Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2015 ( 13 )

2014 ( 13 )

2013 ( 18 )

2012 ( 17 )

Custom range...

Search Results: 1 - 10 of 177 matches for " Stetson "
All listed articles are free for downloading (OA Articles)
Page 1 /177
Display every page Item
Hyla sanborni Schmidt, 1944 (Anura: Hylidae). Primera cita para las provincias de Chaco y Formosa, Argentina
Stetson, Roberto
Cuadernos de Herpetología , 1999,
Abstract: Argentina: Formosa, Parque Nacional Pilcomayo (Abadía Cué). 14 - 19 de marzo de 1993. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" — Buenos Aires — Argentina (MACN 34689). S. Haene Heinomen y Gil G. Chaco, Parque Nacional Chaco. Octubre de 1982. MACN 32380. M. Rumboll.
The Impact of Microcomputers on Methods for Holographic Displacement and Strain Analysis

Karl A Stetson,

实验力学 , 1988,
Abstract: The subject of this paper will be the role that microcomputers and image processors can play in the analysis of diplacement and strain in hologram interferom try. The first consideration will be data acquisition, i. e. the process of converting fringes to numerical data that can be used by a computer, Methods will be discussed that range from digitizing tablets to solid-state TV cameras. The next consideration will be proper identification of object points in the image field and the transformation between the image field and mesh points from a finite-element analysis of the object. After this, the problem will be considered of how to interpolate fringes. so as to compute strain or displacements at mesh point locations. Finally, the mathematics for converting holographic data into displacement or strain will be presented.
Accidentes con escorpiones en la ciudad de posadas, Provincia de Misiones, Argentina, durante el a?o 2002
Stetson, Roberto E.;
Biota Neotropica , 2005, DOI: 10.1590/S1676-06032005000200022
Abstract: studies were carried out to evaluate scorpion accidents in the city of posadas. studies comprised the analysis of doctor consulting forms belonging to the emergency rooms from two of the main hospitals in the city (ramón madariaga hospital and self -management pediatrics hospital), as well as files from accidents with poisonous non ophidian animals, all scorpions involved in the accidents were identified. results obtained in the year 2002 are shown discriminating between: number of cases, months of the year, scorpion species involved, type of accidents, most frequent symptoms, treatments used, relationship rate with other poisonous non ophidian animals, injured sexes and ages of treated children. also, we compared data of previous years from 1998. we found that during the year 2002, 97 accidents with scorpions were recorded. the accidents occurred in nearly all months of the year, increasing steadily when warm periods started, and having their highest peak during the months of december, january and february. from data available, we consider that most of them were produced by tityus trivittatus. no serious or lethal cases was officially reported. stings were painful and no antidotes were required. treatments included use of corticoids or antihistamines and sedatives. females were the most affected, and accidents involved children between ages of 6 and 13. when comparing the occurrence of previous years, results show that scorpion accidents are gradually increasing.
Distribución geográfica de Hyalinobatrachium uranoscopum (Ruiz Carranza & Lynch, 1993) (Anura: Centrolenidae)
Stetson, Roberto E.
Cuadernos de Herpetología , 2000,
Abstract: Argentina, Misiones, Departamento San Pedro, Colonia o Paraje Alegría (26o24' S / 53o 54' W).
On the Photometric Consequences of Charge-Transfer Inefficiency in WFPC2
Peter B. Stetson
Physics , 1998, DOI: 10.1086/316286
Abstract: Charge-transfer effects in photometry with Wide Field Planetary Camera 2 aboard the Hubble Space Telescope are investigated by a comparison of WFPC2 observations with groundbased photometry for the Galactic globular clusters omega Centauri and NGC 2419. Simple numerical formulae describing the fraction of lost signal as functions of position on the detector, stellar brightness, and the diffuse sky brightness recorded in an image are presented, and the resulting corrections are compared to those previously derived by Whitmore & Heyer (1997, Instrument Science Report WFPC2 97-08). Significant lost-charge effects are seen that are proportional to both the Y coordinate (i.e., the number of shifts along the parallel register during readout) and the X coordinate (number of shifts along the serial register). The percentage of charge lost decreases as the star brightness or the diffuse sky brightness increases. Charge losses during the brief period when WFPC2 was operated at a temperature of -76 degrees C were approximately 85% greater, but apart from that no significant change in the charge transfer losses with time during the first 3.5 years of WFPC2's mission is evident, except possibly a weak effect for the very faintest star images. These results are quite similar to those of Whitmore & Heyer, which were based on a much smaller data set, but there are some differences in detail. Even with the present set of corrections, additional sources of calibration uncertainty which I am unable identify or characterize with the available data probably limit the external accuracy of photometry from WFPC2 to of order 1-2%.
Homogeneous Photometry for Star Clusters and Resolved Galaxies. II. Photometric Standard Stars
Peter B. Stetson
Physics , 2000, DOI: 10.1086/316595
Abstract: Stars appearing in CCD images obtained over 224 nights during the course of 69 observing runs have been calibrated to the Johnson/Kron-Cousins BVRI photometric system defined by the equatorial standards of Landolt (1992, AJ, 104, 340). More than 15,000 stars suitable for use as photometric standards have been identified, where "suitable" means that the star has been observed five or more times during photometric conditions and has a standard error of the mean magnitude less than 0.02 mag in at least two of the four bandpasses, and shows no significant evidence of intrinsic variability. Many of these stars are in the same fields as Landolt's equatorial standards or Graham's (1982, PASP, 94, 244) southern E-region standards, but are considerably fainter. This enhances the value of those fields for the calibration of photometry obtained with large telescopes. Other standards have been defined in fields containing popular objects of astrophysical interest, such as star clusters and famous galaxies, extending Landolt-system calibrators to declinations far from the equator and to stars of sub-Solar chemical abundances. I intend to continue to improve and enlarge this set of photometric standard stars as more observing runs are reduced. The full current database of photometric indices is being made freely available via a site on the World-Wide Web, or by direct request to the author. Although the contents of the database will evolve in detail, at any given time it should represent the largest sample of precise BVRI broad-band photometric standards available anywhere.
Ampliación de la distribución geográfica de Hyla sanborni Schmidt, 1944 (Anura: Hylidae)
Stetson, Roberto,Benítez, P.,Pividori, N.
Cuadernos de Herpetología , 1996,
An HST study of OB associations and star clusters in M101
F. Bresolin,R. Kennicutt,P. Stetson
Physics , 1996, DOI: 10.1086/118073
Abstract: The massive stellar content, the OB associations and the star clusters in an HST field in M101 = NGC 5457 are investigated. A clustering algorithm yields 79 putative associations. Their size distribution is similar to that found in the Magellanic Clouds, M31 and M33, with an average size around 90 pc. The V luminosity function for the stars contained within the associations has a slope dlogN/dV = 0.60 +/- 0.05, while an average reddening E(B-V) = 0.21 mag is measured. The stellar content is further discussed by means of color-magnitude and color-color diagrams. Ages are estimated using theoretical isochrones, and range between 3 and 14 Myr (+\- 2 Myr). We find a suggestion that the upper mass limit of the IMF for stars in OB associations in M101 may be quite high, contrary to some theoretical expectations that the mass limit should be lower in a high metallicity environment. Forty-one star cluster candidates and two HII region core clusters are identified in the M101 field, and their integrated photometric properties are compared with the cluster system of the LMC and M33. Most of the M101 clusters probably belong to the class of young, populous star clusters such as are found in the LMC. Red clusters are rare in this field. In the Appendix the objective finding algorithm is applied to the brightest stars in the Large Magellanic Cloud.
Supernova 1991T and the Value of the Hubble Constant
Brad K. Gibson,Peter B. Stetson
Physics , 2000, DOI: 10.1086/318905
Abstract: Based upon multi-epoch Hubble Space Telescope observations, we present the discovery of sixteen high-quality Cepheid candidates in NGC 4527. Corrected for metallicity effects in the Cepheid period-luminosity relation, we derive a distance, including both random (r) and systematic (s) uncertainties, of 13.0+/-0.5(r)+/-1.2(s) Mpc. Our result is then used to provide a calibration of the peak B-, V-, and I-band luminosities of the peculiar Type Ia supernova SN 1991T, a resident of NGC 4527. Despite its documented spectroscopic peculiarities, after correction for the decline rate-luminosity correlation the corrected peak luminosity is indistinguishable from those of so-called ``normal'' Type Ia SNe. With now nine local calibrators at our disposal, we determine a robust value for the Hubble Constant of H_0=73+/-2(r)+/-7(s) km/s/Mpc.
The Distance to Supernova 1998aq in NGC3982
Peter B. Stetson,Brad K. Gibson
Physics , 2001, DOI: 10.1046/j.1365-8711.2001.05005.x
Abstract: The distance to NGC3982, host galaxy to the Type Ia supernova SN1998aq, is derived using 32 Cepheids discovered in archival multi-epoch Hubble Space Telescope observations. Employing recent Large Magellanic Cloud Cepheid period-luminosity relations and absolute zero point, we find a distance to NGC3982 of 20.5+/-0.8(r)+/-1.7(s) Mpc, including both random (r) and systematic (s) uncertainties, and ignoring any metallicity dependency in the Cepheid period-luminosity relation. Still unpublished light curve photometry promises to make SN1998aq one of the most important calibrators for the Type Ia supernova decline rate-peak luminosity relationship.
Page 1 /177
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.