X-ray Transform and Boundary Rigidity for Asymptotically Hyperbolic Manifolds

We consider the boundary rigidity problem for asymptotically hyperbolic manifolds. We show injectivity of the X-ray transform in several cases and consider the non-linear inverse problem which consists of recovering a metric from boundary measurements for the geodesic flow.Comment: 54 page

Discards in fisheries - a summary of three decades of research at IMARES and LEI

Discards and the possible ecological and economic effects of discarding are a hot topic in discussions about sustainable fisheries. The perception of the effects of discarding differs between parties and it is influenced by the ecosystem functioning and the state of the species under consideration. This report provides an overview of the current scientific knowledge at IMARES and LEI about discard levels, effects, and discard reduction from an ecological, technical, economic and management perspective. The following Dutch commercial marine wild capture fisheries with active gear are considered: pelagic, beam trawl, otter trawl (demersal fish and nephrops) and shrimp fisheries

Connections and Metrics Respecting Standard Purification

Standard purification interlaces Hermitian and Riemannian metrics on the space of density operators with metrics and connections on the purifying Hilbert-Schmidt space. We discuss connections and metrics which are well adopted to purification, and present a selected set of relations between them. A connection, as well as a metric on state space, can be obtained from a metric on the purification space. We include a condition, with which this correspondence becomes one-to-one. Our methods are borrowed from elementary *-representation and fibre space theory. We lift, as an example, solutions of a von Neumann equation, write down holonomy invariants for cyclic ones, and ``add noise'' to a curve of pure states.Comment: Latex, 27 page

Travelling-waves consistent with turbulence-driven secondary flow in a square duct

We present numerically determined travelling-wave solutions for pressure-driven flow through a straight duct with a square cross-section. This family of solutions represents typical coherent structures (a staggered array of counter-rotating streamwise vortices and an associated low-speed streak) on each wall. Their streamwise average flow in the cross-sectional plane corresponds to an eight vortex pattern much alike the secondary flow found in the turbulent regime

The European Landing Obligation. Reducing Discards in Complex, Multi-Species and Multi-Jurisdictional Fisheries

This open access book provides a comprehensive examination of the European Landing Obligation policy from many relevant perspectives. It includes evaluations of its impacts at economical, socio-cultural, ecological and institutional levels. It also discusses the feasibility and benefits of several potential mitigation strategies. The book was timely published, exactly at the time where the Landing Obligation was planned to be fully implemented. This book is of significant interest to all stakeholders involved, but also to the general public of Europe and to other jurisdictions throughout the world that are also searching for ways to deal with by-catch and discard issues

Fidelity and Concurrence of conjugated states

We prove some new properties of fidelity (transition probability) and concurrence, the latter defined by straightforward extension of Wootters notation. Choose a conjugation and consider the dependence of fidelity or of concurrence on conjugated pairs of density operators. These functions turn out to be concave or convex roofs. Optimal decompositions are constructed. Some applications to two- and tripartite systems illustrate the general theorem.Comment: 10 pages, RevTex, Correction: Enlarged, reorganized version. More explanation

Emergent Horizons in the Laboratory

The concept of a horizon known from general relativity describes the loss of causal connection and can be applied to non-gravitational scenarios such as out-of-equilibrium condensed-matter systems in the laboratory. This analogy facilitates the identification and theoretical study (e.g., regarding the trans-Planckian problem) and possibly the experimental verification of "exotic" effects known from gravity and cosmology, such as Hawking radiation. Furthermore, it yields a unified description and better understanding of non-equilibrium phenomena in condensed matter systems and their universal features. By means of several examples including general fluid flows, expanding Bose-Einstein condensates, and dynamical quantum phase transitions, the concepts of event, particle, and apparent horizons will be discussed together with the resulting quantum effects.Comment: 7 pages, 4 figure