A Dynamic Model for Double Bounded Time Series With Chaotic Driven Conditional Averages

In this work we introduce a class of dynamic models for time series taking values on the unit interval. The proposed model follows a generalized linear model approach where the random component, conditioned on the past information, follows a beta distribution, while the conditional mean specification may include covariates and also an extra additive term given by the iteration of a map that can present chaotic behavior. The resulting model is very flexible and its systematic component can accommodate short and long range dependence, periodic behavior, laminar phases, etc. We derive easily verifiable conditions for the stationarity of the proposed model, as well as conditions for the law of large numbers and a Birkhoff-type theorem to hold. A Monte Carlo simulation study is performed to assess the finite sample behavior of the partial maximum likelihood approach for parameter estimation in the proposed model. Finally, an application to the proportion of stored hydroelectrical energy in Southern Brazil is presented

Model Performance as an Estimator of Language Complexity

Quantifying the complexity of a natural language is a difficult task on its own and comparing two or more languages typically requires establishing a reference point and determining the biases and context of the languages being compared. I propose a new metric for unbiasedly quantifying the complexity of a language in a way that allows for easy comparison between languages. I use a variety of common machine learning solutions for tasks such as part- of-speech tagging and language modeling, then analyze the learning ability of these models as parameters are adjusted. I then use the evaluation metrics from these tasks to compare similar models trained on different languages. I find that the evaluation metrics accuracy and perplexity mimic the behavior of four metrics found in linguistics literature and can be used to compare relative complexities

A Study of the Intestinal Fauna of the Frog

This 23 page thesis describes experiments conducted to analyze the different types of parasites found in the digestive tracts of frogs

On the behavior of the DFA and DCCA in trend-stationary processes

In this work, we develop the asymptotic theory of the Detrended Fluctuation Analysis (DFA) and Detrended Cross-Correlation Analysis (DCCA) for trend-stationary stochastic processes without any assumption on the specific form of the underlying distribution. All results are presented and derived under the general framework of potentially overlapping boxes for the polynomial fit. We prove the stationarity of the DFA and DCCA, viewed as stochastic processes, obtain closed forms for moments up to second order, including the covariance structure for DFA and DCCA and a miscellany of law of large number related results. Our results generalize and improve several results presented in the literature. To verify the behavior of our theoretical results in small samples, we present a Monte Carlo simulation study and an empirical application to econometric time series

THE FECAL FLORA OF VARIOUS STRAINS OF MICE. ITS BEARING ON THEIR SUSCEPTIBILITY TO ENDOTOXIN

Adult mice from seven different colonies were studied with regard to (a) the numbers and types of bacteria that could be cultivated from their stools; (b) their resistance to the lethal effect of endotoxins prepared from three strains of Gram-negative bacilli. See PDF for Structure In six of the seven colonies, the stools yielded large numbers of various types of lactobacilli, enterococci, and Gram-negative bacilli. Most animals in these colonies died within 48 hours following injection of endotoxin. The other mouse colony (NCS) has been maintained for the past three years at the Rockefeller Institute under exacting sanitary conditions; it is free of many types of common mouse pathogens. The stool flora of NCS mice yielded very large numbers of viable lactobacilli (109 per gm), representing at least three different morphological types. In contrast, it contained only few enterococci and Gram-negative bacilli (less than 106 per gm). Moreover, E. coli, Proteus sp., and Pseudomonas sp. could not be recovered from the stools under normal conditions. NCS mice proved resistant to the lethal effect of endotoxins. These characteristics of the NCS colony prevailed whether the animals were housed continuously in individual cages on wire grids, or grouped continuously in large cages with wood shavings as litter. However, the composition of the bacterial flora could be rapidly and profoundly altered by a variety of unrelated disturbances such as sudden changes in environmental temperature, crowding in cages, handling of the animals, administration of antibacterial drugs, etc. The first effect of the change was a marked decrease in the numbers of lactobacilli and commonly an increase in the numbers of Gram-negative bacilli and enterococci. When tested 3 weeks after these disturbances some NCS animals were found to have become susceptible to the lethal effects of endotoxin

Hackathons como estratégia para inovação aberta: insights de eventos no Brasil e no Canadá

Purpose: The present study aims to analyze the elements and practices used in hackathons for software development and how they contribute to the success of the events. Design/methodology/approach: Through a qualitative and exploratory approach, a multiple case study was used to analyze two hackathon events in Brazil and Canada organized by a multinational technology company. Data collection was carried out through semi-structured interviews and document analysis. Data analysis was conducted using content analysis.Findings: The results illustrate that the participation of people with different profiles and knowledge is important for hackathon results. The support provided to participants and the choice of the proposed challenge affect participants’ perception of the event and the solutions developed.Research limitations/implications: As this is a multiple case study of a qualitative nature, it is infeasible to establish generalizations based on the results, and it is only possible to present evidence and proposals based on the specific cases.Practical implications: Proposed best practices to be followed in organizing hackathons, specifically in the context of software development.Originality/value: Few studies treat the subject of hackathons, and rarer still consider different countries to analyze the enabling elements based on different structures and their contributions to innovation. The development of hackathons as an alternative for innovation in the software area is also investigated.Objetivo: O presente estudo tem por objetivo analisar os elementos capacitadores utilizados em hackathons de desenvolvimento de software e como eles contribuíram para o sucesso dos eventos.Método: Mediante abordagem qualitativa e exploratória, o método empregado foi o estudo de casos múltiplos, tendo como unidades de análise dois eventos no formato hackathon, organizados por empresa multinacional de tecnologia no Brasil e Canadá. A coleta de dados foi desenvolvida por entrevistas semiestruturadas e análise documental. A análise dos dados foi conduzida com a técnica da análise de conteúdo.Resultados: Os resultados mostram que a participação de pessoas com perfis e conhecimentos diferentes é importante para os resultados de um hackathon. O suporte fornecido aos participantes e a escolha do desafio proposto são aspectos que afetam a percepção dos participantes sobre o evento, assim como exercem influência nas soluções desenvolvidas.Limitações da pesquisa: Por se tratar de um estudo de casos múltiplos e de caráter qualitativo, não é viável estabelecer generalizações com base nos resultados do estudo, sendo apenas viável apresentar evidências e propostas com base nos casos concretos estudados.Implicações práticas: Proposição de melhores práticas a serem seguidas para a organização de hackathons, em específico no contexto das maratonas para desenvolvimento de soluções.Originalidade: Poucos estudos são direcionados para a aplicação de hackathons, e mais raros são aqueles desenvolvidos considerando diferentes países para análise dos elementos capacitadores baseados em estruturas distintas e suas contribuições na inovação. Investiga-se o desenvolvimento de hackathons como alternativa para inovação na área de software