Nonlinear time-domain macromodeling of OTA circuits

The authors present an accurate nonlinear macromodel of the operational transconductance amplifier (OTA) which is suitable for the transient simulation of OTA-based CMOS analog integrated circuits. As compared to device-level OTA models, the proposed macromodel is advantageous in terms of CPU time. Also, in circuits with many OTAs, it does not have the problems of convergence that the device-level MODEL has. All the macromodel parameters can be calculated from measurements made at the OTA terminals. Experimental results from a 3-μm CMOS OTA prototype as well as simulation results from device-level models are included and compared to simulation results from the macromodel

Empirical evaluation of educational interactive systems

[EN ]Educational software systems are usually highly interactive systems that needs to be evaluated from two different perspectives, first as interactive software, mainly using usability and accessibility approaches, and second as an educational product that needs to be evaluated from its learning impact. The empirical evaluation methods may be quantitative, with a more deductive reasoning, or qualitative, with a more inductive reasoning, oriented, however mixed approaches have been used extensively because they combine the both main methods with a more pragmatic knowledge focusing on knowing the consequences or solving problems. The empirical evaluation of interactive educational software due to its own characteristics requires a mixed approach typically. This special issue is devoted to identify, share and valorise best practices and experiences, with a very solid modelling background, that are focused on the empirical evaluation of educational interactive systems with a special emphasis on mixed quantitative and qualitative approaches

How Europeans move: a moderate-to-vigorous physical activity and sitting time paradox in the European Union

Objectives: This study aimed to assess the interactions between physical activity (PA) and sedentary behaviour in a large population taking account of major sociodemographic characteristics. Study design: Cross-sectional population-based study. Methods: Data from 28,031 individuals living in the European Union who were aged ≥15 years were retrieved from a cross-sectional survey, the Eurobarometer 2017. Interactions among the four mobility components (vigorous, moderate, walking activity and sitting time) were assessed at the individual level across age, gender and place of residence, and at the country level by compositional data analysis, hierarchical linear regressions and principal component analysis. Results: The most frequently reported PA was walking; however, sitting time represented >95% of the reported weekly times, whereas moderate-to-vigorous PA (MVPA) represented <1%. Women reported less PA and sitting time, age decreased total PA and increased sitting time, and individuals living in large urban areas reported lower PA and higher sitting times. MVPA decreased with age (β = -0.047, P < 0.001) and was lower in women (β = -0.760, P < 0.001) and those living in large urban areas (β = -0.581, P < 0.001), while walking and sitting times increased with age, being higher in women and lower in those living in rural areas. At the country level, sitting time was positively associated with moderate activity (β = 0.389, P = 0.041) and marginally non-significant with MVPA (β = 0.330, P = 0.087). Conclusions: Walking was the highest contributor to weekly PA, whereas sitting time was paradoxically associated with higher MVPA. Specific measures to reduce sitting time are required to achieve an active lifestyle

Seroprevalencia de la toxoplasmosis humana en Córdoba

Se realiza un estudio sobre seroprevalencia de la toxoplasmosis humana en Córdoba, mediante inmunofluorescencia indirecta y hemaglutinación indirecta. La muestra encuestada se compone de 443 sueros, 356 personas supuestamente sanas (estudiantes fundamentalmente) y 87, consideradas de “alto riesgo” (enfermos del Hospital “Reina Sofía”). La positividad obtenida para el total de la muestra ha sido del 43,79 % con IFI y 53,50 % para HAI. Con respecto al sexo, la prevalencia es superior en mujeres con un 54,36 % y 70,47 % con IFI y HAI, respectivamente, en varones el 38,43 % y 44,90 % para las mismas pruebas. En relación con la procedencia de la muestra, 31,lB % con IFI y 43,25 % para HAI sobre la población normal, en la de “alto riesgo” para ambas pruebas el 95,40 %. Entre ambas pruebas hay diferencias significativas a títulos bajos, no así en diluciones altas, Concluimos que la toxoplasmosis humana está presente y difundida en las poblaciones estudiadasA seroprevalency study of human toxoplasmosis was carried out in Córdoba, using indirect immunofluorescence and indirect haemoglutination. The sample of people interviewed was made up of 443 serums, 356 supposedly healthy people (mainly students) and 87, considered “high risk” (pafients from the “Reina Sofia” Hospital). The positiveness obtained for the total of the sample was 43,79 % with IFI and 53,59 % for HAI. As regards sex of the person tested, prevalence is higher in women, with 54,36 % and 70,47 % with IFI and HAI respectively, in men the scores were 38,43 % and 44,90 % for the same tests. As far as the origin of the sample was concerned, there were 31,lB % with IFI and 43,25 % for HAI of the nornal population, in the “high risk” sample, for both tests it was 9540 %. With both tests there are significative differences in low amounts, but not in high dilutions. We conclude that human toxoplasmosis is present and widespread in the studied population