2,858 research outputs found
Studying the Imaging Characteristics of Ultra Violet Imaging Telescope (UVIT) through Numerical Simulations
Ultra-Violet Imaging Telescope (UVIT) is one of the five payloads aboard the
Indian Space Research Organization (ISRO)'s ASTROSAT space mission. The science
objectives of UVIT are broad, extending from individual hot stars, star-forming
regions to active galactic nuclei. Imaging performance of UVIT would depend on
several factors in addition to the optics, e.g. resolution of the detectors,
Satellite Drift and Jitter, image frame acquisition rate, sky background,
source intensity etc. The use of intensified CMOS-imager based photon counting
detectors in UVIT put their own complexity over reconstruction of the images.
All these factors could lead to several systematic effects in the reconstructed
images. A study has been done through numerical simulations with artificial
point sources and archival image of a galaxy from GALEX data archive, to
explore the effects of all the above mentioned parameters on the reconstructed
images. In particular the issues of angular resolution, photometric accuracy
and photometric-nonlinearity associated with the intensified CMOS-imager based
photon counting detectors have been investigated. The photon events in image
frames are detected by three different centroid algorithms with some energy
thresholds. Our results show that in presence of bright sources, reconstructed
images from UVIT would suffer from photometric distortion in a complex way and
the presence of overlapping photon events could lead to complex patterns near
the bright sources. Further the angular resolution, photometric accuracy and
distortion would depend on the values of various thresholds chosen to detect
photon events.Comment: Submitted to PASP, 16 Pages, 9 figure
Binding of hypernuclei, and phtoproduction of -hypernuclei in the latest quark-meson coupling model
We study the binding of hypernuclei based on the latest version of
quark-meson coupling model, and estimate the phtoproduction cross sections for
the C()B reaction using the bound
spinors obtained in the model.Comment: 6 pages, 3 figures, Talk given at (Pre-symposium in) Sendai
International Symposium on Strangeness in Nuclear and Hadronic Systems
(SENDAI08), December (14)15-18, 2008, Tohoku Univ., Japa
Adoption of Variability Detection and Variable Rate Application Technologies by Cotton Farmers in Southern United States
A nested logit model was used to analyze the 2009 Southern Cotton Precision Farming Survey to study the impact of farmer and farm characteristics on the adoption of Variability Detection Technologies (VDT) and the adoption of Variability Rate application Technology (VRT) conditioned on the type of the VDT chosen. The results showed that the farm size and exposure to extension activities are important factors affecting the choice of VDTs. The farmers adopting both soil and plant based VDTs are more likely to adopt VRT. The probability of adoption of VRTs was lower for Texas cotton farmers irrespective of the type of VDT adopted. In general, younger, more educated farmers who use computers for farming operations are more likely to adopt VRT when they choose soil based or both soil and plant based VDT.Precision Agriculture, Technology Adoption, Cotton, Crop Production/Industries, Farm Management, Research and Development/Tech Change/Emerging Technologies, O33, Q16,
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