Proactive interference and the dynamics of free recall.

Proactive interference (PI) has long been recognized as a major cause of forgetting. Two experiments were conducted that offer another look at the subject by providing a detailed analysis of recall latency distributions during the buildup of and release from PI. These functions were accurately characterized by the convolution of the normal and exponential distributions (viz., the ex-Gaussian), which previously has been shown to describe recognition latency distributions. Further, the fits revealed that the increase in recall latency associated with the buildup of PI results from a slowing of the exponential retrieval stage only. The same result was found even when a short retention interval was used (and recall probability remained constant). These findings suggest that free-recall latency may be a sensitive index of the increased search set size that has often been assumed to accompany the buildup of PI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition and Importance of Restrictions on Randomization in Industrial Experimentation

Statisticians typically recommend completely randomized experimental designs. The reasoning behind this advice is theoretically sound. Unfortunately, engineers who typically run industrial experiments frequently fail to recognize restrictions on randomization, i.e., split-plot experiments, and are often unaware of the risks associated with analyzing split-plot experiments as if they were randomized. Similarly, issues concerning the inference space of the experiment frequently are not given adequate consideration. Conversely, statisticians frequently are unaware that a restriction on randomization does not necessarily translate into less information than a completely randomized design.

In this paper, we discuss a proactive methodology for identifying and incorporating information concerning restrictions on randomization and inference space in industrial experiments. We also present the factor relationship diagram (FRD), a tool that assists engineers in the recognition of restrictions of randomization and guides the development of questions that encourage the experimenter to understand those sources of variation that may contribute to a lack of precision in a split-plot experiment or lack of repeatability in inference space different from that studied in the experiment. Examples that illustrate the use of the methodology and the FRD are included.     

Computer analysis of a polymer coating exposed to field weather conditions

A heat and moisture transfer model was used to study weathering of polymeric materials, such as paint, asphalt, sealants, plastics, textiles, and polymeric composites. Three damage indices, related to temperature changes, humidity changes, and time of wetness, respectively, were introduced to quantify adverse effects of climate. The variation of these indices was investigated for a hot and humid climate (Miami, FL) and a hot and dry climate (Phoenix, AZ). In addition, the relative effects of solar radiation, surface wetting by rain and dew condensation, and variations in outdoor temperature and relative humidity on the three damage indices were investigated. 100 Bureau Dr., Stop 8621, Gaithersburg, MD 20899-8621.     

Monodisperse ellipsoidal polystyrene latex particles: Preparation and characterisation

An improved version of a novel method first employed by Nagy & Keller for the preparation of monodisperse ellipsoidal polystyrene latex particles is described. The method involves embedding monodisperse spherical polystyrene latex particles as starting material in a deformable polymer matrix such as poly(vinyl alcohol) and deforming these mechanically to various predetermined macroscopic draw ratios to give ellipsoids of various axial ratios. Ellipsoids with lengths ranging from about 350 to 12250nm were prepared. Stable aqueous dispersions of these were recovered and characterised with respect to particle size and axial ratio distributions and surface morphology using electron microscopy. Axial ratios ranging from 2.0 to 5.65 were obtained for the resulting ellipsoids. Various factors influencing the monodispersity of the resulting ellipsoids in the preparation method are discussed.     

Deformation behavior of an S-B-S copolymer

In accordance with previous studies, ‘single crystal’ tyr samples were prepared from the polystyrene-polybutadien- polystyrene (S-B-S) three block copolymer Kraton 102 consist ing of a hexagonally packed parallel array of glassy S cylinder within a rubbery B matrix. Following earlier investigations o the pronounced anisotropy of the modulus, the actual deformation mechanism is examined in terms of the microstructures on straining perpendicular and parallel to the cylinder direction up to and beyond yielding. On perpendicular straining, a one to-one relation is observed between ‘lattice’ and sample stray up to about 10 percent, coupled with complete recovery. For higher strains, the deformation becomes increasingly irreversible dependent on the time of stressing, a behavior which is found to be caused by cracks forming along crys tallographically defined directions of the hexagonal macrolai tice. On parallel straining, the stress-strain curves display yield behavior at ～3 percent strain, the yielded material be coming more compliant even at small strains on repeated test ing. However, on storage, the sample rehardens, a proces accelerated by heat treatment. This behavior is explained in terms of a breaking up and reformation of the cylinders and is supported by the subsequent experiments. These includ measurement of birefringence, which in the reversible small strain region corresponds to expectations from uniform strain in both S and B phases, but which beyond the yielded region displays behavior such as expected from deformation of the B phase alone. The postulated break-up of cylinders on yielding is directly confirmed by electron microscopy on Iongitudinal sections thin enough to contain a single layer of cylinders. The yield behavior itself is treated theoretically using the composite mechanics approach. Two treatments are applied, the trad itional shear lag theory and a new random rod breaking theory In the latter case, in particular, very good agreement with experiment is found in that both the observed stress to yield and the electronmicroscopically seen fractured rod length in the yielded product are predicted.     

Effect of intraclass correlation among training samples on the misclassification probabilities of bayes procedure

The sample mean and sample covariance matrix are unbiased and consistent estimates of population mean and covariance matrix only if the samples are independent. In practical applications of Bayes' procedure these estimates are used in place of population means and covariance matrices on the assumption of independence among the training samples. This practice has often given, especially in remote sensing data analysis, misclassification probabilities much higher than that can be accounted for theoretically. The reason may be that the assumption of independence may not be valid. In reality, the samples are rarely independent, they are rather dependent, at best equicorrelated. This paper investigates how such intraclass correlation among the training samples affects the misclassification probabilities of the Bayes' procedure.     

The phase diagram of the system PBZT/ polyphosphoric acid/water

The phase diagram of the system PBZT/polyphosphoric acid/water has been investigated using differential scanning calorimetry, optical microscopy and ³¹P nuclear magnetic resonance spectroscopy. A peritectic line at higher temperatures and a eutectic line at lower temperatures have been found independent from the polycondensation degree of the polyphosphoric acid (PPA). The phase transitions between the different regions in the phase diagram are strongly dependent on the condensation degree of the solvent. All phase transitions are completely reversible. The formation of crystal solvate phases is connected with the water content of the system and therefore with the polycondensation reaction of the PPA. The solvent molecules are strongly associated with the macromolecules. The nematic phase is formed by interaction of six solvent molecules per monomeric unit of the polymer and proton transfer from the solvent towards the polymer in the nematic phase.