A closely packed system of low-mass, low-density planets transiting Kepler-11

When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47?days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation.     

FAS and NF-κB signalling modulate dependence of lung cancers on mutant EGFR

Human lung adenocarcinomas with activating mutations in EGFR (epidermal growth factor receptor) often respond to treatment with EGFR tyrosine kinase inhibitors (TKIs), but the magnitude of tumour regression is variable and transient. This heterogeneity in treatment response could result from genetic modifiers that regulate the degree to which tumour cells are dependent on mutant EGFR. Through a pooled RNA interference screen, we show that knockdown of FAS and several components of the NF-κB pathway specifically enhanced cell death induced by the EGFR TKI erlotinib in EGFR-mutant lung cancer cells. Activation of NF-κB through overexpression of c-FLIP or IKK (also known as CFLAR and IKBKB, respectively), or silencing of IκB (also known as NFKBIA), rescued EGFR-mutant lung cancer cells from EGFR TKI treatment. Genetic or pharmacologic inhibition of NF-κB enhanced erlotinib-induced apoptosis in erlotinib-sensitive and erlotinib-resistant EGFR-mutant lung cancer models. Increased expression of the NF-κB inhibitor IκB predicted for improved response and survival in EGFR-mutant lung cancer patients treated with EGFR TKI. These data identify NF-κB as a potential companion drug target, together with EGFR, in EGFR-mutant lung cancers and provide insight into the mechanisms by which tumour cells escape from oncogene dependence.     

A Pluto-like radius and a high albedo for the dwarf planet Eris from an occultation

The dwarf planet Eris is a trans-Neptunian object with an orbital eccentricity of 0.44, an inclination of 44 degrees and a surface composition very similar to that of Pluto. It resides at present at 95.7 astronomical units (1?AU is the Earth-Sun distance) from Earth, near its aphelion and more than three times farther than Pluto. Owing to this great distance, measuring its size or detecting a putative atmosphere is difficult. Here we report the observation of a multi-chord stellar occultation by Eris on 6 November 2010 UT. The event is consistent with a spherical shape for Eris, with radius 1,163?±?6?kilometres, density 2.52?±?0.05 grams per cm(3) and a high visible geometric albedo, Pv = 0.96(+0.09)(-0.04). No nitrogen, argon or methane atmospheres are detected with surface pressure larger than ～1?nanobar, about 10,000 times more tenuous than Pluto's present atmosphere. As Pluto's radius is estimated to be between 1,150 and 1,200 kilometres, Eris appears as a Pluto twin, with a bright surface possibly caused by a collapsed atmosphere, owing to its cold environment. We anticipate that this atmosphere may periodically sublimate as Eris approaches its perihelion, at 37.8 astronomical units from the Sun.     

搜索引擎日志中"V+N1+N2"型短语研究

搜索引擎用短语词典能够有效地改善和提高信息检索的性能,"V+N1+N2"型结构是一种常见汉语短语结构.本文基于搜狗语料,分别从各组成要素特点、语义特征以及句法功能,对"V+N1+N2"型动词短语和名词短语进行统计分析和相关数据处理.针对不同语义关系,在不改变原语义的条件下,提出了相应的转换模式,为搜索引擎用短语词典的构建提供了理论支撑.     

转炉流程轴承钢连铸坯非金属夹杂物的行为

探讨了BOF-LF-VD-CC流程生产的轴承钢连铸坯非金属夹杂物的物性、分布、特点,并通过示踪剂追踪分析了轴承钢夹杂物的来源,为轴承钢夹杂物的去除,提高转炉流程轴承钢质量提供了依据.研究表明,该生产流程可以获得T[O]的平均值为9.3×10-4%;显微夹杂体积分数为0.031%;>50μm的大型夹杂为1.5 mg/10 kg的洁净度较高的轴承钢连铸坯.夹杂物主要为<5μm的显微夹杂,它的分布特点决定了连铸坯中夹杂物的分布特点,显微夹杂主要是多元素复合脱氧产物与中间包液面二次氧化产物吸附集聚形成的复合物,其次是结晶器液面对钢液的污染,钢包液面影响较小.     

EMF和电导率法对SDS胶束体系热力学性质研究

为深入了解表面活性剂溶液的性质,对其在使用和处理过程中的行为加以控制,在298K恒温下,用Na^＋选择性电极法测量了不同浓度的阴离子表面活性剂十二烷基硫酸钠（SDS）溶液的电动势（EMF）,求出了其临界胶束浓度（Cmc）及反离子结合度,进而获得了反离子与胶束结合的经验平衡常数Kass,实验数据表明,随表面活性剂浓度增大,Kass降低,反离子与胶束表面的结合逐渐弱化,在289～328K测量了SDS溶液的电导率随浓度的变化,求出了不同温度下的Cmc值,发现随温度的变化Cmc曲线存在一个最低点．由Cmc与温度T的关系,计算了胶束化热力学参数△micG^0、△micH^0和△micS^0．结果表明,△micG^0在整个实验范围内均为负值,胶束化过程可以自发进行;△micH^0的值相对于T△micS^0小很多,胶束化过程为熵驱动过程．以上特征参数的确定,可为研究表面活性剂溶液的各种应用以及处理技术提供重要参考．     

实时荧光定量PCR法检测环境假单胞菌属细菌丰度

应用实时荧光定量PCR法,建立了总细菌及假单胞菌属的标准曲线,并以环境样本中假单胞菌属与总细菌的比值反映其细菌丰度.应用该方法评价人工除藻反应器中组合填料、无纺布、弹性填料等介质对太湖水中溶藻细菌之一的假单胞菌属的富集情况.结果显示:该方法对总细菌的检测范围为103~108个基因拷贝/μL(R2=0.997);假单胞菌属的检测范围为1~105个基因拷贝/μL(R2=0.994).对除藻反应器溶藻细菌富集效果的评价显示,所建立的方法能有效检测反应器中填料对该类溶藻细菌的富集程度.初步证明所建立的方法可有效定量假单胞菌属在环境样本中的丰度.     

BioStarM-140s芯片基因信息查询系统的构建及应用

应用生物信息学数据库查询的方法,对B ioS tarM-140s小鼠基因表达芯片上的14 112个基因进行相应注释信息的查询和所对应蛋白质功能的分类.首先参照人类综合型芯片上基因的功能分类,设定了14个蛋白质类别,然后采用V isual C 编程语言,构建了基因信息查询系统.应用该查询系统,进行了网络生物学数据库信息资源的自动直接查询,共搜索到有注释信息的基因12 070个;进一步按照所设定的14个蛋白质类别对12 070个基因进行分类查询,搜索到了与这14个分类相符合的、具有详细蛋白质功能注释信息的基因共1 606个.     

Ordinary language philosophy,explanation, and the historical turn in philosophy of science

Taking a cue from remarks Thomas Kuhn makes in 1990 about the historical turn in philosophy of science, I examine the history of history and philosophy of science within parts of the British philosophical context in the 1950s and early 1960s. During this time, ordinary language philosophy's influence was at its peak. I argue that the ordinary language philosophers' methodological recommendation to analyze actual linguistic practice influences several prominent criticisms of the deductive-nomological model of scientific explanation and that these criticisms relate to the historical turn in philosophy of science. To show these connections, I primarily examine the work of Stephen Toulmin, who taught at Oxford from 1949 to 1954, and Michael Scriven, who completed a dissertation on explanation under Gilbert Ryle and R.B. Braithwaite in 1956. I also consider Mary Hesse's appeal to an ordinary language-influenced account of meaning in her account of the role of models and analogies in scientific reasoning, and W.H. Watson's Wittgensteinian philosophy of science, an early influence on Toulmin. I think there are two upshots to my historical sketch. First, it fills out details of the move away from logical positivism to more historical- and practice-focused philosophies of science. Second, questions about linguistic meaning and the proper targets and aims of philosophical analysis are part and parcel of the historical turn, as well as its reception. Looking at the philosophical background during which so-called linguistic philosophers also had a hand in bringing these questions to prominence helps us understand why.