The different asymptotic regimes of nearly unstable autoregressive processes

We extend classical results about the convergence of nearly unstable AR(p) processes to the infinite order case. To do so, we proceed as in recent works about Hawkes processes by using limit theorems for some well chosen geometric sums. We prove that when the coefficients sequence has a light tail, infinite order nearly unstable autoregressive processes behave as Ornstein-Uhlenbeck models. However, in the heavy tail case, we show that fractional diffusions arise as limiting laws for such processes.Comment: 16 page

Limit theorems for nearly unstable Hawkes processes

Because of their tractability and their natural interpretations in term of market quantities, Hawkes processes are nowadays widely used in high-frequency finance. However, in practice, the statistical estimation results seem to show that very often, only nearly unstable Hawkes processes are able to fit the data properly. By nearly unstable, we mean that the $L^1$ norm of their kernel is close to unity. We study in this work such processes for which the stability condition is almost violated. Our main result states that after suitable rescaling, they asymptotically behave like integrated Cox-Ingersoll-Ross models. Thus, modeling financial order flows as nearly unstable Hawkes processes may be a good way to reproduce both their high and low frequency stylized facts. We then extend this result to the Hawkes-based price model introduced by Bacry et al. [Quant. Finance 13 (2013) 65-77]. We show that under a similar criticality condition, this process converges to a Heston model. Again, we recover well-known stylized facts of prices, both at the microstructure level and at the macroscopic scale.Comment: Published in at http://dx.doi.org/10.1214/14-AAP1005 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Limit theorems for nearly unstable Hawkes processes: Version with technical appendix

Because of their tractability and their natural interpretations in term of market quantities, Hawkes processes are nowadays widely used in high frequency finance. However, in practice, the statistical estimation results seem to show that very often, only "nearly unstable Hawkes processes" are able to fit the data properly. By nearly unstable, we mean that the L1 norm of their kernel is close to unity. We study in this work such processes for which the stability condition is almost violated. Our main result states that after suitable rescaling, they asymptotically behave like integrated Cox Ingersoll Ross models. Thus, modeling financial order flows as nearly unstable Hawkes processes may be a good way to reproduce both their high and low frequency stylized facts. We then extend this result to the Hawkes based price model introduced by Bacry et al. We show that under a similar criticality condition, this process converges to a Heston model. Again, we recover well known stylized facts of prices, both at the microstructure level and at the macroscopic scale

Larval learning affects adult nest-mate recognition in the ant Aphaenogaster senilis

Relatório de estágio do mestrado em Ensino da Educação Física nos Ensinos Básico e Secundário, apresentada à Faculdade de Ciências do Desporto e Educação Física da Universidade de CoimbraO Mestrado em Ensino da Educação Física nos Ensino Básico e Secundário da Faculdade de Ciências do Desporto e Educação Física da Universidade de Coimbra, engloba uma componente prática que permite a profissionalização, através do aprofundamento alargado dos conhecimentos de intervenção profissional na área de Educação Física. O presente documento denominado Relatório Final do Estágio Pedagógico, foi produzido com o propósito de descrever todo o processo de aprendizagem realizado ao longo da nossa intervenção pedagógica na Escola Básica 2,3/S Dr. Daniel de Matos - Vila Nova de Poiares, com a turma do 9º B no presente ano letivo. Deste modo, todo este documento contempla um conjunto de tarefas inerentes ao processo de ensino-aprendizagem que permite a organização, realização, avaliação e reflexão de todo o processo pedagógico. O relatório apresenta-se estruturado de acordo com as atividades desenvolvidas, iniciando com o primeiro capítulo, onde refletimos sobre Expectativas e Opções Iniciais em Relação ao Estágio. Seguimos com a Análise Reflexiva da Prática Pedagógica, mais precisamente no que respeita ao Planeamento; Realização e Avaliação. Passamos para a reflexão da Atitude Ético-Profissional, à Justificação das Opções Tomadas, e uma Síntese Conclusiva no âmbito de toda a nossa intervenção pedagógica. Por último e não menos importante, temos o segundo capítulo, referente ao tema problema - A influência das aulas de educação física no âmbito do programa “Toca a Mexer” na Coordenação Motora de crianças com NEE, que iremos tratar mais adiante. Palavras-chave: Reflexão. Docência. Competências. Pratica Pedagógica. Coordenação Motora. Abstract The Master of Education Physical Education in Elementary and Secondary Education of the Faculty of Sport Sciences and Physical Education, University of Coimbra, includes a practical component that enables professional, by deepening broadened the professional intervention of knowledge in Physical Education. This document called Final Report of the Teacher Training, was produced for the purpose of describing the whole process of learning done throughout our educational intervention in Primary School 2.3 / S Dr. Daniel de Matos - Vila Nova de Poiares, with 9th class B in this school year. Thus, throughout this document includes a set of tasks of teaching-learning process that allows the organization, implementation, evaluation and reflection of the entire educational process. The report is structured according to the activities, starting with the first chapter, where we reflect on expectations and Start Options in Relation to Stage. We follow with the Reflective Analysis of Teaching Practice, specifically with regard to planning; Achievement and Assessment. We passed to the reflection of Ethical and Professional Attitude, the justification of the options sockets, and a Conclusive Synthesis under all our pedagogical intervention. Last but not least, we have the second chapter, referring to the theme problem - The influence of physical education classes under the program "Play to Stir"on the Motor Coordination of children with SEN, which we will address later

Análisis comparativo del indicador del desempeño fiscal de los departamentos categoría 4 y 1 de Colombia vigencia 2016

Trabajo de InvestigaciónUn análisis comparativo del indicador del desempeño fiscal de los departamentos categoría 4 y 1, con el fin de identificar la capacidad de ahorro, inversión, endeudamiento, nivel de ingresos que corresponden a recursos propios, nivel de dependencia de las transferencias, y el nivel de autofinanciación del gasto. Con el fin de identificar las razones por la que estos departamentos se ubicaron en esas respectivas categorías para el año 2016.1. Resumen. 2. Introducción 3. Marco teórico. 4. Marco Legal. 5. Metodología. 6. Resultados. 7. Conclusiones. 8. Recomendaciones.PregradoEconomist

Enhanced activation of and increased production of matrix metalloproteinase-9 by human blood monocytes upon adhering to carbamylated collagen

AbstractCarbamylation refers to chemical modification of protein side chains by cyanate derived e.g. from urea. It alters their structural and functional properties. We have studied the influence of the carbamylation of type I collagen in vitro on its interactions with elutriated human monocytes, and its potential role in atherosclerosis. Adhesion of monocytes onto carbamylated collagen was significantly enhanced compared to native collagen. There was no change in superoxide anion production. On the other hand, there was an increase in the production and the activation of matrix metalloproteinase-9. No effect was found on tissue inhibitor of metalloproteinase-1 production. Thus, the presence of carbamylated collagen may stimulate the remodelling of extracellular matrix mediated by activated monocytes. Such alterations may contribute to enhanced atherosclerosis in renal insufficiency, a pathological condition associated with elevated levels of carbamylation

L’étude des pratiques médicales : l’écran de la sociologie des professions

The sociology of medicine is constituted from the model of the American sociology of professions, which has emerged in the 1930s (a model that has also marked the historians of medicine). This article traces the context in which the sociology of professions emerged and later became institutionalized in the United States, notably from the works by Talcott Parsons, Everett Hughes and Eliot Freidson. Even now, questionings about medical practices are strongly influenced by these authors, while the sociology of professions include debated and debatable postulates and important blind spots, such as the link between State and medicine.La sociologie de la médecine s’est constituée à partir du modèle de la sociologie américaine des professions qui a émergé au cours des années 1930 (modèle qui a aussi marqué les historiens de la médecine). Cet article retrace le contexte dans lequel a émergé puis s’est institutionnalisé la sociologie des professions aux États-Unis à partir notamment des travaux des Talcott Parsons, Everett Hughes et Eliot Freidson. Aujourd’hui encore les questionnements portés sur les pratiques médicales en subissent fortement l’empreinte alors même que la sociologie des professions comporte des postulats discutés et discutables et des points aveugles importants, tel le lien entre l’État et la médecine.A sociologia da medicina é feita a partir do modelo da sociologia americana das profissões que surgiu no decorrer da década de 1930 (modelo que também marcou os historiadores da medicina). O artigo traz de volta o contexto em que a sociologia das profissões surgiu e, em seguida, quando foi institucionalizada nos Estados Unidos, sobretudo a partir dos trabalhos de Talcott Parsons, Everett Hughes e Eliot Freidson. Ainda hoje os questionamentos realizados em práticas médicas são fortemente influenciados por essa empreitada, enquanto a sociologia das profissões comporta suposições discutidas e discutíveis e pontos cegos importantes, tais como a ligação entre o Estado e a medicina