Showing papers by "University of Ottawa published in 1989"

Testing for the equivalence of factor covariance and mean structures: The issue of partial measurement invariance.

Abstract: Addresses issues related to partial measurement in variance using a tutorial approach based on the LISREL confirmatory factor analytic model. Specifically, we demonstrate procedures for (a) using "sensitivity analyses" to establish stable and substantively well-fitting baseline models, (b) determining partially invariant measurement parameters, and (c) testing for the invariance of factor covariance and mean structures, given partial measurement invariance. We also show, explicitly, the transformation of parameters from an all-^fto an all-y model specification, for purposes of testing mean structures. These procedures are illustrated with multidimensional self-concept data from low (« = 248) and high (n = 582) academically tracked high school adolescents. An important assumption in testing for mean differences is that the measurement (Drasgow & Kanfer, 1985; Labouvie, 1980; Rock, Werts, & Haugher, 1978) and the structure (Bejar, 1980; Labouvie, 1980; Rock etal., 1978) of the underlying construct are equivalent across groups. One methodological strategy used in testing for this equivalence is the analysis of covariance structures using the LISREL confirmatory factor analytic (CFA) model (Joreskog, 1971). Although a number of empirical investigations and didactic expositions have used this methodology in testing assumptions of factorial invariance for multiple and single parameters, the analyses have been somewhat incomplete. In particular, researchers have not considered the possibility of partial measurement invariance. The primary purpose of this article is to demonstrate the application of CFA in testing for, and with, partial measurement invariance. Specifically, we illustrate (a) testing, independently, for the invariance of factor loading (i.e., measurement) parameters, (b) testing for the invariance of factor variance-covariance (i.e., structural) parameters, given partially invariant factor loadings, and (c) testing for the invariance of factor mean structures.1 Invariance testing across groups, however, assumes wellfitting single-group models; the problem here is to know when to stop fitting the model. A secondary aim of this article, then, is to demonstrate "sensitivity analyses" that can be used to establish stable and substantively meaningful baseline models.

A Primer of Lisrel: Basic Applications and Programming for Confirmatory Factor Analytic Models

Abstract: Section I Introduction.- 1 The LISREL Confirmatory Factor Analytic (CFA) Model.- 1. Basic Concepts.- 2. The General LISREL Model.- 3. The LISREL CFA Model.- 4. Summary.- 2 Using the LISREL Program.- LISREL Input.- 1. Basic Rules.- 2. Problem Run Specification.- 3. Data Specification.- 4. Model Specification.- 5. Output Specification.- LISREL Output.- 1. Standard Output.- 2. Error Messages.- Summary.- Section II Single-Group Analyses.- 3 Application 1: Validating a Theoretical Construct.- Hypothesis 1: Self-Concept Is a Four-Factor Structure.- 1. LISREL Input.- 2. LISREL Output.- 3. The Issue of Post Hoc Model Fitting.- Hypothesis 2: Self-Concept Is a Two-Factor Structure.- Hypothesis 3: Self-Concept Is a One-Factor Structure.- Summary.- 4 Application 2: Validating a Measuring Instrument.- 1. The SDQIII: The Measuring Instrument Under Study.- 2. LISREL Input.- 3. LISREL Output.- 4. Post Hoc Analyses.- 5. Summary.- 5 Validating Multiple Traits Assessed by Multiple Methods: The Multitrait-Multimethod Framework.- 1. Assessment of Contruct Validity: The MTMM Matrix.- 2. LISREL Input.- 3. LISREL Output.- 4. Comparison of MTMM Models.- 5. Summary.- Section III Multigroup Analyses.- 6 Testing for Measurement and Structural Invariance of a Theoretical Construct.- 1. Testing for Factorial Invariance: The General Framework.- 2. Tests for Invariance Related to Self-Concept.- 3. LISREL Input for Multigroup Analyses.- 4. Testing Hypotheses Related to Factorial Invariance.- 5. Summary.- 7 Testing for Item Invariance of a Measuring Instrument.- 1. Tests for Invariance Related to the SDQIII.- 2. Tests for Invariance Across Ability.- 3. Summary.- 8 Testing for Invariant Latent Mean Structures.- 1. Tests for Invariance Related to Latent Self-Concept Means.- 2. Testing for the Invariance of Factor Covariance Structures.- 3. Testing for the Invariance of Factor Mean Structures.- 4. Summary.- References.- Appendix: Description of Data and Measuring Instruments.

Content-based second language instruction

Abstract: In the "Michigan Classics Edition of Content-Based Second Language Instruction," the authors provide updates on the field of CBI in second language acquisition since 1989.While the core of the book remains the same, new features discuss important CBI-related research and modifications to the pedagogy in the past many years."Content-Based Second Language Instruction, Michigan Classics Edition," now includes: a new preface a glossary of key terms an updated bibliography an epilogue highlighting the major developments in the field since 1989.

A source analysis of the late human auditory evoked potentials

Abstract: The intracerebral generators of the human auditory evoked potentials were estimated using dipole source analysis of 14-channel scalp recordings. The response to a 400-msec toneburst presented every 0.9 sec could be explained by three major dipole sources in each temporal lobe. The first was a vertically oriented dipole located on the supratemporal plane in or near the auditory koniocortex. This contributed to the scalp-recorded N1 wave at 100 msec. The second was a vertically oriented dipole source located on the supratemporal plane somewhat anterior to the first. This contributed to both the Nl and the sustained potential (SP). The third was a laterally oriented dipole source that perhaps originated in the magnopyramidal temporal field. This contributed a negative wave to the lateral scalp recordings at the latency of 145 msec. A change in the frequency of the toneburst elicited an additional negativity in the scalp-recording ---the mismatch negativity (MMN). When the frequency change was large, the mismatch negativity was composed of two distinct sources with sequential but partially overlapping activities. The earlier corresponded to the Nl dipole sources and the later to a more anteriorly located dipole with an orientation more lateral than Nl. Only the later source was active when the frequency change was small. MMN source activities peaked about 15 msec earlier in the contralateral hemisphere, while this difference was only 4 msec for the sources of the Nl.

The resolution of conflict.

Abstract: Of course, from childhood to forever, we are always thought to love reading. It is not only reading the lesson book but also reading everything good is the choice of getting new inspirations. Religion, sciences, politics, social, literature, and fictions will enrich you for not only one aspect. Having more aspects to know and understand will lead you become someone more precious. Yea, becoming precious can be situated with the presentation of how your knowledge much.

Reaction time after head injury: fatigue, divided and focused attention, and consistency of performance.

Abstract: Three groups of patients who had suffered head injury were compared with matched control subjects on reaction time (RT) tasks. Group I consisted of outpatients previously hospitalised for head injury of wide ranging degrees of severity, assessed at varying intervals after injury. Group II was composed of non-hospitalised mildly concussed patients. Group III was made up of head injured patients of varying degrees of severity assessed 7-10 months after initial hospitalisation for their injury. The reaction time tests were graded in difficulty, from a simple RT response to a complex choice RT test. In addition, subjects were compared in their ability to ignore redundant information during one of the choice RT tests. The findings indicate that traumatic brain injury causes slower information processing, deficits in divided attention, an impairment of focused attention, and inconsistency of performance.

Concept learning and the problem of small disjuncts

Abstract: Ideally, definitions induced from examples should consist of all, and only, disjuncts that are meaningful (e.g., as measured by a statistical significance test) and have a low error rate. Existing inductive systems create definitions that are ideal with regard to large disjuncts, but far from ideal with regard to small disjuncts, where a small (large) disjunct is one that correctly classifies few (many) training examples. The problem with small disjuncts is that many of them have high rates of misclassification, and it is difficult to eliminate the errorprone small disjuncts from a definition without adversely affecting other disjuncts in the definition. Various approaches to this problem are evaluated, including the novel approach of using a bias different than the "maximum generality" bias. This approach, and some others, prove partly successful, but the problem of small disjuncts remains open.

Hierarchy in picture segmentation: a stepwise optimization approach

Abstract: A segmentation algorithm based on sequential optimization which produces a hierarchical decomposition of the picture is presented. The decomposition is data driven with no restriction on segment shapes. It can be viewed as a tree, where the nodes correspond to picture segments and where links between nodes indicate set inclusions. Picture segmentation is first regarded as a problem of piecewise picture approximation, which consists of finding the partition with the minimum approximation error. Then, picture segmentation is presented as an hypothesis-testing process which merges only segments that belong to the same region. A hierarchical decomposition constraint is used in both cases, which results in the same stepwise optimization algorithm. At each iteration, the two most similar segments are merged by optimizing a stepwise criterion. The algorithm is used to segment a remote-sensing picture, and illustrate the hierarchical structure of the picture. >

Beef fat prevents alcoholic liver disease in the rat.

Abstract: The amount and type of dietary fat is thought to be important in the pathogenesis of alcoholic liver disease (ALD). We investigated the role of different dietary fats in our rat model for ALD. Liver pathology was evaluated in rats fed ethanol and lard or tallow or corn oil over a period of 2 to 6 months. All experimental animals were pair-fed the same diet as controls except that glucose was isocalorically replaced by ethanol. Rats fed tallow and ethanol developed none of the features of ALD, those fed lard and ethanol developed minimal to moderate disease, rats fed corn oil and ethanol developed the most severe pathology. The degree of histopathological abnormality correlated with the linoleic acid content of fat in the diet (tallow 0.7%, lard 2.5%, corn oil 56.6%). We postulate that linoleic acid facilitates development of ALD and provides an explanation for our previous epidemiological observations.

Infants of Postpartum Depressed Mothers: Temperament and Cognitive Status

Abstract: This study examined the association of postpartum depression with specific infant characteristics. Twenty-five diagnosed depressed and 25 nondepressed mothers and their 2-month-old infants participated in the study. The mothers completed measures of infant temperament and difficulty associated with infant care, and the infants were assessed using the Bayley Scales of Infant Development. Group comparisons indicated that, compared with the infants of the nondepressed mothers, the infants of the depressed women were less competent cognitively and expressed more negative emotions during the testing. The depressed mothers perceived their infants as more difficult to care for and more bothersome than did the nondepressed mothers, but did not attribute these difficulties to the temperament of their infants. These findings suggest that postpartum depression is associated with an identifiable pattern of infant behavior that may exacerbate depressed women's mood. A number of researchers have explored the association between maternal depression and child adjustment. The results of

The neutralization of organic cations

Abstract: Trois types de spectrometrie de masse sont etudies: la spectrometrie NIBS («Neutralized ion beam spectroscopy»), la spectrometrie NRMS («Neutralization-reionization mass spectrometry») et la spectrometrie de masse CIDI («Collision-induced dissociative ionization»)

Further experiments on the evolution of turbulent stresses and scales in uniformly sheared turbulence

Abstract: Measurements of the Reynolds stresses, integral lengthscales and Taylor microscales are reported for several cases of uniformly sheared turbulent flows with shear values in a range substantially wider than those of previous measurements. It is shown that such flows demonstrate a self-preserving structure, in which the dimensionless Reynolds stress ratios and the dissipation over production ratio, e/ P , remain essentially constant. Flows with sufficiently large $k_{\rm s} = (1/\overline{U_{\rm c}}){\rm d}\overline{U_1}dx_2$ have exponentially growing stresses and e/ P ≈ 0.68; a linear relationship between the coefficient in the exponentiallaw and k s is shown to be compatible with measurements having k s > 3. The possibility of a self-preserving structure with asymptotically constant stresses and e/ P ≈ 1.0 is also compatible with measurements, corresponding to flows with small values of k s . The integral lengthscales appear to grow according to a power law with an exponent of about 0.8, independent of the mean shear, while the Taylor microscales, in general, approach constant values. Various attempts to scale the stresses and to predict their evolution are discussed and the applicability of Hasen's theory is scrutinized. Finally, an ‘exact’ expression for the pressure-strain rate covariance is derived and compared to some popular models.

Chemical disinfection of non-porous inanimate surfaces experimentally contaminated with four human pathogenic viruses

Abstract: The chemical disinfection of virus-contaminated non-porous inanimate surfaces was investigated using coxsackievirus B3, adenovirus type 5, parainfluenza virus type 3 and coronavirus 229E as representatives of important nosocomial viral pathogens. A 10 microliter amount of the test virus, suspended in either faeces or mucin, was placed onto each stainless steel disk (about 1 cm in diameter) and the inoculum allowed to dry for 1 h under ambient conditions. Sixteen disinfectant formulations were selected for this study based on the findings of an earlier investigation with a human rotavirus. After 1 min exposure to 20 microliters of the disinfectant, the virus from the disks was immediately eluted into tryptose phosphate broth and plaque assayed. Using an efficacy criterion of a 3 log10 or greater reduction in virus infectivity titre and irrespective of the virus suspending medium, only the following five disinfectants proved to be effective against all the four viruses tested: (1) 2% glutaraldehyde normally used as an instrument soak, (2) a strongly alkaline mixture of 0.5% sodium o-benzyl-p-chlorophenate and 0.6% sodium lauryl sulphate, generally used as a domestic disinfectant cleaner for hard surfaces, (3) a 0.04% solution of a quaternary ammonium compound containing 7% hydrochloric acid, which is the basis of many toilet bowl cleaners, (4) chloramine T at a minimum free chlorine level of 3000 p.p.m. and (5) sodium hypochlorite at a minimum free chlorine concentration of 5000 p.p.m. Of those chemicals suitable for use as topical antiseptics, 70% ethanol alone or products containing at least 70% ethanol were ineffective only against coxsackievirus B3. These results emphasize the care needed in selecting chemical disinfectants for routine use in infection control.

There's No Tense Like the Present: Verbal -s Inflection in Early Black English.

Abstract: This article contributes to the understanding of the origin and function of verbal -s marking in the Black English grammar by systematically examining the behaviour of this affix in two corpora on early Black English. To ascertain whether the variation observed in (early and modern Black English) -s usage has a precedent in the history of the language, or is rather an intrusion from another system, we focus particularly on the linguistic and social contexts of its occurrence, within a historical and comparative perspective. Our results show that both third person singular and nonconcord -s are subject to regular, parallel environmental conditioning. The finding that both insertion and deletion are conditioned by the same factors suggests that verbal -s marking is a unitary process, involving both concord and nonconcord contexts. Moreover, the (few) variable constraints on verbal -s usage reported throughout the history of the English language remain operative in early Black English. These results, taken in conjunction with indications that -s marking across the verbal paradigm was a prestige marker in the dialect at some earlier point in time, lead us to hypothesize that the contemporary pattern might be a synchronic reflex of the constraint ranking on -s usage in the varieties of English that provided the linguistic model for the slaves. Many of the conditioning effects we report would have been subsequently overridden by the grammaticalization of -s as the Standard English agreement marker. We conclude that present-tense marking via verbal -s formed an integral part of the early Black English grammar.

Stretch-inactivated ion channels coexist with stretch-activated ion channels.

Abstract: Stretch-activated ion channels of animal, plant, bacterial, and fungal cells are implicated in mechanotransduction and osmoregulation. A new class of channel has now been described that is stretch-inactivated. These channels occur in neurons, where they coexist with stretch-activated channels. Both channels are potassium selective. The differing stretch sensitivities of the two channels minimize potassium conductance over an intermediate range of tension, with the consequence that, over this same range, voltage-gated calcium channels are most readily opened. Thus, by setting the relation between membrane tension and transmembrane calcium fluxes, stretch-sensitive potassium channels may participate in the control of calcium-dependent motility in differentiating, regenerating, or migrating neurons.

Adaptational Responses of Rainbow Trout to Lowered External Nacl Concentration: Contribution of the Branchial Chloride Cell

Abstract: 1. Whole-body ionic fluxes and gill chloride cell (CC) morphology were monitored in rainbow trout ( Salmo gairdneri ) exposed acutely or chronically to natural fresh water (NFW; [Na + ]=0.120 mmoll −1 ; [Cr]=0.164 mmoll −1 ) or artificially prepared fresh water with reduced [NaCl] (AFW; [Na+]=0.017 mmoll −1 ; [CT]=0.014 mmoll −1 ). 2. Net fluxes of Na + ( J net Na ) and Cl − ( J net Cl ) became extremely negative (indicating net NaCl loss to the environment) upon immediate exposure to AFW exclusively as a result of reduced NaCl influx ( J in Na and J in Na ). J net Na and J net Cl were gradually restored to control rates during prolonged (30 days) exposure to AFW. 3. The restoration of J net Cl in AFW was due both to increased J in Cl and to reduced Cl − efflux ( J out Cl ) whereas the primary response contributing to the restoration of J net Na a t was an increase of J Na in . 4. The total apical surface area of branchial CCs exposed to the external environment increased markedly after 24 h in AFW and remained elevated for 1 month as a consequence of enlargement of individual CCs and, to a lesser extent, increased CC density. J in Na and J in Na were correlated significantly with total CC apical surface area. 5. Plasma cortisol levels rose transiently in fish exposed to AFW. Treatment of NFW-adapted fish with cortisol for 10 days (a protocol known to cause CC proliferation) caused pronounced increases in J in Cl and J in Na , as measured in both NFW and AFW. 6. These results suggest that an important adaptational response of rainbow trout to low environmental [NaCl] is cortisol-mediated enlargement of branchial epithelial CCs which, in turn, enhances the NaCl-transporting capacity of the gill as a result of the proliferation of Na + and Cl − transport sites.

Distinguishing language contact phenomena: evidence from Finnish-English bilingualism

Abstract: Using a variationist, i.e. accountable, approach to the study of code-switching, this paper attempts to validate the equivalence contraint on intrasentential code-switching on the basis of natural speech data from two typologically different languages, Finnish and English. Though the data include many apparent exceptions to the constraint, the authors show how these are resolved by distinguishing on the one hand between code-switching and borrowing, and on the other between the different functions code-switching fulfills in the discourse.

Field responses of certain forest Coleoptera to conifer monoterpenes and ethanol.

Abstract: Field experiments using baited sticky stovepipe traps and Lindgren multiple funnel traps were done near Chalk River, Ontario, Canada, to determine the effects of conifer monoterpenes (α-pinene, β-pinene, myrcene, limonene, camphene and carene) and ethanol on the number of beetles captured. Several species of conifer-feeding beetles were attracted to the monoterpenes or to monoterpenes and ethanol, including species in the families Cerambycidae (Asemum striatum, Acmaeops proteus, Xylotrechus undulatus, Monochamus scutellatus), Curculionidae (Pissodes strobi, Hylobius pales), and Scolytidae (Dryocetes autographus, Ips grandicollis). Species of Buprestidae generally did not respond to the monoterpenes or to ethanol. Species of Cleridae (Thanasimus dubius, Enoclerus nigripes rufiventris, Enoclerus nigrifrons gerhardi) which are predators of conifer bark beetles were attracted to the monoterpenes. Synergism between monoterpenes and ethanol was evident forM. scutellatus, H. pales, andD. autographus. While α-pinene was the most potent attractant for most beetle species, monoterpenes other than α-pinene synergized attraction to ethanol forD. autographus. Attraction of beetles to commercial turpentine and ethanol did not differ significantly from attraction to a pure monoterpene blend and ethanol.

Bedload transport of mud as pedogenic aggregates in modern and ancient rivers

Abstract: Abundant sand-sized mud aggregates in the Cooper and Diamantina Rivers, Lake Eyre Basin, Australia are attributed to bedload transport of aggregates formed in deeply-cracked floodplain soils. The conditions required for formation of pedogenic mud aggregates are: (i) abundant clay containing at least minor swelling clay, and (ii) a climate with at least seasonally hot dry periods. The worldwide distribution of these soils (Vertisols) suggests that a significant amount of mud is transported as pedogenic aggregates by modern rivers. Ancient analogues in which mud aggregates and Vertisol profiles have been recognized are the Jurassic East Berlin Formation (Connecticut, USA) and the Carboniferous Maringouin Formation (New Brunswick and Nova Scotia, Canada). The dominant red mudstones of these formations are interpreted as mainly bedload sediments deposited by sheet floods in semi-arid palaeoclimates. The Triassic Hawkesbury Sandstone (NSW, Australia) also contains sand-sized mudstone aggregates, thought to be pedogenic, but its paleosol and other facies point to formation in a wetter palaeoclimate. The indications are that bedload transport of mud as pedogenic aggregates was as significant a process in ancient rivers as it is at present.

Fish gill water boundary layer: a site of linkage between carbon dioxide and ammonia excretion

Abstract: Carbon dioxide excreted across fish gills is hydrated catalytically to form HCO 3 − and H+ ions in water near the gill surface. We tested the possibility that CO2 excretion is functionally linked to ammonia excretion through chemical reactions in the gill-water boundary layer. A bloodperfused trout head preparation was utilized in which the convective and diffusive components of branchial gas transfer were controlled. Pre-incubation of blood perfusate with the carbonic anhydrase inhibitor, acetazolamide, reduced both carbon dioxide and ammonia excretion in the blood-perfused preparation. Increasing the buffering capacity of inspired ventilatory water significantly reduced ammonia excretion, but carbon dioxide excretion was unaffected. Each of these experimental treatments significantly reduced the acidification of ventilatory water flowing over the gills. It is proposed that the catalysed conversion of excreted CO2 to form HCO 3 − and H+ ions provides a continual supply of H+ ions need for the removal of NH3 as NH 4 + . We suggest, therefore, that acidification of boundary layer water by CO2 enhances blood-to-water NH3 diffusion gradients and facilitates ammonia excretion.

The influence of psychological status on respiratory symptom reporting.

Abstract: The American Thoracic Society respiratory symptom questionnaire (ATS-Q) is widely used and has provided valuable information in epidemiologic studies. To determine the influence of psychological status on respiratory symptoms, we compared subjects' ATS-Q responses to their Ilfeld Psychiatric Symptom Index (PSI) scores. To minimize the potential confounding effect of respiratory disease on the association between respiratory and psychological status, from a population-based survey of 3,628 subjects, we studied only the 600 “healthy” subjects, defined by the following characteristics: between 14 and 55 yr of age; never-smokers; no diagnoses of respiratory, heart, kidney, thyroid disease, or anemia; and normal spirometry (defined as an FEV1 and FVC > 80% of predicted). Associations were found between respiratory symptoms (cough, phlegm, wheeze, dyspnea) and PSI subscales (anxiety, anger, depression, and cognitive disturbance). Adjusted odds ratios for respiratory symptoms ranged from 1.13 to 2.15 for every 1...

Intra-articular fractures of the calcaneus.

Abstract: The results of computed tomography, combined with those of plain radiography, permit comprehensive assessment of the pattern of the fracture and, therefore, accurate classification and possible alteration of the mode of treatment