Spatial variations of rainwash and runoff within apparently homogeneous areas     

Shiu-hung Luk  C. Morgan 《CATENA》1981,8(3-4)

The magnitude and causes of rainwash and runoff variability within small and supposedly “homogeneous” areas were investigated. Artificial rainfall (at 50 mm hr⁻¹ for 30 minutes) was applied to twenty identical 0.0929 m² (1 ft²) mini-plots arranged within a wetted annular 16.5 m² in area. Despite the uniformity of techniques used for data collection, there was considerable variability in the rainwash and runoff data (coefficient of variation= 21 to 35% and 20 to 75% respectively) at the three locations in southern Ontario. In comparison with laboratory data, field rainwash variability was similar but field runoff variability was substantially higher. Soil strength parameters, surface roughness and microtopography, as well as aggregation indices, are considered to be the potential causes of the observed variabilities. Operator variance was found to be extremely significant in our study. It is suggested, therefore, that comparison of erosion data collected by different researchers must be conducted with great caution.  相似文献   

Effect of non-linear adsorption on the transport behaviour of Brilliant Blue in a field soil   总被引：4，自引：1，他引：4  

R. Kasteel  H.-J. Vogel  & K. Roth 《European Journal of Soil Science》2002,53(2):231-240

The food dye Brilliant Blue FCF (Color Index 42090) is often used as dye tracer in field studies for visualizing the flow pathways of water in soils. Batch studies confirmed findings of other researchers that non‐linear sorption is important for Brilliant Blue, especially at small concentrations (< 10 g l^?1 for our soil), and that retardation increases with decreasing concentrations as well as with increasing ionic strength of solutions. Therefore, it is not obvious if it can be used as an indicator for water flow paths as is often done. In this study, we compared the mobility of Brilliant Blue in a field soil (gleyic Luvisol) with that of bromide. Brilliant Blue and potassium bromide were simultaneously applied as a 6‐mm pulse on a small plot in the field, and the tracers were displaced with 89 mm of tracer‐free water using a constant intensity of 3.9 ± 0.2 mm hour^?1. Both tracer concentrations were determined on 144 soil cores taken from a 1 m × 1 m vertical soil profile. The transport behaviour differed in both (i) mean displacement and (ii) spatial concentration pattern. We found the retardation of Brilliant Blue could not be neglected and, in contrast to the bromide pattern, a pulse splitting was observed at the plough pan. Numerical simulations with a particle tracking code revealed that the one‐dimensional concentration profile of bromide was represented fairly well by the model, but the prediction of the double peak in the Brilliant Blue concentration profile failed. With additional assumptions, there were indications that Brilliant Blue does not follow the same flow paths as bromide. However, the question of Brilliant Blue taking the same flow pathways as bromide cannot be adequately answered by comparing both concentration distributions, because we look at two different transport distances due to the retardation of Brilliant Blue. It became obvious, however, that Brilliant Blue is not a suitable compound for tracing the travel time of water itself.  相似文献   

Sexual dimorphism,survival and dispersal in red deer     

E.?A.?CatchpoleEmail author  Y.?Fan  B.?J.?T.?Morgan  T.?H.?Clutton-Brock  T.?Coulson 《Journal of Agricultural, Biological & Environmental Statistics》2004,9(1):1-26

A detailed and extensive mark-recapture-recovery study of red deer on the island of Rum forms the basis of the modeling of this article. We analyze male and female deer separately, and report results for both in this article, but use the female data to demonstrate our modeling approach. We provide a model-selection procedure that allows us to describe the survival by a combination of age-classes, with common survival within each class, and senility, which is modeled continuously as a parametric function of age. Dispersal out of the study area is modeled separately. Survival and dispersal probabilities are examined for the possible influence of both environmental and individual covariates, including a range of alternative measures of population density. The resulting model is succinct and biologically realistic. We compare and contrast survival rates of male and female deer of different ages and compare the factors that affect their survival. We demonstrate large differences in the rate of senescence between males and females even though their senescence begins at the same age. The differences between the sexes suggest that, in population modeling of sexually size-dimorphic species, it is important to identify sex-specific survival functions.  相似文献   

Enzyme-linked immunosorbent assay of ochratoxin A in barley   总被引：3，自引：0，他引：3  

M R Morgan  R McNerney  H W Chan 《Journal of the Association of Official Analytical Chemists》1983,66(6):1481-1484

A noncompetitive, double antibody enzyme-linked immunosorbent assay for ochratoxin A using microtitration plates has been developed and applied to samples of barley. The anti-ochratoxin A antiserum, which is used at high dilution, does not cross-react significantly with ochratoxin B or ochratoxin a. Assay sensitivity for determination of the toxin in barley samples is 60 ng/kg. Minimal sample preparation is required before assay.  相似文献   

A promoter that drives transgene expression in cerebellar Purkinje and retinal bipolar neurons   总被引：13，自引：0，他引：13  

J Oberdick  R J Smeyne  J R Mann  S Zackson  J I Morgan 《Science (New York, N.Y.)》1990,248(4952):223-226

A genomic clone encoding the Purkinje cell-specific L7 protein has been isolated and utilized to drive the expression of beta-galactosidase in mice. Three independent transgenic lines, germ line transformed with an L7-beta-galactosidase fusion gene, exhibit beta-galactosidase expression in both cerebellar Purkinje cells and retinal bipolar neurons. This distribution is the same as that previously determined for the L7 protein by immunohistochemistry. The transgenic murine lines can be used to obtain populations of marked Purkinje and bipolar neurons. Similar L7 promoter constructs can be used to express other foreign genes specifically in these two classes of neurons.  相似文献   

Glazed lunar rocks: origin by impact     

Morgan JW  Laul JC  Ganapathy R  Anders E 《Science (New York, N.Y.)》1971,172(3983):556-558

The glassy coating of lunar rock 12017 is enriched in 15 trace elements relative to the crystalline interior. It apparently consists chiefly of shock-melted rock, somewhat richer in rare earth elements and alkali metals than rock 12017 itself. The glass has been contaminated by about 0.5 percent carbonaceous-chondrite-like material or, alternatively, by a mixture of 0.06 to 0.3 percent fractionated meteoritic material and approximately 10 to 15 percent local soil. The glazing seems to represent molten material splashed from a nearby meteorite impact and not in situ melting by a sudden increase in solar luminosity.  相似文献   

THE RISE OF GENETICS     

Morgan TH 《Science (New York, N.Y.)》1932,76(1969):261-267

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A SIMPLE SPOT-PLATE TEST FOR NITRATE NITROGEN IN SOIL AND OTHER EXTRACTS     

Morgan MF 《Science (New York, N.Y.)》1930,71(1839):343-344

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IONIZED ARGON IN THE SPECTRUM OF UPSILON SAGITTARII     

Morgan WW 《Science (New York, N.Y.)》1934,79(2055):454-455

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Ras p21 as a potential mediator of insulin action in Xenopus oocytes   总被引：36，自引：0，他引：36  

L J Korn  C W Siebel  F McCormick  R A Roth 《Science (New York, N.Y.)》1987,236(4803):840-843

The oncogene protein product (p21) of the ras gene has been implicated in mediating the effects of a variety of growth factors and hormones. Microinjection of monoclonal antibody 6B7, which is directed against a synthetic peptide corresponding to a highly conserved region of p21 (amino acids 29 to 44) required for p21 function, specifically inhibited Xenopus oocyte maturation induced by incubation with insulin. The inhibition was dose-dependent and specific since (i) the same antibody had no effect on progesterone-induced maturation, (ii) immunoprecipitation and Western blotting indicated that the antibody recognized a single protein of molecular weight 21,000 in oocyte extracts, and (iii) inhibition was not observed with identical concentrations of normal immunoglobulin. Thus, p21 appears to be involved in mediating insulin-induced maturation of Xenopus oocytes. Furthermore, the mechanism may involve phosphorylation of p21, as p21 was found to be a substrate of the insulin receptor kinase.  相似文献