1,721,015 research outputs found
Plant cultivation for Bioregenerative Life Support Systems (BLSSs) in Space
No full textHuman colonization of Space relies on the efficient realization of Bioregenerative Life Support Systems (BLSSs), for resources regeneration during long term missions or in planetary stations.
Higher plants play a key role in BLSSs, thank to their “complementary” interrelationship with humans: in a simplistic vision, plants recycle human waste and provide food to humans, while humans recycle plant waste and provide nutrients to plants. Specifically, plants are able to regenerate air through photosynthetic absorption of carbon dioxide and oxygen emission, to recover water through transpiration, and to convert waste products in biomass through mineral nutrition. In addition, they can provide fresh food to integrate the crew diet and help to preserve the astronauts’ wellbeing.
However, realizing resource regeneration at high and continuous rate, and food production stable in quantity and quality, requires the proper choice of plant crops and varieties, which must be compliant with the specific growth environment and fulfil the astronauts needs, and of cultivation techniques, which must be feasible under the several constraints of Space vehicles and colonies (including reduced availability of crew-time, volume and energy, altered gravity).
Based on technical and dietary requirements, several plant species (e.g. tomato, lettuce, wheat, potato, soybean) are studied in Space research programs as candidates for cultivation in BLSSs. Experiments are conducted in growth chamber, mainly by using closed-loop hydroponic (soilless) cultivation systems, in order to design Space greenhouses where each environmental factor (e.g. light, temperature, air composition, water and nutrients availability) can be precisely modulated to optimize plant performance.
For long time our team has been realizing experiments aiming to investigate the adaptation of various crops to hydroponics in controlled environment, by considering both biological and agro-technological issues. Wide attention is dedicated to the influence of several parameters (e.g. hydroponic system, nitrogen source in the nutrient solution, influence of microbes in the rhizosphere) on plant behaviour, in order to identify cultivation protocols able to maximise the plant productivity and the resource use efficiency, even while reducing plant sensitivity to space stressors and enhancing the nutritional quality of products.
The lecture will present an overview on the achievements and the current research in agro-technology in controlled environment, and the related technical and scientific issues. Focus will be on our experience on plant cultivation for BLSSs
Allometric model for leaf area estimation in Bougainvillea genotypes.
No full textAccurate estimates of leaf area (LA) are an urgent need for modeling eco-physiological processes within urban greening. LA can be measured by direct or indirect methods. The direct methods are fast, but require leaf excision and it is therefore not possible to make sequential measurements. An alternative tool would be to develop allometric models that relate the individual LA to the linear measurements of leaf length (L) and maximum width (W). The development of an unbiased allometric model from linear measurements to predict individual LA of Bougainvillea irrespective of genotypes is still lacking. The models were built using LA, L, and W data measured in 600 leaves collected from four Bougainvillea genotypes: B. glabra LSQUOCrimson LakeRSQUO, B. spectabilis LSQUOLady WilsonRSQUO, LSQUOMary PalmerRSQUO and LSQUORubianaRSQUO. Model validation was performed on 150 Bougainvillea leaves collected from another genotype (B. spectabilis LSQUOFucsia colorRSQUO). LA prediction models based only on L or W measurements were not suitable for estimating LA of Bougainvillea. A linear model having the product L×W as independent variable (LA = -1.36 +0.63 LW) provided the most accurate estimate highest r2 (0.95), smallest MSE, smallest prediction sum of squares (PRESS), and to the reasonably close PRESS value to error sum of squares. In the model validation, correlation coefficients showed that there was a highly reliable relationship between the predicted and the observed LA values with an underestimation of 3.7%. The LA model using L×W as independent variable can be successfully adopted in research on Bougainvillea, since it provides an accurate, simple non-destructive estimation of LA across Bougainvillea genotypes avoiding the use of any expensive device such as electronic leaf area meters and plant canopy analyzers
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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