A pseudoinverse filter for limited-angle diffraction tomography involving objects with planar structure

A reconstruction technique for limited-angle diffraction tomography is described in which a special pseudoinverse filter is applied to the back-propagation. Using this approach, it is possible to reconstruct a ten-layered object with only 19 projections having angles ranging from -10 degrees to +10 degrees . It is concluded that the algorithm proposed here offers an efficient and computationally easy method for reconstructing an object with planar structure. Even when the number of layers is large and the range of incident angle is limited, the method will give good images.

Parallel Algorithms for Image Template Matching on Hypercube SIMD Computers

This correspondence presents several parallel algorithms for image template matching on an SIMD array processor with a hypercube interconnection network. For an N by N image and an M by M window, the time complexity is reduced from O(N2M2) for the serial algorithm to O(M2/K2 + M * log2 N/K + log2 N * log2 K) for the N2K2-PE system (1 ¿ K ¿ M), or to O(N2M2/L2) for the L2-PE system (L ¿ N). With efficient use of the inter-PE communication network, each PE requires only a small local memory, many unnecessary data transmissions are eliminated, and the time complexity is greatly reduced.

Calibration of optical fiber power meters: the effect of connectors

This paper addresses the question of accurate measurement of optical power at the wavelengths and power levels of interest to the telecommunications community. In particular, we examine the calibration of power meters that are destined for use in a field environment. Connectors and adapters are shown to skew the measurements, leading to errors attributable to reflections from the connector or to angular dependence of detector response. Calibration data are taken using two popular connector types: a biconic and an SMA type. The data are sufficient to illustrate the problem but definitive conclusions cannot be drawn regarding variability of performance with connector or connector type, because of the limited data.

The first stage in two-stage template matching

This paper formulates the problem encountered in the first stage of two-stage, binary template matching as a set of hypotheses to be tested, including a hypothesis of ``no object.'' Two new statistics R and G are proposed, based on a likelihood ratio, and are compared to the sum of absolute differences and a correlation measure by analytical approximations and Monte Carlo experiments. Statistical power and a measure of sensitivity to the true location of the object are the criteria. Parameters are the numbers of 1's in object and image, subtemplate size, and parameters reflecting intensity distortion between template and object. One of the proposed statistics R is much more computationally intensive than the other G. Although R is more powerful than G and the other statistics, G is generally more sensitive to the true object location. Statistic G is also more powerful than the sum of absolute differences and correlation. All statistics are robust to incomplete knowledge of distortion parameters. Experiments on Landsat images confirm the sensitivity of G and recommend it for application in the first stage.

Activation of the classical complement pathway by a polysaccharide from sugar cane

The effects of an immunostimulating polysaccharide, Bo, from sugar cane, on the complement system have been investigated. Bo, a glucan of about 10,000 mol wt, was found to activate complement in whole human and guinea pig serum in vitro by the classical pathway. Complement consumption was also demonstrated in guinea pigs upon intravenous injection. Specifically, C1 is activated, and C4 and C2, as well as C3, are consumed. The activation is prevented when Ca++ ions are chelated by ethyleneglycoltetraacetic acid, and when C1q is lacking. Hence, it does not rest on direct activation of C1s. Supplementation of C1q-deficient human serum with purified C1q restores the ability to be activated by Bo. The alternative pathway of complement is little if at all affected by the polysaccharide. The activation of C1 seems to be mediated by immune complex formation between Bo and naturally occurring immunoglobulins. Complement in sera from two severely hypogammaglobulinemic patients was not activated by Bo, but was made reactive by addition of purified human immunoglobulin G.