山东莒南发现的石制品

本文报道的128件人工石制品分别采自山东莒南县的石莲子乡烟敦岭和扁山乡九顶莲花山两个地点。石制品常见类型有边刮器,端刮器和砍斫器等,另有少量的雕刻器和尖状器,内含典型细石器。就石制品的组合及工艺水平而言,其时代可能属于旧石器时代末期。     

载脂蛋白多基因家族分子进化的研究

与脂质运输有关的载脂蛋白基因构成一个复杂的多基因家族。为探讨这种演化时间长的基因家族的进化规律,本文首先建立了一种在非均衡进化速率条件下计算系统发生树中任意分支长度的简易方法,并可在此基础上算出无根分支系统树中分歧年代的期望值。进一步对本文科１０个种属共２６种载脂蛋白的系统演作作了实际分析,结果提示：①ＡｐｏＡ－Ｉ＇ＡｐｏＡ－ＩＶ,ＡｐｏＥ及ＡｐｏＡ－ＩＩ的共同祖先可能在奥陶纪水生脊椎动物中就已存     

A new 500-year reconstruction of Truckee River streamflow

The Truckee River Basin, located on the Nevada-California border, is an area of extreme hydrologic variability, being subject to both prolonged multi-decadal droughts and devastating floods; however, due to the brief instrumental record, understanding of the full range of this variability is limited. To assist local water managers assess the post-2000 drought in the context of historic droughts, this study revisits the first tree-ring reconstruction of Truckee River runoff: Hardman and Reil (1936). Incorporating their original 1930s tree cores as well as newly sampled material, three new site chronologies were developed and combined with other regional chronologies to produce a 1491–2003 reconstruction of Truckee River streamflow, an over 400-year extension of the instrumental record and 230 years longer than the previous reconstruction, providing new insights into the basin’s natural variability. In addition to evidence of extended droughts and extreme high streamflow years, this reconstruction shows a marked hydroclimatic shift centered around the 1850s. Prior to then, the Truckee River experienced decadal to multi-decadal periods of higher than average streamflow; subsequently, these periods have been decreasing in length with only two instances above three consecutive years of high streamflow since 1900. Whether this represents fundamental shift to a new hydroclimatic regime remains unclear. However, as global temperatures continue to rise, fewer long-term high streamflow episodes may have lasting impacts on water availability in the basin, raising the question further of whether the post-2000 drought is a new megadrought or a sign of aridification.     

DISCOVERY OF VERTEBRATE FOSSILS AND PALEOLITHIC ARTIFACTS IN DANJIANG SUBMERGING AREA AND ITS IMPLICATIONS

IntheareatobefloodedinthesecondengineeringstagefortheDanjiangreservoir,wediscovered16vertebratefossillocalitiesand52Paleolithicsitesin1994,andcollected603artifactsandmanyfossils.Ofthel6new1yfoundvertebratefossillocalities,threearereptilesitesrepresentedbydinosaureggsandlimbbones,andl3producemamma1s,including4Pale0gene,2Ne0geneand7Quaternarysites'ThemammalianlocalitiesareofPale0cene,Eocene,EarlyMiocene,andPli0ceneorEarlyPleistocene,MiddleandIntePleistocene,respectively.Theyfillinsomestrat…     

Fouling communities and degradation of archeological metals in the coastal sea of the Southwestern Gulf of Mexico

Corrosion and biofouling phenomena of cast iron and brass were evaluated under natural conditions to determine the degradation process of archeological artifacts. Field exposure studies of experimental materials were conducted over 15 months at an offshore position in the sea of Campeche in the Gulf of Mexico. Corrosion was determined by gravimetric measurements. The community structure of the benthic assemblage inhabiting the surfaces of both materials was evaluated. A total of 53 species was identified. The community in both cases was composed of a small number of species. Encrusting, attached and erect life forms were dominant on iron. Attached life forms were dominant on brass. Biofouling produced a decrease in the weight loss measurements of cast iron samples. Biofouling provided a beneficial factor for in situ preservation of iron archeological artifacts in wreck sites.     

能谱CT在去除腰椎术后金属伪影中的应用进展

多层计算机断层扫描(Multi-slice computed tomography,MSCT)具有时间及空间分辨率高的特点已经被广泛应用于脊柱术后评价,然而,因为术中植入金属植入物,CT图像由于其成像原理的限制,其图像质量受到金属植入物的严重影响,金属伪影大多来源于量子噪声、散射线和射束硬化效应,降低图像的对比度,使细微解剖结构显示不清,从而使得感兴趣区域的检测能力降低,其图像质量明显下降,甚至使临床医师做出错误的诊断,因此,为了做出更准确的腰椎术后并发症诊断和术后评估,使金属伪影最小化成为关键。能谱CT及其扫描及重建技术可以有效的去除腰椎术后产生的金属伪影,改善图像质量,本文能谱CT在腰椎术后金属伪影去除方面的应用进行综述。     

数字化外科技术在颌面部外伤修复重建中的应用与展望

近年来,数字化外科技术在颌面部外伤修复重建临床应用中得到不断发展和完善,极大地提高了手术的精确性和可靠性,节约了手术时间。本文主要从术前手术模拟、快速打印3D头模、术中导航、导板制作、个性化修复体及机器人的临床应用等六个方面来阐述数字化外科技术在颌面部骨折修复重建中的应用,总结了各个技术的原理、优缺点及应用现状,回顾了我们单位应用数字化技术提高颌面部外伤修复手术的精确度和可行性以及恢复了患者良好的面型及功能的临床应用经验。同时,本文对未来数字化外科在颌面部骨折修复重建中的应用提出了新的展望,我们认为,结合术前手术模拟、术中导航及术中机器人技术依据术中具体情况自动调整手术方案进行颌面部骨折修复重建的完全自动化智能机器人的实现将是最终的目标。     

关节镜下前交叉韧带重建术的手术时机对患者膝关节功能恢复的影响

目的:研究关节镜下前交叉韧带(ACL)重建术的手术时机对患者膝关节功能恢复的影响。方法:选取2016年1月至2017年8月我院收治的膝关节ACL损伤患者65例为研究对象,所有患者均接受关节镜下ACL重建术治疗,并按照患者受伤至接受手术的时间分为研究组(n=35,受伤至接受手术的时间≤3周)和对照组(n=30,受伤至接受手术的时间3周),术后对患者进行为期6个月的随访,对比两组患者术前和术后6个月的膝关节活动度、膝关节功能以及ACL恢复情况,并比较随访期间两组并发症发生情况。结果:术前,两组膝关节活动度、国际膝关节文献委员会膝关节评估表(IKDC)和Lysholm膝关节评分比较差异无统计学意义(P0.05),术后6个月,两组膝关节活动度、IKDC评分和Lysholm膝关节评分均较术前升高,且研究组高于对照组,差异有统计学意义(P0.05)。术前与术后6个月,两组前抽屉(ADT)试验和Lachman试验阴性率比较差异无统计学意义(P0.05),但与术前比较,术后6个月两组ADT试验和Lachman试验阴性率均升高,差异有统计学意义(P0.05)。与对照组比较,研究组并发症总发生率降低,差异有统计学意义(P0.05)。结论:膝关节ACL损伤患者在不同时间内接受关节镜下ACL重建术治疗均具有较好的效果,但是在受伤后3周内接受手术对患者膝关节功能恢复效果更明显,同时并发症发生率也相对更低。     

黄河中游晋陕峡谷陕西侧龙门至壶口段新发现的石制品

2019-2020年,在黄河中游晋陕峡谷陕西一侧龙门至壶口段新发现9处旷野旧石器地点,采集石制品136件,部分石制品直接采自地层剖面上。康家岭地点石制品的埋藏地层为马兰黄土底部的洪积碎屑层,时代可能为晚更新世早期。苏家岭地点有1件石制品出自MIS3阶段弱古土壤层之下的洪积碎屑层,光释光年龄为距今7.2±0.7万年。其余大部分石制品的埋藏地层为马兰黄土层,时代为晚更新世中、晚期,其中凉泉沟地点埋藏石制品的黄土地层光释光年龄大于距今5万年。古人类加工石制品的原料主要为砾石,岩性以石英岩为主,其次为石英,此外还有少量燧石、细砂岩和硅质岩。石制品类型包括石核、石片、石器和断块。个体大小以中小型为主。石核和石片以自然台面者为主,剥片主要采用硬锤锤击法直接剥片,少量应用砸击法。石器有中小型的刮削器、凹缺器和大型的砍砸器,均属简单石核-石片技术产品。本次新发现的旧石器地点进一步扩大了晋陕峡谷地区旧石器时代遗存的时空分布范围,有助于后续相关研究工作的开展。     

Microtome sectioning causes artifacts in rhizobox experiments

Experimental data on rhizosphere characteristics at high spatial resolution are required to improve our knowledge on phytoavailability of nutrients and pollutants. In numerous studies, sectioning using refrigerated microtomes has been employed to obtain thin soil layers at defined distances from the root surface. In this study, we assessed the effect of thin slicing and freezing on soil chemical characteristics. Two experimental soils were frozen at –20°C and sliced using a refrigerated microtome. In general, chemical changes relative to the non-sliced control were more pronounced as the trim thickness (thickness of a single slice) decreased. Maximum increases in pH and electrical conductivity (EC) for the smallest trim thickness used (20 m) were 0.9 units and 50%, respectively. Extractable fractions of P (0.5 M NaHCO₃) K, Mg, Mn, Na and Si (1 M NH₄NO₃) increased up to 40, 91, 19, 621, 50 and 100%, respectively. Based on these results, we suggest to use a trim thickness of 200 m. Apart from slicing, freezing (a prerequisite for the microtome technique) was found to bias soil chemical parameters. To circumvent microtome-related artifacts we present a home-made slicing device as a cost-effective alternative, which allows sectioning of non-frozen rhizosphere soil employing one single slice.