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Long-Horizon MPC Reference Generator for Circulating Currents in Modular Multilevel Converter-Based Variable-Speed Drives
No full textThe article introduces a circulating current reference generator based on a constrained model predictive control (MPC) in modular multilevel converters (M2C) for drive applications. It aims to control the energy in each cluster by generating optimal circulating currents over a long-horizon prediction while considering branch current limits. The optimal control problem is decomposed into smaller subproblems, which allows the utilization of an iterative algorithm based on the alternating direction method of multipliers (ADMM) to efficiently solve the optimization problem. As a result, the ADMM-based reference generator enables a considerably extended prediction horizon, which enhances M2C performance, particularly in balancing and mitigating low-frequency oscillations in capacitor voltages during challenging operating conditions like low-speed and high-torque scenarios. The proposed control is validated by experimental results using an M2C with four cells per cluster driving a 3 kW induction machine
Inclusive health for people with disabilities in Chile: a national health system assessment
No full textBackground Globally, one in six people have disabilities. They often experience health inequities and many of them arise from system-level failures. This study aimed to assess the inclusion of people with disabilities in the health system of Chile and define recommendations for improvement on the basis of the evidence. Methods A health system assessment was conducted between June and November 2023 following the Missing Billion Disability-Inclusive Health Systems Framework and System Level Assessment Toolkit. The assessment was led by the Ministry of Health and conducted by a task team, including organizations of people with disabilities. Mixed methods were used to collect data on nine system-level and service delivery components for a set of 33 indicators, including through a health policy review, systematic review, key informant interviews and a scoping review. Scores were assigned to indicators, components and the overall health system. With this assessment, key recommendations were developed and agreed upon on the basis of a prioritization analysis of impact and feasibility during workshops. Results The Chilean health system was assessed to have a low progress towards disability-inclusive health. Among system-level components, intermediate progress has been made in governance, health financing and data and evidence. However, progress in leadership on disability seems low. Among service delivery components, the accessibility of health facilities and rehabilitation and assistive technology showed the best results. However, there were notable gaps in the autonomy and awareness and ability to afford care by people with disabilities, and the capacity of human resources to support this group. The task team defined priority actions in governance, leadership, and human resources. Conclusions Short-term actions for the country should involve foundational governance on inclusive health, strengthened leadership of people with disabilities, and mandatory training of healthcare workers to improve healthcare access among this population. Future reassessments should be conducted to monitor and evaluate progress on effective healthcare coverage and health status among people with disabilities
Effects of leucine intake on muscle growth, strength, and recovery in young active adults: a systematic review of randomized controlled trials
No full textPurposeLeucine is an essential branched-chain amino acid required for skeletal muscle protein synthesis as a substrate and as a key anabolic signaling molecule primarily via activation of the mTORC1. Leucine supplementation has been proposed to enhance muscle adaptations, with some studies showing improvements in muscle growth. However, results from randomized controlled trials (RCTs) have been inconclusive, potentially due to variations in resistance exercise protocols and Leu dose or duration of supplementation. This systematic review explores the effects of leucine supplementation on resistance-training-induced muscle growth, strength, and recovery in healthy individuals.MethodsA systematic literature search was conducted across multiple databases (MedLine, EMBASE, PubMed, Science Direct, Scopus, and Cochrane) to identify RCTs investigating the effect of leucine intake on markers of muscle growth, strength, and recovery in trained adults aged 18 to 40 years old.ResultsA total of 14 RCTs were identified including acute (n = 5) and chronic leucine (n = 9) supplementation. A total of 13 studies did not find significant differences in muscle mass, strength, or recovery between leucine-supplemented and placebo groups.ConclusionsThe evidence from this systematic review suggests that leucine supplementation does not confer significant benefits in muscle growth, strength, or recovery in healthy, trained young adults.Food Science and Nutrition" of the University of Cambridge ReachSci Societ
Reagent efficiency and analytical sensitivity optimization for a reliable SARS-CoV-2 pool-based testing strategy
No full textBackground: The SARS-CoV-2 pandemic caused millions of infections worldwide. Among the strategies for effective containment, frequent and massive testing was fundamental. Although sample pooling allows multiplying the installed analysis capacity, the definition of the number of samples to include in a pool is commonly guided more by economic parameters than analytical quality. Methods: We developed a mathematical model to determine the pooling conditions that maximize reagent efficiency and analytical sensitivity. We evaluated 30 samples individually and in 2-sample to 12-sample pools. Using Passing Bablok regressions, we estimated the shift of Ct values in the RT-qPCR reaction for each pool size. With this Ct shift, we estimated sensitivity in the context of the distribution of 1,030 individually evaluated positive samples. Findings: Our results showed that the most significant gain in efficiency occurred in the 4-sample pool, while at pools greater than 8-sample, there was no considerable reagent savings. Sensitivity significantly dropped to 87.18 %–92.52 % for a 4-sample pool and reached as low as 77.09 %–80.87 % in a 12-sample pooling. Conclusions: Our results suggest that a 4-sample pooling maximizes reagent efficiency and analytical sensitivity. These considerations are essential to increase testing capacity and efficiently detect and contain contagious
Through the convex Looking Glass: A Helmholtzian lesson for the connection between dynamics and chronogeometry in spacetime theories
No full textOver the last two decades, the rise of the dynamicist view in the philosophy of spacetime theories has motivated a discussion about the way in which chronogeometric structure and dynamics are connected. Geometricists defend that chronogeometry determines and explains dynamics, whereas dynamicists state that it is the other way around. Both parties assume that the arrow of explanation at issue involves a claim of fundamentality and priority of one of the elements over the other. I challenge this assumption, and I propose a third way to understand the connection. Drawing a lesson from Herman von Helmholtz's and David Hilbert's views on the foundations of geometry, I argue that in spacetime theories chronogeometry and dynamics are inextricably interconnected counterparts, so claims of fundamental explanation and priority, regardless of the direction of the alleged arrow, are misconceptions. The link between chronogeometry and dynamics in spacetime theories is properly understood in terms of a bidirectional arrow, not in terms of a unidirectional arrow of fundamental explanation
What do In-Service Teachers Notice in Teaching–Learning Situations that Seek to Foster Modelling?
No full textProfessional noticing has been stressed as one of the key professional competencies that teachers must develop. To date, there is a robust amount of literature on teacher noticing with a focus on students’ mathematical thinking. However, we have thus far not found any study that focuses on teacher noticing of classroom situations in which mathematical modelling is to be fostered. A professional development program was designed; and five Chilean elementary teachers were enrolled. Participants analysed video recordings of real in-class teaching sessions from other colleagues or from their own teaching. Such recordings illustrated different characteristics of fostering (or not) the mathematical modelling in classroom. Results show modelling situations identified by teachers as well as characteristics that teachers identified on how the modelling was being fostered. Furthermore, results illustrate that identifying classroom situations in which mathematical modelling is fostered seems to be linked to the characterization that teachers have about modelling
Música de la calle, inmigración y género como nodos de la cultural musical del hip-hop en Concepción, Chile
No full textTesis (Doctor en Artes, mención Música)--Pontificia Universidad Católica de Chile, 2024Esta tesis examina el desarrollo del hip-hop en la ciudad de Concepción, Chile, en la década de 2020, enfatizando en la música de la calle, el género y la inmigración. El marco teórico de esta investigación se basa en los conceptos de escena musical, amateurismo y generación. Un primer capítulo argumentativo estudia el rap como expresión de música callejera en Concepción. La creciente presencia de jóvenes raperos/as cantando en el transporte y espacio público ha introducido renovadas sonoridades, formas de interpretación y performatividades. En este contexto, los/as raperos/as ponen en evidencia una disposición juvenil de la música callejera, que dista en algunos aspectos clave de las prácticas desarrolladas por músicos “adultos”. El siguiente capítulo explora la presencia de hiphoperos/as inmigrantes. Se examinan las redes sociales de apoyo formadas en la actual ola de inmigración latinoamericana en Chile, ofreciendo una perspectiva distinta del fenómeno al exponer cómo las culturas musicales también pueden generar conexiones sociales y fomentar la solidaridad entre y para inmigrantes. El último capítulo estudia al hip-hop de Concepción desde un enfoque de género. Se presenta como estudio de caso al festival y grupo musical de rap, Expresión FEM. Estas raperas dan cuenta de la asociatividad femenina para dar solución a la falta de oportunidades que las mujeres enfrentan en la música, a la par que postulan transformaciones en las dinámicas sociales y artísticas del hip-hop. Asimismo, este grupo de rap aborda problemáticas de género específicas en sus letras de canciones, lo que da cuenta de una producción musical de carácter feminista. Las conclusiones de la tesis sugieren que el hip-hop en Concepción debe ser entendido como una escena musical dinámica, en la que diversas prácticas musicales y de baile, junto con identidades sociales variadas, contribuyen a su vitalidad y fluidez.ANIDNúcleo Milenio en Culturas Musicales y Sonora
The future of MRI in thoracic aortopathy: blueprint for the paradigm shift to improve management
No full textThoracic aortopathies result in aneurysmal expansion of the aorta that can lead to rapidly fatal aortic dissection or rupture. Despite the availability of abundant non-invasive imaging tools, the greatest contemporary challenge in the management of thoracic aortic aneurysm (TAA) is the lack of reliable metrics for risk stratification, with absolute aortic diameter, growth rate and syndromic factors remaining the primary determinants by which prophylactic surgical intervention is adjudged. Advanced MRI techniques present as a potential key to unlocking insights into TAA that could guide disease surveillance and surgical intervention. MRI has the capacity to encapsulate the aorta as a complex biomechanical structure, permitting the determination of aortic volume, morphology, composition, distensibility and fluid dynamics in a time-efficient manner. Nevertheless, current standard-of-care imaging protocols do not harness its full capacity. This state-of-the-art review explores the emerging role of MRI in the assessment of TAA and presents a blueprint for the required paradigm shift away from aortic size as the sole metric for risk stratifying TAA
Theoretical study of Photon-Assisted Tunneling of Ultracold Atoms in a Triple-well Potential
No full textTesis (Master’s degree in Physics)--Pontificia Universidad Católica de Chile, 2024The thesis studies Photon-Assisted Tunneling (PAT) in a system of ultracold atoms in a triple-well potential, utilizing Bose-Hubbard and Gross-Pitaevskii models. Simulations reveal that an ac-driving field influence tunneling dynamics, enabling quantum self-trapping and PAT. The study extends to open quantum systems, analyzing PT-symmetric setups with balanced gain and loss, showcasing PAT’s role in quantum control and potential applications in ultracold atom systems and quantum optics.In this thesis, we theoretically investigate the tunneling dynamics of a Bose-Einstein condensate confined in a triple-well potential (TWP), in the presence of an ac-driving. We focus the analysis on the phenomenon of Photon Assisted Tunneling (PAT), that take place between the non-central
wells of the TWP. PAT is a resonant process, originally studied in condensed matter physics in which periodic driving fields are implemented to control the transport of particles. We explore this phenomenon modeling both noninteracting and interacting regimes through a the Bose-Hubbard model and the Gross-Pitaevskii equation. Numerical simulations demonstrate how varying the amplitude and frequency of the driving field may drastically change the tunneling of atoms, either assisting or suppressing the tunneling. This leads to coherent population oscillations and regimes of quantum self-trapping. Very importantly, we show that PAT can enhance atomic tunneling under specific driving frequencies, resulting in tunneling rates well above the otherwise non-driven case.
Additionally, our study extends the analysis to open quantum systems with a TWP with balanced gain and loss, which exhibits PT-symmetry. We investigate how PAT enlarges the region of the parameter space with real spectrum. The results provide insights into quantum control strategies and shed light on potential applications in the fields of ultracold atoms and quantum optics
Using Timber in Mid-Rise and Tall Buildings to Construct Our Cities: A Science Mapping Study
No full textThe increase in population and urban migration has incentivized the construction of mid-rise and tall buildings. Despite the incremental rise in vertical construction, there are still investigation gaps related to high-rise buildings, such as carbon emissions and the use of low-carbon materials in tall structures. Timber presents a potential sustainable solution for mid-rise and tall buildings. The history of topics in timber building investigations began with the material characterization of innovation in construction technologies such as crosslaminated timber (CLT) and practical topics like construction collaboration, sustainability, engineering, and construction science. To identify potential topics and understand the research history of mid- and high-rise timber buildings, a bibliometric analysis is proposed.Therefore, this article aims to perform a bibliometric analysis with a science mapping technique to categorize and analyze the evolution of mid- and high-rise timber building research topics and identify the most relevant trends and current challenges. A co-occurrence keyword analysis was performed with the software SciMAT to analyze the evolution and actual trends of mid-rise and tall timber buildings. The results show an evolution in theinvestigation topics from timber frame elements to mass timber and CLT for high-rise buildings, which was expected due to the higher structural capacity of the mass timber product. Surprisingly, sustainability topics such as carbon emission and life-cycle analysis (LCA) were transversal in all periods with concrete as a recurrent keyword in the analysis. More specialized topics such as robustness, disproportioned collapse, perceptions, and attitude were observed in the final periods. Research projections indicate that for mid-rise and tall timber buildings, the environmental potential has to be aligned with the structural feasibility and perception of the construction’s actors and society to improve the carbon emissions reduction and support the increment of the population in an urban context