Mysterious abrupt carbon-14 increase in coral contributed by a comet.

A large and sudden increase in radiocarbon ((14)C) around AD 773 are documented in coral skeletons from the South China Sea. The (14)C increased by ~ 15‰ during winter, and remain elevated for more than 4 months, then increased and dropped down within two months, forming a spike of 45‰ high in late spring, followed by two smaller spikes. The (14)C anomalies coincide with an historic comet collision with the Earth's atmosphere on 17 January AD 773. Comas are known to have percent-levels of nitrogen by weight, and are exposed to cosmic radiation in space. Hence they may be expected to contain highly elevated (14)C/(12)C ratios, as compared to the Earth's atmosphere. The significant input of (14)C by comets may have contributed to the fluctuation of (14)C in the atmosphere throughout the Earth's history, which should be considered carefully to better constrain the cosmic ray fluctuation.

[Multi-modalities for reconstruction of circumferential defects in the pharyngoesophageal region].

OBJECTIVE: To investigate the feasibility of multi-modalities in the reconstruction of circumferential defects after resection of cancers in pharyngoesophageal regions, and to compare the pros and cons between different surgical procedures. METHODS: According to the nature and extend of defects, five different methods including pectoralis major myocutaneous flap, laryngeal tube replacement, free jejunum, free forearm flap and gastric pull-up were used to reconstruct the circumferential pharyngoesophageal defects in 72 patients. Function of deglutition and restoration of swallowing was regularly followed up and objectively evaluated. RESULTS: A total of 35 cases of pectoralis major myocutaneous (PM) flaps, 8 cases of laryngeal tube replacement, 12 cases of free jejunum, 12 cases of free forearm flaps and 16 cases of gastric pull-up were performed. Different complications including wound infection, pharyngeal fistula, partial necrosis of PM flap, partial necrosis of gastric wall, stricture of anastomotic site were encountered in 15 cases. All patients survived the operation except one due to partial necrosis of the gastric wall. Two of 4 patients who developed anastomotic stricture can ingest half-liquid food, the remaining cases regained normal deglutition function. The mean postoperative follow-up time was 1. 6 years with 2-year survival rate of 45.3%. CONCLUSIONS: Circumferential defects resulting from resection of carcinomas in pharyngoesophageal region can be reconstructed with different operative techniques depending on the nature and extend of the defects. Once the operative indications are properly selected, the good reconstructive results are to be achieved.