Detecção de periodicidades em séries temporais: o Periodograma

Neste texto, depois de uma breve introdução à análise de Fourier, com especial incidência na apresentação de Fourier de sucessões periódicas, definimos o periodograma e deduzimos algumas das suas propriedades estatísticas. Mostramos como este pode ser utilizado para a detecção de periodicidades numa série temporal, e damos alguns testes nas ordenadas do periodograma. Por fim, aplicamos a teoria desenvolvida a um conjunto de observações referentes à temperatura da água do mar.

Periodicidade de oviposição de fêmeas de Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae) em laboratório e campo

O objetivo deste trabalho foi determinar o padrão gonotrófico de fêmeas de Aedes aegypti em condições de laboratório e de campo. Fêmeas copuladas e alimentadas com sangue de galinha foram transferidas para gaiolas de polipropileno e oferecidos diferentes substratos de oviposição (papel sulfite, filtro, manteiga e toalha). O papel filtro recebeu significativamente maior (40,4%) deposição de ovos do que os demais substratos. Observou-se que maior (35,7% dia modal) oviposição ocorreu ao terceiro dia, após alimentação sangüínea. Foi observada a oviposição das fêmeas a cada duas horas de intervalo, durante o fotoperíodo em laboratório e em campo por meio de ovitrampas. Os resultados de laboratório demonstraram que maior deposição de ovos ocorreu entre a 9ª - 12ª hora da fotofase e 1ª - 2ª hora de escotofase. Em campo maior número de ovos ocorreu entre 9ª - 12ª hora de fotofase e na 1ª - 4ª hora de escotofase. Estes resultados indicam que Aedes aegypti exibiu um padrão na periodicidade de oviposição e podem subsidiar em programas de monitoramento e ou controle do inseto vetor. Sugere-se que, em campo, por exemplo, armadilhas de oviposição (ovitrampa) devem ser instaladas no período da manhã pois as capturas ocorrem a partir do período da tarde.

Observações preliminares sobre a periodicidade e taxa de crescimento em árvores tropicais

Resultados preliminares sobre a periodicidade e taxa de crescimento de Cardeiro (Scleronema micranthum Ducke, Bombacaceae) são apresentados. Observou-se ama periodicidade de crescimento. As taxas de incremento são correlacionadas aos resultados referidos da Guiana Francesa.

Periodicidade e escolha de exames laboratoriais na terapia hipolipemiante

Intervenções farmacológicas com hipolipemiantes devem ser monitoradas periodicamente para avaliar eficácia e parâmetros de segurança. As estatinas são drogas normalmente bem toleradas e os seus principais efeitos colaterais incluem aumento das enzimas hepáticas (AST e ALT) e muscular (CK). O tratamento deve ser interrompido ou diminuído no caso de um aumento significativo das AST ou ALT (> 3x LSN), ou CK (> 10x LSN). Outros agentes hipolipemiantes também podem produzir hepatotoxicidade ou miosite, fibratos e ácido nicotínico, especialmente em associação com as estatinas ou na presença de anormalidades metabólicas (tireoidite, hepatopatia e nefropatia). Ácido nicotínico pode também aumentar os níveis plasmáticos de glicose e ácido úrico. Testes laboratoriais podem ser utilizados no seguimento da terapia hipolipemiante e devem ser repetidos a cada três meses durante o primeiro ano e então em intervalos de seis meses. Intervalos menores são recomendados para casos especiais.

A vegetação no município de Ilhéus Estado da Bahia: IV - Caracaterísticas analíticas e periodicidade sociológica

It is well-known that diverse groups of vegetation with an analogous but not identical floristic composition show an ecological similarity which leads to a determined type of vegetation. Starting from this fact it becomes evident that the scope of phytosociological work is the establishing of the significance of the species within the association and the discovery of the rules which govern associations. The floristic surveys made in the field have to be analysed statistically so as to obtain satisfactory results. The usefulness of this method depends largely on the possibilities of comparing the results with previous studies of the same kind, in the same country, or elsewhere. The method used in this paper is that of measuring circumferences and counting individuals in the different associations studied because it permits the presentation of the results in tables which show the phytosociological complexity of the Brazilian rain-forests. The classical method of characteristics is valuable because the more evolved an association is the less sociable are the species it contains, so that such groups do not show clear differences between species but rather between sinusia or strata of individuals. Five tables are presented in which several of the qualitative and quantitative characteristics are studied with a view to discussing their value in relation to groups and species. They are: I - Abundance (number of individuals). II - Density (distance in meters between the individuals belonging to each stratum). III - Basal coverture (circles measured in square meters of the mean projection of the individuals on the surface). IV - Basal area (mean circle in square meters occupied by individuals on the surface). V - Frequency, abundance and sociability in relation to occurrence. TABLE I. This table indicates first the number of individuals in relation to the sinusia studied: next, the sum total of the individuals belanging to the strata are given for each association, thus providing the numeric value of the sinusia: finally, the relation between the total number of individuals in the association and the total for the sinusium thus fursnishing the abundance per sinusium, in the classic sence, that is the percentage, or rather the relative number, of the elements which compose the group. CONCLUSIONS. The general character of abundance of the regional vegetation of Ilheos may be summed up in the following way: as an association evolves towards permanent equilibirum the number of individuals the inferior strata diminishes in relation to those of the superior strata which increase. For the shrub sinusium, two important facts were observed: a) in a given association the number of elements of the inferior strata diminishes as the diameter of the individuals increases; b) the percentage of individuals belonging to the shrub sinusium in the sere diminishes as the association evolve. In the subarboreal sinusium it is seen that: in the sere the number of subarboreal individuals does not vary much; whereas in the climax or the prisere there is a fall owing to the equilibrum of the biologic forms. In the arboreal sinusium the following conclusion can be deduced from analogous facts: the number of individuals of the lower strata diminishes as circumference increases. Also, in the sere there is a progressive sequence for the individuals belonging to the superior strata. TABLE II. The relation between the mean distances of individuals belonging to the same stratum and the area of an association is equal to the density. The table shows that the mean density of the association and the distance between the individuals belonging to the strata of the same sinusium in relation to the total number of individuals belonging to the association. CONCLUSIONS. As rule, the density of individuals in the associations studied follows a very general character or at least a regional one: the distance between the individuals in the diverse strata varies according to their abundance and sociability. Two other facts of some sociological importance are: a) in identical strata of the same sere the density of individuals oscillates in an analogous manner in teh subclimaces and varies in the stages which have reached equilibrium. b) the density of individuals varias in accordance with the sinusium and the distances between individuals of the same sinusium varg in accordance with the strata. TABLE III. This table presents the mean basal individual coverture, that is the mean projection of the frond of the various individuals belonging to the same stratum. The means were obtained by measurement in the field, of 100 individuals belonging to each stratum and their projection on the surface. In the latoratory these measurements were converted into mean circles (in square meters) and the result was multiplied by the individuals belonging to the strata corresponding to the sinusium of each association. The result obtained is named basal coverture. CONCLUSIONS. As a rule, the basal coverture of the vegetation of the county of Ilhéus indicates that: in the evolution of the vegetation the basal coverture of the arbustive sinusium diminishes progressively whereas that of the arboreal one increases. The special norms obtained are: 1) in the shrub sinusium the basal coverture seems to follow a uniform norm, that is, in stages of evolution of the subclimax the basal coverture oscillates with a certain uniformity. 2) in the subarboreal sinusium this fact is related to the vitality and age of the species, as in the subclimax the number of young trees is large and the vitality of the species very variable. This permits the conclusion that: in the sere the basal coverture increases with the evolution of the vegetation and diminishes when an equilibrium is reached. 3) in the tree sinusium the climax association of the prisere and subsere seem to obey a binomial rule, as the coverture (density-abundance) increases until a determined stratum is reached and...

Avaliação do conhecimento sobre periodicidade química em uma turma de química geral do ensino a distância

This work describes the software Quiptabela, suggests a teaching activity, and analyses responses of general chemistry students from the Biological Sciences distance course at the Federal University of Tocantins. The software was described according to its educational potential, featuring the creation of dozens of charts or tables correlating physicochemical properties of the elements, being Brazilian, and free distribution. The teaching activities suggested analyzed students' ability to create and analyze tables and charts correlating the properties of chemical elements. Some 41% of students tested could define the term "periodic", but failed to use the concept to explain and differentiate changes in mass or atomic radius with the atomic number of elements.

Química y arte : la armonía escondida.

Resumen tomado de la publicación

En busca de la palabra escondida.

Pretende estimular el uso del lenguaje oral y su desarrollo para hacer que los niños aprendan por medio de los intercambios personales con el adulto. A través de un equipo de grabación en video y del material didáctico disponible en cada escuela, se procede a la obtención y análisis posterior de observaciones sobre el desarrollo comunicativo en el entorno del aula y comparar las competencias lingüísticas en desarrollo en niños procedentes de ámbitos y escuelas diferentes. Las grabaciones se hacen sobre actividades grupales e individuales dirigidas o espontáneas y se comprueba cómo se utiliza la lengua y cómo el oyente puede interpretar lo que se dice. También se requiere la participación activa de los padres. Concluye con las funciones y desarrollo del lenguaje en la escuela en los niños a partir de dos años..

La historia escondida en nuestro Instituto

Monográfico con el título: 'Ser bachiller ayer y hoy'. Resumen basado en el de la publicación

Simetria de invariância de escala discreta, log-periodicidade e singularidades em tempo finito

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Generalização da periodicidade: um estudo sobre Apostrophe et six réflexions de Henri Posseur

Pós-graduação em Música - IA

Generalização da periodicidade: um estudo sobre Apostrophe et Six Réflexions de Henri Pousseur

Neste livro, Rodolfo Augusto Daniel Vaz Valente debruça-se sobre a obra do compositor belga Henri Pousseur (1929-2009), um dos principais expoentes da música contemporânea ao lado de Luciano Berio, Karlheinz Stockhausen e Pierre Boulez. Valente discute, principalmente, a contribuição de Pousseur para a revisão teórica do serialismo, já que este recupera, no âmbito da música serial, a noção de periodicidade (ou fraseologia regular), que havia sido banida das experiências iniciais do serialismo em nome do princípio basilar da não repetição. Pousseur estava convencido de que era necessário retomar em alguma medida a periodicidade das estruturas. Chegou mesmo a experimentar a sua teoria na música eletrônica e a recorrer à teoria ondulatória proveniente da Acústica para repensar o discurso musical, especialmente no terreno da organização das durações. Valente também aborda a periodicidade conforme os preceitos de Abraham Moles, um dos principais teóricos da Teoria da Informação e que teve grande influência sobre o trabalho de Pousseur. Analisa ainda a obra Apostrophe et six réflexions, escrita pelo compositor na época em este que formulou o conceito de periodicidade generalizada, como chamou a fraseologia do serialismo revisado que já não recorria às estruturas musicais essencialmente não periódicas.

Sistema GPS: uma órbita em evolução - número de satélites e periodicidade

The objective of this project was to monitor the satellites of the Global Positioning System (GPS) from a fixed point on Earth and to verify the rate of recurrence respect to their rotation and displacement. A topographic GPS signal receiver connected to a personal computer was used to recorded, for five days, the displacement of the satellites. This work was based on the fact that many literature references state that satellites complete one orbit around the Earth every 12 hours, then, it is assumed that the satellite would be seen twice in a day from the same fixed point on Earth.Although, this does not occur, as thise time interval correspond to 12 hours sidereal time and not solar time. In addition, this study was carried out in order toconfirm and update the information related to the number of satellites in operation today, found to be 31. In that sense, some references concerning the space segment of this system were defined in details.

Late Holocene air temperature variability reconstructed from the sediments of Laguna Escondida, Patagonia, Chile (45 degrees 30 ' S)

Climate and environmental reconstructions from natural archives are important for the interpretation of current climatic change. Few quantitative high-resolution reconstructions exist for South America which is the only land mass extending from the tropics to the southern high latitudes at 56°S. We analyzed sediment cores from two adjacent lakes in Northern Chilean Patagonia, Lago Castor (45°36′S, 71°47′W) and Laguna Escondida (45°31′S, 71°49′W). Radiometric dating (210Pb, 137Cs, 14C-AMS) suggests that the cores reach back to c. 900 BC (Laguna Escondida) and c. 1900 BC (Lago Castor). Both lakes show similarities and reproducibility in sedimentation rate changes and tephra layer deposition. We found eight macroscopic tephras (0.2–5.5 cm thick) dated at 1950 BC, 1700 BC, at 300 BC, 50 BC, 90 AD, 160 AD, 400 AD and at 900 AD. These can be used as regional time-synchronous stratigraphic markers. The two thickest tephras represent known well-dated explosive eruptions of Hudson volcano around 1950 and 300 BC. Biogenic silica flux revealed in both lakes a climate signal and correlation with annual temperature reanalysis data (calibration 1900–2006 AD; Lago Castor r = 0.37; Laguna Escondida r = 0.42, seven years filtered data). We used a linear inverse regression plus scaling model for calibration and leave-one-out cross-validation (RMSEv = 0.56 °C) to reconstruct sub decadal-scale temperature variability for Laguna Escondida back to AD 400. The lower part of the core from Laguna Escondida prior to AD 400 and the core of Lago Castor are strongly influenced by primary and secondary tephras and, therefore, not used for the temperature reconstruction. The temperature reconstruction from Laguna Escondida shows cold conditions in the 5th century (relative to the 20th century mean), warmer temperatures from AD 600 to AD 1150 and colder temperatures from AD 1200 to AD 1450. From AD 1450 to AD 1700 our reconstruction shows a period with stronger variability and on average higher values than the 20th century mean. Until AD 1900 the temperature values decrease but stay slightly above the 20th century mean. Most of the centennial-scale features are reproduced in the few other natural climate archives in the region. The early onset of cool conditions from c. AD 1200 onward seems to be confirmed for this region.