Showing papers by "University of Alberta published in 1983"

Firm internationalization, transaction costs and strategic choice

Abstract: Export expansion is usually conceptualized as a progressive organizational commitment ultimately leading to an international enterprise. However, such deterministic export behavior models are irreconcilable with a perspective which sees businesses as developing export structures to fit existing and potential foreign market opportunities. This paper examines how the formal administrative arrangements that firms use for conducting foreign trade are peculiarly fitted to achieve specific export performances. It shows how changes in these arrangements represent primarily organizational strategies for handling export transaction costs more efficiently.

DNA-binding proteins

Abstract: The structures of three proteins that regulate gene expression have been determined recently and suggest how these proteins may bind to their specific recognition sites on the DNA. One protein (Cro) is a repressor of gene expression, the second (CAP) usually stimulates gene expression, and the third (lambda repressor) can act as either a repressor or an activator. The three proteins contain a substructure consisting of two consecutive alpha helices that is virtually identical in each case. Structural and amino acid sequence comparisons suggest that this bihelical fold occurs in a number of proteins that regulate gene expression, and is an intrinsic part of the DNA-protein recognition event. The modes of repression and activation by Cro and lambda repressor are understood reasonably well, but the mode of action of CAP is still unclear.

Dominance and reproductive success in primates

Abstract: Theoretical models of the relationship between competition and differential reproduction in primates share the premise that agonistic dominance hierarchies determine differential access to those limited resources which are essential to reproduction. In particular, the priority-of-access-to-estrous-female model is based on the postulate that high rank in males enhances reproductive success. Tests for a correlation between rank and reproductive success in males have produced mixed results. Problems in measuring male reproductive success and in conceptualizing dominance systems are implicated in the diversity of conclusions reached. Other attributes which affect reproductive success have been proposed, and alternative models of mating systems, based on the concepts of reproductive strategies, social skills, and life histories have also been developed. Studies of differential reproduction in female primates are fewer, but have the advantage over male studies of directly measuring infant production and offspring survival. Research on the relationship between rank and reproductive success in females has shown that under conditions of low resource availability, subordinate females sometimes suffer reduced fecundity and infant survival as a result of restricted access to food and water. Under conditions of social stress, low-ranking females may suffer from disruption of their reproductive cycles, resulting in lowered fecundity. Dominant females may also incur reproductive costs as well as benefits for their social position. Better insights into the relationship between dominance and reproduction are potentially offered by improved genetic paternity measures, new models of social and demographic processes, and the recent availability of life history data from field studies.

Effect of Heat Stress During Floral Development on Pollen Tube Growth and Ovary Anatomy in Wheat (Triticum aestivum L.)

Abstract: Wheat plants (cv. Gabo) otherwise grown at 20°C were subjected to a temperature of 30°C for 3 days at the onset of meiosis in the anthers. Control plants were maintained at 20°C throughout development. Serial sections through the heat-stressed ovaries just prior to anthesis showed that a third contained abnormal embryo sacs. Abnormalities ranged from the complete absence of an embryo sac accompanied by reduced nucellus development, to small embryo sacs that contained the full complement of cells. No abnormalities were observed in control ovaries. Following pollination with fertile pollen, heat-stressed stigmas had similar numbers of germinated pollen grains to non-stressed controls but there were fewer tubes reaching the ovary. In 7% of the stressed pistils, no pollen tube reached the ovary. Callose was deposited in some of the inhibited pollen grains and tubes that showed abnormal growth. It is concluded that heat stress during meiosis in wheat can reduce yield by causing abnormal ovary development, which results in reduced pollen tube growth and seed set.

A theory of activity-based anorexia

Abstract: The present paper documents the etiological importance of physical activity to self-starvation in animals and suggests similarities between this research area and the literature concerned with some self-starvation in humans. An activity anorexia is proposed that may account for 38% to 75% of anorexia nervosa. An account of excessive locomotor activity is made in terms of schedule-induced behavior. A reciprocally interactive effect of activity and food ingestion is taken to explain self-starvation for animals and activity anorexia in humans. Literature is reviewed which demonstrates that rats and mice self-starve when they are given access to a running wheel and placed on food restriction. In this paradigm, these animals become excessively active and paradoxically reduce food consumption when compared with control subjects. This evidence and related findings are shown to be consistent with a phylogenetically based model of anorexia. Sociocultural factors are hypothesized to set and maintain the conditions that produce activity anorexia in humans.

1 Hormones, Pheromones, and Reproductive Behavior in Fish

Abstract: Publisher Summary The role of hormones in the regulation of various aspects of reproductive behavior has been reported by a number of researchers. This chapter discusses the more recent studies, particularly those dealing mainly with the role of endocrine factors as determinants of reproductive behavior. The chapter emphasizes the two-way nature of the relationship between the endocrine system and the biological and physical environment. Not only does the endocrine system regulate the behavioral responses necessary for successful reproduction, but it is also responsive to social and other exogenous stimuli. The smooth progression through the reproductive cycle depends on the continuing interplay between the endocrine system and the environment. In effect, behavior provides the link between the organism and its environment. As in all vertebrates, with the possible exception of the cyclostomes, a fundamental feature of the fish endocrine system is the interdependence of the hypothalamus, pituitary, and gonads: The hypothalamus–pituitary–gonadaxis (HPG).

A simple apparatus for measuring gas production by methanogenic cultures in serum bottles

Abstract: The construction and use of an apparatus for measuring gas production in methanogenic cultures is described. The device consists of two glass syringes and two 3‐way stopcocks assembled and connected to a water manometer. Measurements of known amounts of methane added to serum bottles gave recoveries between 96 and 101%.

Structural relationships between spines and lateral plates in threespine stickleback (gasterosteus aculeatus).

Abstract: Of the five genera of stickleback (Gasterosteidae), Casterosteus has the longest dorsal and pelvic spines and the most extensive expression of lateral bony plates (Nelson, 1971). Spines, which can be locked into an erect position (Hoogland, 1951), enlarge the effective body diameter of the stickleback and may pierce the mouthparts of a predator during manipulation, increasing the opportunity for escape (Hoogland et al., 1957). As might be expected, in localities where predatory fish are common, the stickleback spines are relatively longer than in populations where such predators are rare or absent (Hagen and Gilbertson, 1972; Gross, 1978a). Numbers of lateral plates are also geographically variable (for review see Bell, 1976; Wootton, 1976). Most marine populations have a row of 35 lateral plates on each side of the body extending from the head to the caudal peduncle (Fig. 1a). These plates are greatly reduced in number in many freshwater populations in western North America and southwest Europe. While populations are known in which fish lack all lateral plates (Miller and Hubbs, 1969; Moodie and Reimchen, 1973), the majority have from three to eight plates per side in the anterior region of the body (Fig. 1b). Early investigators (Bertin, 1925) considered this variation to be environmentally induced, but subsequent genetic analysis showed that a large component of the variance is heritable (Munzing, 1959; Lindsey, 1962; Hagen, 1973; Hagen and Gilbertson, 1973a; Avise, 1976). However, the adaptive significance

Interneurons in the flight system of the locust: distribution, connections, and resetting properties.

Abstract: The organization and functional properties of interneurons in the flight system of the locust, Locusta migratoria, were investigated by using intracellular recording and staining techniques. Interneurons were found to be distributed within the three thoracic and the first three abdominal ganglia, and they could be subdivided into three organizational categories: (1) members of one of two serially homologous groups controlling either the forewing or the hindwing, (2) unique individuals with no known homologues in other ganglia, and (3) members of a set of serial homologous in the metathoracic and first three abdominal ganglia. Interneurons in the last two categories influenced both forewing and hindwing motoneurons in a similar manner. Thus interneuronal organization is not characterized by two distinct homologous groups of interneurons for the separate control of forewing and hindwing motor activity. Flight interneurons may also form two separate functional categories: (1) those making short latency connections to motoneurons (premotor interneurons), and (2) those which reset the flight rhythm when depolarized by brief current pulses (pattern generator interneurons). None of the ten premotor interneurons we identified influenced the flight rhythm when depolarized and none of the three groups of pattern generator interneurons were found to form short latency connections with motoneurons. This separation of function may allow phase-shifts in motor output for flight control without changes in wingbeat frequency. Pattern generator interneurons influence motor output to both forewings and hindwings. Thus we conclude that the flight rhythm is generated in a distributed neuronal oscillator driving both the pairs of wings. The organization of flight interneurons is considerably more complex than predicted from existing models of the flight system, or anticipated from the relative simplicity of the motor output. Our finding of homologous sets of interneurons in the abdominal ganglia supports the notion that insect flight evoked from a behavior using appendages distributed along the thorax and the abdomen. Thus the organization of flight interneurons may reflect an interneuronal system which controlled the behavior from which flight evolved.

Partitioning: the emergence of rational number ideas in young children

Abstract: The study sought to trace the emergence and differentiation of partitioning as a process that leads young children to construct ideas of rational numbers. The method involved clinical sessions with children as they manipulated materials while solving tasks designed to reveal partitioning processes. The data analysis led to a theory concerning the emergence of partitioning capability, and conceptual structures that undergird the capability were identified. A five-level theory of the development of the partitioning process is presented. Key position papers by Kieren (1976, 1980) have created a new theoretical context for inquiring into the child's acquisition of rational number concepts. Recent work within the new perspective (Kieren & Nelson, 1978; Kieren & Southwell, 1979) has lent support to Kieren's position. Basic in Kieren's perspective is the process of dividing a whole into parts, a process variously referred to as partitioning, subdivision, or dissection. The purpose of the present study was to trace the emergence and differentiation of the process of partitioning as revealed in children's attempts to subdivide a continuous whole into equal parts. METHOD The method involved a clinical interaction with a child as he or she grappled with tasks specifically designed to reveal partitioning capabilities. As the child grappled with the tasks, the researchers grappled with the even more complex task of attempting to make sense of the child's behavior. We hoped to discover underlying patterns that would help us trace the emergence and differentiation of the partitioning process. The method can be characterized as a clinical interaction technique set within a discovery paradigm. The interactive encounters were designed to yield insights rather than to verify hypotheses; validity, as opposed to generalizability, was our concern. The interaction was characterized by flexibility in questioning. The initial question for each task was standard, but the subsequent questions, although following a general pattern, were varied, as were the numbers in the problem, depending on the behavior of the child. The method permitted probing,

Towards a descriptive theory of management accounting

Abstract: This paper draws on the agency theory and on the markets and hierarchies literature to provide an elaborated view of the contingency theory of organizations. Several MAS implications of this elaborated view are presented. One implication is that MAS may serve a constitutional like role withing organizations. This constitutional role for MAS encourages cooperation and facilities control. The constitutional role which MAS measures play, may serve to explain why many MAS measures and practices resist change.

Nucleoside transport in animal cells.

Abstract: Nucleosides have a mult i tude of biochemical and physiological effects. For example, adenosine is believed to participate in processes such as modulation of immune response% regulation of blood flow, p late let aggregation, renal function, neuromodulation in the central nervous system, neurotransmission, muscle contraction, and numerous other biological processes ( i -3 ) . Inosine has been postulated as an in vivo energy source for adult pig erythrocytes, ceils unable to metabolize glucose (4 ,5) . In addit ion, nucleoside analogues are widely used as the rapeu t i c agents for neoplas t ic and viral diseases in man and to a lesser ex t en t as an t iparas i t ic agents (6) . However , be fore the above biological e f f e c t s of nucleosides and their analogues are in i t ia ted these c o m p o u n d s have general ly to be t ranspor ted out of or into cells. Thus , n u c l e o s i d e t rans loca t ion is an impor tan t de t e rminan t of the biological ac t iv i ty of nucleosides and nucleoside drugs. This review is no t a c o m p r e h e n s i v e survey of the large l i t e r a tu re on nucleoside uptake; for this readers should re fe r to two r ecen t review ar t ic les (7~g). Instead, we have a t t e m p t e d to highlight and discuss r ecen t o b s e r v a t i o n s r e l e v a n t to the g e n e r a l m e c h a n i s m s of nuc leos ide t r a n s p o r t . Most of t h e s e o b s e r v a t i o n s c o m e f ro m s t u d i e s on mammal ian red cells and as a consequence this review will c o n c e n t r a t e mainly on the proper t ies of the nucleoside t r anspor t e r in e r y t h r o c y t e s . In p a r t i c u l a r , we discuss the kinet ics and inhibition of nucleoside transport~ the proper t ies of the speci f ic potent nuc leos idet ranspor t i n h i b i t o r n i t r o b e n z y l t h i o i n o s i n e ( 6 [ L t n i t r o b e n z y l t h i o l ] 9 B D-r ibofuranosylpur ine; NBMPR)9 the regulat ion of nucleoside t ranspor t , and the molecular proper t ies of the t r anspor te r .

Pure states, polarized waves, and principal components in the spectra of multiple, geophysical time-series

Abstract: Summary This paper outlines the connection between pure states, polarized waves, and principal components in the spectral representation of multichannel or multivariate geophysical time series. If a wave is a pure state or a polarized wave (e.g. a teleseismic P-wave), the multidimensional spectral representation can be reduced to a one-dimensional spectral representation. The objective of this paper is to develop estimators of the spectral representations of these pure states, which are based on a number of optimality criteria. If nothing is known about the noise in the data, then an estimator similar to the principal components of real multivariate analysis is most useful. If some knowledge of the spectral density matrix of the noise is available, then a number of other optimality criteria can be used. Minimization of the prediction error in the spectral representation of the pure states leads to estimators similar to those used to estimate factor-scores in factor-analytic methods. These estimators of the spectral representations of polarized waves should be extremely useful to the geophysical experimenter because they allow a more objective evaluation of the parameters of the wave, and because they allow the multichannel data to be filtered to extract polarized waves, without specific knowledge of the type of polarization (e.g. elliptical or linear, and orientation of polarization ellipse). Some practical examples using spectral representations of ULF (1–20 mHz) magnetic fields are given in order to illustrate the usefulness of these methods in interpreting multichannel data.

Choice, matching, and human behavior: A review of the literature

Abstract: This review concerns human performance on concurrent schedules of reinforcement Studies indicate that humans match relative behavior to relative rate of reinforcement Herrnstein's proportional matching equation describes human performance but most studies do not evaluate the equation at the individual level Baum's generalized matching equation has received strong support with humans as subjects This equation permits the investigation of sources of deviation from ideal matching and a few studies have suggested variables which control such deviations in humans While problems with instructional control are raised, the overall findings support the matching law as a principle of human choice

Initial stages of visual information processing in dyslexia.

Abstract: Four experimental tasks were employed to explore the initial stages of visual information processing in a group of dyslexic boys and in a group of normal control subjects ranging in age from 8 to 14 years. Two tasks involved visual backward masking; the other two were temporal integration tasks. The backward-masking tasks yielded evidence of slower rates of visual information processing in dyslexic children; the temporal-integration tasks yielded evidence of longer duration of visible persistence in dyslexic children. This effect was most evident in situations in which sequential stimuli impinged on the same retinal location. Some age trends in the development of these effects are noted. It is suggested that the dyslexic visual system may take an unusually long period of time to recover from the aftereffects of neural activity evoked by an inducing stimulus. Language: en

3 The Brain and Neurohormones in Teleost Reproduction

Abstract: Publisher Summary This chapter discusses the input of information to the neurohormonal system, and describes how the brain might integrate neurohormone output to regulate reproductive activity. This requires analysis of both the elements of the system and the manner by which the neuroendocrine system functions as a unit to regulate the various stages of the reproductive cycle. However, the major problem of such a functional approach is that it leaves the matter unsettled because of the limited amount of information available, and because of the large number of questions that remain. Photoperiod is an important environmental cue for regulation of the reproductive cycles of many teleosts. The pineal and/or eyes are the presumed route of input of photoperiod information. Input of physiological factors is regulate by the steroid feedback. The positive-feedback effect of estrogens, stimulating synthesis and accumulation of gonadotropin (GtH) in the pituitary, is probably an important part of the regulation of onset of puberty. Spermiating salmonids have relatively high blood levels of GtH compared to earlier phases of the reproductive cycle. Male goldfish and carp have an increase in blood GtH levels during participation in spawning; this coincides with an increase in the expressable sperm volume in goldfish. Although these changes in blood GtH are not as dramatic as those found in the females of these species, various evidence indicates that the same neurohormones are present and have similar actions in both sexes of a given species.

The mechanism of action of quinone antibiotics.

Abstract: The review describes recent studies designed to elucidate the molecular mechanism of action of certain quinone antibiotics which exhibit or have potential for clinical treatment of malignant diseases. Although a large number of quinone antibiotics has been described the review will concentrate on four types, the anthracyclines, the mitomycins, streptonigrin, and the saframycin antibiotics because of their biological significance and because the understanding of their underlying modes of action is perhaps more advanced than in the case of other antibiotics. It will be evident that although the antibiotics bear a common quinone moiety this does not confer a commonality of mechanism. Indeed the variety and precision of the different chemical lesions induced by quinone antibiotics on nucleic acids, their principal cell targets, is remarkable. The particular lesions identified include (i) equilibrium binding, (ii) ‘permanent’ single covalent attachment, (iii) reversible covalent binding, (iv) metal ion sequestration and subsequent DNA binding, (v) DNA groove and base specific binding, (v) interstrand cross-linking, (vi) intercalation with concomitant supercoil relaxation and duplex extension, (vii) redox cycling with production of reactive oxygen species and DNA single strand breaks, and (viii) single strand breaks as a result of phosphotriester formation.

Expected linkage disequilibrium for a neutral locus linked to a chromosomal arrangement.

Abstract: The expected value of the squared linkage disequilibrium is derived for a neutral locus associated with a chromosomal arrangement that is maintained in the population by strong balancing selection. For a given value of recombination, the expected squared linkage disequilibrium is shown to decrease as the intensity of selection maintaining the arrangement increases. The transient behavior of the expected square linkage disequilibrium is also derived. This theory applies to loci that are closely linked to inversions in Drosophila species and to loci closely linked to the differential segments of the translocation complexes in ring-forming species of Oenothera. In both cases the strong linkage disequilibria that have been observed in natural populations can be explained by random drift.