The relationship between the degree of chronic middle ear inflammation and pneumatization was investigated in the pig as an animal model, since its tympanic bulla closely resembles the human mastoid air cell system. Ten piglets (sire: Landrace-Hampshire crossbreed; dam: Duroc) were used for this experiment. Four ears of two animals served as the normal control group and 16 ears of eight animals were the experimental group. In this latter group, otitis media was induced by injecting glycerin into the middle ear clefts 1 months after birth, and the degree of inflammation was varied by administering or withholding antibiotics (cefamandole and dibekacin) and adjusting the dosage regimen. The animals were sacrificed 6 months after birth and examined for the relationship between the degree of chronic middle ear inflammation present and tympanic bulla pneumatization. Various degrees of inflammation were successfully induced by injecting the antibiotics: the more severe the inflammation found, the greater was the inhibition of pneumatization. Findings demonstrated that the degree of inhibition of pneumatization produced was directly proportional to the severity of chronic middle ear inflammation.
The utilization of drones as flying base stations (BSs) in the sixth-generation (6G) cellular networks has attracted much attention recently. In this context, free-space optical (FSO) systems could be deployed to provide high-capacity fronthaul/backhaul links between drones and ground BSs. Particularly, a drone-to-ground FSO communication link can be established by equipping the drone with a modulating retro-reflector (MRR) to modulate the incoming optical beam and reflect the modulated beam back along the same path. This helps to alleviate stringent pointing requirements from the drone while satisfying the limited size, weight, and power (SWaP) consumption requirements. Nevertheless, the underlying physical channel effects of this aerial retro-reflected FSO system have never been experimentally explored in the literature. In this paper, we report, for the first time, the experimental channel statistics of a drone-to-ground retroreflected FSO link, offering practical insights into the angle-of-arrival (AoA) fluctuations at the receiver, the channel coherence time, the probability of fade, the level crossing rate, the average fade duration, and the time-frequency channel characteristics. Our results are expected to serve as practical sources of reference for the theoretical performance analyses and engineering designs of drone-based retro-reflected FSO systems.INDEX TERMS Free-space optics (FSO), unmanned aerial vehicles (UAVs), aerial fronthaul/backhaul links, drone hovering, fine-tracking systems.
To examine whether gas exchange occurs in the middle ear air cell system independent of the eustachian tube (ET), we occluded the middle ear clefts of piglets, whose tympanic bullae closely resemble the human mastoid air cell system, and investigated subsequent changes in the air cell system. We anticipated that pneumatization and development of the air cell system would continue if gas were exchanged through the mucosa lining the air cell system. If, on the other hand, mastoid air cells depend on the ET, mastoid development would be impaired or arrested. In noninflamed ears, pneumatization was maintained, and development of the air cell system continued after the middle ear cleft had been occluded with an acrylate adhesive and the bullar air cell system was thus excluded from any communication with the ET. These results indicate that the normal middle ear air cell system has the capacity to perform gas exchange independently of the ET, with gas exchange appearing to occur through the submucosal capillary network.
A segmented coplanar waveguide (SCPW) is presented in this paper to improve the propagation characteristics of on-body communication. The SCPW is connected electromagnetically by two half-wavelength resonators arranged on both sides of the center line. The resonators provide the function to couple the SCPW with the top and bottom antennas at arbitrary positions along the line, which is a unique feature of the proposed geometry. The basic performance of the SCPW was confirmed at 5.12 GHz by a thin dielectric substrate and at 2.45 GHz by a flexible paper substrate with a silver-ink conductor. The propagation loss is reduced more than 20dB by this SCPW in on-body communication between abdomen and back sides, which is confirmed by the measurement using a phantom.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.