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.     

Iodine potassium iodide improves the contrast‐to‐noise ratio of micro‐computed tomography images of the human middle ear

High‐resolution imaging of middle‐ear geometry is necessary for finite‐element modeling. Although micro‐computed tomography (microCT) is widely used because of its ability to image bony structures of the middle ear, it is difficult to visualize soft tissues – including the tympanic membrane and the suspensory ligaments/tendons – because of lack of contrast. The objective of this research is to quantitatively evaluate the efficacy of iodine potassium iodide (IKI) solution as a contrast agent. Six human temporal bones were used in this experiment, which were obtained in right‐left pairs, from three cadaveric heads. All bones were fixed using formaldehyde. Three bones (one from each pair) were stained in IKI solution for 2 days, whereas the other three were not stained. Samples were scanned using a microCT system at a resolution of 20 μm. Eight soft tissues in the middle ear were segmented: anterior mallear ligament, incudomallear joint, lateral mallear ligament, posterior incudal ligament, stapedial annular ligament, stapedius muscle, tympanic membrane and tensor tympani muscle. Contrast‐to‐noise ratios (CNRs) of each soft tissue were calculated for each temporal bone. Combined CNRs of the soft tissues in unstained samples were 6.1 ± 3.0, whereas they were 8.1 ± 2.7 in stained samples. Results from Welch's t‐test indicate significant difference between the two groups at a 95% confidence interval. Results for paired t‐tests for each of the individual soft tissues also indicated significant improvement of contrast in all tissues after staining. Relatively large soft tissues in the middle ear such as the tympanic membrane and the tensor tympani muscle were impacted by staining more than smaller tissues such as the stapedial annular ligament. The increase in contrast with IKI solution confirms its potential application in automatic segmentation of the middle‐ear soft tissues.     

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.     

SURFACE TENSION-DRIVEN CONVECTION IN A CYLINDRICAL GEOMETRY

Three aspects of surface tension-driven natural convection in a bounded cylindrical geometry are investigated. First, the linear stability of the steady subcritical and supercritical convective solutions near the critical point is examined using a perturbation analysis and the theory of differential operators. Second, the effect of small surface tension gradients on free surface flows in deep fluid layers is studied. It is shown that surface tension effects produce subcritical convective solutions for this buoyancy-dominated flow. Finally, solutions are obtained for finite amplitude surface tension-driven flows in a cylindrical container.     

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)     

INVESTIGATION INTO THE THEORIES OF DESORPTION ISOTHERMS FOR ROUGH RICE AND PEANUTS

SUMMARY— Several existing mathematical models are investigated with respect to their range of applicability to biological materials. It is found that a logarithmic plot of vapor pressure of water in the material vs. vapor pressure of pure water can best describe the sorption phenomenon. The general form of the equation is: In P = f₁ (W) In P_s+ f₂ (W). The functions f₁ (W) and f₂ (W) may differ significantly from material to material. The method of determining these functional relationships is described in detail for rough rice and peanuts. The comparison of experimental and computed values for peanuts shows that this method can predict the required sorption isotherm data within 2% deviation from the experimental values.     

A Study of Solvent Extraction of Lipids from Whole Peanut Kernels Using All-Purpose Automatic Solvent Extractor

Extraction of lipids from whole peanut kernels can be accomplished much faster in an automatic solvent extractor with a lower solvent: seed ratio than by immersion or in a Soxhlet extractor. A possible explanation of the function of moisture in the extraction of lipids from the whole peanut kernels has been put forward. This mode of extraction is expected to produce economically fat-lean kernels, while oil is obtained as a co-product.     

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