Nanoflow liquid chromatography coupled to matrix-assisted laser desorption/ionization mass spectrometry: Sample preparation, data analysis, and application to the analysis of complex peptide mixtures

We report the development of a robust interface for off-line coupling of nano liquid chromatography (LC) to matrix-assisted laser desorption/ionisation-mass spectrometry (MALDI-MS) and its application to the analysis of proteolytic digests of proteins, both isolated and in mixtures. The interface makes use of prestructured MALDI sample supports to concentrate the effluent to a small sample plate area and localize the MALDI sample to a predefined array, thereby enriching the analyte molecules and facilitating automated MALDI-MS analysis. Parameters that influence the preparation of MALDI samples from the LC effluent were evaluated with regard to detection sensitivity, spectra quality, and reproducibility of the method. A procedure for data processing is described. The presented nano LC MALDI-MS system allowed the detection of several peptides from a tryptic digest of bovine serum albumin, at analyzed amounts corresponding to one femtomole of the digested protein. For the identification of native proteins isolated from mouse brain by two-dimensional gel electrophoresis, nano LC MALDI-MS increased the number of detected peptides, thereby allowing identification of proteins that could not be identified by direct MALDI-MS analysis. The ability to identify proteins in complex mixtures was evaluated for the analysis of Escherichia coli 50S ribosomal subunit. Out of the 33 expected proteins, 30 were identified by MALDI tandem time of flight fragment ion fingerprinting

CREB Inhibits AP-2α Expression to Regulate the Malignant Phenotype of Melanoma

The loss of AP-2alpha and increased activity of cAMP-responsive element binding (CREB) protein are two hallmarks of malignant progression of cutaneous melanoma. However, the molecular mechanism responsible for the loss of AP-2alpha during melanoma progression remains unknown.Herein, we demonstrate that both inhibition of PKA-dependent CREB phosphorylation, as well as silencing of CREB expression by shRNA, restored AP-2alpha protein expression in two metastatic melanoma cell lines. Moreover, rescue of CREB expression in CREB-silenced cell lines downregulates expression of AP-2alpha. Loss of AP-2alpha expression in metastatic melanoma occurs via a dual mechanism involving binding of CREB to the AP-2alpha promoter and CREB-induced overexpression of another oncogenic transcription factor, E2F-1. Upregulation of AP-2alpha expression following CREB silencing increases endogenous p21(Waf1) and decreases MCAM/MUC18, both known to be downstream target genes of AP-2alpha involved in melanoma progression.Since AP-2alpha regulates several genes associated with the metastatic potential of melanoma including c-KIT, VEGF, PAR-1, MCAM/MUC18, and p21(Waf1), our data identified CREB as a major regulator of the malignant melanoma phenotype

Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

Waermeuebergang und Siedebeginn beim unterkuehlten Sieden unter Zwangskonvektion

SIGLEAvailable from TIB Hannover: DR 4481 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Affine Point Pattern Matching

This paper presents a general solution for the problem of affine point pattern matching (APPM). Formally, given two sets of two-dimensional points (x,y) which are related by a general affine transformation (up to small deviations of the point coordinates and maybe some additional outliers). Then we can determine the six parameters a  ¡ of the transformation using new Hu point-invariants which are invariant with respect to affine transformations. With these invariants we compute a weighted point reference list. The affine parameters can be calculated using the method of the least absolute differences (LAD method) and using linear programming. In comparison to the least squares method, our approach is very robust against noise and outliers. The algorithm works in O(n) average time and can be used for translation and/or rotations, isotropic and non-isotropic scalings, shear transformations and reflections.