A Protein Complex Containing the Conserved Swi2/Snf2-Related ATPase Swr1p Deposits Histone Variant H2A.Z into Euchromatin

The conserved histone variant H2A.Z functions in euchromatin to antagonize the spread of heterochromatin. The mechanism by which histone H2A is replaced by H2A.Z in the nucleosome is unknown. We identified a complex containing 13 different polypeptides associated with a soluble pool of H2A.Z in Saccharomyces cerevisiae. This complex was designated SWR1-Com in reference to the Swr1p subunit, a Swi2/Snf2-paralog. Swr1p and six other subunits were found only in SWR1-Com, whereas six other subunits were also found in the NuA4 histone acetyltransferase and/or the Ino80 chromatin remodeling complex. H2A.Z and SWR1 were essential for viability of cells lacking the EAF1 component of NuA4, pointing to a close functional connection between these two complexes. Strikingly, chromatin immunoprecipitation analysis of cells lacking Swr1p, the presumed ATPase of the complex, revealed a profound defect in the deposition of H2A.Z at euchromatic regions that flank the silent mating type cassette HMR and at 12 other chromosomal sites tested. Consistent with a specialized role for Swr1p in H2A.Z deposition, the majority of the genome-wide transcriptional defects seen in swr1Δ cells were also found in htz1Δ cells. These studies revealed a novel role for a member of the ATP-dependent chromatin remodeling enzyme family in determining the region-specific histone subunit composition of chromatin in vivo and controlling the epigenetic state of chromatin. Metazoan orthologs of Swr1p (Drosophila Domino; human SRCAP and p400) may have analogous functions

Atomic force microscopy studies of bioprocess engineering surfaces - imaging, interactions and mechanical properties mediating bacterial adhesion

The detrimental effect of bacterial biofilms on process engineering surfaces is well documented. Thus, interest in the early stages of bacterial biofilm formation; in particular bacterial adhesion and the production of anti-fouling coatings has grown exponentially as a field. During this time, Atomic force microscopy (AFM) has become an essential tool for the evaluation of bacterial adhesion. Due to its versatility AFM offers not only insight into the topographical landscape and mechanical properties of the engineering surfaces, but elucidates, through direct quantification the topographical and biomechnical properties of the foulants The aim of this paper is to collate the current research on bacterial adhesion, both theoretical and practical, and outline how AFM as a technique is uniquely equipped to provide further insight into the nanoscale world at the bioprocess engineering surface

The tale of two talins – two isoforms to fine-tune integrin signalling

Talins are cytoplasmic adapter proteins essential for integrin-mediated cell adhesion to the extracellular matrix. Talins control the activation state of integrins, link integrins to cytoskeletal actin, recruit numerous signalling molecules that mediate integrin signalling, and coordinate recruitment of microtubules to adhesion sites via interaction with KANK (kidney ankyrin repeat- containing) proteins. Vertebrates have two talin genes, TLN1 and TLN2. Although talin1 and talin2 share 76% protein sequence identity (88% similarity), they are not functionally redundant, and the differences between the two isoforms are not fully understood. In this Review, we focus on the similarities and differences between the two talins in terms of structure, biochemistry and function, which hint at subtle differences in fine-tuning adhesion signalling

Qualité géométrique & aspect des surfaces (approches locales et globales)

Parmi tous les leviers à disposition des entreprises, la prise en compte de la perception par les clients est aujourd'hui centrale, dès la conception des produits. En effet, le consommateur est aujourd'hui mieux informé et attentif à ce qu'il perçoit de la qualité d'un produit et cette perception lui permet d'établir une valeur d'estime de la qualité esthétique des produits, mais aussi de ses fonctionnalités techniques. La méthodologie de l'analyse de la qualité d'aspect des surfaces est donc un enjeu essentiel pour l'industrie. Deux approches de la fonctionnalité des surfaces sont proposées afin de formaliser la méthodologie de détection, et d'apporter aux experts des critères objectifs d'évaluation des anomalies. La première approche proposée est basée sur la métrologie des surfaces. Elle consiste à analyser les topographies mesurées pour lier la fonction aspect aux caractéristiques géométriques extraites. Une approche multi-échelle basée sur la Décomposition Modale Discrète est mise en oeuvre afin de séparer efficacement les différents ordres de variations géométriques d'une surface, et ainsi d'isoler les anomalies d'aspect. D'autre part, cette méthode permet la mise en oeuvre du calcul des courbures sur une surface de façon simplifiée et robuste. On montre que cet attribut géométrique apporte une information supplémentaire et pertinente en lien avec la fonction aspect. Enfin, ces travaux ont mis en évidence l'importance de la qualité des données sources pour analyser l'aspect, et particulièrement deux difficultés d'ordre métrologiques, liées à la présence de points aberrants (hautes fréquences) et de variations géométriques non intrinsèques aux surfaces, générées par le moyen de mesure (basses fréquences). Une méthode innovante d'identification des points aberrants dédiée à la métrologie des surfaces et basée sur une approche statistique multi-échelle est proposée. La problématique des variations géométriques liées aux tables de positionnement du moyen de mesure est traitée au moyen de la Décomposition Modale, et un protocole pour corriger ces variations est présenté. La seconde approche, plus globale, est basée sur l'interaction entre les surfaces et l'environnement lumineux. L'objet de cette approche de l'analyse de l'aspect est d'apporter une aide aux experts pour mieux détecter les anomalies. Les travaux présentés sont basés sur la technique Polynomial Texture Mappings et consistent à modéliser la réflectance en chaque point des surfaces afin de simuler le rendu visuel sous un éclairage quelconque, à la manière de ce que font les opérateurs en analyse sensorielle pour faciliter la détection. Un dispositif d'aide à l'inspection des surfaces basé sur ce principe est présenté. Enfin, une approche industrielle est proposée afin de montrer comment ces 2 axes de recherche peuvent être complémentaires dans le cadre d'une méthodologie globale, industrielle, de l'analyse de la qualité d'aspect de surfaces.Accounting for customers' perception of manufactured goods has become a major challenge for the industry. This process is to be established from early design to retail. Customers are nowadays more aware and detail oriented about perceived quality of products. This allows one to set not only an estimated price but also the expected quality of the product. Surface appearance analysis has therefore become a key industrial issue. Two approaches are proposed here to formalize the detection methodology and provide objective criteria for experts to evaluate surface anomalies. The first proposed approach is based on surface metrology. It consists in analyzing the measured topologies in order to bind aspect to geometric characteristics. A multi-scale procedure based on Discrete Modal Decomposition is implemented and allows an effective separation of geometric variations. Accordingly, appearance anomalies can be isolated from other geometrical features. This method enables the calculation of surface curvatures in a simplified and robust manner. It is shown that such geometric information is relevant and bound to visual aspect. The presented work also emphasizes the influence of raw data in aspect analysis. Two main metrological difficulties are investigated: the presence of outliers (High frequencies) and the presence of non surface-related geometric defects, generated by the measuring device (Low frequencies). An innovative method for identifying outliers in surface metrology is presented. It is based on a multi-scale statistical approach. Finally, the issue of geometrical variation due to positioning tables is also addressed. A calibration protocol based on DMD that intends to correct this phenomenon is proposed. The second proposed approach, more global, is based on the interaction of a surface with its light environment. It aims at providing experts with assistance, specifically during the anomaly detection phase. The presented work uses Polynomial Texture Mapping. This technique consists of calculating the reflectance at each point of the surface and simulating its appearance while the lighting angles vary. A surface Inspection Support Device based on this principle is presented and detailed. Finally, an industrial study is proposed that shows how these two academic approaches can be combined within a global industrial methodology dedicated to surface appearance quality.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

PTMs developments for the appearance control on high-added value surfaces

International audienceIn many areas of activity, the value of a product depends greatly on the perceived quality, including visual one. This work aims to better control sensory perception of products with high added value, especially on the first step of the visual control: the detection, or localization of anomalies in appearance to the surfaces. Companies have controllers, specially trained to locate and evaluate anomalies. These specialists have a higher sensitivity for the detection and evaluation of defects as a potential buyer for example, and this higher acuity is generally completed by a weighting of the intensity of defects according to their location. However, there is still great variability on the results of the visual inspection. To overcome the disadvantages of human subjectivity, and also handling parts, we present a new device of analysis of surfaces, specifically focused on the step of detection of appearance anomalies, based on a technique called Polynomial Texture Mapping. By varying the direction of the light source, it makes possible to figure out the anomalies present on the surface. The device was developed and built entirely in the Symme laboratory (Université de Savoie, France, Annecy). We are working on developments of the method: - To improve the quality of the "PTM": a new approximation method of reflective surfaces ("Modal Mapping") of each pixel has been done, using the Modal Discrete Decomposition - To estimate the fields of surface normals (slopes). - To integrate normal fields, in order to do 3D reconstruction of the surface - To implement the methodology related to the sensory "human" control of appearance, like simulating the path of the controller eyes, or simulating the lights effects. The results obtained show that the control aspect is greatly facilitated by the device, and that the PTM method is relevant for the appearance control in an industrial environment. Improved estimation of the surface reflectance of each pixel increase greatly the quality of texture mapping, and makes possible current developments (Curvature Mappings, Slope mappings, 3D mappings). It opens new possibilities of augmented reality in the control of surface appearance

PTMs developments for the appearance control on high-added value surfaces

International audienceIn many areas of activity, the value of a product depends greatly on the perceived quality, including visual one. This work aims to better control sensory perception of products with high added value, especially on the first step of the visual control: the detection, or localization of anomalies in appearance to the surfaces. Companies have controllers, specially trained to locate and evaluate anomalies. These specialists have a higher sensitivity for the detection and evaluation of defects as a potential buyer for example, and this higher acuity is generally completed by a weighting of the intensity of defects according to their location. However, there is still great variability on the results of the visual inspection. To overcome the disadvantages of human subjectivity, and also handling parts, we present a new device of analysis of surfaces, specifically focused on the step of detection of appearance anomalies, based on a technique called Polynomial Texture Mapping. By varying the direction of the light source, it makes possible to figure out the anomalies present on the surface. The device was developed and built entirely in the Symme laboratory (Université de Savoie, France, Annecy). We are working on developments of the method: - To improve the quality of the "PTM": a new approximation method of reflective surfaces ("Modal Mapping") of each pixel has been done, using the Modal Discrete Decomposition - To estimate the fields of surface normals (slopes). - To integrate normal fields, in order to do 3D reconstruction of the surface - To implement the methodology related to the sensory "human" control of appearance, like simulating the path of the controller eyes, or simulating the lights effects. The results obtained show that the control aspect is greatly facilitated by the device, and that the PTM method is relevant for the appearance control in an industrial environment. Improved estimation of the surface reflectance of each pixel increase greatly the quality of texture mapping, and makes possible current developments (Curvature Mappings, Slope mappings, 3D mappings). It opens new possibilities of augmented reality in the control of surface appearance

Multi-scale analysis of surface topographies by modal filtering

International audienceThis work introduces an innovative method for the multi-scale analysis of surface topographies, which consists of applying a method based on a new parameterization. This kind of surface parameterization refers to natural modes of vibration, and is therefore named modal parameterization. It allows us to characterize the form, waviness and roughness defects of a surface. This parameterization opens up new fields of analysis, such as the appearance quality of surfaces. It is thereby possible to decompose a measured surface in a vector basis, of which vectors are represented by plane natural eigenmodes sorted by frequency and complexity. Different filtering operations can then be produced, such as extracting the primary form of the surface

Multi-scale analysis of surface topographies by modal filtering

International audienceThis work introduces an innovative method for the multi-scale analysis of surface topographies, which consists of applying a method based on a new parameterization. This kind of surface parameterization refers to natural modes of vibration, and is therefore named modal parameterization. It allows us to characterize the form, waviness and roughness defects of a surface. This parameterization opens up new fields of analysis, such as the appearance quality of surfaces. It is thereby possible to decompose a measured surface in a vector basis, of which vectors are represented by plane natural eigenmodes sorted by frequency and complexity. Different filtering operations can then be produced, such as extracting the primary form of the surface

Multi scale modal decomposition of form, undulation and roughness of surfaces.

International audienc

Precise positioning and active vibration isolation using piezoelectric actuator with hysteresis compensation.

International audienceThis article investigates precise positioning at the micrometer scale using piezoelectric actuators. A special focus is given to the rejection of ambient vibration disturbances. An original experimental setup composed of two superposed piezoelectric actuator stages is used to evaluate the performances of the proposed approach. The bottom one is devoted to the disturbance generation, whereas the upper one allows position tracking and active stabilization. The experimental dynamic and hysteretic characterizations of the top actuator are performed. Based on the identified dynamic model, alinear controller is designed. Its performances are improved with a hysteresis compensation method. Such methods usually imply either simple symmetrical hysteresis (e.g. General Maxwell Slip) or operators able to model asymmetric loops(e.g. Preisach) at the cost of more memory usage and computational time. In the present study, a previously published lightweight asymmetric operator hysteresis is successfully used for the first time within a piezoelectric positioning closed-loop control