3,765 research outputs found
Superconductivity in the Chalcogens up to Multimegabar Pressures
Highly sensitive magnetic susceptibility techniques were used to measure the
superconducting transition temperatures in S up to 231(5) GPa. S
transforms to a superconductor with T of 10 K and has a discontinuity in
T_c dependence at 160 GPa corresponding to bco to beta-Po phase transition.
Above this pressure T_c in S has a maximum reaching about 17.3(+/-0.5) K at 200
GPa and then slowly decreases with pressure to 15 K at 230 GPa.
This trend in the pressure dependence parallels the behavior of the heavier
members Se and Te. Superconductivity in Se was also observed from 15 to 25 GPa
with T_c changing from 4 to 6 K and above 150 GPa with T_c of 8 K.
Similiarities in the T_c dependences for S, Se, and Te, and the implications
for oxygen are discussed.Comment: 4 pages, 10 figure
Incidental Malrotation in Adolescent Diagnosed with Appendicitis
17-year-old male patient with a history of autism presenting with right lower quadrant pain that started in the morning. The appendix was not able to be visualized by ultrasonography. An abdominal and pelvic CT with contrast showed a dilated appendix with surrounding inflammation. Malrotation was not identified on CT Scan. Patient was transferred to a nearby Children’s Hospital for laparoscopic appendectomy. During the procedure, the pediatric surgeon noted that initially, neither the appendix nor cecum was present in the right lower quadrant. This case represents an uncommon finding for a patient in the adolescent age group
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High-Pressure X-ray Diffraction and Raman Spectroscopy of Ice VIII
In situ high-pressure/low-temperature synchrotron x-ray diffraction and optical Raman spectroscopy were used to examine the structural properties, equation of state, and vibrational dynamics of ice VIII. The x-ray measurements show that the pressure-volume relations remain smooth up to 23 GPa at 80 K. Although there is no evidence for structural changes to at least 14 GPa, the unit-cell axial ratio c/a undergoes changes at 10-14 GPa. Raman measurements carried out at 80 K show that the nu(Tz)A(1g)+nu Tx,yEg lattice modes for the Raman spectra of ice VIII in the lower-frequency regions (50-800 cm(-1)) disappear at around 10 GPa, and then a new peak of similar to 150 cm(-1) appears at 14 GPa. The combined data provide evidence for a transition beginning near 10 GPa. The results are consistent with recent synchrotron far-IR measurements and theoretical calculations. The decompressed phase recovered at ambient pressure transforms to low-density amorphous ice when heated to similar to 125 K.Engineering and Applied Science
Plasma waves observed at low altitudes in the tenuous Venus nightside ionosphere
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95128/1/grl7140.pd
Cosmic Ray Spallation in Radio-Quiet Active Galactic Nuclei: A Case Study of NGC 4051
We investigate conditions for and consequences of spallation in radio-quiet
Seyfert galaxies. The work is motivated by the recent discovery of significant
line emission at 5.44 keV in Suzaku data from NGC 4051. The energy of the new
line suggests an identification as Cr I Ka emission, however the line is much
stronger than would be expected from material with cosmic abundances, leading
to a suggestion of enhancement owing to nuclear spallation of Fe by low energy
cosmic rays from the active nucleus. We find that the highest abundance
enhancements are likely to take place in gas out of the plane of the accretion
disk and that timescales for spallation could be as short as a few years. The
suggestion of a strong nuclear flux of cosmic rays in a radio-quiet Seyfert
galaxy is of particular interest in light of the recent suggestion from Pierre
Auger Observatory data that ultra-high-energy cosmic rays may originate in such
sources.Comment: 14 pages, 1 figure. Accepted for publication in The Astrophysical
Journa
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