Showing papers on "Character (mathematics) published in 1972"

Convergent and divergent character displacement

Abstract: Consideration of the possibilities and difficulties of detecting character displacement leads to a re-definition of the phenomenon; character displacement is the process by which a morphological character state of a species changes under Natural Selection arising from the presence, in the same environment, of one or more species similar to it ecologically and/or reproductively. This incorporates the principal ideas in the original definition given by Brown & Wilson (1956), but eliminates the restriction of making comparisons of the character states of a species in sympatry and allopatry. The evidence for the ecological (competitive) aspect of character displacement is assessed by analyzing in detail the best documented and well publicized examples in the literature. Some of the examples either do not exhibit displaced characters or, if they do, the “displacement” can be interpreted in other and perhaps simpler ways; this applies to the so-called classical case of character displacement, Sitta tephronota and S. neumayer in Iran. Other examples, involving lizards and birds, constitute better evidence for character displacement, but in no single study is it entirely satisfactory. It is concluded that the evidence for the ecological aspect of character displacement is weak.

Characters of Free Groups Represented in the Two-Dimensional Special Linear Group*

Abstract: We consider here the problem of determining when two elements in a free group will have the same character under all possible representations of the given group in the special linear group of 2 x 2 matrices with determinant 1. Problems involving the representation of free groups in terms of 2 x 2 matrices with real entries and determinant 1 have been investigated by R. Fricke in connection with certain problems in the theory of Riemann surfaces [2]. Fricke’s main concern is to find those representations which define discontinuous groups of the conformal self-mappings of the upper half-plane. His method is based on arguments in non-Euclidean geometry, and has only recently been made fully rigorous and transparent by Linda Keen [4]. Apart from the analytic problems inherent in Fricke’s method there are several algebraic problems which have been answered by Fricke either incompletely or not at all. It is the algebraic aspects of Fricke’s theory which we shall investigate here. Independently of Fricke’s problems however, the subsequent development may be considered as a straightforward contribution to the representation theory of free groups. We shall consider the following general situation. K will denote a fixed commutative ring with identity of characteristic zero, and SL(2, K) the group of all 2 x 2 matrices with determinant 1 and entries from K. It will be shown that the character of any element in a free group under an arbitrary representation of the group in SL(2, K) can be constructively represented as a polynomial expression with integer coefficients in the characters of certain simple products of the group generators. Two polynomials will represent the same character if and only if they are congruent modulo a member of a certain class of ideals. This will reduce the problem of determining whether two elements have the same character to the problem of determining the structure of these ideals. The structure of the ideals will then be determined for the free groups of rank 1, 2, and for the free group of rank 3 under restricted conditions on K. We shall show that if two elements u, v in a free group F have the same character under all possible * The work for this paper was done while the author was at the Courant Institute of Mathematical Sciences and was supported by the National Science Foundation Grant GP-28538. Reproduction in whole or in part is permitted for any purpose of the United States Government. 635

Further Studies Based on the Uniquely Derived Character Concept

Abstract: LeQuesne, W. J. (70 Lye Green Road, Chesham, Bucks, England) 1972. Further studies based on the uniquely derived character concept. Syst. Zool., 21:281-288.-A number of methods of selection of characters based on the uniquely derived character concept (LeQuesne, 1969) have been applied to published data on taxa of Orthopteroid insects and also to random data obtained by dealing cards. The latter has been used to verify the essential soundness of the statistical methods. The data on Orthopteroid insects show some uncertainty in the most likely phylogeny among the group, although verifying the existence of some already well-accepted groupings. It is shown that at least 54 out of 80 characters tested are not uniquely derived. Most work employing numerical taxonomic methods has been aimed at establishing phenetic relationships between taxa. Useful as this aim is, I suspect that the main application of numerical methods will in the future become the study of the speciation process and the relative effects of influences such as divergence, convergence, and parallel evolution. In an earlier paper (LeQuesne, 1969) I defined a "uniquely derived character" as one which has evolved only in one direction on a single occasion in the history of the group being studied. This concept produced the logical result that for two independent uniquely derived characters each with two character states, not more than three out of the four possible combinations of character states can be found. Thus, if all four combinations are actually found, one or both of the characters concerned is not uniquely derived. The conicept of the uniquely derived character is one that will, I am sure, help in the study of the speciation process; it is one that has been instinctively assumed by many taxonomists studying evolution and phylogeny. For the work described below, the data of Blackith and Blackith (1968) for higher taxa among the Orthopteroid orders has been carefully studied. For this purpose a number of Fortran programs have been written and run. In this, I am greatly indebted to Mr. J. Bryant, who not only performed much of the programming, but helped considerably in all phases of this work by his interest and valuable suggestions. THE COEFFICIENT OF CHARACTER

Page width optical character processing method and system

Abstract: A transport system moves documents beneath a self-scanned photocell array extending substantially the entire width of a page. The output data from the photocells is scanned via a plurality of channels, amplified, multiplexed, and converted to a digital format. The digital data is then processed to compensate for fixed pattern errors characteristic of the photocell array and for scan pattern error. The corrected digital data is quantized for character thresholding and input to a recirculating memory. Line-tracking circuitry monitors the location of individual lines of character data within the recirculating memory and gates a complete line of character data into one of two storage registers. While data is input to one register, the contents of the other register is output to character recognition circuitry.

Character modules, dimension and purity

Abstract: In this paper we use the Bourbaki conventions for rings and modules: all rings are associative but not necessarily commutative and have an identity element; all modules are unital.

Character recognition apparatus

Abstract: Character recognition apparatus wherein projection pattern signals obtained by projecting the density distribution of a printed or typed character on two axes orthogonal to each other are transformed into frequency spectrum patterns by a Fourier transform unit, the transformed signals are compared with a number of standard frequency spectrum pattern signals which correspond to a number of standard characters and which are obtained by a method similar to the foregoing one, and the standard character corresponding to the frequency spectrum pattern of the highest degree of similarity is outputted as a recognized character.

Television type display system for displaying information in the form of curves or graphs

Abstract: Television type display system for displaying information in the form of curves or graphs. Code words designating characters are read out of a random access memory and the characters are displayed at fixed normal locations on the display surface of the display device. The normal location of a character on the display surface is determined by the position of the character code word in the memory. Delay code words designating amounts of delay may be associated with characters by being stored in the position in the memory preceding a character code word. The delay code word is employed to hold the character data for each scanline in a buffer for a period of time determined by the delay code word before releasing the data into the video stream. Thus, display of the character is delayed causing it to appear in a location on the display surface shifted from its normal location. A plurality of characters may be displayed in this manner to produce a curve. The system may also be utilized to display data in bargraph format.

Apparatus for improving the shape of characters formed by a row and column coordinate matrix for display on a cathode-ray tube

Abstract: An addressing circuit arrangement for character display apparatus in which the characters are composed in a matrix form. When doubling the character height extra elements are added on either side of the character so as to improve its shape resulting in a rounding-off effect. To this end the addressing circuit arrangement is formed with shift registers, bistable circuits and gates which jointly supply write-early and write-late signals.

Methods and means for reproducing non-alphabetic characters

Abstract: Non-alphabetic characters are reproduced by feeding into a computer symbols defining the gross form of each character, then feeding in successive pairs of symbols, with one symbol in each pair defining an element of the character and another symbol defining the juxtaposition of each element relative to previous elements. The operation of the computer is fixed by a program to cause a plotter to draw the elements in accordance with their juxtaposition and thereby form the characters.

One-at-a-time alternate dispensing method

Abstract: A web roll having a pair of plies equipped with transverse perforations of a specified character which are off-set in the different plies so as to provide a source for dispensing through a force-developing nip whereby web segments issue sequentially and alternately.

On the formalist-structuralist theory of character

Abstract: The Formalist-Structuralist conception of character is best summed up by the term invented (I think) by Greimas, namely actantiel — the notion that characters are to be conceived äs actants or participants, rather than äs real beings — to avoid what the structuralists take to be a mistaken indulgence in considerations of 'psychological essence'. The structuralists wish to base their analyses strictly on what characters DO in a story, not on what they ARE — by some outside psychological measure. Further, the 'spheres of action' in terms.of which the character is manifested are 'comparatively small in number, typical and classable'. For Propp, characters are simply the products of their functions in narratives, what it is that the Russian fairy-tale requires them to do:

Effects of the Defendant's Character and Suffering on Juridic Judgment: A Replication and Clarification

Abstract: (1972). Effects of the Defendant's Character and Suffering on Juridic Judgment: A Replication and Clarification. The Journal of Social Psychology: Vol. 88, No. 1, pp. 149-150.

Natural Selection for a Quantitative Character over Several Generations

Abstract: THERE are many plausible models to describe how selection might affect the values of a quantitative character. Perhaps the most generally useful is a quadratic model in which fitness decreases in proportion to the square of the deviation of the character from an optimum value. If w is the fitness of an organism when the character has the value x, then w=1−α− K(θ−x)2 where θ is the optimum value of the character and K is a constant. Thus at x=θ, w=1−α and fitness is at a maximum. From this model the values of Δx and ΔVx, the changes in the mean and variance after selection, can be predicted1. Conversely, if Δx and ΔVx are known, then the values of the parameters, α, K and θ, and the change in mean fitness can be calculated2. The proportionate change in mean fitness, Δw/w, is a general measure of the effect of selection. While selection is acting only on phenotypes and there has been no mating, Δw/w=Vw/w2. But if sexual reproduction takes place after the selection, the formulae for Δx, ΔVx and Δw/w may no longer be valid. Changes that affect environmental variations will not be passed on to the next generation: changes in the numbers of genotypes will be subject to genetic segregation and recombination. The variance may increase or decrease depending on the frequencies of the genes. In this communication, formulae are derived for the changes in the mean and variance of a character after selection from one generation to the next. They depend on a simple model of the inheritance of the character.

The gambling addict versus the gambling professional. A difference in character

Abstract: By contrasting the addicted with the professional gambler it is hoped that a greater insight into the character of each will be gained. An attempt is made to compare the two types in terms of emotional, interpersonal, behavioral, and attitudinal factors.

System and method for character recognition

Abstract: A character recognition system is disclosed in which each character in a retina, defining a scanning raster, is scanned with random lines uniformly distributed over the retina. For each type of character to be recognized the system stores a probability density function (PDF) of the random line intersection lengths and/or a PDF of the random line number of intersections. As an unknown character is scanned, the random line intersection lengths and/or the random line number of intersections are accumulated and based on a comparison with the prestored PDFs a classification of the unknown character is performed.

On the evaluation of Brewer’s character sums

Abstract: A decade ago in this journal B. W. Brewer defined a sequence of polynomials V (x, 1) and for zz = 4 and 5 evaluated

Automatic Character Reading Using a Holographic Data Processing Technique

Abstract: One of the useful applications of holography is information conversion. This paper reports on a newly developed automatic character reading system using code-transform holograms for analog-digital (A-D) conversion. Unknown characters are recognized by converting spatial analog character information to spatial digital information. System parameters are sampled out, and important factors such as (1) discrimination, (2) storage capacity, and (3) reading speed, which determine the performance of this system, are discussed.

A method for objective evaluation of the fertilizing ability of spermatozoa irrespective of genetic character.

Abstract: X-irradiation with 6000 to 10,000 rad can be used as a method of `marking' a population of rabbit spermatozoa without affecting their fertilizing ability. Following a mixed insemination, irradiated spermatozoa compete equally well with non-irradiated spermatozoa from the same population, as judged by differential egg development 50 hr after insemination, at which time eggs fertilized by irradiated spermatozoa display obviously retarded cleavage. In this paper, the technique has been used to demonstrate: (a) a subtle decrease in the fertility of spermatozoa after incubation in vitro at 40\\s=deg\\ C, which was not detectable by insemination of the treated sample alone, (b) the ability of spermatozoa from the proximal cauda epididymidis to initiate contact with and fertilize ova as readily as ejaculated spermatozoa following mixed insemination, there being no delay in the time of egg penetration by the epididymal spermatozoa, (c) the existence of selective fertilization between individuals of the same breed, as well

Electrical display devices

Abstract: An addressing circuit arrangement for an electrical display device comprising a two-dimensional matrix of light-emitting elements which are connected at respective crosspoints formed by two groups of row and column conductors and each of which can be illuminated selectively by suitable energizing signals applied contemporaneously to the two conductors, one in each group, between which the element is connected. The arrangement includes, a circulation memory for storing character data in respect of a plurality of lines of characters to be displayed and for supplying in turn the character data for each line of characters serially character by character in a recurrent cycle, a character generator which is responsive to the supplied data for each character to produce a group of coded electrical signals that determine the discrete parts of the character to be displayed in the row of elements concerned, and a row store for storing in each fill period of each row period the several groups of coded electrical signals for the whole of the row of elements concerned.