On the tradeoff between almost sure error tolerance versus mean deviation frequency in martingale convergence

In this article we quantify almost sure martingale convergence theorems in terms of the tradeoff between asymptotic almost sure rates of convergence (error tolerance) and the respective modulus of convergence. For this purpose we generalize an elementary quantitative version of the first Borel-Cantelli lemma on the statistics of the deviation frequencies (error incidence), which was recently established by the authors. First we study martingale convergence in $L^2$, and in the settings of the Azuma-Hoeffding inequality. In a second step we study the strong law of large numbers for martingale differences in two settings: uniformly bounded increments in $L^p$, $p\geq 2$, using the respective Baum-Katz-Stoica theorems, and uniformly bounded exponential moments with the help of the martingale estimates by Lesigne and Voln\'y. We also present applications for the tradeoff for the multicolor generalized P\'olya urn process, the Generalized Chinese restaurant process, statistical M-estimators, as well as the a.s. excursion frequencies of the Galton-Watson branching process. Finally, we relate the tradeoff concept to the convergence in the Ky Fan metric.Comment: Our findings are generalized to the modulus of convergenc

Conception et évaluation d'une technique d'interaction pour la sélection d'un volume dans un nuage de point 3D

International audienceA fundamental task needed when using a 3D virtual environment is the ability to select. This is necessary to perform local treatments, such as translating an object. While classical techniques, such as ray-casting, works well for large objects it becomes more difficult when the need for precision is greater and almost impossible for a point selection. To select a set of points in a point cloud we created a novel selection technique. It allows to select complex shapes while remaining simple to use. Using our technique relies on three principles: 1) selecting points consists in progressively elaborating a cylinder-like shape (the worm) through the sequential definition of several sections ; 2) a section is defined between two contours linked together with straight lines; 3) each contour is a freely drawn closed line. A user study reveals that our technique is significantly faster than a classical selection mechanism based on predefined volumes such as spheres or cuboids while maintaining a comparable level of precision and recall .Une tâche fondamentale d'interaction dans un environne-ment 3D est la possibilité de réaliser une sélection. Elle est nécessaire pour appliquer des traitements locaux, comme le déplacement d'un objet. Bien que pour les objets larges les techniques classiques fonctionnent bien, comme le lancer de rayon, elles deviennent moins adaptées quand le besoin en précision augmente. Elles sont même impossibles à utiliser pour sélectionner des ensembles de points. Pour ces ensembles de points, nous proposons une nouvelle technique de sélection. Elle permet de sélectionner des formes complexes tout en restant simple d'utilisation. Elle repose sur trois principes : 1) la sélection de points consiste à progressivement élaborer une forme rappelant vaguement un cylindre à travers la définition itérative de sections ; 2) une section est définie par deux contours liés ensemble par des lignes droites ; 3) chaque contour est un tracé fermé dessiné librement. Les résultats d'une évaluation utilisateur établissent que notre technique est significativement plus rapide que les techniques plus classiques basées sur des volumes prédéfinis, comme des sphères ou des cuboïdes, tout en gardant un niveau de précision et de rappel comparable

Novel drug targets in cell wall biosynthesis exploited by gene disruption in Pseudomonas aeruginosa

© 2017 Elamin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For clinicians, Pseudomonas aeruginosa is a nightmare pathogen that is one of the top three causes of opportunistic human infections. Therapy of P. aeruginosa infections is complicated due to its natural high intrinsic resistance to antibiotics. Active efflux and decreased uptake of drugs due to cell wall/membrane permeability appear to be important issues in the acquired antibiotic tolerance mechanisms. Bacterial cell wall biosynthesis enzymes have been shown to be essential for pathogenicity of Gram-negative bacteria. However, the role of these targets in virulence has not been identified in P. aeruginosa. Here, we report knockout (k.o) mutants of six cell wall biosynthesis targets (murA, PA4450; murD, PA4414; murF, PA4416; ppiB, PA1793; rmlA, PA5163; waaA, PA4988) in P. aeruginosa PAO1, and characterized these in order to find out whether these genes and their products contribute to pathogenicity and virulence of P. aeruginosa. Except waaA k.o, deletion of cell wall biosynthesis targets significantly reduced growth rate in minimal medium compared to the parent strain. The k.o mutants showed exciting changes in cell morphology and colonial architectures. Remarkably, ΔmurF cells became grossly enlarged. Moreover, the mutants were also attenuated in vivo in a mouse infection model except ΔmurF and ΔwaaA and proved to be more sensitive to macrophage-mediated killing than the wild-type strain. Interestingly, the deletion of the murA gene resulted in loss of virulence activity in mice, and the virulence was restored in a plant model by unknown mechanism. This study demonstrates that cell wall targets contribute significantly to intracellular survival, in vivo growth, and pathogenesis of P. aeruginosa. In conclusion, these findings establish a link between cell wall targets and virulence of P. aeruginosa and thus may lead to development of novel drugs for the treatment of P. aeruginosa infection

Outline Pursuits:Gaze-assisted Selection of Occluded Objects in Virtual Reality

In 3D environments, objects can be difficult to select when they overlap, as this affects available target area and increases selection ambiguity. We introduce Outline Pursuits which extends a primary pointing modality for gaze-assisted selection of occluded objects. Candidate targets within a pointing cone are presented with an outline that is traversed by a moving stimulus. This affords completion of the selection by gaze attention to the intended target's outline motion, detected by matching the user's smooth pursuit eye movement. We demonstrate two techniques implemented based on the concept, one with a controller as the primary pointer, and one in which Outline Pursuits are combined with head pointing for hands-free selection. Compared with conventional raycasting, the techniques require less movement for selection as users do not need to reposition themselves for a better line of sight, and selection time and accuracy are less affected when targets become highly occluded

Novel drug targets in cell wall biosynthesis exploited by gene disruption in Pseudomonas aeruginosa

This study demonstrates that cell wall targets contribute significantly to intracellular survival, in vivo growth, and pathogenesis of P. aeruginosa. In conclusion, these findings establish a link between cell wall targets and virulence of P. aeruginosa and thus may lead to development of novel drugs for the treatment of P. aeruginosa infection

Phylogenetic placement of environmental sequences using taxonomically reliable databases helps to rigorously assess dinophyte biodiversity in Bavarian lakes (Germany).

1. Reliable determination of organisms is a prerequisite to explore their spatial and temporal occurrence and to study their evolution, ecology, and dispersal. In Europe, Bavaria (Germany) provides an excellent study system for research on the origin and diversification of freshwater organisms including dinophytes, due to the presence of extensive lake districts and ice age river valleys. Bavarian freshwater environments are ecologically diverse and range from deep nutrient‐poor mountain lakes to shallow nutrient‐rich lakes and ponds. 2. We obtained amplicon sequence data (V4 region of small subunit‐rRNA, c. 410 bp long) from environmental samples collected at 11 sites in Upper Bavaria. We found 186 operational taxonomic units (OTUs) associated with Dinophyceae that were further classified by means of a phylogenetic placement approach. 3. The maximum likelihood tree inferred from a well‐curated reference alignment comprised a systematically representative set of 251 dinophytes, covering the currently known molecular diversity and OTUs linked to type material if possible. Environmental OTUs were scattered across the reference tree, but accumulated mostly in freshwater lineages, with 79% of OTUs placed in either Apocalathium, Ceratium, or Peridinium, the most frequently encountered taxa in Bavaria based on morphology. 4. Twenty‐one Bavarian OTUs showed identical sequences to already known and vouchered accessions, two of which are linked to type material, namely Palatinus apiculatus and Theleodinium calcisporum. Particularly within Peridiniaceae, delimitation of Peridinium species was based on the intraspecific sequence variation. 5. Our approach indicates that high‐throughput sequencing of environmental samples is effective for reliable determination of dinophyte species in Bavarian lakes. We further discuss the importance of well‐curated reference databases that remain to be developed in the future