简介:本文提出了一种新的反演方法:通过采用纵、横波走时数据对(从相同的震源产生的P和S波被同一台站记录)来联合反演纵波速度(Vp)和纵、横波速度比(Vp/Vs),然后单独反演横波速度Vs,在反演过程中同时对地震参数进行定位。该方法不需要假设P和S波的射线路径一致,它是沿着P和S波射线路径计算相对慢度扰动值。该方法直接把Vp/Vs作为一个模型参数,由此能获得比采用从独立反演获得的Vp和Vs计算出Vp/Vs的方法更精确的速度比值。该新方法被应用到反演日本东北地区的壳幔速度及波速比结构的研究中,获得了较好的效果。反演结果表明,在日本东北地区,太平洋俯冲板块为一高Vp,高Vs和低Vp/Vs异常区,而在活火山下方的浅部地幔楔以及背弧深部地区为低Vp,低VS和高Vp/VS异常。虽然这些特征在前人的研究中已经报道过,但与前人的研究结果相比,本次研究所获得的Vp/Vs的空间分布具有较小的分散性,同时,它的分布特征能较好的与地震波速度结构相吻合。
简介:AbstractLong-term and stable preservation of bacteriophages is of crucial importance. Although many efforts have been made in the past decades to explore the influence of external factors on bacteriophage preservation, there is still little understanding, and a systematic description is lacking. In this study, we explored the influence of different factors on the preservation of lytic bacteriophage VP3, one of the typing bacteriophages of Vibrio cholerae O1 biotype El Tor, and attempted to optimize its preservation. We examined external factors, including temperature, solution, and cryoprotectant, in stable cooling/freezing conditions or alternate cooling/freezing and thawing. We found that whether in Luria-Bertani (LB) medium or SM buffer, in terms of 20-week stable cooling or freezing, -20 °C was the most damaging while 4 °C, -80 °C, and -196 °C were protective. Thirteen cycles of alternate cooling/freezing and thawing caused a loss in the survival rates of bacteriophages. The addition of cryoprotectant, glycerol (30%, w/v) or dimethyl sulfoxide (DMSO, 10%, w/v) significantly improved the survival rates of bacteriophages preserved at -20 °C. However, at 4 °C, -80 °C, and -196 °C, the cryoprotectant effect was only slightly positive or even harmful. In summary, for bacteriophage VP3, the best preservation method is to directly preserve the bacteriophage stocks in LB medium at -80 °C or -196 °C instead of storing them in SM buffer or adding cryoprotectant. Our results provided insights into the external influencing factors on bacteriophage VP3 during preservation at low temperature and can be applied to the optimization of bacteriophage preservation in the future.
简介:“NP+之+VP”结构是上古汉语中一种常见的语法现象,当今对该结构的认识尚有较大分歧。文章以《国语》中的“NP+之+VP”结构为语料详尽地统计、分析了该结构的构成成分和语法功能,以便深化对该结构的认识。
简介:ShanxiGrabenisinthemiddlepartoftheNorthChinaCraton,fromsouthtonorth.WiththeteleseismicdatarecordedbyRegionalSeismographNetworksandthetemporaryZBnet-WSeismicArrayaroundeastpartofShanxiGraben,wemeasuredthecrustalthicknessandvP/vSratiobeneatheachstationusingtheH-jstackofreceiverfunctions.Theobservedcrustalthicknessshowsobviouslateralvariation,increasinggraduallyfromeasttowestintheShanxiGraben.BeneaththeShanxiGrabenthecrustisrelativelythickerthanbothsidesofthesouthandthenorth.Inaddition,thevP/vSratiointhenorthofstudyzoneishigherthanthatinthesouth.ThehighestvP/vSratioexistsinthecrustoftheXindingbasinandtheDatongbasin.Ourstudyalsosuggeststhathighvelocityratiomightresultfromthestrongactivitiesofthemagmationandvolcanism.