Curvilinear Relationship Research Articles

Dose-response effects of starch in sterilised and unsterilised chicken excreta on Musca domestica larval growth and bioconversion efficiency

Abstract Housefly (Musca domestica L.) larvae can convert animal manure into valuable protein and fat but little is known about their nutritional requirements. We assessed the effects of differential starch content in unsterilised (UE) and heat sterilised (SE) chicken excreta on larval performance and bioconversion. Gelatinized corn starch was added to excreta resulting in 11 diets with 0 to 50% starch of dry mass. Individual larval mass increased from (mean ± SD) 12 ± 0.2 (UE) and 13 ± 0.4 (SE) mg at 0% starch up to 18 ± 0.4 (UE) and 18 ± 0.5 (SE) mg at 15% starch and decreased to 5 ± 0.4 (UE and SE) mg in 50% starch. Higher starch concentrations resulted in non-normal distributions of individual larva mass. Larval wet yield showed a curvilinear relation with starch content, with maxima of 39 ± 2.3 g in UE at 10% starch, and 43 ± 2.8 g in SE at 15% starch. The decrease in yield after the maxima was faster in UE compared to SE. Larval survival was highest in 0% starch, 80 ± 8% (UE) and 72 ± 13 % (SE), linearly decreasing to 14 ± 7% (UE) and 18 ± 3% (SE) in 50% starch. Dry matter bioconversion increased from 4 ± 0.1% (UE) and 4 ± 0.3% (SE) in 0% starch to 6 ± 0.2 in UE with 10% starch and 7 ± 0.3 in SE with 15% starch, decreasing to close to 0 in 50% starch. Highest nitrogen bioconversion was 15 ± 0.5% in UE with 10% starch and 15 ± 0.5% in SE with 15% starch. Optimal starch inclusions increased nitrogen bioconversion with 40% (UE) and 100% (SE) compared to pure excreta. Finally, around 20 to 25% starch uric acid and ammonia contents, pH, and diet residue C/N decreased, indicating a tipping point. In conclusion, adding starch to chicken excreta can substantially increase larval yield and bioconversion while reducing ammonia content in the substrate residue.

Net‐Zero Transition Pathways in Belt and Road Economies: Insights From Threshold Effects and Heterogeneous Analysis

ABSTRACTGiven the pressing need for economies to mitigate climate change and champion carbon neutrality, this study investigates the threshold effects of financial development and foreign direct investment (FDI) on carbon dioxide (CO₂) emissions in Sub‐Saharan Africa (SSA) within the Belt and Road Initiative (BRI) bloc, taking into account the moderating role of the regulatory environment. Drawing on the environmental Kuznets curve and the pollution haven hypothesis, the study utilizes the dynamic generalized method of moments (GMM) modeling, proposed by Arellano and Bover, to analyze panel data from 37 SSA countries spanning 1990–2022. The findings reveal that financial development in the banking, financial, and private sectors, along with FDI outflows, is associated with a reduction in CO₂ emissions. Conversely, FDI inflows are linked to increased CO₂ emissions. A curvilinear relationship is observed, where initial increases in financial development and FDI correlate with higher emissions, which decline beyond a certain threshold. Stronger regulations enhance the positive impact of financial development on reducing CO₂ emissions. Finally, the findings show a significant heterogeneous effect across the SSA regional blocs. These findings underscore the critical need for implementing stringent environmental regulations and promoting sustainable financial practices to mitigate negative environmental impact. This research provides both theoretical and practical insights into fostering a carbon neutrality agenda and advancing Sustainable Development Goal 13.

Association between the Planetary Health Diet Index and biological aging among the U.S. population

BackgroundThe Planetary Health Diet (PHD) is a novel dietary pattern proposed by the EAT-Lancet Commission in 2019, yet a limited study has investigated the anti-aging effects of PHD to date.ObjectivesThis study aimed to explore the association between adherence to PHD, as quantified by the Planetary Health Diet Index (PHDI), and biological aging in American populations.MethodsData were obtained from the National Health and Nutrition Examination Survey (NHANES) for 1999–2018. Food consumption information was relied on two 24-h diet recall questionnaires. The biological aging condition was comprehensively assessed by four biological markers, including phenotypic age, biological age, telomere length, and klotho concentration. Weighted multivariate linear models, restricted cubic spline (RCS), and subgroup analysis were subsequently carried out to evaluate the influence of PHDI on biological aging.Results44,925 participants with complete data were finally enrolled in our study. The fully adjusted models showed decreased 0.20 years in phenotypic age [−0.20 (−0.31, −0.10)] and declined 0.54 years in biological age [−0.54 (−0.69, −0.38)] correlated with PHDI per 10 scores increment. Klotho concentration [6.2 (1.0, 11.0)] was positively related to PHDI. In Model 2, telomere length increased by 0.02 bp for every 10-point rise in PHDI. Besides, the RCS analysis results exhibited a curvilinear relationship between PHDI and four indicators.ConclusionOur study explored a significant correlation between PHDI and biological aging, indicating that adherence to PHD may prevent biological aging.

Too much of a good thing: Addressing the shape of relationship between positive media sentiment and IPO performance

The influence of mass media sentiment on the IPO performance of newly listed firms has received increasing research attention in management and entrepreneurship research. However, prior literature assumes the beneficial role of positive media sentiment in investors’ evaluation of the firm yet overlooks the potential downside of too much positive media sentiment. Based on two theories, dual processing theory and celebrity theory, we develop and test a curvilinear relationship between positive media sentiment and newly listed firms’ IPO performance. Further, we suggest that IPO market conditions, offering an important information cue, moderate this curvilinear relationship. Drawing a representative sample of newly listed U.S. firms in recent decades, we find support for the proposed inverted U-shape relationship and a moderating effect of market conditions.

How Does Shareholding by Passive Institutional Investors Impact the Corporate Governance of European Firms?

ABSTRACTResearch Question/IssueThe passive investment (PI) trend, characterized by the increasing inflow of investment funds into PI strategies, has resulted in an increase in the share of corporate ownership held via investments in PI strategies. This paper investigates this trend's consequential impact on European companies' corporate governance (CG).Research Findings/InsightsWe find that higher ownership by passive institutional investors (PIIs) is associated with fewer female directors, reduced independence in audit and nomination committees, and higher executive pay, negatively impacting CG. Nevertheless, our findings show that PIIs can increase the probability that a company has a policy regarding the adequate experience of board members and equal treatment of shareholders.Theoretical/Academic ImplicationsWe hypothesize that the level of ownership could be the missing link connecting mixed theories about the impact of ownership by PIIs on the CG of companies they invest in. A curvilinear relationship between the two could allow conflicting theories to coexist in one framework. We find weak evidence for a curvilinear relationship, but this relationship may become more prevalent if PII ownership of European companies increases because of regulatory changes.Practitioner/Policy ImplicationsSome critics have proposed limiting PII voting rights, but our findings suggest that the effect of PII ownership may become less negative beyond a certain level of ownership and that PIIs may play a positive role in enhancing board experience and shareholder equity policies. Restricting PIIs may not necessarily be beneficial for the CG of companies they invest in.

Relationship between trauma, post-traumatic stress and post-traumatic growth for police officials: A path analysis

Background & Objective: Police officials tend to face a high frequency of potentially traumatic incidents due to nature of their job. A dichotomous distinction among these traumatic incidents is witnessing of threat or harm to others and the experiencing of threat or harm directly to oneself. Previous research suggests that different types of traumas (direct and indirect) exposure can produce different levels of negative responses including posttraumatic stress disorder (PTSD) symptoms and positive outcomes such as posttraumatic growth (PTG) in police officials and other law enforcement agencies officials. Our objective was to study post-traumatic stress and post traumatic growth among police officials. Methods: In this cross-sectional study conducted from January 2019 to December 2022. The sample consisted of 400 police officials (having direct and indirect exposure of war trauma) who participated in war on terror in FATA Pakistan. Non probability purposive sampling technique was used for sample selection. Relationship among trauma, PTS (Post traumatic stress) and PTG (Post traumatic growth) was assessed. Results: Findings from the present study indicated that stress played vital role in paving pathway from trauma to growth (β =0.08). Study results also confirmed that moderate level of stress is linked with positive changes like posttraumatic growth. R-square change in linear relationship among stress and posttraumatic growth was 0.59 but in curvilinear relationship among stress and posttraumatic growth R-square change was 0.77 which is higher than linear relationship which confirmed the curvilinear relationship between stress and growth and these findings proved that moderate level of stress after war trauma exposure produced higher levels of post traumatic growth. Conditional indirect effect of exposure to trauma on growth is highly significant (***p < .001) so the role of stress as mediator has been confirmed. Conclusion: The study provided initial evidence that after trauma exposure levels of posttraumatic stress which is experienced play a significant role in the promotion of PTG. Moreover, the results from the present study also revealed the possibility of positive changes in behaviors facilitated by moderate exposure of trauma and stress. doi: https://doi.org/10.12669/pjms.40.10.8897 How to cite this: Azeem A, Kiran N. Relationship between trauma, post-traumatic stress and post-traumatic growth for police officials: A path analysis. Pak J Med Sci. 2024;40(10):2223-2227. doi: https://doi.org/10.12669/pjms.40.10.8897 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Rhythm and shift frequency of strategic renewal in Indonesian firm performance

Purpose This study aims to explore how manufacturing firms in emerging economies can effectively adjust the rhythm and shift frequency between exploitation and exploration renewal. The authors also examine how these strategic adjustments can significantly boost firm performance, offering insights into the dynamic process of strategic renewal. Design/methodology/approach This study analyzes annual reports of 127 Indonesian manufacturing firms from 2014 to 2019, applying both linear and curvilinear regression models to examine the hypotheses. Data on exploration and exploitation renewal were meticulously gathered using computer-aided text analysis, using targeted keywords to identify strategic renewal efforts. Findings The study shows that a rather irregular balance rhythm between exploitation and exploration renewal surprisingly enhances firm performance. A curvilinear relationship emerges as performance peaks when the shift frequency of renewal occurs about three times. This relationship optimizes the strategic renewal processes, emphasizing that firms need to remain agile and adaptable in today’s dynamic market environment. Originality/value This study leverages organizational learning to assess how the paradoxical dimensions of exploration and exploitation renewal impact firm performance. By focusing on the temporal transition of these tensions, it provides insights into optimizing the rhythm and shift frequency of renewal, transitioning from a static to a dynamic accord.

Assessing electoral coordination: A quasi-experimental design of changes in district magnitude over time

This paper examines the impact of district magnitude, defined as the number of representatives elected per district, on the number of political parties. Conventional wisdom, supported by cross-national and within-country studies, indicates a positive and curvilinear relationship between district magnitude and the number of parties, with diminishing returns in larger-magnitude districts. However, this relationship is complicated by the increasing regionalization of party systems and the distinct socio-economic compositions of districts correlated with district magnitude. To address these limitations and obtain an appropriate counterfactual, we employ a quasi-experimental design using data from Spain, where district magnitude changes by only one seat in some districts and elections. Our findings align with previous research, confirming that the number of electoral parties increases with district magnitude, particularly in low-magnitude districts.

Intellectual Humility and Belief Extremity: Evidence for Curvilinearity?

Because an intellectually humble person is neither diffident nor arrogant in their views, intellectual humility (IH) is considered a virtuous mean. Yet, evidence for the virtuous mean account is mixed, with some studies finding evidence for it and some studies finding evidence against it. To clarify these ambiguities, we examined the curvilinear relations between multiple IH conceptualizations and belief strength across political, religious, and irreligious beliefs. In a secondary analysis of more than 4,000 participants, there was evidence for the virtuous mean account for political beliefs, evidence against it for religious beliefs, and little evidence for irreligious beliefs. Altogether, these results raise the possibility that the virtuous mean account of IH is not as generalizable as originally presumed. Thus, instead of asking whether IH is a virtuous mean, future research should ask when, why, and how IH is a virtuous mean for some beliefs and not for others.

Association between colchicine use and adverse cardiovascular events in patients with gout: a nationwide nested case-control study.

The association between colchicine use and the primary prevention of atherosclerotic cardiovascular disease (ASCVD) remains unknown. This study aimed to explore the association between colchicine use and new development of ASCVD and ASCVD-related mortality in patients with incident gout. This nested case-control study utilized the nation-wide claims database of the Korean National Health Insurance System. Patients without a history of ASCVD who developed incident gout and were newly started on allopurinol as first-line therapy between 2011 and 2016 were initially screened. Individuals who experienced ASCVD event or ASCVD-related mortality during the follow-up period were matched with four controls for age, sex, income, residential area, co-morbidities, and medications. The main exposure was colchicine use, assessed by 1) the cumulative defined daily doses (cDDDs) and 2) the cumulative duration. For secondary analyses, the risk of ASCVD events and ASCVD-related mortality were examined, separately. Overall, 9,346 patients with ASCVD event or ASCVD-related mortality were matched with 35 070 controls. The patient population was predominantly male. Compared with non-users, a curvilinear relationship between higher cDDDs of colchicine and the odds of ASCVD event was observed; the odds ratios (95% confidence interval) were were 1.09 (1.04-1.15) for <90 cDDDs, 1.20 (1.07-1.33) for 80-179 cDDDs, and 1.21 (1.09-1.35) for ≥180 cDDDs. This association was similarly observed for ASCVD events and ASCVD-related mortality, respectively. Colchicine use was associated with an increased risk of ASCVD in patients with newly diagnosed gout who did not have a prior history of ASCVD.

Parental attachment and mental health in Chinese early adolescents: The mediation role of narcissism

The generalization of multiple attachment models in Chinese youth is still unknown, and the specific effect of combined parental attachment on the mental health of early Chinese adolescents and the mechanism behind it remains unclear. Therefore, the aim of this study was to empirically investigate the effect of parental attachment on early Chinese adolescents’ mental health, to examine which multiple attachment model could best explain this impact, and to explore the mediating effect of narcissism between them. A sample of 834 early adolescents was recruited to complete standard questionnaires. Regression analyses, MANOVA, and mediation analysis were performed. We found (1) the effects of parental attachment on the mental health of early Chinese adolescents were generally consistent with the integrative model of multiple attachment; (2) a linear relationship was observed between combined parental attachment and anxiety/depression, while a curvilinear relationship was observed between combined parental attachment and life satisfaction; (3) combined parental attachment could affect mental health through vulnerable narcissism instead of grandiose narcissism. The current study offered one of the first evidence for the association between parental attachments and early adolescents’ mental health within a multiple attachment framework in China and provided valuable insight into the role of narcissism between them, as well as contributing to the literature by suggesting that the integrative model could be better refined by considering the characteristics of the indicators.

When Does Positive Communication Maximize Effective Information Flow?

Positive communication and its importance to organizations has become a popular topic of research among organizational scholars. However, there remains a paucity of work exploring nonlinearities in the role of positivity in communication effectiveness, with little research examining whether there can be too much of a good thing when it comes to communication positivity. To address these gaps in the literature on positive communication, I tested the hypothesis that work-related workplace communication will exhibit an inverted U-shaped curvilinear relationship with positive emotion. This relationship is hypothesized to result from a tradeoff between total workplace communication and the proportion of total workplace communication that is explicitly work-related as communication positivity increases. The results of this study generally support the hypothesized relationship and, save for some minor caveats, the hypothesized mechanisms underlying it. Enclosed are discussions on these caveats and the implications of this study’s findings for both organizational researchers and practitioners.

Too much information! When job resources become job demands, producing a curvilinear relationship between informational social support and creativity

Objective Informational social support can have both positive and negative effects on employees. This research aims to examine the curvilinear relationship between informational social support and employees’ cognitive processes, specifically cognitive depletion and creativity. Additionally, we investigate the moderating role of emotional stability on this curvilinear relationship, particularly regarding cognitive depletion. Methods A total of 108 male employees in South Korea participated in the study, completing 864 two-wave, time-lagged daily diary questionnaires. The surveys measured informational social support, cognitive depletion, creativity, and emotional stability. Results The findings reveal that informational social support enhances employees’ cognitive processes up to a certain threshold, after which its effects become detrimental, demonstrating a curvilinear pattern. Furthermore, emotional stability moderates this relationship: emotionally stable employees show a linear relationship between informational social support and cognitive depletion, while emotionally unstable employees exhibit a curvilinear relationship. Conclusion Our results suggest that excessive informational social support may harm employees’ cognitive processes, indicating that there is an optimal level of support, beyond which the effects become counterproductive.

Interactions of the CSF3R polymorphism and early stress on future orientation: evidence for the differential model of stress-related growth.

This study aims to explore the concept of future orientation, which encompasses individuals' thoughts about the future, goal-setting, planning, response to challenges and behavioural adjustments in evolving situations. Often viewed as a psychological resource, future orientation is believed to be developed from psychological resilience. The study investigates the curvilinear relationship between childhood maltreatment and future orientation while examining the moderating effects of genotype. A total of 14,675 Chinese adults self-reported their experiences of childhood maltreatment and their future orientation. The influence of genetic polymorphism was evaluated through genome-wide interaction studies (GWIS; genome-wide association study [GWAS] using gene × environment interaction) and a candidate genes approach. Both GWAS and candidate genes analyses consistently indicated that rs4498771 and its linked single-nucleotide polymorphisms, located in the intergenic area surrounding CSF3R, significantly interacted with early trauma to influence future orientation. Nonlinear regression analyses identified a quadratic or cubic association between future orientation and childhood maltreatment across some genotypes. Specifically, as levels of childhood maltreatment increased, future orientation declined for all genotypes. However, upon reaching a certain threshold, future orientation exhibited a rebound in individuals with specific genotypes. The findings suggest that individuals with certain genotypes exhibit greater resilience to childhood maltreatment. Based on these results, we propose a new threshold model of stress-related growth.

“Love thy neighbor, but don’t pull down your hedge”: The influence of interdependence with major customers on supplier productivity

This research examines how mutual and relative dependence on major customers impact supplier productivity. We investigate two research questions: (1) Does the extent of mutual dependence between a supplier and its major customer base exhibit a non-linear impact on supplier productivity? (2) How does the combined influence of the supplier’s relative dependence and mutual dependence on major customers affect supplier productivity? Using major customer relationship data from Compustat segment files, we construct a longitudinal dataset in the manufacturing industry for the period 1998–2017. We estimate supplier productivity accounting for selection bias and employ the fixed effect regression approach to examine the effects of mutual dependence and relative dependence on supplier productivity. Moreover, we address potential endogeneity in the model with the control function approach. Our results indicate an inverted curvilinear relationship between a supplier’s mutual dependence on its major customers and its productivity: While increased mutual dependence initially enhances productivity, the marginal returns diminish. Interestingly, the curvilinear effect becomes more prominent when the supplier’s relative dependence increases. Our study’s findings offer three best-practice strategies including (1) spread and anchor risk, (2) reduce relative dependence, and (3) deepen customer understanding, all of which help suppliers manage the interdependence in major customer relationships.

Association of ambient air pollution with cognitive functioning and markers of structural brain damage: The Maastricht study

IntroductionGiven the absence of curative interventions and the rising global incidence of dementia, research is increasingly focusing on lifestyle factors for prevention. However, identifying shared environmental risk for dementia, next to individual factors, is crucial for optimal risk reduction strategies. Therefore, in the present study we investigated the association between air pollution, cognitive functioning, and markers of structural brain damage. MethodsWe used cross-sectional data from 4,002 participants of The Maastricht Study on volumetric markers of brain integrity (white and grey matter volume, cerebrospinal fluid volume, white matter hyperintensities volume, presence of cerebral small vessel disease) and cognitive functioning (memory, executive functioning and attention, processing speed, overall cognition). Individuals were matched by postal code of residence to nationwide data on air pollution exposure (particulate matter < 2.5 μm (PM2.5), particulate matter <10 μm (PM10), nitrogen dioxide (NO2), soot). Potentia linear and non-linear associations were investigated with linear, logistic, and restricted cubic splines regression. All analyses were adjusted for demographic characteristics and a compound score of modifiable dementia risk and protective factors. ResultsExposure to air pollutants was not related to cognitive functioning and most brain markers. We found curvilinear relationships between high PM2.5 exposures and grey matter and cerebrospinal fluid volume. Participants in the low and high range of exposure had lower grey matter volume. Higher cerebrospinal fluid volumes were only associated with high range of exposure, independent of demographic and individual modifiable dementia risk factors. After additional post hoc analyses, controlling for urbanicity, the associations for grey matter volume became non-significant. In men only, higher exposure to all air pollutants was associated with lower white matter volumes. No significant associations with white matter hyperintensities volume or cerebral small vessel disease were observed. DiscussionOur findings suggest that higher PM2.5 exposure is associated with more brain atrophy.

How does government R&D subsidies affect enterprises’ viability? An investigation on inverted U-shaped relationship

Based on the theory of New Structural Economics, this study investigates the non-linear relationship between government R&D subsidies (RDS) and enterprises’ viability (VIA) in China, utilizing data from A-share listed advanced manufacturing enterprises. The findings reveal an inverted U-shaped relationship, where VIA initially increases and subsequently decreases as RDS intensifies. Furthermore, we examine the impact of technological convergence between the digital and real economy industries (TCG) on this relationship and find that TCG strengthens the curvilinear relationship. This study provides valuable insights for formulating advanced manufacturing policies that address structural needs, thereby fostering high-quality development of the real economy.

Moderation Effects of Person-Organization Fit on Curvilinear Relationship between Transformational Leadership and Innovation Performance : Focused on Ph D-Level R&amp;D Practitioners

Moderation Effects of Person-Organization Fit on Curvilinear Relationship between Transformational Leadership and Innovation Performance : Focused on Ph D-Level R&amp;D Practitioners

Examining the Curvilinear Relationship between Grit and Burnout in University Student Athletes

Examining the Curvilinear Relationship between Grit and Burnout in University Student Athletes

Nonlinear association between atherogenic index of plasma and chronic kidney disease: a nationwide cross-sectional study

BackgroundThe interplay between metabolic disorders and chronic kidney disease (CKD) has been well-documented. However, the connection between CKD and atherogenic index of plasma (AIP) remains understudied. This research delves into the correlation between these two factors, aiming to shed new light on their potential association.MethodsThe relationship between AIP and CKD was evaluated using a weighted multivariate logistic regression model, and the curvilinear relationship between AIP and CKD was explored through smooth curve fitting. We engaged a recursive partitioning algorithm in conjunction with a two-stage linear regression model to precisely determine the inflection point. By conducting stratified analyses, the heterogeneity within subpopulations was explored.ResultsIn the regression model that accounted for all covariates, ORs (95% CI) for the association between CKD and AIP were 1.12 (0.91, 1.36), indicating no significant association between AIP and CKD. However, sensitivity analyses suggested that the relationship between them may be non-linear. Smooth curve analysis confirmed the non-linear relationship between AIP and CKD, identifying an inflection point at -0.55. Below this threshold, AIP exhibited a significant inverse correlation with CKD. Conversely, above this threshold, a pronounced positive correlation was detected. Stratified analyses elucidated that a non-linear association between AIP and CKD was observed among female participants and those aged 50 and above.ConclusionWe found a curvilinear relationship between chronic kidney disease and atherogenic index of plasma.