Catholic University of the Most Holy Conception

Chile has one of the highest life expectancies in the Americas, alongside a rapidly aging population and a growing proportion of older women living in rural areas. One of the most common forms of civic engagement among older adults is participation in clubes de adulto mayor, neighborhood-based organizations that foster social participation and collective action. At the communal level, these clubs are organized under coordinating bodies known as UCAM, where leadership is predominantly female. This chapter examines how older women leaders in clubes de adulto mayor in Hualqui, Chile, foster intergenerational relationships and mobilize their communities through everyday communication practices. Grounded in transformational leadership theory and the life course perspective (Bass & Avolio, 1994; Elder, 1985), leadership is conceptualized as a dynamic process shaped by accumulated life experiences, agency, and sociocultural context. Drawing on seven qualitative interviews with female leaders aged 60–80, the analysis focuses on two dimensions: (1) intergenerational relationships with students, volunteers, and municipal staff and (2) communication strategies, including humor, warmth, and conflict resolution. These practices sustain group cohesion and help bridge generational divides. Findings show that older women’s leadership challenges ageist narratives of decline while strengthening intergenerational solidarity, resilience, and civic participation. The study contributes empirically by documenting leadership practices in rural older-adult organizations in the Global South and conceptually by integrating life course and transformational leadership perspectives to position communication as a core mechanism of intergenerational community building. Although situated in Chile, the findings offer transferable insights for inclusive, age-friendly initiatives in diverse contexts.

The energy transition demands sustainable and selective processes for recovering critical cobalt (Co) from complex secondary resources. This work evaluates the influence of extracting phase composition on Co(II) extraction from concentrated acidic chloride media (initial pH approximate to 0.85 before LiCl addition, 6-12 M LiCl), comparing conventional molecular diluents with ionic and eutectic matrices containing trioctylphosphine oxide (TOPO) as the extractant. Three systems were compared: 200 mM TOPO in n-dodecane/1-octanol, 200 mM TOPO in the ionic liquid (IL) [C(8)mim][Tf2N], and a hydrophobic eutectic solvent (HES) of equimolar TOPO:decanoic acid. All systems achieved high Co extraction (>93%) at 10 M LiCl, with the IL providing the highest selectivity (log alpha Co/Ni = 4.03), followed by the HES (3.77). Notably, the HES enabled a substantially higher Co loading capacity due to its greater TOPO concentration, although it showed lower extraction efficiency when normalized per mole of extractant. The dodecane phase presented a robust extraction and stripping behavior, but suffered hydrodynamic failure via third-phase formation and significant volatile losses (similar to 90% at 50 degrees C for 128 h). Conversely, while ionic and eutectic systems effectively suppressed solvent volatilization, they exhibited elevated dynamic viscosities (98.1 and 70.1 mPa center dot s, respectively) and significant aqueous phase losses for the IL (1334 ppm). Furthermore, a qualitative toxicity assessment and economic analysis revealed sharp trade-offs, balancing the more favorable estimated acute-toxicity profile and low cost of n-dodecane against the high cost and less favorable estimated acute-toxicity profile of the IL, positioning the HES as a balanced compromise among the evaluated systems.

Background The femoral circumflex arteries (FCAs), arising from the femoral and profunda femoris arterial system, exhibit substantial anatomical variability and are clinically relevant due to their role in supplying the femoral head and proximal thigh musculature. These variations may affect surgical, vascular, reconstructive, and anesthetic procedures in the femoral region. The objective of this study is to systematically evaluate the prevalence of FCA anatomical variants, characterize their patterns, and assess their clinical and surgical implications. Methods A systematic search was performed across PubMed/MEDLINE, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS up to July 2025. Studies describing morphological or branching variants of the medial or lateral FCA were included. Methodological quality was assessed using the Anatomical Quality Assurance tool. A random-effects model estimated pooled prevalences and subgroup differences. Thirty-six studies met the eligibility criteria, of which 29 contributed data to the quantitative meta-analysis. Results The global pooled prevalence of FCA variations was 56% (95% confidence interval [CI]: 46%–66%) with high heterogeneity (I2 = 99.5%). No significant laterality predominance was observed. Regional subgroup analysis demonstrated higher prevalence in European populations (33%, 95% CI: 25%–42%) relative to Asian populations (28%, 95% CI: 20%–36%). Sex-specific analysis showed a greater prevalence in females (72%, 95% CI: 59%–84%) than in males (42%, 95% CI: 29%–54%). Variations primarily involved origin, branching pattern, and course of the FCAs. Conclusion Anatomical variations of the FCAs are common and exhibit significant geographic and sexual variability. Based on this, we have proposed a classification of the probability of iatrogenic injury according to FCA variant and its relationship to the main surgical approaches to the hip.

A bstract We apply the conformal compensating technique for constructing matter couplings to conformal scalars on a D -dimensional foliated conformal Carroll manifold dividing the tangent space into ( p + 1)-dimensional longitudinal and ( D − p − 1)-dimensional transversal directions corresponding to p -branes. We show that the conformal Carroll algebra that was used for particle-like foliated geometries with p = 0 cannot be used for higher-dimensional objects, called p -branes, with 0 < p ≤ D − 2. Furthermore, string-like foliated geometries are not suitable for the conformal compensating technique due to the conformal invariance in the longitudinal directions that is present for p = 1. All other cases can be dealt with provided one uses a different conformal extension of the Carroll algebra that amounts to a conformal extension in the longitudinal directions only supplemented with an additional an-isotropic dilatation. By brane-duality similar results hold for foliated Galilean geometries which we present as well. Our results nicely fit in with recent work on foliated Aristotelian geometries.

The ultrarelativistic (Carrollian) regime of gravity has recently emerged as a fertile framework for exploring holography, non-Lorentzian symmetries, and geometric limit of general relativity. In this Letter, we establish the presence of a nonvanishing torsion within three-dimensional Carrollian gravity by constructing the Carrollian Mielke-Baekler (C-MB) gravity theory in its Chern-Simons formulation, obtained as the ultrarelativistic limit of the relativistic Mielke-Baekler model. The resulting C-MB theory features nonzero temporal torsion and curvature, together with spatial curvature, providing the most general three-dimensional Carrollian gravity model with these properties. Temporal torsion affects nonaffinity of null generators and boundary dynamics. Several known ultrarelativistic gravity theories arise as particular limits of this framework, highlighting its unifying character.