Role of extended gravity theory in matter bounce dynamics

In this work, we have studied some bouncing cosmologies in the frame work of $f(R,T)$ gravity. The bouncing scenario has been formulated to avoid the big bang singularity. The physical and geometrical parameters are investigated. The effect of the extended gravity theory on the dynamical parameters of the model is investigated. It is found that, the $f(R,T)$ gravity parameter affects the cosmic dynamics substantially. We have also, tested the model through the calculation of the cosmographic coefficients and the $Om(z)$ parameter. A scalar field reconstruction of the bouncing scenario is also carried out. The stability of the model are tested under linear, homogeneous and isotropic perturbations.

Potential of Kazakhstan’s grain export trade

ABSTRACT: Kazakhstan is located in the hinterland of Central Asia. Its virtuous geographical advantages and huge grain production potential make it one of the most important grain exporters in the world. The research on the problem of the grain trade in Kazakhstan is of great significance for food security. This study measured its international competitiveness using the International Market Share Index, the Revealed Comparative Advantage Index, Trade competitiveness index and calculated the international competitiveness and analyzed the influencing factors of grain export by constructing an extended gravity model and measured its export potential. Results showed that Kazakhstan has a low share of the international grain market; however, wheat, barley, and buckwheat have strong export advantages; the level of economic development and economic distance has significantly promoted the scale of grain exports. While geographical distance, the difference in GDP per capita, and the fact whether trading partner countries have joined the Eurasian Economic Union have caused obstacles to grain exports. Kazakhstan’s export potential to 6 countries including Russia, Kyrgyzstan and China shows an upward” trend, its export potential to 6 countries including Tajikistan and Ukraine showing a “stable” trend, and its export to 9 countries included Poland and Germany. The potential showed a “declining” trend.

Determinants, efficiency and potential of agri-food exports from Nigeria to the EU: Evidence from the stochastic frontier gravity model

This study uses an extended gravity model to examine the determinants, efficiency and potential of agri-food exports from Nigeria to the EU for the 1995–2019 period. It uses a stochastic frontier analysis (SFA) to estimate the extended gravity model. The results show that the economic size (GDP) of Nigeria and the EU countries, as well as bilateral distance, positively determine agri-food exports from Nigeria to the EU. Also, the results show that Nigeria's agri-food exports to the EU are negatively determined by the income (per capita GDP) of Nigeria and its EU trading countries, bilateral exchange rate and EU new member states (NMS). The results further show that Nigeria scores relatively low in terms of the efficiency of its agri-food exports to the EU countries. On a final note, the study shows that Nigeria's agri-food exports with the EU have a relatively large potential that has not been exploited. We document policy recommendations in this study.

Dynamics of a Homogeneous and Isotropic Space in Pure Cubic f(R) Gravity

The possible ways of dynamics of a homogeneous and isotropic space described by the Friedmann–Lemaitre–Robertson–Walker metric in the framework of cubic in the Ricci scalar f(R) gravity in the absence of matter are considered. This paper points towards an effective method for limiting the parameters of extended gravity models. A method for f(R)-gravity models, based on the metric dynamics of various model parameters in the simplest example is proposed. The influence of the parameters and initial conditions on further dynamics are discussed. The parameters can be limited by (i) slow growth of space, (ii) instability and (iii) divergence with the inflationary scenario.

Emerging Countries as the Main Destinations for European Value-Added Exports

Nowadays, production chains may cross the borders of several continents in search of greater profitability. In order to more accurately calculate countries’ foreign demand, value-added exports should be used rather than gross exports. This study takes the value-added exports calculated for European Union countries and uses extended gravity models to analyze the determinants of this trade, differentiating between countries according to the main destinations for their value-added, USA, Russia and China. The results reveal certain changes according to the economic period analyzed and the destination of the goods, with respect to key variables such as the wealth of the exporting country, the level of logistics performance and distance. In 2014, China registered an improvement in its position compared to Russia.