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This paper presents a simplified and straightforward method for determining optimal beach profile spacing from an economic point of view with an admissible error. This error can be computed theoretically by comparing different profile spacings from two consecutive bathymetries. When a beach sediment budget (from previous monitoring surveys) or the volume density of a beach nourishment project is known, a virtual bathymetry can be designed; therefore, a unique real bathymetry would be needed. The method is applied and analysed for beaches with different characteristics regarding tide, energy, morphology and natural features. The results indicate that the estimated errors are proportional to a beach heterogeneity factor, depending on each particular beach case, such that large spacings do not necessarily induce large errors. In our case, profile spacings of 100 m induce average errors of less than 5%. Moreover, differences in tidal range and the existence of rocky reefs do not seem to affect the results.

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Abstract Background There is a lack of studies evaluating longitudinal changes in adiposity indicators and the association with 24-hour movement behavior guidelines in preschoolers. Therefore, this study aimed to investigate associations between changes in Body Mass Index (BMI) z-scores, waist circumference and waist-to-height ratio, and compliance with the 24-hour movement behavior guidelines in three- to six-year-old children from a European sample. Methods In total, data from a European sample of 719 preschoolers (50.9% boys, 4.76 ± 0.45 years) were analyzed at baseline and one year later. Physical activity (steps/day) was objectively measured using Omron pedometers. Screen time and sleep duration were subjectively measured using a parental questionnaire. Height, weight and waist circumference were measured by well-trained researchers, using standardized procedures and equipment, and were used to calculate BMI z-score and waist-to-height ratio. Linear mixed-effects models were used to investigate associations between changes in adiposity indicators (BMI z-score, waist circumference and waist-to-height ratio) and compliance with 24-hour movement behavior guidelines. Results BMI z-scores changed differently from baseline to follow-up according to compliance with the integrated guidelines, both for weekdays (effect estimate = -0.15, p = 0.001) and weekend days (effect estimate = -0.12, p = 0.046). Preschoolers who did not comply with the integrated guidelines showed a small, significant increase in BMI z-scores compared to compliers having no significant change in BMI z-score. No significant difference between both groups over time was found for waist circumference and waist-to-height ratio neither for weekdays nor weekend days. Conclusions The change in BMI z-scores after one year is less optimal for preschoolers who do not comply with the 24-hour movement behavior guidelines compared to preschoolers who comply with the integrated guidelines, although not clinically relevant. Future studies should incorporate longer follow-up periods to observe the effects of compliance to the integrated guidelines on adiposity indicators in preschool children.

Today, it is of vital importance to research actuators and its control to harness their advantages, such as the force-to-weight ratio of the actuator or its energy consumption, in a more efficient way. For this reason, this work describes the characterization and control of actuators based on Shape Memory Alloy wires with different diameters ranging from 0.5 to 2 mm. These Nickel Titanium wires contract in length when heated, which makes them a distinguishing property compared to other alloys. This contraction is used to apply force so that it can be used in applications such as moving objects, controlling valves, or designing exoskeletons, among others. In this context, the objective of this work is to characterize Shape Memory Alloy wires of varying diameters, ranging from 0.5 mm to 2 mm, which are capable of lifting loads exceeding 100 kg with a single wire, while maintaining controlled positioning. Among the parameters to be highlighted are cooling and heating times, speed, energy consumption, breaking limits, and duty cycles. Additionally, various heating methods for Shape Memory Alloys wires are analyzed: direct heating by Joule effect and external heating. The results obtained with the proposed control strategy for steady-state position control (when the output remains within ±5% of the final value) were as follows: RMSE of 0.0401% for the one-way 0.51 mm wire, 0.0483% for the two-way 0.51 mm wire, 0.289% for the 1 mm wire, and 0.0857% for the 2 mm wire.

The major contribution of this study is the feedback design of a finite-time convergence sliding mode control to solve the trajectory-tracking problem in a class of mechanical systems. Some advantages are that the controller presents a continuous signal by integration of the high-frequency switching term. Another benefit is the design and implementation of an uncertainty and disturbance estimator (UDE) to robustify the closed-loop system. We use Lyapunov tools to develop the closed-loop stability analysis and to give an expression of the convergence time t = t through this, we can reduce the convergence time by tuning the gains of the controller. We illustrate the performance of the proposed control structure via numerical simulations conducted for a mass-spring-damper system and experiments developed in a pendular system.

La lamivudina es uno de los medicamentos más prescritos en el mundo, se utiliza para tratar la inmunodeficiencia humana y la hepatitis B. El objetivo del estudio fue evaluar los atributos de calidad y comparar los perfiles de disolución de dos lotes (A y B) del medicamento genérico lamivudina 150 mg tabletas con el medicamento innovador Epivir 150 mg tabletas. Se realizó un estudio analítico, experimental y de corte transversal, se usó un método espectrofotométrico a una longitud de onda de máxima absorción (λ) correspondiente a 270 nm, para medir el porcentaje de fármaco disuelto. El estudio evaluó identificación, contenido, disolución y uniformidad de masas. Se usó el aparato 2 USP (Paleta) 75 rpm, 900 mL de medio de disolución (37 ± 0,5 °C) a en tres medios de disolución: pH 1,2; 4,5 y 6,8. Se retiraron muestras de 5 mL a los 5, 10, 15, 20 y 30 min. Se encontró que ambos lotes de lamivudina genérico (A y B) presentan el mismo perfil cinético de disolución que el medicamento innovador. Ambas formulaciones cumplen con el criterio de medicamentos de disolución muy rápida (85% disuelto en 15 min), y de disolución rápida (85% disuelto en 30 min). Por lo tanto, no fue necesario calcular el factor de similitud. Se concluye que los medicamentos genéricos A y B son equivalentes in vitro con el medicamento innovador Epivir.

Abstract Childhood obesity is a complex disorder that appears to be influenced by an interacting system of many factors. Taking this complexity into account, we aim to investigate the causal structure underlying childhood obesity. Our focus is on identifying potential early, direct or indirect, causes of obesity which may be promising targets for prevention strategies. Using a causal discovery algorithm, we estimate a cohort causal graph (CCG) over the life course from childhood to adolescence. We adapt a popular method, the so-called PC-algorithm, to deal with missing values by multiple imputation, with mixed discrete and continuous variables, and that takes background knowledge such as the time-structure of cohort data into account. The algorithm is then applied to learn the causal structure among 51 variables including obesity, early life factors, diet, lifestyle, insulin resistance, puberty stage and cultural background of 5112 children from the European IDEFICS/I.Family cohort across three waves (2007–2014). The robustness of the learned causal structure is addressed in a series of alternative and sensitivity analyses; in particular, we use bootstrap resamples to assess the stability of aspects of the learned CCG. Our results suggest some but only indirect possible causal paths from early modifiable risk factors, such as audio-visual media consumption and physical activity, to obesity (measured by age- and sex-adjusted BMI z-scores) 6 years later.

Motion primitives are a highly useful and widely employed tool in the field of Learning from Demonstration (LfD). However, obtaining a large number of motion primitives can be a tedious process, as they typically need to be generated individually for each task to be learned. To address this challenge, this work presents an algorithm for acquiring robotic skills through automatic and unsupervised segmentation. The algorithm divides tasks into simpler subtasks and generates motion primitive libraries that group common subtasks for use in subsequent learning processes. Our algorithm is based on an initial segmentation step using a heuristic method, followed by probabilistic clustering with Gaussian Mixture Models. Once the segments are obtained, they are grouped using Gaussian Optimal Transport on the Gaussian Processes (GPs) of each segment group, comparing their similarities through the energy cost of transforming one GP into another. This process requires no prior knowledge, it is entirely autonomous, and supports multimodal information. The algorithm enables generating trajectories suitable for robotic tasks, establishing simple primitives that encapsulate the structure of the movements to be performed. Its effectiveness has been validated in manipulation tasks with a real robot, as well as through comparisons with state-of-the-art algorithms.