scholarly journals 22 GHz Observations of Southern H2O Sources

1974 ◽  
Vol 27 (3) ◽  
pp. 417 ◽  
Author(s):  
JL Caswell ◽  
RA Batchelor ◽  
RF Haynes ◽  
WK Huchtmeier
Keyword(s):  
Hii Regions ◽  
Intensity Changes ◽  
Considerable Intensity

The discovery of three new H20 sources associated with HII regions is reported. Observations of other southern H20 sources show, in several instances, considerable intensity changes over a 20-month interval.

A Tilting Procedure to Enhance Compositional Contrast and Reduce Residual Bragg Contrast in EFTEM Imaging of Planar Interfaces

2000 ◽  
Vol 6 (S2) ◽  
pp. 156-157
Author(s):  
K.T. Moore ◽  
E.A. Stach ◽  
J.M. Howe ◽  
D.C. Elbert ◽  
D.R. Veblen
Keyword(s):  
Electron Scattering ◽  
Planar Interface ◽  
Zone Axis ◽  
Crystalline Material ◽  
Energy Losses ◽  
Inelastic Electron ◽  
Diffraction Contrast ◽  
Background Removal ◽  
Intensity Changes ◽  
Elemental Maps

When acquiring energy-filtered TEM (EFTEM) images of a crystalline material, the detrimental effects of diffraction contrast can often be seen in raw energy-filtered images (EFI) (i.e., pre-edge and post-edge images), jump-ratio images and elemental maps as residual diffraction contrast. Residual diffraction contrast occurs in raw EFI because of plural scattering (i.e., inelastic-elastic and elastic-inelastic electron scattering) and in jump-ratio images and elemental maps because background removal procedures often are unable to completely account for intensity changes due to dynamical effects (elastic scattering) that occur between pre-edge and post-edge images acquired at different energy losses.It is demonstrated in these experiments that, when examining a planar interface, EFTEM images have increased compositional contrast and decreased residual diffraction contrast when the sample is oriented so that the interface is parallel to the electron beam, but not directly on a zone axis.

Preliminary Observations of Interstellar Sodium D-Line Absorption towards the Carina Nebula

1980 ◽  
Vol 4 (1) ◽  
pp. 95-97 ◽  
Author(s):  
J. B. Whiteoak ◽  
F. F. Gardner
Keyword(s):  
High Resolution ◽  
Hii Regions ◽  
Early Type ◽  
Interstellar Clouds ◽  
Carina Nebula ◽  
Line Absorption ◽  
General Investigation ◽  
Early Type Stars ◽  
Resolution Study

As part of a general investigation of interstellar clouds associated with southern HII regions we have begun a high-resolution study of the sodium D-line absorption in the directions of early-type stars that are likely to be associated with or located behind the clouds.

14 years of 6.7 GHz periodic methanol maser observations towards G188.95+0.89

2019 ◽  
Vol 15 (S356) ◽  
pp. 393-394
Author(s):  
Martin M. Mutie ◽  
Paul Baki ◽  
James O. Chibueze ◽  
Khadija El Bouchefry
Keyword(s):  
Radio Telescope ◽  
Exponential Decay ◽  
Hii Regions ◽  
Monitoring Period ◽  
Methanol Maser ◽  
Spectral Components ◽  
Methanol Masers ◽  
Compact Hii Regions

AbstractWe report the results of 14 years of monitoring of G188.95+0.89 periodic 6.7 GHz methanol masers using the Hartebeesthoek 26-m radio telescope. G188.95+0.89 (S252, AFGL5180) is a radio-quiet methanol maser site that is often interpreted as precursors of ultra-compact HII regions or massive protostar sites. At least five bright spectral components were identified. The maser feature at 11.36 km s-1 was found to experience an exponential decay during the monitoring period. The millimetre continuum reveals two cores associated with the source.

Dentate nucleus signal intensity changes on T1-weighted MRI after repeated administrations of linear and macrocyclic gadolinium-based contrast agents: a pediatric intraindividual case-control study

2021 ◽  
pp. 028418512110188
Author(s):  
Kerem Ozturk ◽  
David Nascene
Keyword(s):  
Repeated Measures ◽  
Signal Intensity ◽  
Dentate Nucleus ◽  
Pearson Correlation ◽  
Gadopentetate Dimeglumine ◽  
Control Groups ◽  
Significant Difference ◽  
Intensity Changes ◽  
Cerebellar Peduncle ◽  
Pediatric Brain

Background An association between consecutive administrations of macrocyclic gadolinium-based contrast agent (mcGBCA) gadobutrol and linear (L)-GBCA gadopentetate dimeglumine and gadolinium retention in the pediatric brain remains incompletely understood. Purpose To compare signal intensity (SI) changes in the dentate nucleus (DN) on unenhanced T1-weighted imaging (T1WI) in children who obtained mcGBCA gadobutrol with those who had previously received L-GBCA gadopentetate dimeglumine. Material and Methods This retrospective study included 27 children who received L-GBCA gadopentetate dimeglumine followed by mcGBCA gadobutrol and two different control groups matched for age and sex for both periods, each involving 27 individuals with no GBCA administration from January 2010 to January 2020. DN-to-middle cerebellar peduncle (MCP) SI ratios on T1WI were determined. A repeated-measures ANOVA was performed to compare the T1WI SI ratio between children exposed to GBCA in each of the two periods and controls. Pearson correlation analysis was conducted to determine any correlation between SI ratios and confounding parameters. Results T1WI SI ratio was significantly higher in those who had only L-GBCA (1.005±0.087) or subsequent mcGBCA gadobutrol (1.002±0.104) than in control groups 1 (0.927±0.041; P<0.001) and 2 (0.930±0.041; P=0.002), respectively, but no significant difference of the T1WI SI ratio was noted between L-GBCA period and subsequent mcGBCA gadobutrol period ( P=0.917). T1WI SI ratios and the L-GBCA administration number revealed a modest but significant correlation (correlation coefficient=0.034; P=0.016). Conclusion Previous administration of gadopentetate dimeglumine is associated with increased T1WI SI in the DN, while subsequent administration of gadobutrol does not demonstrate any additional SI increase in the pediatric brain.

A Thermal Source with Strong 1612 MHz OH Emission

1969 ◽  
Vol 1 (5) ◽  
pp. 211-212
Author(s):  
B. J. Robinson ◽  
W. M. Goss ◽  
R. N. Manchester
Keyword(s):  
Ground State ◽  
Hii Regions ◽  
Thermal Source ◽  
Strong Source ◽  
Galactic Longitude

During 1968 we have found at Parkes several types of emission in the lines of the 18 cm quadruplet of the ground-state OH molecule. This note describes a strong source of 1612 MHz emission near galactic longitude 331°.OH emission was originally detected in the vicinity of HII regions, and a search of a large number of HII regions showed that about a third had associated OH emission. This type of emission is usually strongest at 1665 MHz, and is also seen at 1667 MHz and weakly on one of the satellite lines.

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