Showing papers by "University of New Brunswick published in 2001"

A wavelet-based continuous classification scheme for multifunction myoelectric control

Abstract: This work represents an ongoing investigation of dexterous and natural control of powered upper limbs using the myoelectric signal. When approached as a pattern recognition problem, the success of a myoelectric control scheme depends largely on the classification accuracy. A novel approach is described that demonstrates greater accuracy than in previous work. Fundamental to the success of this method is the use of a wavelet-based feature set, reduced in dimension by principal components analysis. Further, it is shown that four channels of myoelectric data greatly improve the classification accuracy, as compared to one or two channels. It is demonstrated that exceptionally accurate performance is possible using the steady-state myoelectric signal. Exploiting these successes, a robust online classifier is constructed, which produces class decisions on a continuous stream of data. Although in its preliminary stages of development, this scheme promises a more natural and efficient means of myoelectric control than one based on discrete, transient bursts of activity.

Exponentiated exponential family: an alternative to gamma and weibull distributions

Abstract: Summary In this article we study some properties of a new family of distributions, namely Exponentiated Exponentialdistribution, discussed in Gupta, Gupta, and Gupta (1998). The Exponentiated Exponential family has two parameters (scale and shape) similar to a Weibull or a gamma family. It is observed that many properties of this new family are quite similar to those of a Weibull or a gamma family, therefore this distribution can be used as a possible alternative to a Weibull or a gamma distribution. We present two reall ife data sets, where it is observed that in one data set exponentiated exponential distribution has a better fit compared to Weibull or gamma distribution and in the other data set Weibull has a better fit than exponentiated exponential or gamma distribution. Some numerical experiments are performed to see how the maximum likelihood estimators and their asymptotic results work for finite sample sizes.

Integrating seaweeds into marine aquaculture systems: a key toward sustainability

Abstract: The rapid development of intensive fed aquaculture (e.g. finfish and shrimp) throughout the world is associated with concerns about the environmental impacts of such often monospecific practices, especially where activities are highly geographically concentrated or located in suboptimal sites whose assimilative capacity is poorly understood and, consequently, prone to being exceeded. One of the main environmental issues is the direct discharge of significant nutrient loads into coastal waters from open-water systems and with the effluents from land-based systems. In its search for best management practices, the aquaculture industry should develop innovative and responsible practices that optimize its efficiency and create diversification, while ensuring the remediation of the consequences of its activities to maintain the health of coastal waters. To avoid pronounced shifts in coastal processes, conversion, not dilution, is a common-sense solution, used for centuries in Asian countries. By integrating fed aquaculture (finfish, shrimp) with inorganic and organic extractive aquaculture (seaweed and shellfish), the wastes of one resource user become a resource (fertilizer or food) for the others. Such a balanced ecosystem approach provides nutrient bioremediation capability, mutual benefits to the cocultured organisms, economic diversification by producing other value-added marine crops, and increased profitability per cultivation unit for the aquaculture industry. Moreover, as guidelines and regulations on aquaculture effluents are forthcoming in several countries, using appropriately selected seaweeds as renewable biological nutrient scrubbers represents a cost-effective means for reaching compliance by reducing the internalization of the total environmental costs. By adopting integrated polytrophic practices, the aquaculture industry should find increasing environmental, economic, and social acceptability and become a full and sustainable partner within the development of integrated coastal management frameworks.

Class Size and Student Achievement

Abstract: Schooling has multiple purposes. In the long run, higher levels of schooling are associated with higher earnings and economic mobility, better health, lower mortality rates, and greater democratic participation. For these reasons, most societies require children to attend school for a specified number of years or until they reach a certain age. Many of the benefits of schooling occur in part because students learn some new knowledge or skills that enhance their ability to communicate, solve problems, and make decisions. Much of the debate over schooling is essentially about how to maximize the amount of student learning, typically as measured by various assessment instruments such as standardized achievement tests. From a societal viewpoint, since resources—most notably, time—are required for learning, and are scarce, the amount of learning needs to be maximized at least cost. Learning is complex, involving cognitive processes that are not completely understood. Typically, school systems have established a primary mode of learning that involves groups of students of about the same age interacting with a single individual leading activities in a confined physical space, directed toward learning a particular topic—in other words, students are placed in classes. The number of other students in the class can vary. At the extreme, there can be one or more adults facilitating learning—teachers—with one or two students. At the other, a student may be one of a few hundred being taught by a single instructor (or, with new Internet technology, one of millions). The number of students in a class has the potential to affect how much is learned in a number of different ways. For example, it could affect how students interact with each other—the level of social engagement. This may result, for example, in more or less noise and disruptive behavior, which in turn affect the kinds of activities the teacher is able to promote. It could affect how much time the teacher is able to focus on individual students and their specific needs rather than on the group as a whole. Since it is easier to focus on one individual in a smaller group, the smaller the class size, the more likely individual attention can be given, in theory at least. The class size could also affect the teacher’s allocation of time and, hence, effectiveness, in other ways, too—for example, how much material can be covered. Teachers may choose different methods of teaching and assessment when they have smaller classes. For example, they may assign more writing, or provide more feedback on students’ written work, or use open-ended assessments, or encourage more discussions, all activities that may be more feasible with a smaller number of students. Exposure to a particular learning environment may affect learning over the time period of exposure, or it may have longer term or delayed effects (e.g., by increasing self-esteem or cognitive developments that have lasting effects). For these reasons, changes to the class size are considered a potential means of changing how much students learn. Not only is class size potentially one of the key variables in the “production” of learning or knowledge, it is one of the simplest variables for policymakers to manipulate. However, the amount of student learning is dependent on many different factors. Some are related to the classroom and school environment in which the class takes place, but others are related to the student’s own background and motivation and broader community influences. When we ask whether class size matters for achievement, it is essential to ask also, how class size matters. This is important for three reasons. First, if we can observe not only achievement differences, but also the mechanisms through which the differences are produced, this will increase our confidence that the differences are real, and not an artifact of some unmeasured or inadequately controlled condition. Second, the effects of class size may vary in different circumstances, and identifying how class size affects achievement will help us to understand why the effects of class size are variable. Third, the potential benefits of class-size reduction may be greater than what we observe. For example, suppose class-size reductions aid achievement, but only when teachers modify instructional practices to take advantage of the smaller classes. If a few teachers make such modifications, but most do not, then understanding how class size affects achievement in some cases will help reveal its potential effects, even if the potential is generally unrealized.

Generalized exponential distribution: different method of estimations

Abstract: Recently a new distribution, named as generalized exponential distribution has been introduced and studied quite extensively by the authors. Generalized exponential distribution can be used as an alternative to gamma or Weibull distribution in many situations. In a companion paper, the authors considered the maximum likelihood estimation of the different parameters of a generalized exponential distribution and discussed some of the testing of hypothesis problems. In this paper we mainly consider five other estimation procedures and compare their performances through numerical simulations.

Comparison of Measurements of Atmospheric Wet Delay by Radiosonde, Water Vapor Radiometer, GPS, and VLBI

Abstract: The accuracy of the Global Positioning System (GPS) as an instrument for measuring the integrated water vapor content of the atmosphere has been evaluated by comparison with concurrent observations made over a 14-day period by radiosonde, microwave water vapor radiometer (WVR), and Very Long Baseline Interferometry (VLBI) The Vaisala RS-80 A-HUMICAP radiosondes required a correction to the relative humidity readings (provided by Vaisala) to account for packaging contamination; the WVR data required a correction in order to be consistent with the wet refractivity formulation of the VLBI, GPS, and radiosondes The best agreement of zenith wet delay (ZWD) among the collocated WVR, radiosondes, VLBI, and GPS was for minimum elevations of the GPS measurements below 10° After corrections were applied to the WVR and radiosonde measurements, WVR, GPS, and VLBI (with 5° minimum elevation angle cutoff) agreed within ∼6 mm of ZWD [1 mm of precipitable water vapor (PWV)] when the differences were averaged,

From Nothing Works to What Works: Changing Professional Ideology in the 21st Century:

Abstract: The authors explore changes over time in criminologists' “professional ideology”—a core set of underlying beliefs that focuses academic thinking along certain lines but not others. Until the late 1960s, criminologists believed that the scientific study of the causes of crime would form the basis of individualized treatments that would reduce offender recidivism. By the mid-1970s, this view had collapsed and had been replaced by a professional ideology emphasizing that “nothing works” in corrections, that the causes of criminality are structural, and that crime can only be reduced through social justice. Although not without its merits, the authors suggest that this professional ideology has had the unfortunate consequence of legitimating “knowledge destruction” (showing what does not work) as the core intellectual project of criminology and thus of undermining efforts at “knowledge construction” (showing what does work). A “what works” movement within corrections, however, is advancing an alternative prof...

Tensile and compressive strain measurement in the lab and field with the distributed Brillouin scattering sensor

Abstract: The structural strain measurement of tension and compression in the steel beam was demonstrated with a distributed fiber-optic sensor system based on Brillouin scattering. The experiments were conducted both in the laboratory and outdoors. When it is in the outdoor environment, the temperature compensation has been taken into account for the strain measurement due to sunlight radiation. The compressive strain has been measured, without needing pretension on the fiber with a Brillouin scattering-based distributed sensor system, when the fiber is glued to the steel beam at every point. The dynamic range in the strain measurement has been increased, due to the elimination of the pretension requirement. The spatial resolution of the strain measurement is 0.5 m. The strain measurement accuracy is /spl plusmn/10 /spl mu//spl epsi/(/spl mu/m/m) in the laboratory environment with nonuniform-distributed strain. With uniform strain distribution, the strain accuracy for this system can be. /spl sim//spl plusmn/5 /spl mu//spl epsi/. These results were achieved with the introductions of a computer-controlled polarization controller, a fast digitizer-signal averager, a pulse duration control, and the electrical optical modulator bias setting in the software.

Organic Composition of C/1999 S4 (LINEAR): A Comet Formed Near Jupiter?

Abstract: In the current paradigm, Oort cloud comets formed in the giant planets' region of the solar nebula, where temperatures and other conditions varied greatly. The measured compositions of four such comets (Halley, Hyakutake, Hale-Bopp, and Lee) are consistent with formation from interstellar ices in the cold nebular region beyond Uranus. The composition of comet C/1999 S4 (LINEAR) differs greatly, which suggests that its ices condensed from processed nebular gas, probably in the Jupiter-Saturn region. Its unusual organic composition may require reevaluation of the prebiotic organic material delivered to the young Earth by comets.

Impact-induced hydrothermal activity within the Haughton impact structure, arctic Canada: Generation of a transient, warm, wet oasis

Abstract: Field studies and analytical scanning electron microscopy indicate that a hydrothermal system was created by the interaction of water with hot, impact-generated rocks following formation of the 24 km diameter, 23 Ma Haughton impact structure. Hydrothermal alteration is recognized in two settings: within polymict impact breccias overlying the central portion of the structure, and within localized pipes in impact-generated concentric fault systems. The intra-breccia alteration comprises three varieties of cavity and fracture filling: (a) sulfide with carbonate, (b) sulfate, and (c) carbonate. These are accompanied by subordinate celestite, barite, fluorite, quartz and marcasite. Selenite is also developed, particularly in the lower levels of the impact breccia sheet. The fault- related hydrothermal alteration occurs in 1-7 m diameter subvertical pipes that are exposed for lengths of up 20 m. The pipes are defined by a monomict quartz-carbonate breccia showing pronounced Fe-hydroxide alteration. Associated sulfides include marcasite, pyrite and chalcopyrite. We propose three distinct stages in the evolution of the hydrothermal system: (1) Early Stage (>200 °C), with the precipitation of quartz (vapor phase dominated); (2) Main Stage (200-100 °C), with the development of a two-phase (vapor plus liquid) zone, leading to calcite, celestite, barite, marcasite and fluorite precipitation; and (3) Late Stage (<100 °C), with selenite and fibroferrite development through liquid phase-dominated precipitation. We estimate that it took several tens of thousands of years to cool below 50 °C following impact. During this time, Haughton supported a 14 km diameter crater lake and subsurface water system, providing a warmer, wetter niche relative to the surrounding terrain. The results reveal how understanding the internal structure of impact craters is necessary in order to determine their plumbing and cooling systems.

Intrinsic Regulation of Cambial Growth

Abstract: Secondary growth in trees is an attractive system for explaining, through concerted research into mRNA, proteomics, and cell biology, how eukaryotic cellular differentiation is regulated. Differentiation pursuits by genetically uniform cambial derivatives are diverse, less than perfectly repetitive in time and space, and readily modified experimentally. Within each zone of both xylo- and phloiogenesis, competence for at least pluripotent, and not uncommonly totipotent, development evidently is retained. Thus, hypothetical concepts of cellular differentiation ‘programs’ and ‘determined histogenesis’ lack support beyond formation and continuing perpetuation of cambium as template for production of similarly shaped and sized daughter cells. The several distinct developmental zones of wood formation manifest metabolic plateaus, and their transitional regions indicate where equilibrium becomes overbalanced and cascades to the next step, changing cells biochemically, hence anatomically, into differentiated states. It remains unclear if differential gene expression during wood formation is strictly of a quantitative nature or if it also varies qualitatively. In addition to selective transcription, another plausible regulatory mechanism is quantitatively varying but still totipotent expression of so-called ‘housekeeping’ genes modulated through spatial information and changing environments, for example, at levels of mRNA supply and stability. The environment of fusiform and ray cells of the cambial region comprises, in addition to dynamic maintenance metabolism, fluxes in phytohormones, carbohydrates, water, O 2 , root nutriment, and physical factors capable of influencing both gene expression and enzyme kinetics. In addition to phloem and xylem transport, intercellular communication is normal to cambium and its differentiating derivatives; thus, the procambium-cambium continuum appears to be a living ‘fibre’ communication network plausibly serving to integrate growth and development throughout the whole plant.

Use of sterile triploid Atlantic salmon ( Salmo salar L.) for aquaculture in New Brunswick, Canada

Abstract: Induced triploidy is the only effective method currently available for mass production of reproductively sterile salmonids for aquaculture. Repeated studies at the Atlantic Salmon Federation's hatchery (St Andrews, New Brunswick, Canada) have shown only minor differences between triploids and diploids in survival to S1 smolt age (15 months), percentage of the population which became S1 smolts, and mean S1 smolt size. However, a similar study at a commercial hatchery was terminated because of exceptionally high mortality of triploids prior to the start of feeding. Marine growout trials in sea cages showed that triploids grew well in seawater, but had reduced survival rates (leading to a 5-15% reduction in yield at harvest) and high rates of jaw abnormalities. Similar results have been reported elsewhere. Although induced triploidy can be used effectively as a management tool to ensure lack of reproduction, there is at present little support of the aquaculture industry to switch to their large-scale use. In light of fundamental biological differences, it is perhaps naive to expect triploids to perform as well as diploids using standard culture methods. Triploids should be treated as a new “species” for aquaculture development, beginning with research to determine their optimum rearing requirements.

Multilevel Modelling of Hierarchical Data in Developmental Studies

Abstract: This report attempts to give nontechnical readers some insight into how a multilevel modelling framework can be used in longitudinal studies to assess contextual influences on child development when study samples arise from naturally formed groupings. We hope to achieve this objective by: (1) discussing the types of variables and research designs used for collecting developmental data; (2) presenting the methods and data requirements associated with two statistical approaches to developmental data—growth curve modelling and discrete-time survival analysis; (3) describing the multilevel extensions of these approaches, which can be used when the study of development includes intact clusters or naturally formed groupings; (4) demonstrating the flexibility of these two approaches for addressing a variety of research questions; and (5) placing the multilevel framework developed in this report in the context of some important issues, alternative approaches, and recent developments. We hope that readers new to these methods are able to visualize the possibility of using them to advance their work.

Solar illumination as cause of the equinoctial preference for geomagnetic activity

Abstract: Geomagnetic and auroral activity vary seasonally with maxima at equinoxes, as has been known for more than a century. The cause remains under debate. The angle made by the Earth's dipole axis with the typical direction of the interplanetary magnetic field (IMF) can explain a portion (about 17%) of the effect. To explain the majority of the equinoctial effect, we suggest that geomagnetic activity peaks when the nightside auroral zones of both hemispheres are in darkness, as happens at equinox. Under such conditions, no conducting path exists in the ionosphere to complete the currents required by solar wind-magnetosphere-ionosphere coupling, and geomagnetic disturbances maximize. To test this theory, the Universal Time (UT) variation of geomagnetic activity was explored. As our model predicts, geomagnetic activity in December, measured by the Am index, evinces a deep minimum around 0300–0600 UT when the auroral oval of both hemispheres are in darkness and a maximum around 1500–1600 UT when the southern nightside oval is sunlit. In June, complementary effects are predicted and observed. Previous studies using the AE index have shown more ambiguous results. Here we show that if AE is resolved into the AU and AL components, the discrepancy disappears, with the AL component following the same pattern as does Am. We thus conclude that the intensity of global geomagnetic activity is well ordered by whether the nightside auroral oval is sunlit in one hemisphere or neither.

MOLECULAR SYSTEMATICS OF THE FLORIDEOPHYCEAE (RHODOPHYTA) USING NUCLEAR LARGE AND SMALL SUBUNIT rDNA SEQUENCE DATA

Abstract: Sequence data are presented for approximately 85% of the nuclear large subunit (LSU) rDNA gene for one member of the Bangiophyceae and 47 members of the Florideophyceae, the latter representing all but one of the currently recognized florideophyte orders. Distance, parsimony, and maximum likelihood analyses of these data were used to generate phylogenetic trees, and bootstrap resampling was implemented to infer robustness for distance and parsimony results. LSU phylogenies were congruent with published nuclear small subunit (SSU) rDNA results in that four higher level florideophyte lineages were resolved: lineage 1, containing the order Hildenbrandiales; lineage 2, recovered only under distance analysis, composed of the orders Acrochaetiales, Balliales, Batrachospermales, Corallinales, Nemaliales, Palmariales, and Rhodogorgonales; lineage 3, containing the Ahnfeltiales; and lineage 4, composed of the orders Bonnemaisoniales, Ceramiales, Gelidiales, Gigartinales, Gracilariales, Halymeniales, Plocamiales, and Rhodymeniales. Analyses were also performed on a combined LSU-SSU data set and an SSU-only data set to account for differences in taxon sampling relative to published studies using this latter gene. Combined LSU-SSU analyses resulted in phylogenetic trees of similar topology and support to those obtained from LSU-only analyses. Phylogenetic trees produced from SSU-only analyses differed somewhat in particulars of branching within lineages 2 and 4 but overall were congruent with the LSU-only and combined LSU-SSU results. We close with a discussion of the phylogenetic potential that the LSU has displayed thus far for resolving relationships within the Florideophyceae.

A Survey of Organic Volatile Species in Comet C/1999 H1 (Lee) Using NIRSPEC at the Keck Observatory

Abstract: The organic volatile composition of the long-period comet C/1999 H1 (Lee) was investigated using the —rst of a new generation of cross-dispersed cryogenic infrared spectrometers (NIRSPEC, at the Keck Observatory atop Mauna Kea, HI). On 1999 August 19¨21 the organics spectral region (2.9¨3.7 km) was completely sampled at both moderate and high dispersion, along with the CO fundamental region (near 4.67 km), revealing emission from water, carbon monoxide, methanol, methane, ethane, acetylene, and hydrogen cyanide. Many new multiplets from OH in the 1¨0 band were seen in prompt emission, and numerous new spectral lines were detected. Several spectral extracts are shown, and global production rates are presented for seven parent volatiles. Carbon monoxide is strongly depleted in comet Lee relative to comets Hyakutake and Hale-Bopp, demonstrating that chemical diversity occurred in the giant

The effect of light intensity and spectrum on the incidence of first feeding by larval haddock

Abstract: Under full–spectrum white light, feeding success of haddock Melanogrammus aeglefinus first feeding larvae, as measured both by proportion of larvae feeding and mean prey consumed, peaked at 1·7-18 μmol s-1 m-2. Feeding was significantly reduced at lower and higher intensities. A similar result was observed for larvae feeding under blue (470 nm) light, with significantly greater feeding success at intermediate light intensity (1·8 μmol s-1 m-2). When different light qualities were compared, larvae had significantly greater feeding success when exposed to blue (470 nm) light than either full-spectrum white or green (530 nm) light. Haddock larvae were capable of prey capture under all light treatments tested, indicating a necessary degree of adaptive flexibility in feeding response. The results are consistent with predisposition of haddock larvae to optimal feeding in a visual environment comparable with open ocean nursery grounds. Information on the impact of light on haddock first feeding can be incorporated into models of larval growth, survival, year-class strength and recruitment, and assist in developing husbandry protocols to maximize larval survival in aquaculture.

A longitudinal study of the development of low back pain in an industrial population.

Abstract: Study design This is a longitudinal study in which industrial workers without chronic low back pain (LBP) were initially assessed with a comprehensive test battery and surveyed every 6 months thereafter for 2 years. Objective To determine factors that may predispose industrial workers who lift over 5000 kg per shift to LBP. Summary of background data Prospective studies are small in number and often limited in breadth or depth of the test battery, methodologic issues, or investigator expertise. There are no prospective studies that focus on a homogeneous work sample of industrial employees. Methods Production workers (n = 149) who volunteered for the 2-year study were assessed using physical measures (e.g., muscular strength, endurance, and flexibility), lifting kinematics (a sagittal plane box lift), and health, lifestyle, and work environment data (paper questionnaires). Follow-up questionnaires were distributed every 6 months for 2 years. Results Using self-report of LBP as the main outcome measure, eight variables predicted LBP in this sample with a 75% correct prediction rate. Predictor variables included age, thoracic acceleration during the trunk velocity test, median frequency intercept of electromyography of the right L3 erector spinae, quadriceps strength, quadriceps endurance, self-assessment of fitness, having a confidante, and number of medications currently taken. Conclusion Results confirmed the multifactorial nature of low back pain and suggest that personal fitness is an important defense against low back pain, even in manual handling lifting tasks.