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Sampling Points (sampling + point)
Selected AbstractsPartitioning behavior of mercury during coal combustion: the influence of low-NOx burners and operation load of boilerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009Guang-Qian Luo Abstract Two 200 MW, pulverized bituminous coal-fired electric utility boilers each equipped with a five-field cold-side electrostatic precipitator (ESP) as the only air pollution control device (APCD) were investigated on mercury distribution and speciation under various conditions. With the same fuel consumption, both facilities are the same but with different burners, low-NOx type and conventional type. Sampling points of gaseous mercury and chlorine species were at the inlet and outlet of the ESP. The mercury concentrations in various solids, including parent coal, bottom slag, economizer bottom ash and fly ash in different hoppers of ESP, were sampled and analyzed. The Ontario Hydro Method was employed to detect mercury in flue gas, and HCl and Cl2 were detected by the EPA method 26. A series of tests were conducted on the boiler with low-NOx burners under various loads (70, 85 and 100% of full load) and on the other boiler with conventional burners under full load. Results showed that small amount of mercury remained in the solid combustion products and most of mercury was released into the atmosphere. The majority of the released mercury was in oxidized form. Burner types and load variation had effects on Cl species concentration in flue gas. Furthermore, particle diameter and carbon content and specific surface area of fly ash affected speciation and distribution of mercury and mercury removal efficiency of ESP. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Monitoring of DNA breakage in embryonic stages of the African catfish Clarias gariepinus (Burchell, 1822) after exposure to lead nitrate using alkaline comet assayENVIRONMENTAL TOXICOLOGY, Issue 6 2008Alaa G. M. Osman Abstract Increasing lead contamination in Egyptian ecosystems and high lead concentrations in food items have raised concern for human health and stimulated studies on monitoring ecotoxicological impact of lead-caused genotoxicity. In this work, the alkaline comet assay was modified for monitoring DNA strand breakage in sensitive early life stages of the African catfish Clarias gariepinus. Following exposure to 100, 300, and 500 ,g/L lead nitrate, DNA strand breakage was quantified in embryos at 30, 48, 96, 144, and 168 h post-fertilization (PFS). For quantitative analysis, four commonly used parameters (tail % DNA, %TDNA; head % DNA, %HDNA; tail length, TL; tail moment, TM) were analyzed in 96 nuclei (in triplicates) at each sampling point. The parameter %TDNA revealed highest resolution and lowest variation. A strong correlation between lead concentration, time of exposure, and DNA strand breakage was observed. Here, genotoxicity detected by comet assay preceded the manifested malformations assessed with conventional histology. Qualitative evaluation was carried out using five categories are as follows: undamaged (%TDNA , 10%), low damaged (10% < %TDNA , 25%), median damaged (25 < %TDNA , 50%), highly damaged (50 < %TDNA , 75%), and extremely damaged (%TDNA > 75%) nuclei confirming a dose and time-dependent shift towards increased frequencies of highly and extremely damaged nuclei. A protective capacity provided by a hardened chorion is a an interesting finding in this study as DNA damage in the prehatching stages 30 h-PFS and 48 h-PFS was low in all treatments (qualitative and quantitative analyses). These results clearly show that the comet assay is a sensitive tool for the detection of genotoxicity in vulnerable early life stages of the African catfish and is a method more sensitive than histological parameters for monitoring genotoxic effects. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Macro- and Micro-Purge Soil-Gas Sampling Methods for the Collection of Contaminant VaporsGROUND WATER MONITORING & REMEDIATION, Issue 1 2009Brian A. Schumacher Purging influence on soil-gas concentrations for volatile organic compounds (VOCs), as affected by sampling tube inner diameter and sampling depth (i.e., system volume) for temporary probes in fine-grained soils, was evaluated at three different field sites. A macro-purge sampling system consisted of a standard, hollow, 3.2-cm outer diameter (OD) drive probe with a retractable sampling point attached to an appropriate length of 0.48-cm inner diameter (ID) Teflon® tubing. The macro-purge sampling system had a purge system volume of 24.5 mL at a 1-m depth. In contrast, the micro-purge sampling systems were slightly different between the field sites and consisted of a 1.27-cm OD drive rod with a 0.10-cm ID stainless steel tube or a 3.2-cm OD drive rod with a 0.0254-cm inner diameter stainless steel tubing resulting in purge system volumes of 1.2 and 7.05 mL at 1-m depths, respectively. At each site and location within the site, with a few exceptions, the same contaminants were identified in the same relative order of abundances indicating the sampling of the same general soil atmosphere. However, marked differences in VOC concentrations were identified between the sampling systems, with micro-purge samples having up to 27 times greater concentrations than their corresponding macro-purge samples. The higher concentrations are the result of a minimal disturbance of the ambient soil atmosphere during purging. The minimal soil-gas atmospheric disturbance of the micro-purge sampling system allowed for the collection of a sample that is more representative of the soil atmosphere surrounding the sampling point. That is, a sample that does not contain an atmosphere that has migrated from distance through the geologic material or from the surface in response to the vacuum induced during purging soil-gas concentrations. It is thus recommended that when soil-gas sampling is conducted using temporary probes in fine-grained soils, the sampling system use the smallest practical ID soil-gas tubing and minimize purge volume to obtain the soil-gas sample with minimal risk of leakage so that proper decisions, based on more representative soil-gas concentrations, about the site can be made. [source] Energy Saving Speed and Charge/Discharge Control of a Railway Vehicle with On-board Energy Storage by Means of an Optimization ModelIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 6 2009Masafumi Miyatake Member Abstract The optimal operation of rail vehicle minimizing total energy consumption is discussed in this paper. In recent years, the energy storage devices have enough energy and power density to use in trains as on-board energy storage. The on-board storage can assist the acceleration/deceleration of the train and may decrease energy consumption. Many works on the application of the energy storage devices to trains were reported, however, they did not deal enough with the optimality of the control of the devices. The authors pointed out that the charging/discharging command and vehicle speed profile should be optimized together based on the optimality analysis. The authors have developed the mathematical model based on a general optimization technique, sequential quadratic programming. The proposed method can determine the optimal acceleration/deceleration and current commands at every sampling point under fixed conditions of transfer time and distance. Using the proposed method, simulations were implemented in some cases. The electric double layer capacitor (EDLC) is assumed as an energy storage device in our study, because of its high power density etc. The trend of optimal solutions such as values of control inputs and energy consumption is finally discussed. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Spatial dynamics of predation by carabid beetles on slugsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2000David A. Bohan Summary 1.,An explicitly spatial sampling approach was employed to test the null hypothesis that the predation on slugs by the carabid beetle Pterostichus melanarius (Illiger) was opportunistic. 2.,The beetles and slugs were sampled across a nested series of grids of sampling points, in a field of winter wheat during June and July 1997. 3.,The spatial distribution of all slugs in June was found to change with the scale of the sampling grid, from random on the 0.25 m scale, through aggregation at 1 m, to random at 4 m. At the highest scale of 16 m, the slugs were significantly spatially aggregated. 4.,The distribution of beetles in June was also spatially dynamic, with randomness observed at the 4 m and 8 m scales. At 16 m, significant aggregation was observed. 5.,The dynamic distributions of slugs and beetles, at 16 m, were found not to be associated with, and thus were not determined by, soil or crop factors. 6.,Comparison of slug and beetle populations showed, however, that the distributions at 16 m were dynamically associated with each other. In June where there were many slugs there were also many carabids, whilst in July where there were many carabids there were few slugs. 7.,Approximately 11% of the beetles sampled across the 16 m grid in June and July were found to have ingested slug protein, following intensive enzyme-linked immunosorbent assay (ELISA) testing. 8.,The spatial distribution of these slug-positive beetles was significantly associated with the distribution of the larger slug classes, over 25 mg. Where there were many large slugs in June there were many slug-positive beetles. Conversely, in July few large slugs were found where there were many slug-positive beetles. 9.,Parametric analysis revealed that these changes in the large slug class, at each sampling point between June and July (growth), were negatively related to the local numbers of slug-positive beetles, and that growth declined as the local numbers of beetles increased. 10.,These findings suggest that predation was not opportunistic, but direct and dynamic, falsifying the null hypothesis. Moreover, this predation elicited significant changes in the spatial distribution and local density of the slugs, in a manner that may be termed spatially density dependent. [source] Adaptive charting schemes based on double sequential probability ratio testsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 1 2009Yan Li Abstract Sequential probability ratio test (SPRT) control charts are shown to be able to detect most shifts in the mean or proportion substantially faster than conventional charts such as CUSUM charts. However, they are limited in applications because of the absence of the upper bound on the sample size and possibly large sample numbers during implementation. The double SPRT (2-SPRT) control chart, which applies a 2-SPRT at each sampling point, is proposed in this paper to solve some of the limitations of SPRT charts. Approximate performance measures of the 2-SPRT control chart are obtained by the backward method with the Gaussian quadrature in a computer program. On the basis of two industrial examples and simulation comparisons, we conclude that the 2-SPRT chart is competitive in that it is more sensitive and economical for small shifts and has advantages in administration because of fixed sampling points and a proper upper bound on the sample size. Copyright © 2008 John Wiley & Sons, Ltd. [source] Spatial autocorrelation of assemblages of benthic invertebrates and its relationship to environmental factors in two upland rivers in southeastern AustraliaDIVERSITY AND DISTRIBUTIONS, Issue 5 2005Natalie J. Lloyd ABSTRACT The nature of spatial autocorrelation of biota may reveal much about underlying ecological and biological factors responsible for producing those patterns, especially dispersal processes (drift, adult flight, etc.). We report here on assemblage-level autocorrelation in the benthic-invertebrate assemblages (retained in sieves of 300 µm mesh) of riffles in two adjacent, relatively pristine rivers in southeastern Victoria, Australia (40-km reaches of the Wellington and Wonnangatta Rivers). These are related to patterns of autocorrelation in physical and catchment conditions (,environmental variables') in the vicinity of the sampling points. Both the invertebrate assemblages and environmental variables were autocorrelated at small scales (= 8 km) in the Wellington River in one of the sampling years (1996). Dissimilarities of invertebrate assemblages were correlated with dissimilarities of environmental variables in both sampling years (1996 and 1997) in that river. Environmental variables were autocorrelated in the Wonnangatta River, but this was not expressed as autocorrelation in the assemblages of invertebrates, which were not autocorrelated at any scale studied. Individual environmental variables showed different spatial patterns between the two rivers. These results suggest that individual rivers have their own idiosyncratic patterns and one cannot assume that even similar, geographically adjacent rivers will have the same patterns, which is a difficulty for ecological assessment and restoration. [source] Integrative optimization by RBF network and particle swarm optimizationELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 12 2009Satoshi Kitayama Abstract This paper presents a method for the integrative optimization system. Recently, many methods for global optimization have been proposed. The objective of these methods is to find a global minimum of nonconvex function. However, large numbers of function evaluations are required, in general. We utilize the response surface method to approximate function space to reduce the function evaluations. The response surface method is constructed from sampling points. The RBF Network, which is one of the neural networks, is utilized to approximate the function space. Then Particle Swarm Optimization (PSO) is applied to the response surface. The proposed system consists of three parts: (Part 1) generation of the sampling points, (Part 2) construction of response surface by RBF Network, (Part 3) optimization by PSO. By iterating these three parts, it is expected that the approximate global minimum of nonconvex function can be obtained with a small number of function evaluations. Through numerical examples, the effectiveness and validity are examined. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(12): 31,42, 2009; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecj.10187 [source] Quantifying dye tracers in soil profiles by image processingEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2000I. Forrer Summary Developing and testing models for solute transport in the field requires experimental data on the spreading of solutes in the soil. Obtaining such data is costly, and a substantial part of the total costs is in the preparation and chemical analysis of the tracing compounds in the gathered samples. We developed a cheap method to quantify the concentration of the mobile dye tracer Brilliant Blue FCF from digitized photographs of stained soil profiles, and we have tested it in the field. Soil sampling and chemical analyses were necessary only to establish a calibration relation between the dye content and the colour of the soil. The digital images were corrected for geometrical distortions, varying background brightness, and colour tinges, and then they were analysed to determine the soil colour at sampling points in the profiles. The resident concentration of the dye was modelled by polynomial regression with the primary colours red, green, blue and the soil depth as explanatory variables. Concentration maps of Brilliant Blue were then computed from the digitized images with a spatial resolution of 1 mm. Validation of the technique with independent data showed that the method predicted the concentration of the dye well, provided the corrected images contained only the colours included in the calibration. [source] Care needs among the dependent population in Spain: an empirical approachHEALTH & SOCIAL CARE IN THE COMMUNITY, Issue 6 2004J. Garcés PhD Abstract The objective of the present paper was to identify the profile and needs of social and healthcare users in Spain who required long-term care. To achieve this goal, an extensive empirical study was carried out in 2001 of a typical southern European region: the Valencia Autonomous Region in Spain. The method used was a questionnaire-based survey. The data collection instrument was a questionnaire comprising 119 questions grouped into seven sections: social and demographic data; clinical diagnosis and treatment; living environment; degree of dependence in activities of daily living (ADLs); cognitive state; social support; and the social, demographic and attendance data of the carer, if available. The sampling was carried out in two strata, i.e. social and healthcare: first, the authors randomly selected the centres and services as sampling points, and then they randomly selected the subjects. A total of 1265 people were interviewed. The results show different care profiles: users aged under 65 years were mostly mentally ill and/or drug users requiring short- and medium-term care from the health services, while those aged over 65 years had chronic illnesses for which they were actively receiving treatment, were functionally dependent for ADLs, and were normally receiving social care that basically provided company and resolved functional limitations. [source] Changes in hydrology and erosion over a transition from grassland to shrublandHYDROLOGICAL PROCESSES, Issue 4 2010Laura Turnbull Abstract The degradation of grasslands is a common problem across semi-arid areas worldwide. Over the last 150 years, much of the south-western United States has experienced significant land degradation, with desert grasslands becoming dominated by shrubs and concurrent changes in runoff and erosion which are thought to propagate further the process of degradation. Plot-based experiments to determine how spatio-temporal characteristics of soil moisture, runoff and erosion change over a transition from grassland to shrubland were carried out at four sites over a transition from black grama (Bouteloua eriopoda) grassland to creosotebush (Larrea tridentata) shrubland at the Sevilleta NWR LTER site in New Mexico. Each site consisted of a 10 × 30 m bounded runoff plot and adjacent characterization plots with nested sampling points where soil moisture content was measured. Results show distinct spatio-temporal variations in soil moisture content, which are due to the net effect of processes operating at multiple spatial and temporal scales, such as plant uptake of water at local scales versus the redistribution of water during runoff events at the hillslope scale. There is an overall increase in runoff and erosion over the transition from grassland to shrubland, which is likely to be associated with an increase in connectivity of bare, runoff-generating areas, although these increases do not appear to follow a linear trajectory. Erosion rates increased over the transition from grassland to shrubland, likely related in part to changes in runoff characteristics and the increased capacity of the runoff to detach, entrain and transport sediment. Over all plots, fine material was preferentially eroded which has potential implications for nutrient cycling since nutrients tend to be associated with fine sediment. Copyright © 2009 John Wiley & Sons, Ltd. [source] Optimal stress sampling points of plane triangular elements for patch recovery of nodal stressesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2003S. Rajendran Abstract The existence of optimal stress sampling points in finite elements was first observed by Barlow. Knowledge of optimal stress sampling points is important in stress-recovery methods such as the superconvergent patch recovery (SPR). Recently, MacNeal observed that Barlow points and Gaussian quadrature points are the same for the linear and quadratic bar elements, and different for the cubic bar element. Prathap proposed the best-fit approach to predict the optimal sampling points, and showed that the best-fit points coincide with Gaussian quadrature points not only for the linear and quadratic bar elements but also for the cubic bar element. In this paper, the best-fit approach for predicting the optimal sampling points is extended to the linear and quadratic plane triangular elements, and the effectiveness of Barlow points, Gaussian points and best-fit points as candidates of sampling points for the patch recovery of nodal stresses with these triangular elements is investigated for typical problems. The numerical results suggest that Barlow points do not exist for all strain/stress components, and Gaussian quadrature points which are the same as or close to the best-fit points are better candidates for patch recovery. Copyright © 2003 John Wiley & Sons, Ltd. [source] Parametric intensity and the spatial arrangement of the terrestrial mollusc herbivores Deroceras reticulatum and Arion intermediusJOURNAL OF ANIMAL ECOLOGY, Issue 6 2000David A. Bohan Summary 1. Parametric intensity and spatial arrangement analyses were used to investigate the spatial pattern of the slugs Arion intermedius and Deroceras reticulatum. 2. The spatial lag of sampling (distance between sampling points) was shown to be unimportant in the intensity analyses. Rather, the 0·25 m grain scale was imposed on the whole sampling. The observed slope of the variance to mean relationships was common to both species, possibly determined by egg laying in batches at 0·25 m. However, the variance of the sample, for a given mean, was lower in summer. This corresponded with a reduction in the proportion of zero counts, which could be due to slug movement, possibly increased by predator activity, acting at the 0·25 m scale. 3. By contrast with the intensity analyses, the lag scale was important for spatial arrangement. At 0·25 m, in March 1997, the A. intermedius and D. reticulatum juveniles were aggregated, presumably about where egg batches were laid. At higher scales, the arrangements of D. reticulatum became spatially random, and A. intermedius resolved to a patch arrangement at the 16 m scale. 4. Over time, the D. reticulatum spatial arrangements remained random and independent of the previous sampling date. From March to July 1997, the A. intermedius patch persisted. A crash in abundance of both species, between July and October 1997, appeared to destroy the patch, but subsequent association suggested that the patch persisted until March 1998. The arrangements of the species were independent of one another on all sampling dates. 5. These species-specific spatial arrangements were independent of all measured environmental factors and consistent with differences in the local reproduction, survival and migration of A. intermedius and D. reticulatum. 6. This comparative study indicates that the terms aggregated, random and regular should have separate definitions for parametric intensity and spatial arrangement. Furthermore, spatial scale has different meaning in intensity and arrangement analyses. Spatial arrangements are not described by parametric intensity. Spatial arrangements change with spatial scale. Temporal changes in intensity need not manifest as changes in spatial arrangement. [source] The early IL-6 and IL-10 response in trauma is correlated with injury severity and mortalityACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2009J. STENSBALLE Background: Trauma has previously been shown to influence interleukin (IL)-6 and IL-10 levels, but the association of injury severity and mortality with IL-6 and IL-10 responses in the early phase of accidental trauma remains to be investigated. We wished to describe serum levels of IL-6 and IL-10 in the first 24 h after trauma and to assess the relationship with severity of injury and mortality. Methods: Prospective, descriptive cohort study in a Level 1 trauma centre, Copenhagen, Denmark. We included 265 consecutive adult trauma patients admitted directly from the accident scene during an 18-month period. Serum levels of IL-6 and IL-10 were measured upon arrival and at 6, 12, and 24 h after admittance using an enzyme-linked immunosorbent assay. Correlation analysis was used to assess the relationship between Injury Severity Score (ISS) and levels of IL-6 and IL-10. Analysis of variance was used to describe the IL-6 and IL-10 concentrations in relation to 30-day mortality in a mixed-effect model repeated measures analysis. Results: Mortality was 10.9% (29/265) at 30 days. A significant increase of both IL-6 and IL-10 concentrations was found over time, and a significant correlation was found between ISS and the levels of both IL-6 and IL-10 at all sampling points. Serum concentrations of IL-6 and IL-10 were significantly higher in patients not surviving 30 days (P<0.0001). Conclusion: The early systemic inflammatory response measured as IL-6 and IL-10 in serum is correlated with injury severity and 30-day mortality following trauma. [source] CURRENT VARIABILITY SHAPES MORPHOLOGICAL COMPLEXITY IN COLONIAL STREAM DIATOMSJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Passy, S. I.1,2 & Freehafer, D.2 1Department of Biology, Rensselaer Polytechnic Institute, Troy, NY 12180; 2US Geological Survey, 425 Jordan Rd., Troy, NY 12180-8349 USA On August 27, 1999 diatoms were sampled, and current velocity was measured at 81 locations on a regular square sampling grid in an unshaded, cobble-bottom reach of White Creek, NY. The grid had an extent of 16 m2, interval, the distance between neighboring sampling points, of 0.5 m, and grain size, the size of the elementary sampling unit, of 0.01 m2. Six of the seven dominant benthic diatoms were colonial forms, including Diatoma vulgaris, Fragilaria capucina, F. crotonensis, Gomphoneis minuta, Melosira varians, and Synedra ulna. Their morphology and distribution were investigated from the perspective of fractal geometry and stream ecology, respectively. Fractal dimension of diatom colonies, indicative of their shape complexity, ranged from 1.06 to 1.54, demonstrating vast morphological variation from simple geometric shapes to complex outlines. The relative abundance of the six diatoms was regressed against current regime, which ranged from 0.03 to 0.66 m, s -1. All regression models were significant at P < 0.05 and explained between 55% and 94% of the variation in diatom distribution. The diatom niche breadth, i.e. the amount of environmental variability a species can tolerate, was defined from these models and showed substantial variation, from 5 to 14. The regression model of fractal dimension against niche breadth was significant and explained 76% of colonial shape variation, revealing a strong relationship between diatom colonial complexity and habitat variability. This finding suggests that environmental variability could create highly complex colonial morphologies in benthic diatoms as an evo-lutionary strategy for survival in unpredictable environments. [source] Persistence of a plasma melatonin rhythm in constant darkness and its inhibition by constant light in the sleepy lizard, Tiliqua rugosaJOURNAL OF PINEAL RESEARCH, Issue 1 2006Bruce T. Firth Abstract:, This study determined whether a blood plasma melatonin rhythm persists in constant photothermal environments in the sleepy lizard, Tiliqua rugosa. It builds upon an earlier investigation which provided equivocal results as to whether an in vivo melatonin rhythm persists in constant dark (DD) and light (LL) and temperature in this species. Using more frequent sampling points and new assay techniques, the present study showed that the melatonin rhythm persisted for at least 6 days at temperatures of 25 and 33°C in constant dark (DD). The melatonin rhythm, however, was largely eliminated in constant light (LL) at 33°C, thereby contradicting some previous findings in other species of reptiles where melatonin levels were apparently insensitive to an unexpected pulse of light at night. These results demonstrate that the sleepy lizard has a persistent, possibly circadian rhythm of melatonin in DD and constant temperature, and that the rhythm is inhibited by LL and constant temperature. Therefore, the sleepy lizard pineal gland may be an independent oscillator capable of driving the melatonin rhythm and be a transducer of the seasonally changing external photothermal environment. [source] Spatial variability of sequentially extracted P fractions in a silty loamJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2005Elena Heilmann Abstract Knowledge of the spatial distribution of soil P forms in agricultural fields is important for evaluating the risk of P transfer to waterways. The objective of this study was to characterize the spatial variation of total P (Pt) and sequentially extracted P forms in the Ap horizon of arable soils at the field scale. Soil samples were taken on a regular grid of 50 m × 50 m with 40 sampling points. Chemical analyses included basic soil properties, Pt, sequentially extracted P forms, and acid phosphomonoesterase activity. The spatial variability was analyzed by geostatistics and descriptive statistics. The concentrations of Pt ranged from 521 to 1020 mg,kg,1 with lower values observed for Gleysols and Stagnic Phaeozems and higher values for Luvisols and Cambisols. For the sequentially extracted P fractions, the largest coefficients of variation (c.v.) were found for NaHCO3 -Po (41%), NaHCO3 -Pi (36%), NaOH-Po (34%), and resin-P (33%). Despite this great spatial variability, no spatial dependence could be proved by geostatistics because the calculated range of P forms (<10 m) was below the smallest sampling distance (50 m). A clear trend of increasing concentrations and proportions of organic NaHCO3 - and NaOH-P fractions and phosphomonoesterase activity towards lower slope positions and the discharging brook indicated that Gleysols were a particular source of P losses to waterways in this catchment. It was concluded that these soils require a specific management with reduced P inputs and, perhaps, chemical treatment to fix leachable P. Räumliche Variabilität sequenziell extrahierter P-Fraktionen in einem Schlufflehm Kenntnisse über die räumliche Verteilung der P-Formen in landwirtschaftlichen Flächen sind notwendig für die Abschätzung des Risikos von P-Austrägen. Gegenstand dieser Untersuchung war die räumliche Verteilung von Gesamt-P (Pt) und P-Formen im Ap-Horizont von landwirtschaftlich genutzten Böden im Feldmaßstab. Dazu wurden Proben auf einem Raster von 50 m × 50 m an 40 Punkten entnommen. Die chemischen Analysen umfassten Grundeigenschaften sowie Pt, sequenziell extrahierte P-Formen und die Aktivität der sauren Phosphomonoesterase. Die räumliche Variabilität wurde mit räumlicher und deskriptiver Statistik untersucht. Die Pt -Gehalte lagen im Bereich von 521 bis 1020 mg,kg,1, wobei Gleye und Pseudogleye die niedrigsten Werte hatten. Bei den sequenziell extrahierten P-Fraktionen wurden die größten Variationskoeffizienten für NaHCO3 -Po (41%), NaHCO3 -Pi (36 %), NaOH-Po (34 %) und Harz-P (33 %) festgestellt. Trotz dieser großen räumlichen Variabilität konnte mit Geostatistik keine räumliche Abhängigkeit nachgewiesen werden, möglicherweise weil die geschätzte Reichweite der P-Formen mit <10 m unterhalb der kleinsten Beprobungsdistanz von 50 m lag. Deutliche gerichtete Trends steigender Gehalte und Anteile organischer NaHCO3 - und NaOH-P-Fraktionen und Phosphomonoesterase-Aktivitäten hin zu niedrigeren Geländepositionen und zur Nachbarschaft zu dem entwässernden Bach deuteten darauf hin, dass insbesondere Gleye eine Quelle der P-Einträge in Oberflächengewässer des Einzugsgebietes sein können. Es ergibt sich daher die Schlussfolgerung, dass diese Böden einer teilschlagspezifischen Bewirtschaftung mit reduzierten P-Zufuhren und eventuell P-fixierenden Behandlungen bedürfen. [source] Sequential Plasma Lactate Concentrations as Prognostic Indicators in Adult Equine EmergenciesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2010B.S. Tennent-Brown Background: Sequential lactate concentration ([LAC]) measurements have prognostic value in that hospitalized humans and neonatal foals that have a delayed return to normolactatemia have greater morbidity and case fatality rate. Hypothesis: Prognosis for survival is decreased in horses with a delayed return to normal [LAC]. Animals: Two hundred and fifty adult horses presented for emergency evaluation excepting horses evaluated because of only ophthalmologic conditions, superficial wounds, and septic synovitis without systemic involvement. Methods: Prospective observational study. [LAC] was measured at admission and then at 6, 12, 24, 48, and 72 hours after admission. The change in [LAC] over time ([LAC],T) was calculated from changes in [LAC] between sampling points. Results: Median [LAC] was significantly (P < .001) higher at admission in nonsurvivors (4.10 mmol/L [range, 0.60,18.20 mmol/L]) when compared with survivors (1.30 mmol/L [range, 0.30,13.90 mmol/L]) and this difference remained at all subsequent time points. The odds ratio for nonsurvival increased from 1.29 (95% confidence interval 1.17,1.43) at admission to 49.90 (6.47,384) at 72 hours after admission for every 1 mmol/L increase in [LAC]. [LAC],T was initially positive in all horses but became negative and significantly lower in nonsurvivors for the time periods between 24,72 hours (, 0.47, P= .001) and 48,72 hours (, 0.07, P= .032) when compared with survivors (0.00 at both time periods) consistent with lactate accumulation in nonsurvivors. Conclusions and Clinical Importance: These results indicate that lactate metabolism is impaired in critically ill horses and [LAC],T can be a useful prognostic indicator in horses. [source] Optimal acquisition schemes for in vivo quantitative magnetization transfer MRIMAGNETIC RESONANCE IN MEDICINE, Issue 4 2006Mara Cercignani Abstract This paper uses the theory of Cramer-Rao lower bounds (CRLB) to obtain optimal acquisition schemes for in vivo quantitative magnetization transfer (MT) imaging, although the method is generally applicable to any multiparametric MRI technique. Quantitative MT fits a two-pool model to data collected at different sampling points or settings of amplitude and offset frequency in the MT saturation pulses. Here we use simple objective functions based on the CRLB to optimize sampling strategies for multiple parameters simultaneously, and use simulated annealing to minimize these objective functions with respect to the sampling configuration. Experiments compare optimal schemes derived for quantitative MT in the human white matter (WM) at 1.5T with previously published schemes using both synthetic and human-brain data. Results show large reductions in error of the fitted parameters with the new schemes, which greatly increases the clinical potential of in vivo quantitative MT. Since the sampling-scheme optimization requires specific settings of the MT parameters, we also show that the optimum schemes are robust to these settings within the range of MT parameters observed in the brain. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] Thawing permafrost and thicker active layers in sub-arctic SwedenPERMAFROST AND PERIGLACIAL PROCESSES, Issue 3 2008H. Jonas Åkerman Abstract Observations of active-layer thickness from nine sites with up to 29 years of gridded measurements located in the Torneträsk region, northernmost Sweden, were examined in relation to climatic trends. Mean annual air temperatures in this area have warmed and recently rose above 0°C. Active layers at all sites have become thicker, at rates ranging from 0.7 to 1.3,cm per year. This trend has accelerated in the past decade, especially in the westernmost site where rates have reached 2,cm per year and permafrost has disappeared at 81 per cent of the sampling points. Increased active-layer thicknesses are correlated with increases in mean summer air temperature, thawing degree-days and, in five of the nine sites, with increases in snow depth. Copyright © 2008 John Wiley & Sons, Ltd. [source] The spatial pattern of air seeding thresholds in mature sugar maple treesPLANT CELL & ENVIRONMENT, Issue 9 2005BRENDAN CHOAT ABSTRACT Air seeding threshold (Pa) of xylem vessels from current year growth rings were measured along the vertical axis of mature sugar maple trees (Acer saccharum Marsh.), with sampling points in primary leaf veins, petioles, 1-, 3-, and 7-year-old branches, large branches, the trunk and roots. The air seeding threshold was taken as the pressure required to force nitrogen gas through intervessel pit membranes. Although all measurements were made on wood produced in the same year, Pa varied between different regions of A. saccharum, with distal organs such as leaves and petioles having lower Pa than basal regions. Mean (SE) Pa ranged from 1.0 (± 0.1) MPa in primary leaf veins to 4.8 (± 0.1) MPa in the main trunk. Roots exhibited a Pa of 2.8 (± 0.2) MPa, lower than all other regions of the tree except leaf veins and petioles. Mean xylem vessel diameter increased basipetally, with the widest vessels occurring in the trunk and roots. Within the shoot, wider vessels had greater air seeding thresholds, contrasting with trends previously reported. However, further experimentation revealed that differences in Pa between regions of the stem were driven by the presence of primary xylem conduits, rather than differences in vessel diameter. In 1-year-old branches, Pa was significantly lower in primary xylem vessels than in adjacent secondary xylem vessels. This explained the lower values of Pa measured in petioles and leaf veins, which possessed a greater ratio of primary xylem to secondary xylem than other regions. The difference in Pa between primary and secondary xylem was attributed to the greater area of primary cell wall (pit membrane) exposed in primary xylem conduits with helical or annular thickening. [source] Adaptive charting schemes based on double sequential probability ratio testsQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 1 2009Yan Li Abstract Sequential probability ratio test (SPRT) control charts are shown to be able to detect most shifts in the mean or proportion substantially faster than conventional charts such as CUSUM charts. However, they are limited in applications because of the absence of the upper bound on the sample size and possibly large sample numbers during implementation. The double SPRT (2-SPRT) control chart, which applies a 2-SPRT at each sampling point, is proposed in this paper to solve some of the limitations of SPRT charts. Approximate performance measures of the 2-SPRT control chart are obtained by the backward method with the Gaussian quadrature in a computer program. On the basis of two industrial examples and simulation comparisons, we conclude that the 2-SPRT chart is competitive in that it is more sensitive and economical for small shifts and has advantages in administration because of fixed sampling points and a proper upper bound on the sample size. Copyright © 2008 John Wiley & Sons, Ltd. [source] Characterization of diverse plant communities in Aspen Parkland rangeland using LiDAR dataAPPLIED VEGETATION SCIENCE, Issue 3 2007Jason G. Su Moss (1983) Abstract Question: How effective is high-resolution airborne LiDAR technology for quantifying biophysical characteristics of multiple community types within diverse rangeland environments? Location: Native Aspen Parkland vegetation in central Alberta, Canada. Methods: Vegetation within 117 reference plots stratified across eight types, including forest, shrubland, upland grassland and lowland meadow communities, were assessed in 2001 for the height, cover and density of vegetation within various strata (herb, shrub and tree layers). Actual ground data were subsequently compared against modelled values for each community type and strata derived from the analysis of airborne LiDAR data obtained in 2000. Results: LiDAR data were effective for quantifying vegetation height, cover and density of the overstory within closed- and open Populus forest communities. However, LiDAR measurements typically underestimated the height and cover of shrublands, as well as most of the herbaceous communities. Analysis of LiDAR intensity data indicated reflectance generally decreased as LiDAR sampling points moved upwards from the ground to the vegetation canopy. Conclusions: While LiDAR technology is useful for characterizing deciduous forest properties, the quantification of understory vegetation characteristics, as well as those of individual shrublands and grasslands, was more limiting. Further refinements in analysis methods are necessary to increase the reliability of characterizing these communities. [source] Microbial and nutrient pollution in the coastal bathing waters of Dar es SalaamAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009Thomas J. Lyimo Abstract 1.The objective of the present study was to assess the microbial and nutrient quality of coastal beach waters used for bathing in the city of Dar es Salaam, Tanzania. Concentrations of traditional and alternative microbial indicators of faecal pollution and nutrients were assessed over a 1 year period (August 2005 to August 2006) using standard methods and the results were compared with the WHO water quality guidelines. 2.Faecal indicator bacteria values varied in a consistent fashion and correlated significantly with eachother, reflecting the presumed human faecal pollution. 3.The maximum counts (MPN per 100,mL) were observed on the site close to the city centre (Ocean Road) throughout the sampling period where values ranged from 1700 to>240 000 total coliform (TC), 200 to 92000 faecal coliform (FC) and 11 to 4900 enterococci (ENT). Other sites showed less predictable results with a range of values from 0,920, 0,540 and 0,46 for TC, FC and ENT, respectively. Furthermore, the faecal indicator bacteria concentration varied significantly with sampling time (P<0.05) and between sampling points (P<0.05). 4.Similarly, nutrients were significantly higher (P<0.05) at Ocean Road where concentration (µmolL,1) ranges were 0.2,54 (NO3), 0.0,20 (NO2) and 0.3,45 (PO4). 5.The levels of faecal indicator bacteria and nutrients were higher during the rainy seasons than the dry seasons, showing the inclusion of rain run-off as a source of contamination. The faecal indicator bacteria correlated positively with nutrients in both 1 year and daily data sets (P<0.01). Positive relationships were also observed among faecal indicators. This strongly suggests that an important role is played by sewage contamination in the extent of microbial pollution at the studied urbanized coastal beaches. Copyright © 2009 John Wiley & Sons, Ltd. [source] Combining state estimator and disturbance observer in discrete-time sliding mode controller design,ASIAN JOURNAL OF CONTROL, Issue 5 2008Jeang-Lin Chang Abstract In response to a multiple input/multiple output discrete-time linear system with mismatched disturbances, an algorithm capable of performing estimated system states and unknown disturbances is proposed first, and then followed with the design of the controller. Attributed to the fact that both system states and disturbances can be estimated simultaneously with our proposed method, the estimation error is constrained at less than O(T) as the disturbance between the two sampling points is insignificant. In addition, the estimated system states and disturbances are then to be used in the controller when implementing our algorithm in a non-minimum phase system (with respect to the relation between the output and the disturbance). The tracking error is constrained in a small bounded region and the system stability is guaranteed. Finally, a numerical example is presented to demonstrate the applicability of the proposed control scheme. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source] Effektiver Algorithmus zur Lösung von inversen Aufgabenstellungen , Anwendung in der GeomechanikBAUTECHNIK, Issue 7 2006Jörg Meier Dipl.-Ing. Durch den Einsatz von numerischen Modellen für ingenieurtechnische Problemstellungen, wie z. B. der FEM oder der FDM, können zunehmend komplexere Berechnungen in immer kürzerer Zeit bewältigt werden. Gleichzeitig ergibt sich jedoch bei dem Einsatz dieser Werkzeuge der Bedarf an Werten für die verschiedenen Modellparameter, von rein konstitutiven Kennwerten bis hin zu geometrischen Angaben, für deren Bestimmung zunehmend inverse Verfahren Anwendung finden. Bei der Nutzung dieser Methoden ist jedoch , insbesondere bei komplizierten Simulationen , mit sehr langen Berechnungszeiten zu rechnen. Gegenstand dieses Beitrags ist die Vorstellung einer Verfahrensklasse, die eine Abschätzung der Lösung solcher inverser Aufgaben auf der Basis von relativ wenigen Stützstellen ermöglicht. An die Verteilung der Stützstellen werden geringste Anforderungen gestellt, so daß diese wahlweise aus vorhergehenden Simulationen oder auch aus alternativen Quellen stammen können. Im Rahmen dieses Beitrags soll ausgehend von einer Einführung in den theoretischen Ansatz eine Strategie zur Beschleunigung der Lösung von inversen Problemstellungen und Optimierungsaufgaben an einem Beispiel aus dem Gebiet der Geomechanik vorgestellt werden. Effective algorithm for solving inverse problems , geomechanical application. When working with numerical models, it is essential to determine model parameters which are as realistic as possible. Optimization techniques are being employed more and more frequently for solving this task. However, using these methods may lead to very high time costs , in particular, if rather complicated forward calculations are involved. In this paper, we present a class of methods that allows estimating the solution of this kind of optimization problems based on relatively few sampling points. We put very weak constraints on the sampling point distribution; hence, they may be taken from previous forward calculations as well as from alternative sources. Starting from an introduction into the theoretical approach, a strategy for speeding up inverse optimization problems is introduced which is illustrated by an example geomechanics. [source] Fine-scale Microhabitat Heterogeneity in a French Guianan ForestBIOTROPICA, Issue 4 2010Christopher Baraloto ABSTRACT We examined fine-scale heterogeneity of environmental conditions in a primary rain forest in French Guiana to describe variation in microhabitats that plants may experience during establishment. We characterized both the range as well as the spatial structuring of 11 environmental factors important for seedling establishment in six hexagonal sampling grids, one each in gap and understory sites at three points representing the predominant geomorphic units in this primary forest. Each grid contained 37 sampling points separated by 31 cm,20 m. Monte-Carlo tests of semivariograms against complete spatial randomness indicated that for many variables in all six sampling grids, spatial dependence did not exceed 1 m. A principal component analysis of all sampling points revealed a lack of spatial microhabitat structure, rather than homogeneous patches associated with canopy structure or geomorphology. Our results suggest that ample fine-scale spatial heterogeneity exists to support the coexistence of plant species with differential abiotic requirements for regeneration. [source] Serum neuron-specific enolase, prolactin, and creatine kinase after epileptic and psychogenic non-epileptic seizuresACTA NEUROLOGICA SCANDINAVICA, Issue 5 2004C. Willert Purpose , To evaluate the discriminative power of serial, simultaneous determinations of serum neuron-specific enolase (NSE), prolactin (PRL) and creatine kinase (CK) in differentiating psychogenic non-epileptic seizures (PNES) from epileptic seizures (ES). Methods , Prospective measurement of the three markers after 44 single seizures (32 ES and 12 PNES) during continuous video-EEG monitoring at seven different sampling points. Results , Patients with ES had a significantly greater increase in PRL at 10, 20, 30 min, 1 and 6 h. The sensitivity for elevated NSE and CK was low. PRL showed a higher sensitivity. However, the corresponding positive predictive value was lower than in CK and NSE. Additionally, PRL had the lowest specificity of all parameters. Conclusions , The limited discriminative power of PRL, CK, and NSE calls into question if these markers are helpful in differentiating PNES and ES. [source] | ||||||||||||||||||||||