4,720 research outputs found
Evolution strategies combined with central pattern generators for head motion minimization during quadruped robot locomotion
In autonomous robotics, the head shaking induced
by locomotion is a relevant and still not solved problem. This
problem constraints stable image acquisition and the possibility
to rely on that information to act accordingly.
In this article, we propose a movement controller to generate
locomotion and head movement. Our aim is to generate the
head movement required to minimize the head motion induced
by locomotion itself. The movement controllers are biologically
inspired in the concept of Central Pattern Generators (CPGs).
CPGs are modelled based on nonlinear dynamical systems,
coupled Hopf oscillators. This approach allows to explicitly
specify parameters such as amplitude, offset and frequency of
movement and to smoothly modulate the generated oscillations
according to changes in these parameters. Based on these
ideas, we propose a combined approach to generate head
movement stabilization on a quadruped robot, using CPGs and
an evolution strategy. The best set of parameters that generates
the head movement are computed by an evolution strategy.
Experiments were performed on a simulated AIBO robot.
The obtained results demonstrate the feasibility of the approach,
by reducing the overall head movement
Morfodiagnose de Orbignya teixeirana Bondar (Palmae - Cocosoideae) nos Estados do Piaui e Maranhao.
bitstream/item/97234/1/PAND390001.pd
The influence of scavengers on VOC emissions in particleboards made from pine and poplar
This paper studies the performance of scavengers on Volatile Organic Compound (VOC) emissions from wood-based composites. Particleboards made from maritime pine (Pinus pinaster Ait.) and European poplar (Populus spp.) were produced with a UF resin doped with melamine and two scavengers, sodium metabisulfite and urea. VOC emission was measured according to EN ISO 16000. Particleboards made from pine present much higher total VOC (TVOC) emissions than boards made from poplar. Pine emits a higher amount of terpenes, but also aldehydes, acids and terpenoids, while poplar emits mainly acetic acid. Sodium metabisulfite showed an excellent ability to reduce aldehydes emission, which represents nearly 50 % of total emission of particleboards made from pine. When sodium metabisulfite was applied to particleboards made from poplar, reduction of TVOCs was not significant due to the low contribution of aldehydes to TVOCs. Urea presents a low reduction in TVOCs for both wood species
Composição quÃmica da forragem produzida em pastagens degradadas de Brachiaria brizantha cv. Marandu submetidas a diferentes nÃveis e freqüência de fertilização do solo.
O objetivo deste trabalho foi avaliar os efeitos de nÃveis e frequências de fertilização do solo sobre a composição quÃmica da forragem produzida empastagens degradadas de Brachiaria brizantha cv.Marandu, nas condições edafoclimáticas de PortoVelho - RO.bitstream/item/45969/1/ct116-pastagem.pd
Resposta de pastagens degradadas de Brachiaria brizantha cv. Marandu a diferentes nÃveis e frequência de fertilização do solo.
O objetivo desse trabalho foi avaliar os efeitos de nÃveis e frequências de fertilização do solo no acúmulo de forragem em pastagens degradadas de Brachiaria brizantha cv. Marandu, nas condições edafoclimáticas de Porto Velho-RO.bitstream/item/46603/1/cot363-pastagem.pd
Influence of Insulin-like Growth Factor I (IGF-I) on the survival and the in vitro development of caprine preantral follicles
The aim of this study was to investigate the effects of the insulin-like growth factor -I (IGF-I) on survival, activation (transition from primordial to primary follicles) and growth of caprine preantral follicles cultured in vitro. Fragments of ovarian cortex were cultured for one and seven days in the absence or presence of IGF-I (0, 50 and 100ng/ml). The non-cultured and cultured tissues were processed and analyzed by histology and transmission electron microscopy. The culture for one day in a medium with 100ng/ml of IGF-I showed 86.7% of morphologically normal follicles. These results were similar (P>0.05) to the percentage of normal follicles found in the control (96.7%). It was also found that this medium increased the percentage of follicular activation (developing follicles) with one day of culture. The oocyte and follicular diameters remained similar to the control by culturing for one day in a medium containing 100ng/ml of IGF-I. The ultrastructural analysis did not confirm the integrity of the follicular fragments in a medium containing IGF-I (100ng/ml) after one and seven days of culture. In conclusion, this study demonstrated that the addition of 100 ng/ml of IGF-I in the culture medium enables the development of preantral follicles of goats with one day of culture. However, it is not sufficient to maintain the follicular integrity and the follicular survival rate after seven days of culture.O objetivo do presente estudo foi investigar os efeitos do fator de crescimento semelhante a insulina-I (IGF-I) na sobrevivência, ativação (transição de folÃculos primordiais para primários) e crescimento de folÃculos pré-antrais caprinos cultivados in vitro. Fragmentos de córtex ovariano foram cultivados por um e sete dias na ausência ou presença de IGF-I (0, 50 e 100ng/mL). Os tecidos não cultivados e cultivados foram processados e analisados por histologia e microscopia eletrônica de transmissão. O cultivo por um dia em meio com 100ng/mL de IGF-I apresentou 86,7% de folÃculos morfologicamente normais. Estes resultados foram semelhantes (P>0,05) ao percentual de folÃculos normais encontrados no controle (96,7%). Verificou-se ainda que este meio aumentou o percentual de ativação folicular (folÃculos em desenvolvimento) com um dia de cultivo. Os diâmetros ovocitário e folicular mantiveram-se semelhantes ao controle ao cultivar por um dia em meio contendo 100ng/mL de IGF-I. As análises ultraestruturais não confirmaram a integridade folicular dos fragmentos em meio contendo IGF-I (100 ng/mL) após um e sete dias de cultivo. Em conclusão, esse estudo demonstrou que a adição de 100 ng/mL de IGF-I no meio de cultivo ativa o desenvolvimento de folÃculos pré-antrais de caprinos com um dia de cultivo. Entretanto, não é suficiente para manter a integridade folicular e a taxa de sobrevivência folicular após sete dias de cultivo
Implantable microdevice with integrated wireless power transfer for thermal neuromodulation applications
Medication resistant neurological and psychiatric disorders, RNPD, are devastating multicausal chronic diseases that cannot be adequately controlled using conventional pharmaco and/or psychotherapies, being epilepsy a well-known RNPD. Wireless biomedical device availability is growing at an impressive rate, and the systems' miniaturization, integration and complexity is also increasing, unveiling new therapies based on such new devices. This paper presents a new wireless implantable device as a solution for thermal neuromodulation of brain cells, which can be used to treat or study the brain's behavior when cooled down. The obtained results show that, despite these systems' potential to be power hungry, they may operate within acceptable electrical power values, while reaching the required neuromodulation temperatures.This work has been supported by FCT (Fundação para a Ciência e
Tecnologia) in the scope of the project PTDC/EEITEL/5250/2014, project
PTDC/CTM-NAN/5414/2014 and under grant SFRH/BD/100649/2014.info:eu-repo/semantics/publishedVersio
Maize open-pollinated populations physiological improvement: validating tools for drought response participatory selection
Participatory selection—exploiting specific adaptation traits to target environments—helps
to guarantees yield stability in a changing climate, in particular under low-input or organic production.
The purpose of the present study was to identify reliable, low-cost, fast and easy-to-use tools to
complement traditional selection for an e ective participatory improvement of maize populations
for drought resistance/tolerance. The morphological and eco-physiological responses to progressive
water deprivation of four maize open-pollinated populations were assessed in both controlled and
field conditions. Thermography and Chl a fluorescence, validated by gas exchange indicated that the
best performing populations under water-deficit conditions were ‘Fandango’ and to a less extent
‘Pigarro’ (both from participatory breeding). These populations showed high yield potential under
optimal and reduced watering. Under moderate water stress, ‘Bilhó’, originating from an altitude of
800 m, is one of the most resilient populations. The experiments under chamber conditions confirmed
the existence of genetic variability within ‘Pigarro’ and ‘Fandango’ for drought response relevant for
future populations breeding. Based on the easiness to score and population discriminatory power,
the performance index (PIABS) emerges as an integrative phenotyping tool to use as a refinement of
the common participatory maize selection especially under moderate water deprivationinfo:eu-repo/semantics/publishedVersio
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