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31 results on '"Tong, Yichen"'

1. Homotopy commutativity in quasitoric manifolds

Author

Hasui, Sho, Kishimoto, Daisuke, Tong, Yichen, and Tsutaya, Mitsunobu

Subjects
Mathematics - Algebraic Topology, Mathematics - Geometric Topology, 57S12, 55P35, 55Q15
Abstract

We prove that the loop space of a quasitoric manifold is homotopy commutative if and only if the underlying polytope is $(\Delta^3)^n$ and the characteristic matrix is equivalent to a matrix of certain type. We also construct for each $n\ge 2$ and a positive integer $k$, a quasitoric manifold $M(k,n)$ over $(\Delta^3)^n$ such that its loop space is homotopy commutative if and only if $k$ is even, where every quasitoric manifold over $\Delta^3$ is equivalent to $\mathbb{C} P^3$ whose loop space is homotopy commutative., Comment: 14 pages

Published
2024

2. Homotopy commutativity in symmetric spaces

Author

Kishimoto, Daisuke, Minowa, Yuki, Miyauchi, Toshiyuki, and Tong, Yichen

Subjects
Mathematics - Algebraic Topology, 55P35, 55Q15
Abstract

We extend the former results of Ganea and the two of the authors with Takeda on the homotopy commutativity of the loop spaces of Hermitian symmetric spaces such that the loop spaces of all irreducible symmetric spaces but $\mathbb{C}P^3$ are not homotopy commutative., Comment: 11pages

Published
2023

4. Self-Closeness Numbers of Rational Mapping Spaces

Author

Tong, Yichen

Subjects
Mathematics - Algebraic Topology, 55P10, 55P62
Abstract

For a closed connected oriented manifold $M$ of dimension $2n$, it was proved by M\o ller and Raussen that the components of the mapping space from $M$ to $S^{2n}$ have exactly two different rational homotopy types. However, since this result was proved by the algebraic models for the components, it is unclear whether other homotopy invariants distinguish their rational homotopy types or not. The self-closeness number of a connected CW complex is the least integer $k$ such that any of its self-map inducing an isomorphism in $\pi_*$ for $*\le k$ is a homotopy equivalence, and there is no result on the components of mapping spaces so far. For a rational Poincar\'e complex $X$ of dimension $2n$ with finite $\pi_1$, we completely determine the self-closeness numbers of the rationalized components of the mapping space from $X$ to $S^{2n}$ by using their Brown-Szczarba models. As a corollary, we show that the self-closeness number does distinguish the rational homotopy types of the components. Since a closed connected oriented manifold is a rational Poincar\'e complex, our result partially generalizes that of M\o ller and Raussen.

Published
2022

7. Homotopy commutativity in Hermitian symmetric spaces

Author

Kishimoto, Daisuke, Takeda, Masahiro, and Tong, Yichen

Subjects
Mathematics - Algebraic Topology, 55P35, 55Q15
Abstract

Ganea proved that the loop space of $\mathbb{C}P^n$ is homotopy commutative if and only if $n=3$. We generalize this result to that the loop spaces of all irreducible Hermitian symmetric spaces but $\mathbb{C}P^3$ are not homotopy commutative. The computation also applies to determining the homotopy nilpotency of the loop spaces of flag manifolds., Comment: 8 pages

Published
2022

8. Self-Closeness Number of Non-Simply-Connected Spaces

Author

Tong, Yichen

Subjects
Mathematics - Algebraic Topology, 55S37, 55P10
Abstract

The self-closeness number $N\mathcal{E}(X)$ of a space $X$ is the least integer $k$ such that any self-map is a homotopy equivalence whenever it is an isomorphism in the $n$-th homotopy group for each $n\le k$. We discuss the self-closeness numbers of certain non-simply-connected $X$ in this paper. As a result, we give conditions for $X$ such that $N\mathcal{E}(X)=N\mathcal{E}(\widetilde{X})$, where $\widetilde{X}$ is the universal covering space of $X$., Comment: 18 pages

Published
2021

11. Spatial Image Steganography Incorporating Adjacent Dependencies

Author

Tong, Yichen, Ni, Jiangqun, Su, Wenkang, Hu, Xianglei, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Sun, Xingming, editor, Zhang, Xiaorui, editor, and Xia, Zhihua, editor

Published
2022
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12. Spatial Image Steganography Using a Correlational Model

Author

Ni, Jiangqun, Tong, Yichen, Hu, Xianglei, Su, Wenkang, Kang, Xiangui, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Sun, Xingming, editor, Zhang, Xiaorui, editor, and Xia, Zhihua, editor

Published
2022
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15. Image Steganography Using an Eight-Element Neighborhood Gaussian Markov Random Field Model

Author

Tong, Yichen, Ni, Jiangqun, Su, Wenkang, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Woeginger, Gerhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Wang, Hongxia, editor, Zhao, Xianfeng, editor, Shi, Yunqing, editor, Kim, Hyoung Joong, editor, and Piva, Alessandro, editor

Published
2020
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27. Qualitative and quantitative analysis of Alpiniae Oxyphyllae Fructus by high‐performance liquid chromatography coupled to Fourier transform‐ion cyclotron resonance mass spectrometry.

Author

Zhang, Yu, Dong, Lei, Zhang, Qingyu, Han, Jing, Sui, Wenwen, Wei, Ziyun, Zhang, Zan, Tong, Yichen, Wang, Sijie, and Han, Fei

Subjects
HIGH performance liquid chromatography, CYCLOTRON resonance, MASS spectrometry, CHINESE medicine, QUANTITATIVE research
Abstract

Alpiniae Oxyphyllae Fructus, as a homology of medicine and food, has been widely used in China for thousands of years. However, the existing qualitative and quantitative methods are difficult to evaluate the quality of Alpiniae Oxyphyllae Fructus samples from multiple sources. In this paper, an high‐performance liquid chromatography fingerprint was established for assessing the quality of Alpiniae Oxyphyllae Fructus from different areas. Then, high‐performance liquid chromatography was coupled to Fourier transform‐ion cyclotron resonance mass spectrometry for characterization of the chemical compositions in Alpiniae Oxyphyllae Fructus. In fingerprint analysis, 54 common peaks were confirmed and six chromatographic peaks of them were identified. The similarity of 14 samples from different areas was between 0.990 and 1.000. Moreover, a total of 30 chemical components were characterized by high‐performance liquid chromatography coupled to Fourier transform‐ion cyclotron resonance mass spectrometry method, six compounds of which were decisively identified. Finally, the content of nootkatone was determined by high‐performance liquid chromatography. In conclusion, the methods used in this study are efficient for qualitative and quantitative analysis of Alpiniae Oxyphyllae Fructus. Also, these methods can be used to control the quality of other traditional Chinese medicines. [ABSTRACT FROM AUTHOR]

Published
2022
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30. Studies on the Design and Synthesis of Marine Peptide Analogues and Their Ability to Promote Proliferation in HUVECs and Zebrafish.

Author

Zheng, Yinglin, Tong, Yichen, Wang, Xinfeng, Zhou, Jiebin, Pang, Jiyan, and Avato, Pinarosa

Subjects
*ZEBRA danio, *TRIPEPTIDES, *ENDOTHELIAL cells, *CELL proliferation, *CELL migration, *NEOVASCULARIZATION, *FISHES
Abstract

In our previous studies, tripeptide 1 was found to induce angiogenesis in zebrafish embryos and in HUVECs. Based on the lead compound 1, seven new marine tripeptide analogues 2–8 have been designed and synthesized in this paper to evaluate the effects on promoting cellular proliferation in human endothelial cells (HUVECs) and zebrafish. Among them, compounds 5–7 possessed more remarkable increasing proliferation effects than other compounds, and the EC50 values of these and the leading compound 1 were 1.0 ± 0.002 μM, 1.0 ± 0.0005 μM, 0.88 ± 0.0972 μM, and 1.31 ± 0.0926 μM, respectively. Furthermore, 5–7 could enhance migrations (58.5%, 80.66% and 60.71% increment after culturing 48 h, respectively) and invasions (49.08%, 47.24% and 56.24% increase, respectively) in HUVECs compared with the vehicle control. The results revealed that the tripeptide including l-Tyrosine or d-Proline fragments instead of l-Alanine of leading compound 1 would contribute to HUVECs' proliferation. Taking the place of the original (l-Lys-l-Ala) segment of leading compound 1, a new fragment (l-Arg-d-Val) expressed higher performance in bioactivity in HUVECs. In addition, compound 7 could promote angiogenesis in zebrafish assay and it was more interesting that it also could repair damaged blood vessels in PTK787-induced zebrafish at a low concentration. The above data indicate that these peptides have potential implications for further evaluation in cytothesis studies. [ABSTRACT FROM AUTHOR]

Published
2019
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31. Marine-Derived Xyloketal Compound Ameliorates MPP + -Induced Neuronal Injury through Regulating of the IRE1/XBP1 Signaling Pathway.

Author

Tong Y, Mukhamejanova Z, Zheng Y, Wen T, Xu F, and Pang J

Subjects
Animals, Caenorhabditis elegans Proteins, Endoplasmic Reticulum Stress, Neurons metabolism, Signal Transduction, Unfolded Protein Response, Caenorhabditis elegans, Endoribonucleases genetics, Endoribonucleases metabolism, Protein Serine-Threonine Kinases genetics, Protein Serine-Threonine Kinases metabolism, X-Box Binding Protein 1 genetics, X-Box Binding Protein 1 metabolism
Abstract

The IRE1/XBP1 signaling pathway is the most conserved component of the endoplasmic reticulum unfolded protein response (UPR ER ). Activating this branch to correct defects in ER proteostasis is regarded as a promising anti-Parkinson's disease (PD) strategy. P-53 is a marine-derived xyloketal B analog which exhibited potential neuroprotective activities in previous research studies; however, the molecular mechanism underneath its protective effect remains unknown. Herein, a transcriptomic approach was introduced to explore the protective mechanism of P-53 . RNA microarray profiling was conducted based on an MPP + -induced C. elegans PD model, and bioinformatics analyses including GO enrichment and PPI network analysis were subsequently performed. In particular, the recovery of the impaired UPR ER was highlighted as a main physiological change caused by P-53 , and a cluster of genes including abu and hsp family genes which are involved in the IRE1/XBP1 branch of the UPR ER were identified as the key genes related to its neuroprotective effect. The transcription levels of these key genes were validated by RT-qPCR assays. Further results showed that P-53 enhanced the phosphorylation of IRE1, the splicing of xbp-1 mRNA, and the translation of XBP1S and boosted the expression level of the downstream targets of the IRE1/XBP1 signaling pathway. Moreover, it was also demonstrated that P-53 accelerated the scavenging of misfolded α-synuclein and attenuated the correlative mitochondrial dysfunction. Finally, the protective effect of P-53 against MPP + -induced dopaminergic neuronal loss was assessed. Taken together, these results revealed that P-53 plays its neuroprotective role through regulating of the IRE1/XBP1 signaling pathway and laid the foundation for its further development as an ER proteostasis-regulating agent.

Published
2021
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