Browsing by Subject "migration"
Now showing 1 - 13 of 13
Results Per Page
Sort Options
Item A distributed hard real-time Java system for high mobility components(Texas A&M University, 2005-02-17) Rho, SangigIn this work we propose a methodology for providing real-time capabilities to component-based, on-the-fly reconfigurable, distributed systems. In such systems, software components migrate across computational resources at run-time to allow applications to adapt to changes in user requirements or to external events. We describe how we achieve run-time reconfiguration in distributed Java applications by appropriately migrating servers. Guaranteed-rate schedulers at the servers provide the necessary temporal protection and so simplify remote method invocation management. We describe how we manage overhead and resource utilization by controlling the parameters of the server schedulers. According to our measurements, this methodology provides real-time capability to component-based reconfigurable distributed systems in an effcient and effective way. In addition, we propose a new resource discovery protocol, REALTOR, which is based on a combination of pull-based and push-based resource information dissemination. REALTOR has been designed for real-time component-based distributed applications in very dynamic or adverse environments. REALTOR supports survivability and information assurance by allowing the migration of components to safe locations under emergencies suchas externalattack, malfunction, or lackofresources. Simulation studies show that under normal and heavy load conditions REALTOR remains very effective in finding available resources, and does so with a reasonably low communication overhead.REALTOR 1)effectively locates resources under highly dynamic conditions, 2) has an overhead that is system-size independent, and 3) works well in highlyadverse environments.We evaluate the effectiveness of a REALTOR implementation as part of Agile Objects, an infrastructure for real-time capable, highly mobile Java components.Item All Aboard: Bringing the Community Forward to Fedora 6.0(Texas Digital Library, 2021-05-24) Wilcox, David; Griffith, ArranItem An AVO method toward direct detection of lithologies combining P-P and P-S reflection data(Texas A&M University, 2004-09-30) Carcuz Jerez, Juan Ramon de JesusI here present a combined AVO analysis of P-P and P-S reflection data whose objective is to improve the identification of lithology by estimating the specific values of Poisson's ratio, [sigma], for each rock formation in a given geological model, rather than a contrast between formations. Limited knowledge on the elastic parameters of a given rock formation and difficulty regarding the availability and processing of P-S data constitute hindrances of lithology identification. Considering that ocean bottom seismology (OBS) has aided in solving the problem of P-S data availability, limited information on elastic parameters is still a challenge, and the focus of this thesis. The present analysis is based on Zoeppritz' solution for the P-P and P-S reflection coefficients, RPP and RPS, with a slight modification. We used the normalized P-S reflection coefficient; i.e., R'PS = RPS / sin [theta] for [theta] > 0, instead of RPS, where [theta] is the incident angle. By normalizing RPS, we avoid dealing with the absence of converted S-waves at small incident angles and enhance the similar linear behavior of the P-P and normalized P-S reflection coefficients at small angles of incidence. We have used the linearity of RPP and R'PS at angles smaller than 35 degrees to simultaneously estimate the average VP/VS ratio, the contrasts of P- and S-wave velocities, and the contrast of density. Using this information, we solve for Poisson's ratio of each formation, which may enable lithology discrimination. The feasibility of this analysis was demonstrated using nonlinear synthetic data (i.e., finite-difference data). The results in estimating Poisson's ratio yielded less than 5 percent error. We generalize this new combined P-P and P-S AVO analysis for dipping interfaces. Similarly to the nondipping interface case, our derivations show that the amplitude variation with offset (AVO) of P-P and P-S for a dipping interface can be cast into intercepts and gradients. However, these intercepts and gradients depend on the angle of the dipping interface. Therefore, we further generalize our analysis by including a migration step that allows us to find the dipping angle. Because seismic data is not available in terms of RPP and R'PS, this process includes recovery of reflection coefficients after migrating the data and correcting for geometrical spreading, as done by Ikelle et al. (1986 and 1988). The combination of all of these steps, namely geometrical-spreading correction, migration, and AVO analysis, is another novelty of this thesis, which leads to finding the specific values of Poisson's ratio of each rock formation directly from the seismic data.Item Channel planform dynamics of an alluvial tropical river(Texas A&M University, 2005-08-29) Alvarez, AldoThe meandering stream has been well studied in temperate environments but the same level of research has not been achieved for meandering streams in tropical areas. The overall objective of this research was to gain an increased understanding of meandering planform dynamics in humid tropical rivers. The objective was pursued by examining the rate of change of channel pattern and results indicate that migration rate and the range of radius of curvature to width ratio where maximum migration occurs is similar to those reported for humid temperate rivers. In summary, as regards to these aspects, the results suggest that the representative humid tropical river is no more dynamic than its temperate counterparts. A second objective was to document the response and recovery of a humid tropical river system to an extreme flood event. As a result, the trend of shorter recovery times following a major perturbation was demonstrated, and suggests that in the long term, a large flood such as a 100-year event apparently plays a relatively minor role as a formative event in shaping the overall humid tropical landscape. A third objective was to develop an empirical model for predicting bend migration rates in humid tropical rivers, resulting in empirical relationships that indicate that meander migration has a high degree of correlation with the number of bankfull discharge events under all scenarios, and that model correlation can be enhanced when the silt-clay composition of the banks, and the radius of curvature to width ratio are included as independent variables. The resulting equations were tested to predict maximum meander migration distance, and predictions produced very satisfactory results. In addition to increasing basic understanding of meander processes in tropical areas and for developing fluvial geomorphological theory, the results of this research have potentially important benefits to society. Because property and structures are often threatened by channel movement, there is a need for improved predictive capability of deformation of stream channels, and the results can therefore be useful to engineers and other professionals in delineating channel hazard zones.Item Domestic Institutions and the Supply and Demand of Remittances(2011-02-22) Hicks, Brian N.Many countries are dependent upon capital flows for their balance of payments accounts. Sources of expenditures include foreign direct investment (FDI), portfolio investment (PI) and remittances. While the determinants of FDI and PI have been extensively analyzed, the analyses of remittance flows from host to home countries are largely lacking and wide-ranging. Factors predominantly not considered are domestic institutions which support or encourage international remittance exchange. Nations routinely desire to control international immigration and capital movement. Consequently they adopt domestic policies which create and enforce institutions that manage both capital and labor mobility across borders. Additionally, researchers commonly neglect to consider the impact of both the supply and demand factors simultaneously, or in other words, the domestic condition (home and host) which both push and pull migrants to migrate and remit. Further, given the non-dyadic nature of the data, there arises a need to "regionalize" the data. To test the effects of variations in immigration institutional attributes, I employ a pooled data set of approximately 104 nations from 1990 to 2004. Controlling for existing explanations and regional influences, I find that domestic institutions have a significant impact on the ability of an individual to migrate to a host country and to eventually remit back to their country of origin.Item Early Migratory Behavior of Northern Fur Seal (Callorhinus ursinus) Pups from Bering Island, Russia(2012-07-16) Lee, Olivia AstilleroI examined the population trends of northern fur seals (Callorhinus ursinus) using an age-specific metapopulation model that allowed migration between rookeries. Mortality and birth rates were modified to simulate future population trends. I also examined the early migratory behavior and habitat associations of pups from Bering Island (BI), Russia. I instrumented 35 pups with Mk10-AL satellite tags and stomach temperature telemeters which provided diving, foraging and location data. I hypothesized that some aspects of pup behavior from the stable BI population differed from the behavior of pups from the unstable Pribilof Islands (PI). The population model revealed that emigration did not contribute significantly to the current PI population decline. However, large source populations contributed significantly to population growth in newly colonized rookeries. A stabilization of the PI population was predicted with a 10 to 20 percent reduction in both juvenile and adult female mortality rates. The diving behavior of pups showed a general progression towards longer and deeper dives as pups aged, particularly between 1600 ? 0400 (local time), that was similar to PI pup behavior. However, unlike pups from the PI, I found three main diving strategies among BI pups: 1) shallow daytime divers (mean depth = 3.56 m), 2) deep daytime divers (mean depth = 6.36 m) and 3) mixed divers (mean depth = 4.81 m). The foraging behavior of pups showed that most successful ingestion events occurred between 1600 ? 0400, with successful ingestion events lasting 25.36 plus/minus 27.37 min. There was no significant difference among the three strategies in the depth of successful foraging dives. I also examined the foraging search strategies in adult females and pups. Both pups and adults conducted Levy walks, although pups foraged in smaller patches (1 km scales). Using a logistic model to determine habitat associations, I found that pup locations were positively correlated with increasing chlorophyll a concentrations, distances from shore, and sea surface temperatures, and were negatively correlated with depth. There was no significant relationship between all pup locations and the regions (peripheries or centers) or types (cyclonic or anti-cyclonic) of eddies, but ingestion event locations were related to mesoscale eddy peripheries.Item Mexican-Origin Interregional Migration from the Southwest: Human, Household, and Community Capital Hypotheses(2010-01-16) Siordia, CarlosThis research addresses the question of what factors lead Mexican-origin individuals living in the U.S. to seek a new residence outside their Southwestern state of residence. The analysis examines three hypotheses: (1) the human capital hypothesis that college graduates have higher odds of migrating out of the core region than those with less than a high school education; (2) the household social capital hypothesis that posits that the presence of a household member born outside the core increases the odds of migration; and (3) the community social capital hypothesis which states that householders residing in an area with community social capital will have higher odds of leaving the core than those living in areas with no community social capital. These hypotheses are investigated using three models: (1) a full model that includes both native- and foreign-born Mexican-origin householders; (2) a native-born model which includes only native-born Southwest householders; and (3) a foreign-born models that includes only foreign-born Mexican-origin householders. By using the Saenzian region-concepts of core, periphery, and frontier, I find: (1) limited support for the human capital hypothesis; (2) consistent support for the household social capital; and (3) no support for the community social capital. The analysis is important to sociological theory and demography because it specifically endeavors to explain how the connections between three kinds of capital?human, household, and community?shape the decision to leave the Southwest for other regions of the country. By computing statistical and theoretical particulars, the thesis ascertains that migration-selectivity theories regarding the general population are useful in theorizing Mexican-origin interregional migration. Findings expand existing sociological literature by theorizing how human, household, and community capital operate under the Saenzian regions to shape the interregional migration of the growing Mexican-origin population of the U.S.Item Rethinking the nonmetropolitan turnaround: renewed rural growth or extended urbanization?(Texas A&M University, 2007-04-25) Wang, XiaodongThis dissertation proposes a new, synthesized perspective for explaining the ??????Nonmetropolitan Turnaround?????? in the 1970s and 1990s. By studying the definition of urbanization carefully, using the human ecological perspective, many processes happening during the ??????Nonmetropolitan Turnaround?????? in the 1970s and 1990s, such as suburbanization, deconcentration, and counterurbanization, can be understood as different forms of the urbanization processes. When the majority of the population was rural, the dominant pattern of urbanization was rural-urban migration. When the majority of the population became urban, the dominant urbanization pattern reversed to urbanrural migration because urban centers had reached beyond their optimal density and processes operated to reduce their density. This paper hypothesizes that the two ??????turnarounds?????? were simply the result of different aspects of urbanization complicated by metropolitan status reclassifications. The perspectives of suburbanization, counterurbanization and deconcentration are integrated into the urbanization perspective. Using migration flow data compiled by the Census Bureau from 1975 to 1980 and from 1995 to 2000, the summary analyses confirmed that the net migration due to the three forms of urbanization largely accounted for all of the net migrant flows. This dissertation further tested the validity of optimal density theory with net migration data and confirmed the utility of this perspective in predicting the direction of net migration.Item Session 3L | Stop Storming and Start Performing: Developing a DAMS using Scrum(Texas Digital Library, 2021-05-26) Jones, Jerrell; Ramirez, Ada Laura; Scott, Bethany; Watkins, SeanTo answer calls for improved access, discovery, and system integration, UH Libraries has been building a flexible digital collections ecosystem over the past several years. In 2020, UH Libraries launched its digital collections ecosystem that supports efficient digital collections management, effective digital preservation, and integration with ArchivesSpace to better support discovery and retrieval of digital objects. This complex and challenging undertaking resulted in the adoption of a project management approach called Agile using a framework called Scrum. In this presentation, we will give an overview of the DAMS, and describe our project management trajectory from its earliest days, through its transformation into a highly effective team regularly delivering value-added increments to our users and stakeholders. We will give examples of different parts of the agile processes, the pivot points in the project, and the lessons learned from each iteration of our team. We are substantially underway with our migration of collections from CONTENTdm to our new repository and continue to benefit from the success of our Scrum approach.Item Social organization of the New Zealand dusky dolphin(Texas A&M University, 2004-09-30) Markowitz, Timothy MichaelSocial organization of dolphins in extensive societies has not been well studied. Off Kaikoura, New Zealand, thousands of dusky dolphins (Lagenorhynchus obscurus) gather, feeding nocturnally on deep scattering layer prey, resting and socializing diurnally. During 1997-2003, interval sampling was used to monitor large assemblages numbering hundreds (n=169), smaller mating groups (mean+s.e.=7+1.6 adults, n=42), mother-calf nurseries (mean+s.e.=13+1.6 adults, 1+0.5 juveniles, 4+0.7 calves and 1+0.4 neonates, n=41), and non-mating adult groups (mean+s.e.= 9+1.3 adults, 1+0.2 juvenile, n=37). Group size, distance from shore (east), ranging along shore (north), traveling, inter-individual distance, and noisy leaping peaked in winter (n=39), with dolphins maintaining closer proximity to each other in smaller, more restful groups, closer to shore during the spring-summer-autumn (n=234) reproductive seasons. Dolphin groups were found closest to shore (west) during early morning, spread out and leaping often. Resting peaked at midday in tight groups. Late in the day, dolphins spread out, moving eastward (offshore) in preparation for feeding. Large groups exhibited coordinated travel, with noisy leaps as a directional signal. "Mating of the quickest" occurred in groups of (median) 6 males chasing 1 female. Leaping rarely occurred in restful nurseries, which at times associated with Hector's dolphins (Cephalorhynchus hectori). Other mixed-species groups included common dolphins (Delphinus delphis), southern right whale dolphins (Lissodelphis peronii), long-finned pilot whales (Globicephala malaena), and bottlenose dolphins (Tursiops truncatus). Killer whales (Orcinus orca) elicited predator assessment and evasion. Whale riding occurred with larger whales. Residence was seasonal, with 1,969+814.9 from a population of 12,626 dolphins spending 103+38.0 days in Kaikoura (mean+s.e., mark-recapture mortality, single-season lagged-ID emigration models, n=153 weeks). Dolphins (n=39) summering in Kaikoura migrated to the Marlborough Sounds in winter, where small, coordinated groups foraged diurnally on schooling fishes in shallow bays, often associated with sea birds and New Zealand fur seals (Arctocephalus forsteri). Aquaculture may threaten dusky dolphin foraging habitat in Admiralty Bay, where an estimated 220 dolphins gathered to feed each winter. Photo-identification research, enhanced by digital techniques, demonstrated a structured fission-fusion society. Dusky dolphins associated with preferred long-term (>1,000 days) hunting companions in Admiralty Bay and non-random casual acquaintances (200 days) in Kaikoura (lagged-association models).Item The Effect of Physico-Chemical Factors on the Stability and Transport of Clay Particles(2012-07-16) Musharova, DaryaClays which exist in formations in the vicinity of injection and disposal wells is a worldwide problem in the petroleum industry. Clays can be categorized as two major groups: swelling clays, which include smectite group clays, and dispersing clays, which include the kaolinite groups of clays. Therefore, two basic damage mechanisms of clay minerals are swelling and dispersion. Both mechanisms cause pore plugging, and thus aggravate hydrocarbon ease of flow. In this thesis, the effect of temperature, injected water chemical composition, pH, and flowrate of the injected fluid were tested experimentally. Clay mineralogy, chemistry, and composition of the exchangeable cations were also examined. The existing theoretical models of evaluation of forces between clay particles and the rock matrix were used to quantify the interactions. Coreflood experiments were conducted to determine the effect of parameters such as variation of temperature, flowrate, pH, presence of various salts in working solution and their concentration. The results obtained from experimental and theoretical work show that clay minerals in sandstone formation are subject to fines migration and can cause a detrimental impact on the reservoir permeability. Every aforementioned factor has its influence on clays behavior and therefore, a degree of fines migration. The work accomplished summarizes and concludes what parameters sensitize clays migration. Moreover, recommendations for formation damage due to fines migration are given. The scope of work presented can be useful for petroleum engineers as well as geologists and clay mineralogists.Item The Motivators that Contribute to the Migration of African American Educators from Suburban School Districts to Urban School Districts(2012-07-16) McGary, Ostrova DewayneThe purpose of this qualitative study was to examine the perceived motivators contributing African American educators' decision to migrate from a suburban school district to an urban school district. The case study approach was used in an effort to capture the participants' voices and the motivators contributing to their decision to migrate to an urban school district after working as an educator in a suburban school district. The findings from this study will contribute to the existing body of literature by providing national policy makers, state policy makers, local school leaders and school district personnel information to create national, state, and local policy initiatives regarding African American educator personnel. The seven informants in this study were members of a large metropolitan area in the state of Texas and the suburban school districts bordering that metropolitan area. Since the enactment of the federal No Child Left Behind Act (2001), the achievement gap has been discussed and studied. However, few studies have investigated African American educator migration from suburban school districts to urban school districts and the strategies used by African American educators to close the achievement gap for African American students who attend those suburban schools left void of African American educators. The interpretational analysis process selected was based on Glaser and Strauss' constant comparative approach to analysis. The constant comparative data analysis generated five major themes of the motivators contributing to African American educator migration: (1) educators migrated to become social change agents, (2) educators migrated for growth opportunities, (3) educators migrated for financial increases, (4) educators migrated due to workplace relationships, and (5) educators migrated due to their perceptions and experiences in their suburban school district. My findings, based on the context of these seven African American educators, suggest that while the school district as an institution is not responsible or accountable for the African American educators migration, it can provide systems of support and initiatives for African America educators to assist them in overcoming the motivators inside of the school walls that contribute to their decision to leave.Item Two Essays in Labor Economics(2012-12-10) Zhu, Siyi 1983-The first essay studies the long term trend of internal migration in the United States. Over the last forty years, there has only been a modest change in the overall interstate migration rate in the United States. However, different demographic groups have seen very different patterns of changes. The migration rate for families with two college graduate spouses dropped from 5.66% in 1965-1970 to 2.82% in 2000-2005. As for the families with college-graduate husband, it dropped from 4.05% to 2.15% during the same time frame. Interstate migration rates for other types of families or singles have seen little change. This paper extends Mincer?s family migration model into a search framework and directly estimates the effects of female labor force participation, spousal earnings ratio, correlation of earnings from job offers, and home ownership on the migration propensity by using the Current Population Survey (CPS) data in the period of 1982-2005. Endogeniety issues of these variables are appropriately addressed. According to the Blinder-Oaxaca decomposition analysis, we find that the increasing female labor force participation rate and earnings ratio of wife to husband are the primary determinants for the decline in the interstate migration rate of families with two college-graduate spouses and families with a college-graduate husband in the 1980s-1990s. The rising home ownership accounts for a large portion of the decrease in the migration rate of highly educated families, in the 1990s-2000s. The second essay studies the impact of changing youth cohort size on the unemployment rate. Although an increase in youth cohort size is often found to exert an upward pressure on the aggregate unemployment rate, it has been provided some empirical evidences and a theoretical model to the contrary. We find that the estimated elasticity of unemployment rate is quite sensitive in a fixed effect model, with the inclusion of year dummies, when there is a strong temporal correlation between the youth cohort size and the unemployment rate. Both the sign and magnitude of the estimates vary significantly when using data from different time periods. We propose an alternative way to control for the fixed effects and obtain consistent estimates across the time periods in the United States. Our results support the conventional wisdom of positive correlation between youth cohort size and aggregate unemployment rate. This positive effect of the youth cohort size is strongest for the youngest workers and gradually diminishes for older workers, which implies that the young and the prime age workers are not perfect substitutes to the employers.