Scaling Assumptions Research Articles

Swedish Version of the System Usability Scale: Translation, Adaption, and Psychometric Evaluation.

The Swedish health care system is undergoing a transformation. eHealth technologies are increasingly being used. The System Usability Scale is a widely used tool, offering a standardized and reliable measure for assessing the usability of digital health solutions. However, despite the existence of several translations of the System Usability Scale into Swedish, none have undergone psychometric validation. This highlights the urgent need for a validated and standardized Swedish version of the System Usability Scale to ensure accurate and reliable usability evaluations. The aim of the study was to translate and psychometrically evaluate a Swedish version of the System Usability Scale. The study utilized a 2-phase design. The first phase translated the System Usability Scale into Swedish and the second phase tested the scale's psychometric properties. A total of 62 participants generated a total of 82 measurements. Descriptive statistics were used to visualize participants' characteristics. The psychometric evaluation consisted of data quality, scaling assumptions, and acceptability. Construct validity was evaluated by convergent validity, and reliability was evaluated by internal consistency. The Swedish version of the System Usability Scale demonstrated high conformity with the original version. The scale showed high internal consistency with a Cronbach α of .852 and corrected item-total correlations ranging from 0.454 to 0.731. The construct validity was supported by a significant positive correlation between the System Usability Scale and domain 5 of the eHealth Literacy Questionnaire (P=.001). The Swedish version of the System Usability Scale demonstrated satisfactory psychometric properties. It can be recommended for use in a Swedish context. The positive correlation with domain 5 of the eHealth Literacy Questionnaire further supports the construct validity of the Swedish version of the System Usability Scale, affirming its suitability for evaluating digital health solutions. Additional tests of the Swedish version of the System Usability Scale, for example, in the evaluation of more complex eHealth technology, would further validate the scale.

Corrections to scaling in the 2D φ4 model:Monte Carlo results and some related problems

Abstract Monte Carlo (MC) simulations have been performed to refine the estimation of the correction-to-scaling exponent ω in the 2D φ4 model, which belongs to one of the most fundamental universality classes. If corrections have the form ∝L-ω, then we find ω=1.546(30) and ω=1.509(14) as the best estimates. These are obtained from the finite-size scaling of the susceptibility data in the range of linear lattice sizes L∈[128,2048] at the critical value of the Binder cumulant and from the scaling of the corresponding pseudocritical couplings within L∈[64,2048]. These values agree with several other MC estimates at the assumption of the power-law corrections and are comparable with the known results of the ε-expansion. In addition, we have tested the consistency with the scaling corrections of the form ∝L-4/3, ∝L-4/3ln L and ∝L-4/3/ln L, which might be expected from some considerations of the renormalization group and Coulomb gas model. The latter option is consistent with our MC data. Our MC results served as a basis for a critical reconsideration of some earlier theoretical conjectures and scaling assumptions. In particular, we have corrected and refined our previous analysis by grouping Feynman diagrams. The renewed analysis gives ω≈4-d-2η as some approximation for spatial dimensions d<4, or ω≈1.5 in two dimensions.

Efficiency of Primary Health Services in the Greek Public Sector: Evidence from Bootstrapped DEA/FDH Estimators.

Strengthening primary healthcare (PHC) is vital for enhancing efficiency and improving access, clinical outcomes, and population well-being. The World Health Organization emphasizes the role of effective PHC in reducing healthcare costs and boosting productivity. With growing healthcare demands and limited resources, efficient management is critical. Background/Objectives: Building on this point, this study aimed to evaluate the efficiency of PHC units across Greece, focusing on Health Centers (HCs) and Local Health Units (ToMYs). The objective was to assess their efficiency levels and identify factors contributing to observed inefficiencies. This study explores a novel research area by being the first to assess the efficiency of restructured primary healthcare facilities in Greece, utilizing 2019 data-the first year operational data became available for the newly established ToMY facilities following recent healthcare reforms. Methods: We applied a comprehensive suite of non-parametric methods, including Data Envelopment Analysis (DEA) under variable, constant, increasing, and decreasing returns to scale (VRS, CRS, IRS/NDRS, DRS/NIRS) assumptions, along with the Free Disposal Hull (FDH) model, all oriented toward output maximization. Efficiency scores were refined using bootstrapping to calculate 95% confidence intervals, and efficient units were ranked via the super-efficiency model. Outliers were identified and removed through the data cloud algorithm. For the first time at this scale, the final sample included the vast majority of PHC facilities in Greece-234 Health Centers and 94 Local Health Units-with inputs categorized into three human resource types: medical, nursing/paramedical, and administrative/other staff. Outputs encompassed scheduled visits, emergency visits, and pharmaceutical prescription visits. This diverse and comprehensive application of DEA methods represents a novel approach to evaluating PHC efficiency in Greece, with potential relevance to broader healthcare contexts. Results: The analysis revealed significant inefficiencies and differences in technical efficiency between HCs and ToMYs. HCs could nearly double their outputs (VRS score: 1.92), while ToMYs could increase theirs by 58% (VRS score: 1.58). Scale efficiency scores were closer, with HCs slightly more aligned with their optimal scale (1.17 vs. 1.20 for ToMYs). Conclusions: There is significant potential to improve efficiency in PHC, with variations depending on unit characteristics and regional differences. This evaluation provides a foundation for policymakers to identify areas for improvement and enhance the overall performance of healthcare services in Greece.

Applying Fractal Theory: Solving the Geometric Challenge of Price Change and Scaling in Economics

<i>Background</i>: Price changes in economics present significant geometric challenges due to sharp discontinuities, which cannot be efficiently described by continuous processes like Brownian motion. Traditional models often rely on linear assumptions, yet financial data frequently exhibit irregular, complex patterns. Fractal theory, a mathematical framework, offers a more accurate way to describe these fluctuations by revealing the underlying self-similar structures in price changes and scaling phenomena. This study explores the use of fractal geometry to gain deeper insights into market behavior. <i>Objective</i>: The objective is to demonstrate that an alternative model, constructed based on geometric scaling assumptions, offers a more accurate description of price changes in competitive markets. <i>Method</i>: The study combined the scaling principle from fractal geometry with a stable Levy model to formulate an integrated model. The logarithmic transformation of the model was applied over successive price changes to observe the behavior of market prices. <i>Result</i>: The scaling principle asserts that no specific time interval (such as a day or a week) holds inherent significance in competitive markets. Instead, these time features are compensated or arbitrated away, supporting the idea that market behavior is self-similar across different time scales. <i>Conclusion</i>: The scaling principle provides a more reliable framework for modeling price changes and is recommended for consideration in economic analyses.

Characterization of production sets through individual returns-to-scale: A non parametric specification and an illustration with the U.S industries

This paper proposes to estimate the returns-to-scale of production sets by considering the individual return of each observation, considered as a decision-making unit through the notion of Λ-returns to scale assumption. Along this line, the global technology is then constructed as the intersection of all the individual technologies. Hence, an axiomatic foundation is proposed to present the notion of Λ-returns to scale. This new characterization of the returns-to-scale encompasses the definition of α-returns to scale, as a special case as well as the standard non-increasing and non-decreasing returns-to-scale models. A non-parametric procedure based on the goodness of fit approach is proposed to assess these individual returns-to-scale. To illustrate this notion of Λ-returns to scale assumption, an empirical illustration is provided based on a dataset involving 63 industries constituting the whole American economy over the period 1987-2018.

Reduced energies for thin ferromagnetic films with perpendicular anisotropy

We derive four reduced two-dimensional models that describe, at different spatial scales, the micromagnetics of ultrathin ferromagnetic materials of finite spatial extent featuring perpendicular magnetic anisotropy and interfacial Dzyaloshinskii–Moriya interaction. Starting with a microscopic model that regularizes the stray field near the material’s lateral edges, we carry out an asymptotic analysis of the energy by means of [Formula: see text]-convergence. Depending on the scaling assumptions on the size of the material domain versus the strength of dipolar interaction, we obtain a hierarchy of the limit energies that exhibit progressively stronger stray field effects of the material edges. These limit energies feature, respectively, a renormalization of the out-of-plane anisotropy, an additional local boundary penalty term forcing out-of-plane alignment of the magnetization at the edge, a pinned magnetization at the edge, and, finally, a pinned magnetization and an additional field-like term that blows up at the edge, as the sample’s lateral size is increased. The pinning of the magnetization at the edge restores the topological protection and enables the existence of magnetic skyrmions in bounded samples.

How emotion is experienced and expressed in multiple cultures: a large-scale experiment across North America, Europe, and Japan.

Core to understanding emotion are subjective experiences and their expression in facial behavior. Past studies have largely focused on six emotions and prototypical facial poses, reflecting limitations in scale and narrow assumptions about the variety of emotions and their patterns of expression. We examine 45,231 facial reactions to 2,185 evocative videos, largely in North America, Europe, and Japan, collecting participants' self-reported experiences in English or Japanese and manual and automated annotations of facial movement. Guided by Semantic Space Theory, we uncover 21 dimensions of emotion in the self-reported experiences of participants in Japan, the United States, and Western Europe, and considerable cross-cultural similarities in experience. Facial expressions predict at least 12 dimensions of experience, despite massive individual differences in experience. We find considerable cross-cultural convergence in the facial actions involved in the expression of emotion, and culture-specific display tendencies-many facial movements differ in intensity in Japan compared to the U.S./Canada and Europe but represent similar experiences. These results quantitatively detail that people in dramatically different cultures experience and express emotion in a high-dimensional, categorical, and similar but complex fashion.

An improved equilibrium efficient frontier data envelopment analysis approach for evaluating decision-making units with fixed-sum outputs

In recent years, significant development has been made in efficiency evaluation for Decision-Making Units (DMUs) with fixed-sum outputs. The Generalized Equilibrium Efficient Frontier Data Envelopment Analysis (GEEFDEA) approach introduced by Yang et al. (2015) is one of the most representative methods. In the GEEFDEA approach, all DMUs are adjusted to become efficient under the same set of weights, indicating that the Equilibrium Efficient Frontier (EEF) constructed consists of only one hyperplane. However, in practical scenarios under the Variable Return to Scale (VRS) assumption, the production frontier always consists of multiple hyperplanes, presenting a more complex shape. To fill this research gap, we propose an improved Equilibrium Efficient Frontier Data Envelopment Analysis approach. Our approach allows DMUs to have different weights for inputs, variable-sum outputs, and fixed-sum outputs, resulting in an EEF with multiple hyperplanes. It is noted that our new approach uses a non-linear model to obtain the EEF. We show that the model can be linearized in the case of a single fixed-sum output. In situations involving multiple fixed-sum outputs, we propose an algorithm based on the Expectation Maximization (EM) mechanism to solve the model to obtain an EEF. Finally, we illustrate the advantages of our new approach through a numerical example and a case study in the global motor vehicle industry.

The Nuances of Plant Disease Severity Estimation Using Quantitative Ordinal Scales-Lessons Learned over Four Decades.

We revisit the foundations of the Horsfall-Barratt (HB) scale, a widely cited and applied plant disease visual assessment tool introduced in 1945, a full 37 years prior to T. T. Hebert's 1982 critique that raised concerns regarding the scale's rationale, particularly its reliance on the Weber-Fechner law and visual perception assumptions. Although use of the HB scale and similar ordinal scales persists, comprehensive studies have revealed that direct visual estimation using percentage scales often proves more accurate and reliable. Challenges remain, such as biases due to estimator subjectivity and the potential for misclassification. The logarithmic assumptions of the HB scale have been debunked, and the importance of choosing appropriate interval sizes and numbers of classes in developing ordinal scales is emphasized. Analyzing ordinal scale data appropriately is crucial, and recent advances offer promising methods that reduce type II error rates. The closely related disease severity index is noted to have its shortcomings and potential for misuse. The letter underscores the need for continuous refinement and critical evaluation of disease assessment methodologies.

Response to “Discussion of ‘How Sensitive Are Bank Market Values to Regulatory Adjustments of Capital?’”

We provide a detailed response to Ines Simac's ( 2024 ) discussion of our study on the sensitivity of bank market values to regulatory adjustments (RAs) of capital. Initially, we investigated the relevance of these adjustments, motivated by ongoing changes in the definition of bank capital aimed at ensuring financial stability. Our research utilized log-log models to address the challenges of alternative methodologies that may not effectively capture the value relevance of bank capital and RAs. Our results underscore the stability and predictability of coefficients that measure value relevance. We further explore the valuation perspective, distinguishing between a “valuation” model for a theory of the relation between market and accounting values and a statistical model that estimates the sensitivity of market values to changes in accounting variables. We advocate for the use of log-log models due to their robustness in estimating response coefficients as elasticities. This approach minimizes issues related to scale and distribution assumptions inherent in additive-linear models. We also address minor points raised in the discussion, including the coefficient values of goodwill and Tier 2 capital. Our findings contribute to a nuanced understanding of how regulatory adjustments influence bank valuations, offering implications for both academic research and regulatory policy.

Toward mapping turbulence in the intra-cluster medium

Context. Future X-ray observatories with high spectral resolution and imaging capabilities will enable measurements and mappings of emission line shifts in the intracluster medium (ICM). Such direct measurements can serve as unique probes of turbulent motions in the ICM. Determining the level and scales of turbulence will improve our understanding of the galaxy cluster dynamical evolution and assembly, together with a more precise evaluation of the non thermal support pressure budget. This will allow for more accurate constraints to be placed on the masses of galaxy clusters, among other potential benefits. Aims. In this view, we implemented the methods presented in the previous instalments of our work to characterising the turbulence in the intra-cluster medium in a feasibility study with the X-ray Integral Field Unit (X-IFU) on board the future European X-ray observatory, Athena. Methods. From idealized mock observations of a toy model cluster, we reconstructed the second-order structure function built with the observed velocity field to constrain the turbulence. We carefully accounted for the various sources of errors to derive the most realistic and comprehensive error budget within the limits of our approach. With prior assumptions on the dissipation scale and power spectrum slope, we constrained the parameters of the turbulent power spectrum model through the use of Markov chain Monte Carlo (MCMC) sampling. Results. With a very long exposure time, a favourable configuration, and a prior assumption of the dissipation scale, we were able to retrieve the injection scale, velocity dispersion, and power spectrum slope, with 1σ uncertainties for better than ∼15% of the input values. We demonstrated the efficiency of our carefully set framework to constrain the turbulence in the ICM from high-resolution X-ray spectroscopic observations, paving the way for more in-depth investigation of the optimal required observing strategy within a more restrictive observational setup with the future Athena/X-IFU instrument.

A Variational Perspective on Auxetic Metamaterials of Checkerboard-Type

The main result of this work is a homogenization theorem via variational convergence for elastic materials with stiff checkerboard-type heterogeneities under the assumptions of physical growth and non-self-interpenetration. While the obtained energy estimates are rather standard, determining the effective deformation behavior, or in other words, characterizing the weak Sobolev limits of deformation maps whose gradients are locally close to rotations on the stiff components, is the challenging part. To this end, we establish an asymptotic rigidity result, showing that, under suitable scaling assumptions, the attainable macroscopic deformations are affine conformal contractions. This identifies the composite as a mechanical metamaterial with a negative Poisson’s ratio. Our proof strategy is to tackle first an idealized model with full rigidity on the stiff tiles to acquire insight into the mechanics of the model and then transfer the findings and methodology to the model with diverging elastic constants. The latter requires, in particular, a new quantitative geometric rigidity estimate for non-connected squares touching each other at their vertices and a tailored Poincaré type inequality for checkerboard structures.

Input allocative efficiencies for operation and maintenance of rural piped water supply systems in highland areas of Vietnam

Strengthening the functioning of existing rural piped water supply systems is a critical strategy for ensuring household water security, particularly in water-scarce contexts. Improving operation and maintenance (O&M) of the systems is an important area of focus, commonly plagued by poor reliability and functionality over time. From an economic perspective, there is an opportunity to optimise O&M input efficiencies as a foundation for improved management. This paper presented challenges and opportunities to optimise O&M input efficiencies based on an analysis of water supply systems in Vietnam’s highland areas characterised by mountainous terrain and water scarcity. The analysis focused on state-based agencies for O&M given their mandate for restoring the inefficient systems and identified input norms for guidance on how to optimise O&M activities. We applied an input-oriented data envelopment analysis (DEA) model under constant returns to scale assumption to estimate technical, economic and allocative efficiencies. The results identified efficiency levels of 90%, 30% and 33% respectively. The study suggests a 10% reduction in general input amounts and identified efficient input target values reveal potential reduction rates for technical labour (12%), electricity (12%), as well as the technical and economic norms of technical labour (0.86 person- day∙(100 m3)–1 water sold) and electricity (0.53 kWh∙m–3 water sold). The policy implications for O&M state-based agencies include the adoption of input-based contracting mechanisms, while the government is encouraged to approve water tariffs and provide compensation based on input items to promote water service supply as a public good in water- scarce and challenging areas.

Assessing Degree of Overall Prospect for Merger and Acquisition of Managed Funds: A Relative Performance Perspective

The objective of this research is to analyze the merger and acquisition potential of managed funds as distinct endeavors and evaluate their overall prospects separately. Initially, the pre-merger performance is evaluated employing data envelopment analysis (DEA) under the variable returns to scale assumption. Merged fund performance is evaluated similarly after augmenting the sample with the merged fund. A fund pair is considered a merger prospect when both demonstrate the potential to enhance DEA-efficiency based rankings. Similarly, prospective acquisition targets are identified, albeit meeting different criteria. Improvement in rankings is categorized as high, medium, or low on an ordinal scale. The overall merger prospect of a given fund is determined by a weighted sum of the number of its prospective merger candidates and the frequency of the fund in question enhance their performance at the high, medium, and low level. Overall prospects serve as indicators of a fund’s potential to merge and acquire within the industry. Studies generally compute efficiency gain focusing on one merger. We propose a novel method to aggregate efficiency gain. This approach is new to the literature. In an investigation of a sample of Australian superannuation funds with 2021 annual cross-sectional data reveals that, on average, industry funds exhibit more merger and acquisition prospects within their own category compared to retail, corporate, and public sector funds. Notably, corporate funds show no such prospects. These findings have important policy implications.

Level of technical efficiency and associated factors among health centers in East Gojjam Zone, Northwest Ethiopia: an application of the data envelopment analysis

BackgroundBesides the scarcity of resources, inefficient utilization of available health service resources has been the bottleneck to deliver quality health services in Ethiopia. However, Information regarding the efficiency of health service providers is limited in the country. Health service managers and policy makers must be well informed about the efficiency of health service providers and ways of using limited resources efficiently to make evidence-based decisions. This study aimed to assess the level of technical efficiency and associated factors among health centers in East Gojjam Zone, Northwest Ethiopia.MethodsA facility-based cross-sectional study was conducted among 27 randomly selected health centers in East Gojjam zone, Northwest Ethiopia, from October 30, 2022, to April 30, 2023. Using an interviewer-administered questionnaire and document review checklist, health centers’ data was collected and entered to Epi-Data version 4.6. The data was exported to Microsoft office excel and Stata version 14 for analysis. A two-stage output-oriented data envelopment analysis with a variable return to scale assumption was employed to determine the level of technical efficiencies. Finally, the tobit regression model was applied to identify the associated factors at 5% level of significance.ResultsIn this study, 59.3% of the health centers were technically efficient. The mean technical efficiency score of the health centers was 0.899 ± 0.156. Inefficient health centers could provide more 22, 433 outpatient visits, 1,351 family planning visits, 155 referral services, 206 skilled deliveries and 385 fully vaccinations of children if they were technically efficient as their peer health centers for the same year. From the tobit regression, the catchment population and number of administrative staffs were statistically significant determinants of the technical efficiency of health centers.ConclusionsThe mean technical efficiency of the health centers in East Gojjam zone, Northwest Ethiopia was high. However, nearly half of the health centers were technically inefficient, which indicates the exitance of a space for further improvements in the productivity of these health centers. Employing excess number administrative staffs (above the optimal level) should be discouraged and selecting appropriate sites where the health centers to be constructed (to have large catchment population coverage) could improve the productivity of health centers.

Optimization of business strategy in improving the efficiency of business capital use

Indonesia is the fourth largest coffee-producing country in the world after Brazil, Vietnam, and Colombia (Richardson et al., 2023). Seeing this opportunity is widely used by business people in making coffee shops (Fahmi & Savira, 2023). This study aims to see the level of efficiency produced by coffee shops with data envelopment analysis (DEA) techniques. This analysis uses input variables, namely labor costs, raw material costs, overall capital, and the amount of labor, and output variables, namely gross profit, and net profit. In DEA using variable return scale (VRS) assumptions where the addition of inputs is not necessarily offset by the output. The sample used was 67 coffee shops in Soloraya. The results of the analysis show that 22 coffee shops have experienced a 100 percent efficiency level while 45 coffee shops have not experienced a 100 percent efficiency level, meaning that those that have not reached 100 percent need improvement in the use of inputs and improved output targets and also benchmarking to make adjustments to their business activities. Managers find it easier to make decisions about whether the business will be saved or increased targets so DEA techniques are more suitable for business people to use in making a decision.

Efficiency of Mutual Funds and Portfolio Performance Measurement: A Case of Selected Mutual Funds in Tanzania

This study examines the current efficiency trends in the Tanzanian mutual fund industry over a five-year span (2018-2022), focusing on six specific funds: Umoja Fund, WekezaMaisha, Watoto Fund, Jikimu Fund, Liquid Fund, and Bond Fund. Employing a non-parametric approach, specifically Data Envelopment Analysis (DEA), the research collects secondary data from diverse sources, including newspapers, journals, books, periodicals, and the websites of UTT and the Bank of Tanzania (BOT). Monthly Net Asset Values (NAVs) of the selected mutual funds are scrutinized from each scheme's inception. Motivated by the limited understanding of mutual fund efficiency in Tanzania despite reported successes in increased asset values, profitability, and investor numbers, the study reveals distinctive performances under Constant Returns to Scale (CRS) and Variable Returns to Scale (VRS) assumptions. Under VRS, all mutual funds consistently achieve nearly 100% efficiency, signifying optimal operational scales. However, under CRS, efficiency scores fluctuate over time, underscoring the importance of mutual funds' adaptability for enhanced efficiency. Furthermore, the research suggests that mutual fund size significantly influences efficiency and potential scale economies. Smaller mutual funds demonstrate superior resource utilization efficiency, attributed to their focused investment approach. The analysis of inputs and output slacks provides insights into efficiency and resource utilization, identifying areas of optimal resource management and highlighting opportunities for improvement. The findings offer valuable insights into mutual fund efficiency under different scale assumptions, emphasizing the importance of scale flexibility and efficient resource management for superior performance. Implications suggest avenues for further research to explore external factors, efficiency fluctuations, portfolio management practices, and longitudinal trends within the mutual fund industry.

No evidence for fractal scaling in canopy surfaces across a diverse range of forest types

AbstractCanopy structural complexity is a key emergent property of forest ecosystems that directly relates to their ability to store carbon, cycle water and nutrients, and provide habitat for biodiversity. However, we lack a general framework for quantifying the structural complexity of forest canopies, and it remains to be seen if there are simple rules that explain the huge variation in canopy structure that we observe across the world's forests.A leading candidate for characterizing differences in structural complexity among forest ecosystems are fractal scaling laws, or measures of statistical self‐similarity. If forest canopies were fractal in nature, their structural attributes could be distilled into a single coefficient—their fractal dimension—which could then be used to directly compare structural differences within and across biomes.To test this idea, we used airborne laser scanning (ALS) data acquired across nine landscapes in Australia that span a huge environmental gradient and include everything from dry shrublands, tropical savannas, dense rainforests, to 90 m tall Mountain Ash forests. Using the ALS data, we built high‐resolution 3D canopy height models of each landscape so that we could quantify how closely they followed fractal scaling laws, based on a comprehensive set of fractal dimension estimators.Across all ecosystem types, fractal scaling assumptions were consistently violated, with clear and systematic differences between real‐world forest canopies and simulated fractal surfaces. However, deviations from fractality did vary predictably among sites, with forests in less arid environments, dominated by tall trees with large crowns, exhibiting a higher degree of self‐similarity across scales.Synthesis: Our study conclusively shows that canopy surfaces are not fractal beyond the scale of individual tree crowns. Nevertheless, we still observed ecologically meaningful and generalisable patterns in forest structure across scales, which closely reflect biophysical and physiological constraints on tree size and architecture. These patterns point the way towards a more general framework for characterizing ecological complexity.

Generation of Artificial ULF/ELF Electromagnetic Emission in the Ionosphere by Horizontal Ground‐Based Current System

AbstractThe feasibility of the detection of electromagnetic response in the upper ionosphere to ground large‐scale ultra‐low‐frequency (ULF) and extremely‐low‐frequency (ELF) transmitters by low‐Earth‐orbit (LEO) satellites is considered. As an example of such transmitters, we consider the ZEVS 82 Hz transmitter, FENICS installation driven by 0.5–150 Hz generator, and industrial 50 Hz unbalanced power transmission lines. We numerically model the ULF/ELF wave energy leakage into the upper ionosphere from an oscillating grounded linear power line of a finite length suspended above a ground with a finite resistivity. The numerical scheme is based on the theoretical formalism developed to describe the excitation of an electromagnetic field by a horizontal grounded dipole. A realistic altitudinal profile of the plasma parameters has been reconstructed with the use of the IRI ionospheric model. For the ZEVS transmitter powered by 200 A current the modeled amplitudes of electromagnetic response can reach in the upper nightside ionosphere up to 60 µV/m and 6 pT. The assumption of an infinite source scale overestimates the ionospheric response by a factor of ∼7 as compared with realistic scale 60 km of the ZEVS transmitter. Unbalanced 50 Hz current of 10 A in large‐scale (>100 km) power transmission lines can produce the electric response in the upper ionosphere that is sufficient to be detected by electric sensors at LEO satellite. The stimulation of artificial Pc1 pulsations (0.5 Hz) with amplitudes ∼1 pT and ∼10 µV/m by large‐scale (>100 km) power lines is possible with driving current >100 A. The use of decommissioned power lines can be a cheap and efficient tool to stimulate Pc1 pulsations in the ionosphere.

Addressing erroneous scale assumptions in microbe and gene set enrichment analysis.

By applying Differential Set Analysis (DSA) to sequence count data, researchers can determine whether groups of microbes or genes are differentially enriched. Yet sequence count data suffer from a scale limitation: these data lack information about the scale (i.e., size) of the biological system under study, leading some authors to call these data compositional (i.e., proportional). In this article, we show that commonly used DSA methods that rely on normalization make strong, implicit assumptions about the unmeasured system scale. We show that even small errors in these scale assumptions can lead to positive predictive values as low as 9%. To address this problem, we take three novel approaches. First, we introduce a sensitivity analysis framework to identify when modeling results are robust to such errors and when they are suspect. Unlike standard benchmarking studies, this framework does not require ground-truth knowledge and can therefore be applied to both simulated and real data. Second, we introduce a statistical test that provably controls Type-I error at a nominal rate despite errors in scale assumptions. Finally, we discuss how the impact of scale limitations depends on a researcher's scientific goals and provide tools that researchers can use to evaluate whether their goals are at risk from erroneous scale assumptions. Overall, the goal of this article is to catalyze future research into the impact of scale limitations in analyses of sequence count data; to illustrate that scale limitations can lead to inferential errors in practice; yet to also show that rigorous and reproducible scale reliant inference is possible if done carefully.