggering the pro-inflammatory cytokine cascade. Thus, blocking the oxidative stress response and reducing inflammation could together reduce the likelihood of severe disease development. Garlic has been shown to have several health benefits, and many of these are thought to be due to the reduction of inflammation. Garlic has also been shown to have effects on the oxidative stress response and prevent intracellular glutathione depletion. Here, we hypothesized that garlic could reduce inflammation during dengue virus infection through the reduction of the oxidative stress response. Our results indicate that garlic active compounds reduce inflammation during dengue virus infection and show that this reduction is due to the effects on the oxidative stress response. These results suggest that garlic could be used as an alternative treatment for dengue virus infection and for the prevention of severe disease development
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