800 MHz single-photon detection at 1550-nm using an InGaAs/InP avalanche photodiode operated with a sine wave gating.

Single-photon detection at 1550-nm with a high repetition rate was realized using an InGaAs/InP avalanche photodiode operated with a sine wave gating. Removing the AC noise due to the transferred gate signal usingband elimination filters, we have discriminated the avalanche signal which is much smaller than that in the conventional gating, which results in the suppression of the afterpulsing. At the repetition frequency of 800MHz, the overall afterpulsing probability was 6.0% with the detection efficiency of 8.5% and the dark count probability of 9.2X10(-6).

[Statistical study of 41 cases with denture foreign bodies in the air and food passages and significance of the duplicated denture model].

A statistical study of 41 cases with denture foreign bodies in the air and upper food passages which were treated in our department during the past 21 years was done. (1) Males were more frequently affected. The ratio of male to female was about 2 to 1. (2) Of 41 dentures, 2, 2 and 37 were lodged in the air passages, hypopharynx and esophagus respectively. (3) There were 5 complete mandibular dentures in 41 cases. (4) The causes of the denture foreign bodies were originated to the problem of denture itself in 29 cases, that of the patient himself in 2 cases and both in 10 cases. (5) Of 39 problematic dentures, 16 showed the breakage such as plate fracture and clasp deformity, but the other 23 showed no breakage. In this latter group, poor holding of the denture was ascribed to miss-making or miss-planning. (6) Of 12 patients with problems in their physical function, 5 had suffered from cerebrovascular disease and 3 from geriatric dementia. (7) The denture foreign body in aged patients with physical hypofunction tends to increase in recent years. (8) Of 39 dentures tried to remove by esophagoscopy, 18 were done with difficulty and they were detachable partial dentures with one artificial tooth and 2-arm-clasps lodged at the first and/or second isthmus of the esophagus. Though we have a denture removed successfully at the third trial, we have no case needed external esophagotomy. (9) Duplicated denture models were made in 20 cases prior to the procedure, and we certify that these models play an important role for the safer removal of denture foreign bodies.

[Acute low tone sensorineural hearing loss caused by inner ear barotrauma].

Three cases of inner ear barotrauma with subjective symptoms and hearing impairment which were similar to the low tone sudden deafness were reported. Case 1 was a 34-year-old man who developed a hearing loss in the next morning of taking an airplane and recovered four days after. Case 2 was a 42-year-old man who developed a hearing loss 2 days after flying in an airplane and hearing loss have recurred 4 times in his right ear for 3 months. Eight months after recovery of previous recurrent attack, a hearing loss occurred in his left ear without flying and recurred twice for 3 weeks. Case 3 was a 25-year-old woman who developed a hearing loss in the right ear after 24 meter depth scuba diving and recurred 4 times for 40 days. Those three patients complained of no vertigo at any attacks and were treated conservatively. From previous reports and the onset and the course of hearing disturbance, acute low tone sensorineural hearing loss in case 1 and case 2 was thought to be caused by circulatory disturbance of the inner ear and in case 3 thought to be caused by inner ear window rupture. But, endolymphatic hydrops was also needed to be take into account in those three cases as a common possible cause. Inner ear barotrauma and so called labyrinthine window rupture were considered to be one of the diseases needed to differentiate from low tone sudden deafness without reference to mono-attack type or recurrent type.