Showing papers by "Carleton University published in 1993"

Delta-sigma modulation in fractional-N frequency synthesis

Abstract: A description is given of a delta-sigma ( Delta - Sigma ) modulation and fractional-N frequency division technique for performing indirect digital frequency synthesis using a phase-locked loop (PLL). The use of Delta - Sigma modulation concepts results in beneficial shaping of the phase noise (jitter) introduced by fractional-N division. The technique has the potential to provide low phase noise, fast settling time, and reduced impact of spurious frequencies when compared with existing fractional-N PLL techniques. >

Vegetation effects on the isotope composition of oxygen in atmospheric CO2

Abstract: THE 18O/16O ratio in atmospheric CO2 is a signal dominated by CO2 exchange with the terrestrial biosphere and it has considerable potential to resolve the current importance of the oceans and individual terrestrial biomes as net sinks for anthropogenic CO2. Fractionation of the oxygen isotopes of CO2 occurs in plants owing to differential diffusion of C18O16O and C16O2 and to isotope effects in oxygen exchange with chloroplast water. Kere we investigate the consequences of these effects for the global distribution of oxygen isotopes in CO2. We predict that 18O isotopic exchange fluxes, especially between the atmosphere and terrestrial biosphere, are large, with considerable spatial variation. Near 70° N, where precipitation (and soil water) is most depleted in 18O, photosynthesis and respiration both deplete the atmospheric CO2 of O. This provides an explanation for the depletion of 18O in atmospheric CO2 at high northern latitudes1.

Relative Power of the Wilcoxon Test, the Friedman Test, and Repeated-Measures ANOVA on Ranks

Abstract: Many introductory statistics textbooks in education, psychology, and the social sciences consider the Friedman test to be a nonparametric counterpart of repeated-measures ANOVA, just as the Kruskal-Wallis test is a counterpart of oneway ANOVA However, it is known in theoretical statistics that the Friedman test is a generalization of the sign test and possesses the modest statistical power of the sign test for normal as well as many nonnormal distributions Although not familiar to researchers, another significance test that can be regarded as a nonparametric counterpart of repeated-measures ANOVA is a rank-transformation procedure, in which the usual parametric statistical analysis is performed on ranks replacing the original scores In the present computer simulation study we compared the ordinary paired-samples Student t test, the Wilcoxon signed-ranks test, and the sign test for correlated samples from normal, uniform, mixed-normal, exponential, Laplace, and Cauchy distributions, for which t

Evolution of the hind wing in coleoptera

Abstract: A survey is made of the major features of the venation, articulation, and folding in the hind wings of Coleoptera. The documentation is based upon examination of 108 Coleoptera families and 200 specimens, and shown in 101 published figures. Wing veins and articular sclerites are homologized with elements of the neopteran wing groundplan, resulting in wing vein terminology that differs substantially from that generally used by coleopterists. We tabulate the differences between currently used venational nomenclature and the all-pterygote homologous symbols. The use of the neopteran groundplan, combined with the knowledge of the way in which veins evolved, provides many strong characters linked to the early evolutionary radiation of Coleoptera. The order originated with the development of the apical folding of the hind wings under the elytra executed by the radial and medial loop. The loops, which are very complex venational structures, further diversified in four distinctly different ways which mark the highest (suborder) taxa. The remaining venation and the wing articulation have changed with the loops, which formed additional synapomorphies and autapomorphies at the suborder, superfamily, and sometimes even family and tribe levels. Relationships among the four currently recognized suborders of Coleoptera are reexamined using hind wing characters. The number of wing-related apomorphies are 16 in Coleoptera, seven in Archostemata + Adephaga–Myxophaga, four in Adephaga–Myxophaga, seven in Myxophaga, nine in Archostemata, and five in Polyphaga. The following phylogenetic scheme is suggested: Polyphaga [Archostemata (Adephaga + Myxophaga)]. Venational evidence is given to define two major lineages (the hydrophiloid and the eucinetoid) within the suborder Polyphaga. The unique apical wing folding mechanism of beetles is described. Derived types of wing folding are discussed, based mainly on a survey of recent literature. A sister group relationship between Coleoptera and Strepsiptera is supported by hind wing evidence.

Exploring the Link Between Giftedness and Self-Concept

Abstract: We explored three broad issues in the article. First, do gifted and nongifted children differ in their self-concepts? Second, what are the effects on the self-concept of labeling the child as gifted? Third, are there any effects on self-concept of placing a child in special programs for the gifted? The review begins with a discussion of theoretical and methodological issues associated with the self-concept and giftedness constructs. This is followed by a meta-analysis of studies bearing on the three issues. Two types of studies are reviewed: (a) cases where gifted and average students are compared in terms of the self-concept and (b) studies in which gifted children are exposed to differential programming and the effects on self-concept explored. The studies indicated generally higher academic self-concepts for gifted students, but otherwise the results of the investigations were highly variable. The article concludes with a discussion of research and practical implications.

Emotional attachments in abusive relationships: a test of traumatic bonding theory.

Abstract: An empirical test of traumatic bonding theory, the notion that strong emotional attachments are formed by intermittent abuse, is reported. In-depth assessments (interviews plus questionnaires) were conducted on 75 women who had recently left abusive relationships (50 where physical violence had occurred). The study found support for the effect of relationship dynamic factors such as extremity of intermittent maltreatment and power differentials on long-term felt attachment for a former partner, experienced trauma symptoms, and self-esteem, immediately after separation from an abusive partner and again after a six month interim. All three of these measures were significantly intercorrelated within each time period. Each measure at Time 1 correlated significantly with each corresponding measure at Time 2. After six months attachment had decreased by about 27%. Relationship variables (total abuse, intermittency of abuse and power differentials) accounted for 55% of the variance in the attachment measure at Time 2 indicating prolonged effects of abuse suffered in the relationship.

Efficient search and design procedures for robust multi-stage VQ of LPC parameters for 4 kb/s speech coding

Abstract: A tree-searched multistage vector quantization (VQ) scheme for linear prediction coding (LPC) parameters which achieves spectral distortion lower than 1 dB with low complexity and good robustness using rates as low as 22 b/frame is presented. The M-L search is used, and it is shown that it achieves performance close to that of the optimal search for a relatively small M. A joint codebook design strategy for multistage VQ which improves convergence speed and the VQ performance measures is presented. The best performance/complexity tradeoffs are obtained with relatively small size codebooks cascaded in a 3-6 stage configuration. It is shown experimentally that as the number of stages is increased above the optimal performance/complexity tradeoff, the quantizer robustness and outlier performance can be improved at the expense of a slight increase in rate. Results for log area ratio (LAR) and line spectral pairs (LSPs) parameters are presented. A training technique that reduces outliers at the expense of a slight average performance degradation is introduced. The method significantly outperforms the split codebook approach. >

Rank Transformations and the Power of the Student T Test and Welch T' Test for Non-Normal Populations with Unequal Variances

Abstract: Classical studies have disclosed that parametric significance tests such as t and F are robust under violation of homogeneity of variance, provided sample sizes are equal. But relatively little is known about effects of unequal variances on nonparametric counterparts of the tests or about non - normality combined with unequal variances. In the present computer simulation study, the Student t test and the Welch version of the t test (the t' test) were performed first on the initial sample values and then on ranks of the sample values. Unequal variances together with unequal N's markedly altered the probability of Type I and Type II errors for normal and for eight kinds of non - normal distributions, including mixed - normal, exponential, lognormal, and Cauchy distributions. Substitution of the Welch t' test for the Student t test eliminated effects of unequal variances, but not effects of non - normality. The t test on ranks, which is equivalent to the Mann - Whitney - Wilcoxon test, was more powerful than the Student t test for several non - normal distributions, but exhibited a substantial power loss when variances were unequal. The Welch t' test in conjunction with the rank transformation simultaneously counteracted effects of both non - normality and unequal variances. Resume Des etudes classiques ont revele que des tests d'hypothese parametriques comme les tests t et F sont rigoureux dans les cas ou l'homogeneite de la variance est perturbee, pourvu que les echantillons aient la me@me taille. Mais on en sait relativement peu au sujet des effets des variances inegales sur les versions non parametriques des tests ou au sujet de la non - normalite combinee a des variances inegales. Dans la presente etude de simulation par ordinateur, le test de Student et la version Welch du test t ont ete appliques d'abord aux valeurs initiales de l'echantillon, puis aux rangs des valeurs. Les variances inegales jointes aux N inegaux modifiaient nettement la probabilite des erreurs de type I et de type II dans le cas des distributions normales et de huit genres de distributions non normales, dont les distributions mixtes - normales, exponentielles, normales logarithmiques, et des distributions de Cauchy. Le remplacement du test de Student par le test t de Welch a elimine les effets des variances inegales, mais non ceux de la non - normalite. Le test t effectue sur les rangs, qui equivaut au test de Mann - Whitney - Wilcoxon, etait plus rigoureux que le test de Student pour plusieurs distributions non normales, mais il perdait considerablement de pouvoir lorsque les variances etaient inegales. Le test t de Welch joint a la transformation en rangs neutralise simultanement les effets de la non - normalite et des variances inegales.It is well known that parametric significance tests such as t and F are based on an assumption of equality of variances in treatment groups, or "homogeneity of variance," as it is known. For a long time, researchers have been concerned about how violation of this assumption affects statistical tests (see, for example, Box, 1953, Glass, Peckham, & Sanders, 1972, Scheffe, 1959). As a result of numerous simulation studies, as well as theoretical investigations, there is now general agreement that the t and F tests are robust under violation of homogeneity of variance, provided sample sizes are equal, although some exceptions have been found recently (Tomarkin & Serlin, 1986).When sample sizes are unequal, the Type I error probabilities of the tests are decidedly influenced by unequal variances (see, for example, Boneau, 1960, Box, 1953, Games & Howell, 1976, Hsu, 1938, Kohr & Games, 1977, Ramsey, 1980, Rogan & Keselman, 1977, Scheffe, 1959). It has been found that, when the larger variance is associated with the larger sample size, there is a depression of the Type I error probability, and when the larger variance is associated with the smaller sample size, there is a spurious elevation of that probability. …

Audibility and identification of auditory alarms in the operating room and intensive care unit

Abstract: The audibility and the identification of 23 auditory alarms in the intensive care unit (ICU) and 26 auditory alarms in the operating rooms (ORs) of a 214-bed Canadian teaching hospital were investigated. Digital tape recordings of the alarms were made and analysed using masked-threshold software developed at the Universite de Montreal. The digital recordings were also presented to the hospital personnel responsible for monitoring these alarms on an individual basis in order to determine how many of the alarms they would be able to identify when they heard them. Several of the alarms in both areas of the hospital could mask other alarms in the same area, and many of the alarms in the operating rooms could be masked by the sound of a surgical saw or a surgical drill. The staff in the OR (anaesthetists, anaesthesia residents, and OR technologists) were able to identify a mean of between 10 and 15 of the 26 alarms found in their operating theatres. The ICU nurses were able to identify a mean of between 9 and 14 of the 23 alarms found in their ICU. Alarm importance was positively correlated with the frequency of alarm identification in the case of the OR, rho = 0.411, but was not significantly correlated in the case of the ICU, rho = 0.155. This study demonstrates the poor design of auditory warning signals in hospitals and the need for standardization of alarms on medical equipment.

The effects of forest fragmentation on genetic variation in Acer saccharum Marsh. (sugar maple) populations

Abstract: To investigate the effects of forest fragmentation on genetic variation in Acer saccharum Marsh. (Aceraceae) populations, aflozyme variation in eight populations in fragmented forest patches was compared to variation in eight population samples from extensive continuous forest. Contrary to theoretical predictions, increased genetic drift and inbreeding have not led to reduced within-individual or within-population genetic variation in patch populations. Polymorphism and individual heterozygosity were slightly higher in patch than continuous forest populations. However, overall, founder effects may have resulted in the loss of six alleles in the fragmented forest system. Maintenance of genetic variation in patch populations may be because of the limited number of generations since fragmentation occurred, or because populations in patches have not been reduced below the size of normal breeding associations for A. saccharum. Comparison of the distribution of alleles among populations, between patch and continuous forest, suggests that the higher genetic variation in patch populations may be the result of increased interpopulation gene flow.

Anthropometric craniofacial pattern profiles in down syndrome

Abstract: A series of 21 anthropometric craniofacial measurements was performed on 199 individuals with Down syndrome (DS), age 6 months to 61 years. These were compared to age and sex-matched normal standards, and Z score pattern profiles were constructed. These profiles confirmed brachycephaly and reduced ear length. With increasing age, maxillary growth was reduced in comparison to mandibular growth. Clinically, this was manifested by a change in facial shape from the characteristic round face of infancy to an oval shape in later life. Stepwise forward discriminant function analysis identified a subset of three variables (ear length, maxillary arc, and upper facial depth) which could accurately classify greater than 99% of the individuals in the combined sample of affected and unaffected individuals. Of the subjects with DS, 96.8% were classified correctly. These findings demonstrate the usefulness of anthropometric craniofacial pattern profiles in defining abnormal facial dimensions in particular syndromes and documenting the changes that occur with age. The technique should facilitate syndrome recognition, identification of carriers, and comparisons between syndromes. © 1993 Wiley-Liss, Inc.

The battered woman syndrome: effects of severity and intermittency of abuse.

Abstract: The concept of a battered woman syndrome was tested by assessing 50 battered women and 25 emotionally abused women who had recently left their relationships. For both groups, essential features of the syndrome were present and were significantly interrelated. Dynamic features of the prior abusive relationship correlated significantly with these sequelae. The concept of intermittency is proposed as an alternative to the cycle of violence theory as main contributor to the syndrome. Predictability of abuse was found to be unrelated to the intermittency measure.

The effects of complainant age and expert psychological testimony in a simulated child sexual abuse trial

Abstract: Mock jurors viewed a videotape of a simulated child sexual abuse trial and then deliberated to a unanimous verdict. The complainant was described as either a 13- or 17-year-old female child. Jurors voted to convict more often when the younger complainant was seen, and the younger complainant was rated as more credible than the older complainant. Female jurors voted the defendant guilty more often and rated the complainant as being more credible than male jurors. Jurors voted to convict more often and rated the defendant as less credible when expert psychological testimony was specific to the case than when they were presented with either general expert testimony or no expert testimony. Jurors who saw a psychological expert testify became less accepting of child sexual abuse misconceptions than those in the no expert control condition. The implications of these findings are discussed.

American robin nestlings compete by jockeying for position

Abstract: We investigated whether nestling American robins (Turdus migratorius) were capable of influencing food distribution in their nests by perceiving that certain sectors of the nest received a relatively high proportion of feedings and positioning themselves accordingly. Feeding observations were obtained from videotape recordings taken at different stages of the nestling period. Parents generally arrived at a predictable location on the nest rim and allocated proportionally more food to nestlings in the central position. The degree of nestling movement was significantly positively correlated with variation in the predictability of parental arrival locations on the nest rim. Furthermore, nestlings moved more in broods suffering brood reduction. This suggests that when competition for food is intense and the location of parental arrival is predictable, nestlings respond by jockeying for access to the most favorable (i.e., central) position in the nest. We conclude that jockeying for position by nestlings can influence the pattern of food allocation by parents, and that hungry nestlings can improve their competitive standing against nestmates by moving to positions where parents are more likely to feed them.

Coefficient Alpha as an Estimate of Test Reliability Under Violation of Two Assumptions

Abstract: Through use of computer simulation, the central tendency and variability of coefficient alpha were examined under violation of two assumptions made in the derivation of the formula. When assumption...

Performance of some new preliminary test ridge regression estimators and their properties

Abstract: The problem of estimation of the regression coefficients in a multiple regression model is considered under multicollinearity situation when it is suspected that the regression coefficients may be restricted to a subspace. We present the estimators of the regression coefficients combining the idea of preliminary test and ridge regression methodology. Accordingly, we consider three estimators, namely, the unrestricted ridge regression estimator (URRE), the restricted ridge regression estimator (RRRE), and finally, the preliminary test ridge regression estimator (PTRRE). The biases, variancematrices and mean square errors (mse) of the estimators are derived and compared with the usual estimators. Regions of optimality of the estimators are determined by studying the mse criterion. The conditions of superiority of the estimators over the traditional estimators as in Saleh and Han (1990) and Ali and Saleh (1991) have also been discussed.

Parasite faunas, testosterone and secondary sexual traits in male red-winged blackbirds

Abstract: We examined associations among parasite infections, secondary sexual traits and testosterone in male red-winged blackbirds sampled at the start of the breeding season. Parasites quantified included ectoparasitic lice and mites and endoparasitic blood protozoans, nematodes, trematodes and cestodes. Secondary sexual traits that we quantified included body size, epaulet size and color, song repertoire size and song switching rate, and behavioral responses to male and female models. Overall we found few significant associations between parasites and secondary sexual traits, between secondary sexual traits and testosterone, or between parasites and testosterone. In addition, most parasite taxa appeared to infect birds independently, although the low prevalence (<50%) of many of the parasites meant that our sample sizes were too small to detect weak associations. Our most promising results were obtained for ectoparasitic mites, which tended to occur on birds uninfected with other parasites, on birds with longer epaulets, and on birds with higher levels of testosterone. Epaulet length and testosterone are both probable correlates of dominance in this species. Further research will be required to determine whether there is a causal link between the immunosuppressive effects of testosterone and the mite infections, and between testosterone, epaulet length and male mating success.

Rates of water uptake into the mature root system of maize plants

Abstract: SUMMARY A new method of measuring water uptake by roots is applied to whole root systems of large maize plants growing in aeroponic (mist) culture. The method depends on the build-up of concentration of dye (sulphorhodamine G) on and in the root surface, when it is fed in the mist. Water enters the roots rapidly, but the dye is separated from the water by osmotic filtration and penetrates the apoplast only by very slow diffusion. The dye accumulates progressively with time on roots on transpiring plants, but not on roots of non-transpiring controls. The rate of accumulation of dye at a place on the root is translated to a flux of water into the root at that place, using the concentration of dye in the mist. Water fluxes were measured into first-order branches and axes over the root system and expressed both as fluxes per unit length and per unit surface of root. Values are consistent with those found by potometric methods for limited samples of young plants. The variance of the measurements is quite large, possibly reflecting real heterogeneities in water uptake throughout the root system. The maximum water uptake achieved by a few branches was 40 μl h−1 cm−2 root. On average, flux into axes and branches was the same throughout the root system, at about 5 μl h−1 cm−2. The region of the axis at which the late metaxylem vessels mature and become conducting coincides with the region where the branches become active in water uptake (20–30 cm from the tip). Proximal to this, the branches collect about eight times as much water as the axis, having about eight times the surface area. The zone of maximum water collection by branches and axis is 30–60 cm from the tip (6–8 μl h−1 cm−1 axis). In the older, more proximal regions, water collection drops to about a quarter of this.

Habitat fragmentation and pairing success in the ovenbird (seiurus aurocapillus)

Abstract: ABSTRACr.-In 1990 and 1991, we determined the proportion of Ovenbird (Seiurus aurocapillus) territorial males that were paired in a 25-ha plot in an extensive forest (>350 kM2) in Quebec, and compared it to pairing success in populations breeding in nearby forest fragments (4.5-53.0 ha) in Quebec and Ontario. We tested the hypotheses that pairing success would increase with population density, and decrease with the degree of fragmentation of the habitat. Pairing success was higher in the extensive forest in both years, although the difference was only marginally significant (P 0.25) in 1991 (76.5 vs. 58.3%). The density of territorial males was twice as high in the extensive forest as in the forest fragments. When including data from similar studies conducted in New Jersey and Missouri, we found that pairing success increased and gradually levelled off with the density of territorial males. Although we lacked a common parameter for measuring habitat fragmentation across all three studies, pairing success appeared to decrease with the isolation of forest fragments from surrounding woodland, while it remained stable around 80% in extensive forests of all three studies. The effect of habitat fragmentation on pairing success was particularly severe in the Missouri study area, at the periphery of Ovenbird's breeding range. A general linear model showed that woodland configurationthe location of a study site in an extensive or fragmented forest-was the best predictor of pairing success, and that geographical location also had a significant effect. We conclude that habitat fragmentation reduces pairing success by altering dispersal dynamics or habitat selection by females. Received 6 April 1992, accepted 17 November 1992. THE OVENBIRD (Seiurus aurocapillus) has been

Antioxidant defenses in the tolerance of freezing and anoxia by garter snakes.

Abstract: The garter snake Thamnophis sirtalis parietalis can readily tolerate several hours of freezing or anoxia exposure Both stresses halt oxygen availability to tissues and to endure these stresses snakes must cope with potential oxidative stress arising as a result of the ischemic/anoxic condition followed by reperfusion of aerated blood during recovery To determine whether antioxidant defenses are important for freezing and anoxia survival, we monitored the activities of antioxidant enzymes and the levels of glutathione (GSH and GSSG) during freezing (5 h at -25 degrees C) and anoxia (10 h under N2 gas at 5 degrees C) exposures in three organs (muscle, liver, and lung) of snakes Freezing resulted in a significant rise in the activity of muscle and lung catalase (by 183 and 63%) and in muscle glutathione peroxidase (52%) Anoxia enhanced muscle and liver superoxide dismutase activities (by 59 and 118%) and also caused a 57% increase in muscle GSH levels The increase in muscle GSH concentration in anoxia (from 045 to 071 mM) could also stimulate muscle glutathione peroxidase activity in vivo by 15-fold because of its low affinity for GSH (Km = 11 mM) The ratio of GSSG/GSH was not affected by experimental state in any tissue, suggesting that oxidative stress did not occur during the freezing or anoxic exposure Rather, H2O2- and O2(-)-detoxification systems may be activated in preparation for possible oxygen free radical overgeneration during thawing or reoxygenation Antioxidant defenses appear to be part of the adaptive machinery for reptilian tolerance of freezing and anoxia

Extending cryptographic logics of belief to key agreement protocols

Abstract: The authentication logic of Burrows, Abadi and Needham (BAN) provided an important step towards rigourous analysis of authentication protocols, and has motivated several subsequent refinements. We propose extensions to BAN-like logics which facilitate, for the first time, examination of public-key based authenticated key establishment protocols in which both parties contribute to the derived key (i.e. key agreement protocols). Attention is focussed on six distinct generic goals for authenticated key establishment protocols. The extended logic is used to analyze three Diffie-Hellman based key agreement protocols, facilitating direct comparison of these protocols with respect to formal goals reached and formal assumptions required.

Heroin self-administration in rats under a progressive ratio schedule of reinforcement.

Abstract: Heroin self-administration behavior under a progressive ratio (PR) schedule of reinforcement was evaluated in rats. The schedule was designed to restrict drug intake, minimize opiate dependency, and quantify the number of responses emitted (final response ratio) in order to receive a limited number of heroin infusions. Final ratios were found to be stable and did not increase with chronic (31 days) PR reinforcement. The ability of the PR schedule to detect changes in heroin reinforcement was demonstrated by evaluating the effect of naltrexone pretreatment and unit dose alteration on final ratios. Naltrexone (0.4 mg/kg) reduced final ratios and an inverted U dose-response relationship was established for the unit heroin doses 12.5–100 µg/injection. Maximal final ratios occurred with 50 µg/injection heroin reinforcement. This PR schedule may provide a useful method for evaluating the effects of pharmacological manipulations or lesions on opiate reinforcement.

Evidence for a Younger Dryas-like cooling event on the British Columbia coast

Abstract: Two independent paleoclimatic records from the Pacific coast of Canada indicate that a late-glacial warming trend was interrupted by a return to colder conditions between about 11,000 and 10,200 radiocarbon yr B.P., correlative with the classical Younger Dryas chronozone of the North Atlantic region. Fossil benthic foramnifera from three cores from the continental shelf dated by accelerator mass spectrometry show peak abundances of the cold-water indicator species Cassidulina reniforme at this time. Fossil-pollen spectra from two sites on the Queen Charlotte Islands record a shift from forest to open, herb-rich vegetation after 11,100 yr B.P., probably in response to colder and wetter conditions identified by pollen-climate transfer functions. These preliminary data for a cold oscillation between ca. 11000 and 10000 yr ago in the northeast Pacific argue that this deglacial phenomenon was not restricted to the North Atlantic, but was a hemispheric—and possibly global—event.