- Research Article
- 10.1016/j.jmmm.2026.174061
Spin wave modes in Pacman-shaped disks with perpendicular uniaxial anisotropy
- Jun 01, 2026
- Journal of Magnetism and Magnetic Materials
- S Urcia-Romero + 3 more +3
Publications from 2021 to 2026
Showing 10 of 251 papers
Spin wave modes in Pacman-shaped disks with perpendicular uniaxial anisotropy
Stress-tuned spin wave modes in magnetic vortex nanoellipses for flexible magnonic systems
Mapping Olive Crops (Olea europaea L.) in the Atacama Desert (Peru): An Integration of UAV-Satellite Multispectral Images and Ensemble Machine Learning Models
Spatial monitoring of olive systems in arid regions is essential for understanding agricultural expansion, water pressure, and productive sustainability. This study aimed to map coverage and estimate olive plantation density (Olea europaea L.) in the Atacama Desert, Tacna (Peru) through the integration of UAV-satellite multispectral images and machine learning algorithms (CART, Random Forest, and Gradient Tree Boosting). Forty-eight optical, radar, and topographic covariates were analyzed. Fifteen were selected for coverage classification and 16 for plantation density, using Pearson’s correlation (|r| > 0.75). The classification maps reported an area of 23,059.87 ha (38.21%) of olive groves, followed by 5352.10 ha (8.87%) of oregano cultivation and 725.74 ha (1.20%) of orange cultivation, with respect to the total study area, with overall accuracy (OA) of 86.6% and a Kappa coefficient of 0.81. Meanwhile, the RF and GTB regression models showed R2 ≈ 0.89 and RPD > 2.8, demonstrating excellent predictive performance for estimating tree density (between 1 and 8 trees per 100 m2). Furthermore, the highest concentration of olive trees was found in the central and southern zones of the study area, associated with favorable soil and microclimatic conditions. This work constitutes the first comprehensive approach for olive mapping in southern Peru using UAV–satellite fusion, demonstrating the capability of ensemble models to improve agricultural mapping accuracy and support water and productive management in arid ecosystems.
Read moreStable 1T″ HfCl2 monolayer with strong excitonic effects and promising solar harvesting efficiency.
In this work, we performed a computational screening of group IV transition-metal dihalide monolayers in the recently proposed 1T″ phase. We have thoroughly examined their structural, electronic, optical, and excitonic characteristics, using density functional theory with both the generalized gradient approximation (PBE) and hybrid (HSE06) exchange-correlation approaches including spin-orbit coupling, complemented by Wannier-function-based tight-binding and Bethe-Salpeter equation analyses; as well as phonon dispersion calculations and ab initio molecular dynamics to shed light on the material stability. Out of the nine candidate systems, only 1T″ ZrCl2, HfCl2, and HfBr2 were found to be dynamically and thermally stable, with semiconducting behavior observed exclusively for HfCl2. From a detailed analysis of this compound, we have revealed pronounced excitonic effects, with a binding energy of 275 meV, strong optical anisotropy, and broadband absorption covering the infrared, visible, and ultraviolet ranges. Moreover, efficiencies of up to 20% were obtained by evaluating the 1T″-HfCl2 photovoltaic performance using the spectroscopic limited maximum efficiency and the Shockley-Queisser limit. These results highlight 1T″-HfCl2 as a promising two-dimensional semiconductor for optoelectronic and solar energy applications.
Read moreRelación entre el plano terminal y el tipo de arco según Baume en niños de 3 a 5 años
Objetivo: Determinar la relación entre el plano terminal y el tipo de arco según Baume en niños de 3 a 5 años (Tacna, 2024). Metodología: Estudio no experimental, transversal y de nivel relacional. La muestra estuvo constituida por 145 niños. La recolección de datos se realizó mediante una ficha diseñada para el registro clínico y la clasificación del arco según Baume. Resultados: Se observó mayor prevalencia del plano terminal mesial asociado al arco tipo I, con una frecuencia de 46,21 % en el maxilar superior y 39,31 % en el maxilar inferior; sin embargo, esta distribución no mostró diferencias estadísticamente significativas. Conclusión: Se descartó la existencia de una relación entre el tipo de plano terminal y el tipo de arco según Baume en niños de 3 a 5 años de una institución educativa inicial de Tacna.
Read moreLa Cofradía del Rosario del pueblo de Tacna:
El presente artículo analiza la Cofradía del Rosario del pueblo de Tacna durante el siglo XVIII como una institución que integró la devoción, la economía y la organización social. A través de fuentes del Archivo Eclesiástico de la Diócesis de Tacna y Moquegua, se examina el papel de sus mayordomos —Pedro de Salamanca, Juan Severino de Guzmán y Fulgencio de Barrios— en la administración de bienes, censos y limosnas, así como en la reconstrucción y mantenimiento de la capilla. El estudio evidencia que la cofradía actuó como una unidad de gestión económica y espiritual, capaz de movilizar recursos, sostener el culto y consolidar redes de prestigio dentro de la sociedad tacneña. Asimismo, se destaca la importancia de las visitas eclesiásticas como mecanismos de control y legitimación institucional. Esta aproximación busca aportar a la historia eclesiástica local y a la comprensión del papel de las cofradías en la vida colonial del sur andino.
Read moreThe right to healthy lunchboxes and eating habits in schoolchildren
Introduction: Health is a key aspect of human development. Therefore, it is necessary to study whether schoolchildren are being provided with a healthy lunchbox as part of their human rights, as well as whether these rights are linked to their eating habits. Objective: To determine how the right to healthy lunchboxes relates to eating habits in schoolchildren. Methodology: A basic type was considered, and it was also approached with a quantitative focus, and it was also framed within the non-experimental design, with a hypothetical deductive method and cross-section, considering the survey as a technique for this work, and the survey was selected as the instrument. Results: A p-value of 0.001 and Spearman's rho of 0.852 were found between the right to have healthy lunchboxes with respect to eating habits, also 35.4% consider that the right to have healthy lunchboxes is regularly respected, so the care of eating habits is on a regular basis. Discussion: The findings are supported by previous research, which found both agreement and disagreement with the postulates of authors and theorists, highlighting the need to improve criteria for healthy lunchboxes to raise awareness about schoolchildren's eating habits. Conclusions: The right to healthy lunchboxes is highly positively related to schoolchildren's eating habits, generating the need to include educational policies to improve this aspect and help strengthen and raise awareness about human health and proper eating habits.
Read moreHOMA-IR levels in pediatric metabolic syndrome: characterization and associated clinical and biochemical factors
Objetivo: Caracterizar los niveles de resistencia a la insulina mediante el modelo homeostático de resistencia a la insulina (HOMA-IR) en niños y adolescentes con síndrome metabólico (SM), analizar los factores clínicos y bioquímicos asociados a su elevación y evaluar el desempeño del índice triglicéridos glucosa-circunferencia de cintura (TyG-CC) como marcador sustituto en esta población. Materiales y métodos: Se realizó un estudio transversal en el Hospital Hipólito Unanuede Tacna, Perú. Se incluyeron pacientes de 10 a 17 años con diagnóstico clínico de SM entre enero de 2015 y diciembre de 2024, definido según los criterios del Programa Nacional de Educación sobre el Colesterol — Tercer Panel de Tratamiento en Adultos (NCEP-ATP III) adaptados a una población pediátrica. Para identificar los factores clínicos asociados a los valores elevados del HOMA-IR, se empleó un modelo lineal generalizado (GLM). Asimismo, se evaluó el rendimiento diagnóstico delas variables asociadas significativamente. Resultados: Se incluyeron 68 niños y adolescentes con SM, con edad promedio de 13,2 ± 2,2 años; predominó el sexo femenino (51,50 %). Los niveles del HOMA-IR fueron elevados, con una mediana de 6,69 y 23,50 % se ubicó por encima del percentil 75 (HOMA-IR ≥10). En el análisis ajustado mediante el GLM, la falta de un seguro de salud y un TyG-CC elevado se asociaron significativamente con un HOMA-IR alto. El TyG-CC presentó un punto de corte >980 para discriminar un HOMA-IR elevado, con sensibilidad del 45,00 % y especificidad del 85,40 %, lo que permitió identificar de manera confiable a adolescentes con marcada resistencia a la insulina. Estos hallazgos confirman la utilidad de incorporar índices antropométricos y bioquímicos simples en la práctica clínica, especialmente en contextos con limitaciones de acceso a pruebas especializadas. Conclusiones: En niños y adolescentes con SM, la resistencia a la insulina fue elevada, con una cuarta parte de la muestra por encima del percentil 75. La falta de un seguro de salud y un TyG-CC elevado se asociaron significativamente con un HOMA-IR alto, lo que destaca su relevancia como indicadores de riesgo metabólico en esta población pediátrica.
Read moreReconstructing aquifer dynamics with machine learning: Linking irrigation expansion to groundwater decline in a data-scarce hyper-arid region
Bayesian Optimization for the Synthesis of Generalized State-Feedback Controllers in Underactuated Systems
Underactuated systems, such as rotary and double inverted pendulums, challenge traditional control due to nonlinear dynamics and limited actuation. Classical methods like state-feedback and Linear Quadratic Regulators (LQRs) are commonly used but often require high gains, leading to excessive control effort, poor energy efficiency, and reduced robustness. This article proposes a generalized state-feedback controller with its own internal dynamics, offering greater design flexibility. To automate tuning and avoid manual calibration, we apply Bayesian Optimization (BO), a data-efficient strategy for optimizing closed-loop performance. The proposed method is evaluated on two benchmark underactuated systems, including one in simulation and one in a physical setup. Compared with standard LQR designs, the BO-tuned state-feedback controller achieves a reduction of approximately 20% in control signal amplitude while maintaining comparable settling times. These results highlight the advantages of combining model-based control with automatic hyperparameter optimization, achieving efficient regulation of underactuated systems without increasing design complexity.
Read more