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31.
Kernel algorithms for large data-sets are now an active research area motivated by the many real world problems producing very large numbers of data points. However, standard kernel methods scale poorly with the size of the data-set. We propose a mathematically motivated approach to sparse function estimation that utilises the uniform continuity properties of functions in continuous reproducing kernel Hilbert spaces (RKHS) defined on compact domains. Using the uniform continuity properties of the function a similarity measure on data points is defined that allows data to be pre-clustered. Unlike previous methods for sparse function estimation using clustering the proposed approach is supervised and relies on well-defined mathematical concepts. The cluster centres are used to form a sparse RKHS subspace within which the function is estimated. The greedy pre-clustering algorithms and sparse model based on pre-clustering and committee machine techniques are presented. Results are presented to demonstrate the application of the proposed algorithms on function approximation problems. 相似文献
32.
Microsystem Technologies - This paper presents the fabrication and characterization of spin coated multilayer graphene oxide/p-silicon heterojunction solar cell. Liquid graphene oxide is... 相似文献
33.
Ion exchange (IE) has been so far limited to treating waters and wastewaters low in solids (TS) and ammonium (NH4 +). This study provides a new insight into the application of IE for NH4 + removal from wastewaters with high NH4 + and TS, using natural zeolite as adsorbent medium. Assays were carried out in continuously stirred batch reactors to study the effect of initial NH4 +, pH, TS, contact time, and zeolite pore size (0.2–0.5 and 0.6–2.0 mm). Results confirmed the suitability of this zeolite to remove NH4 + from wastewater with high amounts of solids (up to 2%TS) and NH4 + (up to 2500 mgNH4 +-N/L). Ammonium adsorption capacity (q t ) was faster with 0.2–0.5 mm size because of the greater specific surface area and shorter diffusion path than 0.6–2.0 mm zeolite. Both zeolites showed increasing q t with increasing initial NH4 + due to the higher driving force produced by higher concentrations. The process followed a pseudo-second order kinetic and was best described by the Freundlich isotherm. Varying the pH (6–8.5) of the wastewater had no effect on NH4 + removal capacity. In conclusion, this natural zeolite showed high affinity for NH4 + in wastewater with high loads of NH4 + and solids, returning a viable treatment method when other techniques are not applicable. 相似文献
34.
Susmita Bhattarai Sudha Sharma Utsab Subedi Hosne Ara Alika Shum Murov Milena Md. Shenuarin Bhuiyan Srivatsan Kidambi Hong Sun Sumitra Miriyala Manikandan Panchatcharam 《International journal of molecular sciences》2022,23(8)
Endothelial permeability is a major complication that must be addressed during stroke treatment. Study of the mechanisms underlying blood–brain barrier (BBB) disruption and management of the hypoxic stress-induced permeability of the endothelium following reperfusion are both urgently needed for stroke management. Lysophosphatidic acid (LPA), a bioactive lipid essential for basic cellular functions, causes unfavorable outcomes during stroke progression. LPA-producing enzyme autotaxin (ATX) is regulated in ischemic stroke. We used an electrical cell-substrate impedance sensor (ECIS) to measure endothelial permeability. Mitochondrial bioenergetics were obtained using a Seahorse analyzer. AR-2 probe fluorescence assay was used to measure ATX activity. LPA increased endothelial permeability and reduced junctional protein expression in mouse brain microvascular endothelial cells (MBMEC). LPA receptor inhibitors Ki16425 and AM095 attenuated the LPA-induced changes in the endothelial permeability and junctional proteins. LPA significantly diminished mitochondrial function in MBMEC. ATX was upregulated (p < 0.05) in brain microvascular endothelial cells under hypoxic reperfusion. ATX activity and permeability were attenuated with the use of an ATX inhibitor in a mouse stroke model. The upregulation of ATX with hypoxic reperfusion leads to LPA production in brain endothelial cells favoring permeability. Inhibition of the ATX–LPA–LPAR axis could be therapeutically targeted in stroke to achieve better outcomes. 相似文献
35.
Laszlo M Mukherjee S 《IEEE transactions on pattern analysis and machine intelligence》2006,28(4):533-543
The k-means algorithm is widely used for clustering because of its computational efficiency. Given n points in d-dimensional space and the number of desired clusters k, k-means seeks a set of k-cluster centers so as to minimize the sum of the squared Euclidean distance between each point and its nearest cluster center. However, the algorithm is very sensitive to the initial selection of centers and is likely to converge to partitions that are significantly inferior to the global optimum. We present a genetic algorithm (GA) for evolving centers in the k-means algorithm that simultaneously identifies good partitions for a range of values around a specified k. The set of centers is represented using a hyper-quadtree constructed on the data. This representation is exploited in our GA to generate an initial population of good centers and to support a novel crossover operation that selectively passes good subsets of neighboring centers from parents to offspring by swapping subtrees. Experimental results indicate that our GA finds the global optimum for data sets with known optima and finds good solutions for large simulated data sets. 相似文献
36.
Shela Gorinstein Sumitra PoovarodomHanna Leontowicz Maria LeontowiczJacek Namiesnik Suchada VearasilpRatiporn Haruenkit Pramoj RuamsukeElena Katrich Zev Tashma 《Food research international (Ottawa, Ont.)》2011,44(7):2222-2232
The aim of this research was to investigate the bioactivity of durian, snake fruit and mangosteen, rare exotic Thai fruits. These fruits were compared among them and with conventional fruits: durian with mango and avocado, and snake fruit with mangosteen and kiwifruit in order to find the preferable diet for human consumption. The contents of polyphenols, flavonoids, flavanols, tannins, anthocyanins, ascorbic acid and carotenoids, and the level of antioxidant potential by ABTS, DPPH, FRAP and CUPRAC in different extracts (methanol, water, acetone, and hexane) were determined. The presence of polyphenols (flavonoids and phenolic acids) in the investigated samples was characterized by Fourier transform infrared (FT-IR) spectroscopy and three-dimensional fluorimetry (3D-FL).The in vivo studies were carried out on 25 male Wistar rats, divided into 5 diet groups, each of 5. During 30 days of the experiment the rats of all 5 groups were fed basal diet (BD), which included wheat starch, casein, soybean oil, vitamin and mineral mixtures. The rats of the Control group were fed only the BD. The BD of the other 4 groups was supplemented with 1% of nonoxidized cholesterol (NOC) (Chol group), 1% of NOC in each group and 5% of lyophilized fruits: durian (Chol/Durian), snake fruit (Chol/Snake), mangosteen (Chol/Mangosteen). After the experiment diets supplemented with exotic fruits significantly hindered the rise in plasma lipids and hindered the decrease in the plasma antioxidant activity. In conclusion, the contents of bioactive compounds and the antioxidant potential are relatively high in the studied fruits and varied among them depending on the extraction procedure. FT-IR and 3D-FL can be used as additional tools for identification and comparison of bioactive compounds. Supplementation of diets with exotic fruits positively affects plasma lipid profile and antioxidant activity in rats fed cholesterol-containing diets. 相似文献
37.
Ratiporn Haruenkit Sumitra Poovarodom Suchada Vearasilp Jacek Namiesnik Magda Sliwka-Kaszynska Yong-Seo Park Buk-Gu Heo Ja-Yong Cho Hong Gi Jang Shela Gorinstein 《Food chemistry》2010
The aim of this investigation was to compare the bioactive and nutrient compounds, fatty acids, and antioxidant and antiproliferative activities of Mon Thong durian at different stages of ripening. It was found that the total polyphenols, flavonoids, flavanols, ascorbic acid, tannins and the antioxidant activity determined by four assays (CUPRAC, DPPH, ABTS and FRAP) differed in immature, mature, ripe and overripe samples. The content of polyphenols and antioxidant activity were the highest in overripe durian, flavonoids were the highest in ripe durian, and flavanols and antiproliferative activity were the highest in mature durian (p < 0.05). FTIR spectra of polyphenols, HPLC profiles of fatty acids, the antioxidant and antiproliferative activities can be used as indicators to characterise different stages of durian ripening. 相似文献
38.
In the present study, the seeds and fruit rind of six plants of the Fabaceae family were selected to evaluate their potential as antioxidant and antibacterial agents. The dried powders were individually extracted with various organic solvents by the cold percolation method, were evaluated for antibacterial activity and methanol extracts used for antioxidant activities. Total phenol, protein and sugar contents were also measured. Antioxidant activities were measured by DPPH free radical scavenging activity, superoxide anion radical scavenging activity and reducing capacity assessment. Antibacterial activity was measured by the agar well diffusion method against four Gram positive and four Gram negative bacteria. The methanol extract of the fruit rind of C. indica showed the maximum DPPH free radical scavenging activity, superoxide anion radical scavenging activity, a high reducing capacity assessment and also had the highest total phenol content. There was a direct correlation between the phenol content and the antioxidant activity. The antibacterial activity of all the extracts was more pronounced on Gram positive bacteria than on Gram negative bacteria. Thus, the fruit rind of C. indica showed the best antioxidant and antibacterial activities. 相似文献
39.
The aim of the present study was to find out the best method for extracting antioxidants from Syzygium cumini L. leaves. The extraction was done by three different methods: sequential cold percolation extraction method, decoction extraction
method, and maceration extraction method. Antioxidant activity, total phenol, and flavonoid content were determined in all
different extracts of various extraction methods of S. cumini L. leaves. Antioxidant activity was tested by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical, superoxide anion radical
and hydroxyl radical scavenging activities, and reducing capacity assessment. Sequential cold percolation extraction method
proved to be the best extraction method. The acetone extract had maximum phenol and flavonoid content and showed best DPPH
free radical scavenging activity and reducing capacity assessment. Ethyl acetate extract showed best superoxide radical scavenging
activity, while aqueous extract showed best hydroxyl radical scavenging activity. It can be concluded that sequential cold
percolation extraction method is the best method of extracting leaf antioxidants for this plant at least. 相似文献