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Search Results: 1 - 10 of 19305 matches for " Richard Winkel "
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Rush to Judgment
Richard Winkel
PLOS Medicine , 2006, DOI: 10.1371/journal.pmed.0030071
Abstract:
Analysis of T-DNA alleles of flavonoid biosynthesis genes in Arabidopsis ecotype Columbia
Peter A Bowerman, Melissa V Ramirez, Michelle B Price, Richard F Helm, Brenda SJ Winkel
BMC Research Notes , 2012, DOI: 10.1186/1756-0500-5-485
Abstract: The confirmed knockout lines present easily-scorable phenotypes due to altered pigmentation of the seed coat (or testa). Knockouts for seven alleles for six flavonoid biosynthetic genes were confirmed by PCR and characterized by UPLC for altered flavonol content.Seven mutant lines for six genes of the central flavonoid pathway were characterized in ecotype, Columbia. These lines represent a useful resource for integrating biochemical and physiological studies with genomic, transcriptomic, and proteomic data, much of which has been, and continues to be, generated in the Columbia background.Flavonoids are a group of specialized plant metabolites that play critical roles in plant reproduction, defense from abiotic and biotic stress and are of growing interest as health-promoting compounds in human and animal diets [1-3]. As pigments, they have also figured into numerous seminal biological discoveries including Mendel’s elucidation of the laws of genetics, McClintock’s discovery of mobile genetic elements, and more recently the phenomenon of cosuppression, or RNA interference, in Petunia hybrida (reviewed in [4,5]). The flavonoid pathway continues to serve as an important experimental system in a variety of plant species, with studies ranging from understanding complex transcriptional control to biochemical structure-function relationships, intra- and intercellular transport, and the subcellular organization of pathways as multi-enzyme complexes [6-9]. Still, many questions remain about the specific biological targets of flavonoids in plants and animals [1,10], while engineering the production of specific flavonoids in plants and microorganisms is still far from straight-forward [11,12].Mutations within genes in the flavonoid biosynthetic pathway of Arabidopsis were described as early as 1971, easily identified by the transparent testa (tt) phenotype of the mutant seed coat [13] (Figure?1 and Table?1). Large-scale mutant screens carried out by Maarten Koornneef, initial
Trauer als Biografiegenerator Mourning as Biography Generator El duelo como generador de biografía
Heidemarie Winkel
Forum : Qualitative Social Research , 2008,
Abstract: Der Tod eines Alter Ego erweist sich für Trauernde als gravierende Kontingenzerfahrung. Sie vermag das individuelle Selbstverst ndnis in umfassender Weise zu erschüttern, wobei sich Trauer als Schmerz von unvergleichlicher Intensit t und Tiefe konstituiert. Die emotionale Erfahrung wird hierbei – nach Ma gabe psychologischer und therapeutischer Vorstellungen – zum Ausgangspunkt und zum Ma stab individueller Selbstvergewisserung. Diese Auffassung von Trauer korrespondiert mit einer allgemeinen, im Kontext moderner Gesellschaften entstandenen Zuschreibung von Emotionalit t zur Ebene des inneren Erlebens: Ich bin, was meine Gefühle mir sagen. Dass es gelingen kann, Trauer als pers nlichen Schmerz zu thematisieren und zum Ausgangspunkt individueller Selbstthematisierung zu machen, setzt systemtheoretisch gesehen semantische Strukturen zur Kommunizierung von individuellem Leid voraus. Im Rahmen einer auf biografischen Interviews basierenden Studie hat sich die symbolische Codierung von Trauer als individuell einzigartige Erfahrung von Schmerz und Leid erwiesen. Unabh ngig von kommunikativen Zurechnungen sozialer Systeme k nnen, so zeigt das Material weiterhin, verschiedenste lebensgeschichtliche Brüche und Diskontinuit tserfahrungen thematisiert werden. Trauer er ffnet aber nicht nur punktuell eine Selbstthematisierung: Die zentrale These lautet, dass Trauer als Biografiegenerator fungiert, indem sie eine systematische und umfassende Rekonstruktion der Lebensgeschichte unter den Aspekten von Leid und Schmerz erlaubt. URN: urn:nbn:de:0114-fqs0801501 For bereaved persons, an alter ego's death proves to be a serious experience of contingency. It can unsettle the individual's conception of the self, whereby mourning emerges as grief of a unique intensity and depth. The development of the emotional experience becomes a starting point and measure for the individual's re-conceptualization of the self in terms of psychological and therapeutic images. The notion of mourning as personal grief corresponds to a general, typically modern attribution of emotionality within the realm of inner experience and inwardness, i.e., I am what my feelings are expressing. From a general systems approach, talking about mourning as private and individual grief requires social communication standards. Within a research based on biographical interviews mourning proved to be a symbolic communication code for the expression of a unique and individual experience of sorrow, despair and bewilderment. Furthermore the results revealed that the distinctiveness of different biographical discontin
Construire son identité européenne grace à l’Autre : le cas des légendes urbaines
Aurore Van de Winkel
Synergies Canada , 2011,
Abstract: Dans la société européenne actuelle, les individus ont tendance à effectuer un repli identitaire sur l’un de leurs groupes d’appartenance. Chacun d’entre eux veut devenir autonome par rapport aux autres et en même temps, s’homogénéiser. C’est seulement en refusant de s’identifier à un “Autre”, à l’étranger, que ce “nous” pourra se construire en une entité auto-suffisante. Par leur narration, les légendes urbaines permettent, aux Européens, la réaffirmation de leurs normes et de leurs valeurs, et ainsi la clarification de l’une de leurs identités. L’analyse sémio-pragmatique de centaines de légendes nous a permis de montrer les intentions, les représentations, la relation et les r les de leurs diffuseurs européens. Ces récits mettent tous en scène la confrontation de deux protagonistes et ses conséquences: l’un représentant la communauté des sujets-transmetteurs, l’autre une entité opposée jugée négative . Cette opposition permet d’associer certains individus à des actes ou des événements renvoyant à la peur, l’interdit, le mystère et l’espoir. Même si l’approche interactionnelle nous a montré que les situations de construction ou d’affirmation d’une identité sont plus complexes et ne peuvent se résumer en une stricte et permanente opposition entre deux groupes, le contenu des légendes urbaines européennes se construit sur une simplification de la réalité qui facilite la représentation du monde et de soi. Comme cette désignation de l’Autre n’est pas reliée à des faits mais à des croyances et des stéréotypes, cet Autre devient un bouc-émissaire qui permet par opposition de savoir comment les Européens s’identifient aujourd’hui.
I. Gallin, Rechtsetzung ist Machtsetzung. Die deutsche Rechtsetzung in den Niederlanden 1940-1945
L.C. Winkel
BMGN : Low Countries Historical Review , 2001,
Abstract:
Hereditary tree growth and Levy forests
Thomas Duquesne,Matthias Winkel
Mathematics , 2012,
Abstract: We introduce the notion of a hereditary property for rooted real trees and we also consider reduction of trees by a given hereditary property. Leaf-length erasure, also called trimming, is included as a special case of hereditary reduction. We only consider the metric structure of trees, and our framework is the space $\bT$ of pointed isometry classes of locally compact rooted real trees equipped with the Gromov-Hausdorff distance. Some of the main results of the paper are a general tightness criterion in $\bT$ and limit theorems for growing families of trees. We apply these results to Galton-Watson trees with exponentially distributed edge lengths. This class is preserved by hereditary reduction. Then we consider families of such Galton-Watson trees that are consistent under hereditary reduction and that we call growth processes. We prove that the associated families of offspring distributions are completely characterised by the branching mechanism of a continuous-state branching process. We also prove that such growth processes converge to Levy forests. As a by-product of this convergence, we obtain a characterisation of the laws of Levy forests in terms of leaf-length erasure and we obtain invariance principles for discrete Galton-Watson trees, including the super-critical cases.
Regenerative tree growth: Markovian embedding of fragmenters, bifurcators, and bead splitting processes
Jim Pitman,Matthias Winkel
Mathematics , 2013, DOI: 10.1214/14-AOP945
Abstract: Some, but not all processes of the form $M_t=\exp(-\xi_t)$ for a pure-jump subordinator $\xi$ with Laplace exponent $\Phi$ arise as residual mass processes of particle 1 (tagged particle) in Bertoin's partition-valued exchangeable fragmentation processes. We introduce the notion of a Markovian embedding of $M=(M_t,t\ge 0)$ in a fragmentation process, and we show that for each $\Phi$, there is a unique (in distribution) binary fragmentation process in which $M$ has a Markovian embedding. The identification of the Laplace exponent $\Phi^*$ of its tagged particle process $M^*$ gives rise to a symmetrisation operation $\Phi\mapsto\Phi^*$, which we investigate in a general study of pairs $(M,M^*)$ that coincide up to a random time and then evolve independently. We call $M$ a fragmenter and $(M,M^*)$ a bifurcator. For $\alpha>0$, we equip the interval $R_1=[0,\int_0^{\infty}M_t^{\alpha}\,dt]$ with a purely atomic probability measure $\mu_1$, which captures the jump sizes of $M$ suitably placed on $R_1$. We study binary tree growth processes that in the $n$th step sample an atom (``bead'') from $\mu _n$ and build $(R_{n+1},\mu_{n+1})$ by replacing the atom by a rescaled independent copy of $(R_1,\mu_1)$ that we tie to the position of the atom. We show that any such bead splitting process $((R_n,\mu_n),n\ge1)$ converges almost surely to an $\alpha$-self-similar continuum random tree of Haas and Miermont, in the Gromov-Hausdorff-Prohorov sense. This generalises Aldous's line-breaking construction of the Brownian continuum random tree.
Regenerative tree growth: Binary self-similar continuum random trees and Poisson--Dirichlet compositions
Jim Pitman,Matthias Winkel
Mathematics , 2008, DOI: 10.1214/08-AOP445
Abstract: We use a natural ordered extension of the Chinese Restaurant Process to grow a two-parameter family of binary self-similar continuum fragmentation trees. We provide an explicit embedding of Ford's sequence of alpha model trees in the continuum tree which we identified in a previous article as a distributional scaling limit of Ford's trees. In general, the Markov branching trees induced by the two-parameter growth rule are not sampling consistent, so the existence of compact limiting trees cannot be deduced from previous work on the sampling consistent case. We develop here a new approach to establish such limits, based on regenerative interval partitions and the urn-model description of sampling from Dirichlet random distributions.
Restricted exchangeable partitions and embedding of associated hierarchies in continuum random trees
Bo Chen,Matthias Winkel
Mathematics , 2009,
Abstract: We introduce the notion of a restricted exchangeable partition of $\mathbb{N}$. We obtain integral representations, consider associated fragmentations, embeddings into continuum random trees and convergence to such limit trees. In particular, we deduce from the general theory developed here a limit result conjectured previously for Ford's alpha model and its extension, the alpha-gamma model, where restricted exchangeability arises naturally.
Growth of Levy trees
Thomas Duquesne,Matthias Winkel
Mathematics , 2005,
Abstract: We construct random locally compact real trees called Levy trees that are the genealogical trees associated with continuous-state branching processes. More precisely, we define a growing family of discrete Galton-Watson trees with i.i.d. exponential branch lengths that is consistent under Bernoulli percolation on leaves; we define the Levy tree as the limit of this growing family with respect to the Gromov-Hausdorff topology on metric spaces. This elementary approach notably includes supercritical trees and does not make use of the height process introduced by Le Gall and Le Jan to code the genealogy of (sub)critical continuous-state branching processes. We construct the mass measure of Levy trees and we give a decomposition along the ancestral subtree of a Poisson sampling directed by the mass measure.
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