208 research outputs found
The effect of cosmic variance on the characteristics of dust polarization power spectra
No full textIn the context of cosmic microwave background polarization studies and the characterization of the Galactic foregrounds, the power spectrum analysis of the thermal dust polarization sky has led to intriguing evidence of an E∕ B asymmetry and a positive TE correlation. In this work, we produce synthesized dust polarization maps from a set of global magneto-hydrodynamic (MHD) simulations of Milky-Way-sized galaxies, and analyze their power spectra at intermediate angular scales (intermediate angular multipoles l∈ [60, 140]). We study the role of the initial configuration of the large-scale magnetic field, its strength, and the feedback on the power spectrum characteristics. Using full-galaxy MHD simulations, we were able to estimate the variance induced by the peculiar location of the observer in the galaxy. We find that the polarization power spectra sensitively depend on the observer's location, impeding a distinction between different simulation setups. In particular, there is a clear statistical difference between the power spectra measured from within the spiral arms and those measured from the inter-arm regions. Also, power spectra from within supernova-driven bubbles share common characteristics, regardless of the underlying model. However, no correlation was found between the statistical properties of the polarization power spectra and the local (with respect to the observer) mean values of physical quantities such as the density and the strength of the magnetic field. Finally, we find some indications that the global strength of the magnetic field may play a role in shaping the power spectrum characteristics; as the global magnetic field strength increases, the E∕ B asymmetry and the TE correlation increase, whereas the viewpoint-induced variance decreases. However, we find no direct correlation with the strength of the local magnetic field that permeates the mapped region of the interstellar medium
La labor editorial de Vera Tassis
No full textThis article reviews and analyzes the various contributions on the work of Vera Tassis, especially as regards the texts edited by him, and highlights the major points of conflict that exist today, particularly the value one can give to the texts which Vera may have followed as a basic text and his relevance in detecting possible double versions of works by Calderón de la Barca. It would be desirable to advance the investigation in these areas towards Calderón’s controversial friend.En este artículo se repasan y analizan las diferentes aportaciones sobre la labor de Vera Tassis, en especial en lo que respecta a los textos editados por él, y se señalan los mayores puntos de conflicto que existen en la actualidad, particularmente el valor que se quiera dar a los textos que Vera pudo haber seguido como texto base, así como su relevancia a la hora de detectar posibles dobles versiones de obras de Calderón de la Barca. En estos ámbitos sería deseable que avanzase la investigación en torno al polémico amigo de Calderón
L'oeuvre de Lev Tolstoj dans les romans de l'écrivain Mark Aldanov [Un dialogue ininterrompu]
No full textGervaise Tassis, The works of Lev Tolstoi reflected in Mark Aldanov's novels: a permanent dialogue.
The famous Russian émigré writer Mark Aleksandrovich Aldanov (his real name was Landau, 1886-1957) has been all his life an untiring reader of the works of his favourite writer Lev Nikolaevich Tolstoi. Nevertheless he has never entirely understood this great Russian writer though he was full of admiration for him, he just could not understand Tolstoi's faith, Tolstoi's quest of God. Aldanov could only see in him the writer of genius, the author of the yet unequalled masterpiece War and peace. But in fact, Aldanov reader of War and peace tells us more about his own art of historical novel, and about his own method which is much more scrupulous and historical than Tolstoi's. It clearly appears in a comparison between their two Napoleons. And so we are able to see in Aldanov's novels how enthusiastically, but at the same time, how reducingly, he always kept on reading the works of L. N. Tolstoi.Gervaise Tassis, L'œuvre de Lev Tolstoj dans les romans de l'écrivain MarkAldanov : un dialogue ininterrompu.
Le célèbre écrivain émigré russe Mark Aleksandrovič Aldanov, de son vrai nom Landau (1886- 1957), n'a jamais cessé, tout au long de sa vie, de lire et de relire l'œuvre de son auteur favori, Lev Nikolaevič Tolstoj. Il n'a pourtant jamais véritablement compris cet auteur malgré la profonde et fervente admiration qu'il lui vouait, méconnaissant sa quête de Dieu et sa foi. Aldanov n'a vu en lui que le génial écrivain, l'auteur du chef-d'œuvre inégalé de la littérature russe qu'est pour lui Guerre et paix. Mais Aldanov lecteur de Guerre et paix nous apprend beaucoup sur son propre art du roman historique, sur sa méthode, bien plus scrupuleuse, méticuleuse et historique que celle de Tolstoj. Une comparaison de leur Napoléon respectif le montre ici. L'on voit ainsi poindre dans ses propres romans une lecture à la fois fervente et réductrice de l'œuvre du grand classique russe.Tassis Gervaise. L'oeuvre de Lev Tolstoj dans les romans de l'écrivain Mark Aldanov [Un dialogue ininterrompu]. In: Cahiers du monde russe et soviétique, vol. 33, n°2-3, Avril-Septembre 1992. pp. 147-180
Parece que con mis ojos se abrasan los horizontes. Las “evidencias” líricas de Juan de Tassis, Conde de Villamediana
No full textThis paper focuses on a special modality of construction of poetical images in Juan de Tassis, Count of Villamediana’s
poetry, which is based on the rhetorical devices that aim at the metaphorical evidentia. It corresponds to a personal
technique of composition quite opposite to other manners that critics usually recognize as typical of this author;
nevertheless, this exclusive technique represents a useful tool by which the lyrical subject can project outside his
inner and most profound instances.En el presente trabajo se intenta dar cuenta de una modalidad de construcción de la imagen poética de parte de Juan de Tassis, Conde de Villamediana, basada en los recursos retóricos que favorecen la evidentia metafórica. Se trata de un procedimiento versificatorio fundamentalmente contrario al que se suele reconocer como típico del autor y que, sin embargo, se revela en los textos como el medio a través del cual el sujeto lírico proyecta en la realidad exterior sus instancias más profundas
Víctor Infantes de Miguel, o las venturas del libro
No full textAn outline of the personal relationship of an intellectual nature between the author and Víctor Infantes. It is structured as a convergence along four lines: the poetic experimentations of the author that began in 1964, and culminated in 1972 (experimental poetry); an interest in emblems and hieroglyphics; my book Juegos del Sacromonte; and finally, el conde de Villamediana, Don Juan de Tassis y Peralta, Correo Mayor de Felipe IV, Mercurio-Hermes de la Corte. KEYWORDS: Víctor Infantes; Experimental Poetry; Emblematics; Juegos del Sacromonte; Juan de Tassis y Peralta
A dynamo amplifying the magnetic field of a Milky-Way-like galaxy
No full textContext. The magnetic fields of spiral galaxies are so strong that they cannot qualify as primordial. Their typical values are over one billion times higher than any value predicted for the early Universe. Explaining this immense growth and incorporating it in galaxy evolution theories is one of the long-standing challenges in astrophysics.
Aims. So far, the most successful theory for the sustained growth of the galactic magnetic field is the alpha-omega dynamo. This theory predicts a characteristic dipolar or quadrupolar morphology for the galactic magnetic field, which has been observed in external galaxies. So far, however, there has been no direct demonstration of a mean-field dynamo operating in direct, multi-physics simulations of spiral galaxies. We carry out such a demonstration in this work.
Methods. We employed numerical models of isolated, star-forming spiral galaxies that include a magnetized gaseous disk, a dark matter halo, stars, and stellar feedback. Naturally, the resulting magnetic field has a complex morphology that includes a strong random component. Using a smoothing of the magnetic field on small scales, we were able to separate the mean from the turbulent component and analyze them individually.
Results. We find that a mean-field dynamo naturally occurs as a result of the dynamical evolution of the galaxy and amplifies the magnetic field by an order of magnitude over half a Gyr. Despite the highly dynamical nature of these models, the morphology of the mean component of the field is identical to analytical predictions.
Conclusions. This result underlines the importance of the mean-field dynamo in galactic evolution. Moreover, by demonstrating the natural growth of the magnetic field in a complex galactic environment, it brings us a step closer to understanding the cosmic origin of magnetic fields
A three-step approach to reliably estimate magnetic field strengths in star-forming regions
No full textContext. The magnetic field has been shown to play a crucial role in star formation. Dust polarization is one of the most effective tools for probing the properties of the magnetic field, yet it does not directly trace its strength. To bridge this gap, several methods have been developed, combining polarization and spectroscopic data, to estimate the strength of the magnetic field. The most widely applied method was developed by Davis (1951, Phys. Rev., 81, 890) and Chandrasekhar & Fermi (1953, ApJ, 118, 113), hereafter DCF, and relates the polarization angle dispersion to magnetic field strength under the assumption of Alfvénic turbulence. Skalidis & Tassis (2021, A&A, 647, A186), hereafter ST, relaxed this assumption to account for the compressible modes, and derived more accurate estimates of the magnetic field strength than the DCF in clouds with no self-gravity. The accuracy of these methods in self-gravitating regions is poorly explored. Aims. We aim to evaluate the accuracy of these magnetic-field estimation methods in star-forming regions and propose a systematic approach for calculating the key observational parameters they involve: the velocity dispersion (δv), the polarization angle dispersion (δθ), and the cloud density (ρ). Methods. We used a three-dimensional magnetohydrodynamic chemo-dynamical simulation of a turbulent collapsing molecular cloud. We generated synthetic observations for seven different inclination angles with respect to the mean component of the magnetic field, which encompass a comprehensive set of observables, including emission line spectra, Stokes parameters, and column density maps. We employed various approaches for estimating the parameters δv, δθ, and ρ, and identified the best approach that most effectively probes the plane-of-sky (POS) component of the magnetic field. Results. We find that the approach used to calculate the parameters δv, δθ, and ρ plays a crucial role in estimating the magnetic field strength, regardless of the specific method used (i.e., the DCF or the ST methods). We show that the value probed by both methods corresponds to the median of the molecular-species–weighted POS component of the magnetic field. We also find that ST outperforms DCF. The magnetic field strength values derived with the ST method accurately follow the expected cosine trend with respect to the inclination angle of the magnetic field and consistently remain within 1σ of the median component of the magnetic field strength. In self-gravitating clouds, we propose the following approach to accurately constrain the intrinsic parameters involved in the magnetic field estimation methods: ρ using radiative transfer analysis, δv using the second moment maps, and δθ by fitting Gaussians to the polarization angle distributions to remove the contribution of the hourglass morphology.SCI-SB-P
The Enigmatic Textual Transmission of Amado y aborrecido
No full textThe text of Amado y aborrecido, published by Vera Tassis in the Novena parte of Calderón’s Comedias (1691), shows clear signs of deriving from a late and already rather corrupt testimony: the one included in the unauthorized Quinta parte (1677). However, it offers a longer and more coherent text, and its variants seem to reveal the hand of the author. In this paper, two alternative hypotheses are proposed in order to explain these facts. Perhaps the composer of the 1691 text worked from a copy of the Quinta parte accompanied by a list of corrections taken from a more reliable testimony. Or, perhaps, Vera Tassis used the text of a new palace performance of the play, based on the Quinta parte but revised and corrected by Calderón himself. The conclusions may well be relevant for the textual criticism of other plays by the same author
La enigmática transmisión textual de ‘Amado y aborrecido’
No full textEl texto de ‘Amado y aborrecido’, publicado por Vera Tassis en la ‘Novena parte de las Comedias de Calderón’ (1691), muestra claras huellas de derivar de un testimonio tardío y ya bastante corrupto: el de la desautorizada Quinta parte de 1677. No obstante, ofrece un texto considerablemente más largo y coherente, y sus variantes parecen revelar la mano del propio autor. En este estudio se proponen dos hipótesis alternativas capaces de explicar estos hechos: que el cajista responsable del texto de 1691 trabajara con un ejemplar de la Quinta parte acompañado de una lista de enmiendas procedentes de un testimonio más fiable; o que Vera Tassis manejara el texto usado para una reposición palaciega de la comedia —basado en la Quinta parte— enmendado por el propio Calderón. Las conclusiones pueden ser relevantes para la crítica textual de otras obras del autor.---------------------------------------------- The text of ‘Amado y aborrecido’, published by Vera Tassis in the ‘Novena parte of Calderón’s Comedias' (1691), shows clear signs of deriving from a late and already rather corrupt testimony: the one included in the unauthorized Quinta parte (1677). However, it offers a longer and more coherent text, and its variants seem to reveal the hand of the author. In this paper, two alternative hypotheses are proposed in order to explain these facts. Perhaps the composer of the 1691 text worked from a copy of the Quinta parte accompanied by a list of corrections taken from a more reliable testimony. Or, perhaps, Vera Tassis used the text of a new palace performance of the play, based on the Quinta parte but revised and corrected by Calderón himself. The conclusions may well be relevant for the textual criticism of other plays by the same author
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