Unilateral Restrictions Research Articles

Pandemic bordering: domestic politicisation, European coordination, and national border closures in the COVID-19 crisis

ABSTRACT When the member states imposed unilateral restrictions on the cross-border movement of persons and goods in their initial response to the COVID-19 pandemic, the EU appeared to relapse into the ‘politics trap’ of earlier integration crises. However, our analysis of entry restrictions for persons in France, Germany, Italy, the Netherlands, and Poland from the end of 2019 to the summer of 2022 shows no systematic relationship between domestic politicisation and national border closures. Rather, border closures followed the course of the pandemic as well as EU recommendations. Our findings suggest that the EU was able to escape the ‘politics trap’ thanks to the exogenous and symmetrical nature of the crisis and effective EU-level policy coordination.

Might Cooperative Approaches Not Be So Cooperative? Exploring the Potential of Article 6.2 of the Paris Agreement to Generate Legal Disputes

Abstract With Article 6.2, the Paris Agreement offers its parties the possibility to engage in cooperative approaches to import mitigation outcomes that have been generated on the territory of another party and use these international transferred mitigation outcomes (itmos) for compliance purposes. While this possibility seems to pave the way to more—and presumably new forms of—climate cooperation outside the UN climate regime, this paper asks whether Article 6.2 is also likely to spark disagreement among states. It is suggested that it bears as much a potential to generate cooperation as to generate conflict. To illustrate that point, the paper explains how Article 6.2 could lead to conflict between developed and developing states over the legality of unilateral restrictions on the admittance of itmos and discusses what such conflict may look like, as well as its possible legal and political implications.

Restricted Unilateral Ankle Dorsiflexion Movement Increases Interlimb Vertical Force Asymmetries in Bilateral Bodyweight Squatting.

Crowe, MA, Bampouras, TM, Small, K, and Howe, LP. Restricted unilateral ankle dorsiflexion movement increases interlimb vertical force asymmetries in bilateral bodyweight squatting. J Strength Cond Res 34(2): 332-336, 2020-The purpose of this study was to investigate the effect of unilateral restrictions in ankle-dorsiflexion range of motion (DF-ROM) on interlimb vertical ground reaction force (vGRF) asymmetries. Twenty healthy and physically active volunteers (age 23 ± 3 years; height 1.72 ± 0.1 m; mass 74.9 ± 20.3 kg) performed 3 barefoot bodyweight squats (control condition) and with a 10° custom-built forefoot wedge under the right foot to artificially imitate ankle DF-ROM restriction (wedge condition). Force data were used to calculate the mean asymmetry index score for the upper descent phase, lower descent phase, lower ascent phase, and upper ascent phase during the bilateral squat. Significant differences were found for comparisons for each phase between conditions, with effect sizes ranging between 0.7 and 1.1. Asymmetry index scores indicated that for all phases, the unrestricted limb in the wedge condition produced greater vGRF. Therefore, interlimb differences in ankle DF-ROM can cause interlimb asymmetries in vGRF during bilateral squatting. As such, athletes with asymmetrical squat mechanics should be screened for interlimb differences in ankle DF-ROM to ascertain whether it is a contributing factor.

On the stability of reinforced arches

This paper deals with the problems of stability of circular arches supported by inextensible threads that cannot withstand compressive forces. Both ends of the thread are attached to the axis of the arch so that the distance between the attachment points cannot increase during deformation. The problems of stability and supercritical behavior of elastic systems in the presence of unilateral restrictions on the movement lead to the need to study the bifurcation points of the equations or to find the parameters for which some variational problem with restrictions on the desired functions in the form of inequalities has a non-unique solution. In the numerical study, this problem is reduced to finding and studying the bifurcation points of solutions to a nonlinear programming problem. The problem of finding bifurcation points for solutions of nonlinear programming problems is reduced to the problem of identification of conditional positive definiteness of quadratic forms on cones. There are criteria of conditional positive definiteness of quadratic forms on cones in the important special case, when the cone is a positive orthant in Euclidean space. Their application poses the necessity to calculate a large number of determinants, which is computationally extremely inefficient, although in the case of a small number of variables, they offer promise for solving Lyapunov stability problems. The paper proposes and justifies the method of searching for options to solve the problem of nonconvex quadratic programming that arises during the study of the stability of elastic unilateral restrictions on the movement. The results can be used in the design of arches and arch systems to improve their bearing capacity.

International Data Flows and Privacy: The Conflict and Its Resolution

The free flow of data across borders underpins today's globalized economy. But the flow of personal data outside the jurisdiction of national regulators also raises concerns about the protection of privacy. Addressing these legitimate concerns without undermining international integration is a challenge. This paper describes and assesses three types of responses to this challenge: unilateral development of national or regional regulation, such as the European Union's Data Protection Directive and forthcoming General Data Protection Regulation; international negotiation of trade disciplines, most recently in the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP); and international cooperation involving regulators, most significantly in the EU-U.S. Privacy Shield Agreement. The paper argues that unilateral restrictions on data flows are costly and can hurt exports, especially of data-processing and other data-based services; international trade rules that limit only the importers' freedom to regulate cannot address the challenge posed by privacy; and regulatory cooperation that aims at harmonization and mutual recognition is not likely to succeed, given the desirable divergence in national privacy regulation. The way forward is to design trade rules (as the CPTPP seeks to do) that reflect the bargain central to successful international cooperation (as in the EU-US Privacy Shield): regulators in data destination countries would assume legal obligations to protect the privacy of foreign citizens in return for obligations on data source countries not to restrict the flow of data. Existing multilateral rules can help ensure that any such arrangements do not discriminate against and are open to participation by other countries.

САНКЦИИ ООН В ОТНОШЕНИИ КНДР: ОЦЕНКА ЭФФЕКТИВНОСТИ

The last decade and a half we saw the gradual forming of a sanctions regime against the DPRK in connection with Pyongyang’s nuclear and missile programs. United Nations Security Council resolutions have disconnected North Korea from the global financial system, cut all foreign military ties with the country, introduced considerable sectoral sanctions on imports and exports, blocked major channels Pyongyang used to acquire foreign currency. Besides, the United States, South Korea and Japan have simultaneously enforced unilateral restrictions. Early 2018 offers an opportunity to solve the Korean Peninsula nuclear problem, and now is the time to assess the sanctions’ efficiency. We analyze the problems with their implementation and describe the means North Korea employs to circumvent the regime. Such measures include building an autarkic economy, ignoring the directives of the United Nations Security Council, deceiving international partners, exploiting the global market and engaging in espionage and diplomacy. These strategies allow the DPRK to support and develop the economy, as well as missile and nuclear programs. Whatever the outcome of the negotiations may be, it is already evident that sanctions cannot efficiently solve the nuclear issue and must give way to dialogue.

Equilibrium formulation of masonry helical stairs

In this paper the lower bound theorem of limit analysis for No-Tension materials is applied to study the equilibrium of spiral vaults, modeled as continuous unilateral membranes. The most efficient approach to the equilibrium of a thin shell is the covariant representation proposed by Pucher and adopted in the present study. Statically admissible singular stresses in the form of line or surface Dirac deltas and lying inside the masonry, are taken into account. The unilateral restrictions require that the Airy stress function representing the stress, be concave. The case study is a helical stair with a central pillar in Sanfelice Palace in Naples, whose structure is a tuff masonry spiral vault. The maps of the stress corresponding to two different stress functions and the safety factors in the two cases are provided.

Brexit and the Free Movement of Persons: A Plea for National Legal Self-Assertiveness

National judges and Member State governments have an obligation to be assertive about national interests threatened by EU policies, even to the extent of challenging existing doctrines of law, proposing new interpretations, and insisting on the proper division of judicial functions, for they have particular knowledge and understanding of the consequence of EU law. An unquestioning obedience to the Court of Justice and to established doctrine is not loyalty, but subversion of an essential legal dialogue, and a failure to play an active and constructive role in building a legal system which serves the goals and wellbeing of Europeans. The Brexit debate is a case study in this: despite claiming publicly that mass migration was threatening essential and legitimate public interests, the UK did not attempt to use the available doctrines or derogations to defend these, behaving as if legal orthodoxy was fixed in stone, and the only options were leave or accept. It would have been more loyal, more European, more helpful to Europe, to impose unilateral restrictions and defend them vigorously with evidence and good arguments.

Singular stress fields for masonry-like vaults

In the present paper, we apply the theorems of limit analysis to vaults modeled as masonry-like materials, that is, unilateral continuous bodies. On allowing for singular stresses, we consider statically admissible stress field concentrated on surfaces lying inside the masonry. Such structures are unilateral membranes, whose geometry is described a la Monge, and the equilibrium of them, under vertical loads, is formulated in the Pucher form. The problem is reduced to a singular partial differential equation of the second order where the shape f and the stress function F appear symmetrically. The unilateral restrictions require that the membrane surface lies in between the extrados and intrados surfaces of the vault and that the stress function be concave. Such a constraint is, in general, not satisfied on a given shape for given loads: in such a case, the shape has to be modified to fit the constraint. In a sense, the unilateral assumption renders the membrane an underdetermined structure that must adapt its shape in order to satisfy the unilateral restrictions. A number of simple examples are presented to illustrate how the method works.

On the detrimental impact of visa restrictions on bilateral trade and foreign direct investment

This article estimates the effect of visa restrictions on bilateral trade flows and foreign direct investment (FDI) stocks. By raising the costs of travel and deterring some visitors, visa restrictions hamper personal contact across borders, which is detrimental to trade and FDI. Employing a standard gravity-type model in a global dyadic country sample, I estimate that if one country unilaterally requires a visa from nationals of the other country with no reciprocal restriction in place by the partner country, this lowers bilateral trade and FDI by up to 19 and 25 per cent, respectively. If both countries require a visa from nationals of the other country, the effect on trade is larger, but less than double, at up to 28 per cent, while the effect on FDI is essentially the same as for unilateral restrictions. With such substantial negative effects, it is at least questionable whether many of the existing visa restrictions would pass a cost-benefit test.

Variational formulation and nonsmooth optimization algorithms in elastodynamic contact problems for cracked body

A mathematical model of an elastodynamic contact problem for a body with a crack with unilateral restrictions and friction on the crack faces is presented in classical and weak forms. Different variational formulations of unilateral contact problems with friction based on the principles of Hamilton–Ostrogradskii and Tupin, and boundary variational principles are considered. In particular, boundary variational functionals that are used with boundary integral equations are established. Nonsmooth optimization algorithms of Udzawa type for the solution of these unilateral contact problems with friction are developed. The convergence of the proposed algorithms is studied numerically.

Nonsmooth Optimization Algorithms in Some Problems of Fracture Dynamics

Mathematical statement of elastodynamic contact problem for cracked body with considering unilateral restrictions and friction of the crack faces is done in classical and weak forms. Different variational formulations of unilateral contact problems with friction based on boundary variational principle are considered. Nonsmooth optimization algorithms of Udzawa’s type for solution of unilateral contact problem with friction have been developed. Convergence of the proposed algorithms has been studied numerically.

Dynamic fracture mechanics with contact interaction at the crack edges

This paper deals with elastodynamic contact problems with unilateral restrictions and friction for bodies with cracks. General dynamic loading and a relevant case of harmonic loading are considered. The mathematical aspects of this problem are briefly discussed. The variational formulation of the problem, variational boundary inequalities and boundary functionals are used to solve it. The problems of a tension-compression plane harmonic wave interaction with one and two co-linear cracks of finite length with the allowance of unilateral contact interaction at the crack edges are solved. The influence of the contact interaction between the crack edges on a stress intensity factor is investigated.

Boundary integral equation and the existence theorems in contact problems with friction

The mathematical statements for contact problems with unilateral restrictions and friction for elastic bodies with cracks are investigated. The unilateral restrictions and friction on the crack surfaces are formulated in the form of inequalities. An algorithm for the solution of this problem is considered as the superposition of the boundary integral operators and projection operators on the sets of the unilateral restrictions and friction. The theorems of existence and uniqueness are proved.

Variational-hemivariational inequalities for multidimensional superpotential laws

A variational- hemivariational inequality on a vector valued functions space is considered with the nonconvex part satisfying unilateral growth restrictions, only. By applying Ky-Fan's theorem and the finite intersection property, an existence result is obtained and afterwords we give some applications.

The impact of unilateral OECD carbon taxes on the location of aluminium smelting

Aluminium smelting is electricity intensive. Within the OECD region, electricity generation is based largely on fossil fuels, and a carbon tax would have a significant impact on the cost of electricity. Outside the OECD, there are large amounts of additional electricity that could be generated through hydro–electricity or flare gas. If carbon limits were adopted unilaterally by the OECD nations, domestic producers would be at a competitive disadvantage. To quantify these ideas, we have updated a global aluminium trade model constructed at the World Bank during the early 1980s. According to our business–as–usual scenario, there will be a gradual shift toward new sources of production located outside the OECD region. Unilateral OECD carbon restrictions could dramatically accelerate this process.

Iterative Optimization with Equality Constraints

We discuss certain globally convergent iterative procedures for determining an “extremal” of a nonconvex optimization problem with a finite number of equality constraints and infinite-dimensional inclusion constraints. These procedures are designed for nonlinear programming and for relaxed optimal control problems with isoperimetric and unilateral restrictions. We also present a variant of one such procedure which does not involve any infinite subiterations.

Optimization and Controllability without Differentiability Assumptions

Let $\mathcal{X}$ and $\mathcal{Y}$ be real normed vector spaces, $K \subset \mathcal{X}$ convex and compact, $C \subset \mathcal{Y}$ a convex body, $\mathcal{U} \subset K$, and $(\phi ,\Phi ):K \to \mathbb{R}^m \times \mathcal{Y}$ a function that can be appropriately approximated by functions $(\phi _i ,\Phi _i )$ whose compositions with linear maps of small finite-dimensional simplices are $C^1 $. We derive sufficient conditions for $\phi $ to be (locally) controllable on $\mathcal{U}$ subject to the restriction $\Phi (u) \in C$, and obtain, as a corollary, corresponding necessary conditions for a related restricted minimum. These conditions are formulated in terms of directional derivate containers which are a type of set-valued “derivatives” of $(\phi ,\Phi )$, and they improve on and extend previously obtained results. They are used elsewhere to obtain new conditions for controllability and restricted minimum in nonsmooth optimal control problems defined by differential or functional-integral equations with isoperimetric and unilateral restrictions and involving either relaxed or original controls.

Controllability, extremality, and abnormality in nonsmooth optimal control

We derive sufficient conditions for controllability and necessary conditions for minimum in nonsmooth optimal control problems defined by differential or functional-integral equations with isoperimetric and unilateral restrictions. We consider the cases when the controls are relaxed or chosen fromabundant sets of original (ordinary) controls (which include most, or all, of the control sets studied in the literature). We prove that, if there exist optimal strictly original controls (that is, controls that are optimal in an abundant set but not among relaxed controls), then the problem admits abnormal extremals. We also study the abnormality of the optimal strictly original controls themselves.

Steepest Descent with Relaxed Controls

We prove the convergence of a steepest descent iterative procedure for determining an “extremal” point of a function defined on a sequentially compact convex subset of a topological vector space. We then apply this procedure to the problem of determining an extremal of a relaxed optimal control problem defined by ordinary differential equations without endpoint or unilateral restrictions.