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Generation Mechanism (generation + mechanism)
Selected AbstractsGeneration Mechanism and in situ Growth Behavior of ,-Iron Nanocrystals by Electron Beam Induced Deposition,ADVANCED ENGINEERING MATERIALS, Issue 8 2006W. Zhang Amorphous iron-containing deposits were formed on carbon films by electron beam induced deposition with a precursor of iron pentacarbonyl and alpha-Fe nanocrystals were grown around the target tip deposits when the electron beam irradiation time was longer than 1000,s. [source] Changes of Headspace Volatiles in Milk with Riboflavin PhotosensitizationJOURNAL OF FOOD SCIENCE, Issue 7 2009J.H. Lee ABSTRACT:, Effects of fluorescent light, riboflavin, ascorbic acid, sodium azide, and butylated hydroxyanisole (BHA) on the volatiles in milk at 4 °C were determined using a combination of headspace-solid phase microextraction (HS-SPME), gas chromatography (GC), and mass spectrometry (MS). Pentanal, hexanal, heptanal, and dimethyl disulfide were formed only in the milk stored under light and increased significantly as the duration of light exposure increased from 0 to 8 h and the concentration of added riboflavin increased from 5 to 50 ppm (P,< 0.05). As fat content in milk increased, peak areas of pentanal, hexanal, and heptanal increased significantly (P,< 0.05) while those of dimethyl disulfide did not change significantly (P,> 0.05). Sodium azide prevented the formation of dimethyl disulfide in milk, implying that dimethyl disulfide can be formed through singlet oxygen oxidation (type II pathway). Addition of ascorbic acid and BHA reduced the formation of hexanal, heptanal, and dimethyl disulfide significantly (P,< 0.05). Generation mechanisms of pentanal seem to be different from those of hexanal and heptanal in milk. Both singlet oxygen oxidation (type II pathway) and free radicals (type I pathway) play important roles in the formation of light-induced volatiles in milk. [source] Disparate Scale Nonlinear Interactions in Edge TurbulenceCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2008M. Yagi Abstract In this topical review, we explain the recent achievement in the study of nonlinear interactions, putting an emphasis on the relevance to edge turbulence. First, we start from the survey of the essence in the nonlinear theory of drift wave -zonal flows systems, and visit the experimental observations of the nonlinear interactions of tokamak edge turbulence. Secondly, the universality of intermittent convective transport in the SOL of different magnetic devices are shown. Then, we discuss evolution of collisional drift wave instability in the linear plasma configuration, which is bounded by end plates having analogy to SOL plasmas. By introducing the Numerical Linear Device, the intermittent evolution of large-amplitude instabilities, generation mechanism of the poloidal flow and other nonlinear process are examined. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Visualization of stochastic Ca2+ signals in the formed somites during the early segmentation period in intact, normally developing zebrafish embryosDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 7 2009Christina F. Leung Localized Ca2+ signals were consistently visualized in the formed somites of intact zebrafish embryos during the early segmentation period. Unlike the regular process of somitogenesis, these signals were stochastic in nature with respect to time and location. They did, however, occur predominantly at the medial and lateral boundaries within the formed somites. Embryos were treated with modulators of [Ca2+]i to explore the signal generation mechanism and possible developmental function of the stochastic transients. Blocking elements in the phosphoinositol pathway eliminated the stochastic signals but had no obvious effect, stochastic or otherwise, on the formed somites. Such treatments did, however, result in the subsequently formed somites being longer in the mediolateral dimension. Targeted uncaging of buffer (diazo-2) or Ca2+ (NP-ethyleneglycoltetraacetic acid [EGTA]) in the presomitic mesoderm, resulted in a regular mediolateral lengthening and shortening, respectively, of subsequently formed somites. These data suggest a requirement for IP3 receptor-mediated Ca2+ release during convergence cell movements in the presomitic mesoderm, which appears to have a distinct function from that of the IP3 receptor-mediated stochastic Ca2+ signaling in the formed somites. [source] Methods for Generating Longitudinally Correlated Binary DataINTERNATIONAL STATISTICAL REVIEW, Issue 1 2008Patrick J. Farrell Summary The analysis of longitudinally correlated binary data has attracted considerable attention of late. Since the estimation of parameters in models for such data is based on asymptotic theory, it is necessary to investigate the small-sample properties of estimators by simulation. In this paper, we review the mechanisms that have been proposed for generating longitudinally correlated binary data. We compare and contrast these models with regard to various features, including computational efficiency, flexibility and the range restrictions that they impose on the longitudinal association parameters. Some extensions to the data generation mechanism originally suggested by Kanter (1975) are proposed. Résumé L'analyse des données longitudinales corrélées fait récemment l'objet d'un grand intérêt. Comme l'estimation des paramètres des modèles pour de telles données est souvent basée sur des études asymptotiques, il est nécessaire de procéder à des simulations pour explorer les propriétés des estimateurs en petits échantillonages. Dans ce papier, nous présentons une revue des méthodes qui ont été proposées pour générer des données binaires longitudinales corrélées. Nous les comparons sous différents aspects, notamment en termes d'efficience, flexibilité, et des restrictions qu'elles peuvent avoir sur les paramètres dits d'association longitudinale. Quelques extensions, de la méthode suggérée par Kanter (1975) pour générer de telles données, sont aussi proposées. [source] Bayesian conformational analysis of ring molecules through reversible jump MCMCJOURNAL OF CHEMOMETRICS, Issue 8 2005Kim Nolsøe Abstract In this paper, we address the problem of classifying the conformations of m -membered rings using experimental observations obtained by crystal structure analysis. We formulate a model for the data generation mechanism that consists in a multidimensional mixture model. We perform inference for the proportions and the components in a Bayesian framework, implementing a Markov chain Monte Carlo (MCMC) reversible jump algorithm to obtain samples of the posterior distributions. The method is illustrated on a simulated data set and on real data corresponding to cyclo-octane structures. Copyright © 2005 John Wiley & Sons, Ltd. [source] Bed morphology and generation of step,pool channelsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2008Roman B. Weichert Abstract Flume experiments have been carried out to study the formation processes and the bed morphology of step,pool channels. From the experiments different step types and step configurations could be distinguished depending on the stream power. These step types can be seen as an image of the generation mechanisms of step,pool systems. These results suggest that the bed roughness geometry develops towards a condition that provides the maximum possible bed stability for a given grain size distribution. In contrast to a variety of other studies, antidunes did not contribute to the generation of the step structures. However, the data of the presented study fits well into the region of antidune formation proposed by Kennedy for sand-bed rivers. This observation points out that step,pool field-data located in the Kennedy region do not inevitably prove that antidunes played a role in step development. It is rather proposed that in Kennedy's region of antidune formation there exist hydraulic conditions where the flow resistance is maximized. It is suggested that such maximum flow resistance is associated with an optimal distance between the bedforms and their height, independently of whether these are antidunes in sand- and gravel-bed rivers or step,pool units in boulder-bed streams. The considerations of the Kennedy region of antidune formation and the analysis of planform step types depending on stream power both suggest that steep channels have a potential for self-stabilization by modifying the step,pool structure towards a geometry that provides maximum flow resistance and maximum bed stability. Copyright © 2008 John Wiley & Sons, Ltd. [source] Mechanisms and pathways of lateral flow on aspen-forested, Luvisolic soils, Western Boreal Plains, Alberta, CanadaHYDROLOGICAL PROCESSES, Issue 21 2010Todd Redding Abstract Rainfall simulation experiments by Redding and Devito (2008, Hydrological Processes 23: 4287,4300) on two adjacent plots of contrasting antecedent soil moisture storage on an aspen-forested hillslope on the Boreal Plain showed that lateral flow generation occurred only once large soil storage capacity was saturated combined with a minimum event precipitation of 15,20 mm. This paper extends the results of Redding and Devito (2008, Hydrological Processes 23: 4287,4300) with detailed analysis of pore pressure, soil moisture and tracer data from the rainfall simulation experiments, which is used to identify lateral flow generation mechanisms and flow pathways. Lateral flow was not generated until soils were wet into the fine textured C horizon. Lateral flow occurred dominantly through the clay-rich Bt horizon by way of root channels. Lateral flow during the largest event was dominated by event water, and precipitation intensity was critical in lateral flow generation. Lateral flow was initiated as preferential flow near the soil surface into root channels, followed by development of a perched water table at depth, which also interacted with preferential flow pathways to move water laterally by the transmissivity feedback mechanism. The results indicate that lateral flow generated by rainfall on these hillslopes is uncommon because of the generally high available soil moisture storage capacity and the low probability of rainfall events of sufficient magnitude and intensity. Copyright © 2010 John Wiley & Sons, Ltd. [source] Simulating hydrological response for the R-5 catchment: comparison of two models and the impact of the roadsHYDROLOGICAL PROCESSES, Issue 5 2002Keith Loague In this paper the performance of two hydrological-response models is evaluated and compared based upon simulations for a single rainfall,runoff event. The two models are QPBRRM, a relatively simple model of Horton overland flow, and InHM, a comprehensive physics-based model of each of the known streamflow generation mechanisms. The rainfall,runoff event focused upon in this study is from the small rangeland catchment in Oklahoma known as R-5. When calibrated, both QPBRRM and InHM are shown to effectively simulate the R-5 event. The calibration procedures used in this study for QPBRRM and InHM were quite different. The calibration of QPBRRM was a curve fitting exercise, whereas the calibration of InHM was based upon an internally valid estimate of the continuous head field. In this study QPBRRM did not perform well outside of the calibrated range. The impact of the roads cutting across the R-5 catchment is simulated with InHM and discussed for the first time in the study reported here. The relative merits of QPBRRM and InHM are each discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Protein trafficking mechanisms associated with neurite outgrowth and polarized sorting in neuronsJOURNAL OF NEUROCHEMISTRY, Issue 5 2001Bor Luen Tang Neuronal differentiation in vitro and in vivo involves coordinated changes in the cellular cytoskeleton and protein trafficking processes. I review here recent progress in our understanding of the membrane trafficking aspects of neurite outgrowth of neurons in culture and selective microtubule-based polarized sorting in fully polarized neurons, focusing on the involvement of some key molecules. Early neurite outgrowth appears to involve the protein trafficking machineries that are responsible for constitutive trans -Golgi network (TGN) to plasma membrane exocytosis, utilizing transport carrier generation mechanisms, SNARE proteins, Rab proteins and tethering mechanisms that are also found in non-neuronal cells. This vectorial TGN-plasma membrane traffic is directed towards several neurites, but can be switch to concentrate on the growth of a single axon. In a mature neuron, polarized targeting to the specific axonal and dendritic domains appears to involve selective microtubule-based mechanisms, utilizing motor proteins capable of distinguishing microtubule tracks to different destinations. The apparent gaps in our knowledge of these related protein transport processes will be highlighted. [source] | |||||||||||||