Rozprawy doktorskie na temat „Leaves”

Master of Arts
Department of Modern Languages
Robert L. Clark
Medieval French literature provides the modern researcher with references to the healing arts in many passages that are incorporated into prose or poetic works. Because there was no clear separation of the genres into modern classifications, references to treatment of sicknesses of body, mind or spirit are woven into many literary works, providing us with a kind of snapshot of the state of the art healing practices of the day. Texts make reference to herbs and plants used to cure the ailments of the body, gardens and flowers that refresh the spirit, miraculous unguents, cures through the intercession of the saints and the Virgin Mary and surgical procedures. Texts examined here include Le Roman de la Rose, Erec et Enide, Aucassin et Nicolette, Les Lais of Marie de France, Le conte du Graal, Le chevalier de la charrette, La Condamnation de Banquet, Yvain, Cligès, La Chanson de Roland and Treize Miracles de Notre-Dame. The picture they provide of the medicine of the time has a certain charm and quaintness that many moderns seek in holistic treatments of today which hearken back to this more rustic medicine.

Maggie Benedict was born in Pretoria and attended Pretoria Tech where she studied music, dance and theatre. During her theatre stint, Maggie performed at the Civic Theatre in Showboat and Goldilocks and the Three Bears. Maggie also works as an ambassador with the Walt Disney Company. Some of her television tributes include appearances on "Snitch, Justice For All 3" and "7de Laan". She was also a presenter on the daytime show Lifestyle. She also currently plays the role of Zoey Matsekwa in the M-Net soapie Binneland Sub Judice (formerly known as Binnelanders), since April 2010.

”No one leaves behind” är en uppsats som diskuterar vilka berättarstrukturer och ideologier som kan urskiljas i de amerikanska krigsfilmerna Behind Enemy Lines (2001), Black Hawk Down (2001), We Were Soldiers (2001) och Saving Private Ryan (1998), med hjälp av teoretiska metoder från strukturalismen och teoretikern John Fiske. Dessutom behandlas även begreppet nationell identitet för att undersöka om man kan se någon tendens till nationella identiteter i de amerikanska krigsfilmerna.

Slutsatsen är att filmerna har en gemensam berättarstruktur och gemensamma teman som är viktiga för de ideologiska tankar och värderingar som kan urskiljas i filmerna. Teman såsom ära, mod och heder, det manliga förhållandet som i uppsatsen benämns brödraskap, och dessutom temat No one leaves behind vilket är mycket centralt i en del av filmerna. Ingen av soldaterna i filmerna skall lämnas kvar i en krigszon, levande eller död.

The author presents the first detailed review of the pharmacological therapy of parkinsonism from ancient times until the near present (1980). It is not clear whether parkinsonism as it is now defined – a progressive neurodegenerative disorder of the basal ganglia characterized by sharply reduced striatal dopamine levels, particularly in the striatum – has always affected a significant minority of aged persons, but suggestive evidence to this effect in the older literature is reviewed. The major discussion commences, however, with the administration of various plant alkaloids to parkinsonian patients in the second half of the 19th century. Antiparkinsonian therapy since this time may be divided into a number of phases: 1. The employment of alkaloids derived from solanaceous plants: initially hyoscyamine, then hyoscine/scopolamine and atropine. The discovery and characterization of these alkaloids, and the gradual recognition that other pharmacologically useful solanaceous alkaloids (such as duboisine) were identical with one or other of these three compounds, is discussed. 2. With the outbreak of encephalitis lethargica following the First World War, parkinsonian patient numbers increased dramatically, leading to a multiplicity of new directions, including the use of another solanaceous plant, stramonium, of extremely high atropine doses, and of harmala alkaloids. 3. The so-called “Bulgarian treatment” was popularized in western Europe in the mid-1930s. It was also a belladonna alkaloid-based therapy, but associated with greater efficacy and fewer side effects. This approach, whether as actual plant extracts or as defined combinations of belladonna alkaloids, remained internationally dominant until the end of the 1940s. 4. Synthetic antiparkinsonian agents were examined following the Second World War, with the aim of overcoming the deficiencies of belladonna alkaloid therapy. These agents fell into two major classes: synthetic anticholinergic (= antimuscarinic) agents, such as benzhexol, and antihistaminergic drugs, including diphenhydramine. These agents were regarded as more effective than plant-based remedies, but certainly not as cures for the disease. 5. A complete change in direction was heralded by the discovery in 1960 of the striatal dopamine deficit in parkinsonism. This led to the introduction of L-DOPA therapy for parkinsonism, the first approach directed against an identified physiological abnormality in the disorder. 6. Subsequent developments have thus far concentrated on refinement or supplementation of the L-DOPA effect. Recent attempts to develop neuroprotective or -restorative approaches are also briefly discussed. The thesis also discusses the mechanisms by which the various types of antiparkinsonian agent achieved their effects, and also the problems confronting workers at various periods in the design and assessment of novel agents. The impact of attitudes regarding the etiology and nature of parkinsonism, particularly with regard to symptomatology, is also considered. Finally, the history of antiparkinsonian therapy is discussed in context of the general development of both clinical neurology and fundamental anatomical, physiological and biochemical research. In particular, the deepening understanding of the neurochemical basis of central nervous system function is emphasized, for which reason the history of dopamine research is discussed in some detail. This history of antiparkinsonian therapy also illustrates the fact that the nature of experimental clinical pharmacology has markedly changed throughout this period: No longer the preserve of individual physicians, it is now based firmly on fundamental laboratory research, the clinical relevance of which is not always immediately apparent, and which is only later examined in (large scale) clinical trials. It is concluded that antiparkinsonian therapy was never irrational or without basis, but has always been necessarily rooted in current knowledge regarding neural and muscular function. The achievements of L-DOPA therapy, the first successful pharmacological treatment for a neurodegenerative disorder, derived from the fruitful union of the skills and contributions of different types by laboratory scientists, pharmacologists and clinicians
Der Autor stellt die erste detaillierte Zusammenfassung der Entwicklung der pharmakologischen Therapie des Parkinsonismus vom Altertum bis in die jüngere Vergangenheit (1980) dar. Es ist nicht klar, ob der Parkinsonismus, wie er jetzt definiert wird – eine progressive neurodegenerative Störung der Basalganglien, die durch die zum scharf verringerten Dopamininhalt des Corpus striatum führende Degeneration der nigrostriatalen Bahn gekennzeichnet wird – zu allen Zeiten eine bedeutende Minderheit älterer Personen heimgesucht hat, verlockende Hinweise darauf findet man aber in der älteren Literatur. Die Hauptdiskussion beginnt jedoch mit der Anwendung verschiedener Pflanzenalkaloide bei Parkinson-Patienten in der zweiten Hälfte des 19. Jahrhunderts. Die Geschichte der Parkinson-Therapie seit dieser Zeit läßt sich in eine Serie von Phasen gliedern: 1. Die Anwendung von aus den Solanazeen isolierten Alkaloiden: zuerst Hyoscyamin, später Hyoscin/Skopolamin und Atropin. Die Entdeckung und die Charakterisierung dieser Alkaloide und die allmähliche Feststellung, daß andere pharmakologisch nützliche Solanazeen-Alkaloide (z.B. Duboisin) mit einem oder anderem dieser schon bekannten Mittel identisch waren, werden diskutiert. 2. Mit dem Ausbruch der Encephalitis lethargica nach dem Ersten Weltkrieg stieg die Anzahl von Parkinson-Patienten dramatisch an, was zu einer Vielfältigkeit neuer therapeutischer Richtungen führte: Der Einsatz des auch zu den Solanazeen gehörenden Stramonium, die Verabreichung von extrem hohen Atropindosen, und die Benutzung von Harmala-Alkaloiden waren insbesondere hochgeschätzt. 3. Die sogenannte “Bulgarische Kur” verbreitete sich schnell in Westeuropa in der Mitte der dreißiger Jahre. Es handelte sich dabei ebenfalls um eine auf Tollkirsche-Alkaloiden basierte Therapie, der jedoch höhere Wirksamkeit und wenige Nebenwirkungen zugemutet wurde. Diese Methode, vermittels der Verabreichung tatsächlicher Tollkirschenextrakte bzw. definierter Kombinationen von Belladonna-Alkaloiden, beherrschte die Parkinson-Therapie bis zum Ende der vierziger Jahre. 4. Nach dem Zweiten Weltkrieg wurden synthetische Parkinson-Mittel überprüft, in der Hoffnung, die Mängel der bisherigen anticholinergen Therapien überwinden zu können. Diese Mittel teilten sich in zwei Hauptkategorien ein: synthetische anticholinerge (= antimuskarine; z.B. Benzhexol) und antihistaminerge Mittel (z.B., Diphenhydramin). Diese Arzneimittel wurden als wirkungsvoller als pflanzliche Therapien angesehen, jedoch sicherlich nicht als Heilmittel für die Krankheit. 4. Eine gründliche Richtungsänderung der Parkinson-Therapie kündigte sich mit der Entdeckung (1960) des striatalen Dopamindefizits im Parkinsonismus an. Diese führte zur Einführung der L-DOPA-Therapie, der ersten Parkinson-Therapie, die gegen eine genau definierte physiologische Abnormität gerichtet war. 5. Die darauf folgenden Entwicklungen haben sich bis heute auf Verfeinerung bzw. Ergänzung des L-DOPA-Effektes konzentriert. Neuere Ansätze, neuroprotektive bzw. -restorative Therapien zu entwickeln, werden kurz behandelt. Die Arbeit diskutiert auch die Mechanismen, die der Wirksamkeit der verschiedenen Parkinson-Mittelarten zugrunde liegen, und auch die Probleme, die Forscher bei der Entwicklung und Bewertung neuartiger Mittel konfrontiert haben. Diese Diskussion zieht auch in Betracht die Auswirkung der Haltung des jeweiligen Forschers betreffend der Ätiologie und Natur des Parkinsonismus auf die Beurteilung neuer therapeutischer Möglichkeiten. Schließlich wird die Geschichte der Parkinson-Therapie im Kontext der allgemeinen Entwicklung der klinischen Neurologie als auch der grundlegenden anatomischen, physiologischen und biochemischen Forschung während dieser Periode behandelt. Insbesondere wird das wachsende Verständnis der neurochemischen Grundlagen der Funktion des Zentralnervensystems hervorgehoben, indem die Geschichte der Dopaminforschung ausführlich behandelt wird. Die Geschichte der Parkinson-Therapie weist auch darauf hin, daß sich die Natur der experimentellen Pharmakologie während dieser Periode grundsätzlich geändert hat. Sie liegt nämlich nicht mehr im Zuständigkeitsbereich des einzelnen Arztes, sondern wird im Gegenteil auf grundlegender Laborforschung aufgebaut, deren klinische Bedeutung nicht immer sofort deutlich ist. Erst später werden die Ergebnisse dieser Grundlagenforschung in großangelegten klinischen Versuchen bei Patienten überprüft. Es wird gefolgert, daß die Parkinson-Therapie zu keiner Zeit als ohne vernünftige Grundlage bzw. irrational betrachtet werden darf. Sie ist jedoch immer dem aktuellen Wissensstand betreffend neuraler und muskulöser Funktion entsprechend geregelt worden. Der Erfolg der L-DOPA-Therapie, der ersten langfristig wirksamen pharmakologischen Behandlung einer neurodegenerativen Krankheit, ist das Ergebnis der ertragreichen Vereinigung der Fähigkeiten und verschiedenartigen Beiträge von Grundlagenforschern, Pharmakologen und Klinikern

Changes in chlorophyll content, carotenoid content and composition, abscisic acid and phaseic acid levels, hydrolytic enzyme activity and polypeptide pattern were monitored during senescence of the primary attached leaves of Hordeum vulgare L. cv. Dyan. Senescence occurred due to the normal course of leaf development or was induced by incubation of leaves in darkness. Loss of chlorophyll and total leaf protein was retarded in light whereas it continued rapidly in leaves from dark-incubated seedlings. Chlorophyll alb ratio increased with the progression of senescence, suggesting that chlorophyll b was referentially degraded during this process. Loss of total protein coincided with enhanced activity of acid and neutral proteases. In contrast, loss of chlorophyll was not accompanied by an increase in· peroxidase activity, suggesting that this enzyme was not responsible for initiating chlorophyll breakdown. Carotenoid and abscisic acid levels were monitored in the same tissue extracts. The results obtained show that the increase in endogenous levels of abscisic acid, induced by senescence, correlated with enhanced epoxidation of the xanthophyll cycle, ie., increased conversion of zeaxanthin to antheraxanthin and all-trans-violaxanthin. In addition, an increase in abscisic acid levels occurred concomitant with a decrease in all-trans-violaxanthin and 9'-cis-neoxanthin, suggesting an apparent 1:1 relationship on a molar basis. It is therefore proposed that enhanced abscisic acid production, due to foliar senescence, arises from fluctuations in carotenoid turnover. Polypeptide patterns in isolated chloroplasts, purified thylakoid and stromal fractions were very similar for leaves incubated in either light or darkness. A decrease in intensity of bands was observed in isolated chloroplasts and stromal fractions. Intensity of bands in thylakoids remained unchanged with the progression of senescence. Protein standards of peroxidase and lipoxygenase co-migrated with proteins of the isolated chloroplast. Although tentative, some proteins of the chloroplast may be representative of precursors of hydrolytic enzymes which are known to increase during senescence.

Thesis (M.S.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains viii, 86 p. : ill. Vita. Includes abstract. Includes bibliographical references.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
Damos exemplos de variedades suaves abertas que não podem ser folhas de nenhuma folheação riemanniana, nem de qualquer folheação transver- salmente homotética, de variedade compacta. Também apresentamos uma nova classe de não folhas de folheação C0 de codimensão um de variedades compactas, as variedades não periódica em homotopia, usando grupos de homotopia de dimensão maior. Finalmente generalizamos ligeiramente os exemplos de não folhas de Ghys, Inaba et al. e Attie-Hurder, com uma demonstração baseada na recorrência de blocos na variedade.
We give examples of open smooth manifolds that cannot be leaves of any riemannian or transversely homothetic foliation of a compact manifold. We also present a new class of non-leaves of C0 codimension one foliations, manifolds that are non-periodic in homotopy, using higher-dimensional homotopy groups. Finally we give small generalizations of the non-leaf examples of Ghys, Inaba et al., and Attie-Hurder, with a proof based on the recurrence of blocks in the manifold.

How patterns arise from an apparently uniform group of cells is one of the classical problems in developmental biology. The mechanism is complicated by the fact that patterning occurs on a growing medium. Therefore, changes in an organism’s size and shape affect the patterning processes. In turn, patterning itself may affect growth. This interaction between growth and patterning leads to the generation of complex shapes and structures from simpler ones. Studying such interactions requires the possibility to monitor both processes in vivo. To this end, we developed a new technique to monitor and quantify vein patterning in a growing leaf over time using the leaves of Arabidopsis thaliana as a model system. We used a transgenic line with fluorescent markers associated with the venation. Individual leaves are followed in many samples in vivo through time-lapse imaging. Custom-made software allowed us to extract the leaf surface and vein pattern from images of each leaf at each time point. Then average spatial maps from multiple samples that were generated revealed spatio-temporal gradients. Our quantitative description of wild type vein patterns during leaf development revealed that there is no constant size at which a part of tissue enclosed by vasculature will become irrigated by a new vein. Instead, it seemed that vein formation depends on the growth rate of the tissue. This is the first time that vein patterning in growing leaves was quantified. The techniques developed will later be used to explore the interaction between growth and patterning through a variety of approaches, including mutant analysis, pharmacological treatments and variation of environmental conditions.

In this thesis, we investigate the question when a non-compact manifold can be quasi-isometric to a leaf in a foliation of a compact manifold. The point of departure is the result of Paul Schweitzer's that every non-compact manifold carries a Riemannian metric so that the resulting Riemannian manifold is not quasi-isometric to a leaf in a codimension one foliation of a compact manifold. We show that the coarse homology of these non-leaves is not finitely generated. This observation motivates the main question of this thesis: Does every leaf in a foliation of a compact manifold have finitely generated coarse homology? The answer to this question is a double negative: Firstly, we show that there exists a large class of two-dimensional leaves in codimension one foliations that have non-finitely generated coarse homology. Moreover, we improve Schweitzer's construction by showing that every Riemannian metric can be deformed to a codimension one non-leaf without affecting the coarse homology. In particular, we find non-leaves with trivial coarse homology. In order to answer these questions we develop computational tools for the coarse homology. Furthermore, we show that certain known criteria for manifolds to be a leaf are independent of one another and of the coarse homology.
In dieser Arbeit beschäftigen wir uns mit der Frage, wann eine nicht-kompakte Mannigfaltigkeit quasi-isometrisch zu einem Blatt in einer Blätterung einer kompakten Mannigfaltigkeit sein kann. Ausgangspunkt der Arbeit ist ein Resultat von Paul Schweitzer, nach dem jede nicht-kompakte Mannigfaltigkeit eine Riemannsche Metrik trägt, sodass die resultierende Riemannsche Mannigfaltigkeit nicht quasi-isometrisch zu einem Blatt einer Kodimension 1 Blätterung einer kompakten Mannigfaltigkeit ist. Wir zeigen, dass die Grobhomologie dieser Nicht-Blätter nicht endlich erzeugt ist. Aus dieser Beobachtung motiviert sich die in dieser Arbeit untersuchte Frage, ob alle Blätter in kompakten Mannigfaltigkeiten endlich erzeugte Grobhomologie haben. Wie sich herausstellt, ist sowohl dies als auch die Umkehrung im allgemeinen nicht wahr: Wir zeigen, dass es eine große Klasse zweidimensionaler Blätter in Kodimension 1 mit nicht endlich erzeugter Grobhomologie gibt. Ferner verbessern wir Schweitzers Konstruktion, indem wir zeigen, dass jede Riemannsche Metrik zu einem Kodimension 1 Nicht-Blatt deformiert werden kann, ohne die Grobhomologie dabei zu verändern. Insbesondere konstruieren wir Nicht-Blätter mit trivialer Grobhomologie. Zur Behandlung dieser Fragestellungen entwickeln wir Berechnungsmethoden für die Grobhomologie und zeigen ferner, dass verschiedene bekannte Kriterien für Mannigfaltigkeiten Blatt zu sein voneinander und von der Grobhomologie unabhängig sind.

Plant phenotyping refers to the measurement of plant visual traits. In the past, the collection of such traits has been done manually by plant scientists, which is a tedious, error-prone, and time-consuming task. For this reason, image-based plant phenotyping is used to facilitate the measurement of plant traits with algorithms. However, the lack of robust software to extract reliable phenotyping traits from plant images has created a bottleneck. Here, we will study the problem of estimating the total number of leaves in plant images. The leaf count is a sought-after plant trait, as it is related to the plant development stage, health, yield potential, and flowering time. Previously, leaf counting was determined using a per-leaf segmentation. The typical approaches for per-leaf segmentation are: (i) image processing to segment leaves, using assumptions and heuristics; or (ii) training a neural network. However, both approaches have drawbacks. Heuristics-based approaches use a set of rules based upon observations that can easily fail. Per-leaf segmentation via neural networks requires fine grained annotated datasets during training, which are hard to obtain. Alternatively, the estimation of the number of leaves in an image can be addressed as a direct regression problem. In this context, the learning of the algorithm is relaxed to the prediction of a single number (the leaf count) and the collection of labelled datasets is easy enough to be also performed by non-experts. This thesis discusses the first machine learning algorithm for leaf counting for top-view rosette plants. This approach extracted patches from the log-polar representation of the image, allowing us to cancel out leaf rotation. These patches were then used to learn a visual dictionary, which was used to encode the image into a holistic descriptor. As a next step, we developed a shallow neural network to extract rotation-invariant features. Using this architecture, we could learn features to explicitly account for the radial arrangement of leaves in rosette plants. Although the results were promising, the leaf counting with rotation-invariant features could not outperform the previous approach. For this reason, we moved our attention to deep neural networks. However, it is widely known that deep architectures are hungry of data. Therefore, we addressed the problem of how to collect more labelled plant image datasets, using three approaches: (i) we developed an annotation tool to help experts to annotate images; (ii) we uploaded images in a crowdsourcing online platform, allowing citizen scientists to annotate them; (iii) we used a generative deep neural network to synthesise the images of plants with the leaf count. Lastly, we will show how a deep leaf counting network can be trained with data from different sources and modalities, showing promising results and reducing the performance gap between algorithm and human annotators.

Esta tesis doctoral analiza la eficacia del sistema de licencias parentales en España para facilitar la conciliación de la vida laboral y familiar y promover la igualdad de género. Para ello, el primer artículo explora los factores individuales e institucionales que influyen en el uso y la duración de la excedencia por cuidado de hijos, haciendo especial hincapié en las características que justifican la implicación de los hombres. El segundo artículo profundiza en las diferencias del contexto regional español con el objetivo de evaluar el impacto de las políticas desarrolladas por cinco Comunidades Autónomas en la utilización de esta licencia. El tercer artículo estudia los determinantes de la transición laboral de las madres a una reducción de jornada tras el nacimiento del primer hijo, teniendo en cuenta el resto de alternativas laborales disponibles; la excedencia por cuidado de hijos, el trabajo a tiempo parcial y la inactividad o el desempleo.
This PhD dissertation analyzes the effectiveness of the parental leave system in Spain to facilitate the reconciliation of work and family life and to promote gender equality. Accordingly, the first article explores the individual and institutional factors that influence the use and duration of full-time parental leave, with special emphasis on the characteristics that influence male participation. The second article delves into differences at the regional level and evaluates the impact of policies developed by five Autonomous Communities on the utilization of full-time parental leave. Finally, the third article examines the determinants of mothers’ transitions from full-time employment to part-time parental leave following the birth of their first child, while accounting for all other alternatives: full-time parental leave, part-time work and inactivity or unemployment.

The anthocyanins, a relatively small group of pigments in the diverse flavonoid family, are largely responsible for the red-blue colouration in a large number plant species worldwide. Their occurrence in fruits and flowers seems to offer clear benefits in attracting pollinators and aiding seed dispersal, however their presence in the vacuoles of leaves remains obscure. The accumulation of anthocyanin pigments in leaves can be induced by a host of disparate environmental and anthropogenic stressors, such as UV-exposure, wounding, pathogen infection, high light, chilling, pollution, osmotic stress, and nutrient deficiency. Anthocyanins are in some species expressed throughout leaf development; in others the pigments are found exclusively in the young, rapidly expanding leaves, or at later stages of leaf senescence. Many researchers have explored the possible functional role(s) of anthocyanins within leaves, although none of the hypotheses provides a unified explanation for the diverse range of environmental triggers, or for the variability in the pigment’s location and expression at particular stages of development. Differences in the cellular location of cyanic pigments had little effect on the optical properties of leaves from several native New Zealand species. Instead, the absorptance of green-yellow light was strongly proportional to the concentration of anthocyanin. Red leaves absorbed up to 17 % more PAR (400-700 nm) than green leaves of same species. The reflectance of red light was independent of leaf anthocyanin content. In Lactuca sativa, the absorption of light by anthocyanic cell vacuoles in the upper epidermis led to a reduction in the light incident on subjacent chlorenchyma. Under high irradiances, the dissipation of excess energy through non-photochemical processes (qNP) was lower in the red regions of the leaves than in the green regions. Red L. sativa, maintained higher photochemical efficiencies (0PSII), and had greater rates of photochemical quenching (qP) than the green tissues. Moreover, the cyanic areas were photoinhibited significantly less (7 %), as measured by levels of maximum PSII efficiency (Fv/Fm), than green areas during a high light treatment of 1300 mmol m-2 s-1. Chloroplast suspensions from shade adapted L. sativa generated less superoxide (O2 -) through the Mehler reaction and had reduced rates of chlorophyll bleaching, when irradiated with 300 mmol m-2 s-1 of red light rather than white light. These data demonstrated the impact of the light-filtering effects of anthocyanins on the photophysiology of the leaves. Complementary to their light-shielding functions, anthocyanins also demonstrated potent antioxidant capabilities at pH values typical of both the cytoplasm and the vacuole. The addition of cyanidin-3-malonylglucoside, which was colourless at the cytoplasmic pH, to a chloroplast suspension receiving high irradiance resulted in the significant scavenging of O2 -. The red, flavylium form of anthocyanin was also oxidised by O2 -. After 15 minutes, this oxidation equated to a 40 % reduction in antioxidant potential of the anthocyanin, as measured by cyclic voltammetry. The data suggested that anthocyanins could provide widespread cellular protection to cellular membranes, organelles, and DNA. Analysis of the overall antioxidant defence in red and green leaves of Elatostema rugosum, a shade-adapted herb native to New Zealand, and Quintinia serrata, a native tree found on exposed ridges, provided evidence for a photoprotective role of anthocyanins. Red leaves of E. rugosum were on average five-times more effective at scavenging DPPH radicals than were green leaves. The anthocyanins constituted the most active phenolic component, providing a greater relative contribution to the antioxidant pool than the flavones, flavonols, and hydroxycinnamic acids. In contrast, red and green leaves of Q. serrata exhibited comparable ranges in antioxidant activities. The data suggest that for some species, anthocyanins can supplement the pool of low molecular weight antioxidants but are not a prerequisite for protection from oxidative stress. It is likely that the localised accumulation of anthocyanins in the leaves of Q. serrata serves to shield photosynthetic tissues that are the more susceptible to photodamage. In conclusion, the accumulation of anthocyanins represents a multifunctional mechanism to; i) directly reduce ROS through scavenging and possibly metal chelation, acting in conjunction with other antioxidants, and ii) to shield photosynthetic processes experiencing excessive irradiances, thereby reducing the extent of photooxidation, photoinhibition, and wasteful dissipatory systems. Such protection may be vital for leaves experiencing stressful environments.

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In this dissertation we will discuss Walt Whitman’s poetry in the aspects that articulate the lyric and the epic in an epilyric unity, taking the 1892 edition of Leaves of Grass as its study object. We shall ascertain the theoretical assumptions of modernity and modern poetry characteristics, which are crucial to the understanding of the poet’s aesthetic and ideological project, as delivered in his preface for the 1855 edition, as well as his importance to modernism in poetry in the following century. Subsequently, we shall examine carefully the subjectivity expressed in the book at issue, which is polymorphically shaped, as it’s showed by the categories proposed by Kinnaird (1962) and Bloom (2001). Finally, we shall find how Whitman used aspects of the epical literature to construct his oeuvre and carry out his design to become the national poet of the United States.
Nesta dissertação trataremos da poesia de Walt Whitman sob os aspectos que articulam o lírico e o épico numa unidade epilírica, tendo como objeto a obra Leaves of Grass em sua edição de 1892. Averiguaremos, ainda, os pressupostos teóricos da modernidade e as caracterizações da poesia moderna, fundamentais para a compreensão do projeto ideológico e estético do poeta, demonstrado em seu prefácio de 1855, bem como da sua importância para o próprio modernismo na poesia no século seguinte. Em seguida, nos aprofundaremos no estudo da subjetividade expressa na obra em questão, que se configura polimorficamente, como demonstram as categorias propostas por Kinnaird (1962) e Bloom (2001). Por fim, verificaremos como Whitman lançou mão de aspectos da literatura épica para construir sua obra e executar seu projeto de ser o poeta nacional estadunidense.

Mature field-grown apple trees were used to gain a better understanding of the influences of light and fruit on leaf physiology. Light effects on net photosynthesis (Pn), specific leaf weight (SLW), leaf N content (Weight/area) (Nw), and leaf N concentration (% dry weight) (Np) of spur leaves from two canopy locations were evaluated on four dates in 1987. Interior leaves had lower Pn, SLW, Nw, and Np than exterior leaves. In 1988 the influence of %available photosynthetic photon flux (PPF) on the same parameters was examined throughout the season. On most measurement dates both Pn and SLW increased quadratically while Nw increased linearly with increasing PPF. In both years positive linear relationships existed between Pn and Nw, SLW and Nw, and Pn and SLW.
Ph. D.

J’étudie la formation du système vasculaire des feuilles des plantes à l’aide de modèles mathématiques. L’hypothèse de canalisation d’une phytohormone, l’auxin, stipule que l’auto activation de son transport entre les cellules crée des chemins préférentiels qui se différencieront plus tard en système vasculaire. J’entreprends une analyse numérique de modèles de canalisation sur une grande matrice, et parviens à créer des motifs branchés dans lesquels circule l’auxin. Une analyse de stabilité d’un modèle simplifié nous éclaire sur les raisons de la formation de ces motifs et l’impossibilité de créer un réseau réticulé. La majorité des plantes ayant un système vasculaire réticulé, je modifie le modèle de façon à obtenir ce type de réseau. En ajoutant une variable biologiquement plausible, je parviens à créer un réseau réticulé dans lequel l’auxin circule uniformément. Enfin, je discute des relations entre la formation du système vasculaire et de la spirale de phyllotaxie.

Alluvium is an important archaeological and palaeoenvironmental resource in lowland Britain. The research presented here develops plant macrofossil analysis of alluvial facies, with special emphasis on the depositional and natural environments of the Lower Thames Basin. Plant macrofossil analysis is a poorly developed area of alluvial research, usually limited to superficial description of the fossils seen in section, or detailed analysis of a narrow suite of remains. A comprehensive, quantitative method of macrofossil analysis using counts and cover abundance scores is developed. Identification criteria for several groups of macrofossils are presented, including leaves, rootlets and epidermis. Potential macrofossil incorporation was investigated at eight wetland and alluvial sites, including saltmarsh, wet woodland and herb fen environments. Macrofossil collections were compared to extant vegetation and subject to multivariate analysis. The results showed that macrofossil assemblages produce spatially and temporally precise data of plant presences, although spatial and temporal fidelity varies in different depositional environments and between plant taxa. Vegetation dominants were favoured in the assemblages of all classes of macrofossils, with bulky Monocotyledons and Therophytes favourably preserved and sparsely distributed taxa, such as rosette plants, less well favoured. The depositional environment and position in relation to environmental gradients were also found to affect macrofossil composition. Multiple approaches to macrofossil analysis using a wide range of macrofossils were found to produce improved interpretations. The value of different macrofossil classes and occurrences of the major observed taxa in alluvial sediments are discussed. The method was applied to samples from the Medway River at Chatham. Vegetation history, hydrology and traces of human disturbance are discussed from 7000BP to 2000BP. Analysis showed a gradual increase in human disturbance over time, development of a distinctive human-influenced upper salt marsh flora from 3000BP and supports the trend across southern Britain for a change in hydrology by the same period.

The aim of this master thesis is to classify the tree class from an image of a leaf with a computer vision classiffication system. We compare different descriptors that will describe the leaves different features. We will also look at different classiffication models and combine them with the descriptors to build a system hat could classify the different tree classes.

The plant leaf is one of the most challenging natural objects to be realistically depicted by computer graphics due to its complex morphological and optical characteristics. Although many studies have been done on plant modeling, previous research on leaf modeling required for close-up realistic plant images is very rare. In this thesis, a novel method for modeling of the leaf shape based on the leaf venation is presented. As the first step of the method, the leaf domain is defined by the enclosure of the leaf boundary. Second, the leaf venation is interactively modeled as a hierarchical skeleton based on the actual leaf image. Third, the leaf domain is triangulated with the skeleton as constraints. The skeleton is articulated with nodes on the skeleton. Fourth, the skeleton is interactively transformed to a specific shape. A user can manipulate the skeleton using two methods which are complementary to each other: one controls individual joints on the skeleton while the other controls the skeleton through an intermediate spline curve. Finally, the leaf blade shape is deformed to conform to the skeleton by interpolation. An interactive modeler was developed to help a user to model a leaf shape interactively and several leaves were modeled by the interactive modeler. The ray-traced rendering images demonstrate that the proposed method is effective in the leaf shape modeling.

Various methods for the production of bioethanol using different feedstocks have been researched on. In most work on bioethanol synthesis from sugar cane, tops and leaves have been regarded as waste and generally removed and thrown away. In this work, lignocellulosic sugarcane leaves and tops were not discarded but instead used as biomass to evaluate their hydrolyzate content. The leaves and tops were hydrolysed using different methods, namely concentrated acid, dilute acid pre-treatment with subsequent enzyme hydrolysis and compared with a combination of oxidative alkali pretreatment and enzyme hydrolysis. Subsequent fermentation of the hydrolyzates into bioethanol was done using the yeast saccharomyces cerevisae. Acid hydrolysis has the problem of producing inhibitors, which have to be removed and this was done using overliming with calcium hydroxide and compared to sodium hydroxide neutralization. Oxidative alkali pre-treatment with enzyme hydrolysis gave the highest yields of fermentable sugars of 38% (g/g) using 7% (v/v) peroxide pre-treated biomass than 36% (g/g) for 5% (v/v) with the least inhibitors. Concentrated and dilute acid hydrolysis each gave yields of25% (g/g) and 22% (g/g) yields respectively although for acid a neutralization step was necessary and resulted in dilution. Alkaline neutralization of acid hydrolyzates using sodium hydroxide resulted in less dilution and loss of fermentable sugars as compared to overliming. Higher yields of bioethanol, 13.7 (g/l) were obtained from enzyme hydrolyzates than 6.9 (g/l) bioethanol from dilute acid hydrolyzates. There was more bioethanol yield 13.7 (g/l) after 72h of fermentation with the yeast than 7.0 (g/l) bioethanol after 24h. However, the longer fermentation period diminishes the value of the increase in yield by lowering the efficiency of the process.

Variation of phenylheptatriyne (PHT) concentrations in leaves of Bidens alba (Linn.) var. radiata (Schultz-Bip.) was investigated across it's Florida range, throughout the year and in response to photoenvironment. Natural surveys of PHT concentrations in B. alba leaves were done at 13 sites in Florida and three sites throughout the year. PHT concentrations were significantly different between populations (p<0.001) but showed little relationship with latitude (R2 =0.024) and none with longitude. Concentrations in leaves fluctuated throughout the year (p<0.001). They were highest in October, followed by June and lowest in January and April. Photoenvironmental influences were experimentally tested. PHT concentrations decreased under low R/FR treatments and increased under filtered UV treatments. Low light quantity did not significantly influence PHT concentrations but decreased PHT levels and leaf biomass. The results suggests that PHT concentrations in B. alba leaves vary in nature and that light quality, R/FR and UV, may effect PHT biosynthesis.