Highlights on endothelins: a review

The endothelins (ET) are a family of contractile peptides made up of 21 amino acids. They are synthesised from larger precursors and they are expressed in different tissues. ET-1 is synthesised in endothelial cells by means of a specific endothelin converting enzyme and it is assumed that most of it is secreted into the basolateral compartment. It acts in a paracrine manner on the ETA and ETB2 receptors located on the surface of the vascular smooth muscle to elicit an increase in intracellular calcium and vasoconstriction. The circulating ET-1 can also activate endothelial ETC and ETB1 receptors releasing vascular smooth muscle relaxing factors, such as nitric oxide and prostacyclin. At present, it is generally accepted that ET-1 is a vasodilator in physiological conditions acting on endothelium ETB1 receptors. Nevertheless, in pathological situations such as hypertension, heart failure, acute myocardial infarction, acute renal failure and vasospastic conditions (Raynaud's disease and subarachnoid haemorrhage), ET-1 levels increase and it binds to the receptors present in vascular smooth muscle in such a way that its vasoconstrictor effect is manifested. Currently, experimental and clinical evidence exists to support the importance of the development of drugs that block the production or actions of ET for use in cardiovascular medicine, particularly in conditions in which these peptides are clearly implicated.     

A Hidden Markov Models combination framework for handwriting recognition

We propose a general framework to combine multiple sequence classifiers working on different sequence representations of a given input. This framework, based on Multi-Stream Hidden Markov Models (MS-HMMs), allows the combination of multiple HMMs operating on partially asynchronous information streams. This combination may operate at different levels of modeling: from the feature level to the post-processing level. This framework is applied to on-line handwriting word recognition by combining temporal and spatial representation of the signal. Different combination schemes are compared experimentally on isolated character recognition and word recognition tasks, using the UNIPEN international database.Received: 16 August 2002, Accepted: 21 November 2002, Published online: 6 June 2003     

Graft copolymerization of methacrylic acid onto xanthan gum by Fe2+/H2O2 redox initiator

The graft copolymer of xanthan gum with methacrylic acid was synthesized in inert atmosphere by using Fentos reagent as a redox initiator. The effect of reaction conditions on grafting parameters [G(%), E(%), C(%), A(%), H(%), and R_g] was investigated. Similar trend was observed on increasing the concentration of ferrous ion and hydrogen peroxide from 4.0 to 20.0 × 10^?3 mol dm^?3 and 2.5 to 10 × 10^?3 mol dm^?3 respectively, i.e., initially grafting parameters increased and after a certain range of concentration grafting parameters showed decreasing trend. Hydrogen ion shows influenced result i.e., small increment of concentration in hydrogen ion presents much increment in percent of grafting. It was observed that the [G(%), E(%), C(%), A(%), and R_g] increased upto 6.67 × 10^?2 mol dm^?3 concentration of methacylic acid after that it decreased. Maximum G(%) was obtained at minimum concentration of xanthan gum i.e., at 40 × 10^?2 g dm^?3. The optimum temperature and time duration of reaction for maximum percentage of grafting were found to be 45°C and 150 min respectively. Thermogravimetric analysis showed that the xanthan gum‐g‐methacrylic acid is thermally more stable than pure gum. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis and characterization of xanthan gum‐g‐N‐vinyl formamide with a potassium monopersulfate/Ag(I) system

A xanthan gum‐g‐N‐vinyl formamide graft copolymer was synthesized through the graft copolymerization of N‐vinyl formamide (NVF) onto xanthan gum with an efficient system, that is, potassium monopersulfate (PMS)/Ag(I) in an aqueous medium. The effects of the concentrations of Ag(I), PMS (KHSO₅), hydrogen ion, xanthan gum, and NVF along with the time and temperature on the graft copolymerization were studied by the determination of the grafting parameters (grafting ratio, add‐on, conversion, grafting efficiency, and homopolymer) and the rate of grafting. The maximum grafting ratio was obtained at a 0.6 g/dm³ concentration of xanthan gum. All the parameters showed an increasing trend with an increasing concentration of peroxymonosulfate, except the homopolymer percentage, which showed a decreasing trend. The grafting ratio, add‐on conversion, grafting efficiency, and rate of grafting increased with the concentration of Ag(I) increasing from 0.8 × 10^?2 to 1.2 × 10^?2 mol/dm³. The optimum time and temperature for the maximum degree of grafting were 90 min and 35°C, respectively. The graft copolymer was characterized with IR spectral analysis, thermogravimetric analysis, and differential calorimetry analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1637–1645, 2006     

Learning iteratively a classifier with the Bayesian Model Averaging Principle

We present a learning algorithm for nominal vector data. It builds a complex classifier by adding iteratively a simple function that modifies the current classifier. In order to limit overtraining problem we focus on a class of such functions for which optimal Bayesian learning is tractable. We investigate a few classes of functions that yield to models that are similar to Na?¨ve Bayes and logistic classification. We report experimental results for a collection of standard data sets that show that our learning algorithm outperforms standard learning of such these standard models.     

Online handwritten shape recognition using segmental hidden Markov models

We investigate a new approach for online handwritten shape recognition. Interesting features of this approach include learning without manual tuning, learning from very few training samples, incremental learning of characters, and adaptation to the user-specific needs. The proposed system can deal with two-dimensional graphical shapes such as Latin and Asian characters, command gestures, symbols, small drawings, and geometric shapes. It can be used as a building block for a series of recognition tasks with many applications     

Groverian Entanglement Measure and Evolution of Entanglement in Search Algorithm for <Emphasis Type="Italic">n</Emphasis>(= 3, 5)-Qubit Systems with Real Coefficients

Evolution of entanglement with the processing of quantum algorithms affects the outcome of the algorithm. Particularly, the performance of Grover’s search algorithm gets worsened if the initial state of the algorithm is an entangled one. The success probability of search can be seen as an operational measure of entanglement. This paper demonstrates an entanglement measure based on the performance of Grover’s search algorithm for three and five qubit systems. We also show that although the overall pattern shows growth of entanglement, its rise to a maximum and then consequent decay, the presence of local fluctuation within each iterative step is likely.      

Compatibility and biodegradability studies of linseed oil epoxy and PVC blends

With the aim to utilize linseed oil epoxy – a product from sustainable resource for the processing of hard polymers, blends of linseed oil epoxy (LOE) with polyvinylchloride (PVC) were prepared for the first time by solution blending of the requisite amounts of the two components in the weight ratios LOE/PVC- 85/15, 65/35, 55/45, 45/55, 35/65, and 15/85 through solution method by mixing in tetrahydrofuran (THF). The miscibility of the two components in solution phase was investigated by relative viscosity, reduced viscosity and density measurements. The blend with 85 wt% of LOE yielded stiff and flexible films with maximum stress of 33 MPa and 216% elongation at break. Biodegradability of these blends has been studied by soil burial test, enzymatic degradation, and hydrolytic degradation in phosphate buffer. The blend LOE/PVC 85/15 showed the highest biodegradation of 68 wt% in 6 months in the soil burial test. The degradability was found to increase with the increase in LOE content in the blend compositions. The potential applications for such sustainable resource based blend films include packaging materials and biodegradable plastic sheets which can be formed into products such as bio-bags.