N6-methyladenosine triggers renal fibrosis via enhancing translation and stability of ZEB2 mRNA.

In recent years, a surge in studies investigating N6-methyladenosine (m6A) modification in human diseases has occurred. However, the specific roles and mechanisms of m6A in kidney disease remain incompletely understood. This study revealed that m6A plays a positive role in regulating renal fibrosis (RF) by inducing epithelial-to-mesenchymal phenotypic transition (EMT) in renal tubular cells. Through comprehensive analyses, including m6A sequencing, RNA-seq, and functional studies, we confirmed the pivotal involvement of zinc finger E-box binding homeobox 2 (ZEB2) in m6A-mediated RF and EMT. Notably, the m6A-modified coding sequence of ZEB2 mRNA significantly enhances its translational elongation and mRNA stability by interacting with the YTHDF1/eEF-2 complex and IGF2BP3, respectively. Moreover, targeted demethylation of ZEB2 mRNA using the dm6ACRISPR system substantially decreases ZEB2 expression and disrupts the EMT process in renal tubular epithelial cells. In vivo and clinical data further support the positive influence of m6A/ZEB2 on RF progression. Our findings highlight the m6A-mediated regulation of RF through ZEB2, revealing a novel therapeutic target for RF treatment and enhancing our understanding of the impact of mRNA methylation on kidney disease.

Upregulated Tß4 expression in inflammatory bowel disease impairs the intestinal mucus barrier by inhibiting autophagy in mice.

Disrupted intestinal barrier homeostasis is fundamental to inflammatory bowel disease. Thymosin ß4 (Tß4) improves inflammation and has beneficial effects in dry-eye diseases, but its effects on the intestinal mucus barrier remain unknown. Therefore, this study evaluated the underlying regulatory mechanisms and effects of Tß4 by examining Tß4 expression in a mouse model with dextran sodium sulfate (DSS)-induced colitis and colonic barrier damage. Additionally, we intraperitoneally injected C57BL/6 mice with Tß4 to assess barrier function, microtubule-associated protein 1 light chain 3 (LC3II) protein expression, and autophagy. Finally, normal human colon tissue and colon carcinoma cells (Caco2) were cultured to verify Tß4-induced barrier function and autophagy changes. Mucin2 levels decreased, microbial infiltration increased, and Tß4 expression increased in the colitis mouse model versus the control mice, indicating mucus barrier damage. Moreover, Tß4-treated C57BL/6 mice had damaged intestinal mucus barriers and decreased LC3II levels. Tß4 also inhibited colonic mucin2 production, disrupted tight junctions, and downregulated autophagy; these results were confirmed in Caco2 cells and normal human colon tissue. In summary, Tß4 may be implicated in colitis by compromising the integrity of the intestinal mucus barrier and inhibiting autophagy. Thus, Tß4 could be a new diagnostic marker for intestinal barrier defects.

Nutritional screening and assessment tools for patients with cirrhosis based on the Global Leadership Initiative on Malnutrition criteria.

BACKGROUND: Malnutrition is highly prevalent and associated with complications and mortality in patients with cirrhosis. METHODS: This was a prospective observational study. Patients with cirrhosis were screened using the Nutritional Risk Screening 2002, the Royal Free Hospital-Nutritional Prioritizing Tool and the Skeletal Muscle Index. Then, the sensitivity, specificity, positive and negative predictive values, and consistency with the Global Leadership Initiative on Malnutrition criteria results were calculated. We also analysed the association between nutritional status and short-term prognosis. RESULTS: We enrolled 125 patients with cirrhosis, of whom 59.20% and 60.00% were malnourished based on the Global Leadership Initiative on Malnutrition criteria and Skeletal Muscle Index. Some 53.60% and 65.60%, respectively, were classified medium-to-high nutritional risk by Nutritional Risk Screening 2002 and the Royal Free Hospital-Nutritional Prioritizing Tool. The Royal Free Hospital-Nutritional Prioritizing Tool had the best predictive value, and it was more sensitive and had a better negative predictive value than the Nutritional Risk Screening 2002 Tool. The Skeletal Muscle Index also had good sensitivity and predictive value. The Royal Free Hospital-Nutritional Prioritizing Tool, Skeletal Muscle Index and Global Leadership Initiative on Malnutrition criteria showed high concordance. The 3- and 6-month mortality rates were significantly higher for patients with moderate-to-high nutritional risk or malnutrition, regardless of the tool. CONCLUSIONS: When assessing cirrhosis with the Global Leadership Initiative on Malnutrition criteria, the Royal Free Hospital-Nutritional Prioritizing Tool is best for nutritional screening and the Skeletal Muscle Index is also a good nutritional assessment tool.

Comparison of thermal comfort between different heating systems and adaptation to different indoor climates in winter.

Individual heating systems, such as the air-source heat pump (ASHP) air-conditioner or floor heating (FH), are usually used by people living in the hot summer and cold winter (HSCW) zone of China to heat indoor climates in the winter. However, little research has been conducted in the HSCW zone on the thermal comfort difference between indoor climates heated by ASHP air-conditioners and those heated by floor heating, as well as how occupants adapt to different indoor climates. We conducted a comparative field experiment in ASHP-heated and FH-heated apartments in Nanjing to investigate how different types of heating systems influence the thermal sensation of occupants, and we conducted a comparative field experiment in ASHP-heated office buildings and naturally ventilated teaching buildings in Shanghai to investigate how occupants adapt to different indoor thermal environments. Indoor environmental parameters and body surface temperatures were measured using instruments, and occupants' thermal sensation, activity level, and clothing were evaluated using the questionnaire. The results show that floor heating improves thermal comfort by raising foot temperature compared to the ASHP air-conditioner, and that occupants become acclimatized to different indoor climates by adjusting neutral operative temperature. According to the findings, there is no need to overheat the indoor environment in the HSCW zone because occupants can adapt to their experienced thermal environment and it is critical to maintain warm foot temperature in the cool/cold indoor environment.

Isothermal Amplification-Based Detection of Single-Base RNA N6-Methyladenosine.

N6-methyladenosine (m6A) has recently gained much attention due to its diverse biological functions. Currently, the commonly used detection methods for locus-specific m6A marks are complicated to operate, it is difficult to quantify the methylation level, and they have high false-positive levels. Here, we report a new method for locus-specific m6A detection based on the methylate-sensitive endonuclease activity of MazF and the simultaneous amplification and testing (SAT) method, termed "m6A-MazF-SAT". Mechanically, MazF fails to cleave the A (m6A) CA motif; therefore, the undigested template can be SAT-amplified using specific probes targeting the upstream and downstream of sites of interest. Fluorescent signals of SAT amplification can be detected by real-time PCR, and therefore, they achieve the detection of m6A existence. After the condition optimization, m6A-MazF-SAT can significantly, accurately, and rapidly detect the m6A-modified sites in mRNA, rRNA, and lncRNA at the fmol level, as well as 10% m6A at the fmol level. In addition, m6A-MazF-SAT can quantify the abundance of target m6A in biological samples and can be used for the inhibitor selection of m6A-related enzymes. Together, we offer a new approach to detect locus-specific m6A both qualitatively and quantitatively; it is easy to operate, results can be obtained rapidly, and it has low false-positive levels and high repeatability.

Bayesian phylodynamic analysis reveals the evolutionary history and the dispersal patterns of citrus tristeza virus in China based on the p25 gene.

BACKGROUND: Citrus tristeza virus (CTV) is one of the most serious threats to the citrus industry, and is present in both wild and cultivated citrus. The origin and dispersal patterns of CTV is still poorly understood in China. METHODS: In this study, 524 CTV suspected citrus samples from China were collected, including 354 cultivated citrus samples and 174 wild citrus samples. Finally, 126 CTV coat protein sequences were obtained with time-stamped from 10 citrus origins in China. Bayesian phylodynamic inference were performed for CTV origin and dispersal patterns study in China. RESULT: We found that CTV was mainly distributed in southern and coastal areas of China. The substitution rate of CTV was 4.70 × 10- 4 subs/site/year (95% credibility interval: 1.10 × 10- 4 subs/site/year ~ 9.10 × 10- 4 subs/site/year), with a slight increasing trend in CTV populations between 1990 and 2006. The CTV isolates in China shared a most common recent ancestor around 1875 (95% credibility interval: 1676.57 ~ 1961.02). The CTV in China was originated from wild citrus in Hunan and Jiangxi, and then spread from the wild citrus to cultivated citrus in the growing regions of Sichuan, Chongqing, Hubei, Fujian, Zhejiang, Guangxi and Guangdong provinces. CONCLUSIONS: This study has proved that CTV in China was originated from wild citrus in Hunan and Jiangxi. The spatial-temporal distribution and dispersal patterns has uncovered the population and pandemic history of CTV, providing hints toward a better understanding of the spread and origin of CTV in China.

Fibroblast growth factor 13 is involved in the pathogenesis of temporal lobe epilepsy.

BACKGROUND: Temporal lobe epilepsy (TLE) is the most common drug-resistant epilepsy in adults, with pathological mechanisms remaining to be fully elucidated. Fibroblast Growth Factor 13 (FGF13) encodes an intracellular protein involved in microtubule stabilization and regulation of voltage-gated sodium channels (VGSCs) function. FGF13 mutation has been identified in patients with inherent seizure, suggesting a potential association between FGF13 and the etiology of TLE. Here, we set to explore the pathological role of FGF13 in the etiology of TLE. RESULTS: We found that the expression of FGF13 was increased in the cortical lesions and CA1 region of sclerotic hippocampus and correlated with the seizure frequency in TLE patients. Also, Fgf13 expression was increased in the hippocampus of chronic TLE mice generated by kainic acid (KA) injection. Furthermore, Fgf13 knockdown or overexpression was respectively found to attenuate or potentiate the effects of KA on axonal length, somatic area and the VGSCs-mediated current in the hippocampal neurons. CONCLUSIONS: Taken together, these findings suggest that FGF13 is involved in the pathogenesis of TLE by modulating microtubule activity and neuronal excitability.

Recent Understanding and Future Directions in the Application of MMP-2 in Encapsulating Peritoneal Sclerosis Clinical Practice.

Encapsulating peritoneal sclerosis (EPS) is an uncommon and harmful complication which may cause destructive outcomes. Matrix metalloproteinase-2 (MMP-2) as a protease can reduce constituents of the extracellular matrix and play a crucial role in the progression of EPS. As a new biomarker, MMP-2 may improve the detection rate of EPS patients in clinical work. In this review, we summarize the recent study of MMP-2 in different etiologies and the assessment of its application value and draw attention to its future directions.

Characterizing gas-liquid two-phase flow behavior using complex network and deep learning.

Gas-liquid two-phase flow is polymorphic and unstable, and characterizing its flow behavior is a major challenge in the study of multiphase flow. We first conduct dynamic experiments on gas-liquid two-phase flow in a vertical tube and obtain multi-channel signals using a self-designed four-sector distributed conductivity sensor. In order to characterize the evolution of gas-liquid two-phase flow, we transform the obtained signals using the adaptive optimal kernel time-frequency representation and build a complex network based on the time-frequency energy distribution. As quantitative indicators, global clustering coefficients of the complex network at various sparsity levels are computed to analyze the dynamic behavior of various flow structures. The results demonstrate that the proposed approach enables effective analysis of multi-channel measurement information for revealing the evolutionary mechanisms of gas-liquid two-phase flow. Furthermore, for the purpose of flow structure recognition, we propose a temporal-spatio convolutional neural network and achieve a classification accuracy of 95.83%.

Interconnected ordinal pattern complex network for characterizing the spatial coupling behavior of gas-liquid two-phase flow.

The complex phase interactions of the two-phase flow are a key factor in understanding the flow pattern evolutional mechanisms, yet these complex flow behaviors have not been well understood. In this paper, we employ a series of gas-liquid two-phase flow multivariate fluctuation signals as observations and propose a novel interconnected ordinal pattern network to investigate the spatial coupling behaviors of the gas-liquid two-phase flow patterns. In addition, we use two network indices, which are the global subnetwork mutual information (I) and the global subnetwork clustering coefficient (C), to quantitatively measure the spatial coupling strength of different gas-liquid flow patterns. The gas-liquid two-phase flow pattern evolutionary behaviors are further characterized by calculating the two proposed coupling indices under different flow conditions. The proposed interconnected ordinal pattern network provides a novel tool for a deeper understanding of the evolutional mechanisms of the multi-phase flow system, and it can also be used to investigate the coupling behaviors of other complex systems with multiple observations.

Criticality in transient behavior of coupled oscillator system toward chimera and synchronization.

Chimera states in spatiotemporal dynamical systems have been investigated in physical, chemical, and biological systems, while how the system is steering toward different final destinies upon spatially localized perturbation is still unknown. Through a systematic numerical analysis of the evolution of the spatiotemporal patterns of multi-chimera states, we uncover a critical behavior of the system in transient time toward either chimera or synchronization as the final stable state. We measure the critical values and the transient time of chimeras with different numbers of clusters. Then, based on an adequate verification, we fit and analyze the distribution of the transient time, which obeys power-law variation process with the increase in perturbation strengths. Moreover, the comparison between different clusters exhibits an interesting phenomenon, thus we find that the critical value of odd and even clusters will alternatively converge into a certain value from two sides, respectively, implying that this critical behavior can be modeled and enabling the articulation of a phenomenological model.

A bioartificial transgenic porcine whole liver expressing human proteins alleviates acute liver failure in pigs.

BACKGROUND: Preventing heterologous protein influx in patients is important when using xenogeneic bioartificial livers (BALs) to treat liver failure. The development of transgenic porcine livers synthesizing human proteins is a promising approach in this regard. Here, we evaluated the safety and efficacy of a transgenic porcine liver synthesizing human albumin (hALB) and coagulation factor VII (hFVII) within a bioartificial system. METHODS: Tibetan miniature pigs were randomly subjected to different interventions after surgery-induced partially ischemic liver failure. Group A (n = 4) was subjected to basic treatment; group B (n = 4) was to standard medical treatment and wild-type porcine BAL perfusion, and group C (n = 2) was to standard medical treatment and transgenic BAL perfusion. Biochemical parameters, coagulation status, survival time, and pathological changes were determined. Expressions of hALB and hFVII were detected using immunohistochemistry and enzyme-linked immunosorbent assays. RESULTS: The survival time in group A was 9.75 ± 1.26 days; this was shorter than that in both perfused groups, in which all animals reached an endpoint of 12 days (P = 0.006). Ammonia, bilirubin, and lactate levels were significantly decreased, whereas albumin and fibrinogen levels were increased after perfusion (all P < 0.05). hALB and hFVII were detected in transgenic BAL-perfused pig serum and ex vivo in the liver tissues. CONCLUSIONS: The humanized transgenic pig livers could synthesize and secrete hALB and hFVII ex vivo in a whole organ-based bioartificial system, while maintaining their metabolism, detoxification, transformation, and excretion functions, which were comparable to those observed in wild-type porcine livers. Therefore, the use of transgenic bioartificial whole livers is expected to become a new approach in treating acute liver failure.

Radioactive versus normal stent insertion for malignant hilar obstruction: a meta-analysis.

PURPOSE: This meta-analysis was designed for examining the relative clinical safety and efficacy of normal stent (NS) and radioactive stent (RS) insertion in malignant hilar obstruction (MHO) patients. MATERIAL AND METHODS: Relevant studies published as of March 2022 were identified through searches of the Medline, Embase, Wanfang, and CNKI databases, and the pooled results of these studies were then analyzed. RESULTS: Eight studies including 258 and 247 patients that underwent NS and RS insertion, respectively, were incorporated into this meta-analysis. RS insertion was found to be associated with significant improvements in functional successful rate (p = 0.04), Δaspertate aminotransferase (AST, p = 0.0004), Δalanine aminotransferase (ALT, p = 0.002), stent patency (p < 0.00001), stent re-obstruction rate (p = 0.03), and OS (p < 0.00001) outcomes as compared to those associated with NS insertion. No differences in Δtotal bilirubin (TBIL, p = 0.38), cholangeitis rate (p = 0.45), cholecystitis rate (p = 0.84), or hemorrhage rate (p = 0.87) were observed when comparing patients that underwent RS and NS insertion. Substantial publication bias was observed for endpoints of cholecystitis and hemorrhage. CONCLUSIONS: These results suggest that relative to NS insertion, RS insertion can effectively prolong stent patency and OS in MHO cases.

Motor neuron survival is associated with reduced neuroinflammation and increased autophagy after brachial plexus avulsion injury in aldose reductase-deficient mice.

Brachial plexus root avulsion (BPRA) is frequently caused by high-energy trauma including traffic accident and birth trauma, which will induces massive motoneurons (MNs) death as well as loss of motor and sensory function in the upper limb. The death of MNs is attributed to energy deficiency, neuroinflammation and oxidative stress at the injured ventral horn of spinal cord triggered by BPRA injury. It has been reported which aldose reductase (AR), an endogenous enzyme that catalyzes fructose synthesis, positively correlates with the poor prognosis following cerebral ischemic injury, diabetic retinopathy and diabetic peripheral neuropathy. However, the role of AR in BPRA remains unknown. Herein, we used a mouse model and found that in the spinal cord of BPRA mice, the upregulation of AR correlated significantly with (1) an inactivated SIRT1-AMPK-mTOR pathway and disrupted autophagy; (2) increased byproducts accumulation of lipid peroxidation metabolism and neuroinflammation; and (3) increased MNs death. Furthermore, our results demonstrated the role of AR in BPRA injury whereby the absence of AR (AR knockout mice, AR-/-) prevented the hyper-neuroinflammation and disrupted autophagy as well as motor neuron death caused by BPRA injury. Finally, we further demonstrate that AR inhibitor epalrestat is neuroprotective against BPRA injury by increasing autophagy level, alleviating neuroinflammation and rescuing MNs death in mice. Collectively, our data demonstrate that the AR upregulation in the spinal cord is an important factor contributing to autophagy disruption, neuroinflammation and MNs death following brachial plexus roots avulsion in mice. Our study also provides a promising therapy drug to assist re-implantation surgery for the treatment of BPRA.

Aqueous lithium chloride solution as a non-toxic bactericidal and fungicidal disinfectant for air-conditioning systems: Efficacy and mechanism.

Airborne pathogenic bacteria and fungi transmitted through air-conditioning (AC) systems have been identified as a major public health risk. Air scrubbing is a promising liquid-based air disinfection technique that captures and inactivates airborne pathogens in liquid disinfectants. However, owing to the drawbacks of irritating odor and toxicity, the commonly-used chemical disinfectants cannot be employed for AC systems. This study aimed to unveil the inactivation performance and mechanism of non-toxic and chemically stable aqueous lithium chloride (LiCl) solution-the popular liquid desiccant in the AC systems-as a user-friendly disinfectant. Four prominent airborne pathogenic bacteria and fungi were exposed to the LiCl solution under various conditions. The inactivation effects were quantified with fluorescence-staining-based confocal microscopy and verified with the pathogens' membrane integrity variations, intracellular substance leakage, and morphological changes. Results showed that LiCl solution was remarkably efficient in inactivating the pathogens within 60 min, with an efficacy of 35.2-96.2%. The solution's inactivation ability was promoted by increasing the temperatures and concentrations; however, it appeared insensitive to exposure time over 30 min. We then explored the inactivation mechanism of LiCl solution by assessing cellular protein leakages and compared the inactivation rates with those of NaCl solution. The extracellular protein increased by over 470% after being exposed to LiCl solution. The inactivation rate was also considerably higher than in NaCl solution under the same osmotic pressure (24.79 MPa). We suggest that apart from osmotic pressure, the inactivation is reinforced by Li+-specific properties, including its strong water attraction that deprived the solvation shells of microbial protein and caused protein denaturation. We propose that aqueous LiCl solution may act as a user-friendly disinfectant for air-scrubbing due to its attractive characteristics, including its non-toxicity, odorless nature, and chemical stability. These findings may open up a "green" way to disinfect airborne pathogens and safeguard public health.

Portable ultrasonic humidifier exacerbates indoor bioaerosol risks by raising bacterial concentrations and fueling pathogenic genera.

Portable ultrasonic humidifiers are frequently used in heating rooms to ease air dryness. However, it has also posed serious health concerns such as "humidifier fever" because the bioaerosol concentration and community in the humidified space may alter quickly before the occupants could even notice. We compared the microbial proliferation rates in the humidifiers' reservoirs filled with three commonly used water types and investigated the impacts of the ultrasonic humidifiers on the temporal concentration, size distribution, and community variations of indoor bacterial and fungal aerosols during two-week humidification. The concentration of indoor bacterial aerosols increased exponentially, concentrating in the respiratory size ranges (≤1.1 µm), and was proportional to the humidification level, which soon exceeded 1000 CFU/m3 in one week (at RH = 70%), while the fungal concentration always remained low (≤177 CFU/m3 ). The indoor bioaerosol community, significantly associated with the humidifier water, was substantially distorted after humidification and dominated by the pathogenic Pseudomonas spp. (40.50%), Brevundimonas spp. (3.02%), Acinetobacter spp. (0.98%) and Legionella spp. (0.69%). Our results show that ultrasonic humidification contaminates indoor air by raising bacterial concentrations and fueling the pathogenic genera. To minimize the exposure risks, occupants should avoid long-term and excessive humidification (RH ≥ 70%) and clean the ultrasonic humidifier weekly.

Cross-subject emotion recognition using visibility graph and genetic algorithm-based convolution neural network.

An efficient emotion recognition model is an important research branch in electroencephalogram (EEG)-based brain-computer interfaces. However, the input of the emotion recognition model is often a whole set of EEG channels obtained by electrodes placed on subjects. The unnecessary information produced by redundant channels affects the recognition rate and depletes computing resources, thereby hindering the practical applications of emotion recognition. In this work, we aim to optimize the input of EEG channels using a visibility graph (VG) and genetic algorithm-based convolutional neural network (GA-CNN). First, we design an experiment to evoke three types of emotion states using movies and collect the multi-channel EEG signals of each subject under different emotion states. Then, we construct VGs for each EEG channel and derive nonlinear features representing each EEG channel. We employ the genetic algorithm (GA) to find the optimal subset of EEG channels for emotion recognition and use the recognition results of the CNN as fitness values. The experimental results show that the recognition performance of the proposed method using a subset of EEG channels is superior to that of the CNN using all channels for each subject. Last, based on the subset of EEG channels searched by the GA-CNN, we perform cross-subject emotion recognition tasks employing leave-one-subject-out cross-validation. These results demonstrate the effectiveness of the proposed method in recognizing emotion states using fewer EEG channels and further enrich the methods of EEG classification using nonlinear features.

Co-Occurrence Fingerprint Data-Based Heterogeneous Transfer Learning Framework for Indoor Positioning.

Distribution discrepancy is an intrinsic challenge in existing fingerprint-based indoor positioning system(s) (FIPS) due to real-time environmental variations; thus, the positioning model needs to be reconstructed frequently based on newly collected training data. However, it is expensive or impossible to collect adequate training samples to reconstruct the fingerprint database. Fortunately, transfer learning has proven to be an effective solution to mitigate the distribution discrepancy, enabling us to update the positioning model using newly collected training data in real time. However, in practical applications, traditional transfer learning algorithms no longer act well to feature space heterogeneity caused by different types or holding postures of fingerprint collection devices (such as smartphones). Moreover, current heterogeneous transfer methods typically require enough accurately labeled samples in the target domain, which is practically expensive and even unavailable. Aiming to solve these problems, a heterogeneous transfer learning framework based on co-occurrence data (HTL-CD) is proposed for FIPS, which can realize higher positioning accuracy and robustness against environmental changes without reconstructing the fingerprint database repeatedly. Specifically, the source domain samples are mapped into the feature space in the target domain, then the marginal and conditional distributions of the source and target samples are aligned in order to minimize the distribution divergence caused by collection device heterogeneity and environmental changes. Moreover, the utilized co-occurrence fingerprint data enables us to calculate correlation coefficients between heterogeneous samples without accurately labeled target samples. Furthermore, by resorting to the adopted correlation restriction mechanism, more valuable knowledge will be transferred to the target domain if the source samples are related to the target ones, which remarkably relieves the "negative transfer" issue. Real-world experimental performance implies that, even without accurately labeled samples in the target domain, the proposed HTL-CD can obtain at least 17.15% smaller average localization errors (ALEs) than existing transfer learning-based positioning methods, which further validates the effectiveness and superiority of our algorithm.

OHetTLAL: An Online Transfer Learning Method for Fingerprint-Based Indoor Positioning.

In an indoor positioning system (IPS), transfer learning (TL) methods are commonly used to predict the location of mobile devices under the assumption that all training instances of the target domain are given in advance. However, this assumption has been criticized for its shortcomings in dealing with the problem of signal distribution variations, especially in a dynamic indoor environment. The reasons are: collecting a sufficient number of training instances is costly, the training instances may arrive online, the feature spaces of the target and source domains may be different, and negative knowledge may be transferred in the case of a redundant source domain. In this work, we proposed an online heterogeneous transfer learning (OHetTLAL) algorithm for IPS-based RSS fingerprinting to improve the positioning performance in the target domain by fusing both source and target domain knowledge. The source domain was refined based on the target domain to avoid negative knowledge transfer. The co-occurrence measure of the feature spaces (Cmip) was used to derive the homogeneous new feature spaces, and the features with higher weight values were selected for training the classifier because they could positively affect the location prediction of the target. Thus, the objective function was minimized over the new feature spaces. Extensive experiments were conducted on two real-world scenarios of datasets, and the predictive power of the different modeling techniques were evaluated for predicting the location of a mobile device. The results have revealed that the proposed algorithm outperforms the state-of-the-art methods for fingerprint-based indoor positioning and is found robust to changing environments. Moreover, the proposed algorithm is not only resilient to fluctuating environments but also mitigates the model's overfitting problem.

Data Fusion Methods for Indoor Positioning Systems Based on Channel State Information Fingerprinting.

Indoor signals are susceptible to NLOS propagation effects, multipath effects, and a dynamic environment, posing more challenges than outdoor signals despite decades of advancements in location services. In modern Wi-Fi networks that support both MIMO and OFDM techniques, Channel State Information (CSI) is now used as an enhanced wireless channel metric replacing the Wi-Fi received signal strength (RSS) fingerprinting method. The indoor multipath effects, however, make it less robust and stable. This study proposes a positive knowledge transfer-based heterogeneous data fusion method for representing the different scenarios of temporal variations in CSI-based fingerprint measurements generated in a complex indoor environment targeting indoor parking lots, while reducing the training calibration overhead. Extensive experiments were performed with real-world scenarios of the indoor parking phenomenon. Results revealed that the proposed algorithm proved to be an efficient algorithm with consistent positioning accuracy across all potential variations. In addition to improving indoor parking location accuracy, the proposed algorithm provides computationally robust and efficient location estimates in dynamic environments. A Cramer-Rao lower bound (CRLB) analysis was also used to estimate the lower bound of the parking lot location error variance under various temporal variation scenarios. Based on analytical derivations, we prove that the lower bound of the variance of the location estimator depends on the (i) angle of the base stations, (ii) number of base stations, (iii) distance between the target and the base station, djr (iv) correlation of the measurements, ρrjai and (v) signal propagation parameters σC and γ.