Phase-Field Model of Stressed Incoherent Solid-Solid Interfaces

We introduce a new phase-field model which allows for simulation of incoherent solid/solid transformations. Contrary to previous models which impose coherency at the interface, the zero shear-stress condition characteristic of incoherent solids is recovered in the limit of small interface thickness. For the sake of clarity, we limit ourselves to the case of stress-driven phase transitions between two elastic solids. However, since we use a variational formulation which has a clear thermodynamic interpretation, the extension of the model to the cases of chemical and/or thermal diffusion is straightforward.Comment: RevTeX4 source file, 1 eps figur

Precarity and Agency through a Migration Lens

This special issue leverages the migrant experience to better understand precarity and agency in the contemporary world. By way of introduction, we examine the broader bodies of literature on precarity and agency, relate them to research on migration, and link them to the contributions in the special issue. Laying a foundation for further research, we illuminate three approaches to study the precarity-migration-agency nexus: an industry-specific approach, a sending country/deportee approach, and a collective action approach. We conclude with a critical analysis of freedom and national borders, considering the \u27open borders\u27 movement, postnational citizenship, and opposition to marketization

Tensor Products, Positive Linear Operators, and Delay-Differential Equations

We develop the theory of compound functional differential equations, which are tensor and exterior products of linear functional differential equations. Of particular interest is the equation $\dot x(t)=-\alpha(t)x(t)-\beta(t)x(t-1)$ with a single delay, where the delay coefficient is of one sign, say $\delta\beta(t)\ge 0$ with $\delta\in{-1,1}$. Positivity properties are studied, with the result that if $(-1)^k=\delta$ then the $k$-fold exterior product of the above system generates a linear process which is positive with respect to a certain cone in the phase space. Additionally, if the coefficients $\alpha(t)$ and $\beta(t)$ are periodic of the same period, and $\beta(t)$ satisfies a uniform sign condition, then there is an infinite set of Floquet multipliers which are complete with respect to an associated lap number. Finally, the concept of $u_0$-positivity of the exterior product is investigated when $\beta(t)$ satisfies a uniform sign condition.Comment: 84 page

A condition on delay for differential equations with discrete state-dependent delay

Parabolic differential equations with discrete state-dependent delay are studied. The approach, based on an additional condition on the delay function introduced in [A.V. Rezounenko, Differential equations with discrete state-dependent delay: uniqueness and well-posedness in the space of continuous functions, Nonlinear Analysis: Theory, Methods and Applications, 70 (11) (2009), 3978-3986] is developed. We propose and study a state-dependent analogue of the condition which is sufficient for the well-posedness of the corresponding initial value problem on the whole space of continuous functions $C$. The dynamical system is constructed in $C$ and the existence of a compact global attractor is proved

Machiavelli, Fichte, and Clausewitz in the Labyrinth of German Idealism

Fichte’s 1807 essay on Machiavelli, written when much of Prussia was occupied by French troops, and Clausewitz’s lengthy response, based on long acquaintance with Machiavelli’s works, discuss Machiavelli’s writings as an inspiration and practical guide in helping German states regain their liberty. As well as their authors’ politics, the two essays reveal their different views of history – Fichte’s being highly deterministic, as is that of his friend Johannes von Müller, the historian of the Swiss struggle for freedom; whereas Clausewitz seeks objectivity in his reading of the past, without which, he has come to believe, he cannot understand war and its place in history. For Clausewitz, Machiavelli’s writings are of more than current political significance; they have given valuable support to his growing recognition of the mutual dependence of war and politics

Constraints on the braneworld from compact stars

According to the braneworld idea, ordinary matter is confined on a 3-dimensional space (brane) that is embedded in a higher-dimensional space-time where gravity propagates. In this work, after reviewing the limits coming from general relativity, finiteness of pressure and causality on the brane, we derive observational constraints on the braneworld parameters from the existence of stable compact stars. The analysis is carried out by solving numerically the brane-modified Tolman-Oppenheimer-Volkoff equations, using different representative equations of state to describe matter in the star interior. The cases of normal dense matter, pure quark matter and hybrid matter are considered.Comment: 13 pages, 11 figures, 2 tables; new EoS considered, references and comments adde

Politics of solidarity and agency in an age of precarity

Abstract: This article critically examines Guy Standing’s A Precariat Charter by posing three questions: 1) What is the significance of the North/South divide for the global spread of the precariat? 2) Is the precariat an agent of transformation, or simply a passive recipient? 3) How should we understand the fragmentation of the working class and its implications for progressive change? In addressing these questions, I argue that Standing’s analysis offers useful insights into the current era of insecurity. But it downplays important variations in forms of precarity, and also over‐emphasises fragmentation and weakness. The limits of this approach are illustrated through two empirical examples drawn from Johannesburg, South Africa, and Oakland, United States. Taken together, these examples point towards a broader and more fluid understanding of the “working class”. They also underscore possibilities for workingclass solidarity, both between stable workers and their more precarious counterparts, and between different groups that Standing identifies as the precariat

Towards a precarity agenda

Abstract: It is widely acknowledged that the closing decades of the twentieth century, and the early decades of the twenty‐first century, have been marked by growing economic insecurity across the globe. But how we understand this process is highly contested. What are the sources of economic insecurity? To what extent do contemporary forms of economic and political organisation mark a break from the past? What analytical tools do we need to make sense of the current moment? Are new concepts needed, or will well‐established concepts suffice? What are the implications of growing economic insecurity for questions of agency, solidarity, class struggle and social change? How does economic insecurity relate to various forms of collective organisation such as trade unions, political parties and community‐based organisations