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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

The Role Volunteer Tourism Plays in Conservation: A Case Study of the Elephant Nature Park, Chiang Mai, Thailand

Rattan, Jasveen January 2009 (has links)
This study examined the role volunteer tourism played in the conservation of elephants in Chiang Mai, Thailand. A case study was conducted to determine whether volunteer tourism at the Elephant Nature Park (ENP) had an effect on elephant conservation. Specifically, this study looked at how volunteer tourism and the ENP had an impact on: non-volunteer tourists, elephants, the local economy, and government policy. Mixed methods were used to attain the data in this study. Self-administered questionnaires were created to determine the impact volunteer tourism had on non-volunteer tourists. Results showed an increase in non-volunteer tourists’ awareness of elephant tourism, volunteer tourism and elephant conservation during the time they spent at the park. Self-administered questionnaires were also used to determine whether members of the local community felt they were receiving economic or social benefits from volunteer tourism and the ENP. The data showed that community participants felt they were receiving both economic and social benefits but their responses varied depending on sex, age, and how long they had lived in the region. Semi-structured interviews were also conducted to determine the role the ENP had on the conservation of elephants in Thailand and government policy. Interviewees consisted of experts in the industry who were knowledgeable about elephant tourism, volunteer tourism, and the ENP. The data indicated that the ENP created awareness about elephant conservation issues with non-volunteer tourists, volunteers, the community, and government officials. However, the ENP did not have any measureable effect on government policy. The model of volunteer tourism utilized by the Elephant Nature Park has been shown to be effective in conserving the domestic elephant and in creating awareness about domestic elephant conservation issues in Thailand.
102

Workload-aware network processors : improving performance while minimizing power consumption

Iqbal, Muhammad Faisal 06 September 2013 (has links)
Network Processors are multicore processors capable of processing network packets at wire speeds of multi-Gbps. Due to their high performance and programmability, these processors have become the main computing elements in many demanding network processing equipments like enterprise, edge and core routers. With the ever increasing use of the internet, the processing demands of these routers have also increased. As a result, the number and complexity of the cores in network processors have also increased. Hence, efficiently managing these cores has become very challenging. This dissertation discusses two main issues related to efficient usage of large number of parallel cores in network processors: (1) How to allocate work to the processing cores to optimize performance? (2) How to meet the desired performance requirement power efficiently? This dissertation presents the design of a hash based scheduler to distribute packets to cores. The scheduler exploits multiple dimensions of locality to improve performance while minimizing out of order delivery of packets. This scheduler is designed to work seamlessly when the number of cores allocated to a service is changed. The design of a resource allocator is also presented which allocates different number of cores to services with changing traffic behavior. To improve the power efficiency, a traffic aware power management scheme is presented which exploits variations in traffic rates to save power. The results of simulation studies are presented to evaluate the proposals using real and synthetic network traces. These experiments show that the proposed packet scheduler can improve performance by as much as 40% by improving locality. It is also observed that traffic variations can be exploited to save significant power by turning off the unused cores or by running them at lower frequencies. Improving performance of the individual cores by careful scheduling also helps to reduce the power consumption because the same amount of work can now be done with fewer cores with improved performance. The proposals made in this dissertation show promising improvements over the previous work. Hashing based schedulers have very low overhead and are very suitable for data rates of 100 Gbps and even beyond. / text
103

Environmental stochasticity and African elephant population dynamics : investigating limitation through juvenile mortality.

January 2008 (has links)
The successful conservation management of African elephants depends largely on understanding the fundamental processes driving the population regulation of this species. Southern Africa’s increasing populations have raised concern over the impact of high elephant densities on the system, in stark contrast against the elephant’s more precarious position in other parts of Africa. As we search for solutions from the processes of historical elephant regulation, we realise that there is a decided lack of empirical evidence to explicitly direct our efforts. In this PhD, I attempt to investigate the application of the classic pattern of large herbivore population limitation, which mainly involves high juvenile mortality in response to stochastic environmental events, to African elephant population dynamics. Firstly, I evaluated the magnitude and frequency of mortality events that would be required to prevent elephant population growth. The death of 85 % of infants and weaned calves would need to occur twice a generation, while a single severe mortality event (causing the death of all infants and weaned calves and 10 % of the rest of the population) once a generation would be sufficient. However, the severity of these events is not matched in natural occurrence in Africa today and only a single recorded event in Tsavo National Park, Kenya, in the 1970’s has come close when more than 7 000 died during a very severe drought. Secondly, I evaluated the potential role of fire as a stochastic, massmortality event limiting elephant populations. I found that fire functions in a similar manner to other environmental catastrophes and primarily causes high juvenile mortality. However, this catastrophic event also highlighted the extreme behavioural and physiological impacts experienced by the elephant population involved. The potential role of these types of events on long-term female fecundity needs further investigation. In isolation, this type of mortality event would need to occur with high frequency to prevent population growth. However, in combination with a decrease in female fecundity, these stochastic events may have a much greater impact on population demography than first thought. Thirdly, I investigated a potential mechanistic link between stochastic mortality events and juvenile susceptibility to resource limitation. Allometric relationships dictate that juveniles select a diet of higher quality than adult elephants. We found that this was achieved by weaned calf selection of higher quality plant parts, although use of plant types and plant species was similar to that of adult females, who they move across the landscape with. The strong sexual dimorphism exhibited by this species was reflected in adult male use of lower quality forage than adult females (or juveniles) in both dry and wet seasons. Diet quality scaled negatively with body size, but adult females consistently selected a higher quality diet than adult males, irrespective of body size. The nutritional and reproductive demands placed on an individual during different life-history stages therefore influence foraging strategies, together with nutrient requirements, e.g. phosphorus for pregnancy/lactation selected consistently by females when unrestricted in the wet season, protein for growth selected consistently by weaned calves. Competitive displacement of adult females to feed at higher levels in the canopy by calves also influenced feeding behaviour. Therefore intraspecific body size, nutritional requirements (in terms of nutrients and energy) and competition had a strong influence on foraging strategy employed by age-sex classes of elephants in response to seasonal environmental change. More selective juvenile foraging requirements means that juveniles are most susceptible to resource limitation, for example during stochastic environmental events such as droughts. In small, closed systems, juvenile mortality is likely to have a strong influence on elephant population regulation, with a slight, temporary decrease in female fecundity possibly acting in conjunction with juvenile mortality effects. Therefore, stochastic environmental events such as drought and fire may be the only natural incidence of population regulation to occur in these systems, where populations continue to grow exponentially and there is no evidence of density-dependence (as in the case of many small, fenced reserves in South Africa). In large, open, high-density systems in other parts of southern Africa, density dependence acts strongly on female fecundity and causes low levels of juvenile mortality in areas of local population aggregation. Therefore, in isolation, natural juvenile mortality is unlikely to regulate African elephant populations, but in conjunction with decreased female fecundity in response to density-dependent feedbacks and stochastic environmental events, population regulation may occur. The management of long-lived megaherbivore species with similar demographic drivers must include an appreciation of the complexity of population response to manipulation of mortality or fecundity effects. Small changes can potentially result in large shifts in population dynamics. Further insight into the mechanisms driving these processes will allow sound scientific support of megaherbivore management decisions to be made throughout Africa. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2008.
104

Thermoregulation in free-ranging African-endemic small mammals : the rock elephant shrew, Elephantulus myurus and the lesser bushbaby, Galago moholi.

Mzilikazi, Nomakwezi. January 2005 (has links)
Endothermy in birds and mammals is invariably associated with homeothermy. However, homeothermy can only be maintained if sufficient energy is obtained to meet the animals' maintenance budget. In mammals, daily torpor and hibernation have evolved to conserve energy when energy inputs from the environment are insufficient to meet maintenance requirements. Several studies have suggested that daily torpor and hibernation do not represent distinct physiological responses but are components of a continuum of heterothermy. Under laboratory conditions, even within phylogenetically ancient eutherian mammals, such as elephant shrews, it is unclear whether daily torpor or hibernation is used. Furthermore, an interpretation of the torpor patterns observed under laboratory conditions is complicated by the fact that torpor patterns often differ between laboratory and free-ranging conditions. Within the more recent mammal lineages, torpor has been observed in strepsirrhine primates. The occurrence of torpor in strepsirrhines is interesting as it pertains to arguments relating to the colonization of Madagascar by strepsirrhine primates as well as implications for human physiology. The first aim of this study was to investigate and quantify parameters that characterize torpor in a phylogenetically ancient eutherian mammal (Macroscelidae: Elephantulus myurus) under free-ranging conditions. This was done mainly to resolve whether daily torpor and hibernation were physiologically discrete responses. The second aim was to investigate torpor occurrence in a more recently evolved eutherian mammal (Primates: Galago moholi). The objective was to gain insights into the phylogenetic distribution of torpor and to provide a physiological verification of torpor occurrence in a mainland strepsirrhine relative to arguments about the colonization of Madagascar. I measured body temperatures in three monthly cycles between May 2001 - May 2002 in 22 free-ranging E. myurus. I recorded a total of 467 torpor bouts throughout the study period. The elephant shrews were capable of daily torpor throughout the year, with torpor most prevalent during winter and correlated with ambient temperature, photoperiod and invertebrate abundance. Only two torpor bouts were observed during summer. I suggest that although torpor use was most prevalent during winter, summer torpor might also be important for energy conservation in this species during drought years. This highlights the need for long-term physiological data in free-ranging animals. The mean torpor Tbmin and the mean bout length for the whole year were in the range expected for daily heterotherms. However, there was some marginal overlap with hibernation characteristics; a few torpor bouts were longer than 24 hrs in duration indicating that the animals were capable of opportunistically extending torpor bouts longer than 24 hours in response to unpredictable energetic shortfalls. Tbmin also decreased below 10°C. However, a consideration of behavioural and ecological factors argues against hibernation in E. myurus. Instead, these results support the idea of a physiological continuum for heterothermy. A return to normothermic body temperatures requires considerable energy expenditure, and this is perceived to be one of the major disadvantages of torpor. E. myurus offset the high cost of arousal from low body temperatures by using exogenous passive heating. This is achieved by coupling of the timing of arousal with ambient temperature cycles. Laboratory studies that quantify torpor energetics are usually conducted under constant temperature conditions and are likely to underestimate the energetic benefits accrued through the use of ambient temperature cycles during arousal. Torpor is often displayed during the animal's rest phase. However, nocturnal small mammals that utilize passive heating to assist arousal from torpor may enter torpor during the nighttime, thus effectively advancing the onset of the rest phase. I investigated the functional significance of daily and seasonal rhythms of body temperature in normothermic and torpid free-ranging E. myurus. Daily patterns of Tb, in normothermic E. myurus suggested polyphasic Tb patterns that nevertheless indicated a rest phase coincident with the daytime. I suggested that the principal benefit of a flexible daily rhythm of Tb, is that it facilitated torpor use during the nighttime and arousal by passive exogenous heating using ambient temperature cycles. It has been suggested that the evolution of endothermy precluded the need for homeothermic mammals to be sensitive to Ta cycles because they could maintain physiological function despite fluctuations in the ambient temperature. Elephant shrews utilize passive heating and provide excellent models with which to investigate whether mammals can entrain their body temperature rhythms to ambient temperature cycles. I experimentally tested whether food restricted E. myurus can entrain torpor cycles to shifts in the Ta cycle while holding the light-dark cycle constant. Food restriction and short photoperiod were only sufficient to induce torpor in E. myurus if photoperiod and Ta, cycles are in phase with each other. Shifting the cold T, into the photophase prevented the expression of torpor. I concluded that the body temperature rhythm is most probably tightly coupled with the photoperiod cycle and that although Ta and photoperiod usually act synergistically in nature, photoperiod is probably the stronger zeitgeber. The evolution of endothermy is thought to have been facilitated by the advent of endothermic energy sources such as brown adipose tissue (BAT), the principal site of nonshivering thermogenesis (NST). Rock elephant shrews are amongst the smallest members of the Afrotheria, the most basal of the eutherian lineage. I determined whether the phylogenetic placement of E. myurus and reliance on passive heating might result in a decreased capacity for NST relative to other eutherians. I investigated the capacity for NST in winter acclimated E. myurus by measuring the thermogenic response to noradrenalin (NA) injection. I used phylogenetically independent analyses to compare E. myurus NST capacity with other eutherians. E. myurus had an NST capacity that was no different from other eutherian mammals. Although they displayed a NST capacity that was 74% of that expected on the basis of body mass, this value was not significantly different from phylogenetically independent allometric predictions. Although heterothermy is almost always considered in the context of how the environment affects function , its use may offer insights into topics such as island biogeography and species dispersal. For example, there have been suggestions that heterothermy might have played an important role in the successful colonization of Madagascar by strepsirrhine primates. To my knowledge no studies exist as yet that provide a physiological verification of this suggestion. Currently no data exist on thermoregulation and heterothermy in any free-ranging African strepsirrhines. The lesser bushbaby, Galago moholi, is a small nocturnal strepsirrhine primate that experiences severe winters and drastic food reduction during winter and is a candidate employer of torpor. I measured body temperatures of 11 free-ranging lesser bushbabies, Galago moholi, captured at different times between February 2002 - September 2003. I did not record any incidents of heterothermy throughout the study period. Why does G. moholi not employ heterothermy? I consider several alternatives; phylogenetic placement, physiological and ecological factors that might preclude the use of torpor in this species. I suggest that the breeding pattern observed in G. moholi obviates torpor use whilst increasing fecundity, which would be adaptive if the animals are confronted with high predation risks. Much is currently known about the advantages of torpor use. This study highlights the need to consider and investigate those physiological, ecological and phylogenetic factors that might constrain species from utilizinq heterothermy. Furthermore, this study highlights the potential for thermoregulatory studies to offer insights into topics as widely separated as evolution of endothermy to species dispersal and island biogeography. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
105

Habituation to Auditory Stimuli by Captive African Elephants (Loxodonta Africana)

Goodyear, Sarah Elizabeth 01 May 2015 (has links)
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.
106

What drives the seasonal movements of african elephants (Loxodonta africana) in Ithala Game Reserve?

Muller, Kayleigh. January 2013 (has links)
The changes in plant quality and availability in space and time present a substantial problem to mammalian herbivores. As a result, these herbivores need to alter their foraging behaviour to maximize their energy gain at both small (plant level) and large (landscape level) scales. A megaherbivore, the African elephant (Loxodonta africana), has been shown to be selective in its foraging choices at both of these scales. Furthermore, the ratio of palatability:defences (e.g. fibre and total polyphenols) has been highlighted as an important determinant of habitat selection in elephants. The elephants in Ithala Game Reserve (IGR) frequently leave IGR during the wet season and forage outside the reserve. However, they predominantly feed on the low-nutrient granite soils of the reserve and return to a high-nutrient area with dolerite soils during the dry season. In an attempt to understand these seasonal movements, I focused on how the small-scale foraging decisions of the elephants lead to large-scale seasonal movements in IGR, KwaZulu-Natal. Plant availability was determined seasonally for seven target species across four areas in the reserve. Crude protein, fibre, energy and total polyphenols as well as the ratios of palatability:digestion-reducing substances were analysed in the wet and dry seasons. All factors and their interactions were significant in a MANOVA. Consequently, I employed a dimension-reducing Principal Components Analysis (PCA) to better understand the factors of greatest importance. The PCA highlighted four of the six most important factors to be the ratios of palatability:digestion-reducing substances. The other two important variables were total polyphenols (negative effect) and crude protein (positive effect). At small spatial scales, I found that the elephants were selective in their decisions, especially during the dry season. For example, the increased inclusion of the principal tree species Acacia nilotica from 2.9% in the wet season to 39.3% during the dry season appears to be a result of a decline in total polyphenols and fibre during the dry season. At large spatial scales, the elephants moved back into IGR from the low-nutrient granite soils in the east in response to an increase in forage quality in the west as the quality declined in the east at the same time. However, it is unclear as to why the elephants are leaving the reserve during the wet season. Some possible explanations for this are discussed.Key-words: acid detergent fibre, crude protein, Loxodonta africana, neutral detergent fibre, total polyphenols, plant part quality. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
107

The conservation and management of freshwater fishes in the Greater Addo Elephant National Park /

Traas, Graham Ronald Louis. January 2009 (has links)
Thesis (M.Sc. (Ichthyology & Fisheries Science)) - Rhodes University, 2009.
108

The effect of elephant utilisation on the Sterculia rogersii and Adansonia digitata populations of the Kruger National Park

Kelly, Henry Lyle Patrick. January 2000 (has links)
Thesis (M. Sc.)--University of Pretoria, 2000. / Title from PDF t.p. (viewed on July 17, 2006). Includes bibliographical references (p. 118-122).
109

An assessment of perceived crop damage in a Tanzanian village impacted by human-elephant conflict and an investigation of deterrent properties of African elephant (Loxodonta africana) exudates using bioassays

Karimi, Rebekah R. Schulte, Bruce A. January 2009 (has links) (PDF)
"A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Title from PDF of title page (Georgia Southern University, viewed on June 19, 2010). Bruce A. Schulte, major professor; Lissa M. Leege, J. Michelle Cawthorn, committee members. Electronic version approved: December 2009. Includes bibliographical references (p.76-78).
110

La région de l’oreille osseuse chez les Proboscidea (Afrotheria, Mammalia) : anatomie, fonction, évolution / The ear region of the Proboscidea (Afrotheria, Mammalia) : anatomy, function, evolution

Schmitt, Arnaud 04 October 2016 (has links)
Les éléphants font partie des rares mammifères capables d’entendre les infrasons et leur comportement locomoteur est unique. Ces singularités correspondent à des spécialisations de leurs organes sensoriels contenus dans l’oreille interne : la cochlée (audition) et le système vestibulaire (locomotion). Alors que la diversité actuelle des proboscidiens est très faible (trois espèces), ce groupe a été bien plus diversifié pendant les 60 millions d’années qui composent son histoire. Cette thèse étudie pour la première fois de façon complète la morphologie et la fonction de la région de l’oreille (périotique, labyrinthes osseux et membraneux) d’éléphants actuels grâce aux techniques CT scan 3D. De plus, les périotiques de quatorze genres de proboscidiens fossiles sont décrits afin de documenter l’évolution de ce complexe anatomique au sein de cet ordre de mammifères. Les résultats montrent que certains caractères de l’oreille sont très variables au niveau spécifique. Notre analyse inclut les plus anciens proboscidiens connus et suggère que la morphologie de la région otique a évolué graduellement pendant la première moitié de l’histoire évolutive du groupe et que le morphotype moderne éléphantin est déjà acquis chez les Deinotheriidae et généralisé chez les éléphantimorphes. Les inférences sur la locomotion et l’audition des taxons fossiles confirment ces observations. Ce travail permet ainsi de lever le voile sur l’évolution d’une région anatomique majeure, jusque-là méconnue chez un groupe emblématique de mammifères. / Elephants are among the few mammals able to hear infra-sounds, and they display a unique locomotor behavior. It corresponds to specializations of their sensory organs contained in the inner ear: the cochlea (audition) and the vestibular system (spatial orientation). While only three species are living today, they were a much more diverse group found in five continents and with a 60 Ma-long history. We provide here the first comprehensive morphological and functional study of the ear region (petrosal, bony and membranous labyrinths) of extant elephants using 3D CT scan techniques. Additionally, we describe and compare the petrosals of fourteen extinct proboscidean genera in order to shed light on the evolution of this anatomical complex in the Proboscidea. The results show that some features of the petrosal and bony labyrinth of extant elephants - such as the number of turns of the cochlea – display a noticeable level of intra-specific variability. Our analysis includes the earliest-known proboscideans and suggests that the petrosal and bony labyrinth morphology evolved gradually during the first half of the proboscidean evolutionary history, but also that the modern morphotype exhibited in elephants was probably already acquired in deinotheriids and generalized in elephantimorphs. Functional inferences on the locomotor behavior and the audition of extinct proboscideans confirm these observations. This work hence provides new insights on the evolution of a major anatomical region hitherto poorly known in an emblematic group of mammals.

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