Preliminary X-ray diffraction analysis of YcdB from Escherichia coli: a novel haem-containing and Tat-secreted periplasmic protein with a potential role in iron transport

YcdB is a periplasmic haem-containing protein from Escherichia coli that has a potential role in iron transport. It is currently the only reported haem-containing Tat-secreted substrate. Here, the overexpression, purification, crystallization and structure determination at 2.0 angstrom resolution are reported for the apo form of the protein. The apo-YcdB structure resembles those of members of the haem-dependent peroxidase family and thus confirms that YcdB is also a member of this family. Haem-soaking experiments with preformed apo-YcdB crystals have been optimized to successfully generate haem-containing YcdB crystals that diffract to 2.9 angstrom. Completion of model building and structure refinement are under way.

Modèle d'état à coefficient aléatoire: filtrage par densités approchées

Le filtrage de Bucy-Kalman s'applique au modèle d'état comprenant des équations linéaires bruitées, décrivant l'évolution de l'état et des équations linéaires bruitées d'observation . Ce filtrage consiste dans le cas gaussien, à calculer de façon récursive, la loi de probabilité, a posteriori, de l'état, au vu de l' observation actuelle et des observations passées . Le filtrage par densités approchées permet de traiter des équations d'état, non linéaires ou à bruits non Gaussiens. Pour un coefficient de rappel aléatoire, cas typique d'une situation de changements de modèles, l'article introduit une famille de lois de probabilité, paramétrées, bimodales servant, par ajustement des paramètres, à approcher les lois a posteriori de l'état aux divers instants . Les paramètres sont recalculés récursivement, lors des mises à jour et des prédictions.

Conscience, discretion and the creation of property rights

This paper considers the utility of the concept of conscience or unconscionable conduct as a contemporary rationale for intervention in two principles applied where a person seeks to renege on an informal agreement relating to land: the principle in Rochefoucauld v Boustead; and transfers 'subject to' rights in favour of a claimant. By analysing the concept in light of our current understanding of the nature of judicial discretion and the use of general principles, it responds to arguments that unconscionability is too general a concept on which to base intervention. In doing so, it considers the nature of the discretion that is actually in issue when the court intervenes through conscience in these principles. However, the paper questions the use of constructive trusts as a response to unconscionability. It argues that there is a need, in limited circumstances, to separate the finding of unconscionability from the imposition of a constructive trust. In these limited circumstances, once unconscionability is found, the courts should have a discretion as to the remedy, modelled on that developed in the context of proprietary estoppel. The message underlying this paper is that many of the concerns expressed about unconscionability that have led to suggestions of alternative rationales for intervention can in fact be addressed whilst retaining an unconscionability analysis. Unconscionability remains a preferable rationale for intervention as it provides a common thread that links apparently separate principles and can assist our understanding of their scope.

Poetry of social conscience, poetry of transition: Ann Hawkshaw's 'Introductory Stanzas' and 'The Mother to her Starving Child'

Through close readings of Ann Hawkshaw's poetry in the context of industrial Manchester in the 1840s, this article highlights the interaction of form and content in poetry that makes use of the idea of the past to question or complicate the politics of the present.