A programmable triangular neighborhood function for a Kohonen self-organizing map implemented on chip

An efficient transistor level implementation of a flexible, programmable Triangular Function (TF) that can be used as a Triangular Neighborhood Function (TNF) in ultra-low power, self-organizing maps (SOMs) realized as Application-Specific Integrated Circuit (ASIC) is presented. The proposed TNF block is a component of a larger neighborhood mechanism, whose role is to determine the distance between the winning neuron and all neighboring neurons. Detailed simulations carried out for the software model of such network show that the TNF forms a good approximation of the Gaussian Neighborhood Function (GNF), while being implemented in a much easier way in hardware. The overall mechanism is very fast. In the CMOS 0.18 mu m technology, distances to all neighboring neurons are determined in parallel, within the time not exceeding 11 ns, for an example neighborhood range, R, of 15. The TNF blocks in particular neurons require another 6 ns to calculate the output values directly used in the adaptation process. This is also performed in parallel in all neurons. As a result, after determining the winning neuron, the entire map is ready for the adaptation after the time not exceeding 17 ns, even for large numbers of neurons. This feature allows for the realization of ultra low power SOMs, which are hundred times faster than similar SOMs realized on PC. The signal resolution at the output of the TNF block has a dominant impact on the overall energy consumption as well as the silicon area. Detailed system level simulations of the SOM show that even for low resolutions of 3 to 6 bits, the learning abilities of the SUM are not affected. The circuit performance has been verified by means of transistor level Hspice simulations carried out for different transistor models and different values of supply voltage and the environment temperature - a typical procedure completed in case of commercial chips that makes the obtained results reliable. (C) 2011 Elsevier Ltd. All rights reserved

Correlation between metallothionein (MT) expression and selected prognostic factors in ductal breast cancers.

Our study aimed at examining significance of metallothionein (MT) expression in ductal breast cancers by determination of a relationship between expression of MT protein (MT-1/2) and selected prognostic factors, including grade of histological differentiation (G), expression of Ki-67 proliferative antigen, expression of estrogen receptors (ER) and progesterone receptors (PgR) and expression of HER-2 receptor. Material for the studies involved 54 samples of invasive ductal breast cancer, manifesting malignancy grades of G1-G3. In paraffin sections of examined tumours immunohistochemical reactions were performed using specific antibodies directed to MT, Ki-67, ER, PgR or HER-2. Intensity of MT-specific immunohistochemical reactions was measured using the semiquantitative IRS scale of Remmele. Intensity of colour reactions targeted at Ki-67, ER, PgR was evaluated scoring proportions of positive cells, while HER-2-specific reactions were evaluated in the scale of 0-3 points. The lowest level of MT expression was detected in breast cancer cases of G1 malignancy grade (G1 vs G3 p=0.020). A positive correlation between MT and Ki-67 antigen expression (r=0.32, p=0.019) was disclosed. Moreover, MT expression exhibited negative correlations with expression of ER (r=-0.35, p=0.008) and PgR (r=-0.27, p=0.046). No relationships could be detected between expression of MT and expression of HER-2 (r=0.12, p=0.37). The obtained results suggest that MT expression might be helpful in prognostic evaluation of ductal breast cancers

A low power, low chip area decimation filter for Σ - Δ modulator for flywheel MEMS gyro realized in the CMOS 180 nm technology

The paper presents a low power and low chip area decimation filter for a 15-bits Σ-Δ analog-to-digital converter (ADC) designed for a flywheel MEMS gyroscope. In contrary to typical solutions, in which decimation is performed after each filtering stage, in the proposed approach all filter sections operate at the sampling frequency of the modulator. The low power dissipation is in this case achieved by substantially simpler structure of particular stages. By selecting the oversampling ratio (OSR) of the modulator sufficiently large, e.g. 200, the decimation filter composed of Finite Impulse Response (FIR) filters with equal coefficients does not distort the passband signal. The low chip area results from eliminating a complex selective filter usually placed at the end of the filtering chain in the decimation filter