The circular economy (CE) framework is increasingly recognized as essential for achieving sustainable development by addressing the challenges of resource depletion, waste generation, and environmental degradation. This study examines the relationship between resource consumption, waste management procedures, and energy efficiency within European Union (EU) member states, leveraging data from 2004 to 2023. Using Pearson correlation analysis, Principal Component Analysis (PCA), and K-means clustering, this study identifies key sustainability performance indicators and classifies EU nations into four distinct clusters based on CE adoption. These findings reveal a strong positive correlation between resource productivity and circular material use, indicating that efficient resource management significantly enhances sustainability performance. Similarly, energy productivity exhibits a moderate correlation with resource efficiency, suggesting that economies optimizing energy consumption also enhance material use efficiency. This study also assesses the role of policy instruments, such as environmental taxation, which show a weak negative correlation with resource productivity. These insights provide actionable recommendations for policymakers to tailor interventions, harmonize sustainability strategies, and address regional disparities to accelerate the transition to a resilient and efficient circular economy model.

Times of hardship lead to insecurity and uncertainty about the future. When this happens, many people turn to gold or other precious metals, real estate, land, and tangible assets in general. The multiple non-cyclical crises that have occurred in recent years have led to a resurgence of interest in gold. The regression of globalization and the multipolar order derived from the pandemic, the energy crisis, the degradation of geopolitics to the point of war and the nomad wars between the United States and China have marked the beginning of a new type of capitalism in which market uncertainty is heightened by economic and political interdependencies between countries. This research aims to analyse the actuality of the gold standard among the populations of civilized countries, which began to show an increase in the demand for gold directly proportional to the depreciation of geopolitical events. This article also traces the evolution of the economic idea around gold, from its beginnings to the banking and financial system’s relation to it, providing new insights on economic behaviour during difficult times.

This study investigates the predictive contribution of digital infrastructure to GDP per capita growth across 27 European Union Member States over the period 1995–2024, using a balanced panel of 810 country–year observations and an explainable machine learning framework. An XGBoost model trained on six World Bank indicators—fixed broadband subscriptions, internet users, mobile subscriptions, patent applications, R&D expenditure, and secure internet servers—achieves a training R² of 0.804 and a test R² of 0.430 under temporal out-of-sample validation spanning the COVID-19 structural break. TreeSHAP decomposition identifies fixed broadband as the strongest predictor of model-estimated GDP per capita growth (mean |SHAP| = 0.948; bootstrap rank 1 in 78% of 50 resamples; Friedman Chi-square (5) = 168.16, p < 0.001), providing predictive support for Hypothesis H1. Innovation indicators, represented by patent applications and R&D expenditure, exceed the pre-specified materiality threshold, providing predictive support for H2, while SHAP dependence plots reveal pronounced non-linear threshold patterns consistent with S-curve diffusion theory, supporting H3. Temporal SHAP decomposition identifies three structural phases: broadband dominance (1995–2007), crisis-induced reconfiguration (2008–2013), and quality convergence (2014–2024). The framework reconciles contradictory findings from prior literature by visualizing the complete functional form of the broadband–growth relationship without imposing a parametric specification.