Dynamical correlations and the direct summation method of evaluating infinite continued fractions

Testes from 11.5-day-old mouse embryos, with and without attached mesonephroi, were cultured for 7 days. Isolated testes failed to develop well-differentiated testis cords: however, when cultured attached to a mesonephros from either a male or a female donor embryo, testes developed cords that were normal in appearance. Testes cultured next to a mesonephric region but separated from it by a permeable filter, did not develop normal cords, nor did testes grafted to fragments of embryonic limb or heart. When testes were grafted to mesonephric regions from mice carrying a transgenic marker, the marker was found in some of the peritubular myoid cells and other interstitial cells of the testis, but not in the Sertoli cells or the germ cells. We conclude that after 11.5 days post coitum, cells can migrate from the mesonephric region into the differentiating testis and can contribute to the interstitial cell population, and that this contribution is necessary for the establishment of normal cord structure. The germ cells in all cultured testes, whether or not differentiated cords were present, were T1 prospermatogonia: no meiotic germ cells were seen.     

PRA*: Massively Parallel Heuristic Search

In this paper we describe a variant of A* search designed to run on the massively parallel, SIMD Connection Machine (CM-2). The algorithm is designed to run in a limited memory by the use of a retraction technique which allows nodes with poor heuristic values to be removed from the open list until such time as they may need reexpansion, more promising paths having failed. Our algorithm, called PRA* (for Parallel Retraction A*), is designed to maximize use of the Connection Machine′s memory and processors. In addition, the algorithm is guaranteed to return an optimal path when an admissible heuristic is used. Results comparing PRA* to Korf′s IDA* for the fifteen puzzle show significantly fewer node expansions for PRA*. In addition, empirical results show significant parallel speedups, indicative of the algorithm′s design for high processor utilization.     

Synthesis of satellite footprint patterns from rectangular planar array antenna by using swarm‐based optimization algorithms

A pattern synthesis method based on Firefly Algorithm (FA) and Artificial Bee Colony (ABC) optimization has been presented to generate satellite footprint patterns from a rectangular planar array of isotropic antennas by modifying the amplitude, phase, and the state of the array elements. Three cases comprising three different footprints of rectangular, square, and circular boundary are generated from the same array by using two different swarm‐based optimization algorithms FA and ABC. Both the algorithms, following the proposed procedures are able to generate the three different footprint patterns while maintaining a satisfactory lower peak side lobe level and ripple. A comparative analysis has been carried out between FA, ABC, and Genetic Algorithm (GA) for the presented problem in terms of fitness value for the three different cases. The superiority of FA and ABC over GA has been established in terms of finding better solutions for all the three cases of the proposed problem. Copyright © 2013 John Wiley & Sons, Ltd.     

Shear waves in a fluid saturated elastic plate

In the present context, we consider the propagation of shear waves in the transverse isotropic fluid saturated porous plate. The frequency spectrum for SH-modes in the plate has been studied. It is observed that the frequency of the propagation is damped due to the two-phase character of the porous medium. The dimensionless phase velocities of the shear waves have also been calculated and presented graphically. It is interesting to note that the frequency and phase velocity of shear waves in porous media differ significantly in comparison to that in isotropic elastic media.     

The dispersion of lead and graphite in aluminium alloys for bearing applications

The experimental procedure for uniform dispersion of lead and graphite in some aluminium alloys which are particularly suitable for bearing purposes is described in this paper. The results of thermal expansion studies and wear testing of the lead- and graphite-dispersed Al-Si systems have been included to demonstrate their good bearing properties.     

<Emphasis Type="Italic">Ab Initio</Emphasis> Studies of Hydrogen Defects in CdTe

Using first-principles calculations based on density functional theory, we have investigated the nature of H defects in CdTe. The formation energy calculations indicate that the ground state position of the H inside the CdTe lattice depends on charge state: the lowest energy position for H⁰ and H⁺ is at the bond center site, while H⁻ prefers the tetrahedral interstitial site with Cd nearest neighbors (T_Cd). We find that H in CdTe acts as an amphoteric impurity. In p-type samples, H is in a positive charge state, acting as a donor to neutralize the free holes in the valence band, and in n-type samples H acquires an electron, compensating the donors in the sample.     

Inertia effect of micropolar fluid in squeeze bearings and thrust bearings

A theoretical study is made of squeeze films between two infinitely long rectangular plates and between circular plates, and of a thrust bearing, assuming the lubricant to be a micropolar fluid. The effect of inertia is considered and the effects of the material constants of the fluid on the bearing characteristics are discussed. The effect of inertia is to increase the time of approach for squeeze bearings and to diminish the load capacity for thrust bearings. For squeeze bearings, the time of approach is greater with a micropolar fluid than with a Newtonian fluid and, for thrust bearings, the load capacity is greater with a micropolar fluid than with a Newtonian fluid.