摘要:

AbstractThe photon pressure exerted on thin film and small particles, which are located in the evanescent field near the surface of a high refractive‐index prism, is studied. The mechanism of the movement of particles in the evanescent field is first discussed, and the calculations resulting from the force exertion on the film by the evanescent field are shown in the different conditions of film thickness, spacing from the surface to the film, incident angle and polarization of the laser beam, with the data of the electric‐field intensity distribution. It is found from these results that the force on the film near the substrate could change the action from pulling to pushing it by changing the parameters. It is also found that at a certain condition of incident angle and polarization, a trapping (levitation) force will occur on the film towards a given position above the surface of the substr

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<1::AID-BIO2>3.0.CO;2-L

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA method for estimating surface area is developed for three‐dimensional binary objects. This method is based on assigning surface area weights to the surface volume‐elements (voxels) of a binary object. Surface voxels are defined as object voxels which are six‐connected to one or more background voxels. Of the many types of surface voxel configurations, three basic types dominate the surface of relatively smooth, solid objects. These basic types are surface voxels with one, two or three adjacent sides exposed to the background. In planar regions, only these three types exist. By assigning weights to the various surface voxel configurations, total surface area can be estimated by summing the area contributed by all surface voxels of an object. Since this method estimates an object's true surface area, the weights selected should be optimized to give unbiased results with minimum mean‐square‐error. Formulae to calculate bias and mean‐square‐error are developed for this surface model when applied to randomly oriented and positioned planar regions. Optimal weights computed from these formulae for surface voxels with one, two or three adjacent sides areW1≈ 0.8940,W2≈ 1.3409 andW3≈ 1.5879, respectively, in sample‐grid units squared, with a coefficient of variation (CV = σ/μ) of 2.33%. To address the feasibility for area estimation of curved surfaces, e.g. surfaces of objects extracted from biological or medical3Dimages, this method is applied to binary spheres. Furthermore, previously published methods for estimating surface area are compared wi

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<6::AID-BIO3>3.0.CO;2-3

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractImage digitizers, particularly video frame grabbers, are subject to the phenomenon of ‘jitter’. This is due to timing instabilities, and it manifests itself in a slight shifting of rows or columns of image data relative to neighbouring rows or columns. This can degrade displayed image quality and reduce the accuracy of measurements extracted from the objects within the image. This paper illustrates a method for quantifying the amount of jitter present in a digitized im

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<17::AID-BIO4>3.0.CO;2-M

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper we present a volume visualization method for multi‐parameter images of three dimensional microscopic objects. Our aim in developing the method is the visualization of unsegmented images in a reliable way. The capability to render unprocessed images is a prerequisite for a visualization tool when used during interactive image segmentation and analysis. In addition, such a method makes it feasible to equip volume imaging instruments, such as confocal microscopes, with a device the authors call an ‘intelligent eyepiece’. The visualization algorithm is founded on the physical process of fluorescence, ensuring its fidelity and enablingphysically realistic volume rendering. In addition to the method presented, applications to three‐dimensional confocal microscopical and medical data sets are di

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<20::AID-BIO5>3.0.CO;2-2

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAlterations in plasma membrane structure and function are considered of primary importance in the pathogenesis of cell injury. Here, fluorescence quenching imaging and Fluorescence Resonance Energy Transfer (FRET) imaging were used to detail alterations of plasma membrane structure during hypoxic injury in rat hepatocytes. Each of these methods provides complementary information and indicated that hypoxic injury leads to a spatially and temporally heterogeneous increase in the rigidity of the plasma membrane. We propose a model, based on our results, for the explanation of alterations in plasma membrane architecture which occur during hypoxic injury. This model also suggests points at which interventional strategies may be applied to prevent or decrease the extent of the hypoxia‐induced changes in membrane structure and thus prolong or even rescue cells from hypoxic injur

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<30::AID-BIO6>3.0.CO;2-Z

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBy combining near‐infrared intensity‐modulated illumination with frequency domain detection methods, we have obtained the first detailed optical images of thick tissues (1–3 cm). The raw data of these images are characterized by millimetre resolution and high contrast. The method employs a pulsed laser coupled to a cross‐correlation frequency domain detection scheme. The near‐infrared imaging method is non‐invasive and inexpensive, uses non‐ionizing radiation and is potentially fast enough for real‐time imaging in the seconds time range. In the frequency domain, diffusional wave optics provides the framework for a description of the light propagation in tissues. Our approach results in a theoretically and experimentally simple way to exploit the advantages of time resolution in optical imaging of inhomogeneous highly scattering materials. At any given modulation frequency, the light wavefront advances at constant velocity in a spherical wave. Objects with scattering or absorption coefficients that are different from the surrounding medium cause a deformation of the propagating wavefront that can be accurately measured using frequency domain detection methods. The visualization (on a computer screen) of these wavefront deformations provides a projection of the i

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<40::AID-BIO7>3.0.CO;2-V

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractExisting estimators for edge length in2Dand surface area in3Dare applied to a binary representation of the object. In this paper we estimate length and surface area through grey‐volume measurements. Volume is measured without thresholding and does not introduce a sampling error. Object boundaries are carefully transformed into volumes using bandlimited operations.We give two methods: GC and GCL. The GC method measures the length of an isophote. The GCL method measures the length of the Laplacian zerocrossing line. The GC estimator is biased because the isophote position is shifted towards smaller radii due to both analogue and digital low‐pass filtering. The GCL estimator contains a compensating mechanism and yields unbiased results for both the edge position and the length.Extension of both methods to3Dimages is straightforward. The3DGC area bias is scale independent. The3DGCL method yields unbiased edge position. For3Dobjects without tunnels or enclosed cavities the3DGCL area bias amounts to a constant correction per object and an unbiased estimator can still be construc

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<47::AID-BIO8>3.0.CO;2-7

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0966-9051    

DOI:10.1002/1361-6374(199303)1:1<::AID-BIO1>3.0.CO;2-G

出版商:IOP Publishing Ltd    

年代:1993

数据来源: WILEY