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41.
Changes over the past twenty-five years in information and communication technology (ICT) are beginning to provide us with a clearer picture of the technical platform that will influence the shape of urban and industrial development into the 21st century. During this period we have experienced a number of key paradigm shifts in computing: from 1960s batch systems to 1970s time sharing systems to 1980s desktop systems (Newton et al. 1988). At the same time, but somewhat independently, communications were evolving from the slow speed analogue public switched telephone network which provided a measure of computer-to-computer interaction (via modems) to the newly emerging high speed broadband digital networks, networks which will provide a truly vast array of value added products and services (discussed more fully in Cavill and Fidler' paper). The dramatic price-performance improvements in these technologies and the synergy which now exists between computers and communications provides us in the 1990s with the core information infrastructure of the future: computers and the networks that interconnect them (Newton etal. 1991).  相似文献   
42.
The precise orientation of the collagen fibrils in human cornea and sclera and the method by which these two areas fuse together at the limbus have never been determined, despite the importance of this information. From a consideration of the mechanics of the system, fibril orientation in the tissue has the potential to affect the curvature of the cornea so, by inference, refractive problems such as astigmatism involving an incorrect curvature of the cornea may be related to fibril orientation. The high intensity and small beam size of a synchrotron x-ray source has enabled us to study fibril orientation in post-mortem human cornea and sclera. Previously we have revealed two preferred directions of orientation in the cornea (Meek, K. M., T. Blamires, G. F. Elliot, T. Y. Gyi, and C. J. Nave. 1987. Curr. Eye Res. 6:841-846) and a circumcorneal annulus in the limbus (Newton, R. H., and K. M. Meek. 1998. Invest. Ophthalmol. & Visual Sci. 39: 1125-1134). Here we present the results of our investigation into the relationship between these two features. Our measurements indicate that the corneal fibrils oriented in the two preferred directions bend at the limbus to run circumferentially. On the basis of these results we propose a model as to how the human cornea and sclera fuse together.  相似文献   
43.
Ecological and physiological effects of the sulphate-reducing bacterium (SRB) Desulfovibrio desulfuricans on other intestinal organisms were investigated in anaerobic chemostats (dilution rate approximately 0.2 h-1). Reproducible defined bacterial communities were used in these experiments, comprising 14 different saccharolytic and amino acid fermenting species: Bifidobacterium longum, Bif. adolescentis, Bif. pseudolongum, Bif. infantis, Bacteroides thetaiotaomicron, Bact. vulgatus, Lactobacillus acidophilus, Enterococcus faecalis, Ent. faecium, Escherichia coli, Clostridium perfringens, Cl. butyricum, Cl. innocuum, Cl. bifermentans. Lactobacillus and Cl. bifermentans populations never rose above minimum detection limits (log10 2.0 and 4.0, respectively) under the experimental conditions employed in these studies. Inclusion of Des. desulfuricans in bacterial cultures (c. log10 8.4 viable cells ml-1) resulted in marked reductions (i.e. greater than 1 log) in planktonic cell population densities of several species, particularly Bif. longum, Cl. perfringens and Bif. pseudolongum. The two bacteroides species were unaffected by Des. desulfuricans, while numbers of Cl. butyricum increased. Extensive wall growth developed in the SRB culture, consisting mainly of Des. desulfuricans (log10 9.2 viable cells ml-1), Bact. thetaiotaomicron and Bact. vulgatus, with lesser numbers of facultative anaerobes, Cl. perfringens and Bif. longum. Wall growth was associated with a reduction in planktonic cell mass and increased acid production by the cultures. Chemotaxonomic study of chemostat microbiotas, on the basis of cellular fatty acid methyl ester (FAME) analyses, showed the existence of characteristic bacteroides (C15) and bifidobacterial (C18) markers, but desulfovibrio markers (i-C15:0, C16:0, i-C17:1) could be identified. The metabolic activities of saccharolytic organisms were altered in the SRB chemostat, including synthesis of a number of hydrolytic enzymes involved in carbohydrate breakdown, such as alpha-galactosidase, alpha-glucosidase and beta-galactosidase, together with several mucinolytic enzymes. High concentrations of sulphide (8.2 mmol 1-1) were detected in the SRB chemostat, suggesting that this metabolite may have been inhibitory to some species. Saccharolytic organisms growing in the SRB fermenter utilized more starch, but less galactose-containing polymers, which correlated with the observed glycosidase activities. Profound differences were also recorded with respect to fermentation product formation in the chemostats, where a major switch to acetate production occurred in the SRB culture, with concomitant reductions in propionate, butyrate and lactate, which is an important electron donor for desulfovibrios.  相似文献   
44.
The tilled row structure is known to be one of the important factors affecting the observations of the microwave emission from a natural surface. Measurements of this effect were carried out with both L-and X-band radiometers mounted on a mobile truck on a bare 40 m × 45 m row tilled field. The soil moisture content during the measurements ranged from ~10 to ~30 percent by dry weight. The results of these measurements showed that the variations of the antenna temperatures with incident angle ? changed with the azimuthal angle ? measured from the row direction. In particular, at ? = 0° and ? ? 45°, the observed horizontally and vertically polarized antenna temperatures, TBH(?, ?) and TBV(?, ?), were not equal. In general, TBH(?°, ?) > TBV(?°, ?) when 0° ? ? < 45° and TBH(?°, ?) < TBV(0°, ?) when 45° < ? ? 90°. The difference between TBH(0°, ?) and TBV(0°, ?) was observed to decrease with ? approaching 45° and/or with soil moisture content. A numerical calculation based on a composite surface roughness-a small-scale RMS height variations superimposed on a large periodic row structure-was made and found to predict the observed features within the model's limit of accuracy. It was concluded that the difference between TBV(0°, ?) and TBH(0°, ?) was due to the change in the local angle of field emission within the antenna field of view caused by the large-scale row structure.  相似文献   
45.
Examined the feasibility of applying the static strength and endurance relationships suggested in 1960 by W. Rohmert to a simple manual task. Results indicate that there was a relationship between grip strength expenditure and impairments in task performance similar in respect to the static strength and endurance relationships suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
46.
47.
The main activity of the RBDATA-EULEP project is the development of an electronic database of information on the biokinetics of radionuclides after intake by inhalation, ingestion or injection. It consists of linked tables of publications and experiments, with details and comments on the materials, procedures and results. By March 2004 it contained information on more than 1600 experiments from 600 publications. It will be extended and Internet access will also be provided.  相似文献   
48.
Data are presented on the whole-body retention of 133Ba (half-life 10.74 y), over periods of up to 13 y after injection into six healthy male volunteers aged 25-81, and on their levels of biochemical markers for bone turnover. The results are relevant to propositions underlying the ICRP's current (Publication 67) and former (Publication 20) models of alkaline earth metabolism. The tracer was predominantly skeletal within weeks of the injection, as predicted in the current model. The mean retention accorded satisfactorily throughout with predictions based on the current model, but this accord does not necessarily validate the model, for two reasons. First, parameter values attributed to barium were influenced by data emerging during the early years of this study. Second, bone resorption rates in these subjects, as indicated by urinary markers, appear insufficient to explain the long-term reductions in skeletal retention which, in the present model, arise exclusively through this mechanism.  相似文献   
49.
The C-3 substituted phenylazo derivatives of lawsone (2-hydroxy-l,4 p-naphthoquinone, III) were synthesized and characterized. The X-ray crystal structure was determined for the ligand 3-(3'-methyl phenylazo) lawsone. The copper complexes of these derivatives were found to possess 1:2 metal stoichiometry and square planar geometries with intermolecular stackings, resulting in antiferromagnetic exchange interactions. The in vitro activity of all the synthesized compounds was examined against human breast cancer cell-line, MCF-7, which revealed enhanced activities for the metal complexes, the highest activity being observed for the copper compound of 3-(3'-methyl phenylazo) lawsone.  相似文献   
50.
Water-leaving reflectance (ρw) data from the European Space Agency ocean colour sensor Medium Resolution Imaging Spectrometer (MERIS) was validated with in situ ρw between October 2008 and November 2011, off Sagres on the southwest coast of the Iberian Peninsula. The study area is exceptional, since Stations A, B, and C at 2, 10, and 18 km offshore are in optically deep waters at approximately 40, 100, and 160 m, respectively. These stations showed consistently similar bio-optical properties, characteristic of Case 1 waters, enabling the evaluation of adjacency effects independent of the usual co-varying inputs of coastal waters. Using the third reprocessing of MERIS with the standard MEGS 8.1 processor, four different combinations of procedures were tested to improve the calibration between MERIS products and in situ data. These combinations included no vicarious adjustment (NoVIC), vicarious adjustment (VIC), and, for mitigating the effects of land adjacency on MERIS ρw, the improved contrast between ocean and land (ICOL) processor (version 2.7.4) and VIC + ICOL. Out of approximately 130 potential matchups for each station, 38–77%, 74–86%, and 88–90% were achieved at Stations A, B, and C, respectively, depending on which of the four combinations were used. Analyses of ρw comparing these various procedures, including statistics, scatter plots, histograms, and MERIS full-resolution images, showed that the VIC procedure compared with NoVIC produced minimal changes to the calibration. For example, at the oceanic Station C, the regression slope was closer to unity at all wavelengths with NoVIC compared to VIC, whereas, with the exception of wavelengths 412 and 443 nm, the intercept, mean ratio (MR), absolute percentage difference (APD), and relative percentage difference (RPD) were better with NoVIC. The differences for MR and APD indicate that there was marginal improvement for these two bands with VIC, and an over-adjustment with RPD. ICOL also showed inconsistent results for improving the retrieval of the near-shore conditions, but under some conditions, such as ρw at wavelength 560 nm, the improvement was striking. VIC + ICOL showed results intermediate between those of VIC and ICOL implemented separately. In relation to other validation sites, the offshore Station C at Sagres had much in common with the Mediterranean deep water, BOUSSOLE buoy, although the matchup statistics between MERIS ρw and in situ ρw were much better for Sagres than for BOUSSOLE. Strikingly, the matchup statistics for ρw at Sagres were very similar to those for the Acqua Alta Oceanographic Tower (AAOT), where the AAOT showed more scatter at 412 nm, probably because of the atmospheric correction where the aerosol optical thickness is higher at the AAOT. Conversely, Sagres showed much greater scatter at 665 nm in the red as the values were generally close to the limits of detection owing to the clearer waters at Sagres compared to the more turbid waters at the AAOT.  相似文献   
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