Empirical Fourier Decomposition: An Accurate Adaptive Signal Decomposition Method

Signal decomposition is an effective tool to assist the identification of modal information in time-domain signals. Two signal decomposition methods, including the empirical wavelet transform (EWT) and Fourier decomposition method (FDM), have been developed based on Fourier theory. However, the EWT can suffer from a mode mixing problem for signals with closely-spaced modes and decomposition results by FDM can suffer from an inconsistency problem. An accurate adaptive signal decomposition method, called the empirical Fourier decomposition (EFD), is proposed to solve the problems in this work. The proposed EFD combines the uses of an improved Fourier spectrum segmentation technique and an ideal filter bank. The segmentation technique can solve the inconsistency problem by predefining the number of modes in a signal to be decomposed and filter functions in the ideal filter bank have no transition phases, which can solve the mode mixing problem. Numerical investigations are conducted to study the accuracy of the EFD. It is shown that the EFD can yield accurate and consistent decomposition results for signals with multiple non-stationary modes and those with closely-spaced modes, compared with decomposition results by the EWT, FDM, variational mode decomposition and empirical mode decomposition. It is also shown that the EFD can yield accurate time-frequency representation results and it has the highest computational efficiency among the compared methods

Impacts of Tibetan Plateau sensible heat and El Niño–Southern Oscillation on precipitation over South China under the background of the PDO

This study aims to investigate the impacts of the spring sensible heat (SH) over the Tibetan Plateau (TP) and the El Niño–Southern Oscillation (ENSO) in the preceding wintertime on midsummer (July–August) precipitation over South China under the different Pacific decadal oscillation (PDO) phases. More specifically, eight classifications are adopted at the demarcation point around 1996 when the spring SH over the TP and the midsummer precipitation in South China occurred as well as the PDO phase transition, including positive and negative SHs and ENSOs under a positive PDO phase (1979–1996) and a negative PDO phase (1997–2019), respectively, based on the Niño-3 index and the spring SH calculated from 48 stations over the central and eastern parts of the TP. The results show that both the spring SH and the ENSO in preceding wintertime have a significant impact on the midsummer precipitation over South China; that is, when the two factors are in their respective positive (negative) phase, the midsummer precipitation in South China is generally less (more). Importantly, the phase change of background field PDO can significantly enhance the effect of the SH and the ENSO on summer precipitation over South China. Moreover, compared with the preceding wintertime ENSO, the spring SH over the TP contributes more to the midsummer precipitation in South China based on analyses of their independent and synergistic effects. The main mechanism responsible for the anomalous midsummer precipitation over South China are the combined effects of the South Asian high (SAH) and the western Pacific subtropical high (WPSH), which are controlled by the spring SH anomaly over the TP and the ENSO, respectively. Deep understanding of the dominant factors of the midsummer precipitation over South China will help understand the local climate change and reduce the losses caused by drought and flood disasters

Expression of GCRG213p, LINE-1 endonuclease variant, significantly different in gastric complete and incomplete intestinal metaplasia.

BACKGROUND: Intestinal metaplasia (IM) of the gastric mucosa is classified as complete (Type I) and incomplete IM (Type II and III) subtypes, which showed significantly different risk for developing to gastric adenocarcinoma (GAC). GCRG213, a variant of L1-endonuclease (L1-EN), first identified in our lab, was upregulated in GAC tissue. However, the relationship between GCRG213 and IM subtypes is not clear. Our study explored the association of GCRG213 protein (GCRG213p) with IM subtypes. METHODS: Gastric cancer and/or para-tumor tissue samples were collected from 123 patients who underwent gastrectomy for intestinal type gastric adenocarcinoma. The subtypes of IM were characterized with Alcian blue-periodic acid-Schiff and High Iron Diamine-Alcian blue staining methods. Immunohistochemistry of GCRG213p was performed, and its expression in gastric adenocarcinoma and para-tumor tissue including dysplasia, IM, and normal mucosa were analyzed. RESULTS: GCRG213p was expressed in 48.94% IM, 57.14% dysplasia and 55.32% GAC, respectively. GCRG213p expression was higher in well and moderately differentiated adenocarcinoma (P = 0.037). In IM glands, GCRG213p expressed mainly in the cytoplasm of absorptive enterocytes with defined brush borders, but not in goblet cells. The expression of GCRG213p in type I IM (90.00%) was significantly higher than that in type II (36.36%) and type III (25.00%) (P \u3c 0.001). In normal gastric mucosa, GCRG213p was exclusively positive in the cytoplasm of gastric chief cells. CONCLUSIONS: The expression of GCRG213p in complete IM was significantly higher than in incomplete IM, which implies that GCRG213p may play a role on the developing of IM to adenocarcinoma. GCRG213p was exclusively expressed in chief cells, suggesting that it might be involved in cell differentiation from the chief cells to IM

BMP-driven NRF2 activation in esophageal basal cell differentiation and eosinophilic esophagitis

Tissue homeostasis requires balanced self-renewal and differentiation of stem/progenitor cells, especially in tissues that are constantly replenished like the esophagus. Disruption of this balance is associated with pathological conditions, including eosinophilic esophagitis (EoE), in which basal progenitor cells become hyperplastic upon proinflammatory stimulation. However, how basal cells respond to the inflammatory environment at the molecular level remains undetermined. We previously reported that the bone morphogenetic protein (BMP) signaling pathway is critical for epithelial morphogenesis in the embryonic esophagus. Here, we address how this pathway regulates tissue homeostasis and EoE development in the adult esophagus. BMP signaling was specifically activated in differentiated squamous epithelium, but not in basal progenitor cells, which express the BMP antagonist follistatin. Previous reports indicate that increased BMP activity promotes Barrett’s intestinal differentiation; however, in mice, basal progenitor cell–specific expression of constitutively active BMP promoted squamous differentiation. Moreover, BMP activation increased intracellular ROS levels, initiating an NRF2-mediated oxidative response during basal progenitor cell differentiation. In both a mouse EoE model and human biopsies, reduced squamous differentiation was associated with high levels of follistatin and disrupted BMP/NRF2 pathways. We therefore propose a model in which normal squamous differentiation of basal progenitor cells is mediated by BMP-driven NRF2 activation and basal cell hyperplasia is promoted by disruption of BMP signaling in EoE