Search results for "Microscopy"

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

Survival of Erwinia amylovora in mature apple fruit calyces through the viable but nonculturable (VBNC) state

2009

Aims:  Survival of Erwinia amylovora, causal agent of fire blight in pome fruits and other rosaceous plants, was monitored inside mature apples calyces under some storage conditions utilized in fruit. Methods and Results:  Apple fruit calyces inoculated with two E. amylovora strains and their respective GFP-marked strains were maintained at 26° and 5°C, and the effect of copper treatment was assayed at 0·01 and 0·1 mmol l−1 CuSO4. In nontreated apples at 26°C, part of the population of E. amylovora survived in the ‘viable but nonculturable’ (VBNC) state, whereas at 5°C the majority of the population retained culturability. In copper-treated apples, the whole population adopted the VBNC stat…

Mutation Analysis of Core Binding Factor A1 in Patients with Cleidocranial Dysplasia

1999

SummaryCleidocranial dysplasia (CCD) is a dominantly inherited disorder characterized by patent fontanelles, wide cranial sutures, hypoplasia of clavicles, short stature, supernumerary teeth, and other skeletal anomalies. We recently demonstrated that mutations in the transcription factor CBFA1, on chromosome 6p21, are associated with CCD. We have now analyzed the CBFA1 gene in 42 unrelated patients with CCD. In 18 patients, mutations were detected in the coding region of the CBFA1 gene, including 8 frameshift, 2 nonsense, and 9 missense mutations, as well as 2 novel polymorphisms. A cluster of missense mutations at arginine 225 (R225) identifies this residue as crucial for CBFA1 function. …

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…