Orientador: Djairo Guedes de Figueiredo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-03T18:28:16Z (GMT). No. of bitstreams: 1 Silva_IlmaAparecidaMarques_D.pdf: 2082603 bytes, checksum: f50c6d7271687b50eec8043996d4473a (MD5) Previous issue date: 2003 / Doutorado / Doutor em Matemática

Orientador: Djairo Guedes de Figueiredo / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-03T20:14:56Z (GMT). No. of bitstreams: 1 ArrazolaIriarte_EdsonAlex_D.pdf: 2278616 bytes, checksum: dca1293f6c4e26a0465b27cc58bbc735 (MD5) Previous issue date: 2004 / Resumo: Provamos a existência de um par de soluções positivas para o problema {-L:lpU = f(x, u) em O u = O sobre ao, onde L:lpu é o operador p-Laplaciano, O é um domínio limitado em JRN, com fronteira de classe C2. A não linearidade f : O x JR+ -'-+ JR é Caratheodory, "sublinear" em zero, com crescimento subcrítico, e satisfaz a condição de Ambrosetti-Rabinowitz. Na primeira parte do trabalho supomos a existência de uma super-solução estrita para provar a existência do par de soluções positivas. A existência da primeira solução é obtida via um processo de minimização clássico. A segunda solução é obtida via argumentos variacionais tais como o Teorema do Passo da Montanha e o Principio Variacional de Ekeland. Na segunda parte do trabalho, usamos técnicas de Simetrização de Schwarz, para determinar condições sobre a não-linearidade f que garantam a existência de uma super-solução estrita, primeiro no caso de uma bola e depois no caso do domínio geral O / Abstract: We prove the existence of a pair of positive solutions for the problem {-!J.pu = f(x, u) em n u = O sobre an, where !J.pu is the p-Laplacian operator, n is a bounded domain in IRN with a C2 boundary. The non-linearity f : n x IR+ -+ IR is Caratheodory, "sublinear"in zero, with subcritical growth, and satisfies the Ambrosetti- Rabinowitz condition. At the first part of the work, we suppose the existence of a strict super-solution to prove the existence of a pair of positive solutions. We obtain the existence of the first positive solution using classical minimization. The second solution is obtained using variational arguments such that The Mountain Pass Theorem and the Ekeland Variational Principle. At the second part of the work, we use Schwarz Symmetrization techniques to obtain conditions about the nonlinearity f such that, it guaranteed the existence of the strict super-solution, first in the case of the ball and then after in the case of the general domain n / Doutorado / Doutor em Matemática

Magíster en Ingeniería de Negocios con Tecnología de Información / El conocimiento en la medicina se ha acumulado en artículos de investigación científica a través del tiempo, por consiguiente, se ha generado un interés creciente en desarrollar metodologías de minería de texto para extraer, estructurar y analizar el conocimiento obtenido de grandes volúmenes de información en el menor tiempo posible. En este trabajo se presenta un una metodología que permite lograr el objetivo anterior utilizando el modelo LDA (Latent Dirichlet Allocation). Esta metodología consiste en 3 pasos: Primero, reconocer tópicos relevantes en artículos de investigación científica médica de la Revista Médica de Chile (2012 2015); Segundo, identificar e interpretar la relación entre los tópicos resultantes mediante métodos de visualización (LDAvis); Tercero, evaluar características propias de las investigaciones científicas, en este caso, el financiamiento dirigido, utilizando los dos pasos anteriores. Los resultados muestran que esta metodología resulta efectiva, no sólo para el análisis de artículos de investigación científica médica, sino que también puede ser utilizado en otros campos de la ciencia. Adicionalmente, éste método permite analizar e interpretar el estado en el que se encuentra la investigación médica a nivel nacional utilizando como referente la Revista Médica de Chile. Dentro de este contexto es importante considerar los procesos de planificación, gestión y producción de la investigación científica al interior de los Hospitales que han sido estandartes de generación del conocimiento ya que funcionan como campus universitarios de tradición e innovación. Por la razón anterior, se realizará un análisis del entorno en el sector de la salud, su estructura y la posibilidad de aplicar la metodología propuesta en este trabajo a partir del planteamiento estratégico y el modelo de negocio del Hospital Exequiel González Cortés.

In this thesis focus is on developing an online social network application with a Peer-to-Peer infrastructure motivated by BestPeer++ architecture and BATON overlay structure. BestPeer++ is a data processing platform which enables data sharing between enterprise systems. BATON is an open-sourced project which implements a peer-to-peer with a topology of a balanced tree. We designed and developed the components for users to manage their accounts, maintain friend relationships, and publish their contents with privacy control and newsfeed, notification requests in this social network- ing application. We also developed a Hashtag Recommendation system for this social net- working application. A user may invoke a recommendation procedure while writing a content. After being invoked, the recommendation pro- cedure returns a list of candidate hashtags, and the user may select one hashtag from the list and embed it into the content. The proposed ap- proach uses Latent Dirichlet Allocation (LDA) topic model to derive the latent or hidden topics of different content. LDA topic model is a well developed data mining algorithm and generally effective in analyzing text documents with different lengths. The topic model is further used to identify the candidate hashtags that are associated with the texts in the published content through their association with the derived hidden top- ics. We considered different methods of recommendation approach for the pro- cedure to select candidate hashtags from different content. Some methods consider the hashtags contained in the contents of the whole social net- work or of the user self. These are content-based recommendation tech- niques which matching user’s own profile with the profiles of items.. Some methods consider the hashtags contained in contents of the friends or of the similar users. These are collaborative filtering based recommendation techniques which considers the profiles of other users in the system. At the end of the recommendation procedure, the candidate hashtags are or- dered by their probabilities of appearance in the content and returned to the user. We also conducted experiments to evaluate the effectiveness of the hashtag recommendation approach. These experiments were fed with the tweets published in Twitter. The hit-rate of recommendation is measured in these experiments. Hit-rate is the percentage of the selected or relevant hashtags contained in candidate hashtags. Our experiment results show that the hit-rate above 50% is observed when we use a method of recommendation approach independently. Also, for the case that both similar user and user preferences are considered at the same time, the hit-rate improved to 87% and 92% for top-5 and top-10 candidate recommendations respectively.

The Dirichlet process is perhaps the most popular prior used in the nonparametric Bayesian inference. This prior which is placed on the space of probability distributions has conjugacy property and asymptotic consistency. In this thesis, our concentration is on applying this nonparametric Bayesian inference on the Tukey depth and Tukey median. Due to the complexity of the distribution of Tukey median, we use this nonparametric Bayesian inference, namely the Lo’s bootstrap, to approximate the distribution of the Tukey median. We also compare our results with the Efron’s bootstrap and Rubin’s bootstrap. Furthermore, the existing asymptotic theory for the Tukey median is reviewed. Based on these existing results, we conjecture that the bootstrap sample Tukey median converges to the same asymp- totic distribution and our simulation supports the conjecture that the asymptotic consistency holds.

Les travaux présentés dans cette thèse concernent l'étude d'opérateurs sur certains espaces de Banach de séries de Dirichlet. Nous étudions principalement les opérateurs de composition sur deux familles d'espaces de Bergman. Dans un premier temps, nous donnons des estimations de la norme essentielle des opérateurs de composition sur les espaces de Hardy de séries de Dirichlet à l'aide de deux points de vue : les fonctions de comptage déjà étudiées dans ce cadre et les mesures de Carleson que nous définissons. Dans un second temps nous étudions deux familles d'espaces de Bergman de séries de Dirichlet. Le premier type d'espace est associé au "demi-plan" : on montre que les propriétés d'injection vis-à-vis des espaces de Hardy ne sont pas les mêmes que dans le cas du disque unité et nous prouvons des résultats similaires à ceux obtenus dans la première partie concernant la norme essentielle des opérateurs de composition. Le deuxième type d'espace est associé au polydisque infini : à l'aide d'un résultat d'hypercontractivité nous généralisons des résultats classiques du disque unité sur ces espaces puis nous étudions la continuité des opérateurs de composition sur ces espaces. Nous finissons cette thèse par la définition et l'étude d'espaces de Hardy-Orlicz de séries de Dirichlet. / In this thesis we study operators on some Banach spaces of Dirichlet series. We mainly study composition operators on two families of Bergman spaces. First we give estimates of the essential norm of composition operators on Hardy spaces of Dirichlet series with help of the Nevanlinna couting function and the Carleson's measures. Second we define and study two families of Bergman spaces of Dirichlet series : we compare these new spaces and the Hardy spaces of Dirichlet series and obtain results about boundedness and compactness of compostion operators in this framework. Finally we define and study the Hardy-Orlicz spaces of Dirichlet series.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22982号 / 理博第4659号 / 新制||理||1669(附属図書館) / 京都大学大学院理学研究科数学・数理解析専攻 / (主査)教授 熊谷 隆, 教授 長谷川 真人, 小澤 登高 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

TOPICAL ANALYSIS OF FAKE NEWS 4 Abstract Since the 2016 US presidential campaign of Donald Trump, the term "fake news" has permeated mainstream discourse. The proliferation of disinformation and false narratives on social media platforms has caused concern in security circles in both the United States and European Union. Combining latent Dirichlet allocation, a machine learning method for text mining, with themes on topical analysis, ideology and social identity drawn from Critical Discourse theory, this thesis examines the elaborate fake news environments of two well-known English language websites: InfoWars and Sputnik News. Through the exploration of the ideologies and social representations at play in the larger thematic structure of these websites, a picture of two very different platforms emerges. One, a white dominant, somewhat isolationist counterculture mindset that promotes a racist and bigoted view of the world. Another, a more subtle world order-making perspective intent on reaching people in the realm of the mundane. Keywords: fake news, Sputnik, InfoWars, topical analysis, latent Dirichlet allocation Od americké prezidentské kampaně Donalda Trumpa z roku 2016, termín "fake news" (doslovně falešné zprávy) pronikl do mainstreamového diskurzu. Šíření dezinformací a falešných zpráv na platformách...

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The starting point of the thesis is the {\it universality} property of the Riemann Zeta-function $\zeta(s)$ which was proved by Voronin in 1975: {\it Given a positive number $\varepsilon>0$ and an analytic non-vanishing function $f$ defined on a compact subset $\mathcal{K}$ of the strip $\left\{s\in\mathbb{C}:1/2 < \Re s< 1\right\}$ with connected complement, there exists a real number $\tau$ such that \begin{align}\label{continuous} \max\limits_{s\in \mathcal{K}}|\zeta(s+i\tau)-f(s)|<\varepsilon. \end{align} } In 1980, Reich proved a discrete analogue of Voronin’s theorem, also known as {\it discrete universality theorem} for $\zeta(s)$: {\it If $\mathcal{K}$, $f$ and $\varepsilon$ are as before, then \begin{align}\label{discretee} \liminf\limits_{N\to\infty}\dfrac{1}{N}\sharp\left\{1\leq n\leq N:\max\limits_{s\in \mathcal{K}}|\zeta(s+i\Delta n)-f(s)|<\varepsilon\right\}>0, \end{align} where $\Delta$ is an arbitrary but fixed positive number. } We aim at developing a theory which can be applied to prove the majority of all so far existing discrete universality theorems in the case of Dirichlet $L$-functions $L(s,\chi)$ and Hurwitz zeta-functions $\zeta(s;\alpha)$, where $\chi$ is a Dirichlet character and $\alpha\in(0,1]$, respectively. Both of the aforementioned classes of functions are generalizations of $\zeta(s)$, since $\zeta(s)=L(s,\chi_0)=\zeta(s;1)$, where $\chi_0$ is the principal Dirichlet character mod 1. Amongst others, we prove statement (2) where instead of $\zeta(s)$ we have $L(s,\chi)$ for some Dirichlet character $\chi$ or $\zeta(s;\alpha)$ for some transcendental or rational number $\alpha\in(0,1]$, and instead of $(\Delta n)_{n\in\mathbb{N}}$ we can have: \begin{enumerate} \item \textit{Beatty sequences,} \item \textit{sequences of ordinates of $c$-points of zeta-functions from the Selberg class,} \item \textit{sequences which are generated by polynomials.} \end{enumerate} In all the preceding cases, the notion of {\it uniformly distributed sequences} plays an important role and we draw attention to it wherever we can. Moreover, for the case of polynomials, we employ more advanced techniques from Analytic Number Theory such as bounds of exponential sums and zero-density estimates for Dirichlet $L$-functions. This will allow us to prove the existence of discrete second moments of $L(s,\chi)$ and $\zeta(s;\alpha)$ on the left of the vertical line $1+i\mathbb{R}$, with respect to polynomials. In the case of the Hurwitz Zeta-function $\zeta(s;\alpha)$, where $\alpha$ is transcendental or rational but not equal to $1/2$ or 1, the target function $f$ in (1) or (2), where $\zeta(\cdot)$ is replaced by $\zeta(\cdot;\alpha)$, is also allowed to have zeros. Until recently there was no result regarding the universality of $\zeta(s;\alpha)$ in the literature whenever $\alpha$ is an algebraic irrational. In the second half of the thesis, we prove that a weak version of statement \eqref{continuous} for $\zeta(s;\alpha)$ holds for all but finitely many algebraic irrational $\alpha$ in $[A,1]$, where $A\in(0,1]$ is an arbitrary but fixed real number. Lastly, we prove that the ordinary Dirichlet series $\zeta(s;f)=\sum_{n\geq1}f(n)n^{-s}$ and $\zeta_\alpha(s)=\sum_{n\geq1}\lfloor P(\alpha n+\beta)\rfloor^{-s}$ are hypertranscendental, where $f:\mathbb{N}\to\mathbb{C}$ is a {\it Besicovitch almost periodic arithmetical function}, $\alpha,\beta>0$ are such that $\lfloor\alpha+\beta\rfloor>1$ and $P\in\mathbb{Z}[X]$ is such that $P(\mathbb{N})\subseteq\mathbb{N}$. / Der Ausgangspunkt dieser Dissertation ist die folgende {\it Universalit\"atseigenschaft} der Riemannschen Zetafunktion $\zeta(s)$, die von Voronin 1975 nachgewiesen wurde: {\it Zu gegebenem $\varepsilon>0$ und einer analytischen nullstellenfreien Funktion $f$, die auf einer kompakten Teilmenge $\mathcal{K}$ des Streifens $\left\{s\in\mathbb{C}:1/2 < \Re s< 1\right\}$ mit zusammenh\"angendem Komplement definiert ist, existiert eine reelle Zahl $\tau$, so dass \begin{align}\label{continuouus} \max\limits_{s\in \mathcal{K}}|\zeta(s+i\tau)-f(s)|<\varepsilon.\tag*{(1)} \end{align} } Im Jahr 1980 bewies Reich folgendes diskrete Analogon des Voroninschen Satzes, welches auch als {\it diskretes Universalit\"atstheorem} f\"ur $\zeta(s)$ bekannt ist: {\it Sind $\mathcal{K}$, $f$ und $\varepsilon$ wie oben, so gilt \begin{align}\label{discreteeee} \liminf\limits_{N\to\infty}\dfrac{1}{N}\sharp\left\{1\leq n\leq N:\max\limits_{s\in \mathcal{K}}|\zeta(s+i\Delta n)-f(s)|<\varepsilon\right\}>0,\tag*{(2)} \end{align} wobei $\Delta$ eine beliebige, aber fest gew\"ahlte positive reelle Zahl bezeichnet. } Unser Ziel ist die Entwicklung einer Theorie, welche die Mehrheit der bislang bewiesenen diskreten Universalit\"atstheoreme im Fall Dirichletscher $L$-Funktionen $L(s,\chi)$ und Hurwitzscher Zetafunktionen $\zeta(s;\alpha)$ (wobei $\chi$ ein Dirichlet-Charakter ist und $\alpha\in(0,1]$) umfasst. Beide genannten Funktionenklassen verallgemeinern $\zeta(s)$, denn $\zeta(s)=L(s,\chi_0)=\zeta(s;1)$, wobei $\chi_0$ der Hauptcharakter modulo 1 ist. Neben anderen Resultaten beweisen wir Aussage (2) mit $L(s,\chi)$ f\"ur einen beliebigen Dirichlet-Charakter $\chi$ bzw. $\zeta(s;\alpha)$ f\"ur ein transzendentes oder rationales $\alpha\in(0,1]$ anstelle von $\zeta(s)$ sowie $(\Delta n)_{n\in\mathbb{N}}$ ersetzt durch eine der nachstehenden Folgen: \begin{enumerate} \item \textit{Beatty-Folgen,} \item \textit{Folgen von Imagin\"arteilen der $c$-Punkte einer beliebigen Zetafunktion der Selbergklasse,} \item \textit{Folgen, die durch ein Polynom generiert werden.} \end{enumerate} In all diesen F\"allen spielt der Begriff einer {\it gleichverteilten Folge} eine wichtige Rolle, und wir schenken diesem Aspekt besondere Beachtung im Folgenden. Speziell f\"ur den Fall der Polynome benutzen wir weitere fortgeschrittene Techniken der Analytischen Zahlentheorie, wie besipielsweise Schranken f\"ur Exponentialsummen und Nullstellen-Dichtigkeitsabsch\"atzungen f\"ur Dirichletsche $L$-Funktionen. Dies erlaubt uns, die Existenz gewisser diskreter quadratischer Momente f\"ur $L(s,\chi)$ und $\zeta(s;\alpha)$ links der vertikalen Geraden $1+i\mathbb{R}$ im Polynom-Fall zu beweisen. Im Fall der Hurwitzschen Zetafunktion $\zeta(s;\alpha)$, wobei $\alpha$ transzendent oder rational, aber ungleich $1/2$ oder 1 ist, kann die zu approximierende Funktion $f$ in (1) oder (2), wobei $\zeta(\cdot)$ durch $\zeta(\cdot;\alpha)$ zu ersetzen ist, sogar Nullstellen besitzen. Bis vor kurzem waren hinsichtlich der Universalit\"at von $\zeta(s;\alpha)$ in der Literatur f\"ur algebraisch-irrationale $\alpha$ keine Ergebnisse erzielt worden. Im zweiten Teil der Dissertation beweisen wir eine schwache Version der Aussage \eqref{continuous} f\"ur $\zeta(s;\alpha)$ f\"ur alle algebraisch-irrationalen $\alpha\in[A,1]$ bis auf h\"ochstens endlich viele Ausnahmen, wobei $A\in(0,1]$ eine beliebige, aber fest gew\"ahlte reelle Zahl ist. Schlie\ss{}lich weisen wir die Hypertranszendenz der gew\"ohnlichen Dirichlet-Reihen $\zeta(s;f)=\sum_{n\geq1}f(n)n^{-s}$ und $\zeta_\alpha(s)=\sum_{n\geq1}\lfloor P(\alpha n+\beta)\rfloor^{-s}$ nach, wobei $f:\mathbb{N}\to\mathbb{C}$ irgendeine {\it Besicovitch-fastperiodische zahlentheoretische Funktion} ist, $\alpha,\beta>0$ der Ungleichung $\lfloor\alpha+\beta\rfloor>1$ gen\"ugt und $P\in\mathbb{Z}[X]$ die Bedingung $P(\mathbb{N})\subseteq\mathbb{N}$ erf\"ullt.