• Canada

Abstract In this paper, we consider a discrete logistic equation x ( n +1)= x ( n ) exp r ( n ) 1 − x ( n ) K ( n ) where {r(n)} and {K(n)} are positive ω-periodic sequences. Sufficient conditions are obtained for the existence of a positive and globally asymptotically stable ω-periodic solution. Counterexamples are given to illustrate that the conclusions in [1] are incorrect.

When defining a data type, it is often useful to specify restrictions on the permitted values of that type. Pascal's subrange type declaration, a special case of this kind of constraint definition, has already proved itself to be quite useful. Restricted data types allow more complex constraints to be defined and checked; for example, a variable could be declared of type “odd integer” or the day field of a “date” type variable could be checked for consistency with the year and month fields. A simple mechanism is proposed, allowing the formulation of such constraints and their association with data types; the behaviour of a restricted type variable is described. The effects of the use of such a mechanism on program reliability, readability and efficiency are discussed.

Abstract The purpose of this study was to investigate the alterations with obesity, and the effects of moderate aerobic exercise or prebiotic dietary-fibre supplementation on the mechanical and biochemical properties of the tail tendon in a rat model of high-fat/high-sucrose (HFS) diet-induced obesity. Thirty-two male Sprague-Dawley rats were randomized to chow (n = 8) or HFS (n = 24) diets. After 12-weeks, the HFS fed rats were further randomized into sedentary (HFS sedentary, n = 8), exercise (HFS + E, n = 8) or prebiotic fibre supplementation (HFS + F, n = 8) groups. After another 12-weeks, rats were sacrificed, and one tail tendon was isolated and tested. Stress-relaxation and stretch-to-failure tests were performed to determine mechanical properties (peak, steady-state, yield and failure stresses, Young’s modulus, and yield and failure strains) of the tendons. The hydroxyproline content was also analyzed. The HFS sedentary and HFS + F groups had higher final body masses and fat percentages compared to the chow and HFS + E groups. Yield strain was reduced in the HFS sedentary rats compared to the chow rats. Peak and steady-state stresses, failure strain, Young’s modulus, and hydroxyproline content were not different across groups. Although the HFS + E group showed higher failure stress, yield stress, and yield strain compared to the HFS sedentary group, HFS + F animals did not produce differences in the properties of the tail tendon compared to the HFS sedentary group. These results indicate that exposure to a HFS diet led to a reduction in the yield strain of the tail tendon and aerobic exercise, but not fibre supplementation, attenuated these diet-related alterations to tendon integrity.

Abstract As human-animal studies (HAS) scholarship has grown and expanded over the past few decades, so have opportunities to bring nonhuman animals into higher education. This article presents an instructional design option for teaching the animal through interdisciplinary experiential learning. Interdisciplinary learning integrates multidisciplinary knowledge across a central theme while experiential learning encourages learners to move through a recursive process of experiencing, reflecting, thinking, and acting. The article also reflects on student learning outcomes based on a questionnaire survey conducted five years after the course completion. Preliminary insights reveal the transformative potential of this approach given students’ modified viewpoints, enhanced ethical sensitivity, enlarged horizons, and behavioral changes regarding animals. HAS scholars are encouraged to engage in animal-focused scholarship of teaching and learning in higher education by sharing instructional templates and scholarly research on HAS courses. Doing so will expand opportunities for students to appreciate, critically examine, and positively influence animal lives.

Novel data obtained through experimental investigation into the fatigue response of 350WT steel, subjected to semi-random loading, comprised of various combinations of intermittent tensile overloads and compressive underloads are presented. An effective model for predicting the fatigue response is also introduced. For that, the capabilities of some of the currently available models are investigated and then an exponential delay model, being capable of accounting for the effects of not only overload ratio, but also stress ratio and overload/underload ratio is introduced. Since most variable amplitude models are based on a constant amplitude model, efforts were also expended to identify a constant amplitude fatigue crack growth model that would be easy to use, requiring the calibration of few (if any) empirical curve-fitting parameters. The integrity of a selected model is examined and results are presented.

Abstract During the processing of water containing food materials, water transport can be driven by pressure from gas, capillarity, swelling, or gravity. To describe these various modes of pressure-driven transport using Darcy's law, permeability is a critical parameter for which few data are available, primarily as a result of measurement difficulties. Permeability in the flow of liquid water through potato tissue was estimated by approximating the plant cellular structure, measured directly using flow-through and indirectly using nuclear magnetic resonance. The data from the three approaches show the same order of magnitude 10−18 m2, and thus are in agreement with each other and results reported in the literature. The dynamics of porosity and permeability changes in fresh, water-saturated, and cooked samples were described using cellular structure changes as observed in microscopy images. Simple mechanistic equations for predicting permeability and porosity, which can include swelling and shrinkage, are proposed based on approximating the geometry of the cellular tissue. Data corroborated in three ways will provide permeability values with confidence, while the simple prediction equation will make a reasonable estimation of permeability possible for a large class of food products.

Progress is reviewed in our understanding of the effects of high electrostatic fields (of the order of volts per angstrom) on the adsorption and reaction of atoms and molecules on metal and semiconductor surfaces.

In this paper, we investigate two-sided bounds for the small ball probability of a mixed fractional Brownian motion with a general deterministic trend function, in terms of respective small ball probability of a mixed fractional Brownian motion without trend. To maximize the lower bound, we consider various ways to split the trend function between the components of the mixed fractional Brownian motion for the application of Girsanov theorem, and we show that the optimal split is the solution of a Fredholm integral equation. We find that the upper bound for the probability is also a function of this optimal split. The asymptotic behaviour of the probability as the ball becomes small is analyzed for zero trend function and for the particular choice of the upper limiting function.

Abstract Background and purpose Cure rates of paediatric malignancies have dramatically improved with therapy intensification, at the cost of late treatment side effects. A survey was developed, centred around medulloblastoma scenarios, in order to explore paediatric oncology physicians’ views on discussing late effects and involving parents in treatment decisions. Materials and methods Participants were 59 paediatric radiation and medical oncologists or fellows from USA (22), Canada (18), Europe (16), Australia (2), and Asia (1). Results Ninety-five percent of respondents indicated late effects discussion prior to multimodality treatment was important. Of those who supported it, 100%, 83%, 64%, and 48% thought discussing cognitive impairment, infertility, stroke, and seizures as potential late effects was important, respectively. Only 71% of respondents believed parents should be involved in treatment decisions, which did not significantly vary by respondent age, country, specialty, gender, or years in practice. Conclusions The majority of oncologists who treat children believe discussing late effects with parents is important. However, there is mixed opinion on which late effects should be discussed and whether parents should be involved in deciding which treatments should be pursued. Research into perceived barriers to shared decision making and effective methods of improving the informed consent process in paediatric malignancies is needed.

Objectives The study objectives were to extend the follow-up of the Ontario uranium miners cohort, one of the largest cohorts of uranium miners with low cumulative exposures, to examine the relationship between radon exposure and lung cancer mortality and, for the first time incidence, and address gaps in the literature, including dose–response relationship between radon exposure and other cancer sites, and non-cancer mortality. Methods The cohort of mine and mill workers was created using data from Canada9s National Dose Registry and the Ontario Mining Master File. The follow-up for the cohort was recently extended for mortality (1954–2007) and for the first time includes cancer incidence (1969–2005). The Poisson regression was used to estimate relative risks (RR) and excess relative risks (ERR) and their 95% CIs with levels of cumulative radon exposure. Results The cohort consisted of 28 546 male miners with a mean cumulative radon exposure of 21.0 working level months (WLM). An increased risk of lung cancer and a dose–response relationship was observed with cumulative radon exposure. Miners exposed to >100 WLM demonstrated a twofold increase in the risk of lung cancer incidence (RR=1.89, CI 1.43 to 2.50) compared with the non-exposed group, and a linear ERR of 0.64/100 WLM (CI 0.43 to 0.85), with similar results observed for mortality. No association was observed for other cancer sites (stomach, leukaemia, kidney and extrathoracic airways) or non-cancer sites (cardiovascular diseases) with increasing cumulative exposure to radon. Conclusions These findings suggest no increased risk of cancer sites other than lung or non-cancer mortality from relatively low cumulative exposure to radon.