Impact of Dark Matter Microhalos on Signatures for Direct and Indirect Detection

Detecting dark matter as it streams through detectors on Earth relies on knowledge of its phase space density on a scale comparable to the size of our solar system. Numerical simulations predict that our Galactic halo contains an enormous hierarchy of substructures, streams and caustics, the remnants of the merging hierarchy that began with tiny Earth mass microhalos. If these bound or coherent structures persist until the present time, they could dramatically alter signatures for the detection of weakly interacting elementary particle dark matter (WIMP). Using numerical simulations that follow the coarse grained tidal disruption within the Galactic potential and fine grained heating from stellar encounters, we find that microhalos, streams and caustics have a negligible likelihood of impacting direct detection signatures implying that dark matter constraints derived using simple smooth halo models are relatively robust. We also find that many dense central cusps survive, yielding a small enhancement in the signal for indirect detection experiments.Comment: 6 pages, revision in response to referees report. Now accepted by Phys. Rev D., in pres

On the geometry of Hamiltonian chaos

We show that Gutzwiller's characterization of chaotic Hamiltonian systems in terms of the curvature associated with a Riemannian metric tensor in the structure of the Hamiltonian can be extended to a wide class of potential models of standard form through definition of a conformal metric. The geodesic equations reproduce the Hamilton equations of the original potential model when a transition is made to the dual manifold, and the geodesics in the dual space coincide with the orbits of the Hamiltonian potential model. We therefore find a direct geometrical description of the time development of a Hamiltonian potential model. The second covariant derivative of the geodesic deviation in this dual manifold generates a dynamical curvature, resulting in (energy dependent) criteria for unstable behavior different from the usual Lyapunov criteria. We discuss some examples of unstable Hamiltonian systems in two dimensions giving, in particular, detailed results for a potential obtained from a fifth order expansion of a Toda lattice Hamiltonian.Comment: 7 pages TeX, Figure captions, 4 figures (eps). Some clarifications, added reference

Global capital markets, housing prices, and partisan fiscal policies

In recent years, global imbalances have channeled the excess savings of surplus countries toward the real estate markets of deficit countries. By consequence, the deficit countries that attracted lots of foreign capital experienced large run-ups in house prices while the surplus countries that exported capital exhibited flat or slow house price growth. We argue that international capital flows affect the fiscal policy preferences of both voters and political parties by way of their impact on housing prices. Where capital inflows are large and housing prices are rising, we expect voters to respond by demanding both lower taxes and less publicly-provided social insurance. This is because rising house prices allow homeowners to “self insure” against income losses due to unemployment, illness, and old age. We present survey evidence that supports this claim. Furthermore, we find that responses to house prices are mirrored in capital exporting countries: households become more supportive of both taxes and social insurance as home prices remain flat or decline. Finally, we show that political parties are the mechanisms through which the fiscal preferences of households find policy expression. Taxes and social insurance spending tend to fall (rise) where the right (left) is in power and capital inflows are driving up housing prices. In capital exporting nations, by contrast, we find an attenuation of these partisan fiscal policy outcomes

Autonomy versus futility? Barriers to good clinical practice in end-of-life care: a Queensland case

Findings from a Queensland coronial inquest highlight the complex clinical, ethical and legal issues that arise in end-of-life care when clinicians and family members disagree about a diagnosis of clinical futility. The tension between the law and best medical practice is highlighted in this case, as doctors are compelled to seek family consent to not commence a futile intervention. Good communication between doctors and families, as well as community and professional education, is essential to resolve tensions that can arise when there is disagreement about treatment at the end of life

Traditional places and modernist spaces : regional geography and northwestern landscapes of power in Canada, 1850-1990

Regions are the manifestation of ideology and power in the landscape. This study maintains that changes in the allocation and exercise of state power are reflected in Western Canada's regional geography at different time periods and that the ideology(ies) supporting this power is (are) actively advanced by the creation, maintenance, and continued existence of those regions. Traditional approaches to historical geography neglect this socio-political aspect of region. To that end, alternate, contemporary approaches are applied. Aspects of critical social theory will illuminate the roles of both ideology and power and their crucial place in forming the human-built environment. Different places in different time periods will be analysed. These include: the territories of the Canadian North-West 'circa' 1885; Alberta and Saskatchewan to provincehood, 1905; and the Inuvialuit Settlement Area, 1990

Design and Control of an Experimental Tilt-Wing Aircraft

In this project, work has been done in the field of conceptual design of experimental tiltrotors. The main tools that have been used are NDARC (NASA Design and Analysis of Rotorcraft) and SIMPLI-FLYD. NDARC is a conceptual design tool for rotorcraft, and it is used to find trim points under various flight conditions. SIMPLI-FLYD is an integrated collection of software tools that enables a flight dynamics and control assessment of the rotorcraft vehicle design generated from NDARC. Two different tiltrotors have been investigated. Initially, work was done with the Bell XV- 15 tiltrotor. NDARCs ability to correctly model the tiltwing transition between airplane mode and hover mode was looked into. In addition, data from old flight tests were compared to the NDARC output, to see how accurately performance could be predicted. After the XV-15 analysis, an NDRARC model of a novel tiltwing concept from Elytron Aircraft was written and analyzed together with SIMPLI-FLYD. Elytron 2S is an experimental tiltwing aircraft, consisting of a joined-wing design with a small central wing for the proprotor. An alternative approach to hover control is used, where the typical rotor hub and swash plate are substituted for linear actuators controlling pitch, yaw and roll. The objective with the analysis of Elytron is to obtain a more complete understanding of the maneuverability and possible performance of this alternative aircraft configuration