Tomographic images of human dentin and enamel are obtained using OCT and polarization sensitive OCT. Strong birefringence effect is detected in enamel. Light propagation along dentinal tubules is also observed. Index ...
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Describes a Markov state model for a cloned potassium channel of the human heart (I/sub K/spl nu/LQT1/). The parameters of the model are determined by a least-squares fit of predicted vs. measured data. The fitting pr...
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Describes a Markov state model for a cloned potassium channel of the human heart (I/sub K/spl nu/LQT1/). The parameters of the model are determined by a least-squares fit of predicted vs. measured data. The fitting process is achieved by using the "SPSA" optimizer to sequentially choose trial values of the parameters. At each choice of parameter value, a loss function is computed by simulating the action of the channel at that trial parameter value. When the optimizer has converged, the parameter value represents the best fit.
A technique has been developed that allows the application of free-standing membranes of polymer adhesives used in microfabricated structures. The film is made free-standing by the application of the adhesive to a pol...
A technique has been developed that allows the application of free-standing membranes of polymer adhesives used in microfabricated structures. The film is made free-standing by the application of the adhesive to a polymer template, followed by an adhesion step to a microfabricated substrate, and the final release of the film by the removal of the polymer template. It was found that the surface treatment used to treat the Teflon template made it adhere too strongly to the adhesive film for this application. The results show that Gel-Paks make a suitable template for the transference of polymer films over holes of at least micron size.
Charge density waves (CDW) in a tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) single crystal have been studied with molecular resolution using a low temperature scanning tunneling microscope (STM). For the fi...
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Charge density waves (CDW) in a tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) single crystal have been studied with molecular resolution using a low temperature scanning tunneling microscope (STM). For the first time the periodicities of the CDW along both the a and b axes have been observed and were found to be coincident with those of the 2kF CDW. The influence of crystal singularities on the ordering of the CDW along the a axis was also revealed.
Teleost embryos have not been successfully cryopreserved. To formulate successful cryopreservation protocols, the distribution and cellular permeability to water must be understood. In this paper, the zebrafish ( Brac...
Advances in neural probe technology are currently hindered by a lack of understanding of the cues and mechanisms responsible for rejection and isolation of probes implanted in the central nervous system. To gain addit...
Advances in neural probe technology are currently hindered by a lack of understanding of the cues and mechanisms responsible for rejection and isolation of probes implanted in the central nervous system. To gain additional insight into this topic, the attachment of astrocytes on nanoscale textured silicon surfaces was investigated. Silicon surfaces were textured using a reactive ion etch process designed to produce nanometer-scale columnar structures in silicon (“silicon grass”). Standard photolithographic techniques were used to pattern the surface thereby allowing selective modification of the surface texture by a wet chemical etch for silicon. The resulting surface allowed a side-by-side presentation of different surface textures to cells grown in culture. The silicon surfaces were characterized by scanning electron microscopy (SEM) and scanning Auger electron microscopy. The cell attachment and morphology were observed with laser scanning confocal microscopy and SEM. Transformed astrocytes from a continuous cell line showed a preference for wet-etched regions over grassy regions. In contrast, primary cortical astrocytes from neonatal rats showed a preference for silicon grass over the wet-etched surface. For the transformed astrocytes cells, the degree of response was continuous with the degree of wet-etch modification.
A high-resolution time-frequency distribution is applied to the study of violin vibrato. Our analysis indicates that the frequency modulation induced by the motion of the stopped finger on the string is accompanied by...
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The development of transducer arrays for high frequency medical imaging is complicated by the extremely small dimensions of the array elements. For example, a 50 MHz linear phased array requires a center to center ele...
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The development of transducer arrays for high frequency medical imaging is complicated by the extremely small dimensions of the array elements. For example, a 50 MHz linear phased array requires a center to center element spacing of only 15 /spl mu/m. Fabricating an array with these dimensions is difficult using conventional technology. A split aperture design that permits much larger element spacing (3-4 times) while avoiding the formation of grating lobes is described. The 3D radiation pattern of a 2.0/spl times/1.4 mm, 50 MHz split aperture phased array with 32 transmit elements and 32 receive elements was evaluated theoretically. The array was designed using a passive lens in the elevation direction focussed at 7.5 mm and a fixed transmit focal distance in the azimuthal direction focussed at 5.0 mm. Grating lobes in the azimuthal direction were suppressed by 60 dB over the range from 5.0 to 9.0 mm.
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