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1.
A project intended to examine the long-standing claims that extragalactic redshifts are periodic or quantized was initiated some years ago at the Royal Observatory, Edinburgh. The approach taken is outlined, and the main conclusions to date are summarized. The existence of a galactocentric redshift quantization is confirmed at a high confidence level. 相似文献
2.
B. N. G. Guthrie 《Astrophysics and Space Science》1982,85(1-2):315-324
Four spectra of the long-period Ap star HR 465 were taken in 1969–70 near its rare-earth minimum phase and analysed. Equivalent widths or upper limits were obtained for lines of 23 elements. Lines of Cr were very strong. The relative abundances of the iron-peak elements were derived by a differential curve-of-growth analysis using Gem as the comparison star. The Sc/Fe, Ti/Fe, V/Fe, and Ni/Fe abundance ratios were found to be abnormally low, while the Cr/Fe ratio was abnormally high (0.08). The equivalent widths in 1969–70 were compared with those measured by Aller on a spectrum taken in 1960 near the rare-earth maximum phase. Ionized lines of Sc, Ti, V, Te, Nb, Mo, and the rare-earths all vary out of phase with the Cri and Crii lines. Although Mo and Cr occupy corresponding positions in the periodic table, the Mo/Cr abundance ratio was apparently at least 180 times higher in 1960 than in 1969–70. 相似文献
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A hypothesis on the formation and seasonal evolution of Atlantic menhaden (Brevoortia tyrannus) juvenile nurseries in coastal estuaries is described. A series of cruises were undertaken to capture postmetamorphic juvenile menhaden and to characterize several biological and physical parameters along estuarine gradients. The two study systems, the Neuse and Pamlico rivers in North Carolina, contain important menhaden nursery grounds. Juvenile menhaden abundance was found to be associated with gradients of phytoplankton biomass as evidenced by chlorophylla levels in the upper water column. Fish abundances were only secondarily associated with salinity gradients as salinity was a factor that moderated primary production in the estuary. The persistence of spatial and temporal trends in the distribution of phytoplankton in the Neuse and Pamlico estuaries was reviewed. The review suggested that postmetamorphic juvenile menhaden modify their distribution patterns to match those created by phytoplankton biomass, which in turn makes them most abundant in the phytoplankton maxima of estuaries. Because the location of these maxima varies with the mixing and nutrient dynamics of different estuaries, so will the location of the nursery. 相似文献
5.
Bas van Geel R. Dale Guthrie Jens G. Altmann Peter Broekens Ian D. Bull Fiona L. Gill Boris Jansen Aline M. Nieman Barbara Gravendeel 《Quaternary Science Reviews》2011,30(17-18):2289-2303
Dung from a mammoth was preserved under frozen conditions in Alaska. The mammoth lived during the early part of the Late Glacial interstadial (ca 12,300 BP). Microfossils, macroremains and ancient DNA from the dung were studied and the chemical composition was determined to reconstruct both the paleoenvironment and paleobiology of this mammoth. Pollen spectra are dominated by Poaceae, Artemisia and other light-demanding taxa, indicating an open, treeless landscape (‘mammoth steppe’). Fruits and seeds support this conclusion. The dung consists mainly of cyperaceous stems and leaves, with a minor component of vegetative remains of Poaceae. Analyses of fragments of the plastid rbcL gene and trnL intron and nrITS1 region, amplified from DNA extracted from the dung, supplemented the microscopic identifications. Many fruit bodies with ascospores of the coprophilous fungus Podospora conica were found inside the dung ball, indicating that the mammoth had eaten dung. The absence of bile acids points to mammoth dung. This is the second time that evidence for coprophagy of mammoths has been derived from the presence of fruit bodies of coprophilous fungi in frozen dung. Coprophagy might well have been a common habit of mammoths. Therefore, we strongly recommend that particular attention should be given to fungal remains in future fossil dung studies. 相似文献
6.
B. N. G. Guthrie 《Astrophysics and Space Science》1974,27(2):489-496
analysis of new X-ray and optical data confirms that the X-ray luminosityL
x of a cluster of galaxies is strongly dependent on its richness. The radio powerP
1445 of clusters at 1445 MHz is independent of richness, but is greater on the average for clusters with dominant cD galaxies than for those withou. The radio emission depends on the activity of one of the brightest galaxies; dominant cD galaxies are often responsible for radio emission, especially if they have double or multiple nuclei. For a given richness, high values ofL
x andP
1445 sometimes occur together, but no strict correlation betweenL
x andP
1445 exists. Possible tests of thermal-bremsstrahlung and inverse-Compton theories for the X-ray emission are mentioned. 相似文献
7.
B. N. G. Guthrie 《Astrophysics and Space Science》1976,43(2):425-431
The sky distribution of deviations from the mean Hubble relation for the brightest galaxies in clusters is non-random for the velocity range 4000<V
r<25 000 km s–1. Deviations in visual magnitude are mainly positive in one large region of the sky and mainly negative in another region; the difference between the regions is 0.37±0.08
m
and is independent of colour. Various explanations are discussed briefly, and galactic or intergalactic absorption may be excluded. 相似文献
8.
George D. Guthrie Jr. David R. Veblen 《Contributions to Mineralogy and Petrology》1991,108(3):298-304
Partially turbid alkali feldspars from hydrothermally altered Tertiary granites on the Isle of Skye (the Red Hills granites)
were studied using light microscopy, scanning and transmission electron microscopies, and energy-dispersive X-ray spectroscopy.
Limpid cores and turbid rims of individual crystals were compared to determine the causes of the turbidity. The limpid cores
were cryptoperthitic, with lamellar widths of 0.1–0.3 μm. In contrast, the turbid rims contained K-rich and Narich areas coarsened
to >0.5 μm. Turbid regions contained abundant inclusions, whereas limpid regions did not. Two generations of turbidity were
recognized. Feldspars from the Beinn an Dubhaich granite, a granite with near-normal values for 18O/16O possessed limpid cores surrounded by turbid rims that cast a reddish-brown hue in transmitted light. When viewed in darkfield
light microscopy, the regions with the reddish-brown turbidity were blue. This is consistent with the hypothesis that the
cloudy appearance of these turbid regions arises from the scattering of light by micrometerto submicrometer-sized inhomogeneities
in refractive index caused by fluid-filled cavities. Feldspars from the Loch Ainort granite, a granite with low values for
18O/16O possessed limpid and reddish-brown-turbid cores surrounded by turbid rims that cast a blackish hue in transmitted light.
Ion thinning of the turbid areas produced an abundance of small holes (≤1–2 μm) apparently the remains of fluid inclusions.
Transmission electron microscopy revealed that some holes from regions of reddish-brown turbidity contained non-feldspar material,
including halite and metal-rich phases of various compositions. In contrast, blackish turbid regions contained cavities filled
with alteration products, such as kaolinite. Hence, the feldspars from granites on the Isle of Skye apparently record interactions
with at least two fluids: a saline fluid (possibly a late-stage magmatic fluid) and a meteoric fluid. 相似文献
9.
Analysis of landslide frequencies and characteristics in a natural system,coastal British Columbia 总被引：1，自引：0，他引：1
Two hundred and one debris slides and debris ?ows were analyzed in a 286 km2 study area on the west coast of Vancouver Island, British Columbia, Canada. The study area remains essentially untouched by humans and therefore affords a natural setting in which to examine slope processes. Landslides were identi?ed and characterized on aerial photographs from 1:15 000 to 1:31 680, and were then mapped and transferred to a GIS for analysis. Based on detailed landslide surveys, we propose a new method to accurately determine volume of landslides of this type by measured total area. Results indicate average denudation rates of 56 m3 y?1 km?2, and higher natural rates of failure than analogous regions in coastal British Columbia. In contrast, the landslide rates are substantially less than those from forested watersheds. Landslide distribution is spatially clustered in air photograph epochs, and we propose intense storm cells within regional events as the causal mechanism. Further, failures occurred preferentially over the West Coast Crystalline Complex (by 1·4 times), a metamorphic assemblage of gabbros, schists and amphibolites, but 1·5 times less often over the Island Plutonic Suite, a granitic intrusive formation. The former result represents a new ?nding, while the latter corroborates ?ndings of previous authors. We examined magnitude–frequency relationships of the data set and present for the ?rst time a strong argument that the rollover effect is not merely an artefact, but is instead a consequence of the physical characteristics of the landslides themselves. We subsequently analyzed magnitude–frequency relationships from two other complete data sets from coastal British Columbia and produced a family of curves corroborating this result. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.
Three hundred and sixty three landslides in three watersheds that totaled 382 km2 were identified from air photographs, beginning at a date that preceded logging to the present. The three watersheds all lie on Vancouver Island; however, they have different precipitation regimes, topography, and amounts logged. Landslide areas in the watersheds varied in size from 200 m2 to more than 1 ha. Nearly 80% of the landslides were debris slides; 15% were debris flows, and the remainder primarily rock falls. Following logging, the number of landslides increased substantially in all watersheds although the amount of increase was variable: approximately 11, 3, and 16 times in Macktush Creek, Artlish River, and Nahwitti River, respectively. Other analyses of changes in landslide density also produced highly variable results, with the number of landslides increasing between 2.4 and 24 times. Further, 2–12 times more landslides reached streams following logging activities. Densities for landslides impacting streams increased for the period of record from 1.5 to 10 times following logging activities. The densities were substantially greater where only landslides that reached streams since development began in a watershed were considered. Roads had the greatest spatial impact in the watersheds (compared to their total area), with frequencies determined to have increased by 27, 12, and 94 times for Macktush, Artlish, and Nahwitti, respectively. The results highlight the relative impact of roads and their role in slope stability. 相似文献