arXiv subjects

Yijing Wu

Publications and source records attributed to Yijing Wu.

11 recordsLinked to original sources

arXiv2025

Single-beam driven rotational manipulation for high-resolution 3D cellular morphology reconstruction

The acquisition of multi-view information of cells is essential for accurate 3D reconstruction of their structures. Rotational manipulation of cells has emerged as an effective technique for obtaining such data. However, most reported methods require a trade-off between manipulation flexibility and system complexity These limitations significantly hinder their practical applicability. Recently, a novel approach has been proposed that enables simultaneous trapping and arbitrary-angle rotation of cells using a single optical beam carrying spin angular momentum (SAM). This method offers improved stability and manipulation flexibility, a simplified experimental setup, and supports coaxial alignment of the imaging and optical paths. In this paper, we employed this method to rotate cells and acquire multi-view images. Furthermore, we present a complete 3D reconstruction workflow, and validate the performance of the proposed method through the reconstruction of Punica granatum pollen cells and Prunus cerasifera cells. Our methods pave the way for 3D reconstruction of microscopic biological specimens, including but not limited to cells.

physics.optics↗

arXiv2024

HeySQuAD: A Spoken Question Answering Dataset

Spoken question answering (SQA) systems are critical for digital assistants and other real-world use cases, but evaluating their performance is a challenge due to the importance of human-spoken questions. This study presents a new large-scale community-shared SQA dataset called HeySQuAD, which includes 76k human-spoken questions, 97k machine-generated questions, and their corresponding textual answers from the SQuAD QA dataset. Our goal is to measure the ability of machines to accurately understand noisy spoken questions and provide reliable answers. Through extensive testing, we demonstrate that training with transcribed human-spoken and original SQuAD questions leads to a significant improvement (12.51%) in answering human-spoken questions compared to training with only the original SQuAD textual questions. Moreover, evaluating with a higher-quality transcription can lead to a further improvement of 2.03%. This research has significant implications for the development of SQA systems and their ability to meet the needs of users in real-world scenarios.

cs.CL↗

arXiv2024

Self-training Strategies for Sentiment Analysis: An Empirical Study

Sentiment analysis is a crucial task in natural language processing that involves identifying and extracting subjective sentiment from text. Self-training has recently emerged as an economical and efficient technique for developing sentiment analysis models by leveraging a small amount of labeled data and a large amount of unlabeled data. However, given a set of training data, how to utilize them to conduct self-training makes a significant difference in the final performance of the model. We refer to this methodology as the self-training strategy. In this paper, we present an empirical study of various self-training strategies for sentiment analysis. First, we investigate the influence of the self-training strategy and hyper-parameters on the performance of traditional small language models (SLMs) in various few-shot settings. Second, we also explore the feasibility of leveraging large language models (LLMs) to help self-training. We propose and empirically compare several self-training strategies with the intervention of LLMs. Extensive experiments are conducted on three real-world sentiment analysis datasets.

cs.CL↗

arXiv2022

Density-constrained Chemotaxis and Hele-Shaw flow

We consider a model of congestion dynamics with chemotaxis, where the density of cells follows the chemical signal it generates, while observing an incompressibility constraint. We show that when the chemical diffuses slowly and attracts the cells strongly, then the dynamics of the congested cells is well approximated by a surface-tension driven free boundary problem. More precisely, we show that in this limit the density of cell converges to the characteristic function of a set whose evolution is described by a Hele-Shaw free boundary problem with surface tension. Our problem is set in a bounded domain, which leads to an interesting analysis on the limiting boundary conditions for the density function. Namely, we prove that the assumption of Robin boundary conditions for the chemical potential leads to a contact angle condition for the free interface.

math.AP↗

arXiv2022

A density-constrained model for Chemotaxis

We consider a model of congestion dynamics with chemotaxis: The density of cells follows a chemical signal it generates, while subject to an incompressibility constraint. The incompressibility constraint results in the formation of patches, describing regions where the maximal density has been reached. The dynamics of these patches can be described by either Hele-Shaw or Richards equation type flow (depending on whether we consider the model with diffusion or the model with pure advection). Our focus in this paper is on the construction of weak solutions for this problem via a variational discrete time scheme of JKO type. We also establish the uniqueness of these solutions. In addition, we make more rigorous the connection between this incompressible chemotaxis model and the free boundary problems describing the motion of the patches in terms of the density and associated pressure variable. In particular, we obtain new results characterizing the pressure variable as the solution of an obstacle problem and prove that in the pure advection case the dynamic preserves patches.

math.AP↗

arXiv2022

$Γ$-convergence of some nonlocal perimeters in bounded subsets of $\mathbb{R}^n$ with general boundary conditions

We establish the $Γ$-convergence of some energy functionals describing nonlocal attractive interactions in bounded domains. The interaction potential solves an elliptic equation (local or nonlocal) in the bounded domain and the primary interest of our results is to identify the effects that the boundary conditions imposed on the potential have on the limiting functional. We consider general Robin boundary conditions, which include Dirichlet and Neumann conditions as particular cases. Depending on the order of the elliptic operator the limiting functional involves the usual perimeter or some fractional perimeter. We also consider the $Γ$-convergence of a related energy functional combining the usual perimeter functional and the nonlocal repulsive interaction energy.

math.AP↗

arXiv2022

Learning-based multiplexed transmission of scattered twisted light through a kilometer-scale standard multimode fiber

Multiplexing multiple orbital angular momentum (OAM) modes of light has the potential to increase data capacity in optical communication. However, the distribution of such modes over long distances remains challenging. Free-space transmission is strongly influenced by atmospheric turbulence and light scattering, while the wave distortion induced by the mode dispersion in fibers disables OAM demultiplexing in fiber-optic communications. Here, a deep-learning-based approach is developed to recover the data from scattered OAM channels without measuring any phase information. Over a 1-km-long standard multimode fiber, the method is able to identify different OAM modes with an accuracy of more than 99.9% in parallel demultiplexing of 24 scattered OAM channels. To demonstrate the transmission quality, color images are encoded in multiplexed twisted light and our method achieves decoding the transmitted data with an error rate of 0.13%. Our work shows the artificial intelligence algorithm could benefit the use of OAM multiplexing in commercial fiber networks and high-performance optical communication in turbulent environments.

physics.optics↗

arXiv2020

On the fully nonlinear Alt-Phillips equation

For a parameter $γ\in(1,2)$, we study the fully nonlinear version of the Alt-Phillips equation, $F(D^2u)=u^{γ-1}$, for $u\ge 0.$ We establish the optimal regularity of the solution, as well as the $C^1$ regularity of the regular part of the free boundary.

math.AP↗

arXiv2020

An isoperimetric problem with a competing nonlocal singular term

In this paper, we investigate the minimization of a functional in which the usual perimeter is competing with a nonlocal singular term comparable (but not necessarily equal to) a fractional perimeter. The motivation for this problem is a cell motility model introduced in some previous work by the first author. We establish several facts about global minimizers with a volume constraint. In particular we prove that minimizers exist and are radially symmetric for small mass, while minimizers cannot be radially symmetric for large mass. For large mass, we prove that the minimizing sequences either split into smaller sets that drift to infinity or develop fingers of a prescribed width. Finally, we connect these two alternatives to a related minimization problem for the optimal constant in a classical interpolation inequality (a Gagliardo-Nirenberg type inequality for fractional perimeter).

math.AP↗

arXiv2018

A non-local one-phase free boundary problem from obstacle to cavitation

We consider a one-phase free boundary problem of the minimizer of the energy \[ J_γ(u)=\frac{1}{2}\int_{(B_1^{n+1})^+}{y^{1-2s}|\nabla u(x,y)|^2dxdy}+\int_{B_1^{n}\times \{y=0\}}{u^γdx}, \] with constants $0<s,γ<1$. It is an intermediate case of the fractional cavitation problem (as $γ=0$) and the fractional obstacle problem (as $γ=1$). We prove that the blow-up near every free boundary point is homogeneous of degree $β=\frac{2s}{2-γ}$, and flat free boundary is $C^{1,θ}$ when $γ$ is close to 0.

math.AP↗

arXiv2017

Fractional analogue of k-Hessian operators

Applying ideas of fractional analogue of Monge-Ampére operator by L. Caffarelli and F. Charro, we consider an analogue of fractional k-Hessian operators expressed as concave envelopes of fractional linear operators, and reproduce the same regularity results when k=2. Under the set up of global solutions prescribing data at infinity and global barriers, the key estimate is to prove that fractional 2-Hessian operator is strictly elliptic. Then we can apply nonlocal Evans-Krylov theorem to prove such solutions are classical.

math.AP↗