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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.
1

Perceptions of a guided wilderness trail

Raimondo, John P 27 September 2023 (has links) (PDF)
Personal recorded Interviews with past and present guides of the Wilderness Leadership School were used to identify four Important factors in a successful guided wilderness trail. Using postal questionnaires, guides and members of the Wilderness Leadership School were asked to rank nine trail scenarios. The technique of conjoint analysis yielded the relative importance, as perceived by the guides and trialists, of each of the four factors. It was shown that the most important attribute for both groups of respondents was how the trails interacted with one another. Next in importance was an increase in awareness, by the trialists of the if interdependence environment. This was followed by the personality of the guide and finally signs of modern man's impact in the wilderness area. There was an important difference in percept f on between the guides and the trails; the trails firsts placed more emphasis on the group interact ion and wilderness on an increase in awareness. There were also differences in perception between the different category of guides and trail fists. of' activities and related experiences relative to a successful trail are included in the report.
2

The Influence of Layout on Degradation of the Appalachian Trail

Meadema, Peter Fletcher 13 November 2018 (has links)
This research investigates the influence of layout and design on the severity of trail degradation. Previous trail studies have been restricted by relatively small study areas which provide a limited range of environmental conditions and therefore produce findings with limited applicability; this research improves on this limitation by analyzing a representative sample of the Appalachian Trail with significant ecological diversity. Most trail science studies have also focused on a singular form of trail degradation, whereas this study investigates trail soil loss, widening and muddiness, providing a more cohesive analysis and revealing interrelationships between trail degradation processes. ANOVA testing of the mean values of three trail impact indicators for trail transects within several trail layout frameworks confirms the broad relevance of core trail design principles, specifically the sustainability advantages of trails with low grades and side-hill alignments. Findings also reveal the importance of landform grade in determining the susceptibility of trails to degradation and the influence of routing decisions; these relationships have received relatively little attention in the literature. The results also reveal several methodological considerations for trail alignment metrics and trail impact indicators. / Master of Science / Natural surfaced trails are an essential infrastructure component in parks and protected natural areas. They provide transportation routes through otherwise undeveloped areas and outdoor recreation opportunities for hikers, mountain bikers, and equestrians. Over time, recreational use and natural processes such as rainfall can lead to negative ecological impacts that damage trail treads in ways that impair their utility for visitors and require costly repairs. Environmental factors like unstable soils or extreme precipitation can make trails more susceptible to degradation. However, sustainable trail layouts and effective maintenance can reduce the rate and severity of degradation. This research investigates the influence of trail layout on three chief forms of trail degradation: trail soil loss, muddiness, and widening. Many trail science studies have occurred in small protected natural areas where the limited range of represented environmental conditions reduces the applicability of their findings in dissimilar settings. This study investigates a dataset from a large and ecologically diverse representative sample of the entire Appalachian Trail from Georgia to Maine which significantly broadens the relevance of its findings. Furthermore, many previous trail studies have focused on single forms of trail degradation whereas this study which investigates three, which provides a more cohesive analysis and reveals interrelationships between impacts. Findings confirm the broad pertinence of core sustainable trail design principles, specifically the benefits of low trail grades and side-hill alignments, and suggests that landform grade is an important factor which has received little attention in the literature. The study also revealed several methodological improvements and considerations which may be useful to trail scientists and practitioners.
3

Modulation of tumor necrosis factor related apoptosis-inducing ligand (trail) receptors in a human osteoclast model in vitro

McManus, Stephen January 2010 (has links)
We have previously shown that osteoclasts (OCLs) from multiple myeloma (MM) specimens vary from healthy OCLs in their expression of the TRAIL receptors. TRAIL (TNF-Related Apoptosis-Inducing Ligand), a member of the TNF superfamily, has been shown to induce apoptosis in cells by binding receptors DR4 and DR5, but not DcR1 and DcR2, its decoy receptors, which lack the necessary internal death domain. The observed modulation of these receptors may confer a resistance to apoptosis in the MM environment, and could be related to the cytokine pattern that primarily involves the resorption promoting Receptor Activator of NF-[kappa]B Ligand (RANKL) and Macrophage Inflammatory Protein 1 (MIP-1[alpha]). The aim of our study was to determine which cytokines present in the disease might be responsible for this modulation. In long term cultures of OCL precursors from cord blood in the presence of M-CSF and RANKL, multinucleated cells (MNCs) that express OCL markers form, and can resorb bone. Through immunocytochemistry we showed that these MNCs can express all four TRAIL receptors. By stimulating with various cytokines (RANKL, MIP-1[alpha], Transforming Factor [bêta] (TGF[bêta]), osteoprotegerin (OPG), TRAIL), and parathyroid hormone (PTH) in OCL cultures, we were able to observe receptor modulation at the mRNA level using real time PCR, the protein level using Western blot analysis, and cell surface expression via immunocytochemistry. To determine if these changes translated to a difference in resistance to apoptosis, cells treated with [with] apoptosis-inducing levels of TRAIL after 5 days of stimulation with the selected cytokines were evaluated via TUNEL to quantify apoptosis. While no correlation has yet been established between the observed receptor modification and apoptosis induction, sample size is a factor, and further tests will be performed. Our results suggest the possibility that TRAIL receptor modification is induced by multiple cytokines present in bone diseases, capable of altering both the susceptibility and resistance pathways in osteoclasts. By potentially prolonging the lifespan of the OCL, these regulatory influences may ultimately be contributory factors to the augmentation of resorption in the micro-environment of bone resorptive diseases like multiple myeloma, Paget's disease of bone, or osteoporosis.
4

Exploring the Social, Environmental and Economic Aspects of Trail Surfacing Decisions

Giles, Andrew January 2002 (has links)
Visitor activities in parks often have a heavy impact on the soil, vegetation, water and wildlife. In front country areas, the most extreme damage is concentrated on and adjacent to recreational trails. Aside from controlling the numbers, activities and behaviours of trail users, managers may choose to make trails more resistant to impact through surfacing. Unfortunately, surfacing may have negative influences on park visitors' enjoyment of trails by limiting access or detracting from the primitive setting. In addition, some surfaces may be ineffective in certain environmental conditions such as wet ground or steep slopes. Finally, the wide variety in construction and maintenance costs may make some surface types economically unfeasible. The goals of this research are to investigate the role of trail surfacing in the management of impacts from outdoor recreation; to develop better understanding of the social, economic and environmental aspects of trail surfacing decisions; and to explore a comprehensive framework for incorporating these three factors in trail management. It is hoped that this research can assist park managers in selecting surfacing options to reduce visitor impact without excessively compromising recreational experience or organizational limitations, such as financial resources. In addition to a comprehensive review of literature on visitor impact management on trails and surfacing techniques, this research employs three methods to further investigate the social, environmental and economic aspects of trail surfacing: a trail user survey, manager survey and trail condition assessment. The trail user survey was conducted at two well-used natural areas in southwestern Ontario, Canada: Presqu'ile Provincial Park and Belfountain Conservation Area. Surveys at each area explored trail users' perceptions and preferences of trail surfacing techniques in late summer 1999. The managers' survey provided insight into organizational approaches to surfacing, including construction cost and observations on recreational or environmental effectiveness. Finally, the trail condition assessment explored an approach to determining environmental effectiveness of trail surfacing techniques, but was limited by the physical and recreational variation between trails. Seven recommendations for trail managers are presented, tying in several conceptual frameworks of visitor impact management and trail surfacing decisions developed in the thesis. First, trail managers are recommended to develop a full understanding of trail design principles and alternative visitor impact management techniques. If surfacing is selected as the best impact management technique, trail managers should obtain as much information on user characteristics, environmental conditions and organizational limitations as possible. Despite the benefits and drawbacks for all surfaces, road base gravel (or angular screenings with fines) merits special attention as an excellent surface, while asphalt and concrete are not recommended for front country, semi-primitive recreation. Finally, trail managers are encouraged to share information on surfacing more freely and open surfacing decision processes to affected trail users. Overall, trail managers are provided with an approach to surfacing decisions that considers the social, environmental and economic aspects of trail surfacing, with the goal of working toward more enjoyable, environmentally responsible and cost-effective trail solutions.
5

Exploring the Social, Environmental and Economic Aspects of Trail Surfacing Decisions

Giles, Andrew January 2002 (has links)
Visitor activities in parks often have a heavy impact on the soil, vegetation, water and wildlife. In front country areas, the most extreme damage is concentrated on and adjacent to recreational trails. Aside from controlling the numbers, activities and behaviours of trail users, managers may choose to make trails more resistant to impact through surfacing. Unfortunately, surfacing may have negative influences on park visitors' enjoyment of trails by limiting access or detracting from the primitive setting. In addition, some surfaces may be ineffective in certain environmental conditions such as wet ground or steep slopes. Finally, the wide variety in construction and maintenance costs may make some surface types economically unfeasible. The goals of this research are to investigate the role of trail surfacing in the management of impacts from outdoor recreation; to develop better understanding of the social, economic and environmental aspects of trail surfacing decisions; and to explore a comprehensive framework for incorporating these three factors in trail management. It is hoped that this research can assist park managers in selecting surfacing options to reduce visitor impact without excessively compromising recreational experience or organizational limitations, such as financial resources. In addition to a comprehensive review of literature on visitor impact management on trails and surfacing techniques, this research employs three methods to further investigate the social, environmental and economic aspects of trail surfacing: a trail user survey, manager survey and trail condition assessment. The trail user survey was conducted at two well-used natural areas in southwestern Ontario, Canada: Presqu'ile Provincial Park and Belfountain Conservation Area. Surveys at each area explored trail users' perceptions and preferences of trail surfacing techniques in late summer 1999. The managers' survey provided insight into organizational approaches to surfacing, including construction cost and observations on recreational or environmental effectiveness. Finally, the trail condition assessment explored an approach to determining environmental effectiveness of trail surfacing techniques, but was limited by the physical and recreational variation between trails. Seven recommendations for trail managers are presented, tying in several conceptual frameworks of visitor impact management and trail surfacing decisions developed in the thesis. First, trail managers are recommended to develop a full understanding of trail design principles and alternative visitor impact management techniques. If surfacing is selected as the best impact management technique, trail managers should obtain as much information on user characteristics, environmental conditions and organizational limitations as possible. Despite the benefits and drawbacks for all surfaces, road base gravel (or angular screenings with fines) merits special attention as an excellent surface, while asphalt and concrete are not recommended for front country, semi-primitive recreation. Finally, trail managers are encouraged to share information on surfacing more freely and open surfacing decision processes to affected trail users. Overall, trail managers are provided with an approach to surfacing decisions that considers the social, environmental and economic aspects of trail surfacing, with the goal of working toward more enjoyable, environmentally responsible and cost-effective trail solutions.
6

Long term operation of engineered anaerobic bioreactors and wetland cells treating zinc, arsenic and cadmium in seepage : results, longevity, cost and design issues.

Duncan, William Fredrick Alexander 30 May 2011 (has links)
At the Trail Smelter, contaminated seepage water is collected and a portion is diverted for treatment to a large pilot-scale wetland system. The design, construction (in stages from 1997 to 2002) and long term sampling (1998-2007) of the wetland system treating high concentrations of zinc, arsenic and cadmium is presented. The final system configuration has been operating year-round since 2002 treating approximately 15,000 L/d. The system is comprised of two vertical upflow anaerobic (compost) bioreactors followed by three horizontal subsurface flow vegetated wetland cells, a slow sand filter and a final holding cell. Operational sampling was done for water quality (metals and various anions), bacterial communities (MPN, PFLA and DGGE) and vegetation (metals content). After several years of operation one of the anaerobic cells was taken apart and rebuilt in 2002. Extensive solid substrate sampling during deconstruction was analyzed for mineralization (SEM/EDS), metals and carbon content (Rock-Eval pyrolysis) to estimate the potential cell life. The system treats seepage with zinc up to 3800 mg/L (average ~ 260 mg/L), arsenic to 3600 mg/L (average ~ 150 mg/L) and Cd to 83 mg/L (average ~ 4.7 mg/L) which are reduced to <0.5 mg/L (<0.02 mg/L for Cd). Vegetation sampling showed variable uptake into exposed plants at much higher levels than control plants. Plant toxicity was experienced in the system. Evapotranspiration and rhizofiltration are the preferred use of plants as opposed to metal hyper-accumulating plants. Bacterial sampling indicated the presence of sulphate reducing bacteria and a diverse anaerobic microbial community throughout the system despite the high metals entering the system. The predicted life of the anaerobic cell by Rock Eval 6 was 18 years with a range from 17 to 21 years, while based on biomass calculations could range from 14 to 34 years. Where wetlands systems can be successfully used, their cost and environmental and social sustainability is very favourable when compared to chemical treatment systems (e.g. lime-dosing systems). Based on author‟s experience at the Trail and other sites, the design issues faced by full scale wetland systems are presented and recommendations made to ensure a successful system. / Graduate
7

Weeds on the Pacific Crest Trail in southwest Oregon : predicting presence and abundance using a Geographic Information System /

Nelson, Peder. January 2006 (has links) (PDF)
Thesis (M.S.)--Southern Oregon University, 2006. / Printout. Includes bibliographical references (leaves 40-46). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.
8

Résistance à l'apoptose induite par TRAIL-R4 : sensibilisation des cellules tumorales par la chimiothérapie ou des mimétiques de TRAIL / TRAIL-R4 mediated resistance to TRAIL induced apoptosis : use of chemotherapy and TRAIL mimetics to overcome it

Morizot, Alexandre 22 October 2010 (has links)
La protéine TRAIL (TNF Related Apoptosis Inducing Ligand) suscite un grand intérêt en thérapie anticancéreuse. Contrairement à la plupart des traitements couramment utilisés en clinique, cette protéine induit sélectivement la mort par apoptose de nombreuses cellules cancéreuses. Cette cytokine exerce son activité cytotoxique en se liant à des récepteurs transmembranaires exprimés à la surface de la cellule cible. Par un jeu d’interactions protéiques, la fixation de TRAIL sur ces récepteurs agonistes (TRAIL-R1 et TRAIL-R2) conduit à l’activation de l’apoptose. L’expression de deux récepteurs antagonistes, TRAIL-R3 et TRAIL-R4, par les cellules cancéreuses, permet aux cellules cibles d’échapper à l’apoptose induite par TRAIL. Nous montrons que ces deux récepteurs font intervenir des mécanismes moléculaires distincts. Leur expression pouvant potentiellement représenter un frein à l’utilisation clinique de TRAIL, nous avons étudié l’effet de la surexpression de l’un d’entre eux, TRAIL-R4 sur l’efficacité des stratégies thérapeutiques associant TRAIL aux chimiothérapies conventionnelles. Les résultats obtenus montrent également que la résistance induite par TRAIL-R4 peut être contournée in vitro et in vivo en associant TRAIL à des agents chimiothérapeutiques. D’un point de vue moléculaire, nous avons montré que la sensibilisation à TRAIL 1) implique une augmentation du recrutement et de l’activation de la caspase-8 au sein du DISC de TRAIL, 2) ne nécessite pas la voie mitochondriale, et 3) est négativement régulée de manière coopérative par c-FLIP, un inhibiteur sélectif de la caspase-8. De manière intéressante, comme les anticorps agonistes actuellement testés en clinique, de petits peptides agonistes de TRAIL-R2, développés en collaboration avec une équipe de chimiste, permettent de contourner la résistance induite par TRAIL-R4, offrant des perspectives thérapeutiques intéressantes. Les récepteurs TRAIL-R3 et TRAIL-R4 sont donc des inhibiteurs de TRAIL. Nos travaux démontrent cependant, que les stratégies associant TRAIL à des agents chimiothérapeutiques, ou l'utilisation d'agonistes TRAIL-R2 permet de contourner la résistance induite par les récepteurs antagonistes de TRAIL et donc d’éliminer ces cellules cancéreuses. / TRAIL (TNF Related Apoptosis Inducing Ligand) is a very promising cytokine for cancer therapy. Contrary to current treatments, this protein is able to selectively kill cancer cells, whilst sparing healthy cells. TRAIL induces apoptosis following binding to one of its two different agonistic membrane receptors, TRAIL-R1 and TRAIL-R2. However, expression of one of its two antagonistic receptors, TRAIL-R3 and TRAIL-R4, on cancer cells can impair cancer cell killing by TRAIL. We have shown that these receptors inhibit TRAIL-induced cell death differentially. As these receptors can represent a brake for the use of TRAIL in cancer therapy, we investigated the effect of the expression of one of them, TRAIL-R4 on the efficacy of the different therapeutic strategies associating TRAIL and conventional therapeutic drugs. We show that acquired resistance to TRAIL following expression of TRAIL-R4 can be overcome in vitro and in vivo by combining TRAIL with chemotherapeutic agents. From a molecular point of view, we could demonstrate that sensitization to TRAIL 1) occurs mainly through an increase of caspase-8 recruitment and activation within the TRAIL DISC, 2) is independent of the mitochondrial pathway and 3) is negatively regulated, in a cooperative manner by c-FLIP, a caspase-8 selective inhibitor. Interestingly, like agonistic receptors currently tested in clinic, small agonistic peptides targeting TRAIL-R2, engineered in collaboration with a team of chemists, afford cancer cell killing regardless of TRAIL-R4 expression, providing novel therapeutic perspectives. TRAIL-R3 and TRAIL-R4 should thus be considered as TRAIL inhibitors. Our results demonstrate however that strategies aiming at combining TRAIL with chemotherapeutic agents or the use of TRAIL-R1 or TRAIL-R2 agonists could be effective treatments to eradicate cancer cells that express TRAIL antagonistic receptors.
9

Survey of Bicycle Trail-Users in New Orleans: Characteristics, Attitudes and Implications for Planning

Judge, Coleen 17 December 2010 (has links)
This thesis focuses on bicyclists using the Jefferson Davis multi-use, off-street trail in the City of New Orleans. Understanding user characteristics and perceptions of bicyclists will help inform planning, policy, and design related to bicycle infrastructure. This thesis uses a review of the relevant literature, intercept surveys of bicyclists, and automatic bicycle counts to understand how user characteristics can influence successful bicycle design, policies, and planning. The user characteristics of the bicyclists on the Jefferson Davis Trail provide us with information on who is using the trail, how often, why, and what users would like to see improved. Planners need to understand the motivations of the current and potential trail users. Making bicycling a safe mode of travel in an urban area involves influencing citizens at both the socialecological level and the travel-behavioral level, providing the culture around bicycling and the facilities available to do so.
10

From the Plains to the Plateau: Indian and Emigrant Interactions During the Overland Trail Migrations

Smith, Christopher 29 September 2014 (has links)
American emigrants frequently encountered Native North Americans during the overland trail migrations of the 1840s-1860s. This study examines the frequency and nature of those interactions in two geographic sections: the first half of the trail, from the Missouri River to the eastern slope of the South Pass of the Rocky Mountains, and the second half, from the western slope of South Pass to Oregon City, Oregon. While the predominant historiography of these migrations has focused on a binary of hostile or non-hostile interactions between Indians and emigrants, the focus on violence has obscured the larger issue of frequent and amicable interactions between emigrants and Indian peoples along the overland route. Factors such as trade, the availability of resources, and cultural differences influenced the nature of these inter-ethnic interactions, which varied from the beginning of the trail on the Plains to the end of the trail on the Columbia Plateau.

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