Wiener-Hammerstein model and its learning for nonlinear digital pre-distortion of optical transmitters.

We present a simple nonlinear digital pre-distortion (DPD) of optical transmitter components, which consists of concatenated blocks of a finite impulse response (FIR) filter, a memoryless nonlinear function and another FIR filter. The model is a Wiener-Hammerstein (WH) model and has essentially the same structure as neural networks or multilayer perceptrons. This awareness enables one to achieve complexity-efficient DPD owing to the model-aware structure and exploit the well-developed optimization scheme in the machine learning field. The effectiveness of the method is assessed by electrical and optical back-to-back (B2B) experiments, and the results show that the WH DPD offers a 0.52-dB gain in signal-to-noise ratio (SNR) and 6.0-dB gain in optical modulator output power at a fixed SNR over linear-only DPD.

Efficacy of the Silensor for treating obstructive sleep apnea syndrome.

INTRODUCTION: Although mandibular repositioning devices were found to be very effective for treating obstructive sleep apnea (OSAS), they can cause side effects such as temporomandibular joint disorder and occlusal deviation. A semi-rigid device with a low frequency of side effects, the Silensor, (Erkodent Gmbh, Tuttlingen, Germany) was reported previously. The purpose of this study is to determine whether the Silensor is effective for treating OSAS. MATERIALS AND METHODS: Thirty-five OSAS patients (27 males and 8 females) who were treated with the Silensor were enrolled in this study. The mean age and body mass index of the patients were 52.2 years (23-72 years) and 24.5 kg/m(2) (19.3-31.6 kg/m(2)), respectively. The patients were classified into two groups based on the length of the apparatus connector: 0-2 or 3-4 mm. A polysomnography test was performed twice, at the first visit and after the improvement of subjective symptoms. These data were statistically analyzed using the Wilcoxon signed-rank test. RESULTS: The apnea-hypopnea index significantly improved in all OSAS patients, the mild to moderate OSAS patients, severe OSAS patients, 0- to 2-mm group, and the 3- to 4-mm group (91.4 %; p < 0.01, 88.9 %; p < 0.01, 100 %; p < 0.05, 86.4 %; p < 0.01, 100 %; p < 0.01, respectively). The only side effects of the Silensor were broken apparatus and damage to the buccal mucosa. DISCUSSION: The Silensor is useful for the treatment of OSAS. In particular, the Silensor is suitable for the first phase of OSAS treatment with oral appliances because the efficacy of the Silensor was equal to that of other oral appliances and had few side effects.

Voice characteristics before versus after mandibular setback surgery in patients with mandibular prognathism using nonlinear dynamics and conventional acoustic analyses.

OBJECTIVES: The purpose of this study was to explore the voice characteristics of patients with mandibular prognathism, and to investigate the effects of mandibular setback surgery on these characteristics using nonlinear dynamics and conventional acoustic analyses. MATERIALS AND METHODS: Sixteen patients (8 males and 8 females) who had skeletal 3, class III malocclusion without cleft palate, and who underwent a bilateral sagittal split ramus osteotomy (BSSRO), were enrolled. As controls, 50 healthy adults (25 males and 25 females) were enrolled. The mean first LEs (mLE1) computed for each one-second interval, and the fundamental frequency (F0) and frequencies of the first and second formant (F1, F2) were calculated for each Japanese vowel. RESULTS AND CONCLUSIONS: The mLE1s for /u/ in males, and /o/ in females and the F2s for /i/ and /u/ in males, changed significantly after BSSRO. Class III voice characteristics were observed in the mLE1s for /i/ in both males and females, in the F0 for /a/, /i/, /u/ and /o/ in females, and in the F1 and F2 for /a/ in males, and the F1 for /u/ and the F2 for /i/ in females. Most of these characteristics were preserved after BSSRO.