Home About us Contact
|
Home About us Contact | ||
|
|
||
Several Processes (several + process)
Selected AbstractsMonitoring and predicting channel change in a free-evolving, small Alpine river: Ridanna Creek (North East Italy)EARTH SURFACE PROCESSES AND LANDFORMS, Issue 14 2007Rossella Luchi Abstract The recent (25 years) morphodynamics of a proglacial reach of the Ridanna Creek, North-East Italy, evolving in the absence of human constraints, has been investigated by means of an intensive field activity and of the analysis of aerial photographs. The study reach mostly displays a braided morphology, with sharp downstream variations of valley gradient, sediment size and formative conditions within the main channel. These discontinuities are associated with different processes of channel adjustment at different timescales, which have been quantified by coupling hydrological with morphological information. Several processes of channel change and variations in braiding intensity have been documented along the whole reach and highlight how a regular, weakly meandering main channel may significantly affect the morphodynamics of the braided network. A first attempt to predict the morphological instability of this main channel at the observed spatial scales through existing linear theories of curved river channels shows a good agreement with field observations. Finally, the complete hydro-morphodynamical characterization of such an undisturbed alpine river reach can provide a relevant contribution to the definition of reference conditions for Alpine rivers required by the EU Water Framework Directive. Copyright © 2007 John Wiley & Sons, Ltd. [source] Geological history and within-island diversity: a debris avalanche and the Tenerife lizard Gallotia gallotiMOLECULAR ECOLOGY, Issue 12 2006RICHARD P. BROWN Abstract Several processes have been described that could explain geographical variation and speciation within small islands, including fragmentation of populations through volcanic eruptions. Massive landslides, or debris avalanches, could cause similar effects. Here we analyse the potential impact of the 0.8 million-year-ago (Ma) Güimar valley debris avalanche on the phylogeography of the lizard Gallotia galloti on the Canary Island of Tenerife. Distributions of mitochondrial DNA lineages (based on cytochrome b sequences) were analysed on a 60-km southeastern coast transect centred on this area. Three main clades were detected, which can be divided into northern (one clade) and southern (two clades) groups that introgress across the valley. Maximum-likelihood estimates of migration rates (scaled for mutation rate) revealed highly asymmetric patterns, indicating that long-term gene flow into this region from both the northern and the southern populations greatly exceeded that in the opposite directions, consistent with recolonization of the area. The ancestral Tenerife node on the G. galloti tree is estimated at 0.80 Ma, matching closely with the geological estimate for the debris avalanche. Morphological variation (body dimensions and scalation) was also analysed and indicated a stepped cline in female scalation across the valley, although the patterns for male scalation and male and female body dimensions were not as clear. Together these findings provide support for the hypothesis that the debris avalanche has shaped the phylogeography of G. galloti and may even have been a primary cause of the within-island cladogenesis through population fragmentation and isolation. Current estimates of timing of island unification mean that the original hypothesis that within-island diversity is explained by the secondary contact of populations from the two ancient precursor islands of Teno and Anaga is less plausible for this and some other Tenerife species. Large-scale landslides have occurred on many volcanic islands, and so may have been instrumental in shaping within-island diversities. [source] Staging of multiple sclerosis (MS) lesions: pathology of the time frame of MSNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 1 2000P. Van Der Valk Several processes take place during an attack of demyelination in multiple sclerosis (MS). The timing of these various processes, and thus of the attack in its entirety, is important if therapeutic stratagies are to be planned. Attempts have been made to introduce and investigate variables relevant to timing the disease processes, leading to staging systems for MS. Here, the terminology and the various parameters used are reviewed, including inflammatory cells, glial cells, axonal loss and myelin staining; then the different systems are compared, including the system put forward by Bö and Trapp, our own modification of that, the Brück and Lassmann system and the recent consensus reached at a Vienna meeting. It is concluded that an ideal staging system does not yet exist, and that, more than anything else, the material dictates the choice for a staging system. The terminology of the Vienna consensus could be used as a reference to facilitate international comparison. [source] Annotation: Recent Research Examining the Role of Peer Relationships in the Development of PsychopathologyTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 5 2001Kirby Deater-Deckard This Annotation highlights recent research on the role of peer group and friendship factors in the development of psychopathology in childhood and adolescence. Several processes are considered, including peer rejection (e.g., exclusion and victimization), social withdrawal and avoidance of peer interaction, and the socialization of deviant behavior and internalizing problems. The mediating influences of several proximal components are examined, including cognitive-perceptual factors and emotion regulation. In addition, the moderating ifluences of close friendship, age, gender, ethnicity, and group norms are considered. Several promising avenues for future directions in research are highlighted, including the examination of heterogeneity in developmental processes, further investigation of gender-based norms, and the application of multi-level modeling techniques and gene-environment process models. [source] Evaluation of six process-based forest growth models using eddy-covariance measurements of CO2 and H2O fluxes at six forest sites in EuropeGLOBAL CHANGE BIOLOGY, Issue 3 2002K. Kramer Abstract Reliable models are required to assess the impacts of climate change on forest ecosystems. Precise and independent data are essential to assess this accuracy. The flux measurements collected by the EUROFLUX project over a wide range of forest types and climatic regions in Europe allow a critical testing of the process-based models which were developed in the LTEEF project. The ECOCRAFT project complements this with a wealth of independent plant physiological measurements. Thus, it was aimed in this study to test six process-based forest growth models against the flux measurements of six European forest types, taking advantage of a large database with plant physiological parameters. The reliability of both the flux data and parameter values itself was not under discussion in this study. The data provided by the researchers of the EUROFLUX sites, possibly with local corrections, were used with a minor gap-filling procedure to avoid the loss of many days with observations. The model performance is discussed based on their accuracy, generality and realism. Accuracy was evaluated based on the goodness-of-fit with observed values of daily net ecosystem exchange, gross primary production and ecosystem respiration (gC m,2 d,1), and transpiration (kg H2O m,2 d,1). Moreover, accuracy was also evaluated based on systematic and unsystematic errors. Generality was characterized by the applicability of the models to different European forest ecosystems. Reality was evaluated by comparing the modelled and observed responses of gross primary production, ecosystem respiration to radiation and temperature. The results indicated that: Accuracy. All models showed similar high correlation with the measured carbon flux data, and also low systematic and unsystematic prediction errors at one or more sites of flux measurements. The results were similar in the case of several models when the water fluxes were considered. Most models fulfilled the criteria of sufficient accuracy for the ability to predict the carbon and water exchange between forests and the atmosphere. Generality. Three models of six could be applied for both deciduous and coniferous forests. Furthermore, four models were applied both for boreal and temperate conditions. However, no severe water-limited conditions were encountered, and no year-to-year variability could be tested. Realism. Most models fulfil the criterion of realism that the relationships between the modelled phenomena (carbon and water exchange) and environment are described causally. Again several of the models were able to reproduce the responses of measurable variables such as gross primary production (GPP), ecosystem respiration and transpiration to environmental driving factors such as radiation and temperature. Stomatal conductance appears to be the most critical process causing differences in predicted fluxes of carbon and water between those models that accurately describe the annual totals of GPP, ecosystem respiration and transpiration. As a conclusion, several process-based models are available that produce accurate estimates of carbon and water fluxes at several forest sites of Europe. This considerable accuracy fulfils one requirement of models to be able to predict the impacts of climate change on the carbon balance of European forests. However, the generality of the models should be further evaluated by expanding the range of testing over both time and space. In addition, differences in behaviour between models at the process level indicate requirement of further model testing, with special emphasis on modelling stomatal conductance realistically. [source] Medium Effect on the Reaction of N -Butyl-2,4,6-trinitroaniline with NaOH,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2007María Laura Salum Abstract The kinetics of the reaction of N -butyl-2,4,6-trinitroaniline (3) with NaOH have been studied in 10 and 60,% 1,4-dioxane/H2O at 25 °C. In both cases, several processes were observed. In 10,% 1,4-dioxane/H2O the only product formed was 2,4,6-trinitrophenol (4), whereas in 60,% 1,4-dioxane/H2O a mixture of 4 and 5,7-dinitro-2-propyl-1H -benzimidazole 3-oxide (5) was observed in ratios that depend on the HO, concentration. A mechanism involving the formation of , complexes through the addition of one or two HO, anions to unsubstituted ring positions is proposed for 2,4,6-trinitrophenol formation. The presence of these complexes was confirmed by NMR studies in 60,% [D8]1,4-dioxane/D2O. The mechanism suggested for the formation of the N -oxide includes the cyclization of an N -alkylidene-2-nitrosoaniline-type intermediate as the rate-determining step. The decrease in solvent polarity produces a decrease in the observed rate constant for the formation of 4 of about one order of magnitude making the cyclization reaction a competitive pathway. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] New concepts of microbial treatment processes for the nitrogen removal in wastewaterFEMS MICROBIOLOGY REVIEWS, Issue 4 2003Ingo Schmidt Abstract Many countries strive to reduce the emissions of nitrogen compounds (ammonia, nitrate, NOx) to the surface waters and the atmosphere. Since mainstream domestic wastewater treatment systems are usually already overloaded with ammonia, a dedicated nitrogen removal from concentrated secondary or industrial wastewaters is often more cost-effective than the disposal of such wastes to domestic wastewater treatment. The cost-effectiveness of separate treatment has increased dramatically in the past few years, since several processes for the biological removal of ammonia from concentrated waste streams have become available. Here, we review those processes that make use of new concepts in microbiology: partial nitrification, nitrifier denitrification and anaerobic ammonia oxidation (the anammox process). These processes target the removal of ammonia from gases, and ammonium-bicarbonate from concentrated wastewaters (i.e. sludge liquor and landfill leachate). The review addresses the microbiology, its consequences for their application, the current status regarding application, and the future developments. [source] Predicting changes in community composition and ecosystem functioning from plant traits: revisiting the Holy GrailFUNCTIONAL ECOLOGY, Issue 5 2002S. Lavorel Summary 1The concept of plant functional type proposes that species can be grouped according to common responses to the environment and/or common effects on ecosystem processes. However, the knowledge of relationships between traits associated with the response of plants to environmental factors such as resources and disturbances (response traits), and traits that determine effects of plants on ecosystem functions (effect traits), such as biogeochemical cycling or propensity to disturbance, remains rudimentary. 2We present a framework using concepts and results from community ecology, ecosystem ecology and evolutionary biology to provide this linkage. Ecosystem functioning is the end result of the operation of multiple environmental filters in a hierarchy of scales which, by selecting individuals with appropriate responses, result in assemblages with varying trait composition. Functional linkages and trade-offs among traits, each of which relates to one or several processes, determine whether or not filtering by different factors gives a match, and whether ecosystem effects can be easily deduced from the knowledge of the filters. 3To illustrate this framework we analyse a set of key environmental factors and ecosystem processes. While traits associated with response to nutrient gradients strongly overlapped with those determining net primary production, little direct overlap was found between response to fire and flammability. 4We hypothesize that these patterns reflect general trends. Responses to resource availability would be determined by traits that are also involved in biogeochemical cycling, because both these responses and effects are driven by the trade-off between acquisition and conservation. On the other hand, regeneration and demographic traits associated with response to disturbance, which are known to have little connection with adult traits involved in plant ecophysiology, would be of little relevance to ecosystem processes. 5This framework is likely to be broadly applicable, although caution must be exercised to use trait linkages and trade-offs appropriate to the scale, environmental conditions and evolutionary context. It may direct the selection of plant functional types for vegetation models at a range of scales, and help with the design of experimental studies of relationships between plant diversity and ecosystem properties. [source] DIFFERENTIAL SUBURBAN DEVELOPMENT IN THE PRAGUE URBAN REGIONGEOGRAFISKA ANNALER SERIES B: HUMAN GEOGRAPHY, Issue 2 2007Martin Ou ABSTRACT. Numerous authors have asserted that suburbanization contributes to many problems in both suburban and inner city localities. Research of suburban development demonstrates variations in spatial patterns, the intensity of spatial processes, and the social and economic status of new suburbanites. While some forms of suburban development could cause serious problems throughout the urban region, other forms could be perceived as processes improving the quality of life in suburbia. This paper seeks to investigate different types of suburban development in the Prague urban region over the past fifteen years of transformation. The focus of my interest is residential suburbanization, which is one of the most significant spatial processes today in the settlement systems of post-socialist countries. The theoretical part of the contribution deals with the differentiation of spatial processes changing the suburban zone. Here I discuss the concepts of several processes of suburban development and their distinctive impact on both suburban and inner city localities. The empirical part of the contribution is based on an analysis of migration flows in the various localities of the Prague urban region in the period 1995 to 2003. I attempt to describe the magnitude and spatial patterns of suburbanization and the composition of migrants to suburbia. The paper concludes with a discussion about the possible future development of suburbanization in the Prague urban region. [source] Efficiencies of NaOH production methods in a Kraft pulp millINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2009Tobias Richards Abstract There are several processes in a Kraft pulp mill where there is a need for sodium hydroxide, e.g. in the digester and the bleaching plant. The objective of this study is to perform a preliminary evaluation, intended to select the best alternative for producing sodium hydroxide on a Kraft pulp mill site. The first step of the evaluation consists of screening available processes for producing sodium hydroxide needed in the mill. The first step of the evaluation shows that the two best options for increasing the production of sodium hydroxide for internal use in a mill are the conventional lime cycle process or direct causticization with titanates. The second step of the evaluation compares the lime cycle and the titanate process using first and second law analyses to determine the energy requirement and the exergy efficiencies of both processes. Such analyses show a higher energy requirement and a lower exergy efficiency in the titanate process than in the lime cycle process without any heat integration. However, the titanate process shows better performance in terms of energy requirement and exergy efficiency than the lime cycle, if heat is integrated into both processes. The titanate process requires, in the best case, only 80% of the energy required for a fully heat-integrated lime cycle process. Copyright © 2009 John Wiley & Sons, Ltd. [source] A C1 microkinetic model for methane conversion to syngas on Rh/Al2O3AICHE JOURNAL, Issue 4 2009Matteo Maestri Abstract A microkinetic model capable of describing multiple processes related to the conversion of natural gas to syngas and hydrogen on Rh is derived. The parameters of microkinetic models are subject to (intrinsic) uncertainty arising from estimation. It is shown that intrinsic uncertainty could markedly affect even qualitative model predictions (e.g., the rate-determining step). In order to render kinetic models predictive, we propose a hierarchical, data-driven methodology, where microkinetic model analysis is combined with a comprehensive, kinetically relevant set of nearly isothermal experimental data. The new, thermodynamically consistent model is capable of predicting several processes, including methane steam and dry reforming, catalytic partial oxidation, H2 and CO rich combustion, water-gas shift and its reverse at different temperatures, space velocities, compositions and reactant dilutions, using the measured Rh dispersion as an input. Comparison with other microkinetic models is undertaken. Finally, an uncertainty analysis assesses the effect of intrinsic uncertainty and catalyst heterogeneity on the overall model predictions. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Molecular mechanisms of membrane transport of vitamin EMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 5 2010Tappei Takada Abstract Vitamin E is an essential fat-soluble micronutrient for higher mammals and functions as an antioxidant for lipids and also as a regulator of gene expression and a modulator of cell signaling and proliferation. To exert its physiological functions, vitamin E must achieve an appropriate disposition throughout the body via several processes, such as intestinal absorption, uptake and efflux in peripheral tissues and biliary secretion. In this review, we mainly discuss membrane proteins involved in these transport processes (ATP-binding cassette transporter A1, scavenger receptor class B type I, Niemann-Pick C1-like 1 and multidrug resistance 3) and vitamin E-mediated regulation of their expression. [source] Evidence for top predator control of a grazing ecosystemOIKOS, Issue 11 2008Douglas A. Frank The importance of top predators in controlling ecological processes in large, intact ecosystems is unclear. In grasslands that support abundant ungulates, top,down control by predators may be particularly important, because of the tight biogeochemical linkages of ungulate prey with plants and soil microbes. Here, I examined the effects of the recent reintroduction of the gray wolf Canis lupus on ecosystem processes in Yellowstone National Park, where herds of grazing ungulates previously have been shown to stimulate several processes, including soil net nitrogen (N) mineralization. Rates of ungulate grazing intensity and soil net N mineralization were compared before and after wolf reintroduction in grasslands ranging five-fold in aboveground production. Grazing intensity and grassland net N mineralization declined after wolf reintroduction, a likely partial function of fewer ungulates; wolf predation has been one of several factors implicated in causing the decline in Yellowstone ungulates. In addition, the spatial pattern of grazing and net N mineralization changed after reintroduction. A shift in the spatial patterns of grazer-associated processes is consistent with a growing body of work indicating that wolves have changed habitat use patterns of ungulates in Yellowstone National Park. These findings suggest widespread wolf effects on ungulate prey, plants, and microbial activity that have spatially reorganized grassland energy and nutrient dynamics in Yellowstone Park. [source] Optimization of underlying layer and the device structure for group-III-nitride-based UV emitters on sapphirePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008K. Iida Abstract Epitaxial lateral overgrowth (ELO) was applied for the growth of AlGaN on a sapphire substrate by metalorganic vapor phase epitaxy. Among several processes, the ELO of AlGaN on grooved AlGaN showed the best surface morphology and the lowest dark-spot density of 1×108 cm,2 as measured using cathodoluminescence. The light output power of a UV LED fabricated on ELO-Al0.25Ga0.75N on grooved Al0.25Ga0.75N was the strongest among several UV LEDs fabricated by different processes. The effect of the Al composition in the electron-blocking (EB) layer on the performance of UV LEDs was investigated. The UV LED with a low-Al-content EB layer showed high output power under a low-injection condition, while the output power of a UV LED with a high-Al-content EB layer did not saturate even under a high-injection condition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Identifying the time of polynomial drift in the mean of autocorrelated processesQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 5 2010Marcus B. Perry Abstract Control charts are used to detect changes in a process. Once a change is detected, knowledge of the change point would simplify the search for and identification of the special ause. Consequently, having an estimate of the process change point following a control chart signal would be useful to process engineers. This paper addresses change point estimation for covariance-stationary autocorrelated processes where the mean drifts deterministically with time. For example, the mean of a chemical process might drift linearly over time as a result of a constant pressure leak. The goal of this paper is to derive and evaluate an MLE for the time of polynomial drift in the mean of autocorrelated processes. It is assumed that the behavior in the process mean over time is adequately modeled by the kth-order polynomial trend model. Further, it is assumed that the autocorrelation structure is adequately modeled by the general (stationary and invertible) mixed autoregressive-moving-average model. The estimator is intended to be applied to data obtained following a genuine control chart signal in efforts to help pinpoint the root cause of process change. Application of the estimator is demonstrated using a simulated data set. The performance of the estimator is evaluated through Monte Carlo simulation studies for the k=1 case and across several processes yielding various levels of positive autocorrelation. Results suggest that the proposed estimator provides process engineers with an accurate and useful estimate for the last sample obtained from the unchanged process. Copyright © 2009 John Wiley & Sons, Ltd. [source] Judicial Review and Deliberative Democracy: A Circular Model of Law Creation and LegitimationRATIO JURIS, Issue 4 2001Mark Van Hoecke In this paper the author discusses the legitimation of judicial review of legislation. He argues that such a legitimation is not just a moral matter but is to be considered more generally in terms of societal acceptability, since it is based on a wide range of reasons including moral, social and pragmatic concerns. Moreover, the paper stresses that the legitimation of judicial decisions should be properly viewed in a circular perspective, so that the relationship between legislators and judges cannot be reduced to an absolute supremacy of those who are democratically elected over those who apply the law. On the contrary, the law is constantly made, adapted and developed in legal practice and legal decisions are basically legitimated through several processes of deliberative communication. [source] Novel peptide from spider venom inhibits P2X3 receptors and inflammatory painANNALS OF NEUROLOGY, Issue 5 2010Eugene V. Grishin PhD P2X3 purinoreceptors expressed in mammalian sensory neurons play a key role in several processes, including pain perception. From the venom of the Central Asian spider Geolycosa sp., we have isolated a novel peptide, named purotoxin-1 (PT1), which is to our knowledge the first natural molecule exerting powerful and selective inhibitory action on P2X3 receptors. PT1 dramatically slows down the removal of desensitization of these receptors. The peptide demonstrates potent antinociceptive properties in animal models of inflammatory pain. ANN NEUROL 2010;67:680,683 [source] Signals from the epoch of cosmological recombination , Karl Schwarzschild Award Lecture 2008ASTRONOMISCHE NACHRICHTEN, Issue 7 2009R. A. Sunyaev Abstract The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of physical processes, still finding potentially measurable consequences for the energy spectrum and temperature anisotropies of the Cosmic Microwave Background (CMB). In this contribution we provide a short historical overview in connection with the cosmological recombination epoch and its connection to the CMB. Also we highlight some of the detailed physics that were studied over the past few years in the context of the cosmological recombination of hydrogen and helium. The impact of these considerations is two-fold: (i) The associated release of photons during this epoch leads to interesting and unique deviations of the CosmicMicrowave Background (CMB) energy spectrum from a perfect blackbody, which, in particular at decimeter wavelength and the Wien part of the CMB spectrum, may become observable in the near future. Despite the fact that the abundance of helium is rather small, it still contributes a sizeable amount of photons to the full recombination spectrum, leading to additional distinct spectral features. Observing the spectral distortions from the epochs of hydrogen and helium recombination, in principle would provide an additional way to determine some of the key parameters of the Universe (e.g. the specific entropy, the CMB monopole temperature and the pre-stellar abundance of helium). Also it permits us to confront our detailed understanding of the recombination process with direct observational evidence. In this contribution we illustrate how the theoretical spectral template of the cosmological recombination spectrum may be utilized for this purpose. We also show that because hydrogen and helium recombine at very different epochs it is possible to address questions related to the thermal history of our Universe. In particular the cosmological recombination radiation may allow us to distinguish between Compton y -distortions that were created by energy release before or after the recombination of the Universe finished. (ii) With the advent of high precision CMB data, e.g. as will be available using the PLANCK Surveyor or CMBPOL, a very accurate theoretical understanding of the ionization history of the Universe becomes necessary for the interpretation of the CMB temperature and polarization anisotropies. Here we show that the uncertainty in the ionization history due to several processes, which until now were not taken in to account in the standard recombination code RECFAST, reaches the percent level. In particular He II , He I recombination occurs significantly faster because of the presence of a tiny fraction of neutral hydrogen at z , 2400. Also recently it was demonstrated that in the case of H I Lyman , photons the timedependence of the emission process and the asymmetry between the emission and absorption profile cannot be ignored. However, it is indeed surprising how inert the cosmological recombination history is even at percent-level accuracy. Observing the cosmological recombination spectrum should in principle allow us to directly check this conclusion, which until now is purely theoretical. Also it may allow to reconstruct the ionization history using observational data (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||