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Reduction Methods (reduction + methods)
Selected AbstractsData partitioning-based parallel irregular reductionsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 2-3 2004Eladio Gutiérrez Abstract Different parallelization methods for irregular reductions on shared memory multiprocessors have been proposed in the literature in recent years. We have classified all these methods and analyzed them in terms of a set of properties: data locality, memory overhead, exploited parallelism, and workload balancing. In this paper we propose several techniques to increase the amount of exploited parallelism and to introduce load balancing into an important class of these methods. Regarding parallelism, the proposed solution is based on the partial expansion of the reduction array. Load balancing is discussed in terms of two techniques. The first technique is a generic one, as it deals with any kind of load imbalance present in the problem domain. The second technique handles a special case of load imbalance which occurs whenever a large number of write operations are concentrated on small regions of the reduction arrays. Efficient implementations of the proposed optimizing solutions for a particular method are presented, experimentally tested on static and dynamic kernel codes, and compared with other parallel reduction methods. Copyright © 2004 John Wiley & Sons, Ltd. [source] Novel strategies targeting pathogen transmission reduction in insect vectors: Tsetse-transmitted trypanosomiasis controlENTOMOLOGICAL RESEARCH, Issue 4 2007Brian L. WEISS Abstract Insect vectors are essential for the transmission of important human diseases such as malaria, leishmaniasis, Chagas and sleeping sickness. Insects are also responsible for the transmission of agricultural diseases that affect livestock and crops. Traditionally, control of the vector populations has been an effective disease management strategy. Recently, vector control strategies have been fortified by research in insect biology and in insect,pathogen interactions as well as by the development of transgenic technologies. In addition to insect population reduction methods, disease control via selective elimination of pathogens in insects can now be explored. Here we explore the tsetse vectors of African trypanosomes and describe the application of recent knowledge gained in their symbiotic, reproductive and vectorial biology to develop novel disease control strategies. [source] Reducing seabird bycatch in longline, trawl and gillnet fisheriesFISH AND FISHERIES, Issue 1 2007Leigh S. Bull Abstract With an increasing number of seabird species, particularly albatross and petrels, becoming threatened, a reduction of fishery impacts on these species is essential for their future survival. Here, mitigation methods to reduce and avoid seabird bycatch are assessed in terms of their ability to reduce bycatch rates and their economic viability for longline, trawl and gillnet fisheries worldwide. Factors influencing the appropriateness and effectiveness of a mitigation device include the fishery, vessel, location, seabird assemblage present and season of year. As yet, there is no single magic solution to reduce or eliminate seabird bycatch across all fisheries: a combination of measures is required, and even within a fishery there is likely to be refinement of techniques by individual vessels in order to maximize their effectiveness at reducing seabird bycatch. In longline demersal and pelagic fisheries, a minimum requirement of line weighting that achieves hook sink rates minimizing seabird bycatch rates should be tailored with a combination of strategic offal and discard management, bird-scaring lines (BSLs) and night-setting, particulary in Southern Hemisphere fisheries. Urgent investigation is needed into more effective measures at reducing seabird interactions with trawl nets and gill nets. In trawl fisheries, a combination of offal and discard management, the banning of net monitoring cables, paired BSLs, and a reduction in the time the net is on or near the surface are likely to be the most effective in reducing seabird interactions with the warp cables and net. Few seabird bycatch reduction methods have been developed for gillnet fisheries, although increasing the visibility of the net has been shown to reduce seabird bycatch. Further studies are required to determine the efficacy of this technique and its influence on target species catch rates. [source] Principles and approaches to abate seabird by-catch in longline fisheriesFISH AND FISHERIES, Issue 1 2005Eric Gilman Abstract Mortality in longline fisheries is a critical global threat to most albatross and large petrel species. Here we identify key principles and approaches to identify and achieve broad use of effective seabird by-catch avoidance methods. Despite the availability of highly effective and cost-saving seabird avoidance methods, few longline fleets employ them. Given the political context and capacity of management authorities of the majority of longline fisheries, it is critical to identify seabird avoidance strategies that are not only highly effective, but are also economically viable and commercially practical. Adoption of an international performance standard for longline baited hook,sink rate, and prescribing minimum gear weighting designs that meet this standard that are achievable by all longline fisheries, would be an important step forward towards resolving low use of seabird avoidance methods by vessels, including those in illegal, unregulated and unreported fisheries. Due to differences between fleets, no single seabird avoidance measure is likely to be effective and practical in all longline fisheries. Therefore, testing of seabird avoidance methods in individual fleets is needed to determine efficacy and economic viability. Longline fishers should directly participate in these trials as they have a large repository of knowledge and skills to effectively develop and improve seabird by-catch avoidance techniques, and this provides industry with a sense of ownership for uptake of effective by-catch reduction methods. Establishing protected areas containing seabird colonies and adjacent waters within a nation's EEZ can be an expedient method to address seabird by-catch. However, establishing high seas marine protected areas to restrict longline fishing in seabird foraging areas, which would require extensive and dynamic boundaries and large buffer zones, may not be a viable short-term solution because of the extensive time anticipated to resolve legal complications with international treaties, to achieve international consensus and political will, and to acquire requisite extensive resources for surveillance and enforcement. Analysis of results of research on seabird avoidance methods reveals that the most reliable comparisons of the efficacy of alternative strategies are from comparing the effectiveness of methods tested in a single experiment. Benefits from standardizing the reporting of seabird by-catch rates to account for seabird abundance are described. To provide the most precise inputs for seabird population models, estimates of seabird mortality in longline fisheries should account for seabird falloff from hooks before hauling, delayed mortality of seabirds caught but freed from gear, and mortality caused by hooks discarded in offal. [source] Toward a reduction of the bimolecular reaction model for titan's ionosphereINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 11 2008Nathalie Carrasco The aim of this paper is to highlight the skeletal chemistry responsible for the rich ionospheric chemistry observed in Titan's atmosphere. The present database is represented by about 700 ion,molecule reactions, which are not all important to describe the system. Our criterion to reduce the list of reactions is to reproduce a reference mass spectrum within its uncertainties. This reference mass spectrum is obtained with the complete reaction database and with neutral densities optimized for the INMS mass spectrum measured at 1200 km during the T5 flyby. We compared two mechanism reduction methods, brute force screening and global sensitivity analysis. The analysis of the residual scheme with only 35 bimolecular reactions highlights several patterns, concerning in particular ionic growth processes and introduction of nitrogen to the ionic species. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 699,709, 2008 [source] An Environmentally Benign, Highly Efficient Catalytic Reduction of p -Nitrophenol using a Nano-Sized Nickel Catalyst Supported on Silica-AluminaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Islam Hamdy Abd El Maksod Abstract A green and effective method is reported for the reduction of p -nitrophenol to p -aminophenol using a nano-sized nickel catalyst supported on silica-alumina in the presence of hydrazine hydrate as an alternative source of hydrogen. It was found that nickel loaded on a silica-alumina support is a very effective catalyst in the hydrogenation of p -nitrophenol to p -aminophenol. Thus it attained 100% conversion in only 69 seconds instead of 260 seconds for commercial Raney nickel. In addition, the possibility to reuse it more than one time with great efficiency gives it another advantage over commercial Rainey nickel which cannot be used more than once. This economical and environmentally friendly method provides a potentially new approach for the synthesis of the intermediate product of paracetamol in industry, which overcomes the drawbacks of the known reduction methods. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and electron spin resonance (ESR) tehniques. [source] Hyperspectral imaging combined with principal component analysis for bruise damage detection on white mushrooms (Agaricus bisporus)JOURNAL OF CHEMOMETRICS, Issue 3-4 2008A. A. Gowen Abstract Hyperspectral imaging (HSI) combines conventional imaging and spectroscopy to simultaneously acquire both spatial and spectral information from an object. This technology has recently emerged as a powerful process analytical tool for rapid, non-contact and non-destructive food analysis. In this study, the potential application of HSI for damage detection on the caps of white mushrooms (Agaricus bisporus) was investigated. Mushrooms were damaged by controlled vibration to simulate damage caused by transportation. Hyperspectral images were obtained using a pushbroom line-scanning HSI instrument, operating in the wavelength range of 400,1000,nm with spectroscopic resolution of 5,nm. The effective resolution of the CCD detector was 580,×,580,pixels by 12 bits. Two data reduction methods were investigated: in the first, principal component analysis (PCA) was applied to the hypercube of each sample, and the second PC (PC 2) scores image was used for identification of bruise-damaged regions on the mushroom surface; in the second method PCA was applied to a dataset comprising of average spectra from regions normal and bruise-damaged tissue. In this case it was observed that normal and bruised tissue were separable along the resultant first principal component (PC 1) axis. Multiplying the PC 1 eigenvector by the hypercube data allowed reduction of the hypercube to a 2-D image, which showed maximal contrast between normal and bruise-damaged tissue. The second method performed better than the first when applied to a set of independent mushroom samples. The results from this study could be used for the development of a non-destructive monitoring system for rapid detection of damaged mushrooms on the processing line. Copyright © 2008 John Wiley & Sons, Ltd. [source] Benefits of sonographic-guided hydrostatic reduction opposed to air reduction in a case of intussusception due to lymphomaJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 2 2004Robyn L Grant Summary A case of intussusception due to a pathological lead point in a child is presented. Such cases are uncommon in the paediatric age-group. The pathological lead point was missed at air enema reduction but it was clearly defined on sonographic-guided hydrostatic reduction. The advantages and disadvantages of these reduction methods are discussed. [source] Fabrication of Silver Nanoparticles in Hydrogel Networks,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2006Y. Murali Mohan Abstract Summary: This paper describes a simple and facile approach to fabricate well dispersed silver nanoparticles (AgNPs) in poly[N -isopropylacrylamide- co -(sodium acrylate)] hydrogels. The silver nanoparticles formed are spherical in shape with a narrow size distribution in the hydrogel networks in which the nanoparticles are stabilized by the polymer network. Uniformly dispersed silver nanoparticles were obtained with poly[N -isopropylacrylamide- co -[sodium acrylate)] hydrogels, whereas a poly(N -isopropylacrylamide)/poly(sodium acrylate) IPN gel showed aggregated nanoparticles. It is demonstrated that the hydrogel network structure determines the size and shape of the nanoparticles. These particles are more stable in the gel networks compared to other reduction methods. The hydrogel/silver nanohybrids were well characterized by XRD, UV-vis spectrometry, scanning electron microscopy and transmission electron microscopy. Schematic representation of the preparation of Ag nanoparticles in hydrogel networks. [source] Reduction of errors in ASL cerebral perfusion and arterial transit time maps using image de-noisingMAGNETIC RESONANCE IN MEDICINE, Issue 3 2010Jack A. Wells Abstract In this work, the performance of image de-noising techniques for reducing errors in arterial spin labeling cerebral blood flow and arterial transit time estimates is investigated. Simulations were used to show that the established arterial spin labeling cerebral blood flow quantification method exhibits the bias behavior common to nonlinear model estimates, and as a result, the reduction of random errors using image de-noising can improve accuracy. To assess the effect on precision, multiple arterial spin labeling data sets acquired from the rat brain were processed using a variety of common de-noising methods (Wiener filter, anisotropic diffusion filter, gaussian filter, wavelet decomposition, and independent component analyses). The various de-noising schemes were also applied to human arterial spin labeling data to assess the possible extent of structure degradation due to excessive spatial smoothing. The animal experiments and simulated data show that noise reduction methods can suppress both random and systematic errors, improving both the precision and accuracy of cerebral blood flow measurements and the precision of transit time maps. A number of these methods (and particularly independent component analysis) were shown to achieve this aim without compromising image contrast. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] Delta Scuti Network observations of XX Pyx: detection of 22 pulsation modes and of short-term amplitude and frequency variationsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2000G. Handler We report multisite observations devoted to the main-sequence , Scuti star XX Pyx, conducted as the 17th run of the Delta Scuti Network. Over 125 nights a total of 550 h of usable time-series photometric B - and V -filter data were acquired involving both photoelectric and CCD measurements at eight observatories spread around the world, which represents the most extensive single time-series for any pulsating star other than the Sun obtained so far. We describe our observations and reduction methods, and present the frequency analysis of our new data. First, we detect six new pulsation and five new combination frequencies in the star's light curves. We also discover evidence for amplitude and/or frequency variations of some of the modes during the observations. These can occur on time-scales as short as 20 d and show quite diverse behaviour. To take them into account in the frequency analysis, a so-called non-linear frequency analysis method was developed, allowing us to quantify the temporal variability of the modes and to compensate for it. Following that we continue the frequency search and we also incorporate published multisite observations. In this way, we reveal three more pulsation and two more combination frequencies. In the end, we report a total of 30 significant frequencies , 22 of which correspond to independent pulsation modes. This is the largest number of independent modes ever detected in the light curves of a , Scuti star. The frequencies of the modes show preferred separations as already suggested by previous work on this star; they are also arranged in clear patterns. These results lead to a refinement of the stellar mean density and to a new constraint on the rotation rate of XX Pyx (,rot=1.1±0.3 d,1). However, our attempts to identify the modes by pattern recognition failed. Moreover, mode identification from multicolour photometry failed as well because the high pulsation frequencies make this method unfavourable. The diverse behaviour of the amplitude and frequency variations of some of the modes leaves resonances as the only presently known possibility for their explanation. [source] Model reduction of interconnected linear systemsOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 3 2009H. Sandberg Abstract The problem of model reduction of linear systems with certain interconnection structure is considered in this paper. To preserve the interconnection structure between subsystems in the reduction, special care needs to be taken. This problem is important and timely because of the recent focus on complex networked systems in control engineering. Two different model reduction methods are introduced and compared in this paper. Both methods are extensions to the well-known balanced truncation method. Compared with earlier work in the area these methods use a more general linear fractional transformation framework, and utilize linear matrix inequalities. Furthermore, new approximation error bounds that reduce to classical bounds in special cases are derived. The so-called structured Hankel singular values are used in the methods, and indicate how important states in the subsystems are with respect to a chosen input,output map for the entire interconnected system. It is shown how these structured Hankel singular values can be used to select an approximation order. Finally, the two methods are applied to a model of a mechanical device. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nonlinear Model Order Reduction in Nanoelectronics: Combination of POD and TPWLPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2008T. Bechtold In this paper we demonstrate model order reduction of a nonlinear academic model of an inverter chain. Two reduction methods, which are suitable for nonlinear differential algebraic equation systems are combined, the trajectory piecewise linear approach and the proper orthogonal decomposition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Profiling MS proteomics data using smoothed non-linear energy operator and Bayesian additive regression treesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 17 2009Shan He Abstract This paper proposes a novel profiling method for SELDI-TOF and MALDI-TOF MS data that integrates a novel peak detection method based on modified smoothed non-linear energy operator, correlation-based peak selection and Bayesian additive regression trees. The peak detection and classification performance of the proposed approach is validated on two publicly available MS data sets, namely MALDI-TOF simulation data and high-resolution SELDI-TOF ovarian cancer data. The results compared favorably with three state-of-the-art peak detection algorithms and four machine-learning algorithms. For the high-resolution ovarian cancer data set, seven biomarkers (m/z windows) were found by our method, which achieved 97.30 and 99.10% accuracy at 25th and 75th percentiles, respectively, from 50 independent cross-validation samples, which is significantly better than other profiling and dimensional reduction methods. The results show that the method is capable of finding parsimonious sets of biologically meaningful biomarkers with better accuracy than existing methods. Supporting Information material and MATLAB/R scripts to implement the methods described in the article are available at: http://www.cs.bham.ac.uk/szh/SourceCode-for-Proteomics.zip [source] MINIMALLY INVASIVE APPROACH IN THE MANAGEMENT OF CHILDHOOD INTUSSUSCEPTIONANZ JOURNAL OF SURGERY, Issue 9 2007Sing T. Cheung Background: Intussusception is one of the most common causes of intestinal obstruction in infancy. Non-operative reduction using air enema or other hydrostatic reduction methods has been the standard treatment in most cases. However, if the non-operative method is not indicated or fails, open surgery is still necessary. With the tremendous development of the minimally invasive approach in handling surgical conditions in children in the last decade, this has been applied recently for the reduction of intussusception in children. We herein reviewed our experience of using the combined approach, namely, pneumatic reduction and, if failed, laparoscopic reduction in the management of childhood intussusception. Methods: We carried out a retrospective analysis of all children with intussusception managed at Prince of Wales Hospital between December 1998 and December 2004. The minimally invasive approach was used as far as possible. The method of reduction, success rate and the incidence of complication were analysed. Results: Over a 6-year period, there were 146 patients with 167 episodes of intussusception. Pneumatic reduction was carried out in 160 occasions and was successful in 134 (83.8%). In 33 patients, operative reduction was required. Of these, laparoscopic reduction was attempted in 15 and was successful in 13 (86.7%). In those with either pneumatic or laparoscopic reduction, no procedure-related complication was encountered and they had a significant shorter hospital stay (median 3.0 day) than those requiring laparotomy (median 8.0 day) (t -test, P < 0.0001). Conclusion: The minimally invasive approach, that is, pneumatic and/or laparoscopic reduction, was successful in reducing intussusception in 88% of patients with minimal morbidity and shorter hospital stay. [source] Stochastic Model Reduction by Maximizing IndependenceASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3-4 2005Hui Zhang By analysing information descriptions in state space models of linear stochastic systems, this paper proposes two model reduction methods via principles of maximizing independence and conditional independence among the reduced state vector, respectively. These methods are based on state aggregation. The independence and conditional independence are measured by the Kullback-Leibler information distance. It is demonstrated that the maximum conditional independence method is not only applicable to stable systems, but also applicable to unstable systems. Simulation results illustrate the efficiency of the present methods. [source] | ||||||||||||||||