Space photography and the exploration of Mars

A general exposition of the scientific potentialities and analytic framework of space photography is presented using the photography of Mars from flybys and orbiters as the principal example. Space photography is treated here as a communication process in which planetary scene information is communicated to the eye-brain receiver of earth-based interpreters. The salient parameters of this process are: (1) total information returned, (2) surface resolution, and (3) a priori knowledge regarding the planetary surface observed

Dynamical Self-assembly during Colloidal Droplet Evaporation Studied by in situ Small Angle X-ray Scattering

The nucleation and growth kinetics of highly ordered nanocrystal superlattices during the evaporation of nanocrystal colloidal droplets was elucidated by in situ time resolved small-angle x-ray scattering. We demonstrated for the first time that evaporation kinetics can affect the dimensionality of the superlattices. The formation of two-dimensional nanocrystal superlattices at the liquid-air interface of the droplet has an exponential growth kinetics that originates from interface "crushing".Comment: 4 pages, 4 figure

IMPACT OF LOCALIZED CUTBACKS IN AGRICULTURAL PRODUCTION ON A STATE ECONOMY

This study examines the effects that a cutback in production by Texas agricultural producers would have on the economic well-being of all producers and consumers in the stateÂ’s economy. To do this, a quadratic input-output model incorporating econometric estimates of final demand was developed for the Texas economy. The output of the agricultural production sectors was constrained to reflect the cutback in production. The results show that agricultural producers would be economically worse off than before only if the producers of raw agricultural products in Texas imported their input needs from other geographical areas.Community/Rural/Urban Development, Production Economics,

Diversity among multidrug-resistant enterococci.

Enterococci are associated with both community- and hospital-acquired infections. Even though they do not cause severe systemic inflammatory responses, such as septic shock, enterococci present a therapeutic challenge because of their resistance to a vast array of antimicrobial drugs, including cell-wall active agents, all commercially available aminoglycosides, penicillin and ampicillin, and vancomycin. The combination of the latter two occurs disproportionately in strains resistant to many other antimicrobial drugs. The propensity of enterococci to acquire resistance may relate to their ability to participate in various forms of conjugation, which can result in the spread of genes as part of conjugative transposons, pheromone-responsive plasmids, or broad host-range plasmids. Enterococcal hardiness likely adds to resistance by facilitating survival in the environment (and thus enhancing potential spread from person to person) of a multidrug-resistant clone. The combination of these attributes within the genus Enterococcus suggests that these bacteria and their resistance to antimicrobial drugs will continue to pose a challenge

Optimization study of high power static inverters and converters Final report

Optimization study and basic performance characteristics for conceptual designs for high power static inverter

Pure multiplicative stochastic resonance of anti-tumor model with seasonal modulability

The effects of pure multiplicative noise on stochastic resonance in an anti-tumor system modulated by a seasonal external field are investigated by using theoretical analyses of the generalized potential and numerical simulations. For optimally selected values of the multiplicative noise intensity quasi-symmetry of two potential minima and stochastic resonance are observed. Theoretical results and numerical simulations are in good quantitative agreement.Comment: 5 pages, 5 figure

Landscape-Level Impacts of Mesquite Canopy Cover on Herbaceous Species Composition

Woody encroachment of mesquite (Prosopis) and acacia (Acacia) species into grasslands has widespread and ongoing impacts on grassland ecosystems. Changes in the herbaceous layer are associated with changes in the canopy cover of these sparse-canopied species, which do not exclude the herbaceous component, but often change species composition under the canopy relative to surrounding open areas. These effects are often differential based on productivity of the site and herbaceous species composition of the grassland. Here we investigated landscape-scale changes in the herbaceous composition resulting from changes in canopy cover of honey mesquite (Prosopis glandulosa) within woody-encroached areas of Texas, U.S.A. Mesquite canopy percent changes were determined from aerial photographs and related to field-based measurements of the herbaceous component. We then related our findings to similar studies in the literature within different environments to assess similarities and differences among the impacts on the herbaceous component across a range of conditions. We utilized herbaceous layer functional groups to make these comparisons across different sites. Finally, we evaluated these changes in herbaceous composition to rates of woody encroachment to assess temporal changes across the landscape and possible impacts from restoration. We found that changes in the herbaceous layer were dependent on length of time of woody encroachment, percent woody cover, and site productivity

Periodicity of mass extinctions without an extraterrestrial cause

We study a lattice model of a multi-species prey-predator system. Numerical results show that for a small mutation rate the model develops irregular long-period oscillatory behavior with sizeable changes in a number of species. The periodicity of extinctions on Earth was suggested by Raup and Sepkoski but so far is lacking a satisfactory explanation. Our model indicates that this is a natural consequence of the ecosystem dynamics, not the result of any extraterrestrial cause.Comment: 4 pages, accepted in Phys.Rev.

Analytical and experimental investigation of gas bearing tilting pad pivots Final report

Fretting damage in gas bearing tilting pad pivot