Electrode array design determines scalar position, dislocation rate and angle and postoperative speech perception

Purpose The aim of this study is to examine the scalar dislocation rate in straight and perimodiolar electrode arrays in relation to cochlear morphology. Furthermore, we aim to analyze the specific dislocation point of electrode arrays depending on their design and shape and to correlate these results to postoperative speech perception. Methods We conducted a comparative analysis of patients (ears: n = 495) implanted between 2013 and 2018 with inserted perimodiolar or straight electrode arrays from Cochlear™ or MED-EL. CBCT (cone beam computed tomography) was used to determine electrode array position (scalar insertion, intra-cochlear dislocation, point of dislocation and angular insertion depth). Furthermore, cochlear morphology was measured. The postoperative speech discrimination was compared regarding electrode array dislocation, primary scalar insertion and angular insertion depth. Results The electrode array with the highest rate of primary SV insertions was the CA; the electrode array with the highest rate of dislocations out of ST was the FlexSoft. We did not find significantly higher dislocation rates in cochleostomy-inserted arrays. The angle of dislocation was electrode array design-specific. A multivariate nonparametric analysis revealed that the dislocation of the electrode array has no significant influence on postoperative speech perception. Nevertheless, increasing angular insertion depth significantly reduced postoperative speech perception for monosyllables. Conclusion This study demonstrates the significant influence of electrode array design on scalar location, dislocation and the angle of dislocation itself. Straight and perimodiolar electrode arrays differ from each other regarding both the rate and place of dislocation. Insertion via cochleostomy does not lead to increased dislocation rates in any of the included electrode arrays. Furthermore, speech perception is significantly negatively influenced by angular insertion depth.

Evaluation and Delineation of Sulfur Groundwater Leakages Using Electrical Resistivity Techniques in Hit Area, Western Iraq

Electrical resistivity methods are one of the powerful methods for the detection and evaluation of shallower geophysical properties. This method was carried out at Hit area, western Iraq, in two stages; the first stage involved the use of 1Dimensional Vertical Electrical Sounding (VES) technique in three stations using Schlumberger array with maximum current electrodes of 50m. The second stage included the employment of two dimension (2D) resistivity imaging technique using dipole-dipole array with a-spacing of 4m and n-factor of 6 in two stations. The 1D survey showed good results in delineating contaminated and clear zones that have high resistivity contrast. Near the main contaminated spring, the 2D resistivity imaging technique was applied in four sections length (100 m) using a dipole-dipole array position coincided with the three points VES. We compared the results of the interpretation of imaging the techniques 2D and VES. We found that the 2D imaging resistivity technique was better than VES survey in determining the distribution of pollution under the surface in the area surveyed. It was also found that the polluted water is located about 5 m below the surface. The largest amount of leakage was found towards the northeast and coincided with the direction of the groundwater movement. Spring water has leaked from outside the region through the Kubaisah area. Most of this water is contained in quaternary deposits and karst gypsum fractures.

Radiological evaluation of a new straight electrode array compared to its precursors

Objective The aim of this study is to examine electrode array coverage, scalar position and dislocation rate in straight electrode arrays with special focus on a new electrode array with 26 mm in lengths. Study design Retrospective study. Setting Tertiary academic center. Patients 201 ears implanted between 2013 and 2019. Main outcome measures We conducted a comparative analysis of patients implanted with lateral wall electrode arrays of different lengths (F24 = MED-EL Flex24, F26 = MED-EL Flex26, F28 = MED-EL Flex28 and F31.5 = MED-EL FlexSoft). Cone beam computed tomography was used to determine electrode array position (scala tympani (ST) versus scala vestibuli (SV), intracochlear dislocation, position of dislocation and insertion angle). Results Study groups show no significant differences regarding cochlear size which excludes influences by cochlear morphology. As expected, the F24 showed significant shorter insertion angles compared to the longer electrode arrays. The F26 electrode array showed no signs of dislocation or SV insertion. The electrode array with the highest rate of ST dislocations was the F31.5 (26.3%). The electrode array with the highest rates of SV insertions was the F28 (5.75%). Most of the included electrode arrays dislocate between 320° and 360° (mean: 346.4°; range from 166° to 502°). Conclusion The shorter F24 and the new straight electrode array F26 show less or no signs of scalar dislocation, neither for round window nor for cochleostomy insertion than the longer F28 and the F31.5 array. As expected, the cochlear coverage is increasing with length of the electrode array itself but with growing risk for scalar dislocation and with the highest rates of dislocation for the longest electrode array F31.5. Position of intracochlear dislocation is in the apical cochlear part in the included lateral wall electrode arrays.

Assessment of Temperature Effects in Interior Orientation Parameters Calibration of Optoelectronic Devices

A digital micromirror device (DMD) micromirrors periodic spatial structure is a measuring scale in interior orientation parameters calibration of optoelectronic devices problems, when using a DMD as a testobject. It is important that DMD micromirrors periodic spatial structure remains constant. Change in a DMD micromirrors spatial structure may occur due to heating. In addition to heating a DMD, an optoelectronic device photodetector is also subject to heating and, accordingly, change in its spatial structure. It is necessary to estimate change in a spatial structure of DMD micromirrors and an optoelectronic device photodetector.A DMD micromirrors spatial drift and a DMD micromirrors spatial drift together with a digital camera photodetector pixels spatial drift for operation 4 h are analyzed. The drift analysis consisted in the points array position assessing formed by a DMD and projected onto a digital camera. When analyzing only a DMD micromirrors drift, a digital camera was turned on only for shooting time for exclude digital camera influence. A digital camera did not have time to significantly heat up, during this time. After a digital camera it cooled to a room temperature.Average drift of all DMD micromirrors determines the accuracy of interior orientation parameters calibration of optoelectronic devices using a DMD in time. Maximum drift of all micromirrors after switching on is observed. Minimum DMD warm-up time is 60 min for average drift of all micromirrors less than 1 μm is necessary. Minimum DMD warm-up time is 120 min when using a DMD together with a digital camera is necessary.A DMD expansion uniformity determines the accuracy of interior orientation parameters calibration of optoelectronic devices using a DMD, because irregular expansion disturbs micromirrors periodicity. The average change in distance of neighboring points is less than 0.1 μm for every 20 min.Thus, a DMD can be used as a test-object in interior orientation parameters calibration of optoelectronic devices. The results can be used as compensation coefficients of change in DMD micromirrors spatial structure due to temperature effects during operation, if more accurate are necessary.

Denoising Algorithm for the FY-4A GIIRS Based on Principal Component Analysis

The Geostationary Interferometric Infrared Sounder (GIIRS) is the first high-spectral resolution advanced infrared (IR) sounder onboard the new-generation Chinese geostationary meteorological satellite FengYun-4A (FY-4A). The GIIRS has 1650 channels, and its spectrum ranges from 700 to 2250 cm−1 with an unapodized spectral resolution of 0.625 cm−1. It represents a significant breakthrough for measurements with high temporal, spatial and spectral resolutions worldwide. Many GIIRS channels have quite similar spectral signal characteristics that are highly correlated with each other in content and have a high degree of information redundancy. Therefore, this paper applies a principal component analysis (PCA)-based denoising algorithm (PDA) to study simulation data with different noise levels and observation data to reduce noise. The results show that the channel reconstruction using inter-channel spatial dependency and spectral similarity can reduce the noise in the observation brightness temperature (BT). A comparison of the BT observed by the GIIRS (O) with the BT simulated by the radiative transfer model (B) shows that a deviation occurs in the observation channel depending on the observation array. The results show that the array features of the reconstructed observation BT (rrO) depending on the observation array are weakened and the effect of the array position on the observations in the sub-center of the field of regard (FOR) are partially eliminated after the PDA procedure is applied. The high observation and simulation differences (O-B) in the sub-center of the FOR array notably reduced after the PDA procedure is implemented. The improvement of the high O-B is more distinct, and the low O-B becomes smoother. In each scan line, the standard deviation of the reconstructed background departures (rrO-B) is lower than that of the background departures (O-B). The observation error calculated by posterior estimation based on variational assimilation also verifies the efficiency of the PDA. The typhoon experiment also shows that among the 29 selected assimilation channels, the observation error of 65% of the channels was reduced as calculated by the triangle method.