Scale Separation Research Articles

Cosmological test of local position invariance from the asymmetric galaxy clustering

ABSTRACT The local position invariance (LPI) is one of the three major pillars of Einstein equivalence principle, ensuring the space–time independence on the outcomes of local experiments. The LPI has been tested by measuring the gravitational redshift effect in various depths of gravitational potentials. We propose a new cosmological test of the LPI by observing the asymmetry in the cross-correlation function between different types of galaxies, which predominantly arises from the gravitational redshift effect induced by the gravitational potential of haloes at which the galaxies reside. We show that the ongoing/upcoming galaxy surveys give a fruitful constraint on the LPI-violating parameter, α, in the distant universe (redshift z ∼ 0.1–1.8) over the cosmological scales (separation s ∼ 5–$10\, {\rm \mathit{ h}^{ -1}\,Mpc}$) that have not yet been explored, finding that the expected upper limit on α can reach 0.03.

Effectiveness of Extension and Advisory Services Provided by Input Dealers during COVID-19 Pandemic

Aim: The main aim of this research is to study the input dealers’ perception towards the extension ad advisory services provided during COVID-19 pandemic.
 Study Design: Cross section research design.
 Place and Duration of Study: Coimbatore and Tiruvallur districts of Tamil Nadu, India. Two years (2021-2022).
 Methodology: From the selected two districts 70 extension officials were randomly selected for conducting the study. Data were collected from the input dealers who delivered extension and advisory services to farmers during COVID-19 pandemic. Paper-Pencil survey method was used to collect data from the farmers. The survey approach is useful for evaluating opinions and trends by gathering quantitative data. A separate scale was developed for assessing the input dealer’s perception towards the effectiveness of extension and advisory services. CIPP model of evaluation was used for developing scale to measure the input dealer’s perception towards the EAS. The developed scale were validated by the experts. A scale was measured using 5-point Likert scale with 1 denoting "strongly disagree and 5 denoting “strongly agree” were employed in this study.
 Results: Majority of the input dealers (70.00%) had medium to very high level of perception towards the effectiveness of extension and advisory services. Input dealer’s perceived that they possessed necessary skills and experience for delivering extension and advisory services. They also perceived that services were made available to farmers on time, door delivery of services were provided, increased agricultural production and productivity of farmers which lead to increased income of the farmers.
 Conclusion: Effectiveness of extension and advisory services provided by input dealers during COVID-19 pandemic was effective in input dealer’s perception. Therefore policy makers must propose a policy in a way that government service provider will work along with the input dealers for delivering extension and advisory services to the farming community. Pluralistic extension approach will be the best option for extension service provider.

Линейные возмущения Блоховского типа пространственно-периодических магнитогидодинамических стационарных состояний. I. Математические вопросы

We consider Bloch eigenmodes in three linear stability problems: the kinematic dynamo problem, the hydrodynamic and MHD stability problem for steady space-periodic flows and MHD states. A Bloch mode is a product of a field of the same periodicity, as the state subjected to perturbation, and a planar harmonic wave, exp(iqx). The complex exponential cancels out from the equations of the respective eigenvalue problem, and the wave vector q remains in the equations as a numeric parameter. The resultant problem has a significant advantage from the numerical viewpoint: while the Bloch mode involves two independent spatial scales, its growth rate can be computed in the periodicity box of the perturbed state. The three-dimensional space, where q resides, splits into a number of regions, inside which the growth rate is a smooth function of q. In preparation for a numerical study of the dominant (i.e., the largest over q) growth rates, we have derived expressions for the gradient of the growth rate in q and proven that, for parity-invariant flows and MHD steady states or when the respective eigenvalue of the stability operator is real, half-integer q (whose all components are integer or half-integer) are stationary points of the growth rate. In prior works it was established by asymptotic methods that high spatial scale separation (small q) gives rise to the phenomena of the α-effect or, for parity-invariant steady states, of the eddy diffusivity. We review these findings tailoring them to the prospective numerical applications.

Effective Governing Equations for Viscoelastic Composites.

We derive the governing equations for the overall behaviour of linear viscoelastic composites comprising two families of elastic inclusions, subphases and/or fibres, and an incompressible Newtonian fluid interacting with the solid phases at the microscale. We assume that the distance between each of the subphases is very small in comparison to the length of the whole material (the macroscale). We can exploit this sharp scale separation and apply the asymptotic (periodic) homogenization method (AHM) which decouples spatial scales and leads to the derivation of the new homogenised model. It does this via upscaling the fluid-structure interaction problem that arises between the multiple elastic phases and the fluid. As we do not assume that the fluid flow is characterised by a parabolic profile, the new macroscale model, which consists of partial differential equations, is of Kelvin-Voigt viscoelastic type (rather than poroelastic). The novel model has coefficients that encode the properties of the microstructure and are to be computed by solving a single local differential fluid-structure interaction (FSI) problem where the solid and the fluid phases are all present and described by the one problem. The model reduces to the case described by Burridge and Keller (1981) when there is only one elastic phase in contact with the fluid. This model is applicable when the distance between adjacent phases is smaller than the average radius of the fluid flowing in the pores, which can be the case for various highly heterogeneous systems encountered in real-world (e.g., biological, or geological) scenarios of interest.

Thermal equilibrium of collisional non-neutral plasma in a magnetic dipole trap

This paper discusses thermal equilibrium states of single-species plasmas, such as pure electron plasmas and pure positron plasmas, that are confined in a dipole trap. Thermal equilibrium states for such plasmas are routinely realized in the homogeneous magnetic field of Penning–Malmberg traps. We generalize the theory of these states to include inhomogeneous magnetic dipole fields. The approach to thermal equilibrium takes place in two stages with well separated time scales. On the collision time scale, thermal equilibrium is established along each magnetic field line. On the much longer transport time scale, heat conduction and viscosity bring the plasmas on different flux contours into thermal equilibrium, we call this a state of global thermal equilibrium. We present numerical results for local and global thermal equilibria. These results agree with the analytic predictions for charge collections that are large compared with the Debye length. There is, in principle, no limit to the confinement time of a single-species plasma in a global thermal equilibrium state. Experiments with hot electron–ion plasmas performed in the LDX and RT1 devices give us confidence that, in contrast to a Penning–Malmberg trap, a magnetic dipole field can also confine cold quasi-neutral electron–positron pair plasmas on the time scale of the phenomena of interest. Such pair plasmas are assumed to form in the magnetosphere of neutron stars but have so far not been realized in a laboratory. The creation of an electron–positron pair plasma is the main goal of the APEX collaboration.

Multiscale modeling of linear elastic heterogeneous structures via localized model order reduction

AbstractIn this article, a methodology for fine scale modeling of large scale linear elastic structures is proposed, which combines the variational multiscale method, domain decomposition and model order reduction. The influence of the fine scale on the coarse scale is modeled by the use of an additive split of the displacement field, addressing applications without a clear scale separation. Local reduced spaces are constructed by solving an oversampling problem with random boundary conditions. Herein, we inform the boundary conditions by a global reduced problem and compare our approach using physically meaningful correlated samples with existing approaches using uncorrelated samples. The local spaces are designed such that the local contribution of each subdomain can be coupled in a conforming way, which also preserves the sparsity pattern of standard finite element assembly procedures. Several numerical experiments show the accuracy and efficiency of the method, as well as its potential to reduce the size of the local spaces and the number of training samples compared to the uncorrelated sampling.

Capturing features of turbulent Ekman–Stokes boundary layers with a stochastic modeling approach

Abstract. Atmospheric boundary layers (ABLs) exhibit transient processes on various time scales that range from a few days down to seconds, with a scale separation of the large-scale forcing and the small-scale turbulent response. One of the standing challenges in modeling and simulation of ABLs is a physically based representation of complex multiscale boundary layer dynamics. In this study, an idealized time-dependent ABL, the so-called Ekman–Stokes boundary layer (ESBL), is considered as a simple model for the near-surface flow in the mid latitudes and polar regions. The ESBL is driven by a prescribed temporal modulation of the bulk–surface velocity difference. A stochastic one-dimensional turbulence (ODT) model is applied to the ESBL as standalone tool that aims to resolve all relevant scales of the flow along a representative vertical coordinate. It is demonstrated by comparison with reference data that ODT is able to capture relevant features of the time-dependent boundary layer flow. The model predicts a parametric enhancement of the bulk–surface coupling in the event of a boundary layer resonance when the flow is forced with the local Coriolis frequency. The latter reproduces leading order effects of the critical latitudes. The model results suggest that the bulk flow decouples from the surface for high forcing frequencies due to a relative increase in detached residual turbulence.

Average Turbulence Dynamics from a One-Parameter Kinetic Theory

We show theoretically that the mean turbulent dynamics can be described by a kinetic theory representation with a single free relaxation time that depends on space and time. A proper kinetic equation is constructed from the Klimontovich-type kinetic equation for fluid elements, which satisfies the Navier–Stokes hydrodynamics exactly. In a suitably averaged form, the turbulent kinetic energy plays the role of temperature in standard molecular thermodynamics. We show that the dynamics of turbulent fluctuations resembles a collision process that asymptotically drives the mean distribution towards a Gaussian (Maxwell–Boltzmann) equilibrium form. Non-Gaussianity arises directly from non-equilibrium shear effects. The present framework overcomes the bane of most conventional turbulence models and theoretical frameworks arising from the lack of scale separation between the mean and fluctuating scales of the Navier-Stokes equation with an eddy viscous term. An averaged turbulent flow in the present framework behaves more like a flow of finite Knudsen number with finite relaxation time, and is thus more suitably described in a kinetic theory representation.

Exact Calculation of Nonideal Fields Demonstrates Their Dominance of Injection in Relativistic Reconnection

Magnetic reconnection is an important source of energetic particles in systems ranging from astrophysics to the laboratory. The large separation of spatiotemporal scales involved makes it critical to determine the minimum physical model containing the necessary physics for modeling particle acceleration. By resolving the energy gain from ideal and nonideal magnetohydrodynamic electric fields self-consistently in kinetic particle-in-cell simulations of reconnection, we conclusively show the dominant role of the nonideal field for the early stage of energization known as injection. The importance of the nonideal field increases with magnetization, guide field, and in three dimensions, indicating its general importance for reconnection in natural astrophysical systems. We obtain the statistical properties of the injection process from the simulations, paving the way for the development of extended MHD models capable of accurately modeling particle acceleration in large-scale systems. The novel analysis method developed in this study can be applied broadly to give new insight into a wide range of processes in plasma physics.

Impact of Inner Control Loops on Small-Signal Stability and Model-Order Reduction of Grid-Forming Converters

The analysis and efficient dynamic simulation of power systems with a large number of distributed generators using grid-forming converter control requires reduced order models. The natural separation of time scales allows for the simplification of the inner control loops, i.e. voltage and current controller. This work provides a structured overview of model reduction approaches of the inner loops and introduces new reduced models based on transfer function approximation. The models are thoroughly tested using frequency response analysis, eigenvalues sensitivity analysis, time-domain simulation and stability regions for various scenarios, varying controller and electrical parameters. Furthermore, the influence of simplifications of the network lines is investigated. It becomes apparent that there is no single reduced model that is suitable for all scenarios. Models ought to be selected depending on the specific scenario. Guidelines for the model selection as well as the choice of controller parameters are provided.

Comparative study of pre- and postauricular flaps for external auditory canal defect reconstruction

BackgroundMalignancies involving the external auditory canal deserve critical evaluation due to this area's aesthetic and functional importance. Flaps can be very useful for the restoration of the external auditory canal. A variety of flaps available for the surgical treatment of external acoustic meatus defects exist, depending on the precise location and size. ObjectivesOur study aimed to compare aesthetic and functional results in the postoncological reconstruction of external auditory canal defects using a preauricular flap and postauricular revolving door flap. MethodsSixteen patients treated at our plastic surgery unit for defects involving the external auditory canal between January 2014 and December 2020 were included in the study. All defects were the result of a primary or secondary skin cancer excision. Patients were divided into two groups, one receiving the preauricular flap technique and the other the postauricular revolving door flap technique. ResultsThree separate visual analog scales reported excellent scores for the two procedures, though the postauricular revolving door flap had slightly better results. Both preauricular flap and postauricular revolving door flap reconstructive techniques showed good options for external auditory canal reconstruction in postexcision skin cancer patients. From an aesthetic point of view, the revolving door flap appeared to be a more elegant surgical approach in this type of reconstruction because the scar was hidden in the postauricular sulcus. ConclusionsReconstruction with a postauricular revolving door flap allowed for a more natural movement with no external pedicle. Evidence-Based Medicine (EBM) LevelIV

A Multifaceted Isoneutral Eddy Transport Diagnostic Framework and Its Application in the Southern Ocean

AbstractWe propose an isoneutral eddy transport diagnostic framework and apply it in the Southern Ocean to analyze eddy potential vorticity (PV) transport dynamics. We leverage a thickness‐weighted spatiotemporal scale separation to define the generalized eddy flux. A local sampling method is employed and validated to estimate the transport tensor. We introduce Leonard's decomposition in Large Eddy Simulations (LES) to split the process into the Reynolds and non‐Reynolds parts. We also use the stationary‐transient decomposition. The non‐Reynolds term and the stationary effect contribute significantly to the transport properties. The Reynolds and transient parts have distinctions, that show oceanic mesoscale dynamics are not synergistic in time and spatial scales. We investigate the spatial scale dependence of each part and find that the transient and stationary components of the Reynolds (non‐Reynolds) term have consistent (dissimilar) scale dependence. The scale dependence of the generalized eddy flux and the transport eigenvalues is controlled by the non‐Reynolds term. We further investigate the eigenvalues in terms of the potential enstrophy and anisotropy. The potential enstrophy in the Southern Ocean holistically has a forward cascade on the researched scales. The Reynolds and transient effects efficiently promote the forward enstrophy cascade. The non‐Reynolds and stationary effects stimulate drastically anisotropic eddy transport. The PV gradient barrier mechanism dominates the drastic anisotropic case. When the anisotropy is weak, a special anisotropic case with a locally balanced potential enstrophy budget overwhelms the case of real isotropy. We also introduce several LES concepts, hoping to enlighten any potential ocean modeling and parameterization.

A Comprehensive Simulation of Solar Wind Formation from the Solar Interior: Significant Cross-field Energy Transport by Interchange Reconnection near the Sun

The physical connection between thermal convection in the solar interior and the solar wind remains unclear due to their significant scale separation. Using an extended version of the three-dimensional radiative magnetohydrodynamic code RAMENS, we perform the first comprehensive simulation of the solar wind formation, starting from the wave excitation and the small-scale dynamo below the photosphere. The simulation satisfies various observational constraints as a slow solar wind emanating from the coronal hole boundary. The magnetic energy is persistently released in the simulated corona, showing a hot upward flow at the interface between open and closed fields. To evaluate the energetic contributions from Alfvén wave and interchange reconnection, we develop a new method to quantify the cross-field energy transport in the simulated atmosphere. The measured energy transport from closed coronal loops to open field accounts for approximately half of the total. These findings suggest a significant role of the supergranular-scale interchange reconnection in solar wind formation.

Work-Family conflict, Social support and Job satisfaction: A Cross-Sectional study of Nurses in Pokhara

INTRODUCTION: Research in the field of nursing has long attempted to address the issue of job dissatisfaction. However, there is scant empirical evidence on work-family conflict and social support in the context of Nepal, both of which are important factors in determining job satisfaction among nurses. Hence, this study examined the role of work-family conflict and social support in determining job satisfaction among nurses in Pokhara. MATERIALS AND METHODS: A descriptive, cross-sectional and correlational study was conducted with a purposive sample of 210 nurses from 10 (public and private) hospitals in Pokhara. Using a Likert-based self-administered structured questionnaire, work-family conflict, social support, and job satisfaction were measured using three separate scales. SPSS 21.0 was used for the correlation and regression analysis of the hypothesized relationships between the variables. RESULTS: The findings revealed that nurses’ job satisfaction was significantly lowered by family-to-work conflicts but not by work-to-family conflicts. The results also demonstrated that social support from management and peers significantly increased nurses’ job satisfaction. CONCLUSIONS: The study concluded that nurses experienced relatively low levels of work-to-family conflict. However, the responsibilities of the home can still affect their job satisfaction. The findings also revealed that social support from both management and coworkers significantly improves nurses' job satisfaction. Implications and suggestions for future study are also presented.

Nonlocality of scale-dependent eddy mixing at the Kuroshio Extension

Although eddy parameterization schemes are often based on the local assumption, previous studies indicate that the nonlocality of total eddy mixing is prevalent at the Kuroshio Extension (KE). For eddy-permitting climate models, only mixing induced by eddies smaller than the resolvable scale of climate models (L*) needs to be parameterized. Therefore, here we aim to estimate and predict the nonlocality of scale-dependent eddy mixing at the KE region. We consider the separation scale L* ranging from 0.2∘ to 2.5∘, which is comparable to the typical resolution of the ocean component of climate models. Using a submesoscale-permitting model solution (MITgcm llc4320) and Lagrangian particles, we estimate the scale-dependent mixing (SDM) nonlocality ellipses and then diagnose the square root of the ellipse area (Ln,particle). Ln,particle is a metric to quantify the degree of SDM nonlocality. We found that, for all the available L* values we consider, the SDM nonlocality is prevalent in the KE region, and mostly elevated values of Ln,particle occur within the KE jet. As L* decreases from 2.5∘ to 0.2∘, the ratio Ln,particle/L* increases from 0.8 to 8.9. This result indicates that the SDM nonlocality is more non-negligible for smaller L*, which corresponds to climate models with relatively high resolution. As to the SDM nonlocality prediction, we found that compared to the conventional scaling and the curve-fitting methods, the random forest approach can better represent Ln,particle, especially in the coastal regions and within the intense KE jet. The area of the Eulerian momentum ellipses well capture the spatial pattern, but not the magnitude, of Ln,particle. Our efforts suggest that eddy parameterization schemes for eddy-permitting models may be improved by taking into account mixing nonlocality.

Young İnternet Bağımlılığı Testinin Boyutluluğunun Üniversite Öğrencileri İçin Mokken Ölçek Analizi Kullanılarak İncelenmesi

The Internet Addiction Test has been used extensively by researchers to collect data from university students, However, empirical studies on the psychometric properties of this test have revealed conflicting results on the factor structure. Although the structure of Internet addiction is generally accepted as unidimensional, these contradictory results require further evidence for the unidimensional nature of the construct. Considering the existing problems regarding the factor structure of the Internet Addiction construct, the aim of this study was set as evaluating the unidimensionality of the Short Internet Addiction Test for University Students by using Mokken Scaling Analysis. The Internet Addiction Test short form was administered to 636 university students studying in Turkey in the 2020-21 academic year via an online data collection platform. The ages of the participants ranged from 20 to 65. The results revealed that the items of the Internet Addiction Test Short Form were scalable and homogeneous enough to form a separate scale. On the other hand, the results showed that the Internet Addiction Test Short Form did not have the Invariant Item Ranking feature. In addition, using the backward selection method, a seven-item form of the Internet Addiction Test Short Form, which has Invariant Item Ordering feature, is proposed. These results showed that the structure of internet addiction can be accepted as one-dimensional for Turkish university students. It is recommended to examine whether the results obtained in future studies can be generalized to different universes.
 Keywords: Mokken scaling analysis, internet addiction, dimensionality, university students.

A new smoothed particle hydrodynamics method based on high-order moving-least-square targeted essentially non-oscillatory scheme for compressible flows

In this study, we establish a hybrid high-order smoothed particle hydrodynamics (SPH) framework (MLS-TENO-SPH) for compressible flows with discontinuities, which is able to achieve genuine high-order convergence in smooth regions and also capture discontinuities well in non-smooth regions. The framework can be either fully Lagrangian, Eulerian or realizing arbitary-Lagrangian-Eulerian (ALE) feature enforcing the isotropic particle distribution in specific cases. In the proposed framework, the computational domain is divided into smooth regions and non-smooth regions, and these two regions are determined by a strong scale separation strategy in the targeted essentially non-oscillatory (TENO) scheme. In smooth regions, the moving-least-square (MLS) approximation is used for evaluating high-order derivative operator, which is able to realize genuine high-order construction; in non-smooth regions, the new TENO scheme based on Vila's framework with several new improvements will be deployed to capture discontinuities and high-wavenumber flow scales with low numerical dissipation. The present MLS-TENO-SPH method is validated with a set of challenging cases based on the Eulerian, Lagrangian or ALE framework. Numerical results demonstrate that the MLS-TENO-SPH method features lower numerical dissipation and higher efficiency than the conventional method, and can restore genuine high-order accuracy in smooth regions. Overall, the proposed framework serves as a new exploration in high-order SPH methods, which are potential for compressible flow simulations with shockwaves.

Assessing Maternal Attitudes: Development, Validation, and Psychometric Properties of the Mother-Child Reminiscing Scales.

Mother-child participation in conversations about past events in early childhood has an invaluable influence on child development. While previous studies have focused on the investigation of maternal styles of talking about the past, the role of maternal attitudes towards reminiscing has been overlooked. This paper presents two studies on the development and validation of two separate scales that assess maternal attitudes in mother-child conversations: the Maternal Attitudes Towards Mother-Child Reminiscing Scale (MCRS) and MCRS-Context. In Study 1, we have investigated the factor structure of the MCRS (N = 312) and MCRS-Context (N = 278) with a sample of mothers whose children aged between 3 and 7. In Study 2, we aimed to test the factor structure obtained by exploratory factor analysis (EFA) in Study 1 using confirmatory factor analysis (CFA) and we have investigated the psychometric properties of the scales with a different sample of 223 mothers. EFA and CFA results have suggested four theoretically consistent factors of the MCRS (interest, competency, satisfaction and difficulty) and a one-factor structure for the MCRS-Context (general positive attitudes in comparison to other mothers). To test construct validity, the relationships with related independent scales were investigated, indicating generally significant and theoretically expected correlations. The test/re-test, Cronbach alpha and composite reliability scores indicated acceptable internal consistency for both scales. The findings of both studies provided evidence for the validity and reliability of these scales in evaluating maternal attitudes towards mother-child conversations. It is thought that the studies presented here will provide useful insight for future studies for understanding the link between maternal cognitions and reminiscing practices in mother-child conversations and the effect of that link on child development.

Nonlinear drift-wave and energetic particle long-time behaviour in stellarators: solution of the kinetic problem

We propose a theoretical scheme for the study of the nonlinear interaction of drift-wave-like turbulence and energetic particles in stellarators. The approach is based on gyrokinetics, and features a separation of time and scales, for electromagnetic fluctuations, inspired by linear ballooning theory. Two specific moments of the gyrokinetic equation constitute the main equations of the system, which requires a full kinetic nonlinear solution. This is found iteratively, expanding in the smallness of the bounce-average radial drift frequency, and nonlinear $\boldsymbol {E}\times \boldsymbol {B}$ drift frequency, compared with the inverse time scales of the resonantly interacting energetic particles. Our analysis is therefore valid for neoclassically optimised stellators. The resummation of all iterative and perturbative nonlinear kinetic solutions is discussed in terms of Feynman diagrams. Particular emphasis is put on the role of collisionlessly undamped large-scale structures in phase space, the kinetic equivalent of zonal flows, i.e. phase-space zonal structures, and on wave-like fluctuations generated by energetic particles.

Life Satisfaction among College Students in Relation to Family and Food

Abstract: Overall life satisfaction of college students depends on numerous domains. This study analyzes two of these domains specifically, family life satisfaction and food-related satisfaction in relation to overall life satisfaction of Indian college students. Moreover, the differences in these domains among migrated and non-migrated students were analyzed. Three separate scales, namely, Satisfaction With Life Scale (SWLS), Satisfaction With Food-related Life Scale and the Family Satisfaction Scale were used to assess the relationship between the variables. Sample included 148 college going students in India, belonging to the age group of 18-25. Results suggested a positive relationship between family and overall life satisfaction of students. No significant relationship was found between food-related and overall life satisfaction. Food-related satisfaction of non-migrated students was found to be higher than migrated students. No difference was found between overall and family satisfaction among migrated and non-migrated students.