The authors address the analysis of three dimensional shape and shape change in nonrigid biological objects imaged via a stereo light microscope (SLM). Most existing stereo or motion analysis techniques cannot be appl...
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The authors address the analysis of three dimensional shape and shape change in nonrigid biological objects imaged via a stereo light microscope (SLM). Most existing stereo or motion analysis techniques cannot be applied to microscopic biological images because they usually lack salient features. The authors propose an integrated approach for the reconstruction of 3D structures and motion analysis for scenes where only a few informative features are available. The key components of this framework are: (1) image registration, (2) region-of-interest extraction, and (3) stereo and motion analysis using a cooperative spatial and temporal matching process. The authors describe these three stages of processing and illustrate the efficacy of the proposed approach using real images of a live frog's ventricle. The reconstructed dynamic 3-D structures of the ventricle are demonstrated in the authors' experimental results.< >
This study investigates the application of Raman spectroscopy and partial least squares for the determination of glucose concentration in mixtures containing lactic acid and urea in water. The Raman spectrometer consi...
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This study investigates the application of Raman spectroscopy and partial least squares for the determination of glucose concentration in mixtures containing lactic acid and urea in water. The Raman spectrometer consisted of a sequence of beam conditioning, sample, and post-sample beam conditioning stages, followed by the monochrometer and CCD detector. The excitation source was a 514.3 nm Argon laser delivering 10 mW of power to the sample. The standard deviation of the residuals for a cross validation of the entire data set was 22.3 mg/dl. This work is part of a continuing effort in the development of technology toward noninvasive glucose sensing for diabetics.< >
Autoregressive power spectral estimation of stabilometric signals is investigated to determine a suitable model order and sampling rate. The spectra of 30 healthy subjects were studied with a protocol of eyes open/clo...
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Autoregressive power spectral estimation of stabilometric signals is investigated to determine a suitable model order and sampling rate. The spectra of 30 healthy subjects were studied with a protocol of eyes open/closed and feet together/apart.
Parallel-detection electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope provides a very sensitive means of detecting specific elements in biological systems. By analyzing EELS spec...
Parallel-detection electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope provides a very sensitive means of detecting specific elements in biological systems. By analyzing EELS spectrum-image data recorded from rapidly-frozen and cryosectioned tissue it is possible to map quantitatively the distribution of the biologically important element, calcium, which is typically present at concentrations of only a few parts per million in cellular structures some tens of nanometers in diameter. A significant improvement (factor of four) in calcium detectability has been demonstrated for EELS compared with energy-dispersive x-ray spectroscopy. The spectrum-imaging technique has also been applied to map water distributions in hydrated biological specimens by utilizing the valence electron excitations.
Diffusion tensor imaging (DTI) provides intravoxel microstructural and microdynamic information about tissues that reflects their physiological state. The authors use DTI to assess changes in water mobility in an in v...
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Diffusion tensor imaging (DTI) provides intravoxel microstructural and microdynamic information about tissues that reflects their physiological state. The authors use DTI to assess changes in water mobility in an in vivo model of cerebral ischemia in cats. They use four estimated scalar quantities: the 3 principal diffusivities (/spl lambda//sub 1/, /spl lambda//sub 2/, and /spl lambda//sub 3/) and the T/sub 2/-weighted NMR signal (A(0)), as features with which to segment both normal and pathological tissues. While the authors can use these parameters to discriminate between normal and ischemic white and gray matter in cats, they are evaluating their use to distinguish between reversibly and irreversibly damaged tissues during stroke and other white matter diseases.< >
Currently, various types of pulsed lasers are used for ablation of tissue. Owing to their small penetration depth, mid-infrared and ultraviolet lasers are attractive candidates for precise tissue cutting. Furthermore,...
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Currently, various types of pulsed lasers are used for ablation of tissue. Owing to their small penetration depth, mid-infrared and ultraviolet lasers are attractive candidates for precise tissue cutting. Furthermore, both the mid-infrared and ultraviolet laser pulses can be delivered via flexible fibers, which allows ablation of tissue in a water environment and in the human body. The mid-infrared holmium (wavelength λ = 2.09 μm) and thulium (λ = 2.01 μm) laser ablation is based on the absorption and subsequent vaporization of tissue water. As a result, with each laser pulse, a rapidly expanding and imploding vapor bubble (lifetime τ ≈ 500 μs, diameter ∅ up to 3 mm) is formed.1
The objectives of this research were (I) to determine whether the use of partially absorbable vascular grafts would improve their nonthrombogenic performance and whether they are more prone to aneurysmal dilation and ...
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The objectives of this research were (I) to determine whether the use of partially absorbable vascular grafts would improve their nonthrombogenic performance and whether they are more prone to aneurysmal dilation and subsequent failure in vivo. and (2) to find out the relationships, if any. between these in vivo and the previously reported in vitro data with an emphasis on how the in vitro changes in fabric structure and properties related to these in vivo data. Bicomponent vascular fabrics were made from Dacron and polyglycolic acid (PGA) yarns with a range of composition ratios of the PGA to Dacron. Both woven and single Jersey knit fabrics were made, and implanted in dogs for 4 months. The following findings and relationships were obtained. (1) The bicomponent vascular fabrics resulted in a full-wall healing in the thoracic aorta of dogs. All bicomponent vascular grafts in survived dogs exhibited 100% patency, no thrombus or aneurysmal formation, no hematoma or seroma around the grafts, and no fibrin coagula in the inner capsules. The gross morphology of the regenerated tissues was very similar visually to the adjacent original arterial tissue. Histologically, the luminal surface was lined with a layer of endothelial cells with myofibroblasts, fibroblasts. and collagens underneath. (2) The extent of the full-wall healing depended on the type of fabric structure. the concentration of absorbable yarns, the location of absorbable yarns (for the woven group only), and initial water permeability. It is believed that the concentration effect was related to the level of macrophage activation from the degradation products of the absorbable yarns, while the location effect was attributed to the various types of fabric structure change on the degradation of the absorbable yarns. (3) In general, the knitted group (K), was better than the woven group (W). K3 showed the best in vivo performance in the knitted group. (4) In the woven group, W3 was the best. The incorporation o
A computer graphics model was used to analyze electromyographic (EMG) and kinematic data from the head and neck of two freely moving cats. The model was used to study two cats performing /spl plusmn/15/spl deg/ sinuso...
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A computer graphics model was used to analyze electromyographic (EMG) and kinematic data from the head and neck of two freely moving cats. The model was used to study two cats performing /spl plusmn/15/spl deg/ sinusoidal (0.25 Hz) head tracking movements in the sagittal plane. Cinefluoroscopic images revealed that vertebral motion described a nearly circular arc in a cat that was standing compared to a diagonal line in a cat that was lying prone. The prone lying animal had more acute angles between the vertebrae. The selection of muscles that were most strongly activated and the aiming of muscle activation differed between the two cats. EMG lead vertebral motion in the standing cat, but EMG was in phase with the peak up position of the head in the prone cat. Analysis of the model indicated that there was very little difference in the moment-generating capacity of each muscle between the two postures. Thus, we expect that the differences in the kinematics resulted from altered muscle activation patterns rather than differences in the musculoskeletal system in the two postures.< >
Multichannel recordings of both movement-related magnetic fields (MRMFs) and movement-related cortical potentials (MRCPs) were simultaneously recorded in association with voluntary unilateral self-paced index finger a...
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