675 research outputs found
On the embedding of spacetime in five-dimensional Weyl spaces
We revisit Weyl geometry in the context of recent higher-dimensional theories
of spacetime. After introducing the Weyl theory in a modern geometrical
language we present some results that represent extensions of Riemannian
theorems. We consider the theory of local embeddings and submanifolds in the
context of Weyl geometries and show how a Riemannian spacetime may be locally
and isometrically embedded in a Weyl bulk. We discuss the problem of classical
confinement and the stability of motion of particles and photons in the
neighbourhood of branes for the case when the Weyl bulk has the geometry of a
warped product space. We show how the confinement and stability properties of
geodesics near the brane may be affected by the Weyl field. We construct a
classical analogue of quantum confinement inspired in theoretical-field models
by considering a Weyl scalar field which depends only on the extra coordinate.Comment: 16 pages, new title and references adde
A study to guide breeding of new cultivars of organic cherry tomato following a consumer-driven approach.
Agricultural studies focusing on the development and/or improvement of new varieties of fruits and vegetables usually prioritize the productivity, disease resistance, response to fertilization, and higher nutrient content. However, new product development needs to take into account not only flavour preference, but also consumer preference for appearance since without tasting products, consumers have to make decisions based on the way a product looks. The present study evaluated the sensory characteristics and consumer preference of ten promising accessions of organic cherry tomato for fresh consumption aiming at identifying the sensory attributes related to appearance that contributed to consumer liking/disliking the fruit. More specifically, the objective of the study was to guide producers regarding the target appearance attributes that play a role on consumer acceptance of cherry tomatoes. Ten accessions of organic cherry tomatoes were evaluated by a trained panel using the QDA methodology, and also by 80 tomato consumers for the acceptance of appearance and intention to purchase. The results achieved after integrating these two data sets (from the trained panel and consumers) in a multidimensional map allowed the elucidation of consumer liking of tomatoes in relation to the appearance, i.e. drivers of liking/disliking were identified. Results revealed that tomatoes with round shape and red colour (reddish) (cultivar ENAS 1031, ENAS 1010, ?Perinha Agua Branca?, Super Sweet, and ?Joana?) were the most liked cherry tomatoes. Those genotypes were also liked by the smallest segment (17.5% of participants) but for them unusual shapes (oblong and pear), orange-yellow colour, and bigger size were also liked. Despite the small number of participants in this study (80 consumers), new shapes and colours for the organic cherry tomatoes could be considered promising alternatives in the Brazilian market, and can be an opportunity for the producers of the state of Rio de Janeiro
Acúmulo de biomassa da cana-de-açúcar irrigada durante ciclo de ressoca no Submédio do Vale do São Francisco.
Influência das mudanças climáticas no ciclo fenológico e na demanda hÃdrica da manga cv. Kent.
Acúmulo e exportação de micronutrientes pela cana-de-açucar irrigada no Semiárido brasileiro.
Acúmulo de nutrientes pela cana de açúcar irrigada cultivada no Semiárido tropical brasileiro.
Aharonov-Bohm-like effect for light propagating in nematics with disclinations
Using a geometric approach for the propagation of light in anisotropic media,
we investigate what effect the director field of disclinations may have on the
polarization state of light. Parallel transport around the defect, of the
spinor describing the polarization, indicates the acquisition of a topological
phase, in analogy with the Aharonov-Bohm effect.Comment: 6 pages, to appear in Europhysics Letter
Flutuação populacional de Spodoptera frugiperda (J. E. Smith), Diatraea saccharalis (Fabricius) e Doru luteipes (Scuder) em milho convencional e transgênico Bt.
O surgimento de tecnologias para o controle de pragas na cultura do milho deve ser analisado periodicamente, para a adoção nas regiões produtoras desse cereal. O objetivo deste trabalho foi avaliar a flutuação populacional de Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), Diatraea saccharalis (Fabricius) (Lepidoptera: Pyralidae) e do predador Doru luteipes (Scudder) (Dermaptera: Forficulidae) em cultivo de milho convencional e Bt. O ensaio foi conduzido na safrinha, em Rio Verde, GO, com delineamento experimental de blocos casualizados, com 24 repetições. Foram empregados os hÃbridos P 3041 e P 3041YG, com população de 50.000 plantas.ha-1. Quantificaram-se o número de insetos e os danos provocados pelas lagartas nas folhas, colmo e pendão, quantificação e presença de internódios com galerias, altura de plantas e da inserção de espiga, massa de grãos por espiga e rendimento de grãos. O hÃbrido de milho P 3041YG sofreu menor ataque de S. frugiperda e apresentou maior massa de grãos por espiga e maior rendimento de grãos em relação ao hÃbrido convencional P 3041
Assessment of the Kinematic Adaptations in Parkinson’s Disease Using the Gait Profile Score: Influences of Trunk Posture, a Pilot Study
Introduction: Postural abnormalities are common in patients with Parkinson’s disease (PD) and lead to gait abnormalities. Relationships between changes in the trunk posture of PD patients and gait profile score (GPS) and gait spatiotemporal parameters are poorly investigated. The aim of the current study was to investigate the relationships between trunk posture, GPS, and gait spatiotemporal parameters, in patients with PD. Materials and Methods: Twenty-three people with PD and nineteen age-matched healthy people participated in this study. A 3D gait kinematical analysis was applied to all participants using the Plug-In Gait Full Body™ tool. Trunk and limb kinematics patterns and gait spatio-temporal parameters of patients with PD and the control group were compared. Additionally, correlations between trunk kinematics patterns, gait spatio-temporal parameters, and GPS of the PD group were tested. Results: Cadence, opposite foot off, step time, single support, double support, foot off, gait speed, trunk kinematics, and GPS showed significant differences between the two groups (p ≤ 0.05). Posture of the trunk during gait was not related to the spatio-temporal parameters and gait profile score in the PD group. The trunk flexor pattern influenced GPS domains, mainly of the ankle and the knee. Discussion and Conclusions: Flexed posture of the trunk in patients with PD seems to influence both ankle and knee movement patterns during the gait. The GPS analysis provided direct and simplified kinematic information for the PD group. These results may have implications for understanding the importance of considering the positioning of the trunk during gait
Bio-Guided Optimization of Cystoseira abies-marina Cosmeceuticals Extraction by Advanced Technologies
Cystoseira abies-marina (reclassified as Gongolaria abies-marina) is a brown seaweed species rich in meroterpenoids, presenting interesting antioxidant, antitumor, and anti-inflammatory activities. However, there is still a lot to uncover regarding the bioactive potential of this species, as evidenced by the lack of records of antiaging activities from Cystoseira abies-marina, making this macroalga an excellent candidate for studies of its cosmeceutical potential. Ultrasound-(UAE) and microwave-assisted extraction (MAE) are advanced sustainable technologies that are very efficient in enhancing bioactive compound extraction. Applying these extraction techniques to a new biological matrix often calls for optimizing the parameters toward the best extraction yield. Since Cystoseira abies-marina is a new matrix for both UAE and MAE techniques, the present work proposes the optimization of the extraction process, using a novel approach: instead of only focusing on increasing the yield, the goal of this work is to determine the parameters for UAE and MAE that lead to extracts with better antiaging activities. For this bio-guided approach, several Cystoseira abies-marina extracts were prepared by UAE and MAE under varying conditions of solvent, time, and algae/solvent ratios. Their antiaging activities were then determined, and all the results combined to unveil the conditions yielding extracts with higher cosmeceutical potential. Using statistical tools, it was found that, for UAE, the best conditions were ethyl acetate, 15 min, and a ratio of 1:4, which led to an extract with high yield, and causing the strong inhibition of tyrosinase and elastase. In turn, ethanol, 10 min, and a ratio of 1:4 were the best conditions for MAE, leading to the extract with the best antioxidant activity. The results show that the proposed bio-guided approach was effective in obtaining extracts with high cosmeceutical potential, unveiling the possibility of modulating an extract’s activity by changing the extraction method.FUNDING: Thanks are due to FCT—Fundação para a Ciência e a Tecnologia for supporting G.P.R.’s grant (SFRH/BD/144446/2019), through National and European Funds and co-financed by the European Social Fund through the Regional Operational Programme Centro 2020, as well as to FCT, the European Union, QREN, FEDER, and COMPETE, through funding the cE3c center (UIDB/00329/2020). This work received financial support from PT National Funds (FCT/MCTES, Fundação para a Ciência e a Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through projects UIDB/50006/2020 and UIDP/50006/2020. A.F.P. thanks FCT for funding through the Individual Call to Scientific Employment Stimulus (2020.01614.CEECIND/CP1596/CT0007).info:eu-repo/semantics/publishedVersio
- …