bluuebunny/crossref_metadata_2025_split huggingface dataset:
The changing-look AGN SDSS J101152.98+544206.4 is returning to a type I state
Authors: Lyu Bing , Wu Xue-Bing , Pang Yuxuan , Wang Huimei , Zhu Rui , Fu Yuming , Wu Qingwen , Yan Zhen , Yu Wenfei , Liu Hao , Kang Shi-Ju , Jin Junjie , Yang Jinyi , Wang Feige 
Published: January 2025

Aims. We discovered that the changing-look active galactic nucleus (CLAGN) SDSS J101152.98+544206.4 (J1011+5442 for short) gradually returns to the type I state after a short period between 2014 and 2019 in the faint type 1.9 state.
Methods. Motivated by the rebrightening in the optical and mid-infrared light curves from ZTF and WISE, we obtained new spectroscopic observations with the Xinglong 2.16 m, the Lijiang 2.4 m, and the MMT 6.5 m optical telescopes in 2024.
Results. After changing its optical AGN type from 1 to 1.9 between 2003 and 2015 according to the repeat spectroscopy from the Time Domain Spectroscopic Survey, J1011+5442 returned to its type I state in 2024. We detect the significant and very broad Hβ lines (full width at half maximum of ≳5000 km/s) based on the new spectra, which suggests that J1011+5442 was in the intermediate state between the dim state in 2015 and the bright state in 2003. The long-term optical and mid-infrared light curves also show a brightening trend between 2019 and 2024 as the broad Hβ line appeared. The time lag of about 100 days between the mid-infrared and optical variability is consistent with the prediction of dust reverberation mapping.
Conclusions. The behavior of the photometric and spectroscopic observations of J1011+5442 is consistent with the argument that the repeating changing-look phenomenon is regulated by the variation in the accretion rate.
Polycyclic aromatic hydrocarbon and the ultraviolet extinction bump at the cosmic dawn
Authors: Lin Qi , Yang Xuejuan , Li Aigen , Witstok Joris 
Published: January 2025

Context. First detected in 1965, the mysterious ultraviolet (UV) extinction bump at 2175 Å is the most prominent spectroscopic feature superimposed on the interstellar extinction curve. Its carrier has remained unidentified over the six decades since its first detection, although many candidate materials have been proposed.
Aims. Widely seen in the interstellar medium of the Milky Way as well as several nearby galaxies, this bump was recently also detected by the James Webb Space Telescope (JWST) at the cosmic dawn in JADES-GS-z6-0, a distant galaxy at redshift z ≈ 6.71, corresponding to a cosmic age of just 800 million years after the big bang. Differing from that of the known Galactic and extragalactic interstellar sightlines, which always peak at ~2175 Å, the bump seen at z ≈ 6.71 peaks at an appreciably longer wavelength of ~2263 Å and is the narrowest among all known Galactic and extragalactic extinction bumps.
Methods. Here we show that the combined electronic absorption spectra quantum chemically computed for a number of polycyclic aromatic hydrocarbon (PAH) molecules closely reproduce the bump detected by JWST in JADES-GS-z6-0.
Results. This suggests that PAH molecules had already been pervasive in the Universe at an epoch when asymptotic giant branch stars had not yet evolved to make dust.
Direct high-resolution observation of feedback and chemical enrichment in the circumgalactic medium at redshift z ∼ 2.8
Authors: Peng B. , Arrigoni Battaia F. , Vishwas A. , Li M. , Iani E. , Sun F. , Li Q. , Ferkinhoff C. , Stacey G. , Cai Z. , Ivison R. 
Published: January 2025

Context. The circumgalactic medium (CGM) plays a vital role in galaxy evolution, however, studying the emission from CGM is challenging due to its low surface brightness and the complexities involved in interpreting resonant lines such as Lyman-alpha (Lyα).
Aims. The near-infrared coverage, unprecedented sensitivity, and high spatial resolution of the James Webb Space Telescope (JWST) enable us to study the optical strong lines associated with the extended Lyα “nebulae” at redshifts of 2−3. These lines serve as diagnostic tools to infer the physical conditions in the massive CGM gas reservoir of these systems.
Methods. In deep medium-band images taken by the JWST, we serendipitously discovered the [O III] emission from the CGM surrounding a massive interacting galaxy system at a redshift of z ∼ 2.8, known to be embedded in a bright extended (100 kpc) Lyα “nebula”.
Results. This is the first time that the [O III] lines have been detected from a Lyα “nebula”. The JWST images reveal that the CGM gas actually resides in narrow (∼2.5 kpc) filamentary structures with strong [O III] emission, tracing the same extent as the Lyα emission. An analysis of the [O III] suggests that the emitting CGM is fully ionized and is energetically dominated by mechanical heating. We also find that the inferred density and pressure are higher than those commonly predicted by simulations of the CGM.
Conclusions. We conclude that the observed CGM emission originates from the gas expelled by the episodic feedback processes, cooling down and enriching the CGM, while traveling a distance of at least 60 kpc. These observations demonstrate how intensive feedback processes shape gas distribution and properties in the CGM around massive halos. While access to such deep, high-resolution imaging opens up a new discovery space for investigating the CGM, it also challenges numerical simulations with respect to explaining and reproducing the exquisitely complex structures revealed by the observations.
A Be star that turned bright and blue during a major outburst
Authors: Gao Qing , Wang Wei , Baade Dietrich , Liu Jifeng , Rivinius Thomas , Arcos Catalina , de Almeida Elisson S. G. , Yuan Hailong , Bai Yu , Jankov Slobodan , Hadjara Massinissa , Bai Zhongrui , Zhang Haotong , de Amorim Tajan H. , Wu Yue , Townsend Richard H. D. , Carciofi Alex C. , Németh Péter , Curé Michel 
Published: January 2025

Context. Classical Be stars are rapidly rotating B-type stars exhibiting Balmer emission lines originating from circumstellar Keplerian gaseous disks, which likely form through episodic mass-ejection events. The currently favored model for Be star disks is the viscous decretion disk (VDD) model. However, the mechanism behind the mass ejection process during the formation of a VDD is a mystery.
Aims. We present peculiar behavior of the Be star KIC 9715425, which exhibited several minor outbursts (MIBs) and one major outburst (MAB) observed as brightenings in broadband photometry, as well as transient Hα line emission. The variability may provide valuable keys to understanding the nature of Be outbursts.
Methods. Based on Kepler, the All-Sky Automated Survey for Supernovae (ASAS-SN) and the Transiting Exoplanet Survey Satellite time-series photometry, the Large Sky Area Multi-Object Fiber Spectroscopic Telescope spectroscopy, multi-wavelength observations in the near-ultraviolet (NUV) from the Galaxy Evolution Explorer (GALEX) and optical from Gaia, Xinglong 2.16 m telescope and Isaac Newton Telescope of KIC 9715425 covering its outbursts, we determined fundamental parameters of the central star and the circumstellar disk. A frequency analysis and spectral modeling were carried out to characterize the events.
Results. During the major outburst, we find a 36% flux increase in the GALEX NUV band compared to 25% in the Kepler band, suggesting that whatever produced the flux increase should be hotter than the central B-type star. This is contradictory to the conventional scenario that the VDD should be cooler. In addition, such a high flux increase can only be accounted for by a luminous disk, which should produce a much stronger Hα emission than observed. The origin of this anomalously hot component remains unexplained.
Conclusions. Except for the bluing, the available observations of KIC 9715425 are perfectly compatible with being a normal Be star. If the bluing was physically related to the MAB, the most economical effort to identify the nature of the underlying process could be adaptive NUV and far-ultraviolet monitoring of Be stars with cyclically repeating MABs.
Full-rank imaging detection of multi-frames of ultrasonic-guided waves in welded structural plate based on arc sparse array
Authors: Zhu Xinjie , Yao Sen , Deng Mingxi , Gao Yang 
Published: January 2025

Abstract
The utilization of ultrasonic-guided wave array imaging in the detection of weld structural plates holds significant importance. This study presents a novel approach for full-rank imaging of shear horizontal-guided wave arc sparse arrays in welding structure imaging detection, the paper discusses the mechanism behind the ultrasonic-guided wave arc sparse array, specifically focusing on its full-rank imaging of multi-frames (FRIMR) capabilities in the presence of weld scattering. The receiving aperture of the arc sparse array is analyzed and discussed using the amplitude matrix and time-transition matrix. Both synthetic aperture and FRIMR of the arc sparse array are examined. The research findings demonstrate that FRIMR detection using ultrasonic-guided wave arc sparse array effectively captures scattering information equivalent to the wavelength size in the imaging detection area. This results in an average SNR improvement of 39.2% in full-frame imaging compared to multi-frames imaging. The imaging experiment validates the feasibility of the proposed imaging principle, highlighting its potential for imaging detection of welded structures. The research presented in this paper serves as a crucial foundation for future studies and applications of array imaging detection using ultrasonic-guided waves in welded structural plates.
Cholesteric liquid crystal mixtures for the switchable smart windows and light shutters: electro-optical and dielectric behavior
Authors: Pooja  , Sharma Vandna , Kumar Pankaj 
Published: January 2025

Abstract
Cholesteric liquid crystal (CLC) mixtures with variable pitch lengths were prepared for the electrical switchable smart window and light shutter applications by taking varied concentrations (2.6, 3.0, 4.0, and 5.0 wt%) of chiral dopant (R1011) having helical twisting power 37.6 μm−1 and nematic E7 liquid crystal (LC). The morphological and electro-optical analysis of these CLC mixtures filled in 10 μm thick cells were observed and reported herein, the switching of initial planar (P) and initial focal conic (FC) to homeotropic (H) states as well as vice-versa. The operating voltage of the 2.6 wt% of chiral doped CLC cell was relatively lower among all the sample cells compared with other concentrations. The maximum contrast ratio (CR) was observed for 5.0 wt% chiral doped CLC cell with initial planar state. However, the best CR was observed in 2.6 wt% CLC cell with initial FC state. The comparative macroscopic views of the P, FC, and H states in the OFF and ON conditions of applied voltage for prepared CLC cells were observed for transparent and opaque states. Further, UV–visible spectroscopy was performed in the P, FC, and H states under the application of an externally applied field to observe the absorbance and band gap behavior of the fabricated CLC cells. Additionally, chiral concentration-dependent dielectric parameters with variable frequency in initial P and FC states of the fabricated cells were also reported. The temperature-dependent phase behavior of all the prepared cells exhibited a slight decrease in the isotropic phase of LC due to the doping of chiral dopants.
Gate-tunable photodetectors based on MoTe2/MoS2 heterostructures anti-ambipolar transistors
Authors: Yan Cong , Liu Hongxia , Yu Hao , Yang Hangtian 
Published: January 2025

Abstract
Anti-ambipolar transistors (AATs) are considered as a breakthrough technology in the field of electronics and optoelectronics, which is not only widely used in diverse logic circuits, but also crucial for the realization of high-performance photodetectors. The anti-ambipolar characteristics arising from the gate-tunable energy band structure can produce high-performance photodetection at different gate voltages. As a result, this places higher demands on the parametric driving range (ΔV
g) and peak-to-valley ratio (PVR) of the AAT. Here, we demonstrate a high-performance photodetector with anti-ambipolar properties based on a van der Waals heterojunction of MoTe2/MoS2. Flexible modulation of carrier concentration and transport by gate voltage achieves a driving voltage range ΔV
g as high as 38.4 V and a PVR of 1.6 × 102. Most importantly, MoTe2/MoS2 exhibits a pronounced gate-tunable photoresponse, which is attributed to the modulation of photogenerated carrier transport by gate voltage. The MoTe2/MoS2 heterojunction photodetector exhibits excellent performance, including an impressive responsivity of 17 A W−1, a high detectivity of 4.2 × 1011 cm Hz1/2 W−1, an elevated external quantum efficiency of 4 × 103%, and a fast response time of 21 ms. Gate-tunable photodetectors based on MoTe2/MoS2 heterostructures AAT have potential to realize optoelectronic devices with high performance, providing a novel strategy to achieve high-performance photodetection.
Impact of mercury vacancy states on Shockley–Read–Hall recombination in narrow gap HgCdTe
Authors: Kozlov D V , Ikonnikov A V , Mazhukina K A , Morozov S V , Gavrilenko V I , Mikhailov N N , Dvoretsky S A , Rumyantsev V V 
Published: January 2025

Abstract
Technologically relevant narrow-gap Hg1−x
Cd
x
Te is known to contain a considerable amount of mercury vacancies that supposedly degrade carrier lifetimes. Using a semiclassical approach with no adjustable parameters, we calculate the capture coefficients for acceptor states with different binding energies. Resulting Shockley–Read–Hall recombination times agree well with the experimental data and suggest that the operating temperature of Hg1−x
Cd
x
Te detectors with ∼20 µm cutoff can be elevated above 77 K.
Radial self-accelerating acoustic beam for three-dimensional helical motion of microparticles
Authors: Chen Di-Chao , Hao Jing , Wu Da-Jian , Cheng Ying , Liu Xiao-Jun 
Published: January 2025

Abstract
Radially self-accelerating acoustic beams (RSABs) with rotating field distributions enable three-dimensional manipulation of particles. Nevertheless, the generation of desired RSABs is always a challenge. In this study, we derive a general form for the RSABs with a rotating acoustic field. We investigate the correlation between acoustic intensity and phase distribution of the RSAB in-depth via theoretical calculations. Artificial structure plates carved with Archimedean spiral slits are designed to produce two-component RSABs (TRSABs). It is found that the number of main lobes, rotational speed, and initial position of the TRSAB can be modulated by simply changing the number of arms, initial radius, and relative angle of the two sets of spirals. The experimental and numerical demonstrations confirm the ability of artificial structure plates to generate TRSABs. Finally, simulations are performed to calculate the acoustic radiation force on Rayleigh polydimethylsiloxane particles in a TRSAB. The work presented here could greatly benefit acoustic particle three-dimensional trapping and manipulation.
Chalcogenide dual-core all-solid anti-resonant fiber polarization beam splitter operating at 3 μm band
Authors: Zhang Zhenlong , Guo Haitao , Li Jianshe , Zhao Yuanyuan , Li Shuguang , Xu Yantao , Chang Yanjie , Zhang Hao 
Published: January 2025

Abstract
For the first time, we proposed a polarization beam splitter (PBS) designed based on chalcogenide dual-core all-solid anti-resonance fiber (AS-ARF) and simulated it numerically using the finite element method (FEM). Two large cladding tubes are introduced to divide the fiber core into fiber cores A and B. Mode coupling and energy exchange between the two fiber cores are enabled through the gap g between the two large cladding tubes. By adjusting the structural parameters of the AS-ARF, polarization beam-splitting ability and single-mode characteristics can be obtained. The influence of the position of the nested tube within the large cladding tube on the performance of the PBS is further investigated. The numerical results show that the beam-splitting lengths of the two proposed PBSs are 9.5 cm and 8.2 cm, respectively, and the polarization extinction ratios (PERs) are −55.98 dB and −41.35 dB at 3 μm. In the wavelength range from 2.98 μm to 3.03 μm, both PBSs can simultaneously achieve polarization beam-splitting and single-mode characteristics. The proposed chalcogenide-based dual-core AS-ARF is a suitable candidate for PBS in the mid-infrared 3 μm band.
The performance of space-fractional quantum carnot engine
Authors: Zacky Muhammad Sulthan , Sukamto Heru , Yuwana Lila , Purwanto Agus , Latifah Eny 
Published: January 2025

Abstract
This paper investigates the impact of space-fractional on the performance of a quantum heat engine. A particle confined in a one-dimensional infinite potential well serves as the working substance. The fractional parameter is incorporated into the Schrodinger equation, allowing us to derive the quantized energy of the system. The engine operates on a Carnot-like thermodynamic cycle, with heat leakage included to evaluate its performance. The findings reveal that both the efficiency and power output depend not only on the fractional parameter but also on the initial width of the potential. Notably, there exists a critical value of the initial potential width where the fractional case outperforms the non-fractional case in terms of both efficiency and power output.
Robust adaptive extended target filtering based on multiplicative noise model
Authors: Wang Li , Chen Hui , Lian Feng , Wang Xuxin 
Published: January 2025

Abstract
This study proposes two novel methods for tracking extended target with elliptical shape under non-Gaussian noise conditions. To achieve this, an explicit nonlinear measurement equation is formulated by incorporating a multiplicative noise term that connects the target's kinematic and shape parameters with the measurements. This measurement equation is employed to derive a closed-form solution for the Student's t extended Kalman filter based on multiplicative noise model (St-EKF-MNM) with recursive measurement updates. To further optimize the target tracking performance, the Hessian matrix was used to deal with the nonlinearity in the measurement equation, further derive the Student's t second-order extended Kalman filter based on multiplicative noise model (St-SOEKF-MNM). The effectiveness and robustness of the proposed methods are demonstrated with simulation.
Energy-preserving methods for gyrocenter system in strong magnetic field
Authors: Ji Lun , Tang Yifa , Wang Bin , Zhu Beibei 
Published: January 2025

Abstract
We formulate second-order and fourth-order energy-preserving methods with two explicit corrections for gyrocenter system in a strong magnetic field

1

ϵ

B
(
X
)

where the

∥
B
(
X
)

∥

2

=
O
(
1
)

and ϵ < < 1. We theoretically show that the error bound of the two methods are independent of ϵ. The two explicit corrections are both manifold corrections. The first correction is confined to the manifold that the Hamiltonian at current time step should equal to the Hamiltonian at former time step and the second correction is confined to the manifold that the Hamiltonian at current time step should equal to the original Hamiltonian. Numerical experiments illustrate the impact of the ϵ on the phase orbit and the global error. Additionally, the numerical results show that the energy-preserving methods with the first correction show its advantage in long-term energy conservation than the energy-preserving methods without correction. The energy-preserving methods with the second correction behaves better in energy conservation than those with the first correction as the energy error of the former ones can be bounded by the machine precision over long time.
Insights into dark matter direct detection experiments: decision trees versus deep learning
Authors: López-Fogliani Daniel E. , Perez Andres D. , de Austri Roberto Ruiz 
Published: January 2025

Abstract
The detection of Dark Matter (DM) remains a significant challenge in particle physics. This study exploits advanced machine learning models to improve detection capabilities of liquid xenon time projection chamber experiments, utilizing state-of-the-art transformers alongside traditional methods like Multilayer Perceptrons and Convolutional Neural Networks. We evaluate various data representations and find that simplified feature representations, particularly corrected S1 and S2 signals as well as a few shape-related features including the time difference between signals, retain critical information for classification. Our results show that while transformers offer promising performance, simpler models like XGBoost can achieve comparable results with optimal data representations. We also derive exclusion limits in the cross-section versus DM mass parameter space, showing minimal differences between XGBoost and the best performing deep learning models. The comparative analysis of different machine learning approaches provides a valuable reference for future experiments by guiding the choice of models and data representations to maximize detection capabilities.
A DAQ system with low-dead-time, high-precision TDC for APD detection efficiency calibration
Authors: Ma S. , Jin G. , Chen L. 
Published: January 2025

Abstract
Correlated photon calibration based on spontaneous parametric down-conversion (SPDC) provides a highly precise means to calibrate the detection efficiency of avalanche photodiode (APD). During the calibration process of detection efficiency via SPDC, precise measurement of the arrival time of correlated photons and accurate photon counting are essential. To achieve this goal, a data acquisition (DAQ) system with low-dead-time, high-resolution Time-to-Digital Converter (TDC) was designed in this paper. This TDC is designed based on tapped delay line (TDL), which is implemented on Xilinx Kintex-7 series field programmable gate array (FPGA). This TDC can accurately measure the time of arrival of input signals. Upon arrival of a photon signal, the TDC rapidly generates a timestamp to record the arrival time of the photon signal. Utilizing these timestamps, time delay and accurate measurements of time intervals can be achieved. The specially designed TDC input stage structure and encoding algorithm enable the alternating propagation and sampling of `01' and `10' transitions on TDL. Coupled with a pipelined architecture, the TDC's dead time is close to one clock cycle, which is 2.33 ns in the current implementation version. The structure of mode recognition and triggering ensures that the TDC can correctly calibrate time measurements and count photon counts. Experimental results show that the TDC achieves an RMS precision of better than 11.08 ps, and this measurement precision is maintained over long time intervals (0–10 us). The reliability of this DAQ for photon counting has been verified through standard signal sources.
Existence results of non-local integro-differential problem with singularity under a new fractional Musielak–Sobolev space*
Authors: Cheng Yu , Bai Zhanbing 
Published: January 2025

Abstract
In this article, we construct a new fractional Musielak–Sobolev space designed to address the non-locality associated with the corresponding integro-differential operators. The completeness, reflexivity, and uniform convexity of this new space, along with an associated embedding theorem are established. As a practical application, we investigate the solvability of a class of non-local problems with singular nonlinearities under the new fractional Musielak–Sobolev space. Based on appropriate assumptions, we derive an existence result for two weak solutions utilizing the fibering method in form of the Nehari manifold. Furthermore, we provide two concrete operator examples within the framework of the fractional Musielak–Sobolev space as examples.