Search results for " Microscopy"

Spatially-multiplexed interferometric microscopy (SMIM): converting a standard microscope into a holographic one

2014

We report on an extremely simple, low cost and highly stable way to convert a standard microscope into a holographic one. The proposed architecture is based on a common-path interferometric layout where the input plane is spatially-multiplexed to allow reference beam transmission in a common light-path with the imaging branch. As consequence, the field of view provided by the layout is reduced. The use of coherent illumination (instead of the broadband one included in the microscope) and a properly placed one-dimensional diffraction grating (needed for the holographic recording) complete the experimental layout. The proposed update is experimentally validated in a regular Olympus BX-60 upri…

Dopant Contrast in Semiconductors as Interpretation Challenge at Imaging by Electrons

2007

Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.

The future of transmission electron microscopy (TEM) in biology and medicine.

2000

1996

The uses of atomic force microscopy, scanning tunneling microscopy, electron spectroscopic imaging, electron energy loss spectroscopy and low voltage, high resolution scanning electron microscopy in polymer research are reviewed

Granulometric moments and corneal endothelium status

2001

Abstract Specular microscopy is a common practice in Ophthalmology. The corneal endothelium status is usually evaluated by means of the density, the hexagonality, the mean, the standard deviation and the coefficient of variation of cell areas. We propose to replace the cell area moments by the corresponding moments of a different probability distribution, the granulometric size distribution associated to a disc. All cells touching the frame are ignored by the area moments but used by the granulometric moments. Twenty images have been analyzed. When the size of the focused region is reduced, the area moments show a greater variation than the corresponding granulometric moments.

Granulometric analysis of corneal endothelium specular images by using a germ–grain model

2007

Specular microscopy is widely used to study the human corneal endothelium status in vivo. In this paper, the corneal endothelium is represented as a binary image composed of the cell inscribed circles. The granulometric distribution function of the complement of this image is used as a functional descriptor, which provides information about the shape, size and spatial arrangement of cells. Experimental evaluation using bootstrap techniques shows its ability to discriminate between controls and pathological cases. It represents a reliable and graphical alternative to the classical indices (cell density, hexagonality and coefficient of variation of cell areas), which behave poorly when detect…

Classifying human endothelial cells based on individual granulometric size distributions

2002

Abstract This paper presents an application to a medical problem of methods of shape analysis based on mathematical morphology. The medical problem consists on the detection of abnormalities in the corneal endothelium, a tissue composed by quasi-planar cells of ideally regular hexagonal shape. Images of this tissue are taken by a specular microscope and used to evaluate the corneal endothelium status. Up to now, cell density, hexagonality and an analysis of cell areas are the usual descriptors of a corneal endothelium. These parameters are not sensitive enough to detect subtle lesions. What this paper proposes is an analysis based on granulometries, which are size-shape descriptors widely u…

Set Descriptors for Visual Evaluation of Human Corneal Endothelia

2001

Images of corneal endothelium obtained from specular microscopy are of great importance in the evaluation of the corneal endothelium status. Several commercial tools provide some numerical descriptors to characterize these images in terms of cell density, hexagonality, and some descriptive statistics of the cell areas. However, it is a too simple analysis that only detects severe abnormal endothelia with many irregular and large cells. Detection of subtle abnormalities needs a more refined analysis. This paper proposes a shape-size descriptor based on some modified versions of the geometric covariogram. This descriptor is presented as a valid alternative to the classical analysis that provi…

Digital holographic microscopy as a screening technology for diabetes

2019

Label-free quantitative phase imaging (QPI) is the hallmark of digital holographic microscopy (DHM). One of the most interesting medical applications of QPI-DHM is that it can be used to analyze illnesses in which the refractive index or/and the morphology of cells/tissues are distorted, from the acquisition of a single image. In this contribution, we obtain the phase maps of red blood cells (RBCs) samples of patients suffering from diabetes mellitus type 1 (DM1) by using a DHM. Our experimental results show that the measured phase values are significantly different between control non-diabetic and diabetic patients. The high correlation coefficient between the phase and the glycated hemogl…

Exploiting Cryo-EM Structural Information and All-Atom Simulations To Decrypt the Molecular Mechanism of Splicing Modulators.

2019

Splicing modulators (SMs) pladienolides, herboxidienes, and spliceostatins exert their antitumor activity by altering the ability of SF3B1 and PHF5A proteins, components of SF3b splicing factor, to recognize distinct intron branching point sequences, thus finely calibrating constitutive/alternative/aberrant splicing of pre-mRNA. Here, by exploiting structural information obtained from cryo-EM data, and by performing multiple μs-long all-atom simulations of SF3b in apo form and in complex with selected SMs, we disclose how these latter seep into the narrow slit at the SF3B1/PHF5A protein interface. This locks the intrinsic open/closed conformational transitions of SFB1's solenoidal structure…