bluuebunny/crossref_metadata_2025 huggingface dataset:
Active stabilization of kilogauss magnetic fields to the ppm level for magnetoassociation on ultranarrow Feshbach resonances
Authors: Borkowski Mateusz , Reichsöllner Lukas , Thekkeppatt Premjith , Barbé Vincent , van Roon Tijs , van Druten Klaasjan , Schreck Florian
Published: July 2023

Feshbach association of ultracold molecules using narrow resonances requires exquisite control of the applied magnetic field. Here, we present a magnetic field control system to deliver magnetic fields of over 1000 G with ppm-level precision integrated into an ultracold-atom experimental setup. We combine a battery-powered, current-stabilized power supply with active feedback stabilization of the magnetic field using fluxgate magnetic field sensors. As a real-world test, we perform microwave spectroscopy of ultracold Rb atoms and demonstrate an upper limit on our magnetic field stability of 2.4(3) mG at 1050 G [2.3(3) ppm relative] as determined from the spectral feature.
Global boundedness for a food chain model with general logistic source
Authors: Xu Lu , Yang Li , Xin Qiao
Published: July 2023

This paper concerns the higher-dimensional food chain model with a general logistic source ut = Δu + u(1 − uα−1 − v − w), vt = Δv − ∇·(ξv∇u) + v(1 − vβ−1 + u − w), wt = Δw − ∇·(χw∇v) + w(1 − wγ−1 + v + u) in a smooth bounded domain Ω ⊂ Rn(n ≥ 2) with homogeneous Neumann boundary conditions. It is shown that for some conditions on the logistic degradation rates, this problem possesses a globally defined bounded classical solution.
Generation of collimated far-ultraviolet (FUV) light using the laser-produced metal plasma
Authors: Ohnishi H. , Tamaki S. , Shiina Y. , Nakano Y.
Published: July 2023

Laser-produced plasma is a promising compact light source applicable in a broad range of wavelengths. We performed a spectroscopic analysis and plasma characterization of the laser-produced plasma of Al, Fe, Cu, and Inconel alloy (Ni/Cr/Fe) to explore their potential applications in the far-ultraviolet (FUV) region where these methods are yet widely exploited. The emission spectrum from each target exhibited a characteristic spectral profile over the wavelength range from 120 to 250 nm. These results were well reproduced by spectral simulations, providing detailed information on the plasma. We also developed a dedicated parabolic mirror that successfully collimated the plasma radiation into beam with an intensity enhanced by a factor of ∼35. Our study demonstrated the generation of collimated FUV radiation with an intensity of a 107 photons/pulse/1% bandwidth as a potent laboratory-size light source for various applications.
Spin textures in synthetic antiferromagnets: Challenges, opportunities, and future directions
Authors: Wang Kang , Bheemarasetty Vineetha , Xiao Gang
Published: July 2023

Spin textures, such as magnetic domain walls and skyrmions, have the potential to revolutionize electronic devices by encoding information bits. Although recent advancements in ferromagnetic films have led to promising device prototypes, their widespread implementation has been hindered by material-related drawbacks. Antiferromagnetic spin textures, however, offer a solution to many of these limitations, paving the way for faster, smaller, more energy-efficient, and more robust electronics. The functionality of synthetic antiferromagnets, comprised of two or more magnetic layers separated by spacers, may be easily manipulated by making use of different materials as well as interface engineering. In this Perspective article, we examine the challenges and opportunities presented by spin textures in synthetic antiferromagnets and propose possible directions and prospects for future research in this burgeoning field.
A novel hydrothermal route of preparing CuMnO2 nanoflakes and their application in Li-ion batteries and supercapacitors
Authors: Cheng Cuixia
Published: July 2023

CuMnO2 nanoflakes have been prepared utilizing a hydrothermal technique with nitrilotriacetic acid as a precipitant. The structure, composition, and morphology are characterized by several techniques. Interestingly, the as-prepared sample delivers 993 mAh g−1 after 300 cycles, excellent rate capabilities (523.2, 293.3, and 156.1 mAh g−1 at 0.5, 1.0, and 2.0 A g−1, respectively) as the anode of a Li-half battery, and a high specific capacitance of 403.3 F g−1 even at 12 A g−1, as well as stable cycling, excellent kinetics, and rate capabilities for supercapacitors applications, which are superior to the single Cu2O or Mn2O3, suggesting a great potential for advanced lithium-ion batteries.
Observation of enhanced dynamic ΔG effect near ferromagnetic resonance frequency
Authors: Hu Wenbin , Wang Yudi , Huang Mingxian , Zhang Huaiwu , Bai Feiming
Published: July 2023

The field-dependence elastic modulus of magnetostrictive films, also called ΔE or ΔG effect, is crucial for ultrasensitive magnetic field sensors based on surface acoustic waves (SAWs). In spite of a lot of demonstrations, rare attention was paid to the frequency-dependence of ΔE or ΔG effect. In this work, shear horizontal-type SAW delay lines coated with a thin FeCoSiB layer have been studied at various frequencies upon applying magnetic fields. The change of shear modulus of FeCoSiB has been extracted by measuring the field dependent phase shift of SAWs. It is found that the ΔG effect is significantly enhanced at high-order harmonic frequencies close to the ferromagnetic resonance frequency, increasing by ∼82% compared to that at the first SAW mode (128 MHz). In addition, the smaller the effective damping factor of a magnetostrictive layer, the more pronounced ΔG effect can be obtained, which is explained by our proposed dynamic magnetoelastic coupling model.
Acoustic Michelson interferometer based on a phononic crystal
Authors: Durmuşlar Aysevil Salman , Kaya Olgun Adem , Biçer Ahmet , Cicek Ahmet
Published: July 2023

A practical and highly sensitive acoustic Michelson interferometer with a small form factor is introduced. It involves two different types of phononic crystals composed of steel rods in water acting as a medium for self-collimated waves and mirrors for the reference and sample beams, as well as a beam splitter formed by modified scatterers arranged diagonally. Finite-element method simulations are employed to demonstrate its operation around 200 kHz. Equifrequency contour analysis reveals self-collimation of ultrasonic waves between 190 and 210 kHz. Introduction of the beam splitter and mirror phononic crystals is not detrimental to self-collimation where outgoing waves from the two interferometer arms interfere such that the output intensity varies in a cosine squared manner. Consequently, maximum sensitivity is achieved when the movable mirror displacement is either zero or half of the interferometer phononic crystal period. On small intervals in these ranges, micrometer-scale displacement resolution is achievable, as the output intensity drops by 0.2% per micrometer. Thus, displacements smaller than a percent of the wavelength are easily resolvable. Nanoscale resolution can be obtained with a scaled down interferometer design. Moreover, application to liquid concentration sensing by considering ethanol–water binary mixture is demonstrated. A percent increase in weight fraction of ethanol up to 10% in the mixture leads to an intensity drop as high as 2%. Thus, significantly higher sensitivities compared to sensing schemes based on resonance frequency shift are attainable. The proposed approach can be adapted for surface acoustic waves in strain measurement or biosensing.
Steady nanocapillary flow: Micropolar approach vs classical models
Authors: Khanukaeva D. Yu. , Troshkin A. R.
Published: July 2023

The peculiarities of nanocapillary flows are studied in the framework of Newtonian and micropolar fluid models. The classical problem of a steady flow driven by a constant pressure gradient is formulated for a cylindrical nanocapillary with a radius much smaller than its length. All possible boundary conditions (slip, no-slip, and stick-slip) are exploited for the model of the Newtonian fluid, and two alternative boundary value problems (hyper-stick and no-slip with nonzero spin) are considered for the micropolar fluid model. Parametric studies of the considered analytical solutions are fulfilled. The flow rate is calculated for the considered boundary value problems and compared with the experimental data known in the literature. Real material constants known for water are used in the analysis. It is demonstrated that the classical approach fails to explain simultaneously two experimental effects known for nanocapillaries: retardation of flow in a capillary with smooth walls and acceleration of flow in a capillary with rough walls. The explanation is given in the framework of a micropolar fluid model, which is the natural extension of the Newtonian fluid model.
In situ neutron diffraction study on the deformation behavior of the plastic inorganic semiconductor Ag2S
Authors: Wang Yanxu , Gong Wu , Kawasaki Takuro , Harjo Stefanus , Zhang Kun , Zhang Zhidong , Li Bing
Published: July 2023

Bulk Ag2S is a plastic inorganic semiconductor at room temperature. It exhibits a compressive strain greater than 50%, which is highly different from brittle conventional counterparts, such as silicon. Here, we present the experimental investigation of the deformation behavior in a plastic inorganic semiconductor Ag2S using in situ neutron diffraction during compressive deformation at room and elevated temperatures. At room temperature, the lattice strain partitioning among hkl-orientated grain families could be responsible for the significant work-hardening behavior in the bulk Ag2S with a monoclinic structure. The rapid accumulation of lattice defects and remarkable development of the deformation texture suggest that dislocation slip promotes plasticity. At 453 K, a monoclinic phase transforms into a body-centered cubic phase. A stress plateau appears at ∼−4.8 MPa, followed by a rehardening state. The deformation mode of bulk Ag2S at the initial stage is likely attributable to the migration of silver ions, and as strain increases, it is closer to that of room temperature, leading to rehardening.
Testing Lennard-Jones clusters for optimality
Authors: Kiessling Michael K.-H.
Published: July 2023

This note advertises a simple necessary condition for optimality that any list N ↦ vx(N) of computer-generated putative lowest average pair energies vx(N) of clusters that consist of N monomers has to satisfy whenever the monomers interact with each other through pair forces satisfying Newton’s “action equals re-action.” These can be quite complicated, as, for instance, in the TIP5P model with five-site potential for a rigid tetrahedral-shaped H2O monomer of water, or as simple as the Lennard-Jones single-site potential for the center of an atomic monomer (which is also used for one site of the H2O monomer in the TIP5P model, which in addition has four peripheral sites with Coulomb potentials). The empirical usefulness of the necessary condition is demonstrated by testing a list of publicly available Lennard-Jones cluster data that have been pooled from 17 sources, covering the interval 2 ≤ N ≤ 1610 without gaps. The data point for N = 447 failed this test, meaning the listed 447-particle Lennard-Jones cluster energy was not optimal. To implement this test for optimality in search algorithms for putatively optimal configurations is an easy task. Publishing only the data that pass the test would increase the odds that these are actually optimal, without guaranteeing it, though.
Reflections on genetic improvement
Authors: van der Werf J. H. J.
Published: July 2023

Dr Helen Newton-Turner introduced a powerful model of bringing science into practice by working closely with breeders and the wider industry. This collaboration model has led to considerable achievements in genetic improvement in the Australian animal industries, with efficient genetic evaluation systems being implemented, providing a platform to achieve well defined breeding objectives and the introduction of new technologies such as genomic selection. The same model can be used to foster future development to achieve sustainable further improvements, allowing further technologies such as functional genomics to be used where they add value.
Evaluation of the 5-ethynyl-1,3,3-trimethyl-3H-indole ligand for molecular materials applications
Authors: Jago David , Milan David C. , Sobolev Alexandre N. , Higgins Simon J. , Vezzoli Andrea , Nichols Richard J. , Koutsantonis George A.
Published: July 2023

The modification of conjugated organic compounds with organometallic moieties allows the modulation of the electronic and optoelectronic properties of such compounds and lends them to a variety of material applications. The organometallic complexes [M(Cp′)(L)n] (M = Ru or Fe; Cp′ = cyclopentadiene (Cp) or pentamethylcyclopentadiene (Cp*); (L)n = (PPh3)2 or 1,2-bi(diphenylphosphino)ethane (dppe)) and [M(L)n] (M = Ru; (L)n = (dppe)2 or (P(OEt)3)4; or M = Pt; (L)n = (PEt3)2, (PPh3)2 or tricyclohexylphosphine, (PCy3)2) modified with a 5-ethynyl-1,3,3-trimethyl-3H-indole ligand were prepared and characterised by NMR spectroscopy, IR and single-crystal X-ray diffraction. Cyclic voltammetry and IR spectroelectrochemistry of the ruthenium systems showed a single-electron oxidation localised over the M–C≡C–aryl moiety. The N-heteroatom of the indole ligand showed Lewis base properties and was able to extract a proton from a vinylidene intermediate as well as coordinate to CuI. Examples from the wire-like compounds were also studied by single-molecule break junction experiments but molecular junction formation was not observed. This is most likely attributable to the binding characteristics of the substituted terminal indole groups used here to the gold contacts.
Still a good dog! Long-term use and effectiveness of livestock guardian dogs to protect livestock from predators in Australia’s extensive grazing systems
Authors: van Bommel Linda , Johnson Chris N.
Published: July 2023

Context Livestock predation is a significant problem for livestock producers all over the world. Livestock guardian dogs (LGDs) can protect livestock from predators, but little is known about the factors that affect their use over long periods of time. Aims Our aims were to investigate the long-term use of LGDs in Australia and determine whether their effectiveness remained high over time, and to establish the reasons for discontinued use. We also wanted to collect data on the fate of LGDs, and how using LGDs affected the use of other methods for predation control. Last, we wanted to estimate the rate at which the use of LGDs is spreading through word-of-mouth. Methods We re-contacted participants from a previous survey of LGD users in Australia and interviewed them about their long-term experience. We were able to include 82% (112) of the original participants, a mean of 8.9 (±0.08) years after the first survey. Key results Half of all original participants were still using LGDs, and in most cases the effectiveness of LGDs had not changed since the first survey. The main reason for ceasing use of LGDs was a change in business that made the dogs unnecessary, followed by unwanted behaviour of dogs, and problems with neighbours. Most LGDs that died prior to old age were euthanised, fell victim to lethal predator control, or were killed by wildlife. Farmers with LGDs reduced other forms of predation control. Informal information transfer among farmers is leading to a net increase in the use of LGDs in Australia. Conclusions LGDs can remain an effective predator control method in Australia with long-term use, and their use is spreading. However, a substantial number of livestock producers experience difficulties in properly training and managing LGDs, leading to failure of the method in some cases and presumably limiting uptake. Implications Given the effectiveness of LGDs for predation management and the many advantages gained by their use, Australia could greatly benefit from programs by government or management agencies both to promote uptake of LGDs and to reduce the incidence of problems by providing farmers with advice and information on best-practice management.
Habitat suitability correlates with mean population fitness of a threatened marsupial predator
Authors: Moore Harry A. , Dunlop Judy A. , Nimmo Dale G.
Published: July 2023

Context Measuring the quality of habitats necessary for the survival of threatened species is a priority for conservation management, but traditional metrics are often too costly to implement. As a result, many practitioners rely on proxies such as habitat suitability, which are measured by relating environmental variables to species occurrence data using habitat suitability models. However, little research has examined how these proxies relate to actual measures of habitat quality, such as body condition. Aim By testing the relationship between habitat suitability and habitat quality – as characterised by mean population fitness – the aim of this study was to improve our understanding of ways in which we can reliably map habitat of high importance for a particular species, as well as habitats where populations are most susceptible to local extinction. Methods We used data from a large-scale monitoring program on the northern quoll (Dasyurus hallucatus), a threatened marsupial predator, which collected data on three measures of population mean fitness (measured as body mass accounting for size, tail circumference, and body mass). We correlated these measures with habitat suitability derived from a habitat suitability model. Key results We found quoll mean population fitness increased with increasing habitat suitability. In addition, we found mean population fitness increased with increasing topographic ruggedness, annual rainfall, rainfall variability, and decreasing distance to water, consistent with previous studies that suggest quolls are able to persist better in habitat where resource availability (shelter, food) is higher. Conclusions Our findings demonstrate the usefulness of habitat suitability models for predicting habitat quality for a threatened predator at a large scale, and that predictions of habitat suitability can correspond with measures of fitness. In addition, they support previous studies in highlighting the importance of topographically complex habitat for this species. Implications These findings have important implications for identifying both source populations, where species recruitment is likely to exceed mortality, and more vulnerable populations that may require targeted conservation interventions to ensure their long-term persistence and stability.
Microstructure evolution of lean duplex stainless steel produced by a short process
Authors: Zhang Xinghai , Gong Qingdi , Li Jiaqi , Liu Chunting , Li Jingyuan
Published: July 2023

A short process of direct cold rolling of continuous casting billets following solution treatment is proposed, and the effect of cold-rolled reduction on the microstructure evolution and corrosion resistance of lean duplex stainless steel (LDSS) 2101 is investigated. The results show that when the cold-rolled reduction increased to 50%, the strain-induced martensite (SIM) engulfed the austenite along the annealing twin boundaries (TBs). Furthermore, the galvanic corrosion of the martensite and matrix combined with the decreasing fraction of the low-Σ CSL boundaries results in a significant reduction in corrosion resistance at 50% cold-rolled reduction. Additionally, the majority of metastable pits were generated within the ferrite grains and at the α/γ phase boundaries.
Structural and optical characteristics of NiO films deposited using the PLD technique
Authors: Farha A. H.
Published: July 2023

NiO films were deposited on glass and Si(100) substrates by reactive pulsed laser deposition from the Ni target. Nd: YAG laser (1064 nm) was used. The oxygen pressure was between 0.05 and 0.3 Torr. The optimum conditions for a good-quality NiO film are an oxygen pressure of 0.1 Torr and a laser power of 410 mW. Preferred orientation changes from (200) to (220) and D decreases from 27 to ∼9 nm as the temperature increases from 200 to 300°C. The preferred orientation changes into (111), nanoparticles size reduces from 46 to 26 nm and D drops from 27 to 10 nm as laser power increases from 410 to 820 mW. The oxygen pressure is significantly affecting the composition and morphologies of the NiO films. The optical band gap was 3.35 eV.
EURAMET DOSEtrace supplementary comparison in terms of the ambient dose equivalent/rate for photon radiation (EURAMET.RI(I)-S18)
Authors: Živanović Miloš , Hupe Oliver , Zutz Hayo , Šabeta Amra , Sandtner Stanislav , Kržanović Nikola
Published: July 2023

Main text

A supplementary comparison in terms of the ambient dose equivalent/rate was organized within EURAMET as a part of the DOSEtrace project, between 13 national metrology institutes and designated institutes. Calibration coefficients were compared for a secondary standard ionisation chamber for 3 X-ray and 2 γ-ray radiation qualities used in the field of radiation protection. Radiation qualities were established according to ISO 4037-1. Measurements were performed between 2019 and 2021.

For the purpose of this comparison, it was considered that the reported uncertainty was confirmed if the relative deviation from the comparison reference value was smaller than or equal to the associated uncertainty. All the reported results by all the partners satisfied this criterium. Three participants were not able to perform calibrations in all mandatory radiation qualities, due to technical problems. The results are published in the Key Comparison Data Base (KCDB) of the BIPM as supplementary comparison EURAMET.RI(I)-S18.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Study of correspondence principle in 1-dimension through examples
Authors: Paul Susobhan , Bhattacharyya Satadal , Mitra Joydip
Published: July 2023

We present several examples both for non-perturbative and perturbative systems to illustrate Bohr’s correspondence principle which is not usually treated in common text-books. In particular, the importance of the limit n → ∞ and h → 0 in understanding of the classical limit of quantum theory has been discussed explicitly in each case.
Enhanced performance of perovskite solar cell by using wavy pattern microstructure antireflective foil as a front surface
Authors: Ma Nanxi , Lu Feiping , Tang Fei , Ling Weijun , Yang Jinfang
Published: July 2023

Perovskite solar cells (PSCs) have been considered promising photovoltaic technology, given their potential to achieve high power conversion efficiency (PCE) and simple preparation technology. Improving the efficiency of PSCs has always been one of the hot issues concerned by researchers since the first PSCs were reported. In this paper, the PSCs with the structure of glass/ITO/poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]/perovskite/C60/atomic layer deposition device SnO
x
/Ag were carefully designed and prepared, and two kinds of polydimethylsiloxane (PDMS) film were scheduled and used in front surfaces of the prepared PSCs as the antireflective foil, which effectively improved the performance of PSCs. Compared with the control device, the short-circuit current density (J
SC) and PCE for the PSCs with flat or wavy pattern microstructure PDMS antireflective foil as front surfaces can be improved simultaneously, reaching 22.67 mA cm−2 and 20.57%, increased by 8.5% and 8.8%, respectively. The improvement of device performance can be ascribed to the advancement of light absorption and reduction of light reflectance by using the wavy pattern microstructure PDMS antireflective foil at the front surface. Lastly, the working mechanism of wavy pattern microstructure PDMS antireflective foil was discussed. This work can provide a facile way to improve the performance of PSCs.
Evaluation of predictive correlation between flux expulsion and grain growth for superconducting radio frequency cavities
Authors: Sung Zu Hawn , Kulyavtsev Paulina , Martinello Martina , Gonnella Dan , Ross Marc , Posen Sam
Published: July 2023

A series of experiments were carried out in an effort to develop a simple method for predicting the magnetic flux expulsion behavior of high purity niobium used to fabricate superconducting radio frequency (SRF) cavities. Using conventional metallographic characterizations in conjunction with high spatial resolution electron backscattered diffraction-orientation imaging microscopy, we find that the flux expulsion behavior of 1.3 GHz single cell SRF Nb cavities is significantly associated with the grain growth of the Nb material during heat treatment. Most of the Nb grains rapidly grew during 900 °C heat treatment, and were likely full-recrystallized with 1000 °C HT. When compared to the magnetic flux expulsion ratio (B
sc/B
nc) at ΔT = 5 K, the flux expulsion efficiency of the cavities increases with the increase of grain size. Most interestingly, 900 °C HT shows a roughly linear trend that suggests that this criterion could be used to predict the appropriate heat treatment temperature for sufficient flux expulsion behavior in SRF-grade Nb. This result can be used to see if flux expulsion can be predicted by examining the materials coming from Nb vendors, prior to cavity fabrication.
Thermodynamics of exponential Kolmogorov–Nagumo averages
Authors: Morales Pablo A , Korbel Jan , Rosas Fernando E
Published: July 2023

This paper investigates generalized thermodynamic relationships in physical systems where relevant macroscopic variables are determined by the exponential Kolmogorov–Nagumo average. We show that while the thermodynamic entropy of such systems is naturally described by Rényi’s entropy with parameterγ, an ordinary Boltzmann distribution still describes their statistics under equilibrium thermodynamics. Our results show that systems described by exponential Kolmogorov–Nagumo averages can be interpreted as systems originally in thermal equilibrium with a heat reservoir with inverse temperatureβthat are suddenly quenched to another heat reservoir with inverse temperatureβ′=(1−γ)β. Furthermore, we show the connection with multifractal thermodynamics. For the non-equilibrium case, we show that the dynamics of systems described by exponential Kolmogorov–Nagumo averages still observe a second law of thermodynamics and the H-theorem. We further discuss the applications of stochastic thermodynamics in those systems—namely, the validity of fluctuation theorems—and the connection with thermodynamic length.
Research on Calibration Method of off-axis Closed-loop Detection System for Multi-target Spectral Telescope
Authors: Du Congcong , Wang Yingfu , Duan Shipeng , Liang Jiadong , Cai Zeyu , Liu Zhigang , Hu Hongzhuan , Wang Jianping , Chu Jiaru , Cui Xiangqun , Zhang Yong , Zhang Haotong , Zhou Zengxiang
Published: July 2023

The LAMOST telescope has been operating steadily for more than 10 yr and is currently undergoing an upgrade to its fiber-optic positioning system on the telescope’s focal plane. By adding a vision detection system to accurately measure the current position of the optical fibres and carry out closed-loop feedback control, the positioning accuracy of the original optical fiber system is greatly improved. Due to the limitation of the existing optical path of the telescope, to avoid blocking the optical path, the detection system camera cannot be placed on the optical axis of the telescope, which makes the camera and the optical fiber end face at a relatively inclined position. However, the angle between the camera and an object will introduce errors to the polynomial calibration method used in the visual detection system. To address this problem, by analyzing the relationship between the camera imaging principle and the polynomial calibration method, this paper studies the influence of distortion and imaging angle on polynomial calibration results under different angle conditions and proposes an improved high-precision polynomial calibration method. First, the distortion parameters are calculated using Zhang’s method, and the image distortion is removed. Then, a mapping model between oblique plane image and nonoblique plane image is established through a homography matrix. The coordinates of all oblique plane feature points are mapped one by one to the nonoblique plane positions on the image space, and a good correction effect is obtained. Finally, the calibration images from different angles are calculated and analyzed through simulation experiments and compared with Zhang’s method. The results show that this method has a 10%–40% improvement over Zhang’s method.
Schrödinger and Klein–Gordon theories of black holes from the quantization of the Oppenheimer and Snyder gravitational collapse
Authors: Corda Christian
Published: July 2023

The Schrödinger equation of the Schwarzschild black hole (BH) has been recently derived by the author and collaborators. The BH is composed of a particle, the ‘electron’, interacting with a central field, the ‘nucleus’. Via de Broglie’s hypothesis, one interprets the ‘electron’ in terms of BH horizon’s modes. Quantum gravity effects modify the BH semi-classical structure at the Schwarzschild scale rather than at the Planck scale. The analogy between this BH Schrödinger equation and the Schrödinger equation of the s states of the hydrogen atom permits us to solve the same equation. The quantum gravitational quantities analogous of the fine structure constant and of the Rydberg constant are not constants, but the dynamical quantities have well-defined discrete spectra. The spectrum of the ‘gravitational fine structure constant’ is the set of non-zero natural numbers. Therefore, BHs are well-defined quantum gravitational systems obeying Schrödinger’s theory: the ‘gravitational hydrogen atoms’. By identifying the potential energy in the BH Schrödinger equation as being the gravitational energy of a spherically symmetric shell, a different nature of the quantum BH seems to surface. BHs are self-interacting, highly excited, spherically symmetric, massive quantum shells generated by matter condensing on the apparent horizon, concretely realizing the membrane paradigm. The quantum BH described as a ‘gravitational hydrogen atom’ is a fictitious mathematical representation of the real, quantum BH, a quantum massive shell having a radius equal to the oscillating gravitational radius. Nontrivial consequences emerge from this result: (i) BHs have neither horizons nor singularities; (ii) there is neither information loss in BH evaporation, nor BH complementarity, nor firewall paradox. These results are consistent with previous ones by Hawking, Vaz, Mitra and others. Finally, the special relativistic corrections to the BH Schrödinger equation give the BH Klein–Gordon equation and the corresponding eigenvalues.
Molecular dynamics study of thermal conductivities of cubic diamond, lonsdaleite, and nanotwinned diamond via machine-learned potential
Authors: Xiong 熊 Jia-Hao 佳豪 , Qi 戚 Zi-Jun 梓俊 , Liang 梁 Kang 康 , Sun 孙 Xiang 祥 , Sun 孙 Zhan-Peng 展鹏 , Wang 汪 Qi-Jun 启军 , Chen 陈 Li-Wei 黎玮 , Wu 吴 Gai 改 , Shen 沈 Wei 威
Published: July 2023

Diamond is a wide-bandgap semiconductor with a variety of crystal configurations, and has the potential applications in the field of high-frequency, radiation-hardened, and high-power devices. There are several important polytypes of diamonds, such as cubic diamond, lonsdaleite, and nanotwinned diamond (NTD). The thermal conductivities of semiconductors in high-power devices at different temperatures should be calculated. However, there has been no reports about thermal conductivities of cubic diamond and its polytypes both efficiently and accurately based on molecular dynamics (MD). Here, using interatomic potential of neural networks can provide obvious advantages. For example, comparing with the use of density functional theory (DFT), the calculation time is reduced, while maintaining high accuracy in predicting the thermal conductivities of the above-mentioned three diamond polytypes. Based on the neuroevolution potential (NEP), the thermal conductivities of cubic diamond, lonsdaleite, and NTD at 300 K are respectively 2507.3 W⋅m−1⋅K−1, 1557.2 W⋅m−1⋅K−1, and 985.6 W⋅m−1⋅K−1, which are higher than the calculation results based on Tersoff-1989 potential (1508 W⋅m−1⋅K−1, 1178 W⋅m−1⋅K−1, and 794 W⋅m−1⋅K−1, respectively). The thermal conductivities of cubic diamond and lonsdaleite, obtained by using the NEP, are closer to the experimental data or DFT data than those from Tersoff-potential. The molecular dynamics simulations are performed by using NEP to calculate the phonon dispersions, in order to explain the possible reasons for discrepancies among the cubic diamond, lonsdaleite, and NTD. In this work, we propose a scheme to predict the thermal conductivity of cubic diamond, lonsdaleite, and NTD precisely and efficiently, and explain the differences in thermal conductivity among cubic diamond, lonsdaleite, and NTD.
A Linear Operator Method to Compute the Normal Modes with Rotation of any Asymmetric 3D Planet with Pure Vector Spherical Harmonics
Authors: Zhang Mian , Huang Cheng-Li
Published: July 2023

In order to compute the free core nutation of the terrestrial planets, such as Earth and Mars, the Moon and lower degree normal modes of the Jovian planets, we propose a linear operator method (LOM). Generalized surface spherical harmonics (GSSHs) are usually applied to the elliptical models with a stress tensor, which cannot be expressed in vector spherical harmonics explicitly. However, GSSHs involve complicated math. LOM is an alternative to GSSHs, whereas it only deals with the coupling fields of the same azimuthal order m, as is the case when a planet model is axially symmetric and rotates about that symmetry axis. We extend LOM to any asymmetric 3D model. The lower degree spheroidal modes of the Earth are computed to validate our method, and the results agree very well with what is observed. We also compute the normal modes of a two-layer Saturn model as a simple application.
Modified Masses and Parallaxes of Close Binary Systems: HD 39438
Authors: Masda Suhail , Yousef Z. T. , Al-Wardat Mashhoor , Al-Khasawneh Awni
Published: July 2023

We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat’s method for analyzing binary and multiple stellar systems. The method implements Kurucz’s plane parallel model atmospheres to construct synthetic spectral energy distributions (SEDs) for both components of the system. It then combines the results of the spectroscopic analysis with the photometric analysis and compares them with the observed ones to construct the best synthetic SED for the combined system. The analysis gives the precise fundamental parameters of the individual components of the system. Based on the positions of the components of HD 39438 on the H-R diagram, and evolutionary and isochrone tracks, we found that the system belongs to the main sequence stars with masses of 1.24 and 0.98 solar masses for the components A and B, respectively, and age of 1.995 Gyr for both components. The main result of HD 39438 is new dynamical parallax, which is estimated to be 16.689 ± 0.03 mas.
A Spectral Element Method to Compute Earth’s Free Core Nutation
Authors: Zhang Mian , Huang Cheng-Li
Published: July 2023

The Free Core Nutation (FCN) is a rotational mode caused by non-alignment of the rotation axis of the core and of the mantle. Its period observed by VLBI and superconducting gravimetry is around 430 sidereal days (Sd) with precision of better than 1 Sd, while its “theoretical” period calculated by traditional approaches and a given Earth model ranges from 450 to 470 Sd. Their gap of about 30 Sd is significant compared with its observation precision. We propose a spectral element method to compute the period of FCN and obtain a period of 434 Sd which is very close to the observed value.
A Pulsar Wind Nebula Origin of the Ultra-high-energy Source 1LHAASO J1929+1846
Authors: Xia Qi , Zhou Lian-Cheng , Fang Jun
Published: July 2023

1LHAASO J1929+1846 is one of the ultra-high-energy (UHE, E > 0.1 PeV) sources in the first catalog of γ-ray sources detected by the Large High Altitude Air Shower Observatory. It has been detected fluxes at 3 TeV for 2.48 ± 0.11 × 10−13 TeV−1 cm−2 s−1 with the Water Cherenkov Detector Array and at 50 TeV for 0.64 ± 0.06 × 10−16 TeV−1 cm−2 s−1 with the Kilometer Squared Array, but the origin of its UHE emission remains unknown. The pulsar wind nebula (PWN) G54.1+0.3, which is powered by the pulsar PSR 1930+1852 with a period of 136 ms and it is detected within a 0.°29 region around the centroid of 1LHAASO J1929+1846. We explore whether G54.1+0.3 is capable of producing the UHE radiation of 1LHAASO J1929+1846. First, the data with Fermi Large Area Telescope for the PWN is analyzed to obtain the GeV fluxes. Second, the multiband non-thermal fluxes for the nebula are investigated based on a one-zone time-dependent model. In the model, we assume the spin-down energy of the pulsar is persistently injected into particles (electrons and positrons) and magnetic field in the PWN, and these high-energy particles produce multiband non-thermal radiation from radio to γ-rays via synchrotron radiation and inverse Compton scattering. We reproduce the spectral energy distribution of PWN G54.1+0.3 with reasonable parameters. The result indicates that the UHE γ-ray source 1LHAASO J1929+1846 possibly originates from PWN G54.1+0.3.
Assessment of the Seismic Vulnerability of a Multi-storey RC Structure with Plan Irregularity: A Case Study
Authors: Arif W , Craifaleanu I G
Published: July 2023

A nine-story reinforced concrete dual system (wall-frame) building located in Bucharest, categorized as plan-asymmetric and designed according to the provisions of Romanian and European codes was studied. The criteria for regularity in plan were verified comparatively according to three codes (Eurocode 8, ASCE 7-16 and the Romanian seismic design code P100-1-2013). The seismic behaviour of the studied building was further investigated by detailed nonlinear static analyses (pushover) and nonlinear dynamic analyses performed on the 3-D building model, for various load patterns and spectrum-compatible ground motion records, respectively. The seismic vulnerability of the building was estimated based on the structural vulnerability index, determined from the nonlinear analyses. The study highlighted the significant effects of the overall torsion on the investigated parameters, in particular on interstory drifts and roof displacements, but also on the seismic vulnerability index.
Roadmap on spatiotemporal light fields
Authors: Shen Yijie , Zhan Qiwen , Wright Logan G , Christodoulides Demetrios N , Wise Frank W , Willner Alan E , Zou Kai-heng , Zhao Zhe , Porras Miguel A , Chong Andy , Wan Chenhao , Bliokh Konstantin Y , Liao Chen-Ting , Hernández-García Carlos , Murnane Margaret , Yessenov Murat , Abouraddy Ayman F , Wong Liang Jie , Go Michael , Kumar Suraj , Guo Cheng , Fan Shanhui , Papasimakis Nikitas , Zheludev Nikolay I , Chen Lu , Zhu Wenqi , Agrawal Amit , Mounaix Mickael , Fontaine Nicolas K , Carpenter Joel , Jolly Spencer W , Dorrer Christophe , Alonso Benjamín , Lopez-Quintas Ignacio , López-Ripa Miguel , Sola Íñigo J , Huang Junyi , Zhang Hongliang , Ruan Zhichao , Dorrah Ahmed H , Capasso Federico , Forbes Andrew
Published: July 2023

Spatiotemporal sculpturing of light pulse with ultimately sophisticated structures represents a major goal of the everlasting pursue of ultra-fast information transmission and processing as well as ultra-intense energy concentration and extraction. It also holds the key to unlock new extraordinary fundamental physical effects. Traditionally, spatiotemporal light pulses are always treated as spatiotemporally separable wave packet as solution of the Maxwell’s equations. In the past decade, however, more generalized forms of spatiotemporally nonseparable solution started to emerge with growing importance for their striking physical effects. This roadmap intends to highlight the recent advances in the creation and control of increasingly complex spatiotemporally sculptured pulses, from spatiotemporally separable to complex nonseparable states, with diverse geometric and topological structures, presenting a bird’s eye viewpoint on the zoology of spatiotemporal light fields and the outlook of future trends and open challenges.
Visualization of the composition of the urinary fluorescent metabolome. Why is it important to consider initial urine concentration?
Authors: Dubayová Katarína , Birková Anna , Lešo Martin , Žilková Jaroslava , Karabinoš Anton , Mareková Mária , Stupák Marek
Published: July 2023

Urine is a highly complex fluorescent system, the fluorescence of which can be affected by many factors, including the often-ignored initial urine concentration in comprehensive fluorescent urine analysis. In this study, a total urine fluorescent metabolome profile (uTFMP) was created as a three-dimensional fluorescence profile of serial synchronous spectra of urine diluted by geometric progression. uTFMP was generated using software designed for this purpose after recalculating the 3D data concerning the initial urine concentration. It can be presented as a contour map (top view) or as a more illustrative and straightforward simple curve, thus usable in various medicinal applications.
Could normalization improve robustness of abdominal MRI radiomic features?
Authors: Giannini Valentina , Panic Jovana , Regge Daniele , Balestra Gabriella , Rosati Samanta
Published: July 2023

Radiomics-based systems could improve the management of oncological patients by supporting cancer diagnosis, treatment planning, and response assessment. However, one of the main limitations of these systems is the generalizability and reproducibility of results when they are applied to images acquired in different hospitals by different scanners. Normalization has been introduced to mitigate this issue, and two main approaches have been proposed: one rescales the image intensities (image normalization), the other the feature distributions for each center (feature normalization). The aim of this study is to evaluate how different image and feature normalization methods impact the robustness of 93 radiomics features acquired using a multicenter and multi-scanner abdominal Magnetic Resonance Imaging (MRI) dataset. To this scope, 88 rectal MRIs were retrospectively collected from 3 different institutions (4 scanners), and for each patient, six 3D regions of interest on the obturator muscle were considered. The methods applied were min-max, 1st-99th percentiles and 3-Sigma normalization, z-score standardization, mean centering, histogram normalization, Nyul-Udupa and ComBat harmonization. The Mann-Whitney U-test was applied to assess features repeatability between scanners, by comparing the feature values obtained for each normalization method, including the case in which no normalization was applied. Most image normalization methods allowed to reduce the overall variability in terms of intensity distributions, while worsening or showing unpredictable results in terms of feature robustness, except for the z-score, which provided a slight improvement by increasing the number of statistically similar features from 9/93 to 10/93. Conversely, feature normalization methods positively reduced the overall variability across the scanners, in particular, 3sigma, z_score and ComBat that increased the number of similar features (79/93). According to our results, it emerged that none of the image normalization methods was able to strongly increase the number of statistically similar features.
Arctic warming in response to regional aerosol emissions reductions
Authors: Previdi Michael , Lamarque Jean-François , Fiore Arlene M , Westervelt Daniel M , Shindell Drew T , Correa Gustavo , Faluvegi Gregory
Published: July 2023

This study examines the Arctic surface air temperature response to regional aerosol emissions reductions using three fully coupled chemistry–climate models: National Center for Atmospheric Research-Community Earth System Model version 1, Geophysical Fluid Dynamics Laboratory-Coupled Climate Model version 3 (GFDL-CM3) and Goddard Institute for Space Studies-ModelE version 2. Each of these models was used to perform a series of aerosol perturbation experiments, in which emissions of different aerosol types (sulfate, black carbon (BC), and organic carbon) in different northern mid-latitude source regions, and of biomass burning aerosol over South America and Africa, were substantially reduced or eliminated. We find that the Arctic warms in nearly every experiment, the only exceptions being the U.S. and Europe BC experiments in GFDL-CM3 in which there is a weak and insignificant cooling. The Arctic warming is generally larger than the global mean warming (i.e. Arctic amplification occurs), particularly during non-summer months. The models agree that changes in the poleward atmospheric moisture transport are the most important factor explaining the spread in Arctic warming across experiments: the largest warming tends to coincide with the largest increases in moisture transport into the Arctic. In contrast, there is an inconsistent relationship (correlation) across experiments between the local radiative forcing over the Arctic and the simulated Arctic warming, with this relationship being positive in one model (GFDL-CM3) and negative in the other two. Our results thus highlight the prominent role of poleward energy transport in driving Arctic warming and amplification, and suggest that the relative importance of poleward energy transport and local forcing/feedbacks is likely to be model dependent.
Regional participation trends for community wildfire preparedness program Firewise USA
Authors: Kampfschulte Andrew R , Miller Rebecca K
Published: July 2023

Community-wide wildfire mitigation can effectively protect homes from structure ignition. The Firewise USA program provides a framework for grassroots wildfire preparedness. Here, we examine the 500 Firewise USA sites in California to understand participation and demographic trends. We find important regional differences regarding the influence of underlying fire hazard, fire history, and other Firewise sites on new site formation. Sites in the Bay Area and Sierras respond strongly to fire history and proximity to other Firewise sites, while Northern and Southern California have few Firewise sites despite underlying hazardous conditions and large fire history. Firewise sites are often whiter, older, and more well-educated than California’s median population, potentially leaving out many communities that do not meet this demographic profile but face severe risks from wildfires. These findings offer important insights into the factors motivating communities to pursue wildfire protection, particularly important given recent severe and destructive wildfire seasons.