Identification of Anisomerous Motor Imagery EEG Signals Based on Complex Algorithms

Motor imagery (MI) electroencephalograph (EEG) signals are widely applied in brain-computer interface (BCI). However, classified MI states are limited, and their classification accuracy rates are low because of the characteristics of nonlinearity and nonstationarity. This study proposes a novel MI pattern recognition system that is based on complex algorithms for classifying MI EEG signals. In electrooculogram (EOG) artifact preprocessing, band-pass filtering is performed to obtain the frequency band of MI-related signals, and then, canonical correlation analysis (CCA) combined with wavelet threshold denoising (WTD) is used for EOG artifact preprocessing. We propose a regularized common spatial pattern (R-CSP) algorithm for EEG feature extraction by incorporating the principle of generic learning. A new classifier combining the K-nearest neighbor (KNN) and support vector machine (SVM) approaches is used to classify four anisomerous states, namely, imaginary movements with the left hand, right foot, and right shoulder and the resting state. The highest classification accuracy rate is 92.5%, and the average classification accuracy rate is 87%. The proposed complex algorithm identification method can significantly improve the identification rate of the minority samples and the overall classification performance

Optimal Repair Strategy Against Advanced Persistent Threats Under Time-Varying Networks

Advanced persistent threat (APT) is a kind of stealthy, sophisticated, and long-term cyberattack that has brought severe financial losses and critical infrastructure damages. Existing works mainly focus on APT defense under stable network topologies, while the problem under time-varying dynamic networks (e.g., vehicular networks) remains unexplored, which motivates our work. Besides, the spatiotemporal dynamics in defense resources, complex attackers' lateral movement behaviors, and lack of timely defense make APT defense a challenging issue under time-varying networks. In this paper, we propose a novel game-theoretical APT defense approach to promote real-time and optimal defense strategy-making under both periodic time-varying and general time-varying environments. Specifically, we first model the interactions between attackers and defenders in an APT process as a dynamic APT repair game, and then formulate the APT damage minimization problem as the precise prevention and control (PPAC) problem. To derive the optimal defense strategy under both latency and defense resource constraints, we further devise an online optimal control-based mechanism integrated with two backtracking-forward algorithms to fastly derive the near-optimal solution of the PPAC problem in real time. Extensive experiments are carried out, and the results demonstrate that our proposed scheme can efficiently obtain optimal defense strategy in 54481 ms under seven attack-defense interactions with 9.64$\%$ resource occupancy in stimulated periodic time-varying and general time-varying networks. Besides, even under static networks, our proposed scheme still outperforms existing representative APT defense approaches in terms of service stability and defense resource utilization

Cross-level transformation of creativity from entrepreneurs to organizations

With the intensification of competition in the business environment, organizational creativity is increasingly becoming crucial for organizations to build competitive advantages and promote organizational development. For innovative enterprises, their entrepreneurs largely determine the development orientation of the enterprise. They are one of the most critical factors determining the level of corporate innovation, but there need to be more effective creativity transformation path to pursue innovation development. The findings in this study show that entrepreneurial individual creativity has a significant positive effect on organizational creativity, platform leadership mediates the path of creativity transformation across hierarchical levels, and organizational culture has positive moderating effect between platform leadership and organizational creativity. The study results explain the transformation mechanism of creativity from the entrepreneur's perspective, expand the potential transformation path of organizational creativity, and are instructive for enhancing organizational creativity

An exploratory survey of money boys and HIV transmission risk in Jilin Province, PR China

This report represents the first exploratory study of Chinese men who provide commercial sex services to other men ("money boys") in Jilin Province, People's Republic of China, through a convenience sample drawn from Changchun and Jilin City. A total of 86 active money boy participants (Changchun, n = 49; Jilin City, n = 37) were surveyed concerning background and demographics, basic HIV transmission knowledge, and sexual practices. The survey indicated that while Jilin Province money boy behavior matches other studies concerning propensity to high risk behavior and significant bridging potential, the Jilin money boys, unlike previous studies, exhibited a high level of basic HIV/AIDS transmission knowledge. In spite of this level of knowledge, none of the participants reported always using a condom in their sexual activities. They also exhibited a high level of awareness of voluntary counseling and testing available in the province, yet relatively few had availed themselves of these services. These preliminary findings will be used as a baseline and springboard for continuing study in the Jilin Province money boy community. Even now, however, it is becoming clear that the dynamics of male commercial sex work may vary greatly depending upon local influences, and will necessitate that future interventions are highly tailored to area-specific circumstances

Diabetic retinopathy risk in patients with unhealthy lifestyle: A Mendelian randomization study

PurposeThis study aimed to investigate the causal association between unhealthy lifestyle factors and diabetic retinopathy (DR) risk and to determine better interventions targeting these modifiable unhealthy factors.DesignTwo-sample Mendelian randomization (MR) analysis was performed in this study. The inverse variance-weighted method was used as the primary method.MethodOur study included 687 single-nucleotide polymorphisms associated with unhealthy lifestyle factors as instrumental variables. Aggregated data on individual-level genetic information were obtained from the corresponding studies and consortia. A total of 292,622,3 cases and 739,241,18 variants from four large consortia (MRC Integrative Epidemiology Unit [MRC-IEU], Genetic Investigation of Anthropometric Traits [GIANT], GWAS & Sequencing Consortium of Alcohol and Nicotine Use [GSCAN], and Neale Lab) were included.ResultIn the MR analysis, a higher body mass index (BMI) (odds ratio [OR], 95% confidence interval [CI] = 1.42, 1.30–1.54; P < 0.001] and cigarettes per day (OR, 95% CI = 1.16, 1.05–1.28; P = 0.003) were genetically predicted to be causally associated with an increased risk of DR, while patients with higher hip circumference (HC) had a lower risk of DR (OR, 95% CI = 0.85, 0.76–0.95; P = 0.004). In the analysis of subtypes of DR, the results of BMI and HC were similar to those of DR, whereas cigarettes per day were only related to proliferative DR (PDR) (OR, 95% CI = 1.18, 1.04–1.33; P = 0.009). In the MR-PRESSO analysis, a higher waist-to-hip ratio (WHR) was a risk factor for DR and PDR (OR, 95% CI = 1.24, 1.02–1.50, P = 0.041; OR, 95% CI = 1.32, 1.01–1.73, P = 0.049) after removing the outliers. Furthermore, no pleiotropy was observed in these exposures.ConclusionOur findings suggest that higher BMI, WHR, and smoking are likely to be causal factors in the development of DR, whereas genetically higher HC is associated with a lower risk of DR, providing insights into a better understanding of the etiology and prevention of DR

Uncooled photodetector at short-wavelength infrared using InAs nanowire photoabsorbers on InP with p-n heterojunctions

In this work, we demonstrate an InAs nanowire photodetector at short-wavelength infrared (SWIR) composed of vertically oriented selective-area InAs nanowire photoabsorber arrays on InP substrates, forming InAs–InP heterojunctions. We measure a rectification ratio greater than 300 at room temperature, which indicates a desirable diode performance. The dark current density, normalized to the area of nanowire heterojunctions, is 130 mA/cm2 at a temperature of 300 K and a reverse bias of 0.5 V, making it comparable to the state-of-the-art bulk InAs p-i-n photodiodes. An analysis of the Arrhenius plot of the dark current at reverse bias yields an activation energy of 175 meV from 190 to 300 K, suggesting that the Shockley–Read–Hall (SRH) nonradiative current is the primary contributor to the dark current. By using three-dimensional electrical simulations, we determine that the SRH nonradiative current originates from the acceptor-like surface traps at the nanowire-passivation heterointerfaces. The spectral response at room temperature is also measured, with a clear photodetection signature observed at wavelengths up to 2.5 μm. This study provides an understanding of dark current for small band gap selective-area nanowires and paves the way to integrate these improved nanostructured photoabsorbers on large band gap substrates for high-performance photodetectors at SWIR

InGaAs-GaAs nanowire avalanche photodiodes toward single-photon detection in free-running mode

Single-photon detection at near-infrared (NIR) wavelengths is critical for light detection and ranging (LiDAR) systems used in imaging technologies such as autonomous vehicle trackers and atmospheric remote sensing. Portable, high-performance LiDAR relies on silicon-based single-photon avalanche diodes (SPADs) because of their extremely low dark count rate (DCR) and afterpulsing probability, but their operation wavelengths are typically limited up to 905 nm. Although InGaAs-InP SPADs offer an alternative platform to extend the operation wavelengths to eye-safe ranges, their high DCR and afterpulsing severely limit their commercial applications. Here we propose a new separate absorption and multiplication avalanche photodiode (SAM-APD) platform composed of vertical InGaAs–GaAs nanowire arrays for single-photon detection. Among a total of 4400 nanowires constituting one photodiode, each avalanche event is confined in a single nanowire, which means that the avalanche volume and the number of filled traps can be drastically reduced in our approach. This leads to an extremely small afterpulsing probability compared with conventional InGaAs-based SPADs and enables operation in free-running mode. We show a DCR below 10 Hz, due to reduced fill factor, with photon count rates of 7.8 MHz and timing jitter less than 113 ps, which suggest that nanowire-based NIR focal plane arrays for single-photon detection can be designed without active quenching circuitry that severely restricts pixel density and portability in NIR commercial SPADs. Therefore, the proposed work based on vertical nanowires provides a new degree of freedom in designing avalanche photodetectors and could be a stepping stone for high-performance InGaAs SPADs

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Essays on Online Platforms: Policy and Monetization Strategies

Thesis (Ph.D.)--University of Washington, 2020This dissertation analyzes the digital platform from two aspects, the platform policy, and the monetization strategies. Based on three different settings, the sharing economy, the user-generated content platform, and the digital game platform, I study how the development of online platforms reshape the consumer decision and the supplier’s choice, and how the online platforms would accommodate for the change. In the first essay, I investigate how the platform-side picture disclosure would influence the consumers’ decision. I find that consumers can better identify the heterogeneous quality when pictures are disclosed as quality signals. However, the efficiency is affected when consumers misinterpret the supplier’s quality from the image. In the second essay, I examine how the peer-based monetary incentive would influence the content generator’s participation. I find that the peer-based monetary incentive increases the content contribution but may have a temporary negative impact as content generators tend to overestimate their ability to monetize the content. The heterogeneous effect on content generators’ intrinsic motivation is also discussed. In the third essay, I study the optimal pricing of the virtual selling strategy, where the premium module can be obtained not only through direct purchase but also through virtual currency earned during excessive gameplay. I build an analytical model to describe the player’s tradeoff of money and time and find a reverse-discrimination effect and a complementary effect, which enable the game provider to provide time discounts to the players, but in the meantime, make more profit. The business implications and theoretical contributions are discussed in each essay