On the power of elementary features in spiking neural P systems

Since their first publication in 2006, spiking neural (SN) P systems have already attracted the attention of a lot of researchers. This might be owing to the fact that this abstract computing device follows basic principles known from spiking neural nets, but its implementation is discrete, using membrane computing background. Among the elementary properties which confer SN P systems their computational power one can count the unbounded fan-in (indegree) and fan-out (outdegree) of each “neuron”, synchronicity of the whole system, the possibility of delaying and/or removing spikes in neurons, the capability of evaluating arbitrary regular expressions in neurons in constant time and some others. In this paper we focus on the power of these elementary features. Particularly, we study the power of the model when some of these features are disabled. Rather surprisingly, even very restricted SN P systems keep their universal computational power. Certain important questions regarding this topic still remain open.     

Implementation of Digital Electronic Arithmetics and its application in image processing

In this paper we introduce new algorithm implementations of a new parametric image processing framework that will accurately process images and speed up computation for addition, subtraction, and multiplication. Its potential applications include computer graphics, digital signal processing and other multimedia applications. This Parameterized Digital Electronic Arithmetic (PDEA) model replaces linear operations with non-linear ones. The implementation of a parameterized model is presented. We also present the design of arithmetic circuits including parallel counters, adders and multipliers based in two high performance threshold logic gate implementations that we have developed. We will also explore new microprocessor architectures to take advantage of arithmetic. The experiments executed have shown that the algorithm provides faster and better enhancements from those described in the literature. The FPGA chips used is Spartan 3E from Xilinix. The critical length in the circuit implemented on the FPGA had the minimum period for the proposed subsystem is 10.209 ns (maximum frequency 97.957 MHz). Maximum power consumed is 2.4 mW using 32 nm process and we used parallelism and reuse of the Hardware components to accomplish and speed up the process.     

Comparison of two-dimensional MR digital subtraction angiography of the lower extremity with x-ray angiography

PURPOSE: To perform a preliminary evaluation of the diagnostic accuracy of contrast-enhanced, two-dimensional (2D) magnetic resonance (MR) digital subtraction angiography (DSA) of the lower extremity by comparison with x-ray angiography (XRA). MATERIALS AND METHODS: Forty lower extremities in 22 patients were imaged at multiple levels with both XRA and 2D MR DSA. Images were retrospectively analyzed by three radiologists in a randomized blinded manner. Seventeen vascular segments were graded as an insignificant lesion, a significant lesion, or as an occlusion. With the use of segments well depicted with XRA as the gold standard, the sensitivity, specificity, and accuracy of 2D MR DSA, as compared with XRA, were evaluated. The McNemar-Stuart-Maxwell test was performed to determine the significance of any differences found. RESULTS: Three hundred eighty-three arterial segments were evaluated with both techniques. Three hundred one segments were well depicted with XRA. There was no significant difference between 2D MR DSA and XRA for assessing the degree of occlusive disease in these 301 segments (.25 < P < .5). The sensitivity, specificity, and diagnostic accuracy of 2D MR DSA were found to be 90%, 98%, and 93%, respectively. CONCLUSION: Two-dimensional MR DSA is an accurate method for assessing arterial lesions in the lower extremity.     

Optimal Sequencing of Items In a Consecutive-2-out-of-n System

A consecutive-2-out-of-n system is an array of n items in a line such that the system fails if and only if two consecutive items both fail. Suppose that the items have different probabilities of failing and that the system can be arranged into any sequence of the n items. Which sequence minimizes the probability of a system failure? It has been conjectured that the best sequence is one which essentially interlaces the more reliable items with the less reliable items. This paper partially supports the conjecture by proving it for the case that: a) the n probabilities take on only two distinct values, and b) the n probabilities take on only three distinct values, including either a zero or a one.     

Penile flow index utilizing a Doppler pulse wave analysis to identify penile vascular insufficiency

A Doppler ultrasound probe was used in 42 men to evaluate penile circulation. Twenty-six patients had confirmation of vascular anatomy by pelvic arteriography. The average penile acceleration (peak velocity over pulse rise time) relative to the radial artery acceleration was expressed as the penile flow index. Eleven potent men had a penile flow index of 3.4 plus or minus 0.4 standard error, while 13 impotent men with vascular disease on arteriography had a penile flow index of 21.7 plus or minus 5 standard error (p less than 0.01). Patients with intermediate penile flow index values had variable degrees of erectile failure. This relatively simple, non-invasive technique identifies a vascular component of impotence, thus aiding in the selection of appropriate management.     

Impulse Noise Detector Performance Measure Based on Intensity Volume

An accurate detector performance evaluation method provides a fair comparison platform and can also support in parameter optimization for existing Impulse noise detectors in the applications of medical imaging. The Impulse noise detector performance measure (INDPM) package is widely applied as tools for quantitative comparison among detectors, which contains recall measure, accuracy measure, precision measure, specificity measure and F-measure. However, these five measures suffer from limited accuracy in correctly evaluating the performance of a detector and are not in well agreement with human subjective evaluation. To solve this problem, five new measures are proposed by introducing a new concept of intensity volume to form a new Impulse noise detector performance package (IV-INDPM). Using a standard image dataset, we conduct experimental and comparative tests with 32 different original images and 5 different existing detectors. Results demonstrate the superior performance of each new measure within IV-INDPM in reaching a much closer agreement with human subjective evaluation, compared to existing measures in INDPM. Even though five new measures are efficient in evaluating detectors’ performance from different perspectives, a new benchmark algorithm (IND-BA) is proposed as a robust and overall metric for ease of general-purpose use by making the most of these five new measures. Comparison results demonstrate its efficiency and accuracy.     

Transform coefficient histogram-based image enhancement algorithms using contrast entropy.

Many applications of histograms for the purposes of image processing are well known. However, applying this process to the transform domain by way of a transform coefficient histogram has not yet been fully explored. This paper proposes three methods of image enhancement: a) logarithmic transform histogram matching, b) logarithmic transform histogram shifting, and c) logarithmic transform histogram shaping using Gaussian distributions. They are based on the properties of the logarithmic transform domain histogram and histogram equalization. The presented algorithms use the fact that the relationship between stimulus and perception is logarithmic and afford a marriage between enhancement qualities and computational efficiency. A human visual system-based quantitative measurement of image contrast improvement is also defined. This helps choose the best parameters and transform for each enhancement. A number of experimental results are presented to illustrate the performance of the proposed algorithms.     

Melatonin prevents death of neuroblastoma cells exposed to the Alzheimer amyloid peptide

Studies from several laboratories have generated evidence suggesting that oxidative stress is involved in the pathogenesis of Alzheimer's disease (AD). The finding that the amyloid beta protein (Abeta) has neurotoxic properties and that such effects are, in part, mediated by free radicals has provided insights into mechanisms of cell death in AD and an avenue to explore new therapeutic approaches. In this study we demonstrate that melatonin, a pineal hormone with recently established antioxidant properties, is remarkably effective in preventing death of cultured neuroblastoma cells as well as oxidative damage and intracellular Ca2+ increases induced by a cytotoxic fragment of Abeta. The effects of melatonin were extremely reproducible and corroborated by multiple quantitative methods, including cell viability studies by confocal laser microscopy, electron microscopy, and measurements of intracellular calcium levels. The importance of this finding is that, in contrast to conventional antioxidants, melatonin has a proposed physiological role in the aging process. Secretion levels of this hormone are decreased in aging and more severely reduced in AD. The reported phenomenon may be of therapeutic relevance in AD.     

Human visual system-based image enhancement and logarithmic contrast measure.

Varying scene illumination poses many challenging problems for machine vision systems. One such issue is developing global enhancement methods that work effectively across the varying illumination. In this paper, we introduce two novel image enhancement algorithms: edge-preserving contrast enhancement, which is able to better preserve edge details while enhancing contrast in images with varying illumination, and a novel multihistogram equalization method which utilizes the human visual system (HVS) to segment the image, allowing a fast and efficient correction of nonuniform illumination. We then extend this HVS-based multihistogram equalization approach to create a general enhancement method that can utilize any combination of enhancement algorithms for an improved performance. Additionally, we propose new quantitative measures of image enhancement, called the logarithmic Michelson contrast measure (AME) and the logarithmic AME by entropy. Many image enhancement methods require selection of operating parameters, which are typically chosen using subjective methods, but these new measures allow for automated selection. We present experimental results for these methods and make a comparison against other leading algorithms.     

Decomposition of Binary Matrices and Fast Hadamard Transforms

Binary matrices or (± 1)-matrices have numerous applications in coding, signal processing, and communications. In this paper, a general and efficient algorithm for decomposition of binary matrices and the corresponding fast transform is developed. As a special case, Hadamard matrices are considered. The difficulties of the construction of 4n-point Hadamard transforms are related to the Hadamard problem: the question of the existence of Hadamard matrices. (It is not known whether for every integer n, there is an orthogonal 4n × 4n matrix with elements ± 1.) In the derived fast algorithms, the number of real operations is reduced from O(N²) to O(N log N) compared to direct computation. The proposed scheme requires no zero padding of the input data. Comparisions revealing the efficiency of the proposed algorithms with respect to the known ones are given. In particular, it is demonstrated that, in typical applications, the proposed algorithm is significantly more efficient than the conventional Walsh-Hadamard transform. Note that for Hadamard matrices of orders ≥ 96 the general algorithm is more efficient than the classical Walsh-Hadamard transform whose order is a power of 2. The algorithm has a simple and symmetric structure. The results of numerical examples are presented.