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Neutron stars (NSs) can capture dark matter (DM) particles because of their deep gravitational potential and high density. The accumulated DM can affect the properties of NSs. In this work we use a general relativistic two-fluid formalism to solve the structure of DM-admixed NSs (DANSs) and the surrounding spacetime. Specifically, we pay attention to the situation where those DANSs possess DM halos. Due to the gravitational effect of the DM halo, the pulse profile of an X-ray pulsar is changed. Our study finds a universal relation between the peak flux deviation of the pulse profile and $M_{\rm halo}/R_{\rm BM}$, which is the ratio of the DM halo mass, $M_{\rm halo}$, to the baryonic matter (BM) core radius, $R_{\rm BM}$. Our results show that, when $M_{\rm halo}/R_{\rm BM}=0.292$ and the DM particle mass $m_f = 0.3\,$GeV, the maximum deviation of the profile can be larger than 100$\%$, which has implication in X-ray pulsar observation., Comment: 9 pages, 11 figures

M-type stars are the ones that flare most frequently, but how big their maximum flare energy can reach is still unknown. We present 163 flares from 162 individual M2 through L1-type stars that triggered the GWAC, with flare energies ranging from $10^{32.2}$ to $10^{36.4}$ erg . The flare amplitudes range from $\triangle G = 0.84$ to $\sim 10$ mag. Flare energy increases with stellar surface temperature ($T_{\rm eff}$) but both $\triangle G$ and equivalent duration $\log_{10}(ED)$ seem to be independent of $T_{\rm eff}$. Combining periods detected from light curves of TESS and K2, spectra from LAMOST, SDSS and the 2.16 m Telescope, and the Gaia DR3 data, we found that these GWAC flare stars are young. For the stars that have spectra, we found that these stars are in or very near to the saturation region, and $\log_{10}(L_{\rm H\alpha}/L_{\rm bol})$ is lower for M7-L1 stars than for M2-M6 stars. We also studied the relation between GWAC flare bolometric energy $E_{\rm bol}$ and stellar hemispherical area $S$, and found that $\log_{10}E_{\rm bol}$ (in erg) increases with increasing $S$ (in cm$^2$), and the maximum flare energy $\log_{10}E_{\rm bol, max} \geqslant \log_{10}S + 14.25$. For M7-L1 stars, there seem to be other factors limiting their maximum flare energies in addition to stellar hemispherical area., Comment: 18 pages, 11 figures, 4 tables

Atoms coupled to the same environment interfere with each other to yield super- or sub-radiance. Specifically, atoms in subradiant states are promising candidates for long-lifetime qubits and quantum memory because of the immunity to the common environment. However, subradiant states can still be influenced by local environments, which are incoherent for different atoms and cannot be canceled out through interference. Here we propose to break this limit by preparing a waveguide QED system in the non-Markovian regime, where the ultra-small decay rate arises because of the retarded interaction. We further show that similar effect occurs spontaneously by self-interference and can be stressed by cooperative coupling., Comment: 6 pages, 4 figures

Out-of-distribution (OOD) detection is crucial for deploying robust machine learning models, especially in areas where security is critical. However, traditional OOD detection methods often fail to capture complex data distributions from large scale date. In this paper, we present a novel approach for OOD detection that leverages the generative ability of diffusion models and the powerful feature extraction capabilities of CLIP. By using these features as conditional inputs to a diffusion model, we can reconstruct the images after encoding them with CLIP. The difference between the original and reconstructed images is used as a signal for OOD identification. The practicality and scalability of our method is increased by the fact that it does not require class-specific labeled ID data, as is the case with many other methods. Extensive experiments on several benchmark datasets demonstrates the robustness and effectiveness of our method, which have significantly improved the detection accuracy.

Let $\mu$ denot the infinite convolution generated by $\{(N_k,B_k)\}_{k=1}^\infty$ given by $$ \mu =\delta_{{N_1}^{-1}B_1}\ast\delta_{(N_1N_2)^{-1}B_2}\ast\dots\ast\delta_{(N_1N_2\cdots N_k)^{-1}B_k} *\cdots. $$ where $B_k$ is a complete residue system for each integer $k>0$. We write $$ \nu_{>k}=\delta_{N_{k+1}^{-1} B_{k+1}} * \delta_{(N_{k+1} N_{k+2})^{-1} B_{k+2}} * \cdots. $$ Since the elements in $B_k$ may have very large absolute values, the infinite convolution may not be compactly supported. In this paper, we study the necessary and sufficient conditions for such infinite convolutions being a spectral measure. Generally, for such infinite convolutions, the necessary conditions for spectrality mainly depend on the properties of the polynomials generated by the complete residue systems. The main result shows that if every $B_k$ satisfies uniform discrete zero condition, and $\{\nu_{>k}\}_{k=1}^\infty$ is {\it tight}, then $\# B_k | N_k$ for all integers $k\geq 2$. For some special complete residue systems $\{B_k\}_{k=1}^\infty$, we provide the necessary and sufficient conditions for $\mu$ being a spectral measure.

Utilizing an equivparticle model with both linear confinement and leading-order perturbative interactions, we obtain systematically the properties of strangelets and nonstrange quark matter ($ud$QM) nuggets at various baryon ($A$) and charge ($Z$) numbers, where the detailed single-quark-energy levels are fixed by solving Dirac equations in mean-field approximation (MFA). We then examine the structures of compact dwarfs made of light strangelets or $ud$QM nuggets forming body-centered cubic lattices in a uniform electron background. Despite the strangelets and $ud$QM nuggets generally become more stable at larger $A$, the compact dwarfs are still stable since the fusion reactions between those objects do not take place in the presence of a Coulomb barrier, which is similar to the cases of light nuclei in normal white dwarfs. If $ud$QM dwarfs or strangelet dwarfs are covered with normal matter, their masses and radii become larger but do not exceed those of ordinary white dwarfs. Finally, we investigate the radial oscillation frequencies of $ud$QM dwarfs and strangelet dwarfs, and find that their frequencies are typically higher than traditional white dwarfs. The stability of compact dwarfs are then analysised by examining radial oscillation frequencies of the fundamental mode, where compact dwarfs covered by normal matter are still stable.

The intermediate-mass-ratio inspirals (IMRIs) may be surrounded by dark matter (DM) minispikes. The dynamical friction from these DM minispike structures can affect the dynamics and the gravitational wave (GW) emission of the IMRIs. We analyze the effects of general dynamical friction, with a particular contribution from DM particles moving faster than the stellar-mass black hole in an eccentric IMRI. The results show that the dynamical friction caused by these DM particles tends to eccentricify the orbit, and the general dynamical friction is able to increase the eccentricity. We also analyze the effects of general dynamical friction on the GW characteristic strain. The results indicate that the peak value of the characteristic strain occurs at higher frequencies as the power law index of DM minispike $\gamma_\mathrm{sp}$ increases. For the first time, a general analytical relation between the frequency peak value of characteristic strain of GWs and $\gamma_\mathrm{sp}$ is established. Using the analytical relation, the presence of DM and its halo density may be determined potentially from future GW data., Comment: 7 pages, 4 figures

For the first time, we have introduced the Pyramid Constellation of Gravitational Wave Observatory (PCGO) for GW polarization detection. The PCGO is composed of four identical spacecrafts (S/Cs). The laser telescopes and their pointing structures are mounted on the S/C platform and are evenly distributed at three locations 120 degrees apart. Compared to a three-S/C configuration, the addition of a fourth S/C and its mounted telescope serve as redundant backups, especially for the telescopes, which together with the other two telescopes, automatically form a stable mass center for the platform without the need for trim mass. Since the radial distance of S/C4 is greater than that of the other spacecraft, the three arm lengths associated with S/C4 change significantly over a one-year period. Time delay interferometry (TDI) has been proven effective for suppressing frequency noise in this context. The unequal arm Michelson TDI configuration and the Sagnac TDI configuration are equally effective for eliminating the laser frequency noise based on the PCGO configuration. Compared to the configurations of LISA, Taiji, and TianQin, the PCGO has more combinations of optical paths in its TDI system, offering greater sensitivity to GW signals. The configuration of PCGO is simultaneously sensitive to the six polarization modes of GWs, which means that it allows for greater flexibility in extracting the polarization components from the total GW polarization signals., Comment: 12 pages, 5 figures

With wearing masks becoming a new cultural norm, facial expression recognition (FER) while taking masks into account has become a significant challenge. In this paper, we propose a unified multi-branch vision transformer for facial expression recognition and mask wearing classification tasks. Our approach extracts shared features for both tasks using a dual-branch architecture that obtains multi-scale feature representations. Furthermore, we propose a cross-task fusion phase that processes tokens for each task with separate branches, while exchanging information using a cross attention module. Our proposed framework reduces the overall complexity compared with using separate networks for both tasks by the simple yet effective cross-task fusion phase. Extensive experiments demonstrate that our proposed model performs better than or on par with different state-of-the-art methods on both facial expression recognition and facial mask wearing classification task.

Sky locating massive black hole binaries (MBHBs) from the foreground of double white dwarf (DWD) is essential for space-based gravitational wave (GW) detection. In an orbit period of the space crafts, there is an optimal orbital position of the GW detectors to observe GW sources, where the signal intensity is at its peak. From the model Q3-d, five MBHB sources are selected based on the optimal observation orbital positions of the GW detectors, which are associated with the orientation of the MBHB perpendicular to the detection arms. For two MBHB sources of lower intensity, luminosity distance uncertainties, $\Delta D_L$/$D_L$ at the 95$\%$ confidence level from the overlapping GW signals of MBHB and DWD sources, when employing wavelet decomposition and reconstruction methods, are improved by $\sim$ 2 times and $\sim$ 10 times. Besides, the angular resolutions $\Delta \Omega_s$ are also improved by a factor of $\sim$ 35 and $\sim$ 8. These results imply that we can obtain relatively high accuracy of quickly localizing MBHB from the overlapped GW signals with DWDs at the best observation orbit position. The luminosity distance uncertainties at the 95$\%$ confidence level for MBHB sources with the higher sign-noise ratio, have constraints on the precision of the Hubble constant., Comment: 10 pages, 5 figures. arXiv admin note: text overlap with arXiv:2310.16796

With the rapid advancement of technology, Augmented Reality (AR) technology, known for its ability to deeply integrate virtual information with the real world, is gradually transforming traditional work modes and teaching methods. Particularly in the realms of remote work and online education, AR technology demonstrates a broad spectrum of application prospects. This paper delves into the application potential and actual effects of AR technology in remote work and education. Through a systematic literature review, this study outlines the key features, advantages, and challenges of AR technology. Based on theoretical analysis, it discusses the scientific basis and technical support that AR technology provides for enhancing remote work efficiency and promoting innovation in educational teaching models. Additionally, by designing an empirical research plan and analyzing experimental data, this article reveals the specific performance and influencing factors of AR technology in practical applications. Finally, based on the results of the experiments, this research summarizes the application value of AR technology in remote work and education, looks forward to its future development trends, and proposes forward-looking research directions and strategic suggestions, offering empirical foundation and theoretical guidance for further promoting the in-depth application of AR technology in related fields.

Image captioning strives to generate pertinent captions for specified images, situating itself at the crossroads of Computer Vision (CV) and Natural Language Processing (NLP). This endeavor is of paramount importance with far-reaching applications in recommendation systems, news outlets, social media, and beyond. Particularly within the realm of news reporting, captions are expected to encompass detailed information, such as the identities of celebrities captured in the images. However, much of the existing body of work primarily centers around understanding scenes and actions. In this paper, we explore the realm of image captioning specifically tailored for celebrity photographs, illustrating its broad potential for enhancing news industry practices. This exploration aims to augment automated news content generation, thereby facilitating a more nuanced dissemination of information. Our endeavor shows a broader horizon, enriching the narrative in news reporting through a more intuitive image captioning framework., Comment: 10 pages, 4 figures

The wide spread of rumors on social media has caused a negative impact on people's daily life, leading to potential panic, fear, and mental health problems for the public. How to debunk rumors as early as possible remains a challenging problem. Existing studies mainly leverage information propagation structure to detect rumors, while very few works focus on correlation among users that they may coordinate to spread rumors in order to gain large popularity. In this paper, we propose a new detection model, that jointly learns both the representations of user correlation and information propagation to detect rumors on social media. Specifically, we leverage graph neural networks to learn the representations of user correlation from a bipartite graph that describes the correlations between users and source tweets, and the representations of information propagation with a tree structure. Then we combine the learned representations from these two modules to classify the rumors. Since malicious users intend to subvert our model after deployment, we further develop a greedy attack scheme to analyze the cost of three adversarial attacks: graph attack, comment attack, and joint attack. Evaluation results on two public datasets illustrate that the proposed MODEL outperforms the state-of-the-art rumor detection models. We also demonstrate our method performs well for early rumor detection. Moreover, the proposed detection method is more robust to adversarial attacks compared to the best existing method. Importantly, we show that it requires a high cost for attackers to subvert user correlation pattern, demonstrating the importance of considering user correlation for rumor detection., Comment: 10 pages, 5 figures

Photonuclear reactions using a laser Compton scattering (LCS) gamma source provide a new method for producing radioisotopes for medical applications. Compared with the conventional method, this method has the advantages of a high specific activity and less heat. Initiated by the Shanghai Laser Electron Gamma Source (SLEGS), we conducted a survey of potential photonuclear reactions, $(\upgamma,n)$, $(\upgamma,p)$, and $(\upgamma,\upgamma')$ whose cross-sections can be measured at SLEGS by summarizing the experimental progress. In general, the data are rare and occasionally inconsistent. Therefore, theoretical calculations are often used to evaluate the production of medical radioisotopes. Subsequently, we verified the model uncertainties of the widely used reaction code TALYS-1.96, using the experimental data of the \ce{^100Mo}$(\upgamma,n)$\ce{^99Mo}, \ce{^65Cu}$(\upgamma,n)$\ce{^64Cu}, and \ce{^68Zn}$(\upgamma,p)$\ce{^67Cu} reactions., Comment: 16 pages, 19 figures

The detection of GW170817/GRB170817A implied the strong association between short gamma-ray bursts (SGRBs) and binary neutron star (BNS) mergers which produce gravitational waves (GWs). More evidence is needed to confirm the association and reveal the physical processes of BNS mergers. The upcoming High Altitude Detection of Astronomical Radiation (HADAR) experiment, excelling in a wide field of view (FOV) and a large effective area above tens of GeV, is a hope for the prompt detection of very-high-energy (VHE; > 10 GeV) SGRBs. The aim of this paper is to simulate and analyse GW/SGRB joint detections by future GW detector networks in synergy with HADAR, including the second generation LIGO, Virgo and KAGRA and the third generation ET and CE. We provide a brief introduction of the HADAR experiment for SGRB simulations and its expected SGRB detections. For GW simulations, we adopt a phenomenological model to describe GWs produced by BNS mergers and introduce the signal-noise ratios (SNRs) as detector responses. Following a theoretical analysis we compute the redshift-dependent efficiency functions of GW detector networks. We then construct the simulation of GW detection by Monte Carlo sampling. We compare the simulated results of LIGO-Virgo O2 and O3 runs with their actual detections as a check. The combination of GW and SGRB models is then discussed for joint detection, including parameter correlations, triggered SNRs and efficiency skymaps. The estimated joint detection rates are 0.09-2.52 per year for LHVK network with HADAR under different possible configurations, and approximately 0.27-7.89 per year for ET+CE network with HADAR.

In a quantum Trojan-horse attack (THA), eavesdroppers learn encoded information by injecting bright light into encoded or decoded devices of quantum key distribution (QKD) systems. These attacks severely compromise the security of non-isolated systems. Thus, analytical security bound was derived in previous studies. However, these studies achieved poor performance unless the devices were strongly isolated. Here, we present a numerical method for achieving improved security bound for a decoy-state QKD system under THAs. The developed method takes advantage of the well-established numerical framework and significantly outperforms previous analytical bounds regarding the achievable final key and secure transmitted distance. The results provide a new tool for investigating the efficient security bounds of THA in practical decoy-state QKD systems. This study constitutes an important step toward securing QKD with real-life components., Comment: Comments are welecomed

Fast radio bursts (FRBs) can present a variety of polarization properties, and some of them have narrow spectra. We study spectral properties from perspectives of intrinsic radiation mechanisms and absorption during the waves propagating in the magnetosphere. The intrinsic radiation mechanisms are considered by invoking quasi-periodic bunch distribution and perturbations on charged bunches moving on curved trajectories. The narrow-band emission likely reflects some quasi-periodic structure on the bulk of bunches, which may be due to quasi-periodically sparking in a ``gap'' or quasi-monochromatic Langmuir waves. A sharp spike would appear at the spectrum if the perturbations can induce a monochromatic oscillation of bunches, however, it is hard to create a narrow spectrum because the Lorentz factor has large fluctuations so that the spike disappears. Both the bunching mechanism and perturbations scenarios share the same polarization properties with a uniformly distributed bulk of bunches. We investigate absorption effects including Landau damping and curvature self-absorption in the magnetosphere, which are significant at low frequencies. Subluminous O-mode photons can not escape from the magnetosphere due to the Landau damping, leading to a height-dependent lower frequency cut-off. Spectra can be narrow when the frequency cut-off is close to the characteristic frequency of curvature radiation, while such conditions can only be met sometimes. The spectral index is 5/3 at low-frequency bands due to the curvature self-absorption but not as steep as the observations. The intrinsic radiation mechanisms are more likely to generate the observed narrow spectra of FRBs rather than the absorption effects., Comment: 19 pages, 11 figures, A&A accepted

Landauer's principle shows that the minimum energy cost to reset a classical bit in a bath with temperature $T$ is $k_{B}T\ln2$ in the infinite time. However, the task to reset the bit in finite time has posted a new challenge, especially for quantum bit (qubit) where both the operation time and controllability are limited. We design a shortcut-to-isothermal scheme to reset a qubit in finite time $\tau$ with limited controllability. The energy cost is minimized with the optimal control scheme with and without nonholonomic constraint. This optimal control scheme can provide a reference to realize qubit reset with minimum energy cost for the limited time., Comment: 8 pages, 7 figures

Quickly localizing the identified white dwarf (WD) binaries is the basic requirement for the space-based gravitational wave (GW) detection. In fact, the amplitude of GW signals are modulated by the periodic motion of GW detectors on the solar orbit. The intensity of the observed signals is enhanced according to the observation time beyond a year to enhance a high signal to noise ratio (SNR). As data gap exists, the completeness of the data observed for a long time depends on filling gaps in the data. Actually, in a year period, the GW sources have a best observation orbit position of GW detectors, where the detector response intensity of GW is maximum. Thus, the best positions, where the direction of GW source is perpendicular to the detection arms, can be searched for the verified GW sources of the sky map to enhance SNR too. For the three arms response intensity of the GW signals changing more clearly with the location of the GW sources relative to the detector, the noises and the suppression of noise by time delay interferometer are ignored. In the four chosen sources, the two verification WD binaries: J0806 and V407 Vul are observed at the best orbit positions by TAIJI for the short time of 2 and 3 days respectively. The intensities of those GWs are above the values of the TAIJI sensitivity curve, significantly. Compared with a single detector, the network of two detectors does not significantly improve the accuracy of location of the verification binaries. These results imply that the searching of GW signals and parameter estimation of GW sources from the experimental data of the space-based mission do not ignore the orbit positions relevant to GW sources., Comment: 22 pages, 15 figures

Atomic force microscope (AFM) generally works on the basis of manipulating absolute magnitude of van der Waals (vdW) force between the tip and specimen. The force is, however, less sensitive to alternation of atom species than to tip-sample separations, resulting in the difficulty of compositional identification, even under multi-modal strategies and other AFM variations. Here, we report a phenomenon of light enhancement of van der Waals force (LvF), and the enhancement factor is found specific to materials. The force difference prior and after illumination, instead of the tip-specimen force itself, is employed for discriminating heterogeneous phases. The corresponding LvF microscopy (LvFM) demonstrates not only a ultra-high compositional resolution represented by 20 dB enhancement factor and 150 times of the detection limit, but also a sub-10 nm lateral spatial resolution much smaller than the tip size of 20 nm. The simplicity of the opto-thermal mechanism, minuteness of excitation light power and wide availability of boosting lasers at various wavelengths imply broad applications of LvFM on nano-materials characterization, particularly on two-dimensional semiconductors that are promising as new generation of chip materials.

The HADAR experiment, which will be constructed in Tibet, China, combines the wide-angle advantages of traditional EAS array detectors with the high sensitivity advantages of focused Cherenkov detectors. Its physics objective is to observe transient sources such as gamma-ray bursts and counterparts of gravitational waves. The aim of this study is to utilize the latest AI technology to enhance the sensitivity of the HADAR experiment. We have built training datasets and models with distinctive creativity by incorporating relevant physical theories for various applications. They are able to determine the kind, energy, and direction of incident particles after careful design. We have obtained a background identification accuracy of 98.6%, a relative energy reconstruction error of 10.0%, and an angular resolution of 0.22-degrees in a test dataset at 10 TeV. These findings demonstrate the enormous potential for enhancing the precision and dependability of detector data analysis in astrophysical research. Thanks to deep learning techniques, the HADAR experiment's observational sensitivity to the Crab Nebula has surpassed that of MAGIC and H.E.S.S. at energies below 0.5 TeV and remains competitive with conventional narrow-field Cherenkov telescopes at higher energies. Additionally, our experiment offers a fresh approach to dealing with strongly connected scattered data.

Soft gamma-ray repeaters (SGRs) are widely understood as slowly rotating isolated neutron stars. Their generally large spin-down rates, high magnetic fields, and strong outburst energies render them different from ordinary pulsars. In a few giant flares (GFs) and short bursts of SGRs, high-confidence quasi-periodic oscillations (QPOs) were observed. Although remaining an open question, many theoretical studies suggest that the torsional oscillations caused by starquakes could explain QPOs. Motivated by this scenario, we systematically investigate torsional oscillation frequencies based on the strangeon-star (SS) model with various values of harmonic indices and overtones. To characterize the strong-repulsive interaction at short distances and the non-relativistic nature of strangeons, a phenomenological Lennard-Jones model is adopted. We show that, attributing to the large shear modulus of SSs, our results explain well the high-frequency QPOs ($\gtrsim 150\,\mathrm{Hz}$) during the GFs. The low-frequency QPOs ($\lesssim 150\,\mathrm{Hz}$) can also be interpreted when the ocean-crust interface modes are included. We also discuss possible effects of the magnetic field on the torsional mode frequencies. Considering realistic models with general-relativistic corrections and magnetic fields, we further calculate torsional oscillation frequencies for quark stars. We show that it would be difficult for quark stars to explain all QPOs in GFs. Our work advances the understanding of the nature of QPOs and magnetar asteroseismology., Comment: 9 pages, 7 figures; accepted by MNRAS

In this paper, we provide an experimental proof-of-concept of this dynamic 3D current manipulation through a 3D-printed reconfigurable meta-radiator with periodically slotted current elements. By utilizing the working frequency and the mechanical configuration comprehensively, the radiation pattern can be switched among 12 states. Inspired by maximum likelihood method in digital communications, a robustness-analysis method is proposed to evaluate the potential error ratio between ideal cases and practice. Our work provides a previously unidentified model for next-generation information distribution and terahertz-infrared wireless communications.