A catalog of validity indices for step counting wearable technologies during treadmill walking: the CADENCE‑adults study

Background: Standardized validation indices (i.e., accuracy, bias, and precision) provide a comprehensive comparison of step counting wearable technologies. Purpose: To expand a previously published child/youth catalog of validity indices to include adults (21–40, 41–60 and 61–85 years of age) assessed across a range of treadmill speeds (slow [0.8–3.2 km/h], normal [4.0–6.4 km/h], fast [7.2–8.0 km/h]) and device wear locations (ankle, thigh, waist, and wrist). Methods: Two hundred fifty-eight adults (52.5 ± 18.7 years, 49.6% female) participated in this laboratory-based study and performed a series of 5-min treadmill bouts while wearing multiple devices; 21 devices in total were evaluated over the course of this multi-year cross-sectional study (2015–2019). The criterion measure was directly observed steps. Computed validity indices included accuracy (mean absolute percentage error, MAPE), bias (mean percentage error, MPE), and precision (correlation coefficient, r; standard deviation, SD; coefficient of variation, CoV). Results: Over the range of normal speeds, 15 devices (Actical, waist-worn ActiGraph GT9X, activPAL, Apple Watch Series 1, Fitbit Ionic, Fitbit One, Fitbit Zip, Garmin vivoactive 3, Garmin vivofit 3, waist-worn GENEActiv, NL-1000, PiezoRx, Samsung Gear Fit2, Samsung Gear Fit2 Pro, and StepWatch) performed at < 5% MAPE. The wrist-worn Acti‑ Graph GT9X displayed the worst accuracy across normal speeds (MAPE = 52%). On average, accuracy was compromised across slow walking speeds for all wearable technologies (MAPE = 40%) while all performed best across normal speeds (MAPE = 7%). When analyzing the data by wear locations, the ankle and thigh demonstrated the best accuracy (both MAPE = 1%), followed by the waist (3%) and the wrist (15%) across normal speeds. There were significant effects of speed, wear location, and age group on accuracy and bias (both p < 0.001) and precision (p ≤ 0.045). Conclusions: Standardized validation indices cataloged by speed, wear location, and age group across the adult lifespan facilitate selecting, evaluating, or comparing performance of step counting wearable technologies. Speed, wear location, and age displayed a significant effect on accuracy, bias, and precision. Overall, reduced performance was associated with very slow walking speeds (0.8 to 3.2 km/h). Ankle- and thigh-located devices logged the highest accuracy, while those located at the wrist reported the worst accuracy.United States Department of Health & Human Services National Institutes of Health (NIH) - USA NIH National Institute on Aging (NIA) 5R01AG04902

Diferencias en las amplitudes articulares entre varones y mujeres en edad escolar

Introducción: En el presente estudio se han analizado las diferencias existentes entre hombres y mujeres, en relación a la amplitud articular a lo largo de la vida del escolar. Métodos: Se analiza una población de 420 alumnos y alumnas, con edades comprendidas entre los 7 y los 17 años (Educación Primaria y Educación Secundaria Obligatoria). El estudio, se realiza mediante la aplicación de una batería de tests de valoración de la flexibilidad por medio de mediciones goniométricas. Esta batería consta de 10 pruebas, de las que se extraen datos relativos a la movilidad articular de hombros, cadera, rodilla y tobillos. Resultados: Los resultados obtenidos indican que la amplitud articular de los sujetos estudiados disminuye con la edad. Asimismo estos resultados son mejores en las mujeres que en los hombres, con diferencias significativas en tres de las pruebas incluidas en el test. Los picos de acortamientos varían en función del sexo del sujeto

Low-Coherence Interferometry Using Microwave Photonics for Multilayered Samples

[EN] A photonic structure is proposed by exploiting the advantages of the Microwave Photonics technology over conventional low coherence interferometry. The proposed scheme is based in the analysis of the interference pattern of an incoherent optical signal which is amplitude modulated and transmitted through a dispersive element. The strategic allocation of an interferometric structure combined with balanced photodetection are used to improve the system performance compared to the previous proposals. To the best of our knowledge, an exhaustive theoretical analysis and an experimental demonstration of the structure for multilayered samples are provided in this paper.This work was supported in part by the Ministerio de Ciencia y Tecnologia under Project TEC2014-60378 and in part by the Generalitat Valenciana under the regional Project PROMETEO 2017/103 TECNOLOGIAS Y APLICACIONES FUTURAS DE LA FOTONICA DE MICROONDAS.Benítez-González, J.; Mora Almerich, J. (2018). Low-Coherence Interferometry Using Microwave Photonics for Multilayered Samples. Journal of Lightwave Technology. 36(19):4611-4617. https://doi.org/10.1109/JLT.2018.282709846114617361

Sensitivity Enhancement for Low-Coherence Interferometry

[EN] In this letter, a sensitivity improvement for systems combining low-coherence interferometry (LCI) and microwave photonics (MWP) is demonstrated. This improvement is due to the introduction of a different modulation format and an exhaustive control of the optical source profile compared with previous MWP-LCI schemes. Our proposal allows to retrieve the visibility of low-coherence interferograms through the analysis of the interference pattern using a dispersive element. We demonstrate that the use of a phase modulator offers better stability and lower insertion loss since a bias point configuration is not needed compared with the intensity modulators typically used in these schemes. The process for controlling the optical source profile permits a comparison between uniform and Gaussian profiles. In this way, the limiting effects of the sidelobes over the achieved sensitivity level are analyzed. The proposed MWP-LCI structure is experimentally demonstrated through the characterization of the electrical transfer function. In this case, a maximum sensitivity of 65 dB is achieved in our MWP-LCI structure showing a 30-dB improvement compared with current proposals.This work was supported in part by the National Project through the Ministerio de Ciencia y Tecnologia under Grant TEC2014-60378-C2-1-R and in part by the Generalitat Valenciana under Grant PROMETEO FASE II/2013/012. (Corresponding author: J. Mora.)Benítez-González, J.; Mora Almerich, J. (2017). Sensitivity Enhancement for Low-Coherence Interferometry. IEEE Photonics Technology Letters. 29(20):1735-1738. https://doi.org/10.1109/LPT.2017.2748818S17351738292

Advanced RF Interferometry Structure for Improving Operation Range

© 2018 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] In this letter, a novel structure combining low coherence interferometry (LCI) and microwave photonics (MWP) is proposed. In this case, the electro-optic modulator is strategically placed inside the interferometric structure in order to modify the behavior of the whole MWP-LCI system. Specifically, limiting effects which are inherently generated as the DC term, the self-reflection term and the carrier suppression effect are avoided. This fact enables the improvement of the MWP-LCI operating range in comparison to previous proposals. Moreover, a detailed description of the MWP-LCI structure is addressed in this letter to support the corresponding experimental demonstration and theoretical development. In addition, typical LCI capabilities such as penetration depth, resolution, and sensitivity are also measured. For the MWP-LCI structure proposed here, a 1 cm penetration depth with a resolution of 120 mu m and a sensitivity beyond 50 dB are achieved.This work was supported in part by the National Project TEC2014-60378 through the Ministerio de Ciencia y Tecnologia and in part by the Regional Project PROMETEO FASE II/2013/012 through the Generalitat Valenciana. (Corresponding author: J. Mora.)Benítez-González, J.; Mora Almerich, J. (2018). Advanced RF Interferometry Structure for Improving Operation Range. IEEE Photonics Technology Letters. 30(18):1637-1640. https://doi.org/10.1109/LPT.2018.2865005S16371640301

Estudio de interrelaciones entre el cuento La reina de las nieves y Frozen, el reino del hielo (Propp, Andersen, Disney)

Las páginas que se desarrollan a continuación proponen como base fundamental una comparación entre la narración de Andersen: La reina de las nieves y la adaptación del mismo cuento por Disney en Frozen, el reino del hielo. Dos medios diferentes, el literario y el audiovisual nos servirán para unir mediante el anclaje directo de la obra de Vladimir Propp: Morfología del cuento maravilloso sus contrastes y similitudes en aspectos funcionales y estructurales en relación al mismo. Un análisis posterior de corte analítico-descriptivo en nuestra acotada investigación nos lleva a encontrar otros intereses igualmente importantes, relacionados con la narratología y simbología en los que se presentan de igual forma analogías y contrastes. Las sorpresas no quedan exentas a pesar de la diferencia de edad de las publicaciones exploradas

Diferències en les amplituds articulars entre homes i dones en edat escolar

Introducció: En aquest estudi s’han analitzat les diferències existents entre homes i dones respecte de l’amplitud articular en el transcurs de la vida escolar. Mètodes: S’analitza una població de 420 alumnes, nois i noies, amb edats compreses entre els 7 i 17 anys (educació primària i educació secundària obligatòria). L’estudi s’ha fet mitjançant l’aplicació d’una bateria de tests de valoració de la flexibilitat per mitjà de mesuraments goniomètrics. La bateria consta de 10 proves, de les quals s’extreuen dades referents a la mobilitat articular d’espatlles, maluc, genoll i turmells. Resultats: Els resultats obtinguts indiquen que l’amplitud articular dels subjectes estudiats disminueix amb l’edat. Així mateix, aquests resultats són millors en les dones que en els homes, amb diferències significatives en tres de les proves del test. Els pics d’escurçaments varien en funció del sexe del subjecte

High performance low coherence interferometry using SSB modulation

[EN] Low coherence interferometry (LCI) is an optical measurement technique that has attracted the interest for relevant fields like medicine or sensing. With the objective of improving LCI capabilities, microwave photonics (MWP) arises as an innovative technology to enhance LCI possibilities. In this letter, a novel MWP-LCI approach is proposed and experimentally demonstrated to measure the optical path difference (OPD) of a sample. The operation principle of the technique is based on the analysis of the interference pattern through a dispersive element to retrieve its visibility using a vector network analyzer. Different capabilities of the system in terms of sensitivity, resolution, and SNR have been proved. In this case, the proposal is able to avoid carrier-suppression effect leading to a sensitivity improvement of 20 dB in comparison with previous structures for certain values of the OPD. Moreover, the OPD range has been extended up to 10 mm achieving an invariant resolution over all operation range. Finally, the improvement of the SNR of the system has been experimentally demonstrated by controlling properly the RF resonance profile through the adjustment of the optical source power distribution. We have observed an improvement of the dynamic range close to 40 dB for a Gaussian profile.This work was supported in part by the National Project funded by the Ministerio de Ciencia y Tecnologia under Grant TEC2014-60378-C2-1-R and in part by the Regional Project PROMETEO FASE under funded by the Generalitat Valenciana Grant II/2013/012.Benítez-González, J.; Bolea Boluda, M.; Mora Almerich, J. (2017). High performance low coherence interferometry using SSB modulation. IEEE Photonics Technology Letters. 29(1):90-93. https://doi.org/10.1109/LPT.2016.2628963S909329

SCM Adaptation to Improve Scanning Rate in RF Interferometry Applications

[FR] In this letter, we present a novel structure for performing subcarrier multiplexing (SCM) to improve the scanning rate in low coherence interferometry (LCI) systems combined with the microwave photonics (MWP) technology. In this MWP-LCI proposal, the optical path differences (OPDs) produced by different samples between the arms of an interferometer are closely related to the central frequency of different RF resonances generated in the RF domain. By the proposed adaptation of the SCM technique, M subcarriers are multiplexed in the modulation stage and each subcarrier is set to sweep simultaneously a concrete part of the spectrum. The complete electrical transfer function of the structure is obtained combining each individual sweep. Therefore, a considerable reduction of the sweep time is provided to collect the complete electrical transfer function. Therefore, the scanning rate is reduced according to the number of subcarriers (M) employed in the multiplexing stage. An OPD range of 8 mm is achieved with a constant resolution of 120 &#956;m in the whole range. Finally, a maximum sensitivity of 60 dB is also reached for that operation range.The research leading to these results was supported by the National Project TEC2014-60378-C2-1-R funded by the Ministerio de Ciencia y Tecnologia and the regional project PROMETEO FASE II/2013/012 funded by the Generalitat Valenciana. (Corresponding author: J. Mora.)Benítez-González, J.; Mora Almerich, J.; Bolea Boluda, M. (2017). SCM Adaptation to Improve Scanning Rate in RF Interferometry Applications. IEEE Photonics Technology Letters. 29(12):999-1002. https://doi.org/10.1109/LPT.2017.2700884S9991002291