bluuebunny/crossref_metadata_2025 huggingface dataset:
X-Shooting ULLYSES: Massive Stars at low metallicity
Authors: Verhamme O. , Sundqvist J. , de Koter A. , Sana H. , Backs F. , Brands S. A. , Najarro F. , Puls J. , Vink J. S. , Crowther P. A. , Kubátová B. , Sander A. A. C. , Bernini-Peron M. , Kuiper R. , Prinja R. K. , Schillemans P. , Shenar T. , van Loon J. Th. ,   XShootu collaboration
Published: October 2024

Context. Current implementations of mass loss for hot, massive stars in stellar evolution models usually include a sharp increase in mass loss when blue supergiants become cooler than Teff ∼ 20 − 22 kK. Such a drastic mass-loss jump has traditionally been motivated by the potential presence of a so-called bistability ionisation effect, which may occur for line-driven winds in this temperature region due to recombination of important line-driving ions.

Aims. We perform quantitative spectroscopy using UV (ULLYSES program) and optical (XShootU collaboration) data for 17 OB-supergiant stars in the LMC (covering the range Teff ∼ 14 − 32 kK), deriving absolute constraints on global stellar, wind, and clumping parameters. We examine whether there are any empirical signs of a mass-loss jump in the investigated region, and we study the clumped nature of the wind.

Methods. We used a combination of the model atmosphere code FASTWIND and the genetic algorithm (GA) code Kiwi-GA to fit synthetic spectra of a multitude of diagnostic spectral lines in the optical and UV.

Results. We find an almost monotonic decrease of mass-loss rate with effective temperature, with no signs of any upward mass loss jump anywhere in the examined region. Standard theoretical comparison models, which include a strong bistability jump thus severely overpredict the empirical mass-loss rates on the cool side of the predicted jump. Another key result is that across our sample we find that on average about 40% of the total wind mass seems to reside in the more diluted medium in between dense clumps.

Conclusions. Our derived mass-loss rates suggest that for applications such as stellar evolution one should not include a drastic bistability jump in mass loss for stars in the temperature and luminosity region investigated here. The derived high values of interclump density further suggest that the common assumption of an effectively void interclump medium (applied in the vast majority of spectroscopic studies of hot star winds) is not generally valid in this parameter regime.
Untangling stellar components of galaxies: Evaluation of dynamical decomposition methods in simulated galaxies with GalaxyChop
Authors: Cristiani Valeria A. , Abadi Mario G. , Taverna Antonela , Cabral Juan , Benelli Federico , Sánchez Bruno
Published: October 2024

Galaxy formation is intrinsically connected to the distinct evolutionary processes of disk and spheroidal systems, which are the fundamental stellar components of galaxies. Understanding the mutual, dynamical interplay and co-evolution of these components requires a detailed dynamical analysis to allow for disentanglement of these systems. We introduce JEHistogram, a new method for the dynamical decomposition of simulated galaxies into disk and spheroidal stellar components that utilizes the angular momentum and energy of star particles. We evaluate its performance against five previously established methods using a sample of equilibrium galaxies with stellar masses in the range 1010 ≤ Mgal/M⊙ ≤ 1012. Our assessment involves several metrics, including the completeness and purity of stellar particle classification, scale lengths, mass density profiles, velocity dispersion, and rotational velocity profiles. While all methods approximate the properties of the original components, such as mass fractions and density or velocity profiles, JEHistogram demonstrates a better accuracy, particularly in the inner regions of galaxies where component overlap complicates separation. Additionally, we apply JEHistogram to a Milky Way-like galaxy from the IllustrisTNG cosmological simulations, showcasing its capability to derive properties such as the size, mass, velocity, color, and age of dynamically defined disk and spheroidal components. All the dynamical decomposition methods we analyzed are publicly accessible through the Python package GalaxyChop.
Hot spots around Sagittarius A*
Authors: Yfantis A. I. , Wielgus M. , Mościbrodzka M.
Published: October 2024

Context. Observations of Sagittarius A* (Sgr A*) in the near-infrared (NIR) show irregular flaring activity. Flares coincide with the astrometric rotation of the brightness centroid and with looping patterns in fractional linear polarization. These signatures can be explained with a model of a bright hot spot, transiently orbiting the black hole.

Aims. We extend the capabilities of the existing algorithms to perform parameter estimation and model comparison in the Bayesian framework using NIR observations from the GRAVITY instrument, and simultaneously fitting the astrometric and polarimetric data.

Methods. Using the numerical radiative transfer code ipole, we defined several geometric models describing a hot spot orbiting Sgr A*, threaded with a magnetic field, and emitting synchrotron radiation. We then explored the posterior space of our models with a nested sampling code dynesty. We used Bayesian evidence to make comparisons between the models.

Results. We have used 11 models to sharpen our understanding of the importance of various aspects of the orbital model, such as non-Keplerian motion, hot-spot size, and off-equatorial orbit. All considered models converge to realizations that fit the data well, but the equatorial super-Keplerian model is favoured by the currently available NIR dataset.

Conclusions. We have inferred an inclination of ∼155 deg, which corroborates previous estimates, a preferred period of ∼70 minutes, and an orbital radius of ∼12 gravitational radii with the orbital velocity of ∼1.3 times the Keplerian value. A hot spot with a diameter smaller than 5 gravitational radii is favoured. Black hole spin is not constrained well.
Enhancing IoT systems through Cloud-Fog-Edge architectures challenges and opportunities
Authors: Kalyashina Anna , Smirnov Yuri , Esov Valeriy , Kuznetsov Maxim , Dmitrieva Oksana
Published: October 2024

This article examines the deployment and implications of Cloud- Fog-Edge architectures in Internet of Things (IoT) systems, highlighting their significance in enhancing data management and system security across diverse sectors. As IoT ecosystems expand, the necessity for architectures that efficiently handle large volumes of data and ensure real-time processing capabilities becomes paramount. The Cloud-Fog-Edge architecture addresses these needs by distributing computing resources across three layers—cloud, fog, and edge—each optimized for specific tasks within the IoT workflow. We discuss the challenges and solutions associated with interoperability in such multi-layered systems, emphasizing the need for standardized communication protocols and data formats to facilitate seamless interactions between heterogeneous devices and platforms. Furthermore, the article delves into the critical aspects of security within these architectures, outlining strategies for robust data encryption, access management, regular security updates, and comprehensive network activity monitoring to safeguard against unauthorized access and cyber threats. The integration of Cloud-Fog-Edge architectures not only promises enhanced operational efficiency and scalability but also significantly boosts the adaptability of IoT systems to meet evolving technological and operational demands. By providing a detailed analysis of the functionalities, integration challenges, and security practices associated with each architectural layer, this article contributes to a deeper understanding of how Cloud-Fog-Edge frameworks can be optimized to bolster the reliability, efficiency, and security of modern IoT environments.
Information sharing decision of retail platform: platform’s risk aversion and competing suppliers
Authors: Wang Xiaofei , Guan Zhenzhong , Ren Jianbiao
Published: October 2024

An increasing number of retail platforms are adopting blockchain technology to mitigate information asymmetries and share data with upstream suppliers, thereby reducing demand uncertainty. However, these platforms often engage with multiple upstream suppliers of varying product quality. This study constructs a game-theoretic model within a supply chain framework, featuring a risk-averse retail platform and two upstream suppliers of different quality levels. As the core leader of the game, the retail platform decides whether to share demand information with the two competing suppliers after implementing the technology. Using mean-variance theory, this study addresses a key question: Which types of suppliers should be included in information sharing on a retail platform? The results show that when the unit cost of information sharing is low, allowing both suppliers to share demand information is most beneficial. Conversely, when the unit cost is high, only high-quality suppliers should be included. Notably, as the unit cost of information sharing and the intensity of competition between high-quality and low-quality products increase, low-quality suppliers are excluded from information sharing. Additionally, the model indicates that the greatest social welfare can be achieved whether both high-quality and low-quality suppliers are authorized to join the information sharing network, or only high-quality suppliers are included.
Exploring stakeholder perceptions about using artificial intelligence for the diagnosis of rare and atypical infections
Authors: Tekin Aysun , Herasevich Svetlana , Minteer Sarah , Gajic Ognjen , Barwise Amelia
Published: October 2024

Objectives: To evaluate critical care provider perspectives about diagnostic practices for rare and atypical infections and the potential for using artificial intelligence (AI) as a decision-support system (DSS).
Methods: We conducted an anonymous web-based survey among critical care providers at Mayo Clinic Rochester between 11/25/2023 and 1/15/2024, to evaluate their experience with rare and atypical infection diagnostic processes and AI-based DSSs. We also assessed the perceived usefulness of AI-based DSSs, their potential impact on improving diagnostic practices for rare and atypical infections, and the perceived risks and benefits of their use.
Results: A total of 47/143 providers completed the survey. 38/47 agreed that there was a delay in diagnosing rare and atypical infections. Among those who agreed, limited assessment of specific patient factors and failure to consider them were the most frequently cited important contributing factors (33/38). 38/47 reported familiarity with the AI-based DSS applications available to critical care providers. Less than half (18/38) thought AI-based DSSs often provided valuable insights for patient care, but almost three quarters (34/47) thought AI-based DDSs often provided valuable insight when specifically asked about their ability to improve the diagnosis of rare and atypical infections. All respondents rated reliability as important in enhancing the perceived utility of AI-based DSSs (47/47) and almost all rated interpretability and integration into the workflow as important (45/47). The primary concern about implementing an AI-based DSS in this context was alert fatigue (44/47).
Conclusion: Most critical care providers perceived that there are delays in diagnosing rare infections, indicating inadequate assessment and consideration of the diagnosis as the major contributors. Reliability, interpretability, workflow integration, and alert fatigue emerged as key factors impacting usability of AI-based DSS. These findings will inform the development and implementation of an AI-based diagnostic algorithm to aid in identifying rare and atypical infections.
Results of a New Treatment Protocol for Sudden Sensorineural Hearing Loss Using Betamethasone for Intratympanic Therapy
Authors: Lopes Paula Tardim , Almeida Jessica , Bento Ricardo Ferreira
Published: October 2024

Introduction Sudden sensorineural hearing loss (SSNHL) is defined as a rapid sensation of hearing impairment in one or both ears. Based on its personal impact on patients, the present study advances the analysis of new treatments for the prompt recognition and management of SSNHL, with higher chances of improvements in terms of hearing recovery and quality of life of the patients.

Objective To describe the intratympanic (IT) corticoid infiltration technique, to demonstrate the efficacy of betamethasone injection as a sequential treatment in patients whose initial systemic steroid treatment failed, as well as to compare its use in different treatment periods.

Methods The present clinical trial was conducted with 37 patients referred to our office with the diagnosis of SSNHL, from September 2019 to May 2022, who provided informed consent to participate.

Results Even dividing the analysis of increasing the pure tone average (PTA) or speech recognition threshold (SRT) between the difference into initiation of the salvage therapy in up to 15 days of the sudden deafness event, and between 15 days and 3 months of the event, we did not find any difference in hearing improvement.

Conclusion Intratympanic corticosteroid therapy is prescribed when conventional therapy fails or when there is a limitation to the use of corticosteroids due to the presence of systemic disorders. As such, new drugs, such as bethametasone, are studied and show promising results.
Effect of Natural Ionizing Radiation on Health Indicators in Region with Monazite Sand in Brazil
Authors: Calegaro José Ulisses Manzzini , Casulari Luiz Augusto , Orlando Marcos Tadeu D'Azeredo
Published: October 2024

Objective This article compares the occurrence of cancer and germinal damage in the city of Guarapari-Espírito Santo (ES), an area with high natural ionizing radiation, with other coastal cities.

Material and Methods The evaluated cities were: Guarapari (ES), Campos (Rio de Janeiro), Rio Grande (Rio Grande do Sul), and Ilhéus (Bahia); the following factors were considered: mortality rate % from tumors (2007–2017), mortality rate % from tumors up to 15 years of age (2007–2017), hospital morbidity rate % from tumors up to 15 years of age (2008–2018), and hospital morbidity rate % from congenital malformation and chromosomal anomalies (2008–2018). Radiometric surveys were conducted by the Applied Physics Group at Universidade Federal do Espírito Santo.

Results The natural radiation levels recorded in Guarapari resulted in accumulated dose between 3.65 and 10.95 mSv/year, and 1 mSv in the other cities. The highest average cancer mortality rates were: Rio Grande = 22.4%; Guarapari = 17.6%; Campos = 16.7%; and Ilhéus = 11.8%. The proportional hospital mortality and morbidity rates for cancer up to 15 years of age are as follows: Ilhéus = 3.36 and 5.87%; Rio Grande = 0.79 and 7.38%; Guarapari = 0.64 and 7.25%; and Campos = 0.39 and 9.13%. The hospital morbidity rate due to congenital malformations and chromosomal anomalies was 0.72% for Campos, 0.63% for Rio Grande, 0.62% for Guarapari, and 0.43% for Ilhéus.

Conclusion There was no increase in cases of cancer or germ damage in Guarapari. These results indicated a dose threshold in the induction of these damages, contradicting the current linear no-threshold theory.
The Role of Viral Infections in the Development and Progression of COPD
Authors: Burkes Robert
Published: October 2024

Chronic obstructive pulmonary disease (COPD) is a common chronic disease seen in smokers associated with poor functional status, quality of life, and morbidity and mortality from acute worsening of chronic symptoms, also called exacerbations. As a disease, the risk factors for COPD are well defined; however, there is room for innovation in identifying underlying biological processes, or “endotypes,” that lead to the emergence and/or progression of COPD. Identifying endotypes allows for more thorough understanding of the disease, may reveal the means of disease prevention, and may be leveraged in novel therapeutic approaches. In this review, we discuss the interface of viral infections with both cellular and epithelial immunity as a potential endotype of interest in COPD.
Therapy of Aspiration: Out-of-Hospital and In-Hospital-Acquired
Authors: Pan Di , Isaacs Bradley , Niederman Michael S.
Published: October 2024

Therapeutic considerations for aspiration pneumonia prioritize the risk of multidrug-resistant organisms. This involves integrating microbiological insights with each patient's unique risk profile, including the location at the time of aspiration, and whether it occurred in or out of the hospital. Our understanding of the microbiology of aspiration pneumonia has also evolved, leading to a reassessment of anaerobic bacteria as the primary pathogens. Emerging research shows a predominance of aerobic pathogens, in both community and hospital-acquired cases. This shift challenges the routine use of broad-spectrum antibiotics targeting anaerobes, which can contribute to antibiotic resistance and complications such as Clostridium difficile infections—concerns that are especially relevant given the growing issue of antimicrobial resistance. Adopting a comprehensive, patient-specific approach that incorporates these insights can optimize antibiotic selection, improve treatment outcomes, and reduce the risk of resistance and adverse effects.
Qualitative insights into a scholarship scheme designed to optimise test scores and expedite SDG-4 actualisation in Nigeria
Authors: Ifediora Chris , Trimmer Karen , Ayodele Adeyinka Adewuyi , Obianyo Etomike
Published: October 2024

Despite huge commitments, education quality and achievement gaps have remained low in developing countries, posing threats to the actualisation of the SDG-4 goals. A recent quantitative study found that a scholarship scheme that engages communities adopts hybrid selection criteria, and seeks en-masse motivation towards high test scores might be effective at improving education quality. Case Study interviews of 15 beneficiaries of the IFOMSSA Senior Scholarship, a scheme established in 2017 for high schools in Southeast Nigeria. Respondents confirmed that the Scheme’s hybrid (needs and merit-based) selection criteria, along with its en-masse motivation strategies and community involvement, all contributed to improved test scores and exam enrolments. Non-scholarship recipients were motivated as much as eventual recipients, affirming “mass motivation”. Community groups (family, friends, teachers, community leaders and government staff) had positive influences, while media publicity inspired confidence and trust. Scholarship schemes that integrate the advocated principles might hold the key to sustainably optimising test scores in developing countries. This expands options for improving education quality and enrolments.
A threshold activation-based simplified Lv’s transform algorithm for transient multi-component linear frequency modulation signals analysis
Authors: Lei Maolin , Ye Peng , Li Chengyang , Yang Kuojun
Published: October 2024

The high sampling rate in modern digital systems generates a large scale of data. To address the computational burden, this paper proposes a threshold activation-based simplified Lv’s transform (SLVT) algorithm to analyze the transient multi-component linear frequency modulation signals. Only the signal arrival can trigger the signal analysis. This mechanism alleviates the computation pressure because of the sparsity of signals. The threshold activation mechanism enables transient signal detection and sampling rate adjustment, thereby enhancing the efficiency and effectiveness of the analytical process. The simplified Lv’s transform (LVT) removes redundant computations on stretch weighting and the Discrete Fourier Transform (DFT) in Lv’s transform. SLVT uses the efficient Bluestein chirp-z algorithm to implement the stretch keystone transform. The comparison results show that SLVT reduces the computational complexity of the original LVT by at least 30.8%. This algorithm exhibits superior performance compared to other advanced signal processing methods, such as discrete chirp Fourier transform, fractional Fourier transform, and Radon Wigner transform algorithms, in terms of parameter extraction accuracy, computational complexity, and execution time. Moreover, the implementation of a field programmable gate array accelerates SLVT computing by a factor of 116 in comparison to the CPU (Central Processing Unit) platform.
Fusion model of gray level co-occurrence matrix and convolutional neural network faced for histopathological images
Authors: Wang Shanxiang , Zhao Xiaoxue , Guo Hao , Qi Fei , Qiao Yu , Wang Chunju
Published: October 2024

The image recognition of cancer cells plays an important role in diagnosing and treating cancer. Deep learning is suitable for classifying histopathological images and providing auxiliary technology for cancer diagnosis. The convolutional neural network is employed in the classification of histopathological images; however, the model’s accuracy may decrease along with the increase in network layers. Extracting appropriate image features is helpful for image classification. In this paper, different features of histopathological images are represented by extracting features of the gray co-occurrence matrix. These features are recombined into a 16 × 16 × 3 matrix to form an artificial image. The original image and the artificial image are fused by summing the softmax output. The histopathological images are divided into the training set, validation set, and testing set. Each training dataset consists of 1500 images, while the validation dataset and test dataset each consist of 500 images. The results indicate that the effectiveness of our fusion model is demonstrated through significant improvements in accuracy, precision, recall, and F1-score, with an average accuracy reaching 99.31%. This approach not only enhances the classification performance of tissue pathology images but also holds promise for advancing computer-aided diagnosis in cancer pathology.
Alchemical insights into approximately quadratic energies of iso-electronic atoms
Authors: Krug Simon León , von Lilienfeld O. Anatole
Published: October 2024

Accurate quantum mechanics based predictions of property trends are so important for material design and discovery that even inexpensive approximate methods are valuable. We use the alchemical integral transform to study multi-electron atoms and to gain a better understanding of the approximately quadratic behavior of energy differences between iso-electronic atoms in their nuclear charges. Based on this, we arrive at the following simple analytical estimate of energy differences between any two iso-electronic atoms, ΔE≈−(1+2γNe−1)ΔZZ̄. Here, γ ≈ 0.3766 ± 0.0020 Ha corresponds to an empirical constant, and Ne, ΔZ, and Z̄, respectively, to electron number, nuclear charge difference, and average. We compare the formula’s predictive accuracy using experimental numbers and non-relativistic, numerical results obtained via density functional theory (pbe0) for the entire periodic table up to Radon. A detailed discussion of the atomic helium-series is included.
Thermal transport in metal halide perovskites and other third-generation photovoltaic materials
Authors: Chen Du , Li Shunran , Li Bowen , Guo Peijun
Published: October 2024

Third-generation photovoltaic materials, including metal halide perovskites (MHPs), colloidal quantum dots (QDs), copper zinc tin sulfide (CZTS), and organic semiconductors, among others, have become attractive in the past two decades. Unlike their first- and second-generation counterparts, these advanced materials boast properties beyond mere photovoltaic performance, such as mechanical flexibility, light weight, and cost-effectiveness. Meanwhile, these materials possess more intricate crystalline structures that aid in understanding and predicting their transport properties. In particular, the distinctive phonon dispersions in MHPs, the layered architecture in quasi-two-dimensional (2D) perovskites, the strong quantum confinement in QDs, and the complex crystal structures interspersed with abundant disorders in quaternary CZTS result in unique and sometimes anomalous thermal transport behaviors. Concurrently, the criticality of thermal management in applications such as photovoltaics, thermoelectrics, light emitting diodes, and photodetection devices has received increased recognition, considering that many of these third-generation photovoltaic materials are not good thermal conductors. Effective thermal management necessitates precise measurement, advanced modeling, and a profound understanding and interpretation of thermal transport properties in these novel materials. In this review, we provide a comprehensive summary of various techniques for measuring thermal transport properties of these materials and discuss the ultralow thermal conductivities of three-dimensional (3D) MHPs, superlattice-like thermal transport in 2D perovskites, and novel thermal transport characteristics inherent in QDs and CZTS. By collecting and comparing the literature-reported results, we offer a thorough discussion on the thermal transport phenomenon in these materials. The collective understanding from the literature in this area, as reviewed in this article, can provide guidance for improving thermal management across a wide spectrum of applications extending beyond photovoltaics.
Observation of doping-induced spin–orbit coupling in gold cluster assembly to carrier-tuneable semiconductors and Schottky behaviors
Authors: Dash P. P. , Kabiraj A. , Mallik G. , Kumari P. , Jha S. N. , Kumar Yogesh , Rath S.
Published: October 2024

The doping influenced carrier dynamics to maneuvering n-type to p-type semiconducting gold cluster assembly have been assessed. The resonance photoemission spectroscopic measurements corroborate an incremental rise in the density of states at the valence edge, the overlap of valence states due to doping, and the presence of distinct spin–orbit splitting and coupling in manganese-doping (Au7Mn) compared to gold clusters (Au8), originating from the relativistic effect resulted in a semiconducting property. The work function dependent current–voltage characteristics in metal–semiconductor configuration show Ohmic and Schottky behaviors assorting p-type carriers in Au7Mn in contrast to the n-type Au8 and are presenting an atomic cluster based fast electronic device.
Compact polarization splitter-rotator based on lithium niobate-on-insulator platform
Authors: Zhang Jialiang , Zhou Kanglu , Liu Xiaochun , Chen Gui , Chen Changshui
Published: October 2024

We propose a compact mode-coupled polarization splitter-rotator (PSR) based on the lithium niobate-on-insulator platform. The PSR is composed of an asymmetric directional coupler, a taper, and an S-bend. Cross-polarization mode coupling is achieved using a ridge waveguide and air cladding to break the symmetry of the waveguide cross section with a length of only 61 μm. Simulation results show that the insertion losses of this device in the 1500–1600 nm range are less than 1.85 and 0.31 dB for TM0 and TE0 modes, respectively, and the extinction ratios are more than 22.5 and 22.7 dB, respectively. In addition, the PSR exhibits a polarization conversion efficiency of 99.97% at 1550 nm. The proposed PSR has great potential for applications in polarization-division multiplexing transmitters and on-chip polarization controllers.
Research on the mechanism and extinguishing technology of substation fire
Authors: Song Jidong , Wang Fei , Liang Yiou , Yang Dongxing
Published: October 2024

This article utilizes the combustion characteristics of combustible materials to investigate the fire mechanisms and extinguishing technologies in substations. Experimental and simulation analyses have revealed patterns in heat release rates, flame heights, flame temperatures, flame resistance, and particulate ash. A modular solution employing a novel hot aerosol fire suppression system has been introduced. This system integrates independently manufactured alarm devices, initiation devices, sensors, and fire suppression equipment, offering either semi-automatic or fully automatic functionality. It serves both targeted fire suppression and complete immersion scenarios. By developing an integrated fire suppression and database alert system, enhanced intelligent fire protection has been attained, thereby advancing the sophistication of substation fire safety and the digitization of power networks.
Utilizing multi-point temperature sensing to evaluate the low frequency noise of phasemeter for intersatellite laser interferometer
Authors: Feng Yu-Jie , Jiang Yuan-Ze , Xiao Guo-Yao , Chen Liu-Yang , Lu Bai-Fu , Xu Zhi-Lin , Liang Yu-Rong
Published: October 2024

High-precision phasemeters are a key technology in intersatellite laser interferometers used for detecting gravitational waves (GWs) in space. As the core of the readout system, the phasemeter must operate in the bandwidth of 5–25 MHz, and its resolution needs to reach the order of μrad/Hz at mHz. It presents significant challenges to electronic signal processing technology. To investigate the primary noise source in the low-frequency band, a mathematical model of thermal drift to phase noise was established, and a multi-point temperature sensing scheme for critical electronic components was proposed. In particular, we evaluated a phasemeter based on a commercial platform and assessed the thermal drift noise according to the proposed model. This study identifies and explains the effects of temperature linear drift and overcorrection in components, demonstrating that thermal drift noise is the main noise source for the phasemeter at frequencies from 0.1 to 1 mHz. In addition, the proposed scheme is universal in its applicability and may be implemented in any circuit for the evaluation of temperature effects on the components of interest.
Flow around triangular prisms with varying vertex angle at low Reynolds numbers
Authors: Khan Majid Hassan , Khan Hamid Hassan
Published: October 2024

The present work investigates the unsteady flow around triangular prisms with vertex angles of 30°,45°,60°, and 90° for shedding Reynolds number between 50 and 150. The numerical simulations of flow around triangular prisms at different vertex angles and Reynolds number has been carried out using the open-source code OpenFOAM. The wake of the prisms in different cases has been examined using instantaneous and time-averaged velocity and vorticity fields. The energy dynamics in the wake are demonstrated using enstrophy. The paper explains the shedding around a prism and reports the differences in the wake due to the different vertex angles of the prisms employed in the present work. Strouhal number and force coefficients have been obtained and compared for different prisms. The coefficient of lift and drag phase plot indicates a higher spread for prisms with larger vertex angles at higher Reynolds number. The shedding frequency has a linear variation with Reynolds numbers for the prisms. The obtained results were compared with earlier works on square cylinders and 45° oriented square cylinder.
Optimal strategy for stabilizing protein folding intermediates
Authors: Wang Mengshou , Peng Liangrong , Jia Baoguo , Hong Liu
Published: October 2024

To manipulate the protein concentration at a certain functional state through chemical stabilizers is crucial for protein-related studies. It not only plays a key role in protein structure analysis and protein folding kinetics, but also affects protein functionality to a large extent and thus has wide applications in medicine, food industry, etc. However, due to concerns about side effects or financial costs of stabilizers, identifying optimal strategies for enhancing protein stability with a minimal amount of stabilizers is of great importance. Here, we prove that either for the fixed terminal time (including both finite and infinite cases) or for the free one, the optimal control strategy for stabilizing the folding intermediates with a linear strategy for stabilizer addition belongs to the class of bang–bang controls. The corresponding optimal switching time is derived analytically, whose phase diagram with respect to several key parameters is explored in detail. The bang–bang control will be broken when nonlinear strategies for stabilizer addition are adopted. Moreover, the above theory is applied to the stabilization of erythropoietin by ten different kinds of chemicals, providing theoretical guidance for the selection and rational usage of stabilizers. Our current study on optimal strategies for protein stabilizers not only offers deep insights into the general picture of protein folding kinetics but also provides valuable theoretical guidance on treatments for protein-related diseases in medicine.
Ultralow thermal conductivity in Si–Ge nanograin mixtures: A cost-effective granular material for thermoelectric applications
Authors: Barakat Nourhan , Akkoush A. , El Haj Hassan Fouad , Kazan Michel
Published: October 2024

This paper presents a theoretical study of the thermal conductivity of Si–Ge nanograin mixtures using a multiscale computational methodology based on solving the Boltzmann transport equation for phonons with first-principles techniques. A size-dependent correction factor is developed to account for the spatial dependence of the phonon distribution function on nanograin size, with parameters derived from the phonon properties of infinite Si and Ge crystals. This approach makes it possible to accurately calculate the thermal conductivity within a single nanograin, using force constants obtained from first-principles calculations. Thermal energy transport by phonons across grain boundaries is modeled by accounting for phonon transmission by two-phonon processes, weighting specular, and diffuse transmission for each phonon mode as a function of the root-mean-square roughness of the boundary relative to the phonon wavelength. The boundary thermal conductance model, previously validated against experimental data, is implemented using first-principles techniques. This approach excludes specular transmission for phonon modes with specific symmetries while ensuring conservation of the total number of modes in each symmetry class. The study examines the influence of grain size, nanograin mixture composition, temperature, and boundary asperities on the thermal conductivity of nanograin mixtures.
Theoretical study of the dielectric properties of the carbon nanotubes doped nematic liquid crystal
Authors: Mukherjee Prabir K.
Published: October 2024

The dielectric properties of the carbon nanotubes (CNT) doped nematic liquid crystal (NLC) are studied theoretically. The temperature and frequency dependence of the real and imaginary part of the complex dielectric permittivity and dielectric loss factor of the CNT doped NLC are calculated. The effects of CNT on the real and imaginary part of dielectric permittivities are discussed by comparing with experimental results. An appreciable change in the dielectric permittivity has been observed in the CNT doped NLC.
Dynamics of high-dimensional quantum systems coupled to a harmonic bath. General theory and implementation via multiconfigurational wave packets and truncated hierarchical equations for the mean-fields
Authors: Picconi David
Published: October 2024

Modeling the dynamics of a quantum system coupled to a dissipative environment becomes particularly challenging when the system’s dimensionality is too high to permit the computation of its eigenstates. This problem is addressed by introducing an eigenstate-free formalism, where the open quantum system is represented as a mixture of high-dimensional, time-dependent wave packets governed by coupled Schrödinger equations, while the environment is described by a multi-component quantum master equation. An efficient computational implementation of this formalism is presented, employing a variational mixed Gaussian/multiconfigurational time-dependent Hartree (G-MCTDH) ansatz for the wave packets and propagating the environment dynamics via hierarchical equations, truncated at the first or second level of the hierarchy. The effectiveness of the proposed methodology is demonstrated on a 61-dimensional model of phonon-driven vibrational relaxation of an adsorbate. G-MCTDH calculations on 4- and 10-dimensional reduced models, combined with truncated hierarchical equations for the mean fields, nearly quantitatively replicate the full-dimensional quantum dynamical results on vibrational relaxation while significantly reducing the computational time. This approach thus offers a promising quantum dynamical method for modeling complex system–bath interactions, where a large number of degrees of freedom must be explicitly considered.
Fluid–structure interaction in engineering based on its applications: A plenary and up-to-date review
Authors: Afridi Muhammad Idrees , Izadi Mohsen , Eizadi Mohammad , Mohammed Hussein A. , Karimi Reza , Alqurashi Faris , Mohamed Mohamed H. , Hajjar Ahmad , Ben Hamida Mohamed Bechir , Mahariq Ibrahim , Rahimi Shayan
Published: October 2024

The present study reviews the relevant research done on the fluid–structure interaction (FSI) in channels and vessels. The cases of FSI in channels with elastic plates, channels with variable geometry, flow airfoils, blood vessels, and heart valves are presented, using data from credible research articles. The review is carried out with a focus on the performance of the FSI method in solving engineering problems in channels, reporting its findings such as the effect of power-law exponent, the Nusselt number in different parts of a fluid, lift, and drag for a rigid cylinder and a plate in Newtonian fluids, the formation of eddy current, and the distribution of velocity and pressure in a fluid and on walls. The review is instrumental for researchers, engineers, and academics in providing comprehensive insight into methodologies and applications of fluid–structure interaction.
Effect of yaw on wake and load characteristics of two tandem offshore wind turbines under neutral atmospheric boundary layer conditions
Authors: Ju Liangyu , Li Linmin , Wang Zhengdao , Yang Hui , Zhang Wei , Wei Yikun
Published: October 2024

In this work, we numerically investigated the effects of yaw angle on the wake and power characteristics of two National Renewable Energy Laboratory (NREL) 5 MW wind turbines based on actuator line method (ALM) and large eddy simulation (LES) under a neutral atmospheric boundary layer (ABL) with specified offshore surface roughness. The turbines are placed in tandem, with a spacing of seven rotor diameters, and the yaw angles range from 0° to 30°. The results indicate that under coordinated yaw conditions, the wakes of the two turbines significantly shift with increasing yaw angles, encroaching on the trailing edge of the turbines. The expansion of the wakes also gradually weakens, leading to a reduction in width. The superposition of the wake generated by the downstream turbine diminishes, leading to both turbines exhibiting approximately comparable physical characteristics within their respective wakes. As the wake of the upstream turbine propagates downstream, a secondary low-speed region emerges between the primary low-speed zone of the wake of downstream turbine and the surrounding atmosphere. With the increase in yaw angle, this secondary low-speed region significantly enhances the rate of wake recovery while also inducing a more pronounced deflection of the wake, thereby demonstrating a stronger entrainment effect. Regarding load characteristics, the time history of power characteristics and the power spectral density (PSD) spectra indicate a good turbine response to the inflow. The power characteristics of the upstream turbine exhibit a scaling law is closely related to the yaw angle. The quantitative relationship is established between yaw angle and the power distribution of the turbines, alongside a proposed correlation between the yaw angle and the  cos 2(γ) scaled power curve. The power of upstream turbine decreases and the power of downstream turbine gradually increases with the increase in yaw angle. It is further found that the downstream turbine demonstrates optimal performance at a yaw angle of 20°due to the influence of the yawed upstream turbine. These analyses provide insights into the characteristics of wind turbine arrays under yaw conditions from the perspective of unsteady wake features, interactions, and aerodynamic performance, which can aid in wind farm unit planning and control strategies.
Nonreciprocal transmission of surface acoustic waves induced by magneotoelastic coupling with an anti-magnetostrictive bilayer
Authors: Zhou Zihan , Hu Wenbin , Wu Hao , Huang Mingxian , Wu Yutong , Jia Yana , Wang Wen , Bai Feiming
Published: October 2024

In this study, we report giant nonreciprocal transmission of shear-horizontal surface acoustic waves (SH-SAWs) in a ferromagnetic bilayer structure with negative–positive magnetostriction configuration. Although the directions of magnetization in the neighboring layers are parallel, SH-SAWs can excite optical-mode spin waves (SWs) via magnetoelastic coupling at relatively low frequencies, which is much stronger than acoustic-mode SWs at high frequencies. The measured magnitude nonreciprocity or isolation of SH-SAWs exceeds 40 dB (or 80 dB/mm) at 2.333 GHz. In addition, maximum nonreciprocal phase accumulation reaches 188° (376°/mm). Our theoretical model and calculations provide an insight into the observed phenomena and demonstrate a pathway for further improving nonreciprocal acoustic devices toward highly compact microwave isolators and circulators.
Impact of dyke and vegetation on fluid force and moment reduction under sub and supercritical flow conditions
Authors: Murtaza Nadir , Pasha Ghufran Ahmed , Khan Zaka Ullah , Alotaibi Saleh , Akbar Zeeshan , Khedher Khaled Mohamed
Published: October 2024

Flooding is the most common natural disaster throughout the world and requires efficient management. Therefore, the current investigation aimed to explore the impact of a composite defense system comprising dyke and vegetation on flow dynamics and velocity reduction. Experiments were conducted in an open channel setup with an adjustable bed slope and transparent sidewalls, and the vegetation model was replicated as real trees such as Eucalyptus trees. The study involved calculating several parameters, including flow velocity, reduction of fluid force index (RFI%), reduction in moment index (RMI%), and hydrostatic and hydrodynamic forces. These calculations were done by changing the channel bed slope and keeping the flow rate (discharge) constant while considering both subcritical and supercritical flow conditions. Moreover, regression analysis was performed for the prediction of RFI% and RMI% under various flow conditions. Also, statistical analyses were performed to assess the effectiveness of the defense system in reducing fluid force and moment indices. The result of the current investigation indicates that the highest values of RFI% and RMI% under subcritical flow conditions were 79% and 88%, while under supercritical flow conditions they were 94% and 78%, respectively. Moreover, a velocity reduction of 69% was observed under subcritical flow, while 84% was observed under supercritical flow conditions. Under subcritical flow conditions, RFI% and RMI% enhanced by enhancing Froude number (Fr) because of an increase in velocity reduction and hydraulic jump formation. Similar trends were observed under supercritical flow conditions, with effective mitigation of high-velocity flows by the composite system. The finding of current research helps in providing effective techniques for flood management.
The Poisson–Boltzmann equation in micro- and nanofluidics: A formulary
Authors: Herrero Cecilia , Joly Laurent
Published: October 2024

The Poisson–Boltzmann (PB) equation provides a mean-field theory of electrolyte solutions at interfaces and in confinement, describing how ions reorganize close to charged surfaces to form the so-called electrical double layer (EDL), with numerous applications ranging from colloid science to biology. This formulary focuses on situations of interest for micro- and nanofluidics, and gathers important formulas for the PB description of a Z:Z electrolyte solution inside slit and cylindrical channels. Different approximated solutions (thin EDLs, no co-ion, Debye–Hückel, and homogeneous/parabolic potential limits) and their range of validity are discussed, together with the full solution for the slit channel. Common boundary conditions are presented, the thermodynamics of the EDL is introduced, and an overview of the application of the PB framework to the description of electrokinetic effects is given. Finally, the limits of the PB framework are briefly discussed, and Python scripts to solve the PB equation numerically are provided.
Rayleigh–Taylor instability in a Casson fluid layer with heat and mass transfer
Authors: Awasthi Mukesh Kumar , Shukla Atul Kumar , Pandey Pragati
Published: October 2024

This study investigates the stability of the interface between two fluids, a Casson fluid on top and a viscous fluid below, with heat and mass transfer occurring between them. We used the potential flow theory, which simplifies the problem by ignoring tangential stresses and focusing on normal stress balance. We did not consider no-slip conditions at the boundaries, assuming zero normal velocity at these rigid boundaries instead. A second-order polynomial equation was developed to calculate the growth rate of instabilities and solved numerically using the Newton–Raphson method. The results showed that heat and mass transfer improved the stability of the interface, even though the Atwood number, a measure of instability, remained high.
Carbonate rocks may release more carbon dioxide as climate warms
Authors: Fattaruso Laura
Published: October 2024

An analysis of 60 years of water chemistry data from Arctic and subarctic Canadian rivers finds that some regions exhibit a major increase of dissolved sulfates, a product of weathering reactions that also release CO2.
Conventional medication adherence and self-treatment practices among South Asian immigrants: a qualitative study
Authors: Akhtar Sumera Saeed , Anwar Mudassir , Coppell Kirsten J. , Parackal Sherly Mathew
Published: October 2024

Introduction Globally, cardiovascular disease (CVD) is a common cause of death. The highest CVD rate is among South Asian populations and South Asian immigrants have a higher risk of developing CVD than other ethnic groups. While treatment of established CVD risk factors is recommended, medication adherence may be poor. Aim This qualitative study aimed to explore medication adherence practices of New Zealand South Asians who are prescribed medications for type 2 diabetes, and/or hypertension, and/or dyslipidaemia, established risk factors for CVD. Method Twenty-one semi-structured telephone interviews were conducted with South Asians with type 2 diabetes, and/or hypertension, and/or dyslipidaemia. Data were transcribed, then analysed thematically using NVivo12. Codes and inductively derived themes were discussed. Results Five themes with 12 subthemes were identified. The five themes included daily routine and medication adherence practices, perceived necessity of medications and concerns about side effects, concern and hesitancy to start conventional medications, integration of herbal and alternative therapies, and the role of healthcare providers and communication. Discussion These findings highlight the importance of personalised approaches to medication management that consider patients’ beliefs, daily routines, and cultural contexts to reduce CVD risk and improve health outcomes among South Asians.