Showing papers by "University of New Brunswick published in 2003"

A robust, real-time control scheme for multifunction myoelectric control

Abstract: This paper represents an ongoing investigation of dexterous and natural control of upper extremity prostheses using the myoelectric signal (MES). The scheme described within uses pattern recognition to process four channels of MES, with the task of discriminating multiple classes of limb movement. The method does not require segmentation of the MES data, allowing a continuous stream of class decisions to be delivered to a prosthetic device. It is shown in this paper that, by exploiting the processing power inherent in current computing systems, substantial gains in classifier accuracy and response time are possible. Other important characteristics for prosthetic control systems are met as well. Due to the fact that the classifier learns the muscle activation patterns for each desired class for each individual, a natural control actuation results. The continuous decision stream allows complex sequences of manipulation involving multiple joints to be performed without interruption. Finally, minimal storage capacity is required, which is an important factor in embedded control systems.

Is the Canadian childhood obesity epidemic related to physical inactivity

Abstract: OBJECTIVE: This study examined the relation among children's physical activity, sedentary behaviours, and body mass index (BMI), while controlling for sex, family structure, and socioeconomic status. DESIGN: Epidemiological study examining the relations among physical activity participation, sedentary behaviour (video game use and television (TV)/video watching), and BMI on a nationally representative sample of Canadian children. SUBJECTS: A representative sample of Canadian children aged 7–11 (N=7216) from the 1994 National Longitudinal Survey of Children and Youth was used in the analysis. MEASUREMENTS: Physical activity and sport participation, sedentary behaviour (video game use and TV/video watching), and BMI measured by parental report. RESULTS: Both organized and unorganized sport and physical activity are negatively associated with being overweight (10–24% reduced risk) or obese (23–43% reduced risk), while TV watching and video game use are risk factors for being overweight (17–44% increased risk) or obese (10–61% increased risk). Physical activity and sedentary behaviour partially account for the association of high socioeconomic status and two-parent family structure with the likelihood of being overweight or obese. CONCLUSION: This study provides evidence supporting the link between physical inactivity and obesity of Canadian children.

A reassessment of carbon content in wood: variation within and between 41 North American species

Abstract: At present, 50% (w/w) carbon is widely promulgated as a generic value for wood; however, the literature yields few data and indicates that very little research has actually been done. C contents in heartwood of forty-one softwood and hardwood species were determined. C in kiln-dried hardwood species ranged from 46.27% to 49.97% (w/w), in conifers from 47.21% to 55.2%. The higher C in conifers agrees with their higher lignin content (∼30%, versus ∼20% for hardwoods). Wood-meal samples drilled from discrete early wood and late wood zones of seven of the forty-one species were also investigated. C contents of early woods were invariably higher than those in corresponding late woods, again in agreement with early wood having higher lignin content. Further investigation was made into freshly harvested wood of some species to determine how much volatile C is present, comparing oven-dried wood meal with wood meal dried at ambient temperature over a desiccant. C contents of oven-dried woods were significantly lower, indicating that all past data on C content in oven- or kiln-dried woods may be inaccurate in relation to the true C content of forests. We conclude that C content varies substantially among species as well as within individual trees. Clearly, a 50% generic value is an oversimplification of limited application in relation to global warming and the concept of “carbon credits”.

A transformation based algorithm for reversible logic synthesis

Abstract: A digital combinational logic circuit is reversible if it maps each input pattern to a unique output pattern. Such circuits are of interest in quantum computing, optical computing, nanotechnology and low-power CMOS design. Synthesis approaches are not well developed for reversible circuits even for small numbers of inputs and outputs.In this paper, a transformation based algorithm for the synthesis of such a reversible circuit in terms of n × n Toffoli gates is presented. Initially, a circuit is constructed by a single pass through the specification with minimal look-ahead and no back-tracking. Reduction rules are then applied by simple template matching. The method produces near-optimal results for 3-input circuits and also produces very good results for larger problems.

AUC: a statistically consistent and more discriminating measure than accuracy

Abstract: Predictive accuracy has been used as the main and often only evaluation criterion for the predictive performance of classification learning algorithms. In recent years, the area under the ROC (Receiver Operating Characteristics) curve, or simply AUC, has been proposed as an alternative single-number measure for evaluating learning algorithms. In this paper, we prove that AUC is a better measure than accuracy. More specifically, we present rigourous definitions on consistency and discriminancy in comparing two evaluation measures for learning algorithms. We then present empirical evaluations and a formal proof to establish that AUC is indeed statistically consistent and more discriminating than accuracy. Our result is quite significant since we formally prove that, for the first time, AUC is a better measure than accuracy in the evaluation of learning algorithms.

AUC: a better measure than accuracy in comparing learning algorithms

Abstract: Predictive accuracy has been widely used as the main criterion for comparing the predictive ability of classification systems (such as C4.5, neural networks, and Naive Bayes). Most of these classifiers also produce probability estimations of the classification, but they are completely ignored in the accuracy measure. This is often taken for granted because both training and testing sets only provide class labels. In this paper we establish rigourously that, even in this setting, the area under the ROC (Receiver Operating Characteristics) curve, or simply AUC, provides a better measure than accuracy. Our result is quite significant for three reasons. First, we establish, for the first time, rigourous criteria for comparing evaluation measures for learning algorithms. Second, it suggests that AUC should replace accuracy when measuring and comparing classification systems. Third, our result also prompts us to reevaluate many well-established conclusions based on accuracy in machine learning. For example, it is well accepted in the machine learning community that, in terms of predictive accuracy, Naive Bayes and decision trees are very similar. Using AUC, however, we show experimentally that Naive Bayes is significantly better than the decision-tree learning algorithms.

Cognitive-Behavioral Therapy for OCD

Abstract: Part 1: The Nature of OCD. Obsessive-Compulsive Disorder: A Diagnostic Enigma. Phenomenology of Obsessions and Compulsions. Part 2: Cognitive-Behavioural Theory and Research. Behavioural Perspectives. Neuropsychology and Information Processing in OCD. Cognitive Appraisals Theories of OCD. Thought Suppression and Obsessions. Cognitive Control: A New Model of Obsessions. Part 3: Cognitive-Behavioural Therapy. Cognitive Behavioural Assessment. Getting Started: Basic Elements and Rationale. Cognitive Restructuring and Generating Alternatives. Behavioural Interventions. Modifying Secondary Appraisals of Control. Empirical Status and Future Directions.

Will we observe black holes at the LHC

Abstract: The generalized uncertainty principle, motivated by string theory and non-commutative quantum mechanics, suggests significant modifications to the Hawking temperature and evaporation process of black holes. For extra-dimensional gravity with Planck scale O(TeV), this leads to important changes in the formation and detection of black holes at the large hadron collider. The number of particles produced in Hawking evaporation decreases substantially. The evaporation ends when the black-hole mass is Planck scale, leaving a remnant and a consequent missing energy of order TeV. Furthermore, the minimum energy for black-hole formation in collisions is increased, and could even be increased to such an extent that no black holes are formed at LHC energies.

Tension Stiffening and Cracking of Steel Fiber-Reinforced Concrete

Abstract: Fiber-reinforced concrete used in structural applications requires characteristic material properties that can be easily incorporated into existing design procedures. This paper investigates the postcracking response of reinforced concrete tension members made with both plain and steel fiber-reinforced concrete (SFRC). Loading was either monotonic or cyclic, and shrinkage effects are included in analysis of the member response. Tension-stiffening results are used to determine the average tensile response of concrete after cracking, and an expression is developed to predict this smeared behavior as a material property for cracked SFRC, as well as to estimate crack spacings. Specimens with steel fibers exhibited increased tension stiffening and smaller crack spacings, which both contributed to a reduction in crack widths. The postcracking tensile strength of fiber concrete at the cracks is the determining factor affecting behavior and is a fundamental material property used to predict tension stiffening and crack behavior for conventionally reinforced SFRC. The uniaxial strength of SFRC immediately after cracking governs serviceability behavior, while the postcracking strength at larger deformations governs strength design and is responsible for tension stiffening after yielding of the reinforcement. Cyclic loading did not have a significant effect on either tension stiffening or crack width control for the specimens tested.

The multifarious world of transition metal hydrides

Abstract: Transition metal (TM) hydrides display a remarkable range of bonding types, encompassing classical M–H moieties, dihydrogen complexes containing the η2-H2 ligand, and trihydrides which display quantum mechanical site exchange. Furthermore, C–H, Si–H and B–H moieties can bind to TM centres in an η2-manner, to give σ-bond complexes with a spectrum of M⋯H contributions. In addition to these primary bonding modes, TM complexes also indulge in a wide spectrum of hydrogen-bonding interactions, including both M⋯H–X and the unique type M–H⋯H–X. This review begins with a historical perspective of the development of TM hydride chemistry, and proceeds to focus on three significant developments of the past two decades: the discovery of σ-bond and dihydrogen complexes, the involvement of TM hydrides in hydrogen bonding, and the role played by quantum mechanical phenomena in the chemistry and dynamics of TM hydrides. The account concludes with an overview of the interrelationship between these apparently disparate novel aspects of TM hydride chemistry.

Dimensions in elderly travel behaviour: A simplified activity-based model using lifestyle clusters

Abstract: The current lack of a detailed description of elderly travel characteristics and behaviours, particularly one that examines the issue at a level involving activity engagement, was a deficiency addressed by this research. Using data from the 1994/95 Portland, Oregon, Household Activity and Stated Preference Survey a simplified activity-based travel model for the elderly was developed and validated. The modelling framework makes use of lifestyle groups which are delineated through advance analyses. The final cluster solution chosen to provide a categorical basis for the modelling framework identified six distinct lifestyle groups based on socio-demographic variables. The clusters were subjectively labelled Workers, Mobile Widows, Granny Flats, Mobility Impaired, Affluent Males, and Disabled Drivers. The clusters were found to have statistically significant differences in travel behaviour and activity engagement patterns. These findings are useful to policy-makers who attempt to balance the mobility needs of the elderly with the prospect for stricter driving license policies in response to traffic safety concerns. The model framework successfully replicated all facets of the base data set used for its development. Using a sequential process, the micro-simulation model employs a bottom-up approach by stochastically developing daily activity itineraries for individuals which are subsequently assembled into trip tours. Elements of travel behaviour synthesized for individuals being modelled included total daily activities (with and without travel), activities engaged in by class (with and without travel), total daily trip tours, and mode splits.The research has shown that a categorical approach using lifestyle groups with unique activity and travel characteristics can be successfully combined within an activity-based framework. Although this approach was applied specifically to the elderly, it can be extended to other heterogeneous groups including the population as a whole. Furthermore, the study has provided a more comprehensive understanding of the varied lifestyles, activity patterns, and subsequent travel behaviour and needs of the elderly.

On the efficiency of national innovation systems

Abstract: This paper presents a non-parametric approach to the disentanglement of the related effects of efficiency and productivity of a country's technological effort. The ultimate purpose is to identify the extent to which the alleged decrease in the productivity growth of many countries can be explained by differences in efficiency and by differences in its components, namely scale and congestion. The role of moderators in explaining productivity fluctuations if also assessed. The database consists of the countries included in the World Competitiveness Report.

Reversible logic synthesis

Abstract: Reversible logic is an emerging research area. Interest in reversible logic is sparked by its necessity in quantum technologies. Reversible implementations are also found in optical technology, nanotechnology, thermodynamics and adiabatic CMOS. Power dissipation in modern technologies is an important issue, and overheating is a serious concern for both manufacturer (impossibility of introducing new, smaller scale technologies, limited temperature range for operating the product) and customer (power supply, which is especially important for mobile systems). One of the main benefits that reversible logic brings is theoretically zero power dissipation in the sense that, independently of underlying technology, irreversibility means heat generation. Most of the listed technologies are either emerging or not fully investigated. As a result, only a small number of Boolean functions can be computed using hardware based on reversible technology. Part of this problem comes from the incompleteness of the technological results, the other part arises from absence of good circuit synthesis procedures. Synthesis of multiple-output functions has to be done in terms of reversible objects. This usually results in addition of garbage bits (bits needed for reversibility, but not required for the output part of a circuit), which in contrast to the non-reversible case is technologically difficult and expensive. The situation is rather pessimistic when it is observed that proposed synthesis procedures use excessive garbage. The amount of garbage is a very important criterion for a good synthesis procedure, since in most technologies the addition of only one bit of garbage is expensive or even impossible to implement. Based on this information, a crucial way to help reversible logic to evolve and become usable is to design a synthesis method which uses the theoretically minimal number of garbage bits. This will help the emerging technologies to use the results of reversible synthesis even in the early stage of their development. Minimal garbage realization may require a larger number of gates in the circuit, but it is better to have a large but working circuit than a small one that is not ready for the technology. In this thesis several synthesis methods that use minimal garbage are considered: RCMG model (defined as a part of this thesis), Toffoli synthesis, Fredkin/Toffoli synthesis. Dynamic programming algorithms are synthesized separately with near minimal garbage. Some of the methods use minimal garbage and produce small circuits (Toffoli and Fred-kin/Toffoli synthesis) but work with reversible specifications, some handle “don't cares” (RCMG), some even allow a trade-off between the garbage amount and the number of gates in the resulting circuit. When a technology is chosen and the relationship between costs of one bit of garbage and a single gate is specified, one or the other method may be better. In the presented thesis the main goal is to design synthesis methods that will be suitable for different cost distributions.

Seasonality in tourism employment: human resource challenges

Abstract: Seasonality in tourism has a profound impact on the management of human resources in organizations operating in a seasonal context. Tourism employment in Canada is profiled and its seasonality examined in Atlantic Canada, where seasonal tourism employment is common. A model for managing seasonality in employment is proposed as a continuum, ranging from “embracing” to “challenging” seasonality. For each approach, differing human resource management practices are identified and operational impacts are discussed, providing possible strategies for employers operating in seasonal tourism contexts. Ongoing research is planned in Atlantic Canada’s accommodations sector, testing the model for managing seasonal tourism employment.

System and method for image fusion

Abstract: A method of fusing a low resolution multispectral image with a high resolution panchromatic image comprising the step of generating a new synthetic pan image using multispectral bands from the multispectral image.

Nonmigrating diurnal tides in the thermosphere

Abstract: [1] Horizontal wind measurements from the HRDI and WINDII instruments on the Upper Atmosphere Research Satellite are analyzed to reveal the most prominent nonmigrating diurnal tidal components at 95 km: the eastward propagating diurnal tide with zonal wave number s = 3 (DE3), the standing (s = 0) diurnal oscillation (D0), and the westward propagating diurnal tide with s = 2 (DW2). The strongest DE3 occurs primarily during Northern Hemisphere summer/fall with maximum eastward winds near the equator of order 15 ms−1 and is a vertical extension of the s = 3 Kelvin wave. The first antisymmetric mode of DE3 dominates during October–April, with maximum meridional winds near the equator of order 8 ms−1. D0 exists during nearly all months and is nonsymmetric about the equator with maximum northward wind amplitudes in the Southern Hemisphere of order 7–10 ms−1. DW2 closely resembles the first symmetric propagating mode from classical tidal theory, with maximum northward wind amplitudes of order 10–12 ms−1 during September through February. The combination of DE3, D0, and DW2 with DW1 gives rise to significant longitude variations in the diurnal tide between ±40° latitude. Forcing in the Global Scale Wave Model (GSWM) is calibrated according to the above observations, thus enabling global estimates of nonmigrating tidal temperatures and other fields. For instance, it is estimated that the temperature and eastward wind perturbations associated with DE3 may be as large as 20K and 35 ms−1 at 145 km and 115 km, respectively, over the equatorial region during July.

Seabirds as Indicators of Changes in Marine Ecosystems: Ecological Monitoring on Machias Seal Island

Abstract: Changes in marine ecosystems can be manifested in many different ways, on different temporal and spatial scales. Seabirds are top consumers in marine foodwebs and offer opportunities to detect and assess the biological effects of changes in physical parameters (sea-surface temperature [SST], salinity, depth of thermocline etc.) of the marine ecosystem. We compare six-eight years' of data on the biology (diet, and breeding success) of four species of seabird (arctic tern Sterna paradisaea and common tern S. hirundo, which feed at the sea surface; and Atlantic puffin Fratercula antica and razorbill Alca torda, which dive 30-60 m for their prey) breeding on Machias Seal Island (MSI) in the Bay of Fundy with both our own meteorological and oceanographic measurements, and with standard measurements from conventional sources. These are compared with fisheries data on changes in the main prey of all the seabirds concerned (juvenile or '0-group' herring Clupea harengus) which are the most direct link between the seabirds and the physical properties of the marine system. We explore relationships between seabird productivity and diet, and other aspects of both herring biology (larval surveys, and fat content) and oceanography (SST data from the island, and remotely sensed data from the entrance to the Bay of Fundy). Timing of laying by puffins followed SST variation at neither the local (MSI) nor regional scales, but at the scale of the North Atlantic, following the trend of populations breeding off northern Norway. The proportion of herring in the diet of terns over 6 years varied inversely with herring larval abundance the previous fall; this relationship was not statistically significant in the puffin and razorbill. A major new finding is the considerable (approximately 50%) inter-annual variation in the energy density (fat content) of juvenile herring that are the main seabird prey; breeding success of both species of tern varied in parallel with the energy density of juvenile herring in the diet until the last two years of the study, when sandlance (Ammodytes sp.) and euphausid shrimp predominated in the diet. Our long-term research approach combines traditional population monitoring (of numbers of breeding birds) with demographic, behavioural and environmental monitoring, to provide new understanding of the marine ecosystem as well as of seabirds.

What is sex? students' definitions of having sex, sexual partner, and unfaithful sexual behaviour

Abstract: In this study 164 heterosexual Canadian university students were asked about their definitions of the terms having sex, sexual partner, and unfaithful. Students were asked to indicate which from a list of 18 sexual behaviours they would include in their definition of each of the three terms. Significantly more behaviours were included in students' unfaithful definition than were included in the sexual partner definition and significantly more behaviours were included in the sexual partner definition than in the having sex definition. For example, while less than 25% of participants considered oral genital behaviour to be having sex, more than 60% thought that the giver or receiver of oral sex was a sexual partner, and more than 97% considered a partner who had oral sex with someone else to be have been unfaithful. Similarly, while masturbating to orgasm in the presence of another was considered to be having sex by less than 4% of participants, 34% reported that this behaviour was sufficient to consider that person a sexual partner and 95% considered it to be unfaithful. Students were more likely to include a behaviour in their definitions if orgasm occurred than if orgasm did not occur. There were no significant gender differences. Multiple regression analyses revealed that older and less sexually experienced students reported a broader definition of sexual partner than did younger and more sexually experienced students. The implications of these findings for sex research and sexual health promotion are discussed.

Improved quantum cost for n-bit Toffoli gates

Abstract: An n-bit Toffoli gate quantum circuit based on the realisation proposed by Barenco et al., where some of the Toffoli gates in their construction are replaced with Peres gates, is presented. This results in a significant cost reduction. The main contribution of this presentation is a quantum circuit which simulates the (m+1)-bit Toffoli gate with 32m−120 elementary quantum gates and one garbage bit which is passed unchanged.

Valence Charge Concentrations, Electron Delocalization and β‐Agostic Bonding in d0 Metal Alkyl Complexes

Abstract: In this paper we describe a range of model d(0) metal ethyl compounds and related complexes, studied by DFT calculations and high resolution X-ray diffraction. The concept of ligand-opposed charge concentrations (LOCCs) for d(0) metal complexes is extended to include both cis-and trans-ligand-induced charge concentrations (LICCs) at the metal, which arise as a natural consequence of covalent metal-ligand bond formation in transition metal alkyl complexes. The interplay between locally induced sites of increased Lewis acidity and an ethyl ligand is crucial to the development of a beta-agostic interaction in d(0) metal alkyl complexes, which is driven by delocalization of the M-C bonding electrons. Topological analysis of theoretical and experimental charge densities reveals LICCs at the metal atom, and indicates delocalization of the M-C valence electrons over the alkyl fragment, with depletion of the metal-directed charge concentration (CC) at the alpha-carbon atom, and a characteristic ellipticity profile for the C(alpha)-C(beta) bond. These ellipticity profiles and the magnitude of the CC values at C(alpha) and C(beta) provide experimentally observable criteria for assessing quantitatively the extent of delocalization, with excellent agreement between experiment and theory. Finally, a concept is proposed which promises systematic control of the extent of C-H activation in agostic complexes.