Miracle-dz/UniFAR-FTUs huggingface dataset:
Magnetohydrodynamic flows in porous media

The aim of this work is to investigate the tensorial filtration law in rigid porous media for steady-state slow flow of an electrically conducting, incompressible and viscous Newtonian fluid in the presence of a magnetic field. The seepage law under a magnetic field is obtained by upscaling the flow at the pore scale. The macroscopic magnetic field and electric flux are also obtained. We use the method of multiple-scale expansions which gives rigorously the macroscopic behaviour without any preconditions on the form of the macroscopic equations. For finite Hartmann number, i.e. ε [Lt ] Ha [Lt ] ε−1, and finite load factor, i.e. ε [Lt ] [Kscr ] [Lt ] ε−1, where ε characterizes the separation of scales, the macroscopic mass flow and electric current are coupled and both depend on the macroscopic gradient of pressure and the electric field. The effective coefficients satisfy the Onsager relations. In particular, the filtration law is shown to resemble Darcy's law but with an additional term proportional to the electric field. The permeability tensor, which strongly depends on the magnetic induction, i.e. Hartmann number, is symmetric, positive and satisfies the filtration analogue of the Hall effect.
Female preferences for high vocal effort in singing mice

Although vocalizations are essential to mammalian sociosexual behaviours, little is known about female preferences for male vocal displays in non-model mammalian species. Here, we characterized female preferences for the advertisement songs of male Alston’s singing mice (Scotinomys teguina). We developed procedures for inducing oestrus, using vaginal perforation as a morphological indicator of oestrus. We then broadcasted ‘high-effort’ and ‘low-effort’ songs recorded from wild-caught males to virgin laboratory-reared females, using a two-choice experiment. Our results indicate that females spent more time investigating speakers playing high-effort songs; surprisingly, this phonotactic response is independent of oestrus status. In wild singing mice, acoustic characteristics of high-effort male songs positively correlate with body condition. Our data suggest that females could use acoustic cues to select mates in good condition, thus providing preliminary support for adaptive mate choice hypotheses. More generally, our results support the hypothesis that elaborate Scotinomys song may be shaped by female choice.
Semi-global stabilization of partially linear composite systems via linear dynamic state feedback

This paper extends the results of the authors (1992) on semi-global stabilization of a class of minimum-phase nonlinear systems via linear state feedback. The class of minimum-phase nonlinear systems considered in this paper subsume those of the previous paper. More specifically, the authors show, by explicit construction of the control laws, that a cascade of linear stabilizable and nonlinear asymptotically stable subsystems is semi-globally stabilizable by linear dynamic feedback of the state of the linear subsystem if the linear subsystem is right invertible and has all its invariant zeros in the closed left half s-plane. The authors' proposed linear dynamic state feedback control law has a single tunable gain parameter that allows for local asymptotical stability and regulation to the origin for any initial condition in some a priori given (arbitrarily large) bounded set. <<ETX>>
New Rate Constants of Hydrogenation of CO on H2O-CO Ice Surfaces

The key route of the formation of solid H2CO and CH3OH on grain surfaces is the hydrogenation reactions. This route was confirmed recently by experiments carried out by Watanabe and his coworkers in 2002 and 2003. On the basis of these experimental results, we derive theoretical formulae and determine the rate constants of the formation of H2CO and CH3OH via the hydrogenation of CO molecules in amorphous H2O-CO ice. In order to reproduce the experimental results, we introduce a new model of the ice called the crack model. We find that the morphology of the ice plays a vital role for the calculations of the rate constants. The rate constants for hydrogenation of CO are k0nH = 0.58-0.52 minute-1 at temperature T = 10 K and 0.23-0.22 minute-1 at T = 15 K, where nH is the number density of hydrogen atoms. For H2CO, the rate constants are k2nH = 0.020-0.013 minute-1 at T = 10 K and 0.075-0.056 minute-1 at T = 15 K. At temperatures 10 and 15 K, the diffusion constant of hydrogen atoms into the amorphous H2O-CO ice is estimated to be 10-21 to 10-20 cm2 s-1, which has little effect on the calculations of the rate constant of the surface hydrogenation. We discuss the deviation of the theoretical results from the experimental ones at late times.
Effect of Socioeconomic Status on Altruistic Behavior in Chinese Middle School Students: Mediating Role of Empathy

Previous studies have shown that socioeconomic status is correlated to altruistic behavior. The role of empathy as one of the motivations for altruistic behavior is gradually gaining attention among researchers. This study explores the role of empathy in the mechanisms of socioeconomic status and altruistic behavior in Chinese adolescents. A total of 253 middle school students from Northern China participated in this study, which included the dictator game and Interpersonal Relation Index. Results showed that (1) low-SES students behaved more generously than high-SES students; (2) the students were more generous to the low-SES recipients, as shown when offering them more money in the dictator game; (3) affective rather than cognitive empathy mediates the relationship between socioeconomic status and altruistic behavior. The findings provide evidence for the validation of the empathy–altruism hypothesis in a group of Chinese adolescents. Meanwhile, it reveals the path to improving altruistic behavior through the promotion of empathy, especially for individuals of high socioeconomic status.
Dynamics of blobs in scrape-off-layer/shadow regions of tokamaks and linear devices

Linear and nonlinear stability of blob propagation in the tokamak scrape off layer (SOL) and in the SOL/shadows of linear devices are studied. It is found that the most stable blobs, which can propagate as coherent structures for large distance, are the blobs with some specific spatial scale. Larger blobs are subject to the Rayleigh–Taylor (RT) instability, which breaks the blob apart and effectively reduces the scale of new structures. Smaller blobs evolve into mushroom structures typical for nonlinear stages of the RT and Richtmyer–Meshkov instabilities in fluids. Biasing of divertor targets can affect the dynamics of blob propagation. For a large magnitude of biasing potential, a strong deformation and even disintegration of the blob as a coherent structure were observed while the blob passes through the biased region.
Is there an asymptotic effect of initial and upstream conditions on turbulence

More than two decades ago the first strong experimental results appeared suggesting that turbulent flows might not be asymptotically independent of their initial (or upstream) conditions [1]. And shortly thereafter the first theoretical explanations were offered as to why we came to believe something about turbulence that might not be true [2]. It was recognized immediately that if turbulence was indeed asymptotically independent of its initial conditions, it meant that there could be no universal single point model for turbulence [2], [3], certainly consistent with experience, but not easy to accept for the turbulence community. Even now the ideas of asymptotic independence still dominate most texts and teaching of turbulence. This paper reviews the substantial additional evidence - experimental, numerical and theoretical - for the asymptotic effect of initial and upstream conditions that has accumulated over the past 20 years. Emphasis has been placed on the canonical turbulent flows (especially wakes, jets, and homogeneous decaying turbulence), which have been the traditional building blocks for our understanding. Some of the implications for the future of turbulence modeling and research, especially LES and turbulence control, are also considered.
Buildup characteristics of roof pollutants in the Shanghai urban area, China

The buildup of roof pollutants in an urban area of Shanghai, China was investigated by conducting 16 experiments between November 2007 and October 2008. Concentrations of Cu, Zn and Cd in runoff from three types of roof (concrete, aluminum and glass) exceeded USEPA National Recommended Water Quality Criteria. The solid/liquid partition of the selected metal elements was consistent for the three roof types: Al, Fe, Zn and Pb were present mainly in the particle-bound form, while the total loading of Cd was nearly 100% in the dissolved form. Atmospheric dry precipitation accounted for most of all pollutant loadings for all roof types, while roof material made only a minor contribution to the loadings. All pollutant accumulation rates except for COD showed a seasonal trend with peaks in spring (March∼May) and winter (December∼February) and troughs in summer (June∼August) and autumn (September∼November). Our results showed that a linear equation is the most reliable of commonly used buildup models to simulate the total phosphorus (TP) and total suspended solids (TSS) buildup processes on aluminum roofs and glass roofs. This study provided novel information about roof runoff in Shanghai, China, in terms of pollution status, pollution source and pollutant buildup processes, thereby aiding in rainwater utilization and non-point pollution control.
Climate-Smart Agriculture Technologies and Determinants of Farmers’ Adoption Decisions in the Great Rift Valley of Ethiopia

Agriculture is a sector that is very vulnerable to the effects of climate change while contributing to anthropogenic greenhouse gas (GHG) emissions to the atmosphere. Therefore, applying Climate-Smart Agriculture (CSA) technologies and practices (referee hereafter as CSA technologies) that can sustainably boost productivity, improve resilience, and lower GHG emissions are crucial for a climate resilient agriculture. This study sought to identify the CSA technologies used by farmers and assess adoption levels and factors that influence them. A cross-sectional survey was carried out gather information from 384 smallholder farmers in the Great Rift Valley (GRV) of Ethiopia. Data were analyzed using percentage, chi-square test, t test, and the multivariate probit model. Results showed that crop diversification, agroforestry, and integrated soil fertility management were the most widely practiced technologies. The results of the chi-square and t tests showed that there are differences and significant and positive connections between adopters and non-adopters based on various attributes. The chi-square and t test results confirmed that households who were older and who had higher incomes, greater credit access, climate information access, better training, better education, larger farms, higher incomes, and more frequent interactions with extension specialists had positive and significant associations with CSA technology adopters. The model result showed that age, sex, and education of the head; farmland size; livestock ownership; income; access to credit; access to climate information; training; and extension contact influenced the adoption of CSA technologies. Therefore, considering barriers to the adoption of CSA technologies, in policy and action is anticipated to support smallholder farmers in adapting to climate change while lowering GHG emissions.
Adaptive control and stabilization of elastic spacecraft

This work treats the question of large angle rotational maneuver and stabilization of an elastic spacecraft (spacecraft-beam-tip body configuration). It is assumed that the parameters of the system are completely unknown. An adaptive control law is derived for the rotational maneuver of the spacecraft. Using the adaptive controller, asymptotically decoupled control of the pitch angle of the space vehicle is accomplished, however this maneuver causes elastic deformation of the beam connecting the orbiter and tip body. For the stabilization of the zero dynamics (flexible dynamics), a stabilizer is designed using elastic mode velocity feedback. In the closed-loop system including the adaptive controller and the stabilizer, reference pitch angle trajectory tracking and vibration suppression are accomplished. Simulation results are presented to show the maneuver capability of the control system.
Self-avoiding walks in a slab: rigorous results

A polymer in the confined spaces between colloid particles loses entropy and exerts a repulsive entropic force on the confining particles. This situation can be modelled by a self-avoiding walk confined in a slab between two parallel planes in the lattice. In this paper, we prove the existence of a limiting free energy for the general case that the walk is interacting with the parallel bounding planes. We also prove that the limiting free energy is strictly increasing with the distance between the bounding planes in some regions of the phase diagram. These results demonstrate the presence of a non-zero repulsive entropic force in the model. Finally, we also examine the relation between the limiting free energy in this model and the limiting free energy in a model of walks adsorbing onto a single plane. We prove that these limiting free energies are equal in some regions of the phase diagram in the limit that the width of the slab between the parallel bounding planes is taken to infinity.
Type II radio emission predictions: Multiple shock ripples and dynamic spectra

[1] A recently developed model of type II radio emission from a single ripple on a global shock is extended to (1) investigate the interaction of multiple shock ripples and (2) calculate the dynamic spectra of radio emission for a shock that consists of multiple independent ripples, as it propagates from 10 solar radii to 1 AU. It is found that the interaction of ripples is relatively unimportant, typically changing the predicted emission level by only 20%. It is predicted that dynamic spectra vary with observer location, which implies that different spacecraft observing the same type II event will see different dynamic spectra. Correlations between source location and dynamic spectra predicted for remote observers are thus investigated and a number of characteristic type II features, such as split bands, are found to be produced naturally by a combination of different source locations and propagation effects such as frequency blocking. The results imply a need for large-scale structure such as large-scale fluctuations in magnetic field orientations, coronal mass ejections, and corotating interaction regions in order to account for the diversity in type II burst observations.
Estimation Bias in Spatial Models with Strongly Connected Weight Matrices

This article shows that, for both spatial lag and spatial error models with strongly connected weight matrices, maximum likelihood estimates of the spatial dependence parameter are necessarily biased downward. In addition, this bias is shown to be present in general Moran tests of spatial dependency. Thus, positive dependencies may often fail to be detected when weight matrices are strongly connected. The analysis begins with a detailed examination of downward bias for the extreme case of maximally connected weight matrices. Results for this case are then extended by continuity to a broader range of (appropriately defined) strongly connected matrices. Finally, a simulated numerical example is presented to illustrate some of the practical consequences of these biases. El siguiente estudio demuestra que en los casos en los cuales las matrices de pesos (o conectividad) poseen alta conectividad, la estimacion de maxima verosimilitud (‘maximum likelihood’) del parametro de dependencia espacial en los modelos de autorregresion presenta necesariamente un sesgo estadistico negativo (ya sean modelos de retardo espacial ‘spatial lag’ o de error espacial ‘spatial error’). Adicionalmente, se demuestra que este sesgo esta presente en el test de Moran de dependencia (autocorrelacion) espacial, y por lo tanto es posible que las dependencias positivas no sean detectadas cuando la conectividad de la matriz de pesos es muy alta. El analisis que se presenta en este articulo comienza con un detallado examen del sesgo negativo para el caso extremo de una matriz con conectividad maxima. Los resultados para este caso son luego aplicados para un rango mas amplio de matrices con conectividad alta. Finalmente, se presenta una simulacion numerica como ejemplo para ilustrar las consecuencias practicas de los sesgos negativos mencionados. 本文研究表明，对于具有强连接权重矩阵的空间滞后和空间误差模型，空间相关性参数的最大似然估计必然存在偏差。 这种偏差同样也存在于常用的空间相关性Moran检测中。 因此，当权重矩阵处于强连接状态下，可能无法检测到其正相关性。 本文详细分析了极端情况下最大连接权重矩阵存在的向下偏差，并不断地向更多类型的（恰当界定的）强连接权重矩阵延拓。 最后借助于数值模拟，进一步分析了这些偏差的实际影响效果。
Transient reflection properties of a dispersive and lossy bi-isotropic slab with an anisotropic laminated composite backing

This paper presents a detailed analysis of the transient reflection from a general bi-isotropic slab backed by a laminated composite. Either a nonreciprocally Tellegen medium or a reciprocally dispersive chiral medium with losses is considered as the bi-isotropic slab. The laminated composite is a graphite-fiber-reinforced-plastic composite (GFRPC), which has been widely used as a replacement for metals and may be treated as a multilayered anisotropic medium from the electromagnetic point of view. For the analysis, a theoretical model is developed based on a state-equation approach. On the basis of this model, both the time-domain and the frequency-domain plane-wave reflection results are obtained and studied. The factors affecting the results, such as the material parameters of the bi-isotropic slab and the fiber-orientation pattern of the GFRPC, are investigated in detail. Some special reflection properties, such as the twist-polarizer reflection and the antireflection, are observed based on this investigation. The properties may lead to a novel transient absorber technology for electromagnetic compatibility (EMC) applications.
Restrictions of Normal Operators, Padé Approximation and Autoregressive Time Series

This work studies restrictions of normal operators on a Hilbert space to so-called Krylov subspaces with special attention to selfadjoint and unitary operators. It is shown that the characteristic polynomials of these restrictions are orthogonal polynomials and furthermore are intimately related to denominators of Pade approximations to certain moment generating functions. These relations are seen to unify certain aspects of Lanczos methods for eigenvalue approximations of selfadjoint operators and autoregressive modeling of time series.
A digital geometry on the tetrakis square tiling—Distance and coarsening

There are various tessellations of the plane, including three regular and eight semi‐regular tilings. The square grid is self‐dual, and the hexagonal and triangular tilings are dual to each other. The semi‐regular tessellations are based on more than one type of regular tiles, while their dual tilings are based on a sole but not a regular tile. In various applications, including Geographical Information Systems, it is worth considering non‐regular grids instead of the most used square grid. In this article, we are interested in the dual of the semi‐regular truncated quadrille tiling, T(8,8,4), which is also known as the Khalimsky grid due to its connectedness structure. In our grid, which is called the tetrakis square or kisquadrille tiling, while it is denoted by D(8,8,4), we consider the right‐angled triangle regions of the usual two‐dimensional Khalimsky graph as tiles/pixels. We give an easy‐to‐use coordinate frame addressing the triangles of all the four different orientations. Neighbor relations are described mathematically based on this frame. Based on the shortest path algorithm, a closed formula is proven to compute the digital, that is, path‐based distance on this grid. Some properties of the distance function have also been studied. Hierarchical coarsening is a frequently used technique both in Geometric and Geographical Information Systems to rescale some parts of the map. The tetrakis square grid is apt for hierarchical coarsening, and thus, it can easily be used in image compression and multigrid and other related methods.
Equivariant Epsilon Constants, Discriminants and Étale Cohomology

Let L/K be a finite Galois extension of number fields. We formulate and study a conjectural equality between an element of the relative algebraic K‐group K0Z[Gal(L/K)], R which is constructed from the equivariant Artin epsilon constant of L/K and a sum of structural invariants associated to L/K. The precise conjecture is motivated by the requirement that a special case of the equivariant refinement of the Tamagawa Number Conjecture of Bloch and Kato (as formulated by Flach and the second‐named author) should be compatible with th functional equation of the associated L‐function. We show that, more concretely, our conjecture also suggests a completely systematic refinement of the central approach and results of classical Galois module theory. In particular, the evidence for our conjecture that we presen here already strongly refines many of the main results of Galois module theory. 2000 Mathematics Subject Classification 11R29, 11R33, 11R42.
Genetic analysis of introgression lines of Oryza rufipogon for improvement of low phosphorous tolerance in indica rice

Soil phosphorus (P) deficiency is one of the major challenges for rice cultivation. The present study was carried out under low soil P condition (available P, < 2 kg ha-1) to study the genetic variability, correlation, path and principal component analysis (PCA) in a set of 40 introgression lines derived from Samba Mahsuri (Oryza sativa ssp. indica) × Oryza rufipogon. High genotypic coefficient of variation and phenotypic coefficient of variation was recorded for productive tillers (PT), seed weight (SW), and grain yield (GY). High heritability coupled with high genetic advance was recorded for plant height (PH), PT, SW, number of spikelets/panicle (SPP), spikelet fertility, and GY. Correlation analysis revealed that grain yield had a significant positive association with PH, PT, panicle length, SPP, and SW. Regression analysis revealed that the grain yield was mainly influenced by PT and SW. This was confirmed by path analysis, wherein PT and SW exerted the highest direct positive effect on grain yield. The PCA revealed that the first two PCs contribute to maximum variability, which together accounted for 60% of the total variability. The traits PT and SW contributed the maximum to load/variance the total variability. Thus, the selection of introgression lines with a greater number of PT and higher SW would be the most appropriate strategy for yield improvement under low soil P condition in rice. Cluster analysis grouped introgression lines along with checks into three clusters. Overall, the study revealed the pattern genetic variability for low P tolerance in the introgression lines. This further helps in designing appropriate breeding strategies for the improvement of rice cultivars for low P tolerance.
Ultrafast intraband spectroscopy of electron capture and relaxation in InAs/GaAs quantum dots

The electron capture and relaxation dynamics in self-assembled InAs/GaAs quantum dots (QDs) is investigated by means of interband-pump–intraband-probe spectroscopy. By tuning femtosecond infrared pulses into resonance with intraband transitions between confined QD states and the wetting layer continuum, the electron population of the QD ground and first excited states is determined as a function of time delay after the interband pump. Our experiments indicate that the most efficient relaxation pathway into the QD ground state is the stepwise relaxation through the excited states of the dot. The capture time at room temperature decreases from 2.8 to 1.5 ps with increasing excitation density above a certain threshold, and changes only slightly at low excitation densities. At low temperature (T=5 K), we determine a longer capture time of 4.7 ps.