12,519 research outputs found
Importancia de una correcta fertilizaciĂłn de zinc en el cultivo de lino.
Almendros, P.; Alvarez, J.M.; Gonzalez, D
The Cauchy problem for a tenth-order thin film equation II. Oscillatory source-type and fundamental similarity solutions
Fundamental global similarity solutions of the standard form
u_\g(x,t)=t^{-\a_\g} f_\g(y), with the rescaled variable y= x/{t^{\b_\g}},
\b_\g= \frac {1-n \a_\g}{10}, where \a_\g>0 are real nonlinear eigenvalues (\g
is a multiindex in R^N) of the tenth-order thin film equation (TFE-10) u_{t} =
\nabla \cdot(|u|^{n} \n \D^4 u) in R^N \times R_+, n>0, are studied. The
present paper continues the study began by the authors in the previous paper
P. Alvarez-Caudevilla, J.D.Evans, and V.A. Galaktionov, The Cauchy problem
for a tenth-order thin film equation I. Bifurcation of self-similar oscillatory
fundamental solutions, Mediterranean Journal of Mathematics, No. 4, Vol. 10
(2013), 1759-1790.
Thus, the following questions are also under scrutiny:
(I) Further study of the limit n \to 0, where the behaviour of finite
interfaces and solutions as y \to infinity are described. In particular, for
N=1, the interfaces are shown to diverge as follows: |x_0(t)| \sim 10 \left(
\frac{1}{n}\sec\left( \frac{4\pi}{9} \right) \right)^{\frac 9{10}} t^{\frac
1{10}} \to \infty as n \to 0^+.
(II) For a fixed n \in (0, \frac 98), oscillatory structures of solutions
near interfaces.
(III) Again, for a fixed n \in (0, \frac 98), global structures of some
nonlinear eigenfunctions \{f_\g\}_{|\g| \ge 0} by a combination of numerical
and analytical methods
Comparison of the extended linear sigma model and chiral perturbation theory
The pion-nucleon scattering amplitudes are calculated in tree approximation
with the use of the extended linear sigma model (ELSM) as well as heavy baryon
chiral perturbation theory (HBPT), and the non-relativistic forms of the
ELSM results are compared with those of HBPT. We find that the amplitudes
obtained in ELSM do not agree with those derived from the more fundamental
effective approach, HBPT.Comment: 7 page
[n]cycloparaphenylenes with charges
Oligophenylenes (polyphenylenes) are constituted by an array of conjugated benzenes where inter-ring electron delocalization tends to extend over the whole chain (linear conjugation) being intrinsically limited, among other factors, by terminal effects. Alternatively, cyclic conjugation is envisaged as the unlimited free-boundary versionofconjugation which will impact the structure of molecules in rather unknown ways. The cyclic version of oligophenylenes, cycloparaphenylenes ([n]CPPs with n the number of phenyl rings) were first synthesized in 2008 by Beztozzi and Jasti.1 Today the whole [n]CPP series from [5]CPP to [18]CPP has been prepared. [n]CPPs represent ideal models to investigate new insights of the electronic structure of molecules and cyclic conjugation when electrons or charges circulate in a closed circuit without boundaries. Radical cations and dications of [n]CPP from n=5 to n=12 have been prepared and studied by Raman spectroscopy.2 Small [n]CPP dications own their stability to the closed-shell electronic configuration imposed by cyclic conjugation. However, in large [n]CPP dications cyclic conjugation is minimal and these divalent species form open-shell biradicals. The Raman spectra reflect the effect of cyclic conjugation in competition with cyclic strain and biradicaloid aromatic stabilization. Cyclic conjugation provokes the existence of a turning point or V-shape behavior of the frequencies of the G bands as a function of n. In this communication we will show the vibrational spectroscopic fingerprint of this rare form of conjugation.
[1] R. Jasti, J. Bhattacharjee, J. B. Neaton, C. R. Bertozzi, âSynthesis, Characterization, and Theory of [9]-, [12]-, and [18]Cycloparaphenylene: Carbon Nanohoop Structuresâ, J. Am. Chem. Soc. 130 (2008), 17646â17647.
[2] M. P. Alvarez, P. M. Burrezo, M. Kertesz, T. Iwamoto, S. Yamago, J. Xia, R. Jasti, J. T. L. Navarrete, M. Taravillo, V. G. Baonza, J. Casado, âProperties of Sizeable [n]CycloParaPhenylenes As Molecular Models of Single-Wall Carbon Nanotubes By Raman Spectroscopy: Structural and Electron-Transfer Responses Under Mechanical Stressâ, Angew. Chem. Int. Ed. 53, (2014), 7033â7037.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
Catalytic activity of iridium NHC complexes covalently bonded to carbon nanotubes and graphene oxide
Trabajo presentado a la Annual World Conference on Carbon, celebrada en Dresden (Alemania) del 12 al 17 de julio de 2015.Carbon nanotubes and graphene have been extensively applied as proactive supports to generate heterogeneous catalysts. Both exhibit a carbon structure composed by carbon atoms with sp2 hybridization and both are used in similar applications, as in catalysis. However, the role of each particular substrate, determined by its structural peculiarities, can be differentvshould be studied for each particular catalytic reaction and in their structure.The aim of this work is to study the differences between oxidized carbon nanotubes (CNT) and graphene oxides (GO) as proactive supports of iridium Nheterocyclic carbene (NHC) catalyst. The effect of their inherent structure in the
catalytic activity in hydrogen transfer reactions was studied in detail.The authors thank MINECO/MECD (Projects CONSOLIDER INGENIO 2010 CSD2009-00050, CTQ 2010-15221, RamĂłn y Cajal contract of P. Alvarez and fellowship of M. Blanco) and the DiputaciĂłn General de AragĂłn (E07) for their financial support.Peer Reviewe
Deep Learning Meets Cognitive Radio: Predicting Future Steps
Learning the channel occupancy patterns to reuse
the underutilised spectrum frequencies without interfering with
the incumbent is a promising approach to overcome the spectrum
limitations. In this work we proposed a Deep Learning (DL)
approach to learn the channel occupancy model and predict its
availability in the next time slots. Our results show that the
proposed DL approach outperforms existing works by 5%. We
also show that our proposed DL approach predicts the availability
of channels accurately for more than one time slot
Epidemic variability in complex networks
We study numerically the variability of the outbreak of diseases on complex
networks. We use a SI model to simulate the disease spreading at short times,
in homogeneous and in scale-free networks. In both cases, we study the effect
of initial conditions on the epidemic's dynamics and its variability. The
results display a time regime during which the prevalence exhibits a large
sensitivity to noise. We also investigate the dependence of the infection time
on nodes' degree and distance to the seed. In particular, we show that the
infection time of hubs have large fluctuations which limit their reliability as
early-detection stations. Finally, we discuss the effect of the multiplicity of
shortest paths between two nodes on the infection time. Furthermore, we
demonstrate that the existence of even longer paths reduces the average
infection time. These different results could be of use for the design of
time-dependent containment strategies
Existence of positive solutions for a Brezis-Nirenberg type problems involving an inverse operator
This article concerns the existence of positive solutions for the
second order equation involving a nonlocal term
ââu = Îł(ââ)â1u + |u|
pâ1u,
under Dirichlet boundary conditions. We prove the existence of positive solutions depending on the positive real parameter Îł > 0, and up to the critical
value of the exponent p, i.e. when 1 < p †2
â â 1, where 2â = 2N
Nâ2
is the
critical Sobolev exponent. For p = 2â â 1, this leads us to a Brezis-Nirenberg
type problem, cf. [5], but, in our particular case, the linear term is a nonlocal term. The effect that this nonlocal term has on the equation changes the
dimensions for which the classical technique based on the minimizers of the
Sobolev constant, that ensures the existence of positive solution, going from
dimensions N â„ 4 in the classical Brezis-Nirenberg problem, to dimensions
N â„ 7 for this nonlocal problem.This research was partially supported by the Ministry of Economy and Competitiveness of Spain, and by the FEDER under research projects MTM2016-80618-P and PID2019-106122GB-I00. P. Alvarez-Caudevilla was also supported by the Ministry of Economy and Competitiveness of Spain under research project RYC-2014-15284
Polarization phenomena in open charm photoproduction processes
We analyze polarization effects in associative photoproduction of
pseudoscalar () charmed mesons in exclusive processes , , . Circularly polarized photons
induce nonzero polarization of the -hyperon with - and -components
(in the reaction plane) and non vanishing asymmetries and for polarized nucleon target. These polarization observables can be
predicted in model-independent way for exclusive -production processes
in collinear kinematics. The T-even -polarization and asymmetries for
non-collinear kinematics can be calculated in framework of an effective
Lagrangian approach. The depolarization coefficients , characterizing
the dependence of the -polarization on the nucleon polarization are also
calculated.Comment: 36 pages 13 figure
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