Control of stroma-dependent hematopoiesis by basic fibroblast growth factor: stromal phenotypic plasticity and modified myelopoietic functions

The immunological agglutination reactions of physically absorbed F(ab')2 molecules onto anionic and cationic latex particles have been investigated by means of optical absorbance measurements. These measurements have been conducted under different conditions to determine the most influential factors. Surface F(ab')2 and BSA densities, particle concentration in the reaction medium and polyethylene glycol concentration are some of these factors. Sensitized cationic and anionic latexes differ considerably with respect to their colloidal stability and reactivity. As a general rule, the sensitized cationic latex has a relatively higher colloidal stability and hence, it provides reagents with a better optical response. Less than 0.025 microgram/ml of C-reactive protein has been detected using this particle enhanced optical immunoassay.     

Multispectral data compression using bidirectional interbandprediction

The introduction of high spatial and spectral resolution sensors on-board remote-sensing spacecraft has increased, by orders of magnitude, the data rates which need to be sustained on the down-link or cross-link transmission channels. Since these channels are severely limited in capacity, the need arises to perform on-board compression to reduce the volume of data which would need to be down-linked. This paper discusses the development and refinement of a low complexity lossy spectral/spatial compression method which provides high compression ratios at low levels of distortion. The developed techniques uses pixels in adjacent bands to predict the intensity of pixels in the band being compressed via a simple linear prediction model. This prediction method when combined with a low-distortion discrete cosine transform (DCT) block coding method yields performance comparable to block-adaptive Karhunen-Loeve Transform (KLT)-DCT methods without incurring the complexity penalty of the KLT. The methods' performance suffers under misregistration. A fractional-pixel interpolation enhancement to the basic technique significantly improves the performance in the case of misregistered bands     

Outlier-resistant methods for estimation and model fitting

Least squares is perhaps the most widely used technique for model fitting. In this article, we illustrate the poor performance of least squares when there are spurious values, or outliers, in a sequence of measurements. A brief overview of three well-known classes of robust alternatives to the least-squares mean is presented. For robust regression, a recent proposal called least median squares (LMS) is decribed. LMS regression is compared to least-squares regression in an example involving the estimation of optical fiber geometry. References are provided for software that is available for robust estimation techniques surveyed in this article.     

Increasing the service properties of weld joints by electrohydroimpulse treatment

Known examples of the positive influence of electrohydroimpulse treatment on the quality of weld joints of various steels, particularly including an increase in their long-term and cyclic strength and also corrosion resistance, are analyzed. It is shown that in this case there is a reduction in residual macro- and micro-stresses and also a change in the parameters of the dislocation structure of the joint metal in the direction of stabilization of it.Translated from Problemy Prochnosti, No. 4, pp. 119–123, April, 1996.     

Effect of oxygen deficiency (δ) on transition temperature of yttrium cuprate superconductors

The nature of pairing mechanism as well as transition temperature of yttrium cuprates is discussed using the strong coupling theory. An interaction potential has been developed for the layered structure with two conducting CuO₂(a–b) layers in a unit cell. The interaction potential properly takes care of electron-electron, electron-phonon and electron-plasmon interactions. Furthermore, the electron-phonon coupling parameter (λ), the modified Coulomb repulsive parameter (μ*) and the 2D acoustic phonon (plasmon) energy as a function of oxygen deficiency is worked out. Finally, the superconducting transition temperature (T _c) is then evaluated by using these coupling parameters and obtainedT _c = 95(92)K for Y(Yb)Ba₂Cu₃O_7−δ superconductors withδ = 0·0. The model parameters estimated from the layered structure approach are consistent with the strong coupling theory. The result deduced on the variation ofT _c withδ are in fair agreement with the earlier reported data on yttrium cuprates. The analysis of the above results are discussed.     

Storage performance-metrics and benchmarks

The metrics and benchmarks used in storage performance evaluation are discussed. The technology trends taking place in storage systems, such as disk and tape evolution, disk arrays, and solid-state disks, are highlighted. The current popular I/O benchmarks are then described, reviewed, and run on three systems: a DECstation 5000/200 running the Sprite Operating System, a SPARCstation 1+ running SunOS, and an HP Series 700 (Model 730) running HP-UX. Two approaches to storage benchmarks-LADDIS and a self-scaling benchmark with predicted performance-are also described     

Thermal expansion of semiconductor materials

The thermal expansion of tellurides of germanium, bismuth, and intermetallic compounds is investigated over the temperature range 293-973 K.Belarusian Agricultural Technical University, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 5, pp. 612–616, May 1994.     

Switched-current memory circuits for high-precision applications

We discuss circuit parameters that limit the precision of basic dynamic current-memory cells. In addition to analyzing current-copying errors caused by the finite output conductances of the current sources and by the clock-feedthrough (CFT) of the feedback switches, we analyze the noise performance of the basic memory cell. To reduce CFT and noise, we propose a novel circuit based on Miller capacitance-enhancement. Measurement results of memory cells integrated in a 1-μm CMOS process confirm the theoretical findings; with our CFT and noise reduction technique based on Miller enhanced capacitance and dummy switches, we achieve a dynamic range of 11 b at clock frequencies greater than 100 kHz     

Estimation of linear parametric models of nonGaussian discreterandom fields with application to texture synthesis

A general (possibly asymmetric noncausal and/or nonminimum phase) 2D autoregressive moving average random field model driven by an independent and identically distributed 2D nonGaussian sequence is considered. The model is restricted to be invertible, i.e., system zeros are not allowed to lie on the unit bicircle. Three performance criteria are investigated for parameter estimation of the system parameters given only the output measurements (image pixels). The proposed criteria are functions of the higher order cumulant statistics of an inverse filter output. One of these criteria is novel and the others have been considered in past only for moving average inverses and without any analysis of their consistency. In the paper strong consistency of the proposed methods under the assumption that the system order is known is proved. The convergence of the proposed parameter estimators under overparametrization is also analyzed. Experimental results involving synthesized as well as real life textures are presented to illustrate the performance of two of the considered approaches. Experimental results of synthesis of 128x128 textures visually resembling several real life textures in the Brodatz album (and other sources) are presented.     

An experimental and numerical investigation of ductile crack growth characteristics in surface cracked specimens under combined loading

Fracture mechanics tests have been performed in the upper shelf region of a steel on large surface cracked plate (SCT) specimens and on small compact tension (CT) specimens. Some of the SCT specimens were subjected to combined tension and bending in such a way that the loading was strongly non-proportional. Crack growth characteristics were compared between the specimens in order to assess possible influences of geometry and nonproportional loading. The differences observed could unambiguously be reduced to and correlated with differences in constraint. Constraint parameters were evaluated by detailed three-dimensional finite element computations and quantities for growing cracks were interpreted on the basis of deformation theory considerations, in analogy with the commonly used J _R-philosophy. It was noted that the initiation of ductile crack growth along a three-dimensional crack front appears to be independent of the degree of local constraint. However, the increase in toughness for a growing crack was markedly affected by the degree of local constraint. Some estimates of the constraints effects regarding stability considerations were also made.