Some Approximations for the Noncentral-F Distribution

Among the various approximations for the noncentral-F distribution. the best known are the computationally simpler approximation due to Severo and Zelen [18] and Laubscher [9], which requires only the normal distribution, and a more accurate approximation due to Tiku [21], which requires the F distribution. Thcsr approximations are systematically evaluated. Some variations of these approximations are considered and found to he of comparable accuracy. An Edgeworth-acries approximation, which requires only the normal distribution, is developed and sren to be superior in accuracy. A FORTRAN-subroutine for the Edgeworth-series approximation is given.     

Optimization strategies on the structural modeling of gelatin/chitosan scaffolds to mimic human meniscus tissue

Meniscus lesions are frequently occurring injuries with poor ability to heal. Typical treatment procedure includes removal of damaged regions, which can lead to sub-optimal knee biomechanics and early onset of osteoarthritis. Some of the drawbacks of current treatment approach present an opportunity for a tissue engineering solution. In this study, gelatin (G)/chitosan (Cs) scaffolds were synthesized via gel casting method and cross-linked with naturally derived cross-linker, genipin, through scaffold cross-linking method. Based on the characteristics of native meniscus tissue microstructure and function, three different layers were chosen to design the macroporous multilayered scaffolds. The multi-layered scaffolds were investigated for their ability to support human-derived meniscus cells by evaluating their morphology and proliferation using MTT assay at various time points. Based on structural, mechanical and cell compatibility considerations, laminated scaffolds composed of G60/Cs40, G80/Cs20 and G40/Cs60 samples, for the first, second and third layers, respectively, could be an appropriate combination for meniscus tissue engineering applications.     

International standards for the acquisition and presentation of comparable data on plastics

One of the problems faced by plastics design engineers, in addition to anyone involved in resin selection in new product development, is access to comparable data among similar products from different material suppliers. This stems from the lack of standardization in the acquisition and reporting format for materials properties data in the plastics industry. Currently, a multiplicity of national test standards is widely used in the acquisition of the data, which often allows a broad flexibility in the choice of test specimen shapes and geometry, conditions for preparing the test specimens, test variables, and test conditions, in addition to units, rendering any comparison between materials extremely difficult. ISO 10350 and 11403, Parts 1, 2, and 3, were developed specifically to address these issues for the acquisition of the data, and the CAMPUS database was developed as a tool for standardization of the reporting format for plastics properties. The real driving force for standardization at the international level is the growing need for comparable data on a global basis because of the emerging global nature of the manufacturing industry and the cost savings. This paper will discuss the rationale, driving forces, and the status of the worldwide standardization efforts, along with the benefits and experience gained to date.     

Multifrequency sounding results of laboratory simulated homogeneousand two-layer Earth models

Scale model studies have established that layered Earth structures can be resolved by central frequency sounding (CFS) through a combination of parametric and geometric approaches. In view of the utility of scale model studies, which often improve the approach towards interpretation of field data, experimental work was carried out for CFS and compared with dipole frequency sounding (DFS) to establish the resolution pattern of CFS on laboratory simulated models. Results presented for homogeneous and two-layer Earth models for the conductive substratum agree well with the actual parameter values of the models     

Airflow Management in a Contained Cold Aisle Using Active Fan Tiles for Energy Efficient Data-Center Operation

Generally, passive perforated tiles are used in a data center and the supplied airflow rate is underprovisioned; thus, the balance of the server air requirement is met by the hot air in the room, resulting in higher server inlet temperatures. Full provisioning of the supplied airflow rate and containing the cold aisle is expected to minimize the hot air leakage in the cold aisle, resulting in uniform and lower server inlet temperatures. Thus, the supply air temperature can be raised, resulting in energy savings at the chiller plant. Supplying extra air can be achieved using active perforated tiles, having multiple fans installed on them. In this paper, the underprovisioned case using passive tiles and the fully provisioned case using active tiles are investigated for both open and contained aisle conditions. Thermal field measurements suggest lower and uniform server inlet temperatures for the case with contained aisle as compared to open aisle and for the fully provisioned case using active tiles as compared to the underprovisioned case using passive tiles. System-level energy calculations suggests that containing the cold aisle results in lower (improved) power usage effectiveness (PUE); however, use of active tiles does not seem to improve the PUE.     

Component structure of individual differences in true and false recognition of faces.

Principal-component analyses of 4 face-recognition studies uncovered 2 independent components. The first component was strongly related to false-alarm errors with new faces as well as to facial “conjunctions” that recombine features of previously studied faces. The second component was strongly related to hits as well as to the conjunction/new difference in false-alarm errors. The pattern of loadings on both components was impressively invariant across the experiments, which differed in age range of participants, stimulus set, list length, facial orientation, and the presence versus absence of familiarized lures along with conjunction and entirely new lures in the recognition test. Taken together, the findings show that neither component was exclusively related to discrimination, criterion, configural processing, featural processing, context recollection, or familiarity. Rather, the data are consistent with a neuropsychological model that distinguishes frontal and occipitotemporal contributions to face recognition memory. Within the framework of the model, findings showed that frontal and occipitotemporal contributions are discernible from the pattern of individual differences in behavioral performance among healthy young adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ζ-potential characterization of collagen and bovine serum albumin modified silica nanoparticles: a comparative study

In this study, bovine serum albumin (BSA) and collagen (COLL) were adsorbed independent of one another, onto the surface of silica nanoparticles (SNPs) at pH’s where the ζ-potential of the proteins were equal in magnitude, but opposite to the SNP surface to ascertain the differences in surface coverage and conformation in the adsorbed layer. In both systems, increasing the concentration of free protein resulted in an increase in protein surface coverage and ζ values, with ζ values approaching that of native protein at high surface coverage. However, a lower critical charge reversal concentration range was measured for COLL relative to BSA (COLL: 0–25 μg/mL, BSA: 25–90 μg/mL). Additionally, a considerable difference in ζ for adsorbed protein versus free protein was observed. These results when interpreted in terms of the theory of Ottewill and Watanabe indicate a higher Gibbs energy of association for COLL versus BSA on SNP surfaces, accompanied by perturbation in protein structure.     

Experimental study of the frictional properties of friction spun yarns

This article reports the results from a study conducted to characterize the frictional properties of friction spun yarns. The aim of the study was to obtain data on the surface mechanical properties of a variety of friction spun yarns. The study was essential as the surface mechanical properties influence the fabric formation, bonding strength, and high‐performance properties of yarns. The yarns used in the study were made from different fibers and were spun at different speeds. The capstan method was used to obtain the friction force values between the yarns and a glass cylindrical rod. The experiment was conducted at different tensions. The results indicate that the friction of friction spun yarns are influenced by different factors such as the type of fiber and tensions applied. The results obtained help to understand the surface mechanical properties of high‐performance yarns and their influence on the performance characteristics of friction spun yarns. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2450–2454, 2003