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.

Deposition records in lake sediments in western Japan of radioactive Cs from the Fukushima Dai-ichi nuclear power plant accident.

Sediment trap observations of lakes in western Japan before and after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident indicate that changes in the radioactive Cs discharge are influenced by fluctuations in precipitation and geomorphological conditions in each catchment. Contributions of FDNPP-derived (134,137)Cs to the sediment decreased from 19-48% to 10-15% within a few months, implying that the major transport processes of FDNPP-derived (134,137)Cs have changed from direct fallout to transport by soil particles.

Deposition of organochlorine pesticides into the surface snow of East Antarctica.

Organochlorine pesticides (OCPs) were measured in surface snow collected on a ~1400-km inland traverse beginning from the coastal regions of East Antarctica during the Japanese Antarctic Research Expedition (JARE) of 2007/2008. Of the 22 OCPs, α-hexachlorocyclohexane (HCH), γ-HCH, and hexachlorobenzene (HCB) were frequently detected in the snow with concentration ranges of 17.5-83.2, 33-137, and ND-182 pg L(-1), respectively. The most abundant pesticide was γ-HCH, with a mean concentration of 69.9 pg L(-1), followed by α-HCH, with an average concentration of 44.5 pg L(-1). The spatial variability of α-HCH and γ-HCH was narrow, and the concentrations of α-HCH and γ-HCH increased slightly with increasing altitude along the traverse route. Dome Fuji, the highest altitude sampling point, had the highest γ-HCH concentrations in the snow. Backward air trajectory analysis showed that the air masses at the sampling sites came mainly from the Indian and Atlantic Oceans and over the Antarctic continent, indicating that the OCPs were subjected to long-range atmospheric transport and were deposited in the surface snow. Our data suggest that the snow of Antarctica contains low levels of OCPs.

[Experimental vocal cord abduction impairment with an artificial vocal cord].

Non-invasive positive pressure ventilation (NPPV) has recently been applied to the patients with multiple system atrophy (MSA) with various respiratory complications including vocal cord abduction impairment and respiratory disturbance by the central origin. Any consensus guidelines on setting up the inspiratory positive airway pressure (IPAP) and expiratory one (EPAP), however, have not been raised yet. To investigate this problem, we made the upper airway tract model with moderately and severely narrow glottis using a training/test lung and the artificial vocal cord which was developed for a humanoid talking robot in Waseda University. The artificial vocal cord was molded out of a high performance thermoplastic rubber in imitation of the human larynx. Previous studies using with a high-speed camera and a sound analyzer showed that the artificial vocal cord resembled human larynx closely both morphologically and functionally. The opening and closing movements of the artificial vocal cord were observed fiberscopically under various conditions of IPAP (4-20 cmH2O) and EPAP (4-10 cmH2O). The maximal glottic width during inspiration and expiration were measured by a pair of calipers on the video-monitored display. Both of the moderately and the severely narrow artificial vocal cords without non-paralytic factors showed typical paradoxical movement showing adduction in inspiration and abduction in expiration, which is characteristic to vocal cord abductor impairment seen in MSA. In the model with moderately severe narrow glottis, this paradoxical movement was released under any positive pressures of continuous (CPAP) and bilevel (Bilevel PAP) modes. In the model with severely narrow glottis, however, there existed a threshold in setting up the optimal EPAP to release the paradoxical movement. In conclusion, EPAP-leading procedure seems to be preferable to IPAP-leading procedure to dilate the narrow glottis as a pneumatic splint in the managements of the patients with MSA presenting with a paralytic type of vocal cord abductor impairment.