Collapse of large vapor bubbles

The refilling of propellant tanks while in a low-gravity environment requires that entrapped vapor bubbles be collapsed by increasing the system pressure. Tests were performed to verify the mechanism of collapse for these large vapor bubbles with the thermodynamic conditions, geometry, and boundary conditions being those applicable to propellant storage systems. For these conditions it was found that conduction heat transfer determined the collapse rate, with the specific bubble geometry having a significant influence

Reviewing critical pedagogy\u27s criticisms and providing a pragmatic heuristic

This article reviews scholarly literature about problems in critical pedagogy, pragmatic examples of implementing critical pedagogy, professional learning communities, and critical pedagogy-based curricula in new media toward proposing part of a broad solution to some of critical pedagogy\u27s criticisms in reaching out to educators: the use of a heuristic that critical pedagogues could use to determine the accessibility in tone of curricula that they could reference to colleagues whom may not know about or otherwise avoid critical pedagogy. Under this initiative, a heuristic is developed based on a review of literature defining and characterizing critical pedagogy. This heuristic is then applied in a study of three critical pedagogy-based unit plans. The results confirm the validity of the heuristic, but the results also cast doubt on the range of its use. A positive correlation about the rate of use of keywords with positive- and negative-connotations cross­ sectioned with unit grade level suggests that the usage rate of such keywords in critical curricula declines as curricula targets earlier grade levels. This positive correlation presents a case for why this research is valuable, and it also creates a compelling case for further research --Leaf iv

Effects of Flow Augmentation on Channel Morphology and Riparian Vegetation in the Upper Arkansas River Basin, Colorado

This study examined historic change of riparian plant communities and fluvial geomorphic response of gravel-bedded streams and their floodplains to over 50 years of hydrologic disturbance. Four tributary basins of the Arkansas River were analyzed. Lake Creek, Clear Creek, and Cottonwood Creek are drainages similar in area, physiography, and vegetation composition. However, Lake Creek may receive an instantaneous discharge of approximately 28 m3sec-1 from the Twin Lakes tunnel, over three times the normal flow of the stream during spring runoff. By contrast, Clear Creek and Cottonwood Creek, nonaugmented streams, were used as controls to compare the historic and present condition of natural flowing streams with Lake Creek. Lake Fork was also examined, another augmented stream that carries transmountain water stored in a reservoir to the Upper Arkansas River. Hydrologic data collected from U.S.G.S. gaging stations were used in an attempt to identify relations between specific flow events and corresponding changes in fluvial landforms, riparian vegetation patterns, and channel morphology. Topographic cross sections of the channel and floodplain were surveyed and hydraulic geometry at each field site was examined. Aerial photographs from 1938-39, 1956-57 , and 1988 were incorporated into a Geographic Information System (GIS) to prepare a series of land cover maps of the river corridor at eight field sites on augmented and nonaugmented streams. Results indicate channel morphology and riparian vegetation cover on the active floodplains of Lake Creek and Lake Fork have experienced substantial change from natural physical and biologic conditions as a result of historic and present flow augmentation practices. The increase in water discharge without a natural sediment load in Lake Creek and Lake Fork appears to have caused accelerated rates of channel bank erosion, incision, and bank retreat below transbasin diversion releases. In some downstream reaches characterized by gentler slopes and wider valley bottoms, the width-depth ratio of the channel has increased and sinuosity has decreased. Sites carrying transmountain water were characterized by higher shear stress and specific stream power values and larger bed material compared to control sites. Consequently, the Lake Creek and Lake Fork drainages show temporal and spatial loss of riparian vegetation adjacent to the stream channel in response to historic and present flow augmentation practices. Control watersheds, Clear Creek and Cottonwood Creek, where natural flow regimes exist, did not experience similar magnitudes of change in channel morphology or spatial distribution of riparian vegetation

UNITED STATES-LATIN AMERICAN TRADE RELATIONS: IMPORTANCE TO U.S. AGRICULTURAL POLICY DECISIONS

International Relations/Trade,

“This Is Public Health: Recycling Counts!” Description of a Pilot Health Communications Campaign

This paper describes the development, implementation, and evaluation of a pilot recycling campaign. The goal of the campaign was to increase people’s awareness and knowledge about recycling and the link between a healthy environment and the public’s health. A total of 258 individuals attended campaign week events and completed an initial survey. Results identified inconvenience of recycling facility locations as a key barrier to recycling. Post-campaign survey results revealed increased recycling of paper, plastic, glass, and cans (p < 0.05). The majority of participants “agreed” or “strongly agreed” that as a result of campaign messages they had greater awareness about recycling (88.4%) and their recycling efforts increased (61.6%)

El perfil de las revistas españolas de comunicación (2007-2008)

La evolución de los parámetros de publicación científi ca y de las exigencias de la carrera académica en España ha provocado cambios en las revistas científi cas y, entre ellas, las de comunicación. Este artículo caracteriza las revistas nucleares españolas en el ámbito de la comunicación a través de variables como el volumen de artículos publicados, el idioma empleado, la procedencia y las redes de colaboración de sus autores o los patrones de citación en el período 2007-2008. Mediante técnicas bibliométricas y el análisis de redes sociales se obtiene un perfi l que muestra las similitudes y las diferencias entre las diferentes revistas y el perfi l del conjunto del sistema.The evolution of parameters for scholarly publications and of academic requirements in Spain has resulted in changes to scholarly journals, among others, those in the fi eld of communication sciences. This article characterizes the core Spanish communication journals according to variables such as the number of published articles, language, author institution and collaboration networks, and citation patterns during 2007-2008. By applying bibliometric techniques and social network analysis, a profile showing similarities and differences among the journals is obtained, as well as a profile of the overall system

Fluid Acquisition and Resupply Experiments on Space Shuttle Flights STS-53 and STS-57

The Fluid Acquisition and Resupply Experiment (FARE) program, managed by the Marshall Space Flight Center Space Propulsion Branch with Martin Marietta Civil Space and Communications as the contractor, consisted of two flights designated FARE I and FARE II. FARE I flew in December 1992 on STS-53 with a screen channel liquid acquisition device (LAD) and FARE II flew in June 1993 on STS-57 with a vane-type LAD. Thus, the FARE I and II flights represent the two basic LAD categories usually considered for in-space fluid management. Although both LAD types have been used extensively, the usefulness of the on-orbit data has been constrained by the lack of experimentation beyond predicted performance limits, including both propellant fill and expulsion. Therefore, the FARE tests were designed to obtain data that would satisfy two primary objectives: (1) Demonstrate the performance of the two types of LADs, screen channel and vane, and (2) support the anchoring of analytical models. Both flights were considered highly successful in meeting these two primary objectives