Showing papers by "Dalhousie University published in 1985"
TL;DR: In this paper, a fairly thorough account of multiple discrepancies theory is presented, with a review of its historical antecedents and an examination of its strength in accounting for the happiness (H) and satisfaction (S) of nearly 700 university undergraduates.
Abstract: A fairly thorough account of multiple discrepancies theory (MDT) is presented, with a review of its historical antecedents and an examination of its strength in accounting for the happiness (H) and satisfaction (S) of nearly 700 university undergraduates. Basically, MDT asserts that H and S are functions of perceived gaps between what one has and wants, relevant others have, the best one has had in the past, expected to have 3 years ago, expects to have after 5 years, deserves and needs. MDT explained 49% of the variance in H, 53% in global S and 50% or more in 7 out of 12 domain S scores. The domains studied were health, finances, family, job, friendships, housing, area, recreation, religion, self-esteem, transportation and education.
811 citations
TL;DR: The possibility that phylogenetically 'prepared' forms of defensive learning might serve as a basis for the study of anxiolytic agents is introduced.
456 citations
TL;DR: It was found that adapting to a high-contrast grating degraded discrimination for test gratings inclined at about 10-20 deg to the adapting grating while having little effect on the detection of these inclined gratings.
Abstract: An orientational difference of only 0.3–0.5 deg can be discriminated between two gratings or two lines, although psychophysical channels and cortical cells both have comparatively broad orientation bandwidths of 10–25 deg. One proposed explanation for the fineness of orientation discrimination is that, while detection is determined by the most excited orientation-tuned neural elements, superthreshold orientation discrimination is determined by difference signals between these elements [ Westheimer, J. Opt. Soc. Am.66, 332 ( 1976)]. This implies that, if stimulus orientation is changed slightly, the most important elements for discriminating this change will be those whose relative activity changes most, even though the excitation of these elements may be comparatively weak. In accord with this prediction, we found that adapting to a high-contrast grating degraded discrimination for test gratings inclined at about 10–20 deg to the adapting grating while having little effect on the detection of these inclined gratings. For test gratings parallel to the adapting grating, discrimination was improved, but detection was degraded. Either an opponent-process or a line-element model can account for these effects of adaptation. An opponent model can also explain our findings that subjects do not confound orientation change with contrast change and that suprathreshold orientation discrimination is almost independent of contrast, varying by only ±10% from about 3 to about 25 times contrast threshold. A discrimination model must incorporate reliable storage of spatial frequency, because discrimination was not affected by increasing the interval between grating presentations from 1 to 10 sec. In spatial form vision the relation between postadaptation detection and discrimination is formally similar along the dimensions of orientation and of size, and these two independent spatial discriminations can be modeled in formally similar ways, for example, in terms of orientation opponency and size opponency among multiple local elements, each of which is tuned to a different orientation and/or size.
412 citations
TL;DR: The genetic structure of natural populations of Drosophila melanogaster as estimated using compound-autosome strains and dominance effect of spontaneous mutant polygenescontrolling viability in heterozygous genetic background are described.
Abstract: gaster as estimated using compound-autosome strains. Evolution 33:359-370. MITCHELL, J. A., AND M. J. SIMMONS. 1977. Fitness effects of EMS induced mutations on the X chromosome of Drosophila melanogaster. II. Hemizygous fitnesseffects. Genetics 87:775-783. MUKAI, T., S. CHIGUSA, AND I. YOSHIKAWA. 1965. The genetic structure of natural populations of Drosophila melanogaster. III. Dominance effect of spontaneous mutant polygenescontrolling viability in heterozygous genetic background. Genetics 52:493-501.
359 citations
TL;DR: The combined results from the three experiments provide support for the existence of three distinct speech-perception factors.
Abstract: A continuing controversy concerns whether speech perception can be best explained by single-factor psychoacoustic models, single-factor specialized linguistic models, or dual-factor models including both phonetic and psychoacoustic processes. However, our recent cross-language speech perception research has provided data suggesting that a three-factor model, including auditory, phonetic, and phonemic processing, may be necessary to accommodate existing findings. In the present article, we report the findings from three experiments designed to determine whether three separate processing factors are used in speech perception. In these experiments, English and Hindi subjects were tested in a same-different (AX) discrimination procedure. The duration of the interstimulus interval, the number of trials, and the experimental context were manipulated when testing the English-speaking subjects. The combined results from the three experiments provide support for the existence of three distinct speech-perception factors.
356 citations
TL;DR: In this article, the authors show that the spin-lattice relaxation times T 1 of both nuclei and the absence of quadrupole splitting indicate extremely rapid overall reorientation of the CN axis of the cation in a potential of cubic symmetry.
324 citations
TL;DR: Using a symbolic interactionist framework, this article employed a time-diary technique combined with in-depth interviews to explore perceptions of leisure situations among a random sample of married couples, finding that although leisure could be experienced during almost any type of activity, there was considerable consensus with regard to the perceptual factors associated with leisure situations.
Abstract: One of the ongoing problems surrounding the whole area of leisure studies concerns conceptualization of the term leisure itself. Few empirical studies to date have looked at the meaning of leisure, and even fewer have incorporated a grounded theory approach. Using a symbolic interactionist framework, the present study employed a time‐diary technique combined with in‐depth interviews to explore perceptions of leisure situations among a random sample of married couples. The results showed that although leisure could be experienced during almost any type of activity, there was considerable consensus with regard to the perceptual factors associated with leisure situations. The factors shown to best differentiate leisure from non‐leisure were enjoyment, freedom of choice, relaxation, intrinsic motivation, and the lack of evaluation. None of these factors alone can be equated with the concept of leisure, but the combination of three or more factors leads to accurate predictions of the definition of sit...
289 citations
TL;DR: Results indicate that the hamster geniculo-suprachiasmatic tract originates in part from NPY-immunoreactive cell bodies and that these cells lie in areas receiving direct retinal afferents.
239 citations
01 Jan 1985
TL;DR: This work has shown that bacterial surface structures comprise a very complex and fluid interface with the environment which the bacterium must maintain in order to survive amid the ubiquitous antibacterial agents and factors in nature.
Abstract: When we use direct microscopic techniques to examine bacteria growing in natural and pathogenic ecosystems, we are forcibly struck by the profound differences between these organisms and cells within derived in vitro laboratory cultures. The development of a series of new techniques for the stabilization and visualization of bacterial surface structures has intensified these differences because, as we come to understand bacterial surface structures more fully, we see that they comprise a very complex and fluid interface with the environment which the bacterium must maintain in order to survive amid the ubiquitous antibacterial agents and factors in nature.
219 citations
TL;DR: Overall improvement was seen in 62.5% of patients on amantadine and 21.8% on placebo, and additional experience up to two years suggests continued benefit but common and important side-effects.
Abstract: We carried out a double blind control study of fatigue in 32 patients with multiple sclerosis, comparing amantadine hydrochloride 100 mg twice a day and placebo On amantadine 31% had marked improvement; 156% moderate improvement; 156% mild improvement; and 365% unchanged On placebo, none noted marked improvement; one claimed moderate improvement on either amantadine or placebo 187% reported mild improvement on placebo; and most of them had similar or more response to amantadine No patient selected placebo over amantadine at the end of the trial Overall improvement was seen in 625% of patients on amantadine and 218% on placebo Additional experience up to two years suggests continued benefit but common and important side-effects
207 citations
TL;DR: Responses of 65 single auditory cortex neurons to frequency-modulated (FM) sweeps with different rates and direction of frequency change were examined quantitatively and preference for downward-directed FM sweeps was especially clear in EI cells.
TL;DR: A U-shaped function of behavioral growth characterizes the early ontogeny of face grooming in mice, and three simultaneous aspects of movement are recorded from high-speed films: the movements of the separate limb and body segments, the resultant paths which are traced by the forepaws, and the paths of contact on the face.
Abstract: A U-shaped function of behavioral growth characterizes the early ontogeny of face grooming in mice. In the first few postnatal days (0-100 hr), mice groom their face by using temporally isolated strokes, or bouts of strokes, which vary in amplitude and symmetry. Later on (100-200 hr), bouts disappear, asymmetry is eliminated, and the amplitude of strokes is gradually restricted; the infants engage in stereotyped, double-handed, temporally isolated strokes. Finally (200-300 hr), bouts reappear, including both short and long, symmetrical and asymmetrical, strokes. These changes, are accompanied by unidirectional changes such as an increasing participation of the trunk, the neck, and the head in grooming, which lead to the flexible organization of face grooming seen in adults. Instead of describing development in terms of emerging unitary "acts," we have recorded from high-speed films three simultaneous aspects of movement: the movements of the separate limb and body segments, the resultant paths which are traced by the forepaws, and the paths of contact which are traced on the face. This method of description discloses (a) reversible changes, and (b) a change in the relative stability of each of these aspects of face grooming, in the course of early ontogeny.
TL;DR: Microtechniques with disposable, calibrated, capillary pipets were developed to measure amounts and classes of lipids in individual Lake Michigan benthic invertebrates and indicated that <5% of the measured gravimetric weights was due to the inclusion of nonlipid material in the extracts.
Abstract: Microtechniques with disposable,
calibrated, capillary pipets were developed to measure amounts and classes of lipids in individual Lake Michigan benthic invertebrates. After lipids from an animal were partitioned into 100 µl of extraction solvent and purified, measured portions were weighed with an electrobalance. Lipids in some samples were also characterized by thin layer chromatography with flame ionization detection (TLC-FID). The extraction method was calibrated gravimetrically with cod liver oil and evaluated with a dry, ground fish sample. Lipid content was proportional (r = 0.99) to fish tissue dry weight over the range of 0.3–13 mg. TLC-FID measurements correlated well (r = 0.98) with gravimetric analysis for portions of extracts of individual amphipods (Pontoporeia hoyi) and oligochaetes (Stylodrilus heringianus). TLC-FID analysis indicated that <5% of the measured gravimetric weights was due to the inclusion of nonlipid material in the extracts.
TL;DR: It is shown that recessive deleterious gene effects foster the maintenance of allelic variants affecting life history under protected polymorphism conditions when the intrinsic rate of increase, or Malthusian parameter, is not too large in magnitude.
TL;DR: On the basis of several experimental approaches, it was concluded that these seaweeds normally absorb bicarbonate rather than CO 2 from sea water and to support normal levels of photosynthesis.
TL;DR: Results suggest that diltiazem and verapamil may have the potential to cause drug interactions involving inhibition of drug biotransformation, as both drugs could prolong pentobarbital-induced sleeping times in mice at doses comparable to those used in man.
TL;DR: In this article, a study of 60 married couples found that the expectation of inequality in access to leisure time was associated with status differences between males and females in society in general, leading to the expectation that they expect to have unequal access to the leisure time.
Abstract: Consideration of status differences between males and females in society in general leads to the expectation of inequality in access to leisure time. In this study of 60 married couples, leisure is...
TL;DR: In this paper, the potential utility of local development as an effective element of regional development policy is examined, emphasizing the emergence of local entrepreneurship and the role of the State in stimulating local initiatives.
Abstract: Coffey W. J. and Polese M. (1985) Local development: conceptual bases and policy implications, Reg. Studies 19, 85–93. Although local development is frequently cited as an option within the broader context of regional policy, the concept remains vague. The bases of the local development approach lie in its complementarity with three traditional pillars of regional theory and policy: capital and infrastructure policies; migration as an adjustment mechanism; and growth centre strategies. In examining the potential utility of local development as an effective element of regional development policy, we emphasize the emergence of local entrepreneurship and the role of the State in stimulating local initiatives. Local development policy may be generalized in terms of three options involving financial assistance, access to information, and social animation.
TL;DR: The kinematics of swimming in tadpoles from four species of anurans was studied using computer-assisted analysis of high speed cine records to support the idea that muscular activity in the posterior, tapered portion of the tadpole tail does not serve a major role in thrust production during normal, straightforward swimming at constant velocity.
Abstract: The kinematics of swimming in tadpoles from four species of anurans ( Rana catesbeiana Shaw, Rana septentrionalis Baird, Rana clamitans Latreille and Bufo americanus Holbrook) was studied using computer-assisted analysis of high speed (≥200 frames s −1 ) cine records. 1. Tadpoles exhibit the same positive, linear relationship between tail beat frequency and specific swimming speed commonly reported for subcarangiform fishes. 2. Tadpoles show an increase in the maximum amplitude of the tail beat with increasing swimming speed up to approximately 4 lengths s −1 . Above 4 lengths s −1 , amplitude approaches an asymptote at approximately 25 % of length. 3. Tadpoles with relatively longer tails have lower specific amplitudes. 4. Froude efficiencies for tadpoles are similar to those reported for most subcarangiform fishes. 5. Bufo larvae tend to have higher specific maximum amplitude, higher tail beat frequencies, lower propeller efficiencies (at least at intermediate speeds) and substantially less axial musculature than do comparable-sized Rana larvae. These differences may relate to the fact that Bufo larvae are noxious to many potential predators and consequently need not rely solely on locomotion for defence. 6. Tadpoles exhibit larger amounts of lateral movement at the snout than do most adult fishes. 7. The point of least lateral movement during swimming in tadpoles is at the level of the semi-circular canals, as assumed in models on the evolution of the vertebrate inner ear. 8. Passive oscillation of anaesthetized and curarized tadpoles at the base of their tail produces normal kinematics in the rest of the tail. This supports the idea that muscular activity in the posterior, tapered portion of the tadpole tail does not serve a major role in thrust production during normal, straightforward swimming at constant velocity. 9. The angle of incidence and lateral velocity of the tail tip as it crosses the path of motion are not consistent with theoretical predictions of how thrust should be generated. The same parameters evaluated at the high point of the tail fin (approximately midtail) suggest that that portion of the tail generates thrust most effectively. 10. Ablation of the end of the tail in passively oscillated tadpoles confirms that the terminal portion of the tadpole tail serves to reduce excessive amplitude in the more anterior portion of the tail, where most thrust is generated. 11. The posterior portion of the tail is important in reducing turbulence around a tadpole. It may also function to produce thrust during irregular, intricate movements, such as swimming backwards. 12. Tadpoles are comparable to subcarangiform fishes of similar size in their maximum swimming speed and mechanical efficiency, despite the fact that they have much less axial musculature and lack the elaborate skeletal elements that stiffen the fins in fishes. The simple shape of the tadpole tail appears to allow these animals efficient locomotion over short distances and high manoeuvrability, while maintaining the potential for rapid morphological change at metamorphosis.
TL;DR: In this paper, Bader et al. showed that the generalization of the bond-length-bond-order relationship of CC bonds may be extended to intermolecular hydrogen bonding.
TL;DR: It is suggested that growth within thick adherent biofilms confers upon cells of Pseudomonas aeruginosa a large measure of resistance to aminoglycosides and other antibiotics that may help to explain the frequent failure of antibiotic chemotherapy in catheter-associated urinary tract infections.
Abstract: A modified Robbins Device was used to establish coherent biofilms of Pseudomonas aeruginosa on the surface of catheter material in an artificial urine milieu and the ability of an antibiotic to penetrate the biofilm and kill the enclosed bacteria was assessed. The Pseudomonas aeruginosa strain used had been isolated from a patient with urinary tract infection. Although planktonic (floating) cells of the Pseudomonas aeruginosa strain were inhibited by less than 1 mg/l of tobramycin and killed by 50 mg/l, contact with 1,000 mg/l of tobramycin for 12 h failed to kill all the sessile (adherent) bacteria in the biofilms on the surface of the catheter material. Surviving sessile bacteria recovered directly from the exposure to 1,000 mg/l of tobramycin were inhibited by 0.4 mg/l of this agent when tested as dispersed planktonic cells by standard MIC methods. It is suggested that growth within thick adherent biofilms confers upon cells of Pseudomonas aeruginosa a large measure of resistance to aminoglycosides and other antibiotics that may help to explain the frequent failure of antibiotic chemotherapy in catheter-associated urinary tract infections.
01 Jan 1985
TL;DR: The authors investigated postpartal women's attitudes toward their body image; these attitudes were then compared to their prepregnant and pregnant body image attitudes, and the results indicated that the subjects had a slightly positive attitude toward their postpartum body image.
Abstract: Research was conducted to investigate postpartal women's attitudes toward their body image; these attitudes were then compared to their prepregnant and pregnant body image attitudes. A repeated measures design was used, with data collected at two and six weeks postpartum. Pregnant and prepregnant attitudes were collected retrospectively. A nonrandom, convenience sample of 63 multiparas and primiparas was used. The results indicated that the subjects had a slightly positive attitude toward their postpartum body image; multiparas felt more positive about their postpartum body image than did the primiparas; the women felt more positive about their prepregnant body image than about their postpartum body image; and the women felt more positive about their postpartum body image than about their pregnant body image.
TL;DR: Cardiac ICa differs from other currents in having a high amplitude-Q10 and an oscillatory response to rapid temperature changes and quick changes in temperature induced pronounced deviations from the steady-state Q10 relations.
Abstract: ICa was recorded in quinea pig ventricular myocytes using the whole-cell voltage-clamp technique. The shape of the I–V relation was unaffected by temperature (21–37°C) but there were large changes in ICa amplitude and time course. Steady-state responses indicated Q10 's of 2.96±0.14 (amplitude), 2.52±0.13 (time to peak), and 2.82±0.28 (T1/2 inactivation) (mean ± SD, n=6). Quick changes in temperature (T1/2<30 s) induced pronounced deviations from the steady-state Q10 relations (early depression, compensatory overshoot). Thus, cardiac ICa differs from other currents in having a high amplitude-Q10 and an oscillatory response to rapid temperature changes.
TL;DR: Horseradish peroxidase was injected into the cervical vagus nerve or stomach wall of adult squirrel monkeys and labelled afferent fibres and terminals were present in medial and lateral parts of the nucleus of the tractus solitarius (NTS) ipsilaterally.
Abstract: Horseradish peroxidase was injected into the cervical vagus nerve or stomach wall of adult squirrel monkeys. Following cervical vagus nerve injections, labelled afferent fibres were present in the tractus solitarius and labelled fibres and terminals were present in medial and lateral parts of the nucleus of the tractus solitarius (NTS) ipsilaterally. Afferent labelling was also seen in the ipsilateral commissural nucleus and in the area postrema. Labelling was present contralaterally in caudal levels of the medial parts of the NTS, in the commissural nucleus, and in the area postrema. Afferent projections to the ipsilateral pars interpolaris of the spinal trigeminal nucleus and to the substantia gelatinosa of the C1 segment of the spinal cord were also labelled. Following injections of HRP into the anterior and posterior stomach walls, the tractus solitarius was labelled bilaterally. Afferent labelling was concentrated bilaterally in the dorsal parts of the medial division of the NTS, i.e., in the subnucleus gelatinosus, and in the commissural nucleus. The regions of NTS immediately adjacent to the tractus solitarius were largely unlabelled.
Injections of HRP into the cervical vagus nerve resulted in heavy retrograde labelling of neurons in the ipsilateral dorsal nucleus of the vagus (DMX) and in the nucleus ambiguus (NA). In addition a few neurons were labelled in the intermediate zone between these two nuclei. Retrogradely labelled neurons were also present in the nucleus dorsomedialis in the rostral cervical spinal cord and in the spinal nucleus of the accessory nerve. Injections of HRP into the left cricothyroid muscle in two cases resulted in heavy retrograde labelling of large neurons in the left NA. Following stomach wall injections of HRP retrograde labelling of neurons was seen throughout the rostrocaudal and mediolateral extent of the DMX; there was no apparent topographical organization of the projection. In these cases, a group of labelled smaller neurons was found lying ventrolateral to the main part of the NA through its rostral levels.
This study in a primate indicates that a large vagal afferent projection originates in the stomach wall and terminates primarily in the subnucleus gelatinosus of the NTS and in the commissural nucleus with a distribution similar to that described previously in studies in several subprimate mammalian species. The present results and those of other studies suggest some degree of segregation of visceral input within different subnuclei of the NTS. In addition, the investigation shows that while the majority of neurons which supply the stomach are located in the DMX, a small number are found in the ambiguus complex.
TL;DR: The generalized quasi-variational inequality problem (GQVI) in locally convex Hausdorff topological vector spaces was studied in this article, where the authors obtained a fixed point theorem due to Ky Fan and I. L. Glicksberg and two different multivalued versions of the Hartman-Stampacchia variational inequality.
TL;DR: Serum osteocalcin holds promise as a useful marker of subacute changes in bone metabolism, particularly in children with renal failure and children with various forms of rickets.
TL;DR: The DNA sequence of the cob region of the Schizosaccharomyces pombe mitochondrial DNA has been determined and it is indicated that Sch.