Fractional Quantum Hall States in Ultracold Rapidly Rotating Dipolar Fermi Gases

We demonstrate the experimental feasibility of incompressible fractional quantum Hall-like states in ultra-cold two dimensional rapidly rotating dipolar Fermi gases. In particular, we argue that the state of the system at filling fraction $\nu =1/3$ is well-described by the Laughlin wave function and find a substantial energy gap in the quasiparticle excitation spectrum. Dipolar gases, therefore, appear as natural candidates of systems that allow to realize these very interesting highly correlated states in future experiments.Comment: 4 pages, 2 figure

Tangles of superpositions and the convex-roof extension

We discuss aspects of the convex-roof extension of multipartite entanglement measures, that is, SL(2,\CC) invariant tangles. We highlight two key concepts that contain valuable information about the tangle of a density matrix: the {\em zero-polytope} is a convex set of density matrices with vanishing tangle whereas the {\em convex characteristic curve} readily provides a non-trivial lower bound for the convex roof and serves as a tool for constructing the convex roof outside the zero-polytope. Both concepts are derived from the tangle for superpositions of the eigenstates of the density matrix. We illustrate their application by considering examples of density matrices for two-qubit and three-qubit states of rank 2, thereby pointing out both the power and the limitations of the concepts.Comment: 7 pages, 5 figures, revtex

dSarm/Sarm1 Governs a Conserved Axon Death Program: A Dissertation

Axonal and synaptic degeneration is a hallmark of peripheral neuropathy, brain injury, and neurodegenerative disease. Axonal degeneration has been proposed to be mediated by an active autodestruction program, akin to apoptotic cell death; however, loss-of-function mutations capable of potently blocking axon self-destruction have not been described. Using a forward genetic screen in Drosophila, we identified that loss of the Toll receptor adaptor dSarm (sterile a/Armadillo/Toll-Interleukin receptor homology domain protein) cell-autonomously suppresses Wallerian degeneration for weeks after axotomy. Severed mouse Sarm1 null axons exhibit remarkable long-term survival both in vivo and in vitro, indicating that Sarm1 prodegenerative signaling is conserved in mammals. Our results provide direct evidence that axons actively promote their own destruction after injury and identify dSarm/Sarm1 as a member of an ancient axon death signaling pathway. This death signaling pathway can be activated without injury by loss of the N-terminal self-inhibitory domain, resulting in spontaneous neurodegeneration. To investigate the role of axon self-destruction in disease, we assessed the effects of Sarm1 loss on neurodegeneration in the SOD1-G93A model of amyotrophic lateral sclerosis (ALS), a lethal condition resulting in progressive motor neuron death and paralysis. Loss of Sarm1 potently protects motor axons and synapses from degeneration, but only extends animal survival by 10%. Thus, there appears to be at least two driving forces in place during ALS disease progression: (1) Sarm1 mediated axon death, and (2) cell body destruction via some unknown mechanism

Household-Level Livestock Marketing Behavior Among Northern Kenyan and Southern Ethiopian Pastoralists

Pastoralists in East Africa's arid and semi-arid lands (ASAL) regularly confront climatic shocks triggering massive herd die-offs and loss of scarce wealth. On the surface, it appears puzzling that pastoralists do not make extensive use of livestock markets to offload animals when climatic shocks temporarily reduce the carrying capacity of local rangelands, and then use markets to restock their herds when local conditions recover. In recent years, donors and policy makers have begun to hypothesize that investments in livestock marketing systems might quickly pay for themselves through reduced demand for relief aid,by increasing pastoralist marketing responsiveness to temporal variation in range conditions.Marketing,

Out of equilibrium correlation functions of quantum anisotropic XY models: one-particle excitations

We calculate exactly matrix elements between states that are not eigenstates of the quantum XY model for general anisotropy. Such quantities therefore describe non equilibrium properties of the system; the Hamiltonian does not contain any time dependence. These matrix elements are expressed as a sum of Pfaffians. For single particle excitations on the ground state the Pfaffians in the sum simplify to determinants.Comment: 11 pages, no figures; revtex. Minor changes in the text; list of refs. modifie

Lack of Diversity in Leadership: Could Selective Randomness Break the Deadlock?

The proportion of women and ethnic minorities in senior management remains indefensibly low. Radical ideas are therefore needed. This paper proposes one. It is to use a form of selective randomness -- random selection from among a pool of pre-chosen and qualified candidates -- as a new HRM tool. We argue this in two parts – an equity case and an efficiency case. First, selective randomness would ensure greater equity between the sexes and races over time; offer ‘rejection insurance’ to candidates wary of discrimination, and thereby mitigate the fear of failure; and encourage women and non-whites to enter tournaments. Second, we consider also the criterion of efficiency. The standard of candidates going into management would be raised; homophily would be reduced, thus improving diversity of people and ideas, and reducing the ‘chosen one’ factor. By using Jensen’s inequality from applied mathematics, we provide the first demonstration that random selection could act to improve organizational efficiency by raising the chance of an extraordinary manager being hired