1,742,476 research outputs found
The putative center in NGC 1052 [Elektronisk resurs]
No full textContext. Many active galaxies harbor powerful relativistic jets, however, the detailed mechanisms of their formation and acceleration remain poorly understood. Aims. To investigate the area of jet acceleration and collimation with the highest available angular resolution, we study the innermost region of the bipolar jet in the nearby low-ionization nuclear emission-line region (LINER) galaxy NGC 1052. Methods. We combined observations of NGC 1052 taken with VLBA, GMVA, and EHT over one week in the spring of 2017. Our study is focused on the size and continuum spectrum of the innermost region containing the central engine and the footpoints of both jets. We employed a synchrotron-self absorption model to fit the continuum radio spectrum and we combined the size measurements from close to the central engine out to ∼1 pc to study the jet collimation. Results. For the first time, NGC 1052 was detected with the EHT, providing a size of the central region in-between both jet bases of 43 μas perpendicular to the jet axes, corresponding to just around 250 RS (Schwarzschild radii). This size estimate supports previous studies of the jets expansion profile which suggest two breaks of the profile at around 3 × 103 RS and 1 × 104 RS distances to the core. Furthermore, we estimated the magnetic field to be 1.25 Gauss at a distance of 22 μas from the central engine by fitting a synchrotron-self absorption spectrum to the innermost emission feature, which shows a spectral turn-over at ∼130 GHz. Assuming a purely poloidal magnetic field, this implies an upper limit on the magnetic field strength at the event horizon of 2.6 × 104 Gauss, which is consistent with previous measurements. Conclusions. The complex, low-brightness, double-sided jet structure in NGC 1052 makes it a challenge to detect the source at millimeter (mm) wavelengths. However, our first EHT observations have demonstrated that detection is possible up to at least 230 GHz. This study offers a glimpse through the dense surrounding torus and into the innermost central region, where the jets are formed. This has enabled us to finally resolve this region and provide improved constraints on its expansion and magnetic field strength
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Santa Fe (ATSF) 1052
No full textA photograph postcard showing Santa Fe (ATSF) 1052, 2-6-2, (Baldwin 1902), class 1050. Rebuilt at Topeka 4-1913
. 1052 Año 21 (2022) octubre. El Tlacuache
No full textLos archivos audiovisuales no cuentan con un inicio oficial, surgieron de diversas formas, algunos archivos contenían grabaciones sonoras, cinematográficas, televisivas, radiofónicas, entre otras, las cuales eran parte de instituciones. En los años treinta, se comenzaron a visibilizar, en específico los archivos de películas, por lo que tomaron una identidad (Edmondson, 1998: 17) y obtuvieron reconocimiento por parte de bibliotecas y federaciones internacionales archivísticas. En cambio, los archivos de grabaciones sonoras tuvieron otra forma de organización.- Archivo Audiovisual. Memoria de un lugar por Lorena Reyes Castañeda.Edmondson, Ray (1998) “Una filosofía de los archivos audiovisuales” preparado por Ray Edmondson y miembros de la AVAPIN, Programa General de Información y UNISIST. París: UNESCO.
Bloch, Catherine (2021) “Documentos sonoros y audiovisuales en Memoria del Mundo” en Creadores de memoria: Los archivos sonoros y audiovisuales en México. Coord. Perla Olivia Rodríguez Reséndiz, Instituto de Investigaciones Bibliotecológicas y de la Información. México: UNAM.
Reyes Sotelo, Jorge Alberto, et. al. (2014) Ponencia “Proyecto del Centro de Información y Documentación del Centro INAH Morelos”, Primer Congreso internacional. El Patrimonio cultural y las nuevas tecnologías. Ciudad de México: Museo Nacional de Antropología e Historia.
Roca, Lourdes, et. al. (2014) Tejedores de imágenes. Propuestas metodológicas de investigación y gestión del patrimonio fotográfico y audiovisual. México: Instituto Mora. Laboratorio Audiovisual de Investigación Social.
Rodríguez Reséndiz, Perla Olivia (2021) “Aproximación histórica al origen de los archivos sonoros y audiovisuales en México” en Creadores de memoria: Los archivos sonoros y audiovisuales en México. Coord. Perla Olivia Rodríguez Reséndiz, Instituto de Investigaciones Bibliotecológicas y de la Información. México: UNAM
UNESCO (1980) Recomendación sobre la Salvaguardia y la Conservación de Imágenes en Movimiento.
https://conservacion.inah.gob.mx/normativa/wp-content/uploads/Documento235.pdf [Consultado septiembre, 2022].Mesa de luz con cinta de celuloide y lupa para
ver a detalle fotogramas. Foto: Lore ReCa, 2022. Cinta 8mm vista desde una lupa. Foto: Lore ReCa, 2022
Ultra-deep imaging of NGC 1052-DF2 and NGC 1052-DF4 to unravel their origins
No full textA number of scenarios have been proposed to explain the low velocity dispersion (and hence possible absence of dark matter) of the low surface brightness galaxies NGC 1052-DF2 and NGC 1052-DF4. Most of the proposed mechanisms are based on the removal of dark matter via the interaction of these galaxies with other objects. A common feature of these processes is the prediction of very faint tidal tails, which should be revealed by deep imaging (μg > 30 mag arcsec−2). Using ultra-deep images obtained with the Gemini telescopes, about 1 mag deeper than previously published data, we analyzed the possible presence of tidal tails in both galaxies. We confirm the presence of tidal tails in NGC 1052-DF4, but see no evidence for tidal effects in NGC 1052-DF2, down to surface brightnesses of μg = 30.9 mag arcsec−2. We therefore conclude that while the absence of dark matter in NGC 1052-DF4 could be attributed to the removal of dark matter by gravitational interactions, in the case of NGC 1052-DF2 this explanation seems less plausible, and therefore other possibilities such as an incorrect distance measurement or that the system may be rotating could alleviate the dark matter problem
Philosophy [IO Islamic 1052] Commentary on تهذيب
No full textPhilosophy.
This manuscript is now IO Islamic 1052 in the India Office collections.
[metadata: Otto Loth, A Catalogue of the Arabic Manuscripts in the Library of the India Office, (volume 1), no. 538 here with further notations and hyperlinks].
538.
1052. Size 7 in. by 5 in.; foll. 146. Nineteen lines in a page.
الترغيب في كشف رموز التهذيب تاليف الشيخ الامام العالم العلامة الحبر البحر الفهامة محيى الدين الكافياجى الحنفى.
A copious Commentary on the first part of the Tahdhîb, by Muḥyi al-dîn (Muḥammad b. Sulaimân) KÂFIYÂJÎ (d. A.H. 879). Cf. Ḥ. Kh. ii. 482, and regarding the author and his surname, Liber As-Sojutii de nomin. relat., ed [Pieter Johannes] Veth, p. ٢١٨. This commentary is apparently also to be found in Aumer, Hdss. Mûnch., p. 304, no. 673, 2.
This is a commentary by قال and اقول, and it contains the full text of the Tahdhîb. Begins:
الحمدلله الذى هدانا الى سواء الطريق‘ و يسرلنا سلوك مناهج التصور و التصديق
Plainly written, but left unfinished. Slight defects, which are indicated by blank leaves, occur after foll.
49 and 68; another defect, after fol. 76, has been supplied from ‘’a different commentary.’’ In the latter portion several blanks, intended for diagrams and rubrics, have not been filled in. Slightly injured by damp.
The following note regarding the author is on the title-page:
هذا شرح التهذيب الذی قرا الشارح على المصنف و هو ابن خالته سنة.... This MS. was the property of Muḥammad Abu’l-Faḍl Ḳuṭb al-dîn.. Nahrwâlî Ḥanafî.
[Gaikwar.
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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