bluuebunny/crossref_metadata_2025 huggingface dataset:
Benchmarking various nonadiabatic semiclassical mapping dynamics methods with tensor-train thermo-field dynamics
Authors: Liu Zengkui , Lyu Ningyi , Hu Zhubin , Zeng Hao , Batista Victor S. , Sun Xiang
Published: July 2024

Accurate quantum dynamics simulations of nonadiabatic processes are important for studies of electron transfer, energy transfer, and photochemical reactions in complex systems. In this comparative study, we benchmark various approximate nonadiabatic dynamics methods with mapping variables against numerically exact calculations based on the tensor-train (TT) representation of high-dimensional arrays, including TT-KSL for zero-temperature dynamics and TT-thermofield dynamics for finite-temperature dynamics. The approximate nonadiabatic dynamics methods investigated include mixed quantum–classical Ehrenfest mean-field and fewest-switches surface hopping, linearized semiclassical mapping dynamics, symmetrized quasiclassical dynamics, the spin-mapping method, and extended classical mapping models. Different model systems were evaluated, including the spin-boson model for nonadiabatic dynamics in the condensed phase, the linear vibronic coupling model for electronic transition through conical intersections, the photoisomerization model of retinal, and Tully’s one-dimensional scattering models. Our calculations show that the optimal choice of approximate dynamical method is system-specific, and the accuracy is sensitively dependent on the zero-point-energy parameter and the initial sampling strategy for the mapping variables.
Observation of temperature-dependent capture cross section for main deep-levels in β-Ga2O3
Authors: Vasilev A. A. , Kochkova A. I. , Polyakov A. Y. , Romanov A. A. , Matros N. R. , Alexanyan L. A. , Shchemerov I. V. , Pearton S. J.
Published: July 2024

Direct observation of the capture cross section is challenging due to the need for extremely short filling pulses in the two-gate Deep-Level Transient Spectroscopy (DLTS). Simple estimation of the cross section can be done from DLTS and admittance spectroscopy data but it is not feasible to distinguish temperature dependence of pre-exponential and exponential parts of the emission rate equation with sufficient precision conducting a single experiment. This paper presents experimental data of deep levels in β-Ga2O3 that has been gathered by our group since 2017. Based on the gathered data, we propose a derivation of apparent activation energy (Eam) and capture cross section (σnm) assuming the temperature dependent capture via the multiphonon emission model, which resulted in a strong correlation between Eam and σnm according to the Meyer–Neldel rule, which allowed us to estimate low- and high-temperature capture coefficients C0 and C1 as well as capture barrier Eb. It also has been shown that without considering the temperature dependence of capture cross section, the experimental values of σn are overestimated by 1–3 orders of magnitude. A careful consideration of the data also allows to be more certain identifying deep levels by their “fingerprints” (Ea and σn) considering two additional parameters (EMN and σ00) and to verify the density functional theory computation of deep-level recombination properties.
Effects of mass and damping ratios on the flow-induced vibration of two staggered circular cylinders
Authors: Chen Qi , Li Tian , Yang Qingshan , Law Siu-seong , Cao Shuyang , Zhang Xuesen
Published: July 2024

The mass ratio between structure and fluid and the structural damping ratio have been shown to significantly affect the flow-induced vibration (FIV) of an isolated circular cylinder. Their influences on multiple staggered circular cylinders commonly found in offshore structures have, however, not been clearly understood. This study numerically investigates the vibration responses and flow field of two staggered circular cylinders with the shear stress transfer k–ω turbulence model and the overset mesh method. The accuracy of the numerical method adopted is validated against published experimental results, and the effects of the mass ratio and damping ratio on FIV are systematically investigated. The structural responses of the two cylinders are found more sensitive to the mass ratio than the damping ratio. The amplitude of vibration increases, in general, with a reduction in the mass ratio or damping ratio, and the vibration is much more significant when the mass ratio is less or equal to unity as compared to those from other mass ratio values. A reduction in the mass ratio is found leading to more diverse vortex shedding modes with fast transition from one into another. The self-excited dynamic forces represented by the added mass ratio ma* and added damping ratio ζa are further analyzed. It is found that the added mass ratio is positive under low inflow velocity, and it gradually becomes negative with higher inflow velocity. The added damping ratio is generally negative under low inflow velocity and it increases with the inflow velocity. Furthermore, the added damping ratio decreases with the inflow velocity only when the mass ratio is smaller than unity.
Enhancing and broadening the photoresponse of CdS nanowire by constructing core–shell heterostructure
Authors: Liu Fengjing , Fu Zhen , Sun Li , Yang Bowen , Zang Zeqi , Wang Mingxu , Sa Zixu , Hao Xiaotao , Yang Zai-xing
Published: July 2024

Limited by the severe surface recombination and large bandgap, it is still a challenge to achieve a high-performance broad-spectrum photodetector based on CdS nanowires (NWs). In this work, the CdS/GeS core–shell heterostructure is constructed to enhance and broaden the photoresponse of CdS NWs. The CdS/GeS core–shell heterostructure NWs are prepared by the chemical vapor deposition method, exhibiting smooth surfaces, controlled shell thicknesses, and compositions. From the UV-Vis-near-infrared (NIR) diffuse reflectance spectrum, PL, and time-resolved photoluminescence studies, it is found that the surface recombination is weakened and the light absorption range is widened after the constructing core–shell heterostructure. When configured into photodetectors, the responsivity of the CdS/GeS core–shell heterostructure NWs is up to 76.8 A W−1, which is 10 folds higher than that of pristine CdS NWs. Furthermore, the photoresponse wavelength of the CdS/GeS core–shell heterostructure NWs is extended from 405 to 850 nm. The improved photodetection performance is attributed to the effective separation of photogenerated carriers at the heterostructure interface, weakened surface recombination, and excellent light absorption of the GeS shell. All results imply that constructing core–shell heterostructures is an effective strategy for constructing high-performance photodetectors.
Numerical simulation of droplet characterized by Rolie–Poly model with finite extensibility passing through cylinder obstacles
Authors: Cao Limei , Pan Ziling , Guo Bo , Sun Fanji , Si Xinhui
Published: July 2024

The deformation and rupture of viscoelastic droplet passing through cylinder obstacles in a microchannel are investigated using OpenFOAM. The constitute relationship of droplet is modeled by the Rolie–Poly model with finite extensibility, and the two-phase interface is tracked by the volume of fluid method. The effects of capillary number (Ca), the distance between cylinders (l1), relaxation time ratio (ξ), Weissenberg number (Wi), etc., on droplet deformation and rupture are mainly explored. When Ca decreases, the symmetry of droplet rupture changes and three behaviors of the droplet, i.e., symmetrical rupture, asymmetrical rupture, and non-rupture, can be captured. Further research shows that the stagnation area formed between cylinders is broken with the increase in l1, where the two sub-droplets merge again. Viscoelastic droplet with a smaller relaxation time ratio ξ is more likely to extend into thin and durable filament. Especially, when ξ=0.2, the filament will break many times during the stretching process. During above-mentioned two kinds of development, the normal stress difference develops obviously at the places, where the filament breaks or the sub-droplets combine together. This may imply that the normal stress difference facilitates the rupture and coalescence of droplets. In addition, with the increase in elasticity, the normal stress difference tends to develop at the phase interface.
Effects of temperature on fracture and damage characteristics of deep granite
Authors: Hou Chenglu , Wu Yeqiu , Pu Chao , Wang Hongbo , Cheng Yugang , Wu Yang , Hao Xiaotian , Long Kun
Published: July 2024

Investigating the fracture- and failure-related behaviors of rock that is subjected to temperature treatment is important for handling warm rock reservoirs during deep mining of hot dry rock and processing high-level radioactive waste. In this study, we use the semi-circular bending test in combination with acoustic emission (AE) monitoring technology to examine the characteristics of fracture and damage in granite treated at different temperatures and under different fracture modes at a depth of 750 m in the Daliuhang Gold Mine in China. The results showed that the peak load and fracture toughness of granite decreased to varying extents when it was treated at increasingly higher temperatures. The high temperature substantially reduced the bonding capacity of the particles of rock, and led to the formation of a large number of microcracks that dislodged the particles of rock along the edges of the samples. The changes in the AE counts during the different loading phases can be categorized into stabilization, increase, sudden increase, and decay stages. The damage-related variable based on the cumulative AE count revealed that samples treated at and below a temperature of 300 °C were mainly damaged in the late period of loading and exhibited brittle failure. Damage began to accumulate as early as in the middle period of loading in samples treated at temperatures greater than or equal to 600 °C. The results of this study provide a useful reference for mining deeply buried granite under different temperature gradients and fracture modes.
Dynamics of large oscillator populations with random interactions
Authors: Pikovsky Arkady , Smirnov Lev A.
Published: July 2024

We explore large populations of phase oscillators interacting via random coupling functions. Two types of coupling terms, the Kuramoto–Daido coupling and the Winfree coupling, are considered. Under the assumption of statistical independence of the phases and the couplings, we derive reduced averaged equations with effective non-random coupling terms. As a particular example, we study interactions defined via the coupling functions that have the same shape but possess random coupling strengths and random phase shifts. While randomness in coupling strengths just renormalizes the interaction, a distribution of the phase shifts in coupling reshapes the coupling function.
Nonlinear composition dependence of hydrogen bond lifetime in water–DMSO binary mixtures: The role of hydrophobic interaction
Authors: Mondal Sangita , Bagchi Biman
Published: July 2024

The lifetime of a hydrogen bond between water and dimethyl sulfoxide (DMSO) is found to be considerably longer than that between two water molecules in neat water. This is counter-intuitive because the charge on the oxygen in DMSO is considerably less than that in water. Additionally, the strength of the water–dimethyl sulfoxide (w–D) hydrogen bond is found to be strongly composition dependent; the lifetime of the hydrogen bond is ten times larger at 30% than at very low concentrations. Using computer simulations, we perform microscopic structural and dynamic analysis to find that these anomalies arise at least partly from an “action-at-a-distance” effect where the attraction between the hydrophobic methyl groups results in the self-aggregation of DMSO molecules that “cages” both the rotational and linear motions of the molecules involved. This is reflected in the observed strong correlation of the lifetime with the local coordination number of the associated methyl groups. The elongated w–D h-bond lifetime causes a slowdown of collective dynamics and affects the lifetime of the w–w h-bond. This nonlinear feedback mechanism explains the strong composition dependence of viscosity and is anticipated to play a dominant role in many self-assemblies. Furthermore, the w–D hydrogen bond breaking mechanism changes from low to high DMSO concentration, a phenomenon not anticipated a priori. We introduce a new order parameter-based free energy surface of the bond breaking pathway. A two-dimensional transition state rate theory calculation is performed for the lifetime of the w–D h-bond that is found to be semi-quantitatively accurate.
Array strategy enhances low-frequency radiation intensity and low-frequency magnetic field sensing SNR of magnetoelectric antenna
Authors: Wang Yinan , Zi Guohao , Song Enzhong , Wang Yuanhang , Zhao Shanlin , Ma Zhibo
Published: July 2024

The magnetoelectric (ME) coupling effect is a more effective approach for reducing antenna size. Nevertheless, at low frequencies, a single ME structure generates a weak signal strength and a low signal-to-noise ratio (SNR). This study utilized an array strategy to improve the radiation and induced electromagnetic field performance of ME antennas. In this study, the array ME coupling structure, composed of Metglas and Pb (Zr1−xTix) O3 (PZT) bilayers, was operated through ME coupling resonance modes. The relationship between the sensitivity and SNR of the serially connected ME antenna array and the number of series connections was determined. On the transmission side, the impact of the multi-source power supply modes on the radiation intensity and directivity of the ME antennas was analyzed. The sensitivity, SNR, magnetic detection limit, directivity, and radiation range of the single ME and array ME antennas were tested for the key parameters. Finally, it was demonstrated that at a frequency of 31.75 kHz, the array strategy achieved a low-frequency signal transmission distance of up to 48.1 m, which is 1.7 times that of a single ME antenna. This array strategy significantly enhances the radiation intensity and magnetic field SNR of ME antennas in the low-frequency range, demonstrating its application prospects in the field of low-frequency communication.
Palmitoylation at a conserved cysteine residue facilitates gasdermin D-mediated pyroptosis and cytokine release
Authors: Liu Zhonghua , Li Sai , Wang Chuanping , Vidmar Kaylynn J. , Bracey Syrena , Li Ling , Willard Belinda , Miyagi Masaru , Lan Tong , Dickinson Bryan C. , Osme Abdullah , Pizarro Theresa T. , Xiao Tsan Sam
Published: July 2024

Gasdermin D (GSDMD)-mediated pyroptotic cell death drives inflammatory cytokine release and downstream immune responses upon inflammasome activation, which play important roles in host defense and inflammatory disorders. Upon activation by proteases, the GSDMD N-terminal domain (NTD) undergoes oligomerization and membrane translocation in the presence of lipids to assemble pores. Despite intensive studies, the molecular events underlying the transition of GSDMD from an autoinhibited soluble form to an oligomeric pore form inserted into the membrane remain incompletely understood. Previous work characterized
S
-palmitoylation for gasdermins from bacteria, fungi, invertebrates, as well as mammalian gasdermin E (GSDME). Here, we report that a conserved residue Cys191 in human GSDMD was
S
-palmitoylated, which promoted GSDMD-mediated pyroptosis and cytokine release. Mutation of Cys191 or treatment with palmitoyltransferase inhibitors cyano-myracrylamide (CMA) or 2-bromopalmitate (2BP) suppressed GSDMD palmitoylation, its localization to the membrane and dampened pyroptosis or IL-1β secretion. Furthermore,
Gsdmd
-dependent inflammatory responses were alleviated by inhibition of palmitoylation in vivo. By contrast, coexpression of GSDMD with palmitoyltransferases enhanced pyroptotic cell death, while introduction of exogenous palmitoylation sequences fully restored pyroptotic activities to the C191A mutant, suggesting that palmitoylation-mediated membrane localization may be distinct from other molecular events such as GSDMD conformational change during pore assembly. Collectively, our study suggests that
S
-palmitoylation may be a shared regulatory mechanism for GSDMD and other gasdermins, which points to potential avenues for therapeutically targeting
S
-palmitoylation of gasdermins in inflammatory disorders.
Eyes do not lie but words do
Authors: Arslan Seçkin , Tunalı Elif Tutku , Çetin Yağmur , Aydın Özgür
Published: July 2024

Evidentiality encodes how a speaker has access to the information contained in his/her proposition. It has been
shown that some ‘evidential language’ speakers make a deliberate choice of evidentials while telling lies (Aikhenvald 2004). In this study, we recruited 40 native speakers of Turkish, an ‘evidential language’, to
judge statements with evidentials using an eye-movement-monitoring-during-reading study with an end-of-sentence deception
detection task. The participants read sentences with four conditions, containing a direct or indirect evidential form either
compatible or incompatible with the given information source. Our results show that the indirect evidential condition was detected
as a lie more often than the direct evidential condition. Readers had the tendency to judge stimulus material with
source-evidentiality mismatch to be untruthful. These findings were mirrored in the eye-movement data, as we found gaze duration
to be longer at the critical verb region for indirect evidential and mismatch conditions.
Tipler naked singularities in N dimensions
Authors: Solanki Kharanshu N , Mosani Karim , Deshpande Omkar , Joshi Pankaj S
Published: July 2024

A spacetime singularity, identified by the existence of incomplete causal geodesics in the spacetime, is called a (Tipler) strong curvature singularity if the volume form acting on independent Jacobi fields along causal geodesics vanishes in the approach of the singularity. It is called naked if at least one of these causal geodesics is past incomplete. Here, we study the formation of strong curvature naked singularities arising from spherically symmetric gravitational collapse of general type-I matter fields in an arbitrarily finite number of dimensions. In the spirit of Joshi and Dwivedi (1993Phys. Rev.D475357), and Goswami and Joshi (2007Phys. Rev.D76084026), beginning with regular initial data, we derive two distinct (but not mutually exclusive) conditions, which we call thepositive root condition(PRC) and thesimple positive root condition(SPRC), that serve as necessary and sufficient conditions, respectively, for the existence of naked singularities. In doing so, we generalize the results of both the aforementioned works. We further restrict the PRC and the SPRC by imposing the curvature growth condition (CGC) of Clarke and Krolak (1985J. Geom. Phys.2127) on all causal curves that satisfy the causal convergence condition. The CGC then gives a sufficient condition ensuring that the naked singularities implying the PRC and implied by the SPRC, are of strong curvature type and hence correspond to the inextendibility of the spacetime. Using the CGC, we extend the results of Mosaniet al(2020Phys. Rev.D101044052) (that hold for dimensionN = 4) to the caseN = 5, showing that strong curvature naked singularities can occur in this case. However, for the caseN⩾6, we show that past-incomplete causal curves that identify naked singularities do not satisfy the CGC. These results shed light on the validity of the cosmic censorship conjectures in arbitrary dimensions.
Scalar fields around a rotating loop quantum gravity black hole: waveform, quasi-normal modes and superradiance
Authors: Xia Zhong-Wu , Yang Hao , Miao Yan-Gang
Published: July 2024

The rotating loop quantum gravity black hole is a newly proposed non-singular black hole, which eliminates spacetime singularities when a regularization parameter is introduced through loop quantum corrections. This parameter is expected to give rise to observable effects. In this paper, the dynamical behavior of a scalar field near a rotating loop quantum gravity black hole is investigated. Given a small initial perturbation, we obtain the waveform of massless scalar fields evolving over time. By analyzing the waveform, we find that the regularization parameter only affects the damping oscillation of waveform, but not the initial outburst and late-time tail stages. This behavior is characterized by quasi-normal modes (QNMs). Under scalar field perturbations, the loop quantum black holes remain stable. Moreover, we calculate the QNMs of massive scalar fields by three numerical methods, which are the Prony, WKB, and shooting methods, respectively. Our results indicate that the real part of QNMs increases when the regularization parameter and angular momentum grow, while the imaginary part depends on the two parameters with a more complex relationship. Finally, we study the amplification effect of rotating black holes, i.e. the superradiance. Our analyses indicate the existence of stronger superradiance around loop quantum gravity black holes compared to Kerr ones.
Inferring dynamical models from time-series biological data using an interpretable machine learning method based on weighted expression trees
Authors: Zhou Yu , Zou Xiufen
Published: July 2024

The growing time-series data make it possible to glimpse the hidden dynamics in various fields. However, developing a computational toolbox with high interpretability to unveil the interaction dynamics from data remains a crucial challenge. Here, we propose a new computational approach called automated dynamical model inference based on expression trees (ADMIET), in which the machine learning algorithm, the numerical integration of ordinary differential equations and the interpretability from prior knowledge are embedded into the symbolic learning scheme to establish a general framework for revealing the hidden dynamics in time-series data. ADMIET takes full advantage of both machine learning algorithm and expression tree. Firstly, we translate the prior knowledge into constraints on the structure of expression tree, reducing the search space and enhancing the interpretability. Secondly, we utilize the proposed adaptive penalty function to ensure the convergence of gradient descent algorithm and the selection of the symbols. Compared to gene expression programming, ADMIET exhibits its remarkable capability in function fitting with higher accuracy and broader applicability. Moreover, ADMIET can better fit parameters in nonlinear forms compared to regression methods. Furthermore, we apply ADMIET to two typical biological systems and one real data with different prior knowledge to infer the dynamical equations. The results indicate that ADMIET can not only discover the interaction relationships but also provide accurate estimates of the parameters in the equations. These results demonstrate ADMIET’s superiority in revealing interpretable dynamics from time-series biological data.
Design strategies and applications of atomically dispersed aerogel catalysts prepared from metal hydrogel formation
Authors: Li Wenyu , Chen Yang , Liu Chuntai , Zhang Yi
Published: July 2024

The preparation of metal hydrogel precursors toward atomically dispersed aerogel catalysts is a captivating subject within the catalysis research domain, exhibiting promising applications in various fields. This minireview intend to summarize those novel design principles and practical applications of metal hydrogel precursors in the creation of atomically dispersed aerogel catalysts. The manuscript focuses on crucial aspects such as the meticulous selection of metal sources and initiators, the intricate process of gel preparation, a comparative analysis of different drying methods, and strategic optimization techniques to enhance the performance of metal hydrogel precursors. Moreover, this article delves into the exploration of atomically dispersed aerogel catalysts derived from metal hydrogel precursors in the realms of photocatalysis and electrocatalysis. Lastly, existing challenges are addressed, and prospective future directions for development are outlined.
A comparative analysis between deep neural network-based 1D-CNN and LSTM models to harness the self-sensing property of the shape memory alloy wire actuator for position estimation
Authors: Singh Samarth , Bhargaw Hari N , Jadhav Mahendra , John Preetesh
Published: July 2024

The article presents a performance-based comparative analysis of popular deep neural network (DNN) models such as 1-dimensional convolutional neural network (1D-CNN) and long short-term memory (LSTM) for position estimation of shape memory alloy (SMA)-based wire actuator. These DNN models utilize the self-sensing property (SSP) for position estimation of the SMA actuator. The phase-dependent electrical resistivity of SMA wire acts as SSP, where the electrical resistivity in the form of SMA wire resistance acts as inputs to the proposed models for precise estimation of the current position of the SMA actuator. For effective position control of the SMA actuator, accurate position sensor feedback is required, utilizing SSP results in the elimination of this external sensor. This will improve the overall system in terms of compactness and reduced interface complexity. Coming to DNN models, 1D-CNN has been meagerly explored in the current literature landscape for self-sensing estimation of SMA actuators. These 1D-CNN models are becoming quite popular for time series prediction for various applications and are emerging as an alternative to widely used LSTM models. In this paper, a novel implementation of a 1D-CNN model for SMA actuator position estimation has been done. A comparative analysis between 1D-CNN and LSTM has been done for prediction capability and inference speed based on performance measures such as Mean Square Error (MSE), Mean Absolute Error (MAE), symmetric Mean Absolute Percentage Error (sMAPE), data distribution, and average inference speed. The proposed comparative results show that 1D-CNN has a matching performance with the LSTM model with respect to prediction capability, however, 1D-CNN offers faster inference speed. The analysis of the proposed work can be useful for choosing a suitable DNN model for deployment on low computing platforms such as microcontrollers for SMA actuator-based real-time applications where time latency is a critical parameter.
Spin-polarization and Coulomb interaction dependent thermal rectification in a quantum dot system
Authors: Su Yufeng , Qi Fenghua , Jin Guojun
Published: July 2024

Based on the master equation approach, we investigate the thermal transport through a diode composed of a quantum dot under Coulomb interaction and tunnel-coupled to two ferromagnetic leads with antiparallel spin polarizations. We analyze the effects of spin polarizations, Coulomb interaction, mean temperature and Zeeman splitting on the thermal rectification. Firstly, we find that the thermal rectification effect is enhanced with the increase of spin polarization, because the mirror-symmetry of the system is broken by the anti-parallel spin polarization. Especially, when both leads are fully spin polarized, the asymmetry of the heat transferred by Coulomb interaction under the opposite temperature bias leads to the appearance of perfect thermal rectification and negative differential thermal conductance. Secondly, we find whether the system is in a Coulomb blockade state greatly affects the thermal rectification coefficient. As the average temperature increases or the intradot Coulomb interaction decreases, the system gradually escapes from the Coulomb blockade state, resulting in a reversal of the thermal rectification direction and ultimately leading to an increase in the rectification coefficient. Thirdly, we also find that the Zeeman splitting can be utilized to modulate the behavior of thermal rectification. Thermal rectification occurs only when Zeeman splitting and spin polarization coexist, and under different spin polarizations, the rectification coefficient exhibits different trends with the change of Zeeman splitting. These observations indicate that this structure holds potential application at a thermal rectifier as well as a thermal detector of magnetic fields.
CT-YoloTrad: fast and accurate recognition of point-distributed coded targets for UAV images incorporating CT-YOLOv7
Authors: Li Ruiguang , Wang Qiang , Wang Shun , Mao Jian , Zhang Zhenxin , Cui Ximin
Published: July 2024

Artificial point-distributed coded targets owns unique coded sequence numbers that can be recognized automatically. To address the issue of decreasing recognition accuracy and efficiency of existing recognition methods in complicated circumstances, an improved object detection model for coded target acquisition from unmanned aerial vehicle (UAV) images, CT-YOLOv7, is proposed. This improved model is based on the original YOLOv7 model, replacing several Conv with partial convolution (PConv), while introducing the bi-level routing attention mechanism, and designing the CBS-R structure and CBS-PR structure. In addition, the loss function is replaced with WIOU loss function to further improve the model’s performance. Based on the above, the new recognition method of point-distributed coded targets for UAV images is organized as follows. Firstly, CT-YOLOv7 is embedded into the front-end of the classical coded targets recognition process (that is, the coded targets are first extracted). Then, the extraction results are fed into the classical recognition algorithm for recognition. Lastly, the recognition results are inverse-calculated back to the original image. The new method aims to focus the processing on the region of interest to achieve fast and accurate coded targets recognition for UAV images. The experimental results show that CT-YOLOv7’s detection accuracy is 90.83%, which improves the accuracy by 8.46% and reduces the computation by 11.54% compared to the original YOLOv7. By incorporating the CT-YOLOv7 model, the time consumption for coded target recognition of a single UAV image is 150–350ms, which improves the average efficiency by 3–5 times compared with the classical method. Furthermore, the proposed method can correctly recognize regions with shadows and noise, and the recognition accuracy is improved by 15%–40%. With the method proposed in this paper, the coded targets are expected to be applied into UAV photogrammetry or remote sensing to realize accurate and quasi-real-time recognition.
Strain-tuned electronic and valley-related properties in Janus monolayers of SWSiX2 (X = N, P, As)
Authors: Qi 戚 Yunxi 云西 , Zhao 赵 Jun 俊 , Zeng 曾 Hui 晖
Published: July 2024

Exploring novel two-dimensional (2D) valleytronic materials has an essential impact on the design of spintronic and valleytronic devices. Our first principles calculation results reveal that the Janus SWSiX
2 (X = N, P, As) monolayer has excellent dynamical and thermal stability. Owing to strong spin–orbit coupling (SOC), the SWSiX
2 monolayer exhibits a valence band spin splitting of up to 0.49 eV, making it promising 2D semiconductor for valleytronic applications. The opposite Berry curvatures and optical selection rules lead to the coexistence of valley and spin Hall effects in the SWSiX
2 monolayer. Moreover, the optical transition energies can be remarkably modulated by the in-plane strains. Large tensile (compressive) in-plane strains can achieve spin flipping in the SWSiN2 monolayer, and induce both SWSiP2 and SWSiAs2 monolayers transit from semiconductor to metal. Our research provides new 2D semiconductor candidates for designing high-performance valleytronic devices.
Detection of Increasing γ-Ray Emissions from 4FGL J1718.5+4237 with Fermi-LAT
Authors: Zheng Jiao , Zhang Pengfei , Zhang Li
Published: July 2024

We report a gradual brightening γ-ray source, 4FGL J1718.5+4237, in 0.1–500.0 GeV, which may be associated with a blazar NVSS J171822+423948 with a redshift of ∼2.7. We analyzed 15.25 yr of γ-ray data recorded by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detected significant γ-ray emissions in the direction of the blazar with a test statistic (TS) of ∼135. Based on timing analysis using a 1 yr time bin, we have observed a gradual brightening in γ-ray emissions from the target. In our analysis, we categorize them into two states: Quiet (TS ∼ 0) and Loud (TS ∼ 226) states, with the distinction occurring in 2016 August (MJD 57602.69). From the Quiet state to the brightest period (the last data point), the γ-ray flux in 0.1–500.0 GeV increased by more than 12-fold from <0.2 × 10−8 photons cm−1 s−1 to 2.6 × 10−8 photons cm−1 s−1. Additionally, we studied the spectral properties in detail for the Loud state and the overall data. While no significant variation was detected, both exhibited a spectral index Γ of ∼2.6. The origin of the brightening γ-ray emissions from the target is not yet clear. Future long-term multi-wavelength observations and studies will provide insight into the astrophysical mechanisms of the target.
Measurement of bidirectional transmittance distribution function in the visible and near-infrared spectral range
Authors: Aschan Robin , Manoocheri Farshid , Lanevski Dmitri , Ikonen Erkki
Published: July 2024

This work characterizes a facility for bidirectional transmittance distribution function (BTDF) measurements in the visible and near-infrared (NIR) wavelength range. The facility includes an absolute reference gonioreflectometer, with an extended capability for BTDF measurements, and a commercial instrument, Cary 7000, using a goniometer extension, Universal Measurement Accessory. The facility characterization includes measurements of two quasi-Lambertian diffusers for their BTDF. The diffuser samples include a piece of porous polytetrafluoroethylene (PTFE) and a piece of fused synthetic silica, HOD-500. The samples are measured for their spectral BTDF in the wavelength range from 450 nm to 1650 nm in 50 nm steps, and in the viewing zenith angle range from −35° to 35° in 5° steps. Measurements are performed in-plane, using an incident zenith angle of 0°, while rotating the samples around their surface normal from 0° to 180° in 90° steps. Rotation of the sample serves the dual purpose of checking the sample rotational symmetry in azimuth angles and for averaging the measurement results. The characterization results show that both samples exhibit Lambertian characteristics across the visible and NIR wavelength range. Furthermore, both samples show a smooth increase in their spectral BTDF as a function of wavelength. Notably, the PTFE sample demonstrates a steeper slope in its spectral BTDF and a higher signal above 650 nm. The facility capability for measurements of spectral BTDF is validated by a rigorous uncertainty analysis and by comparing the difference in measurement results between the absolute gonioreflectometer and the commercial instrument. Characterization results indicate that the absolute reference gonioreflectometer has a standard uncertainty ranging from 0.29% to 0.42%, dependent on the BTDF measurement wavelength. Experimental results show that the devices of the facility deviate in their BTDF within their combined expanded uncertainty, affirming the capability and reliability of the facility for BTDF measurements.
Biofabricated nanomaterials in sustainable agriculture: insights, challenges and prospects
Authors: Mohanty Pratikhya , Singh Puneet Kumar , Lenka Basundhara , Adhya Tapan K , Verma Suresh K , Ayreen Zobia , Patro Shilpita , Sarkar Biplab , Mohapatra Ranjan K , Mishra Snehasish
Published: July 2024

One ever-evolving and ever-demanding critical human endeavour is the provision of food security for the growing world population. This can be done by adopting sustainable agriculture through horizontal (expanding the arable land area) and vertical (intensifying agriculture through sound technological approaches) interventions. Customized formulated nanomaterials have numerous advantages. With their specialized physico-chemical properties, some nanoparticulated materials improve the plant’s natural development and stress tolerance and some others are good nanocarriers. Nanocarriers in agriculture often coat chemicals to form composites having utilities with crop productivity enhancement abilities, environmental management (such as ecotoxicity reduction ability) and biomedicines (such as the ability to control and target the release of useful nanoscale drugs). Ag, Fe, Zn, TiO2, ZnO, SiO2 and MgO nanoparticles (NPs), often employed in advanced agriculture, are covered here. Some NPs used for various extended purposes in modern farming practices, including disease diagnostics and seed treatment are also covered. Thus, nanotechnology has revolutionized agrotechnology, which holds promise to transform agricultural (ecosystems as a whole to ensure food security in the future. Considering the available literature, this article further probes the emergent regulatory issues governing the synthesis and use of nanomaterials in the agriculture sector. If applied responsibly, nanomaterials could help improve soil health. This article provides an overview of the nanomaterials used in the distribution of biomolecules, to aid in devising a safer and eco-friendly sustainable agriculture strategy. Through this, agri-systems that depend on advanced farming practices might function more effectively and enhance agri-productivity to meet the food demand of the rising world population.
Towards dynamical low-rank approximation for neutrino kinetic equations. Part I: Analysis of an idealized relaxation model
Authors: Yin Peimeng , Endeve Eirik , Hauck Cory , Schnake Stefan
Published: July 2024

Dynamical low-rank approximation (DLRA) is an emerging tool for reducing computational costs and provides memory savings when solving high-dimensional problems. In this work, we propose and analyze a semi-implicit dynamical low-rank discontinuous Galerkin (DLR-DG) method for the space homogeneous kinetic equation with a relaxation operator, modeling the emission and absorption of particles by a background medium. Both DLRA and the discontinuous Galerkin (DG) scheme can be formulated as Galerkin equations. To ensure their consistency, a weighted DLRA is introduced so that the resulting DLR-DG solution is a solution to the fully discrete DG scheme in a subspace of the standard DG solution space. Similar to the standard DG method, we show that the proposed DLR-DG method is well-posed. We also identify conditions such that the DLR-DG solution converges to the equilibrium. Numerical results are presented to demonstrate the theoretical findings.
Sketched and truncated polynomial Krylov subspace methods: Matrix Sylvester equations
Authors: Palitta Davide , Schweitzer Marcel , Simoncini Valeria
Published: July 2024

Thanks to its great potential in reducing both computational cost and memory requirements, combining sketching and Krylov subspace techniques has attracted a lot of attention in the recent literature on projection methods for linear systems, matrix function approximations, and eigenvalue problems. Applying this appealing strategy in the context of linear matrix equations turns out to be far more involved than a straightforward generalization. These difficulties include analyzing well-posedness of the projected problem and deriving possible error estimates depending on the sketching properties. Further computational complications include the lack of a natural residual norm estimate and of an explicit basis for the generated subspace.

In this paper we propose a new sketched-and-truncated polynomial Krylov subspace method for Sylvester equations that aims to address all these issues. The potential of our novel approach, in terms of both computational time and storage demand, is illustrated with numerical experiments. Comparisons with a state-of-the-art projection scheme based on rational Krylov subspaces are also included.
Logarithmic systolic growth for hyperbolic surfaces in every genus
Authors: Katz Mikhail , Sabourau Stéphane
Published: July 2024

More than thirty years ago, Brooks [J. Reine Angew. Math. 390 (1988), pp. 117–129] and Buser–Sarnak [Invent. Math. 117 (1994), pp. 27–56] constructed sequences of closed hyperbolic surfaces with logarithmic systolic growth in the genus. Recently, Liu and Petri [Random surfaces with large systoles, https://arxiv.org/abs/2312.11428, 2023] showed that such logarithmic systolic lower bound holds for every genus (not merely for genera in some infinite sequence) using random surfaces. In this article, we show a similar result through a more direct approach relying on the original Brooks/Buser–Sarnak surfaces.
Can a chemotaxis-consumption system recover from a measure-type aggregation state in arbitrary dimension?
Authors: Heihoff Frederic
Published: July 2024

We consider the chemotaxis-consumption system
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout 1st Row with Label left-parenthesis star right-parenthesis EndLabel StartLayout Enlarged left-brace 1st Row 1st Column u Subscript t 2nd Column a m p semicolon equals normal upper Delta u minus chi nabla dot left-parenthesis u nabla v right-parenthesis 2nd Row 1st Column v Subscript t 2nd Column a m p semicolon equals normal upper Delta v minus u v EndLayout EndLayout">

(

⋆

)

{

u
t

a
m
p
;
=
Δ
u
−
χ
∇
⋅
(
u
∇
v
)

v
t

a
m
p
;
=
Δ
v
−
u
v

\begin {cases} u_t &= \Delta u - \chi \nabla \cdot (u\nabla v) \\ v_t &= \Delta v - uv \end {cases} \tag {$\star $}

\]
in a smooth bounded domain

Ω
⊆

R

n

\Omega \subseteq \mathbb {R}^n

,

n
≥
2

n \geq 2

, with parameter

χ
>
0

\chi > 0

and Neumann boundary conditions. It is well known that, for sufficiently smooth nonnegative initial data and under a smallness condition for the initial state of

v
v

, solutions of the above system never blow up and are even globally bounded. Going in a sense a step further in this paper, we ask the question whether the system can even recover from an initial state that already resembles measure-type blowup. To answer this, we show that, given an arbitrarily large positive Radon measure

u
0

u_0

with

u
0

(

Ω
¯

)
>
0

u_0(\overline {\Omega }) > 0

as the initial data for the first equation and a nonnegative

L
∞

(
Ω
)

L^\infty (\Omega )

function

v
0

v_0

with
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="0 greater-than double-vertical-bar v 0 double-vertical-bar Subscript upper L Sub Superscript normal infinity Subscript left-parenthesis normal upper Omega right-parenthesis Baseline greater-than StartFraction pi Over chi EndFraction StartRoot StartFraction 2 Over n EndFraction EndRoot">

0
>
‖

v
0

‖

L

∞

(
Ω
)

>

π
χ

2
n

0 > \|v_0\|_{L^{\infty }(\Omega )} > \frac {\pi }{\chi } \sqrt {\frac {2}{n}}

\]
as initial data for the second equation, it is still possible to construct a global classical solution to the above system. Notably, the above condition on the initial data appears to be weaker than those required in all previous works on (

⋆
\star

) even in frameworks of smooth initial data.
Equivariant 𝒟-modules on 2×2×𝓃 hypermatrices
Authors: Lőrincz András , Perlman Michael
Published: July 2024

We study

D

\mathcal {D}

-modules and related invariants on the space of

2
×
2
×
n

2\times 2\times n

hypermatrices for

n
≥
3

n\geq 3

, which has finitely many orbits under the action of
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper G equals upper G upper L 2 left-parenthesis double-struck upper C right-parenthesis times upper G upper L 2 left-parenthesis double-struck upper C right-parenthesis times upper G upper L Subscript n Baseline left-parenthesis double-struck upper C right-parenthesis">

G
=
G

L
2

(

C

)
×
G

L
2

(

C

)
×
G

L
n

(

C

)

G=GL_2(\mathbb {C}) \times GL_2(\mathbb {C}) \times GL_n(\mathbb {C})

. We describe the category of coherent

G
G

-equivariant

D

\mathcal {D}

-modules as the category of representations of a quiver with relations. We classify the simple equivariant

D

\mathcal {D}

-modules, determine their characteristic cycles and find special representations that appear in their

G
G

-structures. We determine the explicit

D

\mathcal {D}

-module structure of the local cohomology groups with supports given by orbit closures. As a consequence, we calculate the Lyubeznik numbers and intersection cohomology groups of the orbit closures. All but one of the orbit closures have rational singularities: we use local cohomology to prove that the one exception is neither normal nor Cohen–Macaulay. While our results display special behavior in the cases

n
=
3

n=3

and

n
=
4

n=4

, they are completely uniform for

n
≥
5

n\geq 5

.
Testing conditions for multilinear Radon-Brascamp-Lieb inequalities
Authors: Gressman Philip
Published: July 2024

This paper establishes a necessary and sufficient condition for

L
p

L^p

-boundedness of a class of multilinear functionals which includes both the Brascamp-Lieb inequalities and generalized Radon transforms associated to algebraic incidence relations. The testing condition involves bounding the average of an inverse power of certain Jacobian-type quantities along fibers of associated projections and covers many widely-studied special cases, including convolution with measures on nondegenerate hypersurfaces or on nondegenerate curves. The heart of the proof is based on Guth’s visibility lemma [Acta Math. 205 (2010), pp. 263–286] in one direction and on a careful analysis of Knapp-type examples in the other. Various applications are discussed which demonstrate new and subtle interplay between curvature and transversality and establish nontrivial mixed-norm

L
p

L^p

-improving inequalities in the model case of convolution with affine hypersurface measure on the paraboloid.
On the geometry at infinity of manifolds with linear volume growth and nonnegative Ricci curvature
Authors: Zhu Xingyu
Published: July 2024

We prove that an open noncollapsed manifold with nonnegative Ricci curvature and linear volume growth always splits off a line at infinity. This completes the final step to prove the existence of isoperimetric sets for given large volumes in the above setting. We also find that under our assumptions, the diameters of the level sets of any Busemann function are uniformly bounded as opposed to a classical result stating that they can have sublinear growth when the end is collapsing. Moreover, some equivalent characterizations of linear volume growth are given. Finally, we construct an example to show that for manifolds in our setting, although their limit spaces at infinity are always cylinders, the cross sections can be nonhomeomorphic.
Macro-Level Repression and Micro-Level Paths to Political Resistance
Authors: Adra Aya , Li Mengyao
Published: July 2024

This chapter proposes a framework to understand the multifaceted impact of macro-level repression on individuals’ participation in political resistance. We focus on repression as a structural characteristic of a given country, and we propose that it may shape political resistance in two major ways. First, repression can influence resistance through affecting particular micro-level, psychological mechanisms that typically predict resistance (e.g., political dissatisfaction, efficacy). Second, repression can condition the links between resistance and many of its typical predictors. In other words, repression can make certain micro-level factors more, less, or differently relevant for resistance. To illustrate our propositions, we focus on two micro-level predictors of resistance—perceived injustice and political efficacy—and we draw on a wide range of political contexts, from backsliding democracies to stable authoritarian regimes.