Fluctuations In Growth Rate Research Articles

Endowment Structure, Industrial Structure, and the Fluctuation of Urban-rural Income Gap——An Analysis of New Structural Economics

Taking endowment structure as the starting point, this paper examines the determinants of urban-rural income gap fluctuation in China. Firstly, this paper proposes the core hypothesis through theoretical analysis and then proves it with the mathematical model. It shows that economic factors and policy factors jointly determine the fluctuation of endowment structure difference in urban and rural areas, and ultimately determines the fluctuation of the urban-rural income gap by determining the fluctuation of output growth rate. Secondly, this paper uses China's provincial panel data from 2006 to 2019 to empirically test the theoretical model, taking the relative index of urban and rural capital stock as the measure of the difference in endowment structure. The conclusion of this paper shows that the income gap between urban and rural areas is not an overnight result, but a fluctuating process. Policy measures can effectively narrow the urban-rural income gap by narrowing the urban and rural endowment structure gap.

Effect of color cross-correlated noise on the growth characteristics of tumor cells under immune surveillance.

Based on the Michaelis-Menten reaction model with catalytic effects, a more comprehensive one-dimensional stochastic Langevin equation with immune surveillance for a tumor cell growth system is obtained by considering the fluctuations in growth rate and mortality rate. To explore the impact of environmental fluctuations on the growth of tumor cells, the analytical solution of the steady-state probability distribution function of the system is derived using the Liouville equation and Novikov theory, and the influence of noise intensity and correlation intensity on the steady-state probability distributional function are discussed. The results show that the three extreme values of the steady-state probability distribution function exhibit a structure of two peaks and one valley. Variations of the noise intensity, cross-correlation intensity and correlation time can modulate the probability distribution of the number of tumor cells, which provides theoretical guidance for determining treatment plans in clinical treatment. Furthermore, the increase of noise intensity will inhibit the growth of tumor cells when the number of tumor cells is relatively small, while the increase in noise intensity will further promote the growth of tumor cells when the number of tumor cells is relatively large. The color cross-correlated strength and cross-correlated time between noise also have a certain impact on tumor cell proliferation. The results help people understand the growth kinetics of tumor cells, which can a provide theoretical basis for clinical research on tumor cell growth.

The influence of microstructure on short fatigue crack growth rates in Zircaloy-4: Crystal plasticity modelling and experiment

Rates of fatigue crack growth in Zircaloy-4 are highly microstructurally sensitive and dependent upon texture. Crystal plasticity finite element modelling with the eXtended Finite Element Method and a stored energy density fracture criterion are used to simulate crack propagation in single crystals and polycrystalline microstructures for comparison with experimental crack growth rate data. Results demonstrate that growth rate fluctuations at microstructural features are driven primarily by elastic anisotropy and yield stress mismatch. Additionally, reduced rate of growth in soft hexagonal close packed grains (relative to the remote loading direction) can be linked with crack path tortuosity, which is shown to be controlled by the cyclic development of an in-plane shear back stress. Most importantly, stored energy density is shown to accurately capture major microstructure-driven differences in crack growth rate. Comparison of simulated fatigue crack growth rates with experimental data enables estimation of the critical stored energy density for crack propagation in Zircaloy-4 to be 250 J/m2.

Statistical dynamics of wealth inequality in stochastic models of growth

Understanding the statistical dynamics of growth and inequality is a fundamental challenge to ecology and society. Recent analyses of wealth and income in contemporary societies show that economic inequality is very dynamic and that individuals experience substantially different wealth growth rates over time. However, despite a fast-growing body of evidence for the importance of fluctuations, we still lack a general statistical theory for understanding the dynamical effects of heterogeneous growth across a population. Here we derive the statistical dynamics of correlated wealth growth rates in heterogeneous populations. We show that correlations between growth rate fluctuations at the individual level influence aggregate population growth, while only driving inequality on short time scales. We also find that growth rate fluctuations are a much stronger driver of long-term inequality than income volatility. Our findings show that the dynamical effects of statistical fluctuations in growth rates are critical for understanding the emergence of inequality over time and motivate a greater focus on the properties and endogenous origins of growth rates in stochastic environments.

Interrelation Dynamics between Exchange Rate and Stock Market Returns in Egypt

This paper investigates the dynamics between exchange rate and stock market returns in Egypt that have been found to be interlinked with additional two variables, economic growth and inflation. To conduct such a research, the paper employed Autoregressive Distributed Lag (ARDL) model and Granger Causality tests using monthly data from Q1 2012 to Q3 2022. Econometric estimations prove that there exist a long run relationship among these four variables through the equation LNEGX30 = 1.1129 LNEXR + 2.3671 LNGDP – 2.5829 LNM2. The paper investigates that it is the stock market returns that lead to exchange rate fluctuations in the Egyptian economy. Similarly, the exchange rate volatilities lead to fluctuations in both economic growth rates and inflation rates. Indeed, stock market performance granger causes economic growth through a unidirectional causality that goes from stock market to economic growth. Therefore, the paper recommends several adjustments for the Egyptian financial policy through giving more incentives to over-performed and strong companies to be listed in the stock market. In addition, the Egyptian stock market is in need to develop newly established financial products, such as Exchange Traded Funds (ETFs), that would promote value and volume of trade in the market that would lead to boost economic growth. Finally, the central bank of Egypt, through reducing money supply growth rate, would target inflation rate to become one-digit to save the value of the Egyptian Pound from continuous devaluation and structural breaks.

Microstructurally short crack growth simulation combining crystal plasticity with extended finite element method

Accurate description of microstructurally short crack growth remains a long-standing challenging task, due to the fluctuation of crack growth rate induced by grain size and orientation, and grain boundary impediment. Combining crystal plasticity with extended finite element method, a novel framework for short crack growth prediction is proposed, where a new criterion for short crack propagation is established in terms of accumulated shear strain on specific slip system. Compared with three classic empirical models, the proposed method exhibits substantial advantage on the prediction of the fluctuation in FGH96 superalloy, serving as a promising tool for precise estimation of short crack growth rate in polycrystalline materials.

Effect of compositional fluctuation on the survival of bet-hedging species

Understanding the coexistence of diverse species in a changing environment is an important problem in community ecology. Bet-hedging is a strategy that helps species survive in such changing environments. However, studies of bet-hedging have often focused on the expected long-term growth rate of the species by itself, neglecting competition with other coexisting species. Here we study the extinction risk of a bet-hedging species in competition with others. We show that there are three contributions to the extinction risk. The first is the usual demographic fluctuation due to stochastic reproduction and selection processes in finite populations. The second, due to the fluctuation of population growth rate caused by environmental changes, may actually reduce the extinction risk for small populations. Besides those two, we reveal a third contribution, which is unique to bet-hedging species that diversify into multiple phenotypes: The phenotype composition of the population will fluctuate over time, resulting in increased extinction risk. We compare such compositional fluctuation to the demographic and environmental contributions, showing how they have different effects on the extinction risk depending on the population size, generation overlap, and environmental correlation.

우리나라 소지역 인구추계를 위한 방법론 비교 분석

Despite the recent increase in interest in population projections for small-areas such are si-gun-gu level units in South Korea, methodological studies on related matters are being conducted very limited. Therefore, the main objective of this study is to compare and analyze the characteristics of various methodological alternatives for small-area population projections using observation data. To this end, based on a review of previous studies on population projections for small areas, major methodologies were selected. In performing population projections for the selected methodologies, 20 execution-level methods are derived according to the applicable detailed plans or settings. For each method, population projections were performed targeting for year 2020 based on data from 2001-2010 at the si-gun-gu level in South Korea, and the results were analyzed. First, the compromise-share method and the biregional cohort-component method turned out to be almost equally superior in terms of the overall performance for the total population projection. Second, other characteristics were revealed when the estimation results were further examined in terms of population structure and spatio-temporal heterogeneity. The results of the biregional cohort-component method were excellent except for the population aged 0-4 and 25-34. In the short-term projections (5 years), the compromise-share method was the best,but the increase in error due to the increase in the estimation period was the lowest in the biregional cohort-component method. Areas with an error of more than 10% accounted for about 25%. They often experienced a great migration pattern change or a serious fluctuation in population growth rate during the estimation period. This study is expected to be a major reference in conducting population projections for various small-areas by presenting an empirical basis for the small-area population projections.

Nutrient-dependent allometric plasticity in a male-diphenic mite.

Male secondary sexual traits often scale allometrically with body size. These allometries can be variable within species and may shift depending on environmental conditions, such as food quality. Such allometric plasticity has been hypothesized to initiate local adaptation and evolutionary diversification of scaling relationships, but is under‐recorded, and its eco‐evolutionary effects are not well understood. Here, we tested for allometric plasticity in the bulb mite (Rhizoglyphus robini), in which large males tend to develop as armed adult fighters with thickened third legs, while small males become adult scramblers without thickened legs. We first examined the ontogenetic timing for size‐ and growth‐dependent male morph determination, using experimentally amplified fluctuations in growth rate throughout juvenile development. Having established that somatic growth and body size determine male morph expression immediately before metamorphosis, we examined whether the relationship between adult male morph and size at metamorphosis shifts with food quality. We found that the threshold body size for male morph expression shifts toward lower values with deteriorating food quality, confirming food‐dependent allometric plasticity. Such allometric plasticity may allow populations to track prevailing nutritional conditions, potentially facilitating rapid evolution of allometric scaling relationships.

Nucleation and Growth of an Ensemble of Crystals during the Intermediate Stage of a Phase Transition in Metastable Liquids

In this paper, an analytical method of solving the integro-differential system of kinetic and balance equations describing the evolution of an ensemble of crystals during the intermediate phase of the bulk crystallization process is described. The theory is developed for kinetic equations of the first- and second order corresponding to the absence and presence of fluctuations in particle growth rates. The crystal-size distribution function as well as the dynamics of metastability reduction in a supercooled melt (supersaturated solution) are analytically found using the saddle-point and the Laplace transform methods. The theory enables us to obtain the crystal-size distribution function that establishes in a supercooled (supersaturated) liquid at the beginning of the final stage of a phase transformation process when Ostwald ripening, coagulation and fragmentation of crystals are able to occur.

Oil Production and Carbon Emissions: Spline Analysis of Relationships

Obviously, the dynamics of carbon dioxide emissions depends on the volume and structure of consumption of primary energy resources in the economy. The world’s energy consumption shows a growth trend temporarily interrupted during times of economic crisis. The most noticeable decrease in energy consumption in modern history occurred in 2020, which was due to a decline in business activity in the world due to the COVID-19 pandemic. This caused a decrease in carbon emissions (by more than 6% compared to 2019). In the structure of primary energy sources, the largest reduction was in oil consumption. The paper examines the impact of economic crises on the evolution of the mutual link between the dynamics of oil production and carbon dioxide emissions in the world. To detect correlations in local time regions, it is proposed to interpolate process dynamics with cubic splines. Using this toolkit avoids the limitations of classical econometrics on the length of time series. The differentiability of the built spline models allowed us to move on to identifying and analyzing latent correlations in fluctuations in the instantaneous growth rate of oil production volumes and carbon emissions.

Pareto-optimal trade-off for phenotypic switching of populations in a stochastic environment

Finding optimal survival strategies of living systems embedded in fluctuating environments generally involves a balance between phenotypic diversification and sensing. If we neglect sensing mechanisms, it is known that slow, resp. fast, environmental transitions favor a regime of heterogeneous, resp. homogeneous, phenotypic response. We focus here on the simplest non-trivial case, i.e. two randomly switching phenotypes subjected to two stochastically switching environments. The optimal asymptotic (long term) growth rate of this model was studied elsewhere; we further expand these results by discussing finite time growth rate fluctuations. An exact asymptotic expression for the variance, alongside with approximations valid in different regimes, are tested numerically in details. Our simulations of the dynamics suggest a close connection between this variance and the extinction probability, understood as risk for the population. Motivated by an earlier trade-off analysis between average capital growth rate and risk in Kelly’s gambling model, we study the trade-off between the average growth rate and the variance in the present model. Despite considerable differences between the two models, we find similar optimal trade-off curves (Pareto fronts), suggesting that our conclusions are robust, and broadly applicable in various fields ranging from biology/ecology to economics.

Impact of Oil Price Fluctuations on Economic Growth, Financial Development, and Exchange Rate in Iraq: Econometric Approach

Oil is the main source of energy, which plays a pivotal role in the global economy. Therefore, its price fluctuations have a significant impact on the economy of the countries that trade oil. The objective of this study is to investigate the effects of oil price fluctuations on economic growth, financial development and exchange rate in Iraq. To achieve this objective, IRFs and VDCs, which are estimated from VAR, have been used. This study found that great fluctuations in economic growth, financial development, and exchange rate are due to oil price fluctuations. It is a reflection of oil resource mismanagement besides the rampant corruption in the state administrations additional to allocating most of financial resources to the war efforts when Iraq fought against terrorism. Therefore, it is necessary for the decision makers to adopt a certain strategy based on reducing the dependence of the Iraqi economy on crude oil. Prompting financial sector by developing well-regulated economic policies of economic diversity is needed as well. It could be done institutionally by regulating frameworks to build confidence in the economy and reducing the dominance of the public sector.

Statistical Dynamics of Wealth Inequality in Stochastic Models of Growth

Understanding the statistical dynamics of growth and inequality is a fundamental challenge to ecology and society. Recent analyses of wealth and income dynamics in contemporary societies show that economic inequality is very dynamic and that individuals experience substantially different growth rates over time. However, despite a fast growing body of evidence for the importance of fluctuations, we still lack a general statistical theory for understanding the dynamical effects of heterogeneneous growth across a population. Here we derive the statistical dynamics of correlated growth rates in heterogeneous populations. We show that correlations between growth rate fluctuations at the individual level influence aggregate population growth, while only driving inequality on short time scales. We also find that growth rate fluctuations are a much stronger driver of long-term inequality than earnings volatility. Our findings show that the dynamical effects of statistical fluctuations in growth rates are critical for understanding the emergence of inequality over time and motivate a greater focus on the properties and endogenous origins of growth rates in stochastic environments.

Merenje i analiza dinamike privrednog rasta u evropskim zemljama

In this paper, the quantitative aspect of economic growth, i.e. its dynamics, is dealt with. Although it is common to observe the growth rate (intensity) when analyzing the growth dynamics of countries while neglecting growth variability, the fact that covering fluctuations in growth rates has clear motivation and practical significance is presented. On a sample of European countries, including Serbia, growth intensity and stability are analyzed in the paper in order to construct a growth dynamics indicator and an adjusted growth rate based upon these two components. Based upon the two constructed indicators, the position of each country in the sample and in the region (Western and Eastern Europe) which they belong to is analyzed. The detailed analysis and results indicate the importance of this approach when analyzing and comparing the economic growth of individual countries in the medium term and in the long term and when assessing effects on future economic growth and wellbeing.

Research on the Impact of Investment Efficiency of China’s Commercial Economy on Industrial Structure Adjustment Based on Cloud Computing

The adjustment and upgrading of industrial structure is an important issue in macroeconomic development. Through the optimization of resource allocation structure, the overall efficiency and effectiveness of the national economy can be improved. When the investment opportunity is good, the industrial policy can guide the enterprise to invest, which has the significant effect on the investment efficiency. This paper focuses on the impact of China’s OFDI (Outward Foreign Direct Investment) on the upgrading of industrial structure. First of all, this paper combs the research results of domestic and foreign scholars on this topic and describes the main influencing factors of industrial structure upgrading. Secondly, the construction of the empirical model, based on cloud computing, big data analysis, using the grey correlation model. According to China’s development situation, the introduction of industrial structure upgrading, three levels of industrial integration, the whole society’s investment in fixed assets, GDP per capita, financial development indicators to measure the level of technological progress and establish an empirical model for analysis. The empirical results show that China’s OFDI has a positive effect on the industrial structure, but this effect is not significant. The lag of investment rate, the fluctuation of income growth rate, the short-term fluctuation of variables such as tax, relative price of capital, research and development expenditure and human capital stock have significant influence on investment rate. Finally, on basis of the research results, the paper puts forward relevant countermeasures and suggestions on how to use OFDI more effectively to promote the upgrading of industrial structure.

Identifying the Main Factors of Iran’s Economic Growth Using Growth Accounting Framework

This paper aims to present empirical analysis of Iranian economic growth from 1950 to 2018 using data from the World Bank, Madison Data Bank, Statistical Center of Iran, and Central Bank of Iran. The results show that Gross Domestic Product (GDP) per capital increased by 2 percent annually during this time, however this indicator has had a huge fluctuation over time. In addition, the economic growth of Iran and oil revenue have close relationship with each other. In fact, whenever oil crises happen, great fluctuation in growth rate and other indicators happened subsequently. Even though the shares of other sectors like industry and services in GDP have increased over time, the oil sector still plays a key role in the economic growth of Iran. Moreover, growth accounting analysis shows contribution of capital plays a significant role in economic growth of Iran. Furthermore, based on growth accounting framework the steady state of effective capital is 4.27 for Iran’s economy.

The effect of nanoindentation on crystal growth rate fluctuations investigated by in-situ atomic force microscopy

In this article the results of direct observations of elementary processes of crystal growth using AFM are presented. A method of statistical processing of AFM data was developed, which made it possible to compile an array of average tangential and average normal growth rates and their fluctuations. Nanoindentation was applied to a growing spiral hillock; intensified fluctuations and simultaneous growth and dissolution were recorded within a local area. The behavior of average rates, characterized as self-oscillations, suggests self-organization of the system. Comparison of the data obtained in the experiment with those obtained from the other experiments where no nanoindentation was applied indicates that the phenomena of intensified fluctuations and simultaneous growth and dissolution are caused by the nanoindentor action.

Application of QSAR for the identification of key molecular fragments and reliable predictions of effects of textile dyes on growth rate and biomass values of Raphidocelis subcapitata.

The current quantitative structure-activity relationship (QSAR) study seeks to explore the underlying causes of fluctuations in growth rate and biomass of microalgae mainly due to textile dyes. The derived QSAR models cover two endpoints: ErC50 (growth rate) and EbC50 (biomass) of Raphidocelis subcapitata. In order to extract the structural features involved, multiple PLS (partial least squares) models have been developed with easy to interpret and uncomplicated 2D descriptors having proper physico-chemical meaning. These descriptors were calculated from Dragon, SiRMS, and PaDEL-descriptor software. Then, the models were developed initially using stepwise regression followed by partial least squares (PLS) regression, and the model development procedure for both the endpoints (ErC50 and EbC50) followed the stringent Organization for Economic Cooperation and Development (OECD) rules. Later on, the model validation was carried out with statistically significant and internationally accepted metrics (both internally and externally) in both the cases. Next, we have used the "Intelligent Consensus Predictor" tool (available from http://teqip.jdvu.ac.in/QSAR_Tools/DTCLab/) to test the prediction quality with an "intelligent" approach to select multiple models. The estimated prediction quality for the appropriate test sets reveals that the consensus models (CM) surpass the quality shown by individual models (IM) for both the endpoints (ErC50 and EbC50). Finally, the developed models were able to identify the major contributing features (hydrophobic units, unsaturation, saturation, electronegativity, branched atoms and charged fragments) related to aquatic toxicity of textile dyes.

XMAP215 promotes microtubule catastrophe by disrupting the growing microtubule end.

The GTP-tubulin cap is widely accepted to protect microtubules against catastrophe. The GTP-cap size is thought to increase with the microtubule growth rate, presumably endowing fast-growing microtubules with enhanced stability. It is unknown what GTP-cap properties permit frequent microtubule catastrophe despite fast growth. Here, we investigate microtubules growing in the presence and absence of the polymerase XMAP215. Using EB1 as a GTP-cap marker, we find that GTP-cap size increases regardless of whether growth acceleration is achieved by increasing tubulin concentration or by XMAP215. Despite increased mean GTP-cap size, microtubules grown with XMAP215 display increased catastrophe frequency, in contrast to microtubules grown with more tubulin, for which catastrophe is abolished. However, microtubules polymerized with XMAP215 have large fluctuations in growth rate; display tapered and curled ends; and undergo catastrophe at faster growth rates and with higher EB1 end-localization. Our results suggest that structural perturbations induced by XMAP215 override the protective effects of the GTP-cap, ultimately driving microtubule catastrophe.