1,156 research outputs found
Armagh Observatory: Historic Building Information Modelling for Virtual Learning in Building Conservation
In this paper the recording and design for a Virtual Reality Immersive Model of Armagh Observatory is presented, which will replicate the historic buildings and landscape with distant meridian markers and position of its principal historic instruments within a model of the night sky showing the position of bright stars. The virtual reality model can be used for educational purposes allowing the instruments within the historic building model to be manipulated within 3D space to demonstrate how the position measurements of stars were made in the 18th century. A description is given of current student and researchers activities concerning on-site recording and surveying and the virtual modelling of the buildings and landscape. This is followed by a design for a Virtual Reality Immersive Model of Armagh Observatory use game engine and virtual learning platforms and concepts
High Resolution, Wide Field, Narrow Band, Snapshot Imaging
We investigate the imaging performance of an interferometric array in the case of wide field, high resolution, narrow band, snapshot imaging. We find that, when uv-cell sizes are sufficiently small (ie. image sizes are sufficiently large), each instantaneous visibility record is gridded into its own uv-cell. This holds even for dense arrays, like the core of the next generation VLA. In this particular, application, Uniform weighting of the gridded visibilities approaches Natural weighting, with its often deleterious consequences on the resulting synthesized beam. For a core-dominated array, we show that the resulting image noise is highly correlated on scales comparable to the spatial frequencies of the core baselines. In general, this study accentuates the fact that, for imaging applications that require high resolution (Plains array and greater), many of the core antennas can be employed as a separate subarray for low resolution science, without sacrificing the quality of the high resolution science
High Resolution, Wide Field, Narrow Band, Snapshot Imaging
We investigate the imaging performance of an interferometric array in the
case of wide field, high resolution, narrow band, snapshot imaging. We find
that, when uv-cell sizes are sufficiently small (ie. image sizes are
sufficiently large), each instantaneous visibility record is gridded into its
own uv-cell. This holds even for dense arrays, like the core of the next
generation VLA. In this particular, application, Uniform weighting of the
gridded visibilities approaches Natural weighting, with its often deleterious
consequences on the resulting synthesized beam. For a core-dominated array, we
show that the resulting image noise is highly correlated on scales comparable
to the spatial frequencies of the core baselines. In general, this study
accentuates the fact that, for imaging applications that require high
resolution (Plains array and greater), many of the core antennas can be
employed as a separate subarray for low resolution science, without sacrificing
the quality of the high resolution science.Comment: 18 pages; Next Generation VLA Memo No. 78;
https://ngvla.nrao.edu/page/memos#gen-mem
The Rachel Carson Letters and the Making of Silent Spring
Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
Social work and gender::An argument for practical accounts
This article contributes to the debate on gender and social work by examining dominant approaches within the field. Anti-discriminatory, woman-centered and intersectional accounts are critiqued for reliance upon both reification and isolation of gender. Via examination of poststructural, queer and trans theories within social work, the author then presents accounts based upon structural/materialist, ethnomethodological and discursive theories, in order to open up debates about conceptualization of gender. These are used to suggest that social work should adopt a focus on gender as a practical accomplishment that occurs within various settings or contexts
Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources
(abridged) Hard X-ray surveys performed by the INTEGRAL satellite have
discovered a conspicuous fraction (up to 30%) of unidentified objects among the
detected sources. Here we continue our identification program by selecting
probable optical candidates using positional cross-correlation with soft X-ray,
radio, and/or optical archives, and performing optical spectroscopy on them. As
a result, we identified or more accurately characterized 44 counterparts of
INTEGRAL sources: 32 active galactic nuclei, with redshift 0.019 < z < 0.6058,
6 cataclysmic variables (CVs), 5 high-mass X-ray binaries (2 of which in the
Small Magellanic Cloud), and 1 low-mass X-ray binary. This was achieved by
using 7 telescopes of various sizes and archival data from two online
spectroscopic surveys. The main physical parameters of these hard X-ray sources
were also determined using the available multiwavelength information. AGNs are
the most abundant population among hard X-ray objects, and our results confirm
this tendency when optical spectroscopy is used as an identification tool. The
deeper sensitivity of recent INTEGRAL surveys enables one to begin detecting
hard X-ray emission above 20 keV from sources such as LINER-type AGNs and
non-magnetic CVs.Comment: 22 pages, 14 figures, 6 tables, accepted for publication on A&A, main
journa
Search for bottom squarks in pbarp collisions at sqrt(s)=1.8 TeV
We report on a search for bottom squarks produced in pbarp collisions at
sqrt(s) = 1.8 TeV using the D0 detector at Fermilab. Bottom squarks are assumed
to be produced in pairs and to decay to the lightest supersymmetric particle
(LSP) and a b quark with branching fraction of 100%. The LSP is assumed to be
the lightest neutralino and stable. We set limits on the production cross
section as a function of bottom squark mass and LSP mass.Comment: 5 pages, Latex. submitted 3-12-1999 to PRD - Rapid Communicatio
Search for Squarks and Gluinos in Events Containing Jets and a Large Imbalance in Transverse Energy
Using data corresponding to an integrated luminosity of 79 pb-1, D0 has
searched for events containing multiple jets and large missing transverse
energy in pbar-p collisions at sqrt(s)=1.8 TeV at the Fermilab Tevatron
collider. Observing no significant excess beyond what is expected from the
standard model, we set limits on the masses of squarks and gluinos and on the
model parameters m_0 and m_1/2, in the framework of the minimal low-energy
supergravity models of supersymmetry. For tan(beta) = 2 and A_0 = 0, with mu <
0, we exclude all models with m_squark < 250 GeV/c^2. For models with equal
squark and gluino masses, we exclude m < 260 GeV/c^2.Comment: 10 pages, 3 figures, Submitted to PRL, Fixed typo on page bottom of
p. 6 (QCD multijet background is 35.4 events
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