El género narrativo.

ODE pensado para alumnos de primer curso de educación secundaria

El género lírico.

ODE pensado para alumnos de primer curso de educación secundaria

El género dramático.

ODE pensado para alumnos de primer curso de educación secundaria

Ensemble transform Kalman-Bucy filters

Two recent works have adapted the Kalman–Bucy filter into an ensemble setting. In the first formulation, the ensemble of perturbations is updated by the solution of an ordinary differential equation (ODE) in pseudo-time, while the mean is updated as in the standard Kalman filter. In the second formulation, the full ensemble is updated in the analysis step as the solution of single set of ODEs in pseudo-time. Neither requires matrix inversions except for the frequently diagonal observation error covariance. We analyse the behaviour of the ODEs involved in these formulations. We demonstrate that they stiffen for large magnitudes of the ratio of background error to observational error variance, and that using the integration scheme proposed in both formulations can lead to failure. A numerical integration scheme that is both stable and is not computationally expensive is proposed. We develop transform-based alternatives for these Bucy-type approaches so that the integrations are computed in ensemble space where the variables are weights (of dimension equal to the ensemble size) rather than model variables. Finally, the performance of our ensemble transform Kalman–Bucy implementations is evaluated using three models: the 3-variable Lorenz 1963 model, the 40-variable Lorenz 1996 model, and a medium complexity atmospheric general circulation model known as SPEEDY. The results from all three models are encouraging and warrant further exploration of these assimilation techniques.

Discontinuous local semiflows for Kurzweil equations leading to LaSalle`s invariance principle for differential systems with impulses at variable times

In this paper, we consider an initial value problem for a class of generalized ODEs, also known as Kurzweil equations, and we prove the existence of a local semidynamical system there. Under certain perturbation conditions, we also show that this class of generalized ODEs admits a discontinuous semiflow which we shall refer to as an impulsive semidynamical system. As a consequence, we obtain LaSalle`s invariance principle for such a class of generalized ODEs. Due to the importance of LaSalle`s invariance principle in studying stability of differential systems, we include an application to autonomous ordinary differential systems with impulse action at variable times. (C) 2011 Elsevier Inc. All rights reserved.

Da criação à recriação: o percurso intertextual e metalinguístico em O ano da morte de Ricardo Reis, de José Saramago

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Local classification of singular hexagonal 3-webs with holomorphic Chern connection form and infinitesimal symmetries

Implicit ODE, cubic in derivative, generically has no infinitesimal symmetries even at regular points with distinct roots. Cartan showed that at regular points, ODEs with hexagonal 3-web of solutions have symmetry algebras of the maximal possible dimension 3. At singular points such a web can lose all its symmetries. In this paper we study hexagonal 3-webs having at least one infinitesimal symmetry at singular points. In particular, we establish sufficient conditions for the existence of non-trivial symmetries and show that under natural assumptions such a symmetry is semi-simple, i.e. is a scaling in some coordinates. Using the obtained results, we provide a complete classification of hexagonal singular 3-web germs in the complex plane, satisfying the following two conditions: 1) the Chern connection form is holomorphic at the singular point, 2) the web admits at least one infinitesimal symmetry at this point. As a by-product, a classification of hexagonal weighted homogeneous 3-webs is obtained.

Construção exata de sólitons de Hopf

Pós-graduação em Física - IFT

Il Lessico d’amore nei primi tre libri delle Odi di Orazio

Il presente studio si è posto come obiettivo quello di redigere un lessico dei termini d’amore nella poesia di Orazio, e, specificamente, dei lemmi presenti nei primi tre libri delle Odi. L’interesse per la lirica del Venosino ci ha indotti ad affrontarne la lettura non solo considerando quelle che sono le tematiche diremo topiche della sua poetica ( modus, angulus, mors, tempus, cura, solo per citare quelle più significative ), ma anche quelle meno note, quale appunto il tema dell’amore, oggetto di questo lavoro. Si è proceduto così all’analisi di ogni singolo libro di ogni ode, catalogandone ed analizzandone rispettivamente tutte le occorrenze di quei termini che abbiamo ritenuto essere propri del lessico amoroso. Il commento ad ogni libro è stato supportato dagli studi di Nisbet-Hubbard per il primo ed il secondo libro delle Odi ( cfr. R.G.M. Nisbet-M. Hubbard, A commentary on Horace: Odes Book 1, Oxford 1970; R.G.M. Nisbet-M. Hubbard, A commentary on Horace: Odes Book 2, Oxford 1978 ) e Nisbet-Rudd per il terzo ( cfr. R.G.M. Nisbet-Rudd, A commentary on Horace: Odes Book 3, Oxford, 2003 ). Trattandosi di un lessico è stato altresì fondamentale il contributo dell’ Index uerborum amatorium ( Cfr. R. Pichon, De sermone amatorio apud Latinos elegiarum scriptores, Paris 1902 ) e del ThLL. Si è infine proceduto ad individuare quei termini maggiormente significativi nell’ambito della poesia d’amore in generale, il cui riflesso è presente anche nella poesia oraziana, con una particolare attenzione al rapporto che intercorre tra Orazio e la tradizione neoterica ed elegiaca e al lessico dei colori, che vanta numerose occorrenze nella poesia d’amore, soprattutto in riferimento alla bellezza muliebre e maschile e che quindi appare di rilevante importanza per comprendere l’estetica della poesia oraziana nel ritrarre la forma degli amanti che popolano i suoi più celebri versi d’amore.

The Devil’s Calculus: Mathematical Models of Civil War

In spite of the movement to turn political science into a real science, various mathematical methods that are now the staples of physics, biology, and even economics are thoroughly uncommon in political science, especially the study of civil war. This study seeks to apply such methods - specifically, ordinary differential equations (ODEs) - to model civil war based on what one might dub the capabilities school of thought, which roughly states that civil wars end only when one side’s ability to make war falls far enough to make peace truly attractive. I construct several different ODE-based models and then test them all to see which best predicts the instantaneous capabilities of both sides of the Sri Lankan civil war in the period from 1990 to 1994 given parameters and initial conditions. The model that the tests declare most accurate gives very accurate predictions of state military capabilities and reasonable short term predictions of cumulative deaths. Analysis of the model reveals the scale of the importance of rebel finances to the sustainability of insurgency, most notably that the number of troops required to put down the Tamil Tigers is reduced by nearly a full order of magnitude when Tiger foreign funding is stopped. The study thus demonstrates that accurate foresight may come of relatively simple dynamical models, and implies the great potential of advanced and currently unconventional non-statistical mathematical methods in political science.

Tras las huellas de Horacio : Carm.,1,2 y 4, 15

Hor., en Carm., 1, 2 y 4, 15 recoge una serie de referencias a dioses importantes para la familia adoptiva de Octaviano y para el propio gobernante, que han sido tradicionalmente analizadas e interpretadas desde un punto de vista interno: su presencia se explicaría en función de su relación con la gens Iulia. El punto de vista que quiero ofrecer en mi trabajo es complementario a éste: a partir de un análisis externo de las referencias a estos dioses, creo que su presencia se puede explicar en función de los templos en los que "habitaban" en Roma, del lugar donde estos templos se encontraban y de las representaciones icónicas que servían a su culto. Al mismo tiempo, la nueva relación que establezco entre 1,2 y 4, 15 aporta evidencias para una comprensión distinta de la segunda edición de la poesía lírica de Horacio, la que se presentó con el libro 4

El Proemio del Libro IV de las Odas de Horacio

Este artículo se ocupa de la oda 4, 1 de Horacio. En primer lugar, el autor considera que esta oda posee un claro valor programático: en este libro se encontrará nuevamente poesía amorosa, a pesar de lo sostenido en los versos iniciales de la oda 3, 26 Y en la primera epístola. Sigue luego un comentario detallado de la oda, en el que se propone confirmar y ampliar tal interpretación. Se desarrolla especialmente el sentido de la súplica a Venus y el papel que cumple en tal súplica la juventud y riqueza de Paulo Máximo. En los dos últimos parágrafos se discuten la estructura del poema y su clasificación como apopompé, recusatio o renuntiatio amoris; también la característica que diferencia, aun considerando el poema como renuntiatio amoris, a Horacio de los poetas elegíacos

De Horacio a Lucano : Operatividad poética de la figura del Expiator en la configuración de Catón de Utica

En este trabajo analizamos cómo los Epodos VII y XVI y las Odas III, 3 y IV, 15 de la obra de Horacio, pasando por la descripción del suicidio de Catón que Séneca hace en su tratado De providentia, son utilizados y reformulados por Lucano en Pharsalia para configurar su particular versión de Cato Uticiencis. Lucano subvierte las imágenes e invierte el trayecto poético de la figura del expiator que Horacio desarrolla a lo largo de su obra para logar perturbadora Weltanschauung que permea su poema

Horacio y la recusatio de la elegía amorosa

Dentro del género lírico, Horacio trata de diferenciar de su propia lírica amatoria la especie erótica elegíaca de un Tibulo o un Propercio; lo hace con dos recursos de raigambre calimaquea empleados con profusión por otros poetas augusteos: la recusatio y la excusatio presentes en Odas I, 33; II, 9 y I, 38

Horacio, Vir Mercurialis

Examinamos la configuración de Mercurio en la poesía horaciana. Si bien es heredada en parte de la tradición homérica e hímnica griega, su presencia en el poeta de Venusa excede el arquetipo helénico, que es recepcionado depurándose de ciertos rasgos, atenuados y nobilizados ya desde las Sátiras, para culminar en las Odas, o bien adquiriendo algunos rasgos nuevos motivados por sus experiencias individuales, u otros de insospechada dimensión política en vinculación con Augusto (Oda I, 2)