Imaging-in-flow: digital holographic microscopy as a novel tool to detect and classify nanoplanktonic organisms

Traditional taxonomic identification of planktonic organisms is based on light microscopy, which is both time-consuming and tedious. In response, novel ways of automated (machine) identification, such as flow cytometry, have been investigated over the last two decades. To improve the taxonomic resolution of particle analysis, recent developments have focused on "imaging-in-flow," i.e., the ability to acquire microscopic images of planktonic cells in a flow-through mode. Imaging-in-flow systems are traditionally based on classical brightfield microscopy and are faced with a number of issues that decrease the classification performance and accuracy (e. g., projection variance of cells, migration of cells out of the focus plane). Here, we demonstrate that a combination of digital holographic microscopy (DHM) with imaging-in-flow can improve the detection and classification of planktonic organisms. In addition to light intensity information, DHM provides quantitative phase information, which generates an additional and independent set of features that can be used in classification algorithms. Moreover, the capability of digitally refocusing greatly increases the depth of field, enables a more accurate focusing of cells, and reduces the effects of position variance. Nanoplanktonic organisms similar in shape were successfully classified from images captured with an off-axis DHM with partial coherence. Textural features based on DHM phase information proved more efficient in separating the three tested phytoplankton species compared with shape-based features or textural features based on light intensity. An overall classification score of 92.4% demonstrates the potential of holographic-based imaging-in-flow for similar looking organisms in the nanoplankton range

Mise en évidence de Yersinia enterocolitica dans un liquide d'ascite

A strain of Yersinia enterocolita was isolated from a peritoneal fluid obtained in a cirrhotic woman a few hours before death occurs. No symptoms suggesting peritoneal or abdominal infection was present. © 1975.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

SENSIBILITE DES KLEBSIELLA AUX ANTIBIOTIQUES. ETUDE DE 50 SOUCHES PROVENANT DE SEPTICEMIES 'EXTRA' ET 'INTRAHOSPITALIERES'

The sensitivity to antibacterial substances of 50 strains of Klebsiella, isolated by blood culture during the period 1967 to 1971, was determined by the disk method and by determination of mean inhibitory concentrations. All strains were sensitive to gentamicin (MIC ≤ 1.56 μg/ml) and to a lesser extent to trimethoprim (MIC ≤ 3.12 μg/ml). 54% of Klebsiella strains were sensitive to cefalotin and 28% to sulfamethoxazole. There exists a synergy between trimethoprim and sulfamethoxazole. 26% of the strains were inhibited by chloramphenicol, kanamycin and tetracycline. They were isolated almost exclusively in cases of septicemia outside the hospital. A discrepancy between the disk method and the measurement of MIC was observed in 6% of cases for trimethoprim and in 15% of cases for cefalotin.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Applications of digital holographic microscopes with partially spatial coherence sources

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Refocus criterion based on the phase in the Fourier domain for automatically refocusing in multispectral digital holographic microscopy: Accuracy and dependency study

The fast autofocus criterion using the phase in the Fourier domain, suitable for digital holographic microscopy when the complex field is known for at least two distinct wavelengths, is deeply investigated, which allows finer adjustment

Digital holgraphic microscopy for three-dimensional study of phospholipid vesicles in a sher flow under microgravity conditions

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