New dating indicates intermittent human occupation of the Nwya Devu Paleolithic site on the high-altitude central Tibetan Plateau during the past 45,000 years

The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great interest.Here,we report on our reinvestigations and dating of the Nwya Devu site,located nearly 4600 meters above sea level on the central Tibetan Plateau.A new microblade techno-complex was identified on a lower lake shore at this site,distinct from the previously reported blade tool assemblage.These two lithic assemblages were dated to 45.6±2.6 and10.3±0.5 ka using optically stimulated luminescence and accelerator mass spectrometry^(14)C methods.They represent,respectively,the earliest known Paleolithic and microlithic sites on the interior Tibetan Plateau,indicating multiple occupation episodes of hunter-gatherers during the past 45 ka.Our studies reveal that relatively stable depositional conditions and a paleoenvironment characterized by a comparatively warm climate facilitated these multiple occupations at Nwya Devu.The contemporaneous occurrence of the Upper Paleolithic blade technology on the Tibetan Plateau and most of Eurasia between 50 and 40 ka indicates rapid,large-scale dispersals of humans that profoundly affected human demography on a large scale.Combining new archaeological evidence and previously reported genetic data,we conclude that the Tibetan Plateau provided a relatively stable habitat for Upper Paleolithic hunter-gatherers,which may have contributed to the complex and multiple-origin gene pool of present-day Tibetans.

The peopling of the hinterland of the Tibetan Plateau during the late MIS 3

Reaching the Tibetan Plateau is notoriously challenging due to its high elevations and the surrounding mountain ranges.Considering environmental pressures such as low temperatures and precipitations,patchy resources,and especially hypoxia,continued survival in the region requires both biological and behavioral adaptations.This is probably why for a long time the Plateau was considered among the last regions occupied by human beings.

Maternal genetic history of ancient Tibetans over the past 4000 years

The settlement of the Tibetan Plateau epitomizes human adaptation to a high-altitude environment that poses great challenges to human activity.Here,we reconstruct a 4000-year maternal genetic history of Tibetans using 128 ancient mitochondrial genome data from 37 sites in Tibet.The phylogeny of haplotypes M9a1a,M9a1b,D4g2,G2a’c,and D4i show that ancient Tibetans share the most recent common ancestor with ancient Middle and Upper Yellow River populations around the Early and Middle Holocene.In addition,the connections between Tibetans and Northeastern Asians vary over the past 4000 years,with a stronger matrilineal connection between the two during 4000 BPe3000 BP,and a weakened connection after 3000 BP,that are coincident with climate change,followed by a reinforced connection after the Tubo period(1400 BPe1100 BP).Besides,an over 4000-year matrilineal continuity is observed in some of the maternal lineages.We also find the maternal genetic structure of ancient Tibetans is correlated to the geography and interactions between ancient Tibetans and ancient Nepal and Pakistan populations.Overall,the maternal genetic history of Tibetans can be characterized as a long-term matrilineal continuity with frequent internal and external population interactions that are dynamically shaped by geography,climate changes,as well as historical events.

QM/MM study on the O_(2)activation reaction of 4-hydroxylphenyl pyruvate dioxygenase reveals a common mechanism forα-ketoglutarate dependent dioxygenase

The dioxygen activation catalyzed by 4-hydorxylphenyl pyruvate dioxygenase(HPPD)were reinvestigated by using hybrid quantum mechanics/molecular mechanics(QM/MM)approaches at the B3LYP/6-311++G(d,p):AMBER level.These studies showed that this reaction consisted of two steps including the dioxygen addition/decarboxylation and hetero O-O bond cleavage,where the first step was found to be rate-determining.The former step initially runs on a septet potential energy surface(PES),then switches to a quintet PES after crossing a septet/quintet minimum energy crossing point(MECP)5-7M2,whereas the rest step runs on the quintet PES.The reliability of our theoretical predictions is supported by the excellent agreement of the calculated free-energy barrier value of 16.9 kcal/mol with available experimental value of 16-17 kcal/mol.The present study challenges the widely accepted view which holds that the O2activation catalyzed byα-keto glutamate(α-KG)dioxygenase mainly runs on the quintet PES and provides new insight into the catalytic mechanism ofα-KG dioxygenase and/or other related Fe(Ⅱ)-dependent oxygenase.

我国烧伤专业医护人员对Ⅱ度烧伤创面的早期处理的横断面调查与分析

目的了解我国烧伤专业医护人员对Ⅱ度烧伤创面的早期处理现状,促进Ⅱ度烧伤创面早期临床规范化治疗。方法采用横断面调查方法。2020年11月—2021年2月,将自制的Ⅱ度烧伤创面早期处理问卷通过“问卷星”网站发布后经微信分享,对符合入选标准的我国从事烧伤专业的医护人员进行便利抽样调查。统计被调查者所属医院的数量、所在地区、等级,被调查者年龄、性别、职业和年资。将被调查者分为医师组、护士组,高年资组、低年资组,东部地区组和非东部地区组,一二级医院组、三级医院组,统计医师组与护士组被调查者的年资、所属医院等级、所属医院所在地区;所有分组中各组被调查者的Ⅱ度烧伤水疱常规处理、保留水疱皮的原因、去除水疱皮的原因,Ⅱ度烧伤创面早期外用药物或敷料的常规选择、最优方案推荐。对数据行χ^(2)检验。结果该次调查覆盖我国31个省市自治区(除香港、澳门和台湾地区),共回收979份问卷,均为有效问卷。979名被调查者来自全国449家医院,其中东部地区医院203家、西部地区医院116家、中部地区医院99家及东北地区医院31家,三级医院348家、二级医院79家、一级医院22家。被调查者年龄为(39±10)岁,男性543名、女性436名,医师656名、护士323名,低年资人员473名、高年资人员506名,东部地区人员460名、非东部地区人员519名,三级医院人员818名、一二级医院人员161名。医师组和护士组中不同年资被调查者构成,差异明显(χ^(2)=44.32,P<0.01);但医师组和护士组被调查者的所属医院等级、所属医院所在地区分布,差异均无统计学意义(P>0.05)。不同职业组、年资组以及所属医院所在地区组的被调查者在对Ⅱ度烧伤水疱的常规处理上,差异均无统计学意义(P>0.05)。不同所属医院等级组的被调查者在对Ⅱ度烧伤水疱的常规处理上,差异明显(χ^(2)=6.24,P<0.05)。相较于护士组,更大比例医师组被调查者选择保留水疱皮的原因是保护创面并提供湿润环境、减轻换药疼痛(χ^(2)值分别为21.22、19.96,P值均<0.01),更小比例医师组被调查者选择保留水疱皮的原因是预防创面感染(χ^(2)=23.55,P<0.01);医师组和护士组被调查者选择保留水疱皮的原因是加速创面愈合、减轻创面愈后色素沉着和瘢痕增生的情况均相近(P>0.05)。相较于低年资组,更大比例高年资组被调查者选择保留水疱皮的原因是保护创面并提供湿润环境、减轻换药疼痛(χ^(2)值分别为10.36、4.60,P<0.05或P<0.01),更小比例高年资组被调查者选择保留水疱皮的原因是预防创面感染(χ^(2)=8.20,P<0.01);高年资组和低年资组被调查者选择保留水疱皮的原因是加速创面愈合、减轻创面愈后色素沉着和瘢痕增生的情况均相近(P>0.05)。东部地区组与非东部地区组相比、三级医院组与一二级医院组相比,被调查者选择保留水疱皮的5种原因情况均相近(P>0.05)。护士组被调查者选择去除水疱皮的6种原因便于采用更理想敷料保护创面、预防创面感染、利于创面外用药物发挥作用、水疱容易破裂污染创面、加速创面愈合、减轻创面愈后色素沉着和瘢痕增生的比例均分别明显大于医师组(χ^(2)值分别为4.35、25.59、11.83、16.76、46.31、17.54,P<0.05或P<0.01)。相较于高年资组,更大比例低年资组被调查者选择去除水疱皮的原因是水疱容易破裂污染创面、预防创面感染、加速创面愈合以及减轻创面愈后色素沉着和瘢痕增生(χ^(2)值分别为17.25、18.63、14.83、10.23,P值均<0.01)。相较于非东部地区组,更大比例东部地区组被调查者选择去除水疱皮的原因是预防创面感染、水疱容易破裂污染创面(χ^(2)值分别为9.30、8.65,P值均<0.01)。三级医院组和一二级医院组被调查者选择去除水疱皮的6种原因情况均相近(P>0.05)。相较于医师组,更大比例护士组被调查者选择对Ⅱ度烧伤创面早期使用保湿材料(χ^(2)=6.18,P<0.05),更小比例护士组被调查者选择其他外用药物或敷料(χ^(2)=5.20,P<0.05)。相较于低年资组,更大比例高年资组被调查者选择对Ⅱ度烧伤创面早期使用保湿材料、其他外用药物或敷料(χ^(2)值分别为4.97、21.80,P<0.05或P<0.01)。相较于非东部地区组,更大比例东部地区组被调查者选择对Ⅱ度烧伤创面早期使用外用抗菌药物(χ^(2)=4.09,P<0.05),更小比例东部地区组被调查者选择对Ⅱ度烧伤创面早期使用其他外用药物或敷料(χ^(2)=5.63,P<0.05)。相较于一二级医院组,更大比例三级医院组被调查者选择对Ⅱ度烧伤创面早期使用生物敷料(χ^(2)=9.38,P<0.01)。不同职业组、年资组的被调查者对Ⅱ度烧伤创面早期外用药物或敷料的最优方案推荐均差异明显(χ^(2)值分别为39.58、19.93,P值均<0.01)。东部地区组和非东部地区组、三级医院组和一二级医院组的被调查者对Ⅱ度烧伤创面早期外用药物或敷料最优方案推荐,差异均无统计学意义(P>0.05)。结论我国烧伤专业医护人员在对Ⅱ度烧伤水疱的常规处理措施和保留水疱皮的原因上较为一致,但在去除水疱皮的原因、Ⅱ度烧伤创面外用药物或敷料的常规应用及最优方案推荐方面差异较大,亟须建立Ⅱ度烧伤创面早期临床治疗规范。