Fabrication of Textured Silicon Carbide via Seeded Anisotropic Grain Growth

Highly textured silicon carbide was fabricated via anisotropic grain growth. Large, platelike grains were grown from a fine-grained sintered matrix which had been seeded with ≤2% SiC platelets. The seeds were initially incorporated with preferred orientation during the green-state forming process and this resulted in oriented growth of the platelike grains. The development of texture in the samples was evident from microstructure observations and X-ray diffraction analysis.     

Scrapie prions selectively modify the stress response in neuroblastoma cells

The fundamental event underlying scrapie infection seems to be a conformational change in the prion protein. To investigate proteins that might feature in the conversion of the cellular prion protein (PrPC) into the scrapie isoform (PrPSc), we examined mouse neuroblastoma N2a cells for the expression and cellular distribution of heat shock proteins (Hsps), some of which function as molecular chaperones. In scrapie-infected N2a (ScN2a) cells, Hsp72 and Hsp28 were not induced by heat shock, sodium arsenite, or an amino acid analog, in contrast to uninfected control N2a cells, while other inducible Hsps were increased by these treatments. Following heat shock of the N2a cells, constitutively expressed Hsp73 was translocated from the cytoplasm into the nucleus and nucleolus. In contrast, the distribution of Hsp73 in ScN2a cells was not altered by heat shock; the discrete cytoplasmic structures containing Hsp73 were largely resistant to detergent extraction. These alterations in the expression and subcellular translocation of specific Hsps in ScN2a cells may reflect the cellular response to the accumulation of PrPSc. Whether any of these Hsps feature in the conversion of PrPC into PrPSc or the pathogenesis of prion diseases remains to be established.     

Material properties testing using high explosives

The Defense Nuclear Agency has conducted several high explosive (HE) phenomenology tests in the past five years, using explosive weights at or below 1000 pounds, to improve the capability of computer codes to predict weapon effects. One of the interesting results of this series of tests is the major improvement in determining material properties of the concrete, soil, or sand in the testbed. This has permitted a more accurate definition of the equation-of-state (EOS) for the material in question, and thus, improved modeling capabilities over a broader range of weapon effects.     

Likelihood-Based Data Squashing: A Modeling Approach to Instance Construction

Squashing is a lossy data compression technique that preserves statistical information. Specifically, squashing compresses a massive dataset to a much smaller one so that outputs from statistical analyses carried out on the smaller (squashed) dataset reproduce outputs from the same statistical analyses carried out on the original dataset. Likelihood-based data squashing (LDS) differs from a previously published squashing algorithm insofar as it uses a statistical model to squash the data. The results show that LDS provides excellent squashing performance even when the target statistical analysis departs from the model used to squash the data.     

Performance study of a heat pump dryer system for specialty crops—Part 1: Development of a simulation model

This research is concerned with the technology of heat pump assisted drying of specialty crops. A simplified procedure for modelling the performance of a low temperature heat pump dryer was developed. The system modelled consists of a vapour compression heat pump coupled to a continuous cross flow bed dryer. The model takes into account the detailed heat and mass transfer phenomena taking place in the heat pump and dryer circuits. Copyright © 2002 John Wiley & Sons, Ltd.     

Maternal attachment representations, maternal sensitivity, and the infant–mother attachment relationship.

The role of maternal sensitivity as a mediator accounting for the robust association between maternal attachment representations and the quality of the infant-mother attachment relationship was examined. Sixty mother-infant dyads were observed at home and in the Strange Situation at 13 months, and mothers participated in the Adult Attachment Interview (AAI) within the next 6 months. A strong association was found between AAI and Strange Situation classifications. and autonomous mothers were more sensitive at home than were nonautonomous mothers. Mothers in secure relationships were more sensitive at home than mothers in nonsecure relationships. Likewise, infants in secure relationships were more secure as assessed by the Waters' Attachment Q sort than infants in nonsecure relationships. A test of the mediational model revealed that maternal sensitivity accounted for 17% of the relation between AAI and Strange Situation classifications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Expression of ribozymes in gene transfer systems to modulate target RNA levels

The possibility of designing ribozymes to cleave any specific target RNA has rendered them valuable tools in both basic research and therapeutic applications. In the therapeutics area, they have been exploited to target viral RNAs in infectious diseases, dominant oncogenes in cancers and specific somatic mutations in genetic disorders. Most notably, several ribozyme gene therapy protocols for HIV patients are already in Phase 1 trials. More recently, ribozymes have been used for transgenic animal research, gene target validation and pathway elucidation.     

ASTER preflight and inflight calibration and the validation ofLevel 2 products

Describes the preflight and inflight calibration approaches used for the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). The system is a multispectral, high-spatial resolution sensor on the Earth Observing System's EOS-AM1 platform. Preflight calibration of ASTER uses well-characterized sources to provide calibration and preflight round-robin exercises to understand biases between the calibration sources of ASTER and other EOS sensors. These round-robins rely on well-characterized, ultra-stable radiometers. An experiment field in Yokohama, Japan, showed that the output from the source used for the visible and near-infrared (VNIR) subsystem of ASTER may be underestimated by 1.5%, but this is still within the 4% specification for the absolute, radiometric calibration of these bands. Inflight calibration will rely on vicarious techniques and onboard blackbodies and lamps. Vicarious techniques include ground-reference methods using desert and water sites. A recent joint field campaign gives confidence that these methods currently provide absolute calibration to better than 5%, and indications are that uncertainties less than the required 4% should be achievable at launch. The EOS-AM1 platform will also provide a spacecraft maneuver that will allow ASTER to see the Moon, allowing further characterization of the sensor. A method for combining the results of these independent calibration results is presented. The paper also describes the plans for validating the Level 2 data products from ASTER. These plans rely heavily upon field campaigns using methods similar to those used for the ground-reference, vicarious calibration methods     

Drift leakage current in AlGaInP quantum-well lasers

The temperature dependence of threshold current and quantum efficiency for Ga_xIn_1-xP (x=0.4, 0.6; λ=680, 633 nm) single 80-Å quantum-well lasers is compared and analyzed using a model for the electron leakage current. This model fits the experimental data well, correctly describing the rapid increase in threshold and drop in quantum efficiency as temperature increases. Also, it indicates that the drift (rather than diffusion) component of the electron leakage current, is dominant, because of the poor p-type conductivity in AlGaInP