bluuebunny/crossref_metadata_2025 huggingface dataset:
La paléoneurologie
Authors: Estrems Velazquez Emma , Ferton Evaëlle , Colombo Antony
Published: March 2024

Dans le cadre du Master 2 Sciences du Vivant de l’université EPHE-PSL (cursus IMaGHE, parcours Physiopathologie Intégrative, PPI), des étudiants se sont confrontés à la rédaction d’une Nouvelle scientifique. Selon la spécialisation choisie par les étudiants (Neurosciences ou Cancérologie), l’équipe pédagogique leur a proposé de faire une synthèse d’articles sur deux thématiques : (i) la paléoneurologie, qui permet d’analyser la transformation du cerveau de l’Homme au cours de l’évolution et (ii) la recherche bio-inspirée, qui permet de reproduire ce qui existe dans la nature pour développer des surfaces bactéricides évitant l’usage d’antibiotiques. Organisés en binôme, les étudiants ont rédigé deux Nouvelles qui soulignent l’intérêt des travaux analysés, ainsi que leur originalité. Ils se sont pleinement investis dans cette tâche et ont su faire preuve d’un bel esprit de synthèse. Ils ont apprécié cet exercice nouveau pour eux, mais qui leur a permis d’avoir un aperçu de l’exercice de la publication scientifique, inhérent au métier de chercheur auquel ils se destinent.
Overview of the role of fluorine in the mold fluxes
Authors: Gao Qiang , Feng Liu
Published: March 2024

Fluoride is one of components of the traditional mold flux, but it causes environmental pollution. With the increasing requirement of environmental protection on the metallurgical industry, it is a trend to develop low fluorine or fluorine-free mold fluxes in the future. In recent years, many scholars have researched some low fluorine or fluorine-free mold fluxes. However, because the action mechanism of fluorine in mold flux is not completely clear, the performance of mold fluxes composed of fluorine-substituting components has not reached the effect of fluorine-containing mold fluxes. In view of this, this paper summarizes the effects of fluorine in protective slag from macro and micro aspects: in the study of the macro properties of mold flux, it is generally believed that a certain amount of fluorine plays an important role in adjusting the melting temperature, viscosity and surface tension of mold flux, but its adjusting mechanism is not clear; in terms of microstructure, the structural behavior of fluorine in mold flux is very complicated due to the influence of alkalinity, other components and fluorine content. The microstructure of slag determines the properties of slag. Therefore, the complexity of the structural behavior of fluorine leads to the complexity of the transformation mechanism of the physical properties of mold flux, which makes it impossible to control the properties of mold flux fundamentally and increases the difficulty in selecting the alternative component of fluorine in the process of developing low fluorine or fluorine-free mold flux. Therefore, it is necessary to further study the influence mechanism of fluorine on the structure of mold flux.
Anaplastic Thyroid Carcinoma versus Metastatic SCC: A Diagnostic Dilemma in a Rare Presentation of Post-Radiation Thyroid Swelling
Authors: Rao Vrushab , Zade Bhooshan
Published: March 2024

A 71-year-old male with type 2 diabetes and hypertension was diagnosed with carcinoma of the pyriform fossa in 2019. The biopsy was reported as a moderately differentiated squamous cell carcinoma, and positron emission tomography-computed tomography (PET-CT) scan showed an fluorodeoxyglucose (FDG)-avid lesion in the pyriform fossa and the aryepiglottic fold with few nodes in level II and level III. The paitent was treated with radical chemoradiotherapy. A follow-up PET-CT scan done in 2022 revealed an FDG-avid soft tissue thickening in the left palatine tonsillar region and an uptake in the thyroid that was reported as not significant. A punch biopsy from the tonsillar fossa lesion revealed squamous cell carcinoma. The lesion was treated as a second primary and treated with radiotherapy with curative intent. The patient was complaining of dysphagia, difficulty in breathing, and weight loss around 6 months after treatment that were addressed medically. There was a significant reduction in size and FDG activity of the ill-defined thickening in the left tonsillar region which was seen in the response-assessment PET done 6 months after RT. A heterogeneously enhancing nodules were seen in both lobes of the thyroid in which the largest one measured 3.5 × 3.1 cm seen in the right lobe. The patient underwent a biopsy from the thyroid that revealed a benign thyroid gland infiltrated by clusters and nests of poorly differentiated malignant cells. The histomorphology was suggestive of a poorly differentiated carcinoma, likely anaplastic carcinoma thyroid, or metastasis of the squamous cell carcinoma. Curative treatment was ruled out in this case due to his comorbidities, pulmonary symptoms, and radiation delivered to the neck.
SFM Fetal Therapy Practice Guidelines: Intrauterine Blood Transfusion
Authors: Vikraman Seneesh Kumar , Krishnan Manikandan
Published: March 2024

Despite routine antenatal anti-D prophylaxis with immunoglobulin, Rh alloimmunization and hemolytic disease of the fetus and newborn continue to occur due to a myriad of reasons. Intrauterine intravascular transfusion (IUT) or fetal blood transfusion is a therapeutic prenatal procedure in which specifically prepared and treated unit of donor red blood cells is injected intravascularly into the umbilical vein under ultrasound guidance. Originally introduced in the year 1963, it continues to be the standard treatment for severe fetal anemia. The objective of this guideline is to provide an evidence-based update of IUT for the perinatal healthcare providers.
2.11 Covalent Attachment on a Solid Support
Authors: Franzini R. M.
Published: March 2024

DNA oligonucleotides are polyfunctional molecules, and their various functional groups can interfere with DNA-encoded library synthesis. DNA that is attached to the support used for solid-phase synthesis has functional groups (e.g., exocyclic amines) protected. It is therefore possible to use harsher reaction conditions than would be possible with unprotected DNA, and the use of water-free solvents is also facilitated. For example, amide-bond formation on a solid support tends to be higher yielding than reactions in solution phase.
3.2.2.2 Peptide Nucleic Acid (PNA) Encoded Libraries
Authors: Farrera-Soler L. , Vummidi B. R. , Barluenga S. , Winssinger N.
Published: March 2024

DNA-encoded libraries (DELs) have enabled the screening of dual-pharmacophore libraries but have thus far not allowed the recombination of those fragments after each round of selection. Herein we report the screening of suprabodies, a macromolecular PNA–DNA structure, which allow the shuffling of the library fragments after each round of selection. This technology has been applied to the discovery of new PD-L1 ligands.
On a class of Kirchhoff type logarithmic Schrödinger equations involving the critical or supercritical Sobolev exponent
Authors: Fan Haining , Wang Yongbin , Zhao Lin
Published: March 2024

In this paper, we study a class of Kirchhoff type logarithmic Schrödinger equations involving the critical or supercritical Sobolev exponent. Such problems cannot be studied by applying variational methods in a standard way, because the nonlinearities do not satisfy the Ambrosetti-Rabinowitz condition and change sign. Moreover, the appearance of the logarithmic term makes the associated energy functional lose differentiable in the sense of Gateaux. By analyzing the structure of the Nehari manifold and developing some analysis techniques, the above obstacles are overcome in subtle ways and several existence result are obtained. Furthermore, we investigate the regularity, the monotonicity, and the symmetric properties of the solutions via the iterative technique and the moving plane method.
A versatile laser-based apparatus for time-resolved ARPES with micro-scale spatial resolution
Authors: Dufresne S. K. Y. , Zhdanovich S. , Michiardi M. , Guislain B. G. , Zonno M. , Mazzotti V. , O’Brien L. , Kung S. , Levy G. , Mills A. K. , Boschini F. , Jones D. J. , Damascelli A.
Published: March 2024

We present the development of a versatile apparatus for 6.2 eV laser-based time and angle-resolved photoemission spectroscopy with micrometer spatial resolution (time-resolved μ-ARPES). With a combination of tunable spatial resolution down to ∼11 μm, high energy resolution (∼11 meV), near-transform-limited temporal resolution (∼280 fs), and tunable 1.55 eV pump fluence up to 3 mJ/cm2, this time-resolved μ-ARPES system enables the measurement of ultrafast electron dynamics in exfoliated and inhomogeneous materials. We demonstrate the performance of our system by correlating the spectral broadening of the topological surface state of Bi2Se3 with the spatial dimension of the probe pulse, as well as resolving the spatial inhomogeneity contribution to the observed spectral broadening. Finally, after in situ exfoliation, we performed time-resolved μ-ARPES on a ∼30 μm flake of transition metal dichalcogenide WTe2, thus demonstrating the ability to access ultrafast electron dynamics with momentum resolution on micro-exfoliated materials.
Tuning the coercivity of synthetic antiferromagnetic nanoplatelets with perpendicular anisotropy by varying the Co1−xBx alloy composition
Authors: Li J. , Sijtsma W. , Koopmans B. , Lavrijsen R.
Published: March 2024

Synthetic antiferromagnetic (SAF) nanoplatelets (NPs) with perpendicular magnetic anisotropy based on archetype SAF structures, e.g., Pt/Co/Ru/Co/Pt are of particular interest for torque-related bio-applications due to their large uniaxial magnetic anisotropy. However, when the diameter of the NPs is reduced, the magnetic properties change. For instance, the coercive field increases and starts to vary strongly from NP to NP in a batch due to an increased variation in the reversal probability dominated by local defects. In this study, we investigate how the concentration of boron (B) in Co1−xBx affects the switching properties of NPs, because the addition of B renders the Co layer amorphous and hence introduces more defects. Moreover, it reduces variations in local crystalline anisotropy making the magnetic properties of the NPs more soft. Specifically, we show that the coercivity of the NPs decreases with higher B concentration. This decrease is explained by two mechanisms: (i) the loss of interfacial anisotropy due to less Co–Pt hybridization at the Pt–Co interface and (ii) an increase in the surface’s magnetic domain nucleation site density leading to a narrower distribution of the coercivity of an ensemble of NPs. This understanding will greatly help the field of NP-torque related applications as the spread in applied torque from the NPs to their surroundings can be homogenized.
A practical theoretical model for Ge-like epitaxial diodes: I. The I–V characteristics
Authors: Mircovich Matthew A. , Kouvetakis John , Menéndez José
Published: March 2024

A practical quantitative model is presented to account for the I–V characteristics of pin diodes based on epitaxial Ge-like materials. The model can be used to quantify how the different material properties and recombination mechanisms affect the diode performance. The importance of dislocations, non-passivated defects, and residual intrinsic layer doping in determining the qualitative shape of the I–V curves is discussed in detail. Examples are shown covering literature diodes as well as diodes fabricated with the purpose of validating the theoretical effort.
Fuzzy adaptive PID control for path tracking of field intelligent weeding machine
Authors: Liu Jiaodi , Wu Xiaoman , Quan Longzhe , Xu Hongzhen , Hua Yong
Published: March 2024

In order to reduce the influence of external interference on the intelligent weeder, improve the stability of its path tracking system, enhance its weeding effect, and reduce the rate of seedling injury, the motion steering control of the four-wheeled weeder is studied. The control strategy of fuzzy adaptive proportional integral differential (PID) algorithm is determined by establishing the path tracking mathematical model of the field intelligent weeder; the fuzzy adaptive PID controller is designed with the input average steering angle deviation of the front wheels and the rate of change of the deviation so as to realize the automatic adjustment and optimization of the parameters. We use Simulink to build the control system model and to compare and analyze with the PID controller. The results show that under the action of the step signal, the rise time of the fuzzy adaptive PID and PID control system responses is 2.596 and 4.209 s, respectively; under the action of the impulse, the fuzzy adaptive PID has a significant advantage over the traditional PID control system in terms of the rise time and response time. In addition, this control system has a fast response speed, high adaptability, high anti-interference ability, and superior path tracking ability, which are necessary for improving the accuracy of the field intelligent weeder and reducing the rate of seedling injury.
Segmental dynamics of polystyrene near polymer–polymer interfaces
Authors: Lee Jeongin , Lee Soohyun , Lee Keonchang , Joung Hyeyoung , Choi Seung Kun , Kim Myungwoong , Yang Jaesung , Paeng Keewook
Published: March 2024

This study investigated the segmental dynamics of polymers near polymer–polymer interfaces by probing the rotation of polymer-tethered fluorescent molecules using imaging rotational fluorescence correlation microscopy. Multilayered films were utilized to provide spatial selectivity relative to different polymer–polymer interfaces. In the experimental setup, for the overlayer polymer, polystyrene (PS) was employed and a 15 nm-thick probe-containing layer was placed ≈25 nm apart from different underlayer polymers with glass transition temperatures (Tg) either lower or higher than that of PS. The underlayer of poly-n-butyl methacrylate had 72 K lower Tg than that of PS, whereas polymethyl methacrylate and polysulfone had 22 and 81 K higher Tg, respectively, than that of PS. Two key dynamic features of the glass transition, the non-Arrhenius temperature dependence and stretched relaxation, were examined to study the influence of soft and hard confinements on the segmental dynamics of the overlayer polymer near the polymer–polymer interfaces. Although complications exist in the probing location owing to the diffusion of the polymer-tethered probe during the annealing protocol to consolidate the multilayers, the results suggest that either the segmental dynamics of the polymer near the polymer–polymer interface do not change owing to the soft and hard confinements or the interfacial perturbation is very short ranged.
Nanoscaled magnon transistor based on stimulated three-magnon splitting
Authors: Ge Xu , Verba Roman , Pirro Philipp , Chumak Andrii V. , Wang Qi
Published: March 2024

Magnonics is a rapidly growing field, attracting much attention for its potential applications in data transport and processing. Many individual magnonic devices have been proposed and realized in laboratories. However, an integrated magnonic circuit with several separate magnonic elements has yet not been reported due to the lack of a magnonic amplifier to compensate for transport and processing losses. The magnon transistor reported in Chumak et al. [Nat. Commun. 5, 4700 (2014)] could only achieve a gain of 1.8, which is insufficient in many practical cases. Here, we use the stimulated three-magnon splitting phenomenon to numerically propose a concept of magnon transistor in which the energy of the gate magnons at 14.6 GHz is directly pumped into the energy of the source magnons at 4.2 GHz, thus achieving the gain of 9. The structure is based on the 100 nm wide YIG nano-waveguides, a directional coupler is used to mix the source and gate magnons, and a dual-band magnonic crystal is used to filter out the gate and idler magnons at 10.4 GHz frequency. The magnon transistor preserves the phase of the signal, and the design allows integration into a magnon circuit.
Bounds on geometric wakefields in collimators and step transitions of arbitrary cross sections
Authors: Shaposhnikov L. A. , Baturin S. S.
Published: March 2024

We present the wakefield conformal mapping technique that can be readily applied to the analysis of the radiation generated by an ultra-relativistic particle in the step transition and a collimator. We derive simple analytical expressions for the lower and upper bounds of both longitudinal and transverse wake potentials. We test the derived expressions against well-known formulas in several representative examples. The proposed method can greatly simplify the optimization of collimating sections and can become a useful tool in the shape optimization problems.
High-efficiency and frequency-controllable terahertz pulses driven by two-color relativistic laser pulses
Authors: Wang Y. X. , Shou Y. R. , Cai J. , Han L. Q. , Geng Y. X. , Yu J. Q. , Yan X. Q.
Published: March 2024

The two-color laser filamentation technique serves as a high-quality, laser-based strong-field terahertz source. However, the terahertz energy obtained from this method tends to saturate at high laser intensity, limiting its ability to fully exploit the advantage of the extremely strong field offered by relativistic lasers. Here, we proposed a novel approach based on photon deceleration in plasma to obtain controllable terahertz radiations with two-color relativistic femtosecond laser pulses. In our method, an 800-nm laser drives the plasma wave and controls the plasma density distribution, while the other 10.6-μm laser experiences a strong frequency downshift in the plasma wave and converts to a multi-cycle terahertz pulse, whose central frequency is adjustable by altering the parameters of laser and plasma. The conversion efficiency from the 10.6-μm laser to terahertz radiation can be over 12%, potentially unlocking novel applications in the terahertz domain.
Silver induced chirality controlled spin filtration observed in ss-DNA functionalized with MoS2
Authors: Kumar Abhinandan , Majumder Subrata
Published: March 2024

Chiral molecules can exhibit strong spin–orbit coupling, which can result in a large spin polarization. This is due to the fact that the energy levels of the electrons in a chiral molecule are strongly influenced by the chiral structure of the molecule, which can result in the separation of the energy levels for electrons with different spin orientations. We report a controlled spin-selective transmission of electrons through 20 base-paired poly-cytosine molecules functionalized with MoS2 flakes on ITO glass via the quantum mechanical tunneling effect. A reversion in spin polarization was observed after the silver ions interact with poly-cytosine due to the strong coordination of Ag(I) with cytosine–cytosine (C–C) mismatches, indicating the formation of duplex structural motifs, as confirmed by the circular dichroism spectroscopy at room temperature. Manipulating the spin of an electron through such a small molecule merely controlled by special cations could pave the way for major advances in spin-independent charge transport, advanced bioanalytical system design, and related applications.
An experimental look into efficient quaternary Bi5O7I/Bi(IO3)3/Bi2(IO4) (IO3)3/BiOIO3 photocatalytic composite
Authors: Sabuj Imran Hossain , Jahan Shirin Akter , Khan M. N. I. , Akhtar Umme Sarmeen , Islam Dipa , Bashar Muhammad Shahriar , Das H. N. , Jahan Sharmin , Hossain Quazi Shafayat , Hossain Khandker Saadat , Imran Sazzad M. S. , Ahmed Imtiaz
Published: March 2024

The prototypical toxic dye rhodamine B (RhB) is perhaps one of the most abundant pollutants in industrial wastewater. Its efficient photocatalytic degradation through composite photocatalysts is crucial for environmental remediation. Here, we synthesized quaternary Bi5O7I/Bi(IO3)3/Bi2(IO4)(IO3)3/BiOIO3 bismuth iodate composites through facile hydrothermal and solvothermal methods. The coexistence of multiple bismuth iodate phases was confirmed by x-ray diffraction analysis, room temperature Raman, and Fourier-transform infrared spectroscopy. The desired chemical states of Bi, I, and O inside the composites were confirmed by x-ray photoelectron spectroscopy. Field emission electron microscopy revealed flower-shaped nanosheet morphology for the composite synthesized at 120 °C, whereas randomly shaped nanoparticles with an average size of 80 nm were formed in the composite calcined at 400 °C. High-resolution transmission electron microscopy further corroborated the existence of multiple phases in the composites. The diffuse reflectance spectroscopy confirmed the optical absorption edges of the composites to be located within the visible range of 1.68–3.16 eV. The flower-shaped quaternary bismuth iodate composite demonstrated 100% degradation of RhB dye within 40 min of optical exposure. This quaternary bismuth iodate composite is suitable for solar harvesting-driven toxic dye remediation.
Investigating arc and molten metal transport phenomena in gas metal arc welding with Ar–CO2 gas mixtures using a numerical method
Authors: Cui Xuefei , Chen Ji , Chen Maoai , Wu Chuansong
Published: March 2024

This paper presents a numerical investigation of the transient transport phenomena of the arc and molten metal during gas metal arc welding (GMAW) using shielding gas mixtures ranging from 100% Ar + 0% CO2 to 80% Ar + 20% CO2. The thermophysical parameters of the Ar–CO2 mixtures, considering the presence of metal vapor, were calculated as a function for a temperature range of 1000–30 000 K. The influence of metal vapor content and CO2 proportion on the thermophysical properties of the mixed gas was discussed in detail. As the CO2 content increased from 0 to 20%, the shape of the arc changed from a bell to a cone due to the increase in mass density, specific heat, and thermal conductivity. The maximum arc temperature and velocity decreased with increasing CO2 content, resulting in larger droplets and a lower droplet transfer frequency. Although the change in electrical conductivity did not affect the arc shape, it did influence the arc temperature by altering the distribution of current density. Experiments of droplet transfer and arc behavior were carried out, and the results showed that the simulated droplet size, transfer frequency, and arc temperature distribution agreed well with the experimental values. These findings could serve as a theoretical tool for better understanding the underlying physical mechanisms of the GMAW process using different shielding gases, ultimately aiming to achieve high weld quality.
Extraction of geometric features and analysis of flow mechanism of high loaded compressor airfoils at low Reynolds number
Authors: Zhang Ziyun , Wu Yanhui , Guo Zhengtao , Dong Jiezhong
Published: March 2024

When the aircraft cruising at high altitude, the aerodynamic performance of the compressor sharply decreases due to the enhanced boundary layer separation loss. Therefore, it is of great significance to design the high-performance airfoils suitable for low Reynolds numbers (Re) to improve the aerodynamic performance of compressor. In this paper, numerical simulations were carried out on a high-loaded subsonic compressor cascade V103 at low Re. Meanwhile, a multi-objective optimization of blade profile was performed to get optimal solutions, and data mining techniques were applied to extract valuable design knowledge from the optimal database. The results show that the Pareto-optimal airfoils achieve a maximum reduction of 27.32% in total pressure loss coefficient under design condition and 36.71% under near stall condition. Compared with the original airfoil, the curvature distribution law of the camber line with larger values at both ends and smaller values in the middle is advantageous for the performance of the compressor cascade under design condition. This distribution pattern causes a forward shift for the loading distribution of airfoils, accompanied by an earlier transition onset. Additionally, it reduces adverse pressure gradient at the rear part of suction surface, which suppresses the development and growth of laminar separation bubble and delays the separation of turbulent boundary layer. Under near stall condition, maintaining larger leading edge angle and uniform flow diffusion is beneficial for improving the performance of compressor cascade. This is because the larger leading edge angle reduces incidence angle, while the uniform flow diffusion inhibits a great flow separation.
Vibronic coupling and ultrafast relaxation dynamics in the first five excited singlet electronic states of bithiophene
Authors: Priyanka U. , Paul Aishwarya , Mondal T.
Published: March 2024

The vibronic structure and nuclear dynamics in the first five excited singlet electronic states of bithiophene (2T) are investigated here. Specifically, considerations are given to comprehend the first two structureless and broad electronic absorption bands and the role of nonadiabatic coupling in the excited state relaxation mechanism of 2T in the gas phase. Associated potential energy surfaces (PESs) are established by constructing a model vibronic coupling Hamiltonian using 18 vibrational degrees of freedom and extensive ab initio electronic structure calculations. The topographies of these PESs are critically examined, and multiple conical intersections are established. The nuclear dynamics calculations are performed by propagating wave packets on the coupled electronic manifold. The present theoretical results are in good agreement with the experimental observations. It is found that strong nonadiabatic coupling between the S1–S4 and S1–S5 states along totally symmetric modes is predominantly responsible for the structureless and broad first absorption band, and overlapping S2, S3, S4, and S5 states form the second absorption band. Photorelaxation from the highly excited S5 to the lowest S1 state takes place through a cascade of diabatic population transfers among the S1–S4–S5 electronic manifold within the first ∼100 fs. Totally symmetric C=C stretching, C–S stretching, C–H wagging, ring puckering, and inter-ring bending modes collectively drive such relaxation dynamics.
A numerical and experimental investigation into the mixing mechanism of hydrogen transverse jets into an air swirl flow
Authors: Tan Tieyi , Fan Weijun , Zhang Rongchun
Published: March 2024

As a clean fuel with the advantages of abundant reserves, high calorific value, renewability, and zero carbon emissions, hydrogen has broad application prospects in the fields of energy and power. Moreover, the mixing characteristics of hydrogen and air play a crucial role in determining combustion performance. A novel mixing method of hydrogen transverse jets into an air swirl flow was investigated via numerical and experimental approaches. The Schlieren technique and high-speed photography were employed in the experiments. The effects of various swirl numbers and jet momentum flux ratios on the flow field structure, its transient characteristics, and mixing properties were studied. The research results indicate that the complex vortex structure in the mean flow field is jointly affected by the swirl number and the jet momentum flux ratio. An increase in the jet momentum flux ratio has distinct effects on the flow unsteadiness for different swirl numbers, and there exists a critical value of the jet momentum flux ratio that substantially affects the degree of mixing and a characteristic length suitable for normalization of the axial coordinates when describing the centerline concentration decay. This study provides a reference and basis for further research on combustion in air swirl flows of hydrogen transverse jets.
Ensemble variational method with adaptive covariance inflation for learning neural network-based turbulence models
Authors: Luo Qingyong , Zhang Xin-Lei , He Guowei
Published: March 2024

This work introduces an ensemble variational method with adaptive covariance inflation for learning nonlinear eddy viscosity turbulence models where the Reynolds stress anisotropy is represented with tensor-basis neural networks. The ensemble-based method has emerged as an important alternative to data-driven turbulence modeling due to its merit of non-derivativeness. However, the training accuracy of the ensemble method can be affected by the linearization assumption and sample collapse issue. Given these difficulties, we introduce the hybrid ensemble variational method, which inherits the merits of the ensemble method in non-derivativeness and the variational method in nonlinear analysis. Moreover, a covariance inflation scheme is proposed based on convergence states to alleviate the detrimental effects of sample collapse. The capability of the ensemble variational method in model learning is tested for flows in a square duct, flows over periodic hills, and flows around the S809 airfoil, with increasing complexity in the training data from direct observation to sparse indirect observation. Our results show that the ensemble variational method can learn relatively accurate neural network-based turbulence models in scenarios of small ensemble size and sample variances, compared to the ensemble Kalman method. It highlights the superiority of the ensemble variational method in practical applications, since small ensemble sizes can reduce computational costs, and small sample variance can ensure the training robustness by avoiding nonphysical samples of Reynolds stresses.
Hyperbolic phonon polaritons-induced photonic spin Hall effect in an
α
-MoO3 thin film
Authors: Pian Chui , Sang Tian , Zhang Xianghu , Luo Chen , Ge Zekun , Wang Yueke
Published: March 2024

Photonic spin Hall effect (PSHE) can be achieved by using the patterned structures or metal/dielectric multilayers in the nanophotonic systems; however, the complicated structures of these devices hinder their further applications. Herein, we demonstrate that highly directional PSHE can be realized through the excitation of hyperbolic phonon polaritons (HPPs) in a comparably simple architecture based on an anisotropic α-MoO3 thin film. It is shown that the propagation of the HPP modes of α-MoO3 in the reststrahlen (RS) bands exhibits topological transitions between open hyperbola and closed ellipse in both real space and momentum space (k-space) due to the extreme in-plane anisotropy. Specifically, larger dispersion angle possesses larger figure of merit (FoM), and high k mode of HPPs exhibits robust propagation properties at the maximum dispersion angle. Spin-selected propagation with asymmetric ratio of intensity equal to ±0.94 can be realized by changing the handedness of the dipole emitters. By changing the incident wavelengths of the RS bands, the propagation angle of the HPP modes can be dynamically tuned in wide angular and wavelength ranges.
Mathematical definition of the fine-structure constant: A clue for fundamental couplings in astrophysics
Authors: Reinisch Gilbert
Published: March 2024

Astrophysical tests of the stability—or not—of fundamental couplings (e.g., can the numerical value ∼1/137 of the fine-structure constant α = e2/ℏc vary with astronomical time?) are a very active area of observational research. Using a specific α-free non-relativistic and nonlinear isotropic quantum model compatible with its quantum electrodynamics (QED) counterpart yields the 99% accurate solution α = 7.364 × 10−3 vs its experimental value 7.297 × 10−3. The ∼1% error is due to the deliberate use of mean-field Hartree approximation involving lowest-order QED in the calculations. The present theory has been checked by changing the geometry of the model. Moreover, it fits the mathematical solution of the original nonlinear integro-differential Hartree system by use of a rapidly convergent series of nonlinear eigenstates [G. Reinisch, Phys. Lett. A 498, 129347 (2024)]. These results strongly suggest the mathematical transcendental nature—e.g., like for π or e—of α’s numerical value of ∼1/137 and, hence, its astrophysical as well as its cosmological stability.
Physics-informed neural networks for transonic flow around a cylinder with high Reynolds number
Authors: Ren Xiang , Hu Peng , Su Hua , Zhang Feizhou , Yu Huahua
Published: March 2024

The physics-informed neural network (PINN) method is extended to learn and predict compressible steady-state aerodynamic flows with a high Reynolds number. To better learn the thin boundary layer, the sampling distance function and hard boundary condition are explicitly introduced into the input and output layers of the deep neural network, respectively. A gradient weight factor is considered in the loss function to implement the PINN methods based on the Reynolds averaged Navier–Stokes (RANS) and Euler equations, respectively, denoted as PINN–RANS and PINN–Euler. Taking a transonic flow around a cylinder as an example, these PINN methods are first verified for the ability to learn complex flows and then are applied to predict the global flow based on a part of physical data. When predicting the global flow based on velocity data in local key regions, the PINN–RANS method can always accurately predict the global flow field including the boundary layer and wake, while the PINN–Euler method can accurately predict the inviscid region. When predicting the subsonic and transonic flows under different freestream Mach numbers (Ma∞= 0.3–0.7), the flow fields predicted by both methods avoid the inconsistency with the real physical phenomena of the pure data-driven method. The PINN–RANS method is insufficient in shock identification capabilities. Since the PINN–Euler method does not need the second derivative, the training time of PINN–Euler is only 1/3 times that of PINN–RANS at the same sampling point and deep neural network.
A circle-based interface reconstruction algorithm based on the coupled volume-of-fluid and level set method
Authors: Chen Yujie , Gong Junhua , Lu Wei , Wang Bohong , Sun Dongliang , Yu Bo , Zhang Wei , Tao Wenquan
Published: March 2024

The interface tends to behave as a circular shape under the effect of surface tension in the two-dimensional two-phase fluid flow. In this study, based on the coupled volume-of-fluid and level set (VOSET) method, an accurate circle-based interface reconstruction (CIR) algorithm for structured meshes is proposed, which features a straightforward implementation procedure. A portion of the standard circle is employed to approximate the curve interface, without the need for complex classification, coordinate transformation, and equation transformation. The radius of this circle is computed simply by the curvature and signed distance at the mixed cell center, and the center of this circle is determined using a straightforward dichotomy method under the mass conservation constraints. Results indicate that the coupled VOSET and CIR (VOSET-CIR) method maintains superior computational accuracy in the signed distance, interface curvature, and dynamic interface reconstruction compared to the coupled VOSET and piecewise linear interface calculation (VOSET-PLIC) method, with accuracy improvements ranging from 34% to 1490% across different test cases. Furthermore, the VOSET-CIR method outperforms the efficient least squares volume-of-fluid interface reconstruction (ELVIRA) and PLIC algorithms in reconstructing random circles and surpasses the quadratic spline based interface reconstruction (QUASI) algorithm in reconstructing random squares. In terms of computational efficiency, except for the initial PLIC algorithm, the time costs of the VOSET-CIR method are substantially lower than those of the ELVIRA and QUASI algorithms, as well as the VOSET-PLIC method.
Detecting the large-scale wall-attached structural inclination angles by a machine learning perspective in turbulent boundary layer
Authors: Li Xuebo , Hu Xin , Hu Lan , Li Peng , Liu Wanting
Published: March 2024

With the recent advances in machine learning, strategies based on data can be used to augment wall modeling in the turbulent boundary layer. Combined with the attached eddy hypothesis, the present work applies extreme gradient boosting (XGBoost) to predict the large-scale wall-attached structures at a range of wall-normal locations based on a near-wall reference position (zR+≈4) spanning a Reynolds-number range Reτ∼O(103)−O(105). The input and output signals are selected as the large-scale structures; here, the input signals are set as in the fixed near-wall reference position by a series of streamwise velocity ({X−N,…,X−1,X0,X1,…,XN}), and the output signal Y0 is set directly above X0. Within each dataset, the large-scale wall-attached structures are identified from the prediction modeled by XGBoost between the turbulence in the upper region and at the near-wall reference position, resulting in a successful prediction of the large-scale structures inclination angles. Along the wall-normal offset Δz and streamwise offset Lx (distance between Xi and X0), the slope of the feature importance (represented by contour levels) is exactly equal to the degree of inclination of large-scale structures, indicating the turbulent inner and outer connection inferred by the machine learning input and output interactions perspective. This study shows that there is a great opportunity in machine learning for wall-bounded turbulence modeling by connecting the flow interactions between near-wall and outer regions.
Method of kinetic energy reconstruction from time-of-flight mass spectra
Authors: Ngai A. , Dulitz K. , Hartweg S. , Franz J. C. , Mudrich M. , Stienkemeier F.
Published: March 2024

We present a method for the reconstruction of ion kinetic energy distributions from ion time-of-flight mass spectra through ion trajectory simulations. In particular, this method is applicable to complicated spectrometer geometries with largely anisotropic ion collection efficiencies. A calibration procedure using a single ion mass peak allows the accurate determination of parameters related to the spectrometer calibration, experimental alignment, and instrument response function, which improves the agreement between simulations and experiment. The calibrated simulation is used to generate a set of basis functions for the time-of-flight spectra, which are then used to transform from time-of-flight to kinetic-energy spectra. We demonstrate this reconstruction method on a recent pump–probe experiment by Asmussen et al. [Asmussen et al., Phys. Chem. Chem. Phys., 23, 15138, (2021)] on helium nanodroplets and retrieve time-resolved kinetic-energy-release spectra for the ions from ion time-of-flight spectra.
Investigation of coherent structures in low-speed turbulent boundary layers controlled by AC-DBD plasma actuators
Authors: Liu Zhiqiang , Wang Haoyu , Geng Xi , Cheng Keming
Published: March 2024

The dielectric barrier discharge (DBD) actuator has the advantages of being lightweight, having no moving parts, ease of use, and fast response, and has received widespread attention in flow control applications. Turbulence boundary layer drag reduction is one of many applications of DBD flow control, but the mechanism of DBD actuator turbulence drag reduction needs further investigation. The effect of DBD excitation on the skin-friction drag of a turbulent boundary layer on a flat plate at different flow speeds was investigated experimentally. The change in skin-friction drag was measured using oil film interferometry, and the velocity distribution within the boundary layer was obtained using a particle image velocimetry system. The results showed that under the action of the plasma actuator, the local skin-friction coefficient was measured to decrease by 49%. Through dynamic mode decomposition, plasma actuators can increase the thickness of the low-velocity region in the boundary layer, reduce the intensity of Q2 and Q4 events, and inhibit the development of coherent structures, thereby achieving drag reduction.
Modeling the mosaic structure of bacterial genomes to infer their evolutionary history
Authors: Sheinman Michael , Arndt Peter F. , Massip Florian
Published: March 2024

The chronology and phylogeny of bacterial evolution are difficult to reconstruct due to a scarce fossil record. The analysis of bacterial genomes remains challenging because of large sequence divergence, the plasticity of bacterial genomes due to frequent gene loss, horizontal gene transfer, and differences in selective pressure from one locus to another. Therefore, taking advantage of the rich and rapidly accumulating genomic data requires accurate modeling of genome evolution. An important technical consideration is that loci with high effective mutation rates may diverge beyond the detection limit of the alignment algorithms used, biasing the genome-wide divergence estimates toward smaller divergences. In this article, we propose a novel method to gain insight into bacterial evolution based on statistical properties of genome comparisons. We find that the length distribution of sequence matches is shaped by the effective mutation rates of different loci, by the horizontal transfers, and by the aligner sensitivity. Based on these inputs, we build a model and show that it accounts for the empirically observed distributions, taking the
Enterobacteriaceae
family as an example. Our method allows to distinguish segments of vertical and horizontal origins and to estimate the time divergence and exchange rate between any pair of taxa from genome-wide alignments. Based on the estimated time divergences, we construct a time-calibrated phylogenetic tree to demonstrate the accuracy of the method.
La mue du blaireau de Busterin
Authors: Conti Inès , Lajqi Melita
Published: March 2024

Abstraite

L’Armorial des chevaliers de la Table Ronde, ou Armorial arthurien, est
un recueil du XVe siècle recensant les écus et parfois de petites biographies de personnages littéraires, les
chevaliers de la Table Ronde. Ce texte présente de nombreux cas de diffractio, notamment dans la représentation
iconographique des écus qui diffère parfois de ce que le blasonnement (la description) de l’écu indique dans le texte
accompagnant les armoiries. Le personnage de Busterin le Grand, un chevalier de la Table Ronde presqu’inconnu, voit ainsi
l’animal peint sur son écu varier au fil des manuscrits: tantôt un blaireau, tantôt un rat dans les premières versions de
l’Armorial, le quadrupède se mue ensuite en belette et même en louveteau. Cet article explore les
différentes raisons qui ont pu mener tant les copistes que les enlumineurs à cette confusion, puis aux diverses solutions
auxquelles ils ont ensuite fait recours pour réinterpréter l’animal.
Fabula Aesopici canis
Authors: van Dijk Gert-Jan
Published: March 2024

Fables usually appear either assembled in fable collections or as exempla in other literary
genres. In many cases, especially if the fable is well-known, there is no need to retell the full version of it and a short
allusion will be sufficient for the reader to recognize the fable. This contribution offers a complete analysis of forty-two
allusions to fables in Greek and Latin literature.
ICOS costimulation in combination with CTLA-4 blockade remodels tumor-associated macrophages toward an antitumor phenotype
Authors: Sharma Naveen , Fan Xiaozhou , Atolagbe Oluwatomisin T. , Ge Zhongqi , Dao Kelly N. , Sharma Padmanee , Allison James P.
Published: March 2024

We have previously demonstrated synergy between ICOS costimulation (IVAX; ICOSL-transduced B16-F10 cellular vaccine) and CTLA-4 blockade in antitumor therapy. In this study, we employed CyTOF and single-cell RNA sequencing and observed significant remodeling of the lymphoid and myeloid compartments in combination therapy. Compared with anti-CTLA-4 monotherapy, the combination therapy enriched Th1 CD4 T cells, effector CD8 T cells, and M1-like antitumor proinflammatory macrophages. These macrophages were critical to the therapeutic efficacy of anti-CTLA-4 combined with IVAX or anti-PD-1. Macrophage depletion with clodronate reduced the tumor-infiltrating effector CD4 and CD8 T cells, impairing their antitumor functions. Furthermore, the recruitment and polarization of M1-like macrophages required IFN-γ. Therefore, in this study, we show that there is a positive feedback loop between intratumoral effector T cells and tumor-associated macrophages (TAMs), in which the IFN-γ produced by the T cells polarizes the TAMs into M1-like phenotype, and the TAMs, in turn, reshape the tumor microenvironment to facilitate T cell infiltration, immune function, and tumor rejection.
Secondary roughness effect of surface microstructures on secondary electron emission and multipactor threshold for PTFE-filled and PI-filled single ridge waveguides
Authors: Meng Xiangchen , Xu Yanan , Lian Zhuoxi , Wang Jiyuan , Wang Dan , Qi Kangcheng
Published: March 2024

Secondary electron yield (SEY) is a dominant factor in determining the multipactor threshold. In this study, we analyzed the secondary roughness effect of surface microstructures for plastic dielectric on SEY reduction and multipactor mitigation. A single ridge waveguide (SRW) operating in Ku-band, filled with polytetrafluoroethylene (PTFE) or polyimide (PI), was designed with a dielectric–metal multipactor gap. By employing a femtosecond laser, periodic microstructures were fabricated on PTFE and PI surfaces to suppress SEY. The SEY peak values of PTFE and PI decreased from 2.05 to 1.40 and 1.37 to 1.07 by the porous surface. The surface morphologies and cross-sectional images of the porous PTFE and PI demonstrated the existence of secondary roughness structures. Via simulation, we obtained multipactor thresholds of 8496 W, 12 374 W, and 9397 W for the SRWs filled with untreated PTFE surface, ideal porous surface (without secondary roughness), and real porous surface (with secondary roughness). Similar works were implemented for the PI-filled SRWs, resulting in simulated multipactor thresholds of 7640 W, 11 327 W, and 9433 W. The results indicate that the multipactor effect may not be effectively suppressed under the influence of secondary roughness structures such as plastic velvet and foam. Besides, simulation works indicated that the radio frequency electric field could extract secondary electrons from the microstructures, weakening the mitigation effect of microstructures on multipactor. The impact of surface charging on electron motion was also analyzed by considering energy distribution. It was suggested that the surface microstructures of plastic dielectrics lead to a decrease in the surface charge density and the electrostatic field strength, weakening the self-extinguishing effect and lowering the multipactor threshold. This study provides an in-depth analysis of the effect of secondary roughness on SEY and multipactor for organic dielectrics, which makes significant sense for the further investigation of dielectric multipactor.
Improving hybrid image and structure-based deformable image registration for large internal deformations
Authors: Lorenzo Polo A , Nix M , Thompson C , O’Hara C , Entwisle J , Murray L , Appelt A , Weistrand O , Svensson S
Published: March 2024

Objective. Deformable image registration (DIR) is a widely used technique in radiotherapy. Complex deformations, resulting from large anatomical changes, are a regular challenge. DIR algorithms generally seek a balance between capturing large deformations and preserving a smooth deformation vector field (DVF). We propose a novel structure-based term that can enhance the registration efficacy while ensuring a smooth DVF. Approach. The proposed novel similarity metric for controlling structures was introduced as a new term into a commercially available algorithm. Its performance was compared to the original algorithm using a dataset of 46 patients who received pelvic re-irradiation, many of which exhibited complex deformations. Main results. The mean Dice Similarity Coefficient (DSC) under the improved algorithm was 0.96, 0.94, 0.76, and 0.91 for bladder, rectum, colon, and bone respectively, compared to 0.69, 0.89, 0.62, and 0.88 for the original algorithm. The improvement was more pronounced for complex deformations. Significance. With this work, we have demonstrated that the proposed term is able to improve registration accuracy for complex cases while maintaining realistic deformations.