Regime switching dynamics in credit default swaps: Evidence from smooth transition autoregressive model

This paper investigates the dynamics of credit default swap (CDS) spread. We first find auto-correlations and cross-correlations of the CDS series and the CDS average by employing detrended cross-correlation analysis (DCCA). We then employ smooth transition autoregressive (STAR) models to characterize the regime switching behavior of 28 US corporate CDS series from January 2007 through October 2009. In each case, we find clear evidence for transitions between low-price and high-price regimes. The threshold estimations of the STAR model effectively differentiate the price regimes, where the first transition consistently coincides with the explosion of the crisis in late 2008.     

Empirical fractal geometry analysis of some speculative financial bubbles

Empirical evidence of a multifractal signature during increasing of a financial bubble leading to a crash is presented. The April 2000 crash in the NASDAQ composite index and a time series from the discrete Chakrabarti–Stinchcombe model for earthquakes are analyzed using a geometric approach and some common patterns are identified. These patterns can be related the geometry of the rising period of a financial bubbles with the non-concave entropy problem.     

From the currency rate quotations onto strings and brane world scenarios

In the paper, we study the projections of the real exchange rate dynamics onto the string-like topology. Our approach is inspired by the contemporary movements in the string theory. The string map of data is defined here by the boundary conditions, characteristic length, real valued and the method of redistribution of information. As a practical matter, this map represents the detrending and data standardization procedure. We introduced maps onto 1-end-point and 2-end-point open strings that satisfy the Dirichlet and Neumann boundary conditions. The questions of the choice of extra-dimensions, symmetries, duality and ways to the partial compactification are discussed. Subsequently, we pass to higher dimensional and more complex objects. The 2D-Brane was suggested which incorporated bid-ask spreads. Polarization by the spread was considered which admitted analyzing arbitrage opportunities on the market where transaction costs are taken into account. The model of the rotating string which naturally yields calculation of angular momentum is suitable for tracking of several currency pairs. The systematic way which allows one suggest more structured maps suitable for a simultaneous study of several currency pairs was analyzed by means of the Gâteaux generalized differential calculus. The effect of the string and brane maps on test data was studied by comparing their mean statistical characteristics. The study revealed notable differences between topologies. We review the dependence on the characteristic string length, mean fluctuations and properties of the intra-string statistics. The study explores the coupling of the string amplitude and volatility. The possible utilizations of the string theory approach in financial markets are slight.     

Does pop music exist? Hierarchical structure in phonographic markets

I find a topological arrangement of assets traded in phonographic markets which has associated a meaningful economic taxonomy. I continue using the Minimal Spanning Tree and the correlations between assets, but now outside the stock markets. This is the first attempt to use these methods on phonographic markets where we have artists instead of stocks. The value of an artist is defined by record sales. The graph is obtained starting from the matrix of correlation coefficients computed between the world’s most popular 30 artists by considering the synchronous time evolution of the difference of the logarithm of weekly record sales. This method provides the hierarchical structure of the phonographic market and information on which music genre is meaningful according to customers. Statistical properties (including the Hurst exponent) of weekly record sales in the phonographic market are also discussed.     

The diagnostic accuracy of MRI for the detection of partial- and full-thickness rotator cuff tears in adults

This study assessed the diagnostic test accuracy of magnetic resonance imaging (MRI) in the detection of partial- and full-thickness rotator cuff tears in the adult population. A systematic review was conducted of the following electronic databases: Cochrane Central Register of Controlled Trials, Medline, Embase, CINAHL, AMED, ISI Web of Science, Current Controlled Trials, National Technical Information Service, the National Institute for Health Research Portfolio, the UK National Research Register Archive and WHO International Clinical Trials Registry Platform database and reference lists of articles. All studies assessing the sensitivity and/or specificity of MRI for adult patients with suspected rotator cuff tear where surgical procedures were the reference standard were included in the study. A meta-analysis was performed to calculate pooled sensitivity, specificity, likelihood and diagnostic odds ratio values, and summary receiver operating characteristic plots were constructed. Forty-four studies were included. These included 2751 shoulders in 2710 patients. For partial-thickness rotator cuff tears, the pooled sensitivity and specificity values were 0.80 [95% confidence interval (CI): 0.79-0.84] and 0.95 (95% CI: 0.94-0.97), respectively. For full-thickness tears, the sensitivity and specificity values were 0.91 (95% CI: 0.86-0.94) and 0.97 (95% CI: 0.96-0.98), respectively. While there was no substantial difference in diagnostic test accuracy between MRIs reviewed by general radiologists and those reviewed by musculoskeletal radiologists, higher-field-strength (3.0 T) MRI systems provided the greatest diagnostic test accuracy.     

Vague集信息熵测量及其应用

引入了区别于现有文献的Vague集信息熵和Vague集的关联熵的概念,给出了一种改进的测量方法,并讨论了它们之间的关系。进而,我们揭示了Vague集的熵和Fuzzy集的熵之间的关系,并分析了本文所定义熵的意义。最后,讨论了这种关联熵在模糊识别和医疗诊断上的应用。     

地震CT与FBG传感器技术在隧道结构诊断中的应用

针对飞鱼泽隧道的上行线二衬拱顶靠档墙处出现裂缝,经地震CT技术查清隧道上所覆盖岩体的工程地质结构结果表明,沿隧道轴向存在三个岩体破碎带,其中在小里程入口段,岩体完整性较差。在隧道病害治理和隧道健康监测中,经光纤Bragg光栅（FBG）传感器的监测结果表明,松散破碎岩体的地质情况得到了相应的加固。因此,地震CT和FBG两者的检测结论是相互印证的。     

Selective In Situ Analysis of Mature microRNAs in Extracellular Vesicles Using a DNA Cage-Based Thermophoretic Assay

Mature microRNAs (miRNAs) in extracellular vesicles (EVs) are involved in different stages of cancer progression, yet it remains challenging to precisely detect mature miRNAs in EVs due to the presence of interfering RNAs (such as longer precursor miRNAs, pre-miRNAs) and the low abundance of tumor-associated miRNAs. By leveraging the size-selective ability of DNA cages and polyethylene glycol (PEG)-enhanced thermophoretic accumulation of EVs, we devised a DNA cage-based thermophoretic assay for highly sensitive, selective, and in situ detection of mature miRNAs in EVs with a low limit of detection (LoD) of 2.05 fM. Our assay can profile EV mature miRNAs directly in serum samples without the interference of pre-miRNAs and the need for ultracentrifugation. A clinical study showed that EV miR-21 or miR-155 had an overall accuracy of 90 % for discrimination between breast cancer patients and healthy donors, which outperformed conventional molecular probes detecting both mature miRNAs and pre-miRNAs. We envision that our assay can advance EV miRNA-based diagnosis of cancer.     

Functionalization of bismuth sulfide nanomaterials for their application in cancer theranostics

Multifunctional bismuth sulfide (Bi₂S₃) nanomaterials exhibit significant potential as nanomedicines for the diagnosis and treatment of cancer. These nanomaterials act as excellent photothermal agents and radiation sensitizers for the treatment of tumors, and they can also act as contrast agents for computed tomography (CT) imaging, photoacoustic imaging (PA), and other forms of imaging to provide real-time tumor monitoring and testing guidance. Compared with other nanomaterials, Bi₂S₃ nanomaterials can readily adapt to different applications by virtue of the fact that they can be easily functionalized. However, these nanomaterials have some limitations that cannot be ignored and need to be addressed, such as poor biocompatibility, toxicity, and low chemical stability. It is widely believed that appropriate functionalization of Bi₂S₃ nanomaterials could remedy such defects and significantly improve performance. This review summarizes the ways in which Bi₂S₃ nanomaterials can be functionalized and discusses their applications in cancer theranostics over the last few years, focusing particularly on imaging and therapy. We also discuss issues relating to how Bi₂S₃ nanomaterials can be analyzed, including how we might be able to use these systems to inhibit and treat tumors and how current limitations might be overcome to improve treatment efficacy. Finally, we hope to provide inspiration and guidance as to how we might create a more optimized multifunctional nano-system for the diagnosis and treatment of tumors.     

适配体功能化DNA纳米生物传感器应用研究进展EI北大核心CSCD

适配体功能化DNA纳米结构是构建新型生物传感器的理想材料,为临床诊断、食品安全、环境监测等领域提供了材料基础。本文介绍了核酸适配体在功能化DNA纳米结构中的作用,论述了适配体功能化DNA纳米结构的构建方法,以及其在基于固定化和构象开关的电化学生物传感器的最新应用研究。本文为适配体功能化DNA生物传感器的构建提供了制备方法以及生物传感策略等方面的参考,并展望了以适配体功能化DNA纳米结构为材料的生物传感器的应用前景。