1,116 research outputs found
U-operators
Inspired by a statement of W. Luh asserting the existence of entire functions having together with all their derivatives and antiderivatives
some kind of additive universality or multiplicative universality on certain compact subsets of the complex plane or of, respectively, the punctured complex plane, we introduce in this paper the new concept of U-operators, which are defined on the space of entire functions. Concrete examples, including differential and antidifferential operators, composition, multiplication and shift operators, are studied. A result due to Luh, Martirosian and Müller about the existence of universal entire functions with gap power series is also strengthened.Plan Andaluz de Investigación (Junta de Andalucía
Sequences of differential operators: exponentials, hypercyclicity and equicontinuity
In this paper, an eigenvalue criterion for hypercyclicity due to the first author is improved. As a consequence, some new sufficient conditions for a sequence of infinite order linear differential operators to be hypercyclic on the space of holomorphic functions on certain domains of C N are shown. Moreover, several necessary conditions are furnished. The equicontinuity of a family of operators as before is also studied, and it is even characterized if the domain is C N. The results obtained extend or improve earlier work of several authors.Dirección General de Enseñanza Superior (DGES). EspañaJunta de Andalucí
Towards Accurate Modeling of Line-Intensity Mapping One-Point Statistics: Including Extended Profiles
Line-intensity mapping (LIM) is quickly attracting attention as an
alternative technique to probe large-scale structure and galaxy formation and
evolution at high redshift. LIM one-point statistics are motivated because they
provide access to the highly non-Gaussian information present in line-intensity
maps and contribute to break degeneracies between cosmology and astrophysics.
Now that promising surveys are underway, an accurate model for the LIM
probability distribution function (PDF) is necessary to employ one-point
statistics. We consider the impact of extended emission and limited
experimental resolution in the LIM PDF for the first time. We find that these
effects result in a lower and broader peak at low intensities and a lower tail
towards high intensities. Focusing on the distribution of intensities in the
observed map, we perform the first model validation of LIM one-point statistics
with simulations and find good qualitative agreement. We also discuss the
impact on the covariance, and demonstrate that if not accounted for, large
biases in the astrophysical parameters can be expected in parameter inference.
These effects are also relevant for any summary statistic estimated from the
LIM PDF, and must be implemented to avoid biased results. The comparison with
simulations shows, however, that there are still deviations, mostly related
with the modeling of the clustering of emitters, which encourage further
development of the modeling of LIM one-point statistics.Comment: 13 pages (+3 pages of references), 7 figure
Cosmological implications of Primordial Black Holes
The possibility that a relevant fraction of the dark matter might be
comprised of Primordial Black Holes (PBHs) has been seriously reconsidered
after LIGO's detection of a binary black holes merger.
Despite the strong interest in the model, there is a lack of studies on
possible cosmological implications and effects on cosmological parameters
inference. We investigate correlations with the other standard cosmological
parameters using cosmic microwave background observations, finding significant
degeneracies, especially with the tilt of the primordial power spectrum and the
sound horizon at radiation drag. However, these degeneracies can be greatly
reduced with the inclusion of small scale polarization data. We also explore if
PBHs as dark matter in simple extensions of the standard CDM
cosmological model induces extra degeneracies, especially between the
additional parameters and the PBH's ones. Finally, we present cosmic microwave
background constraints on the fraction of dark matter in PBHs, not only for
monochromatic PBH mass distributions but also for popular extended mass
distributions. Our results show that extended mass distribution's constraints
are tighter, but also that a considerable amount of constraining power comes
from the high- polarization data. Moreover, we constrain the shape of
such mass distributions in terms of the correspondent constraints on the PBH
mass fraction.Comment: 20 pages, 9 figures. Matches version accepted to publish in JCA
Francisco Valdés: el viaje inacabado de un escritor de vanguardia
Este autor extremeño, tras su asombrosa puesta al día con la literatura de su época, ejerciendo una crítica ensayística de primerísima línea y cultivando una prosa de raigambre novecentista, pero con nítidas aproximaciones a la mejor prosa poética del 27, desemboca, arrastrado por la "parecida situación político-económica del país a partir de la Segunda República, en una posición reaccionaria, heredera, no obstante, de su humanitario y sensible talante intelectual.This author, after his amazing start up with the literature of his time, putting in the first line his critical essays and cultivating a novecentista prose, but with clear approaches to the best poetic prose of Generation of '27, flows, driven by the similar political and economic situation since the Second Republic, in a reactionary position, heiress, however, of its humanitarian and sensitive intellectual mood.notPeerReviewe
La forma epistolar y sus funciones en "La estafeta romántica" de Galdós
El empleo de la forma epistolar pocos años después de la conquista narrativa llevada a cabo en obras como "La incógnita" y "Realidad", en un episodio nacional de la tercera serie, y en el momento en que se da la dedicación decidida de Galdós, al género teatral, es razón suficiente para calibrar con detenimiento su importancia y no sólo en virtud de la evolución del estilo de su autor y el empleo de determinados recursos narrativos. “La estafeta romántica” es una acertada simbiosis de dos de las corrientes más influyentes en toda la obra de Galdós: la novela histórica y el folletín. El ser un episodio nacional nos evita cualquier explicación sobre los componentes históricos; en cuanto al folletín, toda la serie y específicamente La estafeta da buena cuenta de él.The employment of the epistolary form a few years after the narrative conquest carried out in previous works, in a National Episode, and at the same time that gives the firm commitment of Galdós’ theatrical genre, it's sufficient reason to carefully calibrate its importance and not only in virtue of the evolution of the author’s style and the employment of certain narrative resources. "The romantic Estafeta" is a successful symbiosis of two of the most influential currents in Galdos's entire work: the historical novel and the humorous
La revista "Ultra" de Oviedo en el mar revuelto del ultra
Ultra de Oviedo es una interesante y desconocida revista literaria. Debido a su rareza bibliográfica apenas ha tenido referencias críticas y las pocas, no son muy exhaustivas. Tal vez jugó un papel crucial entre las experiencias regionalistas de la España de vanguardia en el primer período de posguerra y llegó a ser bastión periférico del “Ultraísmo” que brotó en Sevilla y se desarrolló más tarde en Madrid. La revista canalizó los trabajos de vanguardia de sus creadores y también incluye entre sus páginas algunos de los más relevantes poetas de la nueva generación literaria ligada al ultraísmo con nombres como Isaac de Vando Villar, Adriano del Valle, Guillermo de Torre y Gerardo Diego.Ultra from Oviedo is an interesting, almost unknown, literary magazine. Due
to its bibliographical rarity it has hardly had critical references, and the very few are not very exhaustive. However, it played a crucial role within the regionalist experiences of the Spanish vanguard in the early years of the postwar
period. It became a committed peripheral bastion of the «Ultraísmo», which sprang up in Sevilla and later developed in Madrid. Ultra from Oviedo not only channeled the supposedly vanguard works of its creators, not very well known in national
literary panorama, but it also included in its pages some of the most relevant poets
of the new literary generation, who were linked to «Ultraísmo». Names such as
Isaac de Vando Villar, Adriano del Valle, Guillermo de Torre and Gerardo Diego
were among them.notPeerReviewe
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