1,721,002 research outputs found
Some results on a new refinable class suitable for fractional differential problems
Full text linkIn recent years, we found that some multiscale methods applied to fractional differential
problems, are easy and efficient to implement, when we use some fractional refinable functions
introduced in the literature. In fact, these functions not only generate a multiresolution on R, but
also have fractional (non-integer) derivative satisfying a very convenient recursive relation. For this
reason, in this paper, we describe this class of refinable functions and focus our attention on their
approximating properties
A collocation method in spline spaces for the solution of linear fractional dynamical systems
Full text linkWe use a collocation method in refinable spline spaces to solve a linear dynamical system having fractional derivative in time. The method takes advantage of an explicit differentiation rule for the B-spline basis that allows us to efficiently evaluate the collocation matrices appearing in the method. We prove the convergence of the method and show some numerical results
Spectrophotometric Determination Of Hexamethylenetetramine (hmt) In Pharmaceutical Preparations Using Chromotropic Acid And Microwave Oven [determinação Espectrofotométrica De Hexametilenotetramina (hmt) Em Medicamentos, Utilizando ácido Cromotrópico E Forno De Micro-ondas]
No full textThis paper proposes a methodology for spectrophotometric determination of hexamethylenetetramine (HMT) by using chromotropic acid in a phosphoric acid media employing a domestic microwave oven as a source of heating. The reddish-purple soluble product is quantitatively formed after 30 s of irradiation and obeys the Beeŕs law in the range between 0.1-1.2 mg L-1 HMT (r = 0.99925). The method was applied successfully in commercial pharmaceutical preparations containing dyes in their composition. The results showed that the method proposed is feasible for simplicity, speed, low cost, precision and accuracy when compared with United States Pharmacopeia official method.32924582463Nickel, J.C., (2005) J. Urol., 173, p. 21Kaszycki, P., Koloczek, H., (2002) Biodegradation, 13, p. 91Kirk, R.E., Othmer, D.F., Encyclopedia of chemical technology (1951) The Interscience Encyclopedia, , New YorkSharma, S.P., Lahiri, S.C., (2008) J. Indian Chem. Soc., 85, p. 273Turi, E.A., (1981) Thermal Caracterization of Polymeric Materials, , Academic Press: OrlandoMadsen, G.L., Jaselkis, B., (1992) Analyst, 117, p. 1785Tomcik, P., Mrafkova, L., Bustin, D., (2003) Microchim. Acta, 141, p. 69Dzyadevych, S.V., Arkhypova, V.N., Korpan, Y.I., El'skaya, A.V., Soldatkin, A.P., Jaffrezic-Renault, N., Martelet, C., (2001) Anal. Chim. Acta, 445, p. 47Korpan, Y.I., Gonchar, M.V., Sibirny, A.A., Martelet, C., El'skaya, A.V., Gibson, T.D., Soldatkin, A.P., (2000) Biosens. Bioelectron., 15, p. 77Burini, G., Coli, R., (2004) Anal. Chim. Acta, 511, p. 155Pérez-Ruiz, T., Martínez-Lozano, C., Fenoll, T.V., (2003) J. Anal. Bioanal. Chem., 375, p. 661Pinheiro, H.L.C., Andrade, V., Pereira, P.A.P., Andrade, J.B., (2004) Microchem. J., 78Reche, F., Garrigós, M.C., Sánchez, A., Jiménez, A., (2000) J. Chromatogr., A, 896, p. 51Kato, S., Burke, P.J., Fenick, D.J., Taatjes, D.J., Bierbaum, V.M., Koch, T.H., (2000) Chem. Res. Toxicol., 13, p. 509Kato, S., Burke, P.J., Koch, T.H., Bierbaum, V.M., (2001) Anal. Chem., 73Rivero, R.T., Topiwala, V., (2004) J. Chromatogr., A, 1029, p. 217http://www.cdc.gov/niosh/nmam/pdfs/3500.pdf, acessada em Setembro 2009Bosque-Sendra, J.M., Pescarolo, S., Cuadros-Rodríguez, L., García-Campaña, A.M., Almansa-López, E.M., (2001) Freseniuś J. Anal. Chem., 369, p. 715Ross, P.F., Draayer, H., Itoh, O., (2002) Biologicals, 30, p. 37Zhang, Z.Q., Yan, H.T., Yuc, X.F., (2004) Microchim. Acta, 146, p. 259Sibirny, V.A., Gonchar, M.V., Grabek-Lejko, D., Pavlishko, H.M., Csoregi, E., Sibirny, A.A., (2008) Int. J. Environ. Anal. Chem., 88, p. 289Feigl, F., (1956) Spot Tests in Organic Analysis, , 5th ed. Elsevier: AmsterdamGeorghiou, P.E., Ho, C.K., (1989) Can. J. Chem., 67Fagnani, E., Melios, C.B., Pezza, L., Pezza, H.R., (2003) Talanta, 60, p. 171Gigante, A.C., Gotardo, M.A., Tognolli, J.O., Pezza, L., Pezza, H.R., (2004) Microchem. J., 77, p. 47Tininis, A.G., Santini, A.O., Fagnani, E., Melios, C.B., Pezza, L., Pezza, H.R., (2001) Eclet. Quim., 26, p. 175Kingston, H.M., Jassie, L.B., (1988) Introduction to Microwave Sample Preparation - Theory and Practice, , ACS Professional Reference Books: WashingtonGigante, A.C., Pezza, L., Pezza, H.R., (2002) Eclet. Quim., 27, p. 223http://www.anvisa.gov.br/monitora/cmed/legis/comunicados/ lista_conformidade.pdf, acessada em Setembro 2009(1995) The United States Pharmacopeia - The National Formulary, , United States Pharmacopeial Convention, 23rd ed. U.S. Pharmacopeia: RockvilleMiller, J.N., Miller, J.C., (2000) Statistics and Chemometrics for Analytical Chemistry, , 4th ed. Pearson Education: EssexBalasubramanian, M., Thennarassu, S., Sudhakaran, T., Perumal, P.T., (2003) Biol. Pharm. Bull., 26, p. 1211Pavitrapok, C., Williams, D.A., (2006) J. Pharm. Biomed. Anal., 40, p. 1243(2000) Data Analysis and Technical Graphics, , OriginLab CorporationORIGIN® 6.1, Northampton, Estados Unido
A fractional spline collocation-Galerkin method for the time-fractional diffusion equation
Full text linkThe aim of this paper is to numerically solve a diffusion differential problem having time derivative of fractional order. To this end we propose a collocation-Galerkin method that uses the fractional splines as approximating functions. The main advantage is in that the derivatives of integer and fractional order of the fractional splines can be expressed in a closed form that involves just the generalized finite difference operator. This allows us to construct an accurate and efficient numerical method. Several numerical tests showing the effectiveness of the proposed method are presented
Quasi-interpolant operators and the solution of fractional differential problems
No full textNowadays, fractional differential equations are a well established tool to model phenomena from the real world. Since the analytical solution is rarely available, there is a great effort in constructing efficient numerical methods for their solution. In this paper we are interested in solving boundary value problems having space derivative of fractional order. To this end, we present a collocation method in which the solution of the fractional problem is approximated by a spline quasi-interpolant operator. This allows us to construct the numerical solution in an easy way. We show through some numerical tests that the proposed method is efficient and accurate
Effect of bunch thinning on yield and quality of Sylvoz trained cv. Prosecco (Vitis vinifera L.)
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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