核磁共振代谢组学数据的尺度归一化新方法

在核磁共振代谢组学数据预处理中,尺度归一化主要目的是提高特征代谢物信息的权重,减小噪声及无关代谢物信息的影响,从而降低后续模式识别分析的难度. 本文提出一种新的尺度归一化方法,该方法不强调各变量在尺度上的归一,而是在原始数据的基础上,通过提高那些稳定性高、且在不同类别样本中具有显著差异性的变量的权重,以增强与特征代谢物相关的信息. 文中分别采用模拟数据和真实代谢组学数据对新归一化方法的性能进行评估,并与单位方差法(Unit Variance)、变量稳定性(Variable Stability)和尺度缩放法(Level Scaling)等常用的尺度归一化方法做比较. 研究结果表明：新归一化方法能够提高多变量统计模型的预测能力,较好地保留核磁共振谱的分子信息,有助于特征代谢物的识别,并使后续的数据分析结果具有更好的可解释性.     

HMM模型下视频手写签名认证算法研究

为了提高视频手写签名认证的准确率,确保身份认证的严谨性,需要对HMM模型下视频手写签名认证算法进行改进设计。使用当前算法对视频手写签名进行认证时,存在认证判断误差大、效率低的问题。提出基于HMM模型下视频手写签名认证算法。该算法将使用Wacom手写板采集手写签名特征点及压力数据,对采集到的手写签名特征与压力数据进行预处理,消除采集过程中环境和手写板产生的影响,并且规范采集的视频手写签名特征位置、尺寸,提取手写签名特征与压力数据,再以HMM模型对已提取的视频手写签名特征点与压力数据进行认证与计算,确定签名的真实度。实验仿真证明,所提算法提高了视频签名认证的性能。     

Quantum group blind signature scheme without entanglement

In this paper we propose a quantum group blind signature scheme designed for distributed e-voting system. Our scheme combines the properties of group signature and blind signature to provide anonymity of voters in an e-voting system. The unconditional security of our scheme is ensured by quantum mechanics. Without employing entanglement, the proposed scheme is easier to be realized comparing with other quantum signature schemes.     

Molecularly imprinted polymers for selective analysis of chemical warfare surrogate and nuclear signature compounds in complex matrices

This paper describes the preparation and evaluation of molecularly imprinted polymers (MIPs) that display specificity toward diisopropyl methylphosphonate (DIMP) and tributyl phosphate (TBP). Polymer activity was assessed by solid-phase extraction and high-performance liquid chromatography experiments. Both DIMP- and TBP-specific vinylpyridine-based MIPs selectively retained their targets relative to a non-imprinted control. Proof-of-principle experiments demonstrated highly selective analysis of the targets from fortified complex matrix samples (diesel fuel, gasoline, and air extract concentrate). The retained MIP fractions gave near quantitative recovery of the target analytes with very low matrix background content. The same fraction from the control sorbent recovered only about half of the analyte and tended to be less pure.     

硬件复用的内建自测试结构设计

现代数字电路因规模庞大、复杂性高而导致测试困难,系统维护成本较高。内建自测试(Built In Self Test, BIST)是针对该问题的一种有效的可测性设计技术。由于内建自测试是通过在电路内部设计测试生成与分析模块,因此需要消耗额外的硬件资源。通过对测试生成与特征分析模块的结构分析,提出基于硬件结构复用的可重构逻辑块观测器,并基于该模块设计了可重构的内建自测试结构。仿真结果表明,该测试结构通过结构的时分复用,能有效的降低硬件资源消耗,测试逻辑正确有效,测试时间较短。     

Anti-self-dual gravitational metrics determined by the modified heavenly equation

In paper Doubrov and Ferapontov (2010) on the classification of integrable complex Monge–Ampère equations, the modified heavenly (MH) equation of Dubrov and Ferapontov is one of canonical equations. It is well known that solutions of the first and second heavenly equations of Plebañski (1975) and those of the Husain equation in Husain (1994) provide potentials for anti-self-dual (ASD) Ricci-flat vacuum metrics. For another canonical equation, the general heavenly equation of Dubrov and Ferapontov (2010), we had constructed in Malykh and Sheftel (2011) ASD Ricci-flat metric governed by this equation. Thus, the modified heavenly equation remains the only one in the list of canonical equations in Doubrov and Ferapontov (2010) for which such a metric is missing so far. Our aim here is to construct null tetrad of vector fields, coframe 1-forms and ASD Ricci-flat metric for the latter equation. We study reality conditions and signature for the resulting metric. As an example, we obtain a multi-parameter cubic solution of the MH equation which yields a family of metrics with the above properties. Riemann curvature 2-forms are also explicitly presented for the cubic solution.     

Virtual high-throughput screens identifying hPK-M2 inhibitors: Exploration of model extrapolation

Glycolysis with PK-M2 occurs typically in anaerobic conditions and atypically in aerobic conditions, which is known as the Warburg effect. The Warburg effect is found in many oncogenic situations and is believed to provide energy and biomass for oncogenesis to persist. The work presented targets human PK-M2 (hPK-M2) in a virtual high-throughput screen to identify new inhibitors and leads for further study. In the initial screen, one of the 12 candidates selected for experimental validation showed biological activity (hit-rate = 8.13%). In the second screen with retrained models, six of 11 candidates selected for experimental validation showed biological activity (hit-rate: 54.5%). Additionally, four different scaffolds were identified for further analysis when examining the tested candidates and compounds in the training data. Finally, extrapolation was necessary to identify a sufficient number of candidates to test in the second screen. Examination of the results suggested stepwise extrapolation to maximize efficiency.     

Dynamic network reliability modeling under nonhomogeneous Poisson processes

In this paper, we consider a two-state (up and down) network consisting of n links. We study the D-spectrum based dynamic reliability of the network under the assumption that the links are subject to failure according to a nonhomogeneous Poisson process. Several mixture representations are provided for the reliability function of residual lifetime of used networks, under different conditions on the status of the network or its links. These representations enable us to explore the residual reliability of operating networks in terms of the reliability functions of residual lifetimes of upper record values. The distribution function of inactivity time of a network is examined under the condition that the network has failed by inspection time t. Stochastic ordering properties of the residual lifetimes of networks under conditional D-spectra are investigated. Several examples and graphs are also provided to illustrate the established results.     

Characterization of volatile effluents of livestock buildings by solid-phase microextraction

This article presents two examples of the application of SPME to the characterisation of gaseous effluents from animal sheds. In the first example the volatile fraction of swine manure was analysed by solid-phase microextraction combined with gas-phase chromatography-mass spectrometry (SPME-GC-MS). To find the best extraction conditions for volatile components, six types of SPME fibre were tested. Carboxen-PDMS fibre performed best, enabling us to extract and identify 101 compounds of varying polarity and molecular weight. The second example shows that it is possible to concentrate the volatile components in various animal shed atmospheres by simple exposure of a fibre inside the building. Direct injection into a mass spectrometer ionisation source (SPME-MS) of the volatile components thus trapped provided signatures characteristic of the four different animal shed atmospheres studied. The practical simplicity of the SPME-MS method makes it a good candidate for rapid identification and monitoring of animal shed atmospheres.     

The signature of generalized flag manifolds and applications

Let G be a linear algebraic group over C and P be a parabolic subgroup. We determine the signatures of the flag manifold G/P. As an application, we prove that the nonsingular hypersurfaces of degree 2 in CP^n are prime if n satisfies certain conditions.