Invariant Model Research Articles

Shimmering emerging adulthood: in search of the invariant IDEA model for collectivistic countries

Emerging adulthood is the youth trajectory characterized by self-focus, identity exploration, feeling between adolescence and adulthood, instability, and experimentation. This trajectory was first identified in industrialized individualistic countries with gender equality and technological progress. To measure transition to adulthood, the Inventory of the Dimensions of Emerging Adulthood (IDEA) was created. Although emerging adulthood is considered universal, adaptations of the questionnaire across the 12 countries show different patterns, and its cross-cultural invariance has been underinvestigated. This study tests IDEA in three collectivistic countries – Armenia, China, and Russia. The sample consisted of 868 students (total male – 152, total female – 716) aged 18 to 29 years old. We tested the questionnaire separately in the three countries to check that this model fits, but we failed to prove it. After that we used a factor-analytic approach to find a common version for the three countries. We got a five-factor correlated model in accordance with the theory, but it was reduced from 31 items to 21, and three items moved to other factors. Finally, we provided measurement invariance and reached configural level. To test the narrower facets of factors we used multi-group alignment and found that variances in six parameters differ, mainly in Instability. Despite the difference in the questionnaire items, we proposed a common model for three countries that we called questionnaire IDEA-collectivistic countries (IDEA-CC).

Adaptive Prosthetic Trajectory Estimation Based on Key Points Constraints

Lower limb knee–ankle prostheses can effectively assist above-knee amputees in completing their basic daily activities. This study explored methods for estimating the joint kinematics of intelligent lower limb prostheses to better adapt them to the walking requirements of amputees. A method of estimating the knee and ankle joint trajectories under different speeds and slopes was raised. The joints of a prosthetic need to have a movement trajectory similar to that of the joints of healthy individuals, taking into account the person’s motion intentions and complying with the law of movement. In this study, a prosthetic kinematics estimation method was studied to realize continuous speed and slope adaptation through key points. The iterative Douglas–Peucker algorithm automatically found the key points of the kinematic trajectory curve, and an invariant basis function-fitting model with key points constraints was constructed. Finally, the radial basis function neural network was used to estimate the adaptive task function of the parts affected by the speed and slope, resulting in an overall kinematics estimation model. Our experiments verified the effectiveness of the proposed method, which accurately estimated the kinematic trajectory; the knee and ankle joint estimation errors were greatly reduced compared to those obtained with previous methods, facilitating further research on individual algorithms.

Topological defects and boundary states in four-dimensionaltopological insulator

Abstract We show the connection between the second Chern number and topological defects, in a (4+1)-dimensional time-reversal invariant Dirac lattice model. It is discovered that two types of topological defects, the five-dimensional (5D) and four-dimensional (4D) point defects arise from the singular points of wave functions together with the geometric meaning of the second Chern number. We demonstrated that the 5D point defects appear at the band crossing positions with a topological transition, leading to a jump of the second Chern number. The 4D point defects exist in an insulating bulk, whose topological charges can give the evaluations of the second Chern number of energy bands. Finally, we discussed the possible structures of the boundary states in light of the realization way of the 4D model. Our theory provides not only a brand-new perspective to grasp the second Chern number, but also a simple approach to derive its values without calculating any integrals.

LTI/LQE: A Physics-Based Approach for Online Estimation of Dynamic Loads in the Rotating Frame

Accurate and online load monitoring of vital components located in the rotor system is important for not only inferring usage and estimating fatigue in those components but also for developing load alleviation/limiting control schemes. In the literature, on-board models for online (i.e., real-time) estimation of rotor component loads using available in-flight aircraft fixed-frame measurements are developed using neural networks, a statistical-based approach, or a combination of both. These models are aircraft-specific, do not capture the higher harmonic dynamics of the rotor system vibratory loads, and their synthesis requires obtaining a lot of data. To remedy these issues, this paper introduces a purely physics-based approach to online estimation of rotor system loads. The proposed approach can be applied to any rotary-wing vehicle, does not rely on a large amount of data, and captures the higher harmonic dynamics of the rotor system vibratory loads. The developed model entitled LTI/LQE is synthesized using a linear time invariant (LTI) model of helicopter-coupled body-rotor-inflow dynamics and a linear quadratic estimator (LQE), that is designed to correct the LTI model state response using fixed system measurements. The estimation fidelity of the LTI/LQE model is evaluated in simulation using a high-fidelity nonlinear model of a generic helicopter for online prediction of rotor blade pitch link loads arising from vehicle maneuvers. Results obtained using the LTI/LQE model revealed an interesting finding. It was found that the N/rev (where N is the number of blades) fixed system load measurements have information that can be leveraged to make an inference about the N/rev dynamic loads in the rotating system.

THEMIS 2.0: A self-consistent model for dust extinction, emission, and polarisation

Context. Recent observational constraints in emission, extinction, and polarisation have at least partially invalidated most of the astronomical standard grain models for the diffuse interstellar medium. Moreover, laboratory measurements on interstellar silicate analogues have shown quite significant differences with the optical properties used in these standard models. Aims. To address these issues, our objective is twofold: (i) to update the optical properties of silicates and (ii) to develop The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS) to allow the calculation of polarised extinction and emission. Methods. Based on optical constants measured in the laboratory from 5 µm to 1 mm for amorphous silicates and on observational constraints in mid-IR extinction and X-ray scattering, we defined new optical constants for the THEMIS silicates. Absorption and scattering efficiencies for spheroidal grains using these properties were subsequently derived with the discrete dipole approximation. Results. These new optical properties make it possible to explain the dust emission and extinction, both total and polarised. It is noteworthy that the model is not yet pushed to its limits since it does not require the perfect alignment of all grains to explain the observations and it therefore has the potential to accommodate the highest polarisation levels inferred from extinction measurements. Moreover, the dispersion of the optical properties of the different silicates measured in the laboratory naturally explain the variations in both the total and polarised emission and extinction observed in the diffuse interstellar medium. Conclusions. A single, invariant model calibrated on one single set of observations is obsolete for explaining contemporary observations. We are proposing a completely flexible dust model based entirely on laboratory measurements that has the potential to make major advances in understanding the exact nature of interstellar grains and how they evolve as a function of their radiative and dynamic environment. Even if challenging, this is also relevant for future cosmic microwave background (CMB) missions that will aim to perform precise measurements of the CMB spectral distortions and polarisation.

Diagnosing and Rectifying Fake OOD Invariance: A Restructured Causal Approach

Invariant representation learning (IRL) encourages the prediction from invariant causal features to labels deconfounded from the environments, advancing the technical roadmap of out-of-distribution (OOD) generalization. Despite spotlights around, recent theoretical result verified that some causal features recovered by IRLs merely pretend domain-invariantly in the training environments but fail in unseen domains. The fake invariance severely endangers OOD generalization since the trustful objective can not be diagnosed and existing causal remedies are invalid to rectify. In this paper, we review a IRL family (InvRat) under the Partially and Fully Informative Invariant Feature Structural Causal Models (PIIF SCM /FIIF SCM) respectively, to certify their weaknesses in representing fake invariant features, then, unify their causal diagrams to propose ReStructured SCM (RS-SCM). RS-SCM can ideally rebuild the spurious and the fake invariant features simultaneously. Given this, we further develop an approach based on conditional mutual information with respect to RS-SCM, then rigorously rectify the spurious and fake invariant effects. It can be easily implemented by a small feature selection subnet introduced in the IRL family, which is alternatively optimized to achieve our goal. Experiments verified the superiority of our approach to fight against the fake invariant issue across a variety of OOD generalization benchmarks.

Modular invariant holomorphic observables

In modular invariant models of flavor, observables must be modular invariant. The observables discussed so far in the literature are functions of the modulus τ and its conjugate, τ¯. We point out that certain combinations of observables depend only on τ, i.e. are meromorphic, and in some cases even holomorphic functions of τ. These functions, which we dub “invariants” in this Letter, are highly constrained, renormalization group invariant, and allow us to derive many of the models' features without the need for extensive parameter scans. We illustrate the robustness of these invariants in two existing models in the literature based on modular symmetries, Γ3 and Γ5. We find that, in some cases, the invariants give rise to robust relations among physical observables that are independent of τ. Furthermore, there are instances where additional symmetries exist among the invariants. These symmetries are relevant phenomenologically and may provide a dynamical way to realize symmetries of mass matrices.

Irritability across adolescence: Examining longitudinal trajectory, stability, and associations with psychopathology and functioning at age 18

BackgroundIrritability, marked by diminished frustration tolerance, holds significant implications for youth mental health treatment. Despite prior research on irritability trajectories, understanding of individual differences during adolescence remains limited. This study examines the stability and trajectory of irritability across ages 12–18, investigating associations with psychopathology and functioning at age 18. MethodsA community sample of families with 3-year-old children (N = 518) was recruited via commercial mailing lists. Irritability was assessed at ages 12, 15, and 18 using the Affective Reactivity Index. Psychopathology at age 18 was evaluated with the Kiddie Schedule for Affective Disorders and Schizophrenia, and functioning was assessed through the UCLA Life Stress Interview. Measurement invariance analyses and latent growth curve modeling were conducted within a structural equation modeling (SEM) framework. ResultsConfigural, metric, and scalar invariance models were supported. Elevated irritability at age 12 predicted adverse outcomes at age 18, including increased psychotropic medication use, mental health treatment, suicidal ideation, self-injury, and psychiatric disorders. Importantly, these associations persisted even after accounting for corresponding variables at age 12. The trajectory of irritability during early adolescence significantly predicted heightened risks for various outcomes at age 18, including suicidal ideation, depression, anxiety, disruptive behavior disorders, and impaired interpersonal functioning. DiscussionLimitations include using only youth-reported data at age 18, limited generalizability from a mostly White, middle-class sample, and insufficient exploration of the broader developmental trajectory of irritability. Nevertheless, the findings emphasize the crucial role of irritability's trajectory in influencing various psychopathological and functional outcomes in late adolescence.

Resonant graviton-photon transitions with cosmological stochastic magnetic field

We explore the possibility of detecting resonant conversions of high frequency gravitational waves to radio-signals. We show how the graviton-photon transitions, from Gertsenshtein effect, can be resonantly amplified in a cosmological stochastic magnetic background. In particular, we found parametric resonances for both the monochromatic and scale invariant power spectrum models of magnetic field fluctuations. Our results substantially departs from those predicted in resonance-less magnetic domain-like models in a large region of magnetic and oscillation wavelength scales. Resonances can be tested by radio telescopes such as ARCADE 2 and EDGES as a probe of high frequency gravitational wave sources and new physics models for magnetogenesis. Analysis are performed with a robust perturbative approach in discrete scheme for including cosmological decoherence in graviton-photon oscillations.

Efficient learning of Scale-Adaptive Nearly Affine Invariant Networks

Recent research has demonstrated the significance of incorporating invariance into neural networks. However, existing methods require direct sampling over the entire transformation set, notably computationally taxing for large groups like the affine group. In this study, we propose a more efficient approach by addressing the invariances of the subgroups within a larger group. For tackling affine invariance, we split it into the Euclidean group E(n) and uni-axial scaling group US(n), handling invariance individually. We employ an E(n)-invariant model for E(n)-invariance and average model outputs over data augmented from a US(n) distribution for US(n)-invariance. Our method maintains a favorable computational complexity of O(N2) in 2D and O(N4) in 3D scenarios, in contrast to the O(N6) (2D) and O(N12) (3D) complexities of averaged models. Crucially, the scale range for augmentation adapts during training to avoid excessive scale invariance. This is the first time nearly exact affine invariance is incorporated into neural networks without directly sampling the entire group. Extensive experiments unequivocally confirm its superiority, achieving new state-of-the-art results in affNIST and SIM2MNIST classifications while consuming less than 15% of inference time and fewer computational resources and model parameters compared to averaged models.

“It’s too much”: Excessive smartphone use during the COVID-19 crisis, information overload, and infection self-efficacy

During the COVID-19-related lockdowns around the world, individuals received a permanent digital stream of information about the pandemic via their smartphones. We theorize that such excessive COVID-19-related smartphone use can affect information overload, i.e., the perception of being exposed to too much information about COVID-19. We also introduce the notion of infection self-efficacy, the feeling that one is able to control the likelihood of being infected. We conducted a two-wave panel survey among an adult sample in Austria (NT2 = 416) during the first lockdown in 2020. Findings of a metric measurement invariant structural equation model revealed that excessive smartphone use predicts information overload over time. Moreover, information overload resulted in lower infection self-efficacy after one month. Reciprocal effects showed that information overload at T1 also increased excessive smartphone use at T2, suggesting a spiral. However, infection self-efficacy did not predict information overload and excessive smartphone use over time. Our findings contribute to the literature on information processing mechanisms by providing clear evidence for the reciprocal relationship between excessive smartphone use and information overload over time. The findings are also important for health scholarship because they explain individuals’ perceptions about whether they are able to protect themselves from COVID-19.

Griffiths-Type Theorems for Short-Range Spin Glass Models

We establish relations between different characterizations of order in spin glass models. We first prove that the broadening of the replica overlap distribution indicated by a nonzero standard deviation of the replica overlap R1,2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^{1,2}$$\\end{document} implies the non-differentiability of the two-replica free energy with respect to the replica coupling parameter λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda $$\\end{document}. In Z2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathbb {Z}}_2$$\\end{document} invariant models such as the standard Edwards–Anderson model, the non-differentiability is equivalent to the spin glass order characterized by a nonzero Edwards–Anderson order parameter. This generalization of Griffiths’ theorem is proved for any short-range spin glass models with classical bounded spins. We also prove that the non-differentiability of the two-replica free energy mentioned above implies replica symmetry breaking in the literal sense, i.e., a spontaneous breakdown of the permutation symmetry in the model with three replicas. This is a general result that applies to a large class of random spin models, including long-range models such as the Sherrington-Kirkpatrick model and the random energy model. There is a 25-minute video that explains the main results of the present work:https://youtu.be/BF3hJiY1xvI

Quark-lepton mass relations from modular flavor symmetry

The so-called Golden Mass Relation provides a testable correlation between charged-lepton and down-type quark masses, that arises in certain flavor models that do not rely on Grand Unification. Such models typically involve broken family symmetries. In this work, we demonstrate that realistic fermion mass relations can emerge naturally in modular invariant models, without relying on ad hoc flavon alignments. We provide a model-independent derivation of a class of mass relations that are experimentally testable. These relations are determined by both the Clebsch-Gordan coefficients of the specific finite modular group and the expansion coefficients of its modular forms, thus offering potential probes of modular invariant models. As a detailed example, we present a set of viable mass relations based on the Γ4 ≅ S4 symmetry, which have calculable deviations from the usual Golden Mass Relation.

SINS/GNSS Integrated Navigation Based on Invariant Error Models in Inertial Frame

SINS/GNSS Integrated Navigation Based on Invariant Error Models in Inertial Frame

Family functioning in students of health sciences in four Latin American countries: a study of the structure and factorial invariance of the FACES III scale. A cross-sectional study.

Psychometric studies of the FACES III scale in Spanish-speaking countries show a lack of agreement on the factorial structure of the scale. In addition, most of the studies have only performed exploratory analyses of its factorial structure. The objective of the present study was to confirm the structure and factorial invariance of the FACES III scale in nursing and obstetric students from Chile, Colombia, Peru, and Mexico. A total of 3303 students from the four countries participated in this study (Colombia = 1559, Chile = 1224, Peru = 215, Mexico = 305). The results of the study showed that the Bi-factor model presents the best-fit indexes to the data from Colombia, Chile, and Mexico, but not from Peru. In addition, it was found that this model showed evidence of being strictly invariant among the three countries in the sequence of the invariance models proposed: metric invariance (ΔRMSEA = .000), scalar (ΔRMSEA = .008), and strict (ΔRMSEA = .008). The bi-factor model also showed adequate reliability indexes in the three countries. It is concluded that the FACES III scale shows adequate psychometric performance under a bi-factor model in nursing and obstetric students from Colombia, Chile, and Mexico. The lack of fit of the model in Peru could be associated with the small sample size.

The justification of methodological approach of machine-building enterprises efficiency assessment

The article argues for the relevance of researching contemporary methods and tools for assessing the effectiveness of industrial enterprises, particularly in the context of the adverse impact of the country's economy. Specifically, an analysis of the profitability levels of industrial enterprises, also in the machinery industry, was conducted, revealing low-efficiency indicators. Machine-building enterprises are a crucial pillar of the economy, and their development contributes to the country's and society's overall economic progress and the acceleration of scientific and technological advancements. The author proposed a methodological approach to evaluating the efficiency of enterprise operations, reflecting the processes, methods, and planned results of its application for assessing the efficiency of industrial enterprises. To simplify the calculation process and the number of indicators, an invariant model for assessing the efficiency of enterprise operations was suggested. The "centers of gravity" method was used to construct the suggested model. This involved forming an array of analyzed data, standardizing the output data, and calculating the matrix of Euclidean distances for each group of enterprise development indicators. The representative indicators for each group were chosen based on the minimum value of the sum of Euclidean distances. The obtained results were economically interpreted. The invariant model was also based on calculating four representative indicators by efficiency groups. According to the justified model, the representative for the group of indicators of the efficiency of internal business processes and the scientific-technical production level was the profitability of production. The effectiveness of the customer component was reflected in the accounts receivable turnover. Workforce efficiency reflects labor productivity, and the efficiency of the financial component was assessed by calculating the profitability of equity. Keywords: enterprise efficiency, enterprise development, methodical approach to assessing enterprise efficiency, intuitive model.

Gravitational waves from phase transitions in scale invariant models

We investigate the properties of the gravitational waves (GW) generated during a strongly first order electroweak phase transition (EWPT) in models with the classical scale invariance (CSI). Here, we distinguish two parameter space regions that correspond to the cases of (1) light dilaton and (2) purely radiative Higgs mass (PRHM). In the CSI models, the dilaton mass, or the Higgs mass in the PRHM case, in addition to some triple scalar couplings are fully triggered by the radiative corrections (RCs). In order to probe the RC effects on the EWPT strength and on the GW spectrum, we extend the standard model by a real singlet to assist the electroweak symmetry breaking and an additional scalar field Q with multiplicity NQ and mass mQ. After imposing all theoretical and experimental constraints, we show that a strongly first order EWPT with detectable GW spectra can be realized for the two cases of light dilaton and PRHM. We also show the corresponding values of the relative enhancement of the cross section for the di-Higgs production process, which is related to the triple Higgs boson coupling. We obtain the region in which the GW spectrum can be observed by different future experiments such as LISA and DECIGO. We also show that the scenarios (1) and (2) can be discriminated by future GW observations and measurements of the di-Higgs productions at future colliders.

Learning to Generalize towards Unseen Domains via a Content-Aware Style Invariant Model for Disease Detection from Chest X-rays.

Performance degradation due to distribution discrepancy is a longstanding challenge in intelligent imaging, particularly for chest X-rays (CXRs). Recent studies have demonstrated that CNNs are biased toward styles (e.g., uninformative textures) rather than content (e.g., shape), in stark contrast to the human vision system. Radiologists tend to learn visual cues from CXRs and thus perform well across multiple domains. Motivated by this, we employ the novel on-the-fly style randomization modules at both image (SRM-IL) and feature (SRM-FL) levels to create rich style perturbed features while keeping the content intact for robust cross-domain performance. Previous methods simulate unseen domains by constructing new styles via interpolation or swapping styles from existing data, limiting them to available source domains during training. However, SRM-IL samples the style statistics from the possible value range of a CXR image instead of the training data to achieve more diversified augmentations. Moreover, we utilize pixel-wise learnable parameters in the SRM-FL compared to pre-defined channel-wise mean and standard deviations as style embeddings for capturing more representative style features. Additionally, we leverage consistency regularizations on global semantic features and predictive distributions from with and without style-perturbed versions of the same CXR to tweak the model's sensitivity toward content markers for accurate predictions. Our proposed method, trained on CheXpert and MIMIC-CXR datasets, achieves 77.32&±0.35, 88.38&±0.19, 82.63&±0.13 AUCs(%) on the unseen domain test datasets, i.e., BRAX, VinDr-CXR, and NIH chest X-ray14, respectively, compared to 75.56&±0.80, 87.57&±0.46, 82.07&±0.19 from state-of-the-art models on five-fold cross-validation with statistically significant results in thoracic disease classification.

Gender and Age Invariance of the Global Belief in a Just World Scale

Abstract: Belief in a Just World (BJW) underscores the psychological inclination of individuals to view the world as just, where outcomes typically correspond with one’s actions and behaviors. Despite the widespread application of the Global Belief in a Just World Scale (GBJWS) in the social sciences as a measure for the BJW construct, there remains an insufficient exploration of its measurement invariance across age and gender, especially among Chinese working adults. This study aims to fill this gap by using multigroup confirmatory factor analysis (MGCFA) for gender invariance and local structural equation modeling for age invariance assessment. Statistics analyses with 2,128 participants confirmed configural, metric, and scalar invariance for gender, with latent mean comparisons revealing no significant gender differences in BJW. However, age invariance did not reach scalar invariance, suggesting caution in utilizing the one-factor structure of the GBJWS for age-related research. This investigation offers a deeper understanding of the GBJWS’s validity and responds to the pressing call for research on the scale’s applicability across diverse demographic contexts.

Communicative and linguistic translation tools for academic adaptation of educational migrants in crisis conditions

The article is devoted to solving the urgent scientific and methodological problem of adaptation of migrants to living conditions in a new socio-cultural space, which is caused by the current crisis conditions that have developed in Europe and the world and pose a threat not only to the health, but also to the lives of millions of people. A significant part of migration flows is made up of students who master their future profession at foreign universities, in particular in Polish higher education institutions. Modern approaches to determining the structure of communicative competence of an educational migrant, types of adaptation, and tasks of language training are analyzed. The level of proficiency in the language of instruction is the main factor of the success of the educational process. It has been found that todayʼs conditions require clarification of the composition of participants of the academic adaptation of foreign students. The authors believe that at the initial stage of the adaptation process, the role of translators increases significantly. The requirements for the structure of communicative competence of an educational migrant and the professional and communicative competence of a translator have been clarified. A list of actual communicative situations in the domestic, educational, professional, administrative, socio-cultural spheres of communication is determined, examples of lexical units that will ensure the implementation of communicative tasks are provided. For the formation of professional translation competence, the development of communicative and linguistic tools is proposed: the creation of an educational complex consisting of a syllabus of an elective discipline, a manual, the theoretical and practical sections of which will provide linguistic and methodical guidelines for the formation of interpretation and translation skills in situations of adaptation of educational migrants. It is also proposed to add a complex dictionary of a new type to the toolkit, which will combine the characteristics of different types of lexicographic works and perform the task of interpreting and explaining current lexical units. The developed linguomethodical principles for the creation of an educational complex for the formation of professional and communicative competence of translators can become an invariant model for the creation of variable methodical materials for teaching translation from/into other languages.