Parallel architecture for fast transforms with trigonometric kernel

We present an unified parallel architecture for four of the most important fast orthogonal transforms with trigonometric kernel: Complex Valued Fourier (CFFT), Real Valued Fourier (RFFT), Hartley (FHT), and Cosine (FCT). Out of these, only the CFFT has a data flow coinciding with the one generated by the successive doubling method, which can be transformed on a constant geometry flow using perfect unshuffle or shuffle permutations. The other three require some type of hardware modification to guarantee the constant geometry of the successive doubling method. We have defined a generalized processing section (PS), based on a circular CORDIC rotator, for the four transforms. This PS section permits the evaluation of the CFFT and FCT transforms in n data recirculations and the RFFT and FHT transforms in n-1 data recirculations, with n being the number of stages of a transform of length N=rⁿ. Also, the efficiency of the partitioned parallel architecture is optimum because there is no cycle loss in the systolic computation of all the butterflies for each of the four transforms     

Algorithm for cosine transform of Toeplitz matrices

An algorithm for calculating the 2D cosine transform of a Toeplitz matrix is presented. The algorithm is based on the application of 1D cosine transforms. More specifically, four 1D cosine transforms of size N are needed to obtain the transform of a Toeplitz matrix of size N×N. This is an improvement over previously published algorithms. The algorithm is also simple and regular     

Radix-4 Vectoring CORDIC Algorithm and Architectures

In this work we extend the radix-4 CORDIC algorithm to the vectoring mode (the radix-4 CORDIC algorithm was proposed recently by the authors for the rotation mode). The extension to the vectoring mode is not straightforward, since the digit selection function is more complex in the vectoring case than in the rotation case; as in the rotation mode, the scale factor is not constant. Although the radix-4 CORDIC algorithm in vectoring mode has a similar recurrence as the radix-4 division algorithm, there are specific issues concerning the vectoring algorithm that demand dedicated study. We present the digit selection for nonredundant and redundant arithmetic (following two different approaches: arithmetic comparisons and table look-up), the computation and compensation of the scale factor, and the implementation of the algorithm (with both types of digit selection) in a word-serial architecture. When compared with conventional radix-2 (redundant and non-redundant) architectures, the radix-4 algorithms present a significant speed up for angle calculation. For the computation of the magnitude the speed up is very slight, due to the nonconstant scale factor in the radix-4 algorithm.     

Mapping of Trellises Associated with General Encoders onto High-Performance VLSI Architectures

A rate 1/n binary generic convolutional encoder is a shift-register circuit where the inputs are information bits and the outputs are blocks of n bits generated as linear combinations on the appropriate shift register contents. The decoding of the outputs of a convolutional encoder can be carried out by the well-known Viterbi algorithm. The communication pattern of the Viterbi Algorithm is given as a graph, called trellis, associated to the state diagram of the corresponding encoder. In this paper we present a methodology that permits the efficient mapping of the Viterbi algorithm onto a column of an arbitrary number of processors. This is done through the representation of the data flow by using mathematical operators which present an inmediate hardware projection. A single operator string has been obtained to represent a generic encoder through the study of the data flow of free-forward encoders and feed-back encoders. The formal model developed is employed for the partitioning of the computations among an arbitrary number of processors in such a way that the data are recirculated opimizing the use of the processors and the communications. As a result, we obtain a highly regular and modular architecture suitable for VLSI implementation.     

Preparation and storage stability of dried salted mutton

Minced (8 or 18 mm plate) mutton with salt (25%) and sorbate (0·4%) was pressed into cakes about 11 cm in diameter and 3 cm high. The cakes were partially dried in an air oven at 40°C for 48 h to a water activity of about 0·75. The cakes were packed, either in vacuo or in air, and stored at 30 or 2°C for up to 60 days. Objective assessment of quality showed that these dried salted meats can be kept for up to 60 days at 30°C with little loss of textural or nutritional quality although some fading, due to haemoprotein breakdown, occurs. Packaging in vacuum, however, minimises this loss of colour and would be recommended for centralised manufacture prior to distribution in developing, tropical countries.     

Fuzzy ontologies-based user profiles applied to enhance e-learning activities

Nowadays, the impact of technological developments on improving human activities is becoming more evident. In e-learning, this situation is no different. There are common to use systems that assist the daily activities of students and teachers. Typically, e-learning recommender systems are focused on students; however, teachers can also benefit from these type of tools. A recommender system can propose actions and resources that facilitate teaching activities like structuring learning strategies. In any case, a complete user’s representation is required. This paper shows how a fuzzy ontology can be used to represent user profiles into a recommender engine and enhances the user’s activities into e-learning environments. A fuzzy ontology is an extension of domain ontologies for solving the problems of uncertainty in sharing and reusing knowledge on the Semantic Web. The user profile is built from learning objects published by the user himself into a learning object repository. The initial experiment confirms that the automatically obtained fuzzy ontology is a good representation of the user’s preferences. The experiment results also indicate that the presented approach is useful and warrants further research in recommending and retrieval information.     

Phosphorus availability from phosphate rock and sewage sludge as influenced by the addition of water soluble phosphate fertilizer

Phosphorus (P) inputs are required for sustainable agricultural production in most acid soils of the tropics and subtropics. Phosphate rocks (PR) and organic materials have been suggested as alternative P sources in these soils. Quantitative information on the P availability from sewage sludge (SL) is scanty. Methods to improve the effectiveness of PR such as partial acidulation and compaction with water-soluble P sources have been recommended. The objective of this greenhouse study was to evaluate the relative agronomic effectiveness (RAE) of Florida PR and sewage sludges (irradiated and non-irradiated) applied alone and in mixture with a water-soluble source (triple superphosphate, TSP) at two rates (50 and 150 mg P kg^–1 soil). The ³²P isotope dilution technique was utilised to determine the proportion of P in the plant taken up from the P fertilizer treatments. Wheat was grown on an acid loamy sand Dystric Eutrocrepts and harvested 6 weeks after planting. Results on total P uptake and the RAE of the P fertilizer sources tested indicated that the addition of 50 mg P kg^–1 soil as TSP was adequate in supplying P to the 6-week-old wheat plants as compared to PR and sewage sludge. Intermediate values were obtained for the mixtures. Similar responses were observed for the high P rate. For a given P rate, phosphorus uptake from PR and SL in presence of TSP was higher than P uptake from these sources alone, indicating an enhancement effect of TSP on the effectiveness of these non-readily available sources. With respect to P uptake from PR applied alone, the relative increases in P uptake from PR due to TSP influence were 52 and 67% for the low and high P rates, respectively. The relative increases in P uptake from SL due to TSP when compared to P uptake from SL alone were 102 and 59% for the low and high P rates of application. Application of a water-soluble P fertilizer together with a non-readily available P source shows an enhancement on the P uptake from the non-readily available P source by the wheat plants. In this experiment the estimated enhancement effects are very likely underestimated.     

Evaluation of the agronomic effectiveness of natural and partially acidulated phosphate rocks in several soils using32P isotopic dilution techniques

The agronomic effectiveness of two natural phosphate rocks (PRs) from North Carolina (USA) and Togo and their 50% partially acidulated products (PAPRs) was evaluated in two greenhouse experiments using³²P isotopic dilution techniques, namely L and A_L values.In the first experiment rye grass was grown in a soil from Ghana. While the proportion of P in the plant derived from the P fertilizer (Pdff) ranged on. the average from about 10% for the PRs up to 80% for the PAPRs, the P fertilizer recovery was less than 1% for a 60-day growth period. In the second experiment, average values of P in the maize plants derived from the PAPRs ranged from 35% to 75% in 3 different soils. Both PRs were ineffective with the exception of North Carolina PR in the Seibersdorf soil. The P fertilizer recovery was 0.25% for the North Carolina PR in this soil whereas the recovery values ranged from 1.2% to 1.6% for the PAPRs.Mean values of the relative fertilizer efficiency estimated from the L values of each soil were less than 1% for the PRs whereas the values for the PAPRs which were dependent on soil type ranged from 20% up to 45%. The coefficient of relative effect of partial acidulation, that was calculated from the ratio of A_L values for PR and PAPR in each soil indicated that partial acidulation increased the effectiveness of the natural PRs in all soils under study.This study showed that the use of³²P isotope dilution techniques allows an accurate measurement of the P availability from natural and modified PR products to crops. Another advantage is that quantitative comparison of the P sources under study, PRs and PAPRs in this case, can be made even in soils where there is no response to the applied P sources.     

Engineering linear F(ab')2 fragments for efficient production in Escherichia coli and enhanced antiproliferative activity

We developed a novel bivalent antibody fragment, the linear(L-) F(ab')₂, comprising tandem repeats of a heavy chain fragmentV_H–C_H1–V_H–C_H1 cosecreted with a light chain.Functional humanized L-F(ab')₂ directed against p185^HER2 wassecreted from Escherichia coli at high titer (100 mg/l) andpurified to homogeneity. The L-F(ab')₂ binds two equivalentsof antigen with an apparent affinity (K_d = 0.46 nM) that iswithin 3-fold of the corresponding thioether-linked F(ab')₂fragment The N-terminal site binds antigen with an affinity(K_d = 1.2 nM) that is 4-fold greater than that for the C-terminalsite, as shown by the comparison of L-F(ab')₂ variants containinga single functional binding site. L-F(ab')₂ has greater antiproliferativeactivity than the thioether-linked F(ab')₂ against the p185^HER2-overexpressingtumor cell line BT474. Linear and thioether-linked F(ab')₂ havevery similar pharmacokinetic properties in normal mice, andtheir serum permanence times are respectively 7- and 8-foldlonger than the corresponding Fab fragment L-F(ab')₂ offersa facile route to bivalent antibody fragments that are potentiallysuitable for clinical applications, and that may have improvedbiological activity compared with thioether-linked F(ab')₂ fragments.