Lunar surface engineering properties experiment definition Quarterly report, 1 Oct. - 31 Dec. 1968

Mechanical properties of simulated lunar soil

After-School Connectedness, Racial–Ethnic Identity, Affirmation, and Problem Behaviors

After-school programs are potential contexts that may promote positive youth development (PYD) and reduce problem behaviors among African American children. One way after-school programs may be associated with reduced problem behaviors is by fostering an affirming sense of identity. Prior research on racial–ethnic identity among African American children and adolescents has shown that a positive and affirming sense of identity is related to less maladaptive coping, yet little is known about how after-school programs may foster an affirming sense of identity and lead to reduced problem behaviors. The current study adds to this discourse by investigating how children’s connection to staff and peers in after-school settings is associated with racial–ethnic identity (as measured by racial–ethnic affirmation) and reduced problem behaviors. Participants were 186 African American children ages 7–11 (M = 8.44; SD = 1.10) who completed surveys in the LEGACY Together Afterschool research project. Data were collected at 55 community-based after-school programs. Results indicated that positive racial–ethnic affirmation mediated the association between after-school connectedness and problem behaviors, such that childreport of connectedness—that is feeling safe and happy in the after-school programs—was directly related to positive racial–ethnic identity and indirectly to reduced problem behaviors. These findings underscore the importance of supportive after-school programs that encourage meaningful interactions among staff and children that are nurturing and affirming to children’s identities

Material studies related to lunar surface exploration Technical summary report, 6 Mar. 1967 - 30 Jun. 1968

Summary of research studies on lunar surface material propertie

Material studies related to lunar surface exploration, volume 3 Final report, 6 Mar. 1967 - 30 Jun. 1968

Mechanical properties of lunar soils related to lunar exploratio

Material studies related to lunar surface exploration. Volume 4 - Preliminary studies for the design of engineering probes Final report, 6 Mar. 1967 - 30 Jun. 1968

Preliminary design of engineering probes for studying lunar surface material propertie

Material studies related to lunar surface exploration. Volume 2 - Application of geophysical and geotechnical methods to lunar sites exploration Final report, 6 Mar. 1967 - 30 Jun. 1968

Geophysical and geotechnical methods for lunar landing site soil property studie

Material studies related to lunar surface exploration. Volume 1 - Lunar soil mechanics and soil properties Final report, 6 Mar. 1967 - 30 Jun. 1968

Lunar soil mechanics and properties for structural engineering aspects of lunar spacecraft landings and surface exploratio

Field determination of the hydraulic properties of leaky multiple aquifer systems

Abstract. A new field method is proposed for determining the hydraulic properties of aquifers and aquitards in leaky systems. Conventional methods of analyzing leaky aquifers usually rely on drawdown data from the pumped aquifer alone. Such an approach is not sufficient to characterize a leaky system; our new method requires observation wells to be placed not only in the aquifer being pumped but also in the confining layers (aquitards) above and/or below. The ratio of the drawdown in the aquitard to that measured in the aquifer a t the same time and the same radial distance from the pumping well can be used to evaluate the hydraulic properties of the aquitard. The new method is supported by theory and has been applied to the coastal groundwater basin of Oxnard, California. The field results are in good agreement with laboratory measurements. Traditionally, groundwater hydrologists have tended to focus their attention on the more permeable aquifer layers of a groundwater basin in developing water supplies. However, sedimentary groundwater basins usually consist of a series of aquifers separated by confining layers of relatively low permeability, which may act as conduits for the vertical migration of water from one aquifer to another. Since finegrained sediments often tend to be much more compressible than associated coarse-grained aquifer materials, they also can release large quantities of water from storage and thereby increase t,he supply. available t o the aquifer. The combined effects of these phenomena are known as leakage. Usually, when the effects of leakage can be detected by observing drawdown in the aquifer being pumped, the confining beds are called 'aquitards,' and the aquifer is referred t o as being 'leaky.' When such effects cannot be easily detected in the aquifer, the confining beds are called 'aquicludes,' and the aquifer is termed 'slightly leaky' [Neuman and Witherspoon, 19681. Aquitards play an important role in the hydrology of multiple aquifer systems, and we shall mention here only a few examples. Although groundwater recharge is often believed to occur in areas of aquifer outcrops, Gill [I9691 has recently reported that substantial amounts of water produced from the Potomac-RaritanMagothy aquifer system are coming through the aquitards. Earlier, Wdton [I9651 had shown how the Maquoketa formation in Illinois, which is essentially a shale bed, serves as an effective transmitter of water between aquifers. Land subsidence in the San Joaquin Valley and other areas in California has been shown to be associated with water withdrawal from multiple aquifer systems and is generally attributed to the resulting compaction of fine-grained aquitard sediments [Poland and Davis, 19691. Similar situations exist in Venice, Japan, and other parts of the world. For the past 20 years, aquifers at depths below 500 feet have been used for storing natural gas in the United States and Europe. Where the properties of the aquitards were not properly investigated, the gas industry has on occasion witnessed the spectacular and dangerous effects of gas leakage. The storage of other fluids