Mordechay Schlesinger

Optical Constants of Thin Discontinuous Nickel Films

The optical constants and the thickness of thin discontinuous nickel films were determined simultaneously from reflection and transmission measurements in the photon energy range 0.5–6 eV. From supplementary mass measurements, the fractional volume of metal in each film was established and the optical constants of the individual nickel islands were calculated using the Maxwell Garnett theory. The optical constants of islands are compared to those of bulk nickel and are found to give a qualitative support to the speculation that the free electron part of the optical conductivity in metal islands should suffer a size effect much stronger than the effects due to interband processes.

High frequency giant magnetoresistance in evaporated Co/Cu multilayers deposited on Si(111) and Si(100)

We report giant magnetoresistance (GMR) in Co/Cu multilayers deposited using high vacuum electron beam evaporation on Si(111) and Si(100). Samples grown on Si(111) show enhanced magnetoresistance and coercivity, which may be attributed to ill-defined interfacial boundaries between successive layers. Previous work exploring the frequency dependency of GMR has been done using microwave techniques to indirectly determine GMR. Our magnetoresistance data was obtained by replacing one side of a square loop antenna with a Co/Cu multilayer and measuring the impedance. No effect on the magnitude of the GMR, due to high frequency test signals, was observed for a frequency range from dc to 5.5 GHz.

Comments on a new mathematical technique in the theory of complex spectra

A large body of work on the algebraic properties of the Gelfand labelling scheme for atoms with several electrons has recently been synthesized by Harter (see abstr. A31652 of 1974) into a compact procedure for the construction of total angular momentum eigenfunctions and the evaluation of angular coefficients. Certain ambiguities in the procedure are removed. Also, an improved method for the diagonalization of the angular momentum matrix in the Galfand basis set is presented. As an example, the doublet states of the f3 configuration are discussed.

Calculations of atomic spin-orbit matrix elements in the unitary group approach☆

Abstract We present detailed closed-form expressions for the evaluation and numerical calculation of atomic spin-orbit matrix elements in the unitary group approach. A minicomputer implementation of the calculations is described.

The lowest energy 4ƒ-5d transition of the triply ionized gadolinium in CaF2

Abstract The lowest energy 4ƒ-5 d transition of triply ionized gadolinium in CaF 2 is tentatively identified. It is found that the no phonon line is not accompanied by the ≈ 480 cm -1 vibronic feature observed in ten other triply ionized rare-earth ions in the CaF 2 matrix.

The effects of heating on color centers in germanium-doped quartz

Abstract Optical absorption, electron paramagnetic resonance absorption, and thermoluminescence have been measured in germanium-doped quartz crystals which have been X-irradiated at room temperature and subsequently heated. Strong bleaching of the 280 nm optical absorption and the A and C center magnetic resonance absorptions coincided with maxima of the total thermoluminescent glow curve. The temperature at which these several phenomena occurred varied for different quartz samples.

Estimation of Tumor Interstitial Fluid Pressure (TIFP) Noninvasively

Tumor interstitial fluid pressure (TIFP), is a physiological parameter with demonstrated predictive value for a tumor’s aggressiveness, drug delivery, as well as response to treatments such as radiotherapy and chemotherapy. Despite its utility, measurement of TIFP has been limited by the need for invasive procedures. In this work, the theoretical basis for approaching the absolute value of TIFP and the experimental method for noninvasively measuring TIFP are presented. Given specific boundary and continuity conditions, we convert theoretical variables into measurable variables by applying MRI technology. The work shows that TIFP in the central region of the tumor can be estimated by an analysis of the variation of tissue fluid motion in the tumor rim and surrounding tissue. It is determined from three noninvasive measurable parameters: i) an estimate of the velocity of the tumor interstitial fluid at the tumor surface, which is maximal, ii) a measurement of the distance from the tumor surface to where the tumor exudates are absorbed (or normalized), and iii) an estimate of the hydraulic conductivity of the interstitium through which the tumor exudate travels. We experimentally show that the fluid flow within the tumor rim is not uniform, even for a round shaped tumor, and demonstrate the procedures for the noninvasive measurement of TIFP.

Toward a Model of Models: Part I

In this work we discuss the issue of what, if any, limits exist on modelling. We extend notions of Godel to suggest that there may exist theoretical limits to what can be modelled, independent of the complexity of the modelling system. Second, in this talk we briefly describe the system called VPMS, currently under construction by our group, for performing modelling in a distributed HPC context. We suggest that the theoretical limits to modelling may be overcome by appealing to learning based computing paradigms in non-Turing complete systems.

Induced Crystallographic Orientations in Electrodeposited Ni‐Cu Multilayers

The results of controlling the preferential crystallographic orientation of electrodeposited Ni-Cu multilayers by means of electrochemical methods are reported. These multilayers were grown on pulse electrodeposited and dc electrodeposited copper foils of (111) and (220) preferential crystallographic orientation, respectively. Since multilayers have a tendency to grow epitaxially, the multilayers grown on these substrates exhibited (111) or (220) preferential crystallographic orientation. Results of electrodeposition of multilayers on cold-rolled copper foil and on titanium are also presented. Similar results can be obtained using polycrystalline copper foil as compared to single crystal copper substrates.

Distributing Fast Fourier Transform Algorithms for Grid Computing

An abstract machine based approach to distributing the Fast Fourier Transform (FFT) on a queue of N=2 L complex values across a network of N/2 virtual machines is presented. The strategy involves three stages, in general, (a) constructing the FFT virtual machine (FFT_VM) as a set of communicating virtual machine compute nodes, (b) instantiation of the FFT_VM on a physical “grid” of networked computers, and (c) execution of the FFT data queue. The fundamental computational unit of the FFT_VM is a virtual machine called FFT_VM_Butterfly which reflects a specialised computation and communication unit referred to as the Butterfly algorithm, a core component of the FFT algorithms typified as Cooley-Tukey. This approach affords opportunity to prove the correctness of the software design in various contexts of application based only on rigorous logical analysis and also demonstrates flexibility and adaptability to metacomputing design and construction and use of dynamic execution environments such as computational grids.