State dependence of climatic instability over the past 720,000 years from Antarctic ice cores and climate modeling.

Climatic variabilities on millennial and longer time scales with a bipolar seesaw pattern have been documented in paleoclimatic records, but their frequencies, relationships with mean climatic state, and mechanisms remain unclear. Understanding the processes and sensitivities that underlie these changes will underpin better understanding of the climate system and projections of its future change. We investigate the long-term characteristics of climatic variability using a new ice-core record from Dome Fuji, East Antarctica, combined with an existing long record from the Dome C ice core. Antarctic warming events over the past 720,000 years are most frequent when the Antarctic temperature is slightly below average on orbital time scales, equivalent to an intermediate climate during glacial periods, whereas interglacial and fully glaciated climates are unfavourable for a millennial-scale bipolar seesaw. Numerical experiments using a fully coupled atmosphere-ocean general circulation model with freshwater hosing in the northern North Atlantic showed that climate becomes most unstable in intermediate glacial conditions associated with large changes in sea ice and the Atlantic Meridional Overturning Circulation. Model sensitivity experiments suggest that the prerequisite for the most frequent climate instability with bipolar seesaw pattern during the late Pleistocene era is associated with reduced atmospheric CO2 concentration via global cooling and sea ice formation in the North Atlantic, in addition to extended Northern Hemisphere ice sheets.

Spontaneous esophageal rupture successfully treated by conservative therapy: report of two cases.

Spontaneous esophageal rupture is a life-threatening condition for which surgical intervention within 24h after the onset is usually recommended. This report describes two cases of spontaneous esophageal rupture successfully treated by conservative therapy. In the first case, a 68-year-old man was hospitalized for severe upper abdominal pain following hematemesis. A large left pleural effusion occurred the next day and spontaneous esophageal rupture was diagnosed 1 week later, following placement of an intrathoracic drain. In the second case, a 38-year-old man was admitted for severe back pain following vomiting and esophageal rupture diagnosed within 3 h after onset by computed tomography (CT), which showed left pleural effusion, pneumothorax, and pneumomediastinum. Both patients were successfully treated conservatively with continuous intrathoracic drainage, intravenous antibiotics, and hyperalimentation. We conclude that spontaneous esophageal rupture can be treated conservatively under intensive observation.