ABSTRACT
Spectral fingerprints of molecules are mostly accessible in the terahertz (THz) and mid-infrared ranges, such that efficient molecular-detection technologies rely on broadband coherent light sources at such frequencies. If THz Quantum Cascade Lasers can achieve octave-spanning bandwidth, their tunability and wavelength selectivity are often constrained by the geometry of their cavity. Here we introduce an adaptive control scheme for the generation of THz light in Quantum Cascade Random Lasers, whose emission spectra are reshaped by applying an optical field that restructures the permittivity of the active medium. Using a spatial light modulator combined with an optimization procedure, a beam in the near infrared (NIR) is spatially patterned to transform an initially multi-mode THz random laser into a tunable single-mode source. Moreover, we show that local NIR illumination can be used to spatially sense complex near-field interactions amongst modes. Our approach provides access to new degrees of freedom that can be harnessed to create broadly-tunable sources with interesting potential for applications like self-referenced spectroscopy.
ABSTRACT
The article Hearing preservation in children with electric-acoustic stimulation after cochlear implantation-Outcome after electrode insertion with minimal insertion trauma, written by T. Rader, A. Bohnert, C. Matthias, D. Koutsimpelas, MA. Kainz, S. Strieth was originally published electronically.
ABSTRACT
BACKGROUND: Cochlear implantation in patients with functional residual low-frequency hearing is performed according to an established hearing-preserving surgical technique in order to cause minimal trauma of inner ear structures. Due to the increasing number of cochlear implants in children, the preservation of residual hearing is becoming increasingly important in this patient collective. OBJECTIVES: Short- and mid-term hearing preservation outcome in pediatric patients is investigated. MATERIALS AND METHODS: A group of 9 children (12 ears) between 5 and 12 years of age were examined after hearing-assisted cochlear implantation with respect to the pure tone audiometric thresholds. Retrospectively, short-term hearing preservation (up to 3 months after surgery) was examined. In a subgroup of 5 children, mid-term hearing preservation (7.5 to 16 months after surgery) was also analyzed. The mean values of hearing preserved (HL%) and hearing loss (HL) due to electrode insertion were calculated as measured values. RESULTS: In the whole group, the mean values of the preoperative PTAlow were 29.8â¯dB and the short-term postoperative PTAlow 42.6â¯dB. The mean value of the HL% was 73.6%, corresponding to an HL of 9.4â¯dB. In the subgroup, the mean PTAlow postoperatively was 46.0â¯dB in the mid-term and the HL% at 80.7% with a HL of 6.6â¯dB. CONCLUSIONS: The results in children are consistent with the results in adults. Electric-acoustic stimulation (EAS) should be used in the treatment of children with existing low-frequency residual hearing, as good residual hearing preservation can also be achieved in children after implantation.
Subject(s)
Auditory Threshold , Cochlear Implantation , Cochlear Implants , Speech Perception , Acoustic Stimulation , Adult , Audiometry, Pure-Tone , Child , Child, Preschool , Electrodes, Implanted , Female , Humans , Male , Retrospective Studies , Treatment OutcomeABSTRACT
BACKGROUND: Cochlear implantation in patients with functional residual low-frequency hearing is performed according to an established hearing-preserving surgical technique in order to cause minimal trauma of inner ear structures. Due to the increasing number of cochlear implants in children, the preservation of residual hearing is becoming increasingly important in this patient collective. OBJECTIVES: Short- and mid-term hearing preservation outcome in pediatric patients is investigated. MATERIALS AND METHODS: A group of 9 children (12 ears) between 5 and 12 years of age were examined after hearing-assisted cochlear implantation with respect to the pure tone audiometric thresholds. Retrospectively, short-term hearing preservation (up to 3 months after surgery) was examined. In a subgroup of 5 children, mid-term hearing preservation (7.5 to 16 months after surgery) was also analyzed. The mean values of hearing preserved (HL%) and hearing loss (HL) due to electrode insertion were calculated as measured values. RESULTS: In the whole group, the mean values of the preoperative PTAlow were 29.8â¯dB and the short-term postoperative PTAlow 42.6â¯dB. The mean value of the HL% was 73.6%, corresponding to an HL of 9.4â¯dB. In the subgroup, the mean PTAlow postoperatively was 46.0â¯dB in the mid-term and the HL% at 80.7% with a HL of 6.6â¯dB. CONCLUSIONS: The results in children are consistent with the results in adults. Electric-acoustic stimulation (EAS) should be used in the treatment of children with existing low-frequency residual hearing, as good residual hearing preservation can also be achieved in children after implantation.
