In-space experiment on thermoacoustic convection heat transfer phenomenon-experiment definition

The definition phase of an in-space experiment in thermoacoustic convection (TAC) heat transfer phenomenon is completed and the results are presented and discussed in some detail. Background information, application and potential importance of TAC in heat transfer processes are discussed with particular focus on application in cryogenic fluid handling and storage in microgravity space environment. Also included are the discussion on TAC space experiment objectives, results of ground support experiments, hardware information, and technical specifications and drawings. The future plans and a schedule for the development of experiment hardware (Phase 1) and flight tests and post-flight analysis (Phase 3/4) are also presented. The specific experimental objectives are rapid heating of a compressible fluid and the measurement of the fluid temperature and pressure and the recording and analysis of the experimental data for the establishment of the importance of TAC heat transfer process. The ground experiments that were completed in support of the experiment definition included fluid temperature measurement by a modified shadowgraph method, surface temperature measurements by thermocouples, and fluid pressure measurements by strain-gage pressure transducers. These experiments verified the feasibility of the TAC in-space experiment, established the relevance and accuracy of the experimental results, and specified the nature of the analysis which will be carried out in the post-flight phase of the report

Landscape response to Pleistocene-Holocene precipitation change in the Western Cordillera, Peru: 10Be concentrations in modern sediments and terrace fills

The landscape response to climate change is frequently investigated with models because natural experiments on geologic timescales are rare. In Quebrada Veladera, in the western Andes Mountains, the formation of alluvial terraces during periods of high precipitation presents opportunities for such an experiment. We compare drainage-average erosion rates during Pleistocene terrace deposition with Holocene rates, using cosmogenic 10Be samples for seven pairs of quartz sand taken from the trunk and tributaries of Quebrada Veladera and adjacent terraces. Each pair consists of sediment collected from the modern channel and excavated from an adjacent fill terrace. The terrace fill was deposited at ~16 ka and preserved an isotopic record of paleoerosion rates in the Late Pleistocene. Modern sands yield 10Be concentrations between 1.68 × 105 and 2.28 × 105 atoms/g, corresponding to Holocene erosion rates between 43 ± 3 and 58 ± 4 mm/kyr. The 10Be concentrations in terrace sands range from 9.46 × 104 to 3.73 × 105 atoms/g, corresponding to paleoerosion rates from 27 ± 2 to 103 ± 8 mm/kyr. Smaller, upstream tributaries show a substantial decline in erosion rate following the transition from a wet to dry climate, but larger drainage areas show no change. We interpret this trend to indicate that the wetter climate drove landscape dissection, which ceased with the return to dry conditions. As channel heads propagated upslope, erosion accelerated in low-order drainages before higher-order ones. This contrast disappeared when the drainage network ceased to expand; at that point, erosion rates became spatially uniform, consistent with the uniformity of modern hillslope gradients. Key Points Landscape response to climate change evaluated with 10Be erosion rates Wetter climate associated with rapid erosion in smaller, upstream drainages Drier, Holocene climate associated with spatially uniform erosion rates ©2013. American Geophysical Union. All Rights Reserved

The Effects of Children's Time Use and Home and Neighborhood Quality on their Body Weight and Cognitive/Behavioral Development

We estimate a directional distance function to assess the impacts of multiple time-varying parent and child inputs on a cluster of jointly produced child outcomes for children aged 7 to 13 years. The directional distance function specification avoids several well-known empirical problems associated with analysis of household production data, namely, the need to aggregate inputs and outputs, assume separability among inputs and outputs, or estimate reduced form equations. Using a balanced panel of families from the National Longitudinal Survey of Youth-Child Sample for 1996 to 2000, we assess the marginal contributions of home and neighborhood environmental quality and children's time allocations, on their math and reading performance, behavior problems, and body mass index. We also measure productivity growth, technical change, efficiency change, and technical efficiency for production of child outcomes. Our results indicate significant jointness among good and bad child outcomes. Significant improvements in children's good outcomes and reductions in bad outcomes are also associated with a better home and parent perceived neighborhood environment, Head Start participation, and increased family time spent together during meals. Children's productivity growth is found to be highest at age 8 years and diminishes thereafter.Health Economics and Policy, Labor and Human Capital,

Search for synchrotron emission from secondary leptons in dense cold starless cores

We report radio continuum observations with the Australia Telescope Compact Array of two molecular clouds. The impetus for these observations is a search for synchrotron radiation by cosmic ray secondary electrons/positrons in a region of enhanced density and possibly high magnetic field. We present modelling which shows that there should be an appreciable flux of synchrotron above the more diffuse, galactic synchrotron background. The starless core G333.125-0.562 and infrared source IRAS 15596-5301 were observed at 1384 and 2368 MHz. For G333.125-0.562, we find no significant levels of radio emission from this source at either frequency, nor any appreciable polarisation: we place an upper limit on the radio continuum flux from this source of 0.5 mJy per beam at both 1384 and 2368 MHz. Due to the higher than expected flux density limits, we also obtained archival ATCA data at 8640 MHz for this cloud and place an upper limit on the flux density of 50 micro-Jy per beam. Assuming the cosmic ray spectrum is similar to that near the Sun, and given the cloud's molecular density and mass, we place an upper limit on the magnetic field of 500 micro-G. IRAS 15596-5301, with an RMS of 50 micro-Jy per beam at 1384 MHz, shows an HII region consistent with optically thin free-free emission already detected at 4800 MHz. We use the same prescription as G333 to constrain the magnetic field from this cloud to be less than 500 micro-G. We find that these values are not inconsistent with the view that magnetic field values scale with the average density of the molecular cloud.Comment: 6 pages, 5 pdf figures, accepted for publication in PAS

Blended learning: A new approach to legal teaching in South African law schools

This article investigates the development of a sustainable strategy for the integration of online education technology and traditional teaching and learning methodologies in South African law faculties, in a so-called ‘blended learning’ approach to legal teaching. In developing a strategy, a number of issues were considered, including: accommodating an increasing and diverse student population; achieving SAQA exit-level outcomes; national and international trends in blended learning; and ensuring an appropriate level of computer skills for both lecturers and students. Vital to the development of a sustainable strategy is a comprehensive management plan which details clear objectives for the process of implementation.The achievement of the management plan objectives should be driven by a project management team, which will be responsible for conducting training and support in blended learning; developing online learning module materials; producing research into technological advancements in this field; co-operating with the law library; establishing a committed blended learning community; and finally establishing a system of blended learning module review.The overall objective of the strategy then, is to establish a sustainable model for the medium and long-term implementation of blended learning, ensuring that this mode of learning becomes accepted as an integral part of the system of legal education in the institution