bluuebunny/crossref_metadata_2025 huggingface dataset:
Hormones in malaria infection: influence on disease severity, host physiology, and therapeutic opportunities
Authors: Das Aleena , Suar Mrutyunjay , Reddy K Sony
Published: November 2024

Human malaria, caused by Plasmodium parasites, is a fatal disease that disrupts the host’s physiological balance and affects the neuroendocrine system. This review explores how malaria influences and is influenced by hormones. Malaria activates the Hypothalamus-Pituitary-Adrenal axis, leading to increased cortisol, aldosterone, and epinephrine. Cortisol, while reducing inflammation, aids parasite survival, whereas epinephrine helps manage hypoglycemia. The Hypothalamus-Pituitary-Gonad and Hypothalamus-Pituitary-Thyroid axes are also impacted, resulting in lower sex and thyroid hormone levels. Malaria disrupts the renin-angiotensin-aldosterone system (RAAS), causing higher angiotensin-II and aldosterone levels, contributing to edema, hyponatremia and hypertension. Malaria-induced anemia is exacerbated by increased hepcidin, which impairs iron absorption, reducing both iron availability for the parasite and red blood cell formation, despite elevated erythropoietin. Hypoglycemia is common due to decreased glucose production and hyperinsulinemia, although some cases show hyperglycemia due to stress hormones and inflammation. Hypocalcemia, and hypophosphatemia are associated with low Vitamin D3 and parathyroid hormone but high calcitonin. Hormones such as DHEA, melatonin, PTH, Vitamin D3, hepcidin, progesterone, and erythropoietin protects against malaria. Furthermore, synthetic analogs, receptor agonists and antagonists or mimics of hormones like DHEA, melatonin, serotonin, PTH, vitamin D3, estrogen, progesterone, angiotensin, and somatostatin are being explored as potential antimalarial treatments or adjunct therapies. Additionally, hormones like leptin and PCT are being studied as probable markers of malaria infection.
Endothelial cell-cardiomyocyte cross-talk: understanding bidirectional paracrine signaling in cardiovascular homeostasis and disease
Authors: Adao Doris M.T. , Ching Crizza , Fish Jason E. , Simmons Craig A. , Billia Filio
Published: November 2024

To maintain homeostasis in the heart, endothelial cells and cardiomyocytes engage in dynamic cross-talk through paracrine signals that regulate both cardiac development and function. Here, we review the paracrine signals that endothelial cells release to regulate cardiomyocyte growth, hypertrophy and contractility, and the factors that cardiomyocytes release to influence angiogenesis and vascular tone. Dysregulated communication between these cell types can drive pathophysiology of disease, as seen in ischemia-reperfusion injury, diabetes, maladaptive hypertrophy, and chemotherapy-induced cardiotoxicity. Investigating the role of cross-talk is critical in developing an understanding of tissue homeostasis, regeneration, and disease pathogenesis, with the potential to identify novel targets for diagnostic and therapeutic purposes.
Stochastic approach to evaluate the shielding effectiveness of composite materials loaded with randomly oriented helices
Authors: Hamidi Ayoub , Cheldavi Ahmad , Habibnejad Korayem Asghar
Published: November 2024

This letter proposes a method to calculate the expected value of the shielding effectiveness of a composite material slab, including a planar array of randomly oriented metal helices as chiral particles. Helix‐loaded concrete composite materials are advantageous for electromagnetic interference shielding applications. While planar periodic arrays of chiral particles have been extensively studied, this research discusses a non‐periodic array in which the helical particle axis direction in each unit cell is random. This method estimates the slab's shielding effectiveness by defining it as a random variable expanded into three independent basis‐like functions. Comparisons with full‐wave simulations show acceptable agreement across a wide frequency range, with a total RMS error of 0.9 dB. This study additionally includes an experimental measurement to validate the proposed method. This technique provides the initial step in developing an analytical method to analyse and estimate the transmitted power of general structures using a stochastic approach. Examples include concrete composites containing randomly distributed helical steel particles with significant shielding effectiveness.
Decarbonising the Australian economy: A first step
Authors: Kalam Akhtar , Weeks Warren A. , Hogan Brad
Published: November 2024

Amidst mounting global pressure, governments worldwide have embarked on a collective journey towards decarbonising their economies within the next 30 years. This ambitious goal necessitates the phasing out of naturally occurring hydrocarbons such as coal, natural gas, and oil. However, our analysis of data from academic papers, Australian Federal Government publications, and reports from energy industry bodies and manufacturers of electricity‐generating equipment suggests that such a complete elimination of fossil fuel use is not feasible. The data we've gathered, however, indicate that transitioning to a connected energy island power generation topology could at least create a sustainably robust energy supply capable of propelling Australia towards its environmental targets while bolstering its future economic well‐being.
Extension of the multilevel radiative transfer code PyRaTE to model linear polarization of molecular lines
Authors: Tritsis A. , Kylafis N.
Published: November 2024

Context. Linear polarization of spectral lines, commonly known as the Goldreich-Kylafis effect within the star formation community, is one of the most underutilized techniques for probing magnetic fields in the dense and cold interstellar medium.

Aims. In this study, we implement linear polarization of molecular spectral lines into the multilevel, non-local thermodynamic equilibrium radiative transfer code PYRATE.

Methods. Different modes of polarized radiation are treated individually, with separate optical depths computed for each polarization direction. Our implementation is valid in the so-called strong magnetic field limit and is exact for either a system satisfying the large-velocity-gradient approximation, and/or for any system with a uniform magnetic field. We benchmark our implementation against analytical results and provide tests for various limiting cases.

Results. In agreement with previous theoretical results, we find that in the multilevel case the amount of fractional polarization decreases when compared to the two-level approximation, but this result is subject to the relative importance between radiative and collisional processes. Finally, we post-process an axially symmetric, nonideal magnetohydrodynamic chemo-dynamical simulation of a collapsing prestellar core and provide theoretical predictions regarding the shape (as a function of velocity) of the polarization fraction of CO during the early stages in the evolution of molecular clouds.
REsolved ALMA and SMA Observations of Nearby Stars (REASONS)
Authors: Matrà L. , Marino S. , Wilner D. J. , Kennedy G. M. , Booth M. , Krivov A. V. , Williams J. P. , Hughes A. M. , del Burgo C. , Carpenter J. , Davies C. L. , Ertel S. , Kral Q. , Lestrade J.-F. , Marshall J. P. , Milli J. , Öberg K. I. , Pawellek N. , Sepulveda A. G. , Wyatt M. C. , Matthews B. C. , MacGregor M.
Published: November 2024

Context. Planetesimal belts are ubiquitous around nearby stars, and their spatial properties hold crucial information for planetesimal and planet formation models.

Aims. We present resolved dust observations of 74 planetary systems as part of the REsolved ALMA and SMA Observations of Nearby Stars (REASONS) survey and archival reanalysis.

Methods. We uniformly modelled interferometric visibilities for the entire sample to obtain the basic spatial properties of each belt, and combined these with constraints from multi-wavelength photometry.

Results. We report key findings from a first exploration of this legacy dataset: (1) Belt dust masses are depleted over time in a radially dependent way, with dust being depleted faster in smaller belts, as predicted by collisional evolution. (2) Most belts are broad discs rather than narrow rings, with much broader fractional widths than rings in protoplanetary discs. We link broad belts to either unresolved substructure or broad planetesimal discs produced if protoplanetary rings migrate. (3) The vertical aspect ratios (h = H/R) of 24 belts indicate orbital inclinations of ~1–20º, implying relative particle velocities of ~0.1–4 km/s, and no clear evolution of heights with system age. This could be explained by early stirring within the belt by large bodies (with sizes of at least ~140 km to the size of the Moon), by inheritance of inclinations from the protoplanetary disc stage, or by a diversity in evolutionary pathways and gravitational stirring mechanisms. We release the REASONS legacy multidimensional sample of millimetre-resolved belts to the community as a valuable tool for follow-up multi-wavelength observations and population modelling studies.
Studies of stationary features in jets: BL Lacertae
Authors: Arshakian T. G. , Hambardzumyan L. A. , Pushkarev A. B. , Homan D. C.
Published: November 2024

Context. High-resolution very long baseline interferometry observations have revealed a quasi-stationary component (QSC) in the relativistic jets of many blazars, which represents a standing recollimation shock. VLBA monitoring of the BL Lacertae jet at 15 GHz shows the QSC at a projected distance of about 0.26 mas from the radio core.

Aims. We study the trajectory and kinematics of the QSC in BL Lacertae on sub-parsec scales using 15 GHz VLBA data of 164 observations over 20 years from the MOJAVE program and 2 cm VLBA Survey. Methods. To reconstruct the QSC’s intrinsic trajectory, we used moving average and trajectory refinement procedures to smooth out the effects of core displacement and account for QSC positioning errors.

Results. We identified 22 QSC reversal patterns with a frequency of ∼1.5 per year. Most reversals have an acute angle < 90° and a few have a loop-shaped or arc-shaped trajectory. Where observed, combinations of reversals show reversible and quasi-oscillatory motion. We propose a model in which a relativistic transverse wave passes through the QSC, generating a short-lived reverse motion, similar to the transverse motion of a seagull on a wave. According to the model, relativistic waves are generated upstream and the reverse motion of the QSC is governed by the amplitude, velocity, and tilt of the wave as it passes through. The apparent superluminal speeds of the QSC (∼2 c) are then due to the relativistic speed of the jet’s transverse wave (< 0.3 c in the host galaxy rest frame) combined with the relativistic motion towards the observer. The measured superluminal speeds of the QSC indirectly indicate the presence of relativistic transverse waves, and the size of the QSC scattering on the sky is proportional to the maximum amplitude of the wave. We find that most of the transverse waves are twisted in space. In the active state of the jet, the directions of the twisting waves are random, similar to the behaviour of the wave in a high-pressure hose, while in the jet stable state, the wave makes quasi-oscillations with regular twisting.

Conclusions. The study of QSC dynamics in BL Lac-type blazars is important for evaluating the physical characteristics of relativistic transverse jet waves. The latter have important implications for jet physics and open up possibilities for modelling the physical conditions and location in the jet necessary for the excitation of relativistic transverse waves.
Incidence of afterglow plateaus in gamma-ray bursts associated with binary neutron star mergers
Authors: Guglielmi L. , Stratta G. , Dall’Osso S. , Singh P. , Brusa M. , Perna R.
Published: November 2024

One of the most surprising gamma-ray burst (GRB) features discovered with the Swift X-ray telescope (XRT) is a plateau phase in the early X-ray afterglow light curves. These plateaus are observed in the majority of long GRBs, while their incidence in short GRBs (SGRBs) is still uncertain due to their fainter X-ray afterglow luminosity with respect to long GRBs. An accurate estimate of the fraction of SGRBs with plateaus is of utmost relevance given the implications that the plateau may have for our understanding of the jet structure and possibly of the nature of the binary neutron star (BNS) merger remnant. This work presents the results of an extensive data analysis of the largest and most up-to-date sample of SGRBs observed with the XRT, and for which the redshift has been measured. We find a plateau incidence of 18–37% in SGRBs, which is a significantly lower fraction than that measured in long GRBs (> 50%). Although still debated, the plateau phase could be explained as energy injection from the spin-down power of a newly born magnetized neutron star (NS; magnetar). We show that this scenario can nicely reproduce the observed short GRB (SGRBs) plateaus, while at the same time providing a natural explanation for the different plateau fractions between short and long GRBs. In particular, our findings may imply that only a minority of BNS mergers generating SGRBs leave behind a sufficiently stable or long-lived NS to form a plateau. From the probability distribution of the BNS remnant mass, a fraction 18–37% of short GRB plateaus implies a maximum NS mass in the range ∼2.3 − 2.35 M⊙.
Unravelling sub-stellar magnetospheres
Authors: Kavanagh Robert D. , Vedantham Harish K. , Rose Kovi , Bloot Sanne
Published: November 2024

At the sub-stellar boundary, signatures of magnetic fields begin to manifest at radio wavelengths, analogous to the auroral emission of the magnetised solar system planets. This emission provides a singular avenue for measuring magnetic fields at planetary scales in extrasolar systems. So far, exoplanets have eluded detection at radio wavelengths. However, ultracool dwarfs (UCDs), their higher mass counterparts, have been detected for over two decades in the radio. Given their similar characteristics to massive exoplanets, UCDs are ideal targets to bridge our understanding of magnetic field generation from stars to planets. In this work, we develop a new tomographic technique for inverting both the viewing angle and large-scale magnetic field structure of UCDs from observations of coherent radio bursts. We apply our methodology to the nearby T8 dwarf WISE J062309.94-045624.6 (J0623) which was recently detected at radio wavelengths, and show that it is likely viewed pole-on. We also find that J0623’s rotation and magnetic axes are misaligned significantly, reminiscent of Uranus and Neptune, and show that it may be undergoing a magnetic cycle with a period exceeding 6 months in duration. These findings demonstrate that our method is a robust new tool for studying magnetic fields on planetary-mass objects. With the advent of next-generation low-frequency radio facilities, the methods presented here could facilitate the characterisation of exoplanetary magnetospheres for the first time.
Unravelling motives and time use of additional leave in a flexible benefits plan: a mixed-methods case study in Belgium
Authors: Castro Damaris , Bleys Brent
Published: November 2024

Working-time reduction emerges as a promising measure for fostering a well-being economy, as it allows to reconsider time allocation between paid labour and other activities, potentially improving human and environmental well-being. This study investigates the motives for and planned time use of additional leave in the context of a flexible benefits plan, a specific form of working-time reduction that is increasingly popular among employees and employers. Despite its popularity, little is known about the rationale behind this choice and its potential to create socio-environmental benefits. Data were collected from a Belgian media company in 2022 using a mixed-methods approach, comprising a survey (N = 241) and semi-structured interviews (N = 13). The findings reveal that a mix of motives matters for choosing additional leave, including push, pull, personal and contextual factors, as well as the specifics of the flexible benefits plan. While the desire for more leisure emerges as a primary driver, difficulties in taking up the standard amount of leave present a key barrier. Employees plan to use their extra leave for diverse activities, mainly personal and social activities, household tasks, travel, and ad-hoc pursuits. However, preferences vary based on parental status, with couples having children primarily intending to use the leave for caregiving responsibilities. Notably, the primary activities for intended time use align with increased well-being and have relatively low environmental impacts, although positive effects may be partially offset for well-being (such as when paid work is replaced with unpaid care or household work) or for the environment (such as when spending the extra leave on environmentally intensive (travel) activities). These findings tentatively suggest that choosing additional leave in flexible benefits plans could contribute to a well-being economy.
Mechanistic insights into intramolecular energy transfer dynamics in photosensitizers for triplet-triplet annihilation upconversion
Authors: Fu Tingting , Wei Yaxiong , Xu Xinsheng
Published: November 2024

Photosensitizers constitute a crucial element in the process of triplet-triplet annihilation upconversion, necessitating robust absorption of visible or near-infrared light, high intersystem crossing efficiency, prolonged triplet state lifetime, and minimal energy dissipation during intersystem crossing and vibrational relaxation. Nonetheless, conventional monomeric photosensitizers frequently fail to simultaneously meet these requirements. In recent years, researchers, including our group, have fabricated photosensitizers that incorporate multiple covalent linkages, such as dyads and triads, which are regarded more likely to achieve comprehensive performance optimization. This review article explores the design and characteristics of recently synthesized dyads and triads photosensitizers that operate on the principles of intramolecular singlet energy transfer and intramolecular triplet energy transfer, demonstrating their outstanding efficacy in high-efficiency triplet-triplet annihilation upconversion. We provide an exhaustive explanation of the design rationales, photophysical, and photochemical properties of these photosensitizers, along with suggestions for the creation of photosensitizers with enhanced performance. Moreover, we discuss potential avenues and opportunities for the future development of triplet-triplet annihilation upconversion technology.
In-situ measurement of CO2 column density and flame temperature of single biomass particle combustion by laser absorption spectroscopy
Authors: Wang Shaojie , Gu Mingming , Yin Shengming , Zhou Zhongyue , Ma Liuhao , Qi Fei
Published: November 2024

The measurement of the combustion characteristics of a single biomass particle is essential for studying massive biofuel energy conversion process; however, it is challenging due to the small physical scale of the biomass particle flame. In this work, we report an investigation of the combustion behavior of single lignin and single cellulose particle through CO2 absorption spectroscopy and high-speed photography. The biomass samples are prepared with an initial diameter of about 1.0 mm and are ignited on a heating plate placed inside a multi-pass absorption cell. The shape and size transformation of single biomass particle are recorded through high-speed photography, and the combustion temperature and CO2 column densities are measured through laser absorption spectroscopy at 4.172 µm. We find that the maximum combustion temperatures are 1662 ± 38 K and 1569 ± 26 K for lignin and cellulose particle, respectively. Besides, we find that CO2 generation precedes the generation of visible volatile flame for cellulose particle. While for lignin particle, the CO2 generation is found to be almost at the same time as its volatile combustion stage begins. The measurement technique and results presented in this work are of practical interest for biomass combustion studies and arc meaningful for the development of biomass thermal conversion mode.
Experimental observation of fine secular frequency resonance oscillation with a rectilinear ion trap mass spectrometer
Authors: Shan Lixin , Zhang Zuojian , Wei Zhiyang , Gao Yongze , Luo Zhiyuan , Cheng Shiyu , Shu Jinian
Published: November 2024

The mass resolution of the ordinary ion trap mass spectrometer derived from the quadrupole mass spectrometer usually ranges from hundreds to thousands. In this study, the fine secular frequency resonance oscillation was observed with a rectilinear ion trap mass spectrometer. The FWHM of the responding resonance secular frequency of benzene was 0.012 kHz. The corresponding mass resolution was 8600 m/Δm for benzene (m/z=78). The mass spectrometer with secular frequency scanning has a linear response to benzene in the concentration range from 200 ppbv to 10000 ppbv. This study shows a new feature of the secular frequency scanning for ion trap mass spectrometers.
Oxygen reduction reaction activity of Fe-based dual-atom catalysts with different local configurations via graph neural representation
Authors: Xia Xueqian , Ma Zengying , Huang Yucheng
Published: November 2024

The performance of proton exchange membrane fuel cells depends heavily on the oxygen reduction reaction (ORR) at the cathode, for which platinum-based catalysts are currently the standard. The high cost and limited availability of platinum have driven the search for alternative catalysts. While FeN4 single-atom catalysts have shown promising potential, their ORR activity needs to be further enhanced. In contrast, dual-atom catalysts (DACs) offer not only higher metal loading but also the ability to break the ORR scaling relations. However, the diverse local structures and tunable coordination environments of DACs create a vast chemical space, making large-scale computational screening challenging. In this study, we developed a graph neural network (GNN)-based framework to predict the ORR activity of Fe-based DACs, effectively addressing the challenges posed by variations in local catalyst structures. Our model, trained on a dataset of 180 catalysts, accurately predicted the Gibbs free energy of ORR intermediates and overpotentials, and identified 32 DACs with superior catalytic activity compared to FeN4 SAC. This approach not only advances the design of high-performance DACs, but also offers a powerful computational tool that can significantly reduce the time and cost of catalyst development, thereby accelerating the commercialization of fuel cell technologies.
Removing Fermi resonance through deuterated molecules with single C–H bond in C–H stretching region of Raman spectra
Authors: Ullah Nisar , Jiao Zhirun , Bai Jialin , Wang Zhiqiang , Zhang Ruiting , Ma Lin , Lin Ke
Published: November 2024

The Raman spectra in the C-H stretching region are of great importance for the study of the structure and dynamics of organic compounds. However, the Fermi resonance between the first overtone mode of C-H bending vibration and C-H stretching vibration typically results in the disturbance of Raman bands in the C-H stretching region. In this context, a specific deuterated molecule with only one C–H bond was proposed, and it was found that the frequency of the first overtone mode of the C-H bending vibration was significantly different from the frequency of the C-H stretching vibration. Due to the significant discrepancy, Fermi resonance in the C-H stretching region was eliminated from the experimental and theoretical Raman spectra of deuterated leucine, deuterated benzoin, deuterated methanol, and deuterated ethanol. Hence then, the Raman spectra of these specific deuterated compounds in the C-H stretching region can be used to study the structure or the dynamics of the organic compounds.
Vegetation restoration strategies in arid or semi-arid regions—From the perspective of optimal control
Authors: Hou Li-Feng , Gao Shu-Peng , Chang Li-Li , Wu Yong-Ping , Feng Guo-Lin , Wang Zhen , Sun Gui-Quan
Published: November 2024

Inappropriate human activities contribute to the degradation of ecosystems in arid or semi-arid regions. Therefore, emphasizing the importance of strategies for restoring vegetation in these areas cannot be overstated. However, there has been insufficient research on how to develop effective restoration strategies at minimal cost. This paper addresses this gap by studying how optimizing the spatiotemporal distribution of human activities through local and boundary controls can reduce the level of desertification in vegetation pattern structures, thereby facilitating the recovery of arid land vegetation. The results indicate that vegetation restoration depends on the proportion and number of human activity areas, with a trade-off between them. Furthermore, consistent conclusions were obtained on circular regions, demonstrating the robustness of the approach to boundary shapes. This paper aims to offer new insights into the restoration of arid land vegetation and the prevention of catastrophic ecosystem changes from the perspective of optimal control.
Dependence of divertor asymmetries on the toroidal magnetic field
Authors: Deng Guozhong , Yu Lefu , Ding Jiapei , Wang Xiaomei , Yu Changhui , Yang Haihua
Published: November 2024

A study of the effect of toroidal magnetic field (Bt) on the divertor asymmetries is carried out with a plasma transport code under BOUT++ framework with the magnetic equilibria from EAST and C-Mod. For the simulation cases with drifts, the density is larger at the inner divertor target, while the temperature and heat flux are larger at the outer divertor target. The ratio of the total particle flux at the outer target to that of the inner target increases with increasing Bt, while the ratio of the total heat flux at the outer target to that of the inner target decreases with increasing Bt. The in–out divertor asymmetries of both total particle and heat fluxes get weaker with increasing Bt. Further analysis shows that the edge radial transport induced by drifts is much weaker for the simulation case with higher Bt, indicating that drift-driven divertor asymmetries may be less important for future tokamaks with high Bt.
Single-crystal ferroelectric LiNbO3 thin film-based synaptic devices enabled with tunable domain wall current for neuromorphic computing
Authors: Zhu Jiefei , Zhou Changjian , Liu Qi , Zhang Min
Published: November 2024

Neuromorphic devices can emulate the human brain to process information, which receives lots of attention in the field of artificial intelligence. Synaptic devices based on ferroelectric thin films feature low-power consumption, multifunctionality, and scalability. Among them, ferroelectric charged domain wall (CDW) devices have attracted intensive interest for the implementation of memristive devices due to their ultrahigh integration ability inherited from the nanoscale domain wall thickness. In particular, the preparation of wafer-scale single-crystalline ferroelectric thin films via ion-sliced heterogeneous wafer bonding lays a good foundation for large-scale integration of ferroelectric devices with functional circuits. However, the biomimic synaptic characteristics and the systematic demonstration of synaptic devices are largely unexplored for this material system. Here, we demonstrate a model synaptic device based on a single-crystal ferroelectric LiNbO3 thin film, which provides the desired characteristics for neuromorphic computing. The conductance modulation demonstrates good linearity for efficient neuromorphic computing applications. Simulations using the Modified National Institute of Standards and Technology handwritten recognition dataset prove that LiNbO3-based synaptic devices can operate with an online learning accuracy of 95.1%. The injection and annihilation of the CDW are proposed as the basis of the conductivity modulation by combining with the piezoresponse force microscopy and conductive atomic force microscopy mapping measurements. With the mature fabrication process of the ultrathin high-quality ferroelectric thin films, LiNbO3-based synaptic devices have an extensive application prospect for future neuromorphic computing systems.
Improved binary quantum-based Elk Herd optimizer for optimal location and sizing of hybrid system in micro grid with electric vehicle charging station
Authors: Muralikrishnan G. , Preetha K. , Selvakumaran S. , Nagendran J.
Published: November 2024

In recent times, there has been increasing interest in renewable power generation and electric vehicles within the domain of smart grids. The integration of electric vehicles with hybrid systems presents several critical challenges, including increased power loss, power quality issues, and voltage deviations. To tackle these challenges, researchers have proposed various techniques. Effective management of energy systems is essential for maximizing the benefits of integrating a hybrid system with a microgrid at an electric vehicle charging station. This research specifically aims to optimize the location and sizing of such a hybrid system within the microgrid. Additionally, an improved binary quantum-based Elk Herd optimizer approach is proposed. This approach addresses for optimally managing renewable energy sources and load uncertainty. The proposed system also considers the stochastic nature of electric vehicles and operational restrictions, encompassing diverse charging control modes. The proposed technique performance is implemented in MATLAB platform and compared against existing approaches. The analysis demonstrates the effectiveness in achieving optimal location and sizing for a hybrid system with an electric vehicle charging station. Additionally, the proposed approach contributes to minimizing power loss, electricity costs, and average waiting time. Furthermore, the proposed approach reduces computing time, net present cost, and emissions are 12.5 s, 1.1×106 dollar, 2.21×108 g year−1, respectively.
Gradient descent optimization of acoustic holograms for transcranial focused ultrasound
Authors: Sallam Ahmed , Cengiz Ceren , Pewekar Mihir , Hoffmann Eric , Legon Wynn , Vlaisavljevich Eli , Shahab Shima
Published: November 2024

Acoustic holographic lenses, also known as acoustic holograms, can change the phase of a transmitted wavefront in order to shape and construct complex ultrasound pressure fields, often for focusing the acoustic energy on a target region. These lenses have been proposed for transcranial focused ultrasound (tFUS) to create diffraction-limited focal zones that target specific brain regions while compensating for skull aberration. Holograms are currently designed using time-reversal approaches in full-wave time-domain numerical simulations. Such simulations need time-consuming computations, which severely limits the adoption of iterative optimization strategies. In the time-reversal method, the number and distribution of virtual sources can significantly influence the final sound field. Because of the computational constraints, predicting these effects and determining the optimal arrangement is challenging. This study introduces an efficient method for designing acoustic holograms using a volumetric holographic technique to generate focused fields inside the skull. The proposed method combines a modified mixed-domain method for ultrasonic propagation with a gradient descent iterative optimization algorithm. The findings are further validated in underwater experiments with a realistic 3D-printed skull phantom. This approach enables substantially faster holographic computation than previously reported techniques. The iterative process uses explicitly defined loss functions to bias the ultrasound field’s optimization parameters to specific desired characteristics, such as axial resolution, transversal resolution, coverage, and focal region uniformity, while eliminating the uncertainty associated with virtual sources in time-reversal techniques. The proposed techniques enable more rapid hologram computation and more flexibility in tailoring ultrasound fields for specific therapeutic requirements.
Ultra-low-energy defibrillation through adjoint optimization
Authors: Garzón Alejandro , Grigoriev Roman O.
Published: November 2024

This study investigates ultra-low-energy defibrillation protocols using a simple two-dimensional model of cardiac tissue. We find that, rather counter-intuitively, a single, properly timed, biphasic pulse can be more effective in defibrillating the tissue than low energy antitachycardia pacing (LEAP), which employs a sequence of such pulses, succeeding where the latter approach fails. Furthermore, we show that, with the help of adjoint optimization, it is possible to reduce the energy required for defibrillation even further, making it three orders of magnitude lower than that required by LEAP. Finally, we establish that this dramatic reduction is achieved through exploiting the sensitivity of the dynamics in vulnerable windows to promote the annihilation of pairs of nearby phase singularities.
Quantum turbulence in superfluid helium: Decay and energy spectrum
Authors: Kondaurova L. P.
Published: November 2024

The paper presents a comprehensive numerical study of the free decay of vortex tangle in superfluid helium. The initial vortex tangle represents one of the stationary configurations of loops in a counterflow with a laminar normal fluid component. The calculations are carried out in the framework of the vortex line method using the full Biot–Savart law over a wide range of temperatures. The aim of the study is to identify the role of various factors introduced into the numerical procedures (removal of small loops and segments during reconnections, the addition of and exclusion of vortex points on loops) and to determine the evolution of energy spectrum during the decay of quantum turbulence. A statistical approach is used to calculate the kinetic energy distribution on length scales. The calculations are carried out using periodic boundary conditions in a cube. The results show that, in agreement with the Feynman–Vinen theory, initially the rates of reduction in vortex line density at different temperatures are the same. However, when the vortex structure becomes rarefied, the influence of the mutual friction force becomes apparent, in agreement with Schwarz's theory. Statistical method for determining the energy spectrum is used. The Kolmogorov spectrum is not observed during decays at any temperature.
Explainable artificial intelligence for machine learning prediction of bandgap energies
Authors: Masuda Taichi , Tanabe Katsuaki
Published: November 2024

The bandgap is an inherent property of semiconductors and insulators, significantly influencing their electrical and optical characteristics. However, theoretical calculations using the density functional theory (DFT) are time-consuming and underestimate bandgaps. Machine learning offers a promising approach for predicting bandgaps with high precision and high throughput, but its models face the difficulty of being hard to interpret. Hence, an application of explainable artificial intelligence techniques to the bandgap prediction models is necessary to enhance the model's explainability. In our study, we analyzed the support vector regression, gradient boosting regression, and random forest regression models for reproducing the experimental and DFT bandgaps using the permutation feature importance (PFI), the partial dependence plot (PDP), the individual conditional expectation plot, and the accumulated local effects plot. Through PFI, we identified that the average number of electrons forming covalent bonds and the average mass density of the elements within compounds are particularly important features for bandgap prediction models. Furthermore, PDP visualized the dependency relationship between the characteristics of the constituent elements of compounds and the bandgap. Particularly, we revealed that there is a dependency where the bandgap decreases as the average mass density of the elements of compounds increases. This result was then theoretically interpreted based on the atomic structure. These findings provide crucial guidance for selecting promising descriptors in developing high-precision and explainable bandgap prediction models. Furthermore, this research demonstrates the utility of explainable artificial intelligence methods in the efficient exploration of potential inorganic semiconductor materials.
Conjugate heat transfer simulations of a radially cooled gas turbine blade leading edge using a vortex-based fluidic oscillator for sweeping jet impingement
Authors: Farooq Arshad , Chen Shaowen , Zhang Yimin , Yang Pengcheng
Published: November 2024

The turbine blades of aero engines are subjected to extremely high temperatures, particularly at the leading edge, where temperatures can reach approximately 1800–2000 K. Therefore, effective heat load management is crucial. A vortex-based fluidic oscillator for sweeping jet impingement was proposed as an innovative cooling method to enhance heat transfer at leading edge of high-pressure gas turbine blades. This numerical investigation evaluates the cooling performance of a vortex-based sweeping jet compared to steady and conventional sweeping jets in a radially cooled high-pressure turbine blade. In this study, a conjugate heat transfer model based on three-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) equations is employed. The shear stress transport (SST k–ω) model is specifically selected to predict the flow field and heat transfer characteristics of a vortex-based fluidic oscillator applied to the leading edge. To verify the accuracy of numerical calculations, two sets of experimental data were used as benchmark. The results demonstrated strong qualitative and quantitative agreement with experimental data. Various parameters, including coolant mass flow rates (0.171, 0.514, and 0.857 g/s), aspect ratios (0.5, 0.65, and 1), jet-to-wall spacings (H/D = 2, 4, and 6), and pressure drop, were examined to assess overall cooling effectiveness and heat transfer performance. Time-averaged and time-resolved flow field measurements revealed that vortex-based fluidic oscillator significantly enhanced cooling effects and covered a larger impinging area compared to a steady jet. Notably, the vortex-based fluidic oscillator achieved a 24.3% higher heat transfer performance than the steady jet at H/D = 2, with an average temperature decrease in approximately 21 K at leading edge.
Effect of flow direction on circumferential velocity, radial velocity, and flow resistance characteristics of rotating gap structures
Authors: Shen Xufeng , Xu Yuan , Shi Kaige , Li Xin
Published: November 2024

A rotating gap structure is a type of viscous flow resistance using two disks where the rotation of one disk drives the fluid within the gap, generating rotational inertia. This inertia, combined with viscous friction, determines the flow resistance characteristic curve (pressure drop vs flow rate, or Δp-Q curve). By adjusting the disk's rotational speed, the rotational inertia and the Δp-Q curve can be modified. This paper examines how the radial flow direction (positive and negative) affects the circumferential velocity, radial velocity, and the Δp-Q curve of the rotating gap structure through theoretical modeling and experiments. Results show that radial flow direction and rate influence the symmetric distribution of radial velocity and the linear distribution of circumferential velocity, altering the main components of the Δp-Q curve: the viscous flow resistance curve (Δpvis-Q) and the rotational inertia flow resistance curve (Δprot-Q). The study found that the slope of the Δpvis-Q curve is smaller for positive flow than for negative flow due to differences in radial velocity distribution. Additionally, the circumferential velocity is weakened in positive flow and enhanced in negative flow, resulting in a smaller slope of the Δprot-Q curve for positive flow. These factors cause the Δp-Q curve to deviate from linearity, with greater deviation at higher rotational speeds. Finally, experimental verification was conducted, and the measured Δp-Q curve closely matched the theoretical calculations.
Simulation of unsteady ice accretion on horizontal axis wind turbine blade sections in turbulent wind shear condition
Authors: Tahani Mojtaba , Hossein Amirhossein , Hong Jiarong
Published: November 2024

This study presents a comprehensive simulation approach to quantify power losses in horizontal axis wind turbines under environmental icing conditions. It investigates how wind shear and turbulence affect a 2.5 MW wind turbine's performance, particularly under ice accretion. Turbulence intensity, ranging from 1% to 20%, impacts the relative flow fluctuations and angle of attack on the blade sections, influencing the aerodynamic penalty ratio. The incoming wind speed and the flow angle at various blade sections were determined using the unsteady blade element momentum method, considering vortex induction effects and Prandtl and Glauert corrections. For ice accretion analysis, a fully unsteady simulation of computational grid motion due to ice accretion was performed, along with the solution of the multiphase flow of water dispersed particles in cold air, derived from the psychrometric chart. The findings highlight the significant impact of the incoming turbulent wind fluctuations on the dispersion of the ice shape formed at sections corresponding to their radial position on the blade according to the momentary angle of attack fluctuations. The formation of ice profiles along the blade has led to a subsequent degradation in the aerodynamic efficiency of the blade sections, which is directly proportional to the escalation in turbulence intensity. This phenomenon leads to a continual reduction in the power output of the wind turbine. This research provides valuable insights into the performance of wind turbines under icing conditions in real wind fluctuations.
Reconfigurable magnonic crystals: Spin wave propagation in Pt/Co multilayer in saturated and stripe domain phase
Authors: Dhiman Anuj K. , Leśniewski Nikodem , Gieniusz Ryszard , Kisielewski Jan , Mazalski Piotr , Kurant Zbigniew , Matczak Michał , Stobiecki Feliks , Krawczyk Maciej , Lynnyk Artem , Maziewski Andrzej , Gruszecki Paweł
Published: November 2024

To control the spin wave (SW) propagation, external energy sources such as magnetic fields, electric currents, or complex nanopatterning are used, which can be challenging at the deep nanoscale level. In this work, we overcome such limitations by demonstrating SW propagation in Pt/Co multilayers at a remanent state controlled by stripe domain patterns, using Brillouin light scattering and micromagnetic simulations. We show that parallel stripes with a periodicity around 100 nm exhibit reconfigurability, as the stripes can be rotated by applying the in-plane field without damaging their shape. This allows us to study SW propagation perpendicular and parallel to the stripes. We observe multimodal SW spectra—three bands in perpendicular and five in parallel geometry. Numerical results allow us to identify all observed modes and to explain the differences between two configurations by the unequal contribution of all three magnetization components in the SW dynamics. We find that the experimentally measured non-reciprocal dispersion (for the wavevector perpendicular to the stripes) is not the breaking of time-symmetry but the asymmetry in intensity of the measured signals of two different low-frequency modes, which is due to the inhomogeneous SW amplitude distribution over the multilayer thickness and the limited light penetration depth. Our results pave the way for easy reprogrammability and high energy efficiency in nanomagnonics.
Treatment and delay control strategy for a non-linear rift valley fever epidemic model
Authors: Zeb Shah , Mohd Yatim Siti Ainor , Rafiq Muhammad , Ahmad Waheed , Kamran Ayesha , Karim Md. Fazlul
Published: November 2024

Rift Valley Fever (RVF) is a viral disease affecting animals and humans, causing symptoms such as fever, liver damage, and bleeding, particularly prevalent in Africa. This study focuses on numerical solutions for a non-linear delayed dynamic epidemiological model of RVF. It extends a control problem incorporating the susceptible, infected, treated, recovered vector to analyze the impact of measures such as mosquito repellent and treatment. The goal is to examine how time delays in implementing control measures affect the dynamics of an epidemic. The model considers delay factors such as mosquito replication, hospitalization, travel restrictions, and isolation due to the lack of proper vaccination. The study explores the model’s aspects, including the reproduction number, equilibrium points, and stability. Local and global implications are examined using techniques such as the Lyapunov function and the Brauer-F lemma. Numerical analysis employs the non-standard finite difference method, establishing the local stability of the equilibrium through the effective reproduction number Rrvf and sensitivity analysis. The research highlights the importance of treatment and delay strategies in reducing RVF transmission, emphasizing the critical need for immunization and preventive measures.
Statistics of protein electrostatics
Authors: Colburn Taylor , Sarhangi Setare Mostajabi , Matyushov Dmitry V.
Published: November 2024

Molecular dynamics simulations of a small redox-active protein plastocyanin address two questions. (i) Do protein electrostatics equilibrate to the Gibbsian ensemble? (ii) Do the electrostatic potential and electric field inside proteins follow the Gaussian distribution? The statistics of electrostatic potential and electric field are probed by applying small charge and dipole perturbations to different sites within the protein. Nonergodic (non-Gibbsian) sampling is detectable through violations of exact statistical rules constraining the first and second statistical moments (fluctuation–dissipation relations) and the linear relation between free-energy surfaces of the collective coordinate representing the Hamiltonian electrostatic perturbation. We find weakly nonergodic statistics of the electrostatic potential (simulation time of 0.4–1.0 μs) and non-Gibbsian and non-Gaussian statistics of the electric field. A small dipolar perturbation of the protein results in structural instabilities of the protein–water interface and multi-modal distributions of the Hamiltonian energy gap. The variance of the electrostatic potential passes through a crossover at the glass transition temperature Ttr ≃ 170 K. The dipolar susceptibility, reflecting the variance of the electric field inside the protein, strongly increases, with lowering temperature, followed by a sharp drop at Ttr. The linear relation between free-energy surfaces can be directly tested by combining absorption and emission spectra of optical dyes. It was found that the statistics of the electrostatic potential perturbation are nearly Gibbsian/Gaussian, with little deviations from the prescribed statistical rules. On the contrary, the (nonergodic) statistics of dipolar perturbations are strongly non-Gibbsian/non-Gaussian due to structural instabilities of the protein hydration shell.