Variance reduction and signal-to-noise ratio: Reducing uncertainty in spectral ratios

This paper uses an unusually large dataset to study scatter in site-effect estimation, focusing on how the events that increase uncertainty can be removed from the dataset. Four hundred seventy-three weak motion earthquake records from the surface and bedrock of a 178-m-deep borehole in Aegion, Gulf of Corinth, Greece, are used to evaluate spectral ratios. A simple statistical tool, variance reduction (VR), is first used to identify two groups of events that lie closest and farthest from the average, which is considered here as the initial best estimate of the site response. The scatter in the original dataset is found to be due to the group of events with smallest VR. These events can be removed from the dataset in order to compute a more reliable site response. However, VR is not normally used to choose records for site-effect studies, and it cannot be applied to the usual small datasets available. The signal-to-noise ratio (SNR) is normally used to this end, for which reason we investigate whether SNR can be used to achieve similar results as VR. Signal-to-noise ratio is estimated using different definitions. Data selection based on SNR is then compared to that using VR in order to define an SNR-based criterion that discriminates against events that, according to VR, increase scatter. We find that defining the SNR of a surface record as the mean value over a frequency range around the resonant peak (here, 0.5–1.5 Hz) and using a cutoff value of 5 may be used in this case to exclude most events for which VR is small. This process is also applied to the downhole station, where we obtain similar results for a cutoff value of 3

Burnout y educación en línea: adaptación y validación de escala durante la pandemia

During the COVID-19 pandemic, online education represented a serious alternative to continuing working life in higher education institutions (HEIs). Teachers around the world embraced a new role, adopting and using a wide range of technological and virtual tools to continue performing their activities and with the aim to interact with students and to continue teaching.  For this reason, research related to seek and identify factors for the teachers’ well-being is essential for educational leaders. Regarding these ideas, this paper aims to test the construct validity of a Mexican version of the Maslach Burnout Inventory-Educators Survey (MBI-ES) of Maslach et al. (1997), adapted to online education. Participants consisted of 406 Mexican university teachers who emergently switched from traditional to online educational practices during the SARS-CoV-2 virus outbreak. In order to test the factor structure of three alternative models based on Szigeti et al. (2016), the authors performed exploratory and confirmatory factor analyses (Ferrando & Lorenzo-Seva, 2018). Results showed that the model with three domain factors has the best fit. Besides, our findings show that the three-factor structure of the Mexican adaptation of MBI-ES is valid and reliable for the analysis of online education because the loading of all factors was representative.   Keywords: Burnout, Teacher, Online Education, COVID-19, Pandemic, Scale Adaptation.La educación en línea representa una alternativa a la continuidad de la vida laboral en las instituciones de educación superior (IES). Los docentes adoptaron un nuevo rol al disponer de una serie de herramientas tecnológicas y virtuales para realizar sus actividades e interactuar con los alumnos.  Por esta razón, la búsqueda e identificación de factores para el bienestar de los profesores es esencial para los líderes educativos. Este trabajo tiene como objetivo probar la validez de constructo de una versión mexicana de la escala Maslach Burnout Inventory-Educators Survey (MBI-ES) de Maslach et al. (1997), adaptada a la educación en línea.  Los participantes consisten en 406 profesores universitarios mexicanos que cambiaron las prácticas educativas tradicionales por prácticas en línea durante la pandemia de COVID-19. Para probar la estructura factorial de tres modelos alternativos tomando como base a Szigeti et al. (2016), se realizaron análisis factoriales exploratorio y confirmatorio (Ferrando y Lorenzo-Seva, 2018). Los resultados mostraron que el modelo con tres factores de dominio tiene el mejor ajuste. Además, nuestros hallazgos muestran que la estructura de tres factores de la adaptación mexicana de MBI-ES es válida y confiable para el análisis de la educación en línea porque todas las cargas de los factores fueron representativas.   Palabras clave: Burnout, Docente, Educación en línea, COVID-19, Pandemia, Adaptación de escala

Spontaneous Symmetry Breakdown in non-relativistic Quantum Mechanics

The advantages and disadvantages of some pedagogical non-relativistic quantum-mechanical models, used to illustrate spontaneous symmetry breakdown, are discussed. A simple quantum-mechanical toy model (a spinor on the line, subject to a magnetostatic interaction) is presented, that exhibits the spontaneous breakdown of an internal symmetry.Comment: 19 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1111.1213. Equations (30) and (31) have been corrected. Other minor correction

Design and implementation of an ultrasonic sensor for rapid monitoring of industrial malolactic fermentation of wines

Ultrasound is an emerging technology that can be applied to monitor food processes. However, ultrasonic techniques are usually limited to research activities within a laboratory environment and they are not extensively used in industrial processes. The aim of this paper is to describe a novel ultrasonic sensor designed to monitor physical–chemical changes that occur in wines stored in industrial tanks. Essentially, the sensor consists of an ultrasonic transducer in contact with a buffer rod, mounted inside a stainless steel tube section. This structure allows the ultrasonic sensor to be directly installed in stainless steel tanks of an industrial plant. The operating principle of this design is based on the measurement of ultrasonic velocity of propagation. To test its proper operation, the sensor has been used to measure changes of concentration in aqueous samples and to monitor the progress of a malolactic fermentation of red wines in various commercial wineries. Results show the feasibility of using this sensor for monitoring malolactic fermentations in red wines placed in industrial tanks.Postprint (author's final draft

Enfoque de intercambio social y la felicidad en el trabajo: explorando el efecto mediador del compromiso organizacional

This article aims to determine the direct and indirect effects of social exchange relationships Leader Member Exchange and Team Member Exchange (LMX and TMX) on organizational commitment and happiness at work. Based on the literature review and relying on the Social Exchange Theory perspective, the authors constructed the hypothetical structure, including the four variables under study. The sample comprised 177 employees from Mexican firms, and the proposed hypotheses were under examination through a path analysis. Results show that LMX, TMX, and happiness at work have a direct effect on organizational commitment. We also found an organizational commitment to be a partial relationship mediator between LMX and happiness at work.Este artículo tiene como objetivo determinar los efectos directos e indirectos de las relaciones de intercambio social, intercambio líder miembro e intercambio entre miembros del equipo (LMX y TMX) sobre el compromiso organizacional y la felicidad en el trabajo. Con base en la revisión de la literatura y apoyándose en la perspectiva de la Teoría del Intercambio Social, los autores construyeron la estructura hipotética, incluyendo las cuatro variables en estudio. La muestra estuvo compuesta por 177 empleados de empresas mexicanas, y las hipótesis propuestas fueron examinadas a través de un análisis de trayectoria. Los resultados muestran que LMX, TMX y la felicidad en el trabajo tienen un efecto directo sobre el compromiso organizacional. También encontramos que el compromiso organizacional media la relación parcial entre LMX y la felicidad en el trabajo

The chromatin remodeling factor CHD8 interacts with elongating RNA polymerase II and controls expression of the cyclin E2 gene

CHD8 is a chromatin remodeling ATPase of the SNF2 family. We found that depletion of CHD8 impairs cell proliferation. In order to identify CHD8 target genes, we performed a transcriptomic analysis of CHD8-depleted cells, finding out that CHD8 controls the expression of cyclin E2 (CCNE2) and thymidylate synthetase (TYMS), two genes expressed in the G1/S transition of the cell cycle. CHD8 was also able to co-activate the CCNE2 promoter in transient transfection experiments. Chromatin immunoprecipitation experiments demonstrated that CHD8 binds directly to the 5′ region of both CCNE2 and TYMS genes. Interestingly, both RNA polymerase II (RNAPII) and CHD8 bind constitutively to the 5′ promoter-proximal region of CCNE2, regardless of the cell-cycle phase and, therefore, of the expression of CCNE2. The tandem chromodomains of CHD8 bind in vitro specifically to histone H3 di-methylated at lysine 4. However, CHD8 depletion does not affect the methylation levels of this residue. We also show that CHD8 associates with the elongating form of RNAPII, which is phosphorylated in its carboxy-terminal domain (CTD). Furthermore, CHD8-depleted cells are hypersensitive to drugs that inhibit RNAPII phosphorylation at serine 2, suggesting that CHD8 is required for an early step of the RNAPII transcription cycle

Adquisición de datos digitales con protocolo VME sobre FPGA

En este artículo se presenta la realización sobre FPGA de un circuito con 16 filtros digitales. Un cambio en la entrada es validado cada vez que tres muestras consecutivas toman el mismo valor. El dato muestreado es accesible mediante protocolo VME estándar, incluyendo daisy-cbain para la gestión de interrupciones. El circuito de acceso VME se ha descrito en lenguaje de comportamiento VERILOG-XL, y sintetizado usando SYNERGY. El resto del circuito ha sido capturado y simulado empleando el entorno de diseño Framework II de Cadence. El circuito ha sido programado en una FPGA 1020A de Texas Instrument. Como resultado se ha obtenido una tarjeta de adquisición de datos con una densidad de componentes muy baja, y que está siendo actualmente empleada en sistemas de control industriales

Quartz crystal microbalance holder design for on-line sensing in liquid applications

In this paper, the design of a QCM sensor for liquid media measurements in vertical position is described. A rugged and low-cost proof holder has been designed, the cost of which is significantly lower than those of traditional commercial holders. The crystal is not replaceable but it can be easily cleaned. Its small volume permits to be used by dipping it in the liquid with the desired location and orientation. The developed design has been experimentally validated by measuring changes in the resonance frequency and resistance of the QCM sensor immersed vertically in different calibrated aqueous glycerol solutions. The obtained results show a great agreement with the Kanazawa theoretical expression. Consequently, the designed QCM sensor would be appropriate for sensing applications in liquids, and might take part of a future on-line multichannel low-cost QCM-based measurement system.Peer ReviewedPostprint (published version