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Abstract Background To design a pulmonary ground-glass nodules (GGN) classification method based on computed tomography (CT) radiomics and machine learning for prediction of invasion in early-stage ground-glass opacity (GGO) pulmonary adenocarcinoma. Methods This retrospective study included pulmonary GGN patients who were histologically confirmed to have adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), or invasive adenocarcinoma cancer (IAC) from 2020 to 2023. CT images of all patients were automatically segmented and 107 radiomic features were obtained for each patient. Classification models were developed using random forest (RF) and cross-validation, including three one-versus-others models and one three-class model. For each model, features were ranked by normalized Gini importance, and a minimal subset was selected with a cumulative importance exceeding 0.9. These selected features were then used to train the final models. The models’ performance metrics, including area under the curve (AUC), accuracy, sensitivity, and specificity, were computed. AUC and accuracy were compared to determine the final optimal method. Results The study comprised 193 patients (mean age 54 ± 11 years, 65 men), including 65 AIS, 54 MIA, and 74 IAC, divided into one training cohort (N = 154) and one test cohort (N = 39). The final three-class RF model outperformed three individual one-versus-others models in distinguishing each class from the other two. For the multiclass classification model, the AUC, accuracy, sensitivity, and specificity were 0.87, 0.79, 0.62, and 0.88 for AIS; 0.90, 0.79, 0.54, and 0.89 for MIA; and 0.87, 0.69, 0.73, and 0.67 for IAC, respectively. Conclusions A radiomics-based multiclass RF model could effectively differentiate three types of pulmonary GGN, which enabled early diagnosis of GGO pulmonary adenocarcinoma.

Atrial fibrosis is the hallmark of structural remodeling in the pathogenesis of atrial fibrillation (AF). Meanwhile, AF causes a hypercoagulable state, and then provokes pro-fibrotic response. To discover a potential effective AF treatment targeting both coagulation and atrial fibrosis, this study investigated the structure–activity relationship of propylene glycol alginate sodium sulfate (PSS) derivatives with heparin-like activity on TGF-β1-induced atrial fibrosis. We found that PSS derivatives had significantly inhibitory effects on proliferation, migration, phenotypic transformation, and secretion/deposition of extracellular matrix of atrial fibroblasts. Among them, PGGS showed the optimal anti-atrial fibrotic activity by suppressing TGF-β1-induced activation of Smad2/3 signaling pathway. Furthermore, the study in vivo indicated that PGGS treatment displayed a reduced atrial fibrosis and AF inducibility, and attenuated the hypercoagulable state by decreasing D-dimer level and thrombin (FIIa) activity in MHC-TGF-β1 cys33ser transgenic mice, which had increased fibrosis in atrium but not in the ventricles. Our results demonstrated that PSS derivatives, especially PGGS, were potential anti-atrial fibrosis and anti-coagulant agents for AF prevention. Our study is beneficial in extending the current understandings of the function of PSS on atrial fibrosis and vulnerability to AF.

A continuous orthogonal moment is chosen as an image feature descriptor, and a rotation correction algorithm is proposed that can accommodate any order and repetition. In order to demonstrate the expanded application scope of the algorithm, a color image watermarking algorithm based on quantization concept is developed, which enhances the classical algorithm's resistance to rotation attacks. Taking into account the current research status of watermarking algorithms, a chaotic system is employed to bolster the security of the entire process. The experimental results indicate that the calibration algorithm exhibits strong universality and high accuracy. In comparison, the mean square error of the proposed rotation angle estimation model rose from 0.042 to 0.018, and the mean absolute error climbed from 0.065 to 0.032. With this enhancement, the robustness of color image watermarking algorithms against geometric attacks has taken a significant leap forward, the normalized correlation coefficient of quantization watermarking algorithm, which could not resist rotation attack, is now stable above 0.9. Furthermore, the modulated chaotic system heightens the security of the watermark algorithm, the key space up to 1015, while also improving the quality of extracted watermarks.

Purposes Focusing on the issue that the machine learning model may leak the privacy of training data during training process, which could be used by membership inference attacks, and then for stealing the sensitive information of users, an Expectation Equilibrium Optimization Algorithm (EEO) based on neural network is proposed. Methods The algorithm adopts the strategy of adversarial training and optimization, and can be divided into two loops: the inner loop assumes a strong enough opponent, whose goal is to maximize the expectation of the attack model; The outer loop conducts defense training in a targeted manner, with the goal of maximizing the expectation of the target model. Small batch gradient descent method is used to minimize the loss value of the inner and outer loops, which not only ensures the accuracy of the model, but also reduces the reasoning ability of adversaries. Findings Three representative image data sets MNIST, FASHION, and Face were used, and EEO was applied to the optimized neural network model for membership inference attack experiments. The test accuracy of the three data sets lost 2.2%, 4.7%, and 3.7%, respectively, while the accuracy of the attack model decreased by 14.6%, 16.5%, and 13.9%, respectively, and had been close to 50%, that is, random guess. Conclusions Experimental results show that the algorithm possesses both high availability and high privacy of the model. Although inevitable privacy leakage will still exist, the trained neural network model has a strong defense effect against membership inference attacks, and the impact on the target model can be ignored.

The drawbacks of a one-dimensional chaotic map are its straightforward structure, abrupt intervals, and ease of signal prediction. Richer performance and a more complicated structure are required for multidimensional chaotic mapping. To address the shortcomings of current chaotic systems, an n-dimensional cosine-transform-based chaotic system (nD-CTBCS) with a chaotic coupling model is suggested in this study. To create chaotic maps of any desired dimension, nD-CTBCS can take advantage of already-existing 1D chaotic maps as seed chaotic maps. Three two-dimensional chaotic maps are provided as examples to illustrate the impact. The findings of the evaluation and experiments demonstrate that the newly created chaotic maps function better, have broader chaotic intervals, and display hyperchaotic behavior. To further demonstrate the practicability of nD-CTBCS, a reversible data hiding scheme is proposed for the secure communication of medical images. The experimental results show that the proposed method has higher security than the existing methods.

A new multi-antenna transmission scheme, referred to as difference-based spatial modulation (DBSM), is proposed to enhance the reliability of spatial modulation (SM). With the DBSM, a pair of amplitude/phase-shift keying (APSK) symbols are conveyed by each channel-use, but only one of them is radiated from a single transmit antenna. In contrast to conventional SM, DBSM selects the active transmit antenna based on the difference between the two symbols of a channel-use, rather than one of them. The design principle of the APSK constellation in the DBSM is detailed, which guarantees that the mean Euclidean distance between any two DBSM signals mapped by a pair of complementary bit-sequences is the largest possible among all the candidates. In this way, DBSM improves the error performance of conventional SM, even though they have the same achievable data rate given the same system configuration. We demonstrate that channel coding techniques, e.g., convolutional and turbo codes, will enhance the performance gain achieved by DBSM over conventional SM. Both theoretical analysis and simulation results are provided to substantiate the advantages of our proposed DBSM scheme.

Abstract Background HIV prevention, diagnosis, treatment and care services might be hampered by inaccurate risk assessment. This study aimed to investigate the extent of and factors associated with the discordance between perceived risk and actual risky sexual behaviors among undergraduates in mainland China, guided by the Anderson's behavioral model. Methods This study involved a secondary analysis of cross-sectional data collected during the fall semester of 2018–2019 academic year. The present analysis was restricted to 8808 undergraduates with low risk perception. Those who had low perceived risk but actually engaged in risky sexual behaviors were categorized as risk discordance (RD). Univariate and multivariate Logistic regression analyses were conducted to identify factors associated with RD. Results Overall, the discordance rate between perceived and actual risk was 8.5% (95% CI: 7.9%-9.1%). Multivariate Logistic regression analysis indicated that non-heterosexual women (AOR = 0.41, 95% CI:0.27–0.60), heterosexual men (AOR = 0.45, 95% CI:0.33–0.61) and women (AOR = 0.26, 95% CI:0.19–0.35) were less likely to exhibit RD, when compared with non- heterosexual men. Furthermore, non-freshmen (AOR = 1.57, 95% CI:1.30–1.90), early initiators of sexual intercourse (AOR = 5.82, 95% CI:4.10–8.26), and those who had lower levels of HIV knowledge (AOR = 1.28, 95% CI:1.08–1.51), displayed higher levels of stigma against PLHIV (AOR = 1.50, 95% CI:1.26–1.77) and had ever been tested for HIV (AOR = 1.36, 95% CI:1.04–1.77) were more prone to reporting RD. Those with more enabling resources [i.e., displaying high levels of condom use self-efficacy (AOR = 0.70, 95% CI:0.59–0.84) and being knowledge of local testing center (AOR = 0.71, 95% CI:0.60–0.83)] were less likely to report RD. However, spending more than 2000 Yuan a month on basic needs (AOR = 2.55, 95% CI:2.07–3.14), residing in urban areas (AOR = 1.35, 95% CI:1.15–1.59) and being knowledgeable of the national AIDS policy (AOR = 1.40,95% CI:1.18–1.66) increased the chance of exhibiting RD. Conclusions Comprehensive interventions, including targeting students with high-risk characteristics, improving the acceptability of PrEP and PEP, conducting health education, enhancing self-efficacy for using condoms and making opt-out HIV testing routine in college campus, should be taken to reduce the discordance between perceived and actual HIV risk and finally to reach the goal of Zero AIDS.

The deterioration of farmland shelterbelts in the Ulan Buh desert oases could weaken their protective functions. Therefore, an accurate method is essential to assess tree decline degree in order to guide the rejuvenation and transformation of these shelterbelts. This study selected three typical farmland shelterbelts in the Ulan Buh desert oases as the objects. Terrestrial laser scanning (TLS) and airborne hyperspectral imagery (AHI) were used to acquire point cloud data and detailed spectral information of trees. Point cloud and spectral characteristics of trees with varying decline levels were analyzed. Six models were constructed to identify decline degree of shelterbelts, and model accuracy was evaluated. The coefficient of determination between the structural parameters of trees extracted by TLS and field measurements ranged from 0.76 to 0.94. Healthy trees outperformed declining trees in structural parameters, particularly in tridimensional green biomass and crown projection area. Spectral reflectance changes in the 740–950 nm band were evident among the three tree types with different decline levels, decreasing significantly with increased decline level. Among the TLS-derived feature parameters, the canopy relief ratio of tree points and point cloud density strongly correlated with the degree of tree decline. The plant senescence reflectance index and normalized difference vegetation index exhibited the closest correlation with tree decline in AHI data. The average accuracy of the models constructed based on the feature parameters of LiDAR, AHI, and the combination of both of them were 0.77, 0.61, and 0.81, respectively. The light gradient-boosting machine model utilizing TLS–AHI comprehensive feature parameters accurately determined tree decline. This study highlights the efficacy of employing feature parameters derived from TLS alone to accurately identify tree decline. Combining feature parameters from the TLS and AHI enhances the precision of tree decline identification. This approach offers guidance for decisions regarding the renewal and transformation of declining farmland shelterbelts.

Pest management has been a great challenge since the beginning of human agricultural activities. Since the 1930s, chemical pesticide control has been a major control technology that can solve some of the pest problems in agricultural production. Still, it is harmful to food safety and the ecological environment. Meanwhile, the extensive use of chemical pesticides may lead to the rapid development of pest resistance. Because of the advantages of low cost, eco-friendly advantage, and low side effects, Solar Insecticidal Lamp (SIL) as the main physical control technology has been widely used for pest management in agricultural production in China. Owing to the phototaxis of pests, they have a phototropic rhythm during the nighttime. We can adjust the SIL insecticidal time according to the phototropic rhythm of pests. The purpose of this paper is to provide a comprehensive review of the pest phototactic rhythm in a selection of 24 pest species. It is the first comprehensive survey on the phototactic rhythm of pests and the time segments of this survey are accurate to the hour. The phototactic rhythm of pests are investigated in two different varieties of crops: 1) food crops and 2) economic crops. We also discuss and analyze the various factors (e.g., meteorological conditions, insecticidal devices, physiological states and others) that affect the changing phototactic rhythm of pests. Finally, we highlight some open research challenge issues and future directions.

Abstract Background HIV counseling and testing (HCT) is provided free of charge on college campuses, but very few studies have examined whether HCT uptake is equitably distributed. This cross-sectional study aimed to compare the relative importance of various determinants of HCT uptake among undergraduates in mainland China so as to assess and subsequently to suggest ways to eliminate inequities in its use, guided by the Andersen’s behavioral model. Methods A total of 10,665 eligible undergraduates were conveniently selected to complete an online survey. Hierarchical logistic regression analyses were performed to identify the factors associated with HCT utilization. Results Only 7.7% of undergraduates had utilized HCT services. HCT uptake was inequitably distributed, since it was mainly determined by predisposing and enabling factors rather than by need factors. Further analysis indicated that HCT uptake was significantly related to two need factors, one enabling factor and six predisposing factors. Those with a higher need [i.e., perceiving themselves to be at higher risk of acquiring HIV infection (AOR = 2.76, 95% CI:2.02–3.78) and engaging in condomless sex (AOR = 1.29, 95% CI:1.00–1.67)] and those with more resources [i.e., being knowledgeable of local AIDS service organization (AOR = 1.59, 95% CI:1.37–1.85)] were more likely to utilize HCT services. Compared to non-heterosexual men, non-heterosexual women (AOR = 0.51, 95% CI:0.37–0.72), heterosexual men (AOR = 0.44, 95% CI:0.33–0.57) and women (AOR = 0.31, 95%CI: 0.24–0.41) were less likely to utilize HCT service. Furthermore, those with more knowledge (AOR = 0.80, 95% CI:0.69–0.94) and taking a positive attitude towards HCT services [i.e, expressing their willingness to utilize HCT services (AOR = 0.68, 95% CI:0.56–0.81) and having recognized the necessity to provide HTC services in the local university (AOR = 0.46, 95% CI:0.36–0.57)] were less likely to utilize HCT services. However, medical students (AOR = 1.34, 95% CI: 1.15–1.56) and non-freshmen (AOR = 1.22, 95% CI:1.03–1.45) were more likely to utilize HCT services. Conclusions To increase HCT uptake and simultaneously reduce the remaining inequities, a comprehensive intervention should be continued to target non-heterosexual men and non- freshmen and those with a higher need for HCT services, conduct health education, improve the availability and accessibility of HIV testing services.

The lack of a standardized reliable and valid instrument makes it difficult to measure attitudes toward lesbian women and gay men (ATLG) consistently and thus poses a challenge to compare and contrast intervention measures. This study aimed to validate Herek’s ATLG scale among undergraduates in mainland China and identify factors associated with negative attitudes toward LG. A total of 6,036 eligible undergraduates conveniently drawn from 30 provinces across mainland China were randomly split in half. Item analysis was first used to select unrelated or redundant items for deletion. Exploratory factor analysis (EFA) were then conducted on the first half of the sample (n = 3,001), followed by confirmatory factor analysis (CFA) and reliability analysis in the second half (n = 3035). Logistic regression analyses were finally carried out to identify their determinants. Six items were removed from the item analysis. EFA supported the existence of two factors (ATL and ATG). CFA results indicated that the two-factor model fit the data better than the one-factor model. Logistic regression analyses indicated that being female, majoring in non-health-related disciplines, attributing homosexuality to uncontrollable causes, non-adherence to traditional gender norms and exposure to homosexual content were significantly associated with less negative attitudes toward both L and G. Urban students were marginally less likely to express negative attitudes toward L but not G, while non-heterosexuals and those who had prior personal contact with homosexuals exhibited less negative attitudes toward G but not L. However, grade showed no significant associations with either ATL or ATG. The retained 14-item version of Herek’s ATLG scale has been proven to be a reliable and valid tool. Furthermore, ATL and ATG were determined by different factors and thus would be treated separately. In order to reduce negative attitudes toward LG among undergraduates in mainland China, a comprehensive intervention plan such as conducting comprehensive sex education and pushing the process of legalizing same-sex marriage should be designed, implemented and evaluated.

In this work, a novel scheme is proposed to enhance the self-interference (SI) cancellation in full-duplex communications. Beyond conventional SI cancellation schemes that rely on the SI suppression, our proposed scheme exploits periodic antenna switching to generate the pseudo-Doppler effect, thus completely removing the SI at the fundamental frequency. In this way, the desired signal is readily obtained through a low-pass filter. For the purpose of performance evaluation, the SI cancellation capability is defined as the difference between the output signal-to-interference-plus-noise ratio (SINR) and the input SINR. Theoretical formulations and numerical results validate that our pseudo-Doppler aided scheme has higher SI cancellation capability than the conventional SI suppression schemes. Moreover, the impact of the SI suppression achieved by conventional schemes and the influence of antenna switching timing difference on the practical implementation of the proposed scheme are investigated, to further substantiate the validity of our pseudo-Doppler aided SI cancellation.

Abstract Background End-stage heart failure is a major risk of mortality. The conductive super-aligned carbon nanotubes sheets (SA-CNTs) has been applied to restore the structure and function of injured myocardium through tissue engineering, and developed as efficient cardiac pacing electrodes. However, the interfacial interaction between SA-CNTs and the surface cells is unclear, and it remains challenge to restore the diminished contraction for a seriously damaged heart. Results A concept of a multifunctional power assist system (MPS) capable of multipoint pacing and contraction assisting is proposed. This device is designed to work with the host heart and does not contact blood, thus avoiding long-term anticoagulation required in current therapies. Pacing electrode constructed by SA-­CNTs promotes the epithelial-mesenchymal transition and directs the migration of pro-regenerative epicardial cells. Meanwhile, the power assist unit reveals an excellent frequency response to alternating voltage, with natural heart mimicked systolic/diastolic amplitudes. Moreover, this system exhibits an excellent pacing when attached to the surface of a rabbit heart, and presents nice biocompatibility in both in vitro and in vivo evaluation. Conclusions This MPS provides a promising non-blood contact strategy to restore in situ the normal blood-pumping function of a failed heart.

Abstract Regeneration/repair after injury can be endowed by adult stem cells (ASCs) or lineage restricted and even terminally differentiated cells. In corneal epithelium, regeneration after a large wound depends on ASCs (limbal epithelial stem cells, LESCs), whereas repair after a small wound is LESCs-independent. Here, using rat corneal epithelial wounds with different sizes, we show that YAP activation promotes the activation and expansion of LESCs after a large wound, as well as the reprogramming of local epithelial cells (repairing epithelial cells) after a small wound, which contributes to LESCs-dependent and -independent wound healing, respectively. Mechanically, we highlight that the reciprocal regulation of YAP activity and the assembly of cell junction and cortical F-actin cytoskeleton accelerates corneal epithelial healing with different-sized wounds. Together, the common YAP activation and the underlying regulatory mechanism are harnessed by LESCs and lineage-restricted epithelial cells to cope with corneal epithelial wounds with different sizes.

Trusted cloud service selection algorithms aim to select the cloud service with the highest satisfaction from many cloud services with the same or similar functions. However, many existing selection algorithms adopt the inaccurate QoS measurement method and subjective weights of QoS attributes, which make it difficult for cloud users to select the trusted cloud service. Therefore, this paper proposes a trusted cloud service selection algorithm based on lightweight intuitionistic fuzzy numbers. Firstly, based on the consideration of precise and imprecise QoS metrics, three kinds of QoS attributes are transformed into lightweight intuitionistic fuzzy numbers in a uniform way, and corresponding weight coefficients are expressed with the calculated standard deviation. Then, the trusted cloud service selection algorithm based on improved TOPSIS is proposed to guide cloud users to choose the cloud service with the highest satisfaction. The accuracy of the proposed algorithm was validated by two cases and the efficiencies of the proposed algorithm and the traditional cloud service ranking algorithm based on triangular fuzzy numbers were compared.

This article provides a method based on self-organizing maps (SOM) neural network clustering and support vector machine (SVM) ensembles to predict the survival risk levels of esophageal cancer. Nine blood indexes related to patient survival are found by using SOM clustering method. Two critical thresholds for survival are found by plotting the receiver operating characteristic (ROC) curve twice, and the lifetime is divided into three risk levels. Using the SVM method, patients' risk levels are predicted and assessed. Four kernel functions of SVM are compared, and the prediction effect of RBF kernel function is better than other kernel functions. The parameters of SVM are optimized by using genetic algorithm (GA), particle swarm algorithm (PSO) and artificial bee colony (ABC) algorithm. Experimental results show that the prediction accuracies are improved by using optimization algorithms. After comparison, ABC-SVM has better prediction results than GA-SVM and PSO-SVM with a high prediction rate and fast running time.

Background We have previously reported the feasibility of noninvasive stereotactic body radiotherapy (SBRT) as a novel approach for renal denervation. Methods and Results Herein, from a translational point of view, we assessed the antihypertensive effect and chronological evolution of SBRT‐induced renal nerve injury within 6 months in a hypertensive swine model. Hypertension was induced in swine by subcutaneous implantation of deoxycorticosterone acetate pellets in combination with a high‐salt diet. A single dose of 25 Gy with SBRT was delivered for renal denervation in 9 swine within 3.4±1.0 minutes. Blood pressure levels at baseline and 1 and 6 months post‐SBRT were comparable to control (n=5), whereas renal norepinephrine was significantly lower at 6 months (P

The growing indoor location based services (LBS) applications enhance the requirement of room type annotation. Existing room type annotations are either depending on additional sensors or prone to privacy disclosure. We proposed a method called WiLabel-based on channel state information (CSI) alone. By analyzing the CSI fluctuation, we adopt the percentage of nonzero elements (PEM) algorithm to classify indoor scene and design a zero prior knowledge behavior recognition method to achieve behavior perception in the fewer-person scene, then, design a behavior-based decision tree classifier to determine the room type. The evaluation results from 84 rooms of the college building and mall show that the WiLabel can achieve an average accuracy of 90.5% superior to others.

The diagnosis of the degree of differentiation of tumor cells can help physicians to make timely detection and take appropriate treatment for the patient's condition. In this study, the original dataset is clustered into two independent types by the Kohonen clustering algorithm. One type is used as the development sets to find correlation indicators and establish predictive models of differentiation, while the other type is used as the validation sets to test the correlation indicators and models. In the development sets, thirteen indicators significantly associated with the degree of differentiation of esophageal squamous cell carcinoma are found by the Kohonen clustering algorithm. Thirteen relevant indicators are used as input features and the degree of tumor differentiations is used as output. Ten classification algorithms are used to predict the differentiation of esophageal squamous cell carcinoma. Artificial bee colony-support vector machine (ABC-SVM) predicts better than the other nine algorithms, with an average accuracy of 81.5% for the 10-fold cross-validation. Based on logistic regression and ReliefF algorithm, five models with the greater merit for the degree of differentiation are found in the development sets. The AUC values of the five models are 0.672, 0.628, 0.630, 0.628, and 0.608 (P < 0.05). The AUC values of the five models in the validation sets are 0.753, 0.728, 0.744, 0.776, and 0.868 (P < 0.0001). The predicted values of the five models are constructed as the input features of ABC-SVM. The accuracy of the 10-fold cross-validation reached 82.0 and 86.5% in the development sets and the validation sets, respectively.

To provide the general information on corneal transplantation (CT) in China, China Cornea Society designed a questionnaire on CT from 2014 to 2018 and entrusted it to 31 committee members for implementation of the survey nationwide. This article presents the results of the survey and compares the indicators used in the survey and those in the annual statistical report released by the Eye Bank Association of America (EBAA). The number of corneal transplantations completed by the 64 hospitals from 2014 to 2018 was respectively 5377, 6394, 7595, 8270 and 8980, totally 36,616 (22,959 male and 13,657 female). The five largest hospitals by the number of corneal transplantations completed 15,994 surgeries in total, accounting for 43.68% of all the surgeries performed in the 64 hospitals. The most common indication for corneal transplantations was corneal leukoma (7683, 20.98%), followed by bacterial keratitis (4209, 11.49%), corneal dystrophies (4189, 11.44%), keratoconus (3578, 9.77%) and corneal perforation (2839, 7.75%). The main surgical techniques were penetrating keratoplasty (PK) (19,896, 54.34%), anterior lamellar keratoplasty (ALK) (13,869, 37.88%). The proportion of PK decreased from 57.97% in 2014 to 52.88% in 2018 while the proportion of ALK increased from 36.04% in 2014 to 37.92% in 2018. The geographical distribution of keratoplasties performed in China is unbalanced. PK and ALK were the main techniques of CT and corneal leukoma, bacterial keratitis and corneal dystrophies were the main indications for CT in China.

As the capital and one of the metropolises in China, Beijing has met with a number of serious so-called "urban diseases" in the process of rapid urbanization such as blind expansion of urban areas, explosion of population and the increase of urban heat island effect. To treat these "urban diseases" and make the metropolis develop healthful and sustainable in Beijing in the future, the spatial characteristics of metropolis developments in Beijing are explored in this paper. The urban built-up areas in Beijing are extracted using the DMSP-OLS nighttime light data from 1992 to 2013. The characteristics of the urban developments of Beijing are studied, including spatial and temporal scales of urban developments, urban barycenter of Beijing and its transfer trajectory, variations of urban spatial forms and the differences of urban internal developments. The results have shown that the built-up areas had been increasing and circling extending from the central urban areas to the outer spaces in the last 21 years. The built-up area had expanded by 878km2 in 1992-2013, and the built-up area in 2013 had expanded to three times comparing to that of 1992. The expanding area of the built-up area in the northeast is the largest. The expansion of the urban had mainly occurred in 1996-2007, and the expanded area had accounted for 92% of the total research period. During the whole research period, the urban barycenter of Beijing had moved 5000.71 meters towards Northeast 28° of its original place from Dongcheng District to Chaoyang District. The development level of each municipal district had been increasing year by year, and the development differences among the municipal districts had been gradually reduced; the spatial forms of Beijing had been alternately changed between extensive and intensive expansion. The results of this study can help to plan urban land use and people migration of Beijing.

It is important to obtain the location of an access point (AP), such as in the scenario of finding rogue AP in public places or designing indoor positioning system based on AP locations. Most of the existing AP localization methods depend on additional equipment with high cost or the path loss model suffering from indoor multipath. In this paper, an AP localization algorithm based on channel state information and Fresnel zone is proposed, which can just draw a semicircle with one hand to estimate the AP location. The algorithm is divided into two phases: preparations and positioning. Preparations' phase includes calibrating AP direction and identifying Fresnel zone cutting points which are obtained by combining the least squares fitting method in the time domain. Positioning phase consists of AP direction determination and AP position determination; the final AP position is confirmed according to the geometrical information. The experimental results show that the median error of our algorithm can achieve to 0.58 m, which significantly improve the AP positioning performance than other methods.

With the wide deployment of cloud computing, many security challenges have arisen, such as data and storage integrity and virtualization security. The crisis of trust caused by these security issues has become one of the important factors restricting the wide applications of cloud service. Especially for security-sensitive users, it is challenging to quickly select a cloud service which has the high level of trust and can meet both the user preferences and specific functional demands. This paper explores the multi-granularity selection standard of trust level, the users' preference calculation model, and the cloud service selection algorithm. First, the trust evaluation mechanisms among different entities in the human society are fitted, and the multi-granularity selection standard of trust levels based on Gaussian cloud transformation is constructed. Then, the calculation model of user preferences based on the cloud analytic hierarchy process is developed. Finally, the trusted cloud service selection algorithm based on two-step fuzzy comprehensive evaluation is proposed and experimentally validated.

Abstract Background Limbal epithelial stem cells (LESCs) play important roles in corneal epithelial homeostasis and regeneration, and damage to the limbus will lead to limbal stem cell deficiency (LSCD), with conjunctivalization and even visual impairment. Cultured LESCs have been used for ocular surface reconstruction, and silk fibroin (SF) membranes have shown potential as a substrate for LESC cultivation. Both culture methods and the carriers of LESCs affect outcomes following LESC transplantation. Methods Rabbit LESCs were cultured from tissue explant, single cell-suspension, and cell cluster culture methods. Ratios of p63α and/or ABCB5-positive LESCs, differentiated corneal epithelial cells (CK12 staining), and corneal tight junction formation (Claudin-1 staining) were examined to choose the most applicable LESC cultures. SF membranes were prepared and modified by 400-Da poly(ethylene glycol) (PEG). The characteristics of stem cells and normal corneal differentiation of LESCs cultured on PEG-modified SF membranes were further examined by immunofluorescence staining and flow cytometric analysis. LESCs cultured on PEG-modified SF membranes (LESC/SF grafts) and PEG-modified SF membranes (SF grafts) were transplanted onto rabbit corneas with total LSCD. New blood vessels, corneal epithelial defects, and cornea clarity were examined after transplantation. Furthermore, corneal epithelial thickness, stromal thickness, and the percentage area of CK12-positive corneal epithelium were quantified 4 months after transplantation. Results Tissue explant and single cell-suspension cultures harvested more p63α and/or ABCB5-positive LESCs, generated more CK12-positive corneal epithelial cells, and formed more corneal tight junctions than cell cluster cultures. Prepared PEG-modified SF membranes were transparent, flexible, and sturdy enough for surgical manipulation. LESCs cultured on PEG-modified SF membranes maintained characteristics of stem cells and normal corneal differentiation. LESC/SF grafts inhibited new blood vessels and rescued corneal epithelial defects in the rabbit total LSCD model. In addition, LESC/SF grafts repopulated the limbus and increased corneal epithelial thickness, stromal thickness, and the area percentage of CK12-positive corneal epithelium. Conclusions LESCs from tissue explant and single cell-suspension cultures were more applicable corneal epithelial cells for ocular surface reconstruction. LESC/SF grafts repaired corneal epithelial defects and reversed LSCD, and PEG-modified SF membranes were suitable to be a carrier for LESC transplantation.

In order to classify the quality of corn kernels in an affordable, convenient, and accurate manner, a method based on image analysis and support vector machine is proposed. A total of 129 corn kernels with Grade A, Grade B, and Grade C are used for the experiments. Six typical characteristic parameters of samples are extracted as the characteristic groups. Four different classifiers are applied and compared: support vector machine-genetic algorithm, support vector machine-particle swarm optimization, support vector machine-grid search optimization, and back-propagation neural networks. Experimental results show that the support vector machine and back-propagation neural networks without parameter optimization have the same classification accuracy rates of 92.31%. The classification accuracies are improved using the support vector machine optimization algorithms. The average correct classification rates of support vector machine-genetic algorithm and support vector machine-particle swarm optimization are all 97.44%, while the correct classification rate of support vector machine-grid search achieves 94.87%. It is concluded that the support vector machine algorithm based on parameter optimization is superior to back-propagation neural networks algorithm, and the parameter optimization effects of genetic algorithm and particle swarm optimization are better than grid search method. With a relatively small number of samples, the support vector machine-genetic algorithm and support vector machine-particle swarm optimization algorithms can improve the grading accuracy of corn kernels.

Advanced wireless technology in Internet of Things (IoT) devices is increasing and facing various security threats. The authentication of IoT devices is the first line of defense for the wireless network. Especially in a Wi-Fi network, the existing authentication methods mainly use a password or digital certificate, these methods are inconvenient to manage due to certificate issuance or prone to be attacked because passwords are easily cracked. In this paper, we propose a location-aware authentication scheme using smart contracts to ensure that IoT devices can securely perform Wi-Fi network authentication. The scheme adopts the concept of secondary authentication and consists of two phases: the registration phase, which is mainly designed to complete the generation of the public and private keys, and to link the device information with its related device information; the authentication phase, which is mainly designed to determine whether the requesting device is within a legal location range. We use the smart contract to ensure the credibility and irreparability of the authentication process. Analysis of the attack model and the attacks at different stages proves that this certification scheme is assured, and the simulation results show that the overhead introduced by this scheme is acceptable, this scheme can provide greater security for the Wi-Fi authentication of IoT devices.

The ghost city phenomenon is a serious problem resulting from the rapid urbanization process in China. Estimation of the ghost city rate (GCR) can provide information about vacant dwellings. This paper developed a methodology to quantitatively evaluate GCR values at the national scale using multi-resource remote sensing data. The Suomi National Polar-Orbiting Partnership–Visible Infrared Imaging Radiometer (NPP-VIIRS) night-time light data and moderate resolution imaging spectroradiometer (MODIS) land cover data were used in the evaluation of the GCR values in China. The average ghost city rate (AGCR) was 35.1% in China in 2013. Shanghai had the smallest AGCR of 21.7%, while Jilin has the largest AGCR of 47.27%. There is a significant negative correlation between both the provincial AGCR and the per capita disposable income of urban households (R = −0.659, p < 0.01) and the average selling prices of commercial buildings (R = −0.637, p < 0.01). In total, 31 ghost cities are mainly concentrated in the economically underdeveloped inland provinces. Ghost city areas are mainly located on the edge of urban built-up areas, and the spatial pattern of ghost city areas changed in different regions. This approach combines statistical data with the distribution of vacant urban areas, which is an effective method to capture ghost city information.

Spatial identification of the urban-rural fringes is very significant for deeply understanding the development processes and regulations of urban space and guiding urban spatial development in the future. Traditionally, urban-rural fringe areas are identified using statistical analysis methods that consider indexes from single or multiple factors, such as population densities, the ratio of building land, the proportion of the non-agricultural population, and economic levels. However, these methods have limitations, for example, the statistical data are not continuous, the statistical standards are not uniform, the data is seldom available in real time, and it is difficult to avoid issues on the statistical effects from edges of administrative regions or express the internal differences of these areas. This paper proposes a convenient approach to identify the urban-rural fringe using nighttime light data of DMSP/OLS images. First, a light characteristics–combined value model was built in ArcGIS 10.3, and the combined characteristics of light intensity and the degree of light intensity fluctuation are analyzed in the urban, urban-rural fringe, and rural areas. Then, the Python programming language was used to extract the breakpoints of the characteristic combination values of the nighttime light data in 360 directions taking Tian An Men as the center. Finally, the range of the urban-rural fringe area is identified. The results show that the urban-rural fringe of Beijing is mainly located in the annular band around Tian An Men. The average inner radius is 19 km, and the outer radius is 26 km. The urban-rural fringe includes the outer portions of the four city center districts, which are the Chaoyang District, Haidian District, Fengtai District, and Shijingshan District and the part area border with Daxing District, Tongzhou District, Changping District, Mentougou District, Shunyi District, and Fangshan District. The area of the urban-rural fringe is approximately 765 km2. This paper provides a convenient, feasible, and real-time approach for the identification of the urban-rural fringe areas. It is very significant to extract the urban-rural fringes.