Perception of Constructivist Learning Environment: Gender and School Type Differences in Siaya County, Kenya

Aims: The study aimed at investigating gender and school type differences in perception of Biology constructivist learning environment. Study Design: The study adopted a survey design. Place and Duration of Study: The study was carried out in Siaya County in Kenya between October and November 2013 during the school term. Methodology: The study sampled 815 grade 12 students (466 boys, 349 girls, 399 high achieving students and 416 low achieving students). Two instruments were used viz. Learners Perception Questionnaire (LPQ) and Learners Interview Guide (LIG). The data were analyzed using descriptive statistics, independent sample t-tests, two-way MANOVA and two-way ANOVA. The qualitative data were used to explain quantitative data. Results: The findings show that there existed statistically significant difference in perception between the low achieving schools and high achieving schools in favor of the low achieving schools in all the subscales of SPQ (p =.00) and statistically significant gender (Hotelling’s trace = .131, F = 21.19, p = .000) and school type (Hotelling’s trace = .269, F = 43.48, p = .000) differences with respect to the collective dimensions of the SPQ. The results also revealed that there was an interaction between gender and school type and vice versa with respect to collective dimensions of the SPQ (Hotelling’s trace = .176, F = 23.40, p = .000). Conclusion: It is concluded that low achieving schools have higher preference for a constructivist learning environment than high achieving schools and there exists gender and school type differences in perception of constructivist learning environment in favor of girls and low achieving schools respectively. The implications of the findings are discussed

Effective anisotropies and energy barriers of magnetic nanoparticles with Néel surface anisotropy

Magnetic nanoparticles with Néel surface anisotropy, different internal structures, surface arrangements, and elongation are modeled as many-spin systems. The results suggest that the energy of many-spin nanoparticles cut from cubic lattices can be represented by an effective one-spin potential containing uniaxial and cubic anisotropies. It is shown that the values and signs of the corresponding constants depend strongly on the particle's surface arrangement, internal structure, and shape. Particles cut from a simple cubic lattice have the opposite sign of the effective cubic term, as compared to particles cut from the face-centered cubic lattice. Furthermore, other remarkable phenomena are observed in nanoparticles with relatively strong surface effects. (i) In elongated particles surface effects can change the sign of the uniaxial anisotropy. (ii) In symmetric particles (spherical and truncated octahedral) with cubic core anisotropy surface effects can change the sing of the latter. We also show that the competition between the core and surface anisotropies leads to a new energy that contributes to both the second- and fourth-order effective anisotropies. We evaluate energy barriers ΔE as functions of the strength of the surface anisotropy and the particle size. The results are analyzed with the help of the effective one-spin potential, which allows us to assess the consistency of the widely used formula ΔE/V= K∞ +6 Ks /D, where K∞ is the core anisotropy constant, Ks is a phenomenological constant related to surface anisotropy, and D is the particle's diameter. We show that the energy barriers are consistent with this formula only for elongated particles for which the surface contribution to the effective uniaxial anisotropy scales with the surface and is linear in the constant of the Néel surface anisotropy. © 2007 The American Physical Society

Rb induces a proliferative arrest and curtails Brn-2 expression in retinoblastoma cells

BACKGROUND: Retinoblastoma is caused by loss of the Rb protein in early retinal cells. Although numerous Rb functions have been identified, Rb effects that specifically relate to the suppression of retinoblastoma have not been defined. RESULTS: In this study, we examined the effects of restoring Rb to Y79 retinoblastoma cells, using novel retroviral and lentiviral vectors that co-express green fluorescent protein (GFP). The lentiviral vector permitted transduction with sufficient efficiency to perform biochemical analyses. Wild type Rb (Rb(WT)) and to a lesser extent the low penetrance mutant Rb(661W )induced a G0/G1 arrest associated with induction of p27(KIP1 )and repression of cyclin E1 and cyclin E2. Microarray analyses revealed that in addition to down-regulating E2F-responsive genes, Rb repressed expression of Brn-2 (POU3F2), which is implicated as an important transcriptional regulator in retinal progenitor cells and other neuroendocrine cell types. The repression of Brn-2 was a specific Rb effect, as ectopic p27 induced a G0/G1 block, but enhanced, rather than repressed, Brn-2 expression. CONCLUSION: In addition to Rb effects that occur in many cell types, Rb regulates a gene that selectively governs the behavior of late retinal progenitors and related cells

Experimental analysis, predictive modelling and optimization of some physical and mechanical properties of aluminium 6063 alloy based composites reinforced with corn cob ash.

In the present work, aluminium alloy 6063 reinforced with various weight percentages of corncob ash (CCA) particles (2.5%, 5%, 7.5%, 10%, 12.5% and 15%) were prepared using stir casting process.  Some physical and mechanical properties (density, % porosity, hardness, wear index, tensile strength and impact strength) of the produced composite were characterized and compared with that of the matrix alloy.  Corncob ash reinforcements were observed to have been distributed homogeneously in the Aluminium Matrix with pockets of reinforcement particles agglomeration. The reinforcement of CCA particles improved the hardness, wear index and the density of the produced composite over that of the base alloy. There was a reduction in the tensile and impact strengths of the composites compared to the unreinforced matrix alloy. Statistical evaluation and optimization using mixture design of the Design-Expert software package (Stat-Ease) revealed the optimal concentrations of the matrix and the reinforcement mixture and their effects on the studied properties of the developed composites. Regression models were developed for predicting and optimizing the various physical and mechanical properties of the composites. Optimization solution indicates that optimal mixture components of 92.081 and 7.919% (matrix and reinforcement wt%) will yield optimal composite properties’ responses. Based on the improved hardness, wear-resistance and low density of the CCA reinforced AA6063 base composites produced could be employed in the production of automotive components requiring lightweight, load-bearing and wear-resistant composites

Experiences of HIV-related stigma among HIV-positive older persons in Uganda--a mixed methods analysis.

There is limited data on stigma among older HIV-infected adults in sub-Saharan Africa. We describe the experiences of stigma and disclosure in a cohort of HIV-positive older people in Uganda. Using data from the Wellbeing of Older Peoples' Study of Kalungu (rural site) and Wakiso district (peri-urban site) residents, we measured self-reported stigma levels for 183 respondents (94 on antiretroviral therapy (ART); 88, not on ART) using a stigma score generated using three questions on stigma perceptions where 0 meant no stigma at all and 100 was maximum stigma. Based on two questions on disclosure, an overall score was computed. High disclosure was assigned to those who often or very often disclosed to the family and were never or seldom afraid to disclose elsewhere. We examined the experiences of HIV stigma of 25 adults (52% females) using semi-structured, open-ended interviews and monthly oral diaries over one year. Mean age of the respondents was 70 years (range 60-80 years) and 80% of all respondents were enrolled in ART. Interview transcripts were analysed using thematic content analysis. Overall, 55% of respondents had a high disclosure score, meaning they disclosed easily, and 47% had a high stigma score. The stigma scores were similar among those with high and low disclosure scores. In multivariate analyses with disclosure and stigma scores as dependent variables none of the respondents' characteristics had a significant effect at the 5% level. Qualitative data revealed that stigma ranges from: (1) perceptions (relatively passive, but leading to behaviour such as gossip, especially if not intended maliciously); to (2) discriminatory behaviour (active or enacted stigma; from malicious gossip to outright discrimination). Despite the relatively high levels of disclosure, older people suffer from high levels of stigma of various forms apart from HIV-related stigma. Efforts to assess for different forms of stigma at an individual level deserve greater attention from service providers and researchers, and must be context specific

Investigating the Dynamic Nexus between Non-Oil Taxes and Economic Growth in Nigeria: An ARDL Approach

This paper examines the dynamic nexus between non-oil taxes and economic growth in Nigeria. The volatile nature of oil prices has threatened the balance and stability of public expenditure and the budgetary system as a tool for stimulating growth in Nigeria, hence the motivation to look into the prospects of the non-oil sector as a driver of growth.  Secondary data covering the period 1994-2019 was used for this study. This period is selected to ensure that there are no missing data especially for VAT which began in 1994, therefore, using earlier periods will introduce missing data into the estimation. Standard time series econometric techniques were utilized in the study such as descriptive analysis, unit root testing, co-integration test and granger causality testing. The Autoregressive distributive lag model (ARDL) was then employed in the model estimation. The long-run results show the effect of non-oil taxes on economic growth in Nigeria and observed that the effect of log (VAT) on economic growth is negative. Specifically, the result indicates that an increase in VAT revenue by 1% results in decline in GDP by about 0.21% and the result is significant at 5%. In the case of CED, the result shows that the economic growth is impacted positively. Specifically, a 1% rise in CED revenue stimulates growth by 0.113%, and the result is significant at 10%. Also, the effect of PIT revenue on growth is negative and significant at 5% and specifically, a 1% increase in PIT revenue results in decline in economic growth by 0.599%. The result shows that CIT has a positive impact on economic growth, and it is significant at 5%. This implies that a 1% increase in CIT revenue increases economic growth by 0.5757%. The findings of the above have the following implications. First, the negative effect of PIT and VAT on growth suggests that there is a need for fiscal authorities to re-examine these taxes and hence high VAT and PIT rates may be counter-productive for growth. Secondly, CIT and CED show positive growth effects and hence there is a need for effective and accountable expenditure framework that will ensure optimization of public expenditure in this regards

Trends in female sterilization in north central Nigeria

Background: Contraception is key to the reduction of maternal mortality. Tubal ligation is a good option for women seeking out a safe, effective, permanent and convenient form of contraceptive. However, due to variety of reasons, there is aversion to it especially in developing world. The objective of this study was to determine the trends, uptake, socio-demographic characteristics of acceptors, indications and complications of bilateral tubal ligation (BTL) in our environment.Methods: A retrospective study of BTL at UATH was conducted over a five year period, from 1 January 2015 to 31 December 2019. The records of women who had BTL were retrieved from the medical records department, family planning clinic, and the theatre. The data was analyzed using SPSS 21.Results: The mean age and parity were 36.0±4.0 and 5.0±2.0 respectively. The incidence of BTL was 1.3%. Majority of those that had BTL had at least secondary level of education 100 (83.4%) and 58 (48.3%) were grand multiparous. Majority of cases 87 (72.5%) were done during caesarean section/laparotomy. Postpartum BTL accounted for 15.0%, while interval BTL accounted for 12.5%. Completed family size was the commonest indication 48.3%. No client came back with regrets. There was one case of failed BTL.Conclusions: BTL is a safe and effective method of sterilization. There is an increasing trend in utilization of BTL however the rate is still low

Anaemia in HIV positive mothers on antiretroviral therapy for prevention of mother-to-child transmission HIV in a tertiary health institution in North Central Nigeria

Background: Anaemia in pregnancy and HIV infection are two common public health issues in sub-Saharan African with Nigeria bearing the greatest burden. The duo occurring together poses a higher risk of morbidity and mortality for both the foetus and the mother. We therefore conducted this study to determine the burden of anaemia and other haematological abnormalities among HIV positive pregnant mothers on antiretroviral therapy who attended antenatal clinical services in our health institution.Methods: A 10-year retrospective review from January 2010 to December 2019 of medical records of HIV positive mothers on highly anti-retroviral therapy in attendance for antenatal clinical services in our health institution was carried out for the above objectives. Information extracted were, age, HIV status, gestational age at delivery, type of antiretroviral drugs used, duration of use, haemoglobin level, platelet, and complete blood count at booking of the positive mothers.Results: Of a total of 330 HIV positive mothers seen during the review period, 82.7% were from rural communities, 88.8% were from middle socio-economic class, 80.0% were Christians, and 80.3% started their highly active antiretroviral therapy before their index pregnancy. Most, 51.5% and 42.7% were on zidovudine, lamivudine and nevirapine, and tenofovir with lamivudine and lopinavir boasted ritonavir combinations, while 94.2% were on 1st line antiretroviral medication. Their mean age, gestational age at delivery, and parity were 31.11±4.7 years, 38.57±3.1 weeks, and 2.0±1.6 respectively. The prevalence of anaemia, thrombocytopenia and leucopoenia were 36.1%, 4.8%, and 6.7% respectively while their mean CD4 cell count and viral loads at the point of booking were 543.63±283.7 cells/μl, and 2953.02±1619.9 copies/ml. The two maternal variables that showed significant relationship with haemoglobin concentration of <10 gm/dl was mother’s level of education x2=6.29, p=0.043, and her socio=economic class, x2=10.162, p=0.006.Conclusions: There is high burden of anaemia among HIV positive mothers on antiretroviral therapy in our environment. The prevalence of thrombocytopenia and leucopoenia was much lower. The burden of maternal anaemia was associated with maternal level of education and her socio-economic class

An introduction to Trends in Extreme Weather and Climate Events: Observations, Socioeconomic Impacts, Terrestrial Ecological Impacts, and Model Projections

Weather and climatic extremes can have serious and damaging effects on human society and infrastructure as well as on ecosystems and wildlife. Thus, they are usually the main focus of attention of the news media in reports on climate. There are some indications from observations concerning how climatic extremes may have changed in the past. Climate models show how they could change in the future either due to natural climate fluctuations or under conditions of greenhouse gas-induced warming. These observed and modeled changes relate directly to the understanding of socioeconomic and ecological impacts related to extremes.Integrative Biolog

Pallasite paleomagnetism: Quiescence of a core dynamo

Recent paleomagnetic studies of two Main Group pallasites, the Imilac and Esquel, have found evidence for a strong, late-stage magnetic field on the parent body. It has been hypothesized that this magnetic field was generated by a core dynamo, driven by compositional convection during core solidification. Cooling models suggest that the onset of core solidification occurred ∼200 Ma after planetary accretion. Prior to core solidification, a core dynamo may have been generated by thermal convection; however a thermal dynamo is predicted to be short-lived, with a duration of ∼10 Ma to ∼40 Ma after planetary accretion. These models predict, therefore, a period of quiescence between the thermally driven dynamo and the compositionally driven dynamo, when no core dynamo should be active. To test this hypothesis, we have measured the magnetic remanence recorded by the Marjalahti and Brenham pallasites, which based on cooling-rate data locked in any magnetic field signals present ∼95 Ma to ∼135 Ma after planetary accretion, before core solidification began. The cloudy zone, a region of nanoscale tetrataenite islands within a Fe-rich matrix was imaged using X-ray photoemission electron microscopy. The recovered distribution of magnetisation within the cloudy zone suggests that the Marjalahti and Brenham experienced a very weak magnetic field, which may have been induced by a crustal remanence, consistent with the predicted lack of an active core dynamo at this time. We show that the transition from a quiescent period to an active, compositionally driven dynamo has a distinctive paleomagnetic signature, which may be a crucial tool for constraining the time of core solidification on differentiated bodies, including Earth