In this work, a procedure to obtain an accurate value of the critical speed of a cracked shaft is presented. The method is based on the transversal displacements of the cracked section when the shaft ...is rotating at submultiples of the critical speed. The SERR (Strain Energy Ralease Rate) theory and the CCL (Crack Closure Line) approach are used to analyse the proposed methodology for considering the behaviour of the crack. In order to obtain the best information and to define the procedure, the orbits and the frequency spectra at different subcritical rotational speed intervals are analyzed by means of the Fast Fourier Transform. The comparison of the maximum values of the FFT peaks within the intervals allows the subcritical speed to be determined, along with the value of the critical speed. When verified, the proposed procedure is applied to shafts with the same geometry and material and with cracks of increasing depth. The results show that the critical speed diminishes with the severity of the crack, as expected. A comparison is made between the critical speed obtained using the vertical and the horizontal displacements, finding no remarkable differences, meaning that in practical applications only one sensor for one of the displacements (in the vertical or horizontal direction) is needed to determine the critical speed. This is one of the main contributions of the paper, as it means that the orbits of the shaft are not needed. Finally, after this study we can conclude that the best results are achieved when the critical speed is obtained using data displacement in only one direction within the intervals around 12 or 13 of the critical speed.
Covid‐19 has paved the way for major disruptions to conventional healthcare systems accelerating participatory health enabled by interactive virtual environments. The role of the ‘patient voice’ as a ...fundamental resource in an effective Covid‐19 response has moved centre stage. In this time of extraordinary crisis and health system disruptions, patient‐centred models offer opportunities for embedding shared decision‐making to improve health outcomes using digital tools. Through an exploratory case study, this paper examines patient action during Covid‐19 and how co‐design methods can be adapted to an online environment in response to Covid‐19 restrictions to improve the Covid‐19 patient and family experience of care. Experienced‐based co‐design was employed to map the care journey of patients with Covid‐19 confined at home in Spain – one of the hardest‐hit countries in the pandemic – to identify quality improvements. Main touchpoint needs were explored in online co‐design workshops leading to improvement projects including the development of a Covid‐19 patient online health community (OHC) to deliver patient‐centred care during the outbreak. The Covid‐19 patient OHC has become an instrument that facilitates Covid‐19 patient’s recovery, especially psychological resilience. OHC participation has clear potential for empowerment and transformative agency as it enables Covid‐19 patients to control the content and flow of the information available to them. This paper offers valuable insights on how co‐design can be adapted to an online format to enable more meaningful patient input to healthcare design when faced with uncertainty and ambiguity during health crises.
El objetivo del presente trabajo es validar un modelo de predisposición y compromiso organizacional a partir de la teoría de Cohen (2007). El método empleado fue la técnica multivariada de Cuadrados ...Mínimos Parciales (PLS-SEM) en una muestra de 184 empleados de la industria maquiladora en Cd. Juárez. Como resultado se encontró evidencia de que la predisposición instrumental y normativa tienen un efecto directo, positivo y significativo sobre el compromiso afectivo e instrumental. La relevancia de este hallazgo radica en la aportación del sustento empírico a la teoría de dos dimensiones propuesta por Cohen (2007) y su originalidad reside en la inclusión de las teorías del comportamiento planeado (TCP) y de acción razonada (TAR) para estudiar la predisposición para el compromiso. Como limitaciones,
Any experiment conducted in a rodent laboratory is done so against the backdrop of each animal's physiological state at the time of the experiment. This physiological state can be the product of ...multiple factors, both internal (e.g., animal sex, strain, hormone cycles, or circadian rhythms) and external (e.g., housing conditions, social status, and light dark phases). Each of these factors has the potential to influence experimental outcomes, either independently or via interactions with others, and yet there is little consistency across laboratories in terms of the weight with which they are considered in experimental design. Such discrepancies-both in practice and in reporting-likely contribute to the perception of a reproducibility crisis in the field of behavioral neuroscience. In this review, we discuss how several of these sources of variability can impact outcomes within the realm of common learning and memory paradigms.
In this study, two closed-form solutions for determining the first two natural frequencies of the flapwise bending vibration of a cracked Euler–Bernoulli beam at low rotational speed have been ...developed. To solve the governing differential equations of motion, the Frobenius method of solution in power series has been used. The crack has been modeled using two undamaged parts of the beam connected by a rotational spring. From the previous results, two novel polynomial expressions have been developed to obtain the first two natural frequencies as a function of angular velocity, slenderness ratio, cube radius and crack characteristics (depth and location). These expressions have been formulated using multiple regression techniques. To the knowledge of the authors, there is no similar expressions in the literature, which calculate, in a simple way, the first two natural frequencies based on beam features and crack parameters, without the need to know or solve the differential equations of motion governing the beam. In summary, the derived natural frequency expressions provide an extremely simple, practical, and accurate instrument for studying the dynamic behavior of rotating cracked Euler–Bernoulli beams at low angular speed, especially useful, in the future, to establish small-scale wind turbines’ maintenance planes.
The ability of animals to maximize benefits and minimize costs during approach-avoidance conflicts is an important evolutionary tool, but little is known about the emergence of specific strategies ...for conflict resolution. Accordingly, we developed a simple approach-avoidance conflict task in rats that pits the motivation to press a lever for sucrose against the motivation to step onto a distant platform to avoid a footshock delivered at the end of a 30 s tone (sucrose is available only during the tone). Rats received conflict training for 16 days to give them a chance to optimize their strategy by learning to properly time the expression of both behaviors across the tone. Rats unexpectedly separated into three distinct subgroups: those pressing early in the tone and avoiding later (Timers, 49%); those avoiding throughout the tone (Avoidance-preferring, 32%); and those pressing throughout the tone (Approach-preferring, 19%). The immediate early gene cFos revealed that Timers showed increased activity in the ventral striatum and midline thalamus relative to the other two subgroups, Avoidance-preferring rats showed increased activity in the amygdala, and Approach-preferring rats showed decreased activity in the prefrontal cortex. This pattern is consistent with low fear and high behavioral flexibility in Timers, suggesting the potential of this task to reveal the neural mechanisms of conflict resolution.
To study the effect of melatonin administration on glucose metabolism in humans in the morning and evening.
Placebo-controlled, single-blind design.
Laboratory assessments.
21 healthy women (24 ± 6 ...y; body mass index: 23.0 ± 3.3 kg/m(2)).
Glucose tolerance was assessed by oral glucose tolerance tests (OGTT; 75 g glucose) on 4 occasions: in the morning (9 AM), and evening (9 PM); each occurring 15 minutes after melatonin (5 mg) and placebo administration on 4 non-consecutive days.
Melatonin administration impaired glucose tolerance. When administered in the morning, melatonin significantly increased the incremental area under the curve (AUC) and maximum concentration (Cmax) of plasma glucose following OGTT by 186% and 21%, respectively, as compared to placebo; while in the evening, melatonin significantly increased glucose AUC and Cmax by 54% and 27%, respectively. The effect of melatonin on the insulin response to the OGTT depended on the time of day (P < 0.05). In the morning, melatonin decreased glucose tolerance primarily by decreasing insulin release, while in the evening, by decreasing insulin sensitivity.
Acute melatonin administration in humans impairs glucose tolerance in both the morning and evening. When administering melatonin, the proximity to meal timing may need to be considered, particularly in those at risk for glucose intolerance.
Las estrategias comunicativas, especialmente en la nueva economía, evolucionan de forma cada vez más acelerada, para adaptarse al complejo y cambiante escenario de la interconectada sociedad ...red.Partiendo de la hipótesis de la existencia de un planteamiento de la estrategia de comunicación 360º, heredero del enfoque propio de la comunicación integrada de marketing, el artículo describe las estrategias de comunicación de tres marcas nativas digitales de referencia en Barcelona, sede del Mobile World Congress, donde se ha desarrollado un contexto interconectado de startups y marcas nativas digitales.Los resultados de esta investigación provienen de tres casos de estudio (Wallapop, Westwing y Fotocasa), que muestran que su planificación estratégica consta de cuatro fases (investigación, planificación, ejecución y evaluación), coincidentes con el modelo RACE de Marston. La estrategia comunicativa que constatan estos casos de estudio pone el foco en el corto plazo, con una perspectiva growth hacker, característica del ecosistema startup, que aprovecha las sinergias entre acciones de publicidad y relaciones públicas. Para llevarlas a cabo estas accciones de comunicación, las marcas nativas digitales buscan sinergias entre acciones, utilizando todas las herramientas de investigación y medición a su alcance, que les permiten experimentar de forma controlada y tomar decisiones basadas en datos, en un proceso de aprendizaje continuo.
Purpose
La utilización de plataformas colaborativas, que intermedian en la cesión de uso de viviendas con fines turísticos, ha originado: por una parte, que se adopten medidas con el objetivo de ...prevenir el fraude fiscal (como por ejemplo, la obligación de información, a través del modelo 179) y, por otra parte, que la Administración tributaria preste especial atención al tratamiento fiscal de los rendimientos percibidos por los usuarios de las plataformas colaborativas.
Design/methodology/approach
Enfoque jurídico-tributario.
Findings
Las conclusiones se han puesto de manifiesto en el trabajo de investigación realizado.
Originality/value
Análisis de algunos aspectos fiscales sobre la cesión de uso de viviendas con fines turísticos.
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