Search results for " parabola"

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Half-width plots, a simple tool to predict peak shape, reveal column kinetics and characterise chromatographic columns in liquid chromatography: Stat…

2013

Peak profiles in chromatography are characterised by their height, position, width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution, the plots are parabolic, although often, the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics, eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mas…

Peak profiles in chromatography are characterised by their height position width and asymmetry; the two latter depend on the values of the left and right peak half-widths. Simple correlations have been found between the peak half-widths and the retention times. The representation of such correlations has been called half-width plots. For isocratic elution the plots are parabolic although often the parabolas can be approximated to straight-lines. The plots can be obtained with the half-widths/retention time data for a set of solutes experiencing the same kinetics eluted with a mobile phase at fixed or varying composition. When the analysed solutes experience different resistance to mass transfer the plots will be solute dependent and should be obtained with the data for each solute eluted with mobile phases at varying composition. The half-width plots approach is a simple tool that facilitates the prediction of peak shape (width and asymmetry) with optimisation purposes reveal the interaction kinetics of solutes in different columns and characterise chromatographic columns. This work shows half-width plots for different situations in isocratic elution including the use of different flows the effect of temperature the modification of the stationary phase surface by an additive the existence of specific interactions within the column and the comparison of columns. The adaptation to gradient elution is also described. Previous knowledge on half-width plots is structured and analysed to which new results are added.Work (thermodynamics)Column characterisationmedia_common.quotation_subjectKineticsLiquid chromatographyAnalytical chemistryHalf-widthsInteraction kineticsBiochemistryAsymmetryAnalytical ChemistryPeak shapeColumn (typography)Position (vector)Mass transferPhase (matter)media_commonChromatographyElutionChemistryOrganic ChemistryGeneral MedicineModels TheoreticalKineticsPredictionChromatography LiquidJournal of Chromatography A
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Optic disc positioning and blood vessels extraction on eye fundus

2009

This paper presents two methods aimed to the optic disc positioning on the retinal images. The first is based on a template of the entire image, while the second is based on the retinal vascularisation. For this second task, also a vessel extraction method is provided. Both the algorithm have been tested on test images of the Drive Database.

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniRetinaRetinal vessels vascular tree matched filter ROC curve optic disc parabola parabolic modelbusiness.industryComputer scienceRetinalImage segmentationRetinal imagechemistry.chemical_compoundmedicine.anatomical_structurechemistrymedicineMedical imagingExtraction methodsComputer visionsense organsArtificial intelligencebusinessOptic discParabolic model
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