Overview of the NASA high power laser program

The overall objectives of the NASA High Power Laser Program are reviewed along with their structure and center responsibilities. Present and future funding, laser power transmission in space, selected program highlights, the research and technology schedule, and the expected pace of the program are briefly considered

NASA thermionic-conversion program

Current out-of-core emphases allow converter material and design freedoms previously prohibited by in-core nucleonic and geometric restrictions. As a result, potential improvements indicate possibilities for severalfold increases in efficiencies. The new TEC-ART program concentrated initially on low-work function collectors and interelectrode-loss reduction and revealed much in a short time. This new emission capability coupled with improved collectors that maintain performance with emitter-vapor deposit accumulations are requisites for efficient, enduring thermionic converters

Geometric extensions of many-particle Hardy inequalities

Certain many-particle Hardy inequalities are derived in a simple and systematic way using the so-called ground state representation for the Laplacian on a subdomain of $\mathbb{R}^n$. This includes geometric extensions of the standard Hardy inequalities to involve volumes of simplices spanned by a subset of points. Clifford/multilinear algebra is employed to simplify geometric computations. These results and the techniques involved are relevant for classes of exactly solvable quantum systems such as the Calogero-Sutherland models and their higher-dimensional generalizations, as well as for membrane matrix models, and models of more complicated particle interactions of geometric character.Comment: Revised version. 28 page

Matrix Models and Lorentz Invariance

The question of Lorentz invariance in the membrane matrix model is addresse

A review of the NASA/OAST cryogenic coolers technology program

Low and ultra low temperature cryogenic cooler systems for future space missions include mechanical, solid cryogen, gas adsorption, superfluid helium, helium-3, and magnetic (adiabatic demagnetization) coolers. Operating lifetimes required vary from a few weeks for a Shuttle/Spacelab mission to as long as nine years for missions to the outer planets. Temperature requirements vary from tens to tenths of kelvin. At the higher temperature, cooling loads for detectors, instruments and associated shields may be as high as 15 watts. The general requirements for low and ultra low temperature and techniques that can be employed to achieve these temperatures at expected heat loads are discussed. The NASA Centers involved in the R & T efforts and the type of cooler systems on which they are focusing their effort are considered as well as the thrust of R & T effort for each cooler type. Projected missions that will use the technology are identified

Partial Hamiltonian reduction of relativistic extended objects in light-cone gauge

The elimination of the non-transversal field in the standard light-cone formulation of higher-dimensional extended objects is formulated as a Hamiltonian reduction.Comment: 11 page

Discussion of: “On the Aggregation and Valuation of Deferred Taxes”

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47712/1/11142_2004_Article_354422.pd

A dynamical symmetry for supermembranes

A dynamical symmetry for supersymmetric extended objects is given.Comment: 3 page

Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions

Green roofs perform ecosystem services such as summer roof temperature reduction and stormwater capture that directly contribute to lower building energy use and potential economic savings. These services are in turn related to ecosystem functions performed by the vegetation layer such as radiation reflection and transpiration, but little work has examined the role of plant species composition and diversity in improving these functions.We used a replicated modular extensive (shallow growing- medium) green roof system planted with monocultures or mixtures containing one, three or five life-forms, to quantify two ecosystem services: summer roof cooling and water capture. We also measured the related ecosystem properties/processes of albedo, evapotranspiration, and the mean and temporal variability of aboveground biomass over four months. Mixtures containing three or five life-form groups, simultaneously optimized several green roof ecosystem functions, outperforming monocultures and single life-form groups, but there was much variation in performance depending on which life-forms were present in the three life-form mixtures. Some mixtures outperformed the best monocultures for water capture, evapotranspiration, and an index combining both water capture and temperature reductions. Combinations of tall forbs, grasses and succulents simultaneously optimized a range of ecosystem performance measures, thus the main benefit of including all three groups was not to maximize any single process but to perform a variety of functions well.Ecosystem services from green roofs can be improved by planting certain life-form groups in combination, directly contributing to climate change mitigation and adaptation strategies. The strong performance by certain mixtures of life-forms, especially tall forbs, grasses and succulents, warrants further investigation into niche complementarity or facilitation as mechanisms governing biodiversity-ecosystem functioning relationships in green roof ecosystems

The Predictive Value of Expenses Excluded from Pro Forma Earnings

We investigate the informational properties of pro forma earnings. This increasingly popular measure of earnings excludes certain expenses that the company deems non-recurring, non-cash, or otherwise unimportant for understanding the future value of the firm. We find, however, that these expenses are far from unimportant. Higher levels of exclusions lead to predictably lower future cash flows. We also find that investors do not fully appreciate the lower cash flow implications at the time of the earnings announcement. A trading strategy based on the excluded expenses yields a large positive abnormal return in the years following the announcement, and persists after controlling for various risk factors and other anomalies.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47728/1/11142_2004_Article_5127173.pd