Showing papers by "University of Windsor published in 1996"

Semiparametric estimation of a hedonic price function

Abstract: SUMMARY Previous work on the preferred specification of hedonic price models usually recommended a Box-Cox model. In this paper we note that any parametric model involves implicit restrictions and they can be reduced by using a semiparametric model. We estimate a benchmark parametric model which passes several common specification tests, before showing that a semiparametric model outperforms it significantly. In addition to estimating the model, we compare the predictions of the models by deriving the distribution of the predicted log(price) and then calculating the associated prediction intervals. Our data show that the semiparametric model provides more accurate mean predictions than the benchmark parametric model.

Effect of grain size on friction and wear of nanocrystalline aluminum

Abstract: The friction and wear characteristics of nanocrystalline aluminum were investigated as a function of grain size. Nanocrystalline aluminum samples with an average diameter of 16.4 nm were produced using an r.f. magnetron sputtering technique. The grain size was increased (up to 98.0 nm) by an isothermal annealing treatment at 573 K. Hardness measurements were performed using an ultra-microhardness indentation system and it was observed that within the grain size range of 15–100 nm the hardness-grain size data could be well represented by the Hall-Petch relationship. Friction and wear measurements were made using a miniature pin-on-disk type tribometer under unlubricated conditions both in air and in vacuum. The coefficient of friction of aluminum tested against a stainless steel pin varied with the sliding distance. At the early stages of sliding the coefficient of friction rose to a peak value, and this was followed by a decrease to a steady-state value. The transition on the friction curve corresponded to a similar transition from a severe wear regime to a mild wear above a characteristic sliding distance on the cumulative volume loss versus sliding distance curve. The value of the peak coefficient of friction decreased from μp = 1.4 for aluminum with a coarse grain size (106 nm) to μp = 0.6 for the nanocrystalline aluminum with a grain size of 16.4 nm. The coefficient of friction of nanocrystalline aluminum showed a 30% increase when tested in vacuum. In the nanocrystalline grain range, the wear rates were found to be linearly dependent on the square root of the grain size. An empirical equation based on the Archard's Law is proposed to describe the effect of grain refinement on the wear resistance under unlubricated sliding conditions. A qualitative understanding of wear processes is developed in terms of the variation of the surface morphology and subsurface strength with sliding distance.

Variational calculations of dispersion coefficients for interactions among H, He, and Li atoms.

Abstract: The dispersion coefficients ${\mathit{C}}_{6}$, ${\mathit{C}}_{8}$, and ${\mathit{C}}_{10}$ for the interactions among H, He, and Li are calculated using variational wave functions in Hylleraas basis sets with multiple exponential scale factors. With these highly correlated wave functions, significant improvements are made upon previous calculations and our results provide definitive values for these coefficients. \textcopyright{} 1996 The American Physical Society.

Natural Musical Intervals: Evidence From Infant Listeners

Abstract: Ancient and medieval scholars considered tones related by simple (small-integer) ratios to be naturally pleasing, but contemporary scholars attribute the special perceptual status of such sounds to exposure We investigated the possibility of processing predispositions for some tone combinations by evaluating infants' ability to detect subtle changes to patterns of simultaneous and sequential tones Infants detected such changes to pairs of pure tones (intervals) only when the tones were related by simple frequency ratios This was the case for 9-month-old infants tested with harmonic (simultaneous) intervals and for 6-month-old infants tested with melodic (sequential) intervals These results are consistent with a biological basis for the prevalence of particular intervals historically and cross-culturally

Semiparametric Estimation of Stochastic Production Frontier Models

Abstract: This article extends the linear stochastic frontier model proposed by Aigner, Lovell, and Schmidt to a semiparametric frontier model in which the functional form of the production frontier is unspecified and the distributions of the composite error terms are of known form. Pseudolikelihood estimators of the parameters characterizing the two error terms of the model are constructed based on kernel estimation of the conditional mean function. The Monte Carlo results show that the proposed estimators perform well in finite samples. An empirical application is presented. Extensions to a partially linear frontier function and to more flexible one-sided error distributions than the half-normal are discussed

Inland dispersal of adult aquatic insects

Abstract: 1. Adult caddisflies (Trichoptera) and mayflies (Ephemeroptera) were light-trapped on summer evenings along the Detroit River and Lake St. Clair, near Windsor, Ontario, Canada. Light traps were located at the shore and at increasing distances inland up to 5 km, and were operated simultaneously for 2 h following sunset. Catches of five species of caddisflies of the family Hydropsychidae (Cheumatopsychecampyla, Cheumatopsychespeciosa, Hydropsychehageni, Hydropsychephalerata, Macrostemumzebratum) and the mayfly Hexagenia (Ephemeridae) were used to examine inland distribution. 2. Inland dispersal was limited: catches of caddisflies declined at a greater than exponential rate with increasing distance from shore. Mean dispersal distance from the shoreline ranged from 650 to 1845 m. Smaller caddisfly species dispersed shorter distances than larger caddisflies and Hexagenia. 3. Inland distribution of adult caddisflies exhibited considerable interspecific variation: distribution was inconsistent among trials for Hexagenia, possibly owing to timing of collections in relation to periods of peak emergence. 4. Sex ratios of caddisflies were female biased at most sites. No consistent bias was observed for Hexagenia. Different inland distribution patterns were observed for males and females. The differences appeared to reflect species-specific reproductive strategies.

Non-linear prediction of security returns with moving average rules

Abstract: Over the years, investors and the technical analysts have devised hundreds of technical market indicators in an effort to forecast the trend of a security market. Recent literature provides evidence that these rules may provide positive profits after accounting for transaction costs. This clearly contradicts the theory of the efficient market hypothesis which states that security prices cannot be forecasted from their past values or other past variables. This paper uses the daily Dow Jones Industrial Average Index from January 1963 to June 1988 to examine the linear and non-linear predictability of stock market returns with buy—sell signals generated from the moving average rules with a band between the short and the long averages. Strong evidence of non-linear predictability is found in the stock market returns by using the past buy and sell signals of these rules.

Sensory consonance and the perceptual similarity of complex‐tone harmonic intervals: Tests of adult and infant listeners

Abstract: Two experiments examined the influence of sensory consonance on the perceptual similarity of simultaneous pairs of complex tones (harmonic intervals). In experiment 1, adults heard a sequence of five consonant intervals (each a perfect fifth, or 7 semitones) and judged whether a subsequently presented test interval was a member of the sequence. Discrimination performance was better when the test interval was dissonant (tritone, 6 semitones) rather than consonant (perfect fourth, 5 semitones), despite the fact that the change in interval width was twice as great for the consonant than for the dissonant comparison. In experiment 2, 7‐month‐old infants were tested with an operant headturn procedure in a similar design and exhibited an identical pattern of responding. Hence, for both age groups, consonance was more important than interval width in determining the perceived similarity of harmonic intervals.

Cross‐Cultural Testing of Three Social Cognitive Theories: An Application to Condom Use1

Abstract: The cross-cultural validity of Fishbein and Ajzens theory of reasoned action Ajzens theory of planned behavior and Triandis theory of interpersonal behavior was tested and theories applied to understanding the intention to use a condom for each episode of sexual intercourse with a new partner in the Latin American English-speaking Caribbean and South Asian Canadian communities. The approximately 350 participants of mean age 26.8-31.0 years in each of the three groups were recruited from multiple ethnocultural venues. While there were approximately equal numbers of men and women represented in the Latin American and English-speaking Caribbean groups no South Asian woman participated. Cross-cultural validity was found among the three theories. However the theories of Ajzen and Triandis performed better than the theory of Fishbein and Ajzen. The authors recommend that role beliefs and moral norm be added to Ajzens model in the effort to maximize its predictive and explanatory ability.

Logic, Art and Argument)

Abstract: Most infonnallogic texts and articles assume a verbal account of reasoning which defines "argument" as a set of sentences. The present paper broadens this definition in order to account for "visual arguments" which are communicated with nonverbal visual images. Standard approaches to verbal arguments are extended in a way that allows them to explain and evaluate visual argumentation.

Amphibian species richness and distribution in relation to pond water chemistry in south‐western Ontario, Canada

Abstract: 1. We assessed the patterns of amphibian species richness and distribution in relation to water chemistry over a large geographical area in 1992–94. 2. Thirteen amphibian species were observed at 180 ponds, with mean species richness 3.5 ± 0.13 species per pond (range zero to nine). Water samples were collected from 143 ponds, analysed for fifteen chemical variables, and further analysed by multivariate statistical techniques. 3. Water in the study area was hard, alkaline and well-buffered against pH change, and most ponds were eutrophic. Amphibian species richness was negatively correlated with five chemical variables (chloride, conductivity, magnesium, total hardness, turbidity). 4. Principle components analysis reduced the data set to four chemical components that explained 65.4% of the variance in the original variables. Principle component scores were retained for use in further multivariate tests. Multiple regression accounted for only 19.0% of the variance in amphibian species richness. Discriminant function analysis (DFA) was used to determine if water chemistry variables discriminated among species, but it was only able to classify 17.5% of cases correctly. DFA was also used to determine if water chemistry distinguished between used and unused sites for individual species. DFA was moderately successful, classifying 61–77% of cases correctly. 5. General water chemistry appears to play only a minor part in affecting amphibian species richness in south-western, Ontario. However, chemical variables may be helpful to distinguish between used and unused sites for some species.

High-temperature wear and deformation processes in metal matrix composites

Abstract: Dry-sliding wear behaviors of a particulate-reinforced aluminum matrix composite 6061 Al-20 pet A12O3 and an unreinforced 6061 Al alloy were investigated in the temperature range 25 °C to 500 °C against a SAE 52100 bearing steel counterface. Experiments were carried out at a constant sliding speed of 0.2 m·s- at different test loads. The deformation behavior of the materials was studied by performing uniaxial compression tests in the same temperature range as the wear tests. Both alloys showed a mild-to-severe wear transition above a certain test temperature. In the mild wear regime, the wear rate and the coefficient of friction of the unreinforced 6061 Al decreased slightly with temperature, but the temperature had almost no effect on the wear rate and the coefficient of friction of the 6061 Al-20 pet Al2O3 in the same regime. Particulate reinforcement led to an increase in the transition temperature and a 50 to 70 pet improvement in the wear resistance in the severe wear regime. This was attributed to the formation of tribological layers consisting of comminuted A12O3 particles at the contact surface. High-temperature compression tests showed that the flow strength of 6061 Al-20 pet A12O3 and 6061 Al decreased monotonically with temperature and both alloys exhibited a work-softening behavior at temperatures higher than the inflection point on the flow stressvs temperature curves. The logarithmic maximum stressvs reciprocal temperature relationship was not linear, indicating that the deformation processes were too complicated to be characterized by a single activation energy over the whole temperature range. For the range of 250 °C to 450 °C, the activation energy for deformation was estimated to be 311 kJ·mol-1; for both the matrix alloy and the composite. Severe wear proceeded by thermally activated deformation processes involving dynamic recrystallization along a subsurface strain gradient. A power-Arrhenius type relationship was found to describe well the observed dependence of severe wear rates on the applied load and temperature. This relationship was used to calculate an apparent activation energy for wear of 87 kJ·mol-1 for the particulate-reinforced composite and 33 kJ·mol-1 for the matrix alloy. The wear regimes at elevated temperatures are represented in a deformation mechanism map and the relationship between high-strain deformation processes and severe wear are discussed.

The Mechanism of Photochemical Release of Nitric Oxide from S-Nitrosoglutathione

Abstract: — Laser flash photolysis of S-nitroso complexes of glutathione (GSNO) and bovine serum albumin (BSANO) via excitation at 355 nm has been used to investigate the photogeneration of nitric oxide (NO) and subsequent radical reactions. In the case of GSNO, liberation of NO was confirmed by its oxidation of oxyhemoglobin to met hemoglobin. Initial NO release is via homolytic cleavage of the S-N bond to produce the glutathione thiyl radical, GS, which can subsequently react with (a) ground-state GSNO (k= 1.7 × 109M−1/i> s−1) to yield additional NO and oxidized glutathione, GSSG; and (b) oxygen (k= 3.0 × 109M−1 s−1) to give the glutathione peroxy radical, GSOO, which subsequently reacts with ground-state GSNO (k= 3.8 × 108M−1 s−1), also producing additional NO and GSSG. The relative concentrations of oxygen and GSNO in the system determine the major pathway for removal of G'. These secondary reactions occur at such high rates that they preclude radical recombination under low-intensity irradiation conditions. The quantum yield of overall loss of GSNO thus varies with both GSNO and oxygen concentrations; a value of 0.66 was determined for an aerated solution of GSNO (0.86 mM). In the case of GSNO, therefore, generation of NO is not due solely to homolysis of the S-N bond; secondary reactions of the radicals formed lead to further NO liberation. In rationalizing the known phototoxicity of GSNO, possible contributions from thiyl and thiyl-derived radicals should be considered. In contrast to GSNO, direct excitation of BSANO (containing one bound NO group per molecule) led to photodecomposition with a quantum yield of 0.09 but no evidence was obtained for liberation of NO into the bulk medium.

Gambling behavior of adolescent gamblers

Abstract: An adolescent version of the South Oaks Gambling Screen was administered to 965 high school students, aged 14 to 19 years, in the city of Windsor, Ontario. Ninety percent of the adolescents were involved in gambling activities and a substantial proportion of these were engaged in underage gambling. High levels of problem gambling behaviors were found. Problem gambling behaviors were found to be related to the number of different gambling activities and the amount of money gambled. Problem gambling was defined as a score of five or more on the SOGS-RA screen utilizing a scoring method that paralleled the SOGS scoring method. Problem gambling levels were estimated to be 8.1%±1.8% of the adolescent sample. There were significant gender differences in the level of problem gambling, but no significant difference with age was found.

A combined branch-and-bound and genetic algorithm based approach for a flowshop scheduling problem

Abstract: In this paper, we study the application of a meta-heuristic to a two-machine flowshop scheduling problem. The meta-heuristic uses a branch-and-bound procedure to generate some information, which in turn is used to guide a genetic algorithm's search for optimal and near-optimal solutions. The criteria considered are makespan and average job flowtime. The problem has applications in flowshop environments where management is interested in reducing turn-around and job idle times simultaneously. We develop the combined branch-and-bound and genetic algorithm based procedure and two modified versions of it. Their performance is compared with that of three algorithms: pure branch-and-bound, pure genetic algorithm, and a heuristic. The results indicate that the combined approach and its modified versions are better than either of the pure strategies as well as the heuristic algorithm.

An efficient tree architecture for modulo 2 n + 1 multiplication

Abstract: Modulo 2n+1 multiplication plays an important role in the Fermat number transform and residue number systems; the diminished-1 representation of numbers has been found most suitable for representing the elements of the rings. Existing algorithms for modulo (2n+1) multiplication either use recursive modulo (2n+1) addition, or a regular binary multiplication integrated with the modulo reduction operation. Although most often adopted for largen, this latter approach requires conversions between the diminished-1 and binary representations. In this paper we propose a parallel fine-grained architecture, based on a Wallace tree, for modulo (2n+1) multiplication which does not require any conversions; the use of a Wallace tree considerably improves the speed of the multiplier. This new architecture exhibits an extremely modular structure with associated VLSI implementation advantages. The critical path delay and the hardware requirements of the new multiplier are similar to that of a correspondingn×n bit binary multiplier.

The impact of organizational downsizing on the job satisfaction of nurses.

Abstract: Professional nurses across Canada are being affected by health reform initiatives designed to deinstitutionalize the health care system This panel study examined the impact this restructuring has had on nurses' overall job satisfaction as well as their satisfaction with various aspects of their job and work environment The participants consisted of 345 nurses employed in 3 community hospitals in southwestern Ontario Hospital downsizing had relatively little effect on overall job satisfaction, satisfaction with kind of work, amount of work, and physical work conditions However, compared to before the downsizing, nurses reported a significant deterioration in satisfaction with their career future, hospital identification, supervision, and co-workers following the implementation of restructuring initiatives We discuss the organizational and management implications of these findings and suggest ways that hospital administrators can minimize the negative effects of downsizing on nursing professionals

Alkaline single‐cell gel (comet) assay and genotoxicity monitoring using two species of tadpoles

Abstract: Small bodies of water (e.g., creeks, ponds, and drainage ditches) have received very little attention in genotoxicity studies, yet these areas are important because they are often the first to be affected by industrial effluents, sewage contaminants, accidental spills, internal combustion engine emissions, landfill runoffs, and pesticide uses. To address this deficiency, we examined erythrocytes in two species of tadpoles, Rana clamitans and Bufo americanus, using the alkaline single-cell gel (SCG) (“comet”) assay. This approach involves detection, under alkaline conditions, of cell DNA fragments, which on electrophoresis migrate from the nuclear core, resulting in a “comet-with-tail” formation. Exposure of R. clamitans tadpoles to a range of concentrations of methyl methanesulfonate (MMS) produced a linear increase in DNA length to DNA core width ratios. This is consistent with findings in a number of other species. Time-dose experiments using MMS suggest that the peak level of DNA damage in R. clamitans tadpoles occurred 42 hr after exposure. B. americanus tadpoles exposed to 6.25 mg/l of MMS for 12 hours had a significant increase in DNA damage over that seen in the controls. Freshly caught R. clamitans tadpoles from Highgate and B. americanus tadpoles from Duart, both on the north shore of Lake Erie, gave ratios of 2.78 and 2.07, respectively. This region of Ontario is a prime agricultural area and pesticide use is extensive. Tadpoles from Highgate and Duart, maintained in the laboratory for 4 months and 6 weeks, respectively, gave ratios of 1.29 and 1.44. The results of the SCG procedure in tadpoles indicate that this assay is extremely sensitive and suitable for detecting genotoxicity in the environment. © 1996 Wiley-Liss, Inc.

The Substitutability of Real Estate Assets

Abstract: This paper investigates the degree of substitutability between securitized real estate assets and real estate assets whose prices are appraisal-based. Given the insensitivity of unsecuritized asset's returns to the returns on stock market indices, equilibrium asset pricing models cannot be used to compare these two avenues of investment. Two assets are deemed substitutable if the information sets underlying unbiased, minimum error variance estimates of their pricing parameters are identical. The empirical evidence shows that the prices of the transactions-based assets—real estate investment trusts and the stock price index of the home building industry—follow a random walk while the prices of the appraisal-based assets—FRC/NCREIF indices—do not. The variance decompositions of the vector autoregressions also show that the level of economic activity helps predict the price indices of appraisal-based assets while the stock market index and the term structure of interest rates are better predictors of the prices of transactions-based assets