消息与动态

尼安德特人现今一般被认为是智人种(Homo sapiens)的一个亚种,而最近以色列的拉克(Yoel Rak)教授提出尼人可能是与现代人的祖先平行发展的一个单独的种。 尼人在大约10万至3万年前生活于欧洲和中东,其解剖特征在东欧得到最大的发展。如厚重的骨骼,倾斜的前额,粗壮的眉脊,无颏的颌骨等是其与智人相区别的主要性状。 拉克等近年来在以色列占领区卡梅尔山(Mt.Carmel)的基巴拉(Kebara)洞的发掘中,发现了一具近乎完整的尼人骨架,但头部只保存有下颌骨和一个上第三臼齿,其年代测定为距今6万年。尼人的骨盆过去发现的只有少数破片,而基     

Soft tissue re-growth after different crown lengthening techniques among Indian patients

Patients often report complaining of fractured or decayed teeth with severe morphological deformities. However, all these clinical scenarios require the same level of care and consideration to rehabilitate form, function and esthetics. Some cases have sufficient clinical crown height while others often require an interdisciplinary approach in the form of orthodontic/surgical extrusion or surgical periodontal options. A common factor delaying treatment is soft tissue regrowth after crown lengthening which delays the impression required for final prosthesis. Therefore, it is of interest to compare the prevalence of soft tissue regrowth a week after different crown lengthening techniques including laser gingivectomy, electrocautery gingivectomy, modified Widman flap and apically repositioned. The parameters assessed included 1-week postoperative soft tissue regrowth after crown lengthening, age of patients and gender. It was observed that laser and electrocautery-assisted gingivectomy had a higher rate of soft tissue regrowth as compared to surgical techniques. It was further noted that laser and electrocautery assisted gingivectomy had a higher frequency of soft tissue rebound growth compared to surgical crown lengthening using modified widman flap and apically repositioned flap, which was statistically insignificant. Patients within the age groups of 26-60 years were found to have a higher tendency of soft tissue regrowth, which was found to be clinically and statistically significant (p<0.05).     

Changes in the timing of mantle formation and larval life history traits in linguliform and craniiform brachiopods

The distribution of embryonic and larval mantles is documented in linguliform and craniiform brachiopods. Criteria are presented for identifying these mantle types. The mantle type is related to planktotrophic and lecithotrophic larval life history patterns. In the Linguliformea and Craniiformea, all Lower Palaeozoic families with adequate preservation had larval mantles, indicating the presence of a planktotrophic larva. Heterochronic changes in the time of mantle origin, from the larval to the embryonic stage of development, has occurred several times. In the Lingulidae this change appears to have taken place at about the time the family originated in the Devonian and has been retained in extant genera. The family Discinidae has also retained a planktotrophic larval stage from the Lower Palaeozic to the present. The extant genus Crania in the Craniidae has a short-lived lecithotrophic larva that lacks a mantle. Through the Lower Jurassic, this family had planktotrophic larvae with a larval shell. During the Upper Jurassic, genera with a lecithotrophic larva that lacked a larval shell began to appear; however, the last genera in this family with a planktotrophic larva and a larval shell did not become extinct until the Tertiary.     

内蒙古乌达地区早二叠世晋囊蕨属一新种

Chansitheca (Sphenopteris) wudaensis sp. nov. is described based on the materials collected from the Lower Permian Shansi Formation of Wuda, Nei Mongol, China. The frond is small and at least two times pinnate. The pinnule is sphenopteroid. The sori are borne on the abaxial surface of the pinnule, arranged in two rows parallel to the midvein, elliptic,and composed of 4-10 round sporangia. The indusium is absent. The annulus is transverse and complete, and consists of about 18 thickened cells. The features of the fertile parts, sori, sporangia and annulus and the absence of indusium indicate that the new species belongs to the Gleicheniaceae.     

陕西宁强早志留世灰泥丘中微生物及其造岩意义

通过扫描电镜分析 ,在陕西宁强早志留世深缓坡微晶灰泥丘中发现 3种微生物化石 ,分别为 :( 1 )表面光滑卵球体 ,其大小为 5μm× 3μm ,壳体表面光滑 ,长轴端具有圆形凹坑或凸起 ,可能为芽体及芽痕 ;此类化石能与真菌类菌孢对比 ;( 2 )表面粗糙的椭球体 ,其大小为 60 μm× 50 μm ,壳体表面粗糙 ,具蠕虫状断续条纹 ,并有方解石胶结物生长 ;( 3)网格状结构 ,由钙化的胶质席状物及枝状物组成 ,网呈枝状分叉 ,盖覆于灰泥之上并参加造岩。经能谱分析 ,所有微生物化石均由碳酸钙组成 ,他们在灰泥丘的形成过程中起了重要的造岩作用     

南亚热带常绿阔叶林不同大小和发育阶段林隙的树种多样性研究

分析了南亚热带常绿阔叶林不同大小和发育阶段林隙内树种多样性的变化规律.结果表明,在南亚热带常绿阔叶林中,多样性指数在<400m²的林隙中变化不大,但在400～500m²的林隙中达到最大,而在500～600m²的林隙中最小,在>600m²的林隙中又有所增大.树种多样性指数随林隙年龄的变化趋势是中间高两端低,即在20～50年期间的多样性最大,其次是20年以下的,50年以后的多样性相对最小.林隙更新层中树种多样性指数在500～600m²的林隙中达到最大,在>600m²和200～300m²的林隙中最小.林隙更新层树种多样性指数在林隙形成最初的10年内达到最大值,但随着林隙年龄的增加,总体上表现出下降趋势,在30～40年和50～60年左右又分别形成两个相对的峰值.物种丰富度的变化趋势总体上与树种多样性指数相一致.不同大小和发育阶段的林隙通过其生态因子的改变,对不同树种的更新起到了不同的作用,从而使得不同大小和发育阶段的林隙中树种的多样性特征不同.林隙是维持南亚热带常绿阔叶林树种多样性的一个重要机制.     

关于百色手斧问题——兼论手斧的划分标准

本文从讨论手斧的定义出发 ,归纳出划分手斧的标准 ,并以此来衡量百色手斧 ,认为百色手斧是真正手斧。由于百色手斧的原料 (多为石英岩 )质地粗糙、结构面多、且有的在制作工具时已被风化 ,这在很大程度上影响手斧的制作质量 ,因此 ,百色手斧更多地显示出早期类型手斧的特点。百色手斧和印度、中东以及非洲的部分手斧有许多相同之处。这些相同之处主要是由于原料相同或相近的结果。文中论述的百色手斧 ,部分尚属首次报道。     

高龄肝癌患者肝癌切除术后并发症及预后分析

目的:探讨高龄原发性肝癌患者肝癌根治性切除术的疗效及安全性。方法:回顾性分析63例(高龄组≥70岁)与98例(对照组70岁)行肝部分切除术的原发性肝癌患者的一般资料及其围手术期情况,对其术后并发症及预后进行探讨。结果:高龄组术后并发症发生率为36.5%,对照组31.6%(P0.05),高龄组7(11.1%)例肝衰竭,2(3.17%)例术后有出血现象,3(4.8%)例切口感染,3(4.8%)例胸腔积液,1(1.5%)例伴有隔下感染,1(1.5%)例有严重肺部感染,由于下肢深静脉血栓脱落,死于急性肺动脉栓塞。组织病理类型高龄组以结节型多见,Edmondson Ⅰ-Ⅱ级33例,Ⅲ-Ⅳ级18例,胆管细胞癌8例,混合细胞型4例。BCLC-0、A、B、C期分别占2、9、35、17例。高龄组与对照组1、2、3年生存率分别为82.5%VS85.7%、34.9%VS46.3%、15.9%VS36.8%。结论:高龄对肝部分切除术后并发症的发生并无明显影响,并不是原发性肝癌根治性手术切除术的禁忌症,高龄患者2、3年生存率较对照组低。     

Frequency analysis of lower extremity electromyography signals for the quantitative diagnosis of dystonia

The purpose of this study was to develop an objective, quantitative tool for the diagnosis of lower extremity dystonia. Frequency domain analysis was performed on surface and fine-wire electromyography (EMG) signals collected from the lower extremity musculature of ten patients with suspected dystonia while performing walking trials at self-selected speeds. The median power frequency (MdPF) and percentage of total power contained in the low frequency range (%AUC_Total) were determined for each muscle studied. Muscles exhibiting clinical signs of dystonia were found to have a shift of the MdPF to lower frequencies and a simultaneous increase in the %AUC_Total. A threshold frequency of 70 Hz identified dystonic muscles with 73% sensitivity and 63% specificity. These results indicate that frequency analysis can accurately distinguish dystonic from non-dystonic muscles.