Dimensional Effects on the Density of States in Systems with Quasi-Relativistic Dispersion Relations and Potential Wells

Motivated by the recent discoveries of materials with quasi-relativistic dispersion relations, we determine densities of states in materials with low dimensional substructures and relativistic dispersion relations. We find that these dimensionally hybrid systems yield quasi-relativistic densities of states that are a superposition of the corresponding two- and three-dimensional densities of states.Comment: To be submitted to the Canadian Journal of Physics, 8 pages, 4 figue

Some spectrometric results from the NASA 1968 Airborne Auroral Expedition and tentative identification of several N2 c prime /1 Sigma u plus/ yields a /1 Pi g/ bands in auroras

Spectrophotometric results from NASA 1968 Airborne Auroral Expedition and tentative identification of several molecular nitrogen emission band

UN reform and NATO transformation: the missing link. Egmont Paper, no. 10, November 2005

From NATO’s perspective, Kofi Annan’s report In Larger Freedom: Towards Development, Security and Human Rights for All at first sight seemed hardly relevant.(1) In dealing with regional organizations, it nowhere explicitly mentioned the North Atlantic Treaty Organization (NATO). This was all the more surprising because Annan thus bypassed NATO’s active involvement in the implementation of a number of post-conflict peace-building settlements, based on UN Security Council resolutions, in areas such as Kosovo, Afghanistan and Iraq. In the weeks after the publication of Annan’s report, NATO’s Secretary- General, Jaap de Hoop Scheffer, on several occasions expressed his support for his UN counterpart’s reform package. In a keynote address in Brussels, among others, he argued that ‘NATO will increasingly act in concert with other institutions’, including the UN, pointing at NATO’s cooperation on the ground in the Balkans and Afghanistan

Consistency of Markov chain quasi-Monte Carlo on continuous state spaces

The random numbers driving Markov chain Monte Carlo (MCMC) simulation are usually modeled as independent U(0,1) random variables. Tribble [Markov chain Monte Carlo algorithms using completely uniformly distributed driving sequences (2007) Stanford Univ.] reports substantial improvements when those random numbers are replaced by carefully balanced inputs from completely uniformly distributed sequences. The previous theoretical justification for using anything other than i.i.d. U(0,1) points shows consistency for estimated means, but only applies for discrete stationary distributions. We extend those results to some MCMC algorithms for continuous stationary distributions. The main motivation is the search for quasi-Monte Carlo versions of MCMC. As a side benefit, the results also establish consistency for the usual method of using pseudo-random numbers in place of random ones.Comment: Published in at http://dx.doi.org/10.1214/10-AOS831 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Are low-performing students more likely to exit charter schools? Evidence from New York City and Denver, Colorado

A common criticism of charter schools is that they systematically remove or “counsel out” their lowest performing students. However, relatively little is currently known about whether low-performing students are in fact more likely to exit charter schools than surrounding traditional public schools. We use longitudinal student-level data from two large urban school systems that prior research has found to have effective charter school sectors–New York City and Denver, Colorado–to evaluate whether there is a differential relationship between low-performance on standardized test scores and the probability that students exit their schools by sector attended. We find no evidence of a differential relationship between prior performance and the likelihood of exiting a school by sector. Low-performing students in both cities are either equally likely or less likely to exit their schools than are student in traditional public schools.We would like to thank the Denver Public School System for providing the data necessary for this paper, and we especially appreciated the assistance of Josh Drake, Yu-lu Hsiung, and Alisha Anuscencion. Funding for this project comes from the Searle Charitable Trust. We thank the Foundation for its support, but acknowledge that the findings and conclusions presented are our own and do not necessarily represent those of the Foundation. All remaining errors are our own. (Searle Charitable Trust)http://sites.bu.edu/marcuswinters/files/2017/09/Exiting-Charter-Schools.pdfAccepted manuscrip

The Creation of a CPU Timer for High Fidelity Programs

Using C and C++ programming languages, a tool was developed that measures the efficiency of a program by recording the amount of CPU time that various functions consume. By inserting the tool between lines of code in the program, one can receive a detailed report of the absolute and relative time consumption associated with each section. After adapting the generic tool for a high-fidelity launch vehicle simulation program called MAVERIC, the components of a frequently used function called "derivatives ( )" were measured. Out of the 34 sub-functions in "derivatives ( )", it was found that the top 8 sub-functions made up 83.1% of the total time spent. In order to decrease the overall run time of MAVERIC, a launch vehicle simulation program, a change was implemented in the sub-function "Event_Controller ( )". Reformatting "Event_Controller ( )" led to a 36.9% decrease in the total CPU time spent by that sub-function, and a 3.2% decrease in the total CPU time spent by the overarching function "derivatives ( )"

Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon

Growth of GaAs/GaAsSb heterostructurenanowires on silicon without the need for gold seed particles is presented. A high vertical yield of GaAsnanowires is first obtained, and then GaAsₓSb₁ˍₓ segments are successfully grown axially in these nanowires. GaAsSb can also be integrated as a shell around the GaAs core. Finally, two GaAsSb segments are grown inside a GaAsnanowire and passivated using an AlₓGa₁ˍₓAs shell. It is found that no stacking faults or twin planes occur in the GaAsSb segments.Part of this work was funded by the Swedish Foundation for Strategic Research SSF, the Swedish Research Council VR, and the Knut and Alice Wallenberg Foundation

SMIL State: an architecture and implementation for adaptive time-based web applications

In this paper we examine adaptive time-based web applications (or presentations). These are interactive presentations where time dictates which parts of the application are presented (providing the major structuring paradigm), and that require interactivity and other dynamic adaptation. We investigate the current technologies available to create such presentations and their shortcomings, and suggest a mechanism for addressing these shortcomings. This mechanism, SMIL State, can be used to add user-defined state to declarative time-based languages such as SMIL or SVG animation, thereby enabling the author to create control flows that are difficult to realize within the temporal containment model of the host languages. In addition, SMIL State can be used as a bridging mechanism between languages, enabling easy integration of external components into the web application. Finally, SMIL State enables richer expressions for content control. This paper defines SMIL State in terms of an introductory example, followed by a detailed specification of the State model. Next, the implementation of this model is discussed. We conclude with a set of potential use cases, including dynamic content adaptation and delayed insertion of custom content such as advertisements. © 2009 Springer Science+Business Media, LLC