Strong Self-regulation Research Articles

The Role of Academic Motivation in Self-Regulation, Goal Orientation, and Passion Among Medical Students with Self-Handicapping Behaviors

Background: Self-handicapping behaviors, characterized by creating obstacles or excuses to avoid failure, can hinder academic success. Understanding how academic motivation mediates the relationship between self-handicapping behaviors and academic performance is crucial for supporting medical students. Objectives: This study aimed to investigate the relationships between academic self-regulation, goal orientation, passion, and self-handicapping behaviors among medical students, with academic motivation as a potential mediator. Methods: The present study employed a descriptive, correlational approach to examine the relationships between variables within a structural equation modeling (SEM) framework. The population consisted of all undergraduate medical students with self-handicapping behaviors at Jundishapur University of Medical Sciences in 2022. The sample comprised 204 medical students selected using purposive sampling, who completed the Academic Passion Scale, Goal Orientation Scale, Academic Self-Regulation Scale, and Academic Motivation Scale. Structural equation modeling was used to analyze the model with AMOS 24. Results: The SEM analysis revealed that the proposed model had a good fit to the data (CFI = 0.96, RMSEA = 0.05). The results further demonstrated that goal orientation directly enhanced students' academic passion, while academic self-regulation did not have a direct impact. However, strong self-regulation indirectly increased passion by fostering academic motivation (P < 0.001). Similarly, goal orientation also worked indirectly through motivation to enhance academic passion (P < 0.05). Conclusions: This study underscores the importance of goal setting and academic motivation in fostering academic passion among medical students with self-handicapping behaviors. While academic self-regulation strategies may not directly translate to academic passion, they can contribute indirectly by fostering academic motivation. Educators and practitioners can promote academic passion and address self-handicapping behaviors in medical students by encouraging goal orientation, academic motivation, self-regulation, and providing support for overcoming challenges.

Adverse Childhood Experiences, Protective Factors, and Childhood Obesity: Comparing the Effectiveness of Three Resilience Frameworks

Abstract While rates of childhood obesity continue to rise in the United States, multiple studies have linked childhood obesity to adverse childhood experiences (ACEs). ACEs researchers have begun to develop frameworks that identify protective factors that build resilience against ACEs. However, these frameworks have a limited evidence base. Utilizing data from the 2018–2020 National Survey of Children’s Health, this study compared the effectiveness of the National Scientific Council on the Developing Child (NSCDC), Health Outcomes from Positive Experiences (HOPE), and cumulative positive childhood experiences (PCEs) frameworks in mitigating the impact of ACEs on childhood obesity. Based on hierarchical logistic regression conducted on data from 46,672 children between the ages of 10 and 17 years old, this study found that both the NSCDC and HOPE frameworks were associated with childhood obesity, with each framework explaining a similar amount of variance in childhood obesity across analyses. The cumulative PCEs framework did not strengthen the association between either framework and childhood obesity. Across analyses, strong self-regulation, mastery/after-school activities, and living in a supportive neighborhood had the strongest association with childhood obesity. The findings suggest that the most salient protective factors may be those most closely associated with the direct causes of childhood obesity, with the need to identify factors across ecological levels. Future research is needed to validate these frameworks further and explore these frameworks with other outcomes. The findings have important implications for future ACEs research and ACEs interventions. Public Relevance By understanding which resilience frameworks and protective factors have the strongest relationship with childhood obesity among children who experienced ACEs, interventions can potentially be developed using these findings to mitigate the harmful impact of ACEs on childhood obesity. Key Findings This study found that the National Scientific Council on the Developing Child (NSCDC) and Health Outcomes from Positive Experiences (HOPE) frameworks were associated with childhood obesity after controlling for adverse childhood experiences (ACEs) in a sample of children between the ages of 10 and 17 years old. The strongest protective factors against childhood obesity were strong self-regulation, mastery/after-school activities, and living in a supportive neighborhood. Given the relationship between these protective factors along with several covariates in the study with childhood obesity, future ACEs interventions should potentially target these protective factors and other social determinants of health to reduce the negative impact of ACEs on childhood obesity.

Development of temperament types from infancy to adolescence: Genetic and environmental influences with an economically and racially/ethnically diverse sample.

Kagan theorized biologically based temperament types that are present in infancy, stable across development, and essential for understanding individual differences. Despite evidence, temperament research remains focused on a few prominent dimensions of temperament, without adequately addressing covariance among dimensions and temperament types. Using longitudinal twin data, we took a person-centered statistical approach to identify temperament types and examined continuity and change across five developmental periods (Ninfancy = 602; Ntoddlerhood = 522; Nearly childhood = 390; Nlate childhood = 718; Nearly adolescence = 700). We then examined the genetic and environmental etiology of temperament types. Twins were boys and girls (51-53% female), primarily Hispanic/Latinx (23-30%) and non-Hispanic/Latinx White (56-63%), and from socioeconomically diverse families (28-38% near-or-below the poverty line). Using latent profile analysis, we identified three temperament types at each age characterized by negative reactivity and dysregulation, positive reactivity and strong self-regulation, and moderate reactivity and regulation. Latent transition analyses revealed considerable continuity in membership type for "negative dysregulated" beginning in infancy, log odds = 1.58 (SE = .65) to 3.16 (SE = .77), p < .01, of remaining relative to transitioning to "typical expressive", and "positive well-regulated" beginning in early childhood, log odds = 1.41 (SE = .56) to 2.25 (SE = .47), p < .05. Twin analyses revealed moderate heritability and a consistent role of the shared environment on positive well-regulated, with negative dysregulated and typical expressive also moderately heritable with the shared environment being important at some ages. Findings support the presence of theorized biologically based temperament types that develop rapidly in infancy and toddlerhood and provide a foundation for the study of individual differences and risk and resilience processes across the lifespan. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The Moderated-Mediated Influence of TikTok, Facebook, and Twitter Usage Alongside Psychological Factors on Academic Achievement among Botho University Students in Botswana: Examining the Role of Self-Regulation and Personal Profile

The evolving digital landscape underscores the need to investigate the influence of social media on academic performance. This study examines the intricate relationship between social media use—specifically on TikTok, Facebook, and Twitter—and the academic performance of university students in Botswana. Exploring the roles of psychological traits, self-control, and individual profiles as moderators and mediators in this correlation, the research emphasizes the pivotal influence of these factors in shaping how social media impacts academic performance. The primary objective is to scrutinize both the direct and indirect effects of social media use on student performance, evaluating how self-directed regulation mechanisms can mitigate adverse effects. Employing a quantitative approach, the study analyzed survey data from 55 undergraduate students at Botho University in Botswana, recruited through convenience sampling. While the sample size was constrained by practical limitations, the study offers initial insights to be further explored in future research with larger samples. Utilizing descriptive statistics, correlation, and regression analysis, the research investigated usage patterns, perceived impacts, and self-regulation techniques. Findings reveal a robust link between extensive social media use and varied academic performance, influenced significantly by individual self-regulation skills and psychological traits. Notably, strong self-regulation techniques were associated with reduced negative academic consequences, highlighting the crucial role of human control in digital engagement. The study illuminates how social media can serve as both a distraction and a valuable teaching tool, shaped by individual characteristics. It recommends future research focus on specific interventions aimed at enhancing self-regulation abilities to maximize the educational benefits of social media while minimizing drawbacks. This research contributes to a deeper understanding of digital media's impact in educational settings, providing valuable insights for educators, policymakers, and students navigating the challenges of academic success in the digital era.

Cunninghamia lanceolata (Lambert) Hooker: A Promising Candidate for Phytoremediation of Cd-Contaminated Soils

Cadmium (Cd) is one of the most common toxic heavy metal elements in soil pollution, which can be continuously enriched in the food chain and eventually threaten human health. Phytoremediation, which is using plants to transfer heavy metal elements from soils, is a promising solution for the remediation of heavy metal-contaminated soils. In this study, we evaluated whether Cunninghamia lanceolata (Lambert) Hooker (Chinese fir), a widely planted timber tree worldwide, had the potential to remediate Cd-contaminated soils through 90 days pot of experiments with different Cd concentration soils (0, 5, 10, 20, 50, 100 mg kg−1). C. lanceolata did not show obvious toxic symptoms in Cd-contaminated soils, although Cd inhibited plant growth and decreased net photosynthetic rate slightly. The activities of antioxidant enzymes increased significantly under Cd stress, indicating that C. lanceolata had a strong self-regulation ability and can tolerate Cd stress. The Cd bioconcentration factor (Cd concentration in plant divided by Cd concentration in soil) of C. lanceolata were greater than 1 at all Cd concentrations, indicating that C. lanceolata had a strong ability to absorb Cd, although Cd was mainly accumulated in roots. Our results indicated that C. lanceolata had a strong tolerance and phytostabilization ability of Cd. Considering the wide distribution worldwide, large biomass, and rapid growth of C. lanceolata, it could be a promising candidate for phytoremediation of Cd-contaminated soils.

Stable diverse food webs become more common when interactions are more biologically constrained

Ecologists have long sought to understand how diversity and structure mediate the stability of whole ecosystems. For high-diversity food webs, the interactions between species are typically represented using matrices with randomly chosen interaction strengths. Unfortunately, this procedure tends to produce ecological systems with no underlying equilibrium solution, and so ecological inferences from this approach may be biased by nonbiological outcomes. Using recent computationally efficient methodological advances from metabolic networks, we employ for the first time an inverse approach to diversity-stability research. We compare classical random interaction matrices of realistic food web topology (hereafter the classical model) to feasible, biologically constrained, webs produced using the inverse approach. We show that an energetically constrained feasible model yields a far higher proportion of stable high-diversity webs than the classical random matrix approach. When we examine the energetically constrained interaction strength distributions of these matrix models, we find that although these diverse webs have consistent negative self-regulation, they do not require strong self-regulation to persist. These energetically constrained diverse webs instead show an increasing preponderance of weak interactions that are known to increase local stability. Further examination shows that some of these weak interactions naturally appear to arise in the model food webs from a constraint-generated realistic generalist-specialist trade-off, whereby generalist predators have weaker interactions than more specialized species. Additionally, the inverse technique we present here has enormous promise for understanding the role of the biological structure behind stable high-diversity webs and for linking empirical data to the theory.

Using Gamification to Facilitate Students’ Self-Regulation in E-Learning: A Case Study on Students’ L2 English Learning

E-learning has been an important learning approach in the information era by providing flexible environments and rich resources for learners. However, it also faces several challenges, the biggest one being that students need to have strong self-regulation competence to control and manage their e-learning. As gamification has been widely used in primary education to facilitate children’s learning motivation and engagement, it is valuable to explore the impacts of gamification on children’s self-regulated learning. In this study, the role of gamification in children’s English learning in Hong Kong was investigated through a gamified e-learning system. A quasi-experiment with pre-test/post-test design was conducted among primary level 3 students over a semester. Both quantitative and qualitative data were gathered through academic tests, questionnaires, and interviews to provide comprehensive insights into the research questions. The key findings enable the identification of: (1) students’ gaining of self-regulated learning interest and academic performance from the gamified learning system; (2) students’ developed self-regulated learning strategies; and (3) the connection between gamification and students’ self-regulated learning. These findings have implications for e-learning designers and educators with regards to the practice of gamified learning to enhance students’ self-regulated learning and second language learning.

Symmetry-Breaking and Self-Sorting in Block Copolymer-Based Multicomponent Nanocomposites.

Co-assembly of inorganic nanoparticles (NPs) and nanostructured polymer matrix represents an intricate interplay of enthalpic or entropic forces. Particle size largely affects the phase behavior of the nanocomposite. Theoretical studies indicate that new morphologies would emerge when the particles become comparable to the soft matrix's size, but this has rarely been supported experimentally. By designing a multicomponent blend composed of NPs, block copolymer-based supramolecules, and small molecules, a 3-D ordered lattice beyond the native BCP's morphology was recently reported when the particle is larger than the microdomain of BCP. The blend can accommodate various formulation variables. In this paper, when the particle size equals the microdomain size, a symmetry-broken phase appears in a narrow range of particle sizes and compositions, which we named the "train track" structure. In this phase, the NPs aligned into a 3-D hexagonal lattice and packed asymmetrically along the c axis, making the projection of the ac and the bc plane resemble train tracks. Computational studies show that the broken symmetry reduces the polymer chain deformation and stabilizes the metastable hexagonally perforated lamellar morphology. Given the mobility of the multicomponent blend, the system shows a self-sorting behavior: segregating into two macroscopic phases with different nanostructures based on only a few nanometers NP size differences. Smaller NPs form "train track" morphology, while larger NPs form a "simple hexagon" structure, where the NPs take a symmetric hexagonal arrangement. Detailed structural evolution and simulation studies confirm the systematic-wide cooperativity across different components, indicating the strong self-regulation of the multicomponent system.

Factors Affecting Emotional Resilience in Adults

Emotional resilience may be seen as the ability of an individual to cope with adversities and bounce back from failures. Emotional resilience requires a high degree of self-awareness, strong self-regulation and a host of other attributes. Factors like stress, burnout, lack of social support and negative thinking are enemies of emotional resilience. Most of the existing models of emotional resilience deal with children, adolescents, the armed forces or patients. They do not take into account factors affecting emotional resilience of an adult in general. This article aims to study the concept of emotional resilience in adults, analyse key factors affecting the same and propose a new theoretical model of emotional resilience for adults. In addition, based on the literature and experiential knowledge of the authors, this article seeks to develop 12 propositions based on the antecedents of emotional resilience in adults.

Breastfeeding, Early Self-Regulation, and Academic Achievement in Kindergarten Among Disadvantaged Children.

The importance of breastfeeding exposure and children's development of self-regulation, independently, are well established. Each of these domains also has been linked to better cognitive development and academic achievement in children. However, little is known about how breastfeeding affects development of early self-regulation skills or whether self-regulation mediates the relationship between breastfeeding and academic achievement, particularly for disadvantaged children. This study examined breastfeeding exposure, self-regulation, and academic achievement in kindergarten among a population of children who previously attended Head Start. Children were recruited from Head Start classrooms in the Pacific Northwest. Breastfeeding exposure was assessed via parent report. Children's self-regulation (Day Night Stroop, Dimensional Change Card Sort, Head-Knees-Toes-Shoulders-Revised) and academic achievement [Letter-Word Identification and Applied Problems subtests of Woodcock Johnson Tests of Achievement (English) or the Batería III Woodcock-Muñoz (Spanish)] were directly assessed in fall and spring of kindergarten. Regressions were performed using Stata v14.1 and included breastfeeding exposure as the primary independent variable, controlling for child age, sex, and language spoken. Of the 246 children, 56% were reported as White, 34% Latino/a, 4% African American, and 6% other; 83% were ever exposed to breastfeeding. Breastfeeding exposure was predictive of both fall kindergarten academic achievement (emergent math/literacy scores) and self-regulation (p < 0.05) and related to higher math performance in the spring of kindergarten, which was associated with stronger self-regulation in the fall (p = 0.04). These findings extend our understanding of the positive effects of breastfeeding exposure on children's development and support breastfeeding promotion, particularly for children at risk of academic difficulty.

Where, When and With Whom: Cannabis Use, Settings and Self-Regulation Rules

This article examines to what extent and how cannabis users in different countries, with different cannabis legislation and policies practice normalization and self-regulation of cannabis use in everyday life. Data were collected in a survey among a convenience sample of 1,225 last-year cannabis users aged 18–40 from seven European countries, with cannabis policies ranging from relatively liberal to more punitive. Participants were recruited in or in the vicinity of Dutch coffeeshops. We assessed whether cannabis users experience and interpret formal control and informal social norms differently across countries with different cannabis policies. The findings suggest that many cannabis users set boundaries to control their use. Irrespective of national cannabis policy, using cannabis in private settings and setting risk avoidance rules were equally predominant in all countries. This illustrates that many cannabis users are concerned with responsible use, demonstrating the importance that they attach to discretion. Overall, self-regulation was highest in the most liberal country (the Netherlands). This indicates that liberalization does not automatically lead to chaotic or otherwise problematic use as critics of the policy have predicted, as the diminishing of formal control (law enforcement) is accompanied by increased importance of informal norms and stronger self-regulation. In understanding risk-management, societal tolerance of cannabis use seems more important than cross-national differences in cannabis policy. The setting of cannabis use and self-regulation rules were strongly associated with frequency of use. Daily users were less selective in choosing settings of use and less strict in self-regulation rules. Further differences in age, gender, and household status underline the relevance of a differentiated, more nuanced understanding of cannabis normalization.

Resilience Intervention to Strengthen Self-Regulation in Adolescent Students with Hearing Loss

Background: The importance of strong self-regulation (SR) abilities for academic and social success is known, yet relatively few studies examine students’ SR and how it can be promoted especially in adolescents with special needs, such as those students with hearing loss. The purpose of this study was to determine whether a resilience intervention program enhances SR in adolescents with hearing loss. Methods: This study was experimental with a pre-test, post-test, follow up and control group design. Participants included 122 students with hearing loss in mainstream settings randomly assigned to intervention and control groups (61 students in each group). The interventional group had training for six weeks (two times per week for 75 min). The Adolescent Self-Regulatory Inventory was used to measure the self-regulation of students. Results: The results indicated a significant difference between the control and interventional groups in SR, short SR, and Long SR after the intervention, at both the 6-week and 14-week measurements (p &lt; 0.001). Conclusion: This study’s findings indicate that implementing resilience intervention programs can promote the self-regulation skills in adolescent students with hearing loss.

The Role of Parent Self-Regulation in Youth Type 1 Diabetes Management.

Youth with strong self-regulation (SR), or the ability to manage thoughts, emotions, and behaviors, engage in more effective type 1 diabetes (T1D) management. However, while parent support and engagement are critical to ensuring positive youth T1D outcomes, it is rarely considered that parents' SR may also influence youth T1D management. If this is the case, novel interventions to improve parents' SR or ensure adequate support for parents with SR challenges offer great potential to improve family functioning and youth T1D management. Theoretical and preliminary empirical evidence suggests that parental SR impacts family processes that support youth T1D treatment regimen adherence. Furthermore, parent and youth SR likely interact, with high parent SR enhancing the positive effects of high youth SR or compensating for low youth SR. Continued research is needed to better understand the ways in which parent SR matters to youth T1D management and identify how to support improvements in T1D management among families of parents with low SR.

The Efficiency of Stock Exchange Self-Regulation: Evidence from Stock Market Liquidity and Transparency

This study examines whether and how stock exchange self-regulation affects stock market liquidity and corporate transparency. Using a large sample of firms from 46 stock exchanges from 2001 to 2015, we find significant and robust evidence that firms listed in self-regulated stock exchange are associated with fewer zero-return days, lower daily stock price variation, higher stock trading volume, smaller analyst forecast errors, lower discretionary accruals and less earnings management. These findings are more pronounced when the stock exchange has a strong self-regulation model rather than a limited self-regulation model. Also, our results are robust in different-in-difference tests based on the Australian Securities Exchange’s change from strong self-regulation model to a government regulation model. Further, when a firm from a country with a government-regulated stock exchange is cross-listed in a self-regulated stock exchange, the firm has higher liquidity and transparency than the matched firms. In addition, we find that self-regulated exchanges set more detailed insider trading and disclosure rules and are more transparent with their rules and rule enforcement. Overall, our study suggests that stock exchange self-regulation improves the efficiency of stock market regulation.

Self-regulation versus social influence for promoting cooperation on networks

Cooperation is a relevant and controversial phenomenon in human societies. Indeed, although it is widely recognized essential for tackling social dilemmas, finding suitable policies for promoting cooperation can be arduous and expensive. More often, it is driven by pre-established schemas based on norms and punishments. To overcome this paradigm, we highlight the interplay between the influence of social interactions on networks and spontaneous self-regulating mechanisms on individuals behavior. We show that the presence of these mechanisms in a prisoner’s dilemma game, may oppose the willingness of individuals to defect, thus allowing them to behave cooperatively, while interacting with others and taking conflicting decisions over time. These results are obtained by extending the Evolutionary Game Equations over Networks to account for self-regulating mechanisms. Specifically, we prove that players may partially or fully cooperate whether self-regulating mechanisms are sufficiently stronger than social pressure. The proposed model can explain unconditional cooperation (strong self-regulation) and unconditional defection (weak self-regulation). For intermediate self-regulation values, more complex behaviors are observed, such as mutual defection, recruiting (cooperate if others cooperate), exploitation of cooperators (defect if others cooperate) and altruism (cooperate if others defect). These phenomena result from dynamical transitions among different game structures, according to changes of system parameters and cooperation of neighboring players. Interestingly, we show that the topology of the network of connections among players is crucial when self-regulation, and the associated costs, are reasonably low. In particular, a population organized on a random network with a Scale-Free distribution of connections is more cooperative than on a network with an Erdös-Rényi distribution, and, in turn, with a regular one. These results highlight that social diversity, encoded within heterogeneous networks, is more effective for promoting cooperation.

Teacher burnout profiles and proactive strategies

Teacher burnout has been identified as a significant occupational hazard. However, our understanding about individual variations in burnout risk among in-service teachers is still less than sufficient. This study explored socio-contextual burnout risk profiles and their association with the reported use of proactive strategies among in-service teachers by using a person-oriented approach. The survey data were collected from 2310 Finnish in-service primary and lower secondary school teachers using a probability sampling method. In the latent profile analysis, five socio-contextual burnout profiles were identified. The profiles differed from each other in terms of burnout symptoms and proactive strategy use. Results suggested that there is individual variation in teachers’ risk of burnout. In addition, the results imply that well-developed proactive strategies, both in terms of self- and co-regulative strategies, are related to lower risk of experiencing socio-contextual burnout. The utilization of strong co-regulative strategies was related to lower risk of experiencing exhaustion and inadequacy during teacher-pupil interactions. However, strong self-regulation combined with low levels of co-regulation was related to an increased risk of experiencing cynicism. This implies that learning proactive strategies may be useful in preventing teacher burnout.

Grit in Online Education

Aim: This study sought to explore the role of the elusive non-cognitive skill set known as grit, or the resolve and determination to achieve goals regardless of impediments, on student success in online education. It represents an area of exploration where there is a dearth in the available literature and reports the results of a study conducted at a Mid-Atlantic minority-serving university that examined the relationship between grit and student performance in fully online courses.&#x0D; Methodology: Students were administered the standard 12-Question Grit Scale with the addition of a series of validated questions that sought to measure perceived self-learning efficacy. Additionally, student performances in online courses were recorded and correlations conducted. Basic statistical analyses such as mean, mode, standard deviation, variance, and confidence interval were calculated. Two hypotheses were introduced as part of this study and tested with Anovas and crosstabulations.&#x0D; Results: This study found that higher grit scores correlated progressively to both self-discipline and self-efficacy but that a positive relationship to student achievement in fully online courses as measured with a p value of greater than .05 could not be confirmed.&#x0D; Conclusion: As online education continues to grow, providing opportunities to foster and strengthen student success in online courses and programs is increasingly important. E-learning success requires that students exhibit strong self-regulation, self-discipline, resilience, dutifulness, conscientiousness, and low impulsivity all of which are attributes of grit. As such, grit is presented as a promising area of exploration for increasing student achievement in online education.

Effects of nitrogen addition on biomass allocation of Pinus koraiensis and Fraxinus mandshurica seedlings under water stress.

Nitrogen deposition and climate warming-drying are the main environmental changes in Northeast China. How they affect forest ecosystems has always been studied in ecological research. In this study, we explored the effects of water stress and nitrogen (N) addition on the short-term (in 55 weeks) growth of seedlings of Pinus koraiensis and Fraxinus mandshurica, two key species in broad-leaved and P. koraiensis mixed forests in temperate zone of Northeast China. Results showed that the responses of seedling growth of P. koraiensis and F. mandshurica to nitrogen addition and water stress were significantly different. P. koraiensis was more sensitive to water stress. In the early stage (in 10 weeks) of water stress, leaf biomass of P. koraiensis significantly decreased while the root biomass increased. Nitrogen addition significantly reduced the root and total biomass of P. koraiensis under water stress. F. mandshurica was more sensitive to N addition. Nitrogen addition rapidly increased the stem, root and total biomass of F. mandshurica. Only sustained water stress could significantly affect the stem, root and total biomass of F. mandshurica. Under continuous water stress and N addition, the biomass contribution of leaves and roots to whole seedling, and the ratio of aboveground to underground biomass of both species tended to be constant, indicating strong self-regulation ability of both species. The results suggested that when drought occurred in the future, P. koraiensis would adopt a "positive" adjustment strategy, while F. mandshurica would adopt a "passive" response. The survival rate and adaptability of P. koraiensis would be higher than F. mandshurica. F. mandshurica would benefit more from N deposition than P. koraiensis. Our results are helpful for predicting the changes of community structure in temperate forest in Northeast China.

How self-regulation, the storage effect, and their interaction contribute to coexistence in stochastic and seasonal environments

Explaining coexistence in species-rich communities of primary producers remains a challenge for ecologists because of their likely competition for shared resources. Following Hutchinson's seminal suggestion, many theoreticians have tried to create diversity through a fluctuating environment, which impairs or slows down competitive exclusion. However, fluctuating-environment models often only produce a dozen of coexisting species at best. Here, we investigate how to create richer communities in fluctuating environments, using an empirically parameterized model. Building on the forced Lotka-Volterra model of Scranton and Vasseur (Theor Ecol 9(3):353-363, 2016), inspired by phytoplankton communities, we have investigated the effect of two coexistence mechanisms, namely the storage effect and higher intra- than interspecific competition strengths (i.e., strong self-regulation). We tuned the intra/inter competition ratio based on empirical analyses, in which self-regulation dominates interspecific interactions. Although a strong self-regulation maintained more species (50%) than the storage effect (25%), we show that none of the two coexistence mechanisms considered could ensure the coexistence of all species alone. Realistic seasonal environments only aggravated that picture, as they decreased persistence relative to a random environment. However, strong self-regulation and the storage effect combined superadditively so that all species could persist with both mechanisms at work. Our results suggest that combining different coexistence mechanisms into community models might be more fruitful than trying to find which mechanism best explains diversity. We additionally highlight that while biomass-trait distributions provide some clues regarding coexistence mechanisms, they cannot indicate unequivocally which mechanisms are at play.

Reasons for engagement with online tobacco marketing among US adolescents and young adults.

INTRODUCTIONEngagement with online tobacco marketing among US adolescents increased from nearly 9% (2013–2014) to 21% (2014–2015). Such engagement increases the risk of tobacco use initiation. Despite the increase in the prevalence of and risks associated with engagement, the reasons why adolescents and young adults engage are not known.METHODSA sample of 2619 adolescents (13–17 years) and 2625 young adults (18–24 years) living in the US participated in an online survey in July–August 2017. Engagement with online tobacco marketing was assessed through five forms of engagement (e.g. watched a video online promoting tobacco products). Reasons for engagement were assessed through an open-ended survey question. Prevalence of reasons for engagement was calculated overall, by tobacco use status, and by age group (adolescents and young adults). Multivariable logistic regression models were fit with engagement as the outcome (overall and specific reasons) and sociodemographics (including age, gender, and race/ethnicity) and tobacco use status (non-susceptible and susceptible never tobacco users; ever, but not past 30-day tobacco users; and past 30-day tobacco users) as covariates.RESULTSAcross all tobacco use statuses, the leading reasons for engagement were curiosity or desire for general knowledge about tobacco products (3.9%); incidental, unintended or forced exposure to tobacco ad (3.8%); and seeking discounts, coupons, incentives, or contests (2.9%). Susceptible never tobacco users were more likely to engage because of curiosity or general knowledge than non-susceptible never tobacco users (adjusted odds ratio, AOR=6.81; p<0.01). Past 30-day tobacco users were more likely to engage because of discounts, coupons, incentives, or contests and product appeal than ever, but not past 30-day tobacco users (AOR=7.10; p<0.01).CONCLUSIONSStricter state and federal regulation of tobacco marketing, specifically tobacco ads and coupons, and stronger self-regulation by social networking sites could reduce youth engagement with online tobacco marketing.