Showing papers by "Memorial University of Newfoundland published in 2002"

Chitosan as an edible invisible film for quality preservation of herring and atlantic cod.

Abstract: The effect of chitosan with different molecular weights as coatings for shelf-life extension of fresh fillets of Atlantic cod (Gadus morhua) and herring (Clupea harengus) was evaluated over a 12-da...

Pea Starch: Composition, Structure and Properties — A Review

Abstract: Recently, pea has developed into a major protein crop in Western Canada. In the search for new food protein resources, small commercial facilities in Canada have engaged in manufacturing protein concentrates from pea by air classification or wet milling techniques. However, the major products from these processes are either crude or refined pea starches. Pea starch has been utilized almost exclusively for industrial application. A major factor, which has an adverse effect on the widespread utilization of pea starch in food industry, it its high extent of retrogradation. This review summarizes the present knowledge on composition, structure and physiochemical properties of smooth and wrinkled seeded pea starches with a view to providing suggestions for needed research to improve the utilization of pea starches in the food industry.

Nutrition and the immune system from birth to old age.

Abstract: For millennia, food has been at the center of social events, in times of joy and in times of sorrow. Protein-energy malnutrition is associated with a significant impairment of cell-mediated immunity, phagocyte function, complement system, secretory immunoglobulin A antibody concentrations, and cytokine production. Deficiency of single nutrients also results in altered immune response: this is observed even when the deficiency state is relatively mild. Of the micronutrients, zinc, selenium, iron, copper, vitamins A, C, E and B6, and folic acid have important influences on immune responses. Overnutrition and obesity also reduce immunity. Low-birth-weight infants have a prolonged impairment of cell-mediated immunity that can be partly restored by providing extra amounts of dietary zinc. In the elderly, impaired immunity can be enhanced by modest amounts of a combination of micronutrients. These findings have considerable practical and public health significance.

Muscle force and activation under stable and unstable conditions.

Abstract: The objective of this study was to determine differences in isometric force output, muscle activation (interpolated twitch technique), and electromyographic activity of the quadriceps, plantar flexors (PF), and their antagonists under stable and unstable conditions. Instability in subjects was introduced by making them perform contractions while seated on a "Swiss ball." Eight male subjects performed unilateral leg extensor (LE) and PF contractions while seated on a bench (LE), chair (PF), or a ball. Unstable LE and PF forces were 70.5 and 20.2% less than their stable counterparts, respectively. Unstable quadriceps and PF activation averaged 44.3 and 2.9% less than activation under stable conditions. Unstable antagonist/agonist ratios were 40.2 and 30.7% greater than stable ratios in the LE and PF protocols, respectively. The greater decrements with LE can be attributed to the instability of only 2 points of floor contact, rather than 3 points of floor contact as with the PF. Swiss balls may permit a strength training adaptation of the limbs, if instability is moderate, allowing the production of overload forces.

Congestive Heart Failure in Renal Transplant Recipients: Risk Factors, Outcomes, and Relationship with Ischemic Heart Disease

Abstract: Cardiovascular disease (CVD) is the major cause of death in renal transplant recipients (RTR). Several cohort studies have examined CVD in RTR, but none have addressed the development of congestive heart failure (CHF). CHF would hypothetically be a frequent and prognostically important event in RTR. A retrolective cohort study was, therefore, conducted in two Canadian centers to describe the incidence, risk factors for, and interrelationships between de novo CHF, de novo ischemic heart disease (IHD), and mortality in 638 consecutive adult RTR who were free of cardiac disease at 1 yr posttransplant. Detailed clinic and hospital records were available for 99% of patients. Median follow-up was 7 yr (range, 1 to 28 yr). De novo CHF occurred as frequently as de novo IHD (1.26 versus 1.22 events/100 patient-years, respectively) and appeared to carry a similar prognosis (relative risk for death, 1.78 [confidence interval, 1.21 to 2.61] for CHF versus 1.50 [1.05 to 2.13] for IHD). The incidence of CHF was considerably higher than that in the Framingham cohort, whereas the incidence of IHD was not, suggesting that renal transplantation might correspond more to a state of "accelerated heart failure" than to "accelerated atherosclerosis." Age, diabetes, gender, BP, and anemia were identified as independent risk factors for de novo CHF, whereas age, diabetes, gender, BP, and rejection were independent risk factors for de novo IHD. Optimal strategies for treatment of BP and anemia in RTR will need to be determined in randomized controlled trials.

A tutorial on linear and differential cryptanalysis

Abstract: In this paper, we present a detailed tutorial on linear cryptanalysis and differential cryptanalysis, the two most significant attacks applicable to symmetric-key block ciphers. The intent of the paper is to present a lucid explanation of the attacks, detailing the practical application of the attacks to a cipher in a simple, conceptually revealing manner for the novice cryptanalyst. The tutorial is based on the analysis of a simple, yet realistically structured, basic Substitution-Permutation Network cipher. Understanding the attacks as they apply to this structure is useful, as the Rijndael cipher, recently selected for the Advanced Encryption Standard (AES), has been derived from the basic SPN architecture. As well, experimental data from the attacks is presented as confirmation of the applicability of the concepts as outlined.

Model of the energization of outer-zone electrons by whistler-mode chorus during the October 9, 1990 geomagnetic storm

Abstract: [1] Relativistic (> 1 MeV) 'killer electrons' are frequently generated in the Earth's inner magnetosphere during the recovery phase of a typical magnetic storm. We test the hypothesis that the energization of electrons takes place by means of stochastic gyroresonant interaction between lower-energy (several 100 keV) seed electrons and whistler-mode chorus waves. We develop a model kinetic equation for the electron energy distribution, and utilize both electron and whistler-mode wave data at L=4 for a typical geomagnetic storm (on October 9, 1990) from instruments carried on the Combined Release and Radiation Effects Satellite (CRRES). Our model solutions are found to match well with the CRRES profiles of the electron flux. We conclude that the mechanism of stochastic acceleration by whistler-mode turbulence is a viable candidate for generating killer electrons, not only for the storm considered, but for similar storms with a several-day recovery phase containing prolonged substorm activity.

The Construct Validity of Ryff's Scales of Psychological Well-Being (SPWB) and their Relationship to Measures of Subjective Well-Being

Abstract: The factor structure of Ryff's Scales of Psychological Well-Being (SPWB) and their relationship to standardized measures of subjective well-being (SWB) were investigated. Two hundred seventy-seven participants ranging in age from 18 to 48 years were administered the Memorial University of Newfoundland Scale of Happiness (MUNSH), the Satisfaction With Life Scale (SWLS), and the SPWB. Results failed to support either the hypothesis that performing factor analytic procedures on the items of the SPWB should produce a six-factor solution, with scale-specific items loading most highly on their respective factors or the hypothesis that subjecting the sub-scales of the SPWB to factor analytic procedures along with standardized measures of SWB would produce one higher-order well-being factor. Instead, item loadings clustered around three major factors that could not be identified with the six scales proposed by Ryff. Moreover, the factor analysis of SPWB and SWB scale totals produced three, instead of one, higher-order factors. Implications of findings are discussed with respect to the relationship of the PWB construct to the SWB construct.

Pain in children with cerebral palsy: common triggers and expressive behaviors

Abstract: To obtain parents' identification and description of the behaviors, health care procedures and daily living situations associated with pain in children with cerebral palsy (CP), surveys were sent to parents of children with CP recruited via a clinic case list and a parents' newsletter. Forty-three parents completed the survey. Results indicated that children's ability to communicate pain verbally did not influence whether or not their parent reported observing pain. Most children (67%) were reported to have displayed pain within the month prior to rating. All pain behaviors on the Non-Communicating Children's Pain Checklist (Dev Med Child Neurol 40 (1998) 340) were endorsed by some parents, and few additional pain behaviors were identified, suggesting that this instrument adequately samples the pain behavior of children with CP. Assisted stretching was the daily living activity most frequently identified as painful by parents (93% of those reporting pain), and the one with the highest mean pain intensity. Needle injection (40%) was the medical and nursing procedure most frequently identified by parents as painful for their children. Range of motion manipulation was the therapy most frequently identified as painful by parents (58%), and the one with the highest mean intensity. Parents are able to observe pain in their children with CP regardless of the child's verbal fluency. Knowledge of behaviors and painful situations identified by parents can facilitate management of pain in children with CP.

Intermuscle differences in activation.

Abstract: The objective of this study was to investigate differences within individual subjects in the ability to activate the quadriceps, plantar flexors (PF), dorsiflexors (DF), and elbow flexors (EF) during isometric contractions. Twelve male subjects performed submaximal and maximal voluntary isometric contractions, and maximal tetanic contractions were also induced by electrical stimulation. The interpolated twitch technique was used to gauge the extent of muscle inactivation or inability to produce maximum force. Measurements included torque output, absolute and relative rate of force development (RFD), and percentage of muscle inactivation. The quadriceps exceeded all other muscle groups in voluntary and tetanic torque output, voluntary absolute RFD, and absolute and relative tetanic RFD. The quadriceps also exceeded the PF and DF in voluntary relative RFD and had greater muscle inactivation (15.5%) than the EF (5.0%), PF (5.0%), and DF (1.3%). Although the higher RFD may suggest a higher percentage of type II fibers in the quadriceps, their higher threshold of recruitment leads to greater difficulty in fully activating the quadriceps.

Performance of Interior Permanent Magnet Motor Drive over Wide Speed Range

Abstract: This paper investigates the performance of an interior permanent magnet synchronous motor (IPMSM) drive over wide speed range for high precision industrial applications. The scheme incorporates the maximum torque per ampere (MTPA) operation in constant torque region and the flux-weakening operation in constant power region in order to expand the operating limits for an IPMSM. Improved mathematical expressions are derived to analyze the performances of the IPMSM. The power ratings of the motor and the inverter are considered. The effects of motor parameters particularly, the saliency ratio (X/sub q//X/sub d/) on the voltage limit constraint and the power capability of the inverter are also investigated. The efficacy of the above mentioned drive system and the improved steady-state analysis are evaluated by both experimental and computer simulation results. The complete drive is implemented in real-time using digital signal processor (DSP) controller board DS 1102 on a laboratory 1 hp interior permanent magnet synchronous motor.