5,656 research outputs found
Progress in cartography, EROS program
During the past 7 years the Interior Department EROS (Earth Resources Observation Systems) program with NASA sponsorship has conducted cartographic research based on high altitude aerial and space photographs. The research has centered on the direct use of the image and its transformation into so-called photo or image maps. Today the cartographers of the Geological Survey have a real opportunity for making maps from data supplied by ERTS-1 which is dedicated to remote sensing of the earth
Cartographic evaluation of ERTS orbit and attitude data
There are no author-identified significant results in this report
Digital cartography of Io
A high resolution controlled mosaic of the hemisphere of Io centered on longitude 310 degrees is produced. Digital cartographic techniques were employed. Approximately 80 Voyager 1 clear and blue filter frames were utilized. This mosaic was merged with low-resolution color images. This dataset is compared to the geologic map of this region. Passage of the Voyager spacecraft through the Io plasma torus during acquisition of the highest resolution images exposed the vidicon detectors to ionized radiation, resulting in dark-current buildup on the vidicon. Because the vidicon is scanned from top to bottom, more charge accumulated toward the bottom of the frames, and the additive error increases from top to bottom as a ramp function. This ramp function was removed by using a model. Photometric normalizations were applied using the Minnaert function. An attempt to use Hapke's photometric function revealed that this function does not adequately describe Io's limb darkening at emission angles greater than 80 degrees. In contrast, the Minnaert function accurately describes the limb darkening up to emission angles of about 89 degrees. The improved set of discrete camera angles derived from this effort will be used in conjunction with the space telemetry pointing history file (the IPPS file), corrected on 4 or 12 second intervals to derive a revised time history for the pointing of the Infrared Interferometric Spectrometer (IRIS). For IRIS observations acquired between camera shutterings, the IPPS file can be corrected by linear interpolation, provided that the spacecraft motions were continuous. Image areas corresponding to the fields of view of IRIS spectra acquired between camera shutterings will be extracted from the mosaic to place the IRIS observations and hotspot models into geologic context
Quick-change absorption column
Column has end caps held in place by springs; prefilled packs of absorbent can be exchanged quickly. Both ends of metal or plastic body tube of size which can hold adequate amount of absorbent are machined to provide seat for perforated plate and groove for its spring retainer ring
Radio Galaxy Detection in the Visibility Domain
We explore a new Bayesian method of detecting galaxies from radio
interferometric data of the faint sky. Working in the Fourier domain, we fit a
single, parameterised galaxy model to simulated visibility data of star-forming
galaxies. The resulting multimodal posterior distribution is then sampled using
a multimodal nested sampling algorithm such as MultiNest. For each galaxy, we
construct parameter estimates for the position, flux, scale-length and
ellipticities from the posterior samples. We first test our approach on
simulated SKA1-MID visibility data of up to 100 galaxies in the field of view,
considering a typical weak lensing survey regime (SNR ) where 98% of
the input galaxies are detected with no spurious source detections. We then
explore the low SNR regime, finding our approach reliable in galaxy detection
and providing in particular high accuracy in positional estimates down to SNR
. The presented method does not require transformation of visibilities
to the image domain, and requires no prior knowledge of the number of galaxies
in the field of view, thus could become a useful tool for constructing accurate
radio galaxy catalogs in the future.Comment: 11 pages, 11 figures. Accepted for publication in MNRA
Acute reduction in secretory immunoglobulin A following smoking cessation
Smokers report an increase in upper respiratory infections in the early phase of stopping smoking. One possible cause is a depletion in secretory immunoglobulin A (S-IgA) which has been observed in one study. The present study sought to establish this finding in smokers using nicotine patches. Ninety-two smokers, trying to stop smoking, were assessed whilst smoking and for up to six weeks of abstinence. All smokers were prescribed 15 mg 16-h nicotine patches. Among abstinent smokers, changes in S-IgA and saliva volume were assessed. During the preliminary analyses, we observed that for the pre-smoking cessation measure a longer time since the last cigarette was significantly related to Lower S-IgA levels (P = 0.006). Consequently, the main analysis, of changes in S-IgA from pre-cessation to post-cessation, was confined to those who had smoked within 0.5-1.5 h of the pre-cessation measure (n = 51). There was a significant decline in S-IgA, relative to pre-smoking abstinence levels, following abstinence of one day (P = 0.027), but Levels returned to pre-abstinence values after one week. There was no evidence of any significant changes in saliva volume following smoking cessation, relative to pre-cessation levels. Users of 15 mg patches are likely to experience a decline in S-IgA levels on the first day of smoking cessation, independent of saliva volumes, and this decline in S-IgA is Likely to occur acutely, within the first few hours of smoking abstinence. This acute drop in S-IgA appears to stem from a factor other than depletion of nicotine from the body. The observed decrease in S-IgA may help to explain the increased susceptibility of smokers to upper respiratory tract infections in the immediate post-cessation period. (C) 2004 Elsevier Ltd. ALL rights reserved
Ultrasound Investigations of Orbital Quadrupolar Ordering in UPd_3
For a high-quality single crystal of UPd_3 we present the relevant elastic
constants and ultrasonic attenuation data. In addition to the magnetic phase
transition at T_2=4.4 +/- 0.1K and the quadrupolar transition at T_1~6.8K, we
find orbital ordering at T_0=7.6 +/- 0.1K concomitant with a symmetry change
from hexagonal to orthorhombic. A striking feature is the splitting of the
phase transition at T_1 into a second-order transition at T_{+1}=6.9 +/- 0.05K
and a first-order transition at T_{-1}=6.7 +/- 0.05K. For the four phase
transitions, the quadrupolar order parameters and the respective symmetry
changes are specified.Comment: 14 pages (RevTex), 3 eps-figures, accepted by PR
S2LET: A code to perform fast wavelet analysis on the sphere
We describe S2LET, a fast and robust implementation of the scale-discretised
wavelet transform on the sphere. Wavelets are constructed through a tiling of
the harmonic line and can be used to probe spatially localised, scale-depended
features of signals on the sphere. The scale-discretised wavelet transform was
developed previously and reduces to the needlet transform in the axisymmetric
case. The reconstruction of a signal from its wavelets coefficients is made
exact here through the use of a sampling theorem on the sphere. Moreover, a
multiresolution algorithm is presented to capture all information of each
wavelet scale in the minimal number of samples on the sphere. In addition S2LET
supports the HEALPix pixelisation scheme, in which case the transform is not
exact but nevertheless achieves good numerical accuracy. The core routines of
S2LET are written in C and have interfaces in Matlab, IDL and Java. Real
signals can be written to and read from FITS files and plotted as Mollweide
projections. The S2LET code is made publicly available, is extensively
documented, and ships with several examples in the four languages supported. At
present the code is restricted to axisymmetric wavelets but will be extended to
directional, steerable wavelets in a future release.Comment: 8 pages, 6 figures, version accepted for publication in A&A. Code is
publicly available from http://www.s2let.or
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