Heavy metal glasses doubly doped with Yb3＋ and Ln3＋ ions （Ln=Er or Tm） were studied. Glass host matrices were limited to lead borate glass and lead germanate glass. Efficient resonant （yb3＋-Er3＋） and ...non-resonant （yb3＋-Tm3＋） energy transfer was ob- served for the studied systems. Near-infrared luminescence spectra at 1.53 μm （Er3＋） and 1.9 gm （Tm3＋） were detected under excita- tion of Yb3＋ by 975 nm diode laser line. They corresponded to 4I13/2→4115/2 （Er3＋） and 3F4→3H6 （Tm3＋） transitions of rare earth ions, respectively. The unusual large spectral linewidth nearly close to 110 nm for 4I13/2→4I15/2 transition of Er3＋ ions in lead borate glass was obtained, whereas long-lived near-infrared luminescence at 1.53 gm was detected in lead germanate glass. Quite different situa- tion was observed for yb3＋-Tm3＋ doubly doped glasses. In contrast to lead borate glass, near-infrared （3F4→3H6） luminescence spectra were registered for Tm3＋ ions in lead germanate glasses, only. These phenomena strongly depended on stretching vibrations of glass host, which was confirmed by FT-IR spectroscopy.
Histopathology of Cochlear Implants in Humans Nadol, Joseph B.; Burgess, Barbara J.; Gantz, Bruce J. ...
Annals of otology, rhinology & laryngology,
09/2001, Letnik:
110, Številka:
9
Journal Article
Recenzirano
The insertion of an intrascalar electrode array during cochlear implantation causes immediate damage to the inner ear and may result in delayed onset of additional damage that may interfere with ...neuronal stimulation. To date, there have been reports on fewer than 50 temporal bone specimens from patients who had undergone implantation during life. The majority of these were single-channel implants, whereas the majority of implants inserted today are multichannel systems. This report presents the histopathologic findings in temporal bones from 8 individuals who in life had undergone multichannel cochlear implantation, with particular attention to the type and location of trauma and to long-term changes within the cochlea. The effect of these changes on spiral ganglion cell counts and the correlation between speech comprehension and spiral ganglion cell counts were calculated. In 4 of the 8 cases, the opposite, unimplanted ear was available for comparison. In 3 of the 4 cases, there was no significant difference between the spiral ganglion cell counts on the implanted and unimplanted sides. In addition, in this series of 8 cases, there was an apparent negative correlation between residual spiral ganglion cell count and hearing performance during life as measured by single-syllable word recognition. This finding suggests that abnormalities in the central auditory pathways are at least as important as spiral ganglion cell loss in limiting the performance of implant users.
Abstract Inferring the distribution and abundance of a species from field records must deal with false‐negative and false‐positive errors. False‐negative errors occur if a species present goes ...undetected, while false‐positive errors are typically a consequence of species misidentification. False‐positive observations in studies of rare species may cause an overestimation of the distribution or abundance of the species and distort trend indices. We illustrate this issue with the monitoring of the E urasian lynx in the A lps. We developed a three‐level classification of field records according to their reliability as inferred from whether they were validated or not. The first category ( C 1) represents ‘hard fact’ data (e.g. dead lynx); the second category ( C 2) includes confirmed data (e.g. tracks verified by an expert); and the third category ( C 3) are unconfirmed data (e.g. any kind of direct visual observation). For lynx, which is a comparatively well‐known species in the A lps, we use site‐occupancy modelling to estimate its distribution and show that the inferred lynx distribution is highly sensitive to presence sign category: it is larger if based on C 3 records compared with the more reliable C 1 and C 2 records. We believe that the reason for this is a fairly high frequency of false‐positive errors among C 3 records. This suggests that distribution records for many lesser‐known species may be similarly unreliable, because they are mostly or exclusively based on unconfirmed and thus soft data. Nevertheless, such soft data form a considerable part of species assessments as presented, for example in the I nternational U nion for C onservation of N ature R ed L ist. However, C 3 records can often not be discarded because they may be the only information available. When inferring the distribution of rare carnivores, especially for species with an expanding or shrinking range, we recommend a rigorous discrimination between fully reliable and un‐ or only partly reliable data, in order to identify possible methodological problems in the distribution maps related to false‐positive records.
The development of a vestibular implant for the rehabilitation of bilateral vestibular loss is funded on a concept comparable to that of the cochlear implant used in the rehabilitation of bilateral ...deafness. This paper carries an overview of the main aspects of such a development and describes the first experiments done in human subjects in Geneva.
We assess how the properties of technology affect structural transformation, i.e., the reallocation of production factors across the broad sectors of agriculture, manufacturing, and services. To this ...end, we estimate sectoral constant elasticity of substitution (CES) and Cobb-Douglas production functions on postwar US data. We find that differences in technical progress across the three sectors are the dominant force behind structural transformation whereas other differences across sectoral technology are of second-order importance. Our findings imply that Cobb-Douglas sectoral production functions that differ only in technical progress capture the main technological forces behind the postwar US structural transformation.
A technique for simulation of concentrated solutions and melts of spherical micelles composed of diblock copolymers is presented; the degrees of polymerization of blocks are 20 and 80, respectively. ...The concentration of solutions is varied in a wide range up to 67 vol %, which corresponds to the dense packing of spheres in the volume-centered lattice. It is shown that, at all the values of the Flory–Huggins parameter, such inverted phases are instable and fairly rapidly transformed into more equilibrated phases without any long-range order.
In this work microphase separation in ideal interpenetrating networks as well as its influence on the mechanical properties of the networks has been studied. Structures with long-range order in such ...networks have not been found to be formed; the reason for this is apparently the weak bonding (physical entanglements) between the subnetworks. The dynamics of the relaxation of interpenetrating networks with highly incompatible subnetworks has been studied and it has been found that the slow rearrangement of phase boundaries during the stretching process has a significant influence on it. Using the analysis of subchains conformations, it has been found that the increase in the stiffness of interpenetrating networks with incompatible subchains occurs due to the irregular tension of subchains related to the presence of big aggregates in the system.
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