196,113 research outputs found
Simulation of harmonic oscillators on the lattice
No full text[EN] This work deals with the simulation of a two¿dimensional ideal lattice having simple tetragonal geometry. The harmonic character of the oscillators give rise to a system of second¿order linear differential equations, which can be recast into matrix form. The explicit solutions which govern the dynamics of this system can be expressed in terms of matrix trigonometric functions. For the derivation we employ the Lagrangian formalism to determine the correct solutions, which extremize the underlying action of the system. In the numerical evaluation we develop diverse state¿of¿the¿art algorithms which efficiently tackle equations with matrix sine and cosine functions. For this purpose, we introduce two special series related to trigonometric functions. They provide approximate solutions of the system through a suitable combination. For the final computation an algorithm based on Taylor expansion with forward and backward error analysis for computing those series had to be devised. We also implement several MATLAB programs which simulate and visualize the two¿dimensional lattice and check its energy conservation.This work has been supported by the Spanish Ministerio de Economia y Competitividad, the European Regional Development Fund (ERDF) under grant TIN2017-89314-P, and the Programa de Apoyo a la Investigacion y Desarrollo 2018 (PAID-06-18) of the Universitat Politecnica de Valencia under grant SP20180016.Tung, MM.; Ibáñez González, JJ.; Defez Candel, E.; Sastre, J. (2020). Simulation of Harmonic Oscillators on the Lattice. Mathematical Methods in the Applied Sciences. 43(14):8237-8252. https://doi.org/10.1002/mma.6510S823782524314Dehghan, M., & Hajarian, M. (2009). Determination of a matrix function using the divided difference method of Newton and the interpolation technique of Hermite. Journal of Computational and Applied Mathematics, 231(1), 67-81. doi:10.1016/j.cam.2009.01.021Dehghan, M., & Hajarian, M. (2010). Computing matrix functions using mixed interpolation methods. Mathematical and Computer Modelling, 52(5-6), 826-836. doi:10.1016/j.mcm.2010.05.013Kazem, S., & Dehghan, M. (2017). Application of finite difference method of lines on the heat equation. Numerical Methods for Partial Differential Equations, 34(2), 626-660. doi:10.1002/num.22218Kazem, S., & Dehghan, M. (2018). Semi-analytical solution for time-fractional diffusion equation based on finite difference method of lines (MOL). Engineering with Computers, 35(1), 229-241. doi:10.1007/s00366-018-0595-5Paterson, M. S., & Stockmeyer, L. J. (1973). On the Number of Nonscalar Multiplications Necessary to Evaluate Polynomials. SIAM Journal on Computing, 2(1), 60-66. doi:10.1137/0202007Sastre, J., Ibáñez, J., Defez, E., & Ruiz, P. (2011). Efficient orthogonal matrix polynomial based method for computing matrix exponential. Applied Mathematics and Computation, 217(14), 6451-6463. doi:10.1016/j.amc.2011.01.004Higham, N. J. (2008). Functions of Matrices. doi:10.1137/1.9780898717778Sastre, J., Ibáñez, J., Defez, E., & Ruiz, P. (2011). Accurate matrix exponential computation to solve coupled differential models in engineering. Mathematical and Computer Modelling, 54(7-8), 1835-1840. doi:10.1016/j.mcm.2010.12.049Serbin, S. M., & Blalock, S. A. (1980). An Algorithm for Computing the Matrix Cosine. SIAM Journal on Scientific and Statistical Computing, 1(2), 198-204. doi:10.1137/0901013Ruiz, P., Sastre, J., Ibáñez, J., & Defez, E. (2016). High performance computing of the matrix exponential. Journal of Computational and Applied Mathematics, 291, 370-379. doi:10.1016/j.cam.2015.04.001Higham, N. J. (1988). FORTRAN codes for estimating the one-norm of a real or complex matrix, with applications to condition estimation. ACM Transactions on Mathematical Software, 14(4), 381-396. doi:10.1145/50063.21438
Regulation of glutamine synthetase isoenzymes in Rhizobium leguminosarum biovar viciae.
No full textAmmonia assimilation in Rhizobium leguminosarum biovar viceae strain RCRlOO 1 (hereafter
called R. leguminosarum) appears to take place only through the glutamine synthetase/glutamate
synthase pathway since (a) no glutamate dehydrogenase was detected in crude extracts of
bacteria grown in different nitrogen sources, and (b) the growth rate on glutamine as a nitrogen
source was faster than that observed on NH4Cl. In contrast to reports for other Rhizobium
species, R. leguminosarum can definitely utilize NH4C1 for growth. R. Ieguminosarum contains
two glutamine synthetase isoenzymes, GSI and GSII, which can be detected in the presence of
each other by differential heat stability, or separated by affinity chromatography or
immunoabsorption with an antiserum raised against pure GSI. GSII does not cross-react with
an anti-GSI antiserum. GSI was shown to be reversibly adenylylated and it was also shown that
adenylylation inhibits the biosynthetic activity of this enzyme, in a similar way to that reported
for Escherichia coli glutamine synthetase and in contrast to that observed for glutamine
synthetase of Rhizobium sp. strain ANU289. The apparent adenylylation level in different
growth conditions changes from 21% to 99%, indicating a physiological role of this posttranslational
modification in the in vivo regulation of GSI activity. The intracellular
concentration of GSI varies very little when R . leguminosarum is grown on different nitrogen
sources (twofold when measured by the transferase assay, or fourfold when measured by
ELISA). In addition, the concentration of mRNA specific for GSI in different nitrogen sources
does not show appreciable differences. The intracellular concentration of GSII varies from a
specific activity value higher than 1000 when R. leguminosarum is grown on glutamate or nitrate,
to an undetectable level when grown on NH4C1. When NH4C1 is added to a culture growing in
glutamate, GSII activity is rapidly diluted out, suggesting a post-translational mechanism of
enzyme inhibition or inactivation. Chloramphenicol prevents the disappe
Evaluation methods on usability of m-learning environments
No full text[EN] Nowadays there are different evaluation methods
focused in the assessment of the usability of telematic methods.
The assessment of 3rd generation web environments evaluates
the effectiveness and usability of application with regard to the
user needs. Wireless usability and, specifically in mobile phones,
is concentrated in the validation of the features and tools
management using conventional interactive environments. There
is not a specific and suitable criterion to evaluate created
environments and m-learning platforms, where the restricted
and sequential representation is a fundamental aspect to be
considered. The present paper exposes the importance of the
conventional usability methods to verify both: the employed
contents in wireless formats, and the possible interfaces from the
conception phases, to the validations of the platform with such
characteristics. The development of usability adapted inspection
could be complemented with the Remote¿s techniques of usability
testing, which are being carried out these days in the mobile
devices field and which pointed out the need to apply common
criteria in the validation of non-located learning scenarios.Magal Royo, T.; Peris Fajarnes, G.; Tortajada Montañana, I.; Defez Garcia, B. (2007). Evaluation methods on usability of m-learning environments. IEEE multidisciplinary Engineering Education Magazine. 2(2):34-37. https://riunet.upv.es/handle/10251/109807S34372
Preliminary Results on Biotization of Encapsulated Vitro-Derived Propagules of Carrizo Citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf].
No full textComputing Matrix Trigonometric Functions with GPUs through Matlab
No full text[EN] This paper presents an implementation of one of the most up-to-day algorithms proposed to compute the matrix trigonometric functions sine and cosine. The method used is based on Taylor series approximations which intensively uses matrix multiplications. To accelerate matrix products, our application can use from one to four NVIDIA GPUs by using the NVIDIA cublas and cublasXt libraries. The application, implemented in C++, can be used from the Matlab command line thanks to the mex files provided. We experimentally assess our implementation in modern and very high-performance NVIDIA GPUs.This work has been supported by Spanish Ministerio de Economia y Competitividad and the European Regional Development Fund (ERDF) Grants TIN2014-59294-P and TEC2015-67387-C4-1-RAlonso-Jordá, P.; Peinado Pinilla, J.; Ibáñez González, JJ.; Sastre, J.; Defez Candel, E. (2019). Computing Matrix Trigonometric Functions with GPUs through Matlab. The Journal of Supercomputing. 75(3):1227-1240. https://doi.org/10.1007/s11227-018-2354-1S12271240753Serbin SM (1979) Rational approximations of trigonometric matrices with application to second-order systems of differential equations. Appl Math Comput 5(1):75–92Serbin Steven M, Blalock Sybil A (1980) An algorithm for computing the matrix cosine. SIAM J Sci Stat Comput 1(2):198–204Hargreaves GI, Higham NJ (2005) Efficient algorithms for the matrix cosine and sine. Numer Algorithms 40:383–400Al-Mohy Awad H, Higham Nicholas J (2009) A new scaling and squaring algorithm for the matrix exponential. SIAM J Matrix Anal Appl 31(3):970–989Defez E, Sastre J, Ibáñez Javier J, Ruiz Pedro A (2011) Computing matrix functions arising in engineering models with orthogonal matrix polynomials. Math Comput Model 57:1738–1743Sastre J, Ibáñez J, Ruiz P, Defez E (2013) Efficient computation of the matrix cosine. Appl Math Comput 219:7575–7585Al-Mohy Awad H, Higham Nicholas J, Relton Samuel D (2015) New algorithms for computing the matrix sine and cosine separately or simultaneously. SIAM J Sci Comput 37(1):A456–A487Alonso P, Ibáñez J, Sastre J, Peinado J, Defez E (2017) Efficient and accurate algorithms for computing matrix trigonometric functions. J Comput Appl Math 309(1):325–332CUBLAS library (2017) http://docs.nvidia.com/cuda/cublas/index.html . Accessed May 2017Alonso Jordá P, Boratto M, Peinado Pinilla J, Ibáñez González JJ, Sastre Martínez J (2014) On the evaluation of matrix polynomials using several GPGPUs. Universitat Politècnica de València, 2014. http://hdl.handle.net/10251/39615 . Accessed Sept 2017Boratto Murilo, Alonso Pedro, Giménez Domingo, Lastovetsky Alexey L (2017) Automatic tuning to performance modelling of matrix polynomials on multicore and multi-gpu systems. J Supercomput 73(1):227–239Alonso P, Peinado J, Ibáñez J, Sastre J, Defez E (2017) A fast implementation of matrix trigonometric functions sine and cosine. In: Proceedings of the 17th International Conference on Computational and Mathematical Methods in Science and Engineering (CMMSE 2017), pp 51–55, Costa Ballena, Rota, Cadiz (Spain), July 4th–8thSastre Jorge, Ibáñez Javier, Alonso Pedro, Peinado Jesús, Defez Emilio (2017) Two algorithms for computing the matrix cosine function. Appl Math Comput 312:66–77Paterson Michael S, Stockmeyer Larry J (1973) On the number of nonscalar multiplications necessary to evaluate polynomials. SIAM J Comput 2(1):60–66Higham Nicholas J (2008) Functions of matrices: theory and computation. SIAM, PhiladelphiaSastre J, Ibáñez Javier J, Defez E, Ruiz Pedro A (2011) Efficient orthogonal matrix polynomial based method for computing matrix exponential. Appl Math Comput 217:6451–6463Sastre J, Ibáñez Javier J, Defez E, Ruiz Pedro A (2015) Efficient scaling-squaring Taylor method for computing matrix exponential. SIAM J Sci Comput 37(1):A439–455Higham NJ, Tisseur F (2000) A block algorithm for matrix 1-norm estimation, with an application to 1-norm pseudospectra. SIAM J Matrix Anal Appl 21:1185–1201Demmel JW (1987) A counterexample for two conjectures about stability. IEEE Trans Autom Control 32:340–343Wright Thomas G (2002) EigTool library. http://www.comlab.ox.ac.uk/pseudospectra/eigtool/ . Accessed May 201
Preliminary Results on Biotization of Encapsulated Vitro-Derived Propagules of Carrizo Citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf].
No full textThe encapsulation technology represents a new tool to integrate
micropropagation into the nursery activity. It allows combining the advantages of
zygotic or gamic seeds with those of micropropagation. The synthetic or artificial
seeds have been defined as “artificially encapsulated somatic embryos, shoots or
other tissues which can be used for sowing under in vitro or ex vitro conditions”.
This will be a powerful propagation tool in the nurseryman hands, if the levels of the
synthetic seeds conversion can be increased also in the nurseries, without the asepsis
of in vitro laboratories and with the presence of many parasitic microorganisms, like
bacteria and fungi, responsible for contamination and/or for trophic competition.
This research was carried out in order to apply biotization into the synthetic seed
technology of Carrizo citrange [C. sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.],
one most extensively used citrus rootstock, because of its resistance to the Citrus
tristeza virus (CTV). With this goal, preliminary experiments to set up protocols for
biotization, through the introduction of Plant Growth Promoting Bacteria (PGPB)
into calcium alginate capsules of Carrizo citrange in vitro-derived microcuttings,
were carried out, in order to protect the plantlets from abiotic and biotic factors and
to promote their growth during the first stages of development. Specifically, the
Sinorhizobium meliloti wild type strain 1021 and its derivative RD64, that
synthesizes 80-fold more IAA as compared to the wild type strain, was used to
evaluate their performance in inducing rooting of encapsulated microcuttings
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Use of nodulation pattern, stress tolerance, nodC gene amplification, RAPD-PCR and RFLP-16S rDNA analysis to discriminate genotypes of Rhizobium leguminosarum biovar viciae
No full textTwenty-seven new Rhizobium isolates were obtained from root nodules of wild and crop legumes belonging to the genera Vicia, Lathyrus and Pisum from different agroecological areas in central and southern Italy. A polyphasic approach including phenotypic and genotypic techniques was used to study their diversity and their relationships with other biovars and species of rhizobia. Analysis of symbiotic properties and stress tolerance tests revealed that wild isolates showed a wide spectrum of nodulation and a marked variation in stress tolerance compared with reference strains tested in this study. All rhizobial isolates (except for the isolate CG4 from Galega officinalis) were presumptively identified as Rhizobium leguminosarum biovar viciae both by their symbiotic properties and the specific amplification of the nodC gene. In particular, we found that the nodC gene could be used as a diagnostic molecular marker for strains belonging to the bv. viciae. RFLP-PCR 16S rDNA analysis confirms these results, with the exception of two strains that showed different RFLP-genotypes from those of the reference strains of R. leguminosarum bv. viciae. Analysis of intraspecies relationship among strains by using the RAPD-PCR technique showed a high level of genetic polymorphism, grouping our isolates and reference strains into six different major clusters with a similarity level of 20%. Data from seven parameters of phenotypic and genotypic analyses were evaluated by using principal component analysis which indicated the differences among strains and allowed them to be divided into seven different groups
- …
