A Comparison of Word- and Sense-Based Text Categorization Using Several Classification Algorithms

Most of the text categorization algorithms in the literature represent documents as collections of words. An alternative which has not been sufficiently explored is the use of word meanings, also known as senses. In this paper, using several algorithms, we compare the categorization accuracy of classifiers based on words to that of classifiers based on senses. The document collection on which this comparison takes place is a subset of the annotated Brown Corpus semantic concordance. A series of experiments indicates that the use of senses does not result in any significant categorization improvement.     

Tocopherol and tocotrienol homologs in parenteral lipid emulsions

Parenteral lipid emulsions, which are made of oils from plant and fish sources, contain different types of tocopherols and tocotrienols (vitamin E homologs). The amount and types of vitamin E homologs in various lipid emulsions vary considerably and are not completely known. The objective of this analysis was to develop a quantitative method to determine levels of all vitamin E homologs in various lipid emulsions. An HPLC system was used to measure vitamin E homologs using a Pinnacle DB Silica normal phase column and an isocratic, n‐hexane:1,4 dioxane (98:2) mobile phase. An optimized protocol was used to report vitamin E homolog concentrations in soybean oil‐based (Intralipid®, Ivelip®, Lipofundin^® N, Liposyn^® III, and Liposyn^® II), medium‐ and long‐chain fatty acid‐based (Lipofundin^® , MCT and Structolipid®), olive oil‐based (ClinOleic® ), and fish oil‐based (Omegaven®) and mixture of these oils‐based (SMOFlipid®, Lipidem®) commercial parenteral lipid emulsions. Total content of all vitamin E homologs varied greatly between different emulsions, ranging from 57.9 to 383.9 µg/mL. Tocopherols (α, β, γ, δ) were the predominant vitamin E homologs for all emulsions, with tocotrienol content < 0.3%. In all of the soybean emulsions, except for Lipofundin® N, the predominant vitamin E homolog was γ‐tocopherol, which ranged from 57–156 µg/mL. ClinOleic® predominantly contained α‐tocopherol (32 µg/mL), whereas α‐tocopherol content in Omegaven® was higher than most of the other lipid emulsions (230 µg/mL). Practical applications: The information on the types and quantity of vitamin E homologs in various lipid emulsions will be extremely useful to physicians and healthcare personnel in selecting appropriate lipid emulsions that are exclusively used in patients with inadequate gastrointestinal function, including hospitalized and critically ill patients. Some emulsions may require vitamin E supplementation in order to meet minimal human requirements. Vitamin E homologs (tocopherols and tocotrienols) contain a chromanol ring and a hydrophobic side chain.     

Concomitant processes in the redox switching of polyaniline

It is shown for the first time that the redox switching of polyaniline (PANI) under voltammetric conditions is accompanied by the following processes: oxidation of PANI by atmospheric oxygen in the range of low potentials (E < 0.2 V); reduction with addition of aniline (post-polymerization) at E > 0.2(5) V, which in the range 0.2(5) < E < 0.5 V compensates entirely for the oxidation over the timescale of the cyclic voltammogram. These processes determine: (a) the existence of the emeraldine (conducting) state in a potential window (instead of at a defined potential); (b) the fundamental asymmetry in the redox behaviour of PANI; (c) the difference in the rates of the oxidation and reduction transients and (d) the dependence of the electrochemical activity of PANI on the pH of the medium.     

Copolymers of aniline and o‐methoxyaniline. II. Thermoanalytical studies

A study on the thermal stability, thermodynamical parameters, especially relaxation transition temperature (T_g), and their change upon irreversible reactions (crosslinking, postpolymerization, decomposition, etc.) taking place on heating of the undoped homo‐ and copolymers of aniline and o‐methoxyaniline was performed by using differential scanning calorimetry. It was found that polyaniline and its oligomers might be responsible for the postpolymerization process observed on heating thermograms of the polymers in their emeraldine base form. It can be stated that the proceeding of this process appears to be a reason for the higher thermal stability of polyaniline when compared with poly(o‐methoxyaniline). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2729–2734, 2007     

Correlation of Yield Strength and Tensile Strength with Hardness for Steels

Hardness values as well as yield and tensile strength values were compiled for over 150 nonaustenitic, hypoeutectoid steels having a wide range of compositions and a variety of microstructures. The microstructures include ferrite, pearlite, martensite, bainite, and complex multiphase structures. The yield strength of the steels ranged from approximately 300 MPa to over 1700 MPa. Tensile strength varied over the range of 450-2350 MPa. Regression analysis was used to determine the correlation of the yield strength and the tensile strength to the diamond pyramid hardness values for these steels. Both the yield strength and tensile strength of the steels exhibited a linear correlation with the hardness over the entire range of strength values. Empirical relationships are provided that enable the estimation of strength from a bulk hardness measurement. A weak effect of strain-hardening potential on the hardness-yield strength relationship was also observed.     

Resource Management Based on Dynamic Users Association for Future Heterogeneous Telecommunication Access Infrastructures

In this paper an approach for resource management for Heterogeneous Networks (HetNets) based on the dynamic association of users in sets is proposed. The approach is based on the consideration that in a telecommunication network every access point has the property of limited performance, capacity and service potential. Through the definition of two generalized parameters of the servicing cell a characteristic model of the servicing properties of a HetNet access point is developed. An optimization task is defined for a resource management approach with the goal of “providing user service with the required quality of Service while minimizing servicing costs”. The task is solved via the introduction of a modified ADD/DROP heuristic algorithm. A comparison with two other heuristic algorithms is performed showing some of the advantages of the proposed algorithm such as its low computational complexity, fast convergence and effectiveness of the heuristic procedure. A sample application for transmission power control is presented.     

Polyaniline dispersions. 3. Influence of the polymerization conditions

Several series of polyaniline dispersions were prepared by oxidative polymerization of aniline in aqueous medium. Ammonium persulfate was used as an oxidizing agent and poly(vinyl alcohol) as a steric stabilizer of dispersions. The amount of dispersion particles their size and uniformity and the fraction of the steric stabilizer attached to the particles were determined in dependence on the concentration of the individual components and on temperature. The properties of resulting dispersions are controlled mainly by the concentration of the oxidizing agent and by the polyaniline/stabilizer ratio.     

Effect of the talc filler content on the mechanical properties of polypropylene composites

This research examines the effect of a microsize/nanosize talc filler on the physicochemical and mechanical properties of filled polypropylene (108MF10 and 33MBTU from Saudi Basic Industries Corp. and HE125MO grade from Borealis) composite matrices. A range of mechanical properties were measured [tensile properties, bending properties, fracture toughness, notched impact strength (at the ambient temperature and ?20°C), strain at break, and impact strength] along with microhardness testing and thermal stability testing from 40 to 600°C as measured by differential thermal analysis and thermogravimetric analysis. Increasing filler content lead to an increase in the mechanical strength of the composite material with a simultaneous decrease in the fracture toughness. The observed increase in tensile strength ranged from 15 to 25% (the maximum tensile strength at break was found to be 22 MPa). The increase in mechanical strength simultaneously led to a higher brittleness, which was reflected in a decrease in the mean impact strength from the initial 18 kJ/m² (for the virgin polypropylene sample) to 14 kJ/m², that is, a 23% decrease. A similar dependency was also obtained for the samples conditioned at ?20°C (a decrease of 12.5%). With increasing degree of filling of the talc–polypropylene composite matrix, the thermooxidative stability increased; the highest magnitude was obtained for the 20 wt % sample (decomposition temperature = 482°C, cf. 392°C for the virgin polymer). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008