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581.
Pat D. 《Landscape and urban planning》2002,58(2-4)
Fragmentation is a research concept properly belonging to the biosciences and agriculture, yet it is one finding application in the planning and design fields. Cultural landscapes, on the other hand, is a concept uniquely rooted in landscape architecture and resource management. This paper links the two as a means of better grounding each in the decisions and processes affecting countryside planning and rural landuse, although both concepts have applications in urban settings, as well. However, in theory and in practice, both concepts are impacted by the man versus nature paradigm, in which planners and designers are challenged to consider whether human actions are “natural” actions, or whether they belong in a separate philosophical category. This position paper was developed as a keynote speech for the 2000 ISOMUL Conference at the Wageningen University and Research Center in The Netherlands. 相似文献
582.
Linear rolling guideways (LRGs) play an important role in precision engineering. In the pre-rolling region, the hysteretic friction force exerts great impacts on the positioning accuracy. Numerical and experimental studies of the hysteresis of friction force are presented in this paper. A model, which is based on the stripe theory and the simplified theory of rolling contact, is built to describe the transient hysteresis of the friction force. Then, the model is modified by taking the anelasticity effect into consideration. Experimentally, a linear motor direct-drive setup is utilized to measure the transient asymmetrical hysteresis of the friction force in the pre-rolling region of an LRG. The influences of the pre-rolling displacement and the dwelling time on the asymmetrical hysteresis of the friction force are studied. The numerical and experimental results are well correlated, which shows good accuracy of the model. The transient asymmetrical hysteresis of friction force in the pre-rolling region of LRGs can thus be determined using the model. 相似文献
583.
Jason Langley Daniel E. Huddleston Christine J. Liu Xiaoping Hu 《Magma (New York, N.Y.)》2017,30(2):121-125
Objectives
The purpose of this study was to assess the reproducibility of substantia nigra pars compacta (SNpc) and locus coeruleus (LC) delineation and measurement with neuromelanin-sensitive MRI.Materials and methods
Eleven subjects underwent two neuromelanin-sensitive MRI scans. SNpc and LC volumes were extracted for each scan. Reproducibility of volume and magnetization transfer contrast measurements in SNpc and LC was assessed using intraclass correlation coefficients (ICC) and dice similarity coefficients (DSC).Results
SNpc and LC volume measurements showed excellent reproducibility (SNpc-ICC: 0.94, p < 0.001; LC-ICC: 0.96, p < 0.001). SNpc and LC were accurately delineated between scans (SNpc-DSC: 0.80 ± 0.03; LC-DSC: 0.63 ± 0.07).Conclusion
Neuromelanin-sensitive MRI can consistently delineate SNpc and LC.584.
Polyphenolic components, such as anthraquinones and stilbenes, from species of the genus Rheum have been shown to have a range of bioactivities relevant to human health. This paper outlines the polyphenolic composition of edible petioles of garden rhubarb (Rheum rhapontigen) and describes the effects of common cooking methods on total polyphenolic content, anthocyanin content and total antioxidant capacity. 相似文献
585.
Identity and Function of Scent Marks Deposited by Foraging Bumblebees 总被引:12,自引:0,他引:12
Dave Goulson Jane C. Stout John Langley William O. H. Hughes 《Journal of chemical ecology》2000,26(12):2897-2911
Foraging bumblebees can detect scents left on flowers by previous bumblebee visitors and hence avoid flowers that have been depleted of nectar. Tarsal secretions are probably responsible for this repellent effect. The chemical components of the tarsal glands were analyzed by combined gas chromatography–mass spectrometry for three species of bumblebee, Bombus terrestris, B. lapidarius, and B. pascuorum. The hydrocarbons identified were similar for each species, although there were interspecific differences in the relative amounts of each compound present. The tarsal extracts of all three species comprised complex mixtures of long-chain alkanes and alkenes with between 21 and 29 carbon atoms. When B. terrestris tarsal extracts were applied to flowers and offered to foraging bumblebees of the three species, each exhibited a similar response; concentrated solutions produced a repellent effect, which decreased as the concentration declined. We bioassayed synthetic tricosane (one of the compounds found in the tarsal extracts) at a range of doses to determine whether it gave a similar response. Doses 10–12 ng/flower resulted in rejection by foraging B. lapidarius. Only when 10–14 ng was applied did the repellent effect fade. We bioassayed four other synthetic compounds found in tarsal extracts and a mixture of all five compounds to determine which were important in inducing a repellent effect in B. lapidarius workers. All induced repellency but the strength of the response varied; heneicosane was most repellent while tricosene was least repellent. These findings are discussed in relation to previous studies that found that tarsal scent marks were attractive rather than repellent. 相似文献
586.
Joel S. Freundlich Dr. Feng Wang Catherine Vilchèze Dr. Gulcin Gulten Robert Langley Guy A. Schiehser Dr. David P. Jacobus Dr. William R. Jacobs Jr. Prof. Dr. James C. Sacchettini Prof. Dr. 《ChemMedChem》2009,4(2):241-248
Overcoming resistance : Isoniazid (INH) is a frontline antitubercular drug that inhibits the enoyl acyl carrier protein reductase InhA. Novel inhibitors of InhA that are not cross‐resistant to INH represent a significant goal in antitubercular chemotherapy. The design, synthesis, and biological activity of a series of triclosan‐based inhibitors is reported, including their promising efficacy against INH‐resistant strains of M. tuberculosis.
587.
The chemistry of fluids circulated through an artificially-stimulated, hot dry rock (HDR) fractured geothermal reservoir system in granitic rock is described in terms of mixing phenomena, geothermometry, and approach to saturation with reservoir rock minerals. Based on the similar dynamic behavior of Na+, K+, Li+, CI−, and B species and other isotopic evidence, the presence of a concentrated in-situ pore fluid was identified. Mixing and displacement of this in-situ fluid with meteoric make-up water is responsible for the observed behavior of the major dissolved species in the circulated fluid of this HDR system. 相似文献
588.
T Langley 《Canadian Metallurgical Quarterly》1995,11(2):121-124
We report here the operative findings, the incidence of successful laparoscopic treatment, and the perioperative complications in patients with nonvisualized gallbladder on drip infusion cholangiography (DIC). Eighty-five patients with a nonvisualized gallbladder on DIC were entered into the study. None of the patients had a minimal adhesive gallbladder; 51 to 85 patients (60.0%) had moderate adhesive gallbladders, and 34 (40.0%) had severely adhesive ones. The rate of successful laparoscopic treatment, including laparoscopy-assisted abdominal surgery, was 97.6% (83 of 85 patients). Perioperative complications occurred in only three patients (3.5%), and there were no deaths related to the operation. Thus, when patients with a nonvisualized gallbladder on DIC undergo laparoscopic cholecystectomy, meticulous procedures must be carried out; however, as the rate of successful laparoscopic treatment is high, cholecystectomy under laparoscopy is feasible for experienced surgeons. 相似文献
589.
In 3 experiments, pigeons (Columba livia) searched a digitized image of a gravel patch on a computer monitor for cryptic grains. Experiment 1 demonstrated that the bird's ability to detect a type of grain improved over successive encounters, and detection of alternative targets was attenuated when a search image was active. Experiment 2 demonstrated search-image effects independently for the 2 grains. Perception was biased to detect wheat grains after wheat encounters and was biased to detect bean grains after bean encounters. Experiment 3 demonstrated that when a search image was activated, selective attention was heightened to the visual features of the grain used to discriminate it from the multicolor gravel background. These results provide strong support for the view that search images are selective attention to specific visual features of cryptic prey. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献