bluuebunny/crossref_metadata_2025 huggingface dataset:
Parallel‐in‐time‐and‐space electromagnetic transient simulation of multi‐terminal DC grids with device‐level switch modelling
Authors: Cheng Tianshi , Lin Ning , Liang Tian , Dinavahi Venkata
Published: September 2021

The electromagnetic transient (EMT) simulation of multi‐terminal DC (MTDC) grids requires a detailed device‐level modular multilevel converter (MMC) model, which can have thousands of state variables and complex internal structures. The fast device‐level insulated gate bipolar transistor (IGBT) transient requires a very small time‐step, making the computational overhead prohibitive. Based on the analysis of the parallel‐in‐time (PiT) implementation of detailed modelled MMCs, this paper proposes a task‐based hybrid PiT algorithm to achieve high parallel efficiency and speed‐up of MMC with device‐level modelling. Moreover, a transmission line model(TLM)‐based parallel‐in‐time‐and‐space (PiT+PiS) method is proposed to connect PiT grids to conventional or other PiT grids and exploit the maximum parallelism. Simulation results show greater than 30 speed‐up and 60% parallel efficiency on a 48 cores computer for the hybrid PiT method in a 201‐level three‐phase MMC test case, and 20 speed‐up in the transient simulation of CIGRÉ B4 DC grid test system for the PiT+PiS method.
Effects of clock deviations on the performance of microgrids based on virtual synchronous generators
Authors: Castilla Miguel , Miret Jaume , García de Vicuña Luis , Guzmán Ramón , Velasco Manel , Martí Pau
Published: September 2021

An inverter‐based microgrid is a small‐scale power network governed by a distributed control system. In this system, the nodes are the digital controllers of the power inverters, normally located at separate points within the microgrid. A relevant issue is that these controllers operate at different frequencies due to inherent clock deviations in the local hardware oscillators. This paper evaluates the effects of these clock deviations on the performance of microgrids equipped with inverters that emulate the operation of synchronous machines. A systematic procedure is presented to derive steady‐state expressions of the inverter active power and microgrid frequency as a function of clock drift rates. This procedure is applied to swing and governor equations of the virtual synchronous generators, revealing the mechanism that allows clock drifts to be absorbed, making their presence negligible. In addition, it allows recognising the controllers that should never be implemented in a distributed control system, since they cause an unsatisfactory behaviour that can even lead to a blackout in the microgrid. Therefore, the relevance of this study is the identification of the control schemes that are most sensitive to clock drifts, which makes it easier to choose the most suitable control implementation for a particular application. Furthermore, technical guidelines are reported to help researchers on developing control solutions more robust to clock drifts. In this study, the theoretical results are validated by experimental tests in a laboratory microgrid.
Null controllability and finite-time stabilization in minimal time of one-dimensional first-order 2 × 2 linear hyperbolic systems
Authors: Hu Long , Olive Guillaume
Published: September 2021

The goal of this article is to present the minimal time needed for the null controllability and finite-time stabilization of one-dimensional first-order 2 × 2 linear hyperbolic systems. The main technical point is to show that we cannot obtain a better time. The proof combines the backstepping method with the Titchmarsh convolution theorem.
SOP Impfen von Erwachsenen
Authors: Reimers Karin , Müller Dieter
Published: September 2021

Impfen ist eine der wirksamsten Maßnahmen zur Prävention von Infektionskrankheiten. Jeder Arzt ist aufgefordert, seinen Patientinnen und Patienten die empfohlenen Impfungen aktiv anzubieten. Die Ständige Impfkommission am Robert Koch-Institut (STIKO) hat Impfkalender für die in Deutschland empfohlenen Impfungen erarbeitet und gibt in ihren jährlich aktualisierten Empfehlungen wichtige Hinweise zu diesen Impfungen 1.
Unilateral Thoracoscopic Thymectomy for Thymoma: Does Side Matter? A Single Institutional Experience
Authors: Tamburini Nicola , D'Urbano Francesco , Bagolini Francesco , Trapella Giulia Salerno , Quarantotto Francesco , Cavallesco Giorgio , Maniscalco Pio
Published: September 2021

Background Thoracoscopic thymectomy is increasingly performed for the treatment of early stage thymoma. It is characterized by shorter postoperative hospital stay, decreased intraoperative blood loss, and fewer complications compared with transsternal thymectomy. Unilateral video-assisted thoracic surgery (VATS) thymectomy can be easily performed from either side of the thorax, because thymus is located in the middle of mediastinum. However, the side that provides better outcomes remains controversial. The purpose of this study was to compare the efficacy of right and left approaches in performing unilateral thoracoscopic thymectomy for thymoma.

Methods Consecutive patients affected by thymoma who underwent VATS thymectomy on either side between February 2001 and March 2020 were enrolled in the study. Clinicopathologic, surgical, and oncological outcomes were retrospectively analyzed and compared among the two surgical approaches.

Results Unilateral VATS approaches were performed on 29 patients: 12 (41%) on the left side and 17 (59%) on the right side. The mean age was 63.1 ± 11.3 years and the female/male ratio was 1.73:1. The mean operative time and the hospital stay for the left-side VATS and right-side VATS groups were, respectively, 168 ± 49.5 versus 171 ± 47.9 minutes (p = 0.9) and 3 ± 1.03 days versus 3.65 ± 1.93 days (p = 0.7). Postoperative complications occurred in one patient (3%) for left-side VATS group and one patient (3%) for right-side VATS. The 5-year disease-free survival was comparable between two groups (p = 0.74).

Conclusion Unilateral VATS thymectomy in patients with thymoma can be safely and effectively performed by experienced surgeons in either side of the thorax with equivalent oncological outcomes.
Ventricular Assist Device Driveline Infections: A Systematic Review
Authors: Krzelj Kristina , Petricevic Mate , Gasparovic Hrvoje , Biocina Bojan , McGiffin David
Published: September 2021

Infection is the most common complication in patients undergoing ventricular assist device (VAD) implantation. Driveline exit site (DLES) infection is the most frequent VAD infection and is a significant cause of adverse events in VAD patients, contributing to morbidity, even mortality, and repetitive hospital readmissions. There are many risk factors for driveline infection (DLI) including younger age, smaller constitution of patients, obesity, exposed velour at the DLES, longer duration of device support, lower cardiac index, higher heart failure score, DLES trauma, and comorbidities such as diabetes mellitus, chronic kidney disease, and depression. The incidence of DLI depends also on the device type. Numerous measures to prevent DLI currently exist. Some of them are proven, whereas the others remain controversial. Current recommendations on DLES care and DLI management are predominantly based on expert consensus and clinical experience of the certain centers. However, careful and uniform DLES care including obligatory driveline immobilization, previously prepared sterile dressing change kits, and continuous patient education are probably crucial for prevention of DLI. Diagnosis and treatment of DLI are often challenging because of certain immunological alterations in VAD patients and microbial biofilm formation on the driveline surface areas. Although there are many conservative and surgical methods described in the DLI treatment, the only possible permanent solution for DLI resolution in VAD patients is heart transplantation. This systematic review brings a comprehensive synthesis of recent data on the prevention, diagnostic workup, and conservative and surgical management of DLI in VAD patients.
Effect of Epidermal Growth Factor with Silastic Scaffold on Tympanic Membrane Perforations of Chronic Otitis Media
Authors: Bhat Vikram Kemmannu , Desai Suhas Suresh , Hiremath Darshan
Published: September 2021

Aims The burden of chronic otitis media continues to be high, especially in developing countries. The demand for corrective procedure of surgical myringoplasty, which is considered the gold standard for tympanic membrane perforations, is also growing. Hence, there is a need to innovate simpler alternative office procedures that could save effort, time, waiting period, and expenditure.

Materials and Methods This prospective study of 84 patients with mucosal chronic otitis media was undertaken in a tertiary referral hospital. All patients underwent eustachian tube function test, diagnostic nasal endoscopy, and pure tone audiometry. The size of the perforation was assessed endoscopically. All perforations were freshened first with silver nitrate solution. Silastic pieces were placed medial and lateral to the perforation with epidermal growth factor gel in between. Patients were followed up for 3 months.

Results The perforations were classified into three groups (healed, partially healed, and nonhealed) based on the treatment response at the end of the first and third follow-up months. Completely healed and partially healed perforations were considered as “success” and were found to be 79% in this study. Significant association was found between healing status and type of anesthesia. However, the disease stage, size of perforation, and the duration of procedure did not affect the healing status.

Conclusion Silastic enhanced myringoplasty with epidermal growth factor is a simple, effective, and economical procedure that can become an alternative to surgical myringoplasty for chronic otitis media.
MRI T2-Weighted Cochlear Intensity as a Predictor of Hearing Loss with Vestibular Schwannoma Patients
Authors: Luong Peter Q. , Cabrera Claudia I. , Patil Nirav , Khan Hammad , Lagman Carlito , Ostergard Thomas A. , Huang Gary , Bambikidas Nicholas C. , Mowry Sarah E.
Published: September 2021

Objective It is difficult to predict how hearing loss will progress with vestibular schwannomas (VSs) and to determine the optimal time for hearing preservation interventions. This study investigated the relationship between cochlear intensity on T2-weighted magnetic resonance imaging and hearing loss in VS patients over time.

Design Retrospective cohort study.

Setting Single major academic center.

Participants Patients with a diagnosis of VS from 2007 to 2018.

Main Outcome Measures Pure tone average (PTA) and cochlear-to-pontine relative signal intensity (RSI) measured at two time points.

Results Fifty patients were included in the final analysis. For both affected and unaffected ears, the trend in PTA increased from baseline to follow-up. For affected ears, the trend in RSI increased from baseline to follow-up, while for the unaffected ears RSI decreased. There was a significant positive correlation between the initial RSI value in the ipsilateral ear when compared with the change in PTA from baseline to follow-up (r = 0.28, p = 0.048).

Conclusion There is a trend between initial RSI and how hearing changes in the affected ears of patients with VS. Additional studies are needed to explore how this relationship may be better used to predict hearing loss.
Duodenal Ganglioneuroma: A Rare Tumor Causing Upper Gastrointestinal Bleed
Authors: Dhali Arkadeep , Ray Sukanta , Dhali Gopal Krishna , Ghosh Ranajoy , Sarkar Avik
Published: September 2021

Neuroblastic tumors (NTs) include neuroblastoma, ganglioneuroblastoma, and ganglioneuroma (GN). They are very rare in adults. The Surveillance, Epidemiology, and End Results identified 144 patients ≥20 years old at diagnosis (6.1%) from 1973 to 2002. GNs account for 14% of all localized NT. Since 1957, a total of four cases of GN of the duodenum have been reported. We report a novel case of GN of the periampullary region in the duodenum in a 41-year-old man presenting with chronic upper gastrointestinal bleed. Given the rarity of GNs in this age group and the nonspecificity of radiological features, this diagnosis is often missed until histopathology is done. This may negatively affect the prognosis of an otherwise well-prognosticated disease.
Graphene oxide nanosheets help regulate ice formation
Authors: Bandari Anashe
Published: September 2021

Biological organisms exhibit ice regulation properties, which can be mimicked using graphene oxide nanosheets, to help better understand the mechanisms of ice formation.
Investigations of structural and dynamical mechanisms of ice formation regulated by graphene oxide nanosheets
Authors: Zhang Shengkai , Han Jingjing , Luo Xiang , Wang Zhixin , Gu Xudong , Li Na , de Souza Nicolas R. , Garcia Sakai Victoria , Chu Xiang-Qiang
Published: September 2021

Recent research indicates that graphene oxide (GO) nanosheets can be used to regulate ice formation by controlling critical ice nucleus growth in water at supercooling temperatures. In addition, the study of ice formation mechanisms regulated by GO nanosheets, a good model system for antifreeze proteins (AFPs), will shed light on how AFPs regulate ice formation in nature. In this work, time-resolved small-angle x-ray scattering (TR-SAXS) and quasi-elastic neutron scattering (QENS) experiments were carried out to investigate the structural and dynamical mechanisms of ice formation regulated by GO nanosheets. Strikingly, a transient intermediate state was observed in TR-SAXS experiments that only exists in the aqueous dispersions with a larger GO size (11 nm). This serves as evidence that the size of GO is critical for regulating ice formation. Elastic neutron scattering results indicate that ice is formed in all samples and thermal hysteresis occurs in GO aqueous dispersions in both H2O and D2O. The structural and dynamics information about water molecules in GO, extracted from QENS, reveals different dynamical behaviors of water molecules in GO aqueous dispersions when approaching the ice formation temperature.
Comparative studies of IR spectra of deprotonated serine with classical and thermostated ring polymer molecular dynamics simulations
Authors: Inakollu V. S. Sandeep , Yu Haibo
Published: September 2021

Here we report the vibrational spectra of deprotonated serine calculated from the classical molecular dynamics (MD) simulations and thermostated ring-polymer molecular dynamics (TRPMD) simulation with third-order density-functional tight-binding. In our earlier study [Inakollu and Yu, “A systematic benchmarking of computational vibrational spectroscopy with DFTB3: Normal mode analysis and fast Fourier transform dipole autocorrelation function,” J. Comput. Chem. 39, 2067 (2018)] of deprotonated serine, we observed a significant difference in the vibrational spectra with the classical MD simulations compared to the infrared multiple photon dissociation spectra. It was postulated that this is due to neglecting the nuclear quantum effects (NQEs). In this work, NQEs are considered in spectral calculation using the TRPMD simulations. With the help of potential of mean force calculations, the conformational space of deprotonated serine is analyzed and used to understand the difference in the spectra of classical MD and TRPMD simulations at 298.15 and 100 K. The high-frequency vibrational bands in the spectra are characterized using Fourier transform localized vibrational mode (FT-νNAC) and interatomic distance histograms. At room temperature, the quantum effects are less significant, and the free energy profiles in the classical MD and the TRPMD simulations are very similar. However, the hydrogen bond between the hydroxyl–carboxyl bond is slightly stronger in TRPMD simulations. At 100 K, the quantum effects are more prominent, especially in the 2600–3600 cm−1, and the free energy profile slightly differs between the classical MD and TRPMD simulations. Using the FT-νNAC and the interatomic distance histograms, the high-frequency vibrational bands are discussed in detail.
A new criterion for evaluating the extinction abilities of moving droplets: Applied for radiative thermal shielding
Authors: Du Yongcheng , Liu Boyun
Published: September 2021

In this study, the thermal shielding ability of sprays and the accompanying scientific problem of the optimal extinction diameter of moving droplets have been analyzed with the Lagrangian model and Mie theory under the overall consideration of dynamical and optical characteristics. A correction factor is introduced to eliminate the forward scattering effects of large droplets. Then, a new variable, named the thermal shielding index, has been presented as a criterion evaluating the extinction abilities of moving droplets, which analyzed the extinction performance during the whole lifetime of droplets. According to the evaluation method defined in this paper, the optimal extinction diameters obtained based on the thermal shielding index are far greater than those obtained based on the optical properties. In addition, if the initial droplet sizes were relatively large, the upward injection way will perform better than the downward injection way for a longer traveling distance and, of course, a longer lifetime.
Large time behavior of solutions to a quasilinear attraction–repulsion chemotaxis model with nonlinear secretion
Authors: Ren Guoqiang , Liu Bin
Published: September 2021

In this paper, we study the large time behavior of a quasilinear attraction–repulsion chemotaxis model with nonlinear secretion: ut = ∇ · (D(u)∇u − χΦ(u)∇v + ξΨ(u)∇w) + λu − μuϵ; 0=Δv−α1v+β1uγ1; 0=Δw−α2w+β2uγ2, x ∈ Ω, t > 0. We show that the global-in-time bounded smooth solution of the system converges exponentially/algebraically to steady state in the large time limit. Those results generalize some of our previous results [G. Ren and B. Liu, Math. Models Methods Appl. Sci. 30(13), 2619–2689 (2020) and G. Ren and B. Liu, J. Differ. Equations 268(8), 4320–4373 (2020)].
Symmetries of the multi-component supersymmetric (ABC)-type KP hierarchies
Authors: Li Chuanzhong , Shi Qingling
Published: September 2021

In this article, we give the definition and additional symmetries of the multi-component supersymmetric Kadomtsev–Petviashvili (KP) (MSKP) hierarchy, the multi-component supersymmetric B type KP hierarchy, and the multi-component supersymmetric C type KP hierarchy. The additional flows of the MSKP hierarchy constitute ⨂SW1+∞ Lie algebra. Due to the B and C [B(C)] type reduction of the multi-component supersymmetric B and C type KP hierarchies, these additional flows form the B(C) type ⨂SW1+∞ Lie algebra.
Generation and stopping of laser-driven two-component ion beam
Authors: Deng H. X. , Shao F. Q. , Zou D. B. , Jiang X. R. , Wang W. Q. , Zhao N. , Hu L. X. , Zhang G. B. , Yang X. H. , Yu J. Q. , Yu T. P.
Published: September 2021

The generation and stopping of a laser-driven two-component ion beam are investigated by three-dimensional particle-in-cell simulation and an extended stopping model. It is found that a two-component ion beam with the tunable composition ratio can be obtained from the two-species-ions sandwich target interacting with a relativistic laser pulse. When the generated proton beam mixed with a certain portion of carbon ions is transporting in fully ionized dense plasma, the beam stopping power is significantly enhanced compared to a pure proton beam. The maximum penetration depth is sharply reduced, and the Bragg peak with a higher magnitude appears earlier at the end of their paths, which is beneficial for achieving more localized energy deposition. The effect of heavy ion mixing on proton beam driven fast ignition is also discussed. A simple theoretical model is established, indicating that the required ignition time is relatively delayed for a heavy-ion doping case. For a small hot-spot size, it is possible to achieve the fusion ignition for a low mixed ratio. However, it is difficult to maintain a high fuel temperature due to the growing energy loss originating from mechanical work and thermal conduction.
Study of Pt growth on Si, Al2O3, Au, and Ni surfaces by plasma enhanced atomic layer deposition
Authors: Yan Mingming , Zhang Tianchong , Wang Bo , Liu Jing , Liang Xiaoxiao , Xu Yuanze , Yi Futing
Published: September 2021

Atomic layer deposition is a powerful technique for achieving atomic-level control in the deposition of thin films and nanoparticles. The ultrathin noble metal films can be applied in many functional devices, but it is a challenge to obtain such films since the island growth mode generally happens instead of the layer growth mode. In this work, the nucleation and growth of platinum on Si, Al2O3, Au, and Ni substrates were studied using (MeCp)PtMe3 and O2 plasma as a precursor and a co-reactant, respectively. The evolution of Pt coverage on different surfaces was observed and discussed based on the experimental results by x-ray photoelectron spectra. The chemical adsorption of the precursor and the following processes like metal atom diffusion on substrate surfaces and up-stepping onto the existing metal islands were considered to dominate the growth before continuous films formed. The chemisorption determined the metal coverage on bare substrate surfaces, and the total coverage was influenced by metal atom diffusion and up-stepping behaviors that are determined by surface energy relationships between the deposited metal and substrate surfaces. Pt films were easier to form on Al2O3 and Ni surfaces compared with on Si and Au surfaces, respectively. A model was proposed to help to understand the mechanisms in the nucleation and growth processes, involving the chemisorption, diffusion, and up-stepping, which contributed to prepare ultrathin continuous Pt films on different substrates.
Calibration-based overlay sensing with minimal-footprint targets
Authors: Wolterink Tom A. W. , Buijs Robin D. , Gerini Giampiero , Verhagen Ewold , Koenderink A. Femius
Published: September 2021

Overlay measurements are a critical part of modern semiconductor fabrication, but overlay targets have not scaled down in the way devices have. In this work, we produce overlay targets with very small footprint, consisting of just a few scattering nanoparticles in two separate device layers. Using moiré patterns to deterministically generate many overlay errors on a single chip, we demonstrate readout of the relative displacement between the two layers and show that calibration on one realization of the targets can be used for overlay measurements on subsequent instances. Our results suggest that using greater quantities of smaller overlay targets may benefit performance both directly and through finer sampling of deformation.
Pimples reduce and dimples enhance flat dielectric surface image repulsion
Authors: Solis Francisco J. , Olvera de la Cruz Monica
Published: September 2021

In solid–liquid, or liquid–liquid, interfaces with dielectric contrast, charged particles interact with the induced polarization charge of the interface. These interactions contribute to an effective self-energy of the bulk ions and mediate ion–ion interactions. For flat interfaces, the self-energy and the mediated interactions are neatly constructed by the image charge method. For other geometries, explicit results are scarce and the problem must be treated via approximations or direct computation. The case of interfaces with roughness is of great practical importance. This article provides analytical results, valid to first-order in perturbation theory, for the self-energy of particles near rough substrates. Explicit formulas are provided for the case of a sinusoidal deformation of a flat surface. Generic deformations can be treated by superposition. In addition to results for the self-energy, the surface polarization charge is presented as a quadrature. The interaction between an ion and the deformed surface is modified by the change in relative distance as well as by the local curvature of the surface. Solid walls, with a lower dielectric constant than the liquid, repel all ions. We show that the repulsion is reduced by local convexity and enhanced by concavity; dimples are more repulsive than pimples.
Morphological study of the rainbow scattering of protons by graphene
Authors: Ćosić M. , Hadžijojić M. , Petrović S. , Rymzhanov R.
Published: September 2021

We have studied metamorphoses of the angular rainbow pattern generated by classical rainbow scattering of protons by graphene. To analyze the rainbow pattern, a morphological method was developed. It focuses on the shape of the rainbow pattern rather than on the exact position of rainbow lines or the particle count. It comprises elements of the catastrophe theory, which provides a local model of the rainbow pattern and the reduced potential and an index theory of algebraic topology that allows the evolution of the rainbow pattern to be linked with bifurcations of critical points of the reduced potential. The obtained insight is summarized into five principles that allow an experimentalist to sketch a qualitatively correct rainbow pattern in the impact parameter plane and the distribution of the reduced potential critical points, just by observing the evolution of the angular rainbows. The morphological method should be applicable for the analysis of all structurally stable patterns in nature.
Prediction of chemical ordering in refractory high-entropy superalloys
Authors: Wu Yifeng , Irving Douglas L.
Published: September 2021

Refractory high-entropy superalloys (RHESs) exhibit impressive nanostructure-property relationships and have promise in next-generation high-temperature structural applications, which has motivated extensive research into these materials. The design space, however, is compositionally vast and complex due to the presence of multiple phases that differ in the composition and chemical order. To address these obstacles in a computationally efficient manner, an advanced approach combining the mean-field density functional theory with parameters determined using machine learning tools has been developed. This approach was implemented here to investigate AlMo0.5NbTa0.5TiZr, which exhibits a nanostructure consisting of cuboidal BCC precipitates coherently embedded within the B2 matrix. It was found that Al and Zr were responsible for the formation of the B2 matrix. In addition, the matrix and the precipitate were found to have very different elastic characteristics. The matrix has a small elastic moduli and large anisotropy while the precipitate is elastically stiff and nearly isotropic. Beyond the current findings, the parameters for the mean field approach are given in the supplementary material and these can be used in future efforts to predict chemical orders, phase partitioning, and elastic properties of RHESs as a function of chemical composition.
Measuring the complete complex correlation matrix of a partially coherent vector beam via self-referencing holography
Authors: Wang Zhuoyi , Lu Xingyuan , Huang Wenrui , Konijnenberg A. P. , Zhang Hao , Zhao Chengliang , Cai Yangjian
Published: September 2021

Measuring the complete complex correlation matrix of a partially coherent vector beam is extremely important for transmission calculation, encryption, and decryption for free-space optical communication and optical imaging. Based on self-referencing holography, we introduce a simple and efficient setup to measure the complex-valued cross spectral density matrix of a partially coherent vector beam, without any priori assumptions or approximations of the source. To verify the feasibility of our method, 2 × 2 complex-valued cross spectral density components in the matrix function of particularly correlated radially polarized partially coherence beam have been measured. The experimental measurements are in good agreement with the theoretical model.
Resonance oscillations of a drop or bubble in a viscous vibrating fluid
Authors: Konovalov V. V. , Lyubimov D. V. , Lyubimova T. P.
Published: September 2021

In the present work, we study the resonance oscillations of a single liquid drop or gas bubble relative to their equilibrium spherical shape, which arise as a result of harmonic, translational vibrations of a volume of liquid of different densities, containing such an inclusion. The parametric resonance of the forced translational mode with the main resonant frequency equal to the sum of two adjacent eigenfrequencies of capillary oscillations of the interface was previously discovered in an inviscid approximation [Lyubimov et al., “Resonance oscillations of a drop (bubble) in a vibrating fluid,” J. Fluid Mech. 909, A18 (2021)], also taking into account low viscosity using a phenomenological approach. Now, the effect of viscosity on the resonance is investigated by rigorous accounting for the viscosity in the dynamic boundary layer near the interface. The relations governing the evolution of the resonance modes near the threshold of instability excitation are determined. The equivalence of the two approaches taking viscosity into account is revealed: the rigorous one, built on a method of multiple scales, and the previously developed phenomenological approach, which is based on the artificial addition of the dissipative terms to the amplitude equations.
High-speed ultrasound imaging of laser-induced cavitation bubbles
Authors: Izak Ghasemian S. , Reuter F. , Ohl C. D.
Published: September 2021

While ultrasound and cavitation based therapies have mushroomed over the years, there is a lack of online monitoring of the cavitation bubble dynamics in biological tissue. Here, we demonstrate that with ultrasonic plane wave imaging, the fast dynamics of single cavitation bubbles can be resolved non-invasively in a tissue mimicking material. Due to the high contrast of bubbles, plane wave compounding is not necessary and the frame rates of up to 74 kHz can been achieved with a research grade ultrasound scanner. Comparison with simultaneous high-speed imaging demonstrates excellent agreement of both measurement modalities in water and in a tissue mimicking material.
Fabrication of L1-FeNi films with island structures by nitrogen insertion and topotactic extraction for improved coercivity
Authors: Nishio Takahiro , Kura Hiroaki , Ito Keita , Takanashi Koki , Yanagihara Hideto
Published: September 2021

Conventional permanent magnets that exhibit high-saturation magnetizations and coercivities contain rare earth elements or noble metals, which renders them economically unsustainable. L10-FeNi alloy, which does not contain such elements, possesses excellent magnetic properties even at high temperatures. However, the coercivity of the fabricated alloy is much lower than its potential coercivity. In this study, to investigate the temperature dependence of L10-FeNi and its magnetic properties in the vicinity of the single magnetic domain size, L10-FeNi island structures were fabricated via sputter deposition of a FeNi alloy and subsequent application of the nitrogen insertion and topotactic extraction method. The crystallinity of FeNiN in the islands improved during the nitriding process, whereas in the denitriding process, the isolation of the islands for magnetic decoupling proceeded owing to volume shrinkage during phase transition. The superlattice structures in each process were confirmed based on transmission electron microscopy diffraction patterns. By varying the nominal film thickness, it was found that a 20 nm film containing island structures, which had undergone a complete denitriding reaction and showed particle sizes close to the single magnetic domain size, exhibited the highest coercivity (188 kA/m at 10 K) reported thus far. Even at 600 K, the coercivity was only reduced by 15% compared to that at 300 K. These results suggest that L10-FeNi with a controlled island structure is a promising magnetic material with good heat resistance.
Operation of quantum dot based terahertz photoconductive antennas under extreme pumping conditions
Authors: Gorodetsky Andrei , Leite Ivo T. , Rafailov Edik U.
Published: September 2021

Photoconductive antennas deposited onto GaAs substrates that incorporate InAs quantum dots have been recently shown to efficiently generate both pulsed and CW terahertz radiation. In this Letter, we determine the operational limits of these antennas and demonstrate their extreme thermal breakdown tolerance. Implanted quantum dots serve as free carrier capture sites, thus acting as lifetime shorteners, similar to defects in low-temperature grown substrates. However, unlike the latter, defect-free quantum-dot structures possess perfect lattice quality, thus not compromising high carrier mobility and pump intensity stealth. Single gap design quantum dot based photoconductive antennas are shown to operate under up to 1 W of average pump power (∼1.6 mJ cm−2 energy density), which is more than 20 times higher than the pumping limit of low-temperature grown GaAs based substrates. Conversion efficiency of the quantum dot based photoconductive antennas does not saturate up to 0.75 W of pump power (∼1.1 mJ cm−2 energy density). Such a thermal tolerance suggests a glowy prospect for the proposed antennas as a perspective candidate for intracavity optical-to-terahertz converters.
Data-driven surrogates of rotating detonation engine physics with neural ordinary differential equations and high-speed camera footage
Authors: Koch J.
Published: September 2021

Interacting multi-scale physics in the Rotating Detonation Engine (RDE) lead to diverse nonlinear dynamical behavior, including combustion wave mode-locking, modulation, and bifurcations. Here, surrogate models of the RDE physics, including combustion, injection, and mixing, are sought that can reproduce mode-locked combustion waves through their interactions. These surrogate models are constructed and trained within the context of neural ordinary differential equations evolving through the latent representation of the waves: the traveling wave coordinate ξ=x−ct+a. It is shown that the multi-scale nature of the physics can be successfully separated and analyzed separately, providing valuable insight into the fundamental physical processes of the RDE.
Shock-induced cavitation and wavefront analysis inside a water droplet
Authors: Biasiori-Poulanges Luc , El-Rabii Hazem
Published: September 2021

The objective of this study is to develop a basic understanding of the interaction of shock waves with density inhomogeneities. We consider the particular instance of a planar air shock impinging on a spherical water droplet and discuss to what extent this interaction can lead to the inception of cavitation inside the droplet. The effort centers on early phases of the interaction, which are analyzed using both ray theory and a hydrodynamic code. Within the context of ray theory, the occurrence of focusing is examined in detail, and parametric equations are derived for the transmitted wavefront and its multiple internal reflections. It is found that wave patterns predicted by ray calculations compare extremely well with the more accurate numerical solutions from simulations. In particular, it is shown that the internal wavefront assumes a complex time-dependent shape whose dominant feature is the existence of cusp singularities. These singular points are shown to trace out surfaces that are the caustics of the associated system of rays. From the singularities of the energy flux density of the refracted wave, the parametric equations of the caustic surface associated with the kth reflected wavefront are deduced. As a consequence of the focusing process, simulations show the formation of negative-pressure regions in the internal flow field. These low-pressure zones are identified as possible spots at which cavitation may occur, depending on the magnitude of pressure reached. Finally, numerical results provide quantitative information on the dependence of negative-pressure peaks upon incident-shock-wave strength.
Critical phenomena and strategy ordering with hub centrality approach in the aspiration-based coordination game
Authors: Jeong Wonhee , Yu Unjong
Published: September 2021

We study the coordination game with an aspiration-driven update rule in regular graphs and scale-free networks. We prove that the model coincides exactly with the Ising model and shows a phase transition at the critical selection noise when the aspiration level is zero. It is found that the critical selection noise decreases with clustering in random regular graphs. With a non-zero aspiration level, the model also exhibits a phase transition as long as the aspiration level is smaller than the degree of graphs. We also show that the critical exponents are independent of clustering and aspiration level to confirm that the coordination game belongs to the Ising universality class. As for scale-free networks, the effect of aspiration level on the order parameter at a low selection noise is examined. In model networks (the Barabási–Albert network and the Holme–Kim network), the order parameter abruptly decreases when the aspiration level is the same as the average degree of the network. In contrast, in real-world networks, the order parameter decreases gradually. We explain this difference by proposing the concepts of hub centrality and local hub. The histogram of hub centrality of real-world networks separates into two parts unlike model networks, and local hubs exist only in real-world networks. We conclude that the difference of network structures in model and real-world networks induces qualitatively different behavior in the coordination game.
Characterization of plasma synthetic jet actuator with Laval-shaped exit and application to drag reduction in supersonic flow
Authors: Xie Wei , Luo Zhenbing , Hou Lin , Zhou Yan , Liu Qiang , Peng Wenqiang
Published: September 2021

A plasma synthetic jet (PSJ) actuator (PSJA) with a Laval-shaped exit is investigated using a numerical method alongside a PSJA with a straight-shaped exit for comparison. The accuracy of the numerical method is first verified by comparing simulation results with experimental schlieren images and pressure measurement values. The performance of the PSJA with the Laval-shaped exit is then investigated in quiescent air. The results show that when the dimensionless energy ε > 5.06, the maximum exit velocity of the PSJA with the Laval-shaped exit becomes supersonic and is higher than that of the actuator with straight-shaped exit. The opposite is true when ε ≤ 5.06. The jet front velocity of the PSJ is much lower than the exit velocity, and no obvious improvement is seen when changing from the straight-shaped exit to a Laval-shaped exit due to the shock waves near the exit. Finally, the drag reduction effect of an opposing PSJ on a hemisphere in Ma3 flow is investigated. For a geometrically fixed PSJA, the flow field of a singled-pulsed opposing PSJ in Ma3 flow can be classified into three patterns according to the values of the maximum pressure ratio and ε: pattern 1 consists of only vortices and a slight change in the bow shock, pattern 2 consists of a typical long penetration mode (LPM) of the opposing PSJ, and pattern 3 consists of both a short penetration mode and a LPM. For PSJAs with both kinds of exits within a certain range, the average drag reduction increases with ε. However, when ε is higher than 48.02 for a Laval-shaped exit and 16.01 for a straight-shaped exit, the drag reduction effect decreases due to the rise in drag associated with the formation of the PSJ. The drag reduction effect associated with a PSJA with a Laval-shaped exit is significantly better than that of one with a straight-shaped exit when ε > 8. The optimal average drag reduction values, 25.82% and 20.55%, are obtained at ε = 48.02 and ε = 16.01, respectively, for a Laval-shaped exit and a straight-shaped exit.
Effect of particle dipolar interactions on the viscoelastic response of dilute ferrofluids undergoing oscillatory shear
Authors: Cunha Francisco Ricardo , Rosa Adriano Possebon
Published: September 2021

In this work, we investigate the viscoelastic behavior of a ferrofluid undergoing an oscillatory simple shear flow and also under the influence of an external magnetic field. The main goal is to examine the influence of the dipolar interactions and formation of anisotropic structures on the macroscopic rheological response of these complex fluids. This study is performed by direct numerical simulation of neutrally buoyant, Brownian magnetic spheres in the limit of vanishingly small Reynolds numbers using Brownian dynamics. The long-range dipolar interactions are computed by the Ewald summation technique. We present the in-phase and out-of-phase rotational viscosity components as a function of the oscillatory frequency for several values of the dipolar interaction parameter and shear strain. The results show that the viscoelastic transition in the fluid is anticipated in the presence of dipolar interactions. These phenomena are probably related to the formation of complex structures in the fluid like anisotropic linear chains. In addition, a qualitative analysis of microstructure transitions during the suspension time evolution indicates the formation of long anisotropic chains for the high strength of the dipolar interaction and small shear rates. The simulation results are compared with the classical Maxwell linear viscoelastic model, and a characteristic relaxation time is identified for the investigated ferrofluid. We also offer evidence that this relaxation time has a quadratic power law scaling dependence on the dipolar interaction parameter and that the dipolar interactions are the main physical mechanics, which creates elastic response of the ferrofluid investigated here as a direct consequence of the gain of memory at the microscopic level due to the action of the magnetic torque on the particles and the formation of oriented aggregative structures like anisotropic chains.
MAX mutant small-cell lung cancers exhibit impaired activities of MGA-dependent noncanonical polycomb repressive complex
Authors: Llabata Paula , Torres-Diz Manuel , Gomez Antonio , Tomas-Daza Laureano , Romero Octavio A. , Grego-Bessa Joaquim , Llinas-Arias Pere , Valencia Alfonso , Esteller Manel , Javierre Biola M. , Zhang Xiaoyang , Sanchez-Cespedes Montse
Published: September 2021

Significance

The MYC axis is commonly disrupted in cancer, mostly by activation of the MYC oncogenes but also by genetic inactivation of MAX, the obligate partner of MYC, and of the MAX partner MGA, both of which are members of the polycomb repressive complex ncPRC1.6. While the oncogenic properties of the MYC family have been extensively studied, those of the MAX-deficient cells and the role of MGA in MAX mutant cells remain unclear. In this study, we demonstrate that MAX-deficient SCLCs cells have either ASCL1 or NEUROD1 or combined characteristics. Furthermore, our data reveal that the lack of available MAX restricts MGA occupancy in gene promoters and, although the ncPRC1.6 can still be formed, there is a deficient ncPRC1.6-mediated gene repression.
The macrophage odorant receptor Olfr78 mediates the lactate-induced M2 phenotype of tumor-associated macrophages
Authors: Vadevoo Sri Murugan Poongkavithai , Gunassekaran Gowri Rangaswamy , Lee ChaeEun , Lee NaHye , Lee Jiyoun , Chae Sehyun , Park Jae-Yong , Koo JaeHyung , Lee Byungheon
Published: September 2021

Significance

Expression and function of odorant receptors (ORs) are being increasingly reported in nonolfactory sites. However, ORs that can be targeted by drugs to treat diseases remain poorly identified. Here, we hypothesized that the macrophage OR Olfr78 functions as a tumor-derived lactate sensor and shapes the macrophage–tumor axis. Olfr78 and the G protein–coupled receptor Gpr132 form a heterodimer that senses lactate in the tumor microenvironment, leading to generation of tumor-associated macrophages with a protumoral M2 phenotype, which promotes tumor progression and metastasis. Our findings suggest an alternative strategy for cancer treatment, namely targeting the interaction between tumor-derived metabolites and ORs.
Norms of assertion in the United States, Germany, and Japan
Authors: Kneer Markus
Published: September 2021

The recent controversy about misinformation has moved a question into the focus of the public eye that has occupied philosophers for decades: Under what conditions is it appropriate to assert a certain claim? When asserting a claim that
x
, must one know that
x
? Must
x
be true? Might it be normatively acceptable to assert whatever one believes? In the largest cross-cultural study to date (total
n
= 1,091) on the topic, findings from the United States, Germany, and Japan suggest that, in order to claim that
x
,
x
need not be known, and it can be false. However, the data show, we do expect considerable epistemic responsibility on the speaker’s behalf: In order to appropriately assert a claim, the speaker must have good reasons to believe it.
One-dimensional van der Waals heterostructures: Growth mechanism and handedness correlation revealed by nondestructive TEM
Authors: Zheng Yongjia , Kumamoto Akihito , Hisama Kaoru , Otsuka Keigo , Wickerson Grace , Sato Yuta , Liu Ming , Inoue Taiki , Chiashi Shohei , Tang Dai-Ming , Zhang Qiang , Anisimov Anton , Kauppinen Esko I. , Li Yan , Suenaga Kazu , Ikuhara Yuichi , Maruyama Shigeo , Xiang Rong
Published: September 2021

Significance

We recently synthesized coaxially nested one-dimensional van der Waals heterostructures in which boron nitride nanotubes or molybdenum disulfide nanotubes grew seamlessly on a single-walled carbon nanotube template. In this work, edge structures, nucleation sites, and crystal epitaxial relationships in heteronanotubes are unambiguously revealed by a nondestructive transmission electron microscopic technique. These understandings, together with the characterization technique developed here, can help to optimize the synthesis process. Structure-controlled heteronanotubes may, ultimately, be used to build nanoscale devices such as gate-all-around nanotube transistors.
Emergent RNA–RNA interactions can promote stability in a facultative phototrophic endosymbiosis
Authors: Jenkins Benjamin H. , Maguire Finlay , Leonard Guy , Eaton Joshua D. , West Steven , Housden Benjamin E. , Milner David S. , Richards Thomas A.
Published: September 2021

Significance

Stable endosymbiosis between eukaryotic microbes has driven the evolution of further cellular complexity. Yet the mechanisms that can act to stabilize an emergent eukaryote–eukaryote endosymbiosis are unclear. Using the model facultative endosymbiotic system,
Paramecium bursaria
, we demonstrate that endosymbiont–host RNA–RNA interactions can drive a cost to host growth upon endosymbiont digestion. These RNA–RNA interactions are facilitated by the host RNA-interference system. For endosymbiont messenger RNA sharing a high level of sequence identity with host transcripts, this process can result in host gene knockdown. We propose that these endosymbiont–host RNA–RNA interactions—“RNA-interference collisions”—represent an emergent mechanism to sanction the host for breakdown of the endosymbiosis, promoting the stability of the facultative endosymbiotic interaction.
Local- and regional-scale racial and ethnic disparities in air pollution determined by long-term mobile monitoring
Authors: Chambliss Sarah E. , Pinon Carlos P.R. , Messier Kyle P. , LaFranchi Brian , Upperman Crystal Romeo , Lunden Melissa M. , Robinson Allen L. , Marshall Julian D. , Apte Joshua S.
Published: September 2021

Significance

It is known, to researchers and heavily impacted communities, that people of color face a higher average burden of air pollution. It was unknown whether racial/ethnic disparities were caused by spatial heterogeneities at the level of city blocks, neighborhoods, or urban regions. Our approach leverages a unique set of highly local observations, covering every city block of 13 cities and urban districts that are home to 450,000 people. We find that even for pollutants with steep localized gradients, differences in average outdoor concentrations among racial/ethnic groups are driven by regional variability. However, localized peaks indicate opportunities to reduce extremes within groups. The methods and findings of this study can inform strategies to reduce disparities in urban air pollution exposure.