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Quantitative Knowledge (quantitative + knowledge)
Selected AbstractsMODERN CONFUCIAN SYNTHESIS OF QUALITATIVE AND QUANTITATIVE KNOWLEDGE: XIONG SHILI ???JOURNAL OF CHINESE PHILOSOPHY, Issue 3 2009JANA S. RO First page of article [source] Behavior of moment-resisting frame structures subjected to near-fault ground motionsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2004Babak Alavi Abstract Near-fault ground motions impose large demands on structures compared to ,ordinary' ground motions. Recordings suggest that near-fault ground motions with ,forward' directivity are characterized by a large pulse, which is mostly orientated perpendicular to the fault. This study is intended to provide quantitative knowledge on important response characteristics of elastic and inelastic frame structures subjected to near-fault ground motions. Generic frame models are used to represent MDOF structures. Near-fault ground motions are represented by equivalent pulses, which have a comparable effect on structural response, but whose characteristics are defined by a small number of parameters. The results demonstrate that structures with a period longer than the pulse period respond very differently from structures with a shorter period. For the former, early yielding occurs in higher stories but the high ductility demands migrate to the bottom stories as the ground motion becomes more severe. For the latter, the maximum demand always occurs in the bottom stories. Preliminary regression equations are proposed that relate the parameters of the equivalent pulse to magnitude and distance. The equivalent pulse concept is used to estimate the base shear strength required to limit story ductility demands to specific target values. Copyright © 2004 John Wiley & Sons, Ltd. [source] Prediction of uptake dynamics of persistent organic pollutants by bacteria and phytoplanktonENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2002Sabino Del Vento Abstract Phytoplankton and bacteria play an important role on the biogeochemical cycles of persistent organic pollutants (POPs). However, experimental data and quantitative knowledge of the kinetics of uptake and depuration of most POPs by bacteria and phytoplankton are scarce. In the present paper, a procedure to predict the sorption kinetics to bacteria and phytoplankton is developed. The prediction method is the combination of a mechanistic model for sorption and quantitative structure,activity relationships relating bioconcentration factors and membrane permeability to the chemical physical-chemical properties. The model consists of two compartments where the first compartment is the cellular surface and the second compartment is the cell biomass or matrix. Equations for estimating uptake and depuration rate constants into the matrix and adsorption and desorption rate constants onto the surface are obtained. These expressions depend on the physical-chemical properties of the chemical, the environmental temperature, the microorganism size, and species-specific quality of organic matter. While microorganism shape has a secondary influence on uptake dynamics, microorganism size and chemical hydrophobicity arise as the key factors controlling the kinetics of POP incorporation into bacteria and plankton. Uptake, depuration, adsorption, and desorption rate constants are reported for POPs such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dioxins and furans (PCDD/Fs), and POPs of emerging concern, such as polybrominated diphenyl ethers (PBDEs). Finally, implications of uptake and depuration dynamics on the biogeochemical cycling of POPs are discussed. [source] Impact of land use and land cover change on groundwater recharge and quality in the southwestern USGLOBAL CHANGE BIOLOGY, Issue 10 2005Bridget R. Scanlon Abstract Humans have exerted large-scale changes on the terrestrial biosphere, primarily through agriculture; however, the impacts of such changes on the hydrologic cycle are poorly understood. The purpose of this study was to test the hypothesis that the conversion of natural rangeland ecosystems to agricultural ecosystems impacts the subsurface portion of the hydrologic cycle by changing groundwater recharge and flushing salts to underlying aquifers. The hypothesis was examined through point and areal studies investigating the effects of land use/land cover (LU/LC) changes on groundwater recharge and solute transport in the Amargosa Desert (AD) in Nevada and in the High Plains (HP) in Texas, US. Studies use the fact that matric (pore-water-pressure) potential and environmental-tracer profiles in thick unsaturated zones archive past changes in recharging fluxes. Results show that recharge is related to LU/LC as follows: discharge through evapotranspiration (i.e., no recharge; upward fluxes <0.1 mm yr,1) in natural rangeland ecosystems (low matric potentials; high chloride and nitrate concentrations); moderate-to-high recharge in irrigated agricultural ecosystems (high matric potentials; low-to-moderate chloride and nitrate concentrations) (AD recharge: ,130,640 mm yr,1); and moderate recharge in nonirrigated (dryland) agricultural ecosystems (high matric potentials; low chloride and nitrate concentrations, and increasing groundwater levels) (HP recharge: ,9,32 mm yr,1). Replacement of rangeland with agriculture changed flow directions from upward (discharge) to downward (recharge). Recent replacement of rangeland with irrigated ecosystems was documented through downward displacement of chloride and nitrate fronts. Thick unsaturated zones contain a reservoir of salts that are readily mobilized under increased recharge related to LU/LC changes, potentially degrading groundwater quality. Sustainable land use requires quantitative knowledge of the linkages between ecosystem change, recharge, and groundwater quality. [source] Influence of aldehyde fixation on the morphology of endosomes and lysosomes: quantitative analysis and electron tomographyJOURNAL OF MICROSCOPY, Issue 1 2003J. L. A. N. Murk Summary Cryoimmobilization is regarded as the most reliable method to preserve cellular ultrastructure for electron microscopic analysis, because it is both fast (milliseconds) and avoids the use of harmful chemicals on living cells. For immunolabelling studies samples have to be dehydrated by freeze-substitution and embedded in a resin. Strangely, although most of the lipids are maintained, intracellular membranes such as endoplasmic reticulum, Golgi and mitochondrial membranes are often poorly contrasted and hardly visible. By contrast, Tokuyasu cryosectioning, based on chemical fixation with aldehydes is the best established and generally most efficient method for localization of proteins by immunogold labelling. Despite the invasive character of the aldehyde fixation, the Tokuyasu method yields a reasonably good ultrastructural preservation in combination with excellent membrane contrast. In some cases, however, dramatic differences in cellular ultrastructure, especially of membranous structures, could be revealed by comparison of the chemical with the cryofixation method. To make use of the advantages of the two different approaches a more general and quantitative knowledge of the influence of aldehyde fixation on ultrastructure is needed. Therefore, we have measured the size and shape of endosomes and lysosomes in high-pressure frozen and aldehyde-fixed cells and found that aldehyde fixation causes a significant deformation and reduction of endosomal volume without affecting the membrane length. There was no considerable influence on the lysosomes. Ultrastructural changes caused by aldehyde fixation are most dramatic for endosomes with tubular extensions, as could be visualized with electron tomography. The implications for the interpretation of immunogold localization studies on chemically fixed cells are discussed. [source] Raman tensor analysis of baddeleyite single-crystal and its application to define crystallographic domains in polycrystalline zirconiaPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2010Kyoju Fukatsu Abstract The angular dependence of polarized Raman intensity for the Ag and Bg modes was investigated and the full set of Raman tensor elements defined for a baddeleyite single-crystal, namely the monoclinic polymorph of zirconia (ZrO2). Based on the quantitative knowledge of the tensor elements, a method has been proposed for the determination of unknown crystallographic textures in monoclinic zirconia. An application of this method is also shown, which consists of a Raman analysis of crystal orientation on the microscopic scale in polycrystalline ZrO2 after its tetragonal-to-monoclinic (t,m) polymorphic transformation (i.e., occurred under an externally applied stress field). This working example not only confirms the well-known phenomenon of stress-induced phase transformation in polycrystalline zirconia, but also proves the existence of textured domain patterns in the monoclinic phase on a scale larger than that of individual grains. This finding might suggest that the structural and functional properties of polycrystalline zirconia after partial phase transformation should be reinterpreted with taking into account a crystallographic reorientation effect. [source] | ||||||||||