A New Mean Reversion Model of Close-End Fund

On the basis of fractal theory, one of the nonlinear theories, this paper studies the validity of Chinese fund market fractal time sequence through Hurst exponent, calculates the H value and proposes a new close-end fund mean reversion model. Meanwhile, this paper validates the mean reversion time sequence for consecutive 54 week data of fund market. The result indicates that this model can effectively prove that Chinese close-end fund market follows the biased random walk. The research also proves that the fund discount does have mean reversion tendency and averagely the fund with high discount has a higher excess yield than that of the fund with low discount. The mean excess yield and the ratio between discount rate deviation and standard deviation demonstrate a descending relationship. The optimum investment period based on ＂mean reversion＂ is one month. Consequently this model provides a new arbitrage method through the discount of close-end fund.

Enantio-selective preparation of (S)-1-phenylethanol by a novel marine GDSL lipase MT6 with reverse stereo-selectivity

We previously functionally characterized a novel marine microbial GDSL lipase MT6 and identified that the stereo-selectivity of MT6 was opposite to that of other common lipases in trans-esterification reactions.Herein,we have investigated the use of MT6 in stereo-selective biocatalysis through direct hydrolysis reactions.Notably,the stereo-selectivity of MT6 was also demonstrated to be opposite to that of other common lipases in hydrolysis reactions.Parameters,including temperature,organic co-solvents,pH,ionic strength,catalyst loading,substrate concentration,and reaction time,affecting the enzymatic resolution of racemic 1-phenylethyl acetate were further investigated,with the e.e.of the final（S）-l-Phenylethanol product and the conversion being 97%and 28.5%,respectively,after process optimization.The lengths of side chains of 1-phenylethyl esters greatly affected the stereo-selectivity and conversion during kinetic resolutions.MT6 is a novel marine microbial GDSL lipase exhibiting opposite stereo-selectivities than other common lipases in both trans-esterification reactions and hydrolysis reactions.

Micro- and nanoporous materials capable of absorbing solvents and oils reversibly： the state of the art

Treatment of petroleum spills and organic solvent pollution in general is an important issue; several techniques are under development to remove oil from water. The use of absorbents is one of the most common techniques to tackle this problem. These absorbents can be classified based on their characteristics of recyclability into irreversible and reversible ones. In this review, we discuss the application of several materials as oil absorbents, according to their classification and characteristics such as hydrophobicity, surface area and oil absorption capacity. Also, the fabrication methods for some materials are presented and analyzed.

Neuroprotective effects of human telomerase reverse transcriptase on beta-amyloid fragment 25-35-treated human embryonic cortical neurons

BACKGROUND： Numerous current studies have suggested that human telomerase reverse transcriptase （hTERT） gene has neuroprotective effects and can inhibit apoptosis induced by various cytotoxic stresses; however, the mechanism of action remains unknown. OBJECTIVE： To evaluate the neuroprotective effects and possible mechanism of action of hTERT gene transfection in human embryonic cortical neurons treated with beta-amyloid fragment 25-35 （AI325-35）. DESIGN, TIME AND SETTING： The randomized, controlled and molecular biological studies were performed at the Department of Anatomy and Brain Research, Zhongshan School of Medicine, Sun Yat-sen University, China, from September 2005 to June 2008. MATERIALS： AdEasy-1 Expression System was gifted by Professor Guoquan Gao from Sun Yat-Sen University, China. Human cortical neurons were derived from 12-20 week old aborted fetuses, obtained from the Guangzhou Maternal and Child Health Hospital, China. Mouse anti-Odk5 and mouse anti-p16 monoclonal antibodies （Lab Vision, USA）, and mouse anti-hTERT monoclonal antibody （Epitomics, USA）, were used in this study. METHODS： （1） Recombinant adenovirus vectors, encoding hTERT （Ad-hTERT） and green fluorescent protein （Ad-GFP）, were constructed using the AdEasy-1 Expression System. Human embryonic cortical neurons in the Ad-hTERT group were transfected with Ad-hTERT for 1-21 days. Likewise, human embryonic cortical neurons in the Ad-GFP group were transfected with Ad-GFP for 1-21 days. Human embryonic cortical neurons in the control group were cultured as normal. （2） Human embryonic cortical neurons in the Ad-hTERT group were treated with 10 pmol/L Aβ25-35 for 24 hours. Normal human embryonic cortical neurons treated with 10 pmol/Lβ25.35 for 24 hours served as a model group. Human embryonic cortical neurons in the Ad-GFP and control groups were not treated with Aβ25-35. MAIN OUTCOME MEASURES： Expression of hTERT in human embryonic cortical neurons was evaluated by immunocytochemical staining and Western blot assay. Telomerase activity was measured using a PCR-based telomeric repeat amplification protocol （TRAP） ELISA kit. Neural activity in human embryonic cortical neurons was examined by MTT assay; apoptosis was measured using TUNEL assay; and Cdk5 and p16 protein expressions were measured by Western blot. RESULTS： Expression of hTERT protein was significantly increased and peaked at day 3 post-transfection in the Ad-hTERT group. No hTERT expression was detected in the Ad-GFP and control groups. Telomerase activity was significantly greater in the Ad-hTERT group compared with the Ad-GFP and control groups （P 〈 0.01）. Compared with the control group, cell activity was significantly decreased （P 〈 0.05）, and cell apoptotic rate, Cdk5 and p16 expression were significantly increased （P 〈 0.01） in the model group. Compared with the model group, cell activity was increased in the Ad-hTERT group, and peaked at day 3 post-transfection （P 〈 0.05）. Neuroprotective effects also peaked at day 3 post-transfection; and the apoptotic rate, Cdk5 and p16 expression significantly decreased （P 〈 0.01）. CONCLUSION： Expression of hTERT in human embryonic cortical neurons can relieve Aβ25-35-induced neuronal apoptosis. The possible mechanism by which hTERT produces these neuroprotective effects may be associated with inhibition of Cdk5 and p16 expression.

一种对K-means算法的改进

数据聚类是一个功能强大的技术,它能够把数据特征相似的对象划分为一类,但是并不是所有的聚类算法的实现都能产生相同的聚类结果;并且K均值算法的结果很大程度上依赖它的初始中心的选择;提出了一种新颖的关于K均值初始中心选择的策略;该算法是基于反向最近邻(RNN)搜索,检索一个给定的数据集,其最近的邻居是一个给定的查询点中的所有点;使用这种方法计算初始聚类中心结果发现是非常接近聚类算法所需的迭代聚类中心;对提出的算法应用到K均值聚类中给予了证明;用几种流行的数据集的实验结果表明了该算法的优点。

Preparation and Characterization of Cathode Materials La_(0.7)Sr_(0.3-x)Ca_xCo_(0.9)Fe_(0.1)O_(3-δ) by Reverse Titration Co-Precipitation Method for ITSOFC

The precursors of La0.7Sr0.3-xCaxCo0.9Fe0.1O3-δ(LSCCF, x=0.05, 0.10, 0.15, 0.20) as the cathode materials for intermediate temperature solid oxide fuel cell (ITSOFC) were prepared by reverse titration co-precipitation method with metal-nitrates as starting materials and mixed alkali (NaOH and Na2CO3) as a precipitating agent. The formation process of LSCCF from the precursors was monitored by TG-DSC, and the crystal structure and particles morphology of the precursors which were calcined at 600, 800, 1000 ℃ for 3 h were characterized using XRD, SEM technologies. Compared with the solid state reaction of constituent oxides, when the pH value of the precipitating solution was in the range of 9.1～9.5, the LSCCF powders from the precursors caclined at 800 ℃ for 3 h had high purity, homogeneous and single perovskite phase. The electrical conductivity of the LSCCF samples sintered at 1200 ℃ for 3 h, which was measured as a function of temperatures from 100 to 800 ℃ by DC four-probe method in air, decreased with x from 0.05 to 0.20. The value of electrical conductivity was almost equal because of Ca2+, Sr2+ co-dopant resulting in the 'mix effect' while x=0.10 or 0.15. The electrical conductivity of all doped samples was higher than 100 S·cm-1 at intermediate temperatures from 500 to 800 ℃, and there was good compatibility between the LSCCF cathode and Ce0.8Sm0.2O2 electrolyte.

Differential interformational velocity analysis as an effective direct hydrocarbon indicator under velocity reversal conditions,an example from the anomalously high temperature and over-pressured DF1-1 Gas Field in the Yinggehai Basin,South China Sea

In the DF1-1 Gas Field in the Yinggehai Basin, South China Sea, the velocity-depth plot and velocity spectra show significant variations from a linear trend, exhibiting a distinct reversal phenomenon. Velocity parameters derived from velocity spectral analysis of the seismic data and sonic logs indicate that the interval velocity reverses below 2,100 m (2.2 s two-way time (TWT)) in the DF1-1 Gas Field. Some direct hydrocarbon indicators (DHIs) models developed for the shallow strata cannot be simply applied to the moderately to deeply buried strata for direct exploration target recognition because the velocity reversal has caused the middle-deep gas reservoirs to exhibit a moderate or weak seismic amplitude. The hydrocarbon indicator method of “Differential Interformational Velocity Analysis (DIVA)” with the aid of other hydrocarbon indicating techniques was employed to effectively identify DHIs in the middle-deep strata under velocity inversion. The result has shown that the DIVA technique can be effectively used as a DHI in both the shallow and the middle-deep strata in the study area with the shallow strata characterized by Type I DIVA anomaly and the middle-deep strata characterized by the Type II DIVA anomaly.

Asymmetric Mean Annual Temperature Wavelets Surface Air Layer of Berlin for 1701-2021

The regularities of the dynamics of the average annual temperature of Ber­lin from 1701 to 2021 are revealed.A total of 65 wavelets were received.The temperature has a high quantum certainty,and the change in the aver­age annual temperature of Berlin was identified by a model that contains only two components for prediction.The basis of the forecast at 320 years makes it possible to look into the future until the year 2340.The forecast confirms the conclusions made in the CMIP5 report on global warming.With an increase in the number of components in the model up to five,the forecast is possible only until 2060.Therefore,the model with only two components is workable.The trend is characterized by a modified Man­delbrot equation showing exponential growth with a high growth rate of 1.47421.The wave equation also has an amplitude in the form of the Man­delbrot law(in mathematics,the Laplace law,in biology,the Zipf-Pearl law,in econometrics,the Pareto law),when the exponential growth activity is equal to 1.For 1701,the period of oscillation was 2×60.33333≈120.7 years.By 2021,the period decreased and became equal to 87.6 years.The trend is such that by 2340 the period of oscillation will decrease to 30.2 years.Such an increase in fluctuations indicates an imbalance in climate disturbances in temperature in Berlin.For Berlin,the last three years are characterized by sharp decreases in the average annual temperature from 11.8℃ to 10.5℃,i.e.by 12.4% in 2021.Therefore,the forecast is still unstable,as a further decrease in the average annual temperature of Berlin in the near future may change the picture of the forecast.

健听成年人全方向水平声源定位能力初步研究

目的利用360°全方向24和36声源测试设备,初步探讨健听中青年和健听老年前期-老年人水平声源定位特点。方法选取2021年4月至2021年9月中国人民解放军总医院耳鼻喉科收治的43例健听成年受试者为研究对象,其中男性22例,女性21例;根据年龄分为中青年组(21~49岁)20例和老年前期-老年组(50~72岁)23例。两组分别给予纯音听阈测试、全方向24声源(间隔15°)和36声源(间隔10°)水平声源定位(sound localization,SL)能力评估。给声强度60 dB HL,给声刺激为1 kHz啭音,通过计算均方根误差(root mean square,RMS)、平均绝对误差(mean absolutely error,MAE)等评估受试者的声源定位能力。结果24声源老年前期-老年组MAE、RMS均值高于中青年组的MAE、RMS均值,差异有统计学意义(P<0.05);36声源老年前期-老年组MAE、RMS高于中青年组的MAE、RMS,差异无统计学意义(P>0.05)。24声源和36声源前场MAE和RMS均高于后场的MAE和RMS,前后场的MAE和RMS比较,差异有统计学意义(P<0.01);左右场的MAE、RMS比较,差异无统计学意义(P>0.05)。24声源前后混淆比例为7.73%,36声源前后混淆比例为15.42%;24声源和36声源均为正前方的声源定位准确度最差;老年前期-老年组前后混淆的比例高于中青年组,差异无统计学意义(P>0.05)。结论健听老年前期-老年人全方向24声源和36声源水平定位能力,相比健听中青年组有所下降。左右场的定位准确度高,前后场的定位准确度低,正前方定位准确度最低。全方向水平声源定位能力的测试结果与扬声器数量有关,且反应趋势具有一致性。

针对顶点策略优化的三维模型可逆数据隐藏算法

随着3D打印技术和云计算的普及发展,三维模型的数据安全和隐私安全日益受到重视,研究模型无损恢复和存储海量数据的隐藏方法具有重要意义。基于此,以三维网格模型为载体,提出一种顶点策略优化的可逆数据隐藏方法。首先,对网格模型顶点进行划分,在全邻域中生成新的重心集合,根据改进的预测策略预测所有顶点集合的MSB以确定最大嵌入位;其次,在接受端应用顶点处拉普拉斯算子得到光滑恢复模型;最后,采用平均曲率可视化分析。为证明该算法的有效性,选取不同大小的网格模型与其他传统算法的嵌入率、SNR以及恢复模型进行对比。结果表明,该算法不仅提高了嵌入率,还在保留恢复模型局部细节特征的同时有效去除噪声,提高了模型恢复质量和视觉效果,进一步达到数据隐私安全的目的。

基于改进麻雀搜索算法的K-means聚类

针对传统K-means聚类算法依赖初始解、易陷入局部最优等问题,提出了一种基于改进麻雀搜索算法的K-means聚类.首先,将分数阶微积分引入麻雀算法,用自适应分数阶阶次对麻雀进行位置更新,提高算法的收敛精度;其次,对麻雀种群进行精英反向学习,增强种群多样性,扩大搜索区域范围;然后,对麻雀的位置进行自适应t分布变异,避免算法陷入局部最优;最后,将提出的改进算法在8个基准测试函数中进行性能验证,并应用于K-means聚类.对UCI数据集进行聚类仿真实验,结果表明基于改进麻雀搜索算法的K-means聚类可有效提高聚类质量和算法稳定性.

外生冲击与房地产真实价格波动——对1998-2003年中国31省（市、区）的实证研究

文章首先根据经济学模型界定了两个重要指标:自相关系数与收敛系数.认为不同的外生冲击对这两个系数有不同的影响,而它们决定了房地产真实价格波动形态的差异.在此基础上,文章利用1998～2003年中国31个省(市、区)的面板数据对中国房地产市场进行了实证研究,其结论是,在真实人均可支配收入和真实建筑成本较高、真实税后住宅抵押贷款利率较低的地区有较大的自相关系数和较小的收敛系数,从而房地产真实价格具有更大的波动性.为使房地产真实价格在均衡价格附近平稳运行,降低开发成本和提高消费者购买成本能收到较好的效果.

血细胞压积与平均血红蛋白浓度的可见-近红外光谱无创检测

血细胞压积和平均血红蛋白浓度的检测对于心脑血管疾病以及贫血等疾病的预防和治疗起着非常重要的作用,为了能够无创、准确的对血细胞压积和平均血红蛋白浓度进行检测,本研究提出了一种基于光谱技术的检测方法。经解剖学研究表明,在微循环中,血流变的异常以及血液粘稠度的改变均能引起舌象的变化,即舌象和血液成分之间存在一定的相关性,所以本研究通过采集240例志愿者舌尖反射光谱,同时拍摄志愿者舌体图片和记录生化分析结果。在进行数学建模前,首先将240例志愿者随机分为校正集和验证集,运用偏最小二乘分别建立数学模型,校正集预测值和生化分析真实值之间相关系数分别为0.998和0.938,运用所建数学模型对验证集未知样本进行预测,验证集未知样本的预测结果与生化分析真实值之间相关系数分别为0.979和0.883,平均相对误差分别为1.65%和1.88%,均方根误差分别为4.066和4.139,由实验结果可见,所建立的模型可以较好的对HCT和MCHC进行预测,同时实验结果也表明近红外光谱分析结合偏最小二乘方法有可能能够为血细胞压积和平均血红蛋白浓度的检测提供一种无创的检测方法。

时变理性预期假说与过度反应假说——基于ANST-GARCH模型的国际证券市场实证检验

基于ANST-GARCH模型,我们利用美国、英国、日本和中国证券市场数据实证检验了时变理性预期假说,发现国际证券市场普遍存在非对称均值回归特征,非对称性源自投资主体对坏消息的过度反应和对好消息的反应不足,过度反应假说成立。同时,除日本以外的市场风险补偿具有时变特点,但预期收益与风险的正相关在利空消息冲击下并不成立,因此,结论不支持时变理性预期假说。

红细胞平均体积联合葡萄糖-6-磷酸脱氢酶活性测定在地中海贫血初筛中的价值研究

目的探讨红细胞参数中红细胞平均体积(MCV)与葡萄糖-6-磷酸脱氢酶(G6PD)活性测定在地中海贫血(地贫)初筛实验中的联合应用价值。方法采用聚合酶链式反应及反向点杂交技术对229例孕妇的血标本进行基因检测(地贫组163例,对照组66例),采用速率法检测G6PD活性,采用鞘流电阻抗法检测MCV,将单项、两项并联和串联结果与基因诊断(金标准)的地贫结果比较,并进行统计分析。结果 MCV、G6PD、两项并联和两项串联诊断地贫的灵敏度分别为99.4%、37.4%、99.4%和37.4%,特异度分别为47.0%、93.9%、43.9%和97.0%。结论在地贫的初筛试验中,MCV与G6PD活性并联的价值与MCV单项相近。但两项串联应用,可提高诊断地贫的特异度。

非对称均值回归与金融危机形成机理——基于ANST-GARCH模型的实证研究

资产价格向内在价值回归的过程具有必然性和非对称性特征,金融危机的形成就是资产泡沫积累后的快速回归均值的过程,即资产泡沫快速破裂现象。本文以股票市场为例,使用ANST-GARCH模型对世界几个最主要股票指数进行实证检验,结果表明这些股价指数都存在着显著的非对称回归现象,利空消息冲击下的均值回归速度要比利好信息冲击下的均值回归速度快,即负的回归快于正的回归。金融危机正是这种非对称均值回归的特殊表现形式。

股指期货的数据频率对统计套利绩效的影响研究--基于动态预测区间的择时交易机制

为了研究股指期货的数据频率对统计套利的绩效影响,本文提出了动态预测区间的择时交易机制。在实证检验中分别运用OLS恒定波动策略,GARCH时变波动策略与之比较。研究结果表明,在样本区间内外,动态预测区间模型各项指标均是最好的。其次,在确保交易过程中发出的信号始终处于有效状态的情况下,随着使用的数据频率趋向高频,可套利次数增多,同时持有期的收益率升高,而单次套利的最大回撤比例也有增加,说明采用高频数据套利将会牺牲一部分收益能力的稳定性来换取绝对收益量的增加。

回流型内燃波转子过渡段与燃料填充段耦合特性研究

为了在回流型内燃波转子进气过渡段内形成高质量的燃料分布,提出一种新型液态燃料喷注结构。采用数值模拟方法,模拟了不同喷油孔喷射位置与射流角度下液态燃料的填充效果,并结合液滴驻留时间、索太尔平均直径以及燃料分布不均匀度,分析了喷油孔喷射位置和射流角度对过渡段与燃料填充段耦合特性的影响规律。研究结果表明,喷射位置为40 mm和60 mm时,在进气过渡段出口截面可以形成相对均匀的燃料分布;增大射流角度后,弯管掺混区形成了较大尺度和较强强度的涡流,使得出口截面燃料分布更加均匀。

基于ARMA-GARCH模型的恒指隐含波动率指数预测及其在期权交易中的应用

基于ARMA-GARCH模型,并结合均值回归效应,溢出效应和周内效应,本文研究了恒指隐含波动率指数(VHSI)能否被预测及预测是否有助于期权投资实践的问题.研究结果验证了香港股市具有均值回归的特性,标准普尔500指数对恒指隐含波动率指数有明显的溢出效应.此外,恒指隐含波动率指数呈现出周一上涨,周五下跌的特征,具有明显的周内效应.最后,本文运用ARMA-GARCH模型对恒指隐含波动率指数进行预测,并结合实际的市场数据做了期权交易模拟.结果显示,ARMA-GARCH模型比ARMA模型更适合对恒指隐含波动率进行建模;考虑了均值回归效应,溢出效应和周内效应之后,ARMAGARCH模型对恒指隐含波动率指数的预测能力显著提高,并且预测结果有助于期权交易获得较好的收益.

蓝粒小麦花青素合成途径中的查尔酮合酶基因和类黄酮3＇5＇-羟化酶基因3＇末端的克隆和表达分析

采用RT-PCR和RACE方法从蓝粒小麦(Triticum aestivum L.×Thinopyrum ponticum(Podp.)Z.W.Liu et R.R.-C.Wang)发育种子中克隆到两个查尔酮合酶基因(TaCHS.tl，TaCHS．wl)，分别编码394个氨基酸，二者核苷酸和氨基酸序列的同源性分别为96．0％和98．9％；而且克隆到一个类黄酮3'5’．羟化酶基因(F3'5'H)3’-末端。分别从长穗偃麦草(Thinopyrum ponticum(Podp．)Z．W．Liu et R．R．-C．Wang)、蓝粒小麦、白粒小麦和中国春基因组中分离到查尔酮合酶基因(CHS)的全长序列(ThpCHS.tg TaCHS．wg，TaCHS．csg)，它们的核苷酸序列之间具有很高的同源性，且均含有一个内含子(intron)，序列差异主要在内含子。通过DNA序列比较，发现一个CHS与亲本之一的长穗偃麦草基因组同源性达100％，一个CHS与另一白粒亲本基因组同源性达99％，表明来自于父、母本的CHS在蓝粒发育的种子中均表达。Southerm杂交结果表明CHS在小麦中的拷贝数至少有4个，不同颜色的蓝粒小麦、白粒小麦间拷贝数基本一致，但都与长穗偃麦草有差异，根据以上结果初步判定CHS在蓝粒小麦中属于一个多基因家族。Reverse Northern分析表明CHS在开花后15d发育的蓝粒小麦中具有较强的表达；花后21d F3'5'H和DFR的转录本积累显著高于CHS，基本上检测不到CHS的表达。这三个基因在蓝粒小麦中的表达顺序与其他植物花青素合成途径中的基因表达次序一致：ChS先于F3'5'H，F3'5'H先于DFR。实验还表明F3'5'H和DPR在幼叶中表达也较强，CHS仅在发育种子中表达，具有组织特异性。花后21d，F3’5’H在白粒、蓝粒小麦和中国春种子中均强烈表达，蓝粒小麦CHS和DFR转录本比白粒小麦多。因此，认为在蓝粒小麦中存在花青素生物合成途径，在蓝色色素形成过程中，该途径中的结构基因受到调节基因的调控。