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Showing 345 results for Growth
Volume 0, Issue 0 (3-2023)
Abstract
Urban growth boundaries are considered one of the key tools for controlling and managing the physical development of metropolitan areas. Uncontrolled and unplanned expansion in these regions has become a major challenge for urban and regional planners and managers, as this process leads to the destruction of agricultural lands and natural resources. The aim of this research is to simulate and assess future changes in growth boundaries in the Isfahan metropolitan area with the goal of preserving environmental resources and controlling physical expansion. In this regard, by adopting a positivist approach that follows an analytical and measurement-driven process, satellite imagery was utilized to assess changes in the physical expansion of the Isfahan metropolitan area. Artificial neural networks and machine learning algorithms were employed to predict the extent of future physical growth, and the projected growth boundaries were delineated. The research findings indicate that the Isfahan metropolitan area has experienced significant uncontrolled expansion, particularly in terms of physical development, over recent decades, and the reduction of agricultural and natural lands has become one of its major challenges. Based on the conducted simulations, the proposed growth boundaries can serve as an effective tool for managing and planning urban-regional development and preventing further degradation of natural resources and lands.
Volume 0, Issue 0 (1-2024)
Abstract
Increasing need for drought adaptation measures to conserve water and sustain crop yield in water-scarce regions, driven by severe and recurrent droughts. Achieving sustainable production entails studying deficit irrigation as a means to enhance water productivity and selecting genotypes resilient to soil water deficits. In the present study, 17 different melon (Cucumis melo L.) genotypes collected from the Van Lake Basin and 3 hybrids and 1 standard melon cultivar for control purposes were used. The study was carried out under climate room conditions. Two different irrigation levels (I100: 100% full irrigation, I50: 50% deficit irrigation-DI) were applied in the study for deficit irrigation. The applications started with the emergence of the second true leaves of the plants and after one-month, different growth, nutrient, and enzyme contents of the seedlings were determined. In general, it was determined that deficit water application negatively affects seedling growth, and and root dry matter, stomatal width and density, potassium, APX and SOD enzymes, and MDA content increased, while the other examined parameters decreased. The genotypes of the Van Lake Basin melon were found to vary as a result of the findings.
Volume 0, Issue 0 (1-2024)
Abstract
This study aimed to evaluate the capability of the halophyte A. littoralis in symbiosis with Rhizophagus intraradices and Nocardia Halotolerans an indigenous bacterium of saline soils- on phytoextraction of Na under saline conditions. Salinity treatments included 0 (S0), 100 mM NaCl (S1), 200 mM NaCl (S2), 100 mM NaCl+50mM K2SO4 (S3), 200 mM NaCl+50mM K2SO4 (S4) levels. Plant fresh and dry weight, chlorophyll content decreased as salinity increased up to S2 level and increased thereafter. Plant root colonization in the inoculation and co-inoculation of AMF+SR-PGPB were similar. Compared to the S0 treatment, root colonization in the AMF group decreased by 23.5%, 32.6%, 13.5%, and 26.7% under S1, S2, S3, and S4 treatments, respectively. In the Bacteria+AMF group, the reduction was smaller, with decreases of 2.8%, 3.4%, and an increase of 6.8% and 1.4% under S1, S2, S3, and S4 treatments, respectively. These results indicate that co-inoculation with PGPB mitigated the negative effects of salinity on root colonization. The root and soil glomalin contents increased as salinity increased. Root glomalin in plants inoculated by AMF+SR-PGPB was more than in a single inoculation of AMF under salt stress. This study highlights the potential application of salt-tolerant bacteria and AMF as effective strategies for enhancing plant growth and productivity in saline environments, contributing to sustainable agricultural practices in affected regions.
Volume 0, Issue 0 (1-2024)
Abstract
The predatory mite, Euseius scutalis (Athias-Henriot), was studied in terms of its development, survival, and life table parameters on two preimaginal stages (egg and first instar nymph) of its prey, Bemisia tabaci (Gennadius) (Hem.: Aleyrodidae). The first instar nymphs of B. tabaci were found to be the preferred food for E. scutalis, resulting in decreased developmental time from egg to adult, as well as a shorter pre-oviposition period and a higher rate of oviposition. The intrinsic rate of increase (r) was found to be 0.1503 day-1 on first instar nymphs and 0.0843 day-1 on eggs of the prey. On average, females E. scutalis consumed 16.30 eggs and 29.40 nymphs from their emergence to death. When first instar nymphs of B. tabaci were provided, E. scutalis showed a higher net predation rate (C0) and finite predation rate (ω) compared to feeding on eggs. On average, it consumed 3.52 eggs or 2.76 first instar nymphs of B. tabaci to produce a single egg of E. scutalis. In terms of the progeny sex ratio of the progeny, predatory females that fed on first instar nymphs produce more females.
Volume 0, Issue 0 (12-2024)
Abstract
Aim and Introduction:
A growing body of research highlights the bidirectional relationship between conflict and economic performance. Findings indicate that economic decline—particularly severe recessions that reduce income levels, exacerbate inequalities, and intensify widespread economic distress—can fuel social unrest and internal conflicts. Periods characterized by a high risk of government collapse are associated with significantly lower rates of economic growth compared to more politically stable periods. Although such violent events may not occur frequently, they are prevalent worldwide and have affected numerous countries.
The Middle East, in particular, has long been afflicted by internal unrest, persistent conflicts, and intra- and intergovernmental tensions—all of which adversely influence national economies. Political economy literature underscores a complex interplay between political forces and economic direction, suggesting that political instability can disrupt economic continuity and hinder economic growth—a central indicator of national economic performance.
Accordingly, the primary objective of this study is to model the effects of political instability and conflict on economic growth in a sample of developing and developed countries, namely Iran, Iraq, Saudi Arabia, Russia, the United States, India, China, and Canada.
Methodology:
This study adopts a descriptive-analytical approach with practical applications, relying on secondary data collected through documentary research. The analytical method employed is the Bayesian Markov Switching Panel Regression, which effectively captures symmetric and asymmetric effects across different economic regimes.
The selected countries—spanning both developed and developing contexts—include Iran, Iraq, and Saudi Arabia, which have historically faced political tension and oil revenue fluctuations, as well as Russia, Canada, the United States, India, and China. The inclusion of India and China reflects their status as major global energy consumers. These countries were chosen based on their exposure to international tensions and their substantial influence on the global energy landscape.
The study period covers 1990 to 2020. The Markov switching panel framework enables the model to differentiate the impact of explanatory variables across distinct economic regimes. For instance, political stability may influence economic growth differently during recessionary periods compared to times of economic expansion. The variables analyzed include conflict intensity, political instability, oil income, population growth, foreign direct investment, life expectancy, government expenditure, budget deficits, trade openness, and the governance quality index.
Results and Discussion:
The analysis reveals that conflict and economic instability exert statistically significant effects on economic growth across both recession and growth regimes. In the recession regime, the coefficients for conflict and instability are 0.17% and 0.12%, respectively, while in the growth regime, they are slightly lower at 0.16% and 0.11%. Although both variables remain significant in both regimes, their influence is more pronounced during recessions, implying that political instability and conflict are more detrimental to growth when the economy is already underperforming.
These findings are consistent with prior research by Ashenfelter and Troeger (2006), Gaybulov and Sandler (2019), and Bart et al. (2021). Additionally, variables such as oil income, population growth, foreign direct investment, life expectancy, government expenditure, trade openness, and governance quality all exhibit positive and statistically significant effects on economic growth in both regimes.
The dominant economic regime identified in the study is the growth regime. Notably, with the exception of Iraq, Iran, and Saudi Arabia, the other countries analyzed have been experiencing economic growth in recent years. This observation underscores the correlation between political stability and sustained economic performance.
Conclusion:
The findings of this research emphasize the critical role of political stability in fostering a robust and resilient economic environment. A stable political climate is not only essential for social cohesion but also serves as a prerequisite for sustained economic growth and development. Policymakers are thus encouraged to invest in institutional reforms, infrastructure development, and inclusive governance frameworks that enhance citizens’ participation in decision-making processes. These measures can significantly contribute to both political stability and long-term economic prosperity in the countries under study.
A growing body of research highlights the bidirectional relationship between conflict and economic performance. Findings indicate that economic decline—particularly severe recessions that reduce income levels, exacerbate inequalities, and intensify widespread economic distress—can fuel social unrest and internal conflicts. Periods characterized by a high risk of government collapse are associated with significantly lower rates of economic growth compared to more politically stable periods. Although such violent events may not occur frequently, they are prevalent worldwide and have affected numerous countries.
The Middle East, in particular, has long been afflicted by internal unrest, persistent conflicts, and intra- and intergovernmental tensions—all of which adversely influence national economies. Political economy literature underscores a complex interplay between political forces and economic direction, suggesting that political instability can disrupt economic continuity and hinder economic growth—a central indicator of national economic performance.
Accordingly, the primary objective of this study is to model the effects of political instability and conflict on economic growth in a sample of developing and developed countries, namely Iran, Iraq, Saudi Arabia, Russia, the United States, India, China, and Canada.
Methodology:
This study adopts a descriptive-analytical approach with practical applications, relying on secondary data collected through documentary research. The analytical method employed is the Bayesian Markov Switching Panel Regression, which effectively captures symmetric and asymmetric effects across different economic regimes.
The selected countries—spanning both developed and developing contexts—include Iran, Iraq, and Saudi Arabia, which have historically faced political tension and oil revenue fluctuations, as well as Russia, Canada, the United States, India, and China. The inclusion of India and China reflects their status as major global energy consumers. These countries were chosen based on their exposure to international tensions and their substantial influence on the global energy landscape.
The study period covers 1990 to 2020. The Markov switching panel framework enables the model to differentiate the impact of explanatory variables across distinct economic regimes. For instance, political stability may influence economic growth differently during recessionary periods compared to times of economic expansion. The variables analyzed include conflict intensity, political instability, oil income, population growth, foreign direct investment, life expectancy, government expenditure, budget deficits, trade openness, and the governance quality index.
Results and Discussion:
The analysis reveals that conflict and economic instability exert statistically significant effects on economic growth across both recession and growth regimes. In the recession regime, the coefficients for conflict and instability are 0.17% and 0.12%, respectively, while in the growth regime, they are slightly lower at 0.16% and 0.11%. Although both variables remain significant in both regimes, their influence is more pronounced during recessions, implying that political instability and conflict are more detrimental to growth when the economy is already underperforming.
These findings are consistent with prior research by Ashenfelter and Troeger (2006), Gaybulov and Sandler (2019), and Bart et al. (2021). Additionally, variables such as oil income, population growth, foreign direct investment, life expectancy, government expenditure, trade openness, and governance quality all exhibit positive and statistically significant effects on economic growth in both regimes.
The dominant economic regime identified in the study is the growth regime. Notably, with the exception of Iraq, Iran, and Saudi Arabia, the other countries analyzed have been experiencing economic growth in recent years. This observation underscores the correlation between political stability and sustained economic performance.
Conclusion:
The findings of this research emphasize the critical role of political stability in fostering a robust and resilient economic environment. A stable political climate is not only essential for social cohesion but also serves as a prerequisite for sustained economic growth and development. Policymakers are thus encouraged to invest in institutional reforms, infrastructure development, and inclusive governance frameworks that enhance citizens’ participation in decision-making processes. These measures can significantly contribute to both political stability and long-term economic prosperity in the countries under study.
Volume 0, Issue 0 (12-2024)
Abstract
Aim and Introduction
Many theories and models of economic growth have identified capital as one of the most important drivers and determinants of economic growth and development. For years, it was believed that abundant natural resources, as part of a country’s capital, constituted a divine blessing, as they could be converted into other forms of capital and contribute to overall economic development. Consequently, countries rich in natural resources were expected to perform better economically than those without such resources. However, over time, particularly after World War II, empirical evidence revealed that most resource-rich countries performed poorly compared to resource-poor countries.
some empirical studies have highlighted a positive relationship between natural resource abundance and economic growth. Stijns (2001), using an alternative variable from Sachs and Warner (1995) to measure resource abundance, found no evidence of the detrimental effect of natural resources on economic growth. Lederman and Maloney (2003) also reported a positive relationship between resource abundance (measured by net resource exports per worker) and economic growth.
Sala-i-Martin and Subramanian (2003) contended that the relationship between natural resource abundance and economic growth loses statistical significance once institutional quality is accounted for. They suggested that the effect of natural resources depends on the type of resource, indicating that fuel and mineral resources negatively affect institutions (and thus economic growth), whereas the relationship between economic growth and other types of resources is not statistically significant. Similarly, Papyrakis and Gerlagh (2004) demonstrated that when variables such as corruption, investment, degree of freedom, terms of trade, and education are controlled and managed, the abundance of natural resources would have a positive effect on economic growth.
Thus, it can be concluded that not all resource-rich countries have experienced poor economic performance or economic decline. In certain cases, the optimal utilization of abundant resources has led to significant economic growth and increased per capita income.
Economic growth remains the primary goal of all economies, as it is directly linked to maximizing societal welfare. Economic growth encompasses increased utilization of inputs, improved productivity of production factors, and enhanced employment opportunities. Natural resources are among the most crucial sources of production in any country. According to growth and development theories, as well as international trade theories, these resources can provide a comparative advantage for an economy. Income generated from natural resource abundance can create national wealth, spur economic progress, increase societal welfare, and reduce poverty. In this regard, mineral resources are considered a key factor in accelerating investment and economic growth.
Methodology
This study examines the economic growth patterns of Iran and a group of mineral-rich countries from 2000 to 2020. A panel data method was employed to estimate and evaluate the results, considering the similarities between the selected countries and Iran in terms of mineral resource abundance.
In the research process, the final variables and the functional form of the model were identified, and data processing, analysis, and model estimation were conducted using Stata software. The data used in the study were collected from official sources, including the Central Bank, the Statistical Center of Iran, and the Ministry of Industry, Mine, and Trade. Additionally, for data on other countries, international sources such as the World Trade Organization (WTO), the World Bank, the Organization for Economic Cooperation and Development (OECD), and the International Monetary Fund’s (IMF) STAN database were utilized.
Findings
The study investigated the direct and indirect effects of natural resource abundance on economic growth through channels such as physical capital accumulation, research and development (R&D) investment in technology, labor, financial development, and economic freedom across three groups of countries. The first group includes countries with both mineral resources and oil, the second group consists of countries with only minerals, and the third group comprises countries with only oil resources. The generalized fixed effects model was selected as the final model for all three groups. According to the results:
The results suggest that the hypothesis of natural resource abundance positively influencing economic growth is supported for the first and second groups of countries. However, this hypothesis is not confirmed for the third group, which includes Iran.
The findings underscore that the impact of natural resources on economic growth is contingent upon various factors, including the type of resource, the quality of institutions, and the effectiveness of economic and governance policies. While some resource-rich countries have successfully translated their natural wealth into economic prosperity, others, including Iran, have faced challenges in maximizing the economic benefits of their natural resources.
Many theories and models of economic growth have identified capital as one of the most important drivers and determinants of economic growth and development. For years, it was believed that abundant natural resources, as part of a country’s capital, constituted a divine blessing, as they could be converted into other forms of capital and contribute to overall economic development. Consequently, countries rich in natural resources were expected to perform better economically than those without such resources. However, over time, particularly after World War II, empirical evidence revealed that most resource-rich countries performed poorly compared to resource-poor countries.
some empirical studies have highlighted a positive relationship between natural resource abundance and economic growth. Stijns (2001), using an alternative variable from Sachs and Warner (1995) to measure resource abundance, found no evidence of the detrimental effect of natural resources on economic growth. Lederman and Maloney (2003) also reported a positive relationship between resource abundance (measured by net resource exports per worker) and economic growth.
Sala-i-Martin and Subramanian (2003) contended that the relationship between natural resource abundance and economic growth loses statistical significance once institutional quality is accounted for. They suggested that the effect of natural resources depends on the type of resource, indicating that fuel and mineral resources negatively affect institutions (and thus economic growth), whereas the relationship between economic growth and other types of resources is not statistically significant. Similarly, Papyrakis and Gerlagh (2004) demonstrated that when variables such as corruption, investment, degree of freedom, terms of trade, and education are controlled and managed, the abundance of natural resources would have a positive effect on economic growth.
Thus, it can be concluded that not all resource-rich countries have experienced poor economic performance or economic decline. In certain cases, the optimal utilization of abundant resources has led to significant economic growth and increased per capita income.
Economic growth remains the primary goal of all economies, as it is directly linked to maximizing societal welfare. Economic growth encompasses increased utilization of inputs, improved productivity of production factors, and enhanced employment opportunities. Natural resources are among the most crucial sources of production in any country. According to growth and development theories, as well as international trade theories, these resources can provide a comparative advantage for an economy. Income generated from natural resource abundance can create national wealth, spur economic progress, increase societal welfare, and reduce poverty. In this regard, mineral resources are considered a key factor in accelerating investment and economic growth.
Methodology
This study examines the economic growth patterns of Iran and a group of mineral-rich countries from 2000 to 2020. A panel data method was employed to estimate and evaluate the results, considering the similarities between the selected countries and Iran in terms of mineral resource abundance.
In the research process, the final variables and the functional form of the model were identified, and data processing, analysis, and model estimation were conducted using Stata software. The data used in the study were collected from official sources, including the Central Bank, the Statistical Center of Iran, and the Ministry of Industry, Mine, and Trade. Additionally, for data on other countries, international sources such as the World Trade Organization (WTO), the World Bank, the Organization for Economic Cooperation and Development (OECD), and the International Monetary Fund’s (IMF) STAN database were utilized.
Findings
The study investigated the direct and indirect effects of natural resource abundance on economic growth through channels such as physical capital accumulation, research and development (R&D) investment in technology, labor, financial development, and economic freedom across three groups of countries. The first group includes countries with both mineral resources and oil, the second group consists of countries with only minerals, and the third group comprises countries with only oil resources. The generalized fixed effects model was selected as the final model for all three groups. According to the results:
- The share of mineral resources in exports was significant and positive for the first and second groups of countries, whereas it was significant and negative for the third group, which includes Iran.
- The share of oil and gas resources in exports was significant and positive for the first group of countries, but it had a significant negative impact for the third group.
- The unemployment rate had a significant negative relationship with per capita income across all groups.
- The total factor productivity index was positive and significant for all groups, positively influencing per capita income.
- Research and development expenditures had a significant positive effect on per capita income across all groups.
- The economic openness index was significant for all groups, positively affecting per capita income.
- The institutional quality index was significant for all groups, positively influencing per capita income.
- The net foreign direct investment variable was significant for the second group but had a negative effect.
The results suggest that the hypothesis of natural resource abundance positively influencing economic growth is supported for the first and second groups of countries. However, this hypothesis is not confirmed for the third group, which includes Iran.
The findings underscore that the impact of natural resources on economic growth is contingent upon various factors, including the type of resource, the quality of institutions, and the effectiveness of economic and governance policies. While some resource-rich countries have successfully translated their natural wealth into economic prosperity, others, including Iran, have faced challenges in maximizing the economic benefits of their natural resources.
Volume 0, Issue 0 (12-2024)
Abstract
Aim and Introduction
After the global economic recession in 2008-2009, the discussion about countercyclical and procyclical fiscal policies and their effects on the economy began. Countercyclical fiscal policy is applied to reduce economic fluctuations by adjusting government spending and taxes against the business cycle. The aim of this policy is to stabilize the economy and flatten its fluctuations. On the contrary, procyclical fiscal policy strengthens economic fluctuations in the direction of business cycles. On the other hand, fiscal sustainability refers to the government's ability to maintain expenditures, income and public debt at a certain level in the long term without jeopardizing economic stability or facing a fiscal crisis. A sustainable fiscal policy ensures that the government's debt in the long run is at a level proportional to the size of the economy. The main questions of this research are as follows:
After the global economic recession in 2008-2009, the discussion about countercyclical and procyclical fiscal policies and their effects on the economy began. Countercyclical fiscal policy is applied to reduce economic fluctuations by adjusting government spending and taxes against the business cycle. The aim of this policy is to stabilize the economy and flatten its fluctuations. On the contrary, procyclical fiscal policy strengthens economic fluctuations in the direction of business cycles. On the other hand, fiscal sustainability refers to the government's ability to maintain expenditures, income and public debt at a certain level in the long term without jeopardizing economic stability or facing a fiscal crisis. A sustainable fiscal policy ensures that the government's debt in the long run is at a level proportional to the size of the economy. The main questions of this research are as follows:
- Is Iran's fiscal policy countercyclical or procyclical?
- Is Iran's fiscal policy sustainable?
- What is the effect of cyclical fiscal policy and fiscal sustainability on the Iranian economic growth?
- How is the mutual relationship between fiscal sustainability and cyclical fiscal policy in Iran?
Methodology
The evaluation of fiscal policy cyclicality and fiscal sustainability and their determinants have been previously researched. However, the effect of cyclical fiscal policy and fiscal sustainability on economic growth and their mutual relationship has not been covered. This research, has utilized Iran's 1970-2021 annual data and a state-space model with time-varying parameters and an autoregressive distributed lags model as well as Kalman filter method. Moreover, to evaluate Iran's cyclical fiscal policy and fiscal sustainability, the effect of cyclical fiscal policy and fiscal sustainability on economic growth have been investigated. The research also deals with the mutual effect between cyclical fiscal policy and fiscal sustainability in Iran.
Findings
In this research, in order to evaluate the cyclical behavior of Iran's fiscal policy and obtaining the index, a state-space model with time-varying parameters, is estimated in which the real GDP logarithm coefficient varies over time. Then, in order to assess Iran's fiscal sustainability and obtaining the index, a state-space model with time-varying parameters is estimated. Finally, an autoregressive distributed lags model is utilized to estimate the effect of cyclical fiscal policy index and fiscal sustainability index on economic growth, as well as estimating the mutual effect between cyclical fiscal policy index and fiscal sustainability index.
Discussion and Conclusion
The findings of this research show: First, Iran's cyclical fiscal policy index estimated in all years is positive and has not recorded a negative number in any year, which means that the fiscal policy implemented in Iran during the period 1970-2021, was procyclical. In other words, the fiscal policy implemented in Iran has increased the range of fluctuations of cycles and for this reason, it has made the Iranian economy vulnerable to the economic shocks. Second, the estimated Iran's fiscal sustainability index is negative in most years so that the average fiscal sustainability index in the entire period is -0.068. This indicates the unsustainability of Iran's fiscal policy in the period 1970-2021. The trend of the smoothed changes of the time-varying parameter related to the fiscal sustainability index is also downward, which means that Iran's fiscal sustainability has been weakening over time and has moved in the direction of unsustainability. Third, Iran's cyclical fiscal policy index has had a negative effect on economic growth. In other words, procyclical behavior of Iran's fiscal policy has slowed down the economic growth rate. Fourth, Iran's fiscal sustainability index has a negative and significant effect on economic growth. Based on the estimated fiscal sustainability index, unsustainability is evident within Iran's fiscal policy. Therefore, unsustainability of Iran's fiscal policy has weakened economic growth. Fifth, Iran's fiscal unsustainability has increased the procyclical behavior of fiscal policy and as a result, exacerbated the fluctuations of economic cycles. Sixth, the increasing Iran's cyclical fiscal policy index reduces the reaction of the primary balance to the government debt. In other words, the increase in the procyclical behavior of the fiscal policy weakens Iran's fiscal sustainability
The evaluation of fiscal policy cyclicality and fiscal sustainability and their determinants have been previously researched. However, the effect of cyclical fiscal policy and fiscal sustainability on economic growth and their mutual relationship has not been covered. This research, has utilized Iran's 1970-2021 annual data and a state-space model with time-varying parameters and an autoregressive distributed lags model as well as Kalman filter method. Moreover, to evaluate Iran's cyclical fiscal policy and fiscal sustainability, the effect of cyclical fiscal policy and fiscal sustainability on economic growth have been investigated. The research also deals with the mutual effect between cyclical fiscal policy and fiscal sustainability in Iran.
Findings
In this research, in order to evaluate the cyclical behavior of Iran's fiscal policy and obtaining the index, a state-space model with time-varying parameters, is estimated in which the real GDP logarithm coefficient varies over time. Then, in order to assess Iran's fiscal sustainability and obtaining the index, a state-space model with time-varying parameters is estimated. Finally, an autoregressive distributed lags model is utilized to estimate the effect of cyclical fiscal policy index and fiscal sustainability index on economic growth, as well as estimating the mutual effect between cyclical fiscal policy index and fiscal sustainability index.
Discussion and Conclusion
The findings of this research show: First, Iran's cyclical fiscal policy index estimated in all years is positive and has not recorded a negative number in any year, which means that the fiscal policy implemented in Iran during the period 1970-2021, was procyclical. In other words, the fiscal policy implemented in Iran has increased the range of fluctuations of cycles and for this reason, it has made the Iranian economy vulnerable to the economic shocks. Second, the estimated Iran's fiscal sustainability index is negative in most years so that the average fiscal sustainability index in the entire period is -0.068. This indicates the unsustainability of Iran's fiscal policy in the period 1970-2021. The trend of the smoothed changes of the time-varying parameter related to the fiscal sustainability index is also downward, which means that Iran's fiscal sustainability has been weakening over time and has moved in the direction of unsustainability. Third, Iran's cyclical fiscal policy index has had a negative effect on economic growth. In other words, procyclical behavior of Iran's fiscal policy has slowed down the economic growth rate. Fourth, Iran's fiscal sustainability index has a negative and significant effect on economic growth. Based on the estimated fiscal sustainability index, unsustainability is evident within Iran's fiscal policy. Therefore, unsustainability of Iran's fiscal policy has weakened economic growth. Fifth, Iran's fiscal unsustainability has increased the procyclical behavior of fiscal policy and as a result, exacerbated the fluctuations of economic cycles. Sixth, the increasing Iran's cyclical fiscal policy index reduces the reaction of the primary balance to the government debt. In other words, the increase in the procyclical behavior of the fiscal policy weakens Iran's fiscal sustainability
Volume 0, Issue 0 (12-2024)
Abstract
Aim and Introduction
Economic and social instability, insecurity, and poor governance significantly increase transaction costs and investment risks while reducing incentives for productive economic activities. Institutional conditions and the political environment are fundamental factors influencing economic growth, as they affect the motivations of economic agents and thereby influence investment decisions, production organization, and overall economic performance. Macroeconomic instability, as an undesirable phenomenon, imposes both economic and social costs on society. Its persistence disturbs the national economic structure and diminishes household welfare by undermining financial security and increasing economic uncertainty.
Furthermore, effective economic policy-making and national development planning require a comprehensive understanding of the economy’s formal and informal sectors. The informal or underground economy includes activities outside the scope of official oversight, such as unregistered income, tax evasion, and operations beyond legal, social, and economic regulations. These activities are typically excluded from official GDP calculations but represent a significant share of economic production.
Modern definitions of economic growth encompass not only increases in GDP but also broader improvements in societal economic well-being. Notably, economic production occurs in both formal and informal sectors; thus, a thorough analysis of both is essential for developing effective and inclusive growth strategies. This study aims to evaluate the influence of political and economic risk, instability, and governance quality on both sectors of Iran’s economy over the period 1370–1401 (1991–2022). To achieve this, relevant indices were constructed to measure risk and instability in economic, financial, and social domains, as well as Iran’s governance performance, with the goal of identifying key determinants of formal sector strengthening and informal sector reduction.
Methodology
This research employs an endogenous growth model to investigate the factors influencing economic growth in Iran. Data on the underground economy are drawn from estimates produced using the Multiple Indicators and Multiple Causes (MIMIC) model. The methodological framework combines econometric techniques, notably Principal Component Analysis (PCA) and the Autoregressive Distributed Lag (ARDL) model.
PCA is applied to construct composite indices where multiple explanatory variables are involved, particularly in capturing instability and governance indicators. ARDL is used to examine relationships among variables, given the mixed order of integration in the time series data. This dual approach enables the study to assess the impact of governance, risk, and economic instability on both the formal and informal economic sectors.
Results and Discussion
The results show that within the economic growth function, property rights and political management exert a positive influence, while economic instability and international sanctions negatively affect Iran’s economic growth. Specifically, an increase of one unit in the political management index results in a 3.0033% increase in economic growth, whereas a one-unit rise in the economic instability index leads to a 0.1935% decline in growth.
In analyzing the informal (underground) economy, the study finds that increased risk and instability, unemployment, government size, tax revenues, and sanctions all contribute to the expansion of the informal sector. Conversely, improvements in political management reduce informal economic activities. Notably, the risk and instability index shows a high impact, with a coefficient of 3.99, signifying its strong correlation with the growth of Iran’s underground economy.
Conclusion
Improved political management enhances formal economic activity while suppressing informal sector expansion. Specifically, advancements in governance indicators—such as political participation, accountability, and rule of law—help reduce the size of the underground economy and promote formal sector growth. On the other hand, economic and social instabilities, including financial market volatility, inflation, speculation, and societal insecurity, incentivize informal economic behavior, thereby undermining the formal structure of the economy.
To address these challenges, the study recommends implementing comprehensive governance and economic reforms. On the governance side, strategies should include corruption control, enhanced oversight, legal enforcement, public trust-building, and increased legitimacy of political institutions. On the economic front, stabilizing inflation, exchange rates, and market speculation—as well as improving social cohesion through targeted policies—can mitigate the growth of informal economic activities. A balanced, multi-pronged approach will foster sustainable economic development and enhance the resilience of Iran’s formal economy.
Economic and social instability, insecurity, and poor governance significantly increase transaction costs and investment risks while reducing incentives for productive economic activities. Institutional conditions and the political environment are fundamental factors influencing economic growth, as they affect the motivations of economic agents and thereby influence investment decisions, production organization, and overall economic performance. Macroeconomic instability, as an undesirable phenomenon, imposes both economic and social costs on society. Its persistence disturbs the national economic structure and diminishes household welfare by undermining financial security and increasing economic uncertainty.
Furthermore, effective economic policy-making and national development planning require a comprehensive understanding of the economy’s formal and informal sectors. The informal or underground economy includes activities outside the scope of official oversight, such as unregistered income, tax evasion, and operations beyond legal, social, and economic regulations. These activities are typically excluded from official GDP calculations but represent a significant share of economic production.
Modern definitions of economic growth encompass not only increases in GDP but also broader improvements in societal economic well-being. Notably, economic production occurs in both formal and informal sectors; thus, a thorough analysis of both is essential for developing effective and inclusive growth strategies. This study aims to evaluate the influence of political and economic risk, instability, and governance quality on both sectors of Iran’s economy over the period 1370–1401 (1991–2022). To achieve this, relevant indices were constructed to measure risk and instability in economic, financial, and social domains, as well as Iran’s governance performance, with the goal of identifying key determinants of formal sector strengthening and informal sector reduction.
Methodology
This research employs an endogenous growth model to investigate the factors influencing economic growth in Iran. Data on the underground economy are drawn from estimates produced using the Multiple Indicators and Multiple Causes (MIMIC) model. The methodological framework combines econometric techniques, notably Principal Component Analysis (PCA) and the Autoregressive Distributed Lag (ARDL) model.
PCA is applied to construct composite indices where multiple explanatory variables are involved, particularly in capturing instability and governance indicators. ARDL is used to examine relationships among variables, given the mixed order of integration in the time series data. This dual approach enables the study to assess the impact of governance, risk, and economic instability on both the formal and informal economic sectors.
Results and Discussion
The results show that within the economic growth function, property rights and political management exert a positive influence, while economic instability and international sanctions negatively affect Iran’s economic growth. Specifically, an increase of one unit in the political management index results in a 3.0033% increase in economic growth, whereas a one-unit rise in the economic instability index leads to a 0.1935% decline in growth.
In analyzing the informal (underground) economy, the study finds that increased risk and instability, unemployment, government size, tax revenues, and sanctions all contribute to the expansion of the informal sector. Conversely, improvements in political management reduce informal economic activities. Notably, the risk and instability index shows a high impact, with a coefficient of 3.99, signifying its strong correlation with the growth of Iran’s underground economy.
Conclusion
Improved political management enhances formal economic activity while suppressing informal sector expansion. Specifically, advancements in governance indicators—such as political participation, accountability, and rule of law—help reduce the size of the underground economy and promote formal sector growth. On the other hand, economic and social instabilities, including financial market volatility, inflation, speculation, and societal insecurity, incentivize informal economic behavior, thereby undermining the formal structure of the economy.
To address these challenges, the study recommends implementing comprehensive governance and economic reforms. On the governance side, strategies should include corruption control, enhanced oversight, legal enforcement, public trust-building, and increased legitimacy of political institutions. On the economic front, stabilizing inflation, exchange rates, and market speculation—as well as improving social cohesion through targeted policies—can mitigate the growth of informal economic activities. A balanced, multi-pronged approach will foster sustainable economic development and enhance the resilience of Iran’s formal economy.
Volume 0, Issue 0 (12-2024)
Abstract
Aim and Introduction
Asset bubbles arise when the prices of assets – such as real estate or stocks –significantly exceed their intrinsic value due to excessive speculation and investor euphoria. These bubbles are typically characterized by rapid price escalations that become disconnected from fundamental economic indicators, driven more by market psychology than by real economic value. Although asset bubbles may generate short-term economic benefits, they pose serious risks to financial stability, as their eventual collapse often results in sharp market corrections, financial crises, and broader economic downturns.
Monetary policy, primarily executed by central banks, plays a critical role in influencing macroeconomic conditions through liquidity management, credit accessibility, and interest rate adjustments. On the one hand, expansionary monetary policies—characterized by low interest rates and increased liquidity—can stimulate speculative investment and contribute to the formation of asset bubbles. On the other hand, central banks can use contractionary policies—such as raising interest rates or reducing liquidity—to dampen excessive market exuberance and promote financial stability.
The complex relationship between asset bubbles and monetary policy underscores a significant challenge for economists and policymakers, who must balance the goals of economic growth and financial stability. A nuanced understanding of this relationship is crucial for designing effective regulatory frameworks and policy interventions capable of mitigating harmful boom-and-bust cycles and fostering sustainable economic development.
Methodology
This study examines stock market bubbles and the influence of monetary policy in five D-8 countries, Iran, Turkey, Indonesia, Malaysia, and Egypt, over the period 2009–2023. Two key analytical approaches are employed:
Log-Periodic Power Law Singularity with Confidence Interval (LPPLS-CI) for detecting stock price bubbles, and
Asset bubbles arise when the prices of assets – such as real estate or stocks –significantly exceed their intrinsic value due to excessive speculation and investor euphoria. These bubbles are typically characterized by rapid price escalations that become disconnected from fundamental economic indicators, driven more by market psychology than by real economic value. Although asset bubbles may generate short-term economic benefits, they pose serious risks to financial stability, as their eventual collapse often results in sharp market corrections, financial crises, and broader economic downturns.
Monetary policy, primarily executed by central banks, plays a critical role in influencing macroeconomic conditions through liquidity management, credit accessibility, and interest rate adjustments. On the one hand, expansionary monetary policies—characterized by low interest rates and increased liquidity—can stimulate speculative investment and contribute to the formation of asset bubbles. On the other hand, central banks can use contractionary policies—such as raising interest rates or reducing liquidity—to dampen excessive market exuberance and promote financial stability.
The complex relationship between asset bubbles and monetary policy underscores a significant challenge for economists and policymakers, who must balance the goals of economic growth and financial stability. A nuanced understanding of this relationship is crucial for designing effective regulatory frameworks and policy interventions capable of mitigating harmful boom-and-bust cycles and fostering sustainable economic development.
Methodology
This study examines stock market bubbles and the influence of monetary policy in five D-8 countries, Iran, Turkey, Indonesia, Malaysia, and Egypt, over the period 2009–2023. Two key analytical approaches are employed:
Log-Periodic Power Law Singularity with Confidence Interval (LPPLS-CI) for detecting stock price bubbles, and
- Panel Vector Autoregression (P-VAR) for assessing the dynamic impact of monetary policy variables.
The LPPLS-CI model enhances traditional LPPLS techniques by incorporating confidence intervals, thus improving the accuracy and robustness of bubble detection. This model identifies unsustainable asset price growth and log-periodic oscillations—signals typically preceding bubble collapses. Its predictive capacity offers early warning signals that are valuable for financial market monitoring.
To evaluate the effects of monetary policy on these bubbles, the study employs the P-VAR model. This econometric framework captures interdependencies between multiple time-series variables—including stock prices, interest rates, inflation, and liquidity—by analyzing their lagged interactions. This comprehensive approach facilitates a dynamic understanding of how monetary policy decisions shape speculative trends and bubble formation. The effectiveness of this analysis depends on key methodological considerations, including appropriate model specification, lag length selection, and rigorous validation techniques.
Results and Discussion
The LPPLS-CI analysis confirms the presence of stock price bubbles across various time scales (short-, medium-, and long-term) in the selected countries throughout the 2009–2023 period. These bubbles were characterized by rapid price increases fueled by speculative behavior and optimistic market sentiment, ultimately followed by sharp corrections.
The P-VAR results demonstrated that high inflation, increased liquidity, and low interest rates were key contributors to bubble formation. These conditions encouraged capital inflows into financial markets, driving up stock prices beyond sustainable levels. However, as monetary policy conditions tightened or external economic shocks emerged, these bubbles burst, resulting in significant financial losses and increased market volatility.
The findings underscore the dual nature of monetary policy: while accommodative policies can promote growth and investment, they also risk inflating asset bubbles. The study emphasizes the need for balanced and proactive policy responses to prevent systemic instability. Regulatory oversight, timely monetary adjustments, and enhanced early warning mechanisms are crucial in minimizing the risks associated with speculative excesses.
Conclusion
Monetary policy in the examined D-8 countries significantly influences the formation and trajectory of stock market bubbles. Expansionary policies may exacerbate bubbles, leading to financial shocks, economic contractions, and capital flight when the bubbles burst. The study underscores the imperative for central banks in emerging markets to carefully manage accurate interest rates, control inflation, and stabilize liquidity to safeguard financial markets.
Key components of monetary policy affecting asset bubbles include:
To evaluate the effects of monetary policy on these bubbles, the study employs the P-VAR model. This econometric framework captures interdependencies between multiple time-series variables—including stock prices, interest rates, inflation, and liquidity—by analyzing their lagged interactions. This comprehensive approach facilitates a dynamic understanding of how monetary policy decisions shape speculative trends and bubble formation. The effectiveness of this analysis depends on key methodological considerations, including appropriate model specification, lag length selection, and rigorous validation techniques.
Results and Discussion
The LPPLS-CI analysis confirms the presence of stock price bubbles across various time scales (short-, medium-, and long-term) in the selected countries throughout the 2009–2023 period. These bubbles were characterized by rapid price increases fueled by speculative behavior and optimistic market sentiment, ultimately followed by sharp corrections.
The P-VAR results demonstrated that high inflation, increased liquidity, and low interest rates were key contributors to bubble formation. These conditions encouraged capital inflows into financial markets, driving up stock prices beyond sustainable levels. However, as monetary policy conditions tightened or external economic shocks emerged, these bubbles burst, resulting in significant financial losses and increased market volatility.
The findings underscore the dual nature of monetary policy: while accommodative policies can promote growth and investment, they also risk inflating asset bubbles. The study emphasizes the need for balanced and proactive policy responses to prevent systemic instability. Regulatory oversight, timely monetary adjustments, and enhanced early warning mechanisms are crucial in minimizing the risks associated with speculative excesses.
Conclusion
Monetary policy in the examined D-8 countries significantly influences the formation and trajectory of stock market bubbles. Expansionary policies may exacerbate bubbles, leading to financial shocks, economic contractions, and capital flight when the bubbles burst. The study underscores the imperative for central banks in emerging markets to carefully manage accurate interest rates, control inflation, and stabilize liquidity to safeguard financial markets.
Key components of monetary policy affecting asset bubbles include:
- Interest Rates: Low rates can stimulate borrowing and speculation, while higher rates can curb overheating but may suppress growth.
- Quantitative Easing (QE): Although QE enhances liquidity and asset values, prolonged implementation can fuel speculative bubbles.
To prevent crises, Policy recommendations include:
- Regulatory Oversight: Strengthen financial regulations to enhance transparency and mitigate systemic risks.
- Macroprudential Tools: Implement counter-cyclical capital buffers and risk-weighted asset requirements.
- Monetary Policy Adjustments: Implement forward guidance and timely rate changes to manage expectations.
- Early Warning Systems: Monitor key financial indicators to detect signs of market overheating.
- Investment Diversification: Encourage asset diversification to reduce systemic exposure.
Implementing these strategies can help minimize the occurrence and adverse consequences of asset bubbles, contributing to more resilient financial systems and sustainable economic growth in the D-8 member countries.
Omidvar Farhadian, Seyed Mojtaba Fallahi, Nasrollah Mahboobi Soofiani,
Volume 1, Issue 1 (3-2013)
Volume 1, Issue 1 (3-2013)
Abstract
In order to determine effects of chicken and cattle manures in culture of Chlorococcum, an experiment was designed in six treatments including; 0.1, 0.4, 0.8 g/l of chicken manure and 0.1, 0.4, 0.8 g/l of cattle manure as completely randomize design with three replicates for 28 days. Results showed that the mean maximum density (87.1 × 105 cell/ml), specific growth rate (0.054 day-1), algal dry biomass (0.644 g/l), and chlorophyll a (9.42 mg/l) were obtained with 0.8 mg/l chicken manure. In order to compare performance of these manures with other culture media, second experiment with five treatments including; BBM (control) (Bold’s Basal Medium), BBM + soil extract, 0.8 g/l chicken manure, 0.8 g/l cattle manure and mixture of all treatment (BBM, BBM + soil extract, chicken manure and cattle manure) was designed as completely randomize design with three replicates for 15 days. Comparative results showed that BBM + soil extract had highest algal density (11.6 x 106 cells/ml), highest algal dry biomass (0.81 mg/ml), maximum SGR (0.13 /day), highest chlorophyll a (10.15 mg/l) and minimum doubling time (4.97 days). In conclusion, performance of BBM + soil extract was better in terms of biomass and growth parameters of Chlorococcum.
Yousef Iri, Hosseinali Khoshbavar Rostami, Reza Akrami,
Volume 1, Issue 1 (3-2013)
Volume 1, Issue 1 (3-2013)
Abstract
In this study, the effect of fructooligosaccharide as a prebiotic on the growth and density of lactobacillus in intestine of stellate (Acipenser stellatus) has been investigated. To do this, 90 individuals of stellate fingerlings (ten in each replications) were prepared with an average weight of 30.16 ± 0.14 gr from International Sturgeon Research Institute. This study was carried out in a completely randomized design with three replications in fiberglass tanks with 2000 liters volume. They were fed with feed containing 0, 1 and 2 percents of fructooligosaccharide (Raftilos P95, Sigma Company). Results indicated that feed with one percent fructooligosaccharide had a significant effect (P < 0.05) on weight gain, SGR, FCR, FE, PER and HI. The number of colonies regarding to lactobacillus showed a significant increase compared to the control (in one percent fructooligosaccharide). Results indicated that fructooligosaccharide as a prebiotic (in level of one percent in feed) caused good growth capabilities and feed efficiency through increasing the density of lactobacillus in intestine.
Volume 1, Issue 2 (6-2012)
Abstract
The life table parameters of Schizaphis graminum (Rondani) (Hemiptera: Aphididae) on four commercial cultivars of wheat (Kohdasht, Pastor, Tajan and Zagros) were determined in laboratory conditions. Fertility life table were constructed using age-specific survivorship (lx) and age-specific fecundity (mx) and subsequently analyzed using jackknife method and ANOVA. There were significant differences among pre-imaginal period and adult longevity of the aphid on the four wheat cultivars. The highest mortality occurred at first nymphal instar on all of wheat cultivars tested. The life expectancy (ex) of one-day-old adults was estimated to be 23.5, 24.6, 30.36 and 26.83 days on Kohdasht, Pastor, Tajan and Zagros, respectively. The gross reproductive rate was significantly higher on Tajan (102.39 ± 1.42 females/female/generation) compared with other three cultivars. The net reproductive rate (R0) significantly differed on different wheat cultivars examined. The R0-value was highest on Tajan (82.21 ± 1.21) and lowest on Zagros (38.23 ± 0.63 females/female/generation). The highest and lowest values of the intrinsic rate of increase (rm) were 0.276 ± 0.002 (on Pastor) and 0.222 ± 0.001 day-1 (on Zagros), respectively. The finite rate of increase (l) differed significantly among four wheat cultivars, ranging from 1.25 ± 0.00 (on Zagros) to 1.32 ± 0.00 days-1 (on Pastor). Doubling time ranged from 2.51 ± 0.02 (on Pastor) to 3.12 ± 0.02 days (on Zagros). The longest mean generation time (T) of the aphid was obtained on Tajan cultivar. The results showed that the Zagros cultivar had the highest antibiotic effect on population growth of S. graminum.
Volume 1, Issue 2 (6-2013)
Abstract
Logistic regression (LR) was used to model urban growth between the years 1987 and 2001 in Gorgan city, north east of Iran. Three groups of variables including economic-social, land use and biophysical variables were used in the modeling practice. Using covariance of the independent variables, distance to administrative and sporting centers plus distance to cities were removed. ROC (Relative Operating Characteristic) value for LR was 0.87 that confirmed success of the modeling method. Using maps of urban growth probability predicted by the LR model, urban distribution patterns for the years 2010, 2020, 2030, 2040 and 2050 were created. Land use maps for the years 2001-2050 were created using urban probability pattern maps and the base land use map of the year 1987. We used landscape metrics at class and landscape levels to compare the urban growth effects on other land use types present in the area. The comparison showed that urban development influences agriculture and pasture land use types more than other land uses. Also, we found that the landscape in the study area has undergone fragmentation and will become more fragmented and heterogeneous over time. Urban growth creates higher urban patchiness and increases the number of pasture and agricultural patches. The information thus obtained is helpful in more effective management of the area.
Volume 1, Issue 2 (7-2014)
Abstract
Background: Henoch-Schönlein purpura (HSP) is an lgA mediated small vessel systemic vasculitis disease in children. The etiology and pathogenesis of HSP disease remain unknown. However, environmental and genetic risk factors could play important roles in susceptibility to HSP disease. In this study we investigated the association of 5՛-untranslated region polymorphism (-634G/C) of VEGF gene with HSP among Iranian Azeri Turkish population. Methods: Thirty unrelated Iranian Azeri Turkish children with HSP and fifty healthy unrelated subjects without HSP and other inflammatory diseases were enrolled in this population. -634G/C polymorphism of VEGF gene was genotyped by polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) technique. Results: The distribution of CC genotype in VEGF -634G/C polymorphism statistically showed a significant difference in HSP patients in compare to that of control group (P= 0.009). Conclusions: The CC genotype of VEGF -634G/C polymorphism could be associated with susceptibility to HSP disease in Iranian Azeri Turkish ethnic group.
Volume 1, Issue 3 (9-2013)
Abstract
Fish larvae have a high requirement of amino acid (AA) for energy production and growth. This study was aimed to increase knowledge of AA profile during feral carp larval ontogeny and estimate larval AA requirements. Larvae were collected randomly at 1, 3, 7, 11, 15, 19, 26 and 33 days post hatch for growth and AA analysis. The composition of total AA changed significantly during ontogeny. The essential AA profile of marine carp showed low correlation with rotifers (R2=0.22). High correlation was found between dry food and early larval ages (R2≥0.7) but was lower in late stage (R2≥0.37). At day 7, when larvae were fed on rotifers, methionine seemed to be the limiting AA and when larvae were fed dry food at day 11, 15, 19, 26 and 33, arginine seemed to be the limiting AA. Larval indispensible AA profile can be used as index of the IAA requirements of carp larvae. Supplementation of larval diet used with limiting AA is one way for compensating the deficient amino acid.
Volume 1, Issue 4 (12-2013)
Abstract
An 84-day feeding trial was carried out onfingerling (4.44 ± 0.06 g) rainbow trout (Oncorhynchusmykiss, Walbaum, 1792) to evaluate the effect of dietary supplementation with a commercial prebiotic GroBiotic®-A (G-A) on the growth, feed efficiency, haematology and immunlogical parameters. Ttreatments containing various inclusions of G-A (0 %, 0.5 %, 1.0 %, 1.5 %, 2.0 %, 2.5 %, and 3.0 %) were added to a commercial fish dietand were fed twice daily at 2-6 % of body weight. The highest weight gain (WG), specific growth rate (SGR) and average daily gain (ADG) were obtained in fish fed the diet containing 2.5 % G-A followed by 3.0 % inclusion (P<0.05). The highest feed efficiency (FE), protein efficiency ratio (PER) and net protein utilization (NPU) were also recorded in the 2.5 % G-A inclusion (P<0.05). Survival was significantly higher (P<0.05) in fish fed with 2 % and 2.5 % G-Asupplement (P<0.05). Although higher Hb, haematocrit, RBC, WBC, MCH, MCHC, MCV, lymphocytes, and neutrophils were observed at all G-A supplemented diets, the differences among themwerenot significant (P>0.05). On the other hand,significantly higher differencee (P<0.05) in lysozyme and immunoglobulin (IgM) concentrations wereobserved in 2.5% G-A inclusion. The results of this study indicated that 2.5 % G-A inclusionhad a better performance on growth and haematoimmunological parameters in rainbow trout fingerling.
Masoumeh Pourafrasiabi, Zohreh Ramezanpour, Javid Imanpour Namin, Marjan Sadeghi Rad,
Volume 2, Issue 1 (6-2013)
Volume 2, Issue 1 (6-2013)
Abstract
Cell concentrations and growth rate of Dunaliella salina Teodoresco in light intensities e. g. 50 and 150 µmol. photons.m-2.s-1 and temperatures 25 ± 0.5 and 31 ± 0.5 oC (Mean ± SD) were studied. The algae was isolated from the Urumieh Lake and cultured in various treatments (n=12). Algae cells were counted regularly using Thoma counting chamber in 3 replicates on daily basis. The curve of changes in population was plotted. The specific growth rate (SGR; d-1) was calculated and compared within treatments by means of two ways ANOVA Analysis. The highest cell concentration (Mean ± SD) 4.8 ± 0.6 × 10 6 cell.ml-1 was observed in light intensity of 150 µmol. photons.m-2.s-1 and temperature 25 ± 0.5 oC. The minimum cell concentration (2.8 ± 0.3 × 10 6 cell.ml-1) was observed in light intensity of 50 µmol. photons.m-2.s-1 and temperature 31 ± 0.5 oC. Specific growth rate showed significant differences in various treatments (P
, Seyed Hossein Hoseinifar, , , , ,
Volume 2, Issue 1 (6-2013)
Volume 2, Issue 1 (6-2013)
Abstract
The effects of various levels of the commercial dietary supplement, Hoplite containing glucan, on growth performance, body composition and intestinal microbiota in white fish, Rutilus frisii kutum fry were investigated. 25 white fish fry (mean weight=1 ± 0.15 g) were stocked in each experimental tank (100 L). The fry were fed experimental diets supplemented with 0, 0.5, 1 and 2% Hoplite to apparent satiation, 3 times a day for 60 days. Biometry was performed every two weeks. Mean dissolved oxygen concentration, pH and water temperature recorded during the experiment were 5.0±0.1 mg/l, 7.8±0.2 and 24.4±0.11 ºC, respectively. At the end of the trial period, growth parameters, body composition and intestinal microbiota were studied. Results indicate that fry fed 0.5 and 1% glucan exhibited highest weight gain (WG), specific growth rate (SGR) and final body weight (FBW) which were significantly different (P
Mir Hamed Sayed Hassan, , , ,
Volume 2, Issue 1 (6-2013)
Volume 2, Issue 1 (6-2013)
Abstract
A 4 × 4 factorial design was conducted to quantify the optimumrncarbohydrate ⁄ lipid ratio to minimize the dietary protein level in growingrnbeluga, Huso huso (initial weight 891.9 ± 33.4 g, mean ± SD). Fish were fedrnwith sixteen experimental diets formulated to contain four protein levels (35,rn40, 45 and 50%) and four dietary carbohydrate ⁄ lipid ratios of 0.8, 1.1, 1.4,rnand 1.7 for 108 days. At the end of trial, there were no significant differencesrnin growth parameters among fish fed with 35, 40 and 45% protein levels. Nornsignificant difference in growth parameters and feed efficiency (FE) wasrnalso observed when dietary carbohydrate ⁄ lipid ratios decreased from 1.7 torn1.1 within the same energy level (P > 0.05). The highest carcass proteinrncontent was observed in fish fed 0.8 and 1.4 carbohydrate to lipid ratio (P
Volume 2, Issue 1 (4-2012)
Abstract
Nowadays the urban growth pattern of cities is growing dramatically; and current suburbs of cities will form the inseparable components of the main city in the near future. In all cities of world vertical and horizontal urban growth have been one of the most important factors noticed by urban managers and planners. Urban growth is a spatial - structural process that refers to the increased importance of towns and cities as a concentration of population within a particular economy and society. Increase in urban points as quantitative issue shows itself in the forms of increase in population of cities and development in built up area scale. The unorganized physical growth of cities is due to their physical discrete and separate development which is mostly in form of forming individual and separate parts. Hence, analysis of the current physical status, and prediction of the future development of cities due to its influence on the politics and management of city and human resources, is of great importance. Regarding the numerous factors affecting the inharmonic physical urban growth, the present article has investigated the rate of urban horizontal growth from two aspects of area and direction.The research method in this article is analytical- comparative and with respect to the evolution of the physical- spatial pattern of Tabriz metropolitan in the 1956-2006 period. Shannon’s Entropy model is utilized for evaluation of the rate of the urban horizontal growth diversity. In order to use this model first we draw the complete and detailed plan of Tabriz city in concentric buffers with width of one kilometer between years 1956-2006 using Auto Cad software and the physical gravity center of Tabriz city which is the same center of cultural- historical part has been considered as basis for buffering modulation, and Sectoral- Geographical model is used for specification of urban growth directions. . In the next phase center of city gravity has drawn in the form of circle with determined diameter and the center of this circle was considered as basis for modulation of geographical sectors and sectoral buffering in 12 geographic directions. The attained results of analyzing the research findings has shown that the sprawl growth and diversity of inharmonic development has occurred in Tabriz metropolitan. The maximum of this rate has happened on the year 1996 and directions of horizontal urban growth are completely coincided on the margins of main connection corridors of city.