Search results for " Gradient"

IM30 triggers membrane fusion in cyanobacteria and chloroplasts

2015

The thylakoid membrane of chloroplasts and cyanobacteria is a unique internal membrane system harbouring the complexes of the photosynthetic electron transfer chain. Despite their apparent importance, little is known about the biogenesis and maintenance of thylakoid membranes. Although membrane fusion events are essential for the formation of thylakoid membranes, proteins involved in membrane fusion have yet to be identified in photosynthetic cells or organelles. Here we show that IM30, a conserved chloroplast and cyanobacterial protein of approximately 30 kDa binds as an oligomeric ring in a well-defined geometry specifically to membranes containing anionic lipids. Triggered by Mg2+, membr…

An approach to evaluate the information in chromatographic fingerprints: Application to the optimisation of the extraction and conservation condition…

2015

A new approach is reported for high-performance liquid chromatography to measure the level of information in fingerprints. For this purpose, the concept of peak prominence, which is the protruding part of each visible peak with regard to the valleys that delimit it, was used. The peaks in the fingerprints are ranked according to the areas of the peak prominences, and a threshold is established to discriminate between the significant peaks and those that are irreproducible. The approach was applied to evaluate the impact of several extraction conditions (solvent nature and composition, time and temperature of the treatment, amount of sample, and time and temperature of conservation of the ex…

Evaluation of dynamic microbial communities in a styrene-degrading biotrickling filter using 16S rDNA tag pyrosequencing and denaturing gradient gel …

2014

Accurately characterizing microbial communities within bioreactors undergoing dynamic operating conditions is an essential first step towards understanding the relationship between microbial community structure and bioreactor performance. A detailed assessment of the changes in microbial populations within a styrene-degrading biotrickling filter was carried out using samples collected at multiple time points ranging from 21 to 155 days of biotrickling filter operation. Examination of microbial populations was conducted by 16S rDNA tag pyrosequencing and denaturing gradient gel electrophoresis (DGGE). Validation of pyrosequencing results was performed by quantitative polymerase chain reactio…

Sample streaks and smears in immobilized pH gradient gels

1996

In immobilized pH gradient (IPG) gel formulations as wide as pH 4-9, encompassing neutrality and containing the pK 7.0 acrylamido buffer as one of the buffering ions, smears are directly proportional to the total amount of the pK 7.0 species. At a total level of 10 mM pK 7.0 in these gel formulations, severe smears occur not only for mildly hydrophobic proteins (e.g., recombinant alcalase and termamylase) but also for the relatively hydrophilic pI marker proteins. Streaks and smears are essentially abolished in recipes devoid of the pK 7.0 compound or in formulations containing a maximum of 3 mM of this component. Although partitioning in water/n-octanol has shown the pK 7.0 acrylamido buff…

Extraktionschromatographische trennung der freien porphyrine auf tri-n-butylphosphat-s?ulen im pH-gradienten

1969

Abstract The method described allows the separation of the free porphyrins on a tri-n-butyl phosphate (TBP) column by elution with a pH gradient. The prophyrins are eluted from the column at discrete pH values (xD) according to the number of carboxyl groups in the side chains. Separation of isomers could not be observed under the conditions used. The xD values indicate the centre of the pH-interval, in which the dissociation of the carboxyl groups occurs. This finding could be confirmed by spectro-photometric measurements. By combining the method proposed with the method of separation by extraction chromatography in the TBP/IN HCl partition system and the thin-layer technique in the 2,6-lut…

CLOSING THE LOOP: STUDY OF INTEGRATED CYCLES WITH NATURAL AND ARTIFICIAL SOLUTIONS FOR THE PRODUCTION OF ENERGY, MINERALS AND FRESH WATER

A Combinatorial Color Edge Detector

2004

In this paper, we present an edge detection approach in color image using neighborhood hypergraph. The edge structure is detected by a structural model. The Color Image Neighborhood Hypergraph (CINH) representation is first computed, then the hyperedges of CINH are classified into noise or edge based on hypergraph properties. To evaluate the algorithm performance, experiments were carried out on synthetic and real color images corrupted by alpha-stable noise. The results show that the proposed edge detector finds the edges properly from color images.

Average Performance Analysis of the Stochastic Gradient Method for Online PCA

2019

International audience; This paper studies the complexity of the stochastic gradient algorithm for PCA when the data are observed in a streaming setting. We also propose an online approach for selecting the learning rate. Simulation experiments confirm the practical relevance of the plain stochastic gradient approach and that drastic improvements can be achieved by learning the learning rate.

Change-driven Image Architecture on FPGA with adaptive threshold for Optical-Flow Computation

2006

Optical flow computation has been extensively used for object motion estimation in image sequences. However, the results obtained by most optical flow techniques are as accurate as computationally intensive due to the large amount of data involved. A new strategy for image sequence processing has been developed; pixels of the image sequence that significantly change fire the execution of the operations related to the image processing algorithm. The data reduction achieved with this strategy allows a significant optical flow computation speed-up. Furthermore, FPGAs allow the implementation of a custom data-flow architecture specially suited for this strategy. The foundations of the change-dr…

New systems for extracting 3-D shape information from images

1993

Neural architectures may offer an adequate way to deal with early vision since they are able to learn shape features or classify unknown shapes, generalising the features of a few meaningful examples, with a low computational cost after the training phase. Two different neural approaches are proposed by the authors: the first one consists of a cascaded architecture made up by a first stage named BWE (Boundary Webs Extractor) which is aimed to extract a brightness gradient map from the image, followed by a backpropagation network that estimates the geometric parameters of the object parts present in the perceived scene. The second approach is based on the extraction of the boundary webs map …