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Universal localizations, Atiyah conjectures and graphs of groups
Get PDFLet G be a countable group that is the fundamental group of a graph of groups with finite edge groups and vertex groups satisfying the strong Atiyah conjecture over K ⊆ C a field closed under complex conjugation. Assume that the orders of finite subgroups of G are bounded above. We show that G satisfies the strong Atiyah conjecture over K. In particular, this implies that the strong Atiyah conjecture is closed under free products. Moreover, we prove that the ∗-regular closure of K[G] in, U(G), RK[G], is a universal localization of the graph of rings associated to the graph of groups, where the rings are the corresponding ∗-regular closures. As a result, we obtain that the algebraic and center-valued Atiyah conjecture over K are also closed under the graph of groups construction as long as the edge groups are finite. We also infer some consequences on the structure of the K0 and K1-groups of RK[G]. The techniques developed enable us to prove that K[G] fulfills the strong, algebraic and center-valued Atiyah conjectures, and that RK[G] is the universal localization of K[G] over the set of all matrices that become invertible in U(G), provided that G belongs to a certain class of groups TVLI, which contains in particular virtually-{locally indicable} groups that are the fundamental group of a graph of virtually free groupsThe author is grateful to Andrei Jaikin-Zapirain for many helpful conversations and for having suggested him the finite rank operators point of view towards the strong Atiyah conjecture. I am grateful to an anonymous referee, whose comments and corrections have much improved the article. The author is supported by PID2020-114032GB-I00/AEI/10.13039/501100011033 of the Ministry of Science and Innovation of Spai
The educational perceived usefulness of ChatGPT by university students
Get PDFLa Inteligencia Artificial está cambiando el enfoque de la educación. El objetivo de este trabajo es conocer la utilidad didáctica percibida del ChatGPT por parte del alumnado universitario. El instrumento utilizado es la Escala UTAUT2, que mide el uso de las nuevas tecnologías, a partir de ocho factores: la expectativa de rendimiento, la expectativa del esfuerzo, la influencia social, las condiciones favorables, la motivación hedónica, el valor del precio, el hábito y la intención de uso. La muestra está formada por 152 estudiantes de la Universidad Autónoma de Madrid (79.2% chicas, 20.8% chicos), con una media de edad de 21.3 años. Los resultados muestran que la experiencia de uso es el factor que más influye sobre las condiciones favorables, la motivación hedónica y el hábito. Los cinco factores que influyen sobre la utilidad percibida del ChatGPT son el hábito, las condiciones favorables, la expectativa de rendimiento, la motivación hedónica y el valor del precio. Estos resultados sugieren la necesidad de desarrollar actividades de alfabetización digital sobre el uso de ChatGPT desde una perspectiva crítica, fomentar el uso responsable de esta tecnología y dar pautas al alumnado sobre la escritura de instrucciones que generen una respuesta precisaArtificial Intelligence is changing the approach to education. This article aims to know the educational perceived usefulness of ChatGPT by university students. The instrument used is the UTAUT2 Scale, which measures the use of new technologies, based on eight factors: performance expectancy, effort expectancy, social influence, facilitating conditions, hedonic motivation, price value, habit and use intention. The sample consists of 152 students from the Universidad Autónoma de Madrid (79.2% girls, 20.8% boys), with an average age of 21.3 years. The results show that use experience is the factor that most influences facilitating conditions, hedonic motivation and habit. The five factors influencing the perceived usefulness of ChatGPT are habit, facilitating conditions, performance expectancy, hedonic motivation and price value. These findings suggest the need to develop digital literacy activities on the use of ChatGPT from a critical perspective, to encourage the responsible use of this technology and to provide guidance to students on writing instructions that generate an accurate respons
Meaningless, but I still have your support: A diary study on the interactive effects of workplace social support at work and meaningfulness on workers' energy levels
Get PDFSocial support is a resource capable of generating energy and well-being resources among workers. However, the literature has paid little attention to the mechanisms and conditions that can explain this possibility. Drawing on the Conservation of Resources (COR) Theory and an intraindividual approach, this study aimed to analyze whether the effects of daily social support at work were associated with daily variations in levels of vigor at work and vitality at home, conditioned by workers' daily levels of meaningfulness. This is a study that employs an experiential sampling methodology. A total of 94 Spanish nurses from hospitals and primary health-care centers participated by completing a diary over five working days at three times of the day (i.e., before starting work in the morning, leaving work in the afternoon, and at night at home). Daily measures of support from colleagues, meaningfulness, vigor, and vitality were collected. The results showed that social support from coworkers was particularly significant and positive in explaining daily levels of vigor at work and vitality at home for those workers experiencing low levels of meaningfulness in the mornings before going to work. These results were discussed within the theoretical framework of COR theory (i.e., principle of resource salience)This work was supported by I+D+INational Project of Ministerio de Ciencia e Innovación (PID2019-106368GB-I00) AEI/10.13039/50110001103
Aristocratic burials and ecclesiastical networks in Navarra. A brief comparison (14th and 15th centuries)
No full textEl estudio pretende analizar las disposiciones testamentarias de las oligarquías urbanas navarras, y de modo especial las de Pamplona, para reflexionar sobre sus comportamientos a la hora de elegir sepultura. Su preferencia por la catedral, las parroquias y las iglesias de los conventos urbanos, el interés en mantener tradiciones familiares o establecer nuevos criterios; el deseo, en suma, de significar de algún modo su prestigio social, jurídico y económico a la hora de perpetuar su memoria a través de los espacios de inhumaciónThis study aims to analyse the testamentary dispositions of the urban oligarchies of Navarre, and especially those of Pamplona, to reflect on their behaviour when it came to choosing burial sites. Their preference for the cathedral, the parish churches and the churches of the urban convents, their interest in maintaining family traditions or establishing new criteria; the desire, in short, to signify in some way their social, juridic and economic prestige when it came to perpetuating their memory through burial spacesEste trabajo se inserta en el marco de los proyectos COMMEMORtis (EXPL/HAR-HIS/0532/2021 del Gobierno de Portugal, FCT), PRO-UPNAI 1506 de la Universidad Pública de Navarra y MINORES (PID2022-138387NB-I00 de la Agencia Estatal de Investigación de España
A cross-country analysis and comparison of the technical efficiency of higher education systems
No full textThe study of the performance of primary and secondary educational institutions has gained popularity in recent years, but cross-country evaluations of higher education (HE) systems remain rare. This study aims to fill this gap by assessing the technical efficiency (TE) of 87 national HE systems using stochastic production frontier models. The empirical model considers, for each country, the number of universities in the 2023 SCImago Institutions Ranking (SIR) by knowledge areas as the dependent variable, and GDP, R&D expenditures, and national English proficiency as explanatory variables. To offer a comprehensive analysis, the model is applied across all SIR ranking levels. Results show that Western countries generally lead in TE, but three performance profiles emerge: countries that concentrate their resources on a few HE institutions (efficient at the top SIR levels), others with homogeneous HE institutions (high TE across all levels), and low-performance HE systems. Policy implications are discusse
Silicon amorphization responses by combined irradiations with MeV ion beams and ultrashort laser pulses
No full textThis work demonstrates a significant synergistic effect between MeV ion implantation and femtosecond laser irradiation in silicon amorphization. The achievable amorphization depth and the range of laser fluencies leading to amorphization is increased for implanted samples in comparison to pristine silicon. In Si (100) samples, prior to femtosecond laser irradiation (800 nm and 120 fs, or 1030 nm and 180 fs) ion-induced defects are produced with protons (0.6, 1 and 2 MeV) or Si-ions (2 MeV) at varying ion-irradiation fluences. Then, the investigated defects densities before laser irradiation range from low levels to levels approaching ion-induced amorphization (defects per atom, dpa, from 10–9 to 0.1). The optimal pre-conditioning for subsequent femtosecond laser-induced amorphization is found at a moderate defect density level, dpa =10–5. Additionally, it is shown that the achievable spatial resolution of the synergistic material amorphization is determined by the high resolution of the focused ion irradiation, suggesting a potential pathway for high-resolution patterning based on laser assisted techniques. However, at high defect densities (dpa ≈ 0.1), the synergistic effect diminishes, and femtosecond laser irradiation instead reduces disorder, indicating a defect-annealing effect rather than further amorphizationThis work is part of the projects ULS_PSB (grants PID2020-112770RB-C21 andPID2020-112770RB-C22), HyperSpec (grant PID2023-148178OB-C22) funded by MCIN/AEI/10.13039/ 501100011033 and HyperSolar (grant TED2021-130894B-C22) funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR. It was partially funded by the CSIC through the call for internationalization i-LINK 2022 (project ILINK22056) and by the French National Research Agency (grant ANR-23-CE08–0029–03). Authors acknowledge the support from CMAM-UAM for the beam time (STD002/22, STD015/22, and STD024/23) and its technical staff support. Part of the work was conducted using LaMP facilities at LP3. I.S. acknowledges the support by the Spanish Ministry of Science, Innovation and Universities vía a doctoral grant (FPU23/ 01300
Entornos laborables saludables
No full textMaterial formativo destinado a profesionales de la coordinación de TrasplantesA lo largo de las últimas décadas, el concepto de entorno de trabajo saludable ha evolucionado significativamente. En un inicio, se centraba de manera exclusiva en el ambiente físico de trabajo, manteniendo el enfoque tradicional de la salud y seguridad ocupacional que abordaba riesgos físicos, químicos, biológicos y ergonómicos. Sin embargo, esta perspectiva se ha ampliado para incluir aspectos como los hábitos de salud (estilos de vida), factores psicosociales (organización y cultura laboral) y vínculos con la comunidad, considerando todos los elementos que pueden influir en la salud de los empleados. En este cuadernillo se presentan las interrelaciones entre trabajo, salud y comunidad, abordando de manera detallada el mobbing como uno de los factores psicosociales que pueden comprometer el bienestar psicológico de los trabajadores. Además, se analiza el efecto que la salud de los trabajadores ejerce sobre las instituciones sanitarias para, finalmente, presentar un proceso de implementación de un programa de espacio laboral saludabl
Easy and straightforward FPGA implementation of Model Predictive Control using HDL coder
No full textModel Predictive Control (MPC) is widely adopted for power electronics converters due to its ability to optimize system performance under dynamic constraints. However, its FPGA implementation remains challenging due to the complexity of Hardware Description Language (HDL) programming. This paper addresses this challenge by introducing a straightforward methodology that simplifies FPGA implementation using MATLAB R2022b Simulink HDL Coder. It is shown that HDL Coder yields favorable synthesis outcomes, both in terms of area and time, compared to hand-coded HDL. Notably, the proposed method achieves a significantly reduced sampling step for the MPC algorithm— down to 32 ns—marking a substantial improvement over state-of-the-art implementations. The Integrated Logic Analyzer (ILA) IP available in the Vivado tool is used during the HIL testing phase to facilitate the real-time observation and analysis required for debugging and confirming the FPGA-implemented controller performance. Additionally, this paper discusses the advantages of utilizing HDL Coder for simplifying the FPGA programming process in power electronics applications and addresses the design challenges encountered using this methodologyThis research has been partially funded by the project PID2022-137593OB-I00, financed by the Spanish Ministry MCIN/AEI/10.13039/501100011033/FEDER, UE, and FSE+
Historical hourly information of four European wind farms for wind energy forecasting and maintenance
No full textFor an electric company, having an accurate forecast of the expected electrical production and maintenance from its wind farms is crucial. This information is essential for operating in various existing markets, such as the Iberian Energy Market Operator—Spanish Hub (OMIE in its Spanish acronym), the Portuguese Hub (OMIP in its Spanish acronym), and the Iberian electricity market between the Kingdom of Spain and the Portuguese Republic (MIBEL in its Spanish acronym), among others. The accuracy of these forecasts is vital for estimating the costs and benefits of handling electricity. This article explains the process of creating the complete dataset, which includes the acquisition of the hourly information of four European wind farms as well as a description of the structure and content of the dataset, which amounts to 2 years of hourly information. The wind farms are in three countries: Auvergne-Rhône-Alpes (France), Aragon (Spain), and the Piemonte region (Italy). The dataset was built and validated following the CRISP-DM methodology, ensuring a structured and replicable approach to data processing and preparation. To confirm its reliability, the dataset was tested using a basic predictive model, demonstrating its suitability for wind energy forecasting and maintenance optimization. The dataset presented is available and accessible for improving the forecasting and management of wind farms, especially for the detection of faults and the elaboration of a preventive maintenance planThe project, titled “ICARUS—Inspección y Control Automatizado con Redes neuronales y UAVs en Sistemas Fotovoltaicos” (ref. SI4/PJI/2024-00233), is funded by the Comunidad de Madrid through a direct grant agreement for the promotion of research and technology transfer at the Universidad Autónoma de Madri
Recurrent spinal subdural hematoma in granulomatosis with polyangiitis
No full textNervous system involvement is uncommon in granulomatosis with polyangiitis (GPA), a systemic autoimmune disease with episodes of necrotizing vasculitis. It is usually due to the compressive effect of dural or epidural masses. Spinal hemorrhagic presentation is exceptional. A 41-year-old woman diagnosed with GPA presented with three episodes of acute spinal subdural hematoma separated by eight years and ten months, respectively. The symptomatic debut was pain and paresis in all episodes. On all occasions, a lesion compatible with acute spinal subdural hematoma was diagnosed by magnetic resonance imaging (MRI). All episodes were treated conservatively with corticosteroids and immunosuppressants. The patient presented complete neurological recovery in the first two episodes. A mild residual left lower limb paresis remains after the last one. Follow-up MRI was performed after all episodes, and no focal intraspinal lesions were detected. Spinal subdural hemorrhage is a form of manifestation of GPA, either as a debut or in the course of the disease. We describe the third confirmed case of spontaneous spinal hemorrhage secondary to GPA published in the literature and the first with recurrence. Given the extraordinary response to immunosuppressive therapy, a high level of clinical suspicion is necessary to establish treatment as
early as possibl