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Three-dimensional (3D) target localization by using hybrid time difference of arrival (TDOA) and angle of arrival (AOA) measurements from multiple sensors has been an active research area for several decades due to its extensive applications in various fields. For this nonlinear estimation problem, the pseudolinear system of equations constructed by using the measurements generally acts as the basis of numerous localization algorithms. In this paper, we aim to improve the performance of 3D TDOA–AOA localization by introducing the constrained total least squares (CTLS) framework wherein the inherent characteristics of the pseudolinear equations can be properly taken into consideration. On the basis of the total least squares model, the CTLS model for 3D TDOA–AOA localization is established by imposing the inherent characteristics of the pseudolinear equations as additional constraints. Then, the multi-constraint optimization problem in CTLS model is solved by using an iterative algorithm based on successive projections. Extensive numerical simulations are accomplished for evaluating the performance of the proposed CTLS algorithm. The results show that the proposed algorithm gives moderate accuracy enhancement with acceptable computational cost, and more importantly, it is more robust to large measurement noise than the compared algorithms. [ABSTRACT FROM AUTHOR]

In this paper, a method for the problem of depth estimation of a broadband source via reliable acoustic path propagation is presented for the case using a vertical line array (VLA). The estimates are determined by two kinds of multipath time-delay ratios, namely, the ratio of direct-surface-reflected (D-SR) to direct-direct time-delays and the ratio of D-SR to surface-reflected–surface-reflected time-delays. The innovation of ratio behavior is that it provides a mechanism for obtaining a useful depth interval with the assumption of plane-wave propagation. The estimation accuracy of a depth interval relies on the degree to which the actual acoustic propagation characteristic can be modeled by image theory. Furthermore, the variability of depth interval due to the approximation made in the derivation method allows one to achieve binary discrimination of both the source depth and source range with only a minimal amount of prior environmental knowledge. The methodology of multipath time-delay estimation is first reviewed and improved, followed by an illustration of the source depth estimation and a discussion of the performance analysis using results from numerical simulations. Finally, the proposed method is demonstrated with experimental data collected in the South China Sea in which a short-aperture VLA is deployed near the sea bottom. [ABSTRACT FROM AUTHOR]

In this study, three-dimensional source localization is investigated based on time delays between the direct (D) and surface-reflected (SR) paths measured using asynchronous distributed sensors in the deep-water reliable-acoustic-path environment. Instead of matching replicas, we develop computationally efficient formulas to locate the source. The formulas are derived by first pseudolinearizing the measurement model of the D–SR time delay and then solving the obtained pseudolinear system of equations using the instrumental variable technique. Furthermore, the Cramér–Rao lower bound of the investigated problem is derived theoretically. Monte Carlo simulations are performed to demonstrate the performance of the proposed formulas. The results show that the formulas can provide a localization accuracy comparable to that of the matching algorithm when the measurement noise level is low, while exhibiting an acceptable inferiority at high noise levels. Finally, the feasibility of the proposed formulas is verified using experimental data acquired in the western Pacific. In all experimental test groups, the localization biases of the proposed formulas do not exceed 250 m in the horizontal plane and are less than 5% for depth estimation. • Near-surface source in deep-ocean scenario is located by using distributed sensors deployed near the bottom without requiring the angle or time-synchronization information. • The propagation time delays between the direct and surface-reflected paths measured by distributed sensors are used for 3D source localization. • Computationally efficient formulas are derived for locating the source such that the high computational burden associated with the existing matching algorithm is avoided. • The CRLB of the investigated problem is derived. [ABSTRACT FROM AUTHOR]

• The existing modified Fourier transform for source depth estimation is ameliorated by an elaborately-designed resampling scheme to achieve a higher estimation accuracy. • The proposed method (compared to the original counterpart) can reduce the estimation bias by about 12%. • The superiority of the method is verified through the experimental data collected in the South Sea of China. The interference characteristics between the direct and surface-reflected paths in deep-water reliable acoustic path (RAP) environment contain the information of source depth. For the narrowband case, the source depth can be estimated by applying a modified Fourier transform to the beam intensity series in the sine domain of the receiving angle, which was first published by McCargar and Zurk [(2013), J. Acoust. Soc. Am. 133(4), EL320-EL325]. However, in practical RAP environment, the imperfect periodicity of the beam intensity series as well as the inappropriate reference sound speed often degrades the accuracy of this method. To address this problem, this paper designs a pre-processing resampling scheme to modulate the beam intensity series. Given a minor amount of priori environmental information, the proposed resampling function including a specified reference sound speed can effectively enhance the periodicity of the beam intensity series, thereby enables the modified Fourier transform to achieve higher accuracy. The effectiveness and superiority of the proposed method are experimentally demonstrated with the data collected in the South Sea of China. The results show that the proposed resampling scheme can reduce the depth estimation bias by about 12%. [ABSTRACT FROM AUTHOR]

• Near-surface broadband source is located with several asynchronous vertically distributed hydrophones in deep water. • Based on the invariance of the striation frequency ratio with respect to source depth, the proposed method can decouple source range and depth estimation. • Compared to the existing matching method, the proposed method performs more reliably when only a few hydrophones are available and exhibits faster computation speed. • Experimental results in the western Pacific confirm the effectiveness of the proposed method. This paper presents a method for passive broadband source localization using asynchronous vertically distributed hydrophones in a deep-water reliable acoustic path (RAP) environment. The proposed method utilizes the invariance of the striation frequency ratio with respect to the source depth to decouple range and depth estimation. First, the received spectra are resampled according to the striation frequency ratio and matched in pairs to estimate the source range. Then, based on the estimated source range, the source depth is estimated by using a modified Fourier transform. The proposed method outperforms the existing matching algorithm in terms of localization reliability when only a few hydrophones are available. The method also exhibits faster computation speed since it involves only one-dimensional grid scanning. Finally, experimental results in the western Pacific demonstrate that this method can effectively locate a submerged source at a depth of approximately 70 m. [ABSTRACT FROM AUTHOR]

This paper introduces a model-independent passive source localization method, employing asynchronous distributed hydrophones in shallow water. Based on the frequency invariability of the acoustic field, assuming the correct source range information, the warped spectra of received signals at distributed hydrophones exhibit identical shapes. Subsequently, a cost function is formulated to mutually align the warped spectra, with its maximum point indicating the source location. The proposed method can locate the source in two-dimensional horizontal space without requiring either angle- or time-synchronization information. Numerical simulations are conducted to demonstrate the performance of the proposed method. [ABSTRACT FROM AUTHOR]

Persistent apical periodontitis (PAP) is characterized by refractory inflammation and progressive bone destruction. Enterococcus faecalis infection is considered an important etiological factor for the development of PAP, although the exact mechanisms remain unknown. This study aimed at investigating the role of E. faecalis in cell proliferation, inflammatory reactions and osteoclast differentiation of macrophages using an in vitro infection model of osteoclast precursor RAW264.7 cells. A cell viability assay of cultured RAW264.7 cells exposed to live E. faecalis at a multiplicity of infection of 100 for 2 h, indicated that the infection exhibited no cytotoxic effect. Transmission electron microscopy images revealed no apoptotic changes but a rise of metabolic activity and phagocytic features in the infected RAW264.7 cells. Confocal laser scanning microscopic and flow cytometric analysis indicated that the phagocytosis of RAW264.7 cells was activated by E. faecalis infection. Furthermore, quantitative real-time PCR assays demonstrated that the expression of inflammatory cytokines was remarkably elevated in infected RAW264.7 cells. Differentiation of infected RAW264.7 cells into osteoclasts was remarkably attenuated, and expression of osteoclast marker genes as well as fusogenic genes significantly dropped. In summary, E. faecalis appears to attenuate osteoclastic differentiation of RAW264.7 precursor cells, rather stimulates them to function as macrophages. [ABSTRACT FROM AUTHOR]

Background: Regulating the pluripotency of human dental pulp stem cells (hDPSCs) is key for the self-repair of injured dental pulp. We previously found that OCT4A promotes the proliferation and odontogenic differentiation of human dental pulp cells (hDPCs). Recent studies have shown the interaction between OCT4A and lncRNAs in pluripotency maintenance of various stem cells. The aim of this study was to explore the underlying roles and mechanisms of OCT4A and its related lncRNAs in the proliferation and multidirectional differentiation of hDPSCs in an inflammatory microenvironment. Methods: Human lncRNA microarrays were applied to screen out the differentially expressed lncRNAs in hDPSCs between the OCT4A-overexpressing and vector groups. Lipopolysaccharide (LPS) was used to simulate the inflammatory microenvironment. The effects of OCT4A and the lncRNA FTX on the proliferation and multidifferentiation of hDPSCs were observed by the CCK-8 assay, EdU staining, real-time PCR, western blotting, and Alizarin red and oil red O staining. Bioinformatics analysis and chromatin immunoprecipitation (ChIP) assays were performed to clarify the targeted mechanism of OCT4A on FTX. The regulation by FTX of the expression of OCT4A and its downstream pluripotent transcription factors SOX2 and c-MYC was further detected by real-time PCR and western blotting. Results: The microarray results showed that 978 lncRNAs (250 of which were upregulated and 728 downregulated) were potentially differentially expressed genes (fold change ≥ 2, P < 0.05). LPS stimulation attenuated the self-renewal of hDPSCs. OCT4A enhanced the cell proliferation and multidifferentiation capacities of hDPSCs in an inflammatory microenvironment, while FTX exhibited the opposite effects. OCT4A negatively regulated FTX function by binding to specific regions on the FTX promoter, thereby inhibiting the transcription of FTX. Moreover, overexpression of FTX downregulated the expression of OCT4A, SOX2 and c-MYC, whereas knockdown of FTX facilitated their expression. Conclusions: OCT4A was found to be a crucial factor maintaining the self-renewal of hDPSCs by transcriptionally targeting FTX in an inflammatory microenvironment. Moreover, we proposed a novel function of FTX in negatively regulating the pluripotency and multilineage differentiation capacity of hDPSCs. The hierarchical organization between OCT4A and FTX expanded the understanding of the network between transcription factors and lncRNAs in fine-tuning the pluripotency/differentiation balance of adult stem cells, and provided prospective targets for optimizing dental-derived stem cell sources for regenerative endodontics. [ABSTRACT FROM AUTHOR]

Introduction. Xeroderma pigmentosum group C (XPC), essential component of multisubunit stem cell coactivator complex (SCC), functions as the critical factor modulating pluripotency and genome integrity through interaction with Oct-4/Sox2. However, its specific role in regulating pluripotency and multilineage differentiation of human dental pulp cells (DPCs) remains unknown. Methods. To elucidate the functional role XPC played in pluripotency and multilineage differentiation of DPCs, expressions of XPC in DPCs with long-term culture were examined by real-time PCR and western blot. DPCs were transfected with lentiviral-mediated human XPC gene; then transfection rate was investigated by real-time PCR and western blot. Cell cycle, apoptosis, proliferation, senescence, multilineage differentiation, and expression of Oct-4/Sox2/c-Myc in transfected DPCs were examined. Results. XPC, Oct-4, Sox2, and c-Myc were downregulated at P7 compared with P3 in DPCs with long-term culture. XPC genes were upregulated in DPCs at P2 after transfection and maintained high expression level at P3 and P7. Cell proliferation, PI value, and telomerase activity were enhanced, whereas apoptosis was suppressed in transfected DPCs. Oct-4/Sox2/c-Myc were significantly upregulated, and multilineage differentiation in DPCs with XPC overexpression was enhanced after transfection. Conclusions. XPC plays an essential role in the modulation of pluripotency and multilineage differentiation of DPCs through regulation of Oct-4/Sox2/c-Myc. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to evaluate dentinal tubule penetration and the retreatability of EndoSequence BC Sealer HiFlow (HiFlow), iRoot SP, and AH Plus when using the single-cone (SC) or continuous wave condensation (CWC) technique. Materials and methods: Sixty-five single-rooted teeth were instrumented and randomly divided into 5 groups: group 1, AH Plus/CWC; group 2, iRoot SP/CWC; group 3, iRoot SP/SC; group 4, HiFlow/CWC; and group 5, HiFlow/SC. The ability to re-establish patency during endodontic retreatment was recorded, as was the time taken to reach the working length. Dentinal tubule penetration and remaining debris after retreatment were evaluated by confocal microscopy and scanning electron microscopy. Data were analyzed by Kruskal-Wallis test and Dunn's multiple comparisons test (α = 0.05). Results: The HiFlow/CWC and iRoot SP/CWC groups required more time to reach the working length than groups that underwent the SC technique regardless of the sealer used (P <.05). The HiFlow/CWC group showed a significantly higher percentage of sealer penetration area than that of the iRoot SP/SC at 4 mm from the apex (P <.05) and penetrated deeper into dentinal tubules than iRoot SP/SC at both 8-mm and 12-mm levels (P <.05). Moreover, the HiFlow/CWC and HiFlow/SC groups demonstrated less remaining sealer along the canal wall than AH Plus/CWC group at 4-mm level (P <.05). Conclusions: HiFlow/CWC technique showed better performance in dentinal tubule penetration than that of iRoot SP/SC. Both HiFlow and iRoot SP combined with CWC technique groups required more retreatment time than the other groups. Furthermore, using HiFlow with either the CWC or SC technique left less remaining sealer at 4-mm level than using AH Plus with the CWC technique during retreatment. Clinical relevance: With favorable performance in dentinal tubule penetration and retreatability in endodontic retreatment, the combined use of EndoSequence BC Sealer HiFlow with the recommended continuous wave condensation technique may be a worthwhile choice in root canal treatment. [ABSTRACT FROM AUTHOR]

Identifying small molecules to activate the Oct-4/Sox2-derived pluripotency network represents a hopeful and safe method to pluripotency without genetic manipulation. Luteolin and apigenin, two major bioactive flavonoids, enhance reprogramming efficiency and increase expression of Oct-4/Sox2/c-Myc, albeit the detailed mechanism regulating pluripotency in dental-derived cells remains unknown. In the present study, to elucidate the effect of luteolin/apigenin on pluripotency of periodontal ligament cells (PDLCs) through interaction with downstream signals, we examined cell cycle, proliferation, apoptosis, expression of Oct-4/Sox2/c-Myc, and multilineage differentiation of PDLCs with luteolin/apigenin treatment. Moreover, we profiled the differentially expressed pluripotency genes by PCR arrays. Our results demonstrated that luteolin/apigenin restrained cell proliferation, increased apoptosis, and arrested PDLCs in G2/M and S phase. Luteolin and apigenin activated expression of Oct-4, Sox2, and c-Myc in a time- and dose-dependent pattern, and repressed lineage-specific differentiation. PCR arrays profiled multiple signals in PDLCs with luteolin/apigenin treatment, among which NFATc1 was the major upregulated gene. Notably, blocking of the NFATc1 signal with INCA-6 significantly decreased mRNA and protein expression of Oct-4, Sox2, and c-Myc in PDLCs with luteolin/apigenin treatment, indicating that NFATc1 may act as an upstream modulator of Oct-4/Sox2 signal. Taken together, this study showed that luteolin and apigenin effectively maintain pluripotency of PDLCs through activation of Oct-4/Sox2 signal via NFATc1. [ABSTRACT FROM AUTHOR]