Determinants of fertility in urban and rural Kenya: estimates and a simulation of the impact of education policy

Fertility behavior and population growth and its impact on economics in Kenya are a concern because of recent trends. The aim of this research study was to examine the impact of multiple factors on fertility in urban and rural areas based on the 1984 Kenya contraceptive Prevalence Survey. Simulation models were used to project the number of births expected with the current educational program. The expectation was that increasing female education in rural areas would have an impact on birth probabilities. Policy implications are discussed in terms of increasing educational expenditures, particularly for rural women. The empirical model selected was based on theories on proximate determinants, demographic effects, and neoclassical models. A probit model was used to estimate whether or not a woman had a child in the year preceding the survey. Explanatory variables were economic (female employment and years of schooling), biological (mother's age and child mortality), and cultural (marital state, number of live births, and religion). The sample included 6405 women aged 15-49 years. Married urban women were 37% more likely than unmarried urban women to have given birth. Married rural women in monogamous marriages were 23% more likely to have given birth than their unmarried counterparts. The number in a marital union of wives did not affect the probability of birth in urban areas; the effect was quite small in rural areas. Probability of birth increased until age 25 in urban areas and to age 28 in rural areas. Previous live births had a small impact, and the inhibiting effect of an additional child is 2.7 times larger in urban than in rural areas. Only in urban areas did employment reduce the probability of a birth (by 7.4%). In rural areas, increases in education after the primary level were related to a decline in the probability of a birth (for a 26-year old woman there is a reduction in the probability of .18). The fertility rate of a woman completing secondary school was 3.5 and 7.8 for a woman completing primary school. There were no differences in urban Nairobi and Mombasa. The total fertility rate should decline by 25% between 1984 and 2014, and should fall further based on educational increases which affect family planning use, employment, and infant mortality. By 2014, the savings in education and related expenses for reduction in births of 5.8 million will be considerable.     

Microwave Dielectric Properties of Hexagonal 12R-Ba3LaNb3O12 Ceramics

The dielectric properties of dense ceramics of the n =0 member of a newly identified homologous series Ba_{3+ n} LaNb₃Ti _n O_{12+3 n} , where n =0, 1, and 2, are reported. Single-phase powders can be obtained from the mixed-oxide route at 1350°C and dense ceramics (>97% of the theoretical X-ray density) with uniform microstructures (3–5 μm) can be obtained by sintering in air at 1500°C. The ceramics are excellent dc insulators with a band gap >2.6 eV that resonate at microwave frequencies with a relative permittivity, ɛ_r∼44, a quality factor, Q × f _r, of ∼9000 at f _r∼5.5 GHz and a temperature coefficient of resonant frequency, TC_f,∼−100 ppm/K.     

Rapid low temperature synthesis of a titanate pyrochlore by molten salt mediated reaction

Ytterbium titanate pyrochlore, Yb₂Ti₂O₇, was prepared by molten salt mediated synthesis (MSS) from titanium oxide (TiO₂) and ytterbium oxide (Yb₂O₃) reagents. Potassium and sodium chloride mixtures were used as the molten salt medium and the effects of salt to reagent ratio, salt composition, synthesis temperature, reaction time, and TiO₂ particle size were explored. Synthesis temperatures and times required for formation of single phase Yb₂Ti₂O₇ were found to be lower than those required for solid state synthesis (SSS). Whereas MSS synthesis of single phase Yb₂Ti₂O₇ was achieved with micron-sized powders after a single reaction at 1200 °C for 1 h, SSS with micron-sized powders required an extended reaction time of 36 h at 1350 °C. Yb₂Ti₂O₇ micron-sized powder prepared by MSS showed similar particle size and morphology to that of the TiO₂ precursor demonstrating a template growth mechanism. However, the use of TiO₂ nano-sized powder changed the dominant synthesis mechanism from template growth to dissolution–precipitation and facilitated synthesis of near single phase Yb₂Ti₂O₇ at the remarkably low temperature of 700 °C in only 1 h. The potential application for lanthanide and actinide immobilisation from molten salt reprocessing wastes was demonstrated by preparation of Yb₂Ti₂O₇ by molten salt mediated synthesis from TiO₂ and ytterbium chloride (YbCl₃) reagents.     

Sensitive detection of sample interference in environmental qPCR

Sample interference in environmental applications of quantitative PCR (qPCR) can prevent accurate estimations of molecular markers in the environment. We developed a spike-and-recovery approach using a mutant strain of Escherichia coli that contains a chromosomal insertion of a mutant GFP gene. The method was tested in water samples by separately reducing extraction efficiency or adding humic acids and ethanol, compounds that often contaminate environmental DNA extracts, and analyzing qPCR amplification of the spiked E. coli control and human fecal Bacteroides markers (HF183 and HF134). This approach, coupled with previously developed kinetic outlier detection (KOD) methods, allowed sensitive detection of PCR inhibition at much lower inhibitor concentrations than alternative approaches using Cq values or amplification efficiencies. Although HF183 was more sensitive to the effects of qPCR inhibitors than the E. coli control assay, KOD methods correctly identified inhibition of both control and HF183 assays in samples containing as little as 0.1 ng humic acids per reaction or 5% ethanol. Because sigmoidal modeling methods allow distinction of qPCR inhibition from poor DNA recovery, we were able to simultaneously identify qPCR-inhibited reactions and estimate recovery of nucleic acids in environmental samples using a single control assay. Since qPCR is currently used to estimate important water quality parameters that have serious economic and human health outcomes, these results are timely. While we demonstrate the methods in the context of water quality regulation, they will be useful in all areas of environmental research that use qPCR.     

Microstructure characterization of the non-modulated martensite in Ni–Mn–Ga alloy

The microstructure of the non-modulated martensite in a Ni–Mn–Ga alloy has been characterized in detail by conventional transmission electron microscopy. Bright field images show that the martensite exhibits an internal substructure consisting of a high density of narrow twins. Using electron diffraction, it is found that the martensite has a tetragonal crystal structure. The lattice correspondence between the parent phase and the non-modulated martensite is investigated. Furthermore, the four twinning elements describing the microtwinning have been graphically and quantitatively determined. The results indicate that the microtwinning within the non-modulated martensite belongs to the compound type.     

Crystal growth kinetics in BaOAl2O32SiO2 and SrOAl2O32SiO2 glasses

Crystallization kinetics of BaOAl₂O₃2Si0₂ (BAS) and SrOAl₂O₃2SiO₂ (SAS) glasses in bulk and powderforms have been studied by non-isothermal differential scanning calorimetry (DSC). The crystal growth activation energies were evaluated to be 473 and 451 kJ mol^–1 for bulk samples and 560 and 534 kJ mol^–1 for powder specimens in BAS and SAS glasses, respectively. Development of crystalline phases on thermal treatments of glasses at various temperatures has been followed by powder X-ray diffraction. Powder samples crystallized at lower temperatures than the bulk and the crystallization temperature was lower for SAS glass than BAS. Crystallization in both glasses appeared to be surface nucleated. The high temperature phase hexacelsian, MAl₂Si₂O₈ (M = Ba or Sr), crystallized first by nucleating preferentially on the glass surface. Also, monoclinic celsian does not nucleate directly in the glass, but is formed at higher temperatures from the transformation of the metastable hexagonal phase. In SAS the transformation to monoclinic celsian occurred rapidly after 1 h at 1100 °C. In contrast, in BAS this transformation is sluggish and difficult and did not go to completion even after 10 h heat treatment at 1400 °C. The crystal growth morphologies in the glasses have been observed by optical microscopy. Some of the physical properties of the two glasses are also reported.     

On the existence of the compound “Ce_3NbO_(7+δ)” prepared under air atmosphere

The solid state synthesis of the phase Ce_3 NbO_(7+δ),from stoichiometric quantities of CeO_2 and Nb_2 O_5,was investigated under air atmosphere,as previously described by Zhang et al.(Journal of Rare Earths,2007,25,730-733),A combination of powder X-ray diffraction,scanning electron microscopy with energy dispersive X-ray analysis,and laboratory Ce L_3 X-ray absorption spectroscopy,demonstrates the product of the reaction to be a mixture of CeO_2 and CeNbO_4.These data,and reexamination of the published X-ray diffraction data of Ce_3 NbO_(7+δ),are consistent with this phase in fact being CeO_2.No evidence for the formation of a phase of composition Ce_3 NbO_(7+δ) is found,by solid state synthesis under air atmosphere.     

Glass Properties in the Yttria-Alumina-Silica System

The glass formation region in the yttria-alumina-silica system was investigated. Properties of glasses containing 25 to 55 wt% yttria were measured and the effect of the composition was determined. The density, refractive index, thermal-expansion coefficient, and microhardness increased with increasing yttria content. The dissolution rate in IN HCl increased with increasing yttria content and temperature. These glasses were also found to have high electrical resistivity.