Implementación y validación de nuevas funcionalidades para el simulador LeonViP

Uno de los puntos clave al realizar una misión espacial es asegurar de que todos los elementos que lo componen tengan un riesgo mínimo de fallo, y en el caso de haberlo, poder recuperarse de el. Por ello es esencial poder simular posibles fallos y validar la respuesta a ellos. En este proyecto se plantea ampliar la funcionalidad del simulador LeonViP que está siendo desarrollado actualmente por el grupo de investigación Space Research Group de la Universidad de Alcalá, y se caracteriza por poder simular fallos de memoria como los que se producirían en caso de radiación cósmica.One of the key points when doing a space mission is to ensure that all elements that compose it have a very low risk of failing, and, in case of a fault, it has to be able to recover from it. Because of this, is essential to be able to simulate these faults and validate the response to them. This project seeks to extend the LeonViP simulator, which is currently being developed by the Space Research Group of the University of Alcalá and is characterized for being able to simulate memory faults like the ones produced by cosmic radiation.Grado en Ingeniería de Computadore

Memory management unit for hardware-assisted dynamic relocation in on-board satellite systems

Satellite on-board systems spend their lives in hostile environments, where radiation can cause critical hardware failures. One of the most radiation-sensitive elements is memory. The so-called single event effects (SEEs) can corrupt or even irretrievably damage the cells that store the data and program instructions. When one of these cells is corrupted, the program must not use it again during execution. In order to avoid rebuilding and uploading the code, a memory management unit can be used to transparently relocate the program to an error-free memory region. This article presents the design and implementation of a memory management unit that allows the dynamic relocation of on-board software. This unit provides a hardware mechanism that allows the automatic relocation of sections of code or data at run-time, only requiring software intervention for initialization and configuration. The unit has been implemented on the LEON architecture, a reference for the European Space Agency (ESA) missions. The proposed solution has been validated using the boot and application software (ASW) of the instrument control unit of the Energetic Particle Detector of the Solar Orbiter Mission as a base. Processor synthesis on different FPGAs has shown resource usage and power consumption similar to that of a conventional memory management unit. The results vary between ± 1?15% in resource usage and ± 1?7% in power consumption, depending on the number of inputs assigned to the unit and the FPGA used. When comparing performance, both the proposed and conventional memory management units show the same results.Universidad de Alcal

Which one came first: movement behavior or frailty? A cross-lagged panel model in the Toledo Study for Healthy Aging

Background There has been limited longitudinal assessment of the relationship between moderate-to-vigorous physical activity (MVPA) and sedentary behaviour (SB) with frailty, and no studies have explored the possibility of reverse causality. This study aimed to determine the potential bidirectionality of the relationship between accelerometer-assessed MVPA, SB, and frailty over time in older adults. Methods Participants were from the Toledo Study for Healthy Aging. We analysed 186 older people aged 67 to 90 (76.7 ± 3.9; 52.7% female participants) over a 4-year period. Time spent in SB and MVPA was assessed by accelerometry. Frailty Trait Scale was used to determine frailty levels. A cross-lagged panel model design was used to test the reciprocal relationships between MVPA/SB and frailty. Results Frailty Trait Scale score changed from 35.4 to 43.8 points between the two times (P < 0.05). We also found a reduction of 7 min/day in the time spent on MVPA (P < 0.05), and participants tended to spend more time on SB (P = 0.076). Our analyses revealed that lower levels of initial MVPA predicted higher levels of later frailty [std. β = 0.126; confidence interval (CI) = 0.231, 0.021; P < 0.05], whereas initial spent time on SB did not predict later frailty (std. β = 0.049; CI = 0.185, 0.087; P = 0.48). Conversely, an initial increased frailty status predicted higher levels of later SB (std. β = 0.167; CI = 0.026, 0.307; P < 0.05) but not those of MVPA (std. β = 0.071; CI = 0.033, 0.175; P = 0.18). Conclusions Our observations suggest that the relationship between MVPA/SB and frailty is unidirectional: individuals who spent less time on MVPA at baseline are more likely to increase their frailty score, and individuals who are more frail are more likely to spent more time on SB at follow-up. Interventions and policies should aim to increase MVPA levels from earlier stages to promote successful aging

Can physical activity offset the detrimental consequences of sedentary time on frailty? A moderation analysis in 749 older adults measured with accelerometers

Objectives: To determine whether or not and to what extent the association between sedentary time and frailty was moderated by moderate-to-vigorous physical activity in older adults. Design: Cross-sectional. Setting: Community-dwelling individuals. Participants: 749 (403 females and 346 males) white older adults. Measurements: Sedentary time and moderate-to-vigorous physical activity were measured with accelerometers. Frailty was objectively measured using the Frailty Trait Scale. All models were adjusted for age, sex, education, income, marital status, body mass index, moderate-to-vigorous physical activity, and accelerometer wear time. Results: The regression model reported a significant effect of sedentary time on frailty (P < .05). Nevertheless, the results indicated that moderate-to-vigorous physical activity moderates the relationship between frailty status and sedentary time. The Johnson-Neyman technique determined that the estimated moderate-to-vigorous physical activity point was 27.25 minutes/d, from which sedentary time has no significant effect on frailty. Conclusions: Moderate-to-vigorous physical activity is a moderator in the relationship between sedentary time and frailty in older adults, offsetting the harmful effects of sedentary behavior with 27 minutes/d of moderate-to-vigorous activity. Engaging in moderate-to-vigorous physical activities should be encouraged. Reducing sedentary behavior may also be beneficial, particularly among inactive older adults

Dose-response association between physical activity and sedentary time categories on ageing biomarkers

Background: Physical activity and sedentary behaviour have been suggested to independently affect a number of health outcomes. To what extent different combinations of physical activity and sedentary behaviour may influence physical function and frailty outcomes in older adults is unknown. The aim of this study was to examine the combination of mutually exclusive categories of accelerometer-measured physical activity and sedentary time on physical function and frailty in older adults. Methods: 771 older adults (54% women; 76.8 ± 4.9 years) from the Toledo Study for Healthy Aging participated in this cross-sectional study. Physical activity and sedentary time were measured by accelerometry. Physically active was defined as meeting current aerobic guidelines for older adults proposed by the World Health Organization. Low sedentary was defined as residing in the lowest quartile of the light physical activity-to-sedentary time ratio. Participants were then classified into one of four mutually exclusive movement patterns: (1) ‘physically active & low sedentary’, (2) ‘physically active & high sedentary’, (3) ‘physically inactive & low sedentary’, and (4) ‘physically inactive & high sedentary’. The Short Physical Performance Battery was used to measure physical function and frailty was assessed using the Frailty Trait Scale. Results: ‘Physically active & low sedentary’ and ‘physically active & high sedentary’ individuals had significantly higher levels of physical function (β = 1.73 and β = 1.30 respectively; all p < 0.001) and lower frailty (β = − 13.96 and β = − 8.71 respectively; all p < 0.001) compared to ‘physically inactive & high sedentary’ participants. Likewise, ‘physically inactive & low sedentary’ group had significantly lower frailty (β = − 2.50; p = 0.05), but significance was not reached for physical function. Conclusions: We found a dose-response association of the different movement patterns analysed in this study with physical function and frailty. Meeting the physical activity guidelines was associated with the most beneficial physical function and frailty profiles in our sample. Among inactive people, more light intensity relative to sedentary time was associated with better frailty status. These results point out to the possibility of stepwise interventions (i.e. targeting less strenuous activities) to promote successful aging, particularly in inactive older adults

Response to McAvoy and Tudor-Locke on their commentary on our manuscript: “Association of accelerometer-derived step volume and intensity with hospitalizations and mortality in older adults: A prospective cohort study”

2 páginasThe authors expressed some concerns about our methodology used to define accelerometer-derived step intensity and the analytical approach applied in our stud

Breaking sedentary time predicts future frailty in inactive older adults : A cross-lagged panel model

Background Cross-sectional evidence exists on the beneficial effects of breaks in sedentary time (BST) on frailty in older adults. Nonetheless, the longitudinal nature of these associations is unknown. This study aimed to investigate the direction and temporal order of the association between accelerometer-derived BST and frailty over time in older adults. Methods This longitudinal study analyzed a total of 186 older adults aged 67–90 (76.7 ± 3.9 years; 52.7% females) from the Toledo Study for Healthy Aging over a 4-year period. Number of daily BST was measured by accelerometry. Frailty was assessed with the Frailty Trait Scale. Multiple cross-lagged panel models were used to test the temporal and reciprocal relationship between BST and frailty. Results For those physically inactive (n = 126), our analyses revealed a reciprocal inverse relationship between BST and frailty, such as higher initial BST predicted lower levels of later frailty (standardized regression coefficient [β] = −0.150, 95% confidence interval [CI] = −0.281, −0.018; p < .05); as well as initial lower frailty levels predicted higher future BST (β = −0.161, 95% CI = −0.310, −0.011; p < .05). Conversely, no significant pathway was found in the active participants (n = 60). Conclusions In physically inactive older adults, the relationship between BST and frailty is bidirectional, while in active individuals no associations were found. This investigation provides preliminary longitudinal evidence that breaking-up sedentary time more often reduces frailty in those older adults who do not meet physical activity recommendations. Targeting frequent BST may bring a feasible approach to decrease the burden of frailty among more at-risk inactive older adults

Association of accelerometer-derived step volume and intensity with hospitalizations and mortality in older adults: A prospective cohort study

Purpose: To examine the associations of accelerometer-derived steps volume and intensity with hospitalizations and all-cause mortality in older adults. Methods: This prospective cohort study involved 768 community-dwelling Spanish older adults (78.8 ± 4.9 years, mean ± SD; 53.9% females) from the Toledo Study for Healthy Aging (2012–2017). The number of steps per day and step cadence (steps/min) were derived from a hip-mounted accelerometer worn for at least 4 days at baseline. Participants were followed-up over a mean period of 3.1 years for hospitalization and 5.7 years for all-cause mortality. Cox proportional hazards regression models were used to estimate the individual and joint associations between daily steps and stepping intensity with hospitalizations and all-cause mortality. Results: Included participants walked 5835 ± 3445 steps/day (mean ± SD) with an intensity of 7.3 ± 4.1 steps/min. After adjusting for age, sex, body mass index (BMI), education, income, marital status and comorbidities, higher step count (hazard ratio (HR) = 0.95, 95% confidence intervals (95%CI: 0.90–1.00, and HR = 0.87, 95%CI: 0.81–0.95 per additional 1000 steps) and higher step intensity (HR = 0.95, 95%CI: 0.91–0.99, and HR = 0.89, 95%CI: 0.84–0.95 per each additional step/min) were associated with fewer hospitalizations and all-cause mortality risk, respectively. Compared to the group having low step volume and intensity, individuals in the group having high step volume and intensity had a lower risk of hospitalization (HR = 0.72, 95%CI: 0.52–0.98) and all-cause mortality (HR = 0.60, 95%CI: 0.37–0.98). Conclusion: Among older adults, both high step volume and step intensity were significantly associated with lower hospitalization and all-cause mortality risk. Increasing step volume and intensity may benefit older people

Association of accelerometer-derived step volume and intensity with hospitalizations and mortality in older adults : A prospective cohort study

Purpose This study aimed to examine the associations of accelerometer-derived steps volume and intensity with hospitalizations and all-cause mortality in older adults. Methods This prospective cohort study involved 768 community-dwelling Spanish older adults (78.8 ± 4.9 years, mean ± SD; 53.9% females) from the Toledo Study for Healthy Aging (2012–2017). The number of steps per day and step cadence (steps/min) were derived from a hip-mounted accelerometer worn for at least 4 days at baseline. Participants were followed-up over a mean period of 3.1 years for hospitalization and 5.7 years for all-cause mortality. Cox proportional hazards regression models were used to estimate the individual and joint associations between daily steps and stepping intensity with hospitalizations and all-cause mortality. Results Included participants walked 5835 ± 3445 steps/day with an intensity of 7.3 ± 4.1 steps/min. After adjusting for age, sex, body mass index (BMI), education, income, marital status and comorbidities, higher step count (hazard ratio (HR) = 0.95, 95% confidence interval (95%CI: 0.90–1.00, and HR = 0.87, 95%CI: 0.81–0.95 per additional 1000 steps) and higher step intensity (HR = 0.95, 95%CI: 0.91–0.99, and HR = 0.89, 95%CI: 0.84–0.95 per each additional step/min) were associated with fewer hospitalizations and all-cause mortality risk, respectively. Compared to the group having low step volume and intensity, individuals in the group having high step volume and intensity had a lower risk of hospitalization (HR = 0.72, 95%CI: 0.52–0.98) and all-cause mortality (HR = 0.60, 95%CI: 0.37–0.98). Conclusion Among older adults, both high step volume and step intensity were significantly associated with lower hospitalization and all-cause mortality risk. Increasing step volume and intensity may benefit older people

Association of accelerometer-derived step volume and intensity with hospitalizations and mortality in older adults: A prospective cohort study

Purpose: To examine the associations of accelerometer-derived steps volume and intensity with hospitalizations and all-cause mortality in older adults. Methods: This prospective cohort study involved 768 community-dwelling Spanish older adults (78.8 ± 4.9 years, mean ± SD; 53.9% females) from the Toledo Study for Healthy Aging (2012–2017). The number of steps per day and step cadence (steps/min) were derived from a hip-mounted accelerometer worn for at least 4 days at baseline. Participants were followed-up over a mean period of 3.1 years for hospitalization and 5.7 years for all-cause mortality. Cox proportional hazards regression models were used to estimate the individual and joint associations between daily steps and stepping intensity with hospitalizations and all-cause mortality. Results: Included participants walked 5835 ± 3445 steps/day (mean ± SD) with an intensity of 7.3 ± 4.1 steps/min. After adjusting for age, sex, body mass index (BMI), education, income, marital status and comorbidities, higher step count (hazard ratio (HR) = 0.95, 95% confidence intervals (95%CI: 0.90–1.00, and HR = 0.87, 95%CI: 0.81–0.95 per additional 1000 steps) and higher step intensity (HR = 0.95, 95%CI: 0.91–0.99, and HR = 0.89, 95%CI: 0.84–0.95 per each additional step/min) were associated with fewer hospitalizations and all-cause mortality risk, respectively. Compared to the group having low step volume and intensity, individuals in the group having high step volume and intensity had a lower risk of hospitalization (HR = 0.72, 95%CI: 0.52–0.98) and all-cause mortality (HR = 0.60, 95%CI: 0.37–0.98). Conclusion: Among older adults, both high step volume and step intensity were significantly associated with lower hospitalization and all-cause mortality risk. Increasing step volume and intensity may benefit older people