35,218 research outputs found
Subarcsecond Bright Points and Quasi-periodic Upflows Below a Quiescent Filament Observed by the IRIS
Using UV spectra and SJIs from the IRIS, and coronal images and magnetograms
from the Solar Dynamics Observatory (SDO), we present the new features in a
quiescent filament channel: subarcsecond bright points (BPs) and quasi-periodic
upflows. The BPs in the TR have a spatial scale of about 350580 km and
lifetime of more than several tens of minutes. They are located at stronger
magnetic structures in the filament channel, with magnetic flux of about
1010 Mx. Quasi-periodic brightenings and upflows are observed
in the BPs and the period is about 45 min. The BP and the associated
jet-like upflow comprise a "tadpole-shaped" structure. The upflows move along
bright filament threads and their directions are almost parallel to the spine
of the filament. The upflows initiated from the BPs with opposite polarity
magnetic fields have opposite directions. The velocity of the upflows in plane
of sky is about 550 km s. The emission line of Si IV 1402.77 {\AA} at
the locations of upflows exhibits obvious blueshifts of about 530 km
s, and the line profile is broadened with the width of more than 20 km
s. The BPs seem to be the bases of filament threads and the upflows are
able to convey mass for the dynamic balance of the filament. The
"counter-streaming" flows in previous observations may be caused by the
propagation of bi-directional upflows initiated from opposite polarity magnetic
fields. We suggest that quasi-periodic brightenings of BPs and quasi-periodic
upflows result from small-scale oscillatory magnetic reconnections, which are
modulated by solar p-mode waves.Comment: 6 pages, 6 figures, accepted in A&
Variants of the low oxygen sensors EGLN1 and HIF-1AN associated with acute mountain sickness.
Two low oxygen sensors, Egl nine homolog 1 (EGLN1) and hypoxia-inducible factor 1-α inhibitor (HIF-1AN), play pivotal roles in the regulation of HIF-1α, and high altitude adaption may be involved in the pathology of acute mountain sickness (AMS). Here, we aimed to analyze single nucleotide polymorphisms (SNPs) in the untranslated regions of the EGLN1 and HIF-1AN genes and SNPs chosen from a genome-wide adaptation study of the Han Chinese population. To assess the association between EGLN1 and HIF-1AN SNPs and AMS in a Han Chinese population, a case-control study was performed including 190 patients and 190 controls. In total, thirteen SNPs were genotyped using the MassARRAY® MALDI-TOF system. Multiple genetic models were tested; The Akaike's information criterion (AIC) and Bayesian information criterion (BIC) values indicated that the dominant model may serve as the best-fit model for rs12406290 and rs2153364 of significant difference. However, these data were not significant after Bonferroni correction. No significant association was noted between AMS and rs12757362, rs1339894, rs1361384, rs2009873, rs2739513 or rs2486729 before and after Bonferroni correction. Further haplotype analyses indicated the presence of two blocks in EGLN1; one block consists of rs12406290-rs2153364, located upstream of the EGLN1 gene. Carriers of the "GG" haplotype of rs12406290-rs2153364 exhibited an increased risk of AMS after adjustments for age and smoking status. However, no significant association was observed among HIF-1AN 3'-untranslated region (3'-UTR) polymorphisms, haplotype and AMS. Our study indicates that variants in the EGLN1 5'-UTR influence the susceptibility to AMS in a Han Chinese population
Spin Correlations in top quark pair production near threshold at the Linear Collider
We investigate the spin correlations in top quark pair production near
threshold at the linear collider. Comparing with the results above
the threshold region, we find that near the threshold region the off-diagonal
basis, the optimized decomposition of the top quark spins above the threshold
region, does not exist, and the beamline basis is the optimal basis, in which
there are the dominant spin components: the up-down (UD) component for scattering and the down-up (DU) component for scattering can
make up more than 50% of the total cross section, respectively.Comment: 12 pages, 3 figures, minor modification
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