Experimental studies are made of chaotic particle motion in a simple Stokes flow system. Surfaces-of-section that exhibit a generic mixture of regular and chaotic particle motions in good agreement with computer simulations are constructed experimentally. Deformations of line elements exhibit ‘ whorl ’ and ‘ tendril ’ structures of great complexity that can be correlated directly with the underlying particle dynamics and that agree well with numerical computations. In some cases, the laboratory studies are able to resolve dynamical features more accurately than the computer studies. Experiments demonstrating that the flows exhibit poor time reversal in régimes of chaotic particle motion are also performed.
Tissue modulated Raman spectroscopy was used noninvasively to measure blood glucose concentration in people with type I and type II diabetes with HemoCue fingerstick measurements being used as reference. Including all of the 49 measurements, a Clarke error grid analysis of the noninvasive measurements showed that 72% were A range, i.e., clinically accurate, 20% were B range, i.e., clinically benign, with the remaining 8% of measurements being essentially erroneous, i.e., C, D, or E range. Rejection of 11 outliers gave a correlation coefficient of 0.80, a standard deviation of 22 mg/dL with p<0.0001 for N=38 and places all but one of the measurements in the A and B ranges. The distribution of deviations of the noninvasive glucose measurements from the fingerstick glucose measurements is consistent with the suggestion that there are at least two systematic components in addition to the random noise associated with shot noise, charge coupled device spiking, and human factors. One component is consistent with the known variation of fingerstick glucose concentration measurements from laboratory reference measurements made using plasma or whole blood. A weak but significant correlation between the deviations of noninvasive measurements from fingerstick glucose measurements and the test subject's hemoglobin concentration was also observed.
The log normal distribution is shown to be useful for characterizing cluster distributions produced by coalescence growth mechanisms. The Smoluchowski equation and variations thereof produce cluster size distributions very similar to those produced using nozzle beam expansions and laser chemistry of organometallics. The model provides a statistically unbiased basis for interpreting cluster size distributions produced using a wide variety of synthetic methods. It also provides a unified chemical and physical basis for discussing and rationalizing the results of a wide range of gas phase cluster experiments. Under certain conditions, size distributions can be produced in which there is an alteration in the number of odd and even clusters produced. In addition to some inferences regarding fullerene chemistry, data gleaned from the literature are rationalized on the basis of the kinematics of cluster formation, the fractal dimension of clusters composed of different atoms, the Periodic Table, and the degree to which the translational motion of the coalescing species is diffusional or ballistic.
A simple Stokes flow problem, corresponding to an incompressible flow between two eccentric cylinders rotating alternately, is investigated numerically. It is demonstrated that for a wide range of system parameters the fluid particles can evolve along highly chaotic orbits, thereby providing an example of so called ‘‘Lagrangian turbulence.’’ Passive scalar distributions can rapidly evolve into structures of remarkable spatial complexity that can be characterized in terms of the underlying phase space dynamics. An investigation is made of the ability of simple area preserving mappings, deduced from the physical problem, to reproduce the dynamics obtained from the exact solution.
Abstract. Raman spectroscopy was used to study temporal molecular changes associated with spinal cord injury (SCI) in a rat model. Raman spectra of saline-perfused, injured, and healthy rat spinal cords were obtained and compared. Two injury models, a lateral hemisection and a moderate contusion were investigated. The net fluorescence and the Raman spectra showed clear differences between the injured and healthy spinal cords. Based on extensive histological and biochemical characterization of SCI available in the literature, these differences were hypothesized to be due to cell death, demyelination, and changes in the extracellular matrix composition, such as increased expression of proteoglycans and hyaluronic acid, at the site of injury where the glial scar forms. Further, analysis of difference spectra indicated the presence of carbonyl containing compounds, hypothesized to be products of lipid peroxidation and acid catalyzed hydrolysis of glycosaminoglycan moieties. These results compared well with in vitro experiments conducted on chondroitin sulfate sugars. Since the glial scar is thought to be a potent biochemical barrier to nerve regeneration, this observation suggests the possibility of using near infrared Raman spectroscopy to study injury progression and explore potential treatments ex vivo, and ultimately monitor potential remedial treatments within the spinal cord in vivo. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
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