bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic dipole-driven theory for active flow control in heterogeneous porous media
Authors: Yao Neng-Zhi , Wang Bin , Wang Hao , Wu Chen-Long , Wang Xuesheng
Published: September 2024

Although significant efforts have been directed toward refining active control methods for porous media flows, limited explorations have been devoted to the effects of heterogeneous permeability on fluid flow in such environments. These gaps in understanding pose a challenge in developing effective strategies for regulating flow states in porous media with varying permeability. To address these issues, we propose a hydrodynamic dipole-driven theory, solely leveraging a pair of hydrodynamic point source and sink, to rectify flow in heterogeneous porous media systems, thus enabling precise manipulation of the flow field. By carefully tuning the moment of the hydrodynamic dipole, we demonstrate the complete elimination of flow disturbances arising from permeability heterogeneity, and this restoration of the original uniform flow state effectively homogenizes overall permeability. Furthermore, our theory transcends limitations associated with electroosmotic and magnetic methods that require fluids respond to such physical fields, offering broader applicability and minimizing potential contamination risks. Finally, the inherent relation between potential function and pressure distributions in Dracy's law is established with rigorous theoretical analysis, which lays the foundation for active hydrodynamic metamaterials assisted with hydrodynamic dipole strategy. We anticipate that our findings will significantly advance the field of active flow control, particularly in addressing heterogeneous permeability in complex porous media flows, and provide valuable insights for the development of hydrodynamic metamaterial without reliance on heterogeneous or anisotropic materials.
Nonlinear waves propagating over a deformable seafloor
Authors: Kostikov Vasily K. , Hayatdavoodi Masoud , Ertekin R. Cengiz
Published: September 2024

Interaction of nonlinear shallow water waves with a deformable seafloor represented by an infinitely long elastic sheet lying on a viscoelastic foundation is investigated. The study is motivated by damping features of muddy coastal areas on ocean waves. The mathematical model utilizes the Level I Green–Naghdi equations for the fluid flow and the thin plate theory for the elastic bottom deformations. The methodology is validated through comparisons with the linear water wave theory and available numerical data. Theoretical predictions of the coupled seafloor vertical displacement and free-surface elevation are provided for a range of the incoming wave parameters and the seafloor characteristics. The results demonstrate that the wave experiences significant decrease in amplitude and propagation speed, as a result of the interaction with the deformable seabed. An exponential decay of periodic waves with propagating distance is observed. It is found that the foundation stiffness is of dominating importance, as compared to other parameters of the deformable seafloor. It is shown that waves with shorter wavelength are dissipated strongly by the action of the deformable seafloor while the bottom conditions have less impact on long wave dissipation. Just the opposite, long waves experience significant wave diffraction when compared to the waves with shorter wavelength. Patterns of the velocity field are shown to be modulated in magnitude and wavelength contributed by the seafloor.
Shape effects on the local dynamics of suspensions of spheroidal particles
Authors: Lu Jiacai , Xu Xu , Zhong Shijie , Ni Rui , Tryggvason Gretar
Published: September 2024

The effect of shape on the dynamics of suspensions of non-spherical heavy particles is examined by fully resolved numerical simulations of oblate and prolate spheroids, as well as spheres, for a density ratio of ten, volume fractions ranging from 0.5% to 5%, and Reynolds numbers between 20 and 30. The dynamics is determined both by the interactions of the particles with the fluid as well as by collisions, with the number and importance of collisions increasing with volume fractions. A single isolated oblate or prolate spheroid falling under gravity generally falls broadside on, for the governing parameters examined here, and at low-volume fractions, the majority of particles in a suspension fall that way. At higher-volume fractions, the orientation is more random. The slip velocity decreases as the volume fraction increases for all shapes, as expected, but the effect of the shape is much less than seen for a single particle. This seems to be due to two effects. For all volume fractions, the most deformed particles cluster more than spheres and less deformed particles, which increases their slip velocity. As the concentration increases, the increased particle interactions also causes more particles to fall short side-on, which reduces the frontal area and the resulting drag, increasing the slip velocity. This second effect is, of course, absent for spherical particles.
Quantum solution of classical turbulence: Decaying energy spectrum
Authors: Migdal Alexander
Published: September 2024

This paper presents a recent advancement that transforms the problem of decaying turbulence in the Navier–Stokes equations in 3 + 1 dimensions into a Number Theory challenge: finding the statistical limit of the Euler ensemble. We redefine this ensemble as a Markov chain, establishing its equivalence to the quantum statistical theory of N Fermions on a ring, interacting with an external field associated with random fractions of π. Analyzing this theory in the turbulent limit, where N→∞ and ν→0, we discover the solution as a complex trajectory (instanton) that acts as a saddle point in the path integral over the density of these Fermions. By computing the contribution of this instanton to the vorticity correlation function, we obtain an analytic formula for the observable energy spectrum—a complete solution of decaying turbulence derived entirely from first principles without the need for approximations or fitted dimensionless parameters. Our analysis reveals the full spectrum of critical indices in the velocity correlation function in coordinate space, determined by the poles of the Mellin transform, which we prove to be a meromorphic function. Real and complex poles are identified, with the complex poles reflecting dissipation and uniquely determined by the famous complex zeros of the Riemann zeta function. Universal functions of the scaling variables supersede the traditional turbulent scaling laws (K41, Heisenberg, and multifractal). These functions for the energy spectrum, energy decay rate, and velocity correlation significantly deviate from power laws but closely match the results from grid turbulence experiments [Comte-Bellot and Corrsin, J. Fluid Mech. 48(2), 273–337 (1971); Comte-Bellot and Corrsin, J. Fluid Mech. 25(4), 657–682 (1966)] and recent direct numerical simulation data [Panickacheril John, Donzis, and Sreenivasan, Philos. Trans. A Math. Phys. Eng. Sci. 380(2218), 20210089 (2022)] within experimental error margins.
Convection induced by centrifugal and Coriolis buoyancy in a rotating Hele-Shaw reactor
Authors: Bratsun D. A. , Utochkin V. Yu.
Published: September 2024

The study of heat and mass transfer in a Hele-Shaw cell rotating around a perpendicular axis has various advanced technological applications. These include the design of microfluidic devices and continuous-flow chemical microreactors, to name a couple. In this setup configuration, the quasi-two-dimensional design allows for recording the density field using optical methods, and the rotation enables control of this field through spatially distributed inertial forces. As is known, in the limit of an infinitely thin layer, the Coriolis force vanishes within a standard mathematical model. However, experimental observations of fluid flow in a rotating Hele-Shaw cell indicate the opposite. In this paper, we show that the correct derivation of the equation of motion under the Hele-Shaw approximation leads to the appearance of a Boussinesq-type term for the Coriolis force. To study the effect of the Coriolis buoyancy, we consider the problem of fluid stability during the internal generation of a transfer component, which can be either the concentration of the dissolved substance or the temperature of the medium. The careful study of system dynamics involves linear stability analysis, weakly nonlinear analysis, and direct numerical simulation. The general properties of the disturbance spectrum are analyzed. The branching of solutions near the first bifurcation is studied using the technique of multiple time scales. A stationary convection is replaced by an oscillatory one under the action of the Coriolis force, as demonstrated by weakly nonlinear analysis. Finally, we investigate the nonlinear dynamics using direct numerical simulation.
Flexible non-Brownian filament in intensified shear flow
Authors: Lu Yetao , Huang Haibo
Published: September 2024

The behavior of a three-dimensional, non-Brownian flexible filament in a low Reynolds number shear flow was investigated through theoretical and numerical analyses. In the phase plane with Reynolds number Re∈[0.03,8] and flow intensity Z∈[800,35 000], four primary motion modes of the filament were identified: rigid, C-buckling, U-turn, and S-turn. By employing the principle of symmetry, a theoretical model was developed to explain the S-turn mode, and we discovered that the critical flow strength for the transition from U-turn to S-turn was approximately Zc=4900. Our numerical simulations confirmed this transition value. In a system devoid of thermal fluctuations, it was observed that the mode transitions of microscale filament precisely corresponded to the abrupt scale rate changes in the non-Newtonian behavior of the macroscopic solution. Although the polymer stress under different modes has distinct underlying causes, they can all be predicted by the generalized Hooke's law.
Rheological analysis of pressure-driven Jeffrey fluid flow between corrugated porous curved walls with slip constraints
Authors: Mujahid M. , Abbas Z. , Rafiq M. Y.
Published: September 2024

Pressure-driven movement is a fundamental concept with numerous applications in various industries, scientific disciplines, and fields of engineering. Its proper execution is vital for promoting revolutionary innovations and providing solutions in numerous sectors. Therefore, this article scrutinizes the pressure-driven flow of a magnetized Jeffrey fluid between two curved corrugated walls. The geometry of the channel is represented mathematically in an orthogonal curvilinear coordinate system. The corrugation grooves are described by sinusoidal functions with phase differences between the corrugated curved walls. The boundary perturbation method is used to find the analytical solution for the velocity and temperature taking the corrugation amplitude as the perturbation parameter. Furthermore, the volumetric flow rate, skin friction coefficient, and local Nusselt numbers are precisely calculated numerically for a variety of parameters, with the results presented comprehensively in tabular form. The impact of dissimilar parameters, such as the curvature parameter, wave number, magnetic parameter, Darcy number, thermal radiation, heat source/sink parameter, Jeffery fluid parameter, and amplitude parameter, on the flow fields is analyzed through graphical and tabular forms and discussed in detail. The results show that the velocity profile increases due to the curvature parameter and the Jeffrey fluid parameter. However, it decreases due to the magnetic parameter. The temperature distribution rises with the thermal slip and heat source/sink parameters. Meanwhile, it declined for the radiation parameter and the curvature parameter. The model can be used to simulate blood flow in arteries with varying geometries and magnetic fields, aiding in the study of cardiovascular diseases and the design of medical devices such as stents.
Electron–photon–phonon interactions in Dirac semimetals: Magneto-optical absorption and mobility analysis
Authors: Hieu Nguyen N. , Nguyen Chuong V. , Kubakaddi S. S. , Hoa Le T. , Phuc Huynh V.
Published: September 2024

We study the magneto-optical properties of Dirac semimetal (DSM) slabs with particular emphasis on Cd3As2 through electron–photon–phonon interactions, focusing on the magneto-optical absorption coefficient (MOAC) and full-width at half maximum (FWHM). Studying the Landau level (LL) energy of DSMs in the (xy) plane and the z-direction revealed a unique deviation from the square root dependence on the magnetic field, distinguishing DSMs from other semiconductors. At high magnetic fields, the electron–hole symmetry in the LL spectrum is broken, indicating a topological phase in DSMs. For undoped DSMs, MOAC is driven by interband transitions, with peaks from one-photon absorption being smaller and positioned to the left of two-photon ones. Increasing the magnetic field increases peak values. FWHM for one- and two-photon processes increases with the magnetic field and follows a T dependence on temperature. In doped DSMs, both intraband and interband transitions occur, with new interband peaks emerging at higher temperatures near the Fermi energy. Increased electron density shifts the peak position slightly toward higher energy. Peaks from optical phonon emission are consistently higher and located to the right of those from optical phonon absorption, indicating a stronger emission process. The FWHM data allow for the estimation of electron mobilities, and using a reasonable broadening parameter, our predicted mobility values agree with experimental results.
Data-driven insights into cavitation phenomena: From spatiotemporal features to physical state transitions
Authors: Wang Zihao , Zhang Guiyong , Wu Jinxin , Sun Tiezhi , Zhou Bo
Published: September 2024

The application of data-driven methods to study cavitation flow provides insights into the underlying mechanisms and richer physical details of cavitation phenomena. This paper aims to analyze the physically interpretable multi-state cavitation behavior. Initially, the spatiotemporal features of the cavitation flow are represented as network trajectories using principal component analysis. The k-means++ algorithm is then employed to obtain coarse-grained flow field states, and the centroid of each cluster served as a representative for the attributes of that state. Subsequently, the Markov state model is constructed to capture the dynamic transitions in the cavitation flow field. Through a detailed analysis of the dynamic transition model, the cavitation flow field states with genuine physical mechanisms are refined. Finally, proper orthogonal decomposition (POD) is utilized to extract the flow patterns corresponding to different states. The distribution characteristics of the flow field modes in different states correspond to their physical properties. These data-driven algorithm enables a detailed analysis of the typical states in periodic cavitation processes, such as cavity growth, development, shedding, and collapse, providing a deeper understanding of the cavitation flow characteristics in different typical states.
Microstructure evolution of coal undergoing in situ demineralization and ensued impacts on seepage characteristics
Authors: Luo Peng , Zhang Zhenyu , Hao Shengpeng , Liu Xiaoqian , Guang Wenfeng
Published: September 2024

The natural fracture system present in coal provides the principal channel for transporting coalbed methane. Dissolving or modifying mineral occlusions has the potential to enhance the permeability of highly mineralized coal seams. In this study, low-rank mineralized coal was examined using x-ray computed tomography (CT) scanning. A novel in situ demineralization method based on coal CT images was developed using an improved pore-scale three-dimensional morphological modeling algorithm to further investigate the effect of mineral alteration on the dynamic evolution of microstructure and seepage characteristics. The results indicate that the development of pore-fracture and the alteration of mineralogical properties affect the demineralization work. Demineralization increases the connected porosity from 4.16% to 15.42%, significantly increasing the interconnected pore space of the coal. Meanwhile, permeability improved from 0.73 to 2.15 μm2, and a 194.5% increase after the completion of the demineralization work. A higher demineralization degree can develop the preferential flow channels well, resulting in a more rapid pore pressure drop. As demineralization progresses, the flow streamline distribution becomes more homogeneous, and new flow channels emerge. The proposed method shows superior performance in poorly connected areas, with a 69.29% higher permeability compared to previous methods.
Monitoring surgical nociception using multisensor physiological models
Authors: Subramanian Sandya , Tseng Bryan , del Carmen Marcela , Goodman Annekathryn , Dahl Douglas M. , Barbieri Riccardo , Brown Emery N.
Published: September 2024

Monitoring nociception, the flow of information associated with harmful stimuli through the nervous system even during unconsciousness, is critical for proper anesthesia care during surgery. Currently, this is done by tracking heart rate and blood pressure by eye. Monitoring objectively a patient’s nociceptive state remains a challenge, causing drugs to often be over- or underdosed intraoperatively. Inefficient management of surgical nociception may lead to more complex postoperative pain management and side effects such as postoperative cognitive dysfunction, particularly in elderly patients. We collected a comprehensive and multisensor prospective observational dataset focused on surgical nociception (101 surgeries, 18,582 min, and 49,878 nociceptive stimuli), including annotations of all nociceptive stimuli occurring during surgery and medications administered. Using this dataset, we developed indices of autonomic nervous system activity based on physiologically and statistically rigorous point process representations of cardiac action potentials and sweat gland activity. Next, we constructed highly interpretable supervised and unsupervised models with appropriate inductive biases that quantify surgical nociception throughout surgery. Our models track nociceptive stimuli more accurately than existing nociception monitors. We also demonstrate that the characterizing signature of nociception learned by our models resembles the known physiology of the response to pain. Our work represents an important step toward objective multisensor physiology-based markers of surgical nociception. These markers are derived from an in-depth characterization of nociception as measured during surgery itself rather than using other experimental models as surrogates for surgical nociception.
Modulation of m
6
A RNA modification by DAP3 in cancer cells
Authors: Han Jian , Song Yangyang , Xie Jinghe , Tano Vincent , Shen Haoqing , Gan Wei Liang , Ng Larry , Ng Bryan Yik Loong , Ng Vanessa Hui En , Sui Xiaohui , Tang Sze Jing , Chen Leilei
Published: September 2024

N
6
-methyladenosine (m
6
A) RNA methylation is a prevalent RNA modification that significantly impacts RNA metabolism and cancer development. Maintaining the global m
6
A levels in cancer cells relies on RNA accessibility to methyltransferases and the availability of the methyl donor S-adenosylmethionine (SAM). Here, we reveal that death associated protein 3 (DAP3) plays a crucial role in preserving m
6
A levels through two distinct mechanisms. First, although DAP3 is not a component of the m
6
A writer complex, it directly binds to m
6
A target regions, thereby facilitating METTL3 binding. Second, DAP3 promotes
MAT2A
’s last intron splicing, increasing MAT2A protein, cellular SAM, and m
6
A levels. Silencing DAP3 hinders tumorigenesis, which can be rescued by MAT2A overexpression. This evidence suggests DAP3’s role in tumorigenesis, partly through m
6
A regulation. Our findings unveil DAP3’s complex role as an RNA-binding protein and tumor promoter, impacting RNA processing, splicing, and m
6
A modification in cancer transcriptomes.
Sensory integration of food and population density during the diapause exit decision involves insulin-like signaling in
Caenorhabditis elegans
Authors: Zhang Mark G. , Seyedolmohadesin Maedeh , Mercado Soraya Hawk , Tauffenberger Arnaud , Park Heenam , Finnen Nerissa , Schroeder Frank C. , Venkatachalam Vivek , Sternberg Paul W.
Published: September 2024

Decisions made over long time scales, such as life cycle decisions, require coordinated interplay between sensory perception and sustained gene expression. The
Caenorhabditis elegans
dauer (or diapause) exit developmental decision requires sensory integration of population density and food availability to induce an all-or-nothing organismal-wide response, but the mechanism by which this occurs remains unknown. Here, we demonstrate how the Amphid Single Cilium J (ASJ) chemosensory neurons, known to be critical for dauer exit, perform sensory integration at both the levels of gene expression and calcium activity. In response to favorable conditions, dauers rapidly produce and secrete the dauer exit-promoting insulin-like peptide INS-6. Expression of
ins-6
in the ASJ neurons integrates population density and food level and can reflect decision commitment since dauers committed to exiting have higher
ins-6
expression levels than those of noncommitted dauers. Calcium imaging in dauers reveals that the ASJ neurons are activated by food, and this activity is suppressed by pheromone, indicating that sensory integration also occurs at the level of calcium transients. We find that
ins-6
expression in the ASJ neurons depends on neuronal activity in the ASJs, cGMP signaling, and the pheromone components ascr#8 and ascr#2. We propose a model in which decision commitment to exit the dauer state involves an autoregulatory feedback loop in the ASJ neurons that promotes high INS-6 production and secretion. These results collectively demonstrate how insulin-like peptide signaling helps animals compute long-term decisions by bridging sensory perception to decision execution.
An explanation for the prevalence of XY over ZW sex determination in species derived from hermaphroditism
Authors: Lesaffre Thomas , Pannell John R. , Mullon Charles
Published: September 2024

The many independent transitions from hermaphroditism to separate sexes (dioecy) in flowering plants and some animal clades must often have involved the emergence of a heterogametic sex-determining locus, the basis of XY and ZW sex determination (i.e., male and female heterogamety). Current estimates indicate that XY sex determination is much more frequent than ZW, but the reasons for this asymmetry are unclear. One proposition is that separate sexes evolve through the invasion of sterility mutations at closely linked loci, in which case XY sex determination evolves if the initial male sterility mutation is fully recessive. Alternatively, dioecy may evolve via the gradual divergence of male and female phenotypes, but the genetic basis of such divergence and its connection to XY and ZW systems remain poorly understood. Using mathematical modeling, we show how dioecy with XY or ZW sex determination can emerge from the joint evolution of resource allocation to male and female function with its genetic architecture. Our model reveals that whether XY or ZW sex determination evolves depends on the trade-off between allocation to male and female function, and on the mating system of the ancestral hermaphrodites, with selection for female specialization or inbreeding avoidance both favoring XY sex determination. Together, our results cast light on an important but poorly understood path from hermaphroditism to dioecy, and provide an adaptive hypothesis for the preponderance of XY systems. Beyond sex and sex determination, our model shows how ecology can influence the way selection shapes the genetic architecture of polymorphic traits.
Asymmetric fluid flow in helical pipes inspired by shark intestines
Authors: Levin Ido , Sadaba Naroa , Nelson Alshakim , Keller Sarah L.
Published: September 2024

Unlike human intestines, which are long, hollow tubes, the intestines of sharks and rays contain interior helical structures surrounding a cylindrical hole. One function of these structures may be to create asymmetric flow, favoring passage of fluid down the digestive tract, from anterior to posterior. Here, we design and 3D print biomimetic models of shark intestines, in both rigid and deformable materials. We use the rigid models to test which physical parameters of the interior helices (the pitch, the hole radius, the tilt angle, and the number of turns) yield the largest flow asymmetries. These asymmetries exceed those of traditional Tesla valves, structures specifically designed to create flow asymmetry without any moving parts. When we print the biomimetic models in elastomeric materials so that flow can couple to the structure’s shape, flow asymmetry is significantly amplified; it is sevenfold larger in deformable structures than in rigid structures. Last, we 3D-print deformable versions of the intestine of a dogfish shark, based on a tomogram of a biological sample. This biomimic produces flow asymmetry comparable to traditional Tesla valves. The ability to influence the direction of a flow through a structure has applications in biological tissues and artificial devices across many scales, from large industrial pipelines to small microfluidic devices.
Bachatéame, pero con la /s/
Authors: Willis Erik W.
Published: September 2024

Abstracta

El presente estudio analiza la /s/ implosiva en la bachata, un género musical de la República Dominicana asociado
con la clase popular. Se examina la producción de la /s/ implosiva en canciones de trece bachateros y en entrevistas públicas de
un subgrupo de seis integrantes. Los resultados de las canciones de bachata muestran un alto porcentaje de realizaciones completas
de la /s/ implosiva (mayor a 97%); sin embargo, en las entrevistas, la realización completa de la /s/ implosiva se produjo con
menos frecuencia (un promedio de 18%). Al comparar los dos estilos de comunicación, se observa que los bachateros modifican el uso
normal de la elisión de la /s/ implosiva en este dialecto cuando cantan bachata. A pesar de las raíces humildes del género, la
producción de la /s/ implosiva en las canciones de bachata demuestra un comportamiento lingüísticamente hipercorrecto que se
asemeja al habla más formal de los medios de comunicación.
On the magnetostatic scalar potential and magnetic field of a cylindrical magnet
Authors: Martín-Luna P , Gimeno B , González-Iglesias D , Boronat M , Fuster-Martínez N , Martinez-Reviriego P , Martínez E , Menéndez A , Pedraza L , Esperante D
Published: September 2024

The magnetostatic potential and magnetic field of a solid and hollow cylindrical magnet is calculated everywhere in space in terms of complete elliptic integrals. These expressions are calculated using an electromagnetic analogy with the electrostatic potential and electric field of two uniformly charged disks with opposite surface density. The analogy is employed to study intuitively the discontinuities and the dipolar approximation of the fields

H

⃗

and

B

⃗

. The range of validity of the dipolar approximation has been studied along the cylinder axis and in the midplane perpendicular to the cylinder axis, comparing them with the obtained general expression.
1D modeling of plasma streamers at ammonia-air flame conditions
Authors: Sanjeev Taneja Taaresh , Sitaraman Hariswaran , Yang Suo
Published: September 2024

Self-consistent 1D modeling of streamers in ammonia-oxygen-nitrogen-water mixtures has been performed in this work. A fluid model that includes species transport, electrostatic potential, and detailed chemistry was developed and verified. This model is then used to simulate the avalanche, streamer formation and propagation phases, driven by a nanosecond voltage pulse, at different thermochemical conditions derived from a 1D laminar premixed ammonia-air flame. The applicability of the Meek’s criterion in predicting the streamer inception location was successfully confirmed. Streamer formation and propagation duration were found to vary significantly with different thermochemical conditions, due to the difference in ionization rates. The thermochemical state also affected the breakdown characteristics which was tested by maintaining the background reduced electric field constant. Detailed kinetic analyses revealed the importance of

O

(
1

D

)

in the production of key radicals, such as O, OH, and NH2. Furthermore, the contributions of the dissociative electronic excitation of NH3 towards the production of H and NH2 radicals have also been reported. Spatial and temporal evolution of the electron energy loss fractions for various inelastic collision processes at different thermochemical states uncovered the input plasma energy spent of fuel dissociation and the large variability in the dominant processes during the avalanche and streamer propagation phases. The methodology and analyses reported in this work are key towards developing effective strategies for controlled nanosecond-pulsed non-equilibrium plasma sources used for ammonia ignition and flame stabilization.
Machine learning-enhanced stochastic uncertainty and sensitivity analysis of the ICRP human respiratory tract model for an inhaled radionuclide
Authors: Mate-Kole Emmanuel Matey , Howard Sara C , Golden Ashley P , Dewji Shaheen Azim
Published: September 2024

The International Commission on Radiological Protection (ICRP) has developed the reference Human Respiratory Tract Model (HRTM), detailed in ICRP Publications 66 and 130, to estimate the deposition and clearance of inhaled radionuclides. These models utilize reference anatomical and physiological parameters for particle deposition (PD). Biokinetic models further estimate retention and excretion of internalized particulates, aiding the derivation of inhalation dose coefficients (DC). This study aimed to assess variability in deterministic 131I biokinetic and dosimetry models through stochastic analysis using the updated HRTM from ICRP Publication 130. The complexities of the ICRP PD model were reconstructed into a new, independent computational model. Comparison with reference data for total PD fractions for reference worker, solely a nose breather, covering activity median aerodynamic diameters from 0.3 μm to 20 μm, showed a 1.04% relative and 0.7% absolute difference, demonstrating good agreement with ICRP deposition fractions. The deterministic DC module was reconstructed in Python and expanded for stochastic analysis, systematically expanding deposition components from HRTM and assigning probability distribution functions to uncertain parameters. These were integrated into an in-house stochastic radiological exposure dose calculator, utilizing latin hypercube sampling. A case of an occupational radionuclide intake was explored, in which biodistribution and committed effective DC (CEDC) were computed for 131I type F, considering a lognormal particle size distribution with a median of 5 μm. Results showed the published ICRP reference CEDC marginally exceeds the 75th percentile of observed samples, with log-gamma distribution as the best-fit probability distribution. A Random Forest regression model with SHapley Additive exPlanations was employed for sensitivity analysis to predict feature importance. The analysis identified the HRTM particle transport rates scaling factor, followed by the aerodynamic deposition efficiency in the alveolar interstitial region as the most impactful parameters. This study offers a unique stochastic approach on inhaled particulate metabolism, enhancing radiation consequence management, medical countermeasures, and dose reconstruction for epidemiological studies.
Laser-fibre interface for single-particle detector amplification and transportation
Authors: Murray Andrew James
Published: September 2024

Single quantum particle detectors (e.g. photo-multiplier tubes and electron multipliers) produce ns-output pulses that time-correlate to particles that enter them. The detector output pulses usually require amplification at source, before being sent to counting electronics for analysis. A laser-based transport system is detailed here that converts the detector output into light pulses that are injected into single mode fibre. Pulse delivery is then by fibre, so that electrical interference from the laboratory environment and earth grounding loops are eliminated. A fast photodiode and differential amplifier converts the signal exiting the fibre into a voltage pulse for subsequent timing experiments.
A novel method measuring orifice conductance and testing time-of-flight mass spectrometer for water vapor–binary gas
Authors: Geng Jian , Wang Xiaodong , Ren Zhengyi , Tao Wenze , Xi Zhenhua , Zhang Hai , Li Lishan , Guo Meiru
Published: September 2024

The miniature time-of-flight mass spectrometer (TOF-MS) is a crucial instrument for detecting water ice in Chinese Lunar Exploration Program, so it is necessary to compare its detection results for pure water vapor and water vapor–binary gas (such as H2O–N2, H2O–CH4, and H2O–Ar) to evaluate its water detection performance. The throughput must be calculated using the measured conductance to test the miniature TOF-MS. According to the VΔp method, the pΔt method, whose uncertainty is less than 14.2%, is proposed to measure orifice conductance for water vapor–binary gas, and an apparatus was developed based on those two methods. The orifice conductance of four kinds of pure gases (N2, H2O, CH4, and Ar) was measured using those two methods separately, and the measurement results allowed the conductance of the water vapor–binary gas to be calculated through the Equivalent Single Gas method. The conductance of the water vapor–binary gas was measured using the pΔt method, and the difference between the calculated and measured results is less than 7%. Hence, the measured conductance allows the miniature TOF-MS to be tested for the water vapor–binary gas. As throughput is from 10−9 to 10−6 Pa m3 s−1, the difference between the test signals of water vapor–binary gas and pure water vapor is less than 40%.
Application of damping spectrum iterative algorithm for enhanced electrical capacitance tomography image reconstruction
Authors: Zhu Xiaoli , Jiang Xijian , Shi Zhixin , Song Guosheng , Wang Zhenbo
Published: September 2024

In real-world applications, one of the key challenges for electrical capacitance tomography (ECT) measurement is image reconstruction, which is inherently nonlinear and ill-posed, causing its solution to be unstable. To address this issue, the damping spectrum (DS) iterative algorithm once frequently used for solving inverse problems is adopted for the first time in ECT image reconstruction. The relationship between the damping factor and the imaging quality is systematically examined, based on which a method for selecting the optimal damping factor is proposed. The accuracy, efficiency and robustness of the DS iterative algorithm against the traditional linear back projection (LBP) and Landweber algorithms are investigated by numerical simulation and static experiments. Results show that the DS iterative algorithm achieves superior imaging quality with reduced artifact, higher correlation coefficient and lower relative error when compared to the LBP and Landweber algorithms. Moreover, the DS iterative algorithm exhibits significantly higher computational efficiency than the Landweber algorithm, although slightly lower than the LBP algorithm, making it a viable tool for real-time measurements. Static experiments reveal that the imaging quality of the edge flow is better than that of the central flow, primarily due to the inherent soft-field issue in ECT technique which is particularly notable in larger-size ECT sensors. Encouragingly, the effectiveness of the DS iterative algorithm in mitigating the soft-field issue in ECT measurement becomes more pronounced when applied to larger-scale ECT sensors.
Macrophage uptake rate of Sonazoid in breast lymphosonography is highly conserved in healthy controls
Authors: Tichauer Kenneth M , Machado Priscilla , Liu Ji-Bin , Sarathchandra A S Chalmika , Stanczak Maria , Kraft Walter K , Forsberg Flemming
Published: September 2024

Subcutaneous microbubble administration in connection with contrast enhanced ultrasound (CEUS) imaging is showing promise as a noninvasive and sensitive way to detect tumor draining sentinel lymph nodes (SLNs) in patients with breast cancer. Moreover, there is potential to harness the results from these approaches to directly estimate cancer burden, since some microbubble formulas, such as the Sonazoid used in this study, are rapidly phagocytosed by macrophages, and the macrophage concentration in a lymph node is inversely related to the cancer burden. This work presents a mathematical model that can approximate a rate constant governing macrophage uptake of Sonazoid, ki
, given dynamic CEUS Sonazoid imaging data. Twelve healthy women were injected with 1.0 ml of Sonazoid in an upper-outer quadrant of one of their breasts and SLNs were imaged in each patient immediately after injection, and then at 0.25, 0.5, 1, 2, 4, 6, and 24 h after injection. The mathematical model developed was fit to the dynamic CEUS data from each subject resulting in a mean ± sd of 0.006 ± 0.005 h−1 and 0.4 ± 0.1 h−1 for relative lymphatic flow (EFl
) and ki
, respectively. Furthermore, the roughly 25% sd of the ki
measurement was similar to the sd that would be expected from realistic noise simulations for a stable 0.4 h−1 value of ki
, suggesting that macrophage concentration is highly consistent among cancer-free SLNs. These results, along with the significantly smaller variance in ki
measurement observed compared to relative lymphatic flow suggest that ki
may be a more precise and promising approach of estimating macrophage abundance, and inversely cancer burden. Future studies comparing tumor-free to tumor-bearing nodes are planned to verify this hypothesis.
Proton dose calculation with LSTM networks in presence of a magnetic field
Authors: Radonic Domagoj , Xiao Fan , Wahl Niklas , Voss Luke , Neishabouri Ahmad , Delopoulos Nikolaos , Marschner Sebastian , Corradini Stefanie , Belka Claus , Dedes George , Kurz Christopher , Landry Guillaume
Published: September 2024

Objective. To present a long short-term memory (LSTM) network-based dose calculation method for magnetic resonance (MR)-guided proton therapy. Approach. 35 planning computed tomography (CT) images of prostate cancer patients were collected for Monte Carlo (MC) dose calculation under a perpendicular 1.5 T magnetic field. Proton pencil beams (PB) at three energies (150, 175, and 200 MeV) were simulated (7560 PBs at each energy). A 3D relative stopping power cuboid covering the extent of the PB dose was extracted and given as input to the LSTM model, yielding a 3D predicted PB dose. Three single-energy (SE) LSTM models were trained separately on the corresponding 150/175/200 MeV datasets and a multi-energy (ME) LSTM model with an energy embedding layer was trained on either the combined dataset with three energies or a continuous energy (CE) dataset with 1 MeV steps ranging from 125 to 200 MeV. For each model, training and validation involved 25 patients and 10 patients were for testing. Two single field uniform dose prostate treatment plans were optimized and recalculated with MC and the CE model. Results. Test results of all PBs from the three SE models showed a mean gamma passing rate (2%/2 mm, 10% dose cutoff) above 99.9% with an average center-of-mass (COM) discrepancy below 0.4 mm between predicted and simulated trajectories. The ME model showed a mean gamma passing rate exceeding 99.8% and a COM discrepancy of less than 0.5 mm at the three energies. Treatment plan recalculation by the CE model yielded gamma passing rates of 99.6% and 97.9%. The inference time of the models was 9–10 ms per PB. Significance. LSTM models for proton dose calculation in a magnetic field were developed and showed promising accuracy and efficiency for prostate cancer patients.
Physiological definition for region of interest selection in electrical impedance tomography data: description and validation of a novel method
Authors: Francovich Juliette E , Somhorst Peter , Gommers Diederik , Endeman Henrik , Jonkman Annemijn H
Published: September 2024

Objective. Geometrical region of interest (ROI) selection in electrical impedance tomography (EIT) monitoring may lack sensitivity to subtle changes in ventilation distribution. Therefore, we demonstrate a new physiological method for ROI definition. This is relevant when using ROIs to compute subsequent EIT-parameters, such as the ventral-to-dorsal ratio during a positive end-expiratory pressure (PEEP) trial. Approach. Our physiological approach divides an EIT image to ensure exactly 50% tidal impedance variation in the ventral and dorsal region. To demonstrate the effects of our new method, EIT measurements during a decremental PEEP trial in 49 mechanically ventilated ICU-patients were used. We compared the center of ventilation (CoV), a robust parameter for changes in ventro-dorsal ventilation distribution, to our physiological ROI selection method and different commonly used ROI selection methods. Moreover, we determined the impact of different ROI selection methods on the PEEP level corresponding to a ventral-to-dorsal ratio closest to 1. Main results. The division line separating the ventral and dorsal ROI was closer to the CoV for our new physiological method for ROI selection compared to geometrical ROI definition. Moreover, the PEEP level corresponding to a ventral-to-dorsal ratio of 1 is strongly influenced by the chosen ROI selection method, which could have a profound clinical impact; the within-subject range of PEEP level was 6.2 cmH2O depending on the chosen ROI selection method. Significance. Our novel physiological method for ROI definition is sensitive to subtle ventilation-induced changes in regional impedance (i.e. due to (de)recruitment) during mechanical ventilation, similar to the CoV.
Anomalous transient conductivity of magnetic elastomer under the action of strain and magnetic field
Authors: Stepanov G V , Semerenko D A , Raikher Yu L , Bakhtiiarov A V , Lobanov D A , Storozhenko P A
Published: September 2024

Magnetoactive (aka magnetorheological) elastomer composites, which are elastic polymer matrices filled with micron-sized particles of a ferromagnet, are a novel type of magnetically controllable material. In addition to their complex magnetomechanical behavior, magnetoactive elastomers, as conducting substances, possess electrical resistivity that is highly sensitive to both mechanical stress and the applied magnetic field. Here, we present a study on the response of such composites to pulse mechanical or magnetic perturbations. Remarkably, a transient electric process induced by any of those stimuli is always non-monotonic. The electric current measurements reveal that before settling at the new equilibrium level, the resistivity always undergoes a substantial jump-up independently on the sign of the perturbation: a pressure on/off or the field on/off. The main goal of the work is to register the encountered effect in detail.
The OU2 process: characterising dissipative confinement in noisy traps
Authors: Cocconi Luca , Alston Henry , Romano Jacopo , Bertrand Thibault
Published: September 2024

The Ornstein–Uhlenbeck (OU) process describes the dynamics of Brownian particles in a confining harmonic potential, thereby constituting the paradigmatic model of overdamped, mean-reverting Langevin dynamics. Despite its widespread applicability, this model falls short when describing physical systems where the confining potential is itself subjected to stochastic fluctuations. However, such stochastic fluctuations generically emerge in numerous situations, including in the context of colloidal manipulation by optical tweezers, leading to inherently out-of-equilibrium trapped dynamics. To explore the consequences of stochasticity at this level, we introduce a natural extension of the OU process, in which the stiffness of the harmonic potential is itself subjected to OU-like fluctuations. We call this model the OU2 process. We examine its statistical, dynamic, and thermodynamic properties through a combination of analytical and numerical methods. Importantly, we show that the probability density for the particle position presents power-law tails, in contrast to the Gaussian decay of the standard OU process. In turn, this causes the trapping behavior, extreme value statistics, first passage statistics, and entropy production of the OU2 process to differ qualitatively from their standard OU counterpart. Due to the wide applicability of the standard OU process and of the proposed OU2 generalisation, our study sheds light on the peculiar properties of stochastic dynamics in random potentials and lays the foundation for the refined analysis of the dynamics and thermodynamics of numerous experimental systems.
Simulating the motion of a mechanical arm driven by neural circuit
Authors: Zhang Li , Jin Wuyin
Published: September 2024

A simple electromechanical model is constructed in this work to investigate the dynamical behavior of a mechanical arm driven by a light-sensitive neural circuit, simulating the operation of a micromechanical device implanted in the brain under neuronal operation. The physical equation describing the relationship between neural firing and mechanical motion is provided, the dimensionless model is obtained using the scale transformation, and the Hamilton energy of the electromechanical system is calculated based on Helmholtz theorem. It is found that the variation of photocurrent, magnetic field and damping coefficient causes the neuron and mechanical arm to interact with each other to generate a variety of oscillations when the phototube is used as a voltage/current source. Furthermore, it is demonstrated that the conversion of field energy and mechanical energy is another effective method for estimating and controlling the oscillation modes of the electromechanical model. The results explain how a micromassager connected to a neuron processes information from both environment and itself, and provide an insight for the design of implantable neurostimulators to restore brain or muscle function.
Quantum cryptography in the security of cognitive radio networks
Authors: Evelyn Ezhilarasi I , Christopher Clement J , Agnes Nalini Vincent
Published: September 2024

Cognitive radio networks face challenges from malicious users who aim to disrupt decision-making during spectrum sensing and decrease spectrum efficiency. The proposed model seeks to distinguish between the presence and absence of primary user signals using energy detection and also it introduces a quantum-inspired outlier detection mechanism for cognitive radio networks to enhance security and reliability during spectrum sensing by ignoring the identified outliers. It employs BB84 quantum key distribution (QKD) protocol and one time pad for secure transmission of secondary user (SU) local decisions to the fusion center (FC), ensuring data integrity and confidentiality. These decisions are transmitted securely establishing a shared secret key between SU and FC and arrives at a global decision. To make the model more robust, we proposed another novel model with a modified BB84 protocol and compared the results of both the models, offering a robust solution for enhancing the reliability and performance of cognitive radio networks with proven results from simulation.