Simple flexible polymers in a spherical cage

We report the results of Monte Carlo simulations investigating the effect of a spherical confinement within a simple model for a flexible homopolymer. We use the parallel tempering method combined with multi-histogram reweighting analysis and multicanonical simulations to investigate thermodynamical observables over a broad range of temperatures, which enables us to describe the behavior of the polymer and to locate the freezing and collapse transitions. We find a strong effect of the spherical confinement on the location of the collapse transition, whereas the freezing transition is hardly effected.Comment: 7 pages, 4 figure

An Algorithmic Study of Manufacturing Paperclips and Other Folded Structures

We study algorithmic aspects of bending wires and sheet metal into a specified structure. Problems of this type are closely related to the question of deciding whether a simple non-self-intersecting wire structure (a carpenter's ruler) can be straightened, a problem that was open for several years and has only recently been solved in the affirmative. If we impose some of the constraints that are imposed by the manufacturing process, we obtain quite different results. In particular, we study the variant of the carpenter's ruler problem in which there is a restriction that only one joint can be modified at a time. For a linkage that does not self-intersect or self-touch, the recent results of Connelly et al. and Streinu imply that it can always be straightened, modifying one joint at a time. However, we show that for a linkage with even a single vertex degeneracy, it becomes NP-hard to decide if it can be straightened while altering only one joint at a time. If we add the restriction that each joint can be altered at most once, we show that the problem is NP-complete even without vertex degeneracies. In the special case, arising in wire forming manufacturing, that each joint can be altered at most once, and must be done sequentially from one or both ends of the linkage, we give an efficient algorithm to determine if a linkage can be straightened.Comment: 28 pages, 14 figures, Latex, to appear in Computational Geometry - Theory and Application

LAWS: Prospects of Regulation

Lethally Autonomous Weapons Systems are a new emerging technology within the international arena, yet prospects of regulation have scarcely been discussed. This means that this technology, if further developed without regulation, could cause significant casualties and violations of International Humanitarian Law. While this hasn\u27t happened yet, it is important to have these discussions now because later may be too late. This technology is developing fast and is going relatively unnoticed or not understood by many

Economic Interdependence and Conflict: An International Relations Theory Analysis

Theories of International Relations are constructed to help make sense of how power is divided amongst international actors. Three prominent theories: Realism, Liberalism, and Neo-Marxism, interpret international phenomena differently based on their assumptions about structures of global power. Economic interdependence is seen by each theory to impact who has power and how that power is maintained. These theories diverge in interpreting how economic interdependence impacts forms of conflict. These pieces do not interpret which theory is correct but work to emphasize the contextual foundations and analytical framework for how each theory perceives the entanglement of economic interdependence and conflict