Fractals and the large-scale structure in the Universe

In Part 1 of this article, we had introduced the reader to some basic concepts of fractals and some operational algorithms to characterize them. We had also pointed out and clarified some common misconceptions about fractals. In this part we apply the fractal concepts to large-scale structures in the Universe. In particular we discuss the claim by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. Also discussed is the controversy as to whether the matter distribution in the Universe is a fractal on large-scales.     

Teaching Methods in Higher Education: The Changing Scene,with Special Reference to Small‐group Work

The paper opens with a brief statement of the two conceptual frameworks on which the analysis is based. The author then takes up in turn the five classical methods of shaping students' learning: didactic instruction in the form of lectures; discussion methods; practical work in laboratories, studios etc; provision for the students' private study, including individualized learning techniques and computer‐based methods; and the assessment of students' progress. He outlines the main departures from customary practice in each area, with special attention to small‐group techniques. Finally, since a critical aspect of development is the dissemination of fresh techniques, there is a section on development strategy.     

Encoding of the unconditioned stimulus in Pavlovian conditioning

Three experiments, using rats, demonstrated the encoding of a food unconditioned stimulus (US) in a simple Pavlovian conditioning paradigm. In all three studies, one stimulus was used to signal the delivery of pellets and a different stimulus was used to signal the delivery of sucrose. In Experiment 1, postconditioning devaluation of one of the food USs selectively reduced the frequency of conditioned magazine-directed behavior during the stimulus trained with that US. In Experiment 2, transfer of the stimuli to instrumental responses resulted in selective depression of the response trained with a different outcome. In Experiment 3, acquisition of stimulus-outcome learning was impaired by unsignaled intertrial presentations of the same outcome but not of a different outcome. These results indicate that a detailed representation of the outcome is encoded in the normal course of Pavlovian conditioning.     

Fractals and the large-scale structure in the Universe

During the last decade it has been argued by some investigators that the distribution of galaxies in the Universe is a fractal. This is contrary to the standard view that the Universe is homogeneous and isotropic on large scales. In this article, the basic concepts of fractals and their characterization are introduced with the help of simple examples. The applications of these concepts in the context of cosmology will be discussed in the second part. A K Mittal is currently a visiting scientist at Harish-Chandra Research Institute, Allahabad, on leave from the University of Allahabad. His research interests include chaos, fractals and their applications, partleularly in cosmology and in weather prodiction. T H Seshadri is at the Department of Physics and Astrophysics, University of Delhi. He is presently on lien from Harish-Chandra Research Institute, Allahabad. Areas of his interest include cosmic microwave background radiation, large scale structures in the Universe and application of fractals in these.     

Hydrodynamic lubrication

This article gives the principle of hydrodynamic lubrication and also presents the new phenomenon of levitating drops over liquid film flow, which is explained using hydrodynamic lubrication theory.     

Novelty versus retrieval cue value of visual contextual stimuli in pigeons

Learning & Behavior - Thomas and Empedocles (1992) proposed that in a retention test, the relative enhancement of responding when the context that had accompanied training is again present...