Elementary Patterns Research Articles

Morphology of iron pyrite crystals

Effects of growth condition on the morphology of FeS 2 crystals and the growth mechanism have been studied by observing the elementary step patterns on surfaces of the growth crystals. The crystals have been prepared by chemical vapor transport in a sealed quartz tube with chlorine as a transport agent. Crystal surfaces and structures have been evaluated by chemical etching, differential interference microscope, scanning electron microscope and X-ray diffractometry. Crystal shapes vary from polyhedra to octahedra and finally plates or whiskers with increase of a growth temperature gradient. All crystals grow in the [100] or [111] direction, showing the two dimensional lateral growth.

Scaling of contour-coded binary images

Contour-coded binary images on a discrete square grid can be expanded by means of a simple numerical manipulation of their chain code if they are first decomposed into elementary convex patterns. This approach avoids several shape-interpretation problems, arising with arbitrary blobs, and reduces geometrical distortions to a minimum.

Accessibility in transportation networks probabilistic versus deterministic approach

Existing accessibility measures imply either a perfectly legible structure of the communication network, or a perfectly informed “visitor”. In the study of transportation networks (as well as in the study of large architectural complexes, for example) this implied assumption is extremely unrealistic. Markov chain is interpreted as a model of communication process, and an information-theoretic measure is derived for the measurement of accesibility in conditions of uncertainty of the visitor about the structure of the communication network. A number of elementary network patterns are compared using deterministic and probabilistic measures of accessibility. It is claimed that different patterns differ in the degree of susceptibility to uncertainty in the communication process.

Feature extraction from the electroencephalogram by adaptive segmentation

This paper describes the feature extraction stage of a proposed pattern recognition system aimed at automatic EEG analysis. The basic pattern-the EEG record-is split into "elementary patterns" called segments and transients, by means of a method relying on linear predictive filtering. Appropriate features, representing power spectra and the time structure of the signal, are then extracted and finally combined into a feature set representing the EEG as a whole. The quality of this representation may be assessed by comparing the original signal with its simulation from the stored features.

Contribution to the ethology of Limnotilapia Dardennei (Boulenger, 1899) (Pisces, Cichlidae) II. Social behaviour: Qualitative observations

This paper deals with some qualitative observations on the social behaviour of Limnotilapia dardennei (Boulenger, 1899), a mouthbrooding cichlid of Lake Tanganyika. It makes clear the interrelationships between and the contexts in which the elementary actions and patterns of markings — described in a previous paper — occur. Quantitative data are not included in this preliminary study. The general social and territorial organisation of Limnotilapia dardennei is treated, with special reference to fighting behaviour and social hierarchy, as observed in combination with territoriality. The reproductive behaviour of this cichlid is of the Haplochromis type. We give a short description of courting and spawning, and of the brooding habits of the female. This basic knowledge of social behaviour was required to allow subsequent quantitative research on the species.

Study of Directional Data Distributions from Principal Preferred Orientation Axes

This paper provides a simple method to analyze orientation density diagrams. Angular and density distributions of a given set of directional data about the "principal preferred orientation axes" are studied regardless of any theoretical distribution law assumptions. These axes are defined and computed as the nearest ("best axis") and the farthest possible ("pole to the best plane") from the data-vector set; the distribution is studied by computing the radii of nested annuli, each containing 5% data-vectors; illustration is provided by automatically prepared angular deviation histograms. The method applies to simple preferred orientation patterns and to some of their combinations; these seem to cover most geological cases. The three elementary patterns are presented: point-maximum, girdle-maximum, and cone-maximum. Typical geological examples demonstrate how this method can help in solving structural geology problems, such as determining the sense and the angle of shearing in rocks deformed by plastic flow, and defining fold axes by various means.

A theory of the pattern induced flight orientation of the fly Musca domestica II.

In a preceding paper, Poggio and Reichardt (1973a), a phenomenological theory describing the visual orientation behaviour of fixed flying flies (Musca domestica) towards elementary patterns was presented. Some of the problems raised in this first paper are treated here in more detail. The mapping between the position dependent torque distribution -- D(?) characteristics -- associated with a given pattern and the stationary orientation distribution p(?), is studied taking into account that the fluctuation process (generated by the fly) is coloured gaussian noise. Under certain critical conditions this may lead to an "early symmetry breaking" in the mean values of the p(?) distribution. The validity of the "superposition principle" has also been examined. Although shift and superposition give the main qualitative features of the "attractiveness profile" D(?), associated with a 2-stripe pattern, superposition does not hold quantitatively for stripe separations up to about 80°. Evidence is presented suggesting that such an effect is due to inhibitory interactions between input channels of the fly's eye. Implications of this finding with respect to the problem of spontaneous pattern preference are also discussed.

Non-linear aspects of dynamic pattern in cellular networks

Succession of one process-generated pattern by another is governed by non-linear transformation and transport processes, exemplified by chemical reactions within well-mixed cells connected by permeable walls into a regular network. Earlier work on the onset of instability is extended to encompass finite-amplitude disturbances of a uniform stationary state. Multiple stationary states of prescribed symmetries in a sixteen-cell network are found and their stability with respect to symmetric disturbances is examined by means of elementary concentration patterns—a “symmetry-adapted basis”—and their interaction properties, as described by direct products of the irreducible representations of the symmetry group of the network. Group theoretic symmetry considerations ease analysis of emerging dynamic pattern after changing reaction and diffusion parameters turn a uniform state unstable, as a simple example indicates. The paper is a step in the direction of mapping the topography of the physico-chemical state space of a developing system, a space corresponding to Waddington's concept of an epigenetic landscape.

Modeling of Higher Forms of Conditioning

Soviet reflex theorists, like their American S-R counterparts, face a major theoretical hurdle: it is one thing to assert that in principle complex human behavior may be accounted for by the appropriate combination of elementary conditioned reflex patterns; it is quite another to demonstrate the adequacy of such an explanation for any particular bit of complex behavior.

Principles of automatic analysis of sleep records with a hybrid system

A program for automatic sleep staging of whole nights polygraphic records of human subjects is described. The electronic system consists of an analog component, performing a first reduction of data, and a digital one, a small general purpose computer. The computer program assesses first the technical quality of the record, by recognition of artefacts, which may impair the diagnosis procedure. It performs second a two steps analysis, based upon electroencephalogram, muscle activity and eye movements. The first step of analysis is a recognition of elementary patterns on the tape and the second step is a calculation of a minute by minute sleep stage diagnosis, based upon these elementary patterns. This program has been tested by comparisons with human scoring of the same records, and has proved to have a good accuracy. This system is actually used as a clinical tool in the exploration of sleep disturbances.

Excitatory and inhibitory influences of thalamic stimulation on pyramidal tract neurons

Effects of single and repetitive (7/sec) thalamic stimulation on pyramidal tract (PT) neurons were investigated by laminar field potential analysis in the cat. Negative antidromic field potentials in the sensorimotor cortex, elicited by stimulation of the cerebral peduncle, and generated in fast (N 1) and slow (N 2) PT neuronal populations were used as indices. They were preceded by conditioning thalamic stimulation and changes of antidromic potentials at various depths in the cortex were plotted as functions of time intervals between the two stimuli. All cortical potentials evoked by thalamic stimulation represent either single or compound manifestations of the two elementary patterns, viz., the deep and superficial thalamocortical (T-C) responses. During the deep T-C response, both N 1 and N 2 were significantly suppressed at all levels in the cortex. Facilitatory influences on N 1 and N 2 were not seen. The superficial T-C response was associated with an initial enhancement of N 1 and N 2 and subsequent suppression. The facilitation was particularly pronounced in superficial cortical layers. On the basis of the laminar distribution of facilitation and inhibition certain conclusions regarding the location of active synaptic sites along an idealized PT neuron have been suggested: IPSPs associated with both types of T-C responses must be generated in somata as well as apical dendrites. EPSPs underlying the superficial T-C response are localized on superficial apical dendrites, while those generated during the deep T-C response are mainly on cell bodies and adjacent dendritic shafts.

Computer analysis and reconstruction of E.S.R. spectra of gamma-irradiated DNA.

SummaryPrevious results suggest that in DNA γ-irradiated in the dry state at 25°c an electronic migration occurs which transforms the primary random radioproducts into new ones, localized essentially on the pyrimidine nucleotides, dTMP and dCMP. According to this mechanism, the E.S.R. spectrum of irradiated DNA should consist of the weighted superimposition of pyrimidine patterns only. Conversely, starting from pyrimidine patterns only, it should be possible to reconstruct the E.S.R. spectrum of DNA.To demonstrate this assumption we attempted first to isolate the constituent patterns from the dTMP and dCMP experimental spectra. While the dCMP spectrum, C, behaves like a single entity, the spectrum of dTMP was found to consist of the superimposition of three main patterns which we called τ1, τ2 and τ3.A programme was then prepared to perform a large number of linear combinations following the formula Δ = h1τ1 + h2τ2 + h3τ3 + kC, where the variable coefficients represent the relative intensity of the four elementary patterns in the resulting spectra Δ. We obtained in this manner an atlas of reconstructed spectra, all built up from the same pyrimidine patterns, but at different relative intensity. According to our hypothesis, for each experimental spectrum of DNA there should be an identical one among the reconstructed spectra. A series of DNA spectra obtained in our laboratory or published in the literature were successfully subjected to this test. For each of them the relative yields of the different pyrimidine radicals were hence determined by comparison.

Teacher Training in the Federal Republic of Germany

Teacher training in West Germany is on the verge of fundamental change. As the schools—traditionally tripartite on the secondary level-begin to become integrated into comprehensive institutions (similar to the American model), the hitherto different training systems for elementary and secondary teachers face reform patterns aimed at equalizing the length and standards of training. In addition, the planners call for programs that prepare teachers for continuous reforms of the curriculum and of instructional media. Much emphasis is given to scientific studies of didactics-i.e., to the adaptation of fields of knowledge to modes of teaching and learning.

Format-directed list processing in LISP

This paper describes a notation and a programming language for expressing, from within a LisP system, string transformations such as those performed in CoMIT or SNOBOL. A simple transformation (or transformation rule) is specified by providing a pattern which must match the structure to be transformed, and a format which specifies how to construct a new structure according to the segmentation specified by the pattern. The patterns and formats are greatly generalized versions of the left-half and right-half rules of CoMIT and SNOBOL. For example, elementary patterns and formats can be variable names, results of computations, disjunctive sets, or repeating subpatterns; predicates can be associated with elementary patterns which check relationships among separated elements of the match; it is no longer necessary to restrict transformations to linear strings since elementary patterns can themselves match structures. The FLIP language has been implemented in LISP 1.5, and has been successfully used in such disparate tasks as editing LisP functions and parsing Kleene regular expressions.

Proprioceptive leg reflexes in cockroaches.

ABSTRACT Proprioceptive feedback from the moving wings of locusts contains information which could be sufficient for the control of the timing of the wing-muscle contractions. It has been found, however, that at the high frequency of limb movement used in flight this phasic information content is lost in the ganglionic transfer (Wilson & Gettrup, 1963). During rapid running the legs of cockroaches also oscillate at high frequencies, sometimes as rapidly as wing movements of similar-sized animals. It is therefore necessary to know whether the frequency response capabilities of the leg reflexes are similar to or different from those of the wings in order to understand how the legs are coordinated. If the leg reflexes are limited to the same range as that available to the wing reflexes, then coordination of the legs would necessarily depend upon ganglionic phasing mechanisms ; that is, the elementary pattern of leg movements could be due to central nervous control alone, as is true of the locust wing control (Wilson, 1961). However, it can be shown that the phasic leg reflexes are capable of operation at frequencies even greater than those encountered in running. Apparently the significant limitation on rate of leg movement is not nervous but mechanical; that is, due to the maximum rate of contraction of the muscles.

A note on trace-to-trace correlation in visual displays: elementary pattern recognition

In intensity-modulated visual displays used for the detection of pulse signals in noise, e.g., the P.P.I., the B-scan cathode-ray display, or the chemical recorder display, a normal requirement is to recognize the signal not only by its amplitude but also by the fact that it extends across two or more scans or traces.This means, in effect, that detection is partly a matter of recognizing the correlation of signal pulse from one trace to the next. In this note, subjective measurements of the effect of this correlation on the threshold signal/noise ratio are given and discussed. It is shown that over the range of input signal/noise ratio from −10 to 0 db, the reduction of threshold is about 2.2 db per doubling of the number of traces, as compared with the 1.5 db theoretically obtained from "integration" of successive traces.

A Note On the Classification of Elementary Behaviour Patterns

A short review of recent studies on elementary behaviour patterns in non-directional gradients shows that adaptation plays an important part in kinetic responses and that the speed and activity components of orthokinesis may or may not be associated. An expanded classification of kineses into those with and without adaptation is proposed. Within these categories it is suggested that the three components of speed, activity and turning should be separately recognised. More generalised definitions of klinotaxis and tropotaxis are proposed. Klinotaxis is regarded as an orienting pattern in which successive comparisons of stimulation intensities are made; tropotaxis as a pattern in which there is simultaneous comparison of stimulating intensities. Not all 'shock reactions' can be regarded as extreme cases of klinokinesis with adaptation and a new category of reaction made at a boundary is defined. This is characterised by a slowing or cessation of movement followed by some tactic mechanism of orientation. The name titubant reaction is proposed. This reaction does not itself lead to orientation.