Matemática e Estatística | Comunicações em congressos, conferências e seminários / Communications in congresses, conferences
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- 12th Workshop on Statistics, Mathematics and Computation In Honour of Professor Carlos Braumann: book of abstractsPublication . Oliveira, Amilcar; Nunes, Célia; Ferreira, Dário; Grilo, Luís M.; Ferreira, Sandra; Oliveira, TeresaWe celebrate this meeting in Honour of Professor Carlos Braumann, for his brilliant career and outstanding contribution to the field of Statistics in Portugal and abroad, and to whom we are deeply grateful for all the support, kind and precious collaboration in our meetings! We are delighted to have this celebration fostering strong interaction between national and international researchers, leading to a successful com mitment and enthusiasm on promoting research in and between the broad areas of Statistics, Mathematics and Computation. It is a great pleasure to receive all our guests and contributors from 9 to 10 th November in UBI Universidade da Beira Interior, expressing our huge gratitude to the Univer sity Coordinators for kindly accepted to embrace this challenge of receiving us again! The WSMC was successfully organized in several places along these last 12 years and we believe that our meetings have been creating very nice opportunities for showcasing the growth and development of the focused main areas, at a time when so many new technologies are available and huge challenges are emerging. The idea exchanges between participants are al ways helpful for generating positive impact on propelling the advancement of science and technology and some of these results have been published in high standard Journals, special issues and Springer Series Books. Also in this 12th WSMC edition the participants will have several journal oppor tunities for papers submission. Selected papers, after review, will appear in Journal of Applied Statistics, Biometrical Letters, Biometrics & Biostatis tics International Journal (BBIJ) and in a new Springer volume of the Series Contributions to Statistics. We are hightly grateful to all the participants, Invited Speakers, Session Organizers and Authors who submitted abstracts, for their valuable contri bution and for the enthusiastic way how they assume their participation. We also acknowledge all the sponsors and contributors who made this meeting a reality. Furthermore, we acknowledge the Rector of Universidade da Beira Interior, the Rector of Universidade Aberta, the Coordinator of the Centro de Estatística e Aplicações da Universidade de Lisboa and the President of the Committee on Risk Analysis of International Statistical Institute, for v vi Preface their support. We are most grateful to all the members of the Organizing Committee and of the Scientific Committee for their crucial help and sugges tions. We address a deeply thanks to the Local Chair, Sandra Ferreira, and also to Amílcar Oliveira, Célia Nunes, Dário Ferreira and Luís Grilo for their invaluable contribution on organizing the Webpage, the final programme, the Book of Abstracts and so many details in a such incredible short time! Finally, the venue adds an important attraction to the meeting. The destination city, Covilhã, is a fantastic place close to beautiful and highest mountain in Portugal, Serra da Estrela. This region is very famous not only for awesome landscapes and sports opportunities but also for the famous de lights like the wool cheese, ham, licors and also for the traditional artesanat. Covilhã offers a full calendar of traditional festivals and holidays celebrated throughout the year adds to its cultural appeal. We trust that you will find the conference and your visit to the very beautiful city of Covilhã in November 2018 both valuable and enjoyable, we believe that this meeting will be rewarding to all of us and that it will draw us to the next edition -WSMC13, which is planned for 2019 in Lisbon.
- 13th Conference on Statistics, Mathematics and Computation: book of abstractsPublication . Oliveira, Amilcar; Ferreira, Dário; Ferreira, Sandra; Oliveira, Teresa A.We celebrate this meeting in Honour of Professor João Tiago Mexia, for his brilliant career and outstanding contribution to the field of Statistics in Portugal and abroad, and to whom we are deeply grateful for all the support, kindness and precious collaboration in our meetings! We are delighted to have this celebration, fostering strong interaction between national and international researchers, leading to a successful com mitment and enthusiasm on promoting research in and between the broad areas of Statistics, Mathematics and Computation. It is a great pleasure to receive all our guests and contributors from 3 to 5th June in the Aberta University, and we emphasize our huge gratitude to the Magnificent Rector, for kindly accepting to embrace this challenge of hosting once more this International Conference! The WSMC was successfully organized in several places along the 13 editions and we believe that our meetings have been creating very nice op portunities for showcasing the growth and development of the focused main areas, in a time underlined by so many new technologies and huge emerging challenges. The scientific exchanges of ideas between participants is always helpful for generating positive impact on propelling the advancement of sci ence and technology and some of these results have already been successfully published in high standard Journals, special issues and Springer Series Books. Also now, in this 13th edition, the participants have the opportunity to submit their work to high referenced Journals and Book volumes. Selected papers, after peer review, will appear in the Chilean Journal of Statistics (ChJS), Journal of Applied Statistics (JAS), Biometrical Letters, Biometrics & Biostatistics International Journal (BBIJ) and in Springer volumes of the Series Contributions to Statistics. Details will be soon announced in our webpage. We are highly grateful to all the participants, Invited Speakers, members of Scientific Committee, Session Organizers and Authors who submitted ab v vi Preface stracts, for their valuable contribution and for the enthusiastic way how their participation is assumed! We greatly acknowledge all the sponsors and contributors who made this meeting a reality and we reinforce the importance of our social programme. This year it includes the nice opportunity to visit the National Museum of Natural History and Science and the Botanical Garden, allowed all the week, from 3 to 9 of June - during and after WSMC13. We are really grateful to the Director of the Department of Museums Management Support and IICT, Dr Vitor Lucas and to his team, for kindly offering this outstanding opportunity to all the participants of WSMC13. A deeply thanks is addressed to all the members of the Organizing Com mittee, emphasizing the invaluable collaboration of Dr. Virginia Zaidam, the crucial help of the Gabinete de Comunicação e de Relações Internacionais UAB team, and the very hard work of Amílcar, Sandra and Dário on the organization and supervision of many of the programme and schedule de tails, preparing the website and the abstracts book in an incredible record time! Finally, as I guess most of you already noticed, Lisbon is very much enjoyable for offering a rich and varied history, a buzzing nightlife and for being blessed with a glorious year-round climate, where the sky joins the ocean and the city is kissed by the river Tagus. Please take some of your time to enjoy and take profit of it! Don’t forget to taste the famous "Pastéis de Belém" and to listen to Fado music! We wish you all a very productive and successfull meeting, as well as a pleasant and memorable stay in Lisbon, the stunning capital of Portugal!
- An application of Box-Jenkins methodology to model the series of currency in circulation in MozambiquePublication . Arone, Samuel G.; Nunes, Catarina S.; Grilo, Luís M.
- An infinite dimensional umbral calculusPublication . Oliveira, Maria João
- Analysis of the inequality into distributions: an alternative approach to the Gini index applied to the spending environmental in EUPublication . Seijas-Macias, Antonio; Oliveira, Teresa; Oliveira, AmilcarThe Gini index is the most common tool to measure inequality into two distributions. Traditionally, the Gini index and the curve of Lorenz are focused on inequalities measures in the income distribution between countries or regions. But, in the last years, several authors have shown some limitations of the Gini index. In particular, it’s less sensitive to inequality at the tail of income distribution. This type of problem in the Gini index could produce two types of reactions: a new reinterpretation of the Gini index and the proposal of some alternative measures to it. In this paper, we follow the previous work using the Csiszar f-divergence to propose using the α-divergences approach to analyze the differences between the Gini index approach and these alternatives. The Gini index has been applied to the measure of resource inequalities. The AR-Gini is an area-based measure of resource inequality that estimates inequalities between neighbourhoods regarding the consumption of specific consumer goods (Druckman and Jackson, 2008). The AR-Gini could be a useful tool to monitor the distributional impacts of resource-related interventions, but this indicator presents the same overcomes as the Gini index. We can use the Gini concentration coefficient as a measure of the concentration of distribution of a random variable, especially applied to time series of data. In recent years, several studies have studied environmental spending in the European Union (EU). We focus our analysis on the distribution of this type of spending between the countries of the EU. The objective of this study is to show the differences in indexes applied to the study of the distribution of the distribution of monetary resources to environmental conservation and the extension of environmental protected areas into the countries of the European Union (EU). In our comparative study, we use the Gini index and the α-divergence measure and compare the results to get the most accurate measure of the equity of the distribution.
- Anamorphosis: optical games with perspective's playful parentPublication . Araújo, AntónioWe explore conical anamorphosis in several variations and discuss its various constructions, both physical and diagrammatic. While exploring its playful aspect as a form of optical illusion, we argue against the prevalent perception of anamorphosis as a mere amusing derivative of perspective and defend the exact opposite view - that perspective is the derived concept, consisting of plane anamorphosis under arbitrary limitations and ad-hoc alterations. We show how to define vanishing points in the context of anamorphosis in a way that is valid for all anamorphs of the same set. We make brief observations regarding curvilinear perspectives, binocular anamorphoses, and color anamorphoses.
- Application of Benford’s Law to the Tourism Demand: the case of the Island of Sal, Cape VerdePublication . Neves, Gilberto A.; Nunes, Catarina S.; Fernandes, Paula OdeteThis article presents Benford’s Law applied for the first time to the tourism context, focusing on tourism demand. This law states that in sets of random numbers of natural events, the probability of the first digit of these numbers being 1 is approximately 30%, of being 2 is 18%, and so on until reaching 9 with 4.6% probability. In this context, the objective is to verify if Benford’s Law applies to the monthly numbers of overnight stays registered in the accommodation establishments of the Island of Sal, in the period between 2000 and 2018, to test the data reliability. This research focus on data provided by the National Statistics Institute of Cape Verde. The Chi-Square test (χ2) was used to assess the discrepancy between the observed and expected relative frequencies. The results show that the observed χ2 value is higher than the χ2 critical value (5% significance level), meaning that the number of monthly overnight stays recorded in accommodation establishments on the Island of Sal does not follow Benford’s Law. However, certain possible data disturbances must be considered, such as the occurrence of specific events during that time period. Other factors that could influence the results are the size of the data set and a sub notification in the data collection process. These circumstances may be the cause of the non-adaptation of the number of overnight stays to Benford’s Law. The implication of this fact on the estimation of tourism demand is crucial for the development and optimization of prediction models.
- ARX modeling of drug effects on brain signals during general anesthesiaPublication . Nunes, Catarina S.; Lobo, Francisco A.; Amorim, PedroThe effect of drugs’ interaction on the brain signal Bispectral Index (BIS) of the EEG, is of great importance for an anesthesia control drug infusion system. In this study, the objective was to investigate if an autoregressive with exogenous inputs model (ARX) could be a suitable approach to predicting BIS according to the anesthetic drugs concentrations. Data were collected in 45 neurosurgeries with total intravenous anesthesia every 5s. A stochastic ARX model was fitted to the data of each patient. The models structure that performed better as predictor used a 30s lag for BIS, 1min lag for propofol and 2min lag for remifentanil. The models had a good performance with statistical zero errors (P < 0.05) in 31 patients. The average of absolute errors was 8.2 ± 2.5, showing that the model captures the brain signal trend. This model proved to be effective in modeling and one step prediction of the BIS signal capturing unique characteristics. The results show that the previous brain response trend has influence on the present value, in addition the drugs concentrations from the previous 2min still have influence. This is an important conclusion for the development of drug infusion controller algorithms.
- Avaliação digital na matemática: exames onlinePublication . Nunes, Catarina S.
- BIB designs with repeated blocks: review and perspectivesPublication . Oliveira, TeresaExperimental Design plays an important role on establishing an interface between Applied Mathematics and statistical applications in several fields, like Agriculture, Industry, Genetics,Biology and Education Sciences. The goal of any Experimental Design is to obtain the maximum amount of information for a given experimental effort, to allow comparisons between varieties and to control for sources of random variability. Randomized block designs are used to control for these sources. A Balanced Incomplete Block Design (BIB Design) is a randomized block design with number of varieties greater than the block size and with all pairs of varieties occurring equally often along the blocks. The Fisher related information of a balanced block design will remain invariant whether or not the design has repeated blocks. This fact can be used theoretically to build a large number of non-isomorphic designs for the same set of design parameters, which could be used for many different purposes both in experimentations and surveys from finite populations. The original and most important method on the construction of BIB Designs with repeated blocks (BIBDR) is due to Hedayat and Li (1979): the trade-off method. Since then, many authors and researchers have been paying particular attention to the construction of BIBDR, but still some unsolved problems remain. This issue will be briefly reviewed and new results on the existence and construction of BIBDR, as well as several unsolved problems for further research will be presented.