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Correction to: Short-Term Meteorological and Environmental Signals Recorded in a Firn Core from a High-Accumulation Site on Plateau Laclavere, Antarctic Peninsula (Geosciences, (2021), 11, 10, (428), 10.3390/geosciences11100428)
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Hoffmann-Abdi, Kirstin; Fernandoy, Francisco; Meyer, Hanno; Freitag, Johannes; Opel, Thomas; McConnell, Joseph R.; Schneider, Christoph
The authors would like to make the following corrections to the published article [1]. In Section 1, fourth paragraph: In the sentence “Proxy Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.” the word “Proxy” should be deleted as it occurs twice. The sentence should have read: “Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.”. In Section 3.4, second paragraph: In the sentence “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (m = 7.76).” the “m =” should be deleted before “7.76” and “, 8” should be inserted after “GMWL”. The sentence should have read: “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL, 8) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (7.76).”. In Section 4.5, first paragraph: In the sentence “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r > −0.6, p = 0; Table 5).” the “>” in the parenthesis should be replaced by “=”. The sentence should have read: “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r = −0.6, p = 0; Table 5).”. In the original publication, there was a mistake in Table 1 [1]. The order of the values in the column “Accumulation Rate (kg m−2 a−1)” was reversed for the years 2012 to 2015. The authors state that the scientific results for the accumulation rates in Table 1, which are presented and discussed in Sections 3.2 and 4.2 of the original publication, are not affected by this mistake, as all values were used correctly there. The corrected Table 1 is as follows: Annual accumulation rates calculated for the OH-12 drill site for the period 2012–2015. In the original publication, there was a mistake in Figure 6 [1]. The intercept in the equation for the δ18O−δD relationship of firn core OH-12 should be +6.01 and not −6.01. The corrected equation is δD = 7.94 × δ18O + 6.01. A correction was also made to the second paragraph in Section 3.4, where in the sentence “However, intercepts differ significantly (OH-12: −6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).” the intercept of the δ18O−δD relationship of firn core OH-12 should accordingly be +6.01 and not −6.01. In addition, in the same sentence the word “the” should be inserted before the word “intercepts”. The sentence should have read: ”However, the intercepts differ significantly (OH-12: +6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).”. The updated Figure 6 is as follows: (a) δ18O–δD relationship of all considered precipitation samples collected at Bernardo O’Higgins station (OH) between 2008 and 2017 (n = 294; coloured dots) compared to the δ18O–δD relationship of firn core OH-12 (n = 414; white dots). The Global Meteoric Water Line (GMWL) is indicated in blue. The Local Meteoric Water Line (LMWL) established for the study site by Fernandoy et al. [31,32] is shown as a dashed red line and the LMWL derived in this study as a solid red line. For each δ18O–δD relationship, the equation, the coefficient of determination (R2) and the p-value (p) are given. (b) Time series of δ18O, δD and d excess of OH-12 constructed based on the weighted age scale. High-resolution data are shown as light-coloured lines and monthly means as bold lines. The authors apologize for any inconvenience these mistakes may have caused the readers. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated. © 2023 by the authors.
Voltage Regulation Enhancement of DC-MG Based on Power Accumulator Battery Test System: MPC-Controlled Virtual Inertia Approach
(Institute of Electrical and Electronics Engineers Inc., 2022-01-01) Long, Bo; Zeng, Wei; Rodriguez, Jose; Guerrero, Josep M.; Chong, Kil To
In a DC-microgrid (DC-MG) composed of a power accumulator battery test system (PABTS), owing to the low inertia of DC capacitance, the charging and discharging of a PABTS can easily cause DC-link voltage fluctuations, which may jeopardize the system stability. Hence, a virtual inertia control (VIC) strategy is proposed to suppress these fluctuations and enhance the stability of the DC-MG. The VIC method is realized in a bidirectional grid-connected converter (BGCC), which combines VIC and model predictive control (MPC). The proposed method can provide inertia support during the transient state and enhance the dynamic characteristics of the DC-link voltage. A prediction model is established that uses the variation range of the DC-link voltage as the constraint, and the output of VIC as well as voltage deviations as optimization objectives. The desired DC-link current increment is calculated using the prediction model to change the input DC current reference of the VIC. To validate the effectiveness of the proposed method, hardware-in-the-loop (HIL) experiments are performed, and the results indicate that MPC-VIC is superior to the existing VIC methods in terms of inertia support and the DC-link voltage variation suppression of PABTS DC-MGs. © 2010-2012 IEEE.
On stochastic aspects of impact modeling of the innovation incentive system and business internationalization: evidence from Portuguese SMEs
(Taylor and Francis Ltd., 2024) Grilo L.M.; Pereira E.J; Maidana J.P.; Stehlík M.
Multivariate normal distribution is base for many statistical techniques, including ordinary least square inference. Here we show that in order to make research on Internationalization of Companies, more flexible approach is needed, namely partial least squares (PLS). It is a nonparametric technique, used in Structural Equation Modeling (SEM), which makes no distributional assumptions and also may be applied with small sample sizes. In this study we discuss on regularity conditions for PLS from the perspective of semi-continuous covariance which fills the gap in the current studies. The stochastic aspects, especially those related to usage of PLS-SEM, can be well integrated to the topologically grounded regression, where jumps in the covariances can occur. The purpose of the research is to analyze and understand the impact of the Incentive System (IS) for Innovation, within the scope of the National Strategic Reference Framework (QREN) 2014-2020, on the Internationalization of Portuguese Small and Medium Enterprises (SMEs). We study stochastic aspects of theoretical model which aggregates the variables Product Innovation, Marketing Innovation, Organizational Innovation and Working Conditions as determinants of Internationalization of Companies. Data were collected based on a quantitative methodology, through a self-completion questionnaire using the Likert psychometric scale, which registered 120 participants. Organizational Innovation (exogenous latent construct) and Product Innovation have shown a statistically significant indirect effect on the Internationalization of Companies (endogenous latent construct) through Marketing Innovation. The latter has a direct effect on the Internationalization (target construct). However, Working Conditions has the greatest impact on Internationalization, meaning that measures such as increasing wages, decreasing the use of temporary work and precarious work conversion into labor effective relations have a very relevant direct effect on the Internationalization of Portuguese SMEs. © 2023 The Author(s). Published with license by Taylor & Francis Group, LLC.
School Greenness and Student-Level Academic Performance: Evidence From the Global South
(John Wiley and Sons Inc, 2023-08) Jimenez, Raquel B; Bozigar, Matthew; Janulewicz, Patricia; Lane, Kevin J.; Hutyra, Lucy R.; Fabian, M. Patricia
Greenspace in schools might enhance students' academic performance. However, the literature—dominated by ecological studies at the school level in countries from the Northern Hemisphere—presents mixed evidence of a beneficial association. We evaluated the association between school greenness and student-level academic performance in Santiago, Chile, a capital city of the Global South. This cross-sectional study included 281,695 fourth-grade students attending 1,498 public, charter, and private schools in Santiago city between 2014 and 2018. Student-level academic performance was assessed using standardized test scores and indicators of attainment of learning standards in mathematics and reading. School greenness was estimated using Normalized Difference Vegetation Index (NDVI). Linear and generalized linear mixed-effects models were fit to evaluate associations, adjusting for individual- and school-level sociodemographic factors. Analyses were stratified by school type. In fully adjusted models, a 0.1 increase in school greenness was associated with higher test scores in mathematics (36.9 points, 95% CI: 2.49; 4.88) and in reading (1.84 points, 95% CI: 0.73; 2.95); as well as with higher odds of attaining learning standards in mathematics (OR: 1.20, 95% CI: 1.12; 1.28) and reading (OR: 1.07, 95% CI: 1.02; 1.13). Stratified analysis showed differences by school type, with associations of greater magnitude and strength for students attending public schools. No significant associations were detected for students in private schools. Higher school greenness was associated with improved individual-level academic outcomes among elementary-aged students in a capital city in South America. Our results highlight the potential of greenness in the school environment to moderate educational and environmental inequalities in urban areas. © 2023 The Authors. GeoHealth published by Wiley Periodicals LLC on behalf of American Geophysical Union.
Distributed Predictive Secondary Control for Imbalance Sharing in AC Microgrids
(Institute of Electrical and Electronics Engineers Inc., 2022-01-01) Navas-Fonseca, Alex; Burgos-Mellado, Claudio; Gomez, Juan S.; Donoso, Felipe; Tarisciotti, Luca; Saez, Doris; Cardenas, Roberto; Sumner, Mark
This paper proposes a distributed predictive secondary control strategy to share imbalance in three-phase, three-wire isolated AC Microgrids. The control is based on a novel approach where the imbalance sharing among distributed generators is controlled through the control of single-phase reactive power. The main characteristic of the proposed methodology is the inclusion of an objective function and dynamic models as constraints in the formulation. The controller relies on local measurements and information from neighboring distributed generators, and it performs the desired control action based on a constrained cost function minimization. The proposed distributed model predictive control scheme has several advantages over solutions based on virtual impedance loops or based on the inclusion of extra power converters for managing single-phase reactive power among distributed generators. In fact, with the proposed technique the sharing of imbalance is performed directly in terms of single-phase reactive power and without the need for adding extra power converters into the microgrid. Contrary to almost all reported works in this area, the proposed approach enables the control of various microgrid parameters within predefined bands, providing a more flexible control system. Extensive simulation and Hardware in the Loop studies verify the performance of the proposed control scheme. Moreover, the controller's scalability and a comparison study, in terms of performance, with the virtual impedance approach were carried out. © 2010-2012 IEEE.
An Asymmetric Switched-Capacitor Multicell Inverter With Low Number of DC Source and Voltage Stress for Renewable Energy Sources
(Institute of Electrical and Electronics Engineers Inc., 2022) Hosseinzadeh, Mohammad Ali; Sarebanzadeh, Maryam; Garcia, Cristian F.; Babaei, Ebrahim; Rodriguez, Jose
Asymmetric multilevel inverters generate high-quality output voltage using the same number of components as symmetric multilevel inverters. The main drawback of these topologies is that they require many DC voltage sources, and the power switches must endure high voltage stress. In this paper, a switched-capacitor sub-module inverter topology is proposed to reduce the number of DC voltage sources and the voltage stress on the switches of asymmetric multilevel inverters. The proposed sub-module inverter can generate 15 voltage levels by using two DC power supplies and a capacitor. The voltage of the capacitor can be automatically charged at half of the input DC power supply without the need for any sensors. In addition, the capacitor charging operation does not produce an inrush current because it is charged by the direction of the output current; this is an advantage over switched capacitor multilevel inverters. A modular topology is also presented based on the proposed sub-module inverter to achieve high voltage levels while reducing the number of elements. A comprehensive comparison between the proposal and other multilevel inverter topologies is performed to validate the design of the proposed inverter. In addition, thermal and loss distribution simulations of the proposed sub-module inverter are performed. Finally, the performance, efficiency, and accuracy of the proposed inverter are confirmed through laboratory prototyping. © 2013 IEEE.
Quality of automatic geocoding tools: a study using addresses from hospital record files in Temuco, Chile
(Fundacao Oswaldo Cruz, 2022) Quinteros, Maria Elisa; Blazquez, Carola; Rosas, Felipe; Ayala, Salvador; Ossa García, Ximena Marcela; Delgado-Saborit, Juana Maria; Harrison, Roy M.; Ruiz-Rudolph, Pablo; Yohannessen, Karla
Automatic geocoding methods have become popular in recent years, facilitating the study of the association between health outcomes and the place of living. However, rather few studies have evaluated geocoding quality, with most of them being performed in the US and Europe. This article aims to compare the quality of three automatic online geocoding tools against a reference method. A subsample of 300 handwritten addresses from hospital records was geocoded using Bing, Google Earth, and Google Maps. Match rates were higher (> 80%) for Google Maps and Google Earth compared with Bing. However, the accuracy of the addresses was better for Bing with a larger proportion (> 70%) of addresses with positional errors below 20m. Generally, performance did not vary for each method for different socioeconomic status. Overall, the methods showed an acceptable, but heterogeneous performance, which may be a warning against the use of automatic methods without assessing quality in other municipalities, particularly in Chile and Latin America. © 2022 Fundacao Oswaldo Cruz. All rights reserved.
Rainfall-Induced Landslide Assessment under Different Precipitation Thresholds Using Remote Sensing Data: A Central Andes Case
(Multidisciplinary Digital Publishing Institute (MDPI), 2023-07) Maragaño-Carmona, Gonzalo; Fustos Toribio, Ivo J.; Descote, Pierre-Yves; Robledo, Luis F.; Villalobos, Diego; Gatica, Gustavo
The determination of susceptibility to rainfall-induced landslides is crucial in developing a robust Landslide Early Warning System (LEWS). With the potential uncertainty of susceptibility changes in mountain environments due to different precipitation thresholds related to climate change, it becomes important to evaluate these changes. In this study, we employed a machine learning approach (logistic models) to assess susceptibility changes to landslides in the Central Andes. We integrated geomorphological features such as slope and slope curvature, and precipitation data on different days before the landslide. We then split the data into a calibration and validation database in a 50/50% ratio, respectively. The results showed an area under the curve (AUC) performance of over 0.790, indicating the model’s capacity to represent prone-landslide changes based on geomorphological and precipitation antecedents. We further evaluated susceptibility changes using different precipitation scenarios by integrating Intensity/Duration/Frequency (IDF) products based on CHIRPS data. We concluded that this methodology could be implemented as a Rainfall-Induced Landslides Early Warning System (RILEWS) to forecast RIL occurrence zones and constrain precipitation thresholds. Our study estimates that half of the basin area in the study zone showed a 59% landslide probability for a return of two years at four hours. Given the extent and high population in the area, authorities must increase monitoring over unstable slopes or generate landslide early warning at an operational scale to improve risk management. We encourage decision-makers to focus on better understanding and analysing short-duration extreme events, and future urbanization and public infrastructure designs must consider RIL impact. © 2023 by the authors.
Fast Solver for Implicit Continuous Set Model Predictive Control of Electric Drives
(Institute of Electrical and Electronics Engineers Inc., 2022) Favato, Andrea; Carlet, Paolo Gherardo; Toso, Francesco; Torchio, Riccardo; Ortombina, Ludovico; Bruschetta, Mattia; Carli, Ruggero; Alotto, Piergiorgio; Bolognani, Silverio; Rodriguez, Jose
This paper proposes a fast and accurate solver for implicit Continuous Set Model Predictive Control for the current control loop of synchronous motor drives with input constraints, allowing for reaching the maximum voltage feasible set. The related control problem requires an iterative solver to find the optimal solution. The real-time certification of the algorithm is of paramount importance to move the technology toward industrial-scale applications. A relevant feature of the proposed solver is that the total number of operations can be computed in the worst-case scenario. Thus, the maximum computational time is known a priori. The solver is deeply illustrated, showing its feasibility for real-time applications in the microseconds range by means of experimental tests. The proposed method outperforms general-purpose algorithms in terms of computation time, while keeping the same accuracy. © 2013 IEEE.
Sensitivity of Simulated Conditions to Different Parameterization Choices Over Complex Terrain in Central Chile
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-01) Arévalo, Jorge; Marín, Julio C.; Díaz, Mailiu; Raga, Graciela; Pozo, Diana; Córdova, Ana María; Baumgardner, Darrel
This study evaluates the performance of fourteen high-resolution WRF runs with different combinations of parameterizations in simulating the atmospheric conditions over the complex terrain of central Chile during austral winter and spring. We focus on the validation of results for coastal, interior valleys, and mountainous areas independently, and also present an in-depth analysis of two synoptic-scale events that occurred during the study period: a frontal system and a cut-off low. The performance of the simulations decreases from the coast to higher altitudes, even though the differences are not very clear between the coast and interior valleys for 10 m wind speeds and precipitation. The simulated vertical profiles show a warmer and drier boundary layer and a cooler and moister free atmosphere than observed. The choice of the land-surface model has the largest positive impact on near-surface variables with the five-layer thermal diffusion scheme showing the smallest errors. Precipitation is more sensitive to the choice of cumulus parameterizations, with the simplified Arakawa–Schubert scheme generally providing the best performance for absolute errors. When examining the performance of the model simulating rain/no-rain events for different thresholds, also the cumulus parameterizations better represented the false alarm ratio (FAR) and the bias score (BS). However, the Morrison microphysics scheme resulted in the best critical success index (CSI), while the probability of detection (POD) was better in the simulation without analysis nudging. Overall, these results provide guidance to other researchers and help to identify the best WRF configuration for a specific research or operational goal. © 2023 by the authors.
Recognition and conversion of electric field representations: The case of electric field lines
(American Physical Society, 2023-07) Campos, Esmeralda; Zuza, Kristina; Guisasola, Jenaro; Zavala, Genaro
We conducted a study with introductory and upper-division physics students in a Mexican university to learn how students independently recognize the electric field’s main characteristics in the electric field lines diagram and as a source or target representation in conversion processes. We used the theory of registers of semiotic representations and a phenomenographic approach as a framework to analyze data. The recognition and conversion abilities were explored through interpretation and construction tasks. We identified students’ main difficulties in recognition and conversion in the interpretation and construction tasks. In conversion processes, we found that when the electric field lines diagram is the source representation, students do not interpret the field lines’ density as the magnitude of the electric field. The difficulties of interpretation that arise in these conversion processes depend partially on the target representation. We also found that constructing electric field lines is especially difficult for students at both introductory and upper-division levels. Most students would prefer to draw vector field plots instead. We recommend that electricity and magnetism teachers and researchers be aware of the difficulties that the recognition and conversion in interpretation and construction tasks may represent for their students in understanding the electric field concept. © Published by the American Physical Society.
Using vertical areas in finite set model predictive control of a three-level inverter aimed at computation reduction
(Turkiye Klinikleri, 2022) Ja’Afari, Alireza; Davari, S. Alireza; Garcia, Cristian; Rodriguez, Jose
In power electronics applications, finite set model predictive control (FS-MPC) has proven to be a viable strategy. However, due to the high processing power required, using this technology in multilevel converters is difficult. This strategy, which is based on predicting the behavior of the system for all conceivable states, has an issue with a numerous of possible switching states. A recent and useful strategy for dealing with the problem is the limiting of calculations based on triangle regions. Despite its success, this method has several limitations, including the computation required to locate the right triangle and the boundary modes. In this research, the vertical areas are used for the limiting of calculations. Not only determining the right zone is an easy task with this strategy, but the number of possible candidates is also reduced to two. Furthermore, the boundary mode will not occur. In the proposed method, two key advantages can be seen in the discussion of reduction of calculations: (1) new zoning, which eliminates the calculations related to the slope of the lines. (2) The number of options placed in the cost function has been reduced to 2 candidates. Simulations are used to validate the approach, which is applied to a three-level neutral point clamped (NPC) inverter. © 2022 Turkiye Klinikleri. All rights reserved.
Procedimiento de agrupación de estudiantes según riesgo de abandono para mejorar la gestión estudiantil en educación superior
(Lundiana, 2022) Hinojosa, Mauricio; Derpich, Iván; Alfaro, Miguel; Ruete, David; Caroca, Alejandro; Gatica, Gustavo
The complex problem of student dropout represents an opportunity for the application of data mining technology and methods in higher education. The objective of this research is to obtain the profile of students at risk of dropping out and thus generate student management plans that impact on the variables that explain this situation. For this, it is proposed to use a CRISP-DM methodological structure, applying statistical tools and unsupervised machine learning. The cross-sectional analysis was carried out on a universe of freshmen day students at a private Chilean university. The sociodemographic and behavioural variables used were based on attrition theory and expert judgment, and the data were obtained from the historical records available at the Institution. To obtain the variables that most influenced dropout, correlation and principal component analyses were performed. The application of agglomerative hierarchical clustering and rough sets technique produced four profiles of students with their respective association rules and five academic variables that allowed the design of a support system to reduce dropout and promote retention. © 2022 Universidade Federal de Minas Gerais. All rights reserved.
Analytical Calculation of Harmonics and Harmonic Losses in Five-Phase Carrier-Based PWM Voltage Source Inverters
(Institute of Electrical and Electronics Engineers Inc., 2022) Hamedani, Pegah; Garcia, Cristian; Rodriguez, Jose
The main purpose of this paper is to analyze a five-phase Voltage Source Inverter (VSI) that is operated with the Pulse Width Modulation (PWM) switching technique. Double Fourier integral (DFI) analysis has been used to extract the harmonics of the line-to-line voltages. Moreover, the harmonic current ripple has been calculated for an effective inductive five-phase load with a regular pentagon connection. Correspondingly, a new closed-form solution for calculating the harmonic losses in five-phase VSIs has been derived. In addition, a new equation for the weighted total harmonic distortion (WTHD) index has been extracted for five-phase VSIs. To validate the suggested analytical solutions (i.e., harmonic losses and WTHD equations), the results are compared with the DFI calculation method and the method of applying the fast Fourier transform (FFT) to a simulated waveform. The results show that the proposed analytical method has high accuracy and requires less mathematical effort, especially at high-frequency ratio values. Finally, the study includes simulation results and the implementation of an experimental setup. © 2013 IEEE.
Innovative use of micronized biomass silica-GGBS as agro-industrial by-products for the production of a sustainable high-strength geopolymer concrete
(Elsevier Ltd, 2023-07) Jayanthi V; Avudaiappan, Siva; Amran, Mugahed; Arunachalam, Krishna Prakash; Qader, Diyar N.; Delgado, Manuel Chávez; Saavedra Flores, Erick I.; Rashid, Raizal S.M.
Micronized biomass silica (MBS) and ground granulated blast furnace slag (GGBS) are agro-industrial byproducts generated by incinerating of rice husk (grinding in jar mill) and blast furnaces that used produce iron, respectively. MBS accounts for 20% of the world's total paddy output of 590 million tons. These by-products (MBS and GGBS) have a high concentration of amorphous silica, which is utilized as a mineral additive in concrete. This amorphous silica interacts with hydration products, resulting in the formation of additional CSH gel. This improves concrete's strength and durability properties. Therefore, it is proven that inclusion of agro-industrial by-products in concrete helps to promote sustainable and greener development, which in turn reduces carbon footprints and waste that must be disposed of in landfills. There have been few investigations on concrete using MBS and demonstrated the great potential of employing MBS as a cement substitute or additive in normal concrete. Also, the utilization of MBS as partial replace to GGBS in geopolymer concrete (GPC) with different molarity is a novel aspect of this study. However, this study has the aim and limit to develop a high-strength eco-friendly GPC with agro-industrial byproducts (MBS and GGBS) for use in sustainable construction. The impact of incorporating MBS as a partial replacement of GGBS on compressive and split tensile strengths, sorptivity, and chloride permeability was tested up to the age of 28 days. MBS was used to replace GGBS in varying percentages in the preparation of concretes. MBS were used in concrete at 0%, 10%, 20%, and 30% replacement by weight. It was discovered that a GPC combination containing MBS 20% and the balance GGBS as the binder had the best performance in terms of its strength and durability. The compressive strengths of all GPC mixtures exceeded the intended design strength. The main findings of this study demonstrated clearly that MBS may be employed as a binder in the production of GPC. © 2023 The Authors
Fall Risk Classification Using Trunk Movement Patterns from Inertial Measurement Units and Mini-BESTest in Community-Dwelling Older Adults: A Deep Learning Approach
(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Robles Cruz, Diego; Puebla Quiñones, Sebastián; Lira Belmar, Andrea; Quintana Figueroa, Denisse; Reyes Hidalgo, María; Taramasco Toro, Carla
Falls among older adults represent a critical global public health problem, as they are one of the main causes of disability in this age group. We have developed an automated approach to identifying fall risk using low-cost, accessible technology. Trunk movement patterns were collected from 181 older people, with and without a history of falls, during the execution of the Mini-BESTest. Data were captured using smartphone sensors (an accelerometer, a gyroscope, and a magnetometer) and classified based on fall history using deep learning algorithms (LSTM). The classification model achieved an overall accuracy of 88.55% a precision of 90.14%, a recall of 87.93%, and an F1 score of 89.02% by combining all signals from the Mini-BESTest tasks. The performance outperformed the metrics we obtained from individual tasks, demonstrating that aggregating all cues provides a more complete and robust assessment of fall risk in older adults. The results suggest that combining signals from multiple tasks allowed the model to better capture the complexities of postural control and dynamic gait, leading to better prediction of falls. This highlights the potential of integrating multiple assessment modalities for more effective fall risk monitoring.
Comparison of Faster R-CNN, YOLO, and SSD for Third Molar Angle Detection in Dental Panoramic X-rays
(Multidisciplinary Digital Publishing Institute (MDPI), 2024-09) Vilcapoma, Piero; Parra Meléndez, Diana; Fernández, Alejandra; Vásconez, Ingrid Nicole; Hillmann, Nicolás Corona; Gatica, Gustavo; Vásconez, Juan Pablo
The use of artificial intelligence algorithms (AI) has gained importance for dental applications in recent years. Analyzing AI information from different sensor data such as images or panoramic radiographs (panoramic X-rays) can help to improve medical decisions and achieve early diagnosis of different dental pathologies. In particular, the use of deep learning (DL) techniques based on convolutional neural networks (CNNs) has obtained promising results in dental applications based on images, in which approaches based on classification, detection, and segmentation are being studied with growing interest. However, there are still several challenges to be tackled, such as the data quality and quantity, the variability among categories, and the analysis of the possible bias and variance associated with each dataset distribution. This study aims to compare the performance of three deep learning object detection models—Faster R-CNN, YOLO V2, and SSD—using different ResNet architectures (ResNet-18, ResNet-50, and ResNet-101) as feature extractors for detecting and classifying third molar angles in panoramic X-rays according to Winter’s classification criterion. Each object detection architecture was trained, calibrated, validated, and tested with three different feature extraction CNNs which are ResNet-18, ResNet-50, and ResNet-101, which were the networks that best fit our dataset distribution. Based on such detection networks, we detect four different categories of angles in third molars using panoramic X-rays by using Winter’s classification criterion. This criterion characterizes the third molar’s position relative to the second molar’s longitudinal axis. The detected categories for the third molars are distoangular, vertical, mesioangular, and horizontal. For training, we used a total of 644 panoramic X-rays. The results obtained in the testing dataset reached up to 99% mean average accuracy performance, demonstrating the YOLOV2 obtained higher effectiveness in solving the third molar angle detection problem. These results demonstrate that the use of CNNs for object detection in panoramic radiographs represents a promising solution in dental applications.
Breaking the Ring of Fire: How Ridge Collision, Slab Age, and Convergence Rate Narrowed and Terminated the Antarctic Continental Arc
(John Wiley and Sons Inc, 2023-05) Burton-Johnson, Alex; Bastias, Joaquin; Kraus, Stefan
The geometry of the Antarctic-Phoenix Plate system, with the Antarctic Plate forming both the overriding plate and the conjugate to the subducting oceanic plate, allows quantification of slab age and convergence rate back to the Paleocene and direct comparison with the associated magmatic arc. New Ar-Ar data from Cape Melville (South Shetland Islands, SSI) and collated geochronology shows Antarctic arc magmatism ceased at ∼19 Ma. Since the Cretaceous, the arc front remained ∼100 km from the trench whilst its rear migrated trenchward at 6 km/Myr. South of the SSI, arc magmatism ceased ∼8–5 Myr prior to each ridge-trench collision, whilst on the SSI (where no collision occurred) the end of arc magmatism predates the end of subduction by ∼16 Myr. Despite the narrowing and successive cessation of the arc, geochemical and dyke orientation data shows the arc remained in a consistently transitional state of compressional continental arc and extensional backarc tectonics. Numerically relating slab age, convergence rate, and slab dip to the Antarctic-Phoenix Plate system, we conclude that the narrowing of the arc and the cessation of magmatism south of the SSI was primarily in response to the subduction of progressively younger oceanic crust, and secondarily to the decreasing convergence rate. Increased slab dip beneath the SSI migrated the final magmatism offshore. Comparable changes in the geometry and composition are observed on the Andean arc, suggesting slab age and convergence rate may affect magmatic arc geometry and composition in settings currently attributed to slab dip variation. © Wiley Periodicals LLC. The Authors.
Desafíos en la vigilancia de todos los casos de cáncer en Chile: Registro Nacional de Cáncer
(Medwave Estudios Ltda, 2024-01) Taramasco, Carla; Rimassa, Carla; Acevedo, Johana
El cáncer causa millones de muertes a nivel mundial por lo que su registro es fundamental, existiendo registros clínicos, hospitalarios y poblacionales. Estos últimos son el estándar de oro para la información sobre incidencia y supervivencia de cáncer en una región definida. En Chile se cuenta con cinco registros poblacionales ubicados en ciertas zonas del país. El Registro Nacional del Cáncer chileno surge como un desafío para conformar una herramienta transversal a los tres tipos de registro con la finalidad de, al menos, conocer la cantidad de casos por tipo de cáncer. Su diseño implicó un despliegue de acciones orientadas a lograr consensos entre diversos actores respecto de la información, validación y eventos necesarios de registrar. Se identificaron cuatro etapas en el proceso de atención y el registro: sospecha de diagnóstico, confirmación morfológica (biopsia), resolución clínica (comité oncológico incluyendo la indicación de tratamiento), tratamiento y seguimiento oncológico. A su vez, el desarrollo de la plataforma (años 2018 a 2021) implicó levantamiento de información y acuerdos sobre los requerimientos para el co-diseño del registro, incluyendo un exitoso pilotaje con más de 20 establecimientos de salud del sector público y privado con registro de cerca de 7500 casos de cáncer. El despliegue y uso del Registro Nacional de Cáncer a nivel nacional depende de la autoridad sanitaria. Se trata de un sistema de información que recolecta, almacena, procesa y analiza de forma continua y sistemática datos sobre todos los casos y tipos de cánceres que ocurren en el país. En este trabajo se presenta el diseño y desarrollo de la herramienta, los desafíos abordados, sus fortalezas y debilidades.
Applying the Delphi method with early-career researchers to explore a genderissues agenda in STEM education
(Modestum LTD, 2022) Hernandez-Martinez, Paul; Dominguez, Angeles; Zavala, Genaro; Kambouri, Maria; Zubieta, Judith; Clark, Robin
The Delphi method (DM) was initially conceived as a forecasting technique whose results are based on the consensus of a panel of experts. It has been used in many fields, assisting researchers, policymakers, and others in setting directions and future agendas. This study presents an application of the DM, with a broader interpretation of the notion of “expert” as a qualitative tool to explore gender issues in science, technology, engineering, and mathematics (STEM) education. Its aim is to analyze the use of the DM as a technique to achieve agreement among a group of early-career researchers from the UK and Mexico, who are not considered “experts” in the traditional sense. The other aim was to explore the advantages and disadvantages of using the DM in this context. We used three stages to collect information and reach a consensus. The first two were online activities, and the last consisted of a five-day face-to-face workshop. In the first stage, participants sent research questions, and organizers categorized them into themes. Participants responded to a survey ranking all research questions in the second stage. In the last, organizers analyzed the highest scored questions and arranged them into research topics in which participants worked on research proposals. The DM worked successfully with this group of participants by combining their interest in the field and engagement with the activities. The research strands and proposals of using this method are usable. The method used in this paper can serve as a model to develop research graduate courses to develop students’ skills © 2022 by the authors; licensee Modestum. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution License

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