1,721,695 research outputs found
Detección de micro-plásticos en el medio marino mediante backscattering ultrasónico de alta frecuencia
No full textUniversidad Politécnica de Madrid.
Máster Universitario en Ingeniería Acústica. Trabajo Fin de Máster.
106 páginas, 96 figuras, 31 tablas.Los microplásticos son partículas de un tamaño inferior a 5 milímetros que han emergido como una
creciente preocupación en los ecosistemas acuáticos a nivel global. Su presencia generalizada y
persistencia en ambientes marinos ha despertado una alarma ambiental debido a su impacto
negativo en la vida marina, la salud humana y el bienestar de los ecosistemas en su conjunto. La
acumulación de microplásticos en los océanos representa un desafío, ya que pueden ser ingeridos
por organismos acuáticos y potencialmente ingresar a la cadena alimentaria, con consecuencias aún
por determinar.
Por estos motivos, la detección y cuantificación de estas partículas se ha convertido en un objetivo
crucial. Para este fin se han propuesto diferentes métodos como la espectroscopía infrarroja o las
imágenes hiperespectrales. En este proyecto fin de Máster se va a estudiar la idoneidad del uso de
dispersión de ultrasonidos o backscattering ultrasónico de alta frecuencia para la detección de
microplásticos en el entorno marino. Este estudio comprende: la revisión de antecedentes y avances
en este campo; la búsqueda de un modelo teórico que sirva de base y que permita comprender las
variables significativas que determinan la capacidad de esta técnica para identificar micropartículas
de diferente naturaleza así como analizar los resultados obtenidos y; por último, de una fase
experimental para evaluar la viabilidad real del método, en la que se han empleado suspensiones de
partículas de poliestireno y levaduras en un rango de tamaños 7-10um, como modelos de dispersores
plásticos y orgánicos, respectivamente. En esta última fase se caracterizan las partículas de manera
óptica y acústica. El análisis óptico se realiza en laboratorio mediante un microscopio y el programa
de procesamiento de imágenes ImageJ. El análisis acústico comienza con la obtención de imágenes
ultrasónicas y procesado de las mismas, y termina con una clasificación de las partículas detectadas
a partir de algoritmos desarrollados a lo largo del presente trabajo e implementados en la plataforma
de programación Matlab.
Los resultados obtenidos en este estudio preliminar son prometedores. Tras evaluar diferentes
estrategias de clasificación, se ha obtenido un error por debajo del 12% en la identificación de
partículas plásticas.[ENG] Microplastics are microparticles smaller than 5 millimetres in size that have emerged as a growing
concern in aquatic ecosystems globally. Their widespread presence and persistence in marine
environments have raised environmental alarm due to their negative impact on marine life, human
health, and the welfare of ecosystems. The accumulation of microplastics in the oceans represents a
challenge, as they can be ingested by aquatic organisms and potentially reach the food chain, with
consequences yet to be determined.
For these reasons, detection and quantification of these particles has become a crucial objective. For
this end, different methods have been suggested, such as infrared spectroscopy or hyperspectral
imaging. This master’s final project will study the suitability of the use of ultrasound scattering or high-
frequency ultrasonic backscattering for the detection of microplastics in the marine environment. This
study includes: a review of the background and advances in this field the search for a theoretical
model to serve as a basis for understanding the significant variables that determine the capacity of
this technique to identify microparticles of different natures and to analyse the results obtained; and
finally, an experimental phase to evaluate the real viability of the method, in which suspensions of
polystyrene and yeast particles in a size range of 7-10um have been used as models of plastic and
organic dispersants, respectively. In this last phase, the particles are characterised optically and
acoustically. The optical analysis is performed in the laboratory using a microscope and the image
processing software ImageJ. The acoustic analysis begins with the acquisition of ultrasonic images
and their processing and ends with a classification of the detected particles based on algorithms
developed throughout this work and implemented in the Matlab programming platform.
The results obtained in this preliminary study are promising. After evaluating different classification
strategies, an error of less than 12% has been obtained in the identification of plastic particles.Peer reviewe
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
Desarrollo de un algoritmo para el cálculo de flujo vascular en pequeños vasos mediante técnicas ecográficas.
No full textTrabajo de fin de máster
Máster en Matemática Industrial
76 páginas, 41 figuras, 17 tablasEn este trabajo de fin de máster se aborda el diseño de un algoritmo para el cálculo de
la velocidad del flujo sanguíneo dentro de pequeños vasos a través de técnicas ecográficas, su
implementación en Matlab y un estudio de su funcionamiento. El tema ha sido propuesto por el
CSIC/ITEFI (Consejo Superior de Investigaciones Científicas/ Instituto de Tecnologías Físicas
y de la Información), y ha sido tutorizado por Luis Elvira Segura y por María Luisa Rapún
Banzo, del CSIC y de la UPM respectivamente.
Se presentarán en este apartado los motivos para la elaboración de este proyecto, un contexto
para poder situar el tema a trabajar en un nivel teórico y tecnológico y un pequeño resumen
de cómo se organiza esta memoria
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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