A closely linked genetic marker for cystic fibrosis

Cystic fibrosis is a recessive genetic disorder, characterized clinically by chronic obstructive lung disease, pancreatic insufficiency and elevated sweat electrolytes; affected individuals rarely live past their early twenties. Cystic fibrosis is also one of the most common genetic diseases in the northern European population. The frequency of carriers of mutant alleles in some populations is estimated to be as high as 1 in 20, carrying a concomitant burden of about one affected child in 1,500 births. Because little is known of the essential biochemical defect caused by the mutant gene, a genetic linkage approach based on arbitrary genetic markers and family studies is indicated to determine the chromosomal location of the cystic fibrosis (CF) gene. We have now obtained evidence for tight linkage between the CF locus and a DNA sequence polymorphism at the met oncogene locus. This evidence, combined with the physical localization data for the met locus presented in the accompanying paper, places the CF locus in the middle third of the long arm of chromosome 7, probably between bands q21 and q31.     

Caddisfly (Trichoptera) assemblages along major river drainages in Arizona

Seventy-two caddisfly species in 36 genera and 15 families were collected along the Little Colorado, Verde, Gila, and Colorado rivers in Arizona. Brachycentrids, hydropsychids, limnephilids, and uenoids made up nearly 50% of the assemblage in forested sites above 2200 m. Hydropsychids, hydroptilids, and leptocerids made up 75% of the assemblage in grassland watersheds between 2200 and 1000 m, and 80% at sites below 1000 m in desert watersheds. Species richness averaged 16 at sites above 2200 m elevation, 7 between 2200 and 1000 m, and 3 below 1000 m. H' diversity was typically >3 at sites above 2200 m and <2.5 below 2200 m. Each river had distinct faunas likely due to isolation of drainages across semiarid landscapes. Low S&oslash;rensen similarity values were measured for caddisfly assemblages in the highly regulated Colorado River and the other 3 rivers. Only 17 species were collected at 14 sites along 700 km of the Colorado River. Indicator caddisfly species are provided for altered and less disturbed drainages. We added 7 species not previously reported in Arizona for a total of 154 caddisfly species in the state. We provide a baseline of caddisfly indicators for monitoring changes in ecosystem health during the predicted long-term drought and population expansion in southwestern USA.     

HTR-10各运行阶段控制棒反应性当量计算

介绍了10 MW高温气冷反应堆(HTR-10)位于反射层中的控制棒反应性当量的计算方法.用GAM和THERMOS程序分别产生堆芯、反射层、含硼碳砖及控制棒组成材料的超热群和热群截面.用二维离散纵标法程序SN2D在(r,θ)坐标系下作详细控制棒结构的模型计算,该模型包括堆芯、反射层及反射层外的含硼碳砖,控制棒位于反射层中.含硼碳砖的外表面为自由边界,以考虑反射层中的中子泄漏谱.按通量权重归并控制棒区(包括控制棒、空隙及石墨反射层的整个圆环)的均匀化截面.全堆有控制棒和无控制棒情况下的Keff本征值,是由有限差分程序CITATION在(r,z)坐标系下计算出的,并由此得到控制棒的反应性当量.文中给出了HTR-10各运行阶段(包括初装堆、过渡过程中期和后期、平衡换料等时期)的控制棒的反应性当量.初装堆控制棒的反应性积分与微分当量也在文中给出.     

凝结水节流快速变负荷与自恢复控制

为提升燃煤发电机组的快速变负荷能力,进而支撑中国规模化新能源电力的并网与安全运行,通过凝结水节流的快速变负荷与自恢复控制,实现了凝结水节流与传统协调控制的有机结合。基于机理分析与试验曲线辨识建立了凝结水节流调节的动态微增功率模型,给出了机组含凝结水节流调节的三入两出非线性控制模型;设计了一种融合凝结水节流调节与传统协调控制的新型变负荷控制策略,克服了凝结水节流对除氧器和凝汽器热井水位的影响;同时显著提升了机组的变负荷性能。在某300 MW机组上的仿真验证表明,所提控制策略显著改善了机组的变负荷性能,对于响应电网侧的一次调频具有重要意义。     

创造教育与高师的使命

随着科学技术的迅猛发展，社会的急剧变革以开发人的创造力，培养创造型人才为宗旨的新型教育－－创造教育，已越来越引起人们广泛重视和深入的研究。本文探讨了创造型教师的主要特点，创新的教育观念、优化的知识结构、良好的个性特征、科学的教学方法、现代的管理意识、较强的科研能力。并通过对基础教育与创新关系的阐述，对高师如何推行创造教育提出了自己的一些思考，培养学生具有强烈的创造动机、扎实的知识基础、灵活的创造性     

孕妇尿液表皮生长因子的分离,纯化及活性检测

孕发尿液蛋白丙酮粉粗提液经Ｂｉｏ－ｇｅｌＰ－１０凝胶层析获得五个组分，经免疫点印渍分析后，证明其中组分Ⅲ的活性最高，该组分再经ＳｅｐｈａｄｅｘＧ－１５凝胶层析，又得到Ａ、Ｂ、Ｃ和Ｄ四个组，ｈＥＧＦ活性主要分布在组分Ａ中。本文建立了免疫点印渍方法并应用于ｈＥＦＧ的活性检测。     

MYC inactivation uncovers pluripotent differentiation and tumour dormancy in hepatocellular cancer

Hepatocellular carcinoma is generally refractory to clinical treatment. Here, we report that inactivation of the MYC oncogene is sufficient to induce sustained regression of invasive liver cancers. MYC inactivation resulted en masse in tumour cells differentiating into hepatocytes and biliary cells forming bile duct structures, and this was associated with rapid loss of expression of the tumour marker alpha-fetoprotein, the increase in expression of liver cell markers cytokeratin 8 and carcinoembryonic antigen, and in some cells the liver stem cell marker cytokeratin 19. Using in vivo bioluminescence imaging we found that many of these tumour cells remained dormant as long as MYC remain inactivated; however, MYC reactivation immediately restored their neoplastic features. Using array comparative genomic hybridization we confirmed that these dormant liver cells and the restored tumour retained the identical molecular signature and hence were clonally derived from the tumour cells. Our results show how oncogene inactivation may reverse tumorigenesis in the most clinically difficult cancers. Oncogene inactivation uncovers the pluripotent capacity of tumours to differentiate into normal cellular lineages and tissue structures, while retaining their latent potential to become cancerous, and hence existing in a state of tumour dormancy.     

Compact sources as the origin of the soft gamma-ray emission of the Milky Way

The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.     

Bleaching effect and nonvolatile holographic storage in doubly doped LiNbO<Subscript>3</Subscript>:Fe:Cu crystals

The bleaching effect, i. e. the crystal shows that decoloration after it is illuminated by ultraviolet light, has been observed in congruent LiNbO3:Fe :Cu crystals. Based on this bleaching effect, a new technique including the reco rding phase by two interfering red beams and fixing phase by both UV light and a coherent red beam has been experimentally investigated to realize nonvolatile holographic storage in LiNbO3:Fe:Cu. The results of proof-of-concept experiments confirm that bleaching effect becomes an alternative physical mechanism for nonv olatile holographic storage with high recording sensitivity and weak light-induced scattering noise.