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15,349 results on '"Tang, Yi"'

2. General Discussions on the SU(2) Vector Boson Dark Matter Model with a Single Higgs Multiplet -- Lagrangian, Discrete Subgroups, and Scalar Classifications

Author

Yuan, Chun-Xue, Zhang, Zhao, Cai, Chengfeng, Tang, Yi-Lei, and Zhang, Hong-Hao

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Theory
Abstract

The vector boson dark matter particles which stem from some broken gauge symmetries usually requires some unbroken symmetries to keep themselves stable. In the previous literature, some simplest cases have been discussed, in which the unbroken symmetry is provided by a remnant subgroup of the gauge group. It would be interesting to ask whether all the possible remnant subgroups as well as all the possible coupling forms can be enumerated. Classifying all the Higgs components into different mass degenerate representations to simplify the diagonalization processes is also necessary. Rather than the ambitious target of providing a general solution to all kinds of gauge groups configured with all forms of the Higgs multiplets, in this paper, we concentrate on the case of $\text{SU(2)}_{\text{D}}$ gauge group together with a single Higgs multiplet. We enumerate all possible discrete subgroups that can survive up to $n=21$, where $n$ is the dimension of the Higgs multiplet. We also provide the general algorithms to enumerate all possible renormalizable operators, to write down the general forms of the vacuum expectation value (VEV) configurations, and to give the detailed results of all the mass degenerate irreducible representations embedded in the Higgs multiplet.

Published
2024

18. Electroweak Precision Measurements of a Nearly-Degenerate $Z^\prime$-$Z$ System

Author

Qiu, Dayun and Tang, Yi-Lei

Subjects
High Energy Physics - Phenomenology
Abstract

In this paper, we discuss the possibility to probe a nearly-degenerate $Z^{\prime}$-$Z$ system by analyzing the $Z$-lineshape at an electron-positron collider. Compared with the usual $Z^{\prime}$ in the literature well separated with the standard model (SM) $Z$ boson in mass, the nearly-degenerate $Z^{\prime}$-$Z$ mixing affects the observed effective ``oblique parameters'' $\tilde{S}$, $\tilde{T}$, $\tilde{U}$, and the effective deviation of ``number of neutrino species'' $\delta \tilde{N}_{\nu}$ in a more complicated way and cannot be simply computed perturbatively up to a particular order. Aiming at solving this problem, we write down a general simplified effective Lagrangian and enumerate some parameter spaces corresponding to some typical models, and suggest a method to extract the constraints by looking into the line-shape of the $Z$-like resonance at an electron-positron collider.

Published
2023

19. Underwater Image Enhancement by Transformer-based Diffusion Model with Non-uniform Sampling for Skip Strategy

Author

Tang, Yi, Iwaguchi, Takafumi, and Kawasaki, Hiroshi

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

In this paper, we present an approach to image enhancement with diffusion model in underwater scenes. Our method adapts conditional denoising diffusion probabilistic models to generate the corresponding enhanced images by using the underwater images and the Gaussian noise as the inputs. Additionally, in order to improve the efficiency of the reverse process in the diffusion model, we adopt two different ways. We firstly propose a lightweight transformer-based denoising network, which can effectively promote the time of network forward per iteration. On the other hand, we introduce a skip sampling strategy to reduce the number of iterations. Besides, based on the skip sampling strategy, we propose two different non-uniform sampling methods for the sequence of the time step, namely piecewise sampling and searching with the evolutionary algorithm. Both of them are effective and can further improve performance by using the same steps against the previous uniform sampling. In the end, we conduct a relative evaluation of the widely used underwater enhancement datasets between the recent state-of-the-art methods and the proposed approach. The experimental results prove that our approach can achieve both competitive performance and high efficiency. Our code is available at \href{mailto:https://github.com/piggy2009/DM_underwater}{\color{blue}{https://github.com/piggy2009/DM\_underwater}}.

Published
2023

20. High-Throughput Identification of Crystalline Natural Products from Crude Extracts Enabled by Microarray Technology and microED.

Author

Delgadillo, David, Burch, Jessica, Kim, Lee Joon, de Moraes, Lygia, Niwa, Kanji, Williams, Jason, Tang, Melody, Lavallo, Vincent, Khatri Chhetri, Bhuwan, Jones, Christopher, Rodriguez, Isabel, Signore, Joshua, Marquez, Lewis, Bhanushali, Riya, Woo, Sunmin, Kubanek, Julia, Quave, Cassandra, Tang, Yi, and Nelson, Hosea

Abstract

The structural determination of natural products (NPs) can be arduous because of sample heterogeneity. This often demands iterative purification processes and characterization of complex molecules that may be available only in miniscule quantities. Microcrystal electron diffraction (microED) has recently shown promise as a method to solve crystal structures of NPs from nanogram quantities of analyte. However, its implementation in NP discovery remains hampered by sample throughput and purity requirements, akin to traditional NP-discovery workflows. In the methods described herein, we leverage the resolving power of transmission electron microscopy (TEM) and the miniaturization capabilities of deoxyribonucleic acid (DNA) microarray technology to address these challenges through the establishment of an NP screening platform, array electron diffraction (ArrayED). In this workflow, an array of high-performance liquid chromatography (HPLC) fractions taken from crude extracts was deposited onto TEM grids in picoliter-sized droplets. This multiplexing of analytes on TEM grids enables 1200 or more unique samples to be simultaneously inserted into a TEM instrument equipped with an autoloader. Selected area electron diffraction analysis of these microarrayed grids allows for the rapid identification of crystalline metabolites. In this study, ArrayED enabled structural characterization of 14 natural products, including four novel crystal structures and two novel polymorphs, from 20 crude extracts. Moreover, we identify several chemical species that would not be detected by standard mass spectrometry (MS) or ultraviolet-visible (UV/vis) spectroscopy and crystal forms that would not be characterized using traditional methods.

Published
2024

21. Muon precession from the aspect of Dirac equations

Author

He, Jinbo, Ming, Lei, Tang, Yi-Lei, Wang, Qiankang, and Zhang, Hong-Hao

Subjects
High Energy Physics - Phenomenology, High Energy Physics - Experiment
Abstract

In this paper, we would like to compute the muon anomalous precession frequency through solving the wave functions of the Dirac equations straightforwardly. The precession of a (anti-)muon with an anomalous magnetic momentum term is calculated together with the quantum corrections. Lorentz violation terms up to the lowest non-trivial order is introduced, and their effects on anomalous precession are evaluated perturbatively.

Published
2023

22. Genome Mining from Agriculturally Relevant Fungi Led to a d-Glucose Esterified Polyketide with a Terpene-like Core Structure.

Author

Yan, Chunsheng, Han, Wenyu, Zhou, Qingyang, Niwa, Kanji, Tang, Melody, Burch, Jessica, Zhang, Yalong, Delgadillo, David, Sun, Zuodong, Wu, Zhongshou, Jacobsen, Steven, Nelson, Hosea, Houk, K, and Tang, Yi

Subjects
Terpenes, Polyketides, Multigene Family, Fungi
Abstract

Comparison of biosynthetic gene clusters (BGCs) found in devastating plant pathogens and biocontrol fungi revealed an uncharacterized and conserved polyketide BGC. Genome mining identified the associated metabolite to be treconorin, which has a terpene-like, trans-fused 5,7-bicyclic core that is proposed to derive from a (4 + 3) cycloaddition. The core is esterified with d-glucose, which derives from the glycosidic cleavage of a trehalose ester precursor. This glycomodification strategy is different from the commonly observed glycosylation of natural products.

Published
2023

23. Enzymatic Benzofuranoindoline Formation in the Biosynthesis of the Strained Bridgehead Bicyclic Dipeptide (+)-Azonazine A.

Author

Liu, Mengting, Ohashi, Masao, Zhou, Qingyang, Sanders, Jacob, McCauley, Erin, Crews, Phillip, Tang, Yi, and Houk, Kendall

Subjects
Benzofuranoindolines, Biosynthesis, Indole Alkaloids, Oxidative Cyclization, Dipeptides, Oxidation-Reduction, Cyclization, Cytochrome P-450 Enzyme System
Abstract

We uncovered and reconstituted a concise biosynthetic pathway of the strained dipeptide (+)-azonazine A from marine-derived Aspergillus insulicola. Formation of the hexacyclic benzofuranoindoline ring system from cyclo-(l-Trp-N-methyl-l-Tyr) is catalyzed by a P450 enzyme through an oxidative cyclization. Supplementing the producing strain with various indole-substituted tryptophan derivatives resulted in the generation of a series of azonazine A analogs.

Published
2023

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