Search

针对小样本条件下多元时间序列之间的关联分析问题, 提出了一种小样本概率关联度模型。使用样本函数或样本统计量代替样本构造累积经验分布函数并计算概率关联系数。当比较序列样本容量n < 5, 使用样本顺序统计量的经验分布函数计算概率关联系数; 当比较序列样本容量n≥5, 使用Bootstrap方法重抽样扩充样本后再构造经验分布函数计算概率关联系数, 改进了概率关联度模型中关联系数的计算方法, 解决了小样本条件下这一类多元数据关联分析问题。证明了小样本概率关联度模型满足的基本性质, 给出了小样本概率关联分析的基本步骤, 仿真案例和实际应用验证了文中模型的正确性和有效性。

The air-to-ground missile with strapdown seeker may have the problems, including small field of view(FOV), limited overload, and fall angle constraint. To solve the above mentioned problem, a phased guidance scheme is proposed. In this scheme, the attack trajectory is divided into the following six stages, including glided stage, fall angle constraint stage, target acquisition and adjustment stage, terminal guidance stage and blind zone stage. The glided stage is designed to increase range, the terminal fall angle is attained ahead of time at fall angle constraint stage. The aim of target acquisition and adjustment stage is to adjust the missile attitude, so that the target will fall within the FOV of the seeker. It creates good condition to capture the target for strapdown seeker. In the terminal stage, the guidance law of proportional navigation and attitude track are used to fit the needs of FOV constraint and attack accuracy. The simulation result shows that the project trajectory can solve the application of attacking moving targets for air-to-ground missile with strapdown seeker under multi constraints.

Since the electromagnetic (EM) absorbers have wide uses in many military and civilian applications, much effort has been devoted continuously to broadening the absorption bandwidth while making the thickness as thin as possible. In this paper, we present an ultra-wideband metamaterial absorber composed of periodic stepped-structures of magnetic material with a mixture of carbonyl iron powder and resin. The proposed metamaterial absorber features an ultra-thin thickness of only 0.025 wavelength and an ultra-broad operating bandwidth (defined by absorption larger than 90%) from 1.23 to 19 GHz. The ultra-broadband strong absorption is mainly attributed to the giant magnetic loss of the magnetic material, the structure-induced multi-resonances, and the edge diffraction effects of the stepped structures. In addition, good angular performance is observed for all polarizations. Experiments are carried out and are in good agreements with the simulated ones. We also propose a method to further reduce the weight of the structure without affecting much of the overall absorbing performance. The proposed metamaterial absorber has promising prospects in many real-world applications, such as RCS reduction and EM compatibility.

Diffuse scatterings of electromagnetic (EM) waves by thin-thickness metasurfaces have promising prospects in many fields due to their abilities of significantly reducing the backward scatterings of targets. One of the major challenges is to further improve the working bandwidth. Here, we propose a binary geometric phase metasurface with high optical transparency to realize ultra-wideband backward scattering reduction through diffuse scatterings. A multi-layered reflective meta-structure is used as the basic building block while its out-of-phase counterpart is achieved through a geometric rotating operation. The proposed metasurface shows a polarization-insensitive wave-diffusion property with about 10 dB scattering reduction in an ultra-wide frequency band from 3.5 GHz to 16.6 GHz, reaching a fractional bandwidth of 130%. As the experimental demonstration, prototype is fabricated and measured that is in agreement with simulated results. The proposed metasurface provides an efficient way to tailor the exotic scattering features with simultaneously high optical transmittance, which can offer crucial benefits in many practical uses, for example, window stealth applications.

Early detection and treatment are key to delaying the progression of diabetic retinopathy (DR), avoiding loss of vision, and reducing the burden of advanced disease. Our study is aimed at determining if total bilirubin has a predictive value for DR progression and exploring the potential mechanism involved in this pathogenesis. A total of 540 patients with nonproliferative diabetic retinopathy (NPDR) were enrolled between July 2014 and September 2016 and assigned into a progression group (N=67) or a stable group (N=473) based on the occurrence of diabetic macular edema (DME), vitreous hemorrhage, retinal detachment, or other conditions that may cause severe loss of vision following a telephonic interview in August 2019. After further communication, 108 patients consented to an outpatient consultation between September and November 2019. Our findings suggest the following: (1) TBIL were significant independent predictors of DR progression (HR: 0.70, 95% CI: 0.54–0.89, p=0.006). (2) Examination of outpatients indicated that compared to stable group patients, progression group patients had more components of urobilinogen and LPS but a lower concentration of TBIL. The relationship between bilirubin and severe DR was statistically significant after adjusting for sex, age, diabetes duration, type of diabetes, FPG, and HbA1c (OR: 0.70, 95% CI: 0.912–0.986, p=0.016). The addition of serum LPS and/or urobilinogen attenuated this association. This study concludes that total bilirubin predicts an increased risk of severe DR progression. Decreasing bilirubin might be attributed to the increased levels of LPS and urobilinogen, which may indicate that the change of bilirubin levels is secondary to intestinal flora disorder and/or intestinal barrier destruction. Further prospective investigations are necessary to explore the causal associations for flora disorder, intestinal barrier destruction, and DR.

Background A collection of disease-associated data contributes to study the association between diseases. Discovering closely related diseases plays a crucial role in revealing their common pathogenic mechanisms. This might further imply treatment that can be appropriated from one disease to another. During the past decades, a number of approaches for calculating disease similarity have been developed. However, most of them are designed to take advantage of single or few data sources, which results in their low accuracy. Methods In this paper, we propose a novel method, called MultiSourcDSim, to calculate disease similarity by integrating multiple data sources, namely, gene-disease associations, GO biological process-disease associations and symptom-disease associations. Firstly, we establish three disease similarity networks according to the three disease-related data sources respectively. Secondly, the representation of each node is obtained by integrating the three small disease similarity networks. In the end, the learned representations are applied to calculate the similarity between diseases. Results Our approach shows the best performance compared to the other three popular methods. Besides, the similarity network built by MultiSourcDSim suggests that our method can also uncover the latent relationships between diseases. Conclusions MultiSourcDSim is an efficient approach to predict similarity between diseases.

Dynamic control of microwave is essential for many applications, such as antenna technique, focusing lens, etc. The recent developed metamaterials and metasurfaces provide more degrees of freedom to manipulate the electromagnetic wave through artificially engineered resonators. Here, we incorporate electrical tunable lumped elements into metamaterial and metasurface to dynamically manipulate the microwave. We will show that the chiral metamaterial can provide tunable asymmetric transmission in response to the bias voltage, and the Huygens’ metasurface can dynamically reshape the wavefront in a designable way.

This paper was inspired by the internal nucleate-appendage structure of protein complexes and the close relationships between key proteins and protein complexes. Based on these new finding, we design a novel protein complex identifying method from the angle of point (PCIM). The proposed algorithm include three steps: First, selecting the protein with high degree and high connection strength as seed. Then, producing the preliminary nucleus according to connection strength based on the seed protein. Finally, the protein complexes are generated by identifying accessorial proteins through second-order connection strength for each nucleus. We used several common methods to evaluate our algorithm, it is superior to the others existing algorithms, it can identify protein more effectively. We also did a case analysis, a new member protein YGR225W is mined for complex-60 the anaphase promoted complex, which confirmed the correctness of our prediction and also further proved that our algorithm was effective.

Recent studies have shown that protein complex is composed of core proteins and attachment proteins, and proteins inside the core are highly co-expressed. Based on this new concept, we reconstruct weighted PPI network by using gene expression data, and develop a novel protein complex identification algorithm from the angle of edge (PCIA-GeCo). First, we select the edge with high co-expressed coefficient as seed to form the preliminary cores. Then, the preliminary cores are filtered according to the weighted density of complex core to obtain the unique core. Finally, the protein complexes are generated by identifying attachment proteins for each core. A comprehensive comparison in term of F-measure, Coverage rate, P-value between our method and three other existing algorithms HUNTER, COACH and CORE has been made by comparing the predicted complexes against benchmark complexes. The evaluation results show our method PCIA-GeCo is effective; it can identify protein complexes more accurately.

In this paper, we propose a chiral metamaterial structure that enables asymmetric transmission of linearly polarized electromagnetic (EM) wave. The metamaterial is composed of twisted metallic split-ring resonator structures on both sides of a dielectric substrate. By full-wave EM simulations and free space measurements, a strong asymmetric transmission of linearly polarized EM wave, through such a thin metamaterial slab, has been demonstrated in the microwave band. It allows propagation of linearly polarized EM wave in one direction, while almost no propagation is in the opposite direction. Strong optical activity has also been found indicating that the metamaterial slab with a thickness of one-fifteenth the operational wavelength could rotate the linear polarization of the incident wave to its orthogonal polarization. The proposed chiral metamaterial structure could be useful in designing novel nonreciprocal EM devices, as well as polarization control devices.

Disease-causing genes prioritization is very important to understand disease mechanisms and biomedical applications, such as design of drugs. Previous studies have shown that promising candidate genes are mostly ranked according to their relatedness to known disease genes or closely related disease genes. Therefore, a dangling gene (isolated gene) with no edges in the network can not be effectively prioritized. These approaches tend to prioritize those genes that are highly connected in the PPI network while perform poorly when they are applied to loosely connected disease genes. To address these problems, we propose a new disease-causing genes prioritization method that based on network diffusion and rank concordance (NDRC). The method is evaluated by leave-one-out cross validation on 1931 diseases in which at least one gene is known to be involved, and it is able to rank the true causal gene first in 849 of all 2542 cases. The experimental results suggest that NDRC significantly outperforms other existing methods such as RWR, VAVIEN, DADA and PRINCE on identifying loosely connected disease genes and successfully put dangling genes as potential candidate disease genes. Furthermore, we apply NDRC method to study three representative diseases, Meckel syndrome 1, Protein C deficiency and Peroxisome biogenesis disorder 1A (Zellweger). Our study has also found that certain complex disease-causing genes can be divided into several modules that are closely associated with different disease phenotype.

A novel algorithm based on Connected Affinity Clique Extension (CACE) for mining overlapping functional modules in protein interaction network is proposed in this paper. In this approach, the value of protein connected affinity which is inferred from protein complexes is interpreted as the reliability and possibility of interaction. The protein interaction network is constructed as a weighted graph, and the weight is dependent on the connected affinity coefficient. The experimental results of our CACE in two test data sets show that the CACE can detect the functional modules much more effectively and accurately when compared with other state-of-art algorithms CPM and IPC-MCE.

Blind source separation (BSS) has applications in the fields of data compression, feature recognition, speech, audio, and biosignal processing. Identification of ECG signal is one of the challenges in the biosignal processing. Proposed in this paper is a new method, which is the combination of related function relevance to estimated signal and negative entropy in fast independent component analysis (FastICA) as objective function, and the iterative formula is derived without any assumptions; then the independent components are found by maximizing the objective function. The improved algorithm shorthand for R-FastICA is applied to extract random mixed signals and ventricular late potential (VLP) signal from normal ECG signal; simultaneously the performance of R-FastICA algorithm is compared with traditional FastICA through simulation. Experimental results show that R-FastICA algorithm outperforms traditional FastICA with higher similarity coefficient and separation precision.

In this paper, we propose a novel chiral metamaterial structure that enables asymmetric electromagnetic (EM) waves propagation. The metamaterial is composed of two metallic sheets with periodic split-ring resonator structures on both sides of a dielectric substrate. By full-wave EM simulations and free space measurements, strong diode-like asymmetric transmission of linearly polarized EM waves through such a thin metamaterial slab, has been demonstrated in the microwave band. It allows transmission of linearly polarized EM wave in one direction, while no transmission in the opposite direction. Such phenomenon is due to the strong cross-polarized conversion in the chiral slab with a thickness of one-fifteenth the operational wavelength that could rotate the linear polarization of the incident waves to its orthogonal polarization.

This paper demonstrates a new type of frequency tunable polarization selective surface operating at low THz, which is devised by utilizing the unique features of graphene. The device is comprised of an infinite array of identical unit cells in three layers. Multiple graphene dipoles are placed on the top and bottom layers to form the vertical and horizontal electric field filters. Using this new configuration, the proposed device exhibits reflection for the incident Left-Hand-Circular-Polarization (LHCP) waves and becomes transparent to the incoming Right-Hand-Circular-Polarization (RHCP) waves. The excited localized surface plasmonic resonance mode on the graphene based unit cells significantly reduces the physical dimension of the device. The unit cell dimension of the proposed design is in the order of 0.18 wavelengths in comparison to conventional metallic structures, where it is of order a half a wavelength. In the full wave analysis, the graphene based polarization selective surfaces exhibit an isolation of 21 dB for LHCP waves and a transmission loss of around 5.1 dB for waves with RHCP characteristics. The performance has also been examined under oblique incidence. The results fully verify that the proposed planar device operates properly for incident angles up to 40°. The tuning effect of the described device is investigated by varying the chemical potentials of graphene. Significant frequency reconfiguration capability is achieved in the isolation of LHCP incident waves, and meanwhile, for RHCP incidence, the transmission rate remains reasonably high.