Phytophthora cinnamomi root rot of grapevines in South Africa

Thesis (PhD)--Stellenbosch University, 1983.ENGLISH ABSTRACT: No abstract availableAFRIKAANSE OPSOMMING: Geen opsomming beskikbaa

Rekall : un environnement open-source pour documenter, analyser les processus de création et simplifier la reprise des œuvres scéniques

International audienceLes Digital performances, dont le développement commence dans les années 1960, comprennent de nombreuses œuvres musicales ou du moins une composante sonore importante. Du fait de l’obsolescence rapide des technologies, les Digital performances, sont non seulement éphémères comme toute œuvre scénique mais engendrent également des traces de plus en plus éphémères. Il devient ainsi très difficile non seulement de documenter les œuvres et leurs processus de création, mais également de les reprendre, voire de les insérer dans un répertoire. Dans le domaine des digital performances, le modèle de la partition musicale, ou celui d’un système de notation, qui a été avancé par plusieurs chercheurs, est loin de résoudre les problèmes de documentation nécessaires à la reprise des œuvres. Par ailleurs, plusieurs initiatives ont été menées pour documenter très précisément une œuvre sans développer pour autant de proposition générale qui pourrait s’appliquer à un ensemble d’œuvres, voire aux arts de la scène de manière générale. Plutôt que de développer un système de notation, nous proposons de développer un outil d’annotation qui puisse être utilisé dans un très grand nombre de cas, qu’il s’agisse de chorégraphie, de théâtre ou de musique. Rekall est un environnement open source pour documenter, analyser les processus de création et faciliter la reprise des œuvres scéniques. C’est un logiciel qui permet de documenter les digital performances, en prenant en compte le processus de création, la réception et les différentes formes d’un spectacle. Il s’adresse à la fois aux artistes, aux techniciens, aux chercheurs et au grand public. Rekall est une réponse aux problématiques de documentation et de conservation des arts à composante technologique, ainsi qu’aux difficultés rencontrées par les artistes lors de la reprise d’un spectacle dont les technologies sont devenues obsolètes, tout en étant au plus près de la démarche propre à chaque artiste, à chaque compagnie. Il permet à la fois de rendre compte des technologies utilisées dans le spectacle et d’en offrir une description pour éventuellement proposer une alternative avec d’autres composantes. Le fonctionnement de Rekall s’articule essentiellement autour des documents de création et propose une préservation active des digital performances

Subcellular localization and trafficking of phytolongins (non-SNARE longins) in the plant secretory pathway

SNARE proteins are central elements of the machinery involved in membrane fusion of eukaryotic cells. In animals and plants, SNAREs have diversified to sustain a variety of specific functions. In animals, R-SNARE proteins called brevins have diversified; in contrast, in plants, the R-SNARE proteins named longins have diversified. Recently, a new subfamily of four longins named 'phytolongins' (Phyl) was discovered. One intriguing aspect of Phyl proteins is the lack of the typical SNARE motif, which is replaced by another domain termed the 'Phyl domain'. Phytolongins have a rather ubiquitous tissue expression in Arabidopsis but still await intracellular characterization. In this study, we found that the four phytolongins are distributed along the secretory pathway. While Phyl2.1 and Phyl2.2 are strictly located at the endoplasmic reticulum network, Phyl1.2 associates with the Golgi bodies, and Phyl1.1 locates mainly at the plasma membrane and partially in the Golgi bodies and post-Golgi compartments. Our results show that export of Phyl1.1 from the endoplasmic reticulum depends on the GTPase Sar1, the Sar1 guanine nucleotide exchange factor Sec12, and the SNAREs Sec22 and Memb11. In addition, we have identified the Y48F49 motif as being critical for the exit of Phyl1.1 from the endoplasmic reticulum. Our results provide the first characterization of the subcellular localization of the phytolongins, and we discuss their potential role in regulating the secretory pathway.</p

Impact of water and thermal induced crystallizations in a PC/MXD6 multilayer film on barrier properties

A multilayer film composed of alternating layers of polycarbonate (PC) and poly(m-xylene adipamide) (MXD6) was elaborated by using an innovative multilayer coextrusion process. Quasi-continuous thin MXD6 layers (nanolayers) alternating with PC layers were successfully obtained. The PC/MXD6 multilayer film showed a confining effect of MXD6 exerted by PC layers leading to an improvement of barrier properties despite a low degree of crystallinity (X c < 10 wt%). In order to further improve the barrier performances, crystallization treatments induced by water and by heating were then applied on the multilayer film and allowed reaching around 30 wt% of crystallinity in MXD6 layers. To decouple crystallization and geometrical constraint effects on the barrier properties in the multilayer films, the two treatments were also applied on MXD6 films. Surprisingly, despite an increase of the degree of crystallinity from 6 to 26%, water crystallization did not permit to improve gas barrier performances of the MXD6 film nor into the PC/MXD6 multilayer film. On the other hand, thermal crystallization of MXD6 in the multilayer film seems to be a more efficient route to strongly decrease the gas and moisture permeability, up to 75% for nitrogen, 58% for oxygen, 84% for carbon dioxide and 43% for water

Structural and Barrier Properties of Compatibilized PE/PA6 Multinanolayer Films

The barrier performance and structural lightening of organic materials are increasingly desired and constitute a major challenge for manufacturers, particularly for transport and packaging. A promising technique which tends to emerge in recent years is that of multinanolayer coextrusion. The advantage is that it can produce multilayers made of thousands of very thin layers, leading to new properties due to crystalline morphology changes induced by confinement. This paper is focusing on the study of multinanolayered films with alternated polyethylene (PE), compatibilizer (PEgMA) and polyamide 6 (PA6) layers and made by a forced assembly coextrusion process equipped with layer multiplying elements (LME). PE/PA6 multilayer films consisting of 5 to 2049 layers (respectively 0 to 9 LME) were successfully obtained with well-organized multilayered structure. The evolution of the morphology and the microstructure of these two semi-crystalline polymers, when the thickness of each polymer layer decreases from micro-scale to nano-scale, was correlated to the water and gas transport properties of the PE/PA multilayers. The expected improvement of barrier properties was limited due to the on-edge orientation of crystals in very thin PE and PA6 layers. Despite this change of crystalline morphology, a slight improvement of the gas barrier properties was shown by comparing experimental results with permeabilities predicted on the basis of a serial model developed by considering a PE/PA6 interphase. This interphase observed by TEM images and the on-edge crystal orientation in multilayers were evidenced from mechanical properties showing an increase of the stiffness and the strength

GENOMEPOP: A program to simulate genomes in populations

<p>Abstract</p> <p>Background</p> <p>There are several situations in population biology research where simulating DNA sequences is useful. Simulation of biological populations under different evolutionary genetic models can be undertaken using backward or forward strategies. Backward simulations, also called coalescent-based simulations, are computationally efficient. The reason is that they are based on the history of lineages with surviving offspring in the current population. On the contrary, forward simulations are less efficient because the entire population is simulated from past to present. However, the coalescent framework imposes some limitations that forward simulation does not. Hence, there is an increasing interest in forward population genetic simulation and efficient new tools have been developed recently. Software tools that allow efficient simulation of large DNA fragments under complex evolutionary models will be very helpful when trying to better understand the trace left on the DNA by the different interacting evolutionary forces. Here I will introduce GenomePop, a forward simulation program that fulfills the above requirements. The use of the program is demonstrated by studying the impact of intracodon recombination on global and site-specific <it>dN/dS </it>estimation.</p> <p>Results</p> <p>I have developed algorithms and written software to efficiently simulate, forward in time, different Markovian nucleotide or codon models of DNA mutation. Such models can be combined with recombination, at inter and intra codon levels, fitness-based selection and complex demographic scenarios.</p> <p>Conclusion</p> <p>GenomePop has many interesting characteristics for simulating SNPs or DNA sequences under complex evolutionary and demographic models. These features make it unique with respect to other simulation tools. Namely, the possibility of forward simulation under General Time Reversible (GTR) mutation or GTR×MG94 codon models with intra-codon recombination, arbitrary, user-defined, migration patterns, diploid or haploid models, constant or variable population sizes, etc. It also allows simulation of fitness-based selection under different distributions of mutational effects. Under the 2-allele model it allows the simulation of recombination hot-spots, the definition of different frequencies in different populations, etc. GenomePop can also manage large DNA fragments. In addition, it has a scaling option to save computation time when simulating large sequences and population sizes under complex demographic and evolutionary situations. These and many other features are detailed in its web page <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>.</p

The Genome of Borrelia recurrentis, the Agent of Deadly Louse-Borne Relapsing Fever, Is a Degraded Subset of Tick-Borne Borrelia duttonii

In an effort to understand how a tick-borne pathogen adapts to the body louse, we sequenced and compared the genomes of the recurrent fever agents Borrelia recurrentis and B. duttonii. The 1,242,163–1,574,910-bp fragmented genomes of B. recurrentis and B. duttonii contain a unique 23-kb linear plasmid. This linear plasmid exhibits a large polyT track within the promoter region of an intact variable large protein gene and a telomere resolvase that is unique to Borrelia. The genome content is characterized by several repeat families, including antigenic lipoproteins. B. recurrentis exhibited a 20.4% genome size reduction and appeared to be a strain of B. duttonii, with a decaying genome, possibly due to the accumulation of genomic errors induced by the loss of recA and mutS. Accompanying this were increases in the number of impaired genes and a reduction in coding capacity, including surface-exposed lipoproteins and putative virulence factors. Analysis of the reconstructed ancestral sequence compared to B. duttonii and B. recurrentis was consistent with the accelerated evolution observed in B. recurrentis. Vector specialization of louse-borne pathogens responsible for major epidemics was associated with rapid genome reduction. The correlation between gene loss and increased virulence of B. recurrentis parallels that of Rickettsia prowazekii, with both species being genomic subsets of less-virulent strains

Phytophthora cinnamomi root rot of grapevines in South Africa

Thesis (PhD)--Stellenbosch University, 1983.ENGLISH ABSTRACT: No abstract availableAFRIKAANSE OPSOMMING: Geen opsomming beskikbaa

Thermodynamics and kinetics of sorption

Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008.Please refer to full text to view abstract

M.E.R. se beskouing van die Afrikaner en afrikanernasionalisme vergeleke met die beskouinge van N.P. van Wyk Louw, J.J. Degenaar en J.C. Steyn

Die hooffiguur is mev. Maria Elizabeth Rothmann (1875 1975), in die Afrikaanse letterkunde alombekend as M.E.R. Die sleutelbegrippe is Afrikaner en Afrikanernasionalisme. Oor die betekenis van die benaming Afrikaner is daar meningsverskil, maar hier beteken Afrikaner 'n blanke Afrikaanssprekende. Afrikanernasionalisme is oor die afgelope eeu deur leiers soos Kruger, Steyn, Reitz, De la Rey, De Wet, Hertzog, Malan, Strydom en Verwoerd uitgespel. Die tweede hoofstuk bevat 'n aantal verteenwoordigende skrywers en politici se beskouinge oor die Afrikaner en Afrikanernasionalisme. In die derde hoofstuk word M.E.R. se beskouinge in die verband behandel en vergelyk met die menings van Van Wyk Louw, 'n geslag na haar, en J.C. Steyn, 'n geslag na Louw. Degenaar, gebore twee dekades na Louw en 13 jaar voor Steyn, word vernaamlik as klankbord betrek omdat sy siening radikaal verskil van M.E.R., Louw en Steyn s 'n, hoewel Louw na die begin van die jare sestig veel meer "liberaal" geword het. Voorts word M.E.R. se eerstehandse vertellings oor Kruger, Steyn, Hertzog en Verwoerd aan die aanvaarde kenmerke van goeie biografie gemeet. Waar moontlik word haar siening met die drietal vergelyk. 'n Volgende hoofstuk gaan oor M. E. R. se taksering van en deernis vir brandarm Afrikaners, soos vervat in Deel V B van die Carnegie Verslag. Haar verklaring van die oorsake van Afrikanerarmoede word uitgespel. Ook haar betrokkenheid by die Afrikanerkind deur haar talryke kinderboeke word toegelig. Dan volg 'n hoofstuk oor M.E.R. se siening van die Afrikaner se godsdiens. die beurt, waarop M.E.R. se My beskeie Voorts kom volkereverhoudings aan deel as outobiografie van 'n Afrikanervrou bespreek word. Die laaste twee hoof stukke gaan oor die viertal se taal en styl, en~as leermeesters van die Afrikanervolk. Ten slotte word die vier se beskouinge saamgevat. M.E.R. en Steyn glo aan die selfbeskikkingsreg van die Afrikaner. Sedert die begin van die jare sestig het Louw beweer dat die Kaapse bruinmense deel van die Afrikanervolk uitmaak, maar dat daar gebiedskeiding met die swart volke moet wees. Degenaar bepleit 'n unitere staat met die nodige verskansings van regionalisme, 'n handves van menseregte en 'n onafhanklike regbank.Pride of place belongs to Mrs Maria Elizabeth Rothmann (1875 - 1975), in Afrikaans literature widely known as M.·E.R. The key conceptions are Afrikaner and Afrikanernationalism. Theye are differing opinions about the meaning of the name Afrikaner, but for our purpose it means an Afrikaans speaking white. Afrikaner nationalism has been defined over the past century by leaders like Kruger, Steyn, Reitz, De la Rey, De Wet, Hertzog, Malan, Strydom and Verwoerd. The second chapter portrays the views of some representative authors and politicians on the Afrikaner and Afrikaner nationalism. In the next chapter M.E.R.'s opinion in this regard is discussed and compared and contrasted with the opinions of Louw, a generation after her, and J.C. Steyn, a generation after Louw. Degenaar, born two decades after Louw and thirteen years before Steyn, is used mainly as resonator because his views differ radically from the other three. although Louw turned more "liberal" since the early sixties. Forthwith M. E .R. 's first-hand narratives about Kruger, Steyn, Hertzog and Verwoerd are tested by the accepted standards of good biQJZraphy. Where L.o.tw) Sbe-1vi ....a ~~tLLy. possible her views are compared with those of the trio,.., The next chapter treats M.E.R. 's estimate of and compassion with desperately poor Afrikaners, as portrayed in her Chapter V B of the Carnegie Commission Report. Her indication of the causes of Afrikaner poverty is noted. Her concern with Afrikaner children by way of her many children's books occupies a subsequent chapter. Then follow her views on the Afrikaner's religion and on racial relations, whereafter her My beskeie deel (My allotted portion) is assessed as the autobiography of an Afrikaner woman. The last two chapters discuss the language and style of the four writers concerned as well as their role as teachers of the Afrikaner nation. In conclusion their views are summarised. M.E.R. and Steyn believe in the Afrikaner's right of self-determination. Since the early sixties Louw has regarded the Cape Coloureds as part of the Af rikanervolk, al though he has advocated territorial separation of the Black peoples. Degenaar is in favour of a unitary state entrenched by regionalism, a human rights charter and an independent judiciary.Afrikaans and Theory of LiteratureD. Litt. et Phil. (Afrikaans