Gravity Approach Research Articles

Global Value Chains, Trade Shocks and Jobs: An Application to Brexit

This paper develops a gravity model with sector-level input-output linkages in production. In contrast to a traditional gravity approach, which relies on direct gross exports between bilateral trade partners, our model additionally includes (1) domestic and global value chain linkages between goods and services sectors, (2) bilateral tariffs that affect direct production for a final destination as well as indirect production (shipped via third countries) to a final destination and (3) value added rather than gross production. Including input-output linkages implies that domestic production of intermediates can serve as inputs in foreign products and subsequently be exported indirectly to a final destination. Our input-output model can be taken to the sectoral World Input Output Database (WIOD) and can be used to evaluate trade policy shocks. While our framework is entirely general, we use it to predict the impact of the UK's withdrawal from the European Union (Brexit) in terms of value added production and employment for every individual EU country involved. We find that Brexit hits the UK relatively harder than the EU-27. In contrast to other studies, we find EU-27 losses from Brexit to be substantially higher than hitherto believed.

A Non-Polynomial Gravity Formulation for Loop Quantum Cosmology Bounce

Recently the so-called mimetic gravity approach has been used to obtain corrections to the Friedmann equation of General Relativity similar to the ones present in loop quantum cosmology. In this paper, we propose an alternative way to derive this modified Friedmann equation via the so-called non-polynomial gravity approach, which consists of adding geometric non-polynomial higher derivative terms to Hilbert–Einstein action, which are nonetheless polynomials and lead to a second-order differential equation in Friedmann–Lemaître–Robertson–Walker space-times. Our explicit action turns out to be a realization of the Helling proposal of effective action with an infinite number of terms. The model is also investigated in the presence of a non-vanishing cosmological constant, and a new exact bounce solution is found and studied.

Post-Brexit Trade Survival: Looking Beyond the European Union

The UK is struggling to maintain a powerful global position against a backdrop of the British public having a longstanding difficulty in appreciating the benefits of EU membership. The success of the ‘leave’ EU campaign has created huge uncertainty over future ties with the EU. The Trans-Atlantic Trade and Investment Partnership (TTIP) offers an opportunity to be part of one of the mega-regional blocks. On the other hand, the UK may attempt to compensate for losses in the EU markets by signing deals with the US or Commonwealth countries. This paper adopts a structural gravity approach to evaluate five scenarios, based on different assumptions regarding Brexit, TTIP and various free trade deals. We estimate the highest UK welfare losses, approximately 3.1%, if the TTIP comes into force alongside the UK withdrawal from the EU. Negotiating free trade agreements with the US or the largest Commonwealth countries cannot compensate for these losses.

INVESTIGATING INDONESIA’S ENERGY TRADE EFFICIENCY: GRAVITY AND MALMQUIST INDEX APPROACH

This study applies Gravity and Malmquist index approach to investigate energy trade efficiency between Indonesia and East Asia Countries (i.e. Japan, South Korea, and China). Gravity model is employed to identify the inputs that will be used in computing the energy trade efficiency; meanwhile, Malmquist index approach to identify the energy trade efficiency by taking data from 2000-2015. One of the findings shows that the considered inputs that will be utilised are the population of importer countries, Indonesian population, relative distance, and ratio of added value of industry sector towards GDP. In addition, the energy trade efficiency between Indonesia and East Asia countries from 2000 to 2015 was composed by technical change or technical/potential change. China averagely had the highest efficiency and showed improvement like South Korea did. Japan showed, on the other hand, deterioration

Impact of China-Pakistan Economic Corridor (CPEC) on Pakistan's trade: Empirical Evidence from Gravity Model

Purpose: The China-Pakistan Economic Corridor(CPEC) is an enormous project for both economies. There are much potential remunerations for concerning frugalities in trade and industries of both countries. The study was specifically designed to examine the influence of CPEC on fruits export of Pakistan. The bilateral or regional trade was examined through Gravity approach. Data was taken from 2013 to 2015. Since distance plays a vital role in trade, the outcomes of gravity model are estimated with ordinary least square method. Pakistan China Economic Corridor is a mega project for both economies. It will make Pakistan and China, the major economic players in the region and further enhance economic conditions of both countries. Some of the basic determinations of Pak-China economic corridor are to boost business opportunities, efficient transport routes and expanding regional trade. The export target of Pakistan was $ US 20 billion in 2013-2015. As of April 2015, Pakistan exports stand at $ US 6,178 billion. Pakistan’s exports to Asia was amounted to $ US 1,649 billion which was 42 percent of its overall exports and the share of fruit and nuts markets in Pakistan's export was $ US 1,017 billion. The paper analyses the CPEC's impact on exports especially exports from fruit market of Pakistan using Gravity Approach for the evaluation of this bilateral trade. The results show that CPEC reduces the distance and it will be more beneficial for perishable goods trade like fruits.

The failure processes analysis of rock slope using numerical modelling techniques

Abstract The slope failure process includes crack initiation, propagation and coalescence during the formation of a slip surface (small deformation stage) and block movement, rotation and fragmentation during the sliding process (large deformation stage). Neither the finite element method (FEM) nor the discontinuous deformation analysis method (DDA) can solve such problems satisfactorily due to the complex mechanical behaviour of slope failure. To study the entire process of slope failure, we develop here a model that combines the FEM and DDA approaches. The main concept of this approach is to first apply FEM to model crack growth behaviour and then automatically switch to the DDA module to model the post-failure process when the slip surface forms. The efficiency and simplicity of this approach lies in keeping the FEM and DDA algorithms separate and solving each equation individually. The heterogeneous nature of the slope material at the mesoscopic level is considered by assuming that the mechanical properties of individual elements follow a Weibull statistical distribution. The slope models are progressively destabilized by the critical gravity approach, and both the failure onset and the slope collapse process are analysed. Our modelling reveals that shear cracks first initiate at the toe of slope and subsequently promote the propagation of tensile fractures due to the stress accumulation at the shear crack tips. Throughout the entire failure process, failure in tension occurs at a higher rate than shear failure and plays a dominant role in the formation of the slip surface. The effects of slope angle and pre-formed cracks on the post-failure process are studied using the proposed method. This study demonstrates that the modelling approach outlined herein is able to tackle the fundamental problems of rock slope failure and offers a better understanding of the slope failure mechanisms at both the macroscopic and microscopic levels.

Regional Inter-Dependence and Vietnam-Korea Economic Relationship

The world is changing, and more critical changes have been witnessed in East Asia with the emergence of China, which has shaped the economic and geopolitics patterns and inter-dependence among countries. This book aims at investigating the trade and investment dependence of Vietnam on Korea given the increasing economic integration and the more unstable geopolitics in the region. It makes clearer the concept of trade bilateral dependence with the presence of the third parties. By using spatial gravity approach, it also points out the importance of geopolitics factor as well as FTAs in determining the trade and investment flows. The role of some major regional economies should not be neglected. Either the improvement in their institution or their economic slowdown significantly influences the trade and investment relation of Korea and Vietnam.

Premetric equivalent of general relativity: Teleparallelism

In general relativity (GR), the metric tensor of spacetime is essential since it represents the gravitational potential. In other gauge theories (such as electromagnetism), the so-called premetric approach succeeds in separating the purely topological field equation from the metric-dependent constitutive law. We show here that GR allows for a premetric formulation, too. For this purpose, we apply the teleparallel approach of gravity, which represents GR as a gauge theory based on the translation group. We formulate the metric-free topological field equation and a general linear constitutive law between the basic field variables. The requirement of local Lorentz invariance turns the model into a full equivalent of GR. Our approach opens a way for a natural extension of GR to diverse geometrical structures of spacetime.

Correction of Cardy–Verlinde formula for Fermions and Bosons with modified dispersion relation

Cardy–Verlinde formula links the entropy of conformal symmetry field to the total energy and its Casimir energy in a D-dimensional space. To correct black hole thermodynamics, modified dispersion relation can be used which is proposed as a general feature of quantum gravity approaches. In this paper, the thermodynamics of Schwarzschild four-dimensional black hole is corrected using the modified dispersion relation for Fermions and Bosons. Finally, using modified thermodynamics of Schwarzschild four-dimensional black hole, generalization for Cardy–Verlinde formula is obtained.

India’s Trade Potential and Free Trade Agreements: A Stochastic Frontier Gravity Approach

This paper analyses the role of Free Trade Agreements in determining export and import efficiency levels in India using stochastic frontier version of gravity model. We estimate the impact of selected FTAs of India (its bilateral FTAs, FTA with ASEAN and South Asian FTA) and regulatory quality on the efficiency of exports and imports over the period of 2000–2014. The results indicate that India’s bilateral FTAs and its FTA with the ASEAN group help in improving the export and import efficiency respectively. However, the South Asian Free Trade Agreement is statistically insignificant for India’s export and import efficiency. The results also highlight importance of trading partners’ regulatory quality for enhancing the India’s trade efficiency and note that the impacts of regulatory quality are non-monotonic.

Emergent Hyperbolic Network Geometry

A large variety of interacting complex systems are characterized by interactions occurring between more than two nodes. These systems are described by simplicial complexes. Simplicial complexes are formed by simplices (nodes, links, triangles, tetrahedra etc.) that have a natural geometric interpretation. As such simplicial complexes are widely used in quantum gravity approaches that involve a discretization of spacetime. Here, by extending our knowledge of growing complex networks to growing simplicial complexes we investigate the nature of the emergent geometry of complex networks and explore whether this geometry is hyperbolic. Specifically we show that an hyperbolic network geometry emerges spontaneously from models of growing simplicial complexes that are purely combinatorial. The statistical and geometrical properties of the growing simplicial complexes strongly depend on their dimensionality and display the major universal properties of real complex networks (scale-free degree distribution, small-world and communities) at the same time. Interestingly, when the network dynamics includes an heterogeneous fitness of the faces, the growing simplicial complex can undergo phase transitions that are reflected by relevant changes in the network geometry.

Line-based calibration of a micro-vision motion measurement system

We propose a flexible and practical line-based method for calibrating a micro-vision motion measurement system by using a resolution target, considering the lens distortion. First, centerlines of the stripes in the image of resolution target are extracted with an improved center gravity approach. Then distortion coefficients are obtained through the nonlinear optimization, utilizing straightness of the lines. Finally, these lines are corrected and used for estimating parameters of the system. Two experiments are conducted to validate the effectiveness of the proposed method. The results demonstrate that our method is effective and practical for calibrating the micro-vision measurement system.

Separation of Fine Al2O3 Inclusion from Liquid Steel with Super Gravity

An innovative approach of super gravity was proposed to separate fine Al2O3 inclusions from liquid steel in this study. To investigate the removal behaviors of inclusions, the effects of different gravity coefficients and time on separating the inclusions were studied. The results show that a large amount of Al2O3 inclusions gathered at the top of the sample obtained by super gravity, whereas there were almost no inclusions appearing at the bottom. The volume fraction and number density of inclusions presented a gradient distribution along the direction of the super gravity, which became steeper with increasing gravity coefficient and separating time. As a result of the collision between inclusions, a large amount of inclusions aggregated and grew during the moving process, which further decreased the removal time. The experimental required removal time of inclusions is close to the theoretical values calculated by Stokes law under gravity coefficient G ≤ 80, t ≤ 15 minutes, and the small deviation may be because the inclusion particles are not truly spherical. Under the condition of gravity coefficient G = 80, t = 15 minutes, the total oxygen content at the bottom of the sample (position of 5 cm) is only 8.4 ppm, and the removal rate is up to 95.6 pct compared with that under normal gravity.

On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars

The performance of adaptive optics systems is partially dependant on the algorithms used within the real-time control system to compute wavefront slope measurements. We demonstrate use of a matched filter algorithm for the processing of elongated laser guide star (LGS) Shack-Hartmann images, using the CANARY adaptive optics instrument on the 4.2m William Herschel Telescope and the European Southern Observatory Wendelstein LGS Unit placed 40m away. This algorithm has been selected for use with the forthcoming Thirty Meter Telescope, but until now had not been demonstrated on-sky. From the results of a first observing run, we show that the use of matched filtering improves our adaptive optics system performance, with increases in on-sky H-band Strehl measured up to about a factor of 1.1 with respect to a conventional centre of gravity approach. We describe the algorithm used, and the methods that we implemented to enable on-sky demonstration.

Euro introduction and the behaviour of Italian exporting firms

The paper examines the effects on Italian manufacturing firms of trade cost reduction due to the introduction of the euro over the period 1996–2004. Using the gravity approach and a difference-in-differences (DID) empirical strategy, the results reveal the importance of properly controlling for heterogeneity. The euro’s effect on the performance of exporting firms is estimated not to be statistically significant when considering eurozone destination markets as a whole. Nevertheless, an increase of flows to ‘peripheral’ eurozone countries is channelled through the intensive margin. When heterogeneity in terms of firm-level labour-productivity is controlled for, a competition effect emerges in core markets, with a reduction of the intensive margin for less productive firms and an increase for the more productive ones. Finally, more financial contrained firms decreased the extensive margin in core markets, regardless of their productivity level.

Trip generation and distribution modelling in Budapest

The last decades brought social and economic changes. Together with the technical developments and more conscious mobility planning and travelling of people called for a new transport model for Budapest. Additionally, for the sake of coherent project appraisal a strategic, macro level decision supporting and project appraisal tool was developed based on open and transparent methods to give more insight for users and accommodate the best practice for all professionals. In order to reflect person-specific influence factors of the travel behaviour, based on the latest observations and house-hold surveys, 20 population segments and 14 trip purposes were identified. The numerous demand strata led to pretty realistic trip generation figures. The destination choice behaviour model is tour based instead of the most common home-based trip-pair practice. Trip distribution functions implies a gravity approach by logit functions applying general utility. The tour based model works with non-symmetric generation – attraction matrices and the distinction between home zone and non-home zone made the use of area specific variables (e.g. parking fee for non-residents) possible. The aim of the paper is to describe the model structure but also explaining what observations were made, what were the key finding in terms of transportation characteristics and what decisions led to the applied model components. The fitting to the observed volumes and the sensitivity and validity of the model is fairly good, thus against the preceding model set-ups the direct use of observed matrices was not necessary.

Productivity differences and inter-state migration in the U.S.: A multilateral gravity approach

In this paper, we study the quantitative role of productivity differences in explaining migration in presence of multiple destination choices. We construct a dynamic general equilibrium model with multi-region, multi-sector set-up where labor is a mobile input, which adjusts to regional and sectoral productivity shocks, resulting in migration across regions. The proposed model generates a migration network where the flow of migrants between any two regions follows a gravity equation. We calibrate the model to the U.S. data and we find that variation in industrial and regional total factor productivity shocks explains about 63% of the interstate migration in the U.S. Finally, we perform comparative statics to estimate the effects of long-run structural changes on migration. We find that capital intensity of the production process and the demand for services over manufactured goods negatively impact aggregate level of migration whereas asymmetries in trade patterns do not appear to have substantial effects.

Schwarzschild instanton in emergent gravity

In the bottom-up approach of emergent gravity, we attempt to find symplectic gauge fields emerging from Euclidean Schwarzschild instanton, which is studied as electromagnetism defined on the symplectic space [Formula: see text]. Geometrical engineering with the emergent metric sets up the Seiberg–Witten map between commutative and non-commutative gauge fields, preparing the ground for the evaluation of topological invariants in terms of the underlying gauge theory quantities.

Determinants of fdi inflows: the case of russian regions

This paper empirically analyses the determinants of foreign direct investment inflows into the Russian regions. This problem has become highly relevant for the necessary modernization of the Russian economy after the recent economic slowdown and sharp decrease in budget revenues. The authors model foreign direct investment flows with the use of the gravity approach according to which investment flows are positively correlated with the size of the investor’s country as well as the size of the recipient region and are negatively correlated with the distance between investor and recipient. The empirical analysis is based on a constructed database consisting of the foreign direct investment flows from 179 investor countries into 78 Russian regions for the period 2006–2013. The authors apply the Poisson Pseudo Maximum Likelihood method and identify the following factors determining foreign direct investment inflows into the Russian economy: the gross domestic product of the investor’s country, the gross domestic product per capita in the recipient region, the distance from the investor to Moscow, the openness of the region, the economic situation in the region, the innovative capacity of the region and the foreign direct investment of the previous period. Interestingly, the distance from the recipient region to Moscow matters for the regions in the western part of Russia (relatively close to Moscow) but is not significant for the regions in the eastern part (remote regions).

The dynamical environment of asteroid 21 Lutetia according to different internal models

One of the most accurate models currently used to represent the gravity field of irregular bodies is the polyhedral approach. In this model, the mass of the body is assumed to be homogeneous, which may not be true for a real object. The main goal of the present paper is to study the dynamical effects induced by three different internal structures (uniform, three- and four-layers) of asteroid (21) Lutetia, an object that recent results from space probe suggest being at least partially differentiated. The Mascon gravity approach used in the present work, consists of dividing each tetrahedron into eight parts to calculate the gravitational field around the asteroid. The zero-velocity curves show that the greatest displacement of the equilibrium points occurs in the position of the E4 point for the four-layers structure and the smallest one occurs in the position of the E3 point for the three-layers structure. Moreover, stability against impact shows that the planar limit gets slightly closer to the body with the four-layered structure. We then investigated the stability of orbital motion in the equatorial plane of (21) Lutetia and propose numerical stability criteria to map the region of stable motions. Layered structures could stabilize orbits that were unstable in the homogeneous model.