National Distance Education University
Recent publications
Children’s performance in arithmetic word problems (AWPs) predicts their academic success and their future employment and earnings in adulthood. Understanding the nature and difficulties of interpreting and solving AWPs is important for theoretical, educational, and social reasons. We investigated the relation between primary school children’s performance in different types of AWPs and their basic cognitive abilities (reading comprehension, fluid intelligence, inhibition, and updating processes). The study involved 182 fourth- and fifth-graders. Participants were administered an AWP-solving task and other tasks assessing fluid intelligence, reading comprehension, inhibition, and updating. The AWP-solving task included comparison problems incorporating either the adverb more than or the adverb less than, which demand consistent or inconsistent operations of addition or subtraction. The results showed that consistent problems were easier than inconsistent problems. Efficiency in solving inconsistent problems is related to inhibition and updating. Moreover, our results seem to indicate that the consistency effect is related to updating processes’ efficiency. Path analyses showed that reading comprehension was the most important predictor of AWP-solving accuracy. Moreover, both executive functions—updating and inhibition—had a distinct and significant effect on AWP accuracy. Fluid intelligence had both direct and indirect effects, mediated by reading comprehension, on the overall measure of AWP performance. These domain-general factors are important factors in explaining children’s performance in solving consistent and inconsistent AWPs.
The dependence on fossil resources remains high, accounting for 80% of the total primary energy production worldwide. In addition, the COVID-19 pandemic has devastated several industries and electric power is no exception. Therefore, renewable energy sources have become an important aspect of the energy sector, contributing to solutions to environmental problems and the development of a sustainable future. Therefore, this study proposes a model to evaluate the energy autonomy of a photovoltaic microgrid (EAPV,MG) using a battery energy storage system (BESS). To carry out the analysis, the energy consumption history of a residence and the solar irradiation data of the location were used. Thus, this study includes the evaluation of the energy compensation of a photovoltaic microgrid that directly injects energy into the residence, and the surplus is stored in a BESS for later use. The results show the relevance of EAPV,MG modeling for optimal system sizing. The model determines the autonomy of the microgrid without many power variations in the PV system for January, April, and October, corresponding to the summer, autumn, and spring seasons, respectively. However, in July (winter), the photovoltaic MG must increase the installation power considerably and the storage capacity of the BESS. Therefore, an optimal decision evaluating the EAPV,MG will allow broadening an overview to opt for a PV microgrid that injects the highest amount of energy based on the actual residential load profile and the optimal capacity of the BESS. Consequently, the analysis of the EA of a microgrid based on solar irradiation and actual load data is essential for developing an optimal and stable operation of the residential energy system.
Purpose The study focuses on the use of surfactants as enhancing solutions in electrokinetic remediation trials on sediments, with the hypothesis that they will allow heavy metals to desorb from organic matter, and thus favour their removal to the solution. Materials and methods A total of 15 remediation trials were conducted. As enhancing solutions, four different non-ionic commercial surfactants were used, either alone or in combination with citric acid (CA) or ethylenediaminetetraacetic acid (EDTA) in both compartments. A comparison with distilled water was also performed. 30–40 VDC was applied between activated titanium electrodes. The pH, electroosmotic flow (EOF), mineralogy of the samples (before and after the electrokinetic tests), and the percentage of removal of Cr, Ni, Cu, Zn, As, Cd, Pb, and Hg were determined. Results and discussion Every test showed an increase in current intensity during the first hours, and in certain cases, additional intensity peaks were found during the trial, which were mostly attributed to the establishment of EOF episodes. Depending on the case, EOF was transferred to the anolyte or the catholyte. Reversal of EOF occurred in one case, but was not detected in the others. Cr was primarily removed when CA was used. In the catholite, Ni, Cu, Zn, and Pb were extracted preferentially with EDTA. Surfactant B was more effective at removing Zn and As. Only a few treatments removed Cd with CA and surfactant C extracting the most. Hg was detected in the electrolytes of some experiments, being extracted with surfactant A in the catholyte in all cases, and with surfactant B and surfactant C with EDTA. Cr, Ni, Cu, Zn, Cd, and Pb were preferentially collected in the anolyte. Cu and Zn were found in trace levels in the catholyte. Conclusions Surfactants have been shown to help with metal solubilisation to different degrees depending on the metal. Each metal has a unique optimal species combination in the enhancing electrolyte. The direction of the EOF is determined by the chemical conditions of the system as a whole, not by the type of surfactant. Surfactants in combination with CA and EDTA improve desorption in general, which has been attributed to an increase in charge density passed during the tests rather than a symbiotic enhancement between both types of enhancing solutions.
Background Following the active ageing model based on the Health, Lifelong Learning, Participation and Security pillars, this research has a twofold objective: i) to classify older adults according to active ageing profiles, taking into account the four pillars, and ii) to ascertain the relationship between the profiles and personal and contextual factors, as well as well-being and quality of life in old age. Methods A study sample of 5,566 Spanish older adults who participated in wave 6 of the Survey of Health, Ageing and Retirement in Europe (SHARE) was included. Data were analysed in different steps applying several statistical analyses (Principal Component, Cluster, Discriminant, Multiple Correspondence and bivariate analysis with Pearson chi-square and ANOVA). Results Five older adult profiles were obtained (I: with moderate activity; II: quasi-dependents; III: with active ageing-limiting conditions; IV: with diverse and balanced activity; V: with excellent active ageing conditions). The first three profiles were characterised by subjects with a high average age, low educational level, who were retired or housewives, and who perceived a moderate level of loneliness, satisfaction with the social network and quality of life, as well as having a larger family network, but living in small households or alone. In contrast, the latter two profiles showed better personal and contextual conditions, well-being and quality of life. Discussion and conclusions The multidimensional approach to active ageing followed in this article has revealed the presence of several older adult profiles, which are confined to groups with better or worse active ageing conditions. In this context, if ageing is a process that reflects the previous way of life, intervention priorities will have to consider actions that promote better conditions during the life cycle.
The aim of this study is to expand our knowledge about the factors that condition late-life loneliness from a longitudinal perspective. We assess the long-term relationship between education, late-life loneliness and family trajectories in terms of the role of partnership and motherhood, as well as their timing for older women. We set two initial hypotheses: (1) family trajectory has a mediating effect and (2) education has a selection effect. Cross-sectional and retrospective data are drawn from the three waves of the SHARE survey (3rd, 5th and 7th waves), selecting a subsample of women aged 65 and over from 11 European countries (N = 10,615). After distinguishing eight different family trajectories by carrying out a Sequence Analysis, the Karlson-Holm-Breen method is used to assess the mediator effect of family trajectory on the relationship between education and loneliness. Multinomial analysis is used to explore whether the probability of different family trajectories of older European women is defined by their level of education. Our results show that education has a selection effect on family trajectories: a higher educational level increases the probability of a non-standardised family trajectory. Significant results of the mediator effect of family trajectory are however only observed for women with medium-level education, as being single and childless at older ages increases the probability of loneliness among these women. Adopting a life-course perspective has permitted us to introduce the longitudinal dimensions of life events, education and family trajectories to the study of feelings of loneliness among women in old age.
Live Fuel Moisture Content (LFMC) is one of the main factors affecting forest ignitability as it determines the availability of existing live fuel to burn. Currently, LFMC is monitored through spectral vegetation indices or inferred from meteorological drought indices. While useful, neither approach provides mechanistic insights into species-specific LFMC variation and they are limited in the ability to forecast LFMC under altered future climates. Here, we developed a semi-mechanistic model to predict daily variation in LFMC across woody species from different functional types by adjusting a soil water balance model which estimates predawn leaf water potential (Ψpd). Our overarching goal was to balance the trade-off between biological realism, which enhances model applicability, and parameterization complexity, which may limit its value within operational settings. After calibration, model predictions were validated against a dataset comprising 1659 LFMC observations across peninsular Spain, belonging to different functional types and from contrasting climates. The overall goodness of fit for our model (R² = 0.5) was better than that obtained by an existing models based on drought indices (R² = 0.3) or spectral vegetation indices (R² = 0.1). We observed the best predictive performance for seeding shrubs (R² = 0.6) followed by trees (R² = 0.5) and resprouting shrubs (R² = 0.4). Through its relatively simple parameterization, the approach developed here may pave the way for a new generation of process-based models that can be used for operational purposes within fire risk mitigation scenarios.
We study the stability of set-valued optimization problems by using epi-convergence coupled with asymptotic analysis. To do this, we recall the notion of epi-convergence and introduce the notion of total epi-convergence for set-valued maps. We characterize them by means of epi-limits and horizon epi-limits. We use these epi-limits to study the behavior of vector/set type solutions and level/colevel sets under variations of the whole data. We also introduce several stronger epi-convergence notions and use them to study the stability of solution sets and minimal solution sets. We extend and generalize various results from the literature since we deal with unbounded feasible sets and objective maps. Finally, to illustrate our main results, we apply them to various classes of set-valued maps.
Flooding and drought stress are expected to increase significantly across the world and plant responses to these abiotic changes may be mediated by plant‐plant interactions. Stress tolerance and recovery often requires a biomass investment that may have consequences for these plant‐plant interactions. We, therefore, questioned whether phenotypic plasticity in response to flooding and drought affected the balance between competition and facilitation for species with specific adaptations to drought or flooding. Utrecht University For six species, stem elongation, root porosity, root:shoot ratio and biomass production were measured during drought, well‐drained and submerged conditions when grown alone or together with conspecifics. We quantified competition and facilitation as the ‘neighbour intensity effect’ directly after the ten‐day treatment and again after a seven‐day recovery period in well‐drained conditions. Water stress, planting density and species identity interactively affected standardized stem elongation in a way that could lead to facilitation during submergence for species that preferably grow in wet soils. Root porosity was affected by the interaction between neighbour presence and time‐step. Plant traits were only minorly affected during drought. The calculated neighbour interaction effect indicated facilitation for wetland species during submerged conditions and after a recovery period from flooding for species that prefer dry habitats. Our results imply that changing plant‐plant interactions in response to submergence and to a lesser extent to drought should be considered when predicting vegetation dynamics due to changing hydroclimatic regimes. Moreover, facilitation during a recovery period may enable species mal‐adapted to flooding to persist.
Objectives: To examine gender-related differences in the management and survival of out-of-hospital cardiac arrest (OHCA) in Spain during 2 time series. Material and methods: Analysis of data recorded in the prospective Spanish OHCA registry (OHSCAR in its Spanish acronym) for 2 time series (2013-2014 and 2017-2018). We included all 11 036 consecutive cases in which an emergency team intervened. The dependent variables were arrival at the hospital after return of spontaneous circulation, overall survival to discharge, and overall survival with good neurological outcomes. Sex was the independent variable. We report descriptive statistics, patient group comparisons, and changes over time. Results: Women were significantly older and less likely to experience an OHCA in a public place, receive automatic external defibrillation, have a shockable heart rhythm, and be attended by an ambulance team within 15 minutes. In addition, fewer women underwent percutaneous coronary interventions or received treatment for hypothermia on admission to the hospital. In 2013-2014 and 2017-2018, respectively, the likelihood of survival was lower for women than men on admission (odds ratio [OR], 0.52 vs OR, 0.61; P .001 and P = .009 in the 2 time series) and at discharge (OR, 0.69 vs 0.72 for men; P = .001 in both time series). Survival with good neurological outcomes was also less likely in women (OR, 0.50 vs 0.63; P .001 in both series). Conclusion: The odds for survival and survival with good neurological outcomes were lower for women in nearly all patient groups in both time series. These findings suggest the need to adopt new approaches to address gender differences in OHCA.
This article discusses how the COVID-19 pandemic impacted my anthropological research inquiry of care among mental health professionals at a community shelter and a psychiatric hospital in Equatorial Guinea. The rapidly evolving changes required the methods of digital anthropology, which allowed an understanding of embodiments of care. Under volatile conditions and intersections between the personal and the public, mental health professionals carried and invested care in communities and (re)discovered new challenges and vulnerabilities. Medical agencies revealed symbolic roles, meanings, and qualities of care. This article proposes opportunities for the discipline of public anthropology to serve as a medium for the engagement of collective solutions. [anthropology, mental health care, Equatorial Guinea, COVID-19]
Die Corona-Pandemie hat eine unumstrittene Auswirkung auf unser Zusammenleben. Auch Schulen und LehrerInnen mussten sich in kürzester Zeit auf die neuen Umstände einstellen. In diesem Kontext sind viele LehrerInnen in sozialen Medien aktiv geworden, um relevante und praxis-orientierte Informationen zu sammeln und sich untereinander auszutauschen. Es ist jedoch kaum etwas darüber bekannt, wie sich LehrerInnen in sozialen Medien verhalten und welche entsprechende Prozesse und Inhalte dabei zugrunde liegen. Dieser Beitrag adressiert dieses Manko und untersucht wie LehrerInnen auf soziale Medien zugreifen und COVID-19-relatierte Informationen austauschen. Hierzu wurden die Twitter-Profile von 97 amerikanischen LehrerInnen in den Vereinigten Staaten gesammelt und analysiert. Basierend auf sozialen Netzwerkanalysen und bibliometrischen Analysen zeigen unsere Ergebnisse, dass sich LehrerInnen verstärkt auf Twitter austauschten und sich thematisch mit relevanten Themen auseinandersetzten.
The explanation of underachievement and the search for its associated factors have been of constant interest in educational research. In this regard, the number of variables that have been involved in its description and explanation has increased over the years, as has the number of studies at an international level on this topic. Although much research has focused on identifying the personal, family, and school aspects that exert the greatest influence on students’ low academic performance, the literature shows the need to study the differential effects of said variables according to the countries in which the studies are conducted. The objective of this article is therefore to analyse cross-national differences in the effect of personal, family, and school characteristics on students’ academic underachievement based on data derived from the Programme for International Student Assessment (PISA) 2018. Furthermore, it aims to identify the profile that characterises students with the lowest academic performance and to estimate the importance of the selected variables in explaining low achievement across countries. To reach these goals, the multivariate technique of decision trees through the binary CART (Classification and Regression Trees) algorithm was used, allowing the estimation of both a global model and nine specific models for each of the selected countries. The results show that, despite slight differences between the countries analysed, the variables that define the general profile of students with the lowest achievement and which have shown the strongest predictive capacity for low performance are mainly linked to the students themselves. These variables are followed in importance by family aspects, which present great differences between the territories that compose the sample. Finally, teacher and school variables have shown to have a low explanatory capacity in this study. It can therefore be concluded that, although personal characteristics continue to be those that best explain academic performance, a series of contextual variables, especially related to families, appear to influence academic achievement differentially and may even hide or cancel out certain personal characteristics.
Microplastic (MP) ingestion, along with accumulated plasticizers such as bisphenol A (BPA), bisphenol F (BPF), and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP), were quantified in bivalves, fish, and holothurians collected from a coastal pristine area at the western Mediterranean Sea. MP ingestion in sediment-feeders holothurians (mean value 12.67 ± 7.31 MPs/individual) was statistically higher than ingestion in bivalves and fish (mean 4.83 ± 5.35 and 3 ± 4.44 MPs/individual, respectively). The main ingested polymers were polyethylene, polypropylene, and polystyrene. The levels of BPS, BPF, and DEHP were highest in bivalves' soft tissue; BPA and DBP had the highest levels in the holothurians’ muscle. In addition, the levels of all plasticizers assessed were lowest in fish muscle; only BPA levels in fish were higher than in bivalves, with intermediate values between those of bivalves and holothurians. This study provides data on exposure to MPs and plasticizers of different species inhabiting Cabrera Marine Protected Area (MPA) and highlights the differences in MP ingestion and levels of plasticizers between species with different ecological characteristics and feeding strategies.
Two studies were carried out on a Spanish population to explore the extent to which different self-efficacy beliefs in managing positive emotions are associated with common indicators of wellbeing, such as positive and negative affect or life satisfaction. The first study was conducted on 483 participants and attested to the factorial structure of three different self-efficacy beliefs: (a) perceived self-efficacy in expressing positive emotions; (b) perceived self-efficacy in retrieving memories of positive emotional experiences; and (c) perceived self-efficacy in using humor. The second study was carried out on 1,087 individuals between 19 and 80 years of age, and it provided evidence of the factorial invariance of the scales across age and gender. Furthermore, this latter study showed the association of self-efficacy in managing positive affect (SEMPA) with high chronic positive and low negative affect, and with high life satisfaction, controlling for gender and age. In younger participants, stronger associations were found between perceived self-efficacy in using humor and life satisfaction compared to older subjects. These findings may guide the design of interventions aimed at enhancing the potential benefits that could be drawn from the proper management of positive emotions.
A principal animal paradigm employed in Anorexia Nervosa (AN) study is the activity-based anorexia (ABA) model. The model's efficacy in recapitulating the core features of AN in humans allows for the study of the parameters involved in the disorder. The current study examined the susceptibility to the ABA protocol in the presence of a significant stressor (maternal separation) in male and female Sprague Dawley rats. More importantly, we analysed the sex-differences on activity levels during different periods of the ABA protocol to determine the period(s) influencing the most pathological weight loss. Both components of the ABA protocol contributed to the subjects’ bodyweight loss. Stress in the first two weeks of development conferred a protective effect in males. Time spent and activity levels on the running wheel were higher in females compared to males. Hyperactivity in ABA subjects was observed during the food-anticipatory activity (FAA) and postprandial activity in males and during the FAA and nocturnal activity periods in females. This study aids in understanding the effect of intensity of activity during specific periods on the pathological weight loss in ABA rats. These observations are informative for therapies aimed at ameliorating body mass index in AN patients.
El tránsito desde el imperio americano de la monarquía hispánica a nación liberal se analiza a través de la dilatada biografía pública de Narciso Heredia, conde de Ofalia, entre 1801 y 1841. Caracterizado como “realista moderado”, partidario de reformas administrativas y de la preservación de la integridad del Imperio, Ofalia terminó adaptándose al tránsito hacia la monarquía parlamentaria, aceptando finalmente la emancipación de Iberoamérica. A pesar de su protagonismo durante la década absolutista y el régimen del Estatuto Real, no encabezó más que brevemente el Consejo de Ministros en 1824 y 1837-1838. Enfrentó también el expansionismo de Estados Unidos durante las primeras décadas del siglo XIX. This article analyses the transition from the Spanish monarchy’s American empire to a liberal nation by way of the extensive public biography of Narciso Heredia, Count of Ofalia, between 1801 and 1841. Characterized as a “moderate realist”, a supporter of administrative reforms and the preservation of the integrity of the Empire, Ofalia eventually adapted to the transition towards parliamentary monarchy, finally accepting the emancipation of Latin America. Despite his prominence during Ferdinand VII’s decade of absolutism and the regime of the Royal Statute that followed, he only briefly headed the Council of Ministers in 1824 and 1837–1838. He also confronted the expansionism of the United States during the early decades of the 19th century.
In this work we studied, within DFT, the interaction of NO with pure and oxidized Ag n , both anionic and cationic, composed from11 to 13 Ag atoms. In that size interval, shell closing effects are not expected, and structural and electronic odd-even effects will determine the strength of interaction. We obtained that species Ag n {plus minus} and Ag n O {plus minus} with odd number of electrons (n=12) adsorb NO with higher energy than their neighbours. This result agrees with the facts observed in recent mass spectroscopy measurements, which were performed at finite temperature. The adsorption energy is about twice for oxidized clusters compared to pure ones, and higher for anions than for cations. The adsorption of another NO molecule on Ag n NO {plus minus} forms Ag n (NO) 2 {plus minus} , with the dimer (NO) 2 in cis configuration, and binding the two N atoms with two neigbour Ag atoms. The n=12 show the higher adsorption energy again. In absence of reaction barriers, Ag n (NO) 2 {plus minus} dissociate spontaneously into Ag n O {plus minus} and N 2 O, except the n= 12 anion. The máximum high barrier along the dissociation path of Ag 13 (NO) 2 ⁻ is about 0.7 eV. Further analysis of PDOS for Ag11-13 (NO) x {plus minus} (x=0,1,2) molecules shows that bonding between NO and Ag n mainly occurs in the range between -3.0 eV and 3.0 eV. The overlap between 4 d of Ag and 2 p of N and O is larger for Ag 12 (NO) 2 {plus minus} than for neighbour sizes. For n=12, the d bands are close to the (NO) 2 2π orbital, leading to extra back-donation charge from the 4 d of Ag to the closer 2π orbital of (NO) 2 .
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
10,282 members
Miguel Bernabé
  • Psicologia Social y de las Organizaciones
Juan del Rosal 10, 28002, Madrid, Spain