The study assesses process-morphology relationships on 27 debris slopes of an Arctic periglacial environment. A systematic sampling procedure is followed to obtain profile angle and debris size, shape and orientation for each slope. A rigorous test design to analyze size and shape variation has high statistical power and yields reliable results. Vector analysis is employed in the study of debris orientations, while non-parametric tests are performed on geometric parameters. Supplementary studies are made on rockfall accumulation and subsurface meltwater flow. Responses of slope geometry and debris characteristics to three major process groups are independently analyzed and compared in four selected localities, and the nature and effects of each process in the study area are presented. A discussion of interactions between the processes, geometry and debris concludes with a relative assessment of each process. / Thesis / Master of Science (MS)

No description available.

The main purpose of this thesis is to develop a search strategy for space debris that are in the geosynchronous orbit (GEO) region. The search strategy is not an effort to find the object initially but rather if found one time to aid in finding it again within a small time frame. This was a request from NASA Johnson Space Center Orbital Debris Program Office through the MODEST, Michigan Orbital Debris Survey Telescope, program. A single definitive search pattern was not found, however depending on the COEs of the orbit specific search strategy can be employed. These search strategies are far from perfect and can be improved upon with more rigorous testing as well as a larger data sample. Another goal is to look for correlation between the orbital parameters and the errors in the predicted right ascension (RA) and the declination (DEC). This was accomplished by varying the different orbital parameters by ±10% individually while holding the other parameters constant. This showed some correlation existed between some parameters and their errors, in particular there was correlation between a variation in right ascension of ascending node (RAAN) and the value of RAAN itself. The correlation found was that with the higher the value of RAAN the larger the RMS error.

The purpose of this thesis is to create a search strategy to find orbital debris when the object fails to appear in the sky at its predicted location. This project is for NASA Johnson Space Center Orbital Debris Program Office through the MODEST (Michigan Orbital Debris Survey Telescope) program. This thesis will build upon the research already done by James Biehl in “Formulation of a Search Strategy for Space Debris at GEO.” MODEST tracks objects at a specific right ascension and declination. A circular orbit assumption is then used to predict the location of the object at a later time. Another telescope performs a follow-up to the original observation to provide a more accurate orbit predication. This thesis develops a search strategy when the follow-up is not successful. A general search strategy for finding space debris was developed based on previous observations. A GUI was also generated to find a search strategy in real-time for a specific object based upon previous observations of that object. Search strategies were found by adding a 2% mean random error to the position and velocity vectors. Adding a random error allows for finding the most likely location of space debris when the orbital elements are slightly incorrect. A bivariate kernel density estimator was used to find the probability density function. The probability density function was used to find the most probable location of an object. A correlation between error in the orbital elements and error in right ascension and declination root mean square (RMS) error was investigated. It was found that the orbital elements affect the RMS error nonlinearly, but the relation between orbital element and error depended on the object and no general pattern was found. It was found that how long after the original object was found until the follow-up was attempted did not have a large impact on the probability density function or the search strategy.

To aid in forest management, various approaches using Geographic Information Systems (GIS) have been used to identify the spatial distributions of relative slope instability. This study presents a systematic evaluation of three common slope instability modeling approaches applied in the Blue Ridge Mountains of Virginia. The modeling approaches include the Qualitative Map Combination, Bivariate Statistical Analysis, and the Shallow Landsliding Stability (SHALSTAB) model. Historically, the qualitative nature of the first model has led to the use of more quantitative statistical models and more deterministic physically-based models such as SHALSTAB. Although numerous studies have been performed utilizing each approach in various regions of the world, only a few comparisons of these approaches have been done in order to assess whether the quantitative and deterministic models result in better identification of instability. The goal of this study is to provide an assessment of relative model behavior and error potential in order to ascertain which model may be the most effective at identifying slope instability in a forest management context. The models are developed using both 10-meter and 30-meter elevation data and outputs are standardized and classified into instability classes (e.g. low instability to high instability). The outputs are compared with cross-tabulation tables based on the area (m²) assigned to each instability class and validated using known locations of debris flows. In addition, an assessment of the effects of varying source data (i.e. 10-meter vs. 30-meter) is performed. Among all models and using either resolution data, the Qualitative Map Combination correctly identifies the most debris flows. In addition, the Qualitative Map Combination is the best model in terms of correctly identifying debris flows while minimizing the classification of high instability in areas not affected by debris flows. The statistical model only performs well when using 10-meter data while SHALSTAB only performs well using 30-meter data. Overall, 30-meter elevation data predicts the location of debris flows better than 10-meter data due to the inclusion of more area into higher instability classes. Of the models, the statistical approach is the least sensitive to variations in source elevation data. / Master of Science

Measurements of substrate composition, cover characteristics, and trout populations and biomass were made at a total of ten sites on South Fork Mills River and one of its tributaries. Poplar Creek, in 1975 and 1976. Besides providing cover debris accumulations generally caused a reduction in stream velocity with accompanying deposition of smaller substrate types. Removal of debris caused a shift to larger substrates. A multiple regression treatment of the physical characteristics and trout populations indicated that regression models relating the presence of debris and large substrates (interpreted here as increasing water flow) to trout populations were the only ones significant at the .1 level and accounted for 58% of the variation in trout biomass. The presence of debris could account for none of the variations in trout numbers. Areas containing debris were found to contain populations made up of larger fish than areas without debris. The effects of debris removal were not clear cut, however, there was a trend towards reduced biomass but not necessarily reduced number of trout. This was probably due to decreases in cover, which made the areas less desirable for large trout, but increased flows which favored smaller trout. / Master of Science

Coarse woody debris (CWD) is an important habitat component for wildlife, fish, and plants and is important in nutrient cycling and soil formation. Knowledge of the volume, distribution, and use of CWD across Virginia would be useful to forest managers modeling nutrient budgets in southeastern forests and is important to wildlife management efforts. Knowledge of the effectiveness of informational brochures and cooperative learning activities/presentations at influencing public perception of CWD is important to program design and evaluation efforts in teaching and extension. The objectives of this study were to quantify the relationship between forest cover type and CWD volume, correlate CWD volume with small mammal and bird activity, distribute information on the advantages and disadvantages of CWD using informational brochures and cooperative learning activities/presentations, and compare the effectiveness of such teaching techniques at influencing public perception of CWD. The volume and wildlife use of CWD was assessed within 12 mature second-growth stands in Virginia. Volume of CWD was measured using fixed-area plots. Use of CWD by small mammals and birds was assessed by noting bodily, foraging, or movement evidence. Pre- and post-survey instruments were used to evaluate how perceptions were altered in first year college students who either reviewed an informational brochure or participated in a cooperative learning activity/presentation. Results suggested that the management of CWD for wildlife was most needed in southeastern Virginia where CWD volumes were lowest and that the value of CWD for wildlife was best conveyed through cooperative learning activities/presentations and may be important to landowner education efforts. Results suggested that management efforts to increase CWD volumes in Virginia should focus on coniferous dominated stands where CWD volumes were lowest. Such a finding, combined with the knowledge that the value of CWD was best conveyed through presentations, suggests that landowners of coniferous woodlots could be effectively educated with presentations. Given that brochures were more effective for females than males, brochures addressing natural resource issues might be the most appropriate, cost effective method of education at events that target female audiences. Knowledge gained from this study that CWD management for wildlife would be most appropriate in western Virginia where CWD was most used by wildlife for travel and that presentations were most effective at reaching suburban participants may be important to outreach program design efforts. Regardless of academic major, presentations were more effective at generating positive attitudes toward CWD. The results of this study suggest that the choice between informational brochures and presentations for influencing public perceptions of CWD will likely be influenced by the demographics of the target audience and the relevance of the topic locally. / Master of Science

The West Elk Breccia has been studied since the late 1800’s with many interpretations regarding its origin. One unrecognized possibility is that parts of it are debris-avalanche deposits. This study has recognized evidence for this interpretation at three scales: volcano scale, outcrop scale, and intra-outcrop scale. At the volcano scale, a scarp in the old volcano reveals underlying Mesozoic bedrock, suggesting sector collapse. At the outcrop scale, megablocks of the original edifice, up to hundreds of meters in length, have atypical orientations and are surrounded by a gravel matrix. At the intra-outcrop scale, jigsaw-fit fracturing and rip-up clasts are common in distal deposits, which are documented in analogous debris-avalanche deposits. Similar to the debris-avalanche deposit at Mt. Shasta, medial-to-distal-matrix volcaniclast content decreases by 23%; Paleozoic and Mesozoic clasts increase by 5%; and the size of megablocks decreases. The geochemical and petrographic signatures reveal breccia blocks composed of pyroxene-andesite, a more silicic matrix facies, and the andesitic-to-dacitic East Elk Creek Tuff, all compositions that corroborate previous work on this northern extension of the San Juan volcanic field. Measured sections in the 100-km² study area allow for an estimation of total formation volume of approximately 8.5 km3.

Landscapes are comprised of multiple ecosystems shaped by disturbances varying in severity and source. Moderate disturbance from weather, pathogens, insects, and age-related senescence, in contrast to severe disturbances that fell trees, may increase standing woody debris and alter the contribution of coarse woody debris (CWD) to total ecosystem respiration (RE). However, woody debris dynamics are rarely examined following moderate disturbances that substantially increase standing dead wood stocks. We used an experimental manipulation of moderate disturbance in an upper Great Lakes forest to: 1) examine decadal changes in CWD stocks through a moderate disturbance; 2) quantify in situ CWD respiration during different stages of decay for downed and standing woody debris and; 3) estimate the annual contribution of CWD respiration to the ecosystem C balance through comparison with RE and net ecosystem production (NEP). We found that the standing dead wood mass of 24.5 Mg C ha-1 was an order of magnitude greater than downed woody debris stocks and a large source of ecosystem C flux six years following disturbance. Instantaneous in situ respiration rates from standing and downed woody debris in the earliest stages of decay were not significantly different from one another. Independently derived estimates of ecosystem CWD respiration of 1.1to 2.1 Mg C ha-1 yr-1 six years following disturbance were comparable in magnitude to NEP and 12.5 % to 23.8 % of RE, representing a substantial increase relative to pre-disturbance levels. Ecosystem respiration and NEP were stable following moderate disturbance even though ecosystem CWD respiration increased substantially, suggesting a reduction in the respiratory C contribution from other sources. We conclude that CWD is an essential component of the ecosystem C balance following a moderate forest disturbance.

O objetivo do presente estudo foi avaliar, quantitativa e qualitativamente, por meio de microtomografia computadorizada, o percentual de volume e de redução de debris dentinários acumulados (DDA) no sistema de canais radiculares com istmos de raízes mesiais de molares inferiores submetidos à: irrigação por pressão apical positiva; irrigação ultrassônica passiva; finalização do preparo com Self-Adjusting File e finalização do preparo com XP-endo Finisher. Quarenta raízes mesiais de molares inferiores, com curvatura moderada, e presença de dois canais mesiais com istmo único e contínuo verificada por escaneamento em microtomográfo, foram selecionadas. Os canais foram preparados pela técnica de instrumentação reciprocante (WaveOne Small e Primary). Em seguida, a composição dos grupos experimentais foi realizada por meio da técnica de amostragem estratificada, de acordo com o protocolo de irrigação final ou de finalização de preparo biomecânico, em quatro grupos (n=10): Pressão Apical Positiva (PAP), Irrigação Ultrassônica Ativa (IUP), Self-Adjusting File (SAF), e a XP-endo Finisher (XPF). Os protocolos foram realizados durante 2 minutos com 5,5 mL de hipoclorito de sódio a 2,5%. Os espécimes foram submetidos aos exames microtomográfico inicial, após o preparo e após os protocolos de irrigação final ou de finalização do preparo para análise de DDA. A porcentagem de volume e redução de DDA após os protocolos de irrigação final ou de finalização do preparo biomecânico foram comparados estatisticamente entre os grupos por meio de ANOVA e pós-teste de Tukey, com nível de significância de 5%. Foi possível observar redução de DDA após os protocolos de irrigação final e de finalização do preparo biomecânico em todos os grupos avaliados. Os grupos IUP e XPF apresentaram as menores médias de volume e de percentual de volume (%vol) de DDA (0,05±0,06mm³ e 0,61±0,75%; e 0,08±0,09mm³ e 0,81±1,03%, respectivamente) comparados aos grupos PAP e SAF (0,36±0,13mm³ e 3,73±1,59%; e 0,47±0,23mm³ e 4,31±1,87%, respectivamente) (p<0,05). Ainda, o percentual de redução de DDA foi maior nos grupos IUP e XPF (94,05±7,21% e 89,67±10,96%, respectivamente) quando comparados aos grupos PAP e SAF (45,74±15,76% e 41,26±9,96%, respectivamente) (p<0,05). Não houve diferença estatística entre os grupos IUP e XPF; e entre os grupos PAP e SAF (p>0,05). Qualitativamente, os DDA remanescentes foram localizados principalmente no terço apical após o protocolo com IUP; no terço cervical após protocolo com XPF e nos terços médio e apical após protocolos com PAP e SAF. Conclui-se que os protocolos de irrigação ultrassônica passiva e de finalização do preparo com XP-endo Finisher apresentaram maiores remoções de debris dentinários do sistema de canais radiculares com istmos comparados aos protocolos de irrigação por pressão apical positiva e de finalização de preparo com SAF. / The aim of this study was to evaluate, quantitatively and qualitatively, the percent volume and percent reduction of accumulated hard-tissue debris (AHTD) from root canal system with isthmuses of mesial roots of mandibular molars subjected to different final irrigation and final shaping protocols, using micro-computed tomography (micro-CT) analysis. Forty mesial roots of mandibular molars with moderate curvature and two mesial canals with a single and continuous isthmus detected by micro-CT scanning were selected. The canals were prepared by reciprocating instrumentation technique (WaveOne Small and Primary). Then, the composition of the experimental groups was performed by a stratified sampling method, resulting in four groups (n=10), according to the final irrigation or final shaping protocol: Apical Positive Pressure (APP), Passive Ultrasonic Irrigation (PUI), Self-adjusting File (SAF) and XP-endo Finisher (XPF). The protocols were performed with 5.5 mL of 2.5% NaOCl per canal during 2 minutes. The specimens were subjected to preoperative and following preparation, final irrigation or final shaping micro-CT scanning for AHTD analysis. The percent volume and percent reduction of AHTD after final irrigation or final shaping were statistically compared among groups using ANOVA and post hoc Tukey test with a 5% significance level. It was observed a reduction in the percentage of AHTD after final irrigation or final shaping in all groups. The PUI and XPF groups showed the lowest mean of volume and percent volume (%vol) of AHTD (0.05±0.06mm³ and 0.61±0.75%; and 0.08±0.09mm³ and 0.81±1.03%, respectively) when compared with APP and SAF groups (0.36±0.13mm³ and 3.73±1.59%; and 0.47±0.23mm³ and 4.31±1.87%, respectively) (p<0.05). Furthermore, the percent reduction of AHTD was greater in PUI and XPF groups (94.05±7.21% and 89.67±10.96%, respectively) compared with APP and SAF groups (45.74±15.76% and 41.26±9.96%, respectively) (p<0.05). No statistically significant differences were found when comparing PUI and XPF groups or APP and SAF groups (p>0.05). Qualitatively, the remaining DDA were mainly located in the apical third after the protocol with IUP; the cervical third after protocol XPF and in the middle and apical thirds after protocols PAP and SAF. It may be concluded that the passive ultrasound irrigation and final shaping with XP-endo Finisher protocols showed greater AHTD reduction from root canal system with isthmuses of mesial roots of mandibular molars than apical positive pressure and final shaping with SAF.