Showing papers by "York University published in 1993"

WINDII, the wind imaging interferometer on the Upper Atmosphere Research Satellite

Abstract: The WIND imaging interferometer (WINDII) was launched on the Upper Atmosphere Research Satellite (UARS) on September 12, 1991. This joint project, sponsored by the Canadian Space Agency and the French Centre National d'Etudes Spatiales, in collaboration with NASA, has the responsibility of measuring the global wind pattern at the top of the altitude range covered by UARS. WINDII measures wind, temperature, and emission rate over the altitude range 80 to 300 km by using the visible region airglow emission from these altitudes as a target and employing optical Doppler interferometry to measure the small wavelength shifts of the narrow atomic and molecular airglow emission lines induced by the bulk velocity of the atmosphere carrying the emitting species. The instrument used is an all-glass field-widened achromatically and thermally compensated phase-stepping Michelson interferometer, along with a bare CCD detector that images the airglow limb through the interferometer. A sequence of phase-stepped images is processed to derive the wind velocity for two orthogonal view directions, yielding the vector horizontal wind. The process of data analysis, including the inversion of apparent quantities to vertical profiles, is described.

Work in people's lives: a location for counseling psychologists

Abstract: The career development-vocational psychology literature has been marked by 2 persistent problems: a slow response to new developments in basic areas of psychology, such as developmental psychology, and a lack of representation of populations other than White and middle-class groups as research participants or as foci of theoretical explanation. After a brief discussion of 2 factors that may have contributed to these problems, a rational for a new location for this field is developed.

Neuropsychological treatment of mild traumatic brain injury.

Abstract: A neuropsychological model of functional disability after mild traumatic brain injury is presented that allows for selecting Individualized treatments for different patients depending on the particular dynamics of their disability. Neurological, psychological, and physical factors are seen as Intera

Hippocampal Atrophy in Normal Aging: An Association With Recent Memory Impairment

Abstract: • Objective. —To estimate the prevalence of radiographically detectable hippocampal atrophy (HA) in a normal aging sample and to test whether such atrophy is associated with memory dysfunction. Design. —One hundred fifty-four medically healthy and cognitively normal elderly persons (aged 55 to 88 years) received magnetic resonance imaging and/or computed tomographic scans designed to identify HA. One hundred forty-five of these subjects also underwent psychometric tests of memory function. Multivariate analyses of variance were used to evaluate differences in memory performance between subjects with and without HA. Setting. —This study was conducted at a research clinic for the investigation of age-associated neuropsychological and neuroradiologic changes. Participants. —Based on the following criteria, 154 subjects were consecutively selected from a larger group of elderly research volunteers participating in a study of normal aging: age of 55 years or greater; Global Deterioration Scale score of 2 or less; and Mini-Mental State examination score of 28 or greater. Subjects with evidence for significant medical, psychiatric, or neurologic disease were excluded. Main Outcome Measure. —Outcome measurements included individual psychometric test scores and computed tomographic—magnetic resonance imaging hippocampal atrophy ratings. Results. —Nearly 33% of the subjects had radiographic evidence for HA. The prevalence of HA increased significantly with age and was more common in male than female subjects. After controlling for age, level of education, and vocabulary, subjects with HA were found to perform more poorly on tests of recent (secondary) verbal memory when compared with subjects without HA ( P Conclusion. —We conclude that HA is a common accompaniment of normal aging and is associated with mild memory impairment. Additional research is needed to determine whether HA constitutes a significant risk for future dementia.

Factorial validity of the 20-item Toronto Alexithymia Scale

Abstract: The 20‐item Toronto Alexithymia Scale (TAS‐20) was developed in previous research to measure a general dimension of alexithymia with three inter correlated factors. These three factors reflect dist...

Methane flux: Water table relations in northern wetlands

Abstract: Water table position, through the creation of aerobic and anaerobic conditions in the soil profile, plays an important role in controlling CH 4nflux from wetlands. A laboratory study of peat columns revealed that CH 4emission rates initially increased and then decreased as the water table was lowered from the peat surface to a depth of 50 cm, with the release of CH 4ntrapped in pores. There was a strong hysteresis between CH 4nflux on the falling and rising water table limbs (falling g rising). When expressed as seasonal average values, there was a strong relationship (rs 0.08 n 0.74) between log CH 4nflux and water table position for sites within 5 wetland regions in boreal‐subarctic Canada. The regression coefficients were similar among regions (0.022 n 0.037), but there were differences in the regression constants (0.47 n 1.89). CH 4nflux from drained, forested peatland soils decreased as the water table depth increased, and several sites were transformed from sources to sinks of CH 4. Global CH 4nemissions to the atmosphere may have been reduced by a 1 Tg yr m1nby peatland drainage during the last 100 yr.

Properties of skeletal muscle mitochondria isolated from subsarcolemmal and intermyofibrillar regions

Abstract: Two mitochondrial fractions, termed intermyofibrillar (IMF) and subsarcolemmal (SS), were isolated from skeletal muscle, and their biochemical properties were related to differences in respiration and mitochondrial protein synthesis. State III respiration was 2.3- to 2.8-fold greater in IMF than in SS mitochondria. Site 1 inhibition of respiration with rotenone reduced this difference to 1.4-fold. When sites 1 and 2 were inhibited with antimycin, the 1.4-fold differences remained. The activities of cytochrome-c oxidase (CYTOX) and succinate dehydrogenase (SDH) could account for some of these differences, since CYTOX was 20% greater (P < 0.05) in IMF mitochondria, and SDH was 40% greater (P < 0.05) in SS mitochondria. Cytochromes a, b, c, and c1 contents were similar in the two fractions. Cardiolipin (CL) content was higher (P < 0.05) in SS mitochondria, indicating a less dense mitochondrial fraction with respect to CL. In vitro [3H]leucine incorporation was 1.8-fold higher (P < 0.05) in IMF than in SS mitochondria. Thus compositional differences between IMF and SS fractions exist, perhaps representing mitochondria at different stages of biogenesis. The biochemical and functional differences could not solely be due to differences in mitochondrial protein synthesis but could also be due to nuclear-directed protein synthesis specific to each mitochondrial fraction.

Alexithymia and the Recognition of Facial Expressions of Emotion

Abstract: Slides of photographs depicting posed facial expressions of nine different emotions were presented to 131 females and 85 males who were asked to identify the emotion(s) being experienced by the person in each photograph. Subjects were then administered the 20-item version of the Toronto Alexithymia Scale; the 33rd and 66th percentiles were used to categorize subjects into high, moderate, and low alexithymia groups. Results showed that the high alexithymia group was significantly less able to recognize facial expressions of emotions than the low alexithymia group. There was no significant effect for gender on the ability to recognize facial emotions. The results suggest the presence of deficits in the perception of nonverbal emotion in alexithymia.

Conducting event studies with thinly traded stocks

Abstract: Procedures for measuring abnormal performance around events when securities do not trade daily are examined. A rank test patterned after the statistic proposed by Corrado [Corrado, C.J. (1989), A nonparametne test for abnormal security-price performance in event studies Journal of Financial Economics 23, 385-395] is derived. The empirical frequency distributions of the rank test statistic and a conventional test statistic are assessed under different rules for handling missing stock returns. The results suggest that the traditional procedures are reasonably well-specified for thickly and moderately traded stocks but misspecified for thinly traded stocks. The rank test however performs well for all trading frequencies and trade-to-trade returns are the best way to handle missing returns.

dUTP pyrophosphatase is an essential enzyme in Saccharomyces cerevisiae.

Abstract: dUTP pyrophosphatase (dUTPase; EC 3.6.1.23) catalyses the hydrolysis of dUTP to dUMP and PPi and thereby prevents the incorporation of uracil into DNA during replication. Although it is widely believed that dUTPase is essential for cell viability because of this role, direct evidence supporting this assumption has not been presented for any eukaryotic system. We have analysed the role of dUTPase (DUT1) in the life cycle of yeast. Using gene disruption and tetrad analysis, we find that DUT1 is necessary for the viability of S. cerevisiae; however, under certain conditions dut1 null mutants survive if supplied with exogenous thymidylate (dTMP). Analyses with isogenic uracil-DNA-glycosylase (UNG1) deficient or proficient strains indicate that in the absence of dUTPase, cell death results from the incorporation of uracil into DNA and the attempted repair of this damage by UNG1-mediated excision repair. However, in dut1 ung1 double mutants, starvation for dTMP causes dividing cells to arrest and die in all phases of the cell cycle. This latter effect suggests that the extensive stable substitution of uracil for thymine in DNA leads to a general failure in macromolecular synthesis. These results are in general agreement with previous models in thymine-less death that implicate dUTP metabolism. They also suggest an alternative approach for chemotherapeutic drug design.

Behavior of coactive muscles during fatigue

Abstract: Coactivation is antagonist muscle activity that occurs during voluntary contraction. Recently, we showed that the extent of coactivity in the knee flexors decreases after a short period of resistance training of the knee extensors (8). The purpose of the present experiment was to study the time course of coactivation in the knee flexors during fatigue of the knee extensors. Ten male subjects performed repeated submaximal static leg extensions in a low-intensity long-duration and a high-intensity short-duration fatigue protocol until they could no longer produce the required force [time limit of endurance (Tlim)]. Maximal voluntary contraction (MVC), submaximal force, and surface electromyographic (EMG) activity were measured periodically. Vastus lateralis EMG increased progressively during fatigue of the extensor muscles (P < 0.05), resulting in a 38% change from control at Tlim. Biceps femoris EMG, which was our measure of coactivation, also increased by approximately 60% at Tlim in each protocol (P < 0.05). These observations lead us to conclude that a small but significant force loss during repeated static contractions to Tlim is due to an increase in antagonist activity. Moreover, the close correlation between the antagonist and agonist EMG supports the notion of a "common drive" to both motoneuron pools (10).

Individual differences in social categorization: The influence of personal need for structure on spontaneous trait inferences.

Abstract: Because 1 function of categorization is to provide structure and control to social interactions and because individuals differ in the extent to which they desire control and structure, individual differences in personal need for structure (PNS) should moderate the extent to which people categorize. Spontaneous trait inferences (STIs) were used to assess the use of traits in categorization. High-PNS Ss were more likely to form STIs and more likely to recall names of target actors in the stimulus sentences. This research provides evidence for the organization of behavioral information in person nodes in circumstances where processing goals did not explicitly request such organization

What ears do for bats: a comparative study of pinna sound pressure transformation in chiroptera.

Abstract: Using a moveable loudspeaker and an implanted microphone, we studied the sound pressure transformation of the external ears of 47 species of bats from 13 families. We compared pinna gain, directionality of hearing and interaural intensity differences (IID) in echolocating and non-echolocating bats, in species using different echolocation strategies and in species that depend upon prey-generated sounds to locate their targets. In the Pteropodidae, two echolocating species had slightly higher directionality than a non-echolocating species. The ears of phyllostomid and vespertilionid species showed moderate directionality. In the Mormoopidae, the ear directionality of Pteronotus parnellii clearly matched the dominant spectral component of its echolocation calls, unlike the situation in three other species. Species in the Emballonuridae, Molossidae, Rhinopomatidae and two vespertilionids that use narrow-band search-phase echolocation calls showed increasingly sharp tuning of the pinna to the main frequency of their signals. Similar tuning was most evident in Hipposideridae and Rhinolophidae, species specialized for flutter detection via Doppler-shifted echoes of high-duty-cycle narrow-band signals. The large pinnae of bats that use prey-generated sounds to find their targets supply high sound pressure gain at lower frequencies. Increasing domination of a narrow spectral band in echolocation is reflected in the passive acoustic properties of the external ears (sharper directionality). The importance of IIDs for lateralization and horizontal localization is discussed by comparing the behavioural directional performance of bats with their bioacoustical features.

Mutations in the larval foraging gene affect adult locomotory behavior after feeding in Drosophila melanogaster.

Abstract: Previous studies have shown a correlation between the locomotory component of larval and adult foraging behavior in the fruit fly. Here we show that this relationship is far more than mere correlation. It can be attributable to different alleles at the same genetic locus of the behavioral gene foraging (for). The for gene offers us the unique opportunity to study the genetic basis and evolutionary significance of a naturally occurring behavioral polymorphism. Until now, only the effect of for on Drosophila melanogaster larval behavior was studied. Larvae with the rover allele (forR) move significantly more while eating during a set time period than those homozygous for the sitter alleles (fors). Here, we show that rover and sitter larval strains derived from nature differ in the distance adults walk after feeding per unit time and that this variation results from different alleles at the foraging locus, the very gene originally defined on the basis of larval behavior. We hypothesize that for may be involved in the way flies evaluate a food resource.

Imitation in free-ranging rehabilitant orangutans (Pongo pygmaeus).

Abstract: ~~~~~~7$;~ We made an observational study of spontaneous imitation in orangutans (Pongo pygmaeus). Previous studies may have underestimated great apes' imitative capacities by studying subjects under inhibiting conditions. We used subjects living in enriched environments, namely, rehabili­ tation. We collected a sample of spontaneous imitations and analyzed the most complex incidents for the likelihood that true imitation, learning new actions by observing rather than by doing, was involved in their acquisition. From 395 hr of observation and other reports on 26 orangutans, we identified 354 incidents of imitation. Of these, 54 complex incidents were difficult to explain by forms of imitation based on associative processes grounded in experiential learning alone; they were, however, congruent with acquisition processes that include true imitation. These findings suggest that orangutans may be capable of true imitation and point to critical eliciting factors. Imitation, in the general sense of replicating by whatever mechanism behavior inspired by a model, has been a focus

Chemical structures of the core regions of Campylobacter jejuni serotypes O:1, O:4, O:23, and O:36 lipopolysaccharides

Abstract: Complete structures, including the location of N-acetylneuraminic acid (Neu5Ac) residues, were assigned for the core regions of Campylobacter jejuni serotypes O:1, O:4, and O:23 and O:36 lipopolysaccharides (LPS). In continuation of earlier studies, structure determinations of liberated oligosaccharides and, where necessary, of intact LPS, were by 1H-NMR spectroscopy, Smith degradation, chromium trioxide and enzymic degradations, in conjunction with methylation studies supported by fast-atom-bombardment mass spectrometry and linkage analyses by gas chromatography/mass spectrometry. It was concluded on the basis of the following structures, in which each was linked 15 to a terminal 3-deoxy-D-manno-octulosonic acid residue, that the core regions with qualititatively similar sugar compositions showed serotypic differences in one or more of their sequences, linkage types, and anomeric configurations: The outer regions of each structure carry Neu5Ac residues linked 23 to available β-D-Galp residues and show striking similarities with various glycosphingolipids of the ganglioside family. However, Neu5Ac epitopes are not apparently involved in determining serospecificity.

Comparison of somatic mutation in a transgenic versus host locus.

Abstract: Somatic mutations can now be quantified in almost any cell type in mice carrying bacterial genes in a lambda phage shuttle vector. Mutations induced in vivo are detectable ex vivo, after packaging host-cell DNA into phage that are grown on suitable bacteria. However, the transgenic DNA differs from many host loci in several ways: it (i) is prokaryotic DNA, (ii) is present in multiple tandem copies, and (iii) is heavily methylated and probably not expressed. Thus, mutation of a transgene may not be a suitable model of the host loci, which are eukaryotic, unique, and expressed. To test the relevance of the transgene mutation model, the frequencies of the bacterial lacI+ to lacI- mutations induced in half of the small intestine were compared with the frequencies of the host Dlb-1b to Dlb-1a mutations induced in the other half. The loci responded similarly to ethyl nitrosourea (ENU) with respect to the animal's age and sex, sex of the parent transmitting the transgene, and expression time. ENU dose-response curves were similar. Furthermore, no difference was found at the Dlb-1 locus between transgenic and nontransgenic siblings. In contrast, x-rays induced few lacI mutations but many Dlb-1 mutations. Probably few large deletions are detectable at lacI, but many are detectable at Dlb-1. If so, an important class of mutation is not readily detected in these transgenic mice. With this exception, the transgene and host gene responded similarly in this somewhat limited trial, as is necessary if the transgenic mice are to be a useful model.

Accounting for genocide after 1945: Theories and some findings

Abstract: Genocide has been related in social theory to both social and political structure: i.e., plural society (ethnoclass exclusion and discrimination) and types of polities - revolutionary, totalitarian and authoritarian regimes. War has also been noted as an instigator or frequent context of genocide. This paper reviews theoretical expectations and examines the empirical relation between genocides (and other state massacres) and indices of ethnic discrimination, polity form, and war among states in Asia, Africa and the Mid-East from 1948 to 1988. Findings show that (1) most users of genocide are repeat offenders. (2) There is a high likelihood of political exclusion and discrimination of ethnoclasses producing rebellions which instigate genocides and other state-sponsored massacres. (3) As expected, unfree, authoritarian, and one-party communist states (in ascending order) are most likely to use genocide. Democratic states in this era are not perpetrators against their citizens but have been patrons and accomplices of genocidal regimes elsewhere. One-party communist states are 4.5 times more likely to have used genocide than are authoritarian states. (4) States involved in wars are many more times as likely to have employed genocide than other states. Exploring these cases, we find that genocides both lead to war and war leads to genocide through several processes. (5) The use of genocide in conflicts within the state in the regions surveyed tripled between 1968-88 compared to the preceding score of years (10:3 cases). Genocide and genocidal massacres occur so often that they may be considered normal in these regions. Both the theoretical and the policy implications of these findings are discussed. Observing on the latter, we note that journalists and scholars have often confused recognition of genocide and genocidal massacres by framing these cases as 'ethnic conflicts', by confounding the toll of war and massacre and by conflating concepts. To deter genocide, we should promote nonviolent change in order to eliminate ethnoclass domination and monitor civil wars to detect

Work stress, role conflict, social support, and psychological burnout among teachers.

Abstract: This study examined a research model developed to understand psychological burnout among school-based educators. Data were collected from 833 school-based educators using questionnaires completed anonymously. Four groups of predictor variables identified in previous research were considered: individual demographic and situational variables, work stressors, role conflict, and social support. Some support for the model was found. Work stressors were strong predictors of psychological burnout. Individual demographic characteristics, role conflict, and social support had little effect on psychological burnout.

Commoners: Common Right, Enclosure and Social Change in England, 1700-1820

Abstract: Introduction 1. The question of value Part I. Survival: 2. Who had common right? 3. Threats before enclosure 4. Ordering the commons 5. Enforcing the orders 6.The uses of waste Part II. Decline: 7. Two villages 8. Decline and disappearance 9. Resisting enclosure Part III. Conclusion: 10. 'Making freeman of the slave' Appendices Bibliography Index.

An experimental and analytical study of autoparametric resonance in a 3DOF model of cable-stayed-beam

Abstract: Autoparametric interaction and the associated phenomenon of amplitude saturation are experimentally observed in a physical model of cable-and-beam structure In this system, the horizontal beam is fixed at one end and supported at the other end by an inclined taut cable The longitudinal axes of beam and cable are in a vertical plane Three natural frequencies of the system are approximately of the ratio 1:1:2 This is a combination of two conditions that are very likely to occur in relatively long-span, multi-stay-cable bridges, namely, 1:1 tuning and 1:2 superharmonic tuning While the beam is vertically excited with sufficiently large force near a primary resonance, the cable vibrates horizontally at half of excitation frequency The beam also vibrates horizontally at half-frequency, as well as vertically As the vertical excitation on the bean is further increased in amplitude, the vertical vibration amplitude gets saturated instead of increasing proportionately A 3DOF analytical model of the structure is also derived, where the finite motion of the cable introduces geometric nonlinearities in quadratic and cubic forms The system parameters having been carefully measured from the experimental model, steady-state solutions of the coupled nonlinear equations of motion are obtained, by the perturbation method of multiple time scales Agreement between experimental observation and analytical prediction is very good, both qualitatively and quantitatively Very good agreement is found also in the case of horizontal excitation of the beam, where effects of linear and nonlinear interaction are apparent

The Contribution of Social Support to Coping Strategies

Abstract: Cette recherche explore le role du soutien social dans les strategies d'action retenues par des cadres masculins et feminins quand ils sont confrontes au stress professionnel. On a evalue la perception du soutien en provenance du patron, des collegues, des parents et des amis. Les strategies instrumentales, preventives et palliatives ont ete prises en compte. L'analyse de regression a montre que le soutien du superieur contribuait significativement aux strategies preventives et instrumentales uniquement chez les femmes. Comme decouverte complementaire, il est apparu que le soutien des parents et des amis contribuait negativement et de facon significative aux strategies palliatives, toujours uniquement chez les femmes