Search results for "image processing"
showing 10 items of 3285 documents
Cryo-negative staining
1998
Abstract A procedure is presented for the preparation of thin layers of vitrified biological suspensions in the presence of ammonium molybdate, which we termcryo-negative staining. The direct blotting of sample plus stain solution on holey carbon supports produces thin aqueous films across the holes, which are routinely thiner than the aqueous film produced by conventional negative staining on a continuous carbon layer. Because of this, a higher than usual concentration of negative stain (ca. 16% rather than 2%) is required for cryo-negative staining in order to produce an optimal image contrast. The maintenance of the hydrated state, the absence of adsorption to a carbon film and associate…
Red blood with blue-blood ancestry: Intriguing structure of a snail hemoglobin
2006
The phylogenetic enigma of snail hemoglobin, its isolated occurrence in a single gastropod family, the Planorbidae, and the lack of sequence data, stimulated the present study. We present here the complete cDNA and predicted amino acid sequence of two hemoglobin polypeptides from the planorbid Biomphalaria glabrata (intermediate host snail for the human parasite Schistosoma mansoni ). Both isoforms contain 13 different, cysteine-free globin domains, plus a small N-terminal nonglobin “plug” domain with three cysteines for subunit dimerization (total M r ≈ 238 kDa). We also identified the native hemoglobin molecule and present here a preliminary 3D reconstruction from electron microscopical …
RPPanalyzer Toolbox: An improved R package for analysis of reverse phase protein array data
2014
Analysis of large-scale proteomic data sets requires specialized software tools, tailored toward the requirements of individual approaches. Here we introduce an extension of an open-source software solution for analyzing reverse phase protein array (RPPA) data. The R package RPPanalyzer was designed for data preprocessing followed by basic statistical analyses and proteomic data visualization. In this update, we merged relevant data preprocessing steps into a single user-friendly function and included a new method for background noise correction as well as new methods for noise estimation and averaging of replicates to transform data in such a way that they can be used as input for a new t…
Effect of collagen substrates on proteomic modulation of breast cancer cells
2004
We have previously described the occurrence, in breast and colon cancer extra-cellular matrix, of an oncofoetal form of collagen, OF/LB, able to induce an increase in cell proliferation and motility in the breast cancer cell line 8701-BC. It also caused an increased amount of type V collagen which appears to exert an anti-proliferative effect on the same cells. The aim of the present study was to investigate, at the proteomic level, the effect of OF/LB and type V collagens used as substrates for neoplastic cell growth. Due to the complexity of a whole proteomic profile, a subset of significant protein classes was used to assess variations in protein expression levels. For this study we adop…
Quantum Security Proofs Using Semi-classical Oracles
2019
We present an improved version of the one-way to hiding (O2H) Theorem by Unruh, J ACM 2015. Our new O2H Theorem gives higher flexibility (arbitrary joint distributions of oracles and inputs, multiple reprogrammed points) as well as tighter bounds (removing square-root factors, taking parallelism into account). The improved O2H Theorem makes use of a new variant of quantum oracles, semi-classical oracles, where queries are partially measured. The new O2H Theorem allows us to get better security bounds in several public-key encryption schemes.
A Constructive Arboricity Approximation Scheme
2020
The arboricity \(\varGamma \) of a graph is the minimum number of forests its edge set can be partitioned into. Previous approximation schemes were nonconstructive, i.e., they approximate the arboricity as a value without computing a corresponding forest partition. This is because they operate on pseudoforest partitions or the dual problem of finding dense subgraphs.
Conceptualizing and Measuring the Quality of Democracy: The Citizens' Perspective
2018
In recent years, several measurements of the quality of democracy have been developed (e.g. Democracy Barometer, Varieties of Democracy Project). These objective measurements focus on institutional and procedural characteristics of democracy. This article starts from the premise that in order to fully understand the quality of democracy such objective measurements have to be complemented by subjective measurements based on the perspective of citizens. The aim of the article is to conceptualize and measure the subjective quality of democracy. First, a conceptualization of the subjective quality of democracy is developed consisting of citizens’ support for three normative models of democracy …
Three-dimensional helical CT of the tracheobronchial tree: evaluation of imaging protocols and assessment of suspected stenoses with bronchoscopic co…
1996
To assess the accuracy of three-dimensional (3D) helical CT of normal airways, we evaluated different imaging protocols in test objects and patients. The clinical value of 3D helical CT was composed with bronchoscopy in patients with suspected stenoses, especially before and after endobronchial procedures.Solid test objects--one of central airways and one of peripheral airways--were scanned and assessed for volume defects and stairstep artifacts. Fifty helical studies were performed in 36 patients. We evaluated these images for visualization of segmental bronchi; frequency of artifacts; and presence, localization, and degree of stenoses. Bronchoscopic correlation was available for 40 CT exa…
Analysis of atelectasis, ventilated, and hyperinflated lung during mechanical ventilation by dynamic CT.
2005
Study objective: To study the dynamics of lung compartments by dynamic CT (dCT) imaging during uninterrupted pressure-controlled ventilation (PCV) and different positive end-expiratory pressure (PEEP) settings in healthy and damaged lungs. Design: Experimental animal investigation. Setting: Experimental animal facility of a university department. Interventions: In seven anesthetized pigs, static inspiratory pressure volume curves were obtained to identify the individual lower inflection point (LIP) before and after saline solution lung lavage. During PCV, PEEP was adjusted 5 millibars (mbar) below the individually determined LIP (LIP - 5), at the LIP, and 5 mbar above the LIP (LIP + 5). Mea…
Assessment of lung microstructure with magnetic resonance imaging of hyperpolarized Helium-3
2005
Magnetic resonance imaging of the apparent diffusion coefficient (ADC) of hyperpolarized Helium-3 is a new technique for probing pulmonary microstructure in vivo. The aim of this study was the assessment of potential sources of systematic errors of the ADC measurement. The influence of macroscopic motion was determined by measurements at two different delays after initiating the breath-hold, and before and after cardiac arrest. An intercentre comparison was performed in two age- and lung function-matched groups of lung-healthy volunteers at two research sites. Moreover, measurements of diffusion anisotropy were performed. We found no dependency of the ADC as a function of the delay after st…