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A structural design procedure for cement-treated layers in pavements
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Page will reload when a filter is selected or excluded.- Africa 1 results 1
- Background: The African Surgical OutcomeS-2 (ASOS-2) trial tested an enhanced postoperative surveillance intervention to reduce postoperative mortality in Africa. We undertook a concurrent evaluation to understand the process of intervention delivery. Methods: Mixed-methods process evaluation, including field notes, interviews, and post-trial questionnaire responses. Qualitative analysis used the framework method with subsequent creation of comparative case studies, grouping hospitals by intervention fidelity. A post-trial questionnaire was developed using initial qualitative analyses. Categorical variables were summarised as count (%) and continuous variables as median (inter-quartile range [IQR]). Odds ratios (OR) were used to rank influences by impact on fidelity. Results: The dataset included eight in-depth case studies, and 96 questionnaire responses (response rate 67%) plus intervention fidelity data for each trial site. Overall, 57% (n¼55/96) of hospitals achieved intervention delivery using an inclusive definition of fidelity. Delivery of the ASOS-2 interventions and data collection presented a significant burden to the investigators, outstripping limited resources. The influences most associated with fidelity were: surgical staff enthusiasm for the trial (OR¼3.0; 95% confidence interval [CI], 1.3e7.0); nursing management support of the trial (OR¼2.6; 95% CI, 1.1e6.5); performance of a dummy run (OR¼2.6; 95% CI, 1.1e6.1); nursing colleagues seeing the value of the intervention(s) (OR¼2.1; 95% CI, 0.9e5.7); and site investigators’ belief in the effectiveness of the intervention (OR¼3.2; 95% CI, 1.2e9.4). Conclusions: ASOS-2 has proved that coordinated interventional research across Africa is possible, but delivering the ASOS-2 interventions was a major challenge for many investigators. Future improvement science efforts must include better planning for intervention delivery, additional support to investigators, and promotion of strong inter-professional teamwork. 1 results 1
- Classroom interaction 1 results 1
- Global Health 1 results 1
- Nano-enhanced oil recovery 1 results 1
- Nanofluid 1 results 1
- Nanofluid flooding 1 results 1
- Nanofluid flooding in the petroleum industry has generated growing interest because of its potential to greatly improve oil recovery. However, studies have reported that injection of nanofluid could lead to impaired permeability due to adsorption of nanoparticles on reservoir rocks thereby incurring high costs. The use of single Nanofluid Flooding (NF) has not appreciably reduced permeability impairment. This study was therefore, designed to investigate the technical and economic viability of Nanofluid-Alternating-Brine Flooding (NABF) for enhanced oil recovery in Niger Delta reservoirs. Eight sandstone core samples obtained from Niger Delta, were characterised for porosity and permeability using Helium-Porosimeter and Permeameter, respectively. Densities and viscosities of crude oil samples and brine (Salinity: 32.2g/L) were determined using pycnometer and viscometer, respectively. Core samples were initially saturated with brine and drained with crude oil, to determine the initial Water Saturation (SWi). Silica nanoparticles of size: 20-70 nm, were dispersed in brine at concentrations ranging from 0.01 to 3.00 wt%. Interfacial Tensions (IFT) between oil and nanofluids were measured. Brine Flooding (BF) of core samples was conducted at 2.00 cm3 /min. The Optimum Concentration (OC) and Optimum Injection Rate (OIR) during NF were determined by injecting each nanofluid concentration at 0.50, 1.00, 2.00 and 3.00 cm3 /min. The NABF was carried out at OC and OIR. The Oil Recovery Factors (ORF) for all experiments were computed using material balance. The images of pre-flooded and post-flooded core samples were obtained using Scanning Electron Microscope. Nanoskin factors (Sn) were determined for NF and NABF and compared with the analytical model developed from Darcy’s equation. The ORFobtained were upscaled for field application and evaluated for Threshold Oil Price (TOP). Risk analysis with varying ORF, Capital Expenditure (CAPEX) and Operating Expenses (OPEX) was carried out using a commercial software. Data were analysed using ANOVA at 𝛼0.05. Porosity and liquid permeability for the samples were 17.0-30.0% and 1.1x10-8 -1.6x10-8 cm2 (1104.9-1584.0 md), respectively. The densities of crude oil and brine were 0.88 and 1.02 g/cm3 , while their viscosities were 3.0x10-4 kgms-2 (3.0 cp) and 1.0x10-4 kgms-2 (1.0 viii cp), respectively. The SWi were 11.0-18.4%. The IFT were 1.9x10-2 -2.3x10-2 N/m (18.5- 23.0 dynes/cm) while the OC and OIR for NF were 2.00 wt % and 2.00 cm3 /min, respectively. The ORF for BF, NF and NABF were 68.9-73.1, 63.8-66.2 and 83.8-86.2%, respectively. The pre-flooded cores had evenly distributed grain matrices void of external particles while permeability impairment was observed for NF. Permeability impairment reversal was observed during NABF. The predictive model for Sn agreed with the experimental result. Economic analysis revealed that for unit CAPEX (N13,985.56/bbl; $34.00/bbl) and OPEX (N1,867.48/bbl; $4.54/bbl), at discount rate of 10.0%, TOP was N20,196.79/bbl ($49.10/bbl). Risk analysis on profitability showed that TOP for proved, probable and possible ORF were 33,400.81, 19,197.24 and N12,545.87/bbl (81.20, 46.67 and $30.50/bbl), respectively. The order of impact of the economic variables on profitability was ORF>CAPEX>OPEX. Improved oil recovery in Niger Delta reservoirs was achieved using nano-alternating-brine flooding with minimal permeability impairment. The method is also profitable within the stipulated oil price regime. 1 results 1
- Nanoskin 1 results 1
- Nigerian Colleges of Education 1 results 1
- Permeability 1 results 1
- Postoperative Mortality 1 results 1
- Pragmatic Trails 1 results 1
- Process 1 results 1
- Students‟ rating of lecturers 1 results 1
- Student‟s evaluation of lecturers‟ teaching effectiveness at the tertiary level of education in Nigeria is being advocated by educators. While universities are currently evolving the modalities of evaluating lecturers‟ teaching effectiveness by students, colleges of education recorded little or no attempt in this respect. Hence, this study developed, validated and used the Students' Evaluation of Teaching Effectiveness Scale in the College of Education (SETES-CE) to measure specific and observable classroom behaviours of lecturers. This study adopted a survey design. Purposive sampling was used to select four colleges in the south-west, Nigeria and 160 students per college selected from year 2 and 3 while stratified sampling was used to select schools and courses. A total of 640 students and 24 lecturers participated in the validation. The SETES-CE (r = 0.72) which consists of four components namely: classroom interaction (r = 0.72), evaluation (r = 0.72), personality (r = 0.72) and preparation (r = 0.72) was used by a sample of 1600 students to evaluate teaching effectiveness. Eight research questions guided the study. Data was analysed using descriptive statistics, t-test, ANOVA and factor analysis. The Average Factor Loading (AFL), Average Communality Value (ACV) and Initial Eigen Value (IEV) of each component of SETES-CE are: classroom interaction (AFL= 0.44, ACV=0.60, IEV=3.61); evaluation (AFL= 0.46, ACV=0.60, IEV=2.64); personality (AFL= 0.45, ACV=0.60, IEV=2.34) and preparation (AFL= 0.44, ACV=0.61, IEV=2.27). Students‟ ratings for SETES-CE varies accordingly for: classroom interaction (152.60 - 156.38); evaluation (52.65 - 53.32); personality (57.04 - 57.96) and preparation (32.88 - 32.93). There was a significant difference in the male and female students‟ ratings of their lecturers‟ personality (t=2.67, df: 1583, p < .05). There exists a significant mean difference in classroom interaction (F (4, 1595) = 6. 41; p < .05) and personality (F (4, 1580) = 3.03; p < .05) of the lecturers rated. For classroom interaction, age (F(12, 1587) =2.24, p<.005), course of study (F(19, 1580) =3.54, p < .05) and year of study (t=-2.82; df: 1598, p < .05) of the students significantly influenced the rating of their lecturers, while age (F (12, 1576) =1.79, p < .05 and course of study (F(19, 1569) =2.25, p <.05) significantly influenced the ratings of their lecturers‟ evaluation, whereas students‟ year of study did not. Only course of study of the students significantly influenced the way they rated their lecturers‟ personality (F (19, 1565) =1.67, p < .05), while both age and year of study did not show significant differences in lecturers‟ personality. In terms of preparation, lecturers‟ rank (F (6, 1578) =2.87: p < .05) and years of experience (F (11, 1573) = 1.83: p < .05) significantly influenced their teaching effectiveness. Students, especially in the colleges of education can be relied upon to evaluate their lecturers‟ teaching effectiveness. Students‟ variables like course and year of study influence their pattern of ratings. The use of SETES-CE could be considered for adoption in the evaluation of teaching effectiveness of lecturers in Colleges of Education in Nigeria 1 results 1
- Teaching effectiveness scale 1 results 1
- This paper examines the temporal trend, that is, the growth in production subcontracting over the years in Nigeria. The relevant concepts are production subcontracting and diffusion of innovation. Data were collected from the sixty-eight contracting firms among 15 industrial estate/areas in the Lagos region. This paper shows that the growth in the number of contractors/subcontractors, which was gradual at the initial stage, became more rapid thereafter. The results of the regression/correlation analyses carried out, using the year as the dependent variable and the number of contractors/subcontractors as the independent variable are significant at 0.0001 per cent level at both the aggregate level and the level of the Lagos region. The study shows that if encouraged, production subcontracting could be used to enhance the industrial development of Nigeria. 1 results 1
- Threshold oil price 1 results 1
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