34 research outputs found
Matching random colored points with rectangles
No full textThe version of record of this article, first published in Journal of Combinatorial Optimization, is available online at Publisher’s website: http://dx.doi.org/10.1007/s10878-023-01010-zGiven n > 0, let S ¿ [0,1]2 be a set of n points, chosen uniformly at random. Let R¿B be a random partition, or coloring, of S in which each point of S is included in R uniformly at random with probability 1/2. We study the random variable M(n) equal to the number of points of S that are covered by the rectangles of a maximum strong matching of S with axis-aligned rectangles. The matching consists of closed axis-aligned rectangles that cover exactly two points of S of the same color, and is strong in the sense that all of its rectangles are pairwise disjoint. We prove that almost surely M(n) = 0.83n for n large enough. Our approach is based on modeling a deterministic greedy matching algorithm that runs over the random point set as a Markov chain.Author Corujo was supported by grants from the Université Paris-Dauphine (France) and the ITI IRMIA++. Author Flores-Peñaloza was supported by project PAPIIT IN120520 (UNAM, Mexico). Author Huemer was supported by projects PID2019-104129GB-I00/ MCIN/ AEI/ 10.13039/501100011033 and Gen. Cat. DGR 2021-SGR-00266. Author Pérez-Lantero was supported by projects CONICYT FONDECYT/Regular 1160543 (Chile), DICYT 041933PL Vicerrectoría de Investigación, Desarrollo e Innovación USACH (Chile), and Programa Regional STICAMSUD 19-STIC-02. Author Seara was supported by project PID2019-104129GB-I00/ MCIN/ AEI/ 10.13039/ 501100011033 and Gen. Cat. DGR 2021-SGR-00266.Postprint (author's final draft
Intraoperative point-of-care subcostal Inferior Vena Cava (IVC) imaging to detect embolism during hip arthroplasty: clinical image
No full textIdentificación de cepas consanguíneas de roedores como modelos para enfermedades cardiovasculares
No full textDentro de las investigaciones en biomedicina, una de las herramientas más empleadas es el uso de modelos animales y que ha supuesto una gran ayuda en los diferentes avances terapéuticos logrados hasta el momento.
Los modelos animales biomédicos de enfermedad se pueden definir como aquellos en los que se desarrolla espontánea o experimentalmente una situación patológica similar o equivalente a una patología humana. Según el origen de estos modelos nos permitirá el estudio de las causas subyacentes o etiológicas de las enfermedades, como puede ser en el caso del modelo de hámster con malformaciones valvulares. Por otro lado también se puede emplear para estudiar la fisiopatología de las enfermedades y para testar estrategias terapéuticas. Un claro ejemplo de los modelos utilizados en estos últimos estudios son los manipulados genéticamente, sobre todo ratones, Los modelos de aterosclerosis son buenos ejemplos del empleo de animales doble mutante en investigaciones biomédicas de enfermedades humanas.
Una de las actividades principales del grupo de investigación fue el desarrollo de modelos animales relevantes para la investigación cardiovascular. El primero de estos modelos fue una cepa consanguínea de hámsteres, caracterizada por presentar una elevada incidencia de anomalías congénitas de las válvulas semilunares y de las arterias coronarias. Este ha sido el punto de partida para uno de los estudios que conforma la presente tesis, cuyo objetivo es identificar válvulas aórticas con morfología cuadricúspide en el hámster, describir su anatomía e interpretar su origen embriológico en base a la hipótesis propuesta.
Otro hito del grupo de investigación respecto al planteamiento de esta tesis fue la adquisición de un segundo modelo animal para investigaciones cardiovasculares. Se trata de una cepa de ratones modificados genéticamente (knockout), deficientes en la glicoproteína Osteoglicina/Mimecan (Ogn).
Algunos estudios previos sugerían que la Ogn juega un papel en el proceso aterosclerótico. La disponibilidad de los ratones deficientes en Ogn (Ogn-ko) permitió plantear un estudio sobre el efecto de la ausencia de esta glicoproteína en el desarrollo de la aterosclerosis, utilizando un modelo experimental de inducción de la enfermedad.
Finalmente el tercer y último hito que ha hecho posible la realización de la presente tesis tiene que ver con el estudio planteado, sobre los ratones Ogn-ko. Trabajos previos con este modelo habían puesto de manifiesto que, aunque Ogn es particularmente abundante en la matriz extracelular de algunos tejidos, estas estructuras presentan una anatomía e histología normales en los ratones Ogn-ko. Sin embargo un estudio demostraba que al menos un fenotipo asociado a la ausencia de Ogn era detectable solo bajo condiciones experimentales o de estrés. Estos datos hacían imperativo realizar un examen fenotípico del sistema vascular, en general, y de las arterias en las que se pretendía evaluar las lesiones ateromatosas a fin de validar el modelo animal para estudios sobre aterosclerosis.
La relevancia y utilidad de estos hallazgos pasa por conocer si los patrones coronarios anómalos descritos en la cepa C57BL/6 aparecen también en otras cepas del ratón de laboratorio y en ratones salvajes o, por el contrario, son exclusivos de la cepa C57BL/6
La precisión de las descripciones de la ejecución en tareas de discriminación condicional: Su relación con el requerimiento de distintos grados de atención
No full textOverview of RepLab 2014: author profiling and reputation dimensions for Online Reputation Management
No full textilps.science.uva.nl Abstract. This paper describes the organisation and results of RepLab 2014, the third competitive evaluation campaign for Online Reputation Management systems. This year the focus lied on two new tasks: repu-tation dimensions classification and author profiling, which complement the aspects of reputation analysis studied in the previous campaigns. The participants were asked (1) to classify tweets applying a standard typol-ogy of reputation dimensions and (2) categorise Twitter profiles by type of author as well as rank them according to their influence. New data collections were provided for the development and evaluation of systems that participated in this benchmarking activity
Hamsters’ (mesocricetus auratus) memory in a radial maze analog: the role of spatial versus olfactory cues
No full textThe golden hamster’s (Mesocricetus auratus) performance on radial maze tasks has not been studied a lot. Here we report the results of a spatial memory task that involved eight food stations equidistant from the center of a circular platform. Each of six male hamsters depleted the food stations along successive
choices. After each choice and a 5-s retention delay, the hamster was brought back to the center of the platform for the next choice opportunity. When only one baited station was left, the platform was rotated
to evaluate whether olfactory traces guided hamsters’ choices. Results showed that despite the retention delay hamsters performed above chance in searching for food. The choice distributions observed during
the rotation probes were consistent with spatial memory and could be explained without assuming guidance by olfactory cues. The radial maze analog we devised could be useful in furthering the study
of spatial memory in hamsters.Francois Tonneau was supported by the Portuguese FCT during the writing of this article
Uniform in time propagation of chaos for a Moran model
No full textThe goal of this article is to study the limit of the empirical distribution
induced by a mutation-selection multi-allelic Moran model, whose dynamic is
given by a continuous-time irreducible Markov chain. The rate matrix driving
the mutation is assumed irreducible and the selection rates are assumed
uniformly bounded. The paper is divided into two parts. The first one deals
with processes with general selection rates. For this case we are able to prove
the propagation of chaos in over the compacts, with speed of
convergence of order . Further on, we consider a specific type of
selection that we call additive selection. Essentially, we assume that the
selection rate can be decomposed as the sum of three terms: a term depending on
the allelic type of the parent (which can be understood as selection at death),
another term depending on the allelic type of the descendant (which can be
understood as selection at birth) and a third term which is symmetric. Under
this setting, our results include a uniform in time bound for the propagation
on chaos in of order , and the proof of the
asymptotic normality with zero mean and explicit variance, for the
approximation error between the empirical distribution and its limit, when the
number of individuals tend towards infinity. Additionally, we explore the
interpretation of the Moran model with additive selection as a particle process
whose empirical distribution approximates a quasi-stationary distribution, in
the same spirit as the Fleming\,--\,Viot particle systems. We then address the
problem of minimising the asymptotic quadratic error, when the time and the
number of particles go to infinity.Comment: 26 page
Palavras e imagens de mãos dadas: a arquitetura do álbum narrativo em Manuela Bacelar
No full textDoutoramento em LiteraturaÉ objetivo da presente investigação a análise sistemática do álbum narrativo
infantil, mais concretamente, da obra escrita e ilustrada por Manuela Bacelar,
numa leitura dialógica das suas componentes linguística e pictórica. Partindo
de um conspecto teórico-crítico do conceito e da caracterização do álbum
enquanto género maior da literatura, o estudo centra-se no exame técnicocompositivo
do corpus, procurando indagar alguns dos traços e/ou dos
recursos formais, retórico-estilísticos e ideotemáticos que singularizam a obra
desta premiada artista plástica, assentando em algumas das modernas
correntes literárias (e.g., a intertextualidade e a metaficção) que a inscrevem
numa estética pós-modernista. As repercussões práticas do contacto precoce
com o álbum e os seus contributos na promoção de comportamentos
emergentes de literacia são analisados num estudo de caso que a
investigação contempla. Analisando a interação entre as vertentes textual e
icónica sublinha-se a especificidade de um género que aposta na
narrativização como forma de aproximar a criança do universo plástico e
literário.The aim of this thesis is to provide a systematic analysis of the narrative
picturebooks (or picture storybook) of the author illustrator Manuela Bacelar –
an analysis derived from a dialogical reading of the linguistic and pictorial
components. The study begins with a critical overview of the concept and
characterization of the picturebook as one of the greatest forms of literature.
Relying upon modern literary currents (e.g., intertextuality and metafiction) to
be found in a postmodernist aesthetic, it examines the corpus, from both a
technical and compositional point of view, seeking to investigate some of the
traits and / or formal resources, rhetorical, stylistic and thematic, that
distinguish the work of this awarded artist. To contemplate the practical
implications of early contact with picturebooks and their possible contribution to
emergent literacy behaviours, a case study is described. By analysing
interaction with the textual and iconic aspects of these picturebooks, it
highlights how the specificity of a form that relies upon the narrative process
can bring a child closer to the illustrated and literary universe
Overview of RepLab 2014: Author Profiling and Reputation Dimensions for Online Reputation Management
No full textThis paper describes the organisation and results of RepLab 2014, the third competitive evaluation campaign for Online Reputation Management systems. This year the focus lied on two new tasks: reputation dimensions classification and author profiling, which complement the aspects of reputation analysis studied in the previous campaigns. The participants were asked (1) to classify tweets applying a standard typology of reputation dimensions and (2) categorise Twitter profiles by type of author as well as rank them according to their influence. New data collections were provided for the development and evaluation of systems that participated in this benchmarking activity
Literatura infantil chinesa: uma proposta de tradução e análise
No full textPretende-se, com a presente dissertação, traduzir e analisar o conto ilustrado Memórias de Infância, texto Lu Xun, e ilustrações de Da Jun, uma obra de literatura infantil muito popular na China. Este trabalho tem como objetivo proceder à divulgação, no contexto português, da literatura infantil chinesa, contribuindo para o seu mais abrangente conhecimento em Portugal. Para a realização deste trabalho, começou-se por escolher um livro chinês de literatura infantil que pudesse se traduzido para português. Depois, contextualizou-se a obra selecionada no panorama da literatura infantil chinesa contemporânea, dando conta das suas tendências e das diferenças mais significativas que apresenta em comparação com a literatura infantil ocidental. Além disso, também foi relevante refletir sobre a questão da tradução da literatura infantil e das tendências da literatura infantil em Portugal. Este estudo inclui ainda apresentações do autor e do ilustrador, e uma análise de conteúdo do livro em questão, nomeadamente centrada nas características das personagens principais e nas relações existentes entre elas, sem esquecer o tema e o seu tratamento. Finalmente, apresenta ainda uma reflexão sobre os elementos da cultura tradicional chinesa na literatura para crianças.The aim of this dissertation is to translate and analyze the illustrated short story Memories of Childhood, text by Lu Xun, and illustrations by Da Jun, a very popular children's literature in China. This work aims to disseminate Chinese children's literature in the Portuguese context, contributing to its most comprehensive knowledge in Portugal. For this work, we started by choosing a Chinese children's literature book that could be translated into Portuguese. Then, the selected work was contextualized in the panorama of contemporary Chinese children's literature, giving an account of its trends and the most significant differences that it presents in comparison with Western children's literature. In addition, it was also relevant to reflect on the issue of translation of children's literature and on the trends of children's literature in Portugal. This study also includes presentations of the author and illustrator, and an analysis of the content of the book in question, namely focusing on the characteristics of the main characters and on the relationships between them, without forgetting the theme and its treatment. Finally, it also presents a reflection on the elements of traditional Chinese culture in children's literature.Mestrado em Português Língua Estrangeira/Língua Segund
