2,159 research outputs found
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FT-IR spectroscopy of CAI and chondrules in primitive chondrites: techniques and first results
From the Introduction: Here we present preliminary mid-infrared spectra of CAI, chondrules and matrix from the CV3.2 carbonaceous chondrite Allende. This is part of our ongoing project to compile a database of infrared and optical spectra of minerals and components of primitive meteorites. These spectra should allow a better comparison with spectra from astronomical sources e.g. from dust
and molecular clouds or young solar systems
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Infrared spectroscopy of chondrites and their components: a link between meteoritics and astronomy?
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Mid-infrared spectroscopy of CAI and AOA from the Allende CV3.2 chondrite
Mid-infrared spectra of bulk CAI from the CV3.2 chondrite Allende are presented and compared with astronomical spectra of cometary dust, zodiacal light,the circumstellar disk of beta Pictoris and dust around the red supergiant PR Per
Aerosol Data Sources and Their Roles within PARAGON
We briefly but systematically review major sources of aerosol data, emphasizing suites of measurements that seem most likely to contribute to assessments of global aerosol climate forcing. The strengths and limitations of existing satellite, surface, and aircraft remote sensing systems are described, along with those of direct sampling networks and ship-based stations. It is evident that an enormous number of aerosol-related observations have been made, on a wide range of spatial and temporal sampling scales, and that many of the key gaps in this collection of data could be filled by technologies that either exist or are expected to be available in the near future. Emphasis must be given to combining remote sensing and in situ active and passive observations and integrating them with aerosol chemical transport models, in order to create a more complete environmental picture, having sufficient detail to address current climate forcing questions. The Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON) initiative would provide an organizational framework to meet this goal
Asymptotic Giant Branch Variables in the Galaxy and the Local Group
AGB variables, particularly the large amplitude Mira type, are a vital step
on the distance scale ladder. They will prove particularly important in the era
of space telescopes and extremely large ground-based telescopes with adaptive
optics, which will be optimized for infrared observing. Our current
understanding of the distances to these stars is reviewed with particular
emphasis on improvements that came from Hipparcos as well as on recent work on
Local Group galaxies. In addition to providing the essential calibration for
extragalactic distances Gaia may also provide unprecedented insight into the
poorly understood mass-loss process itself.Comment: Accepted for publication in Astrophysics and Space Science. From a
presentation at the conference "The Fundamental Cosmic Distance Scale: State
of the Art and Gaia Perspective, Naples May 2011. 8 Pages, 9 Figure
All-Sky spectrally matched UBVRI-ZY and u'g'r'i'z' magnitudes for stars in the Tycho2 catalog
We present fitted UBVRI-ZY and u'g'r'i'z' magnitudes, spectral types and
distances for 2.4M stars, derived from synthetic photometry of a library
spectrum that best matches the Tycho2 BtVt, NOMAD Rn and 2MASS JHK_{2/S}
catalog magnitudes. We present similarly synthesized multi-filter magnitudes,
types and distances for 4.8M stars with 2MASS and SDSS photometry to g<16
within the Sloan survey region, for Landolt and Sloan primary standards, and
for Sloan Northern (PT) and Southern secondary standards.
The synthetic magnitude zeropoints for BtVt, UBVRI, ZvYv, JHK_{2/S},
JHK_{MKO}, Stromgren uvby, Sloan u'g'r'i'z' and ugriz are calibrated on 20
calspec spectrophotometric standards. The UBVRI and ugriz zeropoints have
dispersions of 1--3%, for standards covering a range of color from -0.3 < V-I <
4.6; those for other filters are in the range 2--5%.
The spectrally matched fits to Tycho2 stars provide estimated 1-sigma errors
per star of ~0.2, 0.15, 0.12, 0.10 and 0.08 mags respectively in either UBVRI
or u'g'r'i'z'; those for at least 70% of the SDSS survey region to g<16 have
estimated 1-sigma errors per star of ~0.2, 0.06, 0.04, 0.04, 0.05 in u'g'r'i'z'
or UBVRI.
The density of Tycho2 stars, averaging about 60 stars per square degree,
provides sufficient stars to enable automatic flux calibrations for most
digital images with fields of view of 0.5 degree or more. Using several such
standards per field, automatic flux calibration can be achieved to a few
percent in any filter, at any airmass, in most workable observing conditions,
to facilitate inter-comparison of data from different sites, telescopes and
instruments.Comment: 36 pages, 30 figures, 3 printed tables, several electronic tables,
accepted PASP Dec 201
Hypercalcemia associated with a parathyroid cyst.
Parathyroid cysts are rare. When they do occur they usually have no demonstrable endocrine function, but may cause respiratory distress by tracheal compression or may be mistakenly diagnosed as thyroid carcinomas or adenomas. We report a case of a parathyroid cyst which presented with hypercalcemia. CASE REPORT: A fifty eight year old man undergoing routine investigations was found to have hypercalcaemia. His calcium level was elevated to 3.63 mmol/l and the serum parathyroid hormone level was 18.4 pmol/l (normal range 1.0- 5.3). Serum alkaline phosphatase was at the upper limit of normal at 1 1 3U/1. X-ray of the renal tract revealed no evidence of calcification. He was asymptomatic and had no palpable neck mass. Ultrasound examination revealed a 3 cm cyst-like structure inferior and posterior to the left lobe of the thyroid, with a well defined wall approximately 2 mm thick. Exploration of the neck revealed a large cyst (6.5 x 5 x 3 cm), which was removed and found to weigh 57 g. Three other parathyroid glands with a normal appearance were found. Macroscopic examination of the removed specimen showed a smooth lined cyst containing greasy, pearly material. Histology revealed a fibrous lined cyst, containing several islands of parathyroid tissue with clear cell cytology and moderate nuclear pleomorphism. Post-operatively serum calcium returned to normal. The patient was discharged on the fourth post-operative day. DISCUSSION Many theories have been advanced regarding the aetiology of parathyroid cysts. Goris1 was the first to report a case. Nylander2 has suggested that they arise from remnants of the third or fourth pharangeal pouch or are vestigia
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