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101.
Alan W. Owen 《Geological Journal》1984,19(3):304-305
102.
103.
Using the recently completed Giant Meterwave Radio Telescope, we have detected the HI 21 cm-line absorption from the peculiar
galaxy C153 in the galaxy cluster Abell 2125. The HI absorption is at a redshift of 0.2533, with a peak optical depth of 0.36.
The full width at half minimum of the absorption line is 100 km s−1. The estimated column density of atomic Hydrogen is 0.7×1022(T
s
/100) cm−2. The HI absorption is redshifted by ∼400km s−1 compared to the [OIII] emission line from this system. We attribute this to an infalling cold gas or to an out-flowing ionised
gas, or to a combination of both as a consequence of tidal interactions of C153 with either a cluster galaxy or the cluster
potential. 相似文献
104.
Bioerosion by Cliona delitrix and Cliona lampa was assessed at 43 sites along the Florida Reef Tract, USA, in the summer of 2001. Sponge abundances were estimated using rapid visual assessment. Tissue samples of sponges were taken for analysis of delta15N. Comparison samples were taken from Belize. Annual trends in sponge abundance were estimated from archived videos covering the period from 1996 to 2001. Sites with the greatest boring sponge size and cover were in the Backcountry and Lower Keys, where total nitrogen, ammonium, and delta15N levels were highest. The sites with the largest relative increase of C. delitrix and C. lampa over the 5 year period were in the Upper Keys, where the greatest relative decline in stony coral cover has occurred. Florida sponge delta15N values were 5.2(+/-0.1)%, suggesting the influence of human waste; in comparison, offshore Belize samples were 2.1(+/-0.1)%. These results suggest sewage contamination of the Florida Reef Tract, shifting the carbonate balance from construction to destruction. 相似文献
105.
106.
107.
Late Holocene radiocarbon and aspartic acid racemization dating of deep-sea octocorals 总被引:1,自引:0,他引:1
Primnoa resedaeformis is a deep-sea gorgonian coral with a two-part skeleton of calcite and gorgonin (a fibrillar protein), potentially containing long-term records of valuable paleo-environmental information. For various reasons, both radiocarbon and U/Th dating of these corals is problematic over the last few centuries. This paper explores aspartic acid racemization dating of the gorgonin fraction in modern and fossil specimens collected from the NW Atlantic Ocean. Radiocarbon dating of the fossil specimen indicates a lifespan of 700 ± 100 years, the longest yet documented for any octocoral. Gorgonin amino acid compositions were identical in the fossil and modern specimens, indicating resistance to organic diagenesis. Similar to bone collagen, the fibrillar protein of gorgonin may impose conformational constraints on the racemization of Asp at low temperatures. The rate of racemization of aspartic acid (d/l-Asp) was similar to previously published results from an 1800 year old anemone (Gerardia). The age equation was: age (years BP 2000 AD) = [(d/l − 0.020 (±.002))/.0011 (±.0001)]2 (r2 = 0.97, p < .001). The error in an age estimate calculated by d/l-Asp was marginally better than that for 14C dating over the most recent 50-200 years, although the dating error may be improved by inclusion of more samples over a broader time range. These results suggest that d/l-Asp dating may be useful in augmenting 14C dating in cases where 14C calibrations yield two or more intercept ages, or in screening samples for further 14C or U/Th dating. 相似文献
108.
Tobias Owen 《Icarus》1976,29(1):159-163
A brief review of the history of Jovian satellite nomenclature is given to indicate the background for the names proposed for the numbered satellites. The new names are consistent with established tradition and should cause minimal confusion with other named objects in the solar system. 相似文献
109.
James M. Bauer Ted L. RoushThomas R. Geballe Karen J. MeechTobias C. Owen William D. Vacca John T. Rayner Kevin T.C. Jim 《Icarus》2002,158(1):178-190
A spectrum from 1.2 to 2.5 μm of Uranus' small satellite Miranda obtained in June 1999 reveals strong water-ice signatures. It confirms the existence of a 2.0-μm water feature previously detected on Miranda and shows a strong second broad 1.5-μm water-ice absorption feature. The spectra also reveal a weak absorption band at 1.65 μm that is indicative of crystalline water ice. Reflectance models which combine the new spectra with new photometry indicate that the spectra are characteristic of a mostly water-ice surface, with a large fraction of carbonaceous or silicate contaminates, and the possible presence of ammonia hydrate, as implied by an apparent weak feature near 2.2 μm. The possible presence of other volatiles is also investigated. 相似文献
110.
Interactive analysis of the spatial distribution of disease using a geographic information systems 总被引:1,自引:0,他引:1
Geographic information systems (GIS) provide a variety of tools for the manipulation and display of public health data. Few,
however, enable users to interactively evaluate hypotheses on spatial trends in disease risk that may be suggested by maps
of measures of disease impact. We addressed this limitation by developing a seamless interface between a commercial GIS and
a suite of spatial analysis algorithms. Users of the system can utilize the GIS's capability to interactively select and manipulate
geographically referenced data and, through a series of pull-down menus, apply a variety of exploratory analysis methods to
this information. In the presented application, we illustrate this capability by including algorithms for the reduction of
random noise in observed incidence rates, for the detection of unusual aggregations of disease events, and for the statistical
evaluation of inferences drawn from spatial trends. We demonstrate this application by examining lung cancer mortality in
the state of Ohio.
Received: 22 September 1999 / Accepted: 8 March 2000 相似文献