1,721,128 research outputs found
Compact and versatile caesium thermal photonic-cells based on microstructured hollow core fibres for frequency and time references
No full textThe recent developments in fabrication of hollow core Photonic crystal fibres (HC-PCFs), especially Anti-resonant fibres (ARFs), made this class of fibre very attractive for gas-phase applications, which ultimately led to the concept of photonic reference cell. This device is a fully-connectorised, stand-alone, HC-PCF filled with a gas specimen. Its application spans from instrument calibration, quantum optics to high-resolution spectroscopy and metrology.For time and frequency applications, the use of alkali metals with narrow atomic features (in the kHz range) is a requirement for ultra-stable reference signals. However, the coherence time of atoms is strongly dependent on the vapour dynamics and photonic cell geometry. This dependency limits the use of alkali vapour in miniaturised reference cells, such as photonic cells, because of the short coherence time that leads to atomic features in the MHz range, for reference cells with cross-section of 100 μm, operating at room temperature. The diffusion of the vapour can be tailored by adding a mixture of inert gas (buffer gas), with resulting atomic features between kHz and sub-kHz range. This is a very well-known method widely used in standard reference cells.This thesis reports on the advances in HC-PCFs technology for time and frequency reference applications. Firstly, I present a method to interconnect solid core fibres and HC-PCFs with dissimilar core sizes by employing a mode field adapter (MFA) to mediate the joint. I model and demonstrate the use of such MFAs for a photonic cell, fully-connectorised to SMFs. Secondly, I demonstrate for the first time spectroscopy of coherent population trapping (CPT) dark resonance in Kagome-lattice ARFs filled with Cs. CPT is a quantum effect very useful in frequency reference applications as it can provide an indirect measurement of the Cs clock transition (~9.2 GHz). I model and demonstrate world record line-width narrowing of CPT dark resonance in HC-PCFs and micro-metre scale capillaries filled with thermal Cs-vapour, with experimental observation of line-widths below 50 kHz for a Kagome-lattice ARF with a hollow core diameter of 125 μm
Curso de Pre-Grado en Formación de Recursos Humanos en Histología y Embriología
Full text linkLa formación de ayudantes alumnos es común en la carrera de Ciencia Veterinaria. Por ello es conveniente la formación, tanto ética y como profesional, de dichos aspirantes, a partir del 1° año de la facultad. Teniendo en cuenta esta situación los miembros de la cátedra de Histología y Embriología anexaron a la actividad académica la formación de recursos humanos a través de cursos de pregrado.Fil: Bazoalto, Daniel. Universidad Católica de Salta; Argentina.Fil: Alonso, Marcelo Javier. Universidad Católica de Salta. Facultad de Ciencias Agrarias y Veterinarias; Argentina.Fil: Ferri, David. Universidad Católica de Salta. Facultad de Ciencias Agrarias y Veterinarias; Argentina.Fil: Peñalva, Pablo. Universidad Católica de Salta; Argentina
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Ausencia de Hospital-Escuela. Un desafío pedagógico
Full text linkSe realiza un relato de las estrategias elegidas para organizar las prácticas preprofesionales en la cátedra de Prácticas Hospitalarias en Animales de Compañía. El problema se plantea por que no disponemos de un Hospital-Escuela para la realización de prácticas clínicas por parte de los alumnos. Por lo tanto debemos aprovechar al máximo las prácticas preprofesionales, en diferentes clínicas privadas, sin confrontar con los criterios de los clínicos que reciben a los alumnos en sus veterinarias. Así fuimos aprendiendo de los errores cometidos en anteriores experiencias.Fil: Luna, Oscar Ricardo. Universidad Católica de Salta; Argentina.Fil: Alonso, Marcelo Javier. Universidad Católica de Salta. Facultad de Ciencias Agrarias y Veterinarias; Argentina.Fil: Ricci, Natalia. Universidad Católica de Salta; Argentina
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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