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Maximum Reduction (maximum + reduction)
Selected AbstractsA one-dimensional model for simulating armouring and erosion on hillslopes: 2.EARTH SURFACE PROCESSES AND LANDFORMS, Issue 10 2007Long term erosion, armouring predictions for two contrasting mine spoils Abstract This paper investigates the dynamics of soil armouring as a result of fluvial erosion for a non-cohesive sandy gravel spoil from the Ranger Mine, Australia, and a cohesive silt loam spoil from the Northparkes Mine, Australia, using a model for hillslope soil armouring. These long term predictions concentrate on the temporal and spatial changes of the spoil grading and erosion over 100,200 years for the flat cap regions (1,2%) and steep batter edges (10,30%) typically encountered on waste rock dumps. The existence of a significant rock fragment fraction in the Ranger spoil means that it armours readily, while Northparkes does not. For Ranger the waste rock showed reductions in (1) cumulative erosion of up to 81% from that obtained by extrapolating the initial erosion rate out 100 years and (2) the erosion/year by more than 10-fold. For Northparkes reductions were less marked, with the maximum reduction in erosion/year being 37% after 200 years. For Ranger the reductions were greatest and fastest for intermediate gradient hillslopes. For the steepest hillslopes the armouring decreased because the flow shear stresses were large enough to mobilize all material in the armour layer. Model uncertainty was assessed with probabilistic confidence limits demonstrating that these erodibility reductions were statistically significant. A commonly used hillslope erosion model (sediment flux = ,1 discharge m1 slope n1) was fitted to these predictions. The erodibility, ,1, and m1 decreased with time, which was consistent with our physical intuition about armouring. At Ranger the parameter m1 asymptoted to 1·5,1·6 while at Northparkes it asymptoted to 1·2,1·3. At Ranger transient spatial trends in armouring led to a short term (50,200 years in the future) reduction in n1, to below zero under certain circumstances, recovering to an asymptote of about 0·5,1. At Northparkes n1 asymptoted to about 0·6, with no negative transients predicted. The m1 and n1 parameters predicted for Ranger were shown to be consistent with field data from a 10-year-old armoured hillslope and consistent with published relationships between erodibility and rock content for natural hillslopes. Copyright © 2007 John Wiley & Sons, Ltd. [source] Various cells of the immune system and intestine differ in their capacity to reduce hexavalent chromiumFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2003Richa Shrivastava Abstract The cells of the immune system form a strong line of defence against foreign substances. The present study was undertaken to investigate the capacity of different cells of Wistar rats to reduce potentially carcinogenic hexavalent chromium (Cr-VI) into less toxic trivalent chromium in vitro. 5×106 cells were incubated with 10 or 25 ,g ml,1 of Cr (VI) in the form of K2Cr2O7 at 37°C in the presence of 5% CO2 in air. At various time periods the remaining amount of Cr (VI) was measured and the percentage of Cr (VI) reduced was calculated. Among the single cell suspensions from the splenic cells a peak reduction of 55% was observed with the total spleen cells, 40% with the B-lymphocyte-enriched subpopulation, 10% with T-lymphocytes and 24% with the macrophages. The reduction by splenic and peritoneal macrophages was similar. Total thymocytes reduced 54% of the Cr (VI). Since the most common route of entry of chromium is through drinking water and food, intestinal cells were also investigated. Among the intestinal cells the maximum reduction of 100% (of 10 ,g ml,1) was observed with the upper villus cells and 72% with the middle villus cells while reduction was the least (4%) with the crypt cells. The reduction in the intestinal loop in situ was 100%. The time taken by each cell type for the peak reduction to Cr (VI) was markedly different. The findings thus show that the capacity of different cells in the body differs vastly in their capacity and time taken to reduce hexavalent chromium. The most efficient handling of Cr (VI) by the intestine, due to the presence of a variety of cells and bacteria, protects the body from its adverse effects. [source] Accelerating iterative solution methods using reduced-order models as solution predictorsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2006R. Markovinovi Abstract We propose the use of reduced-order models to accelerate the solution of systems of equations using iterative solvers in time stepping schemes for large-scale numerical simulation. The acceleration is achieved by determining an improved initial guess for the iterative process based on information in the solution vectors from previous time steps. The algorithm basically consists of two projection steps: (1) projecting the governing equations onto a subspace spanned by a low number of global empirical basis functions extracted from previous time step solutions, and (2) solving the governing equations in this reduced space and projecting the solution back on the original, high dimensional one. We applied the algorithm to numerical models for simulation of two-phase flow through heterogeneous porous media. In particular we considered implicit-pressure explicit-saturation (IMPES) schemes and investigated the scope to accelerate the iterative solution of the pressure equation, which is by far the most time-consuming part of any IMPES scheme. We achieved a substantial reduction in the number of iterations and an associated acceleration of the solution. Our largest test problem involved 93 500 variables, in which case we obtained a maximum reduction in computing time of 67%. The method is particularly attractive for problems with time-varying parameters or source terms. Copyright © 2006 John Wiley & Sons, Ltd. [source] Sensitivity of Alpine snow cover to European temperatureINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 10 2007Michael Hantel Abstract The number of days with snow cover at 268 Alpine climate stations in the winters of 1961,2000 has been investigated with respect to the mean winter temperature over Europe. The corresponding description, originally developed for Austria and recently applied to Switzerland, consists in fitting a logistic curve to the observed data. The slope of this curve, originally the hyperbolic tangent function, is interpreted as the sensitivity of the snow duration-temperature relationship. Here we first demonstrate with a physical-statistical model that the proper logistic curve is not the hyperbolic tangent, but the error function, generated through the pdf of the fluctuating temperature; the slope of this curve is inversely proportional to the standard deviation of temperature. Since the station temperature used for this local model is on a scale much too small for global climate models, we simulate, secondly, the temperature with the concept of the Alpine temperature: It is the spatial Taylor expansion of the seasonal European temperature in vertical and horizontal directions. This improved model yields, for the same Austrian and Swiss data, both a better fit and a slightly smaller sensitivity of the snow-temperature curve than the original hyperbolic model. Thirdly we apply our improved model to a considerably larger Alpine data set comprising also data from France, Germany, Italy and Slovenia and find a sensitivity of about , 0.33 ( ± 0.03) per degree warming. It is representative for the entire Alpine region and corresponds to a maximum reduction of the snow cover of 30 days in winter at a height of 700 m for 1° European warming. The implication is that the relation between the natural fluctuations of winter snow duration and European temperature may be an estimate for a trend of snow duration in case of a future European temperature trend. Copyright © 2007 Royal Meteorological Society [source] Naringin, a grapefruit flavanone, protects V79 cells against the bleomycin-induced genotoxicity and decline in survivalJOURNAL OF APPLIED TOXICOLOGY, Issue 2 2007Abhinav Jagetia Abstract The effect of naringin, a grapefruit flavonone was studied on bleomycin-induced genomic damage and alteration in the survival of cultured V79 cells. Exposure of V79 cells to bleomycin induced a concentration dependent elevation in the frequency of binucleate cells bearing micronuclei (MNBNC) and a maximum number of MNBNCs were observed in the cells treated with 50 ,g ml,1 bleomycin, the highest concentration evaluated. This genotoxic effect of bleomycin was reflected in the cell survival, where a concentration dependent decline was observed in the cells treated with different concentrations of bleomycin. Treatment of cells with 1 mm naringin before exposure to different concentrations of bleomycin arrested the bleomycin-induced decline in the cell survival accompanied by a significant reduction in the frequency of micronuclei when compared with bleomycin treatment alone. The cell survival and micronuclei induction were found to be inversely correlated. The repair kinetics of DNA damage induced by bleomycin was evaluated by exposing the cells to 10 ,g ml,1 bleomycin using single cell gel electrophoresis. Treatment of V79 cells with bleomycin resulted in a continuous increase in DNA damage up to 6 h post-bleomycin treatment as evident by migration of more DNA into the tails (% tail DNA) of the comets and a subsequent increase in olive tail moment (OTM), an index of DNA damage. Treatment of V79 cells with 1 mm naringin reduced bleomycin-induced DNA damage and accelerated DNA repair as indicated by a reduction in % tail DNA and OTM with increasing assessment time. A maximum reduction in the DNA damage was observed at 6 h post-bleomycin treatment, where it was 5 times lower than bleomycin alone. Our study, which was conducted on the basis of antioxidant, free radical scavenging and metal chelating properties of naringin demonstrates that naringin reduced the genotoxic effects of bleomycin and consequently increased the cell survival and therefore may act as a chemoprotective agent in clinical situations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Analysis of optimal controls for a mathematical model of tumour anti-angiogenesisOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 1 2008U. Ledzewicz Abstract Anti-angiogenic therapy is a novel treatment approach for cancer that aims at preventing a tumour from developing its own blood supply system that it needs for growth. In this paper we consider a mathematical model where the endogenous stimulation term in the dynamics is taken proportional to the number of endothelial cells. This system is an example from a class of mathematical models for anti-angiogenic treatment that were derived from a biologically validated model by Hahnfeldt, Panigrahy, Folkman and Hlatky. The problem how to schedule a given amount of angiogenic inhibitors to achieve a maximum reduction in the primary cancer volume is considered as an optimal control problem and it is shown that optimal controls are bang-bang of the type 0a0 with 0 denoting a trajectory corresponding to no treatment and a a trajectory with treatment at maximum dose along that all inhibitors are being exhausted. Copyright © 2007 John Wiley & Sons, Ltd. [source] Biocontrol of Meloidogyne incognita on tomato using antagonistic fungi, plant-growth-promoting rhizobacteria and cattle manurePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 9 2009Zaki A Siddiqui Abstract BACKGROUND: Biocontrol achieved by a single biocontrol agent is generally inconsistent under field conditions. The aim of the present study was to increase the competitiveness and efficacy of biocontrol agents by using them together with cattle manure. RESULTS: The effects of antagonistic fungi [Aspergillus niger v. Teigh., Paecilomyces lilacinus (Thom) Samson and Penicillium chrysogenum Thom] and plant-growth-promoting rhizobacteria (PGPR) [Azotobacter chroococcum Beijer., Bacillus subtilis (Ehrenberg) Cohn and Pseudomonas putida (Trev.) Mig.] were assessed with cattle manure on the growth of tomato and on the reproduction of Meloidogyne incognita (Kof. & White) Chitwood. Application of antagonistic fungi and PGPR alone and in combination with cattle manure resulted in a significant increase in the growth of nematode-inoculated plants. The highest increase (79%) in the growth of nematode-inoculated plants was observed when P. putida was used with cattle manure, followed by use of P. lilacinus plus cattle manure. Paecilomyces lilacinus resulted in a high reduction in galling and nematode multiplication, followed by P. putida, B. subtilis, A. niger, A. chroococcum and P. chrysogenum. The combined use of P. lilacinus with cattle manure resulted in a maximum reduction in galling and nematode multiplication. CONCLUSION: Application of P. lilacinus or P. putida with cattle manure was useful to achieve greater biocontrol of M. incognita on tomato. Copyright © 2009 Society of Chemical Industry [source] Effects of post-density gradient swim-up on apoptosis signalling in human spermatozoaANDROLOGIA, Issue 2 2010S. Grunewald Summary The inclusion of apoptotic spermatozoa during assisted reproductive techniques (ART) may be one reason for suboptimal success rates. The aim of our study was to evaluate the potential of routine semen preparation to eliminate spermatozoa with activated apoptosis signalling. Semen samples from 20 infertility patients scheduled for ART procedures were investigated. Following density gradient centrifugation (DGC) and swim-up, aliquots were taken from each sample to analyse motility, Caspase-3 activation (CP3) and integrity of the mitochondrial membrane potential (MMP) using flow cytometry. Aliquots from the neat semen served as controls. Semen samples of patients contained 53.8 ± 17.7% spermatozoa with disrupted MMP and 51.8 ± 14.9% with active CP3. Preparation by DGC and swim-up resulted in improvement of progressive motility (+43.5%) and reduction of spermatozoa with disrupted MMP (,34.3%) and activated CP3 (,25.7%, P < 0.01). Minimal reduction of spermatozoa with disrupted MMP and active CP3 was 6.0% and 0.7%, maximum reduction was 65.5% (disrupted MMP) and 49.3% (CP3). Semen samples of subfertile patients contain high levels of spermatozoa with activated apoptosis signalling. Although there was a reduction in the majority of the samples, profound interindividual differences in the separation effect demand further development of innovative molecular-based separation methods to deplete apoptotic spermatozoa. [source] Zur Druck-Zug-Festigkeit von Stahlbeton und stahlfaserverstärktem StahlbetonBETON- UND STAHLBETONBAU, Issue 8 2009Ekkehard Fehling Prof. Dr.-Ing. Versuche; Bemessungs- und Berechnungsverfahren Abstract Während die Druckfestigkeit des Betons durch gleichzeitig wirkenden Querdruck gegenüber der einaxialen Druckfestigkeit erheblich gesteigert werden kann, führen Querzugbeanspruchung und Rissbildung zu einer Abminderung der Tragfähigkeit. Dies gilt für unbewehrten Beton und Stahlbeton gleichermaßen. In den einschlägigen Regelwerken finden sich hierzu international sehr unterschiedliche Bemessungsansätze, wobei die vorgesehenen Abminderungsbeiwerte für denselben Anwendungsfall um das bis zu Zweifache differieren. Die Frage der Druck-Zug-Festigkeit von Stahlbeton wurde in den vergangenen 40 Jahren von zahlreichen Wissenschaftlern untersucht. Ihre Ergebnisse sind allerdings zum Teil ebenso widersprüchlich wie die aktuelle Normensituation. Basierend auf eigenen experimentellen Untersuchungen sowie einer kritischen Auswertung und Einordnung als richtungweisend angesehener, früherer Versuchsreihen wird ein Vorschlag zur Abminderung der Druckfestigkeit des gerissenen Stahlbetons entwickelt. Erstmals wird dabei auch der Einfluss einer Faserzugabe in Kombination mit Stabstahlbewehrung berücksichtigt. Ein Vergleich mit den in DIN 1045-1, CEB-FIP Model Code 1990, Eurocode 2 und ACI Standard 318-05 angegebenen Bemessungsregeln zeigt, dass allein DIN 1045-1 die in den Versuchen beobachtete maximale Abminderung der Druckfestigkeit durch Querzug und Rissbildung zum Teil erheblich unterschätzt, so dass eine konservative Auslegung der Tragwerke nicht immer sichergestellt ist. Biaxial Compression-Tension-Strength of Reinforced Concrete and Reinforced Steel Fibre Concrete The compressive strength of concrete can be substantially increased in relation to uni-axial compressive strength by transverse compression acting at the same time. In contrast, transverse tension and cracking lead to a reduction of the load-carrying capacity. This holds true for plain concrete as well as for reinforced concrete. In international standards very different calculation rules can be found on this subject, whereby the provided reductions differ up to a factor of two for the same application. The question of biaxial compression-tension-strength of reinforced concrete was examined in the past 40 years by numerous scientists. Their results are, however, partially contradictory in the same way as the current standard situation. Based on own experimental investigations as well as on a critical review and classification of former test series regarded as trend-setting, a proposal for the reduction of the compressive strength of cracked reinforced concrete is developed. For the first time, also the influence of fibres in addition to bar reinforcement is considered thereby. A comparison with the calculation rules in DIN 1045-1, CEB-FIP Model Code 1990, Eurocode 2, and ACI Standard 318-05 shows, that exclusively DIN 1045-1 underestimates sometimes substantially the maximum reduction of the compressive strength by transverse tension and cracking observed in the tests, so that a conservative design of structures cannot always be ensured. [source] Determining the optimal concentration of fluoride in drinking water in PakistanCOMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 3 2004Ayyaz Ali Khan Abstract , Objectives:,This study was designed to determine the optimal concentrations of fluoride for drinking water in Pakistan. Clinical dental examination of 1020 school children aged 12 years was carried out in 19 cities of Pakistan. Correlation between concentrations of water fluoride, caries and fluorosis was investigated by analyzing the data on fluoride concentrations in drinking water in the sampled population for which the caries and the fluorosis levels were also measured. Methods:,The optimal level of fluoride in drinking water is universally calculated by applying the equation of Galagan and Vermillion, which permits the calculation of water intake as a function of temperature. The annual mean maximum temperatures (AMMT) recorded during the last 5 years were collected from the meteorological centres of the 28 divisional headquarter stations. The average AMMT of Pakistan is 29°C at which the optimal fluoride in drinking water of Pakistan was calculated to be 0.7 ppm. As drinking habits differ in various parts of the world, determination of optimal concentration of fluoride for drinking water in Pakistan was performed using a modified Galagan and Vermillion equation, which applies a correction factor of 0.56 to the equation. The optimal fluoride in drinking water in Pakistan using this modified equation was determined to be 0.39 ppm. Results:,Observation of the correlation showed that a fluoride concentration of 0.35 ppm in drinking water was associated with maximum reduction in dental caries and a 10% prevalence of fluorosis. Conclusions:,Determining the most appropriate concentrations of fluoride in drinking water is crucial for communities. It is imperative that each country calculates its own optimal level of fluoride in drinking water based on the dose,response relationship of fluoride in drinking water with the levels of caries and fluorosis. Climatic conditions, dietary habits of the population and other possible fluoride exposures need to be considered in formulating these recommendations. [source] Efficacy of Pulsed UV-Light for the Decontamination of Escherichia coli O157:H7 and Salmonella spp. on Raspberries and StrawberriesJOURNAL OF FOOD SCIENCE, Issue 5 2008K.L. Bialka ABSTRACT:, Small fruits are increasingly being implicated in outbreaks of foodborne illness, and fresh produce is now the 2nd leading cause of foodborne illness in the United States. Conventional methods of decontamination are not effective, and there is a need to evaluate novel technologies. Pulsed ultraviolet (UV)-light is one such technology. In this study, pulsed UV-light was applied to strawberries and raspberries at varying UV doses and times. On raspberries, maximum reductions of Escherichia coli O157:H7 and Salmonella were 3.9 and 3.4 log10 CFU/g at 72 and 59.2 J/cm2, respectively. On the surfaces of strawberries, maximum reductions were 2.1 and 2.8 log10 CFU/g at 25.7 and 34.2 J/cm2, respectively. There was no observable damage to the fruits at these UV doses. The results obtained in this study indicate that pulsed UV-light has the potential to be used as a decontamination method for raspberries and strawberries. [source] | |||||||||||||||||||