Interactions between multiple anthropogenic stressors can have unexpected synergistic or antagonistic effects, making it difficult to predict their combined effect using single stressor studies. The interaction between invasive consumers and nutrient enrichment is particularly important as both of these stressors frequently co-occur and their respective bottom-up and top-down effects have the potential to interact across multiple trophic levels. We conducted a mesocosm experiment that crossed an increasing nutrient addition gradient against an increasing zebra mussel invasion gradient. Native zooplankton communities were added to the mesocosms, and after three months we examined how the single stressor effects on available resources and the zooplankton community were altered by their multiple stressor interaction. Added nutrients had no effect on primary producer abundance, but increased the abundance and dominance of the top consumer, which likely increased predation pressure on the producers and so prevented their response to increased nutrients. Zebra mussels reduced total phytoplankton abundance by ~75%, rotifer abundance by ~80%, and shifted communities towards dominance of cladocerans and adult/juvenile copepods. When combined, the top-down control exerted by the mussels interacted antagonistically to prevent any bottom-up influence of nutrient enrichment on the zooplankton community. These results provide insight into the potential outcomes of nutrient and invasive consumer stressor interactions, and illustrate the need for researchers to consider single stressor problems in a multiple stressor context. / Thesis (Master, Biology) -- Queen's University, 2014-01-31 15:20:15.387

Elephants are cognitive species that exhibit many types of learning. Associative, social, and insight learning have been investigated with elephants, but one of the simplest forms, habituation, has not. As an individual learns that a stimulus is neither harmful nor beneficial, it will decrease its response to the stimulus through the process of habituation. Elephants possess a well-developed sensory system and may habituate to stimuli that could be used for enrichment and/or management. The aim of this study was to examine the habituation process of elephants in response to repeated presentations of two auditory stimuli –buzzing by a disturbed beehive and the sound of banging on pots and pans, as these sounds invoke alert and avoidance behaviors in wild elephants as part of humanelephant conflict mitigation. I hypothesized that elephants would initially exhibit strong reactions to both sounds, but these responses would diminish over repeated trials. I also hypothesized that their responses to the bee sound would decrease more slowly than to the pot/pans sound because bee buzzing represents a biological cue that a threat is nearby. This study was conducted using four female African elephants (Loxodonta africana) at the Nashville Zoo. Elephants received each stimulus for a 10-day period. On the first sound presentation, the elephants reacted by exhibiting distress, avoidance, and vigilance behaviors. Over repeated presentations, the elephants stopped responding to the stimuli, suggesting habituation had occurred. They also seemed to generalize their habituation between the first and second sound, resulting in a faster habituation to the second sound. Although a preliminary study, the results suggest that elephants learn which stimuli are non-threatening and subsequently stop responding to them, most likely through habituation. Specifically, the elephants habituated to bee buzzing and banging pots and pans, two deterrents used to stop elephants from entering farmlands and eating crops. Habituation is a major concern for the development of effective human-wildlife conflict mitigation and zoo enrichment programs. The results from this study indicate that habituation is an important learning process that should be considered during the implementation of captive and wildlife management, even for highly intelligent species such as elephants.

With rapidly urbanizing societies, waste management needs attention. In 2008, EUs Waste Framework Directive (WFD) set new concepts, like reducing usage of natural materials. Thus, the interest for alternative materials increased. In Skellefteå, since the 1970’s, iron sand has often substituted natural gravel in road construction. But, today stricter regulations might forbid iron sand for further use. The issue is whether leachate from iron sand causes heavy metal pollution or not. This thesis tried to provide more knowledge into iron sand’s environmental impact. In order to investigate this, a sediment sample (<53 cm deep) collected in Inre-viken, a lake 50m from a road with iron sand, were analyzed for Zn, Pb and Cu concentrations. Enrichment factor (EF), national benchmarks, and reference data were used to evaluate anthropogenic impact and age-determine the sediment. The results showed: (1) Inre-viken has elevated heavy metal levels compared to pre-industrial levels, with highest Cu (133 mg/kg) and Zn(204 mg/kg) concentrations found in the surface layer. (2) Zn and Cu showed an increase between 41-0 cm depth (1970-2015), but only Cu reaches high concentrations, while Zn and Pb range between low to very low concentrations. (3) The metal enrichment is low compared to the reference lake. The findings show that there are elevated levels in Inre-viken compared to pre-industrial levels. However, identifying the main source of pollution is difficult, because many pollution sources exist in the area. To determine if iron sand is the culprit, further studies are necessary.

Marriages and families are currently under tremendous pressure. Many marriages and families battle to adapt to changing life circumstances. They have become ignorant about the Divinely intended substance of relationships and are barely surviving. These marriages break up and end up in unhappiness and many times in the breaking up thereof. During the past 40 years there have been many attempts by state and church to stop the deterioration of marriages and family relationships and to put back the essential qualities of life. Many marriage enrichment programmes have been initiated and many couples and families have been encouraged to participate. Social programmes have been discussed and marriage and family initiatives have been launched during these programmes. This has brought hope in many communities. In this confused world of relativism and adaptation people have found some anchor points for their relationships and have found new meaning in their existence. However the question still remains: Do these programs just give a temporary surge of enthusiasm? To move from one program to another and to attend the one course after the other, does not bring a lasting solution. Courses and programs cannot function as crutches from which to get support for wavering marriages and family life. Couples and family members must be equipped in an integral way to revive their marriage and family life. They must be taught to become aware of the richness of happenings and memories that make relationships special and integrate these into their relationships. Rituals (for example: Baptism and Holy Communion) have helped church and humanity through the ages, to look past stale relationships and circumstances, to discover anchors in life and get through traumatic events. These rituals have been the reason for so many unique outcomes in stale relationships and have opened a new future for individuals and groups where none was evident. During this study these rituals have been seen as long–term assistance for marriages and families for the maintenance, extension and dynamics thereof. Rituals with the help of the development line of narrative research methodology, have been put in place to help couples and families to a better understanding and support of each other. They put new life into relationships, to build attainable future dreams and have given the opportunity for partners to move away from stale relationships to more hopeful relationships. The value of the local enrichment program as a safe environment for growth, adaptation and the integral implementation of meaningful rituals in marriage and family life, cannot be stressed enough. Within this enrichment program, with its relevant rituals, relationships are dynamically turned to the future. Believe in the existence of relationship has been found. Energy has been given to couples and families to live more purposefully. They are more creative and have a better understanding of each other. They can face the future together. / Thesis (Ph.D. (Practical Theology))--North-West University, Potchefstroom Campus, 2011.

This study was undertaken in an attempt to establish the cognitive development of student teachers and to determine the impact of Feuerstein's Instrumental Enrichment programme on the development and/or improvement of the cognitive skills of student teachers. A literature study was undertaken to highlight the importance and nature of thinking abilities necessary for learning, as well as the role of Feuerstein's Instrumental Enrichment programme in this regard. Explanatory mixed method research by means of testing, as well as a narrative analysis was employed. An empirical study with a pre-experimental research design in which intervention research was incorporated was conducted over a period of twelve weeks with twenty four second-year student teachers majoring in Mathematics. The students were randomly assigned to two groups. A pretest with the DAT-L test was administered to both groups to determine the extent of their thinking skills development. After the pre-test group 1 was exposed to intervention with the Feuerstein Instrumental Enrichment programme for a period of six weeks in an attempt to develop and/or improve thinking skills. After the intervention program group 1 was tested again with the DAT-L test in order to determine if the intervention programme had developed and/or improved thinking skills or not. After this, group 2 was exposed to intervention with the Feuerstein Instrumental Enrichment programme for a period of six weeks. After the six week period both groups were tested again with the DAT-L test to determine the impact of the intervention programme on the thinking skills of group 2 and to establish what happened to the thinking skills of group 1 during the period in which they were not exposed to the intervention. In support of the data gained through the test results, participants were requested to write up their perceptions of and experiences related to the Feuerstein Instrumental Enrichment programme in a narrative. The narratives were analysed and the results were utilized to support the data obtained with the quantitative study. Results indicated that room exists for improving the thinking skills of student teachers and that Feuerstein's Instrumental Enrichment programme possesses the latent potential to improve and develop thinking skills. The study is concluded with recommendations on how to develop and improve thinking skills. / Thesis (M.Ed.)--North-West University, Vaal Triangle Campus, 2009.

This study was undertaken in an attempt to establish the cognitive development of student teachers and to determine the impact of Feuerstein's Instrumental Enrichment programme on the development and/or improvement of the cognitive skills of student teachers. A literature study was undertaken to highlight the importance and nature of thinking abilities necessary for learning, as well as the role of Feuerstein's Instrumental Enrichment programme in this regard. Explanatory mixed method research by means of testing, as well as a narrative analysis was employed. An empirical study with a pre-experimental research design in which intervention research was incorporated was conducted over a period of twelve weeks with twenty four second-year student teachers majoring in Mathematics. The students were randomly assigned to two groups. A pretest with the DAT-L test was administered to both groups to determine the extent of their thinking skills development. After the pre-test group 1 was exposed to intervention with the Feuerstein Instrumental Enrichment programme for a period of six weeks in an attempt to develop and/or improve thinking skills. After the intervention program group 1 was tested again with the DAT-L test in order to determine if the intervention programme had developed and/or improved thinking skills or not. After this, group 2 was exposed to intervention with the Feuerstein Instrumental Enrichment programme for a period of six weeks. After the six week period both groups were tested again with the DAT-L test to determine the impact of the intervention programme on the thinking skills of group 2 and to establish what happened to the thinking skills of group 1 during the period in which they were not exposed to the intervention. In support of the data gained through the test results, participants were requested to write up their perceptions of and experiences related to the Feuerstein Instrumental Enrichment programme in a narrative. The narratives were analysed and the results were utilized to support the data obtained with the quantitative study. Results indicated that room exists for improving the thinking skills of student teachers and that Feuerstein's Instrumental Enrichment programme possesses the latent potential to improve and develop thinking skills. The study is concluded with recommendations on how to develop and improve thinking skills. / Thesis (M.Ed.)--North-West University, Vaal Triangle Campus, 2009.

Marriages and families are currently under tremendous pressure. Many marriages and families battle to adapt to changing life circumstances. They have become ignorant about the Divinely intended substance of relationships and are barely surviving. These marriages break up and end up in unhappiness and many times in the breaking up thereof. During the past 40 years there have been many attempts by state and church to stop the deterioration of marriages and family relationships and to put back the essential qualities of life. Many marriage enrichment programmes have been initiated and many couples and families have been encouraged to participate. Social programmes have been discussed and marriage and family initiatives have been launched during these programmes. This has brought hope in many communities. In this confused world of relativism and adaptation people have found some anchor points for their relationships and have found new meaning in their existence. However the question still remains: Do these programs just give a temporary surge of enthusiasm? To move from one program to another and to attend the one course after the other, does not bring a lasting solution. Courses and programs cannot function as crutches from which to get support for wavering marriages and family life. Couples and family members must be equipped in an integral way to revive their marriage and family life. They must be taught to become aware of the richness of happenings and memories that make relationships special and integrate these into their relationships. Rituals (for example: Baptism and Holy Communion) have helped church and humanity through the ages, to look past stale relationships and circumstances, to discover anchors in life and get through traumatic events. These rituals have been the reason for so many unique outcomes in stale relationships and have opened a new future for individuals and groups where none was evident. During this study these rituals have been seen as long–term assistance for marriages and families for the maintenance, extension and dynamics thereof. Rituals with the help of the development line of narrative research methodology, have been put in place to help couples and families to a better understanding and support of each other. They put new life into relationships, to build attainable future dreams and have given the opportunity for partners to move away from stale relationships to more hopeful relationships. The value of the local enrichment program as a safe environment for growth, adaptation and the integral implementation of meaningful rituals in marriage and family life, cannot be stressed enough. Within this enrichment program, with its relevant rituals, relationships are dynamically turned to the future. Believe in the existence of relationship has been found. Energy has been given to couples and families to live more purposefully. They are more creative and have a better understanding of each other. They can face the future together. / Thesis (Ph.D. (Practical Theology))--North-West University, Potchefstroom Campus, 2011.

Maternal stress during the perinatal period has been linked to attention and behavioral problems and increased adrenocortical activity in children. Underlying this relationship is thought to be exposure to excessive glucocorticoids during development. The aim of this set of studies was to determine the effects of chronic maternal stress (CMS) during the perinatal period on behaviour and endocrine function in male and female guinea pig offspring at the juvenile and adult life stage. Environmental enrichment was investigated as a potential therapeutic tool to reverse changes induced by CMS. Pregnant guinea pigs were exposed to a sequence of stressors every other day over the second half of gestation until weaning on postnatal day 25. Offspring were tested for ambulatory activity, attention, cognitive function, sex-steroid levels and adrenocortical function. One cohort of animals were housed in an enriched environment, the remaining offspring were housed in standard conditions. A separate cohort was administered amphetamine (1 mg/kg) prior to behavioural testing to determine influence of CMS on dopaminergic function. Juvenile male and female offspring of mothers exposed to stress exhibited increased basal and decreased stress-induced salivary cortisol, and male offspring displayed reduced activity and a phase shift in their circadian rhythm of activity. Adult male offspring of CMS mothers exhibited increased activity in a novel environment and decreased activity in a familiar environment. Female adult offspring of CMS mothers exhibited reduced attention and increased activity in a novel environment. Enrichment acted independently of CMS, increasing plasma testosterone and attention in adult male offspring and reducing the adrenocortical response to stress and decreasing attention and activity in female offspring. Amphetamine decreased activity in a novel environment and increased activity in a familiar environment in both sexes, regardless of age or maternal treatment. Amphetamine improved attention in juvenile and adult males. The current studies demonstrated a strong effect of CMS on behaviour in juvenile and adult offspring. Enrichment was not effective for attenuating the effects of CMS. These studies clearly demonstrate behavioural changes as a result of CMS emerge over the lifetime of the offspring and have begun to uncover the underlying mechanisms of programming.

Maternal stress during the perinatal period has been linked to attention and behavioral problems and increased adrenocortical activity in children. Underlying this relationship is thought to be exposure to excessive glucocorticoids during development. The aim of this set of studies was to determine the effects of chronic maternal stress (CMS) during the perinatal period on behaviour and endocrine function in male and female guinea pig offspring at the juvenile and adult life stage. Environmental enrichment was investigated as a potential therapeutic tool to reverse changes induced by CMS. Pregnant guinea pigs were exposed to a sequence of stressors every other day over the second half of gestation until weaning on postnatal day 25. Offspring were tested for ambulatory activity, attention, cognitive function, sex-steroid levels and adrenocortical function. One cohort of animals were housed in an enriched environment, the remaining offspring were housed in standard conditions. A separate cohort was administered amphetamine (1 mg/kg) prior to behavioural testing to determine influence of CMS on dopaminergic function. Juvenile male and female offspring of mothers exposed to stress exhibited increased basal and decreased stress-induced salivary cortisol, and male offspring displayed reduced activity and a phase shift in their circadian rhythm of activity. Adult male offspring of CMS mothers exhibited increased activity in a novel environment and decreased activity in a familiar environment. Female adult offspring of CMS mothers exhibited reduced attention and increased activity in a novel environment. Enrichment acted independently of CMS, increasing plasma testosterone and attention in adult male offspring and reducing the adrenocortical response to stress and decreasing attention and activity in female offspring. Amphetamine decreased activity in a novel environment and increased activity in a familiar environment in both sexes, regardless of age or maternal treatment. Amphetamine improved attention in juvenile and adult males. The current studies demonstrated a strong effect of CMS on behaviour in juvenile and adult offspring. Enrichment was not effective for attenuating the effects of CMS. These studies clearly demonstrate behavioural changes as a result of CMS emerge over the lifetime of the offspring and have begun to uncover the underlying mechanisms of programming.

A series of model steels containing copper levels up to 0.48wt%, nickel up to 0.22wt% and silicon levels of 0.52wt% were oxidised in air at 1050 and 1150??C, and in a CO2-N2 mixture at 1250??C for times of up to 3 hours. The scaling kinetics were measured and the behaviour of copper-rich phase formation at the scale/metal interface was investigated. When oxidised at 1050/1150??C, significant quantities of copper-rich phase were observed for most model steels. The relatively high oxidation rate under these conditions led to the rapid development of a copper-rich layer with little copper diffusing into the metal. However, when oxidised at 1250??C, the copper-rich phase did not form for a significant amount of time; and for some model steels, not at all. This was attributed to the considerably lower oxidation rate and the fact that more copper was found to have diffused into the metal. Alloying additions of nickel and silicon were found to be beneficial in reducing the amount of copper-rich phase measured at the scale/metal interface under the conditions investigated at 1150??C and 1250??C. This occurred because nickel and silicon addition promoted the occlusion of copper-rich phase into the scale. Copper enrichment during oxidation was modelled using a numerical description of the diffusion processes involved. Predictions of the time for commencement of copper-rich phase formation at 1250??C were in close agreement with observation. Agreement between predicted and observed copper-rich layer thickness was less successful under conditions where occlusion was significant, and the measured thickness varied non-uniformly with time. The cracking susceptibility of the model steels was examined using a hot compression test. Oxidation was performed in air at 1050, 1150 and 1250??C and most specimens were compressed at 1050??C. The amount of cracking was found to increase with the amount of copper-rich phase precipitated at the scale/metal interface during oxidation. In general, nickel addition reduced the amount of cracking at all temperatures; and under some conditions prevented cracking altogether. Silicon reduced or completely suppressed cracking when the subscale formed was liquid. The beneficial effects of nickel and silicon addition were attributed to their effect of promoting copper occlusion.