Role of specific instances in controlling a dynamic system.

This article examines the claim that the learning of a dynamic control task is mediated by a lookup table consisting of previously successful trials on the task. Consistent with the predictions of a lookup table, in 2 experiments participants tended to give the same response to situations in which they had previously been successful rather than unsuccessful. Further, in both experiments, participants' knowledge did not generalize to new dissimilar situations, unless the dynamic control task was governed by a highly salient rule. A version of G. Logan's (1988) instance theory, which assumes that participants store each successful response as a separate instance linking the situation to the response, was able to quantitatively match a range of measures of participants' performance with 1 free parameter, except in the case in which the control task was governed by a salient rule. In a complementary way, an alternative rule-based model could only match participants' performance when the control task was governed by a highly salient rule. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ON‐LINE MONITORING OF POLLUTION CONCENTRATIONS WITH AUTOREGRESSIVE MOVING AVERAGE TIME SERIES

The concentration of aerosol particles, largely caused by traffic volume and often enhanced during temperature inversion episodes in the cold season, can be a concern for human health in the urban environment. This particulate matter is typically recorded as PM₁₀, the total mass of particles below 10 μm in diameter. It is suspected that, within the PM₁₀ class, ultrafine particles ( < 100 nm) may be responsible for causing respiratory and cardiovascular diseases. Because of their low mass, ultrafine particles are hard to detect, and researchers try to utilize PM₁₀ in combination with nitrogen oxides NO_x and other trace gases to monitor their dynamic evolution. To meet pollution standards set by national government and European Union regulation, the city of Klagenfurt, Austria, began using calcium magnesium acetate as a deicer on 11 January 2012, hoping to literally glue pollutants to the ground and thereby reducing pollution concentrations. With the statistical methodology developed in this article, the dynamic evolution of PM₁₀ and NO_x is traced for the time period starting 4 January and ending 25 January 2012, and a change in dynamics is found. The findings are based on on‐line monitoring procedures that sequentially detect structural breaks in the mean and the parameter values of an autoregressive moving average process. These are defined in terms of model residuals and one‐step ahead predictors. Theoretical properties are studied, and a simulation study shows that the proposed procedures work well in finite samples.     

Photon echoes and combination tones--A comparison between their polarization dependence

The effects of level degeneracy on the polarization dependence of photon echoes and of combination tones in gases are compared. A remarkable similarity in behavior is found to exists, with quantitative agreement in the case of several simple transitions. By analogy, the echo behavior for elliptically polarized input pulses is suggested.     

ABCD matrices for dispersive pulse propagation

The use of the ABCD matrices for the calculation of pulse propagation in second-order dispersive media is developed rigorously. Their usefulness is demonstrated by obtaining the results for the propagation of a Gaussian pulse with an arbitrary linear chirp. By analogy with ray optics, the concept of a time ray is introduced to give further insight. The analogy with paraxial optics is carried further by extending the matrix method to a complete Hermite-Gaussian basis and thus to arbitrarily shaped and nonlinearly chirped pulses. Some practical applications of the matrix method are discussed     

Cross-phase modulation in a semiconductor laser amplifierdetermined by a dispersive technique

Cross-phase modulation in a semiconductor laser diode amplifier is reported. A simple expression for the chirp imparted on a weak signal pulse by the action of a strong pump pulse is derived. A novel dispersive technique for characterizing the resulting nonlinear chirp is introduced and used in the present experiment. A maximum frequency excursion of 16 GHz, due to the cross-phase modulation, was measured. A value of 6 was found for α_xpm, which is a factor for characterizing the cross-phase modulation in a similar manner to the conventional linewidth enhancement factor α     

Extramedullary expansion of hematopoietic progenitor cells in interleukin (IL)-6-sIL-6R double transgenic mice

Soluble cytokine receptors modulate the activity of their cognate ligands. Interleukin (IL)-6 in association with the soluble IL-6 receptor (sIL-6R) can activate cells expressing the gp130 signal transducer lacking the specific IL-6R. To investigate the function of the IL-6-sIL-6R complex in vivo and to discriminate the function of the IL-6-sIL-6R complex from the function of IL-6 alone, we have established a transgenic mouse model. Double-transgenic mice coexpressing IL-6 and sIL-6R were generated and compared with IL-6 and sIL-6R single-transgenic mice. The main phenotype found in IL-6-sIL-6R mice was a dramatic increase of extramedullary hematopoietic progenitor cells in liver and spleen but not in the bone marrow. In IL-6 single-transgenic mice and sIL-6R single-transgenic mice no such effects were observed. The high numbers of hematopoietic progenitor cells were reflected by a strong increase of peripheral blood cell numbers. Therefore, activators of the gp130 signal transducer like the IL-6-IL-6R complex may represent most powerful stimulators for extramedullary hematopoietic progenitor cells. gp130 activators may become important for the expansion of hematopoietic progenitor cells in vivo and in vitro.     

A discussion of material rotation and stress rate

Summary Characterization of material behavior can be divided into two parts, the analysis of deformation and the underlying physics, though these are intimately related. A significant advance in the analysis of deformation was made when the polar decomposition theorem was introduced, making it possible to separate large deformations into a stretch and a rotation. Consequences of the theorem affect the way rate processes should be characterized. In particular, rate of material rotation is different from vorticity, and the stress rate for finite strains is different from the usual stress rate of Zaremba, Jaumann, and Noll. It is convenient to define a strain rate that is different from the stretching that is the symmetric part of the velocity gradient. These concepts are described in detail in a 1979 paper. Various criticisms of that paper have appeared in the Journal of Applied Mechanics, which are discussed herein. To illustrate the distinction it is shown that the rate of rotation in a classical vortex does not vanish, though the vorticity is zero. It is also shown that the rate of material rotation recently computed by Nemat-Nasser, which involves an eigenvalue expansion, is equivalent to the one given in the 1979 paper, which makes use of matrix inversion, and it is asseverated that the matrix inversion approach is computationally more efficient.     

Do fielders know where to go to catch the ball or only how to get there?

Skilled fielders were filmed as they ran backward or forward to catch balls projected toward them from a bowling machine 45 m away. They ran at a speed that kept the acceleration of the tangent of the angle of elevation of gaze to the ball at 0. This algorithm does not tell fielders where or when the ball will land, but it ensures that they run through the place where the ball drops to catch height at the precise moment that the ball arrives there. The algorithm leads to interception of the ball irrespective of the effect of wind resistance on the trajectory of the ball. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intracellular accumulation of incompletely processed transforming growth factor-alpha polypeptides in ground glass hepatocytes of chronic hepatitis B virus infection

BACKGROUND: Transforming growth factor-alpha is an intracellularly processed and secreted polypeptide that induces a proliferative response in epithelial target cells and represents a potential regulatory factor in embryonic development, liver regeneration, and also hepatocarcinogenesis. We have observed focal transforming growth factor-alpha expression in liver tissues with chronic hepatitis B virus infection. METHODS: To further elucidate the nature of this focal transforming growth factor-alpha accumulation we have analyzed overall 23 different liver tissues with chronic hepatitis B virus and hepatitis C virus infection as well as normal liver tissues by immunohistology, ELISA, and Western immunoblot with and without immunoprecipitation. RESULTS: By immunohistology transforming growth factor-alpha polypeptides showed focal subcellular accumulation in ground glass hepatocytes, the histological hallmark of chronic hepatitis B virus infection, in co-localization with HBV-preS1 antigen. By ELISA and Western immunoblot increased tissue concentrations of transforming growth factor-alpha were demonstrated in chronically hepatitis B virus-infected liver tissues with ground glass hepatocytes, especially a 15-kD polypeptide, most likely representing an incompletely processed transforming growth factor-alpha polypeptide. Transforming growth factor-alpha retention in ground glass hepatocytes is not a general unspecific effect, since it was not observed for several other secretory liver proteins. Accumulated transforming growth factor-alpha in ground glass hepatocytes does not co-localize with Epidermal Growth Factor Receptor expression. CONCLUSION: Thus evidence is presented that a principally secreted (viral) polypeptide (HBV-preS1) can interfere with the secretion and processing of a second (cellular) protein (transforming growth factor-alpha). Accumulation of transforming growth factor-alpha may result from alteration of the endoplasmic reticulum due to storage of hepatitis B virus surface antigen particles. No evidence was found for transforming growth factor-alpha in ground glass hepatocytes to intracellularly interact with the Epidermal Growth Factor Receptor.