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Lotka-Volterra predator-prey models analytic and numerical methods.
No full textThe Lotka-Volterra equations are a classical model of the populations of interacting
species. In the case of two interacting species, we present a closed parametric solution
to a particular case of the Lotka-Volterra model. We also determine closed expressions
for the branch points, bounds on the parameter, amplitude of the oscillation of the
prey and predator populations, and period of this model in terms of the Lambert W
function. In the case of three interacting species, under certain conditions solutions
are again periodic. However, standard numerical methods often fail to preserve this
periodicity, as well as other important properties of the model. The underlying geometry
of the three-species predator-prey model is developed through the framework of
Poisson dynamics. It is shown that the system is bi-Poisson and possesses two independent first integrals. Numerical methods for approximating solutions to the model
are constructed which incorporate the underlying Poisson geometry of the continuous
system. These methods preserve the periodicity of solutions, and the error in the first
integrals remains bounded. Simulations are used to show that these methods produce
more accurate results than standard numerical methods which do not consider the
Poisson structure of the equations
Contributing to children’s early comprehension of emotions: a picture book approach
No full textPrevious studies have suggested that children’s emotion comprehension begins to develop in the
early stages of childhood and has been linked to prosocial behaviours, displays of empathy and
better interpersonal relationships, to name a few. However, children’s level of emotion
comprehension does not develop at the same rhythm due to both environmental and biological
factors. That said, there are few interventions that can help children in their development of
emotion understanding, but these interventions are not readily accessible (e.g., cost, availability,
duration). The current study examined the use of shared book reading and the effectiveness of
picture books created on current theories and models of children’s emotion comprehension.
Eighteen preschoolers were divided into an experimental and a control group. Over the course
of multiple exposures to the experimental treatment, results revealed a significant gain for the
experimental group compared to the control group. These results are promising by showing
that a simple shared book reading approach can contribute to the development of emotional
comprehension without requiring special training or expertise
Understanding educational caregivers accuracy in detecting facial expressions of pain in children: an eye-tracking study
No full textFacial expressions of pain are important indicators that an individual needs attention from others. Previous studies have found that different caregiver groups have had difficulty in distinguishing genuine, suppressed and fake pain in children. The current study examines education professionals and their ability to recognize pain expressions in children while their eye-movements were tracked. Eye-tracking was used to understand their accuracy in detecting pain expressions, as well as identifying strategies to improve recognition. Results indicated that participants were more accurate for suppressed than fake expressions, and more for fake than genuine expressions. Results from eye movement patterns offer information on how to improve accuracy upon recognition. For genuine and suppressed expressions, participants must attend to the eye zone longer than the mouth zone. For fake expressions, the mouth zone needs more attention to increase accuracy. Also, when participants spent more time in the eye zone than the mouth zone, their levels of accuracy decreased.Undergraduate These
Thematic analysis of key recommendations from commissioned occupational Health and Safety Reports in mining
No full textThe purpose of this research was to review the commissioned occupational health and safety (OHS) reports in mining, over the past 50 years, in a two-step approach. The objective of the initial phase was to determine if there were any recommendations that were stated in more than one of the evaluated commissioned reports, that spanned the 50-year timeframe. The reports were selected through a review of the literature and in consultation with experts in OHS and mining. A multi-stage analysis was conducted on the recommendations, and identified 6 overlapping themes, and 49 sets of specific overlaps. In the second phase, a seeded analysis using a qualitative data analysis software, was completed to understand how safety culture was discussed in the reports. This was accomplished by completing a review of the literature to define safety culture, and to build the dictionary, which was seeded into the software. The analysis highlighted the use of various terms for safety culture throughout the 50-year history, with a particular emphasis on the fact that the term safety culture was not directly referenced in the selected reports until 1997.
Keywords: Mining; Occupational Health and Safety; Accident Investigation; Commission Recommendations; Leximancer
Earwitness identification: an examination of scenario, lineup type and gender as factors in identification accuracy.
No full textThe current study was conducted examining the effects of scenario type, lineup type and target gender in regard to earwitness identification accuracy. Two hundred and forty participants listened to one of the three possible scenarios (criminal, neutral, controversial), and were asked to identify either a male or a female perpetrator Participants completed the State Trait Anxiety Inventory during the retention interval, which lasted roughly five minutes. Afterwards they were asked to identify either the male or female voice from a five-voice lineup. Voice lineups were presented either simultaneously or sequentially. Participants were less accurate at identifying the male voice compared to the female voice in both present and absent lineups. Participants were also more accurate at identifying the target voice in the present simultaneous condition compared to the sequential condition. All other conditions were found to be non-significant. These findings help advance the field and understand the variables such as lineup, gender and scenario
Living with a sibling who has Autism Spectrum Disorder
No full textThe document presented herein is a manuscript-based thesis, entitled: Living with a Sibling who
has Autism Spectrum Disorder (ASD). This thesis consists of an exploratory investigation to
learn more about the experiences of individuals who have a sibling with ASD. The data obtained
is discussed in two papers. The first paper focuses on the discussion of future caregiving which
involves the transference of care to siblings (with typical development) when parents are no
longer able to provide care. The scope of the second paper solely focuses on data obtained from
interviews using Interpretative Phenomenological Analysis (IPA; Smith, Flowers & Larkin,
2009). Siblings highlighted particular aspects of future caregiving that harboured concerns,
resulting in the discussion of four relevant themes. The second paper was guided by the Family
Adjustment and Adaptation Response (FAAR) Model (Patterson, 1988, 1989; Patterson &
Garwick, 1994) to explore the type of stressors that were experienced and whether adequate
supports were being utilized. To understand experiences specific to demands and supports, a
mixed-methods approach was employed. Informed by the FAAR, interview transcripts were
analyzed using Thematic Analysis (Braun & Clarke, 2006), revealing four themes. Descriptive
statistics were also provided based on data obtained from two questionnaires: The Sibling
Inventory of Behaviour Scale (SIBS) and The Sibling Daily Hassles and Uplifts Scale (SDHUS).
Results concluded that siblings are constantly in the process of finding new resources and
developing new capabilities to manage demands across the life span. Clinical implications for
each paper are discussed further
Les bienfaits de la socialisation au programme de jour du Centre de services Guigues (CSG) sur la santé des personne âgées francophones ayant vécu l'isolement ou la solitude dans la région d'Ottawa
No full textL’objectif de cette étude consiste à montrer les bienfaits des activités de socialisation au programme de jour du Centre de services Guigues (CSG) sur la santé des personnes âgées francophones ayant vécu l’isolement ou la solitude dans la région d’Ottawa. En effet, le CSG est un organisme à but non lucratif de la collectivité francophone de la région d’Ottawa. Sa mission consiste à garantir des services de soutien communautaires et des activités socio-récréatives en français, dans toute la région d’Ottawa, aux personnes âgées ainsi qu’aux adultes ayant une incapacité.
Pour répondre aux questions de recherche et pour vérifier les hypothèses qui étaient mises en avant, l’approche structurelle a servi de toile de fond à cette étude. Elle a permis de comprendre, d’analyser et d’interpréter les résultats obtenus lors des entrevues semi-dirigées avec huit aînés ayant volontairement accepté de parler d’eux et de leurs expériences comme participants aux activités de socialisation au programme de jour du CSG.
Étant donné que l’approche structurelle part de la thèse selon laquelle ce sont les structures et les institutions sociales qui sont la source primaire des problèmes sociaux des individus, cette étude montre que le problème d’isolement et de solitude sociale des aînés francophone en contexte minoritaire constitue un problème dont la cause est aussi structurelle. Bien que le CSG organise professionnellement les activités de socialisation à son programme de jour, à la suite de cette recherche, il s’avère que la structure du CSG nécessite un agrandissement à la dimension de sa mission. Cet agrandissement ne peut se faire que si la société (ville d’Ottawa, gouvernement provincial de l’Ontario et gouvernement fédéral du Canada) accepte de porter une attention particulière au problème d’isolement social des aînés francophones en contexte minoritaire dans la région d’Ottawa.
En substance, la recherche a démontré que la participation sociale ou les activités de socialisation procurent des bénéfices notables sur la santé des personnes âgées. Il importe de vérifier, avec d’autres études, à quel point ces activités de socialisation peuvent être bénéfiques, aussi bien pour les aînés encore en bonne santé – au début de la retraite – que pour les personnes âgées déjà fragilisées par les effets néfastes de l’isolement et de la solitude sociale. Cela permettra de déterminer le moment opportun et convenable pour optimiser les bienfaits de la socialisation, en lien avec l’âge et l’état de santé des aînés.Maîtrise en service socia
The role of intestinal hydrogen sulfide on GLP-1 secretion and downstream metabolism
No full textMetabolic hormones released from the gastrointestinal tract are core regulators for digestion,
satiety, gut motility, and glucose homeostasis. Advancements in the management of type 2
diabetes and obesity have recently included the use of incretin hormone-based therapies, such as
glucagon-like peptide-1 (GLP-1) analogs. GLP-1 can enhance glucose-dependent insulin
secretion and stimulate satiety after a meal. The release of this incretin is stimulated by the entry
of nutrients in the lumen or circulation. In addition, microbial metabolites have recently emerged
as a new group of potent stimulators of GLP-1 secretion. Hydrogen sulfide (H2S), produced from
sulfate-reducing bacteria (SRB) of the distal ileum and colon, are localized in the same niche as
GLP-1 secreting L-cells. The physiological role of endogenous H2S is well established in many
biological systems, however it is not well understood how or if H2S can affect the
enteroendocrine system. Therefore, we hypothesized that microbial H2S from the distal GI tract
can potentially alter GLP-1 secretion and downstream metabolism, and further investigated the
potential mechanisms involved in the process. In murine colonic L-cells (GLUTag), we
demonstrated that H2S donors (NaHS and GYY4137) significantly enhanced GLP-1 secretion
and that the process was regulated through the p38 MAPK signaling pathway. In male C57BL/6
mice, a 4-week chondroitin sulfate prebiotic diet successfully elevated SRB and colonic H2S
levels, enhanced the GLP-1 response, and reduced food intake. Together, this study
demonstrated a direct role for H2S in the stimulation of GLP-1 and a potential role for sulfur prebiotics to increase the H2S producing SRB as a means to enhance GLP-1 and improve
metabolis
Examining anaerobic microbial communities that direct the fate of terrestrial carbon in lake sediments.
No full textFreshwater lake sediments play key roles in the cycling of carbon. This includes hosting microbial communities responsible for mineralizing large amounts of carbon into greenhouse gases—namely CO2 and CH4. Yet despite the important roles of sediment communities, their ecology and community structure linkages to biogeochemical cycling are not well known, and little data exists exploring how sediment microbial communities respond to different organic matter inputs. Here I start by reviewing previous literature on lake sediment microbial communities and the physicochemical factors affecting their composition and diversity. Next I
report on data from two experiments, first an in-vitro lab study and then an in-situ field study, in which lake sediments were amended with different plant litters that could result from land use change and or succession in catchments. Microbial communities were examined with next generation amplicon sequencing. These data were linked to rates of CO2 and CH4 flux and dissolved organic matter (DOM) components present in pore water were examined as potential controls on community structure and function. I observed in-vitro that methanogen community composition and activity were affected by OM type, with macrophyte derived C enhancing microbial activity, whereas high concentrations of polyphenolic compounds from terrestrial tree
litters inhibited methanogen activity. The polyphenols had an environmental filtering effect, selecting for different bacteria, fungi and methanogen communities. The in-situ experiments involved installing mesocosms with artificial sediments with variable amounts of deciduous and coniferous tree leaf litter. In these mesocosms we observed a link between methanogen community composition and decomposition rates, as measured with bulk CO2 and CH4 production and DOM humification. Decomposition rates were influenced by lake
physicochemical factors, particularly the degree of photoexposure. With increased decomposition, specialist taxa of methanogens could thrive that conferred higher rates of methanogenesis. The work presented here demonstrates the adaptability of methanogen lake sediment communities as terminal decomposers under changing terrestrial OM subsidies