THE COOL COMPONENT AND THE DICHOTOMY, LATERAL EXPANSION, AND AXIAL ROTATION OF SOLAR X-RAY JETS

2013 ◽  
Vol 769 (2) ◽  
pp. 134 ◽  
Author(s):  
Ronald L. Moore ◽  
Alphonse C. Sterling ◽  
David A. Falconer ◽  
Dominic Robe
Keyword(s):  
Axial Rotation ◽  
Lateral Expansion ◽  
Cool Component ◽  
X Ray

Is intervertebral disc degeneration related to segmental instability? An evaluation with two different grading systems based on clinical imaging

2017 ◽  
Vol 59 (3) ◽  
pp. 327-335 ◽  
Author(s):  
David Volkheimer ◽  
Fabio Galbusera ◽  
Christian Liebsch ◽  
Sabine Schlegel ◽  
Friederike Rohlmann ◽  
...  
Keyword(s):  
Intervertebral Disc Degeneration ◽  
Statistical Significance ◽  
Axial Rotation ◽  
Spinal Motion ◽  
X Ray ◽  
Grading Systems ◽  
Flexion Extension ◽  
The Difference ◽  
Magnetic Resonance Imaging Mri

Background Several in vitro studies investigated how degeneration affects spinal motion. However, no consensus has emerged from these studies. Purpose To investigate how degeneration grading systems influence the kinematic output of spinal specimens. Material and Methods Flexibility testing was performed with ten human T12-S1 specimens. Degeneration was graded using two different classifications, one based on X-ray and the other one on magnetic resonance imaging (MRI). Intersegmental rotation (expressed by range of motion [ROM] and neutral zone [NZ]) was determined in all principal motion directions. Further, shear translation was measured during flexion/extension motion. Results The X-ray grading system yielded systematically lesser degeneration. In flexion/extension, only small differences in ROM and NZ were found between moderately degenerated motion segments, with only NZ for the MRI grading reaching statistical significance. In axial rotation, a significant increase in NZ for moderately degenerated segments was found for both grading systems, whereas the difference in ROM was significant only for the MRI scheme. Generally, the relative increases were more pronounced for the MRI classification compared to the X-ray grading scheme. In lateral bending, only relatively small differences between the degeneration groups were found. When evaluating shear translations, a non-significant increase was found for moderately degenerated segments. Motion segment segments tended to regain stability as degeneration progressed without reaching the level of statistical significance. Conclusion We found a fair agreement between the grading schemes which, nonetheless, yielded similar degeneration-related effects on intersegmental kinematics. However, as the trends were more pronounced using the Pfirrmann classification, this grading scheme appears superior for degeneration assessment.

scholarly journals Magnetic Reconnection as the Origin of Galactic Ridge X-Ray Emission

1998 ◽  
Vol 188 ◽  
pp. 269-270 ◽  
Author(s):  
S. Tanuma ◽  
T. Yokoyama ◽  
T. Kudoh ◽  
K. Shibata ◽  
R. Matsumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Galactic Plane ◽  
Thermal Emission ◽  
Mhd Equations ◽  
Magnetic Islands ◽  
Cool Component ◽  
X Ray ◽  
Hot Plasma ◽  
Helical Tubes

We present a scenario for the origin of the hot plasma in our Galaxy, as a model of a strong X-ray emission (LX(2 – 10keV) ~ 1038 erg s−1), called Galactic Ridge X-ray Emission (GRXE), which has been observed near the Galactic plane. GRXE is thermal emission from hot component (~ 7 keV) and cool component (~ 0.8 keV). Observations suggest that the hot component is diffuse, and is not escaping away freely. Both what heats the hot component and what confines it in the Galactic ridge are still remained puzzling, while the cool component is believed to be made by supernovae. We propose a new scenario: the hot component of GRXE plasma is heated by magnetic reconnection, and confined in the helical magnetic field produced by magnetic reconnection or in the current sheet and magnetic field. We solved also the 2-dimensional magnetohydrodynamic (MHD) equations numerically to study how the magnetic reconnection creates hot plasmas and magnetic islands (helical tubes), and how the magnetic islands confine the hot plasmas in Galaxy. We conclude that the magnetic reconnection is able to heat up the cool component to hot component of GRXE plasma if the magnetic field is localized into intense flux tube with Blocal ~ 30 μG (the volume filling factor of f ~ 0.1).

scholarly journals ASCA Observation of Groups of Galaxies

1998 ◽  
Vol 188 ◽  
pp. 327-328 ◽  
Author(s):  
Y. Tawara ◽  
S. Sato ◽  
A. Furuzawa ◽  
K. Yamashita ◽  
K. Isobe ◽  
...  
Keyword(s):  
Spectral Properties ◽  
Abundance Ratio ◽  
Compact Groups ◽  
Cool Component ◽  
X Ray ◽  
Groups Of Galaxies

Based on the ASCA observations, the X-ray features like spatial extentions and spectral properties of their component were analyzed for nearby four compact groups of galaxies; HCG62, NGC2300 group, HCG42 and HCG48. We found wide variety in their X-ray features. One of the brightest source of HCG62 shows the presence of cool component and enhanced abundance at its center, while HCG42 shows less extention and low abundance ratio of α-element to iron. For NGC 2300 group, we also found interesting feature which may be related to galaxy-intragroup medium interaction.

Lateral Growth Expansion of 4H/6H-SiС M-Plane Pseudo Fiber Crystals by Hot Wall CVD Epitaxy

2012 ◽  
Vol 717-720 ◽  
pp. 33-36 ◽  
Author(s):  
Andrew J. Trunek ◽  
Philip G. Neudeck ◽  
Andrew A. Woodworth ◽  
J. Anthony Powell ◽  
David J. Spry ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Lateral Growth ◽  
Lateral Expansion ◽  
X Ray ◽  
Initial Analysis ◽  
White Beam

Lateral expansion of small mixed polytype 4H/6H-SiC and 6H-SiC slivers were realized by hot wall chemical vapor deposition (HWCVD). Small slivers cut from m-oriented (11 ̅00) SiC boule slices containing regions of 4H and 6H-SiC or just single polytype 6H-SiC were exposed to HWCVD conditions using standard silane/propane chemistry for a period of up to eight hours. The slivers exhibited approximately 1500 μm (1.5 mm) of total lateral expansion. Initial analysis by synchrotron white beam x-ray topography (SWBXT) confirms, that the lateral growth was homoepitaxial, matching the polytype of the respective underlying region of the seed sliver.

Structural Characterization of Lateral-grown 6H-SiC a/m-plane Seed Crystals by Hot Wall CVD Epitaxy

2014 ◽  
Vol 1693 ◽  
Author(s):  
Ouloide Yannick Goue ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Andrew J. Trunek ◽  
Philip G. Neudeck ◽  
...  
Keyword(s):  
Grown Crystal ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Seed Crystal ◽  
Lateral Expansion ◽  
X Ray ◽  
Seed Crystals ◽  
High Resolution Tem ◽  
Crystal Fibers

ABSTRACTThe performance of commercially available silicon carbide (SiC) power devices is limited due to inherently high density of screw dislocations (SD), which are necessary for maintaining polytype during boule growth and commercially viable growth rates. The NASA Glenn Research Center (GRC) has recently proposed a new bulk growth process based on axial fiber growth (parallel to the c-axis) followed by lateral expansion (perpendicular to the c-axis) for producing multi-faceted m-plane SiC boules that can potentially produce wafers with as few as one SD per wafer. In order to implement this novel growth technique, the lateral homoepitaxial growth expansion of a SiC fiber without introducing a significant number of additional defects is critical. Lateral expansion is being investigated by hot wall chemical vapor deposition (HWCVD) growth of 6H-SiC a/m-plane seed crystals (0.8mm x 0.5mm x 15mm) designed to replicate axially grown SiC single crystal fibers. The post-growth crystals exhibit hexagonal morphology with approximately 1500 μm (1.5 mm) of total lateral expansion. Preliminary analysis by synchrotron white beam x-ray topography (SWBXT) confirms that the growth was homoepitaxial, matching the polytype of the respective underlying region of the seed crystal. Axial and transverse sections from the as-grown crystal samples were characterized in detail by a combination of SWBXT, transmission electron microscopy (TEM) and Raman spectroscopy to map defect types and distribution. X-ray diffraction analysis indicates the seed crystal contained stacking disorders and this appears to have been reproduced in the lateral growth sections. Analysis of the relative intensity for folded transverse acoustic (FTA) and optical (FTO) modes on the Raman spectra indicate the existence of stacking faults (SFs). Further, the density of stacking faults is higher in the seed than in the grown crystal. Bundles of dislocations are observed propagating from the seed in m-axis lateral directions. Contrast extinction analysis of these dislocation lines reveals they are edge type basal plane dislocations that track the growth direction. Polytype phase transition and stacking faults were observed by high-resolution TEM (HRTEM), in agreement with SWBXT and Raman scattering.

scholarly journals Radiation dose optimized lateral expansion of the field of view in synchrotron radiation X-ray tomographic microscopy

2010 ◽  
Vol 17 (5) ◽  
pp. 590-599 ◽  
Author(s):  
David Haberthür ◽  
Christoph Hintermüller ◽  
Federica Marone ◽  
Johannes C. Schittny ◽  
Marco Stampanoni
Keyword(s):  
Synchrotron Radiation ◽  
Radiation Dose ◽  
Field Of View ◽  
Lateral Expansion ◽  
X Ray

scholarly journals Vertebral instability of lumbar spine and its neurological presentations

Pain medicine ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 37-42
Author(s):  
A. M. Vitkovskyi
Keyword(s):  
Lumbar Spine ◽  
Sagittal Plane ◽  
Clinical Signs ◽  
Axial Rotation ◽  
Intervertebral Discs ◽  
Linear Displacement ◽  
Patient Treatment ◽  
Spinal Motion ◽  
X Ray ◽  
Surgery Department

 Background. The research results of data of 57 patients with vertebral instability of lumbar spine with neurological presentations are presented. Patients were on in-patient treatment at the Vertebral surgery department of Institute of Traumatology and Orthopedics (Kyiv) in 2010–2014. Research object. The aim of the research was to determine the features of clinical signs and X-ray measures depending on type and stage of instability in lumbar spine. Materials and methods. The research is based on the analysis of management of 57 patients with lumbar spine instability. The management consisted of anamnesis, examination of patients, X-ray of spine, MRI and CT. The majority of patients were males. There were 35 (61.4 %) males, 22 (38.6 %) females among all of the patients. Due to the data of the research it was inquired that the spine instability was detected frequently in the most employable age, from 20 to 44 years – 30 (52.6 %) cases. Results and discussion. The spine instability is clinical and radiographic manifestation of pathological removability of contiguous vertebras due to each other. This resulted in lesion of vertebras and adjoined vessels and nerves, caused by inadequate supporting system of spinal motion segments. Failure of spinal motion segments develops mainly in degenerative and dystrophic disorders resulted in acute or chronic congestions influenced by microtraumas. Development of secondary lesions of spine and spinal radixes are affected by deformation of spine and spinal channel. Emerging of pathological processes is accompanied by orthopedic and neurological presentations, that requiring surgical correction. Conclusions. Instability of VMS is caused by structure alteration of intervertebral discs, aquatics and processes joints and a part of vertebral arc between joints. Clinical signs depend on the level of localization and the stage of spine instability. Among patients with spine instability the manifestation of radixes lesions were on the 1st place – 29 (50.9 %) cases, on the 2nd place – lesions of lumbago – 19 (33.3 %) cases. X-ray features of instability are: enlargement of linear displacement of vertebral body in sagittal plane more than 4.5 mm, segmental axial rotation of vertebra – more than 40°.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

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