Inverse U-shaped Curve Research Articles

Youth migration in Ukraine: regional dimension

Purpose. This study aims to analyze the regional differentiation of youth migration flows and typify the regions of Ukraine according to the characteristics of the migratory behavior of the youth. Accordingly, the research questions are as follows: 1) what is the relationship between economic indicators (income, unemployment, investment) and youth migration at the regional level? 2) how do the regions of Ukraine differ in the scale, structure, and dynamics of youth migration flows? 3) what types of regions can be identified, and can they be considered to determine the young people’s intention to migrate? Research methods. Pearson's correlation coefficients were calculated to assess the relationship between youth migration and economic indicators at the regional level. To prevent skewed indicators distribution, the city of Kyiv was excluded from the analysis. In order to study the regional differentiation of youth migration, we used cluster analysis and constructed Kohonens self-organizing maps. Based on the analysis of spatial and temporal (from 2002 to 2019) trends, we also developed an empirical typification of the regions according to the migration behavior of young people. Main findings. The analysis of spatial differences in youth migration in urban and rural areas shows the diversity and complicated multidirectionality of migration flows. Youth migration has been found to be linked to unemployment and investment attractiveness at the regional level. The assumption that the migration of young people from rural areas is influenced not only by economic factors but also by the lack of prospects for tertiary education, jobs, and the ‘culture of migration’ has been confirmed. The analysis of the relationship between income and out-migration scale shows some signs of a inverse U-shape curve. In general, the results of the study confirmed that at the regional level, economic indicators (unemployment, investment, and income) affect youth migration in Ukraine, but their impact needs to be studied in the broader context of place-specific human capital and life-course transition. Based on the results of cluster analysis and construction of Kohonen self-organizing maps, five clusters of Ukraine’s regions by the similarity of youth migration were identified. The analysis of youth migrations in 2002-2019 allowed to identify six models of their dynamics (monotonically decreasing, abrupt dynamics with a tendency to decrease, abrupt dynamics without changes, abrupt dynamics with a tendency to increase, monotonically increasing, without changes). According to the combination of selected clusters of regions and models of youth migration dynamics, we empirically typified Ukraine’s regions into three groups that can be considered those that, to some extent, determine the young people’s intention to migrate. However, further research should be aimed at analyzing the individualization of migration behavior and liquid migration of Ukrainian youth. Scientific novelty and practical value. The main novelty of the study is its focus on the spatial dimension of youth migration in Ukraine, particularly identifying the features of regional differentiation of migration flows, factors, trends and regional problems associated with youth migration. The practical value of the obtained results lies in the possibility for certain types of regions to become ‘guidelines’ for the migration policy in the regions of Ukraine.

Untangling the Relationship Between Corporate Environmental Performance and Financial Performance

The inconclusive quest on the relationship between corporate environmental performance (CEP) and financial performance (CFP) necessitates this research. We apply fixed–effects analysis on a longitudinal dataset of 8364 firm-year observations from 1455 individual firms. The results suggest that the effect of CEP on CFP is positive at first to a certain level of CEP then becomes negative which indicating an inverse U-shaped CEP-CFP link. Also, the environmental uncertainty in terms of dynamism, munificence, and complexity strengthens the positive (negative) effect of CEP on CFP at the left (right) side of the inverse U-shaped curve. Our findings reconcile the long-standing debate on the CEP-CFP link and provide a comprehensive representation for CEP-CFP relationship by demonstrating the double-edged contingent role of environmental uncertainty.

Drown or Blossom? The Impact of Perceived Chronic Time Pressure on Retail Salespeople's Performance and Customer–Salesperson Relationships

For retail salespeople chronic time pressure, a perpetual perception of being rushed for time, is a prevalent and pervasive phenomenon in their daily sales jobs. Despite this practical relevance, consequences of perceived chronic time pressure on retail salespeople's selling behaviors, such as adaptive selling, and selling performance are not well understood. Thus, the authors investigate the effect of retail salespeople's perceived chronic time pressure in interactions with customers and its impact on retail salespeople's adaptive selling behavior, customers’ purchase outcomes, as well as salespeople's overall objective performance. Analysis of dyadic data from 291 salesperson–customer interactions from a large B2C furniture retailer revealed an inverse U-shaped curve for the relationship between retail salespeople's perceived chronic time pressure and their adaptive selling behavior. The chronic time pressure–selling outcome relationship strongly depends on the contingencies of retail salespeople's goal orientations and perceived organizational support and has implications for retail research and practice.

Long-term profile of serological biomarkers, hepatic inflammation, and fibrosis in a mouse model of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) can be typically classified into two subgroups: non-alcoholic fatty liver and non-alcoholic steatohepatitis. Mouse models of NAFLD are useful tools for understanding the pathogenesis and progression of NAFLD and for developing drugs for its treatment. Here, we investigated the time-dependent changes in serum lipids and biochemical markers of hepatic function, hepatic inflammation, and fibrosis in mice fed a normal diet (ND) or a NAFLD diet (choline deficient, L-amino acid-defined, high-fat diet; CDAHFD) for 12 weeks. CDAHFD-fed mice showed significantly reduced serum levels of total cholesterol, triglyceride, and high-density lipoprotein cholesterol throughout the treatment period compared with ND-fed mice. The changes in aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and total bilirubin showed an inverse U-shaped curve in the CDAHFD-fed mice. The serum alkaline phosphatase levels decreased in both ND- and CDAHFD-fed mice in a time-dependent manner. Furthermore, CDAHFD-fed mice showed a significant increase in the number of inflammatory foci and hepatic fibrosis at 6–12 weeks, although inflammatory foci and hepatic fibrogenesis were observable at relatively early stages as well (1–4 weeks). In conclusion, the long-term profile of serological biomarkers, hepatic inflammation, and fibrosis in CDAHFD-fed mice identified in this study may provide a better understanding of NAFLD pathogenesis.

Conflict or Coordination? Multiscale assessment of the spatio-temporal coupling relationship between urbanization and ecosystem services: The case of the Jingjinji Region, China

Abstract Coordinating urbanization and ecosystem conservation is necessary for future regional sustainability. Understanding the coupling relationship between urbanization and ecosystem conservation has great significance in ecological management and policy making. Based on a comprehensive index system of urbanization and ecosystem services (ESS), this study used the coupling coordination degree (CCD) model and spatial autocorrelation statistical model to evaluate the spatio-temporal coupling interactions of urbanization and ESS in the Jingjinji (JJJ) region at multiple scales from 1996 to 2014, aiming to coordinate development and strengthen regional sustainability. The results showed that although the JJJ region underwent accelerated urban sprawl and urbanization in 1996–2014, the growth of areas such as forests, orchards and water bodies contributed to an overall 4.63% increase in the ecosystem services value (ESV). The dynamic evolution between these two constructs displayed an inverse U-shaped curve and exhibited various characteristics at different development stages and research scales. The urbanization level and the associated changes impacted the natural ecosystems and ESS differently, causing regional differences in ESV per unit area and structural shifts in the ecosystem. During 1996–2014, the CCD between urbanization and ESS in the whole region fluctuated upward, moving from the medium–low stage to the medium–high stage and undergoing a transition from lagging urbanization to lagging ESS. The CCD varied greatly among regions: the spatial similarity between the CCD at the county scale showed that the northern part of the JJJ region presented high-high clusters, while the low-low accumulation areas were mainly distributed in the central southern plain. The overall development trend was good except for the decrease in CCD in some southern counties. The analytical results suggested that the processes that couple urbanization with ecosystems and ESS should be controlled through new urbanization planning, increased sustainable ecological network management, and mutually beneficial cooperation across administrative borders to sustain regional development.

Trend of income inequality in Asia and effects of education

This study considers how education and globalization affect income inequality in Asia, with the unbalanced panel data. The evidence supports the validity of Kuznets inverted-U hypothesis for the connection between the income level and income inequality. However, when more variables are integrated into the model, the consistency of inverse U-shaped curve becomes weaker. The empirical results suggest that educational variables are highly influential in affecting income distribution. Our analysis indicates that a higher level of education achieved by the population aged 15 and over has improved income distribution in Asia, while educational inequality, measured by the educational Gini, has a negative effect on income distribution. Higher levels of globalization are correlated with higher levels of income inequality, while freedom, either political or economic, has marginal effects on the level of inequity in income distribution.
 Key words: Education inequality, globalisation, income inequality

Prognostic Value of Neutrophil-Lymphocyte Ratio in Cardiogenic Shock: A Cohort Study.

BackgroundInflammation plays an important part in the pathogenesis of cardiogenic shock (CGS). Whether the neutrophil-lymphocyte ratio (NLR), an integrated biomarker of inflammation, is associated with the outcome of CGS patients remains unknown. This retrospective cohort study was performed to identify the utility of using NLR among patients with CGS.Material/MethodsData were extracted from the MIMIC database. We applied smooth curve fitting to define the NLR cutoff values. The primary outcome was 30-day mortality. Cox proportional hazards models, subgroup analysis, and receiver operator characteristic (ROC) curve analysis were performed.ResultsA total of 1470 CGS patients were extracted, among which 801 (54.5%) were men. The mean age of the population was 70.37 years. An inverse U-shaped relationship was observed between NLR and mortality in CGS patients, with the highest risk being at values ranging from 9.4 to 15. For the primary outcome of 30-day mortality, the adjusted HR (95% CI) values of the middle tertile (NLR 9.4–15) and the upper tertile (NLR >15) were 1.47 (1.14, 1.88) and 1.22 (0.94, 1.57) compared with the reference of lower tertile (NLR <9.4). ROC curve analysis showed that NLR had a more sensitive prognostic value in predicting 30-day mortality of CGS than the neutrophil or lymphocyte percentage alone (0.660 vs. 0.540, 0.549).ConclusionsAn inverse U-shaped curve was presented between NLR and the mortality of CGS. NLR seemed to be a readily available and independent prognostic biomarker for patients with CGS. The prognostic value of NLR was more sensitive than the neutrophil or lymphocyte percentage alone, but not as good as SOFA or SAPSII score.

Corporate governance and firm performance within the Russian agri-food sector: does ownership structure matter?

This article provides pioneering empirical evidence on the ownership structure and firm performance relationship for the case of corporate agri-food companies in Russia. While Russia plays a vital role in the global agri-food system, its domestic agri-food production is evidently dominated by a small number of corporate enterprises, which are in turn characterized by high ownership concentration. We employ unique panel data obtained from 203 companies for the years between 2012 and 2017. A random effects model was used to analyze the impacts of ownership concentration and ownership identity on the firms’ financial performance, measured by return on assets and return on sales. Our results indicate an inverse U-shaped association between ownership concentration and firm performance, with average level of ownership concentration found to be on the descending range of the inverse U-shaped curve. Moreover, we observe a similar quadratic relationship between ownership concentration by government and directors and firm performance. On average, ownership by directors was found to be on the ascending range and below the peak point, suggesting a potential for further performance improvement, while the impact of agroholding ownership was found to be linear and positive.

China's urban air quality evaluation with streaming data: A DEA window analysis

After the promotion of urbanization in the past decades, air pollution has become one of the bottlenecks of China's urban development. Kinds of real-time air pollution indicators are recorded by using environmental detection system in China's urban area that produces precious streaming data. The present paper constructs window DEA model to compute the dynamic air quality index after applying hierarchy analysis to resolve the heterogeneity of time varying data. In the section of empirical study, we select the daily data of CO, NO, SO2, PM 2.5 and PM 10 since January 2018 to August 2019 for 360 cities in China which includes 1,092,600 streaming data. Our empirical findings indicate that air pollution is heavily serious in most China' cities, in which more than 95% cities have over emitted air pollution by 30% at least. Chinese urban air quality is significantly affected by the change of month and shows an inverse U-shaped curve relationship in year, while the orders of weeks within month or order of days within week is irrelevant. The provinces with the most urban air pollution concentrate in middle China and from a continuous pollution zone with Shanxi as the center.

An empirical analysis of dynamic changes in ecological sustainability and its relationship with urbanization in a coastal city: The case of Xiamen in China

Many coastal cities have undergone a surge of rapid industrialization and urbanization leading to severe eco-environmental issues. Thus, establishing a systematic and scientific ecological sustainability assessment framework and ecological governance system is crucially important for coastal zone to achieve sustainable development. This study used a modified emergy-ecological footprint approach and a set of ecological sustainability evaluation indicators to comprehensively evaluate the ecological sustainability from 2000 to 2017 of Xiamen, a typical coastal city in China. Its results show that Xiamen changed from having an ecological surplus in 2008 to an ecological deficit in 2009, indicating that its demand for resources began to exceed the ecosystem threshold value in 2009. Besides, the results of the ecological sustainability analysis indicate that the ecological sustainability of Xiamen was gradually weakening due to increasing pressure on ecosystem health. We also measured four aspects of Xiamen’s urbanization level—demographic, economic, social and spatial—to investigate their relationship with ecological sustainability. These results indicate that, for Xiamen, demographic urbanization is the essential determinant of the urbanization system’s correlation relationship with ecological sustainability and it thus is the key indicator to be considered when making policy to guarantee ecological balance and sustainable development. Additionally, the relationships between the four different aspects of urbanization and ecological sustainability are all an exhibit inverse U-shaped curve during the study period. Finally, effective measures were proposed in consideration of the research findings. The results hold profound significance for the Xiamen’s sustainable development, as well as for other coastal zones with similar characteristics.

Returns to Education in the Russian Federation: Some New Estimates

This paper presents new estimates of the returns to education in the Russian Federation using data from 1994 to 2018. Although the returns to schooling increased for a time, they are now much lower than the global average. Private returns to education are three times greater for higher education compared with vocational education, and the returns to education for females are higher than for males. Returns for females show an inverse U-shaped curve over the past two decades. Female education is a policy priority and there is a need to investigate the labor market relevance of vocational education. Higher education may have reached an expansion limit, and it may be necessary to investigate options for increasing the productivity of schooling.

Typical and Aberrant Functional Brain Flexibility: Lifespan Development and Aberrant Organization in Traumatic Brain Injury and Dyslexia.

Intrinsic functional connectivity networks derived from different neuroimaging methods and connectivity estimators have revealed robust developmental trends linked to behavioural and cognitive maturation. The present study employed a dynamic functional connectivity approach to determine dominant intrinsic coupling modes in resting-state neuromagnetic data from 178 healthy participants aged 8–60 years. Results revealed significant developmental trends in three types of dominant intra- and inter-hemispheric neuronal population interactions (amplitude envelope, phase coupling, and phase-amplitude synchronization) involving frontal, temporal, and parieto-occipital regions. Multi-class support vector machines achieved 89% correct classification of participants according to their chronological age using dynamic functional connectivity indices. Moreover, systematic temporal variability in functional connectivity profiles, which was used to empirically derive a composite flexibility index, displayed an inverse U-shaped curve among healthy participants. Lower flexibility values were found among age-matched children with reading disability and adults who had suffered mild traumatic brain injury. The importance of these results for normal and abnormal brain development are discussed in light of the recently proposed role of cross-frequency interactions in the fine-grained coordination of neuronal population activity.

Aging Reduces the Functional Brain Networks Strength-a Resting State fMRI Study of Healthy Mouse Brain.

Resting-state functional magnetic resonance imaging (rsfMRI) is increasingly used to unravel the functional neuronal networks in health and disease. In particular, this technique of simultaneously probing the whole brain has found high interest in monitoring brain wide effects of cerebral disease and in evaluating therapeutic strategies. Such studies, applied in preclinical experimental mouse models, often require long-term observations. In particular during regeneration studies, easily several months of continuous monitoring are required to detect functional improvements. These long periods of following the functional deficits during disease evolution as well as the functional recoveries during therapeutic interventions represent a substantial fraction of the life span of the experimental animals. We have therefore aimed to decipher the role of healthy aging alone for changes in functional neuronal networks in mice, from developmental adolescence via adulthood to progressing aging. For this purpose, four different groups of C57Bl6 mice of varying age between 2 and 13 months were studied twice with 4 weeks separation using resting state fMRI at 9.4T. Dedicated data analysis including both Independent Component Analysis (ICA) followed by seed-based connectivity matrix compilation resulted in an inverse U-shape curve of functional connectivity (FC) strength in both the sensorimotor and default mode network (DMN). This inverse U-shape pattern presented a distinct maximum of FC strength at 8–9 months of age, followed by a continuous decrease during later aging phases. At progressed aging at 12–13 months, the reduction of connectivity strength varied between 25% and 70% with most connectivities showing a reduction in strength by approximately 50%. We recommend that these substantial age-dependent changes in FC strength must be considered in future longitudinal studies to discriminate focused disease-based functional deficits and therapy-related functional improvements from underlying independent age effects.

Spatiotemporal variation in PM2.5 concentrations and their relationship with socioeconomic factors in China's major cities

The air quality issues caused by extreme haze episodes in China have become increasingly serious in recent years. In particular, fine particulate matter (PM2.5) has become the major component of haze with many adverse impacts and has therefore become of great concern to scientists, government, and the general public in China. This study investigates the spatiotemporal variation in PM2.5 in 269 Chinese cities from 2015 to 2016 and its associations with socioeconomic factors to identify the possible strategies for PM2.5 pollution mitigation. Specifically, we first quantified the spatial pattern of PM2.5 concentrations in both 2015 and 2016, and then changes between the two years. Next, we examined the relationship between socioeconomic factors and PM2.5 concentrations and changes. The results showed that most cities in eastern China experienced decreases in PM2.5 concentration, although most of these cities already had high PM2.5 pollution level. Cities with low PM2.5 concentrations experienced increases in PM2.5 concentrations and were mostly located in southern and southwestern China. The PM2.5 concentration was the highest in winter, followed by in spring, autumn and summer; for changes in PM2.5 concentrations, the highest magnitude of decrease occurred in summer, followed by the decreases in winter, autumn and spring. Cities with high PM2.5 concentrations tended to be clustered, but the clustered characteristics were not clearly related to the changes in PM2.5 concentrations. The relationship between PM2.5 concentration and urban size was an inverse U-shaped curve, suggesting the existence of the Environmental Kuznets Curve for air quality in China. Population density and secondary industry share are the keys factors relating to air pollution control. In comparison to other cities, most moderately developed cities had a greater magnitude of decrease in PM2.5 concentrations and the key factor for pollution improvement was industrial structure; however, smaller cities tended to have a greater increase in PM2.5 concentrations and population density was the most important influencing factor. As a result, for air pollution control in China, specific regulations should be carried out according to different regions and different developmental stages based on the locations of cities.

How mood affects the stock market: Empirical evidence from microblogs

Examining 22,504 tweets extracted from Sina Weibo, a microblog site, we identify two clusters of microblog users and study how they influence the stock market. Our research contributes the following significant findings to the existing literature. First, we discover that there exists an inverse U-shaped curve between stock return and the attention of both news media and investors. Second, we verify that news media attention plays a positive moderating effect in the relationship between investor attention and the stock return. Finally, we find that social interaction could positively moderate the effect of news media’s and investor’s sentiments on stock return.

Survey of motion sickness susceptibility in children and adolescents aged 3months to 18years.

We conducted two representative, cross-sectional, population-based surveys on the susceptibility to motion sickness (MSS) in childhood: One was targeted at parents with children aged 6months to 18years (7569 households approached) and the other at parents with children aged 3months to 5years (12,720 households approached). In both surveys 3285 parents provided information on 5041 children. The main findings in the first survey were: 369 children (9.2%) were susceptible to motion sickness with a slight female preponderance, and in the second study 16 (1.2%) were susceptible; first occurrence of motion sickness (MS) below the age of 1year was exceptionally rare (n = 2); if MS occurred after the age of 1year it was more severe in the younger children, most pronounced between the age of 6 and 9years; the frequency of MSS was highest in the range between the age of 4 and 13years; in postpubertal children and adolescents MSS frequency declined. The course of MSS frequency from infancy to adolescence is an inverse U-shaped curve. It is characterised by three phases which may be related to the visual-vestibular mismatch theory, the major pathophysiological cause of MS. Phase one is a high resistance in the first year of life. In this phase infants may be less subject to visual-vestibular mismatch, because they do not yet use visual cues for self-motion perception. Phase two is a prepubertal peak. This is possibly due to an oversensitivity to a visual-vestibular mismatch, which reflects sensorimotor maturation. Phase three is a postpubertal decline. This can be explained by habituation through repetitive motion stimulation during various kinds of vehicle transportations.

The impact of advice distance on advice taking: Evidence from an ERP study

To use ERPs to investigate the impact of advice distance on advice taking in the Judge-Advisor System (JAS) paradigm, behavioural and ERP data were recorded from 20 subjects. The behavioural discrepancies and EEG characteristics of advice taking, as affected by the advice distances, were compared. The results showed that the relationship between the modification rate of a decision maker's initial estimation and the advice distance exhibited an inverse U-shaped curve. During the advice evaluation stage, different advice distances induced the feedback-related negativity (FRN) and subsequent P300 components. The amplitude of the FRN increased as the advice distance increased, while the amplitude of P300 in the zero distance condition was significantly larger than those in the intermediate and far distance conditions. These findings indicate that the advice evaluation process of a decision maker is related to conflict perception, prediction error and motivational or affective significance.

A multiscale analysis of urbanization effects on ecosystem services supply in an urban megaregion

The rapid and large-scale urbanization leads to drastic land-use conversion and impacts on ecosystem services. The relationship between urbanization and ecosystem services not only depends on the characteristics of the study area, but is closely related to the selected ecosystem services types and the indicators to measure urbanization level. Exploring the relationship in specific study area is necessary to support regional planning for sustainability. In this study, we analyzed the impacts of urbanization on ecosystem services from 2000 to 2010 in the Beijing-Tianjin-Hebei (BTH) urban megaregion in China. We quantified four critical ecosystem services, food production, carbon sequestration and oxygen production, water conservation, and soil retention, and identified the hotspots of ecosystem service provision. We measured the urbanization level from three aspects, namely, population growth, economic development and developed land expansion. The impacts of urbanization on the selected ecosystem services were examined at the hotspots scale and urban megaregion scale. We found both ecosystem services and urbanization level in the BTH region increased. There was an obvious spatial heterogeneity in the hotspots of ecosystem services, showing hotspots of food production aggregately distributed in the southern plain while hotspots of regulating services mainly located in the north mountainous areas with dense forest. The relationship between population growth, economic development and food production were represented by an inverse U-shaped curve, while it displayed a decreasing trend with regulating services. Both food production and regulating services decreased dramatically with urban land expansion. Additionally, the relationships between urbanization and ecosystem services were consistent across scales. Effective measures should be implemented for the hotspots of different types of ecosystem services to mitigate the loss of ecosystem services during rapid urbanization. The results can provide insights for enhancing urban sustainability in the BTH region, as well other urban megaregion with similar characteristics throughout the world.

Is there any link between economic growth and earth's environment? Evidence from 127 countries for the period 2007–2015

ABSTRACTWe investigate the relationship between economic growth and the earth's environment in 127 developing countries spreading all across the globe (Asia, Africa, Americas, Europe, and Polynesia) from 2007 to 2015. We use random effect estimation technique to check for an inverse U-shaped curve, or ‘Environmental Kuznets Curve (EKC)’. From our empirical results, we do not find any substantiation for this hypothesis. On the contrary, the empirical evidence suggests that there is an inverse U-shape relationship between environmental performance of a country and the per capita GDP for that country, which implies that, as per capita GDP increases, environmental performance improves but beyond some point, it starts to decrease resulting in an inverse U-shape curve. We alternately use the Growth Rate of GDP and GDP in constant 2010$ to obtain comparable results. We also use the average PM 2.5 air pollution, mean annual exposure (AU) of the World Development Indicators as an index of environmental pollution. When we replace EPI with AU and re-run the random effect model, find no evidence supporting EKC hypothesis, rather a U-shape curve and not an inverted U.

The Dose-Response Effect of Lycopene on Cerebral Vessel and Neuron Impairment Induced by Hyperlipidemia.

To study the dose-response effect of lycopene on vessel and neuron damage in the brain against hyperlipidemia, rats were fed with hypercholesterolemic feed and treated with lycopene orally by gavage at the dose of 5, 25, 45, 65, 85, and 105, 125 mg/kg/bw-1/d-1. At the end of the fourth week, lycopene doses and serum lycopene concentration showed an inverse U-shape curve. Serum lycopene concentration was negatively correlated with the levels of serum TC, TG, LDL-C, as well as the cerebral LDL-C, VEGF, and VCAM-1. Serum lycopene concentration was positively correlated with the expression of Claudin-5 and the number of neurons in hippocampal CA1 and CA3. Lycopene could also reduce the pathologic change of these areas. These results suggested an inverse U-shape relation between dose and serum concentration of lycopene, and intermediate doses were most effective to protect cerebral vessels and neurons from being damaged by hyperlipidemia.