To compare the difference in electrode impedance across discrete time points to 24 months post-activation for two groups of adult cochlear implant recipients, one using an investigational ...perimodiolar (Contour Advance®) array augmented with 40% concentration weight per weight (w/w) dexamethasone (the Drug Eluting Electrode, ‘DEE’ Group), and the other the commercially available Contour Advance (’Control’ Group).
Ten adult subjects were implanted with the DEE and fourteen with the Control. Electrode impedances were measured intra-operatively, one-week post-surgery, at initial activation (approximately two-weeks post-surgery), and at approximately one, three, six, 12 and 24 months post-activation. Two different impedance measurements were obtained: 1) in MP1+2 mode using Custom Sound programming software; and 2) 4-point impedance measures utilising BP+2 stimulation mode with recording on non-stimulating electrodes. Data were analysed with respect to both impedance averaged across all electrodes, and impedance for electrodes grouped into basal, middle and apical sections.
Group mean MP1+2 impedance for the DEE was significantly lower than for the Control at all post-operative time points examined, and for each of the basal, middle and apical cochlear regions. Group mean 4-point impedance was significantly lower for the DEE than the Control in the basal region at six, 12 and 24 months post-activation and in the middle region at 12- and 24-months post-activation. The pattern of change in MP1+2 impedance differed significantly in the early post-operative period prior to device activation. A significant 4.8 kOhm reduction in impedance between surgery and one-week was observed for the DEE group but not for the Control. A 2.0 kOhm increase between the one and two week post-operative time points was observed for the Control but not for the DEE group.
While rates of adoption of different surgical approaches differed between the groups and this may have had a confounding effect, the results suggest that passive elution of dexamethasone from the investigational device was associated with a change in the intracochlear environment following surgical implantation of the electrode array, as evidenced by the lower electrode impedance measures.
•The dexamethasone eluting electrode array provided sustained lower electrode impedance measures compared to the control group.•The pattern of change in both standard MP1+2 and 4-point impedance measures varied by cochlear region and by device groups.•Impedance increases on basal electrodes after 3 months was mediated by the early delivery of dexamethasone.
The hourly production of postpollination drops in the ovules of three hybrid larch trees (Larix x. marschlinsii Coaz) was examined and compared with the measured diurnal pattern of xylem water ...potential of the same trees under non-stressed conditions during two reproductive seasons. There was no consistent relationship between xylem water potential and ovular drop production in hybrid larch. Individual trees that showed a diurnal drop production in one year did not follow a similar pattern the other year. One tree produced drops in over half of its ovules hourly, regardless of the measured xylem water potential. Variation in number of drops produced per ovule and drop mass was observed between the three trees both years, and between years for two of the trees. This variation was not in response to xylem water potential or environmental conditions. Here we report the first simultaneous measurements of branch water status and the production of ovular secretions for any conifer. We conclude that the postpollination drop production of hybrid larch is not regulated by a tree's overall water status, but is under the control of localized structures such as the cone or the ovule.
Using an empirical model for the density of states functions associated with hydrogenated amorphous silicon, with defect states taken into account, we examine how the distributions of such states ...shape the optical response of this material. The contributions to this response attributable to the various types of optical transitions are also determined. Finally, we demonstrate that we are able to capture the spectral dependence of the optical absorption coefficient associated with a defect absorption influenced sample of hydrogenated amorphous silicon using our empirical formalism for the density of states functions associated with this material.
Intact phycobilisomes from a wild-type red Chondrus crispus and its vegetatively derived green mutant were isolated by centrifugation through a discontinuous sucrose density gradient. Pigment ...composition was subsequently characterized by spectrophotometry. Vegetative thalli of the two strains grown together for six months in the laboratory resulted in different pigment profiles. Two pigmented phycobilisome bands appeared in the sucrose gradient of the wild-type alga, a purple coloured one, and a pink one, whereas only a single blue band appeared in the gradient of the green mutant. Spectrophotometric and fluorescence analyses identified the phycobiliprotein composition of the purple band as the typical phycoerythrin-phycocyanin-allophycocyanin complement in the wild-type, but there was no detectable phycoerythrin present in the blue band of the green mutant. Sodium dodecyl sulphate, preparative polyacrylamide gel electrophoresis analysis confirmed the presence of allophycocyanin subunits in all extracts, but firm evidence of an R-phycoerythrin linker polypeptide in the blue band was missing. These results highlight the ability of C. crispus to adapt to a phycoerythrin deficiency by adjusting light harvesting pigment ratios.
Intact phycobilisomes from a wild-type red Chondrus crispus and its vegetatively derived green mutant were isolated by centrifugation through a discontinuous sucrose density gradient. Pigment ...composition was subsequently characterized by spectrophotometry. Vegetative thalli of the two strains grown together for six months in the laboratory resulted in different pigment profiles. Two pigmented phycobilisome bands appeared in the sucrose gradient of the wild-type alga, a purple coloured one, and a pink one, whereas only a single blue band appeared in the gradient of the green mutant. Spectrophotometric and fluorescence analyses identified the phycobiliprotein composition of the purple band as the typical phycoerythrin-phycocyanin-allophycocyanin complement in the wild-type, but there was no detectable phycoerythrin present in the blue band of the green mutant. Sodium dodecyl sulphate, preparative polyacrylamide gel electrophoresis analysis confirmed the presence of allophycocyanin subunits in all extracts, but firm evidence of an R-phycoerythrin linker polypeptide in the blue band was missing. These results highlight the ability of C. crispus to adapt to a phycoerythrin deficiency by adjusting light harvesting pigment ratios. PUBLICATION ABSTRACT
A number of empirical models for the valence band and conduction band hydrogenated amorphous silicon density of states functions are presented. Then, a relationship between these density of states ...functions and the imaginary part of the dielectric function is developed. The joint density of states function, which plays a key role in determining the spectral dependence of the imaginary part of the dielectric function, and is directly related to the valence band and conduction band density of states functions, is defined in the process. Joint density of states results, corresponding to a specific empirical density of states model, are then presented. Finally, the modeling results for the imaginary part of the dielectric function are contrasted with those of experiment and satisfactory agreement is found.
Objectives: To determine whether ciprofloxacin retains its antimicrobial activity after storage with Healon at ambient temperature and at 37°C over 5 weeks and then to establish whether the ...application of ciprofloxacin/Healon onto scala tympani electrode arrays reduces the risk of meningitis in implanted rats inoculated with S. pneumoniae.
Study Design: In vitro laboratory and in vivo animal studies
Methods: The antibacterial activity of three concentrations of ciprofloxacin/Healon (7.5, 75, and 750 μg/mL) was examined over 5 weeks at both ambient temperature (23°C) and body temperature (37°C). Thirty‐six rats (18 implanted with ciprofloxacin 750 mg/mL/Healon‐coated electrode array and 18 without the coating) were infected with S. pneumoniae 4 weeks after implantation by way of three different routes of infection (hematogenous, middle ear, and inner ear) and observed for the development of meningitis.
Results: The antibacterial activity of ciprofloxacin/Healon was maintained over 5 weeks at both 23°C and 37°C. The implanted rats with the ciprofloxacin/Healon‐coated electrode array were protected from meningitis when the bacteria were given by way of the hematogenous route (Fisher's exact test, P = .008) but not when the bacteria were inoculated directly into the middle or inner ear. However, the time to develop meningitis was significantly longer in rats implanted with a coated array, irrespective of the route of inoculation (P < .05, log rank test).
Conclusion: Our animal model demonstrated that a ciprofloxacin‐coated electrode array can protect healthy implanted rats from meningitis when the route of infection is hematogenous and can delay the onset of meningitis when bacteria are inoculated directly into the middle or inner ear.
It is desirable to automatically classify data samples for the assessment of quantitative performance of users of haptic devices as the haptic data volume may be much higher than is feasible to ...manually annotate. In this paper we compare the use of three k-metrics for automated classifaction of human motion: cosine, extrinsic curvature and symmetric centroid deviation. Such classification algorithms make predictions about data attributes, whose quality we assess via three mathematical methods of comparison: root mean square deviation, sensitivity error and entropy correlation coefficient. Our assessment suggests that k-cosine might be more promising at analysing haptic motion than our two other metrics.
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