The packings and defects of the strongly coupled two-dimensional Coulomb clusters with particle number N from a few to a few hundred with different forms of mutual repulsion and central confining potentials at zero temperature are investigated using molecular-dynamics simulation through many annealing cycles. The circular symmetry of the confining potential and the interplay with the mutual repulsion lead to the strong competition between the outer circular shells and the inner triangular lattice. Generic packing behaviors, such as the concentric shells with the classical periodic packing sequence at small N, and the triangular latticelike inner core surrounded by a few outer circular shells at large N are observed. The effects of changing the interaction and confining potentials on the detailed packing sequence, the radial variation of packing density, and the positions of the shell-triangular core interface are investigated with a detailed study of the cluster structures along with the formation and distribution of topological defects.

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When compared to the two well-known conventional NR techniques under challenging listening condition, the proposed NC + DDAE NR approach has superior noise suppression capabilities and gives less distortion for the key speech envelope information, thus, improving speech recognition more effectively for Mandarin CI recipients. The results suggest that the proposed deep learning-based NR approach can potentially be integrated into existing CI signal processors to overcome the degradation of speech perception caused by noise.

Background Pure-tone screening (PTS) is considered as the gold standard for hearing screening programs in school-age children. Mobile devices, such as mobile phones, have the potential for audiometric testing. Objective This study aimed to demonstrate a new approach to rapidly screen hearing status and provide stratified test values, using a smartphone-based hearing screening app, for each screened ear of school-age children. Method This was a prospective cohort study design. The proposed smartphone-based screening method and a standard sound-treated booth with PTS were used to assess 85 school-age children (170 ears). Sound-treated PTS involved applying 4 test tones to each tested ear: 500 Hz at 25 dB and 1000 Hz, 2000 Hz, and 4000 Hz at 20 dB. The results were classified as pass (normal hearing in the ear) or fail (possible hearing impairment). The proposed smartphone-based screening employs 20 stratified hearing scales. Thresholds were compared with those of pure-tone average (PTA). Results A total of 85 subjects (170 ears), including 38 males and 47 females, aged between 11 and 12 years with a mean (SD) of 11 (0.5) years, participated in the trial. Both screening methods produced comparable pass and fail results (pass in 168 ears and fail in 2 ears). The smartphone-based screening detected moderate or worse hearing loss (average PTA>25 dB) accurately. Both the sensitivity and specificity of the smartphone-based screening method were calculated at 100%. Conclusions The results of the proposed smartphone-based self-hearing test demonstrated high concordance with conventional PTS in a sound-treated booth. Our results suggested the potential use of the proposed smartphone-based hearing screening in a school-age population.

The defect excitation and nonuniform melting of a two-dimensional Coulomb cluster with 300 charged particles (interacting with 1/r type force) in a uniform neutralizing background are studied numerically. Intrinsic defects exist around the outer circular shells surrounding the inner triangular lattice. They are the source regions for anisotropic particle thermal vibrations and then cyclic hoppings with the increasing temperature. It leads to the nonuniform melting associated with the thermal motion of intrinsic defects, and then the thermal excitation of dislocation pairs and disclinations. The intrinsic defect free center core has the highest melting temperature. It shows the sequential losses of translational and then orientational orders.