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ESTIMATION of microquantities of purines by paper chromatography was first suggested by Hotchkiss1. Later, detection by photographing with an ultra-violet source has amplified the method2. Tennent et al. 3 and others have designed adaptors for the Beckman spectrophotometer to enable direct estimation of the purines from paper chromatograms. This method requires costly instrumentation, and is time-consuming unless an automatic recorder is provided.

THE analysis of the protein composition of blood serum or plasma by means of zone electrophoresis on filter paper has stimulated interest in clinical laboratories throughout the world. In addition to numerous publications dealing with the applications of the technique in various pathological conditions, critical assessments of its validity and accuracy have appeared1–4, in which attention is properly directed to the limitations of the method from the point of view of the numerical evaluation of the separated protein fractions. It has seemed desirable to undertake a study of the accuracy and reproducibility of this method of protein analysis, using two of the most commonly employed protein-dyeing techniques.

It has been observed, and proved experimentally, that the nature of the paper surface has a considerable effect on the tone reproduction characteristics of halftone processes. It is concluded that any tone reproduction curve related to a halftone process is meaningless unless the type of paper to which it applies is specified in general terms.

This paper describes the development and application of an algorithm which generates non-linear representations of English text. The algorithm uses the results of a syntactic analysis system and a set of rules which prescribe linkages to generate a graph of a sentence. The shape of these graphs corresponds to the syntax of the sentence; the labels correspond to the vocabulary of the sentence and the edge types correspond to case grammar roles. The sentence graphs can then be interconnected at common nodes and analyzed according to common edges. Preliminary experimentation has yielded promising results. It appears that the algorithm produces a representation of English text which could be quite useful in automatic language processing.

A practical system for translation of information coded on punched paper tape to a matrix on a photograph is presented. The information here consisted of stereo random brightness fields; however, the system should be applicable to any three-dimensional information. The matrix is developed by slow digital scan of an intensity (ten levels) modulated oscilloscope and is photographed by a camera on time exposure. The system requires 166 seconds to produce each 10 000 element matrix and hence cannot be used for on-line work. However, for the researcher who can tolerate this limitation, the system's low cost, simplicity, and good resolution (better than 100 elements per inch) should prove attractive.

The paper describes an initial study of the problem of automatically distinguishing the action potentials of single motor units in skeletal muscle in man. The implications of the results are discussed in relation to the use of EMG activity for controlling externally powered devices and as a possible means for categorizing pathological states.

The parameters of the models described by Rumelhart and Greeno in this journal (1971) are constrained in certain ways. Neglect of this fact in their paper leads them to an inadmissible set of parameter values, and an invalid argument and statement concerning the equivalence of two models. However, their conclusion that the Restle model fits their data better than the Luce model remains unchanged.

Some of the major results of future goals of an automatic program synthesis project are described in the two papers that comprise this document. The first paper gives a detailed algorithm for synthesizing a computer program from a trace of its behavior. Since the algorithm involves a search, the length of time required to do the synthesis of nontrivial programs can be quite large. Techniques are given for preprocessing the trace information to reduce enumeration, for pruning the search using a failure memory technique, and for utilizing multiple traces to the best advantage. The results of numerous tests are given to demonstrate the value of the techniques. The other paper gives a brief overview of the automatic programming system within which the above algorithm is being used. This system is still under development. (Author/CH)

The primary aim of these five technical papers is to indicate aspects of proof theory which may be of use in the study of non-numerical computing. The three main papers are entitled: "Checking of Computer Programs;""Consistency Proofs and Programs for Translators;" and "Experiments with Computers on the Complexity of Non-numerical computations." The author shows that many theorems on computability in traditional metamathematics are of little use to the computer scientist because they do not lead to feasible algorithms. He also suggests alternative approaches to proof theory which would be of greater applicability. (MM)

Holography is a novel method of photography using coherent light from a laser source. Its unique feature is that it records a faithful three-dimensional image of the object. This allows one to compare the shape of an engineering component at one moment in time with its shape after some change has taken place, e.g. by deforming it under load. In some cases the holographic image of a ‘master’ component can be used as a template against which similar components can be matched with high precision. The techniques of holography, the interpretation of the results obtained, and the present limitations of the method will be discussed.

On each trial Ss viewed one of the patterns of six connected squares that result when the faces of a cube are unfolded onto a flat surface. The Ss tried, as rapidly as possible, to decide whether two arrows, each marked on an edge of a (different) square, would or would not meet if the squares were folded back up into the cube. The time required to make such decisions increased linearly (from 2 to about 15 sec) with the sum of the number of squares that would be involved in each fold, if those folds were actually performed physically.

The main arguments that led to the definition of the 1931 CIE colour system and of the Standard Observer are presented, together with an interpretation of the colour co-ordinates obtained in this system. The correlation of CIE co-ordinates with visual estimates is considered, and other systems of more uniform colour space are discussed. A method of expressing colour differences is indicated and related to colour tolerance. The essential principles on which instrumental methods are based are also given, together with brief descriptions of some typical instruments of different types. The principal applications of colorimetry are outlined and some of the advantages and disadvantages of instrumental methods as compared with visual methods are suggested. Simple numerical examples are included to illustrate important points.

In H. K. Weiss' letter to the Editor (“The Fiske Model of Warfare”, Opns Res. 10, 569–571 (1962).), Weiss pointed out that Rear Admiral Fiske, USN, seemed to have foreshadowed by 11 years the developments that have come to be known as Lanchester's Square Law. Weiss stated that Fiske appears to have been the first to observe publicly that, when the damage each of two forces can inflict on the other is proportional to its own size, the change of size of each force was geometric rather than arithmetic.

SUMMARY Examination of the criteria employed by ALLEN (1963) in his classification of cross-stratified units suggests (a) that an additional criterion, the three-dimensional shape of cross-strata, should be used in describing and recognizing varieties of cross-stratification, (b) that the character of the lower bounding surface of sets should be expressed in descriptive rather than genetic terms, and (c) that in describing the relation between cross-strata and lower bounding surfaces, an additional term, asymptotic, should be used. The recent discussion of the morphological features of cross-stratification by ALLEN (1963) represents a significant advance in our appreciation of the variability of this type of sedimentary structure. The valuable classification of McKEE and WEIR (1953) generated a concern for precise description of cross-stratification which has, in 10 years, made the classification inadequate. Allen's proposed classification, based as it is on observable morphological criteria and utilising a nongenetic terminology, should promote further rapid progress. Allen has discussed the problems that arise in naming varieties of cross-stratification. He very properly avoids terms with genetic implications and his use of Greek letters results in commendably brief names. Almost inevitably, his chosen nomenclature is not readily applicable in the field due to the difficulty of remembering which letter is associated with which assemblage of morphological features. This difficulty will increase as the number of defined varieties increases. It seems probable that workers will prefer for the most part to give names to varieties of cross-stratification only in the laboratory where reference to literature can be made. The basis for recognition of varieties will be detailed field notes and photographs of morphological features. Nor is this undesirable, for it necessitates the making of detailed observations in the field which will lead to the recognition of new varieties. An easily remembered nomenclature too often leads to the suppression of significant differences in the interests of “pigeon-holing” the structure in question. It is therefore important that all significant morphological features should be noted. Consideration of the differences between certain varieties of cross-stratification.

Items have been studied heretofore for their value as elements of particular tests to the neglect of more fundamental research into the multiple potentiality of items. This article proposes a method of grouping items into “synonymies” comprising all of the items which correlate with a given key item. These synonymies can be used for interpretation of the total meaning of the key item: (1) by inspection of the constituent items and (2) by correlational study of obtained single scores of individual persons. The method is illustrated by four items with inter- and intra-correlations, and characteristics of an ideal background reservoir of items are pointed out.