248 research outputs found
Disentangling hexaploid genetics : towards DNA-informed breeding for postharvest performance in chrysanthemum
No full textDNA-informed selection can strongly improve the process of plant breeding. It requires the detection of DNA polymorphisms, calculation of genetic linkage, access to reliable phenotypes and methods to detect genetic loci associated with phenotypic traits of interest. Cultivated chrysanthemum is an outcrossing hexaploid with an unknown mode of inheritance. This complicates the development of resources and methods that enable the detection of trait loci. Postharvest performance is an essential trait in chrysanthemum, but is difficult to measure. This makes it an interesting but challenging trait to phenotype and detect associated genetic loci. In this thesis I describe the development of resources and methods to enable phenotyping for postharvest performance, genetic linkage map construction and detection of quantitative trait loci in hexaploid chrysanthemum. Postharvest performance is a complicated trait because it is related to many different disorders that reduce quality. One of these disorders in chrysanthemum is disk floret degreening, which occurs after long storage. In chapter 2, we show that degreening can be prevented by feeding the flower heads with sucrose, suggesting carbohydrate starvation plays a role in the degreening process. To investigate the response to carbohydrate starvation of genotypes with different sensitivity to disk floret degreening, we investigated the metabolome of sugar-fed and carbohydrate-starved disk florets by 1H-NMR and HPAEC. We show that the metabolome is severely altered at carbohydrate starvation. In general, starvation results in an upregulation of amino acid and secondary metabolism. Underlying causes of genotypic differences explaining variation in disk floret degreening in the three investigated genotypes remained to be elucidated, but roles of regulation of respiration rate and camphor metabolism were posed as possible candidates. In chapter 3, disk floret degreening was found to be the most important postharvest disorder after 3 weeks of storage among 44 white chrysanthemum cultivars. To investigate the inheritance of disk floret degreening, we crossed two genotypes with opposite phenotypic values of both disk floret degreening and carbohydrate content to obtain a population segregating for disk floret degreening. To phenotype the cultivar panel and the bi-parental population precisely and in a high throughput manner, we developed a method that quantified colour of detached capitula over time. This method was validated with visual observations of disk floret degreening during vase life tests. In a subset of the bi-parental population we measured carbohydrate content of the disk florets at harvest. The amount of total carbohydrates co-segregated with sensitivity to degreening, which shows that the difference in disk floret degreening sensitivity between the parents could be explained by their difference in carbohydrate content. However, the correlation was rather weak, indicating carbohydrate content is not the only factor playing a role. In order to develop resources for DNA-informed breeding, one needs to be able to characterize DNA polymorphisms. In chapter 4, we describe the development of a genotyping array containing 183,000 single nucleotide polymorphisms (SNPs). These SNPs were acquired by sequencing the transcriptome of 13 chrysanthemum cultivars. By comparing the genomic dosage based on the SNP assay and the dosage as estimated by the read depth from the transcriptome sequencing data, we show that alleles are expressed conform the genomic dosage, which contradicts to what is often found in disomic polyploids. In line with this finding, we conclusively show that cultivated chrysanthemum exhibits genome-wide hexasomic inheritance, based on the segregation ratios of large numbers of different types of markers in two different populations. Tools for genetic analysis in diploids are widely available, but these have limited use for polyploids. In chapter 5, we present a modular software package that enables genetic linkage map construction in tetraploids and hexaploids. Because of the modularity, functionality for other ploidy levels can be easily added. The software is written in the programming language R and we named it polymapR. It can generate genetic linkage maps from marker dosage scores in an F1 population, while taking the following steps: data inspection and filtering, linkage analysis, linkage group assignment and marker ordering. It is the first software package that can handle polysomic hexaploid and partial polysomic tetraploid data, and has advantages over other polyploid mapping software because of its scalability and cross-platform applicability. With the marker dosage scores of the bi-parental F1 population from the genotyping array and the developed methods to perform linkage analysis we constructed an integrated genetic linkage map for the hexaploid bi-parental population described in chapter 3 and 4. We describe this process in chapter 6. With this integrated linkage map, we reconstructed the inheritance of parental haplotypes for each individual, and expressed this as identity-by-descent (IBD) probabilities. The phenotypic data on disk floret degreening sensitivity that was acquired as described in chapter 3, was used in addition to three other traits to detect quantitative trait loci (QTL). These QTL were detected based on the IBD probabilities of 1 centiMorgan intervals of each parental homologue. This enabled us to study genetic architecture by estimating the effects of each separate allele within a QTL on the trait. We showed that for many QTL the trait was affected by more than two alleles. In chapter 7, the findings in this thesis are discussed in the context of breeding for heterogeneous traits, the implications of the mode of inheritance for breeding and the advantages and disadvantages of polyploidy in crop breeding. In conclusion, this thesis provides in general a significant step for DNA-informed breeding in polysomic hexaploids, and for postharvest performance in chrysanthemum in particular
Architectuur op de Fair: De rol van architectonische stijl op de Chicago World Fair, 1893
No full textEen onderzoek naar de politieke, maatschappelijke en stilistische rol van architectonische stijl op de wereldtentoonstelling in Chicago in 1893. Dit onderzoek gaat specifiek in op de keuze voor de neoclassicistische stijl voor de White City en de gevolgen die dit op de architectuurgeschiedenis van de Verenigde Staten heeft gehad.AR2A011Architecture, Urbanism and Building Science
Suggesting outsider status by behaving improperly: the linguistic realization of a populist rhetorical strategy in Dutch Parliament
No full textOne of the rhetorical strategies employed by populist politicians to create and maintain an anti-elitistprofile, is the use of ‘bad manners’. By violating decency standards that politicians are supposed toobserve in political debates, populists create the image of being different from the ‘political elite’. Asyet, however, little research has been carried out focusing on the question of exactly how populistsviolate the decency standards of a specific political debating culture verbally.This chapter aims to fill this gap, by focusing on improper behaviour in Dutch parliamentary debates.We will discuss how the Dutch populist politician Geert Wilders violates four decency standards forDutch parliamentary debate to create and maintain the image of a political outsider, and show howhe systematically uses a variety of conspicuous as well as inconspicuous linguistic choices to fulfil thisrhetorical strategy.Language Use in Past and Presen
Music for classical guitar by South African composers : a historical survey, notes on selected works and a general catalogue
No full textIncludes abstract.Includes bibliographical references (leaves 296-309).This is the first comprehensive investigation of music for, or including, the classical guitar by South African composers. The focus of this research has been, firstly, to uncover as much of the repertoire as possible, and, secondly, to collate, study, catalogue and report on the information. A brief historical survey of the guitar in South Africa provides the context within which this study was conducted. The primary sources of quantitative data collection were through the archival catalogues of the South African Music Rights Organisation and through personal contact with guitarists, composers and guitar teachers. Other sources consulted were publishers, broadcasting corporations, recording companies, libraries and the internet. The body of the dissertation comprises biographical sketches, background notes, analyses and technical notes on 17 selected solo and chamber works dating from 1947 to 2007 by some of South Africa's most prominent composers and guitaristcomposers. The repertoire ranges in style from the traditional and ethnically inspired to the experimental and abstract. As this is an empirical survey, each selected entry includes details on instrumentation, duration, level of difficulty, number of pages, scordatura, commissions or requests, sources or publishers, premières and recordings. A biography of each composer is provided as well as background notes which offer an overview of the selected work. The notes discuss historical, cultural, musical and extra-musical influences, and frequently include references to interview material. The commentaries on the selected works, with musical examples, include an analytical component describing structure, form, stylistic and compositional elements, while the technical observations include performance suggestions and a grading for each work
Spatial-temporal pathline clustering based on FTLE fields
No full textCardiac flow acquisition is a young and ongoing field of research which provides us with a vast amount of unsteady 3D blood flow data of the heart (4D vector fields). These 4D vector fields of the heart are used in clinical research to gain insight in the flow patterns within the heart which in turn can be used to gain a better understanding of the pathogenesis of cardiovascular diseases. The temporal, 3D dimensional nature and spatial freedom of the blood flow within the heart all add up to the complexity of the blood flow data which can be a challenge to interpret without a proper visualization. The biggest challenge would be the occlusion of relevant flow patterns due to visual clutter. This work describes a visualization technique called Spatial-temporal Clustering based on Finite Time Lyapunov Exponents, that aims to circumvent the challenges posed by the structural complexity of the flow and give a concise and insightful representation of the blood flow patterns within the heart. This technique uses pathlines to visualize the blood flow of which the placement is determined by a seeding strategy based on a clustering of a scalar metric extracted from the 4D vector fields. This scalar metric is the Finite Time Lyapunov Exponent that describes the temporal separation of pathlines. This results in seeding regions (clusters) that create pathline bundles that share the same temporal separation in time and thereby reduce the visual clutter. Aside from the main visualization technique this works also introduces a novel probing technique that highlights the base principles of the FTLE fields to provide the user with a better understanding of how a FTLE field works.Computer Science Media and Knowledge EngineeringComputer Graphics and VisualizationElectrical Engineering, Mathematics and Computer Scienc
Verhoging van de pensioenleeftijd dupeert vele mensen
No full textVerhoging van de leeftijd voor AOW en pensioen tot boven 65, ja zelfs tot 70 jaar, wordt de laatste tijd veelvuldig bepleit, zeer
recent door de commissie Nijpels “Grijs Werkt”. Want zo stelt men, de levensduur is langer geworden en de ouderen zijn
gezonder. Er wordt een beeld opgeroepen over 65 plussers, dat florissant is , met name van de jongsten in die categorie, de
mensen tussen 65 en 70 jaar. Nijpels spreekt zoals vele andere voor hem over het Zwitserlevengevoel. Ook wetenschappers
laten zich door dit florissante beeld inspireren. Zij adviseren om bij die mensen geld weg te halen of hun arbeidskracht te
benutten, met name om de kosten van de vergrijzing te financieren. Niet alleen de commissie Nijpels heeft gepleit om de
AOW-leeftijd in stappen omhoog te brengen, maar ook vele anderen. Begin januari stelde een topambtenaar van
Economische Zaken hetzelfde voor, evenals de OESO. Al eerder lieten de Raad van Economisch Adviseurs, de econoom
Bovenberg in de NRC en Wellink, de president van de Nederlandse Bank zich in deze geest uit . Het lijkt een eenstemmig koor
van adviseurs. Men verwijst daarbij naar Duitsland als voorbeeld. In dat land wordt die verhoging geleidelijk ingevoerd, met de
kanttekening dat de vergrijzing daar sterker is
De tunnel onder de Oude Maas tussen Dordrecht en Zwijndrecht
No full textOntwerp en bouw van de (zeer brede) afgezonken Drechttunnel bij Dordrecht
Analysis of current distribution and circulating currents in a permanent magnet synchronous machine with parallel coils
No full textIn this thesis the current distribution among parallel coils and the presence of circulating currents in an electric machine is investigated. Differences in induced voltage and in impedance between the parallel coils might lead to an uneven current distribution, which may cause the temperature of a single turn to become too high. To determine the flow of current in the machine it is necessary to model the machine in sufficient detail. For this research the coils in the machine have been modelled as a series connection of a voltage source, and inductance (with mutual coupling to other coils) and a resistance. This was made possible by the machine designer, who provided these parameters for every copper turn in the machine. The most important result of this research is that the difference in amplitude of the currents through parallel wires is very small, for this specific machine. The phase difference between the currents is larger, but the impact of this is still insignificant. Furthermore, the investigation on circulating currents has shown that the magnitude of these currents mainly depends on the difference in induced voltage between parallel wires and the resistance of the wires. The inductance of the coils was found to have negligible influence on the magnitude due to very good magnetic coupling between the parallel coils.Electrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc
Die posisie van swart skrywers van Afrikaanse prosa in die Afrikaanse prosasisteem sedert 1992
No full textThesis (DLitt)--University of Pretoria, 2016.In die studie word ? sisteembeskrywing van swart Afrikaanse prosaskrywers se posisie binne die Afrikaanse prosasisteem gegee, met die publikasie van Abraham Phillips se Die verdwaalde land in 1992 as begindatum. Die kontensieuse begrip swart word generies gebruik om alle skrywers van kleur in te sluit.
Swart skrywers se posisie is deur gebruikmaking van metatekste literêr-sistemies beskryf. Even-Zohar, Bourdieu, De Geest en Schmidt se sisteemteorieë is hiervoor aangewend.
Op grond van die aantal studies oor hul werk is Abraham Phillips, A.H.M. Scholtz en E.K.M. Dido as prominente skrywers hanteer. Ander minder prominente skrywers se posisies word ook beskryf.
Die studie het ? aantal bevindinge opgelewer.
Phillips is ? bekroonde skrywer wat uit ? benadeelde posisie prosatekste skryf. Sy posisie word binne die raamwerk van Bourdieu se veldteorie aangetoon. Literêre kritici het sy tekste op verskillende wyses in die literêre veld geposisioneer. Slegs Phillips se debuut word as gekanoniseerd beskou. In 1992 word hy die eerste swart skrywer van Afrikaanse prosa aan wie beduidende simboliese kapitaal toegeken is.
Scholtz, ? bekroonde skrywer, se drie tekste is met gebruikmaking van Even-Zohar se polisisteemteorie beskryf. Op grond van analises van metatekste word hy as gekanoniseerde skrywer in die Afrikaanse literêre sisteem gereken.
Dido se diskursiewe posisies in die literêre sisteem is binne De Geest se funksionele sisteemteorie beskryf. Sy het tot dusver geen literêre toekenning ontvang nie, maar is in 2005 met ? eredoktorsgraad deur UWK vereer. Sy word as baanbreker vir swart Afrikaanse vroueskrywers binne die literêre sisteem geposisioneer.
Karel Benjamin, S.P. Benjamin, Clive Smith, Joseph Marble, Elias P. Nel, Kirby van der Merwe, P.J. Philander, Catherine Willemse, Bettina Wyngaard, Anastasia de Vries en Zain Eckleton word as minder prominente skrywers beskou en hul posisisionering geskied binne Schmidt se operasionele raamwerk.
Die gevolgtrekking was dat swart skrywers van Afrikaanse prosa sedert 1992 verskillende posisies in die Afrikaanse literêre sisteem inneem.A systems description was given of the position of black African prose authors within the Afrikaans prose system with the publication of Abraham Phillips' Die verdwaalde land in 1992 as starting date. Despite being contentious the generic term "black" is used to include all authors of colour. The position of black authors is literary-systematically described by using meta-texts and by implementing the systems theories of Even-Zohar, Bourdieu, De Geest and Schmidt.
Based on the number of studies on their work, Abraham Phillips, AHM Scholtz and EKM Dido are considered to be "prominent" authors. The position of other less "prominent" authors are also described.
The study yielded a number of findings.
Phillips, an award-winning author, writes his texts from a disadvantaged position. His position in the Afrikaans literary field is described according to Bourdieu's field theory. Literary critics positioned Phillips s texts in different ways in the literary field. Only Phillips' debut can be considered part of the literary canon. In 1992 he became the first black author of Afrikaans prose to be awarded symbolic capital.
The acclaimed Scholtz s position is described according to Even-Zohar's Polysystems Theory. Based on the analysis of meta-texts he is considered as a canonical author in the Afrikaans literary system.
Dido s discursive positions in the literary system are described according to De Geest s Functional Systems Theory. Dido has not yet received any literary awards, but was awarded an honorary UWC doctorate in 2005. She is positioned in the Afrikaans literary system as a pioneer for "black" African women authors.
Karel Benjamin, SP Benjamin, Clive Smith, Joseph Marble, Elias P. Nel, Kirby van der Merwe, PJ Philander, Catherine Willemse, Bettina Wyngaard, Anastasia de Vries and Zain Eckleton are considered to be less prominent authors and their positioning is shown according to Schmidt's operational framework.
The study concludes that black Afrikaans prose authors since 1992 can be ranked in different positions in the Afrikaans literary system.AfrikaansDLittUnrestricte
The infancy of Edward Shelonga: an extended case from the Zambian Nkoya
No full textThe case history is based on the health experiences of a boy in the first years of his life. The author aims to shed some light on one of the crucial medical problems of the Third World: the interplay between cosmopolitan (i.e. western, modern) medicine, and such other forms of medicine as exist locally. He argues that the health behaviour of the people involved in the case are rational and understandable. In a postscript (pp. 87-90) he explains his position on the role of cognition more fully.ASC – Publicaties niet-programma gebonde
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