25 research outputs found
To Plate or Not to Plate after a Single- or Two-Level Anterior Cervical Discectomy: Fusion with Cage-Plate Construct or Stand-Alone Cage
Origins of the Ambient Solar Wind: Implications for Space Weather
The Sun's outer atmosphere is heated to temperatures of millions of degrees,
and solar plasma flows out into interplanetary space at supersonic speeds. This
paper reviews our current understanding of these interrelated problems: coronal
heating and the acceleration of the ambient solar wind. We also discuss where
the community stands in its ability to forecast how variations in the solar
wind (i.e., fast and slow wind streams) impact the Earth. Although the last few
decades have seen significant progress in observations and modeling, we still
do not have a complete understanding of the relevant physical processes, nor do
we have a quantitatively precise census of which coronal structures contribute
to specific types of solar wind. Fast streams are known to be connected to the
central regions of large coronal holes. Slow streams, however, appear to come
from a wide range of sources, including streamers, pseudostreamers, coronal
loops, active regions, and coronal hole boundaries. Complicating our
understanding even more is the fact that processes such as turbulence,
stream-stream interactions, and Coulomb collisions can make it difficult to
unambiguously map a parcel measured at 1 AU back down to its coronal source. We
also review recent progress -- in theoretical modeling, observational data
analysis, and forecasting techniques that sit at the interface between data and
theory -- that gives us hope that the above problems are indeed solvable.Comment: Accepted for publication in Space Science Reviews. Special issue
connected with a 2016 ISSI workshop on "The Scientific Foundations of Space
Weather." 44 pages, 9 figure
Antiulcer, wound healing and hepatoprotective activities of the seaweeds Gracilaria crassa, Turbinaria ornata and Laurencia papillosa from the southeast coast of India
STRAIN-RATE EFFECTS ON HIGH-TEMPERATURE FRACTURE-BEHAVIOR OF A 2124AL-SIC(W) COMPOSITE
The high-temperature fracture behavior of a 2124Al-SiC(w) composite compared with a 2124Al alloy was investigated in this study. Axisymmetric tensile tests were carried out over a temperature range from 25-degrees-C to 550-degrees-C and at strain rates from 5 x 10(-5) s-1 to 0.3 s-1. Detailed fractographical observations and cross-sectional microstructure analyses were also made to identify local micromechanical processes of cavity initiation at high temperature. One of the important results is that the cavity initiation sites of the composite are strongly influenced by the strain rate at high temperatures: cavities initiate at whisker ends at low strain rates and at whisker sides at high strain rates. Furthermore, the favored direction of cavity growth is also dependent upon the strain rate, being approximately 45 deg at low strain rates and perpendicular to the tensile axis at high strain rates. Such different local fracture processes at different strain rates are interpreted in terms of the role of the SiC whiskers on the load carrier in the composite at high temperatures.X1114sciescopu