237 research outputs found
Effects of genotype and sowing date on phytostanol-phytosterol content and agronomic traits in wheat under organic agriculture
Cereals are an important source of sterols and stanols in the human diet. The present study underlines the effect of genotype and weather conditions in bread wheat, on total sterol and stanol content (TSS), agronomic traits, proteins and ash content under organic conditions. Variations in TSS as well as other characters between two sowing dates were observed. A broad genotypic variability was also reported since extreme genotypes differed by more than 30 mg 100. g-1 DW for TSS, with total stanol content varying twofold. Moreover, two groups of genotypes that differed in agronomic production, ash and protein content were depicted, based on their response to an increase in temperature. This result suggests that the genotypic factor prevails over the sowing date factor for determining sterol and stanol traits in wheat cultivated under organic conditions. Nevertheless, a strong interaction exists between the two factors, which can be used to drive bioaccumulation of these molecules
Sterol concentration and distribution in sunflower seeds (Helianthus annuus L.) during seed development
Sunflower seeds are currently used for edible oil production. Among oil minor compounds, phytosterols are of special interest due to their cholesterol reducing properties. This paper reports studies on their accumulation and distribution in the embryo and hull, and the effects of temperature on phytosterol contents in sunflower seed produced under both conventional and organic field conditions. An optimized method of sterol determination, adapted to studies on small samples of seed, is presented. Seventy-two % of phytosterols were found in the embryo, 28 % in the hull. The periods of phytosterols concentration varied according to sterol category and seed part. Application of these results to improve production of natural sterols for functional food use is discussed
Sterol content in sunflower seeds (Helianthus annuus L.) as affected by genotypes and environmental conditions
Phytosterols play essential roles in many plant cell mechanisms. They are of industrial interest since, as part of the diet, they can reduce Low Density Lipoprotein cholesterol. An increase in plant sterol contents by improved crop varieties or crop management could help to answer industrial demands and also to develop environmentally friendly extraction methods. The aim of this study was to evaluate genotypic variability for sterol content in cultivated sunflower and effects of sowing date, in particular sowing date. Results showed large variability among a collection of sixteen sunflower inbred lines and hybrids. Total sterols varied almost twofold between extreme genotypes. A delay of sowing, giving higher temperatures during seed formation, induced a general increase in total sterol concentration by up to 35 per cent, as well as sterol composition but this varied according to genotype. These results are discussed with the aim of improving sterol content by sunflower breeding programmes
Dispositif de réalité virtuelle et dividuation: Un dialogue entre art et philosophie autour de la recherche d'une nouvelle ontologie
Following Simondonâs recommendation written to Derrida in 1982 we will try to transpose it to ourcontemporary perceptive modalities structured by our relationship with digital technologies.This article will then introduce the work that I carry out between art and philosophy, how it offers an originalway of considering research and leads me to try to think a new ontology.Through digital interfaces and our relationships to what will be defined as a digital milieu, a new way of beingin the world is materializing, taking shape and asserting itself.Against a certain tradition of the Western philosophy to seek for unity and stability it will be necessary here toinvestigate the fragmented and the process in order to suggest to think a new ontology, of dividuation
Can Peto\u27s paradox be used as the null hypothesis to identify the role of evolution in natural resistance to cancer? A critical review
BACKGROUND: Carcinogenesis affects not only humans but almost all metazoan species. Understanding the rules driving the occurrence of cancers in the wild is currently expected to provide crucial insights into identifying how some species may have evolved efficient cancer resistance mechanisms. Recently the absence of correlation across species between cancer prevalence and body size (coined as Peto\u27s paradox) has attracted a lot of attention. Indeed, the disparity between this null hypothesis, where every cell is assumed to have an identical probability to undergo malignant transformation, and empirical observations is particularly important to understand, due to the fact that it could facilitate the identification of animal species that are more resistant to carcinogenesis than expected. Moreover it would open up ways to identify the selective pressures that may be involved in cancer resistance. However, Peto\u27s paradox relies on several questionable assumptions, complicating the interpretation of the divergence between expected and observed cancer incidences. DISCUSSIONS: Here we review and challenge the different hypotheses on which this paradox relies on with the aim of identifying how this null hypothesis could be better estimated in order to provide a standard protocol to study the deviation between theoretical/theoretically predicted and observed cancer incidence. We show that due to the disproportion and restricted nature of available data on animal cancers, applying Peto\u27s hypotheses at species level could result in erroneous conclusions, and actually assume the existence of a paradox. Instead of using species level comparisons, we propose an organ level approach to be a more accurate test of Peto\u27s assumptions. SUMMARY: The accuracy of Peto\u27s paradox assumptions are rarely valid and/or quantifiable, suggesting the need to reconsider the use of Peto\u27s paradox as a null hypothesis in identifying the influence of natural selection on cancer resistance mechanisms
Formation of Dust in the Ejecta of Type Ia Supernovae
We investigate the formation of dust grains in the ejecta of Type Ia
supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the
calculations of dust formation, we apply the nucleation and grain growth theory
and consider the two cases with and without formation of CO and SiO molecules.
The results of the calculations show that for the sticking probability of
alpha_j=1, C, silicate, Si, and FeS grains can condense at early times of
~100--300 days after the explosion, whereas Fe and SiC grains cannot form
substantially. Due to the low gas density in SNe Ia with no H-envelope, the
average radii of the newly formed grains are generally below 0.01 micron, being
much smaller than those in Type II-P SNe. This supports our previous conclusion
that the radius of dust formed in the ejecta is smaller in SNe with less
massive envelopes. The total dust mass ranges from 3x10^{-4} M_sun to 0.2 M_sun
for alpha_j=0.1--1, depending on whether or not CO and SiO molecules are
formed. We also estimate the optical depths and thermal emission by the newly
formed dust and compare to the relevant observations of SNe Ia. We find that
the formation of C grains in SNe Ia is suppressed to be consistent with the
observational constraints. This implies that energetic photons and electrons
heavily depress the formation efficiency of C grains or that the outermost C-O
layer of SNe Ia is almost fully burned. Finally, we perform the calculations of
dust destruction in the SN remnants and find that dust grains formed in the
ejecta of SNe Ia are almost completely destroyed in the shocked gas before
being injected into the interstellar medium. This indicates that SNe Ia are
unlikely to be the major sources of interstellar dust.Comment: 13 pages, 7 figures, 2 tables. Accepted for publication in Ap
General Practitioners involvement in enteral tube feeding at home: a qualitative study
<p>Abstract</p> <p>Background</p> <p>Complex medical treatment is moving from hospital to primary care and General Practitioners (GPs) are increasingly asked to undertake new roles. There are now an estimated 19,500 patients being fed in the UK in the community on enteral tube feeding using a variety of different feeding tubes (Percutaneous endoscopic gastrostomy (PEG), Jejunostomy, or nasogastric (NG). The majority of patients are over the age of 65 years when they had artificial feeding initiated and mainly because of dysphagia. The aim of this study was to explore GPs knowledge, attitudes and skills relating to enteral feeding in the community.</p> <p>Methods</p> <p>Semi-structured one-to-one interviews with a convenience sample of GPs in Northern Ireland.</p> <p>Results</p> <p>Twenty-three GPs in three health boards in Northern Ireland participated in the study. Most found dealing with enteral feeding to be a predominantly negative experience. They had little involvement in patient selection for the procedure and poor or no discharge information. GPs felt inadequately trained, there was poor communication between primary and secondary care and little support. There was anger and frustration among GPs about lack of resources (funding and training), and the perception that primary care was used as a dumping ground.</p> <p>Conclusion</p> <p>Moving complex medical treatment from secondary to primary care has major implications for GPs who should be included in the patient selection process, have adequate discharge information about their patients, be adequately resourced and have appropriate support and training.</p
Research priorities for nutrition of school-aged children and adolescents in low- and middle-income countries.
PURPOSE: A lack of data, intervention studies, policies, and targets for nutrition in school-age children (SAC) and adolescents (5-19 years) is hampering progress towards tackling malnutrition. To stimulate and guide further research, this study generated a list of research priorities. METHODS: Using the Child Health and Nutrition Research Initiative (CHNRI) method, a list of 48 research questions was compiled and questions were scored against defined criteria using a stakeholder survey. Questions covered all forms of malnutrition, including micronutrient deficiencies, thinness, stunting, overweight/obesity, and suboptimal dietary quality. The context was defined as research focused on SAC and adolescents, 5 to 19 years old, in low-and middle-income countries, that could achieve measurable results in reducing the prevalence of malnutrition in the next 10 years. RESULTS: Between 85 and 101 stakeholders responded per question. Respondents covered a broad geographical distribution across 38 countries, with the largest proportion focusing on work in East and Southern Africa. Of the research questions ranked in the top ten, half focused on delivery strategies for reaching adolescents and half on improving existing interventions. There were few differences in the ranked order of questions between age groups but those related to in-school children and adolescents had higher expert agreement than those for out-of-school adolescents. The top ranked research question focused on tailoring antenatal and postnatal care for pregnant adolescent girls. CONCLUSION: Nutrition programmes should incorporate implementation research to inform delivery of effective interventions to this age group, starting in schools. Academic research on the development and tailoring of existing nutrition interventions is also needed; specifically, on how to package multisectoral programmes and how to better reach vulnerable and underserved sub- groups, including those out of school
Systematic mechanical assessment of consolidants for canvas reinforcement under controlled environment
In conservation, adhesives are commonly used for the consolidation of canvases, yet their impact upon the canvas longevity has raised some concerns amongst conservators. As such, this study presents a testing protocol developed to assess the performance of commonly-used adhesives (natural animal glue and synthetic BevaÂź 371) and a newly developed nanocellulose consolidant, nanofibrillated nanocellulose (CNF). This includes their effect on the visual appearance, consolidation, and response of the mechanical properties of the treated canvases to programmed changes in relative humidity (RH). Scanning electron microscopy (SEM) images of animal glue- and BevaÂź 371-treated canvases revealed the presence of adhesive and consolidant on and in-between cotton fibres. The consolidants form bridges linking and connecting the cotton fibres and holding them together, whereas the CNF treatment, formed a visible continuous and dense surface coating. None of the treatments induced any discernible colour change. Controlled environment mechanical testing was performed in two ways: by applying a linearly increasing static force at fixed RH (Youngâs modulus) and by applying a dynamic force together with a programmed RH cycling between 20 and 80% (RH dependent viscoelastic properties). CNF gave a higher value of Youngâs modulus than either of the two commonly-used materials. Measurements at different values of RH (20 and 80%) demonstrated for all the treated canvases that at the lower value (RH 20%) Youngâs modulus values were higher than at the higher value (RH 80%). Besides, the dynamic mode showed that the rate of response in all cases was rapid and reversible and that the nanofibrillated cellulose treated sample showed the highest variation in storage (or elastic) modulus measured at the end of RH plateaux (20 and 80% RH). Thus CNF appears to be a promising material given its higher mechanical performance. The protocol developed in this study has enabled us to examine and compare candidate materials for the consolidation of canvases systematically, using testing parameters that remained relevant to the field of canvas conservation
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