6 Records out of 22207 Records

Essays in development and labor economics [Kenya].

Author: Mbiti, Isaac M

Awarding University: Brown University, USA

Level : PhD

Year: 2007

Holding Libraries: ;

Subject Terms: Economics ; Essays ; Labour economics ; Development economics ;

Abstract:

Chapter 1 examines the relationship between labor markets and marriage markets in India. Using a unique panel dataset that is representative of rural India, I estimate the effect of increases in the value of female labor on women's marriage market outcomes. Female labor is more valuable in rice farming than wheat farming. I exploit rainfall shocks across rice farming households and wheat farming households to identify the effect of female labor productivity on the marriage market. Consistent with a model of imperfect markets for female labor, I find that increases in female labor productivity decrease the marriage rate of females and decrease the dowries paid out by the bride's family, indicating a rise in the bargaining power of the bride's family during dowry negotiations. Chapter 2 examines the black-white employment gaps during recessions. Previous research has shown that unemployment rates of blacks are substantially higher than that of whites, especially during recessions. However, the extent to which these differences reflect unobserved skills or other factors such as discrimination remains a matter of debate. We use wages earned in the previous year as a measure of a worker's productivity. Conditioning on wages, we find that the unemployment gap between blacks and white falls slightly, consistent with the view that some of the difference arises from unmeasured productivity difference between the races. Chapter 3 investigates the effect of school quality on student achievement in Kenya. I utilize data from the Kenyan secondary school system to obtain causal estimates of the effects of school quality on student achievement. The placement of students into government secondary schools in Kenya is based primarily on primary school test scores. I utilize the random variation induced by this system to isolate the treatment effect of school quality on subsequent student performance in the national high school examination. I find that boys attending Elite Public schools achieved significant increases in their test scores, especially in Mathematics and Sciences. However, I did not find any significant effect for girls. I argue that this disparity is driven by differential resource allocation to boys schools relative to girls schools.

A population-based approach to malaria vaccine candidate identification [Kenya].

Author: Nixon, Christian

Awarding University: Brown University, USA

Level : PhD

Year: 2006

Holding Libraries: ;

Subject Terms: Biological sciences ; Malaria ; Vaccines ; Population ;

Abstract:

Previously, we collected plasma from 143 male volunteers residing in a P. falciparum holoendemic area of western Kenya. Volunteers were drug-cured of current malaria infection, blood was collected two weeks post-treatment, and blood smears were collected weekly for 18 weeks. We identified and pooled plasma from the 10 most resistant individuals (RP) and the 7 most susceptible individuals (SP) and utilized these pools in a differential screen of a P. falciparum cDNA expression library. We screened 550,000 clones and identified 7 clones that were uniquely recognized by RP but not by SP. Two clones encoded a C-terminal region polypeptide from RAMA (RAMA-pr), a recently described rhoptry-associated membrane antigen. We measured anti-RAMA-pr antibody levels in plasma obtained two weeks post-treatment. Individuals with detectable IgG 1 anti-RAMA-pr (n=24) had fewer positive blood films (OR 1.7, 95% CI 1.21-2.44, P < 0.003), 43% lower density of parasitemia ( P < 0.02) and prolonged time to reinfection ( P < 0.0027) than individuals with undetectable (n=115) antibody levels after accounting for known determinants of resistance. In summary, RAMA-pr is a rationally identified vaccine candidate that is preferentially recognized by antibodies produced by humans with a high level of naturally acquired resistance to P. falciparum infection.

The peralkaline effect in rhyolitic melts : iron-titanium oxide solubility, phosphorus solution properties and the iron redox equilibrium, phase equilibria in a peralkaline rhyolite.

Author: Gwinn, Rosa Elizabeth

Awarding University: Brown University, USA

Level : PhD

Year: 1991

Holding Libraries: University Microfilms International ;

Subject Terms: Mineralogy ; Lava ;

Abstract:

The effect of peralkalinity in high silica melts is investigated via phase equilibria in both synthetic and natural compositions. Peralkaline melts are those containing an excess of alkalis over aluminum. In peralkaline melts, alkalis in excess of those needed to charge balance tetrahedrally coordinated aluminum are available for charge balance to other high charge cations including fe$/sp[+3]$, al$/sp[+3]$, ti$/sp[+4]$, and p$/sp[+5]$. In the system sio$/sb2$-al$/sb2$o$/sb3$-k$/sb2$o-feo- fe$/sb2$o$/sb3$-tio$/sb2$, the ratio feo/feo$/sb[1.5]$ (molar) is highest in the most peraluminous melts and decreases to a minimum in peralkaline melts at fixed $f/sb[/rm o2]$. Titanium addition increases the redox ratio relative to tio$/sb2$-free melts. Solubility of fe$/sb2$tio$/sb5$ is relatively low in peraluminous melts and is restricted by the availability of potassium to form kfe$/sp[+3]$o$/sb2$ and k$/sb2$tio$/sb5$- k$/sb2$ti$/sb2$o$/sb7$ complexes in peralkaline melts. Aluminum's use of k$/sp+$ for charge balance dominates the system and ferric iron and titanium are equally able to compete for excess potassium in peralkaline melts. In the system sio$/sb2$-al$/sb2$o$/sb3$-k$/sb2$o-feo- fe$/sb2$o$/sb3$-p$/sb2$o$/sb5$, the ratio feo/feo$/sb[1.5]$ In peraluminous melts is reduced relative to p$/sb2$o$/sb5$-free melts and, in peralkaline melts, trends to an ideal minimum value. In charge balanced melts, large amounts of p$/sb2$o$/sb5$ cause an increase in feo/feo$/sb[1.5]$. Phosphorus uses both al$/sp[+3]$ and fe$/sp[+3]$ in peraluminous melts for charge balance and prefers k$/sp+$ to either fe$/sp[+3]$ or al$/sp[+3]$ in peralkaline and charge balanced melts. Unlike in iron free melts, p$/sp[+5]$ strips k$/sp+$ from kfeo$/sb2$ rather than using al$/sp[+3]$. The crystallizing assemblage of a natural peralkaline rhyolite (kn18) is dominated by alkali feldspar and quartz $/pm$ magnetite, acmite or arfvedsonite for both water-rich and water-poor conditions. Constraints on this particular sample from Kenya suggest that it formed at 3 kbar pressures or less at fluids with x(h$/sb2$o) = 0.25 or less from a trachytic parent magma.

Mechanisms of isostatic compensation in East Africa and North America.

Author: Bechtel, Timothy Daniel

Awarding University: Brown University, USA

Level : PhD

Year: 1989

Holding Libraries: University Microfilms International ;

Subject Terms: Gravity ; Plate tectonics ; Gregory Rift ; Rift Valley ;

Abstract:

The statistical relationship between the fourier amplitudes of topography and bouguer gravity has been calculated for numerous rectangular regions of East Africa and North America, and used to estimate the flexural rigidity (d) or equivalent effective elastic thickness (t$/sb[/rm e]$) of the lithosphere beneath each region. The statistical relationship has been characterized by the coherence as a function of wavenumber. To estimate t$/sb[/rm e]$, the observed coherence is compared to the coherence predicted by a model of surface and subsurface loading of a uniform elastic plate with a specified flexural rigidity. The bouguer gravity power spectrum is used to estimate subsurface loading depths for each region. Upon estimating t$/sb[/rm e]$, it is also possible to invert the observed topography and gravity to obtain the distribution of surface and subsurface loads on the lithosphere. The observed coherence for the region surrounding the Gregory Rift in Kenya yields tm$/sb[/rm e]$ = 26 km. Calculation of initial load distributions suggests that while a previously delineated region of anomalous mantle beneath the Kenya dome does act as an upward directed subsurface load, extrusive volcanics create new downward flexure of the lithosphere, with the volcanic pile forming the observed dome. In East Africa as a whole, the coherence analysis indicates that the lithosphere is quite rigid, with t$/sb[/rm e]$ $>$ 60 km, except where it is tectonically active along the East African rift system. The distribution of less rigid areas suggests that mechanical weakening by faulting (as evidenced by azimuthally anisotropic rigidities), thermal weakening and a combination of the two processes all lower the rigidity of the lithosphere in selected areas of the rift system. Apparent overcompensation of the East African plateau in the center of the rift system is consistent with dynamic support due to convection in a fluid layer at roughly asthenospheric depths. North America shows similar patterns in rigidity, with ancient cratonic regions yielding t$/sb[/rm e]$ = 64-128 km. Tectonically younger regions such as the Appalachians appear to be less rigid, with t$/sb[/rm e]$ between 32 and 64 km. The most recently active portions of the continent beneath the western cordillera yield t$/sb[/rm e]$ $<$ 32 km. The lowest rigidities occur in the recently active basin and range province where t$/sb[/rm e]$ lower than 4 km may occur. The admittance, or spectral ratio between gravity and topography suggests a compensation depth for basin and range topography of roughly 20 km.

Modern pollen data and holocene climate change in Eastern Africa.

Author: Laseski, Ruth Anne

Awarding University: Brown University, USA

Level : PhD

Year: 1983

Holding Libraries: University Microfilms International ;

Subject Terms: Pollen ; Climate change ; Lake Victoria, Kenya ; Haya (African people) ;

Abstract:

Modern pollen spectra have been analyzed from 59 sampling sites in Eastern Africa, and these modern data have been used to interpret fossil pollen spectra from a 14,500-yr sediment core from northern Lake Victoria and fossil pollen spectra from three late holocene-age cores from northwestern Tanzania. Thirty-seven of the 59 sampling sites are located in or near the Western Rift of Uganda, Ruanda, Tanzania, and Zambia, and 22 sites are located in or near the Eastern Rift of Kenya and Tanzania. The sites include 24 water-filled craters, 13 lagoons or expanded places in rivers, 6 lava- or rock-dammed valleys, 5 strike-slip faults, 3 grabens, 2 lahars, 1 spring, and 5 basins of uncertain origin. Transfer function equations that relate modern abundances of key pollen types with modern rainfall values have been derived by linear multiple regression analysis. One of these equations has been applied to the fossil pollen spectra from pilkington bay, northern Lake Victoria. The resulting quantitative estimates of paleo-rainfall at Pilkington bay are consistent for many periods with independent estimates of paleorainfall for Eastern Africa. Modern pollen spectra from Eastern Africa have abundances that are strongly dissimilar to fossil abundances in pollen spectra from two marsh sites and one lake site in Buhaya, Northwestern Tanzania. These differences suggest that pollen spectra in Buhaya reflect vegetation that is restricted geographically in Eastern Africa to areas that fringe Lake Victoria. Some pollen changes in the upper portion of the three sediment cores are consistent with the land use history of the local Haya people, including the cultural exploitation of syzygium trees for charcoal for the local iron smelting industry and the vegetation changes associated with the beginning of cattle grazing in Western Buhaya.

We are all brothers : the suppression of consciousness of socio-economic differentiation in a Kenya Luo lineage.

Author: Goldenberg, David Asher

Awarding University: Brown University, USA

Level : PhD

Year: 1982

Holding Libraries: University Microfilms International ;

Subject Terms: Luo (African people) ; Ethnology ; Social change ; Families and family life ; Social life and customs ;

Abstract:

This dissertation examines the struggle of members of a Luo minimal patrilineage to maintain a definition of themselves as constituting an interest group in the context of Kenya's neo-colonial economy, ethnic rivalries, and rapid urbanization. The recent emergence of a sharp pattern of stratification among members threatens a lineage identity based upon egalitarianism and belief in a joint fate. With the vast majority of its male members away from the home area working as migrants, jokmboya are dispersed all over Kenya. But it is shown that urban and rural settings constitute a unified social field for them. The differential impact of modern stratification is demonstrated in the rural homeland and in Nairobi. The work examines the most important tenets of Luo kinship-- jealousy, seniority, egalitarianism, and joint fate--and explores how these are affected by new patterns of differentiation among members. A review of the lineage's history reveals that despite the transformations of the colonial period, the unit remained relatively undifferentiated as members sought to elevate the fortunes of all its youth. However, the recruitment of a number of educated jokmboya to privileged positions in the post-independence period has recently threatened the group's unity. Members' ties to the lineage lands near Lake Victoria are central. The homelands provide the most significant symbols of lineage coherence. And yet the lineage is now objectively divided between those who must rely upon their lands to support their families and those who have secured economic positions which permit them to house their families in urban areas. Beside the growing, obvious discrepancies in members' life styles and in their children's life chances, this division implies a split of the lineage into a majority for whom membership is vital, and a minority for whom it is essentially optional. It is my thesis that for the time being, lineage members are able to sustain their definition of themselves as an interest group through the manipulation of powerful symbolic forms as well as the suppression of discordant information which threatens to expose the crucial split.