34 research outputs found
Subsurface Flows in and Around Active Regions with Rotating and Non-rotating Sunspots
The temporal variation of the horizontal velocity in subsurface layers
beneath three different types of active regions is studied using the technique
of ring diagrams. In this study, we select active regions (ARs) 10923, 10930,
10935 from three consecutive Carrington rotations: AR 10930 contains a
fast-rotating sunspot in a strong emerging active region while other two have
non-rotating sunspots with emerging flux in AR 10923 and decaying flux in AR
10935. The depth range covered is from the surface to about 12 Mm. In order to
minimize the influence of systematic effects, the selection of active and quiet
regions is made so that these were observed at the same heliographic locations
on the solar disk. We find a significant variation in both components of the
horizontal velocity in active regions as compared to quiet regions. The
magnitude is higher in emerging-flux regions than in the decaying-flux region,
in agreement with earlier findings. Further, we clearly see a significant
temporal variation in depth profiles of both zonal and meridional flow
components in AR 10930, with the variation in the zonal component being more
pronounced. We also notice a significant influence of the plasma motion in
areas closest to the rotating sunspot in AR 10930 while areas surrounding the
non-rotating sunspots in all three cases are least affected by the presence of
the active region in their neighborhood.Comment: Solar Physics (in press), includes 11 figure
The Solar Cycle: A new prediction technique based on logarithmic values
A new prediction technique based on logarithmic values is proposed to predict
the maximum amplitude (Rm) of a solar cycle from the preceding minimum aa
geomagnetic index (aamin). The correlation between lnRm and lnaamin (r = 0.92)
is slightly stronger than that between Rm and aamin (r = 0.90). From this
method, cycle 24 is predicted to have a peak size of Rm (24) = 81.7(1\pm13.2%).
If the suggested error in aa (3 nT) before 1957 is corrected, the correlation
coefficient between Rm and aamin (r = 0.94) will be slightly higher, and the
peak of cycle 24 is predicted much lower, Rm(24) = 52.5\pm13.1. Therefore, the
prediction of Rm based on the relationship between Rm and aamin depends greatly
on the accurate measurement of aa.Comment: 6 pages, 3 figures, Accepted for publication in Astrophysics & Space
Scienc
Histone hyperacetylation disrupts core gene regulatory architecture in rhabdomyosarcoma
Core regulatory transcription factors (CR TFs) orchestrate the placement of super-enhancers (SEs) to activate transcription of cell-identity specifying gene networks, and are critical in promoting cancer. Here, we define the core regulatory circuitry of rhabdomyosarcoma and identify critical CR TF dependencies. These CR TFs build SEs that have the highest levels of histone acetylation, yet paradoxically the same SEs also harbor the greatest amounts of histone deacetylases. We find that hyperacetylation selectively halts CR TF transcription. To investigate the architectural determinants of this phenotype, we used absolute quantification of architecture (AQuA) HiChIP, which revealed erosion of native SE contacts, and aberrant spreading of contacts that involved histone acetylation. Hyperacetylation removes RNA polymerase II (RNA Pol II) from core regulatory genetic elements, and eliminates RNA Pol II but not BRD4 phase condensates. This study identifies an SE-specific requirement for balancing histone modification states to maintain SE architecture and CR TF transcription
Collision velocities between offshore supply vessels and fixed platforms
SIGLELD:6026.982(NMI-R--126). / BLDSC - British Library Document Supply CentreGBUnited Kingdo