Influence of Qinghai-Xizang Plateau snow cover on interannual variability of Western North Pacific tropical cyclone tracks

Track density function(TDF)was computed for all Western North Pacific tropical cyclones(WNP TCs)tracks from 1950 to 2018,and the TDFs were further investigated using principal component analysis(PCA)to analyze their inter-annual spatial and temporal variability.Then,the relationships between each empirical orthogonal function(EOF)mode and the typhoon count,typhoon landfall count,track pattern,and the Qinghai-Xizang Plateau snow cover(QXPSC)were examined,and the possible physical mechanisms implied by the statistical relationship were explored.The results show the QXPSC significantly affected the surface-atmosphere heat exchange through snow cover(SC)level,then changed the East Asian summer monsoon regional circulation pattern,influenced the subtropical high-pressure system strength and location,and ultimately affected the WNP TCs track patterns and thus changed their landfall locations.

Interannual and Decadal Variability of Landfalling Tropical Cyclones in the Southeast Coastal States of the United States

The interannual variability of the Atlantic tropical cyclone (TC) frequency is well known. Separately, recent studies have also suggested that a much longer, multidecadal (40-60 year) trend might be emerging from the recent increase in Atlantic TC activity. However, the overall structure of the intrinsic frequencies (or temporal modes) of Atlantic TC activity is not yet known. The focus of this study is to systematically an-alyze the intrinsic frequencies of Atlantic TC activity using hurricane and tropical storm landfall data collec-ted along the southeast coast(SEC) of the United States, Based on an Empirical Mode Decomposition (EMD) analysis of the frequency of landfall TCs along the SEC from 1887-1999, we have found that Atlantic TC activity has four primary, temporal modes. The interannual and multidecadal modes reported in the published literature are two such modes. After identifying all primary modes, the relative importance of each mode and its physical cause can be analyzed. For example, the most energetic mode is the interannual mode (2-7 year period). This mode is known to be associated with the 2-7 year El Nino/ La Ni na cycle. The average number of annual landfalling TCs along (he SEC decreased by 24% during El Nino years, but did not show significant increase during weak and moderate La Nina years. However, intense La Nina years were generally associated with more than average landfalling TCs along the SEC. The effects of El Nino and La Nina also became more significant when only hurricanes were considered. The significance of the effects of El Nino and La Nina on landfalling TCs and hurricanes in different US southeast coastal states showed significant differences.

Percentage of beta 2 band power of quantitative pharmaco-electroencephalography decreases in propofol anesthetized rabbits A dose-dependent analysis

BACKGROUND： Quantitative pharmaco-electroencephalography can be used for studying the dose-effect and time-effect relationships of drugs affecting central nervous system. Therefore, it may become an effective means for monitoring the anesthetic degree of anesthetic drug in the operation. OBJECTIVE： To observe the dose-effect relationship of propofol influencing β2-band power of quantitative pharmaco-electroencephalography in rabbits. DESIGN： A randomized block design. SETTING： Department of Anesthesiology, Xuzhou Medical College. MATERIALS： Thirty-six healthy adult rabbits of either gender, weighing （2.4 ± 0.5 ） kg, of clean grade, were provided by the Laboratory Animal Center of Xuzhou Medical College. The involved rabbits were randomly divided into 3 groups with 12 in each by table of random digit： high-dose propofol group, moderate-dose propofol group, and low-dose propofol group. The protocol was carried out in accordance with animal ethics guidelines for the use and care of animals. METHODS： This study was carried out in the Department of Anesthesiology, Xuzhou Medical College between August 1999 and April 2000. Rabbits in the high-dose propofol group, moderate-dose propofol group, and low-dose propofol group were injected with 10, 5 and 2.5 mg/kg propofol （ZENECA Company, British, Batch No. 032000）, respectively. Before and after intravenous administration of propofol, percentage of β2-band power of quantitative pharmaco-electroencephalography was measured, and the latent and persistent periods when rabbit righting reflex disappeared were observed by quantitative pharmaco-electroencephalography and power spectrum analysis. MAIN OUTCOME MEASURES： （1） Percentage of β2-band power of quantitative pharmaco-electroencephalography. （2）Latent period and persistent period of abolition of righting reflex of rabbits. RESULTS： Thirty-six rabbits were involved in the final analysis. （1）Effect of propofol on righting reflex of rabbits： Righting reflex disappeared within 1 minute after the rabbits being intravenously injected with propofol. The higher dose, the shorter latent period （r = - 0.94, P 〈 0.01）, and the longer persistent period （r =0.79, P 〈 0.01）. Both latent period and persistent period had good correlation with propofol dose. （2） Effect of propofol on the percentage of β2-band power of quantitative pharmaco-electroencephalography： In the low-dose propofol group, no significant changes in the percentage of β2-band power of quantitative pharmaco-electroencephalography existed between before and after administration within 30 minutes （P 〉 0.05）. In the moderate-dose propofol group, the percentage of β2-band power of quantitative pharmaco-electroencephalography in each brain region except for left and right frontal areas was significantly decreased within 30 s to 5 minutes （P 〈 0.05）, and recovered to the level before administration 10 minutes later. In the high-dose propofol group, the percentage of β2-band power of quantitative pharmaco-electroencephalography in each brain region was significantly decreased from 20 s to 5 minutes after administration （P 〈 0.05 - 0.01）, and that was gradually recovered to the level before administration 5 to 10 minutes after administration. This tendency was basically the same as the changes of latent period and persistent period. CONCLUSION： Propofol decreases the percentage of β2-band power of quantitative pharmacoelectroencephalography in dose-dependent manner, It indicates that β2-band power might become one of indexes for reflecting the anesthetic degree of propofol,