17,192 research outputs found
Nearly Scale-Invariant Spectrum of Adiabatic Fluctuations May be from a Very Slowly Expanding Phase of the Universe
In this paper we construct an expanding phase with phantom matter, in which
the scale factor expands very slowly but the Hubble parameter increases
gradually, and assume that this expanding phase could be matched to our late
observational cosmology by the proper mechanism. We obtain the nearly
scale-invariant spectrum of adiabatic fluctuations in this scenario, different
from the simplest inflation and usual ekpyrotic/cyclic scenario, the tilt of
nearly scale-invariant spectrum in this scenario is blue. Although there exists
an uncertainty surrounding the way in which the perturbations propagate through
the transition in our scenario, which is dependent on the detail of possible
"bounce" physics, compared with inflation and ekpyrotic/cyclic scenario, our
work may provide another feasible cosmological scenario generating the nearly
scale-invariant perturbation spectrum.Comment: 4 pages, no figures, to appear in Phys. Rev. D. Many thanks for
referee's kind comments and criticism
Hepatitis C virus 3'UTR regulates viral translation through direct interactions with the host translation machinery.
The 3' untranslated region (3'UTR) of hepatitis C virus (HCV) messenger RNA stimulates viral translation by an undetermined mechanism. We identified a high affinity interaction, conserved among different HCV genotypes, between the HCV 3'UTR and the host ribosome. The 3'UTR interacts with 40S ribosomal subunit proteins residing primarily in a localized region on the 40S solvent-accessible surface near the messenger RNA entry and exit sites. This region partially overlaps with the site where the HCV internal ribosome entry site was found to bind, with the internal ribosome entry site-40S subunit interaction being dominant. Despite its ability to bind to 40S subunits independently, the HCV 3'UTR only stimulates translation in cis, without affecting the first round translation rate. These observations support a model in which the HCV 3'UTR retains ribosome complexes during translation termination to facilitate efficient initiation of subsequent rounds of translation
- …