bluuebunny/crossref_metadata_2025 huggingface dataset:
Nodular Malignant Melanoma on the Abdomen of a Lactating Lady
Authors: Girisha Banavasi Shanmukha , Chikkanna Kavya , Teerthanath S. , D'souza Caren
Published: January 2024

Malignant melanoma is an uncommon condition in Indian and dark-skinned individuals. Additionally, it is associated with lifetime recurrences and poor prognosis. Its presence on the trunk poses a diagnostic challenge as it can simulate various skin lesions. Furthermore, it raises diagnostic and therapeutic challenges in pregnancy and lactation. Early recognition and appropriate treatment can reduce adverse events in the mother and the baby. Here, we are reporting a case of a 33-year-old lactating mother who presented with a solitary, rapidly growing nodule on the abdomen. Nodular malignant melanoma was diagnosed on further evaluation with histopathology and immunohistochemistry.
Suture-Based Distal Radioulnar Joint Stabilization: A Biomechanical Evaluation in a Cadaveric Model
Authors: Graf Alexander R. , Ahmed Adil S. , Thompson Dan , Gottschalk Michael B. , Wagner Eric R. , Suh Nina
Published: January 2024

Purpose Management of acute distal radioulnar joint (DRUJ) instability is complex and controversial. Common treatment options include prolonged immobilization, stabilization with wires, and acute triangular fibrocartilage complex repair. However, none of these permits an early range of motion. The purpose of this study is to investigate the feasibility of a suture-based stabilization (SBS) technique for acute DRUJ instability to permit early active motion.

Methods A biomechanical study utilizing eight cadaveric arms was performed. All specimens were tested in the intact state prior to the creation of bidirectional DRUJ instability. For the SBS group, 2-mm suture tapes with suture button fixation were utilized to recreate the respective contributions of distal oblique bundle and volar and dorsal radioulnar ligaments to DRUJ stability. All specimens were cyclically loaded with a simulated ballottement stress of 20N in forearm positions of neutral, 60 degrees of pronation and 60 degrees of supination. Range of motion and total translation were measured and then compared between the two groups.

Results The average range of motion in the intact and SBS specimens was 174 and 175 degrees, respectively. There were no significant differences in displacement between the intact and SBS group in neutral and in supination. However, the SBS group had less translation than the intact group in pronation.

Conclusions For acute DRUJ instability, the described SBS technique provides similar stability to the native intact DRUJ without compromising the range of motion in a cadaveric model. Future comparative studies are warranted prior to translation into the clinical arena.

Clinical Relevance This is a biomechanical study investigating a treatment technique for acute DRUJ instability that would allow an early range of motion.
Ipsilateral Nasoseptal Flaps in a Transpterygoid Approach: Technical Pearls and Reconstruction Outcomes
Authors: Chang Michael T. , Grimm David , Asmaro Karam , Yong Michael , Low Christopher , Lee Christine K. , Nayak Jayakar V. , Hwang Peter H. , Fernandez-Miranda Juan C. , Patel Zara M.
Published: January 2024

Background Transpterygoid approaches to the skull base require dissection of the sphenopalatine artery, potentially compromising the option to harvest an ipsilateral nasoseptal flap (NSF) for reconstruction. In cases where other reconstructive options are limited, it may be necessary to utilize a NSF ipsilateral to the transpterygoid approach. Here, we describe the technique of NSF pedicle preservation with reconstruction outcomes.

Methods This was a retrospective single-institution review of all expanded endonasal skull base cases utilizing a NSF ipsilateral to a transpterygoid approach. Reconstruction outcomes collected include intraoperative fluorescence with indocyanine green (ICG), postoperative magnetic resonance imaging (MRI) gadolinium enhancement, endoscopic assessment, and reconstruction-related complications.

Results Twenty-one cases were included in this study (mean age 51.0 ± 20.6 years, 61.9% female). Indications for NSF ipsilateral to the transpterygoid approach included: bilateral transpterygoid approach (52.4%), revision reconstruction (23.8%), or significant septal deviation (19.0%). Twelve of 14 (85.7%) flaps demonstrated intraoperative perfusion with ICG, 15 of 15 (100%) enhanced on postoperative MRI, and 21 of 21 (100%) flaps had a healthy, viable appearance on postoperative endoscopy. There were no instances of flap necrosis or postoperative cerebrospinal fluid leaks. Technical keys to optimize mobilization of the pedicle include wide decompression of the sphenopalatine foramen and release of neurovascular tethering points of the pterygopalatine fossa. These steps allow for wide skull base exposure with preservation of the sphenopalatine artery.

Conclusion With this technique, the transpterygoid approach can be performed in a manner that preserves the pedicle for an ipsilateral NSF and achieve an excellent reconstructive outcome.
Evaluation of Tubularized Incised Plate Urethroplasty with Spongioplasty–Dartosoraphy Reinforcement in Pediatric Hypospadias: A Randomized Controlled Study
Authors: Daboos Mohammad , Abdelmaboud Mohamed , Azab Ahmed , Abdelaziz Mohamed , Eldamanhory Hany
Published: January 2024

Introduction The original description of tubularized incised plate urethroplasty (TIPU) was provided by Snodgrass in 1994. The results were significantly improved by several modifications. To decrease the incidence of complications, interposing a vascularized flap after tubularization of the neourethra is recommended. The extent to which the type of interposed tissue has a direct effect on the rate of complications and cosmetic outcomes after TIPU repair is considered the answer to the main hypothesis of this study.

Materials and Methods This prospective controlled randomized trial was conducted in the Department of Pediatric Surgery, Al-Azhar University, Cairo, Egypt, between May 2019 and May 2023. A total of 220 patients were included in this study. Patients were randomly assigned to either group A or group B. Group A included 110 patients who underwent TIPU with spongioplasty–dartosoraphy reinforcement. The other 110 patients (group B) underwent TIPU with dorsal dartos flap interposition, without spongioplasty.

Results Complications developed in 34 of 220 patients (15.4%). In group A, complications developed in 11 of 110 patients (10.0%). In group B, complications occurred in 23 of 110 patients (20.9%). Although the fistula rate, glanular dehiscence, disruption, and meatal stenosis were not significantly different between the study groups, the skin necrosis rate was significantly lower in group A than in group B. The overall complication rate was significantly lower in group A than in group B. Also, the difference in the mean Hypospadias Objective Scoring Evaluation between the two groups was statistically significant.

Conclusion TIPU with spongioplasty–dartosoraphy reinforcement is an effective modification of conventional TIPU. This modification appears to reduce the rate of complications and yield better cosmetic outcomes.
A connection between Uq(sl(3)) and Z2×Z2-graded special linear Lie colour algebras via Klein operators
Authors: Almutairi Alhanouf M. , Isaac Phillip S.
Published: January 2024

We provide an explicit connection between the quantum group Uq(sl(3)) in the limit q → −1 and a Z2×Z2-graded Lie colour algebra. This is realised through an algebra embedding assisted by a Klein operator. This provides a proof of concept of an explicit method that could lead to constructing more general Z2×Z2-graded Lie colour algebras, and their representations.
Reconfiguration of Amazon’s connectivity in the climate system
Authors: Giammarese Adam , Brown Jacob , Malik Nishant
Published: January 2024

With the recent increase in deforestation, forest fires, and regional temperatures, the concerns around the rapid and complete collapse of the Amazon rainforest ecosystem have heightened. The thresholds of deforestation and the temperature increase required for such a catastrophic event are still uncertain. However, our analysis presented here shows that signatures of changing Amazon are already apparent in historical climate data sets. Here, we extend the methods of climate network analysis and apply them to study the temporal evolution of the connectivity between the Amazon rainforest and the global climate system. We observe that the Amazon rainforest is losing short-range connectivity and gaining more long-range connections, indicating shifts in regional-scale processes. Using embeddings inspired by manifold learning, we show that the Amazon connectivity patterns have undergone a fundamental shift in the 21st century. By investigating edge-based network metrics on similar regions to the Amazon, we see the changing properties of the Amazon are noticeable in comparison. Furthermore, we simulate diffusion and random walks on these networks and observe a faster spread of perturbations from the Amazon in recent decades. Our methodology innovations can act as a template for examining the spatiotemporal patterns of regional climate change and its impact on global climate using the toolbox of climate network analysis.
Comparison of the evolution of Rayleigh–Taylor instability during the coasting phase of the central ignition and the double-cone ignition schemes
Authors: Lei Y. Y. , Wu F. Y. , Ramis R. , Zhang J.
Published: January 2024

The Rayleigh–Taylor (RT) instability has been a great challenge for robust fusion ignition. In this paper, the evolution of the RT instability at the fuel inner interface during the coasting phase is investigated for the central ignition scheme [Hurricane et al., Rev Mod Phys. 95, 025005 (2023)] and the double-cone ignition (DCI) scheme [Zhang et al., Philos. Trans. R. Soc. A. 378, 20200015 (2020)]. It is found that the spherical convergent effect can be helpful for smoothing the disturbance by merging the spikes in the azimuthal direction. For the DCI scheme, the pressure gradient in the same direction with the density gradient at the fuel inner interface can further prevent the disturbance from growing. For the example case with an initial disturbance amplitude as large as 20 μm, the DCI scheme can still reach a high-density isochoric plasma with an areal density of 2.18 g/cm2 at the stagnation moment, providing favorable conditions for fast ignition by the relativistic electron beam.
Coupled-cluster theory for trapped bosonic mixtures
Authors: Bhowmik Anal , Alon Ofir E.
Published: January 2024

We develop a coupled-cluster theory for bosonic mixtures of binary species in external traps, providing a promising theoretical approach to demonstrate highly accurately the many-body physics of mixtures of Bose–Einstein condensates. The coupled-cluster wavefunction for the binary species is obtained when an exponential cluster operator eT, where T = T(1) + T(2) + T(12) and T(1) accounts for excitations in species-1, T(2) for excitations in species-2, and T(12) for combined excitations in both species, acts on the ground state configuration prepared by accumulating all bosons in a single orbital for each species. We have explicitly derived the working equations for bosonic mixtures by truncating the cluster operator up to the single and double excitations and using arbitrary sets of orthonormal orbitals for each of the species. Furthermore, the comparatively simplified version of the working equations are formulated using the Fock-like operators. Finally, using an exactly solvable many-body model for bosonic mixtures that exists in the literature allows us to implement and test the performance and accuracy of the coupled-cluster theory for situations with balanced as well as imbalanced boson numbers and for weak to moderately strong intra- and interspecies interaction strengths. The comparison between our computed results using coupled-cluster theory with the respective analytical exact results displays remarkable agreement exhibiting excellent success of the coupled-cluster theory for bosonic mixtures. All in all, the correlation exhaustive coupled-cluster theory shows encouraging results and could be a promising approach in paving the way for high-accuracy modeling of various bosonic mixture systems.
Defect-dependent environmental stability of high mobility transparent conducting In-doped CdO
Authors: Wu Shan , Zha Shen Jie , Zhang Yang , Liu Gui Shan , Chen Xiong Jing , Li Zhan Hua , Ho Chun Yuen , Deng Bei , Yu Kin Man , Liu Chao Ping
Published: January 2024

Highly degenerate n-type CdO with high electron mobility is a promising transparent conducting oxide (TCO) for optoelectronic devices utilizing a spectrum in the Vis-NIR range. In particular, it has been shown that doped CdO thin films can show much superior transparency of >80% in the NIR region compared to conventional transparent conducting oxide (e.g., Sn-doped In2O3) thin films with a similar sheet resistance. However, CdO thin films typically experience rapid degradation in their electron mobilities when exposed to environmental conditions with H2O moisture. Here, we studied the effects of thermal annealing on the environmental stability of In-doped CdO (CdO:In) using a combination of different analytical techniques. CdO:In thin films with different In concentration (0%–8.3%) synthesized by magnetron sputtering were subjected to different post-thermal annealing (PTA) and then aged in different environmental conditions with varying relative humidity (RH) in the range of 0%–85%. Our results reveal that the degradation of CdO:In thin films can be primarily attributed to the oxygen vacancy-related defects at the grain boundaries, which can readily react with the OH− in the moisture. The moisture induced degradation can be mitigated by appropriate PTA at high temperatures (>400 °C) where grain boundary defects, primarily associated with Cd vacancies, can be passivated through hydrogen (H), thus enhancing their environmental stability. The present study provides a comprehensive understanding of the instability mechanisms and defect passivation in transparent conducting CdO:In thin films, which can also be relevant for other wide gap oxides.
Brownian dynamics simulations of bottlebrush polymers in dilute solution under simple shear and uniaxial extensional flows
Authors: Dutta Sarit , Sing Charles E.
Published: January 2024

We study the dynamics of bottlebrush polymer molecules in dilute solutions subjected to shear and uniaxial extensional flows using Brownian dynamics simulations with hydrodynamic interaction (HI). Bottlebrush polymers are modeled using a coarse-grained representation, consisting of a set of beads interacting pairwise via a purely repulsive potential and connected by finitely extensible nonlinear springs. We present the results for molecular stretching, stress, and solution viscosity during the startup of flow as well as under steady state as a function of side chain length while keeping the backbone length fixed. In extensional flow, the backbone fractional extension and the first normal stress difference decrease with an increase in side chain length at a fixed Weissenberg number (Wi). Using simulation results both in the presence of and in the absence of HI, we show that this is primarily a consequence of steric interaction resulting from the dense grafting of side chains. In shear flow, we observe a shear-thinning behavior in all cases, although it becomes less pronounced with increasing side chain length. Furthermore, nonmonotonicity in the backbone fractional extension is observed under shear, particularly at high Wi. We contextualize our simulation results for bottlebrush polymers with respect to existing studies in the literature for linear polymers and show that the unique dynamical features characterizing bottlebrush polymers arise on account of their additional molecular thickness due to the presence of densely grafted side chains.
Simulations of three-layer Richtmyer–Meshkov mixing in a shock tube
Authors: Sadler James D. , Powell Philip D. , Schalles Mark , Louie Carlton , Jacobs Jeffrey W. , Zhou Ye
Published: January 2024

The Richtmyer–Meshkov instability causes perturbations to grow after a shock traverses a fluid density interface. This increases the mixing rate between fluid from either side of the interface. We use the Flash Eulerian hydrodynamic code to investigate alterations when a thin third layer of intermediate density is placed along the interface, effectively creating two adjacent unstable interfaces. This is a common occurrence in engineering applications where a thin barrier initially separates two materials. We find that the width of the mixing layer is similar or slightly reduced; however, the total mass of mixed material can actually increase. The mixing layer becomes more compact and efficient. However, the normalized mixed mass decreases, meaning that finger entrainment becomes more important than in the simple two-layer case. The effect of adding the central layer appears to decrease when the Atwood number is decreased. The Flash results are also benchmarked against two-layer experimental data from a shock tube at the University of Arizona.
Atomic insights into the optoelectronic properties of vacancy-ordered double perovskite halide semiconductors
Authors: Liu Yongsi , Zhou Junjie , Guan Yinglin , Xiao Ye , Dong Huafeng , Wu Fugen , Huang Le
Published: January 2024

Vacancy-ordered halide perovskite Cs2BX6 semiconductors are attracting an increasing level of interest for optoelectronic applications due to their high chemical stability and unique light emission properties. Here, we performed first-principles calculations to determine the energy positions and atomic orbital hybridization features of band edge states in Cs2BX6 (B = Ge, Sn, Te, Ti, Zr, Hf; X = Cl, Br, I). Our results revealed that all the Cs2BX6 perovskites, except for Cs2TeX6, have direct bandgaps at the Γ point. The indirect bandgaps of Cs2TeX6 originate from the symmetry-forbidden Te p–X p coupling at the Γ point. Both energy positions and dispersions of the band edge states of Cs2BX6 can be well modulated by varying X- and B-site ions. Our work provides a comprehensive understanding of electronic structures and optoelectronic properties of Cs2BX6 perovskites, shedding light on the design rules for high-performance perovskite optoelectronics.
Active search for a reactive target in thermal environments
Authors: Go Byeong Guk , Jeon Euijin , Kim Yong Woon
Published: January 2024

We study a stochastic process where an active particle, modeled by a one-dimensional run-and-tumble particle, searches for a target with a finite absorption strength in thermal environments. Solving the Fokker–Planck equation for a uniform initial distribution, we analytically calculate the mean searching time (MST), the time for the active particle to be finally absorbed, and show that there exists an optimal self-propulsion velocity of the active particle at which MST is minimized. As the diffusion constant increases, the optimal velocity changes from a finite value to zero, which implies that a purely diffusive Brownian motion outperforms an active motion in terms of searching time. Depending on the absorption strength of the target, the transition of the optimal velocity becomes either continuous or discontinuous, which can be understood based on the Landau approach. In addition, we obtain the phase diagram indicating the passive-efficient and the active-efficient regions. Finally, the initial condition dependence of MST is presented in limiting cases.
Perspective on defect characterization in semiconductors by positron annihilation spectroscopy
Authors: Makkonen Ilja , Tuomisto Filip
Published: January 2024

This Perspective focuses on experimental and theoretical aspects of positron annihilation spectroscopy. This set of methods is highly suitable for identifying and quantifying vacancy-type defects in semiconductors and also allows for analyzing their physics characteristics. We present selected examples from the past decade, where the methods have been used for obtaining timely and useful insights into the defect-controlled phenomenon in narrow-gap (Ge, GaSb) and wide-gap (III-nitride, oxide) semiconductors. We also discuss possible future developments that may allow more detailed studies in novel semiconductor materials and devices with ever more complex lattice structures.
The effects of dynamic stalls on the aerodynamics and performance of a Darrieus rotor during self-start
Authors: Selvarajoo Shaza Rae , Mohamed-Kassim Zulfaa
Published: January 2024

Darrieus turbines face difficulty to self-start, especially in environments with fluctuating inflows that cause them to deviate repeatedly from their designed operating parameters. To elucidate the self-starting process in this study, a three-bladed Darrieus rotor was simulated numerically with vector diagrams to facilitate visualizations on the rotor behaviors. Based on segments of the average rotor torque coefficients (Cτ), the self-starting process consisted of linear and accelerated phases, with the first two segments in the linear phase and the next two segments in the accelerated phase. The simulation showed that the self-starting process was largely influenced by dynamic stalls. The rotor experienced difficulty to self-start in the first segment as it encountered a region of “dead band” with a negative mean cyclical caused by a reverse dynamic stall. This dynamic stall and its corresponding dead band disappeared in the second segment, which initiated the transition into the accelerated phase. In the third segment, forward dynamic stalls that formed boosted the generation and accelerated the angular speed of the rotor toward its peak. Finally, without any dynamic stalls formed in the fourth segment due to reduced values of the inflow angles on the blades, they reduced drastically until the rotor reached its steady phase. Outcomes from this work demonstrate that understanding the effects of unsteady aerodynamics is vital to improving the self-starting process. Potential design improvements on the rotor that address this aspect include static and dynamic pitching, blade flaps, intracyclical control, and flow controls using blowing and suction mechanisms.
Generalized wall-modeled large eddy simulation model for industrial applications
Authors: Amatriain Aitor , Gargiulo Corrado , Rubio Gonzalo
Published: January 2024

In this work, a generalized wall-modeled large eddy simulation model (GWMLES) is presented. An extended formulation of the classical WMLES approach is proposed that also enables the modeling of the entire log-layer by using a Reynolds-averaged Navier–Stokes (RANS) model. GWMLES is validated against direct numerical simulations, large eddy simulations (LES), WMLES, hybrid RANS/LES, unsteady RANS (URANS), and experimental data of test cases featuring industrial flows. It is demonstrated that GWMLES does not share the main shortcoming of current WMLES models. When the entire log-layer is solved with a RANS model, GWMLES gives a level of accuracy similar to recent LES results, as well as computational cost savings that are proportional to the Reynolds number in wall-bounded flows. The model shows superior performance than URANS even when the resolved portion of the energy spectrum is reduced. Motivated by the different time scales of the flow and RANS variables, it requires approximately 30% lower computational costs than the detached eddy simulation family models in the turbulent flows considered. These features represent significant advancements in the simulation of wall-bounded flows at high Reynolds numbers, particularly in industrial applications.
Investigation of flow characteristics and velocity fields of excited two parallel plane jets
Authors: Kumar Sanjay , Murugan Sudharson
Published: January 2024

An experimental investigation was conducted to study the flow characteristics and velocity fields of excited two parallel plane jets. The experiments were carried out at a jet Reynolds number of 200. A loudspeaker system was used to create the jets pulsation and to vary the intensity of jet pulsations at a constant excitation frequency of 40 Hz. A hot-wire anemometer was used to measure the velocities of the jets as they exited. The flow patterns were visualized using a laser-light sheet technique combined with smoke flow visualization. The jet spread widths were determined from images taken with a long-exposure method using binary edge detection. A particle image velocimetry measurement technique was used to render the flow field behaviors of the parallel jets. The introduction of jet pulsation by the speaker led to the roll-up of coherent vortices along the shear layers of the jets. These vortices became more prominent as the intensity of jet pulsations increased. These coherent vortices broke apart into turbulent eddies, resulting in wider jet spread with higher pulsation intensities. Two counter-rotating vortices were detected at the jet exit. These vortices moved closer to the jet exits as the jet pulsation intensity was increased. The intensity of turbulence and the presence of vortices were both influenced by the magnitude of the jet pulsation. Greater jet pulsation led to higher turbulence levels, a more pronounced vorticity field, and a more efficient transfer of momentum, consequently enhancing the mixing process.
The impact of electron beams on the arbitrary amplitude electron–acoustic solitons in a nonthermal plasma
Authors: Alyousef Haifa A. , Naeem S. Neelam , Irshad M. , Ata-ur-Rahman  , Ismaeel Sherif M. E. , El-Tantawy S. A.
Published: January 2024

This study examines the nonlinear dynamics of high-frequency electron–acoustic waves (EAWs) in a collisionless, unmagnetized plasma consisting of several components, including inertial cold electrons, an inertial electron beam, and inertialess Cairns-distributed hot electrons in addition to background stationary ions. We use a nonlinear pseudopotential (Sagadeev potential) method to investigate the possibility of stationary-profile electron–acoustic solitons (EASs). In this study, the nonthermal parameter, the temperature ratio between hot and cold electrons, density ratios, and electron beam parameters are carefully examined to see how they change the features of EASs. As the nonthermality of hot electrons rises, the beam speed decreases, the density ratio of the beam to the cold electron increases, and the existence domain for EASs gets bigger. The current theoretical model shows a link between the wideband noise seen in Geotail satellites and the plasma sheet boundary layer in Earth's magnetosphere.
The impact of laser lift-off with sub-ps pulses on the electrical and optical properties of InGaN/GaN light-emitting diodes
Authors: Wolter Stefan , Bornemann Steffen , Waag Andreas
Published: January 2024

Laser lift-off (LLO) is an important step in the processing chain of nitride-based light-emitting diodes (LEDs), as it enables the transfer of LEDs from the growth substrate to a more suitable carrier. A distinctive feature of LLO with ultrashort pulses is the ability to use either above- or below-bandgap radiation, since nonlinear absorption becomes relevant for ultrashort pulses. This study addresses the differences in the absorption scheme for below- and above-bandgap radiation and investigates the electrical and optical properties of InGaN/GaN LEDs before and after LLO with 347 and 520 nm laser light via current–voltage and power- as well as temperature-dependent photoluminescence measurements. LLO could be successfully realized with both wavelengths. The threshold fluence required for LLO is about a factor of two larger for 520 nm compared to that for 347 nm. Furthermore, an increase in leakage current by several orders of magnitude and a significant decrease in efficiency with laser fluence are observed for below-bandgap radiation. In contrast, leakage current hardly increases and efficiency is less dependent on the laser fluence for samples lifted with 347 nm. This degradation is ascribed to the absorption of laser light in the active region, which facilitates a modification of the local defect landscape. The effect is more severe for below-bandgap radiation, as more laser light penetrates deep into the structure and reaches the active region. Ultimately, we show that LEDs lifted with ultrashort laser pulses can exhibit good quality, making ultrashort pulse LLO a viable alternative to conventional LLO with nanosecond pulses.
Machine learning classification of cellular states based on the impedance features derived from microfluidic single-cell impedance flow cytometry
Authors: Wei Jian , Gao Wenbing , Yang Xinlong , Yu Zhuotong , Su Fei , Han Chengwu , Xing Xiaoxing
Published: January 2024

Mitosis is a crucial biological process where a parental cell undergoes precisely controlled functional phases and divides into two daughter cells. Some drugs can inhibit cell mitosis, for instance, the anti-cancer drugs interacting with the tumor cell proliferation and leading to mitosis arrest at a specific phase or cell death eventually. Combining machine learning with microfluidic impedance flow cytometry (IFC) offers a concise way for label-free and high-throughput classification of drug-treated cells at single-cell level. IFC-based single-cell analysis generates a large amount of data related to the cell electrophysiology parameters, and machine learning helps establish correlations between these data and specific cell states. This work demonstrates the application of machine learning for cell state classification, including the binary differentiations between the G1/S and apoptosis states and between the G2/M and apoptosis states, as well as the classification of three subpopulations comprising a subgroup insensitive to the drug beyond the two drug-induced states of G2/M arrest and apoptosis. The impedance amplitudes and phases used as input features for the model training were extracted from the IFC-measured datasets for the drug-treated tumor cells. The deep neural network (DNN) model was exploited here with the structure (e.g., hidden layer number and neuron number in each layer) optimized for each given cell type and drug. For the H1650 cells, we obtained an accuracy of 78.51% for classification between the G1/S and apoptosis states and 82.55% for the G2/M and apoptosis states. For HeLa cells, we achieved a high accuracy of 96.94% for classification between the G2/M and apoptosis states, both of which were induced by taxol treatment. Even higher accuracy approaching 100% was achieved for the vinblastine-treated HeLa cells for the differentiation between the viable and non-viable states, and between the G2/M and apoptosis states. We also demonstrate the capability of the DNN model for high-accuracy classification of the three subpopulations in a complete cell sample treated by taxol or vinblastine.
An immersed boundary method for the thermo–fluid–structure interaction in rarefied gas flows
Authors: Wang Li , Young John , Tian Fang-Bao
Published: January 2024

An immersed boundary method for the thermo–fluid–structure interaction in rarefied gas flows is presented. In this method, the slip model is incorporated with the penalty feedback immersed boundary method to address the velocity and temperature jump conditions at the fluid–structure interface in rarefied gas flows within the slip-flow regime. In addition, the compressible flows governed by the Navier–Stokes equations are solved by using a high-order finite difference method; the elastic solid is solved by using the finite element method; the fluid and solid dynamics are solved independently, and the thermo–fluid–structure interaction is achieved by using a penalty feedback method in a partitioned way. To model the local rarefaction in the supersonic flow, an artificial viscosity is proposed by introducing the local Knudsen number to diffuse the sharp transition at the shock wave front. Several validations are conducted: the Poiseuille flow in a channel, the flow around a two-dimensional airfoil, a moving square cylinder in a channel, the flow around a sphere, and a moving sphere in quiescent flow. The numerical results from the present method show very good agreements with the previous published data obtained by other methods, confirming the good ability of the proposed method in handling the thermo–fluid–structure interaction in both weakly and highly compressible rarefied gas flows. Inspired by the micro/unmanned aerial vehicles in Martian exploration, the proposed method is applied to the aerodynamics of a flapping wing in rarefied gas flows in both two-dimensional and three-dimensional spaces to demonstrate the versatility of the proposed method for modeling flows involving large deformation and fluid–structure interaction.
Modular supersonic nozzle for the stable laser-driven electron acceleration
Authors: Lei Zhenzhe , Jin Zhan , Gu Yan-Jun , Sato Shingo , Zhidkov Alexei , Rondepierre Alexandre , Huang Kai , Nakanii Nobuhiko , Daito Izuru , Kando Masaki , Hosokai Tomonao
Published: January 2024

The sharp density down-ramp injection (shock injection) mechanism produces the quasi-monoenergetic electron beam with a bunch duration of tens of femtoseconds via laser wakefield acceleration. The stability of the accelerated electron beam strongly depends on the stability of the laser beam and the shock structure produced by the supersonic gas nozzle. In this paper, we report the study of a newly designed modular supersonic nozzle with a flexible stilling chamber and a converging–diverging structure. The performance of the nozzle is studied both numerically and experimentally with the computational fluid dynamics simulation and the Mach–Zehnder interferometry method. The simulation results and the experimental measurements are well consistent, and both prove the effectiveness of the stilling chamber in stabilizing the gas flow.
Effect of scattered/diffuse flux on the phototactic bioconvection in the absence of collimated flux
Authors: Rajput S. K. , Panda M. K.
Published: January 2024

The main objective of this paper is to investigate the impact of diffuse/scattered flux in the absence of collimated flux on the stability of an isotropic scattering algal suspension. The linear stability analysis predicts an unstable mode of disturbance shifts from a non-oscillatory (an overstable) to an overstable (a non-oscillatory) state at the variation of diffuse flux for fixed parameters at the bioconvective instability. However, overstable solutions are observed only at the higher cell swimming speed and a higher extinction coefficient. The critical Rayleigh number increases as the magnitude of diffuse flux intensifies. This indicates that a suspension illuminated by higher levels of diffuse flux is more stable. Furthermore, the lower (higher) swimming speed enhances (diminishes) the suspension's stability, especially in low (high) light conditions. Also, the horizontal component of swimming orientation becomes more influential with a higher level of diffuse flux, particularly at smaller pattern wavelengths, resulting in behavior akin to gyrotaxis in certain instances.
Sensor placement for data assimilation of turbulence models using eigenspace perturbations
Authors: Bidar O. , Anderson S. R. , Qin N.
Published: January 2024

We present an approach to sensor placement for turbulent mean flow data assimilation in the context of Reynolds-averaged Navier–Stokes (RANS) simulations. It entails generating a spatial uncertainty map through the eigenspace perturbations (ESPs) of the baseline turbulence model (e.g., the k−ω shear stress transport model) to quantify the epistemic structural errors in the model. A novel greedy search algorithm is proposed to place sensors targeting regions of highest uncertainty in the spatial uncertainty map generated from ESP. The algorithm is computationally efficient (e.g., computational cost negligible compared to a RANS solution) and is both easy to implement and tune. It involves two hyper-parameters (a constraint to avoid sensor clustering and the number of sensors) which we investigate in-depth. A variational (adjoint-based) data assimilation approach is used for flow reconstruction. The proposed strategy was tested on three two-dimensional wall-bounded flows (Reynolds number ranging 5.6×103–9.36×105) involving flow separation and reattachment. For the wall-mounted hump case, we found that data assimilation using 33 sensors with our proposed sensor placement algorithm reduced the average velocity prediction error by 60% vs 38% with a simple uniform placement of sensors. Furthermore, we found that we could achieve 61% error reduction using our algorithm with only three sensors. Notably, in all tested cases, the error reduction using our method for sensor placement was close in accuracy to the instances where the entire flow field data were used for flow reconstruction, which involved two to three orders of magnitude more data points than the placed sensors.
A volume of fluid based method for consistent flux computation in large-density ratio two-phase flows and its application in investigating droplet bag breakup behavior
Authors: Liu Cheng , Gao Ruoqing , Chai Bing , Hu Changhong
Published: January 2024

This article introduces a novel method for computing consistent fluxes, which enables highly robust simulations of two-phase flow problems characterized by large-density ratios. The approach is based on the geometric reconstruction volume of fluid method and utilizes a staggered grid implementation. This allows for accurate and robust simulation of phenomena like droplet bag breakup in flows with intense velocity shear and significant density differences. Through numerical experiments, it has been demonstrated that this method can reliably simulate two-phase flows with large-density ratios while preserving excellent energy conservation properties. Expanding on these findings, the researchers have developed a solver that leverages block-structured adaptive mesh to perform high-fidelity simulations of droplet bag breakup scenarios. Remarkably, this solver accurately reproduces three distinct breakup patterns: bag mode, stamen mode, and sheet-stripping mode. A comprehensive analysis has also been conducted by comparing the dimensionless maximum cross-stream radius with experimental test results. Furthermore, the study investigates the kinetic energy spectrum of fully developed two-phase turbulence under different droplet generation mechanisms and examines the distribution of droplet sizes. The numerical results validate the efficacy and reliability of this method in accurately simulating two-phase flows characterized by significant density disparities and interface momentum exchange.
Gate-controlled near-surface Josephson junctions
Authors: Olausson L. , Olausson P. , Lind E.
Published: January 2024

Gate-tunable Josephson junctions are interesting for quantum technology applications, such as gatemon qubits and topological Majorana-based qubits. Furthermore, high-frequency compatible geometries can be utilized for implementing electrically pumped parametric amplifiers. In this paper, we combine processing, measurements, and modeling of near-surface InGaAs Josephson field-effect transistors in order to facilitate circuit simulations of actual non-ideal devices. We developed a compact model using Verilog-A and confirmed the validity of our model by accurately reproducing our measured data by circuit simulations in Advanced Design System. From the circuit simulations, an effective gate-dependent transmission coefficient, with a peak value of ∼ 3.5%, was extracted, mainly limited by contact transparency.
Inverse dynamic defect annealing in ZnO
Authors: Azarov Alexander , Galeckas Augustinas , Wendler Elke , Monakhov Eduard , Kuznetsov Andrej
Published: January 2024

Radiation tolerance of semiconductors depends on the dynamic defect annealing efficiency during irradiation. Consequently, it matters at what temperature one keeps the sample during irradiation, so that elevated temperatures typically result in lower remaining disorder. In the present work, we observed an opposite trend for the nitrogen ion implants into zinc oxide. Combining ion channeling technique, x-ray diffraction, and photoluminescence spectroscopy, we demonstrate that the interaction of nitrogen with radiation defects promotes an inverse dynamic annealing process, so that the increase in irradiation temperature leads to a more efficient defect formation. As a result, the residual radiation disorder is maximized at 650 °C and this state is characterized by the appearance of prominent optical signatures associated with zinc interstitials and strongly reduced strain accumulation as compared to the samples implanted at lower temperatures. However, for higher implantation temperatures, the impact of the inverse annealing decreases correlating with the surface degradation and loss of nitrogen.
Non-Hermitian extended midgap states and bound states in the continuum
Authors: Zelenayova Maria , Bergholtz Emil J.
Published: January 2024

We investigate anomalous localization phenomena in non-Hermitian systems by solving a class of generalized Su–Schrieffer–Heeger/Rice–Mele models and by relating their provenance to fundamental notions of topology, symmetry-breaking, and biorthogonality. We find two types of bound states in the continuum, both stable even in the absence of chiral symmetry: the first being skin bulk states, which are protected by the spectral winding number. The second type is constituted by boundary modes associated with a quantized biorthogonal polarization. Furthermore, we find an extended state stemming from the boundary state that delocalizes while remaining in the gap at bulk critical points. This state may also delocalize within a continuum of localized (skin) states. These results clarify fundamental aspects of topology and symmetry in light of different approaches to the anomalous non-Hermitian bulk-boundary correspondence and are of direct experimental relevance for mechanical, electrical, and photonic systems.
Highly efficient superradiant oscillator with front-extraction output in TE11 mode operating at low magnetic field
Authors: Wang Jiaoyin , Li Tianming , Cheng Renjie , Wu Ping , Xiao Renzhen , Cao Yibing , Wang Haiyang , Li Hao , Zhou Yihong , Hu Biao
Published: January 2024

With a low guiding magnetic field, a highly efficient X-band coaxial superradiant relativistic backward wave oscillator (SR-RBWO) with a front-extraction cavity and a built-in mode converter is proposed in this paper. The coaxial structure is used to reduce the guiding magnetic field of the intense relativistic electron beam. To decrease the transmission loss of microwave power in the slow wave structure (SWS), a front-extraction cavity is introduced. The inner conductor of the coaxial SWS is hollowed out as the output waveguide, and then, the microwave is extracted by the front-extraction cavity and enters the hollow waveguide rather than re-enter the SWS to output. With this improvement, the power conversion factor K can be increased by 0.44 even more. Making use of the feature of longer SWSs of SR-RBWOs, a built-in mode converter is designed, which can convert the circular TM01 mode propagating in the output waveguide into the circular TE11 radiation mode that can be radiated into free space directly. Therefore, the length of the radiation system can be reduced significantly, which is beneficial to the miniaturization of the entire high-power microwave system. Particle-in-cell simulation demonstrates that with a diode voltage of 180 kV and a guiding magnetic field of 0.37 T, the output SR pulse with an average power of 1.00 GW corresponding to power conversion factor K = 1.8 can be obtained.
A normal-mode approach for high-speed rarefied plane Couette flow
Authors: Zou Sen , Bi Lin , Zhong Chengwen , Yuan Xianxu , Tang Zhigong
Published: January 2024

Based on gas kinetic theory, a linear stability analysis method for low-speed rarefied flows was developed by Zou et al. [“A new linear stability analysis approach for microchannel flow based on the Boltzmann Bhatnagar–Gross–Krook equation,” Phys. Fluids 34, 124114 (2022) and “A novel linear stability analysis method for plane Couette flow considering rarefaction effects,” J. Fluid Mech. 963, A33 (2023)]. In the present study, we extended the method to high-speed rarefied flows using the Bhatnagar–Gross–Krook model. The Chebyshev spectral method is employed to discretize physical space, and the Gauss–Hermite and fourth-order Newton–Cotes quadrature methods are used to discretize velocity space. The fourth-order Newton–Cotes quadrature method was found to have sufficient accuracy for the stability analysis, laying the foundation for future research on hypersonic flows. The stability analysis of compressible rarefied Couette flow showed that acoustic modes are reflected between the wall and the relative sonic line, and the variation in their phase speed and growth rate with the wavenumber is not affected by the Mach number (Ma) and the Knudsen number (Kn). Increasing Kn has a stabilizing effect on both the acoustic and viscous modes, but as Ma increases, the attenuation rate of each mode's growth rate gradually decreases. In subsonic and sonic flows, the least stable viscous mode dominates in the case of small numbers. As Kn increases, the viscous mode gradually dominates over all wavenumber ranges considered in subsonic flow. In sonic flow, mode 1 is dominant in the region beyond the range of small wavenumbers. In supersonic flow, mode 2 is the least stable in the large wavenumber ranges, while mode 1 is the least stable in other wavenumber ranges. At a fixed wavenumber, as Kn increases, the decay rate of the growth rate of mode 2 is the highest. Additionally, under different Knudsen numbers, the growth rates of mode 1, mode 2, and the least stable viscous mode monotonically increase with an increase in Ma, with mode 2 showing the most significant increase.
The overlooked role of excited anion states in NiO2− photodetachment
Authors: Hart C. Annie , Schlimgen Anthony W. , Dao Diep Bich , Head-Marsden Kade , Mabbs Richard
Published: January 2024

Photodetachment spectra of anionic species provide significant insights into the energies and nature of ground and excited states of both the anion and resultant neutral molecules. Direct detachment of the excess electron to the continuum may occur via formally allowed or forbidden transitions (perhaps as the result of intensity borrowing through vibronic coupling). However, alternate indirect pathways are also possible and often overlooked. Here, we report a two-dimensional photoelectron spectral study, combined with correlated electronic structure calculations, to elucidate the nature of photodetachment from NiO2−. The spectra are comprised of allowed and forbidden transitions, in excellent agreement with previously reported slow electron velocity mapped imaging spectra of the same system, which were interpreted in terms of direct detachment. In the current work, the contributions of indirect processes are revealed. Measured oscillations in the branching ratios of the spectral channels clearly indicate non-direct detachment processes, and the electronic structure calculations suggest that excited states of the appropriate symmetry and degeneracy lie slightly above the neutral ground state. Taken together, the results suggest that the origin of the observed forbidden transitions is the result of anion excited states mediating the electron detachment process.