Apodized-pupil Lyot coronagraphs: multistage designs for extremely large telescopes

Earlier apodized-pupil Lyot coronagraphs (APLC) have been studied and developed to enable high-contrast imaging for exoplanet detection and characterization with present-day ground-based telescopes. With the current interest in the development of the next generation of telescopes, the future extremely large telescopes (ELTs), alternative APLC designs involving multistage configuration appear attractive. The interest of these designs for application to ELTs is studied. Performance and sensitivity of multistage APLC to ELT specificities are analyzed and discussed, taking into account several ineluctable coronagraphic telescope error sources by means of numerical simulations. Additionally, a first laboratory experiment with a two-stages-APLC in the near-infrared (H-band) is presented to further support the numerical treatment. Multistage configurations are found to be inappropriate to ELTs. The theoretical gain offered by a multistage design over the classical single-stage APLC is largely compromised by the presence of inherent error sources occurring in a coronagraphic telescope, and in particular in ELTs. The APLC remains an attractive solution for ELTs, but rather in its conventional single-stage configuration.Comment: A&A accepte

How to Model Condensate Banking in a Simulation Model to Get Reliable Forecasts? Case Story of Elgin/Franklin

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Lie Algebroids in Classical Mechanics and Optimal Control

We review some recent results on the theory of Lagrangian systems on Lie algebroids. In particular we consider the symplectic and variational formalism and we study reduction. Finally we also consider optimal control systems on Lie algebroids and we show how to reduce Pontryagin maximum principle.Comment: This is a contribution to the Proc. of workshop on Geometric Aspects of Integrable Systems (July 17-19, 2006; Coimbra, Portugal), published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

The Evolution of Judicial Power: How the Supreme Court Effectively Legalized Rape on Indian Reservations

According to the 2010 National Intimate Partner and Sexual Violence Survey, nearly one in five women in the United States have experienced sexual violence. While the statistics are staggering, the rate of sexual assault on Indian reservations is more than twice the national average. According to the Department of Justice, one in three American Indian and Alaska Native women have been raped or have experienced an attempted rape during their lifetime. Moreover, the primary assailants are males who are not members of tribal communities. Why has rape, perpetrated by non-Indian males, become effectively legalized on reservations? What explains tribal courts’ limited legal capacity to prosecute rape? I emphasize the pivotal Oliphant v. Suquamish Indian Tribe decision that changed the landscape of judicial power on reservations. The result has produced unintended consequences, which greatly diminished the legal capacity to prosecute sexual assault cases in tribal courts. Consequently, three phases of evolution in U.S. history indicate that rape was effectively legalized. These three phases of evolution are dependent on colonialism. The criminal behavior of non-Indian males can be explained through the historical evolution of judicial power, which has in effect legalized rape in tribal communities. An examination of the hidden institutional elements considers the evolutionary trajectory of interactions between the U.S. government and tribal reservations. This broader frame analysis provides new insights toward the impact of Oliphant on the lives of American Indian and Alaska Native women

A Study on the Integration of a High-Speed Flywheel as an Energy Storage Device in Hybrid Vehicles

The last couple of decades have seen the rise of the hybrid electric vehicle as a compromise between the outstanding specific energy of petrol fuels and its low-cost technology, and the zero tail-gate emissions of the electric vehicle. Despite this, considerable reductions in cost and further increases in fuel economy are needed for their widespread adoption. An alternative low-cost energy storage technology for vehicles is the high-speed flywheel. The flywheel has important limitations that exclude it from being used as a primary energy source for vehicles, but its power characteristics and low-cost materials make it a powerful complement to a vehicle's primary propulsion system. This thesis presents an analysis on the integration of a high-speed flywheel for use as a secondary energy storage device in hybrid vehicles. Unlike other energy storage technologies, the energy content of the flywheel has a direct impact on the velocity of transmission. This presents an important challenge, as it means that the flywheel must be able to rotate at a speed independent of the vehicle's velocity and therefore it must be coupled via a variable speed transmission. This thesis presents some practical ways in which to accomplish this in conventional road vehicles, namely with the use of a variator, a planetary gear set or with the use of a power-split continuously variable transmission. Fundamental analyses on the kinematic behaviour of these transmissions particularly as they pertain to flywheel powertrains are presented. Computer simulations were carried out to compare the performance of various transmissions, and the models developed are presented as well. Finally the thesis also contains an investigation on the driving and road conditions that have the most beneficial effect on hybrid vehicle performance, with a particular emphasis on the effect that the road topography has on fuel economy and the significance of this

Improving student retention and achievement: what do we know and what do we need to find out?

Why do some students in post-compulsory education abandon courses? And why do others not achieve their full potential? What can colleges do to improve student retention and achievement? This report reviews the research done to date. Research about retention and achievement is examined under headings such as student motivation and decision-making, demographic factors, college-related issues, and advice and guidance. The review refers to previously inaccessible research, including unpublished reports from conferences and internal reports from institutions. In conclusion, priorities for future research and its application are identified

High-energy dileptons from an anisotropic quark-gluon plasma

We calculate leading-order dilepton yields from a quark-gluon plasma which has a time-dependent anisotropy in momentum space. Such anisotropies can arise during the earliest stages of quark-gluon plasma evolution due to the rapid longitudinal expansion of the created matter. A phenomenological model for the proper time dependence of the parton hard momentum scale, p_hard, and the plasma anisotropy parameter, xi, is proposed. The model describes the transition of the plasma from a 0+1 dimensional collisionally-broadened expansion at early times to a 0+1 dimensional ideal hydrodynamic expansion at late times. We find that high-energy dilepton production is enhanced by pre-equilibrium emission up to 50% at LHC energies, if one assumes an isotropization/thermalization time of 2 fm/c. Given sufficiently precise experimental data this enhancement could be used to determine the plasma isotropization time experimentally.Comment: 13 pages, 5 figures, talk given at the 4th international workshop on High-pT Physics at the LHC 09, February 4-7 2009, Prague, Czech Republic. Accepted to the proceedings of 4th international workshop High-pT physics at LHC 0