Implicit Bayesian Inference Using Option Prices

Abstract. A Bayesian approach to option pricing is presented in which posterior inference about the underlying returns process is conducted implicitly via observed option prices. A range of models allowing for conditional leptokurtosis, skewness and time‐varying volatility in returns are considered, with posterior parameter distributions and model probabilities backed out from the option prices. Models are ranked according to several criteria, including out‐of‐sample predictive and hedging performance. The methodology accommodates heteroscedasticity and autocorrelation in the option pricing errors, as well as regime shifts across contract groups. The method is applied to intraday option price data on the S&P500 stock index for 1995. While the results provide support for models that accommodate leptokurtosis and skewness, no one model dominates when all criteria are considered.     

miR-16-5p Is a Stably-Expressed Housekeeping MicroRNA in Breast Cancer Tissues from Primary Tumors and from Metastatic Sites

For quantitative microRNA analyses in formalin-fixed paraffin-embedded (FFPE) tissue, expression levels have to be normalized to endogenous controls. To investigate the most stably-expressed microRNAs in breast cancer and its surrounding tissue, we used tumor samples from primary tumors and from metastatic sites. MiRNA profiling using TaqMan^® Array Human MicroRNA Cards, enabling quantification of 754 unique human miRNAs, was performed in FFPE specimens from 58 patients with metastatic breast cancer. Forty-two (72%) samples were collected from primary tumors and 16 (28%) from metastases. In a cross-platform analysis of a validation cohort of 32 FFPE samples from patients with early breast cancer genome-wide microRNA expression analysis using SurePrintG3 miRNA (8 × 60 K)^® microarrays from Agilent^® was performed. Eleven microRNAs could be detected in all samples analyzed. Based on NormFinder and geNorm stability values and the high correlation (rho ≥ 0.8) with the median of all measured microRNAs, miR-16-5p, miR-29a-3p, miR-126-3p, and miR-222-3p are suitable single gene housekeeper candidates. In the cross-platform validation, 29 human microRNAs were strongly expressed (mean log2-intensity > 10) and 21 of these microRNAs including miR-16-5p and miR-29a-3p were also stably expressed (CV < 5%). Thus, miR-16-5p and miR-29a-3p are both strong housekeeper candidates. Their Normfinder stability values calculated across the primary tumor and metastases subgroup indicate that miR-29a-3p can be considered as the strongest housekeeper in a cohort with mainly samples from primary tumors, whereas miR-16-5p might perform better in a metastatic sample enriched cohort.     

16MnR钢高温疲劳裂纹扩展行为试验研究

对16MnR钢在常温、150℃、300℃和425℃下的疲劳裂纹扩展速率进行了测试和分析,得到了四种温度下的疲劳裂纹扩展规律。结果表明：该材料在150℃和300℃的疲劳裂纹扩展速率比常温和425℃时低,425℃时疲劳裂纹扩展速率最高。     

Research about the Effect of Ultrasonic Impact on the Fatigue Properties of Cruciform Joints of 16MnR Steel

Surface impact treatment was carried out on the cruciform joint weldment of 16MnR steel by using the HJ-II-type ultrasonic impact machine.The ultrasonic impact current is 1.2 A,the impact amplitude is 30?m and ultrasonic impacting time is 30 and 60 min,respectively.Fatigue experiments were carried out for both treated specimen and un-treated specimen by using EHF-EM200K2-070-1A fatigue testing machine.The fatigue fractures were observed with the scanning electron microscope of 6360LA type and the microstructure of ultrasonic impact treating surface layer was analyzed by using high resolution transmission electron microscope of JEM-2100 type.The experimental results show that the microstructure of ultrasonic impact surface layer has been successfully nanocrystallized.The fatigue life of welded cruciform joints of 16MnR steel can be significantly improved through the ultrasonic impact treatment.The main reasons are that the ultrasonic impact treating can reduces the stress concentration in the weld toe,decrease the tensile stress,and even change to compressive stress in the weldment,the grain size in the welded joint can be refined.The longer the impact time,the greater increasing range of fatigue life will be.Compared to the sample without treatment,its fatigue life was increased 210.37%,362.48%,respectively,when the impact time was 30,60 min,respectively.     

压力容器用钢板焊接温度场模拟与验证

针对某公司生产的压力容器用钢16MnR,为了优化焊接工艺参数,能够提供不同焊接工艺条件下的准确温度场,有效地为应力应变场分析做准备,采用ANSYS有限元对60 mm厚板埋弧焊进行温度场数值模拟,并将模拟结果与相同工艺条件下焊接试验结果进行比较验证.结果表明,模拟结果与试验结果基本吻合;试验特征点越接近热源,温度升高越迅速且峰值越高;道间温度随着焊接道次的增多而逐步上升,只有控制道次间温度来获得均匀组织;这对获得优良的焊接构件有着重要的意义.     

Hydralazine逆转胃癌细胞株p16基因甲基化及增强其表达的研究

目的: 通过使用甲基转移酶抑制剂肼屈嗪(Hydralazine)作用于胃癌细胞株BGC-823,观察Hydralazine对MTS1/p16基因启动子区CpG岛甲基化、p16 mRNA、p16蛋白表达及细胞增殖的影响;分析p16基因启动子区CpG岛甲基化与p16基因表达两者间的关系,以此考察胃癌细胞株BGC-823 p16基因的失活机制是否与启动子区CpG岛甲基化有关。方法: 对体外培养的胃癌细胞株BGC-823进行分组实验,实验组加入水溶性的Hydralazine,浓度0、10、30、100 μmol/L,对照组不加Hydralazine,96 h 后对两组分别行甲基化特异性PCR法(MSP)、RT-PCR及Western blot检测,以观察p16基因甲基化状态、mRNA、蛋白表达的变化;应用6种不同浓度的水溶性Hydralazine(0、3、10、30、100、300 μmol/L)处理胃癌细胞BGC-823,72 h 后行MTT检测,以观察对细胞增殖的影响。结果: P16基因在胃癌细胞株BGC-823中,启动子区CpG岛呈高甲基化状态,mRNA及蛋白呈低水平表达。Hydralazine阻断甲基转移酶作用后,p16基因启动子区CpG岛呈去甲基化状态,Hydralazine浓度越高,CpG岛去甲基化越明显。Hydralazine阻断甲基转移酶作用后,用药后p16 mRNA表达较前明显增强(P<0.05)。Hydralazine阻断甲基转移酶作用后,用药后p16蛋白表达较前明显增强(P<0.01)。MTT检测到不同浓度的Hydralazine(0、3、10、30、100、300 μmol/L)对细胞增殖的抑制率差异有统计学意义(P<0.05),其量效关系反映出抑癌基因p16去甲基化程度越高,对胃癌细胞株BGC-823的增殖抑制越显著。结论: P16基因动子区CpG岛甲基化是p16基因失活的重要机制。     

16Mn钢奥氏体动态再结晶及晶粒细化研究

研究了16Mn钢奥氏体动态再结晶、晶粒细化、晶率细化率及γ—α相变后铁素体晶粒大小与变形量ε、变形温度之间的关系。结果显示,奥氏体晶粒细化率和γ→α相变后铁素体晶粒大小都与变形量。之间存在指数函数关系;动态再结晶完成后,奥氏体晶粒平均直径与变形速率温度修正系数Z之间符合线性关系。     

焦化厂污染土壤中多环芳烃降解菌群解析

以苯并[a]芘、苯并[a]蒽、苯并[b]荧蒽、苯并[k]荧蒽、茚并[1,2,3-cd]芘5种较难降解的多环芳烃为碳源和能源,采用富集培养的方法从焦化厂污染的土壤中筛选分离得到50株PAHs降解菌。通过对其16S rRNA基因序列分析,将这些PAHs降解菌分为15个种群,分别属于Sphingomonas(鞘氨醇单胞菌属)、Methylobacterium(甲基杆菌属)、Burkholderia(伯克霍尔德氏菌属)、Rhodococcus(红球菌属)、Bradyrhizobium(慢生根瘤菌属)、Phyllobacterium(叶杆菌属)、Chryseobacterium(金黄杆菌属)、Microbaterium(微杆菌属)8个属,其中优势菌为鞘氨醇单胞菌属。纯菌株降解能力测试表明,培养12 d后,菌株3-6-12降解效果要优于其他菌株,对苯并[a]蒽、苯并[a]芘、苯并[b]荧蒽、苯并[k]荧蒽、茚并[1,2,3-cd]芘的降解率分别可达39.64%、33.52%、38.57%、25.37%、31.17%。实验结果可为多环芳烃污染土壤的生物修复提供高效的降解菌源。     

金属改性的介孔硅材料FSM-16催化苯酚与H_2O_2合成苯二酚

研究了金属改性的介孔硅材料FSM-16在该反应中的催化性能。其中Fe和Cu改性的FSM-16表现出比较好的性能。在Fe-FSM-16的作用下,苯酚的转化率达到27.8%,对苯二酚和邻苯二酚选择性达到96.4%(邻/对=1.8)。FT-IR和XRD表征证明铜离子进入了FSM-16的骨架,并形成了Si—O—Cu键。     

厌氧发酵产氢细菌的分离和鉴定及产氢特性

获得优良的产氢菌株,鉴定并研究其产氢特性,为提高其产氢能力提供基础。对样品进行预处理和葡萄糖梯度驯化处理后,采用厌氧培养技术分离单菌落,进行菌株形态学观察、生理生化试验及16S rDNA分子生物学鉴定,并采用分批式厌氧发酵研究其产氢特性。结果表明:其中产氢最优的菌株FML-C1为肠杆菌属细菌,葡萄糖为其产氢的最优碳源,氮源则以酵母粉和蛋白胨混合最佳,最适生长和产氢温度为35℃,最佳初始pH值为6.0,该条件下菌株的气相末端产物中氢体积分数达56.51%。菌株FML-C1为一株良好的厌氧发酵产氢菌,可进一步优化其产氢工艺,以提高其产氢能力。