1,083 research outputs found
No evidence for an early seventeenth-century Indian sighting of Keplers supernova (SN1604)
In a recent paper Sule et al. (Astronomical Notes, vol. 332 (2011), 655)
argued that an early 17th-century Indian mural of the constellation Sagittarius
with a dragon-headed tail indicated that the bright supernova of 1604 was also
sighted by Indian astronomers. In this paper it will be shown that this
identification is based on a misunderstanding of traditional Islamic
astrological iconography and that the claim that the mural represents an early
17th-century Indian sighting of the supernova of 1604 has to be rejected.Comment: 7 pages, 6 figures. To appear in Astronomical Notes, vol. 334, issue
5 (2013), DOI number 1172
Three editions of the Star Catalogue of Tycho Brahe
Tycho Brahe completed his catalogue with the positions and magnitudes of 1004
fixed stars in 1598. This catalogue circulated in manuscript form. Brahe edited
a shorter version with 777 stars, printed in 1602, and Kepler edited the full
catalogue of 1004 stars, printed in 1627. We provide machine-readable versions
of the three versions of the catalogue, describe the differences between them
and briefly discuss their accuracy on the basis of comparison with modern data
from the Hipparcos Catalogue. We also compare our results with earlier analyses
by Dreyer (1916) and Rawlins (1993), finding good overall agreement. The
magnitudes given by Brahe correlate well with modern values, his longitudes and
latitudes have error distributions with widths of about 2 arcmin, with excess
numbers of stars with larger errors (as compared to Gaussian distributions), in
particular for the faintest stars. Errors in positions larger than 10 arcmin,
which comprise about 15 per cent of the entries, are likely due to computing or
copying errors.Comment: Accepted by Astronomy and Astrophysics; 24 pages; 63 figures; 3
machine readable tables made available at CD
The Star Catalogue of Hevelius
The catalogue by Johannes Hevelius with the positions and magnitudes of 1564
entries was published by his wife Elisabeth Koopman in 1690. We provide a
machine-readable version of the catalogue, and briefly discuss its accuracy on
the basis of comparison with data from the modern Hipparcos Catalogue. We
compare our results with an earlier analysis by Rybka (1984), finding good
overall agreement. The magnitudes given by Hevelius correlate well with modern
values. The accuracy of his position measurements is similar to that of Brahe,
with sigma=2 arcmin for with more errors larger than 5 arcmin than expected for
a Gaussian distribution. The position accuracy decreases slowly with magnitude.
The fraction of stars with position errors larger than a degree is 1.5 per
cent, rather smaller than the fraction of 5 per cent in the star catalogue of
Brahe.Comment: Accepted by Astronomy and Astrophysics; 23 pages; 62 figures; 1 table
made accessible via CD
Early star catalogues of the southern sky: De Houtman, Kepler (Second and Third Classes), and Halley
De Houtman in 1603, Kepler in 1627 and Halley in 1679 published the earliest
modern catalogues of the southern sky. We provide machine-readable versions of
these catalogues, make some comparisons between them, and briefly discuss their
accuracy on the basis of comparison with data from the modern Hipparcos
Catalogue. We also compare our results for De Houtman with those by Knobel
(1917) finding good overall agreement. About half of the about 200 new stars
(with respect to Ptolemaios) added by De Houtman are in twelve new
constellations, half in old constellations like Centaurus, Lupus and Argo. The
right ascensions and declinations given by De Houtman have error distributions
with widths of about 40 arcmin, the longitudes and latitudes given by Kepler
have error distributions with widths of about 45 arcmin. Halley improves on
this by more than an order of magnitude to widths of about 3 arcmin, and all
entries in his catalogue can be identified. The measurement errors of Halley
are due to a systematic deviation of his sextant (increasing with angle to 2
arcmin at 60 degrees) and random errors of 0.7 arcmin. The position errors in
the catalogue of Halley are dominated by the position errors in the reference
stars, which he took from Brahe.Comment: 26 pages, 58 figures. Tables will become available at CDS once the
article appears in Astronomy and Astrophysic
Surface plasmon resonance immunosensors: sensitivity considerations
Some aspects of improving surface plasmon resonance response in immunosensing applications are considered. Both from calculations and experiments, it was found that maximum sensitivity is obtained for a silver layer about 55 nm thick in direct contact with the species to be quantified. Application of an intermediate layer with high permittivity can be useful in suppressing background responses. Experimentally, a protein surface-coverage fraction of ca. 0.1 could be measured, corresponding to ca. 10−10 mol1−1 antibody
Sputum Induction in Children Is Feasible and Useful in a Bustling General Hospital Practice
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The Jeroen Bosch Hospital funded this study.Peer reviewedPublisher PD
Realizing orders as group rings
An order is a commutative ring that as an abelian group is finitely generated
and free. A commutative ring is reduced if it has no non-zero nilpotent
elements. In this paper we use a new tool, namely, the fact that every reduced
order has a universal grading, to answer questions about realizing orders as
group rings. In particular, we address the Isomorphism Problem for group rings
in the case where the ring is a reduced order. We prove that any non-zero
reduced order can be written as a group ring in a unique ``maximal'' way,
up to isomorphism. More precisely, there exist a ring and a finite abelian
group , both uniquely determined up to isomorphism, such that
as rings, and such that if is a ring and is a group, then
as rings if and only if there is a finite abelian group such that as rings and as groups. Computing and for
given can be done by means of an algorithm that is not quite
polynomial-time. We also give a description of the automorphism group of in
terms of and
Automatizacija u geodeziji
Automatizacija u geodeziji
Complications in subfascial endoscopic perforating vein surgery: A report of two cases
AbstractSubfascial endoscopic perforating vein surgery is a safe method for the division of incompetent perforating veins. Nevertheless, we report two cases with unfortunate complications: the posterior tibial artery and tibial nerve were damaged during the procedures. In one patient this resulted in a reintervention, but in both patients it resulted in permanent discomfort. We then present a guideline that may prevent damage to these critical structures. (J Vasc Surg 2001;33:1108-10.
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