Estimating Attractor Dimension on the Nonlinear Pendulum Time Series

Chaotic dynamical systems exhibit trajectories in their phase space that converges to a strange attractor. The strangeness of the chaotic attractor is associated with its dimension in which instance it is described by a noninteger dimension. This contribution presents an overview of the main definitions of dimension discussing their evaluation from time series employing the correlation and the generalized dimension. The investigation is applied to the nonlinear pendulum where signals are generated by numerical integration of the mathematical model, selecting a single variable of the system as a time series. In order to simulate experimental data sets, a random noise is introduced in the time series. State space reconstruction and the determination of attractor dimensions are carried out regarding periodic and chaotic signals. Results obtained from time series analyses are compared with a reference value obtained from the analysis of mathematical model, estimating noise sensitivity. This procedure allows one to identify the best techniques to be applied in the analysis of experimental data.

Can the fractal dimension be applied for the early diagnosis of non-proliferative diabetic retinopathy?

The fractal dimension has been employed as a useful parameter in the diagnosis of retinal disease. Avakian et al. (Curr Eye Res 2002; 24: 274-280), comparing the vascular pattern of normal patients with mild to moderate non-proliferative diabetic retinopathy (NPDR), found a significant difference between them only in the macular region. This significant difference in the box-counting fractal dimension of the macular region between normal and mild NPDR patients has been proposed as a method of precocious diagnosis of NPDR. The aim of the present study was to determine if fractal dimensions can really be used as a parameter for the early diagnosis of NPDR. Box-counting and information fractal dimensions were used to parameterize the vascular pattern of the human retina. The two methods were applied to the whole retina and to nine anatomical regions of the retina in 5 individuals with mild NPDR and in 28 diabetic but opthalmically normal individuals (controls), with age between 31 and 86 years. All images of retina were obtained from the Digital Retinal Images for Vessel Extraction (DRIVE) database. The results showed that the fractal dimension parameter was not sensitive enough to be of use for an early diagnosis of NPDR.

Ethical research as the target of animal extremism: an international problem

Animal extremism has been increasing worldwide; frequently researchers are the targets of actions by groups with extreme animal rights agendas. Sometimes this targeting is violent and may involve assaults on family members or destruction of property. In this article, we summarize recent events and suggest steps that researchers can take to educate the public on the value of animal research both for people and animals

Practices and ethical concerns regarding preimplantation diagnosis. Who regulates preimplantation genetic diagnosis in Brazil?

Preimplantation genetic diagnosis (PGD) was originally developed to diagnose embryo-related genetic abnormalities for couples who present a high risk of a specific inherited disorder. Because this technology involves embryo selection, the medical, bioethical, and legal implications of the technique have been debated, particularly when it is used to select features that are not related to serious diseases. Although several initiatives have attempted to achieve regulatory harmonization, the diversity of healthcare services available and the presence of cultural differences have hampered attempts to achieve this goal. Thus, in different countries, the provision of PGD and regulatory frameworks reflect the perceptions of scientific groups, legislators, and society regarding this technology. In Brazil, several texts have been analyzed by the National Congress to regulate the use of assisted reproduction technologies. Legislative debates, however, are not conclusive, and limited information has been published on how PGD is specifically regulated. The country requires the development of new regulatory standards to ensure adequate access to this technology and to guarantee its safe practice. This study examined official documents published on PGD regulation in Brazil and demonstrated how little direct oversight of PGD currently exists. It provides relevant information to encourage reflection on a particular regulation model in a Brazilian context, and should serve as part of the basis to enable further reform of the clinical practice of PGD in the country.

The concept of emerging power in international politics and economy

ABSTRACT This paper aims to analyze the concept of emerging power established to the understanding of international affairs. The work observes that the use of the lexicon emerging - regarding to markets, countries or powers - as qualifier for a range of international relations phenomena became a constituent part of the matter. In spite of that, the empirical denotation of the predicate is ahead of the amount of efforts on its theoretical contextualization. Our methodological hypothesis is that the rational denial of the concepts prevailing connotative spectrum by acknowledging the embedded wisdom about cognate phenomena synthesizes a theoretical framework on its accurate use.

Razão e democracia: uso público da razão e política deliberativa em Habermas[ign] [title language="en"]Reason and democracy[ign]: [subtitle]Public use of reason and deliberative politics in Habermas

O objetivo do artigo é examinar como Habermas, orientado pela intuição normativa do uso público da razão, reconstrói uma concepção procedimental de democracia deliberativa, que, sem desconsiderar da dimensão estratégica e instrumental da esfera pública e da política, reformula a dimensão epistêmica da democracia: a aceitabilidade racional dos acordos políticos. Inicialmente, apresento brevemente a análise sociológica e histórica do conceito de esfera pública crítica, realizada em Mudança Estrutural da Esfera Pública (1962), para, em seguida, expor duas linhas de argumentação sobre o conceito de esfera pública e de política deliberativa, em Direito e Democracia (1992): a que se refere ao princípio de legitimação baseado na razão pública como uma reconstrução intersubjetiva e política do conceito kantiano de autonomia; e a que concerne aos aspectos essenciais da teoria crítica da sociedade fundada na distinção entre mundo da vida e sistema e a "tradução" sociológica e institucional do uso público da razão, nos conceitos de sociedade civil e esfera pública.