An emerging non-pharmacological treatment for bone degenerative diseases is whole body vibration (WBV), a mechanical signal composed of low-magnitude, high-frequency (LMHF) vibrations that when applied to bone, have osteogenic and anti-resorptive effects. Currently, the cellular and molecular mechanism underlying the effect of WBV on bone is unclear. In this study, we investigated the response of osteocytes, the putative mechanosensor in bone, under LMHF vibration. As bone cells differentiate from mesenchymal stromal cells (MSCs), we also studied the osteogenic differentiation of rat MSCs in the presence of vibration loading. We found that vibrated osteocytes show gene and protein expression changes suggestive of an anti-osteoclastogenic response, and secrete soluble factors that inhibit osteoclast formation and activity. In contrast, rat MSCs showed moderate to no response to LMHF vibration during osteogenic differentiation. Our data suggest that in vivo effects of LMHF vibration are mediated through mechanosensing and biochemical responses by osteocytes.

The Design of Table-Centric Interactive Spaces, by Daniel J. Wigdor A thesis submitted in partial conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Computer Science, University of Toronto © Copyright by Daniel J. Wigdor, 2008 Direct-touch tabletops offer compelling uses as direct, multi-touch, multi-user displays for face to face collaborative work. As task complexity and group size increase, the addition to the tabletop of multiple, vertical displays allows for more information content, while reducing the need to multiplex the tabletop display area. We dub such systems table-centric interactive spaces. Although compelling, these spaces offer unique challenges. In particular, the displays in such spaces are seen by the users at angles not typically found in combination in other environments. First, the viewing imagery shown on a horizontal display by seated participants means that that imagery is distorted, receding away from the users’ eyes. Second, the sharing of information by users sitting around a horizontal display necessitates that on-screen content be oriented at non-optimal angles for some subset of those users. Third, positioning vertical displays around the table means that some subset of the seated users will be looking at those displays at odd angles. In this thesis, we investigate the challenges associated with these viewing angles. We begin with a examination of related work, including tabletop technology and interaction techniques. Next, we report the results of controlled experiments measuring performance of reading, graphical perception, and ancillary display control under the angles we identified. Next, we present a set of design issues encountered in our work with table-centric spaces. We then review a series of interaction techniques built to address those issues. These techniques are evaluated through the construction and validation of an application scenario. Through these examinations, we hope to provide designers with insights as to how to enable users to take full advantage of ancillary displays, while maintaining the advantages and affordances of collocated table-centric work.

This thesis seeks to analyze the occurrence and behavior of rainfall-triggered landslides in coastal British Columbia. In particular, it focuses on the analysis of landslide temporal and spatial distributions occurrence and their magnitudes, and considers the major factors that influence regional landslide behavior. Implicit in the research is the understanding that the landscape of coastal BC is managed, and that landslides, in addition to occurring naturally may be caused by, and certainly impact, resources that are important to humankind. Underlying each chapter is the rationale that by better understanding the causes of, and controls on landslide occurrence and magnitude, we can reduce the impacts and lower the associated risk. Statistical magnitude-frequency relationships are examined in coastal BC. Observations suggest that landslides in coastal British Columbia tend to a larger size until about 10,000 m2 in total area. At this point larger landslides are limited by landscape controls according to a power law. Probabilistic regional hazard analysis is one logical outcome of magnitude-frequency analysis and a regional mass movement hazard map for Vancouver Island is presented. Physiographic controls on statistical magnitude-frequency distributions are examined using a cellular automata based model and results compare favorably to actual landslide behavior: modeled landslides bifurcate at local elevation highs, deposit mass preferentially where the local slopes decrease, find routes in confined valley or channel networks, and, when sufficiently large, overwhelm the local topography. The magnitude-frequency distribution of both the actual landslides and the cellular automata model follow a power law for magnitudes higher than 10,000 m2 - 20,000 m2 and show a flattening of the slope for smaller magnitudes. The results provide strong corroborative evidence for physiographic limitations related to slope, slope distance and the distribution of mass within landslides. The physiographic controls on landslide magnitude, debris flow mobility and runout behavior is examined using detailed field and air photograph analysis. The role of slope on deposition and scour is investigated and a practical method for estimating both entrainment and runout in the field, as well as in the GIS environment, is presented. Further controls on landslide mobility, including the role of gullies and stream channels, roads and benches and intact forests, are considered. The role of landslides in controlling landscape physiography is also examined. In particular, it is determined that moderate-sized landslides do the most work transporting material on hillslopes, defined by a work peak, and that magnitude varies based on local physiography and climate. Landslides that form the work peak are distinct from catastrophic landslides that are themselves formative and system resetting. The persistence time for debris slides/debris flows and rock slides/rock avalanches is calculated over six orders of magnitude and an event is considered catastrophic when it persists in the landscape ten times longer than the population of landslides that form the work peak. A detailed case study examines meteorological controls on landslide occurrence and the role of extreme weather is considered. A critical onset of landslide triggering rainfall intensity is determined to be between 80 mm and 100 mm in 24 hours and wind is determined to result in increased local precipitation. The role of rain-on-snow is also evaluated and determined to be crucial to landslide occurrence. Finally, a conceptual model of landslide-induced denudation for coastal mountain watersheds spanning 10,000 years of environmental change is presented. Recent human impacts are calculated for landslide frequencies over the 20th century. The impact of logging during the last 100 years is unambiguous; logging induced landslides almost doubles the effect frequency of the wettest millennia in the last 10,000 years. This suggests that the impact of logging outpaces that of climatic change. Debris slides and debris flows are estimated to have resulted in a landscape lowering of 0.7 m across the Vancouver Island during the last 10,000 years.

The purpose of this study is to examine the disruption risk resolution process in supply chains; specifically, to assess how risk attributes impact the approach firms select to resolve risks and the associated final outcomes. We propose that high magnitude risks are positively associated with mutually beneficial problem resolution; on the other hand, low likelihood risks have the opposite effect, they are negatively associated with mutually beneficial resolution. Our conceptual contribution lies in our articulation of the mechanisms though which risk magnitude and risk likelihood impact mutual problem resolution. We posit that high magnitude risks and low likelihood (uncommon) risks mobilize the social network of actors, triggering vigilant monitoring for risks, communication among actors and across firm boundaries, and resource sharing and coordination which facilitate collaborative problem solving and mutual resolutions. These mobilization mechanisms help supply chain partners to overcome the challenges of complexity and allow for information and resource flows among actors and between firms. Our statistical analysis demonstrates that the impact of risk attributes on mutual problem solutions is fully mediated by timely problem identification and collaborative problem solving.

This thesis seeks to analyze the occurrence and behavior of rainfall-triggered landslides in coastal British Columbia. In particular, it focuses on the analysis of landslide temporal and spatial distributions occurrence and their magnitudes, and considers the major factors that influence regional landslide behavior. Implicit in the research is the understanding that the landscape of coastal BC is managed, and that landslides, in addition to occurring naturally may be caused by, and certainly impact, resources that are important to humankind. Underlying each chapter is the rationale that by better understanding the causes of, and controls on landslide occurrence and magnitude, we can reduce the impacts and lower the associated risk. Statistical magnitude-frequency relationships are examined in coastal BC. Observations suggest that landslides in coastal British Columbia tend to a larger size until about 10,000 m2 in total area. At this point larger landslides are limited by landscape controls according to a power law. Probabilistic regional hazard analysis is one logical outcome of magnitude-frequency analysis and a regional mass movement hazard map for Vancouver Island is presented. Physiographic controls on statistical magnitude-frequency distributions are examined using a cellular automata based model and results compare favorably to actual landslide behavior: modeled landslides bifurcate at local elevation highs, deposit mass preferentially where the local slopes decrease, find routes in confined valley or channel networks, and, when sufficiently large, overwhelm the local topography. The magnitude-frequency distribution of both the actual landslides and the cellular automata model follow a power law for magnitudes higher than 10,000 m2 - 20,000 m2 and show a flattening of the slope for smaller magnitudes. The results provide strong corroborative evidence for physiographic limitations related to slope, slope distance and the distribution of mass within landslides. The physiographic controls on landslide magnitude, debris flow mobility and runout behavior is examined using detailed field and air photograph analysis. The role of slope on deposition and scour is investigated and a practical method for estimating both entrainment and runout in the field, as well as in the GIS environment, is presented. Further controls on landslide mobility, including the role of gullies and stream channels, roads and benches and intact forests, are considered. The role of landslides in controlling landscape physiography is also examined. In particular, it is determined that moderate-sized landslides do the most work transporting material on hillslopes, defined by a work peak, and that magnitude varies based on local physiography and climate. Landslides that form the work peak are distinct from catastrophic landslides that are themselves formative and system resetting. The persistence time for debris slides/debris flows and rock slides/rock avalanches is calculated over six orders of magnitude and an event is considered catastrophic when it persists in the landscape ten times longer than the population of landslides that form the work peak. A detailed case study examines meteorological controls on landslide occurrence and the role of extreme weather is considered. A critical onset of landslide triggering rainfall intensity is determined to be between 80 mm and 100 mm in 24 hours and wind is determined to result in increased local precipitation. The role of rain-on-snow is also evaluated and determined to be crucial to landslide occurrence. Finally, a conceptual model of landslide-induced denudation for coastal mountain watersheds spanning 10,000 years of environmental change is presented. Recent human impacts are calculated for landslide frequencies over the 20th century. The impact of logging during the last 100 years is unambiguous; logging induced landslides almost doubles the effect frequency of the wettest millennia in the last 10,000 years. This suggests that the impact of logging outpaces that of climatic change. Debris slides and debris flows are estimated to have resulted in a landscape lowering of 0.7 m across the Vancouver Island during the last 10,000 years.

Subduction zone megathrusts produce the majority of the world's largest earthquakes. To understand the processes that control seismicity here, it is important to improve our knowledge on the subduction interface characteristics and its spatial variations. Nicoya Peninsula, Costa Rica, extends the continental landmass ~50 km towards the trench, making it a very suitable place to study interface activity from right on the top of the seismogenic zone of the Middle America Subduction Zone (MASZ). We contribute to and utilize an earthquake catalog of 8765 analyst-picked events to determine the spatial variability in the earthquake frequency-magnitude distribution (FMD) in this region. After initial detection, magnitude determination and location, the events are precisely relocated using a locally derived 3-D seismic compressional and shear wave velocity model (DeShon et al., 2006). After restricting the dataset to events nearest the interface and with low formal error (horizontal location error < 5 km), we retain a subset of 3226 events that best resolves interface activity. Beneath Nicoya, we determine the spatial variability and mean FMD of the interface, and focus on the relative relationship of small-to-large earthquakes, termed b-value. Across the region, the overall b-value (1.18 ± 0.04) is higher than the global average (b~1), and much larger than the global subduction zone average (b~0.6). Significant variation in b-value is observed along the active plate interface. A well resolved zone of lower b is observed at and offshore central Nicoya coast, in a previously determined locked patch using deformation observed from Global Positioning System (GPS). Conversely, high b-values prevail over the subducted portion of the Fisher ridge, which likely ruptured in the 1990 Gulf of Nicoya Mw 7.0 earthquake. Observed regions of low b-value approximately corresponds to more strongly-locked segments of the subduction interface resulting in higher differential stress, which may be released in the next large interface earthquake in this part of the MASZ. Across the region the b-value is found to vary inversely with the degree of interface locking. Thus, it is proposed that if sufficient data exist, spatial b-value mapping can be used as a proxy to determine interface locking. This method is especially useful along the subduction megathrust, which is generally offshore making geodetic measurements difficult.

Mass movement can be activated by earthquakes, rapid snowmelt, or intense rainstorms in conjunction with gravity. Whereas mass movement plays a major role in the evolution of a hillslope by modifying slope morphology and transporting material from the slope to the valley, it is also a potential natural hazard. Determining the morphology of the mountain slopes and the relationships of frequency and magnitude of landslides are fundamental to understanding the role of landslides in the study of landscape evolution, and hazard assessment. Characteristics of the geomorphic zones in a periglacial landscape were evaluated by plotting local slopes and the drainage areas in Paonia-McClure Pass area of western Colorado. The study suggested that the steepness and concavity of mountain slopes and stream channels in the study area are related by an exponential equation. Seven hundred and thirty five shallow landslides (<160,000 m2) from the same study area were mapped to determine the frequency-magnitude relationships of shallow landslides and to develop an optimum model of mapping susceptibility to landslides. This study suggests that the frequency-magnitude of the landslides in Paonia-McClure Pass area are related by a double pareto equation with values α= 1.1, and β = 1.9 for the exponents. The total area of landslides is 4.8x10⁶ m² and the total volume of the landslides is 1.4x10⁷ m³. The areas (A) and the volumes (V) of landslides are related by V = 0.0254xA^1.45. The frequency-magnitude analysis shows that landslides with areas ranging in size from 1,600 m2 - 20,000 m2 are the most hazardous landslides in the study area. These landslides are the most frequent and also do a significant amount of geomorphic work. Three quantitative approaches: weight of evidence; fuzzy logic; and logistic regression; were employed to develop models of mapping landslides in western Colorado. The weight of evidence approach predicted 78 percent of the observed landslides, the fuzzy-logic approach also predicted 78 percent of the observed landslides, and the logistic regression approach predicted 86 percent of the observed landslides.

Due to the randomness inherent in the occurrence of earthquakes with respect to time, space and magnitude as well as other various sources of uncertainties, seismic hazard assessment should be carried out in a probabilistic manner. Basic steps of probabilistic seismic hazard analysis are the delineation of seismic sources, assessment of the earthquake occurrence characteristics for each seismic source, selection of the appropriate ground motion attenuation relationship and identification of the site characteristics. Seismic sources can be modeled as area and line sources. Also, the seismic activity that can not be related with any major seismic sources can be treated as background source in which the seismicity is assumed to be uniform or spatially smoothed. Exponentially distributed magnitude and characteristic earthquake models are often used to describe the magnitude recurrence relationship. Poisson and renewal models are used to model the occurrence of earthquakes in the time domain. In this study, the sensitivity of seismic hazard results to the models associated with the different assumptions mentioned above is investigated. The effects of different sources of uncertainties involved in probabilistic seismic hazard analysis methodology to the results are investigated for a number of sites with different distances to a single fault. Two case studies are carried out to examine the influence of different assumptions on the final results based on real data as well as to illustrate the implementation of probabilistic seismic hazard analysis methodology for a large region (e.g. a country) and a smaller region (e.g. a province).

Induced seismicity is a common phenomenon that occurs as soon as the stress state in the subsurface is externally altered in a way that faults are destabilized. It is especially problematic in stable tectonic regions where the area is not used to earthquakes; the infrastructure is not built to withstand ground movement and thus when the induced seismicity occurs damage can follow. In this thesis, mining-induced seismicity has been studied at the Dannemora mine, located in central Sweden, with the aim to locate the seismicity and gain understanding of its occurrence and behavior. The mining company, Dannemora Mineral AB, provided with blasting locations and times, as well as maps over the mine's orebodies and stopes. Seismic data acquired between 01 July 2014 - 25 March 2015 from 4 temporary seismic stations, deployed in the summer of 2014 surrounding the mine, along with 8 SNSN stations was analyzed. The project encompassed field work and processing of the data, which involved different methods to investigate the characteristics of the mine's seismicity: Statistics were kept to record the activity rate of the seismicity over time; spectral analysis was used to study the frequency content of the seismicity; particle motion plots were constructed to identify body-phases in the seismicity; Local Earthquake Tomography was used to upgrade the velocity model of the mine and to relocate the induced seismicity with more accuracy; cross-correlation was used to find events originating from similar sources; and finally, magnitude analysis was used to compare the different types of seismicity within the mine. Three main types of induced events were observed in the mine: low-frequency events with clear first arrivals, emergent events with long duration, and high-frequency events that could either have clear first arrivals or emergent-like with long durations. Through the analysis of their characteristics, they were linked to different types of rockbursts. The low-frequency events were linked to both reactivation of fault zones triggered by the mine activity, and rockbursts within the mine directly related to the mining. The emergent and high-frequency events were also linked to rockbursts directly related to the mine activity, e.g. ejection of rock from the tunnel walls or arch collapses in stopes.

Thesis (Ph. D.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.