bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paleolakes and socioecological implications of last glacial “greening” of the South African interior
Authors: Carr Andrew S. , Chase Brian M. , Birkinshaw Stephen J. , Holmes Peter J. , Rabumbulu Mulalo , Stewart Brian A. 
Published: May 2023

Determining the timing and drivers of Pleistocene hydrological change in the interior of South Africa is critical for testing hypotheses regarding the presence, dynamics, and resilience of human populations. Combining geological data and physically based distributed hydrological modeling, we demonstrate the presence of large paleolakes in South Africa’s central interior during the last glacial period, and infer a regional-scale invigoration of hydrological networks, particularly during marine isotope stages 3 and 2, most notably 55 to 39 ka and 34 to 31 ka. The resulting hydrological reconstructions further permit investigation of regional floral and fauna responses using a modern analog approach. These suggest that the climate change required to sustain these water bodies would have replaced xeric shrubland with more productive, eutrophic grassland or higher grass-cover vegetation, capable of supporting a substantial increase in ungulate diversity and biomass. The existence of such resource-rich landscapes for protracted phases within the last glacial period likely exerted a recurrent draw on human societies, evidenced by extensive pan-side artifact assemblages. Thus, rather than representing a perennially uninhabited hinterland, the central interior’s underrepresentation in late Pleistocene archeological narratives likely reflects taphonomic biases stemming from a dearth of rockshelters and regional geomorphic controls. These findings suggest that South Africa’s central interior experienced greater climatic, ecological, and cultural dynamism than previously appreciated and potential to host human populations whose archaeological signatures deserve systematic investigation.
The activated scaling behavior of quantum Griffiths singularity in two-dimensional superconductors
Authors: Cui Zihan , Pan Longxin , Fang Jingchao , Qi Shichao , Xing Ying , Liu Haiwen , Liu Yi , Wang Jian 
Published: May 2023

Abstract
Quantum Griffiths singularity (QGS) is characterized by the divergence of the dynamical critical exponent with the activated scaling law and has been widely observed in various two-dimensional superconductors. Recently, the direct activated scaling analysis with the irrelevant correction was proposed and successfully used to analyze the experimental data of crystalline PdTe2 and polycrystalline

β

-W films, which provides new evidence of QGS. Here we show that the direct activated scaling analysis is applicable to the experimental data in different superconducting films, including tri-layer Ga films and LaAlO3/SrTiO3 interface superconductors. When taking the irrelevant correction into account, we calculate the corrected sheet resistance at ultralow temperatures. The scaling behavior of the corrected resistance in a comparably large temperature regime and the theoretical fitting of the phase boundary give unambiguous evidence of QGS. Compared to previous methods based on finite size scaling, the direct activated scaling analysis represents a more direct and precise way to analyze the experimental data of QGS in diverse two-dimensional superconductors.
Observation of high phase velocity of dust acoustic waves with elongated dust grains in a cryogenic dusty plasma experiment
Authors: Chai Kil-Byoung 
Published: May 2023

Abstract
Self-excited dust acoustic waves (DAWs) with a high phase velocity were observed in the cryogenic dusty plasma experiment, where submillimeter, elongated, and fractal-like water-ice dust grains are formed. The phase velocity of the observed DAWs was obtained by the fast Fourier transform of the sequential images of the DAWs and it ranges from 8 to 15 cm s−1. The length of the dust grains was measured between 100 and 250 μm and the thermal speed of the dust grains was obtained between 1.5 and 2.8 cm s−1. It is shown that the linear theory including the effect of the dust thermal speed can explain the observed fast phase velocity. The possible mechanisms by which the submillimeter dust grains gain such high kinetic energies are discussed.
An ab initio study of the electronic properties of helium in wurtzite gallium nitride
Authors: Alfieri Giovanni , Fujii Yusuke , Micheletto Ruggero 
Published: May 2023

Abstract
Impurities and their complexes with intrinsic point defects, e.g. vacancies, can alter the opto-electronic properties of semiconductors. Among such impurities, helium is incorporated into gallium nitride (GaN) by ion implantation, for wafer splitting and for device isolation purposes. Yet, despite the technological importance of such impurity, it is not known whether or not He is electrically active in GaN or what its impact on n- or p-type dopants is. For this reason, we carried out a density functional theory study of substitutional He and related complexes (vacancies and dopants) in wurtzite GaN. We employed the generalized gradient approximation and overcame the band gap energy underestimation, by a posteriori corrections. It is found that He is unstable at N-sites, moving to interstitial sites and forming a N vacancy (V

N
). This was observed for the case of substitutional He and for He complexed with n- or p-type dopants. The formation of V

N
, in such defects, gives rise to donor states close to the valence band edge (E
V
). On the other hand, the presence of a gallium vacancy (V

G
a

) leads to the formation of an energetically stable complex that gives rise to acceptor states close to the conduction band edge (E
C
). Our findings are then discussed in the light of previous experimental reports on GaN device isolation.
On the rate of convergence of an exponential scheme for the non-linear stochastic Schrödinger equation with finite-dimensional state space
Authors: Mora Carlos M , Muñoz Mario 
Published: May 2023

Abstract
We address the numerical solution of the finite-dimensional non-linear stochastic Schrödinger equation, which is a locally Lipschitz stochastic differential equation modeling, for instance, quantum measurement processes. We study the rate of weak convergence of an exponential scheme that reproduces the norm of the desired solution by projecting onto the unit sphere. This justifies the use of the Talay-Tubaro extrapolation procedure in the numerical simulation of open quantum systems. In particular, we prove that an Euler-Exponential scheme converges with weak-order one, and we obtain the leading order term of its weak error expansion with respect to the step-size. Then, applying the Talay-Tubaro extrapolation procedure to the Euler-Exponential scheme under consideration we get a second-order method for computing the mean values of smooth functions of the solution of the non-linear stochastic Schrödinger equation. We also prove that the exponential scheme under study has order of strong convergence 1/2, which gives theoretical support to the use of the multilevel Monte Carlo method in simulating open quantum systems. We present a numerical experiment with a quantized electromagnetic field in interaction with a reservoir that illustrates the good performance of the weak second-order method, and the multilevel Monte Carlo method.
Structure, stability and defect energetics of interfaces formed between conventional and transformed phases in Cu–Nb layered nanocomposite
Authors: Saikia Ujjal , Sahariah Munima B , Dutta Biswanath , Pandey Ravindra 
Published: May 2023

Abstract
Layered nanocomposite material having fcc-bcc interface with Kurdjumov-Sachs interface orientation relation has shown great potential as radiation resistant structural material for future fusion energy reactors. The superior radiation resistant properties of this material are attributed to it’s special fcc-bcc interface structure. In this study we have reported a stable interface between conventional bcc phase of Nb and transformed bcc phase of Cu. This bcc-bcc interface is found to be stable from both strain-energy and dynamical stability analysis. We have also shown that the bcc-bcc interface has different defect energetics behaviour compared to previously reported fcc-bcc interface which has a negative impact on the self annihilation property of the material against radiation induced defects. These aspects should be carefully considered in the future design of robust layered material for extreme radiation environment.
Influence of coulomb damping on wave propagation behaviors of nonlinear nonconservative phononic chains/lattices
Authors: Sepehri Soroush , Bodaghi Mahdi 
Published: May 2023

Abstract
Fascinating nonlinearity-induced behavior of phononic crystals (PCs) has recently become a hot research topic in the community. However, due to the limitations in the analytical modelling of damping in dynamic systems, the study of damped PCs has not received proper attention. In this paper, the influence of Coulomb damping on the wave propagation behavior of cubically nonlinear monoatomic phononic chains is investigated. To do so, the nonlinear dispersion relation is obtained analytically using the well-established multiple scales method and the band structure of the damped nonlinear chains is compared to the ones corresponding to the linear and nonlinear undamped chains. Due to the coupling between the amplitude and the frequency, stemmed from the nonlinear nature of the chain, Coulomb damping can lead to lower dispersion frequencies in the chain. The formulation and results are then expanded to 2D nonlinear lattices. The present manuscript is the first attempt to capture the effect of Coulomb damping on the wave propagation behavior of nonlinear lattices and the results put us one step closer to developing a comprehensive analytical model for the behavior of damped PCs which can in turn lead to invaluable design concepts for nonlinear nonconservative wave-manipulation devices.
Defect solitons supported by optical lattice with saturable nonlinearity in fractional Schrödinger equation
Authors: Wang Shengyao , Xia Tuanjie , Chen Weijun , Zhao Peng 
Published: May 2023

Abstract
We address the existence, stability, and propagation dynamics of both one- and two-dimensional defect solitons supported by optical lattice with saturable nonlinearity in fractional Schrödinger equation. Under the influence of fractional effect, in one dimension, solitons exist stably in limited regions in the semi-infinite bandgap with high and low power both for a negative and positive defect lattice. In the first bandgap, solitons are stable for negative defect lattice, while unstable for positive defect lattice. In the second bandgap, only stable solitons can propagate in small regions for the positive defect lattice. With increasing the Lévy index from 1 to 2, the power of the defect solitons decreases in the semi-infinite bandgap and increases in the first bandgap. Linear stability analyses show that, the domains of stability for defect solitons strongly depend on the Lévy index, defect strength and different bandgaps. In two dimension, defect solitons can exist stably at high and moderate power regions in the semi-infinite bandgap and all regions in the first bandgap with negative defect lattice, while they are stable at high, moderate and low power regions in the semi-infinite bandgap and unstable in the first bandgap with positive defect lattice.
Small polaron hopping transport mechanism, dielectric relaxation and electrical conduction in NiAl2O4 electro-ceramic spinel oxide
Authors: Iqbal Yousaf , Shah Waqar Hussain , Khan Bisma , Javed Muhammad , Ullah Hayat , Khan Nadia , Khan Abdul Rauf , Asghar Ghulam , Safeen Akif 
Published: May 2023

Abstract
In this study, the frequency and temperature dependent dielectric relaxation and electrical conduction mechanisms in NiAl2O4 spinel oxide ceramic have been explored in a frequency range of

50
−
10
×

10

6

Hz

over a measured temperature from 163–283 K. The polycrystalline NiAl2O4 was synthesized via solid state reaction route and sintered at 1000 °C. The room temperature x-ray powder diffraction pattern confirmed the formation of NiAl2O4 spinel phase with Fd3m space group. The surface morphology of the sample was investigated by scanning electron microscopy and chemical properties by Fourier transform infrared spectroscopic analysis. Complex impedance studies revealed the presence of relaxation time distribution and charge carriers were found to be thermally activated. The Nyquist plots exhibited depressed semicircles and their fitting by an equivalent circuit model with configuration (RGCG)(RGBCGB) resolved the contributions of grains and grain-boundaries to the electrical transport properties of the material. Electrical conductivity analysis followed the Jonscher’s power law behavior and the frequency exponent suggested small polaron hopping as the governing transport mechanism in NiAl2O4 spinel oxide. Non-Debye type nature of dielectric relaxation was confirmed by the complex modulus analysis whereas dielectric constant and tangent loss analysis verified that the hopping mechanism was thermally activated.
Why cosmic voids matter: nonlinear structure & linear dynamics
Authors: Schuster Nico , Hamaus Nico , Dolag Klaus , Weller Jochen 
Published: May 2023

Abstract
We use the Magneticum suite of state-of-the-art hydrodynamical simulations to identify
cosmic voids based on the watershed technique and investigate their most fundamental properties
across different resolutions in mass and scale. This encompasses the distributions of void sizes,
shapes, and content, as well as their radial density and velocity profiles traced by the
distribution of cold dark matter particles and halos. We also study the impact of various tracer
properties, such as their sparsity and mass, and the influence of void merging on these summary
statistics. Our results reveal that all of the analyzed void properties are physically related to
each other and describe universal characteristics that are largely independent of tracer type and
resolution. Most notably, we find that the motion of tracers around void centers is perfectly
consistent with linear dynamics, both for individual, as well as stacked voids. Despite the large
range of scales accessible in our simulations, we are unable to identify the occurrence of
nonlinear dynamics even inside voids of only a few Mpc in size. This suggests voids to be among
the most pristine probes of cosmology down to scales that are commonly referred to as highly
nonlinear in the field of large-scale structure.
Constraints on the phase transition of early dark energy with the CMB anisotropies
Authors: Hayashi Shintaro , Minoda Teppei , Ichiki Kiyotomo 
Published: May 2023

Abstract
Early dark energy (EDE) models have attracted attention in the context of the recent problem of the Hubble tension. Here we extend these models by taking into account the new density fluctuations generated by the EDE which decays around the recombination phase.
We solve the evolution of the density perturbations in dark energy fluid generated at the phase transition of EDE as isocurvature perturbations. Assuming that the isocurvature mode is characterized by a power-law power spectrum and is uncorrelated with the standard adiabatic mode, we calculate the CMB angular power spectra. By comparing them to the Planck data using the Markov-Chain Monte Carlo method, we obtained zero-consistent values of the EDE parameters and H
0 = 67.56+0.65
-0.66 km s-1 Mpc-1 at 68 % CL. This H
0 value is almost the same as the Planck value in the ΛCDM model, H
0 = 67.36 ± 0.54 km s-1 Mpc-1, and there is still a ∼ 3.5σ tension between the CMB and Type Ia supernovae observations. Including CMB lensing, BAO, supernovae and SH0ES data sets, we find H
0 = 68.94+0.47
-0.57 km s-1 Mpc-1 at 68 % CL. The amplitude of the fluctuations induced by the phase transition of the EDE is constrained to be less than 1–2 percent of the amplitude of the adiabatic mode. This is so small that such non-standard fluctuations cannot appear in the CMB angular spectra.
In conclusion, the isocurvature fluctuations induced by our simplest EDE phase transition model do not explain the Hubble tension well.
Halo occupation distribution of Emission Line Galaxies: fitting method with Gaussian processes
Authors: Rocher Antoine , Ruhlmann-Kleider Vanina , Burtin Etienne , de Mattia Arnaud 
Published: May 2023

Abstract
The halo occupation distribution (HOD) framework is an empirical method to describe the
connection between dark matter halos and galaxies, which is constrained by small scale clustering
data. Efficient fitting procedures are required to scan the HOD parameter space. This paper
describes such a method based on Gaussian Processes to iteratively build a surrogate model of the
posterior of the likelihood surface from a reasonable amount of likelihood computations, typically
two orders of magnitude less than standard Monte Carlo Markov chain algorithms. Errors in the
likelihood computation due to stochastic HOD modelling are also accounted for in the method we
propose. We report results of reproducibility, accuracy and stability tests of the method derived
from simulation, taking as a test case star-forming emission line galaxies, which constitute the
main tracer of the Dark Energy Spectroscopic Instrument and have so far a poorly constrained
galaxy-halo connection from observational data.
What geometrically constrained models can tell us about real-world protein contact maps
Authors: Jasmin Güven J , Molkenthin Nora , Mühle Steffen , Mey Antonia S J S 
Published: May 2023

Abstract
The mechanisms by which a protein’s 3D structure can be determined based on its amino acid sequence have long been one of the key mysteries of biophysics. Often simplistic models, such as those derived from geometric constraints, capture bulk real-world 3D protein-protein properties well. One approach is using protein contact maps (PCMs) to better understand proteins’ properties. In this study, we explore the emergent behaviour of contact maps for different geometrically constrained models and compare them to real-world protein systems. Specifically, we derive an analytical approximation for the distribution of amino acid distances, denoted as P(s), using a mean-field approach based on a geometric constraint model. This approximation is then validated for amino acid distance distributions generated from a 2D and 3D version of the geometrically constrained random interaction model. For real protein data, we show how the analytical approximation can be used to fit amino acid distance distributions of protein chain lengths of L ≈ 100, L ≈ 200, and L ≈ 300 generated from two different methods of evaluating a PCM, a simple cutoff based method and a shadow map based method. We present evidence that geometric constraints are sufficient to model the amino acid distance distributions of protein chains in bulk and amino acid sequences only play a secondary role, regardless of the definition of the PCM.
An Independent Degree-eight Mars Gravity Field Model and the Expected Results from the Tianwen-1 Mission
Authors: Liu Shanhong , Cao Jianfeng , Yan Jianguo , Huang Hao , Li Xie , Barriot Jean-Pierre 
Published: May 2023

Abstract
Tianwen-1 is China’s first independent interplanetary exploration mission, targeting Mars, and includes orbiting, landing, and rover phases. Similar to previous Mars missions, the Tianwen-1 orbiter was designed for polar orbits during the scientific mission period but has an exceptional eccentricity of approximately 0.59. We provide the first independent eight-degree Martian gravity field model in this paper, which was developed exclusively by a team working in China with our independent software as well, based on about two months of radiometric Doppler and range data from only the Tianwen-1 mission. This model is independent from the models created by the groups at NASA Jet Propulsion Laboratory and Goddard Space Flight Center in the United States, as well as the Centre National d’Etudes Spatiales in France. Furthermore, in order to optimize the engineering and scientific benefits, we proposed a number of potential orbits for the extended Tianwen-1 mission. In order to solve a higher-degree independent Mars gravity field model, the viability of modifying the perigee height was investigated, with the priority considerations of fuel savings and implementation hazards being controlled.
An Integrated Structure Analysis Method of Active Surface Antenna by Using the Simplified Actuator
Authors: Ban You , Chai Peiyuan , Xu Qian , Feng Shufei 
Published: May 2023

Abstract
The main surface of a large reflector antenna is composed of thousands of panels, which are inevitably deformed under natural load, leading to a great deterioration of electrical performance of the antenna. The active surface technique is an effective method to compensate antenna deformation error and has been widely used. The actuator is a complex component, it has not been established in the antenna structure analysis model, which limits the theoretical analysis ability of the active surface technology. To solve this problem, an integrated structure analysis method of active surface antenna by using the simplified actuator is proposed. First, according to the supporting characteristics and adjusting function of the actuator, the complex actuator is simplified a simple structure of support beams, support truss and adjustment beam. Second, the finite element model of the active surface antenna including the simplified actuator is established. Then, the relationship between the adjustment value (load) of adjustment beam and the deformation of the antenna structure is deduced, and the integrated analysis method for realizing the active adjustment of panels is established. Finally, the model and adjustment analysis method of the active surface antenna in this paper is applied to an 8 m antenna, and satisfactory structural analysis results are obtained, which shows the effectiveness and universality of the method, and provides a reference for the modeling and adjustment analysis of the active surface antenna.
The Spin Measurement of MAXI J0637-430: a Black Hole Candidate with High Disk Density
Authors: Jia Nan , Feng Ye , Song Yu-Jia , Yang Jun , Yuh Jieun , Huang Pei-Jun , Gou Li-Jun 
Published: May 2023

Abstract
The Galactic black hole candidate MAXI J0637-430 was first discovered by MAXI/GSC on 2019 November 2. We study the spectral properties of MAXI J0637-430 by using the archived NuSTAR data and Swift/XRT data. After fitting the eight spectra by using a disk component and a powerlaw component model with absorption, we select the spectra with relatively strong reflection components for detailed X-ray reflection spectroscopy. Using the most state-of-art reflection model, relxillCp, the spectral fitting measures a black hole spin a
* > 0.72 and the inclination angle of the accretion disk i =

46.1

−
5.3

+
4.0

degrees, at a 90% confidence level. In addition, the fitting results show an extreme supersolar iron abundance. Combined with the fitting results of reflection model reflionx_hd, we consider that this unphysical iron abundance may be caused by a very high-density accretion disk (n
e > 2.34 × 1021 cm−3) or a strong Fe Kα emission line. The soft excess is found in the soft state spectral fitting results, which may be an extra free–free heating effect caused by high density of the accretion disk. Finally, we discuss the robustness of black hole spin obtained by X-ray reflection spectroscopy. The result of relatively high spin is self-consistent with broadened Fe Kα line. Iron abundance and disk density have no effect on the spin results.