Weakening of the South Asian summer monsoon linked to interhemispheric ice-sheet growth since 12 Ma.

The evolution and driving mechanism of the South Asian summer monsoon (SASM) are still poorly understood. We here present a 12-Myr long SASM record by analyzing the strontium and neodymium isotopic composition of detrital components at IODP Exp. 359 Site U1467 from the northern Indian Ocean. The provenance investigation demonstrates that more dust enriched in εNd from northeastern Africa and the Arabian Peninsula was transported to the study site by monsoonal and Shamal winds during the summer monsoon season. A two-step weakening of the SASM wind since ~12 Ma is proposed based on the εNd record. This observational phenomenon is supported by climate modeling results, demonstrating that the SASM evolution was mainly controlled by variations in the gradient between the Mascarene High and the Indian Low, associated with meridional shifts of the Hadley Cell and the Intertropical Convergence Zone, which were caused by interhemispheric ice-sheet growth since the Middle Miocene.

Comparison between Intravenous Dexmedetomidine and Spray as you Go with 4% Lignocaine Versus Intravenous Fentanyl and Transtracheal Injection of 4% Lignocaine for Awake Nasotracheal Intubation with Flexible Vedioscope - A Randomized Single-Blind Prospective Study.

Background: Awake fiber-optic bronchoscopy-guided intubation is the method of choice in difficult airway which requires effective airway anesthesia to ensure patient comfort and acceptance. Aims: This study was conducted to assess the quality of airway anesthesia, patient comfort during intubation, and postoperative satisfaction of patients. Settings: Patients posted for surgeries under general anesthesia with Mallampati Grade I and II in a medical college. Patients were followed in the operation theater and postoperative ward. Study Design: This was a prospective randomized single-blind study. Materials and Methods: Group D received intravenous (i.v.) dexmedetomidine 1 µg.kg-1 i.v. over 10 min and 3 ml of 4% lignocaine spray as you go (SAYGo). Group F received i.v. fentanyl 2 µg.kg-1 over 10 min and transtracheal injection 3 ml of 4% lignocaine. Parameters assessed were endoscopic time, intubating condition, vocal cord position, cough severity, comfort during intubation, postoperative patient satisfaction, and any adverse effects such as sore throat, hoarseness, unpleasant memories, and hemodynamic response during intubation. Statistical Analysis: Independent Student's t-test, Mann-Whitney, Chi-squared test, or Fisher's exact test were used. P ≤ 0.05 was considered statistically significant. Results: Intubating conditions, vocal cord position, cough severity, comfort during intubation, and postoperative patient satisfaction were statistically significant (P ≤ 0.05) in favor of Group D though endoscopic time was longer. Conclusion: IV dexmedetomidine with SAYGo is effective than IV fentanyl with transtracheal block for awake fiber-optic videoscopic intubation in terms of intubating conditions, vocal cord position, cough severity, comfort during intubation, and postoperative satisfaction of patients with significant attenuation of postintubation hemodynamic response and better preservation of respiration though endoscopic time is more.

Increased chemical weathering during the deglacial to mid-Holocene summer monsoon intensification.

Chemical weathering and the ensuing atmospheric carbon dioxide consumption has long been considered to work on geological time periods until recently when some modelling and natural records have shown that the weathering-related CO2 consumption can change at century to glacial-interglacial time scale. Last glacial to interglacial transition period is a best test case to understand the interplay between Pco2-temperature-chemical weathering when a pulse of rapid chemical weathering was initiated. Here we show, from a high resolution 54 ka record from the Andaman Sea in the northern Indian Ocean, that the chemical weathering responds to deglacial to mid-Holocene summer monsoon intensification in the Myanmar watersheds. The multi-proxy data (Al/K, CIA, Rb/Sr, 87Sr/86Sr for degree of weathering and 143Nd/144Nd for provenance) reveal an increase in silicate weathering with initiation of interglacial warm climate at ~17.7 ka followed by a major change at 15.5 ka. Inferred changes in chemical weathering have varied in tandem with the regional monsoonal proxies (δ18Osw-salinity changes of Northern Indian Ocean, effective Asian moisture content and δ18O records of Chinese caves) and are synchronous with changes in summer insolation at 30°N and δ18O of GISP2 implying that chemical weathering was not a later amplifier but worked in tandem with global climate change.