bluuebunny/crossref_metadata_2025 huggingface dataset:
Calculation of Pressure Pulsations in the Flow Part of the First Stage of an Axial Turbine in the Rotor-Stator Interaction Zone
Authors: Timushev S. F. , Kondratov A. V.
Published: November 2021

A serious problem in the development of reusable liquid-propellant rocket engines (LRE) is the provision of a high resource and reliability of gas turbines of turbopump, which supply fuel to the combustion chamber. This problem can be solved by reducing the level of pressure pulsations in the interaction zone of the turbine rotor-stator and dynamic loads acting on the working and stator blades. In this regard, a useful tool is the method of numerical simulation of the unsteady turbulent flow of a compressible gas in the turbine flow path with the determination of the amplitude of pressure pulsations in the axial clearance between the stator and rotor blade cascades. The calculation model includes the Navier-Stokes equations and equation of energy. Density, thermal conductivity and diffusion coefficient are linearly dependent on temperature and concentration. Calculations were performed on different meshes, proving the mesh convergence of the method upon reaching the quasi-stationary regime. The calculation results show that the pressure pulsations vary greatly with the axial clearance, and the main frequency of the pressure pulsations in the spectrum is the blade passing frequency. The frequency of dynamic moment acting on the blade also coincides with the indicated frequency.
Improvement of carbon segregation in cast bloom and heredity in hot-rolled bar
Authors: Zhang Mengyun , Bao Yanping , Zhao Lihua , Li Xin
Published: November 2021

In this study, the effect of mechanical soft reduction on carbon segregation in the continuous casting of 300 × 400 mm 42CrMo alloy structural steel blooms was comparatively investigated by adjusting the casting speed, which was systematically optimized through numerical simulation. When the casting speed is 0.60 m · min−1, during the soft reduction process, the central solidification structure of the bloom becomes dense, and carbon segregation is improved. Moreover, the distribution of carbon in the samples before and after rolling was analyzed. Combined with the soft reduction process, the uniformity of carbon across the cross section of the bloom /bar distinctly improved for casting speeds of 0.50 m · min−1, 0.55 m · min−1 and 0.60 m · min−1, this was predominantly reflected in the core areas. The effective segregation length proportion of the bloom and rolled bar is approximately 40%. This phenomenon fully verifies the heredity characteristics of the elements in the rolling process.
Determinant of Prenatal Diagnostic Testing among Women with Increased Risk of Fetal Aneuploidy and Genetic Disorders
Authors: Morgan Tamandra , Tan Catherine D. , Della-Torre Micaela , Jackson-Bey Tia , DiGiovanni Laura , Enakpene Christopher A.
Published: November 2021

Objective This study aimed to assess factors that influence patients' decisions in accepting prenatal diagnostic testing following genetic counseling for increased risk of fetal aneuploidy.

Methods This is a retrospective cohort study of women at increased risk of fetal aneuploidy and genetic disorders who had genetic counseling from January 2012 to December 2016 at a single academic center. Demographics, indications for genetic counseling, and rates of diagnostic testing were collected and compared between those who accepted diagnostic testing and those who chose cell free DNA. The variables were analyzed using Chi-square, Fisher's exact test, and multiple logistic regression.

Result Of the 2,373 pregnant women who underwent genetic counseling for increased risk of fetal aneuploidy and genetic disorders during the study period, 321 women had diagnostic testing (13.5%). Women at 35 years and older accepted diagnostic testing more than women younger than 35 years (20.7 vs. 11.5%, p < 0.001). Asian women accepted diagnostic testing at 27.7% more than white, non-Hispanic Black, and Hispanic women at 18.0, 12.1, and 11.7%, respectively, p = 0.002. Number of indications for genetic counseling influenced the likelihood of accepting diagnostic testing. Women with one indication had 11.5% acceptance of diagnostic testing, and with two and three indications, it was 17.0 and 29.2%, respectively. The commonest indication for diagnostic testing was cystic hygroma (risk ratio [RR] = 7.5, 95% confidence interval [CI]: 3.12–8.76 p < 0.001). The relative risk of diagnostic testing for fetuses with shortened long bones, femur and humerus, thickened nuchal fold, echogenic bowel, single umbilical artery, and increased nuchal translucency were 4.0, 3.3, 3.1, 2.7, and 2.7, respectively. Abnormal serum analyte alone was associated with less acceptance of diagnostic testing (RR = 0.8, 95% CI: 0.7–0.96, p = 0.017).

Conclusion Age, race, ethnicity, and cumulative number of indications for genetic counseling influenced acceptance of diagnostic testing in at-risk women of fetal aneuploidy and genetic disorders.

Key Points
The Trend of Urinary N Terminal Probrain Natriuretic Peptide in Extremely Low Birth Weight Infants during the Neonatal Period
Authors: Khan Safdar S. , Bada Henrietta S. , Torres Maritza , Almodovar Melvin , Hanna Mina
Published: November 2021

Objective N-terminal probrain natriuretic peptide (NT-proBNP) is a biomarker of interest in many cardiopulmonary diseases in extremely low birth weight (ELBW) Infants. However, there is a gap in knowledge about the trend of ELBW infant's urinary NT-proBNP during the neonatal period.

Aim To determine the trend of urinary NT-proBNP during the first 4 weeks of life of an ELBW infant.

Study Design We analyzed prospectively enrolled 87 ELBW infants. Urinary NT-proBNP to creatinine ratios were measured on days 1 to 7, 14, and 28 of life. We plotted each study point's means to determine the trend of urinary NT-proBNP over the entire neonatal period. Data were analyzed using the Friedman analysis of variance for comparative analysis of study points.

Results Urinary NT-proBNP/creatinine ratios were significantly elevated on days 1 to 7 (mean 2,452, ± 1,518) than day 14 (mean 747, ± 176), and day 28 (mean 149, ± 54), p = 0.001. Overall, urinary NT-proBNP levels were highest during days 1 to 3 (mean 3,232, ± 1,255) and lowest on day 28 (mean 149, ± 54).

Conclusion Urinary NT-proBNP levels are higher during the first week in ELBW infants with a downward trend during the neonatal period, the lowest values at 4 weeks postnatal age. More studies are required to determine the clinical utility of this trend during and beyond the neonatal period.

Key Points
From Genetics to Epigenetics: Top 4 Aspects for Improved SARS-CoV-2 Vaccine Designs as Paradigmatic Examples
Authors: Kanduc Darja
Published: November 2021

This literature review described the genetic and biochemical factors that may have been overlooked in the formulation of vaccines and that most likely underlie possible issues with mass vaccination.
Clinical Features of Aberrations Chromosome 22q: A Pilot Study
Authors: Atli Emine Ikbal , Atli Engin , Yalcintepe Sinem , Demir Selma , Mail Cisem , Eker Damla , Ozen Yasemin , Gurkan Hakan
Published: November 2021

Objective A significant number of genetic variations have been identified in chromosome 22, using molecular genetic techniques. Various genomic disorders on chromosome 22, including cat's eye syndrome caused by extra copies of the proximal region of the 22q chromosome, are now well-defined. Our aim in the study was to show phenotypic variability associated with rearrangements of the 22q chromosomal region.

Methods We focused our study on clinical aspects of these disorders, including genetic testing, genotype-phenotype correlation, and potential treatments. A total of 998 patients were referred for genetic analysis (Karyotyping, MLPA, array-CGH) during January 2015 to February 2020 because of intellectual deficiency, behavior issues, and/or multiple congenital abnormalities in several genetics departments. Informed consent was obtained from all the patients and/or their parents.

Results 22q11.21 or 22q13.33 microdeletions and 22q11.22-q11.23 microduplication were identified in 31 patients out of referrals. The 22q aberrations were detected in 31/998 patients, giving a prevalence of 3.1%. In this study, 18 patients with 22q11.2 (LCR22A-H) deletion, three patients with 22q13.31 deletion, 9 patients with 22q11.2 duplication and one patient with 22q13.31 duplication were identified. We report on the clinical and molecular characterization of 31 individuals with distal deletions and duplications of chromosome 22q.

Conclusions The current study demonstrated in the largest postnatal case series reporting the whole spectrum of atypical phenotypic and genotypic variations at 22q. We believe that when all the phenotypic differences are taken into account, various anomalies including developmental delay and intellectual disability might be considered as an indication to search for aberrations of 22q along with congenital heart diseases.
Toward low-temperature processing of lead zirconate titanate thin films: Advances, strategies, and applications
Authors: Song Longfei , Glinsek Sebastjan , Defay Emmanuel
Published: November 2021

Lead zirconate titanate (PZT) thin films stand for a prominent technological brick in the field of microsystems. The recent improvements of their manufacturability combined with excellent piezoelectric properties have enabled their introduction in industrial clean rooms all around the world. These films require annealing temperatures beyond 600 °C to crystallize in the desired perovskite phase, which exhibits outstanding piezoelectric coefficients. This temperature requirement forbids large application fields such as flexible electronics, smart glass but also system-on-chip approaches. Decreasing the annealing temperature of PZT films would therefore spread further their potential usage to other applications. The purpose of this paper is to provide the reader with a comprehensive review of the different techniques available in the literature to process piezoelectric PZT thin films at temperatures compatible with semiconductors (450 °C), smart glass (400 °C), or flexible electronics (350 °C). We first present the typical ferroelectric and piezoelectric properties of PZT films. The different deposition techniques and growth mechanisms of these films are then reviewed with a focus on thermodynamics. Then, all the low temperature processes are detailed, such as seeding effects, the modification of deposition parameters in vapor-phase deposition, special annealing technologies assisted with UV, lasers, flash lamps, microwave radiations or high-pressure, a focus on the hydrothermal method, and finally what is called solution chemistry design with notably combustion synthesis. Transfer processing is also detailed, as an alternative way to this low temperature approach. An outlook of future applications enabled by these innovative techniques is finally provided.
Rate equations model for multiple magnetic mirrors in various thermodynamic scenarios
Authors: Miller Tal , Be'ery Ilan , Barth Ido
Published: November 2021

Axial particle loss is one of the main challenges for fusion aimed, linear magnetic mirror plasma configurations. One way to mitigate this disadvantage and increase the confinement time is to use a multiple mirrors setup. The idea is to reduce the outgoing flux by collisions in the outer magnetic cells. Here, we develop a semi-kinetic rate equation model for the ions' density dynamics, including scattering within the magnetic cell and the transmission between neighboring cells. The dominant parameter is the ions' mean free path, which depends on the temperature and density in each cell. The steady-state flow is studied analytically and numerically for three thermodynamic scenarios: isothermal plasma, adiabatic expansion, and constant diffusion. It is found that the confinement time varies about fivefold over the different scenarios, where the adiabatic cooling is the best confining scenario.
Fractional Kirchhoff-type equation with singular potential and critical exponent
Authors: Liu Senli , Chen Haibo
Published: November 2021

In this paper, we study a class of critical fractional Kirchhoff-type equations with singular potential. With a range of parameters, we propose several existence results. Our work extends the results of Li and Su [Z. Angew. Math. Phys. 66, 3147 (2015)].
Tempered linear and non-linear time series models and their application to heavy-tailed solar flare data
Authors: Susan Kabala Jinu , Burnecki Krzysztof , Sabzikar Farzad
Published: November 2021

In this paper, we introduce two tempered linear and non-linear time series models, namely, an autoregressive tempered fractionally integrated moving average (ARTFIMA) with α-stable noise and ARTFIMA with generalized autoregressive conditional heteroskedasticity (GARCH) noise (ARTFIMA-GARCH). We provide estimation procedures for the processes and explain the connection between ARTFIMA and their tempered continuous-time counterparts. Next, we demonstrate an application of the processes to modeling of heavy-tailed data from solar flare soft x-ray emissions. To this end, we study the solar flare data during a period of solar minimum, which occurred most recently in July, August, and September 2017. We use a two-state hidden Markov model to classify the data into two states (lower and higher activity) and to extract stationary trajectories. We do an end-to-end analysis and modeling of the solar flare data using both ARTFIMA and ARTFIMA-GARCH models and their non-tempered counterparts. We show through visual inspection and statistical tests that the ARTFIMA and ARTFIMA-GARCH models describe the data better than the ARFIMA and ARFIMA-GARCH, especially in the second state, which justifies that tempered processes can serve as the state-of-the-art approach to model signals originating from a power-law source with long memory effects.
Large-eddy-simulation-based analysis of Reynolds-stress budgets for a round impinging jet
Authors: Colombié A. , Laroche E. , Chedevergne F. , Manceau R. , Duchaine F. , Gicquel L.
Published: November 2021

A large-eddy simulation is used to assess the Reynolds-stress budgets of a round impinging jet in the context of a second-moment closure of turbulence. The present work focuses on the stagnation region where no data are available in the literature except in the wall vicinity. Inside the stagnation region, it is shown that the pressure terms are dominant in the budgets. They balance the Reynolds-stress production and the convective fluxes. A visualization of this equilibrium through a specific indicator reveals that impingement effects extend to less than one nozzle diameter in the wall-normal direction and to about one diameter radially. This study underlines the role of the pressure diffusion term that conveys energy to the wall, balancing the high production rates (both positive or negative). Finally, the failure of turbulence models is explained by the absence of appropriate modeling of this pressure diffusion term leading to excessive Reynolds-stress values inside the impingement region.
Helium nanodroplet infrared spectroscopy of oxazole-(water)n (n = 1,2) clusters
Authors: Roy Tarun Kumar , Chatterjee Kuntal , Khatri Jai , Schwaab Gerhard , Havenith Martina
Published: November 2021

The mass-selective infrared (IR) spectra of oxazole-(D2O)n≤2 complexes embedded in helium droplets are recorded in the spectral range of 2565–2800 cm−1. The experimental IR spectra are assigned by comparing with quantum chemical calculations at the MP2/6-311++G(d,p) level of theory. Here, we show that in the case of the 1:1 oxazole-D2O dimer, the water molecule binds to the N atom of the heterocyclic ring via a N⋯DO hydrogen bond (H-bond). However, in the oxazole-(D2O)2 trimer, the water dimer forms N⋯DO and CH⋯O H-bonds with the N atom and adjacent CH group, respectively, leading to the formation of a seven-membered ring. We compare these results with those of our recently reported isoxazole-(water)n≤2 complexes to demonstrate differences in the hydration motif of these two structural isomers.
Partial synchronization in the second-order Kuramoto model: An auxiliary system method
Authors: Barabash Nikita V. , Belykh Vladimir N. , Osipov Grigory V. , Belykh Igor V.
Published: November 2021

Partial synchronization emerges in an oscillator network when the network splits into clusters of coherent and incoherent oscillators. Here, we analyze the stability of partial synchronization in the second-order finite-dimensional Kuramoto model of heterogeneous oscillators with inertia. Toward this goal, we develop an auxiliary system method that is based on the analysis of a two-dimensional piecewise-smooth system whose trajectories govern oscillating dynamics of phase differences between oscillators in the coherent cluster. Through a qualitative bifurcation analysis of the auxiliary system, we derive explicit bounds that relate the maximum natural frequency mismatch, inertia, and the network size that can support stable partial synchronization. In particular, we predict threshold-like stability loss of partial synchronization caused by increasing inertia. Our auxiliary system method is potentially applicable to cluster synchronization with multiple coherent clusters and more complex network topology.
Spatiotemporal evolution of resistance state in simulated memristive networks
Authors: Di Francesco F. , Sanca G. A. , Quinteros C. P.
Published: November 2021

Originally studied for their suitability to store information compactly, memristive networks are now being analyzed as implementations of neuromorphic circuits. An extremely high number of elements is, thus, mandatory. To surpass the limited achievable connectivity—due to the featuring size—exploiting self-assemblies has been proposed as an alternative, in turn posing new challenges. In an attempt for offering insight on what to expect when characterizing the collective electrical response of switching assemblies, in this work, networks of memristive elements are simulated. Collective electrical behavior and maps of resistance states are characterized upon different electrical stimuli. By comparing the response of homogeneous and heterogeneous networks, we delineate differences that might be experimentally observed when the number of memristive units is scaled up and disorder arises as an inevitable feature.
Research on the influence of cathode surface topography on spark discharge
Authors: Wang Dangshu , Yi Jiaan , Lou Jianan , Deng Xuan , Liu Shulin , Wang Xinxia , Dong Zhen , Yang Yaqiang
Published: November 2021

To obtain the relation between spark discharges and the topography of electrode surfaces, some models, such as a micro-initial model of cone and spherical head cylinder, generated from the scanning of a scanning electron microscope are introduced. Based on the principles of energy conservation and thermal equilibrium, the second-order non-homogeneous differential equation is established. The relationships between the temperature of the cathode surface and the distance from the top of micro-protrusions, the cone angle, and the radius of the ball head are derived from a set of second-order non-homogeneous differential equations. When introduced electron emission theory, the main emission type at the initial stage of the discharge is electron field emission. As the discharge progresses, the Joule heat generated by the emission current will cause thermionic emission. During this progress, the emission current density gradually increases. When the temperature of the cathode surface reaches the melting point of the cathode metal, the current density will increase sharply. Observed from the discharge, the temperature of the cathode surface is inversely proportional to the cone angle and the radius of the ball head maintains a gradually decreasing slope. It is proportional to micro-protrusions maintaining a gradually increasing slope. When the cone angle is less than 12° and the radius of the ball head is less than 0.04 µm, the temperature of the cathode surface changes more dramatically. Through this study, a further understanding of factors that affect the density of cathode current emission can be obtained, which is of great significance to improve the capacity of cathode emission.
Cluster synchronization of networks via a canonical transformation for simultaneous block diagonalization of matrices
Authors: Panahi Shirin , Klickstein Isaac , Sorrentino Francesco
Published: November 2021

We study cluster synchronization of networks and propose a canonical transformation for simultaneous block diagonalization of matrices that we use to analyze the stability of the cluster synchronous solution. Our approach has several advantages as it allows us to: (1) decouple the stability problem into subproblems of minimal dimensionality while preserving physically meaningful information, (2) study stability of both orbital and equitable partitions of the network nodes, and (3) obtain a parameterization of the problem in a small number of parameters. For the last point, we show how the canonical transformation decouples the problem into blocks that preserve key physical properties of the original system. We also apply our proposed algorithm to analyze several real networks of interest, and we find that it runs faster than alternative algorithms from the literature.
Hole superconductivity xOr hot hydride superconductivity
Authors: Hirsch J. E.
Published: November 2021

Under the spell of BCS-electron–phonon theory [M. Tinkham, Introduction to Superconductivity, 2nd ed. (McGraw Hill, New York, 1996)], during the last 6 years experimentalists have purportedly discovered a plethora of high temperature conventional superconductors among pressurized hydrides [Pickard et al., Ann. Rev. Condens. Matter Phys. 11, 57 (2020) and R. F. Service, Science 373, 954 (2021)], and theorists have been busy predicting and explaining those findings [Lv et al., Matter Radiat. Extremes 5, 068101 (2020); Flores-Livas et al., Phys. Rep. 856, 1 (2020); and Boeri et al., J. Phys. Condens. Matter. (to be published)]. The alternative theory of hole superconductivity (see https://jorge.physics.ucsd.edu/hole.html for a list of references) predicts instead that no superconductivity can exist in these materials. In this Tutorial, I will first argue that, unclouded by the prejudice of BCS’s validity, the existing experimental evidence for superconductivity in pressurized hydrides does not withstand scrutiny. Once it is established that superconductivity in pressurized hydrides is a myth and not a reality, the claim to validity of BCS-electron–phonon theory as a descriptor of superconductivity of real materials will be forever shattered, and an alternative theory will become imperative. I will explain the fundamentals of the theory of hole superconductivity, developed over the past 32 years [see https://jorge.physics.ucsd.edu/hole.html and J. E. Hirsch, Phys. Lett. A 134, 451 (1989)], and why it is compelling. Crucially, it explains the Meissner effect, that I argue the conventional theory does not. It applies to all superconducting materials and provides guidelines in the search for high temperature superconductors that are very different from those provided by BCS-electron–phonon theory. Light elements are predicted to be irrelevant to warm superconductivity because according to this theory the electron–phonon interaction plays no role in superconductivity.
Initial perturbation matters: Implications of geometry-dependent universal Kardar–Parisi–Zhang statistics for spatiotemporal chaos
Authors: Fukai Yohsuke T. , Takeuchi Kazumasa A.
Published: November 2021

Infinitesimal perturbations in various systems showing spatiotemporal chaos (STC) evolve following the power laws of the Kardar–Parisi–Zhang (KPZ) universality class. While universal properties beyond the power-law exponents, such as distributions and correlations and their geometry dependence, are established for random growth and related KPZ systems, the validity of these findings to deterministic chaotic perturbations is unknown. Here, we fill this gap between stochastic KPZ systems and deterministic STC perturbations by conducting extensive simulations of a prototypical STC system, namely, the logistic coupled map lattice. We show that the perturbation interfaces, defined by the logarithm of the modulus of the perturbation vector components, exhibit the universal, geometry-dependent statistical laws of the KPZ class despite the deterministic nature of STC. We demonstrate that KPZ statistics for three established geometries arise for different initial profiles of the perturbation, namely, point (local), uniform, and “pseudo-stationary” initial perturbations, the last being the statistically stationary state of KPZ interfaces given independently of the Lyapunov vector. This geometry dependence lasts until the KPZ correlation length becomes comparable to the system size. Thereafter, perturbation vectors converge to the unique Lyapunov vector, showing characteristic meandering, coalescence, and annihilation of borders of piece-wise regions that remain different from the Lyapunov vector. Our work implies that the KPZ universality for stochastic systems generally characterizes deterministic STC perturbations, providing new insights for STC, such as the universal dependence on initial perturbation and beyond.
Suspension principle and verification of 6/4 pole bearingless switched reluctance motor with permanent magnets in its stator yoke
Authors: Yang YiFei , Wang RenZhong , Zhu XiaoBin
Published: November 2021

In order to overcome the disadvantages of 12/8 pole bearingless switched reluctance motors (BSRMs), such as high commutation frequency, more stator windings, and more power devices, a 6/4 pole BSRM with half the commutation frequency and number of windings is studied. The structure characteristics and operation characteristics of the 6/4 pole BSRM are investigated through modeling, simulation, and prototype experiment, and the main performance indices, such as suspension force, inductance performance, and air-gap flux density, are evaluated to reveal the levitation control mechanism of the 6/4 pole BSRM with permanent magnets in its stator yoke. The motor can suspend stably in the radial direction, and the correctness and feasibility of the theoretical analysis are verified.
Direct numerical simulation of deformable rising bubbles at low Reynolds numbers
Authors: Zhang Lingxin , Peng Kai , Shao Xueming , Deng Jian
Published: November 2021

We investigate numerically the dynamics of freely rising gas bubbles driven by buoyancy at low Reynolds numbers, focusing on two distinct characteristics: the clustering morphology and the probability density functions (p.d.f.) of the velocity fluctuations for bubbles. A modified Volume-of-fluid (VOF) method is implemented in our direct numerical simulations to circumvent the nonphysical coalescence between bubbles. Four values of the gas fraction are studied: 5%, 10%, 15%, and 20%. The Eötvös number and the Galileo number are fixed at Eo = 2 and Ga = 855, respectively. For a single rising bubble, the Reynolds number according to the terminal velocity and the bubble diameter is around 27, displaying an ellipsoidal shape. For a swarm of bubbles, both irregular and regular clustering configurations are observed in our numerical simulations as we vary the gas fraction, which can only be realized at high Reynolds numbers in the previous experiments due to the low gas fraction limit. Moreover, we find that the p.d.f.s for bubble velocity fluctuations exhibit distinctly different behavior from the high Reynolds number experiments. The horizontal components for these p.d.f.s approach Gaussian distributions only when the gas fraction is high, i.e., α=15% and 20%. It suggests that the strong bubble–bubble interaction through their flow wakes is an efficient way to trigger the flow into turbulent states.
Wake evolution and vortex structure characteristics of flow over two tandem semi-circular cylinders with flat surfaces facing each other
Authors: Zhu Hongjun , Wang Shuo , Zhou Tongming , Shao Ze
Published: November 2021

This paper reports the results of a numerical investigation into the flow over two tandem semi-circular cylinders with flat surfaces facing each other and the associated wake flow characteristics. The effect of spacing ratio (L/D, L is the in-line spacing between two flat surfaces and D is the diameter of cylinders) ranging from 1 to 16 is examined in a low Reynolds number range of Re = 60–180. Five flow patterns are identified including the over-shoot, continuous reattachment, alternate reattachment, quasi-co-shedding, and co-shedding regimes. The difference between quasi-co-shedding and co-shedding regimes depends on the origin of the vortices shed from the downstream cylinder. Unlike the vortices generated due to the roll-up of shear layers detached from both upstream and downstream cylinders in the co-shedding regime, the vortices shed from the downstream cylinder come from upstream instead of the roll-up of shear layers for the quasi-co-shedding regime. The wake flow characteristics are discussed in terms of the vortex formation and shedding, wake structure and evolution, boundary layer separation and shear layer development, the occurrence of secondary vortex street, and the associated migrating vortex modes. The variations of hydrodynamic coefficients and Strouhal number are associated with the flow regime transition. When the alternate reattachment and quasi-co-shedding regimes emerge, a small pair of peaks of the root-mean-squared streamwise flow velocity (u*rms) fixedly occurs at the two corners of the downstream cylinder, illustrating the strong velocity fluctuation caused by vortices impingement and the secondary separation. Three types of vortex street are observed in the wake, where the secondary vortex street region is further divided into three parts in terms of the vortex structure, including S + P (a single vortex and a pair of vortices are formed per cycle in the secondary vortex street), P (a pair of vortices is formed per cycle in the secondary vortex street), and 2S (two vortices in opposite directions are formed per cycle in the secondary vortex street) modes. Two partitions in Re–L/D map (Re and L/D as the vertical and horizontal ordinates, respectively) are proposed in this work for the flow regime as well as the vortex street.
Induced nonlinear phase shift of spin waves for magnonic logic circuits
Authors: Ustinov Alexey B. , Kuznetsov Nikolai A. , Haponchyk Roman V. , Lähderanta Erkki , Goto Taichi , Inoue Mitsuteru
Published: November 2021

An induced nonlinear phase shift of spin waves excited in an yttrium iron garnet film waveguide has been studied. Experiments were performed with two microwave magnonic signals, being operating and pumping waves, co-propagated at different frequencies. The results show that a nonlinear phase shift up to 180° for the low-power operating wave is induced when increasing the pump-wave power. A theory describing the induced nonlinear phase shift is developed taking into account four-wave parametric coupling and nonlinear damping of two waves. The observed phenomenon paves the way to elaborate different types of nonlinear magnonic logic circuits.
Preferential and persistent impact of acute HIV-1 infection on CD4+iNKT cells in colonic mucosa
Authors: Paquin-Proulx Dominic , Lal Kerri G. , Phuang-Ngern Yuwadee , Creegan Matthew , Tokarev Andrey , Suhkumvittaya Suchada , Alrubayyi Aljawharah , Kroon Eugène , Pinyakorn Suteeraporn , Slike Bonnie M. , Bolton Diane L. , Krebs Shelly J. , Eller Leigh Anne , Sajjaweerawan Chayada , Pagliuzza Amélie , Chomont Nicolas , Rerknimitr Rungsun , Chomchey Nitiya , Phanuphak Nittaya , de Souza Mark S. , Michael Nelson L. , Robb Merlin L. , Ananworanich Jintanat , Sandberg Johan K. , Eller Michael A. , Schuetz Alexandra ,   RV217,   RV254/SEARCH010,   RV304/SEARCH013,   Study Groups
Published: November 2021

Significance

Evidence suggests that HIV-1 disease progression is determined in the early stages of infection. Here, preinfection invariant natural killer T (iNKT) cell levels were predictive of the peak viral load during acute HIV-1 infection (AHI). Furthermore, iNKT cells were preferentially lost in AHI. This was particularly striking in the colonic mucosa, where iNKT cells were depleted more profoundly than conventional CD4+T cells. The initiation of antiretroviral therapy during AHI-prevented iNKT cell dysregulation in peripheral blood but not in the colonic mucosa. Overall, our results support a model in which iNKT cells are early and preferential targets for HIV-1 infection during AHI.
Combining pressure and electrochemistry to synthesize superhydrides
Authors: Guan Pin-Wen , Hemley Russell J. , Viswanathan Venkatasubramanian
Published: November 2021

Significance

Superhydrides are a materials system where near–room-temperature superconductivity has been achieved but only at very high (megabar) pressures. This work proposes an approach that combines pressure and electrochemistry to stabilize superhydrides at moderate pressures. Through a computational study of the palladium–hydrogen system, we construct electrochemical phase diagrams and show that electrochemically synthesizing superhydrides may be possible when combined with moderate pressures. We generalize this to other binary metal superhydrides of interest for superconductivity, including La, Y, and Mg hydrides.
Programmable droplet manipulation and wetting with soft magnetic carpets
Authors: Demirörs Ahmet F. , Aykut Sümeyye , Ganzeboom Sophia , Meier Yuki A. , Poloni Erik
Published: November 2021

Significance

A set of magnetically responsive, soft hairs, which form a soft magnetic carpet, can be infused with a liquid to achieve switchable wetting. Applying a pattern of magnetic field results in a reconfigurable wetting pattern on the soft magnetic carpet. Combining this switchable wetting with a travelling magnetic field wave can allow us to spatially manipulate droplets. The efficiency of the droplet manipulation depends on the size and the contact angle of the droplet, which allows a pathway to sort and separate different droplets. Temporal and spatial control over multiple droplets allows us to conduct droplet reactions, which has a potential to be used for automated analytical testing and screening.
Anáforas reflexivas y doblado de clíticos en lenguas romances
Authors: Verdecchia Matías
Published: November 2021

In this paper I analyze the distribution of the reflexive constructionse+a sí mismoin Romance (e.g.,‘Juan se peinó a sí mismo’). I propose that these structures are transitive. Concretely, I argue that in these cases the reflexive anaphor is the internal argument of the predicate, and that the obligatory presence of the cliticseis due to the general phenomenon of clitic doubling with pronominal objects. I show that this approach can account for some asymmetries between these constructions and simplese-reflexives regarding expletive insertion in French, proxy readings, comparative constructions, association with focus, and case distribution in causatives.
Measuring informativity
Authors: Degaetano-Ortlieb Stefania
Published: November 2021

By applying data-driven methods based on information theory, this study adds to previous work on the
development of the scientific register by measuring the informativity of alternative phrasal structures shown to be involved
in change in language use in 20th-century Scientific English. The analysis based on data-driven periodization shows compounds
to be distinctive grammatical structures from the 1920s onwards in Proceedings A of the Royal Society of
London. Compounds not only increase in frequency, but also show higher informativity than their less dense
prepositional counterparts. Results also show that the lower the informativity of particular items, the more alternative, more
informationally dense options might be favoured (e.g., of-phrases vs. compounds) – striving for
communicative efficiency thus being one force shaping the scientific register.
Baby universes and worldline field theories
Authors: Casali Eduardo , Marolf Donald , Maxfield Henry , Rangamani Mukund
Published: November 2021

The quantum gravity path integral involves a sum over topologies that invites comparisons to worldsheet string theory and to Feynman diagrams of quantum field theory. However, the latter are naturally associated with the non-abelian algebra of quantum fields, while the former has been argued to define an abelian algebra of superselected observables associated with partition-function-like quantities at an asymptotic boundary. We resolve this apparent tension by pointing out a variety of discrete choices that must be made in constructing a Hilbert space from such path integrals, and arguing that the natural choices for quantum gravity differ from those used to construct QFTs. We focus on one-dimensional models of quantum gravity in order to make direct comparisons with worldline QFT. We also restrict attention to models in which worldlines do not split apart or join together.
Sound speed uncertainty in acousto-electric tomography
Authors: Jensen Bjørn Christian Skov , Knudsen Kim
Published: November 2021

The goal in acousto-electric tomography is to reconstruct an image of the unknown electric conductivity inside an object from boundary measurements of electrostatic currents and voltages collected while the object is penetrated by propagating ultrasound waves. This problem is a coupled-physics inverse problem. Accurate knowledge of the propagating ultrasound wave is usually assumed and required, but in practice tracking the propagating wave is hard due to inexact knowledge of the interior acoustic properties of the object. In this work, we model uncertainty in the sound speed of the acoustic wave, and formulate a suitable reconstruction method for the interior power density and conductivity. We also establish theoretical error bounds, and show that the suggested approach can be understood as a regularization strategy for the inverse problem. Finally, we numerically simulate the sound speed variations from a numerical breast tissue model, and computationally explore the effect of using an inaccurate sound speed on the error in reconstructions. Our results show that with reasonable uncertainty in the sound speed reliable reconstruction is still possible.
Y2O3:Eu and the Mössbauer isomer shift coefficient of Eu compounds from ab-initio simulations
Authors: Davydov Arkadiy , Sanna Antonio , Concas Giorgio
Published: November 2021

We report on a full potential density functional theory characterization of Y2O3 upon Eu doping on the two inequivalent crystallographic sites 24d and 8b. We analyze local structural relaxation, electronic properties and the relative stability of the two sites. The simulations are used to extract the contact charge density at the Eu nucleus. Then we construct the experimental isomer shift (IS) versus contact charge density calibration curve, by considering an ample set of Eu compounds: EuF3, EuO, EuF2, EuS, EuSe, EuTe, EuPd3 and the Eu metal. The, expected, linear dependence has a slope of α = 0.054 mm s−1 Å−
3, which corresponds to nuclear expansion parameter ΔR/R = 6.0 × 10−5. α allows to obtain an unbiased and accurate estimation of the IS for any Eu compound. We test this approach on two mixed-valence compounds Eu3S4 and Eu2SiN3, and use it to predict the Y2O3:Eu IS with the result +1.04 mm s−1 at the 24d site and +1.00 mm s−1 at the 8b site.
External tuning of topological phase transitions induced by interaction driven mass renormalization
Authors: Jansen Thies , Brinkman Alexander
Published: November 2021

Electron–electron interactions can be useful for realizing new nontrivial topological phases of matter. Here, we show by means of a tight-binding model and mean field theory how electron–electron interactions can lead to a topological phase transition. By externally adding or removing electrons from the system a band inversion between two bands with different parity is induced. This leads to a topological nontrivial phase if spin–orbit coupling is present. Besides the toy-model illustrating this mechanism, we also propose SmB6 as a possible playground for experimentally realizing a topological phase transition by external tuning.
The generation of switchable polarized currents in nodal ring semimetals using high-frequency periodic driving
Authors: Fu Pei-Hao , Lv Qianqian , Yu Xiang-Long , Liu Jun-Feng , Wu Jiansheng
Published: November 2021

A nodal ring semimetal (NRSM) can be driven to a spin-polarized NRSM or a spin-polarized Weyl semimetal (WSM) by a high-frequency electromagnetic field. We investigate the conditions in realizing these phases and propose a switchable spin-polarized currents generator based on periodically driven NRSMs. Both bulk and surface polarized currents are investigated. The polarization of bulk current is sensitive to the amplitude of the driving field and robust against the direction and polarization of the driving, the opaqueness of the lead–device interface and the misalignment between the nodal ring and the interface, which provides sufficient flexibility in manipulating the devices. Similar switchable polarized surface currents are also expected, which is contributed by the Fermi arc surface state associated with the WSM phases. The generation of polarized currents and the polarization switching effect offer opportunities to design periodic driving controlled topological spintronics devices based on NRSMs.
Improving dose calculation accuracy in preclinical radiation experiments using multi-energy element resolved cone-beam CT
Authors: Huang Yanqi , Hu Xiaoyu , Zhong Yuncheng , Lai Youfang , Shen Chenyang , Jia Xun
Published: November 2021

Objective. Cone-beam CT (CBCT) in modern pre-clinical small-animal radiation research platforms provides volumetric images for image guidance and experiment planning purposes. In this work, we implemented multi-energy element-resolved (MEER) CBCT using three scans with different kVps on a SmART platform (Precision x-ray Inc.) to determine images of relative electron density (rED) and elemental composition (EC) that are needed for Monte Carlo-based radiation dose calculation. Approach. We performed comprehensive calibration tasks to achieve sufficient accuracy for this quantitative imaging purpose. For geometry calibration, we scanned a ball bearing phantom and used an analytical method together with an optimization approach to derive gantry angle specific geometry parameters. Intensity calibration and correction included the corrections for detector lag, glare, and beam hardening. The corrected CBCT projection images acquired at 30, 40, and 60 kVp in multiple scans were used to reconstruct CBCT images using the Feldkamp–Davis–Kress reconstruction algorithm. After that, an optimization problem was solved to determine images of rED and EC. We demonstrated the effectiveness of our CBCT calibration steps by showing improvements in image quality and successful material decomposition in cases with a small animal CT calibration phantom and a plastinated mouse phantom. Main results. It was found that artifacts induced by geometry inaccuracy, detector lag, glare, and beam hardening were visually reduced. CT number mean errors were reduced from 19% to 5%. In the CT calibration phantom case, median errors in H, O, and Ca fractions for all the inserts were below 1%, 2%, and 4% respectively, and median error in rED was less than 5%. Compared to the standard approach deriving material type and rED via CT number conversion, our approach improved Monte Carlo simulation-based dose calculation accuracy in bone regions. Mean dose error was reduced from 47.5% to 10.9%. Significance. The MEER-CBCT implemented on an existing CBCT system of a small animal irradiation platform achieved accurate material decomposition and significantly improved Monte Carlo dose calculation accuracy.
A binary-encounter-Bethe approach to compute electron-impact partial ionization cross sections of plasma relevant molecules such as hexamethyldisiloxane and silane
Authors: Arora Ajay Kumar , Gupta Krishna Kumar , Goswami Kanupriya , Bharadvaja Anand , Baluja Kasturi Lal
Published: November 2021

Electron-impact partial ionization cross sections (PICS) of fragments are reported from threshold to 5 keV energy using a modified form of the binary-encounter-Bethe model. Scaling using mass spectrometry data ensures that the cross sections are of the correct order of magnitude. The total ionization cross sections (TICS) were obtained by summing the PICS of fragments. The PICS and TICS obtained from the modified-binary-encounter-Bethe model are in excellent agreement with the experimental and theoretical results. The molecules investigated are hexamethyldisiloxane and silane. Both these species are highly relevant in plasma processing where the PICS are required to be over an extended energy range. The study of the ionization process in conjunction with mass spectrometry provides correct estimates of the contribution that each charged ion makes to the TICS. The present approach can be easily extended to any species provided that ion energetics and relative cation abundances data are available.
Physics of biomolecular recognition and conformational dynamics
Authors: Chu Wen-Ting , Yan Zhiqiang , Chu Xiakun , Zheng Xiliang , Liu Zuojia , Xu Li , Zhang Kun , Wang Jin
Published: November 2021

Biomolecular recognition usually leads to the formation of binding complexes, often accompanied by large-scale conformational changes. This process is fundamental to biological functions at the molecular and cellular levels. Uncovering the physical mechanisms of biomolecular recognition and quantifying the key biomolecular interactions are vital to understand these functions. The recently developed energy landscape theory has been successful in quantifying recognition processes and revealing the underlying mechanisms. Recent studies have shown that in addition to affinity, specificity is also crucial for biomolecular recognition. The proposed physical concept of intrinsic specificity based on the underlying energy landscape theory provides a practical way to quantify the specificity. Optimization of affinity and specificity can be adopted as a principle to guide the evolution and design of molecular recognition. This approach can also be used in practice for drug discovery using multidimensional screening to identify lead compounds. The energy landscape topography of molecular recognition is important for revealing the underlying flexible binding or binding–folding mechanisms. In this review, we first introduce the energy landscape theory for molecular recognition and then address four critical issues related to biomolecular recognition and conformational dynamics: (1) specificity quantification of molecular recognition; (2) evolution and design in molecular recognition; (3) flexible molecular recognition; (4) chromosome structural dynamics. The results described here and the discussions of the insights gained from the energy landscape topography can provide valuable guidance for further computational and experimental investigations of biomolecular recognition and conformational dynamics.