Showing papers by "University of Chicago published in 1968"

Conformation of Polypeptides and Proteins

Abstract: Publisher Summary This chapter deals with the recent developments regarding the description and nature of the conformation of proteins and polypeptides with special reference to the stereochemical aspects of the problem. This chapter considers the parameters that are required for an adequate description of a polypeptide chain. This chapter focuses the attention on what may be called “internal parameters”—that is, those which can be defined in terms of the relationships among atoms or units that form the building blocks of the polypeptide chains. This chapter also provides an account of the mathematical method of utilizing these parameters for calculating the coordinates of all the atoms in a suitable frame of reference, so that all the interatomic distances, and bond angles, can be calculated and their consequences worked out. This chapter observes conformations in amino acids, peptides, polypeptides, and proteins.

The Cost of Transacting

Abstract: Introduction, 33. — The definition and measurement of transaction cost on the New York stock exchange, 35. — The determination of the ask-bid spread, 40. — The determination of the transaction rate, 45. — Statistical results, 46. — Summary and comments, 50. — Appendix I, 52. — Appendix II, 53.

Spectral Distribution of Atomic Oscillator Strengths

Abstract: Information on the spectrum of oscillator strength for neutral atoms in their ground states is surveyed with particular regard to recent progress in the far uv-soft x-ray range and to the theoretical interpretation of data from experiments and from numerical calculations. The analysis brings out numerous aspects of atomic mechanics and problems that remain unsolved. An effort is made to interconnect different theoretical approaches within the framework of the theory of atomic spectra.

Dividend Policy: An Empirical Analysis

Abstract: Starting with the “partial adjustment model” suggested by Lintner [10, 11], this paper examines the dividend policies of individual firms. The Lintner model, in which the change in dividends from year t-1 to year t is regressed on a constant, the level of dividends for t-1, and the level of profits for t, explains dividend changes for individual firms fairly well relative to other models tested. But a model in which the constant term is suppressed and the level of earnings for t-1 is added, provides the best predictions of dividends on a year of data not used in fitting the regressions. Though the dividend policy of individual firms is certainly a subject of economic interest, perhaps much of the novelty of the paper is methodological: specifically, the way in which a validation sample, simulations, and prediction tests are used to investigate results obtained from a pilot sample. To avoid spurious results that could follow from the extensive data-dredging involved in finding “good-fitting” divid...

A Theory of the Quasi-Biennial Oscillation

Abstract: A theory is presented which indicates that the quasi-biennial oscillation of the zonal wind in the tropical stratosphere is a result of the interaction of long-period, vertically propagating gravity waves with the zonal wind. We discuss the theoretical basis and observational evidence for the existence of long-period gravity waves near the equator, and the mechanism of their interaction with the zonal wind, and present some simple numerical results which show how the absorption of the momentum of these waves by the mean flow leads to a downward propagating zonal wind profile. It is shown that the interaction of these gravity waves with the observed semiannual zonal wind oscillation above 40 km will produce a downward propagating quasi-biennial oscillation. We present the results of several numerical experiments with a model of the tropical stratosphere which includes the gravity wave interaction mechanism. The quasi-biennial oscillation is simulated quite successfully. Finally, we discuss possibl...

Finite-Width Corrections to the Vector-Meson-Dominance Prediction for ρ → e + e −

Abstract: Finite-width corrections based on a generalized effective range formula for pion-pion scattering modify by a non-negligible amount the well-known relation between $\ensuremath{\Gamma}(\ensuremath{\rho}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})$ and $\ensuremath{\Gamma}(\ensuremath{\rho}\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi})$ derived on the basis of vector-meson dominance. We also present a new current-algebra prediction for the shape and magnitude of $\ensuremath{\sigma}({e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})$ and estimate the $\ensuremath{\rho}$-meson contribution to the Schwinger term.

The Fixed Point Theory of Multi-valued Mappings in Topological Vector Spaces.

Abstract: Introduction Let K be a compact convex subset of a real topological vector space E, which we shall always assume to be separated (i.e. Hausdorff). We consider multi-valued mappings T of K into E, i.e. mappings (in the usual sense) of K into 2 e, the space of subsets of E, where for each x in K, T(x) is a non-empty closed convex subset of E. By a fixed point of such a mapping, we mean a point u of K such that u e T(u). The earliest extension of the topological theory of fixed points of continuous mappings to the case of multi-valued mappings was made by von Neumann [27] in the connection with the proof of the fundamental theorem of game theory. The extension of the Brouwer fixed point theorem to an upper semi-continuous multivalued mapping T of a n-disk into itself was carried through by Kakutani [23] and corresponding extensions of the Schauder fixed point theorem in Banach spaces were given independently by Bohnenblust-Karlin [33 and Glicksberg [193. The corresponding extension of TychonolTs theorem for locally convex topological vector spaces was proved by Ky Fan [12], who in a group of subsequent papers ([13, 14, 15, 16, 17]) refined and extended this result and considered a variety of applications. Asymptotic fixed point theorems for multi-valued mappings in Banach spaces were established in Browder [4], and parts of the Leray-Schauder theory in Banach spaces were extended to multi-valued mappings by Granas [20, 21]. It is our object in the present paper to present a new general treatment of the fixed point theory of multi-valued mappings in topological vector spaces which has the dual virtues of obtaining new and stronger results on the one hand and drastically simplifying the proofs of known results on the other. The starting point of our investigation of this theory lies in recent results of the writer in connection with the study of monotone operators and non-linear variational inequalities [6, 7, 8]. In this direction, one considers mappings S of a compact convex set K into E*, the dual space of E, rather than E itself. Instead of trying to find fixed points of a mapping T of K into E, one looks for points u in K for which S(u)= 0, or more generally, for which

Selective retention of dihydrotestosterone by prostatic nuclei

Abstract: MUCH attention is being given to the effect of gonadal hormones on various biochemical events in the cell nuclei of the target tissues1–7. It is not known whether steroids act directly at nuclear sites; oestradiol-17β seems to associate with nuclear components without alteration of the oestrogen molecule8,9. Ventral prostate can retain androgens to a somewhat greater extent than the blood10,11, but studying the method of androgen retention is complicated by the rapid and multiple transformations of androgens injected into the experimental animals10–12. Consequently, we have asked two simple questions: (1) which metabolite(s) of testosterone can associate with isolated prostatic nuclei; and (2) is such association selective ? The results reported in this paper suggest to us that nuclear chromatin of prostate, but not other tissues which are insensitive to androgen, contains an androgen receptor which can selectively retain dihydrotestosterone (DHT, 5α-androstane-17β-ol-3-one)—the most potent endogenous androgen for the growth of ventral prostate of rat13,14.

The Analysis of Cross-Classified Data: Independence, Quasi-Independence, and Interactions in Contingency Tables with or without Missing Entries

Abstract: (1968). The Analysis of Cross-Classified Data: Independence, Quasi-Independence, and Interactions in Contingency Tables with or without Missing Entries. Journal of the American Statistical Association: Vol. 63, No. 324, pp. 1091-1131.

AZTEC, a Preprocessing Program for Real-Time ECG Rhythm Analysis

Abstract: A preprocessing program developed for real-time monitoring of the electrocardiogram by digital computer has proved useful for rhythm analysis. The program suppresses low amplitude signals, reduces the data rate by a factor of about 10, and codes the result in a form convenient for analysis.

A Field Theory of Currents

Abstract: A new type of model field theory is constructed. Only currents appear as the coordinates. The canonical formalism is abandoned. The self-consistency, Lorentz covariance, energy-momentum conservation, etc., are checked.

Position-effect variegation

Abstract: Publisher Summary This chapter focuses on the cytogenetic aspects of position-effect variegation. One of the diagnostic characteristics of position-effect variegation, at least in Drosophila, is the suppression of the variegation toward wild type upon the addition of a Y chromosome and, conversely, the enhancement of the variegation toward the mutant phenotype upon the deletion of this element. Three facts are mentioned, which suggest that position-effect variegation is operating at the transcriptional, or possibly the translational, level of gene expression. These facts are the ubiquity of genes affected, the cis-trans nature of the effect and the centromere-distance effect. The phenomenon of position-effect variegation is overly blessed with the number of interesting observations that have been made. The position-effect nature of the variegation in the mouse was demonstrated by use of a translocation between the X chromosome and genophore 8 that produced brown variegation. Position-effect variegation in the mouse is always associated with rearrangements of the X, an element that is known to become heteropycnotic in one of the X's of an XX cell. This correlates well with the heterochromatic regions responsible for variegation in Drosophila .

Estradiol-concentrating neurons: topography in the hypothalamus by dry-mount autoradiography.

Abstract: Serial section autoradiograms were prepared of different planes of the hypothalamus and diencephalon of immature female, immature male, and ovariectomized mature rats injected with 6,7-3H-estradiol-17 β. Known causes of diffusion and redistribution of the label, such as fixation, embedding, and thawing, were eliminated by the use of an autoradiographic technique based on the dry-mounting of freeze-dried sections. Neurons that concentrate estradiol exist in distinct and definable anatomical areas that are independent of the sex and hormonal state of the animals. Distribution of these neurons follows known terminations of the stria terminalis, which supports the concept of an endocrine amygdaloid-hypothalamic-hypophysial axis.

Expected search length: A single measure of retrieval effectiveness based on the weak ordering action of retrieval systems

Abstract: A measure of document retrieval system performance called the “expected search length reduction factor” is defined and compared with indicators, such as precision and recall, that have been suggested by other workers. The new measure is based on calculations of the expected number of irrelevant documents in the collection which would have to be searched through before the desired number of relevant documents could be found. Its advantages are: (1) it provides a single index for the property it attempts to measure; (2) it allows for gradations of retrieval status, through the mathematical concept of a “weak ordering”; (3) it evaluates retrieval performance relative to random searching; and (4) it takes into account the amount of relevant material desired by the requester.

The composition and structure of lower silurian marine communities

Abstract: Five benthic communities occupied the shelf regions of the British Isles, Norway, and North America in Upper Llandovery times. The communities are listed below in order of increasing distance from shore. 1 The Lingula Community is the least diverse; it has both infaunal elements, including a protobranch, and two lingulids, and epifaunal elements, including a rhynchonellid, a pterioid, and a cornulitid. A restricted and protected near-shore environment, such as a bay or estuary, is postulated. 2 The Eocoelia Community shares elements in common with the former community, but is more diverse and is dominated by epifaunal forms; the many small pedunculate brachiopods probably lived attached to the large leptostrophiid brachiopod. 3 The Pentamerus Community is dominated by this genus which lived free and upright on the bottom; smaller pedunculate brachiopods probably attached to this large neighbor. 4 The Costistricklandia Community was similar in structure to the former community with the many small pedunculate brachiopods being attached to the large Costistricklandia. 5 The Clorinda Community is the most diverse, with a great variety of small brachiopods which were probably able to attach to small objects in this quiet off-shore environment, or to some moderately sized brachiopods, such as Clorinda and Cyrtia, which apparently lived free on the bottom. The brachiopod dominated communities of the Silurian clearly inhabited the ‘level bottom’, an area now occupied mainly by infaunal forms. The main attachment surfaces for the epifaunal elements of the Silurian communities were disarticulated, convex-upward shells.

Private Speech: Four Studies and a Review of Theories

Abstract: Similarities and differences in the views of private or egocentric speech held by Piaget, Vygotsky, G. H. Mead, and Flavell are examined. These views are related to previous findings and to four new studies of the effects of age, IQ, and task difficulty upon private speech in various natural and experimental settings. These studies support the "cognitive development" interpretation common to all the theorists in that mental age and task difficulty were found to be primary and regular determinants of private speech in contrast to such factors as sex, nationality, or chronological as opposed to mental age. The findings also support Vygotsky's belief that private speech has a curvilinear course of development (due to its functioning as a transition from outer speech to thought) as opposed to Piaget's view that it declines monotonically with cognitive and social maturity. 7 types of private speech are defined and evidence is presented suggesting that they form a developmental hierarchy consistent with Mead's view of the transformations of external communication to inner thought.

Interchain hydrogen bonds via bound water molecules in the collagen triple helix

Abstract: If the collagen triple helix is so built as to have one set of NH O hydrogen bonds of the type N3H3(A) O2(B), then it is possible to have a linkage between N1H1(B) and O1(A) through the intermediary of a water molecule with an oxygen O leading to the formation of the hydrogen bonds N1(B) O and O (A). In the same configuration, another water molecule with an oxygen O can link two earbonyl oxygens of chains A and B forming the hydrogen bonds O O1(A) and O O0 (B). The two water oxygens also become receptors at the same time for CH O hydrogen bonds. Thus, the neighboring chains in the triple helix are held together by secondary valence bond linkages occurring regularly sit intervals of about 3 A along the length of the protofibril. The additional water molecules occur on the periphery of the proto-fibril and will contribute their full share towards stabilizing the structure in the solid state. In solution, they will be disturbed by the medium unless they are protected by long side groups. It appears that this type of two-bonded structure, in which one NH O bond is to a water molecule, can explain several observations on the stability and hydrogen exchange properties of collagen itself and related synthetic polypeptides. The nature of the water bonds and their strength are found to be better in the one-bonded structure proposed from Madras than in the one having the coordinates of Rich and Crick.

Self-differentiation of the basic patterns of coordination

Abstract: Experiments are described in which the method of transplantation of muscles and nerves was used to analyze the origin and, in certain regards, the operation of motor coordination in amphibians. The results support a preformistic concept of coordination in these forms. A basic repertoire of primary motor patterns develops during the developmental phase. These arise essentially by self-differentiation within the central nervous system, independent of the benefits of sensory control and guidance by experience. They are so predesigned that, when later projected into an anatomically normal peripheral effector system, they produce biologically adequate effects. If confronted, however, with an anatomically disarranged periphery, they produce correspondingly distorted effects without signs of corrective adjustment. The relation of these facts to the phenomenon of “plastic” coordination observed in man and higher mammals, and their bearing on the theories of coordination is discussed.

The stability of thermally stratified plane Poiseuille flow

Abstract: In studying the stability of a thermally stratified fluid in the presence of a viscous shear flow, we have a situation in which there is an important interaction between the mechanism of instability due to the stratification and the Tollmien-Schlichting mechanism due to the shear. A complete analysis has been carried out for the Benard problem in the presence of a plane Poiseuille flow and it is shown that, although Squire's transformation can be used to reduce the three-dimensional problem to an equivalent two-dimensional one, a theorem of Squire's type does not follow unless the Richardson number exceeds a certain small negative value. This conclusion follows from the fact that, when the stratification is unstable and the Prandtl number is unity, the equivalent two-dimensional problem becomes identical mathematically to the stability problem for spiral flow between rotating cylinders and, from the known results for the spiral flow problem, Squire's transformation can then be used to obtain the complete three-dimensional stability boundary. For the case of stable stratification, however, Squire's theorem is valid and the instability is of the usual Tollmien—Schlichting type. Additional calculations have been made for this case which show that the flow is completely stabilized when the Richardson number exceeds a certain positive value.

Nonlinear Maximal Monotone Operators in Banach Space.

Abstract: Such a set G is said to be maximal monotone if it is maximal among monotone sets in the sense of inclusion, and a mapping T is said to be maximal monotone if its graph G(T) is a maximal monotone set. If D(T) is convex and T is hemicontinuous from D(T) to X* (i.e. T is continuous from each line segment of D(T) to the weak* topology of X*), then T is maximal monotone if and only if it is maximal in the sense of operator inclusion in the family of monotone mappings from X to X*. For operators T with D(T) = X , the basic result obtained independently by BROWNER [5] and MINTY [31] states that for a reflexive space X, if T is a hemicontinuous monotone operator from D(T) = X to X* and if in addition, T is coercive, i.e.

Covalent Bond in Crystals. I. Elements of a Structural Theory

Abstract: An a posteriori theory is developed for the structural energy of covalent crystals. The microscopic theory is based on ionic pseudopotentials and valence dielectric screening. The theory explains the difference between empirical pseudopotential form factors derived from the optical spectra of semiconductors and the metallic form factors calculated from free-ion term values by Animalu and Heine. A byproduct of the theory, which utilizes Penn's model isotropic semiconductor dielectric function, is a relation between the covalent bonding charge and the macroscopic dielectric constant. In self-consistent form the theory is an example of the "bootstrap" approach, applied here to treat the effect of covalent bonding on the ground-state energy of the valence electron gas. It is argued that the axiomatic character of the covalent theory is to be expected on symmetry grounds, and it is shown that the theory is superior to a nonlinear multiple-scattering theory based on the free-electron dielectric function. The extension of the theory to III---V and II---VI semiconductors is described briefly. The theory may be used to calculate elastic and macroscopic dielectric properties of covalent crystals starting only from ionic pseudopotential form factors.

Properties of the protein subunit of central-pair and outer-doublet microtubules of sea urchin flagella.

Abstract: The subunit protein has been isolated from the central-pair and outer-doublet microtubules of sea urchin sperm tails Both proteins have a sedimentation constant of 6S and a molecular weight of 120,000 Both are converted to a 60,000 molecular weight species by denaturation in 6 M guanidine hydrochloride and reduction with mercaptoethanol The reduced-alkylated proteins have the same Rf on disc electrophoresis, and the same amino acid composition, which is very similar to that of muscle actin The central-pair protein has one binding site for colchicine per 120,000 g Both proteins appear to have a guanine nucleotide binding site, but the ability to bind GTP in solution has been demonstrated only for the central-pair protein Although 1 mole of guanine nucleotide is bound per 60,000 g to outer-doublet tubules, the protein obtained by dissolving the doublets at pH 105 has lost the guanine nucleotide-binding site and also shows little or no colchicine-binding activity Comparison of the properties of the isolated protein with electron microscopic evidence on structure of microtubules suggests that the chemical subunit (M = 120,000) consists of two of the 40 A morphological subunits