bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape reconstruction of axisymmetric Taylor bubbles using conductivity probes through a scheme of combined experiment and theory
Authors: Mandal Souvik , Das Prasanta Kumar , Biswas Karabi
Published: March 2024

A simple measurement scheme is proposed to reconstruct the geometry of an axisymmetric void propagating through a conducting liquid using a pair of parallel wire conductivity probes. An experimental study allows for obtaining the time variation of the resistance of the film surrounding the void. Analytical modeling and numerical simulation has been adopted to correlate the resistance between the wire electrodes and the film thickness. Finally, the shape of the void can be estimated by combining the predicted resistance–film thickness relationship and the measured time variation of resistance. For validation, this scheme has been used to reconstruct the shape of a rising Taylor bubble. There is a fair match between the reconstructed shape of the bubble and its photographic image. The probable errors in the measurement scheme have been discussed and assessed mathematically.
Gradient index metamaterials for broadband underwater sound absorption
Authors: Pan Xiao , Fang Xinsheng , Yin Xuewen , Li Yan , Pan Yongdong , Jin Yabin
Published: March 2024

The underwater broadband anechoic coating is highly demanded in acoustic stealth for underwater vehicles. In this work, we propose a gradient index metamaterial for broadband underwater sound absorption, which is further experimentally validated under high pressure conditions. The gradient index metamaterial consisting of radius-varied cavities in rubber allows the sound waves to follow the objective trajectory in a broad band with impedance matching at the interface with water. The viscosity of the materials and the coupling effect among the gradient cavities contribute to broadband sound absorption. The performance of broadband sound absorption from 1 to 10 kHz is validated experimentally, which agrees well with the theoretical and numerical results. We further experimentally demonstrate the sound absorption performance with hydrostatic pressure up to 3 MPa and analyze the mechanism of the sound absorption deviation caused by high pressures. The proposed gradient index metamaterial provides a simple and efficient way to develop underwater broadband acoustic coatings.
Turbulent mean flow prediction in impinging jets using data assimilation methods
Authors: Li Zhiyang , He Chuangxin , Liu Yingzheng
Published: March 2024

In this paper, a data-driven turbulence model is devised based on data assimilation (DA) for predicting impinging jet characteristics for various Reynolds numbers and nozzle-to-plate distances. The shear stress transport (SST) model with Tam–Thies correction is applied. The SST model with the X term makes accurate predictions in the region of wall jet near the overlying stationary fluid but fails to predict the velocity distribution near the wall. The DA-optimized SST model with the X term is used for predicting the impinging jet to minimize the deviation between the model prediction and experimental data. Only the model constants corresponding to the region near the wall are optimized through DA. The model constants at H/D = 2, 3, and 6 are fitted using logarithmic curves with respect to the nozzle-to-plate distance to obtain a universal formulation for predicting the impinging jet under various flow conditions. The model using the fitted model constants, referred to as the SST-H/D model, accurately predicts the mean flow for different nozzle-to-plate distances, nozzle types, and Reynolds numbers.
Modeling of plasmonic and polaritonic effects in photocurrent nanoscopy
Authors: Rikhter A. , Basov D. N. , Fogler M. M.
Published: March 2024

We present a basic framework for modeling collective mode effects in photocurrent measurements performed on two-dimensional materials using nano-optical scanned probes. We consider photothermal, photovoltaic, and bolometric contributions to the photocurrent. We show that any one of these can dominate depending on frequency, temperature, applied bias, and sample geometry. Our model is able to account for periodic spatial oscillations (fringes) of the photocurrent observed near sample edges or inhomogeneities. For the case of a non-absorbing substrate, we find a direct relation between the spectra measured by the photocurrent nanoscopy and its parental scanning technique near-field optical microscopy.
Influence of repulsion on entropy scaling and density scaling of monatomic fluids
Authors: Saric Denis , Bell Ian H. , Guevara-Carrion Gabriela , Vrabec Jadran
Published: March 2024

Entropy scaling is applied to the shear viscosity, self-diffusion coefficient, and thermal conductivity of simple monatomic fluids. An extensive molecular dynamics simulation series is performed to obtain these transport properties and the residual entropy of three potential model classes with variable repulsive exponents: n, 6 Mie (n = 9, 12, 15, and 18), Buckingham’s exponential-six (α = 12, 14, 18, and 30), and Tang–Toennies (αT = 4.051, 4.275, and 4.600). A wide range of liquid and supercritical gas- and liquid-like states is covered with a total of 1120 state points. Comparisons to equations of state, literature data, and transport property correlations are made. Although the absolute transport property values within a given potential model class may strongly depend on the repulsive exponent, it is found that the repulsive steepness plays a negligible role when entropy scaling is applied. Hence, the plus-scaled transport properties of n, 6 Mie, exponential-six, and Tang–Toennies fluids lie basically on one master curve, which closely corresponds with entropy scaling correlations for the Lennard-Jones fluid. This trend is confirmed by literature data of n, 6 Mie, and exponential-six fluids. Furthermore, entropy scaling holds for state points where the Pearson correlation coefficient R is well below 0.9. The condition R > 0.9 for strongly correlating liquids is thus not necessary for the successful application of entropy scaling, pointing out that isomorph theory may be a part of a more general framework that is behind the success of entropy scaling. Density scaling reveals a strong influence of the repulsive exponent on this particular approach.
Fluid–structure interaction for mechanical filament valve mimicking a biological leaflet valve
Authors: Yang Jongmin
Published: March 2024

The biological leaflet valve is a structure found in blood vessels and the cardiac system, designed to maintain a unidirectional flow within the vessels. Two filaments inspired by the biological leaflet are installed inside the channel, and behavior of two filaments is explored by using immersed boundary method. It is observed that the filaments serve as a valve, maintaining the unidirectional flow inside the channel depending on the length (L) and the initial inclined angle (θ) of the filaments. The behavior of the filaments is classified into three modes based on the flow characteristics around the filaments. The pressure and vorticity fields in the vicinity of the filaments are examined to investigate the influence of the surrounding flow on the behavior of filaments. The present study reveals the time sensitivity of valve response, the power consumption, and hydrodynamic efficiency (ηV,steady) of the filament valve, noting that the response speed of the filament valve can vary up to 2.5 times depending on L and θ. The dynamic behavior of the filament valve is analyzed with respect to changes in the properties of the filaments, observing a monotonic decrease in hydrodynamic efficiency with an increase in the bending rigidity (γ) of the filaments. As a result, the present study will be employed as a cornerstone in the development of a mechanical system that emulate biological structures through biomimetics.
Applications of the kinetic theory for a model of a confined quasi-two dimensional granular mixture: Stability analysis and thermal diffusion segregation
Authors: Garzó Vicente , Brito Ricardo , Soto Rodrigo
Published: March 2024

The Boltzmann kinetic theory for a model of a confined quasi-two dimensional granular mixture derived previously [Garzó et al., “Navier–Stokes transport coefficients for a model of a confined quasi-two dimensional granular binary mixture,” Phys. Fluids 33, 023310 (2021)] is considered further to analyze two different problems. First, a linear stability analysis of the hydrodynamic equations with respect to the homogeneous steady state (HSS) is carried out to identify the conditions for stability as functions of the wave vector, the coefficients of restitution, and the parameters of the mixture. The analysis, which is based on the results obtained by solving the Boltzmann equation by means of the Chapman–Enskog method to first order in spatial gradients, takes into account the (nonlinear) dependence of the transport coefficients and the cooling rate on the coefficients of restitution and applies in principle to arbitrary values of the concentration, and the mass and diameter ratios. In contrast to the results obtained in the conventional inelastic hard sphere (IHS) model, the results show that all the hydrodynamic modes are stable so that the HSS is linearly stable with respect to long enough wavelength excitations. On the other hand, this conclusion agrees with previous stability analysis performed in earlier studies for monocomponent granular gases. As a second application, segregation induced by both a thermal gradient and gravity is studied. A segregation criterion based on the dependence of the thermal diffusion factor Λ on the parameter space of the mixture is derived. In the absence of gravity, the results indicate that Λ is always positive, and hence, the larger particles tend to accumulate near the cold plate. However, when gravity is present, our results show the transition between Λ>0 (larger particles tend to move toward the cold plate) to Λ<0 (larger particles tend to move toward the hot plate) by varying the parameters of the system (masses, sizes, composition, and coefficients of restitution). Comparison with previous results derived from the IHS model is carried out.
Free-energy landscape and spinodals for the liquid–liquid transition of the TIP4P/2005 and TIP4P/Ice models of water
Authors: Sciortino Francesco , Gartner Thomas E. , Debenedetti Pablo G.
Published: March 2024

Continued increases in computational power now make it possible to evaluate the free-energy landscape associated with the first-order liquid–liquid transition in realistic models of water for which an accurate estimate of the liquid–liquid critical point exists, and to explore its change with pressure near the coexistence line. We report the results of 50 μs-long NPT umbrella sampling simulations for two realistic models for water, TIP4P/2005 and TIP4P/ice, 3–9 K below their critical temperatures. The free energy profile at different pressures clearly shows the presence of two well-defined free energy basins and makes it possible to identify the liquid–liquid spinodal points, the limits of stability that define the (temperature dependent) pressure range within which two distinct free energy basins exist. The results show that for temperatures less than 10 K below the critical temperature, metastable states are possible across a very limited pressure interval, information that is relevant to the interpretation of experiments probing the metastable phase behavior of deeply supercooled water in the so-called no-man’s land.
The metabolic domestication syndrome of budding yeast
Authors: Tengölics Roland , Szappanos Balázs , Mülleder Michael , Kalapis Dorottya , Grézal Gábor , Sajben Csilla , Agostini Federica , Mokochinski João Benhur , Bálint Balázs , Nagy László G. , Ralser Markus , Papp Balázs
Published: March 2024

Cellular metabolism evolves through changes in the structure and quantitative states of metabolic networks. Here, we explore the evolutionary dynamics of metabolic states by focusing on the collection of metabolite levels, the metabolome, which captures key aspects of cellular physiology. Using a phylogenetic framework, we profiled metabolites in 27 populations of nine budding yeast species, providing a graduated view of metabolic variation across multiple evolutionary time scales. Metabolite levels evolve more rapidly and independently of changes in the metabolic network’s structure, providing complementary information to enzyme repertoire. Although metabolome variation accumulates mainly gradually over time, it is profoundly affected by domestication. We found pervasive signatures of convergent evolution in the metabolomes of independently domesticated clades of
Saccharomyces cerevisiae
. Such recurring metabolite differences between wild and domesticated populations affect a substantial part of the metabolome, including rewiring of the TCA cycle and several amino acids that influence aroma production, likely reflecting adaptation to human niches. Overall, our work reveals previously unrecognized diversity in central metabolism and the pervasive influence of human-driven selection on metabolite levels in yeasts.
Multivalent coiled-coil interactions enable full-scale centrosome assembly and strength
Authors: Rios Manolo U. , Bagnucka Małgorzata A. , Ryder Bryan D. , Ferreira Gomes Beatriz , Familiari Nicole E. , Yaguchi Kan , Amato Matthew , Stachera Weronika E. , Joachimiak Łukasz A. , Woodruff Jeffrey B.
Published: March 2024

The outermost layer of centrosomes, called pericentriolar material (PCM), organizes microtubules for mitotic spindle assembly. The molecular interactions that enable PCM to assemble and resist external forces are poorly understood. Here, we use crosslinking mass spectrometry (XL-MS) to analyze PLK-1-potentiated multimerization of SPD-5, the main PCM scaffold protein in C. elegans. In the unassembled state, SPD-5 exhibits numerous intramolecular crosslinks that are eliminated after phosphorylation by PLK-1. Thus, phosphorylation induces a structural opening of SPD-5 that primes it for assembly. Multimerization of SPD-5 is driven by interactions between multiple dispersed coiled-coil domains. Structural analyses of a phosphorylated region (PReM) in SPD-5 revealed a helical hairpin that dimerizes to form a tetrameric coiled-coil. Mutations within this structure and other interacting regions cause PCM assembly defects that are partly rescued by eliminating microtubule-mediated forces, revealing that PCM assembly and strength are interdependent. We propose that PCM size and strength emerge from specific, multivalent coiled-coil interactions between SPD-5 proteins.
Assessment of reactive species concentrations in plasma-treated water: a pH and conductivity-based method validated by absorption spectroscopy
Authors: Petković J , van de Wege R , Wubs J R , van Rooij O J A P , van Oorschot J J , Huiskamp T , Sobota A
Published: March 2024

To assess the species in plasma-treated water, two methods were compared: calibrated absorption spectroscopy and a method using pH and conductivity to determine the amount of dominant reactive species in the water. A function fitting method was developed for the analysis of the absorption spectra based on solutions with known concentrations. The influence of plasma treatment time on demineralized water and the

NO

x

−

concentration was studied using the two methods; the results in both cases show an almost linear growth with time. The method, utilizing pH and conductivity, shows consistent results with those achieved using UV absorption spectroscopy in considerably less time and in a more cost-efficient manner.
Theoretical prediction of two-dimensional CrSi2N4 as a potential anode material for Na-ion batteries
Authors: Du Boyang , Lou Jianzhong , Wu Minghui , Wu Zhanfei , Liu Guangbei , Li Hu , Huo Shizhe , Liu Lei , Wang Linxia
Published: March 2024

Efficient anode materials are critical for high-performance rechargeable lithium-ion batteries (LIBs) and sodium-ion batteries. This paper systematically investigates the potential of the CrSi2N4 monolayer as anode material for LIBs and sodium-ion batteries by first-principles density functional theory calculations. It was found that CrSi2N4 exhibits outstanding performance in sodium-ion batteries, with a low diffusion energy barrier of 0.10 eV and a high theoretical specific capacity of 490 mAh g−1. Meanwhile, the average open circuit voltage is 0.47 V, comparable to the typical anode materials. In addition, a small lattice constant change of 0.3%–3.1% ensures the cycling stability of CrSi2N4 in sodium-ion batteries. This work suggests a promising candidate anode material for sodium-ion batteries.
Understanding the effect of foreign atoms occupation on the metamagnetic behaviors in MnCoSi-based alloys: taking Pt-doping as an example
Authors: Zhang Zhishuo , Bai Yuqing , Gong Yuanyuan , Chen Bin , Pan Shuang , Guo Yong , Xu Feng
Published: March 2024

Present research on TiNiSi-type MnCoSi-based alloys focuses on finding a suitable doping element to effectively reduce the critical magnetic field (μ
0
H
cri) required to induce a metamagnetic transition. This paper provides a guide to achieve this goal through an experimental investigation of Mn1−x
Pt
x
CoSi and MnCo1−x
Pt
x
Si alloys. In Mn1−x
Pt
x
CoSi, as x increases, μ
0
H
cri at room temperature decreases, while in MnCo1−x
Pt
x
Si, it increases. This phenomenon can be attributed to the fact that larger Pt atoms prefer Co sites over Mn sites, as predicted by our density-functional theory. Consequently, in Mn1−x
Pt
x
CoSi, larger Co atoms are extruded into the Mn atoms chain, increasing the nearest Mn–Mn distance and resulting in a reduced μ
0
H
cri. This finding suggests that transition-metal atoms with more valence electrons preferably occupy the Co site, while those with fewer valence electrons preferably occupy the Mn site. Adhering to this rule, one can easily obtain a low μ
0
H
cri and large magnetostrain under a low magnetic field by selecting a suitable foreign element and chemical formula, as demonstrated by the Mn1−x
Pt
x
CoSi alloy.
Rolling bearing degradation trend prediction based on composite multiscale grey entropy and dynamic particle filter
Authors: Cheng Li , Ma Wensuo , Gao Zuobin
Published: March 2024

High accuracy prediction of degradation trend provides valuable information in establishing reasonable maintenance decision-making with the goal of improving the maintenance efficiency and avoiding sudden downtime. The extraction of degradation features and the prediction algorithm are the key factors in degradation trend prediction. In this work, based on composite multiscale grey entropy (CMGE) and dynamic particle filter (PF), a novel prediction architecture is proposed to improve accuracy under different working conditions. The CMGE is proposed as the degradation feature indicator extracted from rolling bearing vibration signal. The dynamic PF is proposed to predict the degradation trend of rolling bearing. Three rolling bearing accelerated life tests were conducted to evaluate the performance of the proposed method for rolling bearing degradation trend prediction. Experimental results demonstrate CMGE has good monotonicity and weak data length dependence, which can effectively describe the degradation trend of rolling bearing, and the proposed dynamic PF achieves higher prediction accuracy than the traditional PF and GM model, respectively.
Nano-antennas with decoupled transparent leads for optoelectronic studies
Authors: Sommer Melanie , Laible Florian , Braun Kai , Goschurny Thomas , Meixner Alfred J , Fleischer Monika
Published: March 2024

Performing electrical measurements on single plasmonic nanostructures presents a challenging task due to the limitations in contacting the structure without disturbing its optical properties. In this work, we show two ways to overcome this problem by fabricating bow-tie nano-antennas with indium tin oxide leads. Indium tin oxide is transparent in the visible range and electrically conducting, but non-conducting at optical frequencies. The structures are prepared by electron beam lithography. Further definition, such as introducing small gaps, is achieved by focused helium ion beam milling. Dark-field reflection spectroscopy characterization of the dimer antennas shows typical unperturbed plasmonic spectra with multiple resonance peaks from mode hybridization.
Performance improvement of enhancement-mode GaN-based HEMT power devices by employing a vertical gate structure and composite interlayers*
Authors: Sun Zhonghao , Dai Jianxun , Huang Huolin , Sun Nan , Zhang Jiayu , Lei Yun , Li Dawei , Ma Kaiming , Yu Huimin , Liu Yanhong , Huang Hui , Liang Yung C
Published: March 2024

In this work, p-n junction vertical gate (JVG) and polarization junction vertical gate (PVG) structures are for the first time proposed to improve the performance of GaN-based enhancement-mode (E-mode) high electron mobility transistor (HEMT) devices. Compared with the control group featuring the vertical gate structure, a highly improved threshold voltage (V
th) and breakdown voltage (BV) are achieved with the assistance of the extended depletion regions formed by inserting single or composite interlayers. The structure dimensions and physical parameters for device interlayers are optimized by TCAD simulation to adjust the spatial electric field distribution and hence improve the device off-state characteristics. The optimal JVG-HEMT device can reach a V
th of 3.4 V, a low on-state resistance (R
on) of 0.64 mΩ cm2, and a BV of 1245 V, while the PVG-HEMT device exhibits a V
th of 3.7 V, an R
on of 0.65 mΩ cm2, and a BV of 1184 V, which could be further boosted when an additional field plate design is employed. Thus, the figure-of-merit value of JVG- and PVG-HEMT devices rise to 2.4 and 2.2 GW cm−2, respectively, much higher than that for the VG-HEMT control group (1.0 GW cm−2). This work provides a novel technical approach to realize higher-performance E-mode HEMTs.
Active self-powered human motion assist system
Authors: Ren Limin , Zhou Yang , Zhang Xu , Zhang Hengchuan , Tan Yisong
Published: March 2024

Harvesting human energy currently occurs to power wearable devices or monitor human signs, these applications make the energy harvester less applicable to and seldom used for assisting human motion. However, there is a high demand for using such collected energy with the assistance of human motion. This paper presents a novel energy harvester that is designed to collect negative work, assist human motion, and realize self-powering. An active self-powered human motion assist system (HMAS) is developed. The system consists of a human motion assist device, a flexible rack, an electronic circuit module, and a supercapacitor. The HMAS can collect negative work from the human body, provide the user with additional motion assistance, and reduce stamina consumption. A series of experiments verify that HMAS has a high negative work collection power and a high energy conversion efficiency. The average output power is 0.93 W measured by the negative work collection test bed at a simulated knee bend angle of 40° and a frequency of 2 Hz. The energy conversion efficiency is up to 48.2%. Human motion assistance experiments verify that HMAS can provide volunteers with up to 2.57% assisting moment and minimize the metabolic cost of volunteers by 6.07% compared to without wearing HMAS. This research work is proposed to contribute to the development of active self-powered exoskeleton technology. This technology can be practically applied in the fields of rehabilitation therapy, logistics transportation, and military combat.
A machine learning-based method for co-design and optimization of microwave-absorbing/load-bearing multifunctional structures
Authors: Wang Jiawen , Zhou Lilin , Fan Caizhi
Published: March 2024

Simultaneously considering the absorption performance and load-bearing capability is a trend in the design of multifunctional structures. Nevertheless, the collaborative design and optimization involved in this process present a challenging problem. Herein, guided by multifunctionality, a lightweight microwave-absorbing/load-bearing multifunctional structure is intelligently inversely designed based on machine learning. A co-design scheme is developed to address the contradiction between the absorption performance and load-bearing performance. An approach for rapid inverse design of metamaterial absorbers containing multilayered frequency-selective surfaces is proposed. The simulation results obtained using multi-objective optimization based on surrogate models indicate that the optimized multifunctional structure achieves more than 90% absorption in the frequency range of 2.5 GHz–18.0 GHz and simultaneously exhibits superior load-bearing performance with an out-of-plane Young’s modulus of 334.8 MPa and an out-of-plane compressive strength of 4.95 MPa, demonstrating the effectiveness of the co-design scheme. Finally, the experimental results are analysed. This study provides a reference for co-design and multi-objective optimization of similar multifunctional structures.
Localising two sub-diffraction emitters in 3D using quantum correlation microscopy
Authors: Li Shuo , Li Wenchao , Sun Qiang , Moran Bill , Brown Timothy C , Gibson Brant C , Greentree Andrew D
Published: March 2024

The localisation of fluorophores is an important aspect of determining the biological function of cellular systems. Quantum correlation microscopy (QCM) is a promising technique for providing diffraction unlimited emitter localisation that can be used with either confocal or widefield modalities. However, so far, QCM has not been applied to three dimensional localisation problems. Here we show that QCM provides diffraction-unlimited three-dimensional localisation for two emitters within a single diffraction-limited spot. By introducing a two-stage maximum likelihood estimator, our modelling shows that the localisation precision scales as

1

/

t

where t is the total detection time. Diffraction unlimited localisation is achieved using both intensity and photon correlation from Hanbury Brown and Twiss measurements at as few as four measurement locations. We also compare the results of (MC) simulations with the Cramér–Rao lower bound.
Quantum non-Markovianity of a qubit in presence of state dependent bath
Authors: Rashid Mehboob , Qadir Lone Muzaffar , Ganai Prince A
Published: March 2024

In the field of quantum information theory, the intersection of the complex dynamics related to non-Markovianity and information is a crucial frontier. Non-Markovian effects, which take memory and temporal correlations into account, challenge conventional wisdom in the fields of quantum biology, metrology, cryptography, and communication. In this work, we analyze the non-Markovian dynamics of a dephasing model in presence of initial system-bath (SB) correlations. These SB correlations are generated via projective measurements on a predefined equilibrium state. Using the non-Markovian measures based on trace distance and quantum Fisher information, it is shown that these correlations have significant impact in the non-Markovian regime at high temperatures while it does not play any role in the Markovian case. Furthermore, it is shown that the oscillatory behaviour of the decoherence function does not always show non-Markovian behaviour.
The auxiliary equation approach for solving reaction-diffusion equations
Authors: Păuna Alina-Maria
Published: March 2024

The paper concerns the auxiliary equation method and proposes an approach for finding the most general nonlinear term that can generalize a nonlinear differential equation, so that it keeps solutions expressed in terms of the same auxiliary equation. More precisely we will consider the second order reaction-diffusion equations and we will find the most general nolinear term of this type of equations, for which the solutions can be expressed in terms of the Riccati equation. The procedure is exemplified on Fitzhugh-Nagumo, Dodd-Bullough-Mikhailov, and Klein-Gordon models, seen as reaction-diffusion equations.
Two soliton interaction of Zakharov–Mikhailov spinor models
Authors: Gerdjikov V. S. , Kostadinov B. , Mishev S.
Published: March 2024

We outline the spectral properties of their Lax operators for the Zakharov-Mikhailov spinor model (ZMm) and construct their fundamental analytic solutions (FAS). Using the dressing Zakahrov-Shabat method we derive the dressing factors for the one-soliton u
1(z
1, Φ1) and u
2(z
1
, z
2, Φ1, Φ2) for the two-soliton solutions. Next we calculate the asymptotics of the dressing factors of u
1(z
1, Φ1) for z
1 → ±∞. Inserting them into u
2(z
1
, z
2, Φ1, Φ2) we find that for z
1
→ ±∞ u
2(z
1
, z
2, Φ1, Φ2) goes into one-soliton solutions but with shifted center of mass and shifted phase. Thus we conclude that the 2-soliton interactions of ZMm are purely elastic and are characterized by the above mentioned shifts.
Achieving High Efficiency: Resource sharing techniques in artificial neural networks for resource-constrained devices
Authors: Gorbounov Y , Chen H
Published: March 2024

Artificial neural networks emerged in the early 1940s as a connectionist approach to modeling the behavior of interconnected living nerve cells within the intricate cognitive framework of the brain. Over the years, this idea has undergone unprecedented proliferation of ever-expanding application areas, accompanied by an exponential surge in the mathematical formalism employed. This prodigious growth poses severe demands on computational hardware infrastructure. The current research suggests a novel approach for optimizing artificial neural network architectures using resource-sharing techniques. It is discussed the concept of merging context-switching and time-division multiplexing in building a single-neuron artificial neural network with the aid of an FPGA device. This would benefit the significant reduction of hardware resources and the possibility of creating small yet very efficient artificial neural networks without deteriorating the dynamical system performance.
Nonlinear black hole scalarization in multi-scalar Gauss-Bonnet gravity
Authors: Staykov Kalin V. , Doneva Daniela D.
Published: March 2024

A process called nonlinear scalarization was recently demonstrated to exist for black holes in scalar-Gauss-Bonnet gravity. Contrary to the standard spontaneous scalarization, the nonlinear scalarization is a process which allows for a Schwarzschild black hole and a scalarized black hole, both linearly stable, to coexist. We extend the search for black holes with nonlinear scalarization in the case of multi-scalar Gauss-Bonnet gravity – a class of theories which allow for hairy compact objects with vanishing scalar charge, hence, there are no constraints from the binary pulsar observations. We demonstrate numerically the existence of such black hole solutions with nonlinear scalarization in the multi-scalar Gauss-Bonnet theories with exponential coupling function which is of fourth leading order in the scalar field.
Experimental investigation on the surface quality of WEDM machined 20MnCr5 steel for gear application
Authors: Vijayakumar N , Chandradass J
Published: March 2024

This experimental study investigates the Wire-cut Electrical Discharge Machining (WEDM) of 20MnCr5 steel, a low alloy steel grade material which is intended for the production of gears, shafts and other parts which need high surface hardness and wear resistance. WEDM is a crucial manufacturing process for producing gears, shafts, spindles, and various mechanical components. The investigation focuses on three key performance parameters: profile error, material removal rate (MRR), and surface roughness (SR), employing five WEDM parameters—wire feed (Wf), wire tension (Wt), servo voltage (SV), discharge arc-off time (Toff), and arc-on time (Ton) - by employing the Taguchi L27 orthogonal array. The study reveals that, in comparison to arc-on time and servo voltage, wire feed rate and tension have a lesser impact. Higher arc-on time and servo voltage result in increased profile error, while reduced wire tension values elevate surface roughness. Recast layer formation has been explored under different WEDM input parameters, revealing its dependence on arc-on time, voltage, wire tension, and feed rate. Higher voltage leads to uneven surfaces with larger globules and deep craters, contributing to a thicker recast layer at higher arc-on time and servo voltage.
Homotopy lifting maps on Hochschild cohomology and connections to deformation of algebras using reduction systems
Authors: Oke Tolulope
Published: March 2024

We describe the Gerstenhaber bracket structure on Hochschild cohomology of Koszul quiver algebras in terms of homotopy lifting maps. There is a projective bimodule resolution of Koszul quiver algebras that admits a comultiplicative structure. Introducing new scalars, we describe homotopy lifting maps associated to Hochschild cocycles using the comultiplicative structure. We show that the scalars can be described by some recurrence relations and we give several examples where these scalars appear in the literature. In particular, for a member of a family of quiver algebras, we describe Hochschild 2-cocycles and their associated homotopy lifting maps and determine the Maurer-Cartan elements of the quiver algebra in two ways: (i) by the use of homotopy lifting maps and (ii) by the use of a combinatorial star product that arises from the deformation of algebras using reduction systems.
Centers and automorphisms of PI quantum matrix algebras
Authors: Gaddis Jason , Lamkin Thomas
Published: March 2024

We study PI quantum matrix algebras and their automorphisms using the noncommutative discriminant. In the multi-parameter case at

n
=
2

n=2

, we show that all automorphisms are graded when the center is a polynomial ring. In the single-parameter case, we determine a presentation of the center and show that the automorphism group is not graded, though we are able to describe certain families of automorphisms in this case, as well as those of certain subalgebras.
A retrospective analysis of COVID-19 dynamics in Mexico and Peru: Studying hypothetical changes in the contact rate
Authors: Acuña-Zegarra M. , Santana-Cibrian Mario , Hernandez-Vela Carlos , Mena Ramsés , Velasco-Hernández Jorge
Published: March 2024

The COVID-19 pandemic has left many open questions for decision-makers. One of them is knowing the counter-factual effect that the implementation of different mitigation strategies to the ones actually used could have caused. This knowledge would allow to contemplate alternative strategies to deal with future infectious disease emergency. Motivated by the above, we model the observed COVID-19 dynamics for Mexico and Peru and explore the impact of implementing hypothetical stricter mitigation strategies on key days of civic, religious, or political character, that could alter contact and transmission intensities. We explore this impact through hypothetical contact rate reductions during the first year of the pandemic but at different times: i) near its beginning, ii) at the beginning of the second outbreak, and iii) end of the year. The effects of interventions are different for Mexico and Peru, but, in general, they do reduce the cumulative number of cases and deaths. Nonetheless, this study underlines the fact that the time and duration of interventions are important factors to obtain better reductions in prevalence. We also provide evidence that key calendar days are good change points for contact rates and, therefore, may be useful to define strategic time periods for effective interventions, particularly in countries with low testing and lack of contact tracing. We recreate different outbreaks of the COVID-19 disease dynamics in Mexico and Peru and explore the impact of hypothetical interventions that further reduce the contact rate.
Discursion on a paper of R. E. Mickens and J. E. Wilkins, Jr.
Authors: Herron Isom
Published: March 2024

The heat equation and a nonlinear counterpart predict the temperature at the end of a semi-infinite rod, when the heat flux is specified there. Both equations have reductions to ordinary differential equations which simplify their solutions. For the nonlinear equation, the problem becomes

y

(
z
)

=
y

(
z
)

2

−
z
y

(
z
)

y

′

(
z
)
,

y \left ( z\right ) =y\left ( z\right ) ^{2}-zy\left ( z\right ) y^{\prime }(z),

 

y

′

(
0
)

=
−

3

,
y

(
∞
)

=
0

\ y^{\prime }\left ( 0\right ) =-\sqrt {3},y\left ( \infty \right ) =0

on

[
0
,
∞
)

[0,\infty )

. A variational approximation to the initial value

y

(
0
)

y\left ( 0\right )

of the nonlinear boundary value problem was found by employing an integral constraint suggested by the equation itself. The approximation is more accurate for the initial value than that of Mickens and Wilkins but misses their pointwise description of the solution.
Modeling T-cell repertoire response to a viral infection with short immunity
Authors: Naumova Elena , Yassai Maryam , Gorski Jack , Naumov Yuri
Published: March 2024

At the molecular level, we observed that immune response to the influenza virus becomes diverse upon repeated viral exposures and can be presented as a fractal self-similar system. We proposed an adaptation of the Markov chain process to model the dynamics of memory T-cell repertoire considering typical experimental conditions. We derived model-inspired characteristics to quantify repertoires’ temporal stability and detected significant age-specific differences. These differences indicate that transitional probabilities are subject to change as the immune system evolves and could potentially serve as a marker of immunosenescence. We concluded that for infection with short immune memory, a boost via periodic vaccinations or direct exposures is critical for sustaining diverse immune responses.
Using unity approximations to construct nonstandard finite difference schemes for Bernoulli differential equations
Authors: Basu Treena , Buckmire Ron , Coovadia Zaheer , Diaz Mayra , Iniguez David , Scott Alexandra
Published: March 2024

We explore the use of nonstandard finite difference (NSFD) methods in numerically approximating solutions to Bernoulli ordinary differential equations (BDEs) with constant coefficients. Specifically, we investigate the numerical performance of NSFD schemes that deploy unity approximations. A unity approximation can be created by introducing and replacing the number

1
1

with an approximation using non-local terms of the form

2

x

k
+
1

x

k
+
1

+

x
k

\displaystyle \frac {2x_{k+1}}{x_{k+1}+x_k}

where

x
k

≈

x

k
+
1

x_k \approx x_{k+1}

on a discrete grid. Our NSFD schemes derived from unity approximations produce solutions that compare favorably with numerical solutions obtained using standard finite difference (SFD) schemes. The NSFD schemes presented here demonstrate their utility by possessing one or more of the following properties: enhanced accuracy, preserving positivity, and maintaining dynamic consistency (i.e., other essential qualities of the ODE pertaining to its domain and the asymptotic properties of the equilibria such as stability).
Discussion on “The central role of the identifying assumption in population size estimation” by Serge Aleshin-Guendel, Mauricio Sadinle, and Jon Wakefield
Authors: King Ruth , McCrea Rachel , Overstall Antony
Published: March 2024

In this discussion response, we consider some practical implications of the authors’ consideration of the no-highest-order interaction (NHOI) model for multiple systems estimation, which permits the authors to derive the explicit (albeit untestable) identifying assumption related to the unobserved (or missing) individuals. In particular, we discuss several aspects, from the standard process of model selection to potential poor predictive performance due to over-fitting and the implications of data reduction. We discuss these aspects in relation to the case study presented by the authors relating to the number of civilian casualties within the Kosovo war, and conduct further preliminary simulations to investigate these issues further. The results suggest that the NHOI models considered, despite having a potentially useful theoretical result in relation to the underlying identifying assumption, may perform poorly in practice.
Rejoinder to the discussion on “The central role of the identifying assumption in population size estimation”
Authors: Aleshin-Guendel Serge , Sadinle Mauricio , Wakefield Jon
Published: March 2024

We organize the discussants’ major comments into the following categories: sensitivity analyses, zero counts, model selection, the marginal no-highest-order interaction (NHOI) assumption, and the usefulness of our proposed framework.
The Arabidopsis Information Resource in 2024
Authors: Reiser Leonore , Bakker Erica , Subramaniam Sabarinath , Chen Xingguo , Sawant Swapnil , Khosa Kartik , Prithvi Trilok , Berardini Tanya Z
Published: March 2024

Since 1999, The Arabidopsis Information Resource (www.arabidopsis.org) has been curating data about the Arabidopsis thaliana genome. Its primary focus is integrating experimental gene function information from the peer-reviewed literature and codifying it as controlled vocabulary annotations. Our goal is to produce a “gold standard” functional annotation set that reflects the current state of knowledge about the Arabidopsis genome. At the same time, the resource serves as a nexus for community-based collaborations aimed at improving data quality, access, and reuse. For the past decade, our work has been made possible by subscriptions from our global user base. This update covers our ongoing biocuration work, some of our modernization efforts that contribute to the first major infrastructure overhaul since 2011, the introduction of JBrowse2, and the resource's role in community activities such as organizing the structural reannotation of the genome. For gene function assessment, we used gene ontology annotations as a metric to evaluate: (1) what is currently known about Arabidopsis gene function and (2) the set of “unknown” genes. Currently, 74% of the proteome has been annotated to at least one gene ontology term. Of those loci, half have experimental support for at least one of the following aspects: molecular function, biological process, or cellular component. Our work sheds light on the genes for which we have not yet identified any published experimental data and have no functional annotation. Drawing attention to these unknown genes highlights knowledge gaps and potential sources of novel discoveries.
On seismic gradiometric wave equation inversion for density
Authors: Faber Marthe , Curtis Andrew
Published: March 2024

Material density remains poorly constrained in seismic imaging problems, yet knowledge of density would provide important insight into physical material properties for the interpretation of subsurface structures. We test the sensitivity to subsurface density contrasts of spatial and temporal gradients of seismic ambient noise wavefields, using wave equation inversion (WEI), a form of seismic gradiometry. Synthetic results for 3-D acoustic media suggest that it is possible to estimate relative density structure with WEI by using a full acoustic formulation for wave propagation and gradiometry. We show that imposing a constant density assumption on the medium can be detrimental to subsurface seismic velocity images. By contrast, the full acoustic formulation allows us to estimate density as an additional material parameter, as well as to improve phase velocity estimates. In 3-D elastic media, severe approximations in the governing wave physics are necessary in order to invert for density using only an array of receivers on the Earth's free surface. It is then not straightforward to isolate the comparatively weak density signal from the influence of phase velocity using gradiometric WEI. However, by using receivers both at the surface and in the shallow subsurface we show that it is possible to estimate density using fully elastic volumetric WEI.
Haplotype-resolved T2T reference genomes for wild and domesticated accessions shed new insights into the domestication of jujube
Authors: Li Kun , Chen Ruihong , Abudoukayoumu Ayimaiti , Wei Qian , Ma Zhibo , Wang Zhengyang , Hao Qing , Huang Jian
Published: March 2024

Chinese jujube (Ziziphus jujuba Mill.) is one of the most important deciduous tree fruits in China, with substantial economic and nutritional value. Jujube was domesticated from its wild progenitor, wild jujube (Z. jujuba var. spinosa), and both have high medicinal value. Here we report the 767.81- and 759.24-Mb haplotype-resolved assemblies of a dry-eating ‘Junzao’ jujube (JZ) and a wild jujube accession (SZ), using a combination of multiple sequencing strategies. Each assembly yielded two complete haplotype-resolved genomes at the telomere-to-telomere (T2T) level, and ~81.60 and 69.07 Mb of structural variations were found between the two haplotypes within JZ and SZ, respectively. Comparative genomic analysis revealed a large inversion on each of chromosomes 3 and 4 between JZ and SZ, and numerous genes were affected by structural variations, some of which were associated with starch and sucrose metabolism. A large-scale population analysis of 672 accessions revealed that wild jujube originated from the lower reaches of the Yellow River and was initially domesticated at local sites. It spread widely and was then independently domesticated at the Shanxi–Shaanxi Gorge of the middle Yellow River. In addition, we identified some new selection signals regions on genomes, which are involved in the tissue development, pollination, and other aspects of jujube tree morphology and fertilization domestication. In conclusion, our study provides high-quality reference genomes of jujube and wild jujube and new insights into the domestication history of jujube.
Hydro-acoustic classification and abundance estimation of mesopelagic fish in deep scattering layers (DSL) of the Indian Ocean
Authors: Chacate Osvaldo Ernesto , Coetzee Janet Claire , Axelsen Bjørn Erik
Published: March 2024

Deep scattering layers (DSL) in oligotrophic systems are typically comprised of a variety of coexisting organisms, including fish, zooplankton, jellyfish, and squid, and hence there is uncertainty about the proportion of the acoustic backscatter in these layers that can be attributed to mesopelagic fish. Here, acoustic targets were classified using a multi-frequency acoustic classification algorithm based on data collected in the Indian Ocean at 18, 38, 70, and 120 kHz during three acoustic surveys in 2018. Frequency-dependent backscattering strength information (∆Sv) was extracted from acoustic data that coincided with trawl hauls dominated by mesopelagic fish. Five ∆Sv frequency pairs were used to separate the acoustic backscattering into three broad scattering categories, i.e. mesopelagic fish, crustacean-like/tunicates, and squids/others. Results indicated that the DSL is highly diverse and dominated by mesopelagic fish, with average densities at a regional scale ranging from 12.0 (±10.9) to 26.0 (±21.7) g m−2, and proportions of the acoustic backscatter attributed to mesopelagic fish ranging from 0.5 to 0.7. These estimates are generally lower than previously estimated for other regions of the Indian Ocean. The situation may well be similar elsewhere, particularly in oligotrophic systems, with potential ramifications for global mesopelagic fish biomass estimates.