170,504 research outputs found
Physiological causes of yield variation in cassava (Manihot esculenta Crantz)
No full textCassava (Manihot esculenta Crantz) is an important crop in many parts of the tropics, being mainly cultivated for its storage roots. Farmers' yields are low and one of the constraints to higher yields is the lack of adequate clones. At the beginning of the 1970s an extensive cassava research programme was started at CIAT (Colombia). One of its aims was to develop high-yielding clones by genetic modification of the plant habitus.This thesis begins with a literature review in which the available information on the physiological determinants of the yield of cassava storage roots is described.Next, a series of experiments carried out to deepen and to broaden this knowledge on physiological causes of yield variation in cassava is described. MCol 1684 (the best cultivar of the CIAT cassava germ plasm bank) and MPtr 26 were used as the reference cultivars in the experiments, both in the field and in the greenhouse.Rate of leaf photosynthesis was measured by infrared gas analysis. Measurements of the photosynthetic rate were carried out using the youngest fully expanded leaf from plants growing outdoors that were 35 - 45 days old. Maximum photosynthetic rates varied from 0.74 x 10 -6to 0.81 x 10 -6kg CO 2 .m -2leaf.s -1. MCol 22 had the highest leaf photosynthetic rate. A relatively low photonflux density level was required for light saturation of the photosynthetic rate. This is characteristic for a plant species with a C 3 cycle. Photosynthesis increased only slightly from 1000 to 1500 μE .m -2.s -1PAR (photosynthetically active radiation). Light efficiency at low light intensities (α) varied from 9.0 x 10 -9to 12.4 x 10 -9kg CO 2 .J -1. The CO 2 concentration remained at an approximately constant level in the intercellular spaces, independent of the light level, being 212 vppm (0.387 x 10 -3kg.m -2). At a photonflux density of 1500 μE.m -2.s -1mesophyl resistance was higher than leaf resistance to CO 2 (335 s.m -1compared with 185 s.m -1). Transpiration rates did not differ between clones, but increased with light intensity. water use efficiency (WUE)varied from 15.1 to 17.1 mg CO 2 uptake per g H 2 O, and was most efficient for MCol 22.Linear relationships were found between total dry matter yield and the amount of intercepted PAR. Photosynthetic efficiency varied from 1.9% to 2.5%, based on PAR during the first six months of the growth period, and decreased markedly in older plants. The fraction of incoming intercepted PAR varied from 43% to 69% during the first six months. Cultivars had an extinction coefficient (K) of 0.72 to 0.88 and their leaves were dominantly planophile.A leaf area index (LAI) of 1.0 (about 50% light interception) was attained at 60 to 90 days from planting. An LAI = 3, which coincides with a light interception by the leaf canopy of approximately 90% was reached 120 to 150 days after planting, so about 40% of a growth period of one year had elapsed before complete ground cover was achieved. Genotypes with very different canopy characteristics reached an LAI of 3 in approximately the same time.Cassava has an indeterminate habit with sympodial branching. The length of the period until first branching depended on genotype and planting date. Large genetic differences were found in leaf life, leaf size, plant age at which maximum leaf size was reached and leaf formation rate per apex. Small variations in environmental conditions caused significant differences in canopy characteristics.During the growth period of cassava two periods with constant dry matter partitioning could be distinguished, with the apparent initiation of the filling of storage roots (AISS) being the crucial point. A constant proportion of the dry matter formed is distributed to the storage roots: this is the efficiency of storage root production (ESRP). Genetic differences were found for ESRP and AISS.The influence of daylength on growth and yield was studied. Daylength was increased by light bulbs, while the other growth conditions remained similar. Daylength had only a very slight influence on AISS value. ESRP was negatively influenced by long days. Differences in ESRP were the main cause of differences in yield of storage roots for plants grown at different daylengths. For MCol 22, the ESRP value was also considerably lower under long-day conditions, but the yield of storage roots was nevertheless only slightly reduced, because of the higher total dry matter yield. MCol 22 is the first detected cassava clone whose yield of storage roots is nearly dayneutral and thus it is suitable for cultivation at higher latitudes. Long-day conditions caused a large increase in LAI. The higher LAI values were caused by a higher leaf formation rate per apex and a larger number of apices per m 2. Photosynthetic efficiency was not influenced by daylength.The implications of the findings are discussed. Plant properties that could be useful for improving storage root yield are: a high ESRP value, a low AISS value, a high growth vigour (short period until 50% light interception), a light interception of about 90% as long as possible, and a good sink potential.Present knowledge of cassava cultivation techniques is such that high yields are possible. Potential yield of storage roots is about 30 t.ha -1.year -1on dry weight basis and about 90 t.ha -1.year -1on fresh weight basis. The highest recorded yield of fresh storage roots at the CIAT experimental farm is of that order (namely 82 t.ha -1), and was achieved after a growth period of one year
06171 Executive Summary – Content-Based Retrieval
No full textThe emphasis of the fourth seminar in the Dagstuhl Seminar series on "Content-Based Retrieval" lies on the PERCEPTUAL and
COGNITIVE aspects of all kinds of content-based retrieval. Fundamental questions such
as the role of perception and cognition in feature extraction, pattern similarity rating,
indexing large collections etc. play an important role
06171 Abstracts Collection – Content-Based Retrieval
No full textFrom 23.04.06 to 28.04.06, the Dagstuhl Seminar 06171 `Content-Based Retrieval''
was held in the International Conference and Research Center (IBFI),
Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available
Properties and Performances of Shape Similarity Measures
No full textThis paper gives an overview of shape dissimilarity measure properties, such as metric and robustness properties, and of retrieval performance measures.
Fifteen shape similarity measures are shortly described and compared.
Since an objective comparison of their qualities seems to be impossible, experimental comparison is needed.
The Motion Picture Expert Group (MPEG), a working group of ISO/IEC has defined the MPGE-7 standard for description and search of audio and visual content.
A region based and a contour based shape similarity method are part of the standard.
The data set created by the MPEG-7 committee for evaluation of shape similarity measures offers an excellent possibility for objective experimental comparison of the existing approaches evaluated based on the retrieval rate.
Their retrieval results on the MPEG-7 Core Experiment Core Experiment Shape-1 test set as reported in the literature and obtained by a reimplementation are compared and discussed.
To compare the performance of similarity measures, we built the framework SIDESTEP – Shape-based Image Delivery Statistics Evaluation Project, http://give-lab.cs.uu.nl/sidestep/
Eurographics Workshop on 3D Object Retrieval - Short Papers: Frontmatter
No full textEurographics Workshop on 3D Object Retrieva
sj-pdf-1-crd-10.1177_14799731211031935 – Supplemental Material for Patient reported side-effects of prednisone and methotrexate in a real-world sarcoidosis population
No full textSupplemental Material, sj-pdf-1-crd-10.1177_14799731211031935 for Patient reported side-effects of prednisone and methotrexate in a real-world sarcoidosis population by Vivienne Kahlmann, Catharina C Moor, Marcel Veltkamp and Marlies S Wijsenbeek in Chronic Respiratory Disease</p
Supplemental material for Rationale and design of the Registry of Acute Stroke Under Novel Oral Anticoagulants-prime (RASUNOA-prime)
No full textSupplemental Material for Rationale and design of the Registry of Acute Stroke Under Novel Oral Anticoagulants-prime (RASUNOA-prime) by Kirsten Haas, Jan C Purrucker, Timolaos Rizos, Peter U Heuschmann and Roland Veltkamp in European Stroke Journal</p
FIG. 3 in Di€erentiation of Gyrodactylus bullatarudis Turnbull, 1956 and G. rasini Lucky, 1973 (Monogenea) with reassignment of Gyrodactylus bullatarudis Turnbull, 1956 sensu Harris (1986) to G. rasini
No full textFIG. 3. Schematic representations of the large cirrus spines of: (A) G. rasini from Xiphophoru s hybrids; and (B) that of G. bullatarudis from P. reticulata. The three-dimensional curvature of these structures is not shown. The main di€erence between the two species is that each side of the base of the large cirrus spine of G. bullatarudis appears to join to form a ring whereas those of the large spine of G. rasini diverge and do not appear to join.Published as part of Richards, G. R., Veltkamp, C. J. & Chubb, J. C., 2000, Di€erentiation of Gyrodactylus bullatarudis Turnbull, 1956 and G. rasini Lucky, 1973 (Monogenea) with reassignment of Gyrodactylus bullatarudis Turnbull, 1956 sensu Harris (1986) to G. rasini, pp. 341-353 in Journal of Natural History 34 (3) on page 347, DOI: 10.1080/002229300299525, http://zenodo.org/record/527951
Design Considerations for Building a Scalable Digital Version of a Multi-player Educational Board Game for a MOOC in Logistics and Transportation
No full textWith more flexible and large-scale learning environments, new design requirements for games emerge. Massive Open Online Courses (MOOCs) are one of the most important innovations in the learning field. Still, it is a challenge to motivate learners and to keep them motivated in such huge learning environments. To address this challenge, we redesigned a board game targeting at an integrated view on disruption and communication management in an intermodal transportation situation. From the redesign, we have learned that an online game works better with fewer roles, requires immediate feedback, and an engaging way of challenge to keep players motivated. Our findings can inform the design of games for large groups of players in an online environment.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Policy AnalysisOrganisation & Governanc
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
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