This study is concerned with the development of an integrated multiple compartment model of the isolated cerebral artery in the rat. The smooth muscle/arterial wall complex is an important component of the circulatory...
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This study is concerned with the development of an integrated multiple compartment model of the isolated cerebral artery in the rat. The smooth muscle/arterial wall complex is an important component of the circulatory model and serves as an "vasomotor organ", which provides the myogenic mechanism. We have focused on this myogenic mechanism and have developed a model of the electrophysiological, contractile and mechanical characteristics of the single smooth muscle cell. This cell model is used to interrelate the topics of arterial wall stress, changes in transmembrane potential, intracellular [Ca/sup 2+/]/sub i/ concentration and smooth muscle contraction. Moreover, the small cell model is embedded in a larger arterial wall model, which converts contractile activity into changes in lumen diameter. The complete model is used to provide biophysically based explanations of the myogenic mechanisms underlying the autoregulation of cerebral blood flow.
Results are reported, based on 5 healthy subjects, concerning patterns in thedynamics of the sequential arrangement of spindles in human stage 2 sleep. Specifically, theconditional probability of incidence of successi...
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Results are reported, based on 5 healthy subjects, concerning patterns in thedynamics of the sequential arrangement of spindles in human stage 2 sleep. Specifically, theconditional probability of incidence of successive spindle lengths and successive inter-spindleintervals is investigated. The results show that successive spindle lengths may be statisticallyindependent. However, their distribution (histogram) may be similar for two different stage 2periods, one in the first third and another in the second third of the night sleep record. Incontrast to the finding about spindle lengths, results show that successive inter-spindle intervalsmay not be statistically independent. Furthermore, the overall dynamics of the sequentialarrangement of inter-spindle intervals may be similar for the two sleep periods. These findings arediscussed in the context of the "sleep maintenance" role of spindles.
Although NMR has the ability to investigate biological systems non-destructively, it suffers from low sensitivity compared to other analytical techniques. Therefore, optimizing radio frequency (RF) coils to improve se...
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Although NMR has the ability to investigate biological systems non-destructively, it suffers from low sensitivity compared to other analytical techniques. Therefore, optimizing radio frequency (RF) coils to improve sensitivity is an area of significant focus in NMR Sensitivity can be improved for mass- and volume-limited samples by reducing, coil diameter, and adding sensing layers to the coil. This paper demonstrates that around skin depth, coil sensitivity can be increased with additional sensing layers, by using multilayered scroll coil geometries. While solenoids have demonstrated increased sensitivity over conventional coils (Helmholtz, Saddle, and Birdcage), their dimensions are limited by wire diameter, and difficulty in fabrication at reduced dimensions. The novel scroll geometry avails of microfabrication techniques to provide flexibility in manufacturing coils at very reduced dimensions.
Presents a model for Raman microscopic images. The model describes the degradation of Raman signals by non-uniform illumination, by the microscopic system, and by additive signal-dependent Gaussian noise. Using this m...
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Presents a model for Raman microscopic images. The model describes the degradation of Raman signals by non-uniform illumination, by the microscopic system, and by additive signal-dependent Gaussian noise. Using this model, synthetic images were created to validate the model. Based on these synthetic images, an anisotropic diffusion filter was applied to reduce the signal-dependent Gaussian noise and at the same time not blur the objects' boundary. A Wiener filter was used to restore the blurred Raman images by the microscopic system. And, an image ratioing method was used to correct for the non-uniform illumination. After the restoration, the mean absolute error between the restored image and the true image was minimized.
Electrochemical impedance spectroscopy (EIS) is a useful means of studying physicochemical processes in electrochemical systems. However, the extraction of useful information from extracting cell equivalent circuit pa...
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Composites of thermally sensitive hydrogels and optically active nanoparticles have been developed for the purpose of photothermally modulated drug delivery. Copolymers of N -isopropylacrylamide (NIPAAm) and acrylamid...
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A theoretical model was developed to study the degradation of highly porous scaffolds containing growth factors. The use of such bioactive agents has been proposed to induce and maintain differentiated cell function i...
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A theoretical model was developed to study the degradation of highly porous scaffolds containing growth factors. The use of such bioactive agents has been proposed to induce and maintain differentiated cell function in bioartificial constructs. Simulation results showed that the total porosity of the scaffolds and the average pore size have significant effects on degradation rates, and consequently, on the release pattern of the growth factor. The release rates also depended on the erosion mechanism, with bulk erosion resulting in more uniform release rates of the growth factor.
We report the development of a model that describes the dynamic behavior of a population of cells that migrate and proliferate to fill a three-dimensional scaffold. This model is then applied to study how cell migrati...
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We report the development of a model that describes the dynamic behavior of a population of cells that migrate and proliferate to fill a three-dimensional scaffold. This model is then applied to study how cell migration and the density or spatial distribution of seed cells affect the tissue growth rates.
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