Nonlinear Attitude Filtering: A Comparison Study

This paper contains a concise comparison of a number of nonlinear attitude filtering methods that have attracted attention in the robotics and aviation literature. With the help of previously published surveys and comparison studies, the vast literature on the subject is narrowed down to a small pool of competitive attitude filters. Amongst these filters is a second-order optimal minimum-energy filter recently proposed by the authors. Easily comparable discretized unit quaternion implementations of the selected filters are provided. We conduct a simulation study and compare the transient behaviour and asymptotic convergence of these filters in two scenarios with different initialization and measurement errors inspired by applications in unmanned aerial robotics and space flight. The second-order optimal minimum-energy filter is shown to have the best performance of all filters, including the industry standard multiplicative extended Kalman filter (MEKF)

Discordance dans la concordance : ressacs de la traduction

Discordance dans la concordance : ressacs de la traduction — L'auteur décrit d'abord le dessein et les propriétés de la Konkordanz, monumental ouvrage de référence paru en 1996. Véritable événement éditorial dans le champ psychanalytique, cet ouvrage donne accès aux termes clés des Gesammelte Werke de Freud. L'auteur compare ensuite cette Konkordanz allemande et la Concordance anglaise, et relève des discordances révélatrices sur le plan lexicographique. Cette comparaison confirme la remarquable cohérence de la conceptualité freudienne, d'une part, et la nécessité d'entreprendre une « psychanalyse de la traduction de Strachey » d'autre part, car les processus de l'inconscient et du préconscient ne passent pas de la même manière d'une langue à l'autre. L'anglais doit-il rester la lingua franca de la psychanalyse?Discordance Between the Concordances : Translation on the Rebound — The author first describes the design and characteristics of the Konkordanz, a monumental work of reference published in 1996. Constituting nothing less than a majestic editorial event in the field of psychoanalysis, this work is useful as a location guide and frequency register of the key terms in the Gesammelte Werke of Freud. The author then compares this German Konkordanz and the English Concordance, and proceeds to highlight a certain number of revelatory discordances on the lexicographical level. This comparison confirms the remarkable coherence of Freud's conceptualization on one hand, and on the other hand underlines the necessity of undertaking "a psychoanalytic translation of Strachey," for the processes of the unconscious and preconscious are variously deflected in the passage from one language to another. Whence the urgent question : should English remain the lingua franca of psychoanalysis

Comment Freud nous parle-t-il?

Depuis plus d'une décennie j'explore certains aspects psychodynamiques de la pensée de Freud et de ses implications, qui tendent à être scotomisés par une institution psychanalytique à tendance idéologique. Idéalement, il devrait y avoir continuité entre la sphère de communication plus circonscrite de la psychanalyse clinique et celle, plus large, des collègues orientés vers la psychanalyse. Plus spécifiquement, un cadre historique allant de la Renaissance au XIXe siècle aide à faire ressortir le côté distinctif de ce genre de discours que Freud préférait utiliser. En particulier, il était de ceux qui stimulaient et facilitaient à la fois les processus associatifs et critiques de Freud quand il écrivait, aussi bien que des nôtres quand nous le lisons. Un tel discours ne fait pas que décrire, il met aussi en acte l'activité psychique aux niveaux conscient, préconscient et inconscient. Il y a, en dernier ressort, un esprit démocratique derrière ce discours, que j'ai appelé ailleurs la prose freudienne de solidarité, et alternativement, la politique freudienne de non-apartheid lexical.For well over a decade I have been exploring certain psychodynamic aspects of Freud's discourse and their implications, which tend to be scotomized by an ideologically-driven organizational psychoanalysis. Ideally there should be a continuity between the more circumscribed communicative scene of clinical psychoanalysis and the broader scene of communication with one's psychoanalyti-cally oriented colleagues. More specifically, a historical framework stretching from the Renaissance to the nineteenth century helps to highlight the distinctivness of that kind of discourse which Freud preferred to use. In particular, it was one which stimulated and facilitated both the associative and critical processes of Freud in the act of writing, and ours as well in the act of reading him. Such a discourse not only describes but also enacts psychic activity on the conscious, preconscious and unconscious levels. There is ultimately a democratic spirit in such expression, which I have pointedly called elsewhere Freud's prose of solidarity, and alternately, Freud's policy of a non-apartheid lexicality

Wigner-Moyal description of free variable mass Klein-Gordon fields

A system of coupled kinetic transport equations for the Wigner distributions of a free variable mass Klein-Gordon field is derived. This set of equations is formally equivalent to the full wave equation for electromagnetic waves in nonlinear dispersive media, thus allowing for the description of broadband radiation-matter interactions and the associated instabilities. The standard results for the classical wave action are recovered in the short wavelength limit of the generalized Wigner-Moyal formalism for the wave equation.Comment: 9 pages, accepted for publication in Journal of Mathematical Physic

Public crises, public futures

This article begins to map out a novel approach to analyzing contemporary contexts of public crisis, relationships between them and possibilities that these scenes hold out for politics. The article illustrates and analyses a small selection of examples of these kinds of contemporary scenes and calls for greater attention to be given to the conditions and consequences of different forms and practices of public and political mediation. In offering a three-fold typology to delineate differences between ‘abject’, ‘audience’ and ‘agentic’ publics the article begins to draw out how political and public futures may be seen as being bound up with how the potentialities, capacities and qualities that publics are imagined to have and resourced to perform. Public action and future publics are therefore analysed here in relation to different versions of contemporary crisis and the political concerns and publics these crises work to articulate, foreground and imaginatively and practically support

Endotoxin-free purification for the isolation of Bovine Viral Diarrhoea Virus E2 protein from insoluble inclusion body aggregates

Background: Protein expression in Escherichia coli may result in the recombinant protein being expressed as insoluble inclusion bodies. In addition, proteins purified from E. coli contain endotoxins which need to be removed for in vivo applications. The structural protein, E2, from Bovine Viral Diarrhoea Virus (BVDV) is a major immunogenic determinant, and is an ideal candidate as a subunit vaccine. The E2 protein contains 17 cysteine residues creating difficulties in E. coli expression. In this report we outline a procedure for successfully producing soluble and endotoxin-free BVDV E2 protein from inclusion bodies (IB).Results: The expression of a truncated form of BVDV-E2 protein (E2-T1) in E. coli resulted in predominantly aggregated insoluble IB. Solubilisation of E2-T1 with high purity and stability from IB aggregates was achieved using a strong reducing buffer containing 100 mM Dithiothreitol. Refolding by dialysis into 50 mM Tris (pH 7.0) containing 0.2% Igepal CA630 resulted in a soluble but aggregated protein solution. The novel application of a two-phase extraction of inclusion body preparations with Triton X-114 reduced endotoxin in solubilised E2-T1 to levels suitable for in vivo use without affecting protein yields. Dynamic light scattering analyses showed 37.5% of the protein was monomeric, the remaining comprised of soluble aggregates. Mice immunised with E2-T1 developed a high titre antibody response by ELISA. Western hybridisation analysis showed E2-T1 was recognised by sera from immunised mice and also by several BVDV-E2 polyclonal and monoclonal antibodies.Conclusion: We have developed a procedure using E. coli to produce soluble E2-T1 protein from IB, and due to their insoluble nature we utilised a novel approach using Triton X-114 to efficiently remove endotoxin. The resultant protein is immunogenic and detectable by BVDV-E2 specific antibodies indicating its usefulness for diagnostic applications and as a subunit vaccine. The optimised E. coli expression system for E2-T1 combined with methodologies for solubilisation, refolding and integrated endotoxin removal presented in this study should prove useful for other vaccine applications