Showing papers by "University of North Carolina at Chapel Hill published in 1974"

Quad trees a data structure for retrieval on composite keys

Abstract: The quad tree is a data structure appropriate for storing information to be retrieved on composite keys. We discuss the specific case of two-dimensional retrieval, although the structure is easily generalised to arbitrary dimensions. Algorithms are given both for staightforward insertion and for a type of balanced insertion into quad trees. Empirical analyses show that the average time for insertion is logarithmic with the tree size. An algorithm for retrieval within regions is presented along with data from empirical studies which imply that searching is reasonably efficient. We define an optimized tree and present an algorithm to accomplish optimization in n log n time. Searching is guaranteed to be fast in optimized trees. Remaining problems include those of deletion from quad trees and merging of quad trees, which seem to be inherently difficult operations.

A behavior rating scale for the preschool child.

Abstract: The increase in the number of children attending preschools or day care centers has provided an opportunity for early detection of emotional problems. However, few screening instruments have been standardized for children in this age group. A modification of Rutter's Children's Behaviour Questionnaire was standardized on a sample of 496 normal and 102 disturbed preschool children. The modified questionnaire (renamed the Preschool Behavior Questionnaire) was found to possess criterion validity and high interrater and test-retest reliabilities. Three factors were extracted and were labeled Hostile-Aggressive, Anxious-Fearful, and HyperactiveDistractible. The data indicated that the Preschool Behavior Questionnaire may be valuable in either clinical or research settings for the first step in early detection of emotional problems.

A Revised Definition for Suppressor Variables: a Guide To Their Identification and Interpretation:

Abstract: In the two-predictor situation it is shown that traditional and negative suppressors increase the predictive value of a standard predictor beyond that suggested by the predictor's zero order validi...

Maternal inheritance of mammalian mitochondrial DNA

Abstract: EUKARYOTIC cells contain a class of cytoplasmic DNA molecules which are found only within the mitochondria, where they replicate and are transcribed (for a general review see ref. 1). This mitochondrial DNA (mtDNA) constitutes the ‘mitochondrial genome’ and carries genetic information essential to mitochondrial function. In view of its extranuclear location, it is not surprising that inheritance of the mitochondrial genome is not governed by the same rules that apply to chromosomal genes. For fungi2–7 and amphibians8 there is evidence that the mitochondrial genome of an individual is derived solely from the maternal parent (in contrast to chromosomal genes, which are inherited biparentally). We present here evidence that the mitochondrial genome is inherited maternally in mammals too.

Methane production in the interstitial waters of sulfate-depleted marine sediments.

Abstract: Methane in the interstitial waters of anoxic Long Island Sound sediments does not reach appreciable concentrations until about 90 percent of seawater sulfate is removed by sulfate-reducing bacteria. This is in agreement with laboratory studies of anoxic marine sediments sealed in jars, which indicate that methane production does not occur until dissolved sulfate is totally exhausted. Upward diffusion of methane or its production in sulfate-free microenvironments, or both, can explain the observed coexistence of measurable concentrations of methane and sulfate in the upper portions of anoxic sediments.

Characterization of the Insulin and Somatomedin-C Receptors in Human Placental Cell Membranes

Abstract: Human placentas have been used to further investigate the binding of insulin and somatomedin to cell membrane receptors. Conditions for optimal binding of 125I-insulin were defined for both participate membrane preparations and membranes solubilized in Triton X-100. Human placental membranes are a rich source of high affinity insulin receptors. As in previous studies with rat liver and fat cell preparations, only somatomedin and proinsulin were effective competitors for binding to the insulin receptor. These findings were used to define the optimal conditions for a competitive binding assay for insulin and insulin-like peptides. This assay had threshold sensitivities of 10 μU/ml for insulin and less than 0.1 U/ml for somatomedin. Incubation at 4 C for 15–18 hr essentially eliminated proteolytic degradation of the labeled hormone and led to strikingly better binding than was observed at higher temperatures. A highly purified preparation of somatomedin-C labeled with radioactive iodine was found to...

Empirical Evidence on the Functional Form of the Earnings-Schooling Relationship

Abstract: This article presents empirical evidence on the correct functional form of the regression relationship between earnings as regressand and schooling and experience as regressors. Evidence from several bodies of data suggests that among simple transformations the natural logarithm of earnings is the correct dependent variable while the best simple specification of the regressors is one advanced by Jacob Mincer on theoretical grounds.

The Somatomedins: A Family of Insulinlike Hormones under Growth Hormone Control

Abstract: Publisher Summary This chapter explains that growth hormone itself exercises no direct metabolic action on skeletal tissue, but rather acts through a second substance, which is detectable both in normal plasma and in plasma from hypophysectomized rats after growth hormone administration. The term sulfation factor is applied to this plasma activity because the assay used for its detection depends upon the in vitro incorporation of radioactive sulfate into proteoglycans of cartilage. The chapter describes with evidence that several distinct growth hormone dependent substances are responsible for the biological activity of plasma in sulfation factor assays and that these substances are all insulin-like; thus, these substances are components of non-suppressible insulin-like activity (NSILA). These insulin-like growth-promoting peptides has much in common with the elusive serum growth factors that are required for the proliferation of cells in tissue culture. The chapter also discusses that the sulfation factor plays a much more pervasive role in somatic growth. The term somatomedin encompasses all growth hormone-dependent plasma factors that mediate the growth of responsive tissues..

On extreme values in stationary sequences

Abstract: In this paper, extreme value theory is considered for stationary sequences ζn satisfying dependence restrictions significantly weaker than strong mixing. The aims of the paper are: (i) To prove the basic theorem of Gnedenko concerning the existence of three possible non-degenerate asymptotic forms for the distribution of the maximum Mn = max(ξ1...ξn), for such sequences. (ii) To obtain limiting laws of the form $$\mathop {\lim }\limits_{n \to \infty } \Pr \{ M_n^{(r)} \underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{ \leqslant } u\} = e^{ - \tau } \sum\limits_{s = 0}^{r - 1} {\tau ^s /S!} $$ where Mn(r)is the r-th largest of ξ1...ξn, and Prξ1>un∼Τ/n. Poisson properties (akin to those known for the upcrossings of a high level by a stationary normal process) are developed and used to obtain these results. (iii) As a consequence of (ii), to show that the asymptotic distribution of Mn(r)(normalized) is the same as if the {ξn} were i.i.d. (iv) To show that the assumptions used are satisfied, in particular by stationary normal sequences, under mild covariance conditions.

The art of natural graphic man—Machine conversation

Abstract: The design of interactive graphic systems whose aim is good symbiosis between man and machine involves numerous factors. Many of those factors can be judged from the perspective of natural spoken conversation between two people. Guiding rules and principles for design of such systems are presented as a framework for a survey of design techniques for man-machine conversation. Attention is especially focused on ideas of action syntax structuring, logical equivalences among action devices, and avoidance of psychological blocks to communication.

Androgen transport and receptor mechanisms in testis and epididymis

Abstract: Spermatogenesis is an androgen dependent process which can be maintained in hypophysectomized rats by the administration of either testosterone (1) or 5α-dihydrostestosterone (2). Gonadotrophins may exert their effects on spermatogenesis indirectly by way of androgens. The sole action of LH appears to result from the stimulation of testosterone synthesis by the interstitial cells of Leydig. FSH is necessary for the full maintenance of spermatogenesis, but its effects can be mimicked by androgen and blocked by the anti-androgen, cyproterone, indicating that its action is linked in series with androgen (1) or that androgen is the mediator of FSH action.

Evidence for involvement of 5-hydroxytryptamine in the actions of amphetamine.

Abstract: 1 Pargyline treatment, 1 h before (+)-amphetamine (1 mg/kg), reduced amphetamine-stimulated motor activity. This inhibition was reversed in animals pretreated with p-chlorophenylalanine (PCPA). 2 Following treatment with PCPA or 5,6-dihydroxytryptamine (5,6-DHT), amphetamine-induced locomotor activity was significantly potentiated. The increased response to amphetamine in PCPA-treated rats was reversed in animals pretreated with 5-hydroxytryptophan. 3 The inhibition of amphetamine-stimulated locomotor activity by treatment with 6-hydroxydopamine was not reversed by PCPA treatment. 4 Stereotypies produced by amphetamine were not found to be altered by depletion of 5-hydroxytryptamine. 5 Induction of adrenal tyrosine hydroxylase activity produced by chronic amphetamine administration was significantly potentiated by PCPA, emphasizing the involvement of a 5-hydroxytryptamine inhibitory system in more than one action of amphetamine.

Reactions of Participants and Observers to Modes of Adjudication1

Abstract: An important aspect of conflict resolution by judgment of a third party is the extent to which participants and observers are satisfied that both the procedure and the outcome are fair and impartial. Male undergaduates participated in a business simulation, which resulted in a controversy placing them in the position of defendants in a trial. An examination was then made of the effects of adversary and nonadversary procedures, prior belief about guilt, and favorableness of the judgment on participant subjects’ perceptions of the adjudication. Another group of subjects who had no prior information about the guilt or innocence of the defendent served as observers. Participant subjects viewed the adversary procedure as most fair and satisfying. They were also most satisfied with judgments resulting from the adversary procedure, independently of pretrial belief or favorableness of verdict. Participants also preferred innocent to guilty verdicts, regardless of their pretrial belief. Subjects who held a pretrial belief of innocence were particularly dissatisfied with guilty verdicts and with the nonadversary trial procedure. Observers also found the adversary procedure to be most fair, and expressed a preference for innocent verdicts.

Sympathetic Influences on Cardiac Rate and Contractility During Acute Stress in Humans

Abstract: Experiments are reported concerning an evaluation of sympathetic influences on heart rate and cardiac contractility in normal young adult humans during a stressful reaction time task. During the preparatory interval only vagal influences on heart rate change could be found which were related to concomitant somatic activity. In expectation of the shock and for a more sustained period thereafter, sympathetic influences became manifested on both heart rate and contractility which were independent of concomitant somatic activity. In a follow-up study, the relationship was evaluated between blood pressure, as measured directly from the radial artery, and both contractility and heart rate. Sympathetic influences on the heart were not found to be secondary to depressor effects, although appreciable phasic decreases in blood pressure were sometimes found to follow the onset of large increases in heart rate and contractility. The data suggest that sympathetic influences on the heart are normally very minimal but are evoked by intense stress when the organism attempts to cope with the stress.

Purposes of a Phenology Book

Abstract: This volume’s authors make a case for phenology—not so much for phenology as it is commonly understood (a field technique of agricultural meteorology), but as an aspect of analysis and management of ecological systems or ecosystems. We have indicated its importance earlier (e.g., Lieth, 1970, 1971; Lieth and Radford, 1971) but our experience is mostly confined to plant-environment relations. Ecosystems require more comprehensive study.

The Relation of Cognitive and Memorial Processes to Persuasion in a Simulated Jury Trial

Abstract: Four experiments investigated the dependence of persuasion on cognitive factors. All experiments employed a court case for which 795 subjects acted as jury members, reading summaries of both the prosecution and defense's testimony. The amount of objective information on both sides of the case was varied. Persuasion was a position function of the number of prosecution arguments and the number of defense arguments. This finding was extended by obtaining measures of the subjects’cognitive reactions to the case as well as their opinions and by following both of these measures over time. Both analysis of variance and multiple regression techniques showed that subjects could have derived their opinions from their cognitions about the case. This relationship also held up over time. These results suggest the general form of an information-processing theory of persuasion. One prediction of this theory is for an asymptotic function relating objective information to persuasion. This prediction received empirical support.

Human Errors in Programming

Abstract: This study attempts to systematize the description of the errors that programmers make. By collecting protocol data from 42 programmers, some insights concerning the relative importance of various programming errors are achieved. These insights are interpreted in terms of programmer experience and the design and redesign of general purpose, compiler-type programming languages.

Comparison of tyrosine hydroxylase and dopamine-Β-hydroxylase inhibition with the effects of various 6-hydroxydopamine treatments on d-amphetamine induced motor activity

Abstract: The significance of central noradrenergic and dopaminergic neural systems for the locomotor stimulant effects of d-amphetamine were investigated in rats with depletions of norepinephrine, dopamine, or both catecholamines produced by treatment with either reserpine, L-α-methyl-tyrosine (α-MPT), 6-hydroxydopamine (6-OHDA), or the dopamine-Β-hydroxylase inhibitor 1-phenyl-3-(2-thiazolyl)-2-thiourea (U-14,624) In animals pretreated with reserpine, amphetamine-stimulated locomotor activity was blocked by Β-MPT but not by U-14,624 when amphetamine was given l h after these catecholamine synthesis inhibitors In rats with chronic depletions of brain norepinephrine, dopamine, or both catecholamines produced by different 6-OHDA treatments, both amphetamine-stimulated motor activity and stereotyped behavior were antagonized by treatments reducing dopamine or both catecholamines but not in animals in which brain norepinephrine was reduced Results are consistent with the view that the locomotor stimulation and stereotyped behaviors produced by d-amphetamine are dependent upon functional dopaminergic neural systems in brain

Nucleolar and perichromosomal RNA synthesis during meiotic prophase in the mouse testis.

Abstract: The transcriptional activity during meiotic prophase in the mouse testis is studied with light microscopy and high-resolution autoradiographic techniques using [3H]uridine as a labeled precursor. In the present study, two types of RNA synthesis are detected during meiotic prophase: an extranucleolar RNA synthesis of perichromosomal localization and a nucleolar RNA synthetic activity. In some of the autosomes and close to the basal knobs, the activity of the nucleolar organizers is evidenced by the incorporation of [3H]uridine into nucleolar masses from zygotene on and at earlier labeling times. The evolution of nucleoli and the formation of a nucleolus attached to the sex pair are described during the different meiotic stages. Perichromosomal labeling, from leptotene on, reaches a maximum during middle pachytene and falls progressively to a low level at longer incorporation times. Sertoli's cell, the most active RNA synthetic cell in the seminiferous epithelium, rises to a maximum of labeling and drops at earlier times compared with the meiotic prophase cells. The condensed sex chromosomes show some scattered silver grains especially at middle pachytene. The axial chromosome cores and synaptonemal complexes are devoid of silver grains during the meiotic prophase. The observations suggest that a control mechanism operates during meiotic prophase to regulate transcriptional activity in the sex chromosomes and to provide differential RNA synthesis in autosomal bivalents at various stages of prophase and within certain segments of the chromosomes.