168 research outputs found

    On the fractional Allee logistic equation in the Caputo sense

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    In the framework of population models, logistic growth and fractional logistic growth has been analyzed. In some situations the so-called Allee effect gives more accurate approximation. In this work, fractional Allee differential equation in the Caputo sense is considered. The solution is obtained by considering formal power series. Numerical computations are presented to compare the truncating series with the classical Allee differential equation.Agencia Estatal de Investigación | Ref. PID2020-113275GB-I00Xunta de Galicia | Ref. Ref. ED431C 2019/0

    Deformaciones provocadas en el tercio apical de los conductos radiculares curvos durante su preparación biomecánica mediante técnicas manuales de impulsión-tracción

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    Los autores hacen un repaso de las deformaciones que se producen en el tercio apical de los conductos radiculares en el curso de la preparación biomecánica, fundamentalmente los 'zips' y 'elbows' de la literatura anglosajona, analizando su causa y repercusiones en la terapia endodóncica. Se estudian también las propuestas para evitar la aparición de las antedichas deformaciones

    On fractional derivatives and primitives of periodic functions

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    We prove that the fractional derivative or the fractional primitive of a -periodic function cannot be a -periodic function, for any period , with the exception of the zero functionThe work of I. Area has been partially supported by the Ministerio de Economía y Competitividad of Spain under Grant MTM2012-38794-C02-01, cofinanced by the European Community fund FEDER. J. J. Nieto also acknowledges partial financial support by the Ministerio de Economía y Competitividad of Spain under Grant MTM2010-15314, cofinanced by the European Community fund FEDER.S

    The number of reduced alignments between two DNA sequences

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    Background In this study we consider DNA sequences as mathematical strings. Total and reduced alignments between two DNA sequences have been considered in the literature to measure their similarity. Results for explicit representations of some alignments have been already obtained. Results We present exact, explicit and computable formulas for the number of different possible alignments between two DNA sequences and a new formula for a class of reduced alignments. Conclusions A unified approach for a wide class of alignments between two DNA sequences has been provided. The formula is computable and, if complemented by software development, will provide a deeper insight into the theory of sequence alignment and give rise to new comparison methods. AMS Subject Classification Primary 92B05, 33C20, secondary 39A14, 65Q30The authors are grateful to Prof. Marko Petkovs̆ek for helpful comments. The work of I. Area has been partially supported by the Ministerio de Economía y Competitividad of Spain under grant MTM2012–38794–C02–01, co-financed by the European Community fund FEDER. J.J. Nieto also acknowledges partial financial support by the Ministerio de Economía y Competitividad of Spain under grant MTM2010–15314, co-financed by the European Community fund FEDERS

    Evaluation of Dentaport ZX and Raypex 6 electronic apex locators: an in vivo study

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    Med Oral Patol Oral Cir Bucal. 2014 Mar 1;19 (2):e202-5. Evaluation of Dentaport ZX and Raypex 6: An in vivo study e202 Journal section: Clinical and Experimental Dentistry Publication Types: Research Evaluation of Dentaport ZX and Raypex 6 electronic apex locators: An in vivo study Saddy Moscoso 1 , Kenneth Pineda 1 , Juan Basilio 1 , Carlos Alvarado 2 , Miguel Roig 2 , Fernando Duran- Sindreu 3 1 MD, Department of Restorative Dentistry and Endodontics, Universitat Internacional de Catalunya, Barcelona, Spain 2 MD, DDS, PhD, Department of Restorative Dentistry and Endodontics, Universitat Internacional de Catalunya, Barcelona, Spain 3 Department of Restorative Dentistry and Endodontics, Universitat Internacional de Catalunya, Barcelona, Spain Correspondence: Dentistry Faculty Universitat Internacional de Catalunya C/Josep Trueta s/n. 08195 Sant Cugat del Vallès, Spain [email protected] Received: 10/02/2013 Accepted: 04/05/2013 Abstract Introduction: Raypex 6 is an electronic apex locator (EAL) that has not yet been tested in vivo. The purpose of this in vivo study was to compare the accuracy of two EALs: the Dentaport ZX and the Raypex 6. Material and Methods: The study involved 36 straight single-rooted teeth. A 10-K file was advanced until the EAL detected the major foramen. The file was fixed in a replaceable pattern of light-cured composite. The apical part of each canal was trimmed to expose the file tip. The distances from the file tips to the major foramen were measured. Results: Wilcoxon's signed Rank test found no significant differences between the Dentaport ZX and Raypex 6 in terms of their abilities to detect the major foramen (P = .52) The Dentaport ZX was accurate 82.35% of the time to ± 0.5 mm and 97.05% of the time to ± 1 mm, whereas the Raypex 6 was accurate 88.22% of the time to ± 0.5 mm and 100% of the time to ± 1 mm. Conclusions: No statistically significant differences were observed between the performance of the Dentaport ZX and Raypex 6 EALs under the in vivo clinical conditions used in this study

    Mathematical modeling of COVID-19 transmission dynamics with a case study of Wuhan

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    We propose a compartmental mathematical model for the spread of the COVID-19 disease with special focus on the transmissibility of super-spreaders individuals. We compute the basic reproduction number threshold, we study the local stability of the disease free equilibrium in terms of the basic reproduction number, and we investigate the sensitivity of the model with respect to the variation of each one of its parameters. Numerical simulations show the suitability of the proposed COVID-19 model for the outbreak that occurred in Wuhan, China.Agencia Estatal de Investigación | Ref. MTM2016-75140-PFundação para a Ciência e a Tecnologia | Ref. UIDB/04106/2020Xunta de Galicia | Ref. ED431C 2019/0

    On the Weak Lefcchetz property for artinian Gorenstein algebras

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    We study the problem of whether an arbitrary codimension three graded artinian Gorenstein algebra has the Weak Lefschetz Property. We reduce this problem to checking whether it holds for all compressed Gorenstein algebras of odd socle degree. In the first open case, namely Hilbert function , we give a complete answer in every characteristic by translating the problem to one of studying geometric aspects of certain morphisms from to , and Hesse configurations in

    Study of coliforms and Clostridium bacteria inactivation in wastewaters by a pilot photolysis process and by the maturation lagoons of a low-cost nature-based WWTP

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    [EN] The inactivation processes of coliform bacteria (total and fecal) and sulphito-reducing Clostridium bacteria (vegetative species and spores) in water maturation lagoon of a low-cost nature-based wastewater treatment plant using constructed wetlands and through processes of photolysis in a pilot photoreactor have been comparatively studied. The diferent inactivation mechanisms by photolysis of these bacteria have been studied following the criteria of diferent statistical and kinetic models. Clostridium disinfection treatments ft models in which two types of bacteria populations coexist, one sensitive (vegetative species) and the other (spores) resistant to the treatment, the sensitive one (94%) with an inactivation rate of k=0.24±0.07 min−1 and the resistant one (6%) with k=0.11±0.05 min−1. Total coliform photolytic disinfection also shows two populations with diferent physiological state. The time required to reduce the frst logarithmic decimal cycle of the diferent types of bacteria (physiological states) are δ1=4.2±0.9 and δ2=8.3±1.1 min, respectively. For fecal coliform photolytic disinfection, only bacteria population, with k=1.15±0.19 min−1, is found. The results obtained confrm the photolytic disinfection processes and maturation lagoon are efective systems for Clostridia bacteria removal after water treatment by nature-based systems. Total removal of coliform bacteria is not achieved by maturation lagoons, but their reduction is signifcant using low doses of cumulative radiation.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE
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