922 resultados para Seeds - Accelerated aging
Resumo:
For many learning tasks the duration of the data collection can be greater than the time scale for changes of the underlying data distribution. The question we ask is how to include the information that data are aging. Ad hoc methods to achieve this include the use of validity windows that prevent the learning machine from making inferences based on old data. This introduces the problem of how to define the size of validity windows. In this brief, a new adaptive Bayesian inspired algorithm is presented for learning drifting concepts. It uses the analogy of validity windows in an adaptive Bayesian way to incorporate changes in the data distribution over time. We apply a theoretical approach based on information geometry to the classification problem and measure its performance in simulations. The uncertainty about the appropriate size of the memory windows is dealt with in a Bayesian manner by integrating over the distribution of the adaptive window size. Thus, the posterior distribution of the weights may develop algebraic tails. The learning algorithm results from tracking the mean and variance of the posterior distribution of the weights. It was found that the algebraic tails of this posterior distribution give the learning algorithm the ability to cope with an evolving environment by permitting the escape from local traps.
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Lipid transfer proteins (LTPs) were thus named because they facilitate the transfer of lipids between membranes in vitro. This study was triggered by the characterization of a 9-kDa LTP from Capsicum annuum seeds that we call Ca-LTP(1). Ca-LTP(1) was repurified, and in the last chromatographic purification step, propanol was used as the solvent in place of acetonitrile to maintain the protein`s biological activity. Bidimensional electrophoresis of the 9-kDa band, which corresponds to the purified Ca-LTP(1), showed the presence of three isoforms with isoelectric points (pIs) of 6.0, 8.5 and 9.5. Circular dichroism (CD) analysis suggested a predominance of alpha-helices, as expected for the structure of an LTP family member. LTPs immunorelated to Ca-LTP(1) from C. annuum were also detected by western blotting in exudates released from C. annuum seeds and also in other Capsicum species. The tissue and subcellular localization of Ca-LTP(1) indicated that it was mainly localized within dense vesicles. In addition, isolated Ca-LTP(1) exhibited antifungal activity against Colletotrichum lindemunthianum, and especially against Candida tropicalis, causing several morphological changes to the cells including the formation of pseudohyphae. Ca-LTP(1) also caused the yeast plasma membrane to be permeable to the dye SYTOX green, as verified by fluorescence microscopy. We also found that Ca-LTP(1) is able to inhibit mammalian alpha-amylase activity in vitro.
Resumo:
A lectin and a galactoxyloglucan were characterized from Mucuna sloanei seed cotyledons. The galactoxyloglucan, isolated by water extraction and ethanol precipitation, had Glc:Xyl:Gal proportions in a molar ratio of 1.8:1.7:1.0 and a molar mass (M(w)) of 1.6 x 10(6) g mol(-1). The lectin (sloanin), isolated from the same seed by affinity chromatography on cross-linked Adenanthera pavonina galactomannan, gave two protein bands by SDS-PAGE (36 and 34 kDa) and one peak by gel filtration (63.6 kDa). Its N-terminal sequence indicated similar to 69% identity with soybean agglutinin to leguminous lectins. Circular dichroism (CD) spectra established that sloanin predominantly contains beta-sheet structures. Sloanin has similar to 5.5% carbohydrate and displayed hemagglutinating activity against rabbit and enzyme treated human erythrocytes, inhibited only by D-Gal containing sugars. The interaction between sloanin and storage cell-wall galactoxyloglucan was tested by affinity chromatography and fluorescence spectroscopy. (C) 2009 Elsevier Ltd. All rights reserved.
Resumo:
Abrus pulchellus seeds contain at least seven closely related and highly toxic type 2 ribosome-inactivating pulchellins, each consisting of a toxic A-chain linked to a sugar binding B-chain. In the present study, four pulchellin isoforms (termed P I, P II, P III and P IV) were isolated by affinity, ion exchange and chromatofocusing chromatographies, and investigated with respect to toxicity and sugar binding specificity. Half maximal inhibitory concentration and median lethal dose values indicate that P I and P II have similar toxicities and that both are more toxic to cultured HeLa cells and mice than P III and P IV. Interestingly, the secondary structural characteristics and sugar binding properties of the respective pairs of isoforms correlate well with the two toxicity levels, in that P I/P II and P III/P IV form two specific subgroups. From the deduced amino acids sequences of the four isoforms, it is clear that the highest similarity within each subgroup is found to occur within domain 2 of the B-chains, suggesting that the disparity in toxicity levels might be attributed to subtle differences in B-chain-mediated cell surface interactions that precede and determine toxin uptake pathways.
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Oxidative DNA damage plays a role in disease development and the aging process. A prominent participant in orchestrating the repair of oxidative DNA damage, particularly single-strand breaks, is the scaffold protein XRCC1. A series of chronological and biological aging parameters in XRCC1 heterozygous (HZ) mice were examined. HZ and wild-type (WT) C57BL/6 mice exhibit a similar median lifespan of similar to 26 months and a nearly identical maximal life expectancy of similar to 37 months. However, a number of HZ animals (7 of 92) showed a propensity for abdominal organ rupture, which may stem from developmental abnormalities given the prominent role of XRCC1 in endoderm and mesoderm formation. For other end-points evaluated-weight, fat composition, blood chemistries, condition of major organs, tissues and relevant cell types, behavior, brain volume and function, and chromosome and telomere integrity-HZ mice exhibited by-and-large a normal phenotype. Treatment of animals with the alkylating agent azoxymethane resulted in both liver toxicity and an increased incidence of precancerous lesions in the colon of HZ mice. Our study indicates that XRCC1 haploinsufficiency in mammals has little effect on chronological longevity and many key biological markers of aging in the absence of environmental challenges, but may adversely affect normal animal development or increase disease susceptibility to a relevant genotoxic exposure.
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An approach was developed to estimate molecular weight distribution of water-soluble Cu, Fe, Mn and Zn species in Brazil nut, cupuassu seed and coconut pulp by size exclusion chromatography (SEC) coupled on-line to ultra-violet (UV) and off-line to graphite furnace atomic absorption spectrometry (GF-AAS) detectors and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). SEC-UV analytical signals showed the prevalence of high molecular weight (HMW) species (79-1.7 kDa for Brazil nut, 50-1.7 kDa for coconut pulp, and 34-1.7 kDa for cupuassu seeds). The Brazil nut SEC-UV, GF-AAS and MALDI-TOF mass spectra gave confirmation of the association of the elements with water-soluble compounds. The elemental profiles were associated with fractions of compounds of molecular weight 1.2-16 kDa for Brazil nut, 1.7-13 kDa for coconut pulp, and 1.2-7.6 kDa for cupuassu seeds. (C) 2009 Elsevier Inc. All rights reserved.
Resumo:
A method for the multi-elemental determination of metals (Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Sr and Zn), metalloids (B and Si), and non-metals (Cl, P and 5) in the babassu nut and mesocarp, sapucaia nut, coconut pulp, cupuassu pulp and seed, and cashew nut by axially viewed inductively coupled plasma optical emission spectrometry is presented. A diluted oxidant mixture (2 ml HNO(3) + 1 ml H(2)O(2) + 3 ml H(2)O) was used to achieve the complete decomposition of the organic matrix in a closed-vessel microwave oven. The accuracy of the entire proposed method was confirmed by standard reference material analysis (peach leaves-NIST SRM1547). The certified values showed a good agreement at a 95% confidence limit (Student`s t-test). The average RSD for repeatability of calibration solutions measurements were in the range of 1.1-6.7%. Limits of quantification (LOQ = 10 x LOD) were in the level of 0.00072-0.0532 mg/l. The macro and micronutrient ranges in the different nuts and seeds did not exceed the dietary reference intake (DRI), except for Mn in the babassu nut. (C) 2010 Published by Elsevier Ltd.
Resumo:
The essential oil from seeds of Licaria puchury-major was isolated by hydrodistillation. The chemical composition of the oil was analyzed by GC and GUMS. Sixteen compounds were identified, representing 91.4% of the total oil. The major components were safrole (58.4%), dodecanoic acid (13.7%) and alpha-terpineol (8.4%). Oxygenated monoterpenoids were the main group of compounds.
Resumo:
In this paper I investigate how philosophy can speak for children and how children can have a voice in philosophy and speak for philosophy. I argue that we should understand children as responsible rational individuals who are involved in their own philosophical inquiries and who can be involved in our own philosophical investigations-not because of their rational abilities, but because we acknowledge them as conversational partners, acknowledge their reasons as reasons, and speak for them as well as let them speak for us and our rational community. In order to argue this I turn, first, to Gareth Matthews' philosophy of childhood and suggest a reconstruction of some of his concepts in line with the philosophy of Stanley Cavell. Second, in order to examine more closely our conceptions of rationality and our pictures of children, I consider the children's books, The Lorax and Where is My Sister? and Henrik Ibsen's play, The Wild Duck.
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Sustainable methods are required to protect newly planted tree seedlings from insect herbivore attack. To this end, here Norway spruce (Picea abies (L.) Karst.) seeds were treated with 2.5 mM nicotinamide (NIC), 2.5 mM nicotinic acid (NIA), 3 mM jasmonic acid (JA) or 0.2 mM 5-azacytidine (5-Aza), and 6-month-old seedlings grown from these seeds were planted at a reforestation area in central Sweden. Attack by pine weevils (Hylobius abietis) was reduced by 50 per cent by NIC treatment, 62.5 per cent by JA treatment and 25 per cent by 5-Aza treatment, when compared with seedlings grown from untreated seeds. Watering 18-month-old spruce seedlings with 2 mM NIC or 2 mM NIA did reduce attack during the first season in the field by 40 and 53 per cent, respectively, compared with untreated plants. Girdling was also reduced by the different treatments. Analysis of conifer seedlings treated with 5-Aza points at a possible involvement of epigenetic mechanisms in this defensive capacity. This is supported by a reduced level of DNA methylation in the needles of young spruce seedlings grown in a greenhouse from NIC-treated seeds. Seed treatment for seedling defense potentiation is simple, inexpensive and also a new approach for forestry with many potential applications.
Resumo:
Although the need to make health services more accessible to persons who have migrated has been identified, knowledge about health-promotion programs (HPPs) from the perspective of older persons born abroad is lacking. This study explores the design experiences and content implemented in an adapted version of a group-based HPP developed in a researcher-community partnership. Fourteen persons aged 70-83 years or older who had migrated to Sweden from Finland or the Balkan Peninsula were included. A grounded theory approach guided the data collection and analysis. The findings showed how participants and personnel jointly helped raise awareness. The participants experienced three key processes that could open doors to awareness: enabling community, providing opportunities to understand and be understood, and confirming human values and abilities. Depending on how the HPP content and design are being shaped by the group, the key processes could both inhibit or encourage opening doors to awareness. Therefore, this study provides key insights into how to enable health by deepening the understanding of how the exchange of health-promoting messages is experienced to be facilitated or hindered. This study adds to the scientific knowledge base of how the design and content of HPP may support and recognize the capabilities of persons aging in the context of migration.
Resumo:
Esta dissertação mapeia a rede de relações intertextuais em Half a Life (2001) e sua continuação Magic Seeds (2004), os romances mais recentes do Prêmio Nobel de Literatura de 2001, V. S. Naipaul, como contribuição para o estudo da obra do autor. A noção de intertextualidade permeia os estudos literários, e o termo tem sido largamente empregado desde que foi cunhado por Julia Kristeva nos anos sessenta. Desde então as mais variadas, e muitas vezes divergentes, teorias sobre intertextualidade compartilham a idéia de que um texto só adquire significado pleno na interação com outros textos. A abordagem metodológica proposta é baseada na teoria da transtextualidade de Gérard Genette. Esta escolha implica o estudo de intertextos, paratextos, metatextos, arquitextos e hipertextos que constituem a interface entre os dois romances e outros escritos. O nome do protagonista "William Somerset Chandran" constitui o fio que guia o estudo das várias relações transtextuais nos dois romances. A partir do prenome do protagonista – William – este estudo situa os romances no contexto da tradição do Bildungsroman, e argumenta que estes estabelecem uma paródia arquitextual do gênero na medida em que subvertem seu cerne, ou seja, a formação do caráter do protagonista. O nome do meio do protagonista – Somerset – remete à ficcionalização do escritor Somerset Maugham na narrativa, ao mesmo tempo em que esta desmistifica a ótica ocidental sobre o hinduísmo popularizada por Maugham em The Razor's Edge. O sobrenome do protagonista – Chandran – leva ao estudo do conjunto de referências à origem indiana de Naipaul e o papel desta na produção do autor. Este nome se reporta ao romance de Narayan The Bachelor of Arts, cujo protagonista também é nomeado Chandran. Narayan é um escritor de destaque na literatura anglo-indiana e referência recorrente na obra de Naipaul. Os temas de migração e choque cultural apresentados nos dois romances têm sido presença constante na obra de Naipaul. Esta pesquisa mapeia a relação de continuidade entre os dois romances em questão e o conjunto da obra de Naipaul, salientando o papel da ambientação geográfica da narrativa, marcada pela jornada do protagonista através de três continentes. A teoria da transtextualidade é uma ferramenta operacional para a pesquisa, a qual examina a densidade das referências geográficas, históricas e literárias em Half a Life e Magic Seeds, visando aportar elementos para o estudo da produção literária de Naipaul, na medida em que estes romances recentes condensam e revisitam a visão de mundo deste autor.
Resumo:
Physical Activity (PA) and functional fitness (FF) are predictors of a healthy and independent lifestyle in older adults. The purpose of this study was: (1) to construct reference values for FF; (2) to describe sex- and age-related changes in FF, balance, gait, PA, body composition, and bone health/strength; and (3) to determine their variation and co-variation with respect to PA. This cross-sectional study included 401 males and 401 females aged 60-79 years old. FF was assessed using the Senior Fitness test and balance by the Fullerton Advance Balance scale (FAB). Gait parameters: gait velocity (GV), stride length (SL), cadence and gait stability ratio (GSR) were measured. Femoral strength index (FSI) and bone mineral density (BMD) of the total body, lumbar spine, hip region and total lean tissue mass (TLTM) and total fat mass (TFM) were determined by dual-energy x-ray absorptiometry-DXA. PA was assessed during face-to-face interviews using the Baecke questionnaire. Demographic and health history information were obtained by structured telephone interview. In both sexes, a significant main effect for age-group was found for FF parameters, balance scores, gait performances, TLTM and hip, LS and total BMD and FSI. Likewise there were significant main effects for age-group for total PA in women and sports related PA in men. Men scored significantly better than women in FF (except in upper- and lower-body flexibility), balance, GV, SL, GSR and had higher BMD and TLTM compared with women. Active subjects scored better in FF, balance, and gait than their average and non-active peers. PA and FF exerted only a minor influence in the differentiation of BMD and FSI among the elderly while constitutive factors like age, height, body mass, TLTM and TFM entered as the most significant contributors. This study gives scientific support to public policies at the community level, targeted to increase PA, FF and TLTM, thereby contributing to improved quality of life in older adults.