Numerical inversion of multidimensional Laplace transforms by the Laguerre method

Numerical transform inversion can be useful to solve stochastic models arising in the performance evaluation of telecommunications and computer systems. We contribute to this technique in this paper by extending our recently developed variant of the Laguerre method for numerically inverting Laplace transforms to multidimensional Laplace transforms. An important application of multidimensional inversion is to calculate time-dependent performance measures of stochastic systems. Key features of our new algorithm are: (1) an efficient FFT-based extension of our previously developed variant of the Fourierseries method to calculate the coefficients of the multidimensional Laguerre generating function, and (2) systematic methods for scaling to accelerate convergence of infinite series, using Wynn's ε-algorithm and exploiting geometric decay rates of Laguerre coefficients. These features greatly speed up the algorithm while controlling errors. We illustrate the effectiveness of our algorithm through numerical examples. For many problems, hundreds of function evaluations can be computed in just a few seconds.     

Electric and dielectric study of cobalt substituted MgMn nanoferrites synthesized by solution combustion technique

Cobalt substituted Mg–Mn nanoferrites with formulae Mg_0.9Mn_0.1Co_xFe_2?xO₄, x=0.0, 0.1, 0.2 and 0.3, have been synthesized for the first time by the solution combustion technique. The effects of Co²⁺ ions on the dc resistivity, dielectric constant and dielectric loss tangent of Mg–Mn nanoferrites at room temperature are presented in this paper. X-ray diffraction confirmed the formation of a single phase spinel structure. Particle size was found to increase, 20.9–23.9 nm, with increasing Co²⁺ concentration. The dc resistivity was increased by two order of magnitude with substitution of Co²⁺ ions while the dielectric constant was found to be decreasing with the increasing concentration of cobalt ions. The value of dc resistivity obtained for Mg_0.9Mn_0.1Fe₂O₄ nanoferrite in our work is greater than the value obtained for the same composition prepared by the conventional ceramic technique. Further, the dielectric constant and dielectric loss tangent were observed to be decreasing with the increase in frequency.     

The role of particle size distribution of suspended solids in defining the flow properties of milk chocolate

The flow characteristics of molten milk chocolate, like most dense suspensions, are a function of the maximum packing fraction ((_m) of the suspended solids. Milk chocolates were prepared from mixtures of two relatively narrow coarse (d_4,3 = 17 μm) and fine (d₄,₃ = 8.5 μm) size distributions of non‐fat solids to contain 0, 25, 50, 75, and 100% of the coarse component. Solids bed density (a measure of maximum packing fraction) correlated with the apparent viscosity of milk chocolates (r = ‐0.98). The highest value for solids bed density and lowest value for apparent viscosity were measured for size distributions with 75% of solids from the coarse fraction. Casson yield value correlated with d_4,3 (r = ‐0.98) and specific surface area (r = 0.93). The maximum packing fraction of binary mixtures of two distinct sizes of non‐fat chocolate solids attained a maximum value for a specific volume ratio of the components. The maximum in _m corresponded with the minimum viscosity in molten chocolate at a given solids volume concentration.     

A middleware‐transparent approach to developing distributed applications

An innovative middleware‐transparent approach to developing distributed applications is presented. The approach uses an aspect‐oriented software development technique to separate an application's middleware‐independent functionality from its middleware‐specific functionality. Application elements that are specific to the middleware are localized in aspects that can be seamlessly integrated into middleware‐independent application designs. The middleware‐transparent approach is used to decouple business functionality from middleware‐specific functionality. The decoupling allows developers to change middleware application elements without significantly modifying business functionality. Middleware technologies such as Java Remote Method Invocation (RMI), Jini, Simple Object Access Protocol (SOAP) remote procedure call (RPC) and .Net are used as examples to illustrate the approach. Copyright © 2005 John Wiley & Sons, Ltd.     

Conditioning of ictal and interictal behaviors in rats by amygdala kindling: Context as the conditional stimulus.

The authors showed that conditional effects of the stimulation environment modulate both the ictal and interictal behaviors of rats subjected to amygdala kindling. Rats received 53 stimulations to the left basolateral amygdala in 1 conditional stimulus (CS) context (CS+) and 53 sham stimulations (the stimulation lead was attached but no current was delivered) in another context (CS-), quasirandomly over 54 days. Three kinds of conditional effects were observed, First, after several stimulations, less ambulatory activity, more freezing, and less rearing reliably occurred in the CS + context than in the CS context. Second, after 45 stimulations, all of the rats chose the CS - context over the CS + context in a conditioned place preference test. Third, when the rats were finally stimulated in the CS- context, their motor seizures were less severe: Latencies were longer, motor seizures were shorter, convulsive patterns were of a lower class, and there were fewer falls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterisation and functional properties of proteins of some Indian chickpea (Cicer arietinum) cultivars

BACKGROUND: Chickpea (Cicer arietinum L.) proteins have received attention during recent years owing to their higher biological values and better functional ingredients than oilseed proteins. In this study the composition, fractionation, electrophoretic behaviour and functional properties of five chickpea protein concentrates were determined. RESULTS: The chickpea proteins contained 15.9–54.8 g kg^?1 albumin, 48.9–154.1 g kg^?1 globulin, 39.2–76.5 g kg^?1 glutelin and traces of prolamin. Electrophoresis of the various fractions revealed that albumin and globulin were made up of sub‐units of different molecular weights ranging from 7 to 96 kDa. Water and oil absorption of the protein concentrates varied from 1.15 to 2.75 g g^?1 and from 2.60 to 5.65 g g^?1 respectively. Foaming capacity and foam stability of the protein concentrates were good and improved with the addition of salt (10 g L^?1 NaCl) or sugar (100 g L^?1 sucrose) at both isoelectric and neutral pH. Emulsifying capacity and emulsion stability of the protein concentrates were good and excellent respectively. CONCLUSION: Protein concentrates prepared from chickpeas have potential use in food formulations owing to their good emulsifying/foaming and water/oil‐binding capacities. Copyright © 2008 Society of Chemical Industry     

Investigations Towards the Chemoselective Thioacetaliztion of Carbonyl Compounds by Using Ionic Liquid [bmim]Br as a Recyclable Catalytic Medium

The ionic liquid based on the 1‐n‐butyl‐3‐methylimidazolium cation has been prepared and used as an efficient catalytic medum for the chemoselective thioacetalization of carbonyl compounds. Furthermore, recycling and reuse of this ionic liquid medium has been demonstrated. Moreover, the use of this catalytic medium not only avoids the generation of waste but also provides a green process with minimal hazards.     

Stratified sampling for data mining on the deep web

In recent years, the deep web has become extremely popular. Like any other data source, data mining on the deep web can produce important insights or summaries of results. However, data mining on the deep web is challenging because the databases cannot be accessed directly, and therefore, data mining must be performed by sampling the datasets. The samples, in turn, can only be obtained by querying deep web databases with specific inputs. In this paper, we target two related data mining problems, association mining and differential rulemining. These are proposed to extract high-level summaries of the differences in data provided by different deep web data sources in the same domain. We develop stratified sampling methods to perform these mining tasks on a deep web source. Our contributions include a novel greedy stratification approach, which recursively processes the query space of a deep web data source, and considers both the estimation error and the sampling costs. We have also developed an optimized sample allocation method that integrates estimation error and sampling costs. Our experimental results show that our algorithms effectively and consistently reduce sampling costs, compared with a stratified sampling method that only considers estimation error. In addition, compared with simple random sampling, our algorithm has higher sampling accuracy and lower sampling costs.     

Effect of Gd doping on magnetic, electric and dielectric properties of MgGdxFe2−xO4 ferrites processed by solid state reaction technique

MgGd_xFe_2−xO₄ (x = 0.0, 0.05, 0.1 and 0.15) ferrites, with improved dc resistivity, initial permeability, saturation magnetization, and extremely low relative loss factor, have been synthesized by solid state reaction technique. The microstructures, electric, dielectric and magnetic properties have been investigated by means of X-ray diffraction, Keithley 2611 system, impedance analyzer and VSM respectively. The addition of Gadolinium in Mg ferrite has been shown to play a crucial role in enhancing the electric, dielectric and magnetic properties. The dc resistivity is increased by two orders of magnitude as compared to Mg ferrite. Saturation magnetization has been increased by two times and remnant magnetization has been increased by more than three times due to the doping of Gd³⁺ ions in Mg ferrite. The relative loss factor was found to have very low values and is of the order of 10⁻⁴-10⁻⁵ in the frequency range 0.1-30 MHz. The variations of electric, dielectric and magnetic properties of the samples have been studied as a function of frequency and Gd³⁺ ions concentration measured at room temperature. High resistivity and improved magnetic properties can be correlated with better compositional stoichiometry and the replacement of Fe³⁺ ions by Gd³⁺ ions. The mechanisms responsible to these results have been discussed in this paper.