Showing papers by "Carleton University published in 1980"

A rapid method for isolation of purified, physiologically active chloroplasts, used to study the intracellular distribution of amino acids in pea leaves.

Abstract: A procedure is described for the rapid ( 240 nmol/mg chl), even thought it is proportionately lower in the chloroplast relative to the rest of the cell. The chloroplasts contain about 20% of many of the amino acids of the cell, but for individual amino acids the percentage in the chloroplast ranges from 8 to 40% of the cell total. Glutamic acid, glutamine and aspartic acid are enriched in the chloroplasts, while asparagine, homoserine and β-(isoxazolin-5-one-2-yl)-alanine are relatively lower. Leakage of amino acids from the chloroplast during preparation or repeated washing was ca. 20%. Some differences exist between the amino-acid composition of chloroplasts isolated from intact leaves and from protoplasts. In particular, γ-aminobutyric acid accumulates to high levels, while homoserine and glutamic acid decrease, during protoplast formation and breakage.

Hormonal factors controlling the initiation and development of lateral roots

Abstract: The decapitated primary root of 3-day-old Alaska pea seedlings has been used as a test system to determine the activities on lateral root formation of six auxins, six cytokinins and several other naturally-occurring compounds. Their effects were assessed on (1) the initiation of lateral root primordia, (2) the emergence of visible lateral roots, and (3) the elongation of these laterals. All the auxins, at the optimum concentration of 10-4M, promoted the initiation of lateral root primordia, and all except 3-indolylpropionic acid inhibited the elongation of the resulting lateral roots. Their effects on the emergence of laterals were small and varied. All the cytokinins, at 10-6M and above, inhibited both the initiation and the emergence of lateral roots, zeatin being the most powerful inhibitor. The emergence process was about twice as sensitive as the initiation of primordia to the presence of cytokinins. The cytokinin ribosides were generally less active than the free bases. Abscisic acid and xanthoxin inhibited both emergence and elongation, the concentration for 50% decrease of emergence being about 10-4M. Gibberellic acid had little clear effect on any of the three criteria. Nicotinic acid and thiamine at 10-3M promoted both the initiation of primordia and their emergence: pyridoxal phosphate stimulated both emergence and elongation but did not influence the initiation of primordia. Adenine and guanine had little effect but decreased root elongation some 25%. The strong inhibiting effect of the cytokinins may well be the basis for the marked inhibition exerted by the root-tip on lateral root formation, while the promoting effects of auxins may explain the previously observed promotion of lateral root formation by the young shoot and cotyledons.

Efficient decision heuristics.

Abstract: This article examines decision making in living systems at the level of the organism. Ten simple decision rules, or heuristics, were implemented as computer subroutines in a simulation program designed to determine how often each would select alternatives with highest-through-lowest expected value in a series of randomly generated decision situations. The decision situations varied in their number of alternatives (2, 4, or 8) and outcomes (2, 4, or 8). Results indicated that most of the heuristics, including some which “ignored” probability information, regularly selected alternatives with highest expected value, and almost never selected alternatives with lowest expected value. Implications of this finding for motivational explanations of heuristic use—as opposed to the more popular cognitive explanations—are discussed.

The hidden observer in hypnotic analgesia: discovery or experimental creation?

Abstract: Eight highly susceptible subjects were assigned to Hilgard's training procedures for eliciting "hidden" reports during hypnotic analgesia. These procedures indicate to subjects that a "hidden part" of themselves continues to feel high levels of pain while their "hypnotized part" experiences reduced pain. A second group of 8 subjects was given the opposite expectation concerning "hidden-pain"--that their "hidden part" would feel less pain than their "hypnotized part." Results were unambiguous. Subjects expecting high levels of "hidden" pain reported high levels whereas those expecting little "hidden" pain reported low levels. These results are inconsistent with the notion that "hidden" reports reflect the intrinsic activity of a "dissociated state." Instead, they indicate that "hidden" reports result from subjects' attempts to convincingly enact the role of "good hypnotic subject" as this role is defined for them by the experimental procedures they undergo.

Extinction and dopamine receptor blockade after intermittent reinforcement training: failure to observe functional equivalence.

Abstract: Response decrements in an operant task produced by either extinction or by the dopamine receptor blocker pimozide were examined in three experiments which employed intermittent reinforcement schedules. In contrast to the congruency between these treatments previously observed following continuous reinforcement training, treatment with pimozide was markedly more effective than extinction in decreasing performance after training with variable interval, fixed interval, and fixed ratio reinforcement. The two treatments also produced substantially different patterns of responding. A shift from extinction to pimozide did not alter the progressive decline in response rate over days, but a shift from pimozide to extinction caused a pronounced increase of performance. These results indicate that the pimozide and extinction treatment did not produce functionally equivalent effects, and that the role of dopamine on reward processes should not be inferred from comparisons between pimozide and extinction.

Converting Linear Programs to Network Problems

Abstract: We describe an algorithm which converts a linear program min{cx ∣ Ax = b, x ≥ 0} to a network flow problem, using elementary row operations and nonzero variable-scaling, or shows that such a conversion is impossible. If A is in standard form, the computational effort required is bounded by Orn, where r is the number of rows and n is the number of nonzero entries of A. A method for determining whether a “binary matroid” is “graphic” plays an important role in the algorithm.

Children's stereotypes about sex differences in emotionality

Abstract: In spite of the egalitarian atmosphere of recent years, contemporary preschool children possess pronounced stereotypes about sex differences in emotionality. They associate anger with maleness, but associate happiness, sadness, and fear with femaleness. These stereotypes are similar to those held by adults, but are largely dissimilar to actual sex differences in emotionality. The impact and possible etiology of these stereotypes are discussed.

Human Orientation in Transportation Terminals

Abstract: A method for measuring human orientation in transportation terminals has been developed. Visibility can be measured by the existence or nonexistence of sight lines. These sight lines form the arcs in a graph where the facilities form the nodes. By measuring the connectivity of such graphs, indices for visibility can be determined. Sight line analysis is a simple technique that can be applied to existing terminal layouts and signage systems or to future floor plans of new or expanding terminals. The method will determine the visibility of the terminal as a whole or of any of its subsystems and components. Changes in layout or signage can now be evaluated in terms of visibility and thus human orientation. The methodology was applied to eight air terminals, one rail terminal, and one bus terminal. The floor plan and signage system of one air terminal was improved to demonstrate how these changes can be measured by changes in the visibility indices.

Optimal fiscal illusion and the size of government

Abstract: The interpretation of the long-standing fiscal illusion hypothesis presented here is that the illusion is the result of attempts by utility maximizing public managers (politicians or bureaucrats) to direct the resources of the community toward themselves. In general, they will succeed if the costs of information about or enforcement of managerial behavior are nonzero, and political competition is imperfect. The consequences of this application of the Williamson theory of the firm, in the context of a median voter model, include the following:

The Importance of Mother: Labor Force Participation and Intergenerational Mobility of Women

Abstract: Previous research concerning the linkages between women's occupational origins and destinations has applied models developed for the study of men's intergenerational occupational mobility. In this paper, we use an approach that incorporates two unique aspects of women's occupational experiences. First, we consider housework to be a possible occupational outcome for women. Second, we consider the occupations of mothers as well as those of fathers in the portrayal of women's occupational origins. We show that this approach more fully displays the influences of occupational origins on women's subsequent occupational activities. In particular, we find that women whose mothers worked are themselves more likely to join the labor force, and their occupations are likely to resemble their mother's.

Analysis of Rotating Stall in Vaneless Diffusers of Centrifugal Compressors

Abstract: Self-excited flow oscillations in radial vaneless diffusers of centrifugal compressors are investigated analytically using the linearized equations of motion for unsteady flows. Solutions of the differential equations are made to satisfy boundary conditions at diffuser inlet and exit which in typical conversion systems represent the coupling between the diffuser and upstream and downstream components. The results indicate that the rotational speed of the stall pattern is dependent on the diffuser radius ratio and the coupling conditions between the impeller and the diffuser. It is shown that the dependence of the onset of the flow oscillations on the diffuser radius ratio is strong if the conditions at diffuser inlet are such that low speed rotating stall patterns are generated in the diffuser. Onset of high speed rotating stall patterns is more affected by the coupling conditions between the impeller and the diffuser than by the diffuser radius ratio.Copyright © 1980 by ASME

Intraventricular 6-hydroxydopamine in the newborn rat and locomotor responses to drugs in infancy: no support for the dopamine depletion model of minimal brain dysfunction.

Abstract: Bilateral intraventricular injections of 6-hydroxydopamine (6-OHDA) after desmethylimipramine (DMI) in rats 1 and 2 days of age, severely depleted brain dopamine (DA) particularly in the neostriatum, where levels in adulthood were about 7% of control. Compared to vehicle-injected controls these rats were hyperactive only at 15 and 20 days of age, and in adulthood were impaired in a two-way avoidance. Rats with similar 6-OHDA treatment but without DMI pretreatment showed severe depletion of brain norepinephrine (NE) as well as DA, and were behaviorally similar to the DA-depleted only rats. This behavioral syndrome is similar to that reported after intracisternal injection of 6-OHDA in 5-day-old rats, which has been argued as a model for minimal brain dysfunction (MBD). Contrary to expectation from this model, however, challenge doses of either d-amphetamine or methylphenidate did not reduce, but instead increased activity of these rats. The 6-OHDA treatments also did not alter the enhancement of locomotor activity by scopolamine, which was present at 30 days but not at 15 days.