State Distribution Research Articles

Inhomogeneous coupling induced quantized distribution of photonic states in Kagome lattices across different Landau levels

Recent progress has demonstrated that synthetic gauge fields can mimic Landau quantization in materials including graphene and lattices for sound and light. However, despite using graphene-like structures with strain-induced textures in prior photonics, it is hard to capture the experimental attainment of distinct photon bound states for various Landau levels. In this work, we introduce an experimental framework for achieving photonic Landau quantization. We present the quantized distribution of photonic states across different Landau levels in a two-dimensional Kagome metal lattice. By introducing inhomogeneous coupling, we implement two kinds of pseudomagnetic field, which quantize spectrums and quantizes distribution of photonic states, respectively. We experimentally observe that the electric field distribution is localized according to the positional attributes of different Landau levels. Our proposed system is more straightforward to implement, and it opens an avenue to explore photonic states at non-zero Landau levels, which are predicted to demonstrate some interesting physical phenomena.

Discovery of a potential open ocean nursery for the endangered shortfin mako shark in a global fishing hotspot

Populations of large pelagic sharks are declining worldwide due to overfishing. Determining the overlap between shark populations and fishing activities is important to inform conservation measures. However, for many threatened sharks the whereabouts of particularly vulnerable life-history stages – such as pregnant females and juveniles – are poorly known. Here, we investigated the spatial distribution of size classes, energy transfer and reproductive states of pregnant females of the endangered shortfin mako, Isurus oxyrinchus, using spatially resolved catch data from a Spanish surface longline vessel (1996 − 2009) in the South-east Pacific Ocean. Our results suggest a general eastward gradient of occurrence of pregnant females of thousands of kilometers from western oceanic feeding grounds towards the eastern Pacific, where we observed an aggregation area of small juveniles. Moreover, the potential nursery likely overlapped a longline fishing hotspot, increasing the vulnerability of juveniles from fisheries. Our results suggest that limiting fishing pressure in this area could reduce mortality of early life stages and contribute to the conservation of this endangered shark species.

Study of Fluid Flow Characteristics and Mechanical Properties of Aviation Fuel-Welded Pipelines via the Fluid–Solid Coupling Method

The welded pipeline structure of aircraft fuel is a complex and diverse entity, significantly influenced by fluid–solid coupling. The refined aviation fuel-welded pipeline model plays a pivotal role in the investigation of its fluid–solid coupling mechanical properties. However, the mechanical analyses of pipelines with welded structures frequently simplify or ignore the influence of the weld zone (WZ). Consequently, these analyses fail to reveal the complex interactions between different weld zones in detail. In this study, a comprehensive and precise fuel-welded pipeline refinement model is developed through the acquisition of microstructural dimensions and mechanical parameters of the weld zone via metallographic inspection and microtensile testing. Additionally, the influence of clamps and brackets under airborne conditions is fully considered. Furthermore, the numerical simulation results are compared and verified using modal and random vibration tests. This paper addresses the impact of diverse fluid characteristics on the velocity field, pressure field, and stress in disparate areas, and it also conducts an investigation into the random vibration characteristics of the pipeline. The results demonstrate that the fluid pressure and velocity exert a considerable influence on the fluid flow state and structural stress distribution within the pipeline. An increase in flow velocity and alteration to the pipeline geometry will result in a change to the local velocity distribution, which in turn affects the distribution of the fluid pressure field. The highest stresses are observed in the weld zone, particularly at the junction between the weld zone and the heat-affected zone (HAZ). In contrast, the stresses in the bend region exhibit a corrugated distribution in both the axial and circumferential directions. An increase in fluid pressure has a significant impact on the natural frequency of the pipeline. This study enhances our comprehension of the mechanical properties of aircraft fuel lines with fluid–solid coupling and provides a foundation and guidance for the optimal design of fuel-welded lines.

Investigation of the Gas-Phase N2+ + CH3CN Reaction at Low Temperatures.

Rate coefficients for ion-polar-molecule reactions between acetonitrile molecules (CH3CN) and nitrogen molecular ions (N2+), which are of importance to the upper atmospheric chemistry of Saturn's moon Titan, were measured for the first time at low translational temperatures. In the experiments, the reaction between sympathetically cooled N2+ ions embedded in laser-cooled Ca+ Coulomb crystals and velocity-selected acetonitrile molecules generated using a wavy Stark velocity filter was studied to determine the reaction rate coefficients. Capture rate coefficients calculated by the Su-Chesnavich approach and by the perturbed rotational state theory considering the rotational state distribution of CH3CN were compared to the experimental rate coefficients. The results indicate that the present reaction is barrierless and that the rate coefficients are consistent with the capture rate coefficients. The potential energy surface of the reaction product CH3CN+ was calculated by the CCSD(T)/aug-cc-pVQZ level theory to explore possible isomerization and dissociation pathways. Several locally stable structures leading to H2CCN+, HCCNH+, HCNCH+, and H2CNC+ were found, while no intrinsic reaction coordinate leading to the CHCN+ formation pathway accompanied by H2 abstraction has been identified. The H2CCN+ + H dissociation channel is a major pathway of the reaction product, though theoretical calculations suggest the CHCN+ + H2 dissociation channel is energetically feasible. The present experimental and theoretical studies will contribute to the accurate modeling of nitrile chemistry in interstellar matter and in the upper atmosphere of Titan.

The Gaussian-Linear Hidden Markov model: a Python package

Abstract We propose the Gaussian-Linear Hidden Markov model (GLHMM), a generalisation of different types of HMMs commonly used in neuroscience. In short, the GLHMM is a general framework where linear regression is used to flexibly parameterise the Gaussian state distribution, thereby accommodating a wide range of uses —including unsupervised, encoding and decoding models. GLHMM is available as a Python toolbox with an emphasis on statistical testing and out-of-sample prediction —i.e. aimed at finding and characterising brain-behaviour associations. The toolbox uses a stochastic variational inference approach, enabling it to handle large data sets at reasonable computational time. The GLHMM can work with various types of data, including animal recordings or non-brain data, and is suitable for a broad range of experimental paradigms. For demonstration, we show examples with fMRI, local field potential, electrocorticography, magnetoencephalography and pupillometry.

PH- and Saccharide-Responsive Cyclometalated Iridium(III) Complexes with Boronic Acid Moieties Displaying a Wide Range of Phosphorescence Colors.

Single compounds displaying a wide range of luminescent colors are attractive optical materials for sensor applications. In this study, we present the beneficial combination of a cyclometalated iridium(III) complex scaffold and boronic acid units for designing stimulus-responsive luminescent materials with various emission colors. Five iridium(III) complexes bearing a diboronic acid ligand (bpyB2) were synthesized: Ir(C^N)bpyB2 (C^N=2-phenylpyridine (1), 2-(2,4-difluorophenyl)pyridine (2), 2-(4-methoxyphenyl)pyridine (3), benzo[h]quinoline (4), 1-phenylisoquinoline (5)). The luminescence color of Complexes 1-4 changed in response to the solution pH or saccharide concentration. Complex 1 exhibited a color change from orange to green-blue due to structural alteration of the boronic acid moiety from trigonal to tetrahedral. Furthermore, the luminescence color of Complex 1 changed reversibly due to repetitive changes in the solution pH between 5 and 10, enabling tuning of the luminescence color and pH tracking. Furthermore, the color range was tuned by selecting an appropriate C^N ligand. Time-dependent density functional theory investigations revealed that the dramatic and reversible color changes could be ascribed to a switch in the electronic distribution in the lowest excited state from bpyB2 to C^N. The stimulus-responsive iridium(III) complexes provide a prospective scaffold for future applications in color-tunable optical devices and chemosensing systems.

Snapshot Imaging of Stokes Vector Polarization Speckle in Turbid Optical Phantoms and In Vivo Tissues

Significance: We present a system to measure and analyze the complete polarization state distribution of speckle patterns generated from in vivo tissue. Accurate measurement of polarization speckle requires both precise spatial registration and rapid polarization state acquisition. A unique measurement system must be designed to achieve accurate images of polarization speckle patterns for detailed investigation of the scattering properties of biological tissues in vivo. Aim and approach: This system features a polarization state analyzer with no moving parts. Two pixel-polarizer cameras allow for the instantaneous acquisition of the spatial Stokes vector distribution of polarization speckle patterns. System design and calibration methods are presented, and representative images from measurements on liquid phantoms (microsphere suspensions) and in vivo healthy and tumor murine models are demonstrated and discussed. Results and Conclusions: Quantitative measurements of polarization speckle from microsphere suspensions with controlled scattering coefficients demonstrate differences in speckle contrast, speckle size, and the degree of polarization. Measurements on in vivo murine skin and xenograft tumor tissue demonstrate the ability of the system to acquire snapshot polarization speckle images in living systems. The developed system can thus rapidly and accurately acquire polarization speckle images from different media in dynamic conditions such as in vivo tissue. This capability opens the potential for future detailed investigation of polarization speckle for in vivo biomedical applications.

Efficient State Synchronization in Distributed Electrical Grid Systems Using Conflict-Free Replicated Data Types

Modern electrical grids are evolving towards distributed architectures, necessitating efficient and reliable state synchronization mechanisms to maintain structural and functional consistency. This paper investigates the application of conflict-free replicated data types (CRDTs) for representing and synchronizing the states of distributed electrical grid systems (DEGSs). We present a general structure for DEGSs based on CRDTs, focusing on the Convergent Replicated Data Type (CvRDT) model with delta state propagation to optimize the communication overhead. The Observed Remove Set (ORSet) and Last-Writer-Wins Register (LWW-Register) are utilized to handle concurrent updates and ensure that only the most recent state changes are retained. An actor-based framework, “Vigilant Hawk”, leveraging the Akka toolkit, was developed to simulate the asynchronous and concurrent nature of DEGSs. Each electrical grid node is modelled as an independent actor with isolated state management, facilitating scalability and fault tolerance. Through a series of experiments involving 100 nodes under varying latency degradation coefficients (LDK), we examined the impact of network conditions on the state synchronization efficiency. The simulation results demonstrate that CRDTs effectively maintain consistency and deterministic behavior in DEGSs, even with increased network latency and node disturbances. An effective LDK range was identified (LDK effective = 2 or 4), where the network remains stable without significant delays in state propagation. The linear relationship between the full state distribution time (FSDT) and LDK indicates that the system can scale horizontally without introducing complex communication overhead. The findings affirm that using CRDTs for state synchronization enhances the resilience and operational efficiency of distributed electrical grids. The deterministic and conflict-free properties of CRDTs eliminate the need for complex concurrency control mechanisms, making them suitable for real-time monitoring and control applications. Future work will focus on addressing identified limitations, such as optimizing message routing based on the network topology and incorporating security measures to protect state information in critical infrastructure systems.

Optimizing carrier transport properties in the intrinsic layer of a-Si single and double junction solar cells through numerical design

This research aims to improve the performance of a-Si: H solar cells, particularly in terms of carrier transport properties, through a numerical design approach utilizing AFORS-HET simulation software. By performing a series of rigorous computer simulations, we explore the potential regulation of the intrinsic layer thickness, carrier mobility, loading factor, and density of states (DoS) distribution in the solar cell's intrinsic layer. Recombination losses are reduced, and light absorption efficiency is significantly increased when the intrinsic layer thickness is adjusted, as shown by simulation findings. Moreover, reduction of transit times and enhancement of the total efficiency of the solar cells depend on increased carrier mobility. Parameters can be adjusted to attain optimal performance under various operating situations by adjusting the DoS and load factors. Furthermore, the simulations provide insightful information about the interactions between the junctions in solar cells with double junctions. Our results of this research provide an important contribution to efforts to develop more efficient and sustainable a-Si: H solar cells and emphasize the importance of numerical design approaches in photovoltaic technology.

Organosilicon Polymeric Acetylene Derivatives: X-Ray Spectral Study and Quantum-Chemical Calculations

The atomic and electronic structure of two organosilicon polymers [–Ph2Si–(C≡C)2–]n (P1) and [–Ph2Si–(C≡C–C≡C)2–]m (P2) (where Ph — is phenyl group) of acetylene and diacetylene types by methods of density functional theory and X-ray emission spectroscopy. The interpretation of X-ray emission SiKβ1-spectra of these polymers was carried out based on an analysis of the distribution of partial electronic states obtained from quantum chemical calculations. Quantitative characteristics of the parameters of the chemical interaction of atoms, such as populations, natural charges, and electronic configurations in the studied polymers, were obtained based on the analysis of hybrid natural bond orbitals. The obtained values of the natural bond orbitals polarization coefficients indicate that the electron density is localized predominantly on carbon atoms. The electronic configurations for carbon atoms in different fragments differ significantly. For C atoms of ethynyl (diethynyl) fragments, they are close to linear σ-bond with sp1.03 (P1) and sp0.95 (P2) configurations, while for C atoms of phenyl fragments it is sp2.42, intermediate between sp2 and sp3 configurations. The natural charges on Si in both polymers are almost the same: +1.58e, +1.59e, while the natural charges on the carbon atoms of the diethynyl group decrease in comparison with the charge on the carbon atom of the ethynyl group from –0.42e to –0.36e.

Breaking the Stability-Activity Trade-off of Oxygen Electrocatalyst by Gallium Bilateral-Regulation for High-Performance Zinc-Air Batteries.

The rational design of metal oxide catalysts with enhanced oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is crucial for the practical application of aqueous rechargeable zinc-air batteries (a-r-ZABs). Precisely regulating the electronic environment of metal-oxygen (M-O) active species is critical yet challenging for improving their activity and stability toward OER and ORR. Herein, we propose an atomic-level bilateral regulation strategy by introducing atomically dispersed Ga for continuously tuning the electronic environment of Ru-O and Mn-O in the Ga/MnRuO2 catalyst. The Ga/MnRuO2 catalyst breaks the stability-activity restriction, showing remarkable bifunctional performance with a low potential gap (ΔE) of 0.605 V and super durability with negligible performance degradation (300,000 ORR cycles or 30,000 OER cycles). The theoretical calculations revealed that the strong coupling electron interactions between Ga and Ru-O/Mn-O tuned the valence state distribution of the metal center, effectively modulating the adsorption behavior of *O/*OH, thus optimizing the reaction pathways and reducing the reaction barriers. The a-r-ZABs based on Ga/MnRuO2 catalysts exhibited excellent performance with a wide working temperature range of -20~60 °C and a long lifetime of 2308 hours (i.e., 13,848 cycles) under a current density of 5 mA cm-2 at -20 °C.

Effects of surface roughness of a waveplate on the development of diffractive polarization speckle

A rough-surfaced retardation plate is a particular polarization-dependent phase modulation device, whose performance is affected by its surface roughness structures. In previous research [J. Opt. Soc. Am. A 32, 2346 (2015)JOAOD60740-323210.1364/JOSAA.32.002346], its decorrelation and depolarization effects have been investigated under an assumption of a rough surface model with large covariance of thickness fluctuations, giving a fully developed speckle field by transmission/reflection. This paper continues the analysis of the rough-surfaced retardation plate and then focuses on a smooth roughness model. When the thickness fluctuation is relatively small, partially developed speckle will be generated. The statistics of partially developed polarization speckle with non-uniform spatial distribution of polarization state will be discussed in the form of the matrix elements of the coherence–polarization matrix. The propagation of the partially developed speckle field will be traced within the framework of the complex-valued ABCD matrix theory under paraxial approximation to reveal the evolution of its degree change of coherence and polarization on propagation. This means that Gaussian apertures are included in the optical train of elements. The differences in statistical features from fully developed polarization speckle are emphasized.

Research on Flower Pattern and Roll Positioning Optimization for Roll Forming Process of TA4 Coiled Tubing.

Titanium alloy coiled tubing (CT) has great superiority while operating in deep wells with severe conditions, but it faces serious challenges during roll forming like high springback, edge cracking and surface wearing. In order to utilize the high precision and high efficiency production of titanium alloy CT, it is urgently necessary to develop a detailed process design. Based on the W-forming strategy and the cubic curve of the strip edge projection, the flower pattern and roll design for the 21-pass roll forming process were completed. Different tube dimensions and roll positionings were researched regarding the aspects of contact state, stress-strain distribution and geometry ovality using numerical simulation. The thickness/diameter ratio of the tube that can be formed should be within an effective range: exceeding the range leads to edge cracking, and an insufficient ratio leads to high springback. Roll positioning significantly affects the contact state and stress distribution, but leads to no major differences in the tube geometry. Finally, the trial production of the TA4 titanium CT with a size of Φ50.8 × 4 mm was completed successfully and was consistent with the simulation results.

МАМЛЕКЕТ ТАРАБЫНАН КАЛКТЫН ПЕНСИЯЛЫК КАМСЫЗДАНДЫРЫЛУУСУНУН ЖӨНДӨЛҮШҮНҮН ӨСҮП-ӨНҮГҮШҮНҮН КЕЛЕЧЕГИ

This article explores the issues with Kyrgyzstan's pension system post-USSR and its potential reforms. This highlights the importance of providing a decent living standard for pensioners and enhancing public financial literacy regarding pensions. The global pension system trends are reviewed, including maintaining state distribution systems with voluntary accumulative elements, raising the retirement age, and shifting to private pension insurance. Key deficiencies in Kyrgyzstan's pension system were identified: low financial literacy, poor interaction between the State Accumulative Pension Fund and the public, and insufficient pension savings for adequate payments. The suggested measures aim to improve the funded pension system, manage pension savings, and protect citizens' pension assets.

Quantum Network Infrastructure

AbstractGlobal quantum state distribution has applications in many areas, one of which is global key distribution for secure communications in an era of the threat of quantum computing. Long‐distance quantum key distribution requires a global network of optical relay stations, ground stations, and quantum memories. In this study, why quantum memories should be operated in space as untrusted nodes is presented. In addition to quantum key distribution, quantum memories in space are an enabling technology for distributed quantum sensor systems. The requirements for distributed sensors are outlined and the current technology readiness level of relevant systems is referenced. Finally, the possibility of an emerging quantum internet, enabling the coherent combination of quantum computers around the world, is addressed.

Specific Influences of Trap States with Distinct Spatial and Energetic Distributions on Ion Migration Dynamics in Metal Halide Perovskites.

Trap state engineering has been widely employed to manipulate the dynamics of ion migration in metal halide perovskites (MHPs), a crucial factor associated with the performance and stability of MHP-based devices. However, the specific roles of different trap states remain poorly understood due to their complicated spatial and energetics distributions. Herein, we propose a methodology for independently regulating the distributions of bulk shallow and surface deep trap states in MHPs. By combining in situ photoluminescence spectroscopy with wide-field imaging microscopy, we elucidate the effect of surface trap states on promoting long-range interparticle ion migration. Interestingly, we ascertain with time-resolved photoelectric techniques that the majority of mobile ionic defects involved in ion migration are predominantly contributed by bulk trap states. Our findings suggest that targeted manipulation of bulk shallow and surface deep trap states can be effective in reducing the number of mobile ions and decelerating the rate of ion migration, respectively.

A study of rare earth intermetallide La<sub>0.73</sub>Dy<sub>0.27</sub>Mn<sub>2</sub>Si<sub>2</sub> by Raman spectroscopy, magnetic force microscopy and resonance photoemission spectroscopy

The features of the magnetic microstructure of La0.73Dy0.27Mn2Si2 at 293 K have been visualized by atomic force and magnetic force microscopy. Magnetic force images reveal the presence of low-contrast magnetic domains. The change of Raman spectral characteristics of light scattering in the process of cooling La0.73Dy0.27Mn2Si2 to a temperature of 263 K is experimentally detected. The electronic structure of La0.73Dy0.27Mn2Si2 is investigated by resonance photoemission spectroscopy with the use of the synchrotron radiation. Resonances at 3d and 4d levels of electronic structure show different properties of valence electrons. Using the 3d–4f (M4.5 absorption edge) resonance, the distribution of 4f states of dysprosium in the valence band is determined. Photoemission upon the giant Dy 4d–4f (N4.5 absorption edge) resonance is determined by the contribution of all states in the valence band due to the sudden involvement of the Coulomb interaction. The energies of La and 4f levels of La, the 4f level of Dy, and the 3d level of Mn in the valence band have been determined.

Compton scattering from proton pairs – illustrating weak and strong measurements

Abstract Neutrons interacting with protons in Compton scattering is here chosen as an example of a non-trivial quantum measurement. It illustrates a situation where a probe particle makes an observation (a weak measurement) of the studied protons, preparing for a final state in which one of them takes up the recoil in the collision. The proton is ejected during a strong (projective) measurement that selects one particular momentum value out of the proton’s initial distribution of momentum states. This course of events in the measurement process is evidenced by the observation that destructive interference appears during the weak interaction stage which leads to a strongly reduced neutron cross section for the proton system.

A Relationship Between Semiconducting Thin Film's Electronic Structure Heterogeneity and Defect Tolerance.

Analyzing the defect states presence in semiconductors and understanding their impact on charge transport is essential to the solar cells' functionality. In recent years, there has been a focus on the concept of "defect tolerance" observed in perovskite solar cells. The energy-resolved electrochemical impedance spectroscopy (ER-EIS) is crucial for measuring the density distribution of defect states in the energy scale from valence to conductance band (or from HOMO to LUMO) and their spatial localization on a thin film. In this study, the aim is to better understand the concept of "defect-tolerant materials" by comparing the surface and bulk densities of defect states obtained from ER-EIS with the loss tangent at the frequency where the redox reactions determine the real part of the impedance. This comparison shows that the heterogeneity of the electronic structure across the thin film manifested as a higher surface density of states significantly impacts the failure of "defect tolerance" properties. The proposed procedure, being fast and efficient, has potential in the search for new materials and effective technological procedures for the conversion of solar energy into electricity.

Exploring the Molecular Structure and Treatment Dynamics of Cellulose Fibres with Photoacoustic and Reversed Double-Beam Spectroscopy.

In this study, we explored the structural and chemical modifications of cellulose fibres subjected to chemical and mechanical treatments through an innovative analytical approach. We employed photoacoustic spectroscopy (PAS) and reversed double-beam photoacoustic spectroscopy (RDB-PAS) to examine the morphological changes and the chemical integrity of the treated fibres. The methodology provided enhanced sensitivity and specificity in detecting subtle alterations in the treated cellulose structure. Additionally, we applied Coifman wavelet transformation to the PAS signals, which facilitated a refined analysis of the spectral features indicative of chemical and mechanical modifications at a molecular level. This advanced signal processing technique allowed for a detailed decomposition of the PAS signals, revealing hidden characteristics that are typically overshadowed in raw data analyses. Further, we utilised the concept of energy trap distribution to interpret the wavelet-transformed data, providing insights into the distribution and density of energy states within the fibres. Our results indicated significant differences in the energy trap spectra between untreated and treated fibres, reflecting the impact of chemical and mechanical treatments on the fibre's physical properties. The combination of these sophisticated analytical techniques elucidated the complex interplay between mechanical and chemical treatments and their effects on the structural integrity and chemical composition of cellulose fibres.