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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.
271

An investigation of the inorganic chemistry of peat systems

Hao, Jicheng January 1996 (has links)
No description available.
272

Enhancement of heat transfer in smooth annular ducts using longitudinal fins or swirling flow

Edwards, R. J. January 1987 (has links)
No description available.
273

The comparative breeding ecology of sympatric common and Arctic terns in N.E. England

Robinson, James Alexander January 1999 (has links)
The life-history traits of two sympatric seabird species, the Common Sterna hirundo and Arctic Tern S. paradisaea, and the flexibility of these traits in relation to short and longer term changes in environmental conditions were measured at Coquet Island, N.E. England. The study focused primarily on inter and intraspecific differences in annual productivity and chick growth, adult time budgets and provisioning rates, and the relationships between these different aspects of reproductive performance. Of the two species, Common Terns delivered larger food items, delivered food at a higher rate to the nest and attended the nest more frequently, indicating that they made trips of shorter average duration. Daily metabolizable energy intake of chicks was about 30% higher in Common Terns than in Arctic Terns, yet the size-specific growth rates of the two species were almost identical, indicating a major difference between species in nestling energy budgets. Brooding appeared to play a less important role in the energy budgets of Common Terns, and the number of chicks that Arctic Terns could raise was probably limited not only by the rate at which parents could supply food to the nest but also by the requirements of chicks for brooding. Increased brood size, low annual food abundance and extreme weather conditions had a negative effect on chick mass development in both tern species. Flexibility of mass growth rates in Arctic and Common Terns may act as a fine-tuning mechanism to regulate provisioning in these species. By maintaining structural growth rates, final fledging mass and final fledging size of nestlings at the expense of retarded mass development rates, these species seem to be able to maximize annual reproductive output and possibly, for parents and nestlings, future survival. Predation of eggs and chicks was generally infrequent and affected mostly very young nestlings. However, Black-headed Gulls took many tern eggs in a year when inshore food supplies were particularly low.
274

An investigation into the nature and impact of financial repression in Trinidad and Tobago, 1960-1991

Ramlogan, Carlyn January 1996 (has links)
This research examines the nature and impact of financial repression in the Trinidad and Tobago economy using cointegration time series techniques and disequilibrium econometrics. While the former is employed to estimate the impact on savings, investment and growth, the latter is mainly used to test whether the characteristics which depict a financially repressed economy are present in Trinidad and Tobago. Trinidad and Tobago has not previously been the subject of such a study, and neither estimation methods have been used to investigate financial repression. While the real interest has been most frequently used to measure financial repression, six proxies are utilised in this study: the real interest rate; dummy variables; commercial banks' reserve requirement; inflation; the difference between the domestic and the foreign interest rate and a variable to measure the overvaluation of a country's currency. With respect to the latter there are two definitions: the difference between the official and the blackmarket exchange rate and the degree of exchange rate misalignment. The results using real interest rates and inflation measures of financial repression suggest that while liberalisation cannot be seen as the solution to increasing savings and investment it may promote economic growth. When all the other proxies are examined the impact of financial repression on the economy is negative albeit statistically insignificant in most instances. There is some indication that exchange rate should be devalued so as to reduce exchange rate misalignment and reduce the widening gap between the official and blackmarket rate. On the basis of these results the McKinnon-Shaw hypothesis cannot be rejected. However the results when inflation and real interest rates are the relevant proxies for financial repression as well as the low significance levels of other proxies, ought to serve as warning signals to avoid implementing drastic liberalisation measures too quickly.
275

Modelling the vertical structure of flows in the shelf seas

Cheok Van Seng, Joseph January 1996 (has links)
No description available.
276

Cooling rates of LL, L and H chondrites and constraints on the duration of peak thermal conditions: Diffusion kinetic modeling and implications for fragmentation of asteroids and impact resetting of petrologic types

Ganguly, Jibamitra, Tirone, Massimiliano, Domanik, Kenneth 11 1900 (has links)
We have carried out detailed thermometric and cooling history studies of several LL-, L- and H-chondrites of petrologic types 5 and 6. Among the selected samples, the low-temperature cooling of St. Severin (LL6) has been constrained in an earlier study by thermochronological data to an average rate of similar to 2.6 degrees C/My below 500 degrees C. However, numerical simulations of the development of Fe-Mg profiles in Opx-Cpx pairs using this cooling rate grossly misfit the measured compositional profiles. Satisfactory simulation of the latter and low temperature thermochronological constraints requires a two-stage cooling model with a cooling rate of similar to 50-200 degrees C/ky from the peak metamorphic temperature of similar to 875 degrees C down to 450 degrees C, and then transitioning to very slow cooling with an average rate of similar to 2.6 degrees C/My. Similar rapid high temperature cooling rates (200-600 degrees C/ky) are also required to successfully model the compositional profiles in the Opx-Cpx pairs in the other samples of L5, L6 chondrites. For the H-chondrite samples, the low temperature cooling rates were determined earlier to be 10-20 degrees C/My by metallographic method. As in St. Severin, these cooling rates grossly misfit the compositional profiles in the Opx-Cpx pairs. Modeling of these profiles requires very rapid cooling, similar to 200-400 degrees C/ky, from the peak temperatures (similar to 810-830 degrees C), transitioning to the metallographic rates at similar to 450-500 degrees C. We interpret the rapid high temperature cooling rates to the exposure of the samples to surface or near surface conditions as a result of fragmentation of the parent body by asteroidal impacts. Using the thermochronological data, the timing of the presumed impact is constrained to be similar to 4555-4560 My before present for St. Severin. We also deduced similar two stage cooling models in earlier studies of H-chondrites and mesosiderites that could be explained, using the available geochronological data, by impact induced fragmentation at around the same time. Diffusion kinetic analysis shows that if a lower petrological type got transformed by the thermal effect of shock impacts to reflect higher metamorphic temperature, as has been suggested as a possibility, then the peak temperatures would have had to be sustained for at least 10 ky and 80 ky, respectively, for transformation to the petrologic types 6 and 4. Finally, we present a model that reconciles textural data supporting an onion-shell parent body of H-chondrites with rapid cooling rate at high temperature caused by impact induced disturbance, and also discuss alternatives to the onion shell parent body model. (C) 2016 Elsevier Ltd. All rights reserved.
277

Transfer Rates of Texas Hispanic Community College Students to 4-Year Institutions: Selected Institutional Factors

Klement, Emily Conrady 08 1900 (has links)
The purpose of this non-experimental, quantitative study was to determine how well selected institutional characteristics explain the variance in Hispanic community college students’ transfer rates to 4-year institutions. Due to the rapidly growing Texas Hispanic population, understanding challenges to their educational attainment has become critical. Hispanic community college enrollment in Texas continues to rise, yet these students are not transferring to 4-year institutions at the same rate as other groups. This study analyzed data from the Texas Higher Education Coordinating Board of 50 Texas community colleges to determine how well the independent variables (Hispanic population of each community college campus locale, Hispanic community college student college readiness as indicated by Texas Success Indicator scores, and the percent of Hispanic faculty at each community college) accounted for the variance on the dependent variable (Hispanic community college student transfer rate). Multiple regression was used to determine the magnitude of the relationships between the dependent variable and the combination of all the independent variables. Commonality analysis was then utilized to identify proportions of variance in the dependent variable from combinations of the independent variables. The independent variables together generated a statistically significant regression model on the dependent variable, F(4, 64) = 3.067, p = .023. The R2 coefficient between the independent variables on the dependent variable presented a positive relationship with 17.2% variance. The percent of Hispanic community college faculty was the largest contributor to the variance (62.09%), the strongest factor in accounting for the transfer rates of Hispanic community college students to 4-year universities. Hispanic population of each community college campus locale had the least effect on the dependent variable with a 1.47% variance. The findings of this study support the recent report by the Texas Higher Education Coordinating Board in favor of research and resources for Hispanic educator preparation programs.
278

Spatial Mismatch Between Hiv Infection and Access to Hiv Service Facilities in Texas

Aggrey Korsah, Emmanuel 08 1900 (has links)
Since 2004, the number of people living with HIV (PLWH) has steadily increased by about 5% and currently, the number in Texas is about 86,000. Though the National HIV/AIDS Strategic Plan seeks to ensure “unfettered access to quality healthcare”, barriers to access still exist especially among minority populations. This study examines the relationship between HIV infection rates and the geographic location of HIV service centers with a focus on 4 counties: namely, Dallas, Denton, Harris and Tarrant. The goal is to show whether there is a spatial mismatch between HIV rates and service providers. Are service facilities located in zip codes where they are most needed? Using the vulnerability framework and the Inverse Care Law (ICL), we address the research question using demographic variables (race/ethnicity, sex, poverty, education attainment) and HIV data. Our results show that extreme vulnerable zip codes have high HIV rates and closest proximity to HIV service providers.
279

A Study of How the Use of High Depreciation Rates Creates Resistances to the Diffusion of Technological Innovation

Ball, Milton K. 08 1900 (has links)
No description available.
280

Erosion Rates in and Around Shenandoah National Park, VA Determined Using Analysis of Cosmogenic 10Be

Duxbury, Jane 13 February 2009 (has links)
We use cosmogenic 10Be analysis of fluvial sediments and bedrock to estimate erosion rates (103 – 106 year timescale) and to infer the distribution of post-orogenic geomorphic processes in the Blue Ridge Province in and around Shenandoah National Park, VA. Our sampling plan was designed to investigate relationships between erosion rate, lithology, slope, and basin area. Fifty-nine samples were collected from a variety of basin sizes (<1 – 3351 km2) and average basin slopes (7 - 26°) in each of four different lithologies that crop out in the Park: granite, metabasalt, quartzite, and siliciclastic rocks. The samples include bedrock (n = 5), fluvial sediment from single-lithology basins (n = 43), and fluvial sediment from multilithology basins (n = 11): two of these samples are from rivers draining streams exiting the eastern and western slopes of the Park (Rappahannock and Shenandoah Rivers). Inferred erosion rates for all lithologies for fluvial samples range from 3.8 to 24 m/My. The mean erosion rate for single-lithology basins in the Park is 11.6 ± 4.8 m/My. Singlelithology erosion rates ranges for fluvial samples are: granite (basin size = ~0.4-40 km2 and slope = 11-23°), 7.9–22 m/My; metabasalt (basin size = ~1-25 km2 and slope = 11-19°), 4.8–24 m/My; quartzite (basin size = ~0.1-9 km2 and slope = 12-23°), 4.7–17 m/My; and siliciclastic rocks (basin size = ~0.3-13 km2 and slope = 18-26°), 6.2–17 m/My. The mean erosion rate for multilithology basins (basin size = ~1-3351 km2 and slope = 7-22°) is 10.2 m/My, and individually for the Shenandoah River 7.3 m/My and the Rappahannock River 13.8 m/My. Bedrock erosion rates range from 2.4-13 m/My across all lithologies, with a mean erosion rate of 7.9 ± 5.0 m/My. Grain-size specific 10Be analysis of four samples showed no consistent trend of concentration with grain size. These data support Hack’s dynamic equilibrium model. Slope and erosion rate are not well correlated, and mean erosion rates are similar for different lithologies. Cosmogenicallydetermined erosion rates in Shenandoah Park are similar to or lower than those reported elsewhere in the Appalachians including those of Matmon and others (2003), 25 to 30 m/My for metaclastic rocks in the steep Great Smoky Mountains, Reuter and others (2004), 4 – 54 m/My in Susquehanna River basin for shale, sandstone, and schist, and Sullivan and others (2006), 6-38 m/My in the micaceous schist and gneiss of the Blue Ridge Escarpment. Cosmogenic erosion rates (integration over 104 yrs) in the Blue Ridge province of Shenandoah National Park are consistent with long-term unroofing rates (integration over 107 yrs) estimated from U-Th/He measurements (11-18 m/My) in samples collected near the Blue Ridge Escarpment by Spotila and others (2004), and fission tracks (20 m/My) in the Appalachians by Naeser and others (2005). The consistency of denudation rates integrated over very different periods of time suggests steady erosion most likely in balance with, and driving isostatic uplift of rock.

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