Wavelets: a powerful tool for studying rotation, activity, and pulsation in Kepler and CoRoT stellar light curves

Aims. The wavelet transform has been used as a powerful tool for treating several problems in astrophysics. In this work, we show that the time-frequency analysis of stellar light curves using the wavelet transform is a practical tool for identifying rotation, magnetic activity, and pulsation signatures. We present the wavelet spectral composition and multiscale variations of the time series for four classes of stars: targets dominated by magnetic activity, stars with transiting planets, those with binary transits, and pulsating stars. Methods. We applied the Morlet wavelet (6th order), which offers high time and frequency resolution. By applying the wavelet transform to the signal, we obtain the wavelet local and global power spectra. The first is interpreted as energy distribution of the signal in time-frequency space, and the second is obtained by time integration of the local map. Results. Since the wavelet transform is a useful mathematical tool for nonstationary signals, this technique applied to Kepler and CoRoT light curves allows us to clearly identify particular signatures for different phenomena. In particular, patterns were identified for the temporal evolution of the rotation period and other periodicity due to active regions affecting these light curves. In addition, a beat-pattern signature in the local wavelet map of pulsating stars over the entire time span was also detected.Comment: Accepted for publication on A&

Transanal total mesorectal excision with triangle rules: a road map to prevent injuries

[Extract] Transanal total mesorectal excision (TaTME) is presented as a promising new surgical technique for the approach to the distal rectum, providing the ability to perform a highquality resection, with technical advantages over the laparoscopic approach. However, the new surgical anatomy of the TaTME resection complicates surgical understanding and increases the risks of inadvertent injuries to important anatomic structures...info:eu-repo/semantics/publishedVersio

Transient Charging and Discharging of Spin-polarized Electrons in a Quantum Dot

We study spin-polarized transient transport in a quantum dot coupled to two ferromagnetic leads subjected to a rectangular bias voltage pulse. Time-dependent spin-resolved currents, occupations, spin accumulation, and tunneling magnetoresistance (TMR) are calculated using both nonequilibrium Green function and master equation techniques. Both parallel and antiparallel leads' magnetization alignments are analyzed. Our main findings are: a dynamical spin accumulation that changes sign in time, a short-lived pulse of spin polarized current in the emitter lead (but not in the collector lead), and a dynamical TMR that develops negative values in the transient regime. We also observe that the intra-dot Coulomb interaction can enhance even further the negative values of the TMR.Comment: 7 pages, 6 figures. Typos corrections corresponding to the published versio

Melhoramento genético e produção de rainhas de Apis mellifera.

bitstream/item/87876/1/MELHORAMENTO-GENETICO.pd

Testes de conforto térmico aplicados a uma malha multifuncional desenvolvida com novos materiais

Os produtores europeus, os engenheiros têxteis e os designers devem, no desenvolvimento de novas peças de vestuário, terem em consideração as novas exigências dos consumidores em relação ao conforto. Uma grande variedade de áreas de investigação foram, nos últimos tempos, criadas e desenvolvidas permitindo atingir as exigências relacionadas com o conforto, nomeadamente, considerando os aspectos funcionais e estéticos, entre outros. O conforto térmico humano é, de certa forma, um dos componentes mais importantes a considerar, podendo ser definido como a principal troca de calor e massa e calor do corpo humano com o meio ambiente, através da roupa. Um dos objectivos deste trabalho foi, através do trabalho de uma equipa multidisciplinar, desenvolver uma malha funcional de forma a permitir o conforto termo-fisiológico a quem a utilizar. O presente trabalho permite assim investigar as várias etapas relacionadas com o estudo do conforto no desenvolvimento de novas peças de vestuário: o desenvolvimento de novas malhas, a execução de testes num manequim térmico; a simulação numérica do corpo humano com e sem roupa e o desenvolvimento de testes subjectivos de conforto térmico. A nova malha produzida foi caracterizada e testada em laboratório, em termos de quantidade de vapor de água e da permeabilidade ao ar e outros parâmetros físicos. A malha produzida foi aplicada como forro de botas de caminhada e para o fabrico de t-shirts. Os protótipos das botas de caminhada foram avaliados de forma subjectiva através de questionários. Um manequim térmico foi utilizado para medir o isolamento térmico das t-shirts e a distribuição de temperatura na pele. Juntamente com este trabalho experimental, um modelo de termo regulação do corpo humano foi desenvolvido para validar os dados experimentais obtidos. Alguns dos resultados são apresentados e discutidos

Stellar parameters for stars of the CoRoT exoplanet field

Aims:To support the computation and evolutionary interpretation of periods associated with the rotational modulation, oscillations, and variability of stars located in the CoRoT fields, we are conducting a spectroscopic survey for stars located in the fields already observed by the satellite. These observations allow us to compute physical and chemical parameters for our stellar sample. Method: Using spectroscopic observations obtained with UVES/VLT and Hydra/Blanco, and based on standard analysis techniques, we computed physical and chemical parameters ($T_{\rm{eff}}$, $\log \,(g)$, $\rm{[Fe/H]}$, $v_{\rm{mic}}$, $v_{\rm{rad}}$, $v \sin \,(i)$, and $A(\rm{Li})$) for a large sample of CoRoT targets. Results: We provide physical and chemical parameters for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in our sample are located in different evolutionary stages, ranging from the main sequence to the red giant branch, and range in spectral type from F to K. The physical and chemical properties for the stellar sample are in agreement with typical values reported for FGK stars. However, we report three stars presenting abnormal lithium behavior in the CoRoT fields. These parameters allow us to properly characterize the intrinsic properties of the stars in these fields. Our results reveal important differences in the distributions of metallicity, $T_{\rm eff}$, and evolutionary status for stars belonging to different CoRoT fields, in agreement with results obtained independently from ground-based photometric surveys. Conclusions: Our spectroscopic catalog, by providing much-needed spectroscopic information for a large sample of CoRoT targets, will be of key importance for the successful accomplishment of several different programs related to the CoRoT mission, thus it will help further boost the scientific return associated with this space mission.Comment: 43 pages, 17 figures, accepted for publication in A&

Use of the video transect method for characterizing the Itacolomis reefs, eastern Brazil

O método do vídeo-transecto consiste em uma filmagem do fundo marinho ao longo de uma seção linear, e as imagens são posteriormente analisadas, em laboratório, na tela de um computador. Este método foi aplicado pela primeira vez no Brasil nos recifes do interior da Baía de Todos os Santos, com resultados satisfatórios. O objetivo deste trabalho foi determinar qual seria o menor esforço amostral na aplicação do vídeo transecto para avaliar a comunidade de coral do recife Pedra do Silva, no complexo de recifes dos Itacolomis, na Reserva Extrativista Marinha de Corumbau, no sul do estado da Bahia. Cada transécto foi analisado em toda a sua extensão em quadros sucessivos gerados com o congelamento da imagem na tela de um computador. Os resultados obtidos apontam o número de seis transéctos de 20 m de comprimento para uma análise de vinte pontos por quadro como adequada para a identificação taxonômica das principais categorias dos corais construtores e dos componentes da biota bentônica dos recifes, podendo toda a operação ser executada durante apenas um mergulho por local de amostragem.The video-transect method consists of a field survey performed with a video-camera along a line of fixed length, with the registered images further analyzed using a computer. This method was successfully applied in Brazil for the first time in the coral reefs of Todos os Santos Bay. The main goal of this work was to define the minimum sampling effort needed to describe the coral community when the video-transect method was applied to a selected reef site, namely the Pedra do Silva Reef in the Itacolomis reef complex, inside the Corumbau Marine Extractive Reserve, in Southern Bahia. Each transect was analyzed throughout its length, in successive captured video frames. The findings revealed that six 20 m long transects with an analysis of twenty points per image (frame) was sufficient for sampling the broad taxonomic categories of hard corals and major reef benthos, and that the whole field operation could be performed during one dive per station