MSCT在少儿胰腺实性假乳头状瘤诊断中的应用

目的:分析少儿胰腺实性假乳头状瘤（SPTP）的多层螺旋CT（MSCT）检查特征,提高其术前诊断正确率。方法:回顾性分析资料完整的7例SPTP患儿的临床资料及MSCT图像。结果:肿瘤均为单发,3例位于胰头颈部,4例位于胰体尾部,长径为3.1~9.6 cm,平均5.9 cm,境界清晰。5例为囊实相间型,2例囊性为主型,1例肿瘤伴钙化,1例伴出血,2例伴远端胰管轻度扩张,1例伴胰周淋巴结增大。增强扫描肿瘤实性部分呈渐进性强化,囊性区无强化。结论:少儿SPTP的MSCT表现具有一定特征性,再结合临床病史,可提高该病的术前诊断正确率。      

Structural analysis and interpretation of the surface deformation associated with the Ning’er,Yunnan Province,China <Emphasis Type="Italic">M</Emphasis><Subscript>S</Subscript>6.4 earthquake of June 3, 2007

The seismogenic fault and the dynamic mechanism of the Ning’er, Yunnan Province M_S6.4 earthquake of June 3, 2007 are studied on the basis of the observation data of the surface fissures, sand blow and water eruption, landslide and collapse associated with the earthquake, incorporating with the data of geologic structures, focal mechanism solutions and aftershock distribution for the earthquake area. The observation of the surface fissures reveals that the Banhai segment of the NW-trending Ning’er fault is dominated by right-lateral strike-slip, while the NNE-trending fault is dominated by left-lateral strike-slip. The seismo-geologic hazards are concentrated mainly within a 330°-extending zone of 13.5 km in length and 4 km in width. The major axis of the isoseismal is also oriented in 330° direction, and the major axis of the seismic intensity VIII area is 13.5 km long. The focal mechanism solutions indicate that the NW-trending nodal plane of the Ning’er M_S6.4 earthquake is dominated by right-lateral slip, while the NE-trending nodal plane is dominated by left-lateral slip. The preferred distribution orientation of the aftershocks of M_S≥2 is 330°, and the focal depths are within the range of 3～12 km, predominantly within 3～10 km. The distribution of the aftershocks is consistent with the distribution zone of the seismo-geologic hazards. All the above-mentioned data indicate that the Banhai segment of the Ning’er fault is the seismogenic fault of this earthquake. Moreover, the driving force of the Ning’er earthquake is discussed in the light of the active block theory. It is believed that the northward pushing of the Indian plate has caused the eastward slipping of the Qinghai-Tibetan Plateau, which has been transformed into the southeastern-southernward squeezing of the southwest Yunnan region. As a result, the NW-trending faults in the vicinity of the Ning’er area are dominated by right-lateral strike-slip, while the NE-trending faults are dominated by left-lateral strike-slip. This tectonic framework might be the main cause of the frequent occurrence of M_S6.0～6.9 earthquakes in the area.     

柴北缘宗务隆构造带蓄集地区闪长岩的发现及其地质意义

宗务隆构造带是柴达木北缘一个重要构造单元,但其构造属性长期存在争议。本次在宗务隆构造带中西部蓄集地区发现了闪长岩体,对其开展了岩相学、地球化学、锆石U-Pb年代学及Lu-Hf同位素等研究。结果表明,岩体侵入时代为258±1 Ma,富集轻稀土元素而亏损重稀土元素,具弱的负Eu异常,相对富集Rb、K、Sr等大离子亲石元素,而强烈亏损P、Ti、Nb等高场强元素,Cr和Ni含量分别为38.0×10~(-6)～92.8×10~(-6)和6.7×10~(-6)～14.1×10~(-6),Mg#值为50～56,Rb/Sr值为0.32～0.34,Ti/Zr值为23.26～32.30,Ti/Y值为145.29～163.97,Nb/Ta值为10.45～11.45,Th/La值为0.39～0.51,Ba/La值为15.04～16.60,~(207)Pb/~(204)Pb(i)值为15.602～15.611,锆石εHf(t)值为-8.52～-3.00,二阶段模式年龄值(tDM2)值存在1 563～1 478 Ma[εHf(t)=-4.37～-3.00]和1 827～1 790 Ma[εHf(t)=-8.52～-7.98]两组,指示蓄集闪长岩岩浆是壳幔混合的产物,其中古老地壳物质占主导。结合区域地质调查结果,推测宗务隆构造带中西部地区的边缘裂陷应晚于东部。     

沉积物对珊瑚礁及礁区生物的影响

海水中日益增多的悬浮物和泥沙沉降是导致珊瑚礁严重衰退的原因之一。沉积物覆盖在珊瑚礁生物表面,影响其呼吸作用,而海水浊度的增加会减少光合作用的可利用光。过多的沉积物改变了礁区的物理以及生物过程,从而对珊瑚礁生态系的结构和功能产生不利影响。为了有效评估珊瑚礁的变化趋势,如优势种丰度以及空间分布的变化等,应用标准的监测方法进行长期监测对于掌握这一复杂生态系统的变化是非常关键的。综述了沉积物对珊瑚生长率、生长形态、代谢和繁殖与补充以及礁区生物的影响,并指出未来的研究方向,以期为珊瑚礁的保护提供参考。