No description available.

No description available.

Least-squares migration has been shown to be able to produce high quality migration images, but its computational cost is considered to be too high for practical imaging. In this dissertation, a multisource least-squares reverse time migration algorithm (LSRTM) is proposed to increase by up to 10 times the computational efficiency by utilizing the blended sources processing technique. There are three main chapters in this dissertation. In Chapter 2, the multisource LSRTM algorithm is implemented with random time-shift and random source polarity encoding functions. Numerical tests on the 2D HESS VTI data show that the multisource LSRTM algorithm suppresses migration artifacts, balances the amplitudes, improves image resolution, and reduces crosstalk noise associated with the blended shot gathers. For this example, multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution, and fewer migration artifacts compared to conventional RTM. The empirical results suggest that the multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with similar or less computational cost. The caveat is that LSRTM image is sensitive to large errors in the migration velocity model. In Chapter 3, the multisource LSRTM algorithm is implemented with frequency selection encoding strategy and applied to marine streamer data, for which traditional random encoding functions are not applicable. The frequency-selection encoding functions are delta functions in the frequency domain, so that all the encoded shots have unique non-overlapping frequency content. Therefore, the receivers can distinguish the wavefield from each shot according to the frequencies. With the frequency-selection encoding method, the computational efficiency of LSRTM is increased so that its cost is comparable to conventional RTM in the examples of the Marmousi2 model and a field data set from the Gulf of Mexico. With more iterations, the LSRTM image quality is further improved. The numerical results suggest that LSRTM with frequency-selection is an efficient method to produce better reflectivity images than conventional RTM. In Chapter 4, I present an interferometric method for extracting the diffraction signals that emanate from diffractors, also denoted as seismic guide stars. The signal-to-noise ratio of these interferometric diffractions is enhanced by √N, where N is the number of source points coincident with the receiver points. Thus, diffractions from subsalt guide stars can then be rendered visible and so can be used for velocity analysis, migration, and focusing of subsalt reflections. Both synthetic and field data records are used to demonstrate the benefits and limitations of this method.

The purpose of this thesis was to trace the pattern of Mormon immigration from Europe and the eastern United States during the decade of the 1860s. Although the initial Mormon migration of 1847 has recieved extensive attention from historians, later organized movements into the Great Basin by immigrant Mormon groups has remained virtually untouched. This thesis traces the formation, organization, and implementation of the church train emigration from Europe and the eastern United States. Also, it details its organization from the church hierarchy, as well as the extensive participation by the Mormon population as a whole. A primary focus of the thesis centered on the pervasive comraderie and sacrifice of the Mormons living in Utah. With the pragmatic leadership of Brigham Young, coupled with the superb organizational apparatus of the church train system, the Mormon church was afforded the opportunity to aid more than twenty thousand converts to immigrate to Utah Territory from 1861-1868. In addition, this study concerned itself with an unprecedented occurrence in the field of nineteenth century transportation. By utilizing the church train system adroitly, the Mormons were the first and only organization to journey both to and from the Missouri River (with large emigrant companies), in one season. This was an extremely important breakthrough in nineteenth century transportation and deserves greater attention from historians. The history of the church train emigration was both unique and successful. It presents a prime example of Mormon organizational abilities in the face of complex and difficult impediments.

We equipped 28 Marbled Godwit from four locations in North America with miniature satellite transmitters to determine migration routes, strategy, and connectivity. Godwits captured in Utah (n = 13) went to breeding sites in Alberta, Saskatchewan, Montana and North Dakota and wintered along the Baja Peninsula and west coast of mainland Mexico. They used Bear River Migratory Bird Refuge (BRMBR), Utah as a stopover during both north and southbound migration. Godwits captured on Akimiski Island, Nunavut, Canada (n = 7) migrated through the midcontinent USA and wintered at sites along the Gulf of California, Sonora, Mexico. There is overlap in use of Mexico winter and stopover areas between the birds from Akimiski Island and those captured in Utah. Godwits captured in Georgia on the Atlantic coast (n = 6) migrated to breeding grounds in North and South Dakota. Godwits wintering along the Atlantic coast breed in close proximity to those originating from Mexico wintering sites and using BRMBR as a stopover. Godwits tagged on Akimiski Island traveled significantly farther during southbound migration (3862 km) than did godwits tagged in Utah (2533 km) and Georgia (2204 km) (P < 0.001). Godwits tagged in Utah traveled the shortest distance to the first stopover during southbound migration (670 km) (P < 0.001). This short distance between stopovers is characteristic of a “hopping” migration strategy, which is different than the intermediate “skipping” distances traveled by godwits from Canada (1925 km) and Georgia (2204 km), to their first stopover. Utah godwits also had the shortest residency period on winter habitats (174 days) (P < 0.001). Georgia godwits had the shortest southbound migration duration (2 days) (P < 0.02), the shortest residency period at breeding habitats (56 days) (P < 0.01) and the longest residency period on the wintering grounds (303 days) (P < 0.003). (152 pages)

Most past research on migration has focused on young adults or recent retirees since these are the two groups most likely to migrate. Very little research has looked at the factors that affect the migration of people in the middle stages of life. The purpose of this research is to identify those factors, and determine if there are differences between whites, blacks, and Hispanics. The data utilized for this research were from the National Longitudinal Study of Youth 79, a study funded by the Bureau of Labor Statistics that has been ongoing since 1979. Migration was defined as the movement across county lines, and was calculated for 1979 and all subsequent even numbered years between 1980 and 2000. Other variables controlled were demographic, socioeconomic status, and household status, and were measured as categorical variables. Descriptive and logistic analyses were used. (77 pages)

No description available.

Migration to Sweden and integration of immigrants in Sweden is an ongoing subject in politics and the media. Swedish people migrating to other countries that have different cultures and values is not as talked about. One example of such a country is Japan which has experienced a drastic demographic change in the last decades with a growing elderly population. Japan has a restrictive migration policy and while the easiest way of solving this issue is allowing more migrants into the country, little has been done to change policies so far. This study aims to explore what experiences Swedish migrants in Japan have in their everyday life. What challenges do they face? To explore this the study focuses on their experiences of contact with Japan’s public sector, workplaces, and relationships with Japanese people. Five semi-structured interviews were conducted with Swedish people that all had experience of living and working in Japan. The results show that the respondents generally have a positive experience of Japan’s public sector, while they wish there were more English-speaking staff. They also critiqued Japan’s restrictive migration policies. In the workplaces they also had generally positive experiences. They talked about cultural differences they encountered and that they had to adapt how they behaved in certain ways. When it came to relationships with Japanese people it was a mixed bag. While they all had Japanese friends, and some had Japanese partners, they all felt that it was difficult to get close to or befriend Japanese people. Several of the respondents also experienced different types of discrimination and harassment. None of the respondents felt fully integrated into Japanese society, where some of them wanted to feel fully integrated, while some were happy the way it was.

Approximately eight people have died every single day since January 1, 2014 attempting to cross the Mediterranean Sea. Put another way, more than 23,000 migrants have met their end in the Mediterranean while attempting to enter the European Union. Yet, it has not always been this way. Dangerous and lethal Mediterranean crossings have been on the rise since the 1990’s as a result of more restrictive EU migration policies and increasing conflict and unsettlement in the Middle East and North Africa regions. This thesis seeks to understand how and why death has become a hallmark of the Mediterranean Sea by examining the laws relevant to the Sea. To do so, this work examines three case studies: the Successful Crossing, where a migrant vessel safely crosses the Mediterranean; the Thwarted Crossing, where a vessel is intercepted while crossing; and, the Failed Crossing, where a migrant vessel sinks or is pushed back from safety. The most relevant international, EU, and state laws are then contrasted with these case studies to determine if the vessels and the government actors around the vessel behaved according to the law or not. Across all three case studies, government actors violated some level of law (international, EU, or state.) In most cases, these violations are stipulated by another level of law (e.g., state laws allow for violations of international laws,) demonstrating a mismatch between the three levels of laws. In other cases, there is absolutely no legal support for the actions that have created so many deaths in the Mediterranean. Such violations are often met with impunity for the operators. This thesis documents such violations and then reflects on why the laws are built and broken in these ways. Subsequently, this thesis then recommends pathways to reform the laws in-line with human rights norms.

Over the past few years, Deep Learning (DL), a promising technology leading the next generation of intelligent environments, has attracted significant attention and has been intensively utilized in various fields in the fourth industrial revolution era. The applications of Deep Learning in the area of Mobile Edge Computing (MEC) have achieved remarkable outcomes. Among several functionalities of MEC, the service migration frameworks have been proposed to overcome the shortcomings of the traditional methodologies in supporting high-mobility users with real-time responses. The service migration in MEC is a complex optimization problem that considers several dynamic environmental factors to make an optimal decision on whether, when, and where to migrate. In line with the trend, various service migration frameworks based on a variety of optimization algorithms have been proposed to overcome the limitations of the traditional methodologies. However, it is required to devise a more sophisticated and realistic model by solving the computational complexity and improving the inefficiency of existing frameworks. Therefore, an efficient service migration mechanism that is able to capture the environmental variables comprehensively is required. In this thesis, we propose an enhanced service migration model to address user proximity issues. We first introduce innovative service migration models for single-user and multi-user to overcome the users’ proximity issue while enforcing the service execution efficiency. Secondly, We formulate the service migration process as a complicated optimization problem and utilize Deep Reinforcement Learning (DRL) to estimate the optimal policy to minimize the migration cost, transaction cost, and consumed energy jointly. Lastly, we compare the proposed models with existing migration methodologies through analytical simulations from various aspects. The numerical results demonstrate that the proposed models can estimate the optimal policy despite the computational complexity caused by the dynamic environment and high-mobility users.