Kinds Of Sequences Research Articles

Carbon-13 NMR spectral assignments of regioirregular polypropylene determined from two-dimensional INADEQUATE spectra and chemical shift calculations

The 13 C NMR spectrum of regioirregular polyropylene containing up to 40 mol% of inverted propylene units was assigned using the 2D INADEQUATE technique, the INEPT technique, and 13 C chemical shift calculations based on the 13 C NMR γ-effect and the application of the RIS model and also on the additive rules for 13 C chemical shifts of methyl-substituted alkanes. The presence of four kinds of sequences containing head-to-head and/or tail-to-tail units in the sample was confirmed. The 13 C- 13 C connectivities of the 2D INADEQUATE spectrum were extremely useful in the asssignment of overlapping peaks as well as the identification of several such sequences

2D-INADEQUATE 13C nuclear magnetic resonance assignment of regioirregular poly(1-butene)

The 13C nuclear magnetic resonance (n.m.r.) spectrum of regioirregular poly(1-butene) with a large number of chemical inversion units in the chain was observed. The assignments were performed by 13C n.m.r. Lindeman-Adams empirical rules, the insensitive nuclei enhancement by polarization transfer (INEPT) and two-dimensional incredible natural abundance double quantum transfer experiment (2D-INADEQUATE) 13C n.m.r. techniques. 2D-INADEQUATE was especially useful to assign each peak to carbon atoms located in several kinds of sequences in the chain.

Design and synthesis of heterogeneous azeotropic distillations—III. Column sequences

The column sequencing problem for heterogeneous azeotropic distillation is investigated. It is shown that residue curve maps play an important role in interpreting the behavior of these systems. Classes of residue curve maps which give rise to feasible column sequences ae identified. Several kinds of sequences are presented and it is shown that the conventional sequence frequently requires much larger reflux ratios than other alternatives.

General discussion after session V

N. C. Wickramasinghe ( Department of Applied Mathematics and Astronomy, University College, Cardiff, U. K. ). The question of the origin of life is, of course, one of the most important scientific questions and it is also one of the most difficult. One is inevitably faced here with a situation where there are very few empirical facts of direct relevance and perhaps no facts relating to the actual transition from organic material to material that can even remotely be described as living. The time perspective of events that relate to this problem has already been presented by Dr Chang. Uncertainty still persists as to the actual first moment of the origin or the emergence of life on the Earth. At some time between 3800 and 3300 Ma BP the first microscopic living systems seem to have emerged. There is a definite moment in time corresponding to a sudden appearance of cellular-type living systems. Now, traditionally the evolution of carbonaceous compounds which led to the emergence of life on Earth could be divided into three principal steps and I shall just remind you what those steps are. The first step is the production of chemical building blocks that lead to the origin of the organic molecules necessary as a prerequisite for the evolution of life. Step two can be described in general terms as prebiotic evolution, the arrangement of these chemical units into some kind of sequence of precursor systems that come almost up to life but not quite; and then stage three is the early biological evolution which actually effects the transition from proto-cellular organic-type forms into truly cellular living systems. The transition is from organic chemistry, prebiotic chemistry to biochemistry. Those are the three principal stages that have been defined by traditional workers in the field, the people who, as Dr Chang said, have had the courage to make these queries and attempt to answer them. Ever since the classic experiments where organic materials were synthesized in the laboratory a few decades back, it was thought that the first step, the production of organic chemical units, is important for the origin of life on the Earth, and that this had to take place in some location on the Earth itself.

In Praise of Theory

time or the interest to consider why we were presenting linguistic concepts in the classroom. We just wanted to know how. Impatient with theory and inexperienced, I grabbed any good idea for a lesson I could find. English Journal and Media & Methods usually had something. Any conference I went to meant an opportunity to gather ideas. If I was really desperate, I might even use something from that older teacher across the hall. But it was always a race to keep up with a steady need for worthwhile teaching ideas. Monday morning came five days a week sometimes. I was a scavenger of lesson plans. After a year or two, I realized something--a whole year of good ideas might not add up to anything substantial in the way of learning if, somewhere and somehow, I did not make connections and build on some kind of sequence. I started planning, partially because I felt guilty about my shotgun approach to teaching. But, oddly enough, the more I planned the more I ended up with the traditional, teacher-centered classroom I was trying to avoid. The more ordered and sequential I became, the less pleased I was with the content of my plans. I needed something to help me combine the need for order with the good lessons I wanted. That something, I know now, is theory. Twelve years ago, I impatiently skimmed articles and books that spoke of theory and eagerly looked for something practical. Now, I am likely to skim over practical information to find a succinct statement of theory. Although I would not have believed it twelve years ago, theory has more to offer me.

Growth of apparent duration: effect of melodic and non-melodic tonal variation.

Time estimates of 12 intervals of 15 to 65 sec. duration were obtained from 30 subjects by one of two methods, magnitude estimation and cross-modal matching. Three kinds of sequences of musical notes were presented during stimulus intervals; repetitive, melodic, and random. Within all sequences, notes were of equal duration and with equal pauses between them. In all cases, the relationship between perceived and physical time is consistent with Stevens' power law. Exponents derived from both kinds of estimates were significantly affected by the content of the interval. Exponents derived for repetitive sequences were not different from 1 and were significantly larger than exponents derived from random or melodic sequences. These results are inconsistent with the view that the predictability, familiarity, or codability of event occurring in the stimulus interval is inversely related to the perceived duration of that interval. There is some indication that the effect of the content of the interval on judgments of duration varies with the magnitude of the duration being judged. Perhaps the relationship holds only within certain parameters and, when these are exceeded, other factors mask the effect. A two-process theory of time perception, one which considers these other factors and explains the present results, is proposed.

Attention-switching and grouping in counting interaurally presented clicks

The present study tests the hypothesis that attention-switching is time-consuming and performance-limiting. Analysis of previous research on counting interaurally presented clicks shows that estimates of ‘switch-times’ can be made, based on the data of Guzy and Axelrod (1972). In the earlier click-counting studies, however, the number of clicks to be counted and the number of physical switches between the ears were confouned. Hence the number of clicks, number of physical switches and interval between clicks were independently varied. The results showed that (a) counting performance did not decrease monotonically with increasing number of switches in the click sequence; (b) no difference in counting performance could be found between the monaural and completely alternating interaural presentation; (c) when the number of switches in the sequence was small and equal groups of clicks alternated between ears, performance dramatically improved. With these kinds of sequences, subjects presumably do not count the clicks one at a time, but subitize a group of clicks.

Instruction and Delight In Medieval and Renaissance Criticism

The Horatian formula holding that a poem should instruct and delight raises two obvious questions: what is ‘instruction’ and what is ‘delight’? These are difficult questions, since they seem too broad to be answerable and too central to be dismissed. They are difficult, also, because they refer to paired terms. Are we to see instruction and delight related in some kind of sequence? And what of the cases where only one term appears and the other not at all?These are the basic questions generated by a consideration of the Horatian formula as it occurs in medieval and Renaissance critical texts and it is the purpose of this paper to show that the formula in these texts can be coherently interpreted through the use of the then dominant faculty psychology.

Determination of nucleotide sequences from double-stranded regions of HeLa cell nuclear RNA

Double-stranded regions which comprise about 4% of isolated HeLa cell heterogeneous nuclear RNA have been characterized by RNA fingerprinting and sequencing analysis. The simplicity of the pattern in two-dimensional RNA fingerprints suggests a sequence complexity of about 1000 nucleotides. The nucleotide sequences of six prominent RNase T 1-resistant oligonucleotides (ranging in size from 7 to 9 bases) have been determined using isolated double-stranded nuclear RNA labeled in vivo with 32P-labeled inorganic phosphate. We conclude that (here exists a substantial subpopulation of simple, potentially complementary sequences common to much of the heterogeneous nuclear RNA population and interspersed with other kinds of sequences.

Distribution of occupied sequences in one-dimensional arrays. Models for the reaction of polymer substituents

An analysis has been carried out to give, as functions of time or extent of occupation, the number Rw of sequences of w occupied members for the random pairwise occupation of a linear array which might represent the reaction of substituents of a polymer molecule. Results are given as a function of time for cyclic (loop) and linear arrays initially consisting of m unreacted members. The model, referred to as (I), has been heretofore analysed to give the time dependence of (i) the number Nx of sequences of x unreacted members, (ii) the extent ξ and (iii) the rate ξ of reaction. The basic postulate is that the probability that a hitherto unreacted pair of adjacent members reacts in the interval between t and t+ dt is kdt. It is found, for example, that for m→∞, more reacted pairs are in sequences of six reacted members than in any other kind of sequence at the completion of reaction (t→∞). The sequences are separated by me–2(≈13.5 %) isolated and therefore unreacted members.

Primary Structure Homology within the 23S Ribosomal RNA

OUR understanding of the evolution of the cell will depend largely on our gaining an understanding of the evolution of the cell's translation apparatus, and in this context I wish to discuss the recent finding that the RNA sequences (seen in a Tl ribonuclease digest) surrounding the methylated bases in the Escherichia coli 23S ribosomal RNA (rRNA) are all repeated twice in the molecule1. This has been interpreted to mean either that the 23S rRNA molecule is actually a dimer of two identical halves, or that the 23S cistron has evolved through a gene duplication and joining mechanism1. The dimer interpretation seems to be ruled out by the fact that there are many more kinds of sequences in the 23S rRNA than there are in the 16S rRNA, and so, reasonably, the former should be larger than the latter, if most sequences were singly represented in each2. In. view of the evolutionary significance of the second possibility, however, I wish to point out that there is at least one other reasonable interpretation of these data (which does not invoke gene duplication) and so they cannot be taken as evidence for an origin of the 23S rRNA cistron by a duplication and joining involving a smaller cistron.

On the Convergence of Sequences of Rational Functions

There are numerous kinds of sequences of rational functions, such as sequences of Pad6 approximants and sequences of rational functions of best approximation on a given point set, where the poles of the individual functions are not known even asymptotically, and no effective methods for their determination are at hand. Yet regions of convergence and degree of convergence depend heavily on the location of those poles. If assumptions on the location of poles are made, it may be possible to deduce results on regions and degree of convergence, as has been shown by Baker, Chisholm, Walsh, and others. The present note on these topics seems appropriate because a number of previous results, as set forth in a recent report by Baker [1], can be materially improved, especially with reference to degree of convergence. We emphasize Pad6 approximants and rational functions of best approximation. A rational function is said to be of type (m, n) if it can be expressed in the form

The Anisotropy of Time

Just as we can coordinatize one of the dimensions of space by means of real numbers without being committed to the anisotropy of that spatial dimension, so also we can coordinatize a topologically open time-continuum without prejudice to whether there exist irreversible processes which render that continuum anisotropic. For so long as the states of the world (as defined by some one simultaneity criterion) are ordered by a relation of temporal betweenness having the same formal properties as the spatial betweenness on a Euclidean straight line, there will be two senses which are opposite to each other. And we can then assign increasing real number coordinates in one of these senses and decreasing ones in the other by convention without assuming that these two senses are further distinguished by the structural property that some kinds of sequences of states encountered along one of them are never encountered along the other.

Matrix Formulation of Copolymerization Statistics

The molecular distribution statistics of a binary linear copolymer are developed by the application of matrix methods appropriate to the treatment of the statistical thermodynamics of one-dimensional systems. Through the definition of a matrix of sequential probabilities, the character of the copolymerization, the various average degrees of polymerization, and the relative probabilities of certain kinds of sequences can be readily obtained. The results are applied to a number of ``most probable'' copolymerizations: For example systems in thermodynamic equilibrium and radical copolymerizations in the steady-state approximation. The question of stereoregularity in the latter case is also examined. Some generalizations of the approach are discussed.

Types of sequence in human behavior

1. The study of types of human behavioral sequence is relatively undeveloped. Five kinds of sequence can, however, be distinguished—those based on determinism, organicism, associationism, autonomy and a fifth as yet inadequately defined type which has been designated provisionally by the letter “X.” 2. These five types of behavioral sequence can be shown to stand in a phylogenetic relationship to each other. 3. All five are present in the human organism and tend to be correlated with the degree of adaptability of the behavior shown, e. g., the deterministic sequences are characteristic of relatively unadaptable behavior. 4. Inadequate appreciation of these different types of sequences has resulted in considerable confusion, especially among those who enter the study of human behavior from the basic sciences and also with respect to certain aspects of our thinking concerning physical and chemical therapy and in the understanding of the mechanisms of psychotherapy.