Non linear dynamics in US macroeconomic time series

This paper investigates whether the inherent non stationarity of the US macroeconomic time series may be entirely explained by simple stochastic non linear models (like GARCH). Applying the numerical tools of the analysis of dynamical systems to long time series for the US, we reject the hypothesis that the uncorrelated and homoscedastic residuals of the estimated GARCH models contain no structure. Contrary to the theories that attribute the source of the irregular behaviour of the economic system to erratic factors, we are not able, using GARCH models, to obtain truly random residuals. Given this evidence we put forward the possibility that seemingly but not truly random residuals could be, in principle, better controlled and forecasted in the short run.economics of technology ;

International parity relationships between Germany and US: a multivariate time series analysis for the post Bretton-Woods period

This paper investigates the effects of replacing the consumer price index (CPI) with the wholesale price index (WPI) in the cointegrating in-ternational parity relationships found by Juselius and MacDonald (2000).AR model, cointegration, purchasing power parity, un-covered interest rate parity.

Random Walks and Non-Linear Paths in Macroeconomic Time Series: Some Evidence and Implications

This paper investigates whether the inherent non-stationarity of macroeconomic time series is entirely due to a random walk or also to non-linear components. Applying the numerical tools of the analysis of dynamical systems to long time series for the US, we reject the hypothesis that these series are generated solely by a linear stochastic process. Contrary to the Real Business Cycle theory that attributes the irregular behavior of the system to exogenous random factors, we maintain that the fluctuations in the time series we examined cannot be explained only by means of external shocks plugged into linear autoregressive models. A dynamical and non-linear explanation may be useful for the double aim of describing and forecasting more accurately the evolution of the system. Linear growth models that find empirical verification on linear econometric analysis, are therefore seriously called in question. Conversely non-linear dynamical models may enable us to achieve a more complete information about economic phenomena from the same data sets used in the empirical analysis which are in support of Real Business Cycle Theory. We conclude that Real Business Cycle theory and more in general the unit root autoregressive models are an inadequate device for a satisfactory understanding of economic time series. A theoretical approach grounded on non-linear metric methods, may however allow to identify non-linear structures that endogenously generate fluctuations in macroeconomic time series.Random Walks, Real Business Cycle Theory, Chaos

Random walks and cointegration relationships in international parity conditions between Germany and USA for the post Bretton-Woods period

This paper is based on a recent paper by Juselius and MacDonald (2000, 2003) and two `Journal of Econometrics' article s by Juselius (1995) and Johansen and Juselius (1992). The basic feature in all these articles is that the joint modelling of international parity conditions, namely ppp and uip, produces stationary relations showing an important interaction between the goods and the capital markets. We replaced the consumer price index (CPI) considered by Juselius and MacDonald with the producer price index (PPI) to check whether the international parity relationships still cointegrate. To our surprise we outstandingly produced similar results to those by Juselius and MacDonald, suggesting that the cointegration relationships in the international parity conditions hold also if we use different measures of prices. What is striking in our results is that even if there is no direct cointegration relation between CPI and PPI both in Germany and USA, the cointegration relation found between ppp and uip still holds notwithstanding of how ppp is measured.ppp, uip, Fisher parity

Random walks and cointegration relationships in international parity conditions between Germany and USA for the Bretton-Woods period

Juselius (1995), MacDonald (2000), Juselius and MacDonald (2000) provided an explanation to some basic issues in international monetary economics concerning the validity of parity conditions. This paper instead restricts the analysis to the years between 1957 and 1969 and the countries under scrutiny are Germany and USA. Results can be easily compared with the Post Bretton Woods analysis by Juselius and MacDonald (2000). The main result of this paper is that important cointegration relationships found for the Post Bretton-Woods by Juselius and MacDonald (2000) essentially hold for the Bretton-Woods period as well, albeit the two periods were characterized by distinct exchange rate regimes and a different regulation in capital markets.ppp, uip, Fisher parity, Bretton-Woods regime

Stage-Specific Regulation of Murine Hsp68 Gene Promoter in Preimplantation Mouse Embryos

AbstractIn early mouse embryos, the major inducible heat shock gene, hsp68, is spontaneously and transiently activated at the two-cell stage and becomes heat-inducible around blastocyst stage. We have probed mouse embryo's ability to activate the promoter of this gene during preimplantation development by expression analysis of DNA constructs containing a reporter lacZ gene driven by hsp68 (hsp70A1) 5′-regulatory sequences of various length: (i) a full-length promoter (construct phsplacZ); (ii) a heat shock element (HSE)-deleted promoter (pΔ1hsplacZ); and (iii) a minimal, proximal promoter (pΔ2hsplacZ). When analyzed in transfected L-cells, phsplacZ was heat-inducible, while neither pΔ1hsplacZ nor pΔ2hsplacZ was. Developmental activity of the full-length construct was first analyzed after genome integration in transgenic embryos and found to follow endogenous hsp68 expression in terms of spontaneous activation at the 2-cell stage, down-regulation at the 4-cell stage, and acquisition of heat inducibility at the 16/32-cell stage. In transient expression experiments, injected phsplacZ, pΔ1hsplacZ, and pΔ2hsplacZ were expressed at similar levels by 2-cell embryos, independently of construct topology and injection stage. At the 4-cell stage, however, phsplacZ and pΔ1hsplacZ were expressed at similar levels, while pΔ2hsplacZ was inactive. Only phsplacZ became heat-inducible in late morulas. We conclude that in early mouse embryos, developmental activity of episomic hsp68 promoter depends on proximal sequences at the 2-cell stage and on putative enhancer sequences at the 4-cell stage, while HSEs appear dispensable during early cleavage

BDDC preconditioners for virtual element approximations of the three-dimensional Stokes equations

The Virtual Element Method (VEM) is a novel family of numerical methods for approximating partial differential equations on very general polygonal or polyhedral computational grids. This work aims to propose a Balancing Domain Decomposition by Constraints (BDDC) preconditioner that allows using the conjugate gradient method to compute the solution of the saddle-point linear systems arising from the VEM discretization of the three-dimensional Stokes equations. We prove the scalability and quasi-optimality of the algorithm and confirm the theoretical findings with parallel computations. Numerical results with adaptively generated coarse spaces confirm the method's robustness in the presence of large jumps in the viscosity and with high-order VEM discretizations

Ecoturismo, conservação da natureza e deep ecology : uma reflexão sobre o turismo como experiência de ampliação da consciência

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Centro de Excelência em Turismo, 2020.O presente trabalho é uma reflexão sobre as relações entre o pensamento e a ação voltados para a conservação da natureza, a biologia da conservação, os princípios éticos e filosóficos estabelecidos pela Deep Ecology (Ecologia Profunda) e os princípios e práticas desenvolvidos pelo ecoturismo. Ele trata do potencial que a prática do ecoturismo, permeada por valores característicos de uma ética ecocêntrica, baseada na noção de que a natureza tem um valor intrínseco, tem como ferramenta de interpretação e educação para a conservação dos patrimônios natural e cultural. A pesquisa foi baseada em amplo material sobre ecoturismo, história da conservação da natureza e Deep Ecology - documentos, sites, artigos, livros e vídeos. As principais conclusões remetem à ideia de que o ecoturismo, como um segmento voltado para a conservação dos patrimônios natural e cultural, da biodiversidade e da sociodiversidade, depende de uma reflexão profunda em relação aos valores e aos princípios éticos que orientam a sua prática.This paper is the result of a research on the relationship between thought and action towards nature conservation, conservation biology, the ethical and philosophical principles established by Deep Ecology and the principles and practices developed by ecotourism. It deals with the potential that the practice of ecotourism, permeated by characteristic values of an ecocentric ethics, based on the notion that nature has an intrinsic value, has as a tool of interpretation and education for the conservation of natural and cultural heritage. The research was based on extensive material on ecotourism, nature conservation history and Deep Ecology - documents, websites, articles, books and videos. The main conclusions refer to the idea that ecotourism, as a segment focused on the conservation of natural and cultural heritage, biodiversity and sociodiversity, depends on a deep reflection on the values and ethical principles that guide its practice

The effects of vent location, event scale and time forecasts on pyroclastic density current hazard maps at Campi Flegrei caldera (Italy)

This study presents a new method for producing long-term hazard maps for pyroclastic density currents (PDC) originating at Campi Flegrei caldera. Such method is based on a doubly stochastic approach and is able to combine the uncertainty assessments on the spatial location of the volcanic vent, the size of the flow and the expected time of such an event. The results are obtained by using a Monte Carlo approach and adopting a simplified invasion model based on the box model integral approximation. Temporal assessments are modeled through a Cox-type process including self-excitement effects, based on the eruptive record of the last 15 kyr.Mean and percentilemaps of PDC invasion probability are produced, exploring their sensitivity to some sources of uncertainty and to the effects of the dependence between PDC scales and the caldera sector where they originated. Conditional maps representative of PDC originating inside limited zones of the caldera, or of PDC with a limited range of scales are also produced. Finally, the effect of assuming different time windows for the hazard estimates is explored, also including the potential occurrence of a sequence of multiple events. Assuming that the last eruption of Monte Nuovo (A.D. 1538) marked the beginning of a new epoch of activity similar to the previous ones, results of the statistical analysis indicate a mean probability of PDC invasion above 5% in the next 50 years on almost the entire caldera (with a probability peak of 25% in the central part of the caldera). In contrast, probability values reduce by a factor of about 3 if the entire eruptive record is considered over the last 15 kyr, i.e., including both eruptive epochs and quiescent periods