bluuebunny/crossref_metadata_2025 huggingface dataset:
Extending the low-recycling, flat temperature profile regime in the lithium tokamak experiment-β (LTX-β) with ohmic and neutral beam heating
Authors: Boyle D.P. , Anderson J. , Banerjee S. , Bell R.E. , Capecchi W. , Elliott D.B. , Hansen C. , Kubota S. , LeBlanc B.P. , Maan A. , Maingi R. , Majeski R. , Menard J.E. , Oliva S. , Rhodes T. , Soukhanovskii V. , Zakharov L.
Published: March 2023

Recent experiments in the lithium tokamak experiment-β (LTX-β) have extended the duration, performance, operating conditions, and diagnosis of the flat-temperature profile, low-recycling regime first observed in LTX. As expected, Li retains hydrogen and suppresses edge neutral cooling, allowing increased edge electron temperature, roughly equal to the core T
e. Flat temperature profiles had been obtained transiently in LTX, as the plasma density decayed following the cessation of edge gas puffing. Careful control over the fueling in LTX-β has now been shown to sustain the flat T
e profile and hot edge unique to the low-recycling regime for multiple confinement times in high performance discharges with decaying or steady density. With low density, the flat T
e profile is also seen to extend into the scrape-off layer. Neutral beam heating is observed in target discharges with relatively flat electron temperature profiles (T
edge ∼ T
core/2), though beam heating is stronger in discharges with higher fueling, higher density, and depressed edge T
e. Beam heating produces additional peaking of the T
e profile, without degradation of the energy confinement time. Neutral beam heating of target discharges with relatively flat electron temperature profiles similarly results in broad beam heated temperature profiles. Energy confinement in LTX-β generally compares favorably to ohmic and H-mode scalings, frequently exceeding them by factors of 2–4. New and improved diagnostics in LTX-β enable better characterization of this unique regime, including measurements of ion temperature and high field side Thomson scattering profiles. As an initial step toward characterizing turbulence with no T
e gradient and roughly equal density and pressure gradient, core fluctuation spectra have been measured in peaked T
e discharges using far-forward scattering and fluctuation reflectometry.
Influence of ICRF-NBI synergy on fast ion distribution and plasma performance in second harmonic heating experiments with deuterium NBI at EAST
Authors: Zhang W. , Zhu G.-H. , Zhang X.-J. , Zhong G.-Q. , Ai L. , Chu Y.-Q. , Fan T.-S. , Fan H.-C. , Guo Y.-Y. , Hao B.-L. , Huang J. , Jin Y.-F. , Liu L.-N. , Liao L.-Y. , Li Y.-H. , Liang Q.-C. , Sun Y.-X. , Wang G. X. , Yang D.-K. , Yang H. , Zhang H.-P.
Published: March 2023

Ion Cyclotron Range of Frequencies (ICRF) heating and Neutral Beam Injection (NBI) can have synergy due to the acceleration of NBI beam ions by ICRF wave fields at their harmonics. To understand the influence of ICRF-NBI synergy on fast ion distribution and plasma performance, dedicated experiments and TRANSP simulations have been carried out on EAST. The simulation results are consistent with the experimental results. They show that the ICRF-NBI synergy not only accelerates the NBI beam ions with energy lower than 80 keV to energy larger than 300 keV, but also generates fusion neutrons with energy larger than 3 MeV. Moreover, ICRF-NBI synergy improves the plasma performance by increasing the poloidal beta, plasma stored energy, core ion temperature, total neutron yield and kinetic pressure. In a typical H-mode plasma with 1.0 MW NBI and 1.5 MW ICRF power, it was observed that ICRF-NBI synergy increases the poloidal beta, plasma stored energy, core ion temperature and neutron yield by ∼35%, 33%, 22% and 80%, respectively. Various parameter scans show that the ICRF-NBI synergetic effects can be enhanced by decreasing the minority ion concentration or the distance between the harmonic resonance and magnetic axis, or by increasing the ICRF heating power or NBI beam energy. Consequently, this leads to a generation of fast ions with higher energy. For instance, the maximum energy of the fast ion tail increases from 300 to 600 keV as n(H) decreases from 5% to 0.1%.
Exact densities of loops in O(1) dense loop model and of clusters in critical percolation on a cylinder: II. Rotated lattice
Authors: Povolotsky A M
Published: March 2023

This work continues the study started in Povolotsky (2021 J. Phys. A: Math. Theor.
54 22LT01), where the exact densities of loops in the O(1) dense loop model on an infinite strip of the square lattice with periodic boundary conditions were obtained. These densities are also equal to the densities of critical percolation clusters on the 45∘ rotated square lattice rolled into a cylinder. Here, we extend those results to the square lattice with a tilt. This in particular allows us to obtain the densities of critical percolation clusters on the cylinder of the square lattice of standard orientation extensively studied before. We obtain exact densities of contractible and non-contractible loops or equivalently the densities of critical percolation clusters, which do not and do wrap around the cylinder, respectively. The solution uses the mapping of O(1) dense loop model to the six-vertex model in the Razumov–Stroganov point, while the effective tilt is introduced via the inhomogeneous transfer matrix proposed by Fujimoto. The further solution is based on the Bethe ansatz and Fridkin–Stroganov–Zagier’s solution of Baxter’s T–Q equation. The results are represented in terms of the solution of two explicit systems of linear algebraic equations, which can be performed either analytically for small circumferences of the cylinder or numerically for larger ones. We present exact rational values of the densities on the cylinders of small circumferences and several lattice orientations and use the results of high precision numerical calculations to study the finite-size corrections to the densities, in particular their dependence on the tilt of the lattice.
Superfluid dynamics, equilibrium conditions, and centripetal forces
Authors: Liu Mario
Published: March 2023

Thermodynamics of superfluids is revisited, clarifying two points. First, the density and pressure distribution for given normal and superfluid velocities is obtained, with the finding that counter heat currents give rise to a pressure depression and a centripetal force. Second, it is shown that the ideal two-fluid hydrodynamics is simply an assembly of equilibrium conditions—expressions of entropy being maximal.
Strain fields and critical phenomena in manganites II: spin-lattice-energy Hamiltonians
Authors: Singh Rohit , Puri Sanjay
Published: March 2023

The dynamic critical behavior at the paramagnetic-antiferromagnetic (PM-AFM) transition in manganites has recently been studied experimentally (Niermann et al 2015 Phys. Rev. Lett.
114 037204). We extend the Hamiltonian of paper I by incorporating an energy field, and study the corresponding Model C of critical dynamics. We use the dynamic renormalization group approach and calculate the dynamic critical exponents z,

ν
z

and the line-width exponent Δ to leading order in the small expansion parameters

ϵ
=
4
−
d
+
2
σ

and

ϵ

′

=
4
−
d

. Here, d is the space dimension and σ is the long-range exponent. Using σ as an adjustable parameter, the theory gives us a good match to the experimentally available static and dynamic critical exponents at the PM-AFM transition.
An Inverse Source Problem for A One-dimensional Time-Space Fractional Diffusion Equation
Authors: Lin Rixin , Li Yushan , Nong Linshuzhen
Published: March 2023

For the fractional diffusion equation, it has received extensive study from various angles on the inverse problem. This paper is dedicated to determining a source term with time-dependence of the time-space fractional diffusion equation with additional observation data. First, the implicit difference scheme and the matrix transfer technique are used to solve an initial boundary value direct problem, in which the time-space fractional diffusion equation for the homogeneous Dirichlet boundary condition is considered. For the conclusive solution of the given inverse source problem, a numerical method is proposed based on the optimal perturbation algorithm with optimized Tikhonov regularization. The numerical examples illustrate that our proposed numerical method is highly effective and relatively stable.
Fast Numerical Solution of a Kind of Nonlinear Integral Equations—Dyson-Schwinger Equations for Quark Propagator in Hadron Physics
Authors: Huang Jinghui , Hu Xiangyun , Chen Huan , Duan Xueying , Wang Guangjun
Published: March 2023

The nonlinear integral equation has been widely studied and has become the heart of the matter in many scientific and engineering fields, such as seismology, optical fiber evolution, radio astronomy, and hadron physics with Quantum Chromodynamics. The Dyson-Schwinger Equations (DSEs) approach provides an essential nonperturbative approach to investigating the properties of hadrons and hot/dense quark matter. Mathematically, the Dyson-Schwinger Equations are a group of coupled nonlinear integral equations of quark propagators, gluon propagators, ghost propagators, and various vertices. On account of the non-linearity and singularity of the coupled equations, it is almost impossible to solve the DSEs analytically. One has to resort to the numerical solution of the equations, in which efficient fast algorithms are key points in practice. In this work, two improvements for numerically solving the nonlinear and singular integral equation for quark propagator in a vacuum are proposed. One is a modified interpolation method for unknown functions in the integral with high degrees of freedom. The other is the parallelization on CPUs with OpenMP in GCC Comparing the CPU times with different algorithms, our results indicate that our proposed methods can greatly improve the efficiency and reduce the computation time of the CPU.
Fractals and Finite Distributions of Power Sets
Authors: Zheng Haosen , Li Xiaopei
Published: March 2023

In this paper, we are committed to investigating the fractal decomposition of power sets. Our main result is that every power set can be decomposed into a sum of a power set and an isomorphic set that does not intersect with it. For the finite power set, this property can be drawn on the ordinal line by constructing the fractal number axis of the ordinal line, and the fractal distribution and fractal graph of the finite power set can be obtained by using the parallel translation drawing method. Moreover, the distributions do not overlap or cross. The results in this paper provide a new perspective for further investigation of the fractal distribution of power sets.
Research on Applicability and Efficient Construction with Typical Surrogate Models
Authors: Wang Puyi , Fan Tianfeng , Wang Liguo , Zhou Jiayong , Ning Yanping
Published: March 2023

Surrogate models (SMs) are generally employed in expensive engineering optimization and uncertainty quantification. At present, it is still one of the hot topics for researchers to construct high-performance SMs with limited resources. By comparing the predicted errors of the typical functions, this work intends to obtain the applicability of typical SMs and the count of the necessary experimental samples for efficiently constructing SMs. In detail, representative test functions such as Branin-Hoo, Camelback, Godlstein-Price, Hartman, ZDT3 and ZDT4 are approximated by the models such as PRS, RBF, GP, NN and SVR. The predicted indicators such as R2, RMSE and MAE under multiple groups of experimental samples are discussed by cross-validation. Finally, the applicability of typical SMs and the count of experimental samples in DOE are given, and the conclusion might be a reference for constructing high-performance SMs and an ensemble of SMs.
Smooth Transition of Safety Controllers Filtered by Control Barrier Functions
Authors: Li Shilei , Yuan Zhimin , Ye Qing , Sun Yuhui , Wang Dong , Li Meng
Published: March 2023

Recently, control barrier functions (CBFs), are becoming popular and widely used as a safety-filter of the controller through quadratic programming(QP) optimization framework to ensure the forward invariance of the dynamic systems. However, for sequential safety tasks, the transitions of CBFs are required. To avoid control input discontinuities, firstly, a smooth and speed adjustable transition mechanism by adding a time-varying coefficient of different CBFs is proposed. Moreover, the value of the previous CBF constraint is fixed to reduce the change of the combined CBF constraint. Secondly, a method to integrate different sequential CBFs into a synthetic new one is presented. Through these methods, the smoothness of optimized control inputs can be ensured compared with existing formulations. Simulation results demonstrate that our algorithm provides a smoother transition mechanism to switch different CBFs, and improves the control performance consequently.
A New Method of Solving Fuzzy Linear Systems
Authors: Chen Fanhong , Han Yuanliang , Shao Zejun
Published: March 2023

In this text, our work focuses on fuzzy linear systems where the number of rows and columns of the left correlation coefficient matrix are not equal. A method to handle a wider range of these systems is introduced by our selected more general definition of fuzzy values. Different expressions for the result are obtained based on generalized inverses for different types of the left-hand side expanded matrix. Finally, we verified our method with five cases where the fuzzy values were defined in a more general range. These cases show that the method is simple and effective whether the equations are consistent or not.
A Novel Method of Efficient Max-min Metric for Classification
Authors: Du Mo , Li Shu , Li Qiang
Published: March 2023

Distance metric learning is an important method to study distance metrics that reflect the interaction between features and labels. Because of the high computational complexity and the fact that existing studies on algorithms that measure the similarities with Euclidean distances cannot reflect the real correlations between pairs of samples, learning a suitable distance metric is quite demanding for many data mining tasks. This paper innovatively proposes an extended efficient max-min metric (EMM) that maximizes the total distance between different pairs and minimizes the total distance between similar pairs as much as possible. Simultaneously, the adoption of the local preserving projection framework changes the solution process of the algorithm and improves the speed of the algorithm without losing accuracy. Because traditional EMM only considers pairwise constraints and ignores sample distribution, this study extends EMM based on sample distribution and successfully solves the multi-manifold problem. In the process of data realization, compared with the vector representation method, the use of high-order tensors will make the image representation more accurate and natural. To maintain the structure of higher-order tensors, a tensor-efficient max-min metric (TEMM) is proposed. In order to prove the accuracy and superiority of the research method in this paper, a large number of experiments have been carried out on image processing. The experimental results show that the method proposed in this paper has a good effect.
Global Topology Concept Neighborhood Graph and Its Application in Topological Similarity Measurement
Authors: Cheng Mianmian , Sun Qun , Chen Huanxin , Yang Na , Xing Zhibin , Meng Yao
Published: March 2023

A topological relationship is a key factor in the spatial data processing. Aiming at the problem of topological similarity measurement when the dimension of spatial objects changes in the process of map generalization, this paper proposes a topological similarity measurement method based on the global topological concept neighborhood graph. Firstly, all the topological relationships that can be described by the nine intersection model are abstracted, generalized, and classified, and the classified point/point, point/line, point/polygon, line/line, line/polygon, and polygon/polygon local topological concept neighborhood graphs are established. Then, according to the map generalization rules, the mapping between different types of topological concept neighborhood graphs is established, and the global topological concept neighborhood graph is obtained, Finally, the similarity of the topological relationship between different morphological objects is measured. The experimental results show that the proposed method can better meet the topological similarity measurement when the shape of spatial objects changes.
Study on Vibration Characteristics of Hydraulic Pipes in Case of Internal Pulsating Fluid Excitation
Authors: Zhou Zhi-jin , Liu Ai-jun , Zhou Li-ying
Published: March 2023

The influence of transverse external periodic force on the fluid-structure interaction vibration of hydraulic pipe was researched. Through stress analysis on the pipe under the effect of internal flow, the Bernoulli-beam model in the paper was selected. The equation of fluid-structure interaction vibration was established. By comparing the simulation results of load and no load the transverse external periodic force, a length of hydraulic pipe was analyzed using ansys cfx. The results were shown that the transverse external periodic force strengthened the hydraulic oil’s pressure fluctuation of the pipe internal and the fluid-structure interaction vibration.
Numerical Method of Propulsion Concept: Partially Cut Multiaperture Stick Propellant
Authors: Xue Shao , Wang Hao , Cheng Shenshen
Published: March 2023

The partially cut Multiaperture stick propellant is a new concept charging structure. In this paper, in order to accurately obtain the change and development process of the two-phase flow field in different stages of the whole interior ballistic process in this propulsion concept system, a coupled calculation model of computational interior ballistic is established, which converts the Euler-Lagrange method to the Euler-Euler method. Firstly, at the initial stage of ignition, the Euler-Lagrange method is used to describe the flow field. During this period, the gas phase is based on Euler coordinates, while the solid phase is based on Lagrangian coordinates. After the projectile starts, the partially cut Multiaperture stick propellant is fractured into granular propellant. The flow field is converted to describe by the Euler-Euler method by using the initial mapping method. Finally, by comparing the calculated results with the experimental results, the maximum pressure error is only 0.54%, which verifies the accuracy and effectiveness of the coupling calculation method. It effectively captures the distribution of the physical parameters in the combustion chamber, providing a new research method for the computational interior ballistic of the propulsion concept. Based on this method, the pressure distribution in the propulsion concept system is obtained, and no obvious shock waves and expansion waves are seen, indicating that the charge scheme of partially cut Multiaperture stick propellant can improve launch safety.
Simulation of an Adaptive Model Based on AIC and BIC ARIMA Predictions
Authors: Zhang Ying , Meng Gong
Published: March 2023

ARIMA model forecasting algorithm is a commonly used time series forecasting algorithm, this paper first obtains a stable sequence through differential operation, and then obtains a stable sequence from the AR model, as the MA model, and even the ARIMA model. Select the appropriate model for prediction and use it for adaptive mode model design. In the field of machine learning, the complexity of the model is likely to increase, while the accuracy of the model improves, and the models with a complex structure usually cause the following overfitting problem. In order to balance the complexity and the accuracy of the model reasonably, using appropriate indicators AIC (Akaike Information Criterion), as well as BIC (Bayesian information criterion), to make the judgments, which is achieved by eliciting penalty terms in the paper, and the established ARIMA (1,1,2) model meets the requirements.
Mathematical Modeling of GM (1, 1) Polymorphic Management Based on Dormant System
Authors: Zhang Ying , Peng Di
Published: March 2023

In this paper, a GM(1, 1) polymorphic management prediction algorithm based on a dormant system is proposed, which first obtains the optimal data quantity m through simulation, and then the data used is forecasted only once, and the input data will be updated to the latest data immediately after the prediction is completed, and then the parameter estimates will be recalculated for the next prediction. The simulation results show that the MRE value of the optimized GM (1, 1) is 0.090, which has much better MRE values for GM (1, 1) algorithms that are not optimized. At the same time, other commonly used algorithms in the industry are compared horizontally. In contrast, the optimized GM (1, 1) algorithm responds quickly, has high prediction accuracy, short prediction time, and consumes fewer resources.
Unsupervised Abnormal Transaction Order Detection Method Based on Deep Learning Time Factor
Authors: Wang Cheng , Jin Cheng
Published: March 2023

Abnormal transaction order detection plays an important role in identifying transaction data changes and abnormal transaction behaviors of users. The existing abnormal order detection methods have low generalization ability in different transaction time series, and the exception itself has a variety of patterns. In addition, the positive sample points with a large proportion carry much more information than the abnormal sample points, which will cause the classifier to be disturbed in the learning process and inaccurate classification. The research proposes an unsupervised abnormal transaction order detection method based on the depth learning time factor. By processing the original data column, the first feature sequence is obtained, and then the later feature sequence is trained through the depth learning model. The abnormal order is detected by comparing the differences between the two feature sequences. The results show that the research effectively solves the practical problem of too few abnormal transaction samples, can be applied to the transaction process of different modes, reduces the noise in the original transaction data, and has obvious improvement in each evaluation index compared with the traditional method.
A Study of the Purely Azimuthal Passive Positioning Problem of UAVs
Authors: Zhao Jianqiang , Hu Wei , Dong Zirui , Kang Liwen
Published: March 2023

In order to maintain electromagnetic silence and avoid external interference, UAV clusters usually use purely azimuthal passive positioning methods to adjust the position of UAVs when attempting formation flights. However, due to the large number of UAVs flying in formation, it is difficult to perform effective localization, although they can keep flying at an altitude based on their own sensors. Therefore, this paper establishes a passive positioning model based on the triangulation method under the condition of pure azimuthal passive positioning, solves the coordinates of the UAV position of the received signal by using the least squares problem, and designs the UAV position adjustment scheme by using the optimal scheduling model based on the immune-genetic algorithm, so as to improve the positioning accuracy and survivability of the UAV.
Multi-objective Optimization Design of Solar UAV Overall Parameters
Authors: Hou Yingyu , Ji Chen , Liu Ziqiang
Published: March 2023

Based on the design background of solar UAV, this paper introduces the characteristics of this kind of UAV, such as high flying height, large wingspan, large structural deformation and low wing load. The mathematical model of multi-objective optimization for this type of UAV is established, and the multi-objective genetic algorithm is used to optimize the design. The optimization results of the aircraft design are obtained by computer. Finally, the summary parameters and basic design drawings of this kind of aircraft are given. The results show that multi-objective optimization can be used in the design of solar UAV, and the optimal combination of the overall parameters of this kind of UAV can be obtained to avoid design defects and improve design efficiency. After the optimization design, the overall performance of the aircraft has been improved. This method has a certain reference value for the design of new aircraft.
Simulation and Majorization of Multi-source Relatively Complemented Heating System Based on TRNSYS
Authors: Lv Haotian , Liu Jingxia , Yang Peihong , Li Baoli
Published: March 2023

In order to make up for the shortcomings of solar energy, ground source heat pump as well as air source heat pump during heating, a new multi-complementary heating system with three heat sources is proposed. Take the Tumeteyouqi item as the object of study for program devise and load simulation on the basis of the set scheme, and TRNSYS hybrid heating system is established. The main parameters of the air source heat pump and the solar collector are optimized, and the hooke-Jeewes and Coordinate descent optimization algorithms are used to optimize the annual value of system costs, and the two algorithms are compared. Results are included the Collector area of 80m2, the Collector of 42.1875 ° inclination, Azimuth Angle of 10°. The unit area is homologous and the volume of the water box is 0.10125. The capacity of the water tank is 8.1 m3, and the heat quantity of the air source heat pump is 286200kj/h. The system reaches the optimum, and the annual value of the heating cost is reduced by 3.8%. Then the supply heating cost is reduced by 4.96%. The Hooke-Jeewes algorithm is superior to the Coordinate descent algorithm.
Design of an Airborne γ-ray Spectrometry System Based on Unmanned Aerial Vehicle
Authors: Jia Xu , Qin Guoxiu , Li Fan , Zhao Guozhi
Published: March 2023

An airborne γ-ray spectrometry system that can be installed on an unmanned aerial vehicle (UAV) was designed to satisfy the requirements of radioactive mineral exploration and environmental radiation monitoring. The system consists of an airborne measurement device and a ground control platform. The airborne measurement device includes a γ-ray spectrum survey instrument, the main controller, data and graph transmission module. The ground control platform integrates the data and graph transmission module, industrial computer, energy spectrum analysis and processing software. Field flight tests showed that the data collected by the system were stable and reliable, and the survey results were consistent with existing data. The designed system can be applied to small-scale radioactive geological surveys, environmental surveys, and radioactive pollution monitoring.
Development and Detection Experiment of Scanning Stage for High-throughput Gene Sequencer
Authors: Zhao Yanyan , Cao Yue , Tan Wenjun , Yang Tianshi , Chen Hao
Published: March 2023

In order to meet the requirements of large stroke, high precision, and high acceleration step scanning imaging of the worktable of a high-throughput gene sequencer, a mechanical ultra-precision positioning platform is designed. The XY translation table has a significant impact on the fluxes and accuracy of gene sequencing detection. Using the finite element method to analyze the structural modal and obtain the first-order natural frequency; Then using the vibration test system and laser interferometer to test the first-order natural frequency and the repeat positioning accuracy of the XY translation table. The test results show that the first-order natural frequencies of the platform in X, y and Z directions are 175Hz, 111Hz and 191Hz respectively, which is much higher than the upper-frequency limit of 16.7Hz step scanning servo bandwidth. The two-way repeat positioning accuracy of XY translation table are ± 0.462 µ m and ± 0.429 µ m, meet ± 0.6 µm. So the scanning stage can meet the index requirements of a high-throughput gene sequencers under the specified working conditions, and the measured test data combined with the modal analysis model can provide a research basis for the optimal design of the subsequent platform.
Research on Near Field Signal Behaviour of Localizer Antenna System
Authors: Qu Chunqing
Published: March 2023

Near-field (NF) signal distribution behavior with a radius of 150 meters was studied to compare with far-field (FF) distribution characteristics. It can be found more flexible and detailed in NF than the signal from an NF monitor with only a single location. The origin of the measured value and signal detection method on the equipment was introduced in detail. The three-dimensional model was established and optimized by phase analysis as well as the measured data on-site. There was little difference between a measured distribution and a theoretical calculation in space. The change of directional weakening of the Log Periodic Dipole Antenna (LPDA) was proposed. Unequal amplitude signal synthesis together with Fresnel loss was considered to research and explain the incredible power gain. The modified 3D model is in good agreement with the measured results.
Optical Set up for Scanning System in Manufacturing Inspection
Authors: Salah Yosri Ben , Liu Weiguo , Tian Ailing , Sellami Lamia , Hamida Ahmed Ben
Published: March 2023

Essentially, 3D scanning systems are fundamental in today’s industry, since there is a necessity for the automation of the whole manufacturing process with the aim to achieve better results in terms of accuracy, quality, and manufacturing time. Indeed, experts move towards the integration of high-resolution sensors, and optical devices alongside software, which may offer several advantages for large manufacturing units. In this paper, a stereo vision system is demonstrated in detail while performing a scan. The developed model could be used to carry out several measurement experiments, and the measurement results are analyzed, which proved the correctness and feasibility of the method. Delivered results and outcomes are discussed.
Experimental studies on the propagation of whistler-mode waves in a magnetized plasma structure with a non-uniform density
Authors: SANG Longlong , LU Quanming , XIE Jinlin , ZHANG Qiaofeng , DING Weixing , KE Yangguang , GAO Xinliang , ZHENG Jian
Published: March 2023

Propagation of whistler-mode waves in a magnetized plasma structure is investigated in the Keda linear magnetized plasma device. The magnetized plasma structure has its density peak in the center, and the background magnetic field is homogeneous along the axial direction. A whistler-mode wave with a frequency of 0.3 times of electron cyclotron frequency (f
ce) is launched into the plasma structure. The wave normal angle (WNA) is about 25°, and the wavefront exhibits a wedge structure. During propagation of the whistler wave, both the propagating angle and WNA slowly approach zero, and then the wave is converged toward the center of the structure. Therefore, the wave tends to be trapped in the plasma structure. The results present observational evidence of the propagation of a whistler-mode wave trapped in the enhanced-density structure in a laboratory plasma. This trapping effect is consistent with satellite observations in the inner magnetosphere.
Inversion techniques to obtain local rotation velocity and ion temperature profiles for the x-ray crystal spectrometer on EAST
Authors: LIN Zichao , ZHANG Hongming , WANG Fudi , BAE Cheonho , FU Jia , JIN Yifei , LU Di’an , FU Shengyu , LI Jiankang , LYU Bo
Published: March 2023

Inversion techniques are conducted based on the tangential x-ray crystal spectroscopy (TXCS) geometry on EAST to obtain the local profiles of ion temperature (T
i) and toroidal rotation velocity (v
t). Firstly, local emissivity profiles of the impurity argon are obtained using the asymmetrical Abel inversion. Then, the local v
t and T
i profiles are calculated by considering the local emissivity profiles and the TXCS detailed geometry. In addition, how the changes in the v
t profiles affect the accuracy in the T
i profiles is discussed in detail. It is also found that the line-integrated T
i profiles are becoming less accurate with the increase in the radial gradient in the local v
t profiles. Nonetheless, accurate T
i radial profiles are reconstructed after considering the effects of the emissivity and velocity, which are verified by comparing the inverted v
t and T
i profiles with those local profile measurements from the Charge eXchange Recombination Spectroscopy (CXRS) on EAST.
Adaptive sampling for accelerating neutron diffraction-based strain mapping
*
Authors: Venkatakrishnan S V , Fancher Chris M , Ziatdinov Maxim , Vasudevan Rama , Saleeby Kyle , Haley James , Yu Dunji , An Ke , Plotkowski Alex
Published: March 2023

Neutron diffraction is a useful technique for mapping residual strains in dense metal objects. The technique works by placing an object in the path of a neutron beam, measuring the diffracted signals and inferring the local lattice strain values from the measurement. In order to map the strains across the entire object, the object is stepped one position at a time in the path of the neutron beam, typically in raster order, and at each position a strain value is estimated. Typical dwell times at neutron diffraction instruments result in an overall measurement that can take several hours to map an object that is several tens of centimeters in each dimension at a resolution of a few millimeters, during which the end users do not have an estimate of the global strain features and are at risk of incomplete information in case of instruments outages. In this paper, we propose an object adaptive sampling strategy to measure the significant points first. We start with a small initial uniform set of measurement points across the object to be mapped, compute the strain in those positions and use a machine learning technique to predict the next position to measure in the object. Specifically, we use a Bayesian optimization based on a Gaussian process regression method to infer the underlying strain field from a sparse set of measurements and predict the next most informative positions to measure based on estimates of the mean and variance in the strain fields estimated from the previously measured points. We demonstrate our real-time measure-infer-predict workflow on additively manufactured steel parts—demonstrating that we can get an accurate strain estimate even with 30%–40% of the typical number of measurements—leading the path to faster strain mapping with useful real-time feedback. We emphasize that the proposed method is general and can be used for fast mapping of other material properties such as phase fractions from time-consuming point-wise neutron measurements.
Quantification of Waning Immunity After Measles Vaccination—Evidence From a Seroprevalence Study
Authors: Zibolenová Jana , Hudečková Henrieta , Chladná Zuzana , Malobická Eva , Novák Martin , Waczulíková Iveta , Mikas Ján , Mečochová Adriana
Published: March 2023

We aimed to quantify rates of waning immunity after measles vaccination from seroprevalence data collected in a study of a population with high vaccination coverage and a fixed vaccination schedule. Data were collected during a national survey (the Immunological Survey) carried out in the Slovak Republic in 2018. The average rate of waning immunity against measles after the first dose of measles, mumps, and rubella (MMR) vaccine (ages 1.5–10 years) was 9.7% per year from the geometric mean titer value of 2,634 mUI/mL. The average waning rate after the second dose of MMR vaccine (ages 10–33 years) was significantly lower: 4.8% per year from the lower geometric mean titer of 1,331 mUI/mL. This decline in antibody levels suggests that vaccine-induced protection may be compromised and results in an increase in the proportion of seronegative/borderline individuals. These outcomes may provide a valuable source for critical assessment of direct and indirect effects of MMR vaccination.
The effects of ecology and behavior on the evolution of coloration in Coraciiformes
Authors: Babarović Frane , Cooney Christopher R , Varley Zoë K , Nouri Lara O , Nadeau Nicola J , Thomas Gavin H
Published: March 2023

What drives the evolution of plumage color in birds? Bird color is likely to be under both natural and sexual selection where natural selection may favor evolution toward crypsis or camouflage whereas sexual selection may favor evolution toward conspicuousness. The responses to selection are predicted to relate to species’ ecology, behavior, and life history. Key hypotheses have focused on habitat and light environment, breeding strategy, territoriality, and hunting behavior. We tested these potential causes of color variation in the Coraciiformes, a colorful clade of non-passerine birds, using phylogenetic comparative methods and data on chromatic and achromatic properties of plumage coloration measured from museum specimens. We found that correlates of color evolution in Coraciiformes vary across body regions and depend on the focal color property (chromatic or achromatic properties of plumage coloration). While the light environment showed widespread effects on coloration in multiple body regions for both color properties, selection pressures related to behavioral characteristics had more spatially localized effects (e.g. territoriality on achromatic properties of wing feathers and hunting strategy on chromatic properties of belly feathers). Our results reveal both general patterns that may hold across other bird clades and more nuanced effects of selection that are likely to be mediated through the visual ecology of the signaler and receiver and the behavioral characteristics of Coraciiform species.
Motif elucidation in ChIP-seq datasets with a knockout control
Authors: Denisko Danielle , Viner Coby , Hoffman Michael M
Published: March 2023

Chromatin immunoprecipitation-sequencing is widely used to find transcription factor binding sites, but suffers from various sources of noise. Knocking out the target factor mitigates noise by acting as a negative control. Paired wild-type and knockout (KO) experiments can generate improved motifs but require optimal differential analysis. We introduce peaKO—a computational method to automatically optimize motif analyses with KO controls, which we compare to two other methods. PeaKO often improves elucidation of the target factor and highlights the benefits of KO controls, which far outperform input controls.

Availability and implementation

PeaKO is freely available at https://peako.hoffmanlab.org.

Contact

michael.hoffman@utoronto.ca
PATO: genome-wide prediction of lncRNA–DNA triple helices
Authors: Amatria-Barral Iñaki , González-Domínguez Jorge , Touriño Juan
Published: March 2023

Motivation

Long non-coding RNA (lncRNA) plays a key role in many biological processes. For instance, lncRNA regulates chromatin using different molecular mechanisms, including direct RNA–DNA hybridization via triplexes, cotranscriptional RNA–RNA interactions, and RNA–DNA binding mediated by protein complexes. While the functional annotation of lncRNA transcripts has been widely studied over the last 20 years, barely a handful of tools have been developed with the specific purpose of detecting and evaluating lncRNA–DNA triple helices. What is worse, some of these tools have nearly grown a decade old, making new triplex-centric pipelines depend on legacy software that cannot thoroughly process all the data made available by next-generation sequencing (NGS) technologies.

Results

We present PATO, a modern, fast, and efficient tool for the detection of lncRNA–DNA triplexes that matches NGS processing capabilities. PATO enables the prediction of triple helices at the genome scale and can process in as little as 1 h more than 60 GB of sequence data using a two-socket server. Moreover, PATO’s efficiency allows a more exhaustive search of the triplex-forming solution space, and so PATO achieves higher levels of prediction accuracy in far less time than other tools in the state of the art.

Availability and implementation

Source code, user manual, and tests are freely available to download under the MIT License at https://github.com/UDC-GAC/pato.
Causal inference with misspecified exposure mappings: separating definitions and assumptions
Authors: Sävje F
Published: March 2023

Exposure mappings facilitate investigations of complex causal effects when units interact in experiments. Current methods require experimenters to use the same exposure mappings to define the effect of interest and to impose assumptions on the interference structure. However, the two roles rarely coincide in practice, and experimenters are forced to make the often questionable assumption that their exposures are correctly specified. This paper argues that the two roles exposure mappings currently serve can, and typically should, be separated, so that exposures are used to define effects without necessarily assuming that they are capturing the complete causal structure in the experiment. The paper shows that this approach is practically viable by providing conditions under which exposure effects can be precisely estimated when the exposures are misspecified. Some important questions remain open.
Cardiac sarcoidosis: phenotypes, diagnosis, treatment, and prognosis
Authors: Lehtonen Jukka , Uusitalo Valtteri , Pöyhönen Pauli , Mäyränpää Mikko I , Kupari Markku
Published: March 2023

Cardiac sarcoidosis (CS) results from epithelioid cell granulomas infiltrating the myocardium and predisposing to conduction disturbances, ventricular tachyarrhythmias, and heart failure. Manifest CS, however, constitutes only the top of an iceberg as advanced imaging uncovers cardiac involvement 4 to 5 times more commonly than what is clinically detectable. Definite diagnosis of CS requires myocardial biopsy and histopathology, but a sufficient diagnostic likelihood can be achieved by combining extracardiac histology of sarcoidosis with clinical manifestations and findings on cardiac imaging. CS can appear as the first or only organ manifestation of sarcoidosis or on top of pre-existing extracardiac disease. Due to the lack of controlled trials, the care of CS is based on observational evidence of low quality. Currently, the treatment involves corticosteroid-based, tiered immunosuppression to control myocardial inflammation with medical and device-based therapy for symptomatic atrioventricular block, ventricular tachyarrhythmias, and heart failure. Recent outcome data indicate 90% to 96% 5-year survival in manifest CS with the 10-year figures ranging from 80% to 90%. Major progress in the care of CS awaits the key to its molecular–genetic pathogenesis and large-scale controlled clinical trials.
Long-term outcomes of phenoclusters in severe tricuspid regurgitation
Authors: Rao Vishal N , Giczewska Anna , Chiswell Karen , Felker G Michael , Wang Andrew , Glower Donald D , Gaca Jeffrey G , Parikh Kishan S , Vemulapalli Sreekanth
Published: March 2023

Aims

Severe tricuspid regurgitation (TR) exhibits high 1-year morbidity and mortality, yet long-term cardiovascular risk overall and by subgroups remains unknown. This study characterizes 5-year outcomes and identifies distinct clinical risk profiles of severe TR.

Methods and results

Patients were included from a large US tertiary referral center with new severe TR by echocardiography based on four-category American Society of Echocardiography grading scale between 2007 and 2018. Patients were categorized by TR etiology (with lead present, primary, and secondary) and by supervised recursive partitioning (survival trees) for outcomes of death and the composite of death or heart failure hospitalization. The Kaplan–Meier estimates and Cox regression models were used to evaluate any association by (i) TR etiology and (ii) groups identified by survival trees and outcomes over 5 years. Among 2379 consecutive patients with new severe TR, median age was 70 years, 61% were female, and 40% were black. Event rates (95% confidence interval) were 30.9 (29.0–32.8) events/100 patient-years for death and 49.0 (45.9–52.2) events/100 patient-years for the composite endpoint, with no significant difference by TR etiology. After applying supervised survival tree modeling, two separate groups of four phenoclusters with distinct clinical prognoses were separately identified for death and the composite endpoint. Variables discriminating both outcomes were age, albumin, blood urea nitrogen, right ventricular function, and systolic blood pressure (all P < 0.05).

Conclusion

Patients with newly identified severe TR have high 5-year risk for death and death or heart failure hospitalization. Partitioning patients using supervised survival tree models, but not TR etiology, discriminated clinical risk. These data aid in identifying relevant subgroups in clinical trials of TR and clinical risk/benefit analysis for TR therapies.
Robustness increases heritability: implications for familial disease
Authors: Frank Steven A
Published: March 2023

Robustness protects organisms in two ways. Homeostatic buffering lowers the variation of traits caused by internal or external perturbations. Tolerance reduces the consequences of bad situations, such as extreme phenotypes or infections. This article shows that both types of robustness increase the heritability of protected traits. Additionally, robustness strongly increases the heritability of disease. The natural tendency for organisms to protect robustly against perturbations may partly explain the high heritability that occurs for some diseases.
The evolution of partner specificity in mutualisms
Authors: Carlson Christopher , Akçay Erol , Morsky Bryce
Published: March 2023

Mutualistic species vary in their level of partner specificity, which has important evolutionary, ecological, and management implications. Yet, the evolutionary mechanisms which underpin partner specificity are not fully understood. Most work on specialization focuses on the trade-off between generalism and specialism, where specialists receive more benefits from preferred partners at the expense of benefits from non-preferred partners, while generalists receive similar benefits from all partners. Because all mutualisms involve some degree of both cooperation and conflict between partners, we highlight that specialization to a mutualistic partner can be cooperative, increasing benefit to a focal species and a partner, or antagonistic, increasing resource extraction by a focal species from a partner. We devise an evolutionary game theoretic model to assess the evolutionary dynamics of cooperative specialization, antagonistic specialization, and generalism. Our model shows that cooperative specialization leads to bistability: stable equilibria with a specialist host and its preferred partner excluding all others. We also show that under cooperative specialization with spatial effects, generalists can thrive at the boundaries between differing specialist patches. Under antagonistic specialization, generalism is evolutionarily stable. We provide predictions for how a cooperation-antagonism continuum may determine the patterns of partner specificity that develop within mutualistic relationships.