Abstract
(1) Background: The repercussions of work environments were widely studied before the pandemic. However, there are still many difficulties to be discovered considering the impact generated by it. Thus, this study aimed to analyse the impact of COVID-19 on nursing practice environments and nurses' job satisfaction. (2) Methods: A correlational study was conducted in a hospital in northern Portugal, with the participation of 416 registered nurses. Data were collected in June 2021 through questionnaires. The study was approved by the Institutional Ethics Committee. (3) Results: COVID-19 had a favourable impact on the structure component of the practice environments; the process component decreased compared to the pre-pandemic period; the outcome component remained moderately favourable to the quality of care. Nurses were not very satisfied or not at all satisfied with their valuation and remuneration; moderately satisfied with the leadership and staffing; and satisfied with the organisation and resources, co-workers and valuation by patients and families. In more favourable environments, nurses' job satisfactions were higher. (4) Conclusions: Identifying the dimensions with the best and worst scores allowed the institution's managers to concentrate efforts on where improvements were needed, thus preparing professional contexts for the recovery of care activities.

Abstract
Many time series exhibit conditional heteroscedasticity such as stock prices or returns, interest rates or exchange rates. Time series used in empirical analysis are often temporal aggregates. We study the effects of using temporally aggregated time series in testing for heteroscedasticity. The distribution of the test statistics is affected by aggregation which causes a severe power loss that worsens with the order of aggregation. Thus, the tests often fail to detect the heteroscedastic nature of the data which is a misleading outcome and can entail wrong decisions. Our conclusions are illustrated by an empirical application.

Abstract
Aim To analyse the impact of COVID-19 on professional nursing practice environments and patient safety culture. Background The relationship between work environments and patient safety has been internationally recognized. In 2020, the pandemic imposed enormous challenges, yet the impact on these variables remains unknown. Method This is a quantitative observational study, conducted in a Portuguese hospital, with 403 registered nurses. A self-completion questionnaire was used. Results The impact on the Structure and Outcome components of nursing professional practice environments was positive. Although the Process component remained favourable to quality of care, a negative trend was confirmed in almost all dimensions. The results regarding safety culture showed weaknesses; 'teamwork within units' was the only dimension that maintained a positive culture. Conclusion Positive responses regarding patient safety were significantly associated with the quality of the nursing professional practice environment. The need to invest in all dimensions of safety culture emerges to promote positive professional environments. Implications for nursing management Improving professional nursing practice environments can be achieved through managers' investment in the participation and involvement of nurses in the policies and functioning of institutions, as well as promoting an open, fair and participatory safety culture that encourages reporting events and provides adequate support for professionals.

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Abstract
The use of industrial by-products to produce new types of cement-substitute binders is gaining significant momentum, particularly through the alkaline activation technique. However, the exact curing conditions that should be considered with each binder variation have not been fully understood yet. The aim of the present work is thus the statistical analysis of the effects of curing conditions (humidity and temperature) on the mechanical response (uniaxial compression strength and elastic modulus) of different aggregate/binder weight ratios. Five blends of solid mine tailings (as an aggregate) and fly ash (as a precursor), both collected from the Portuguese industry, were activated with sodium hydroxide solution and cured under nine different temperature and humidity combinations. The data analysis was performed using multivariate analysis of variance and analysis of variance, followed by Tukey's post hoc test, whenever appropriate. Results show that the curing humidity factor showed a lower impact than the curing temperature. Although the increase in temperature and decrease in humidity produced higher compression strengths, the best results were obtained with a specific combination of both (60 degrees C and 50% relative humidity). In general, the increase in tailings' content produced a reduction in compression strength, but only for values above 20% (by weight of the sum of solids).