乙炔二锂（C2Li2）异构体反应的分子轨道研究

基于量子化学从头计算法（ＣＣＳＤ（Ｔ）、ＱＣＩＳＤ（Ｔ））以及二阶微扰法（ＭＰ２），研究了乙炔二锂分子的平面桥式与线性式之间的异构化途径．６－３１１Ｇ（ｄ）基态被用于几何优化和反应途径的确定，而６－３１Ｇ（３ｄｆ）基态被用于单点式计算．其有关结构优先及成键特征的结果与用Ｍφｌｅｒ－Ｐｌｅｓｓｅｔ微扰方法所得一致．在ＭＰ２／６－３１１Ｇ（ｄ）理论水平上给出了质－权坐标的最小能量途径．在本研究的最高理论水平［ＱＣＩＳＤ（Ｔ，ＦＵＬＬ）／６－３１Ｇ（３ｄｆ）∥ＱＣＩＳＤ（Ｔ，ＦＵＬＬ）／６－３１１Ｇ（ｄ）］上，发现平面型分子的异构化势垒（１０．０ｋｃａｌ／ｍｏｌ）要比线型Ｃ２Ｌｉ２（１．３ｋｃａｌ／ｍｏｌ）的大得多     

Methane emissions from terrestrial plants under aerobic conditions

Methane is an important greenhouse gas and its atmospheric concentration has almost tripled since pre-industrial times. It plays a central role in atmospheric oxidation chemistry and affects stratospheric ozone and water vapour levels. Most of the methane from natural sources in Earth's atmosphere is thought to originate from biological processes in anoxic environments. Here we demonstrate using stable carbon isotopes that methane is readily formed in situ in terrestrial plants under oxic conditions by a hitherto unrecognized process. Significant methane emissions from both intact plants and detached leaves were observed during incubation experiments in the laboratory and in the field. If our measurements are typical for short-lived biomass and scaled on a global basis, we estimate a methane source strength of 62-236 Tg yr(-1) for living plants and 1-7 Tg yr(-1) for plant litter (1 Tg = 10(12) g). We suggest that this newly identified source may have important implications for the global methane budget and may call for a reconsideration of the role of natural methane sources in past climate change.     

Nogo-A is a myelin-associated neurite outgrowth inhibitor and an antigen for monoclonal antibody IN-1

The capacity of the adult brain and spinal cord to repair lesions by axonal regeneration or compensatory fibre growth is extremely limited. A monoclonal antibody (IN-1) raised against NI-220/250, a myelin protein that is a potent inhibitor of neurite growth, promoted axonal regeneration and compensatory plasticity following lesions of the central nervous system (CNS) in adult rats. Here we report the cloning of nogo A, the rat complementary DNA encoding NI-220/250. The nogo gene encodes at least three major protein products (Nogo-A, -B and -C). Recombinant Nogo-A is recognized by monoclonal antibody IN-1, and it inhibits neurite outgrowth from dorsal root ganglia and spreading of 3T3 fibroblasts in an IN-1-sensitive manner. Antibodies against Nogo-A stain CNS myelin and oligodendrocytes and allow dorsal root ganglion neurites to grow on CNS myelin and into optic nerve explants. These data show that Nogo-A is a potent inhibitor of neurite growth and an IN-1 antigen produced by oligodendrocytes, and may allow the generation of new reagents to enhance CNS regeneration and plasticity.     

Market timing using combined forecasts and machine learning

Successful market timing strategies depend on superior forecasting ability. We use a sentiment index model, a kitchen sink logistic regression model, and a machine learning model (least absolute shrinkage and selection operator, LASSO) to forecast 1‐month‐ahead S&P 500 Index returns. In order to determine how successful each strategy is at forecasting the market direction, a “beta optimization” strategy is implemented. We find that the LASSO model outperforms the other models with consistently higher annual returns and lower monthly drawdowns.     

Lung cancer susceptibility locus at 5p15.33

We carried out a genome-wide association study of lung cancer (3,259 cases and 4,159 controls), followed by replication in 2,899 cases and 5,573 controls. Two uncorrelated disease markers at 5p15.33, rs402710 and rs2736100 were detected by the genome-wide data (P = 2 x 10(-7) and P = 4 x 10(-6)) and replicated by the independent study series (P = 7 x 10(-5) and P = 0.016). The susceptibility region contains two genes, TERT and CLPTM1L, suggesting that one or both may have a role in lung cancer etiology.     

A cooperative microRNA-tumor suppressor gene network in acute T-cell lymphoblastic leukemia (T-ALL)

The importance of individual microRNAs (miRNAs) has been established in specific cancers. However, a comprehensive analysis of the contribution of miRNAs to the pathogenesis of any specific cancer is lacking. Here we show that in T-cell acute lymphoblastic leukemia (T-ALL), a small set of miRNAs is responsible for the cooperative suppression of several tumor suppressor genes. Cross-comparison of miRNA expression profiles in human T-ALL with the results of an unbiased miRNA library screen allowed us to identify five miRNAs (miR-19b, miR-20a, miR-26a, miR-92 and miR-223) that are capable of promoting T-ALL development in a mouse model and which account for the majority of miRNA expression in human T-ALL. Moreover, these miRNAs produce overlapping and cooperative effects on tumor suppressor genes implicated in the pathogenesis of T-ALL, including IKAROS (also known as IKZF1), PTEN, BIM, PHF6, NF1 and FBXW7. Thus, a comprehensive and unbiased analysis of miRNA action in T-ALL reveals a striking pattern of miRNA-tumor suppressor gene interactions in this cancer.     

Sequence variant on 8q24 confers susceptibility to urinary bladder cancer

We conducted a genome-wide SNP association study on 1,803 urinary bladder cancer (UBC) cases and 34,336 controls from Iceland and The Netherlands and follow up studies in seven additional case-control groups (2,165 cases and 3,800 controls). The strongest association was observed with allele T of rs9642880 on chromosome 8q24, 30 kb upstream of MYC (allele-specific odds ratio (OR) = 1.22; P = 9.34 x 10(-12)). Approximately 20% of individuals of European ancestry are homozygous for rs9642880[T], and their estimated risk of developing UBC is 1.49 times that of noncarriers. No association was observed between UBC and the four 8q24 variants previously associated with prostate, colorectal and breast cancers, nor did rs9642880 associate with any of these three cancers. A weaker signal, but nonetheless of genome-wide significance, was captured by rs710521[A] located near TP63 on chromosome 3q28 (allele-specific OR = 1.19; P = 1. 15 x 10(-7)).