Formulas for incremental or parallel computation of second order central moments have long been known, and recent extensions of these formulas to univariate and multivariate moments of arbitrary order have been developed. Such formulas are of key importance in scenarios where incremental results are required and in parallel and distributed systems where communication costs are high. We survey these recent results, and improve them with arbitrary-order, numerically stable one-pass formulas which we further extend with weighted and compound variants. We also develop a generalized correction factor for standard two-pass algorithms that enables the maintenance of accuracy over nearly the full representable range of the input, avoiding the need for extended-precision arithmetic. We then empirically examine algorithm correctness for pairwise update formulas up to order four as well as condition number and relative error bounds for eight different central moment formulas, each up to degree six, to address the trade-offs between numerical accuracy and speed of the various algorithms. Finally, we demonstrate the use of the most elaborate among the above mentioned formulas, with the utilization of the compound moments for a practical large-scale scientific application. 相似文献
A comprehensive model has been proposed to account for the large enhancement of thermal conductivity in nanofluids and its strong temperature dependence, which the classical Maxwellian theory has been unable to explain. The dependence of thermal conductivity on particle size, concentration, and temperature has been taken care of simultaneously in our treatment. While the geometrical effect of an increase in surface area with a decrease in particle size, rationalized using a stationary particle model, accounts for the conductivity enhancement, a moving particle model developed from the Stokes-Einstein formula explains the temperature effect. Predictions from the combined model agree with the experimentally observed values of conductivity enhancement of nanofluids. 相似文献
The current study was undertaken to investigate the antibacterial (against molecular characterized E. coli isolated from poultry faeces) potential of biosynthesized zinc oxide nanoparticles (ZnO-NPs) from Passiflora subpeltata Ortega aqueous leaf extract. The biosynthesized nanoparticles were subjected to physico-chemical characterization to study shape, size and purity by UV–Vis spectroscopy, X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscopy (TEM). The molecular identification of isolated E. coli from faeces samples was carried out by using 16–23s rRNA primers. The results of the physico-chemical characterization revealed that the biosynthesized nanoparticles were of 93.7% purity with an average size between 45 and 50 nm. The ZnO-NPs offered significant inhibition against the isolated Gram-negative E. coli with MIC at 62.5 µg mL?1 concentration. The antibacterial potential of ZnO NPs against E. coli has also been investigated by the cell viability test, and further the effects of ZnO NPs on bacterial morphological structures was analysed by SEM and TEM.
Anthracnose is a major disease in Florida hybrid bunch grapes, caused by a fungus viz. Elsinoe ampelina. Florida hybrid bunch grapes are grown in southeastern USA for their superior wine characteristics. However, the effect of
anthracnose on grape productivity and wine quality is a major concern to grape growers. Our research is aimed at determining
biochemical basis of anthracnose tolerance in Florida hybrid bunch grape. Leaf samples were collected from the plants infected
with E. ampelina at different periods and analyzed for differential protein expression using high throughput two-dimensional gel electrophoresis.
Among the 32 differentially expressed leaf proteins, two were uniquely expressed in tolerant genotypes in response to E. ampelina infection. These proteins were identified as mitochondrial adenosine triphosphate synthase and glutamine synthetase, which
are known to play a major role in carbohydrate metabolism and defense. Several proteins including ribulose 1-5 bisphosphate-carboxylase
involved in photosynthesis were found to be suppressed in susceptible genotypes compared to tolerant genotypes following E. ampelina infection. The results indicate that the anthracnose-tolerant genotypes have the ability to up-regulate and induce new proteins
upon infection to defend the invasion of the pathogen as well as maintain the normal regulatory processes. 相似文献
Research on Chemical Intermediates - A new series of benzothiazole amide derivatives (9a–l) were synthesized and characterized by Fourier-transform infrared (FT-IR), mass, and 1H and 13C... 相似文献
A simple, inexpensive and efficient oxidation of 2-aryl-1,2,3,4-tetrahydro-4-quinolones has been carried out by employing FeCl3·6H2O-methanol under mild conditions. This method has been investigated for the synthesis of an endothelin receptor antagonist, benzofuro[3,2-b]pyridine core structure. 相似文献
As a new family member of the emerging two‐dimensional (2D) monoelemental materials (Xenes), germanene has shown promising advantages over the prototypical 2D Xenes, such as black phosphorus (BP) and graphene. However, efficient manufacture of novel germanene nanostructures is still a challenge. Herein, a simple top‐down approach for the liquid‐exfoliation of ultra‐small germanene quantum dots (GeQDs) is presented. The prepared GeQDs possess an average lateral size of about 4.5 nm and thickness of about 2.2 nm. The functionalized GeQDs were demonstrated to be robust photothermal agents (PTAs) with outstanding photothermal conversion efficacy (higher than those of graphene and BPQDs), superior stability, and excellent biocompatibility. As a proof‐of‐principle, 2D GeQDs‐based PTAs were used in fluorescence/photoacoustic/photothermal‐imaging‐guided hyperpyrexia ablation of tumors. This work could expand the application of 2D germanene to the field of photonic cancer nanomedicine. 相似文献
Experimental visualizations of the three dimensional (3D) convection patterns generated near an evaporating meniscus in horizontally
oriented capillary tubes are presented. These patterns are caused due to the differential evaporation along the meniscus.
In this study, transparent capillary tubes with refractive index close to that of the evaporating liquid were used to minimize
refraction effects and obtain velocity vectors near the walls. Polystyrene fluorescent particles of 0.5 μm diameter suspended
in methanol were used to make the measurements in tubes of 75, 200 and 400 μm diameter. For the 75 μm tube, gravity was observed
to have no effect on the flow patterns and an axisymmetric counter-rotating vortex pair was present along the horizontal and
vertical center planes, suggesting the presence of a toroidal vortex near the meniscus. With an increase in tube size, buoyancy
effects became apparent as the axisymmetric pattern broke down. A counter-rotating symmetric vortex pair was observed in the
horizontal center plane, whereas in the vertical center plane, a single vortex dominated the flow and pushed the secondary
vortex to a corner. Particle streak and μPIV images were obtained in multiple horizontal planes and a vertical center plane
to understand this 3D flow behavior. 相似文献