Physical Reasons Research Articles

A global climatology of sting-jet extratropical cyclones

Abstract. Sting jets have been identified in the most damaging extratropical cyclones impacting northwest Europe. Unlike the cold conveyor belt and other long-lived cyclone wind jets, sting jets can lead to regions of exceptionally strong near-surface winds and damaging gusts over just a few hours and with much smaller wind “footprints”. They descend into the frontal-fracture region found in warm-seclusion cyclones. Previous research has focused almost exclusively on North Atlantic–European cyclones, but there are no known physical reasons why sting jets should not develop elsewhere, and recognition of their existence can inform weather nowcasting and wind warnings. We have produced the first climatology of sting-jet cyclones over the major ocean basins. A sting-jet precursor diagnostic has been applied to more than 10 000 warm-seclusion cyclones in the top intensity decile, tracked using 43 extended winters of ERA5 reanalysis data. Cyclones with sting-jet precursors are found to occur over the North Pacific and Southern oceans for the first time, and they are more prevalent in the Northern Hemisphere (27 % of all top decile cyclones) compared to the Southern Hemisphere (15 %). These cyclones have distinct characteristics to those without the precursor, including initiating closer to the Equator, deepening faster in mean-sea-level pressure (MSLP), and having stronger near-surface winds, even in the reanalysis data that are too coarse to fully resolve sting jets. Composite analysis reveals systematic differences in structural evolution, including in potential vorticity (PV) and jet crossing. These differences evidence the climatological consequences of strong diabatic cloud processes on cyclone characteristics, implying that sting jets are likely to be enhanced by climate change.

Multivalued dispersion equation for coupling between plasmons and surface optical phonons in a graphene/polar-substrate system

Dispersion equations are a common paradigm of collective excitation physics. However, in some systems, dispersion equations contain multivalued functions and their solutions are ambiguous. As an example, we consider graphene on a polar substrate where Dirac plasmons are coupled with surface optical phonons. The dispersion equation for this system contains square-root singularity. Using the initial value problem resolves this uncertainty and gives a unique solution. Particularly, we found that the lower plasmon-phonon mode, which in terms of dispersion can have a good quality factor, is almost absent in excitation spectra. The physical reason and experimental evidence of the mode collapse are discussed. Published by the American Physical Society 2024

Binding Energy of Cylindrical Quantum Dots: Effects of External Electric Field and Impurity Position

We have investigated the binding energy properties of a cylindrical quantum dot (CQD) system layered as GaAs/AlGaAs under external electric fields. In our numerical calculations, we considered both on- and off-center impurity cases using the effective mass approximation. The eigenvalues and corresponding eigenfunctions of the system are obtained using a three-dimensional finite difference approach. It is found that the ground-state binding energy is significantly affected by the CQD dimensions (radius and height), impurity position, and the strength and direction of the external electric field. Additionally, the electron probability distributions are examined to provide deeper insight into the physical reasons underlying the behavior of the binding energy. These findings enhance our understanding of the tunable properties of CQDs, which may be useful in the design of optoelectronic and quantum devices.

Performance assessment of Savonius wind turbine: Impact of the cylindrical deflectors with natural shapes

Savonius wind turbine, with various advantage features, is expanding its application for energy harvesting in urban and offshore environments. However, the drawback of this turbine relies on its relatively low aerodynamic efficiency. This study aims to enhance the Savonius wind turbine's aerodynamic performance to expand its effective application in urban areas and reduce offshore wind energy costs by using multiple cylindrical deflectors with natural geometry, changing from square to circular shapes. Results from the sequence of two-dimensional (2D) unsteady computational fluid dynamics (CFD) simulations show various performances gained depending on the deflector shapes. The highest power coefficient, with an increment of up to 133% over the turbine without the deflectors without the complex structure and the requirement of the rotated cylinder, is attained with the square cylindrical one at different wind conditions. The insight flow analysis reveals that the high jet flow formed between the turbine and the deflectors is the physical reason behind such improvement, through adding more positive pressure force on the advancing blade while increasing the recovery pressure on the concave side of the returning one. The results suppose the significance of the present study with a simple wind turbine-deflector configuration for high energy harvesting in urban and offshore environments with effective costs.

The minimal flow unit and origin of two-dimensional elasto-inertial turbulence

The research on elasto-inertial turbulence (EIT), a new type of turbulent flow, has reached the stage of identifying the minimal flow unit (MFU). On this issue, direct numerical simulations of FENE-P fluid flow in two-dimensional channels with variable sizes are conducted in this study. We demonstrate with the increase of channel length that the simulated flow experiences several different flow patterns, and there exists an MFU for EIT to be self-sustained. At Weissenberg number ( $Wi$ ) higher than the one required to excite EIT, when the channel length is relatively small, a steady arrowhead regime (SAR) flow structure and a laminar-like friction coefficient is achieved. However, as the channel length increases, the flow can fully develop into EIT characterized with high flow drag. Close to the size of the MFU, the simulated flow behaves intermittently between the SAR state with low drag and EIT state with high drag. The flow falling back to ‘laminar flow’ is caused by the insufficient channel size below the MFU. Furthermore, we give the relationship between the value of the MFU and the effective $Wi$ , and explain its physical reasons. Moreover, the intermittent flow regime obtained based on the MFU gives us an opportunity to look into the origin and exciting process of EIT. Through capturing the onset process of EIT, we observed that EIT originates from the sheet-like extension structure located near the wall, which is maybe related to the wall mode rather than the centre mode. The fracture and regeneration of this sheet-like structure is the key mechanism for the self-sustaining of EIT.

Heterogeneity in the level of dementia literacy among community doctors in China: A latent profile analysis.

This study aimed to explore the heterogeneity of community doctors based on their knowledge of dementia and the potential factors associated with their dementia literacy. A total of 1288 community doctors completed the Alzheimer disease knowledge scale (ADKS) in a cross-sectional study conducted between December 2021 and January 2022. We used latent class analysis (LCA) to explore potential clusters based on responses to the ADKS. Multivariate multinomial logistic regression analysis was performed to evaluate the associations between potential risk factors and the knowledge of community doctors. Community doctors were divided into four clusters according to their knowledge structure (Akaike information criterion (AIC) = 35672.83, Bayesian information criterion (BIC) = 36307.63, adjusted BIC (aBIC) = 35916.91, entropy = 0.814): the severity-focused subgroup (n = 269), the physical issues-focused group (n = 370), the knowledge uncertainty group (n = 191), and the general-focused group (n = 458). Age, education level, type of practice, and professional title were associated with the knowledge structure of Alzheimer's disease (AD). In addition, the perception that patients seek care in community health centres for physical reasons and community doctors' failure to manage patients with recently identified cognitive impairment were associated with the structures of the ADKS among community doctors (P < 0.05). There is heterogeneity in the level of AD knowledge among community doctors and their demographic characteristics, perceptions, and practices. Further efforts are needed to optimise the knowledge structure of dementia among community health care professionals.

Anomalous influence of electrode width on the critical current of Nb/Au Josephson junctions

Abstract We study the effect of electrodes width on superconducting current transport in Nb-Au-Nb Josephson bridges. The critical current as well as the normal bridge resistance drop with decreasing electrode width on scales of a few μm, which are orders of magnitude larger than the estimated coherence length of Au strip. We consider several physical reasons of such an anomalous influence of the width W of the superconducting electrode on the critical current Ic (AIWIc) and provide model fits for the resistive and superconducting properties of the bridges. {The smooth dependence of the Nb-Au-Nb bridge parameters on the electrode width can be used to optimize the design of superconducting devices for specific applications.

Can Deep Learning Search for Exceptional Chiroptical Properties? The Halogenated [6]Helicene Case

AbstractThe relationship between chemical structure and chiroptical properties is not always clearly understood. Nowadays, efforts to develop new systems with enhanced optical properties follow the trial‐error method. A large number of data would allow us to obtain more robust conclusions and guide research toward molecules with practical applications. In this sense, in this work we predict the chiroptical properties of millions of halogenated [6]helicenes in terms of the rotatory strength (R). We have used DFT calculations to randomly create derivatives including from 1 to 16 halogen atoms, that were then used as a data set to train different deep neural network models. These models allow us to i) predict the Rmax for any halogenated [6]helicene with a very low computational cost, and ii) to understand the physical reasons that favour some substitutions over others. Finally, we synthesized derivatives with higher predicted Rmax obtaining excellent correlation among the values obtained experimentally and the predicted ones.

Can Deep Learning Search for Exceptional Chiroptical Properties? The Halogenated [6]Helicene Case.

The relationship between chemical structure and chiroptical properties is not always clearly understood. Nowadays, efforts to develop new systems with enhanced optical properties follow the trial-error method. A large number of data would allow us to obtain more robust conclusions and guide research toward molecules with practical applications. In this sense, in this work we predict the chiroptical properties of millions of halogenated [6]helicenes in terms of the rotatory strength (R). We have used DFT calculations to randomly create derivatives including from 1 to 16 halogen atoms, that were then used as a data set to train different deep neural network models. These models allow us to i) predict the Rmax for any halogenated [6]helicene with a very low computational cost, and ii) to understand the physical reasons that favour some substitutions over others. Finally, we synthesized derivatives with higher predicted Rmax obtaining excellent correlation among the values obtained experimentally and the predicted ones.

Investigation of neutron irradiated W/CuCrZr joints

This study investigates the effects of neutron irradiation on tungsten (W) and copper-chromium-zirconium (CuCrZr) joints under conditions mimicking the high neutron flux environment of a tokamak fusion reactor. Samples of W/CuCrZr joints were subjected to irradiation in the Belgian Reactor 2 (BR2) nuclear reactor at SCK CEN (Belgian Nuclear Research Centre) to simulate the intense neutron exposure characteristic for International Thermonuclear Experimental Reactor (ITER) and DEMOnstration power plant reactor (DEMO) operations. The primary objective was to evaluate changes in the mechanical properties and microstructure of these materials, which are critical for their potential use in plasma-facing components.It is revealed that a significant reduction in tensile elongation of the joint, indicating some degree of embrittlement, is observed after the irradiation. Importantly, this effect is independent of the irradiation temperature. Possible physical reasons for the observed phenomenon are discussed.

Tuning polymer micelle size and dynamics with solvophobic block structure

Hypothesis: Micelles formed by copolymers with mixed solvophobic blocks have attracted much attention lately. It is expected that changing the mixed blocks sequence can be used as a tool to influence the micellization behavior in a way that is not equivalent to simply varying the incompatibility parameter for pure diblock-copolymers.Simulations: By using coarse-grained simulations, the micellization behavior of copolymers with twelve types of solvophobic blocks, which differed in the fraction f as well as the sequence of solvophilic units in the solvophobic blocks, was studied. To enable quantitative comparison of systems with different f, an “effective” incompatibility parameter was introduced.Findings: The micelles size distributions and dynamics were found to be significantly dependent on both f and the fine details of the sequence. When the solvophobic block sequences were obtained statistically using a model of copolymerization, a strong influence of the reactivity ratios on the resulting micelles was found. Even a moderate tendency to form gradient-like sequences resulted in a noticeable increase in the micelles size. The dynamic properties of the micelles were studied by investigating the rate at which the chains escape from them. The addition of soluble units into the solvophobic block was shown to dramatically decrease the tendency to form kinetically frozen states; gradient-like sequences demonstrated more sluggish dynamics. The physical reasons for the observed peculiarities are discussed in detail.

ON IONIZATION LOSS DISTRIBUTION OF RELATIVISTIC PARTICLES IN THIN DETECTORS

Ionization energy loss distribution of high-energy charged particles in thin detectors is considered. Its modification due to the fact that a part of δ-electrons, kicked out from the atoms by the incident particles, escape from the detector and do not dispose of all their kinetic energy inside it, is estimated and shown to be negligibly small. The physical reasons for this are discussed. The parameters responsible for the magnitude of this modification are obtained.

Utidelone plus pembrolizumab as the fourth-line combination treatment in non-small cell lung cancer with EGFR mutation: a case report.

Utidelone is an ebomycin derivative chemotherapeutic drug, which can promote tubulin polymerization and stabilize microtubule structure, so as to induce apoptosis. The drug is an innovative drug independently developed by China with independent intellectual property rights. Phase II clinical trials for advanced breast cancer are being approved by National Medical Products Administration for the treatment of advanced breast cancer. However, there is no report on the application in non-small cell lung cancer (NSCLC) patients with the epidermal growth factor receptor (EGFR) mutation. This case is a patient with EGFR mutant stage IV NSCLC who has progressed after third-line targeted therapy. The fourth line was treated with utidelone combined with pabolizumab. The patient had progressed after targeted therapy with oxitinib, ametinib, and vometinib. Due to the patient's physical reasons, the traditional platinum drugs were not suitable, so the patient was treated with utidelone combined with pabolizumab. The curative effect was evaluated as SD after two cycles and progesterone receptor after four cycles. At present, it is still in the maintenance of reduction of utidelone combined with pabolizumab, and the tumor continues to shrink. Although peripheral neurotoxicity occurred during treatment, it improved after symptomatic treatment. The treatment of EGFR mutant stage IV NSCLC with utidelone combined with pabolizumab has good effect and mild adverse reactions.

Perceptual and conceptual novelty independently guide infant looking behaviour: a systematic review and meta-analysis.

Human infants are born with their eyes open and an otherwise limited motor repertoire; thus, studies measuring infant looking are commonly used to investigate the developmental origins of perception and cognition. However, scholars have long expressed concerns about the reliability and interpretation of looking behaviours. We evaluated these concerns using a pre-registered ( https://osf.io/jghc3 ), systematic meta-analysis of 76 published and unpublished studies of infants' early physical and psychological reasoning (total n = 1,899; 3- to 12-month-old infants; database search and call for unpublished studies conducted July to August 2022). We studied two effects in the same datasets: looking towards expected versus unexpected events (violation of expectation (VOE)) and looking towards visually familiar versus visually novel events (perceptual novelty (PN)). Most studies implemented methods to minimize the risk of bias (for example, ensuring that experimenters were naive to the conditions and reporting inter-rater reliability). There was mixed evidence about publication bias for the VOE effect. Most centrally to our research aims, we found that these two effects varied systematically-with roughly equal effect sizes (VOE, standardized mean difference 0.290 and 95% confidence interval (0.208, 0.372); PN, standardized mean difference 0.239 and 95% confidence interval (0.109, 0.369))-but independently, based on different predictors. Age predicted infants' looking responses to unexpected events, but not visually novel events. Habituation predicted infants' looking responses to visually novel events, but not unexpected events. From these findings, we suggest that conceptual and perceptual novelty independently influence infants' looking behaviour.

Passivation mechanisms of oxygen-vacancy-induced hole traps by Mg acceptor atoms at GaN/SiO2 interface

Experiments in the past suggest that hole traps at GaN/SiO2 interfaces are reduced with heavily Mg-doped GaN epitaxial layers, but its physical origin is unclear. In this study, we use first-principles calculations to investigate interactions between substitutional Mg atoms at Ga sites (MgGa) and O vacancies (VO) in the nanometer-scale Ga-oxide (GaOx) interfacial layers, which are inevitably formed at GaN/SiO2 interfaces. We clarify the physical reason why Mg passivates hole traps. Our calculations show that MgGa and VO become stable by forming 2MgGa–VO complex in GaOx. In addition, while VO form deep hole traps in the bandgap of GaN, Mg attachment to VO makes the hole-trap level shift upward substantially and thus 2MgGa–VO induces no hole traps. These results indicate that hole traps originated from VO are passivated by the formation of a complex of MgGa atoms and VO.

Influence of Low-Energy High-Current Electron Beam Exposure on the Phase Composition and Corrosion Resistance of the AM60 Magnesium Alloy

The surface of an AM60 (Al – 5.5, Zn – 0.2, Cu – 0.009, Fe – 0.005, Si – 0.1; Ni – 0.002, Mn – 0.3 wt.%, Mg – the rest) magnesium alloy was exposed to a low-energy high-current electron beam. After the irradiation, the content of the β-phase (Mg17Al12) decreases and the aluminum content increases in the alloy surface layer. After the exposure to the electron beam, the corrosion resistance of the alloy in a 1-molar NaCl solution increases significantly compared to the initial state. The physical reason for the increase in the alloy corrosion resistance after exposure to the electron beam is the higher corrosion resistance of the oxide film formed on the alloy surface due to the increased aluminum content.

The role of action concepts in physical reasoning: insights from late childhood.

A fundamental component of human cognition is the ability to intuitively reason about behaviours of objects and systems in the physical world without resorting to explicit scientific knowledge. This skill was traditionally considered a symbolic process. However, in the last decades, there has been a shift towards ideas of embodiment, suggesting that accessing physical knowledge and predicting physical outcomes is grounded in bodily interactions with the environment. Infants and children, who learn mainly through their embodied experiences, serve as a model to probe the link between reasoning and physical concepts. Here, we tested school-aged children (5- to 15-year-olds) in online reasoning games that involve different physical action concepts such as supporting, launching and clearing. We assessed changes in children's performance and strategies over development and their relationships with the different action concepts. Children reasoned more accurately in problems that involved supporting actions compared to launching or clearing actions. Moreover, when children failed, they were more strategic in subsequent attempts when problems involved support rather than launching or clearing. Children improved with age, but improvements differed across action concepts. Our findings suggest that accessing physical knowledge and predicting physical events are affected by action concepts, and those effects change over development. This article is part of the theme issue 'Minds in movement: embodied cognition in the age of artificial intelligence'.

Evidence for validity and reliability of a research-based assessment instrument on measurement uncertainty

The Survey of Physics Reasoning on Uncertainty Concepts in Experiments (SPRUCE) was designed to measure students’ proficiency with measurement uncertainty concepts and practices across ten different assessment objectives to help facilitate the improvement of laboratory instruction focused on this important topic. To ensure the reliability and validity of this assessment, we conducted a comprehensive statistical analysis using classical test theory. This analysis includes an evaluation of the test as a whole, as well as an in-depth examination of individual items and assessment objectives. We make use of a previously reported on scoring scheme involving pairing items with assessment objectives, creating a new unit for statistical analysis referred to as a “couplet.” The findings from our analysis provide evidence for the reliability and validity of SPRUCE as an assessment tool for undergraduate physics labs. This increases both instructors’ and researchers’ confidence in using SPRUCE for measuring students’ proficiency with measurement uncertainty concepts and practices to ultimately improve laboratory instruction. Additionally, our results using couplets and assessment objectives demonstrate how these can be used with traditional classic test theory analysis. Published by the American Physical Society 2024

Understanding the effect of physical aging on slip dynamics in soft-glassy materials using pure elongation flow

Slip over a solid surface is a very common occurrence in industrial scale transport and the processing of complex fluids. The knowledge of slip also plays a huge role in the correct estimation of rheological properties. In this work, we have studied the slip dynamics in a model soft-glassy material that exhibits physical aging, wherein the structure evolves gradually toward a more solid-like character via rearrangement of constituents. More precisely, we have investigated the impact of physical aging on slip associated with pure elongation flow of the material. We have allowed the sample to age over different waiting times, followed by the sample being deformed slowly in elongation mode by pulling the top plate to achieve a pure elongation flow. Normal force as a function of gap has been recorded during such pure elongation. These normal force–gap curves demonstrated a remarkable gap-waiting time superposition, manifesting the strong signature of self-similarity in the pure elongation flow of the soft-glassy system. We have adopted a slip layer model, which predicted these normal force–gap flow curves remarkably well. Such prediction also rendered slip layer thickness as a function of waiting time, using which we have explained the intriguing self-similar nature of normal force–gap dependence. Finally, we have established a relationship between the slip layer thickness and the age-dependent bulk rheological properties. We have provided a possible physical reasoning to explain this link between the physical aging-driven state of material and the slip dynamics.

Important Practical Conditions for Getting the High-Quality Foam Concretes

Introduction. The most important reasons justifying the relevance of the research on the practical methods of reducing the consumption of materials in construction industry have been distinguished. The priorities of the Russian Federation referring to the foam concrete technology have been outlined. The level of reliability of the Internet resources describing properties of the dispersedly reinforced foam concretes has been briefly evaluated. The aim of the study is to establish the relationships between the individual properties of fiber, its quantity to the mass of cement ratio, and the most important operational properties of foam concrete manufactured using a single-stage technology.Materials and methods. The types and properties of raw materials used in the experimental research, the methods for controlling the properties of mixes and hardened foam concretes have been defined.Results. The relationship between the speed of phase transition of the viscoplastic properties of the foam concrete mixes into the elastic ones and the possibility of getting a high-quality structure of the hardened foam concrete have been briefly theoretically justified. The physical reasons influencing the direction and speed of forming the raw material dispersed particle clusters in the structure of the interpore partitions of foam concrete mixes have been revealed, which are the important factors to be considered in practice to get the high-strength foam concretes. Depending on the fiber concentration in the concrete mixture composition, the specifics of the fiber physical nature influence on the speed of phase transition from viscoplastic to elastic state have been established. It has been proved that the synergetic effect of dispersed reinforcement is achieved when fiber concentration is enough to provide the significant acceleration of the phase transition. New experimental data on the influence of the individual properties of fiber on the rheological and physico-mechanical properties of D500 foam concrete has been obtained.Discussion and Conclusion. The scientific explanation of the reasons for emergence of the electret effect on the surface of synthetic fiber has been given. It has been revealed that the discovered effect is induced by the specifics of the foam concrete mixture preparation using a single-stage technology. The most important practical conditions due to be met to get the high-strength foam concrete have been determined.