Age-Associated Changes in Voltage-Gated Sodium Channels Within the Right Atrium Predispose the Elderly to Atrial Fibrillation

Atrial Fibrillation (AF) is the most common cardiac arrhythmia worldwide with sufferers of the condition facing significant morbidity and mortality. Ageing alone is identified as the most significant risk factor for developing the arrhythmia. As such, an ageing global population has, and will continue to give rise to a marked prevalence of AF, placing enormous pressure on healthcare systems around the world. Ionic remodelling of sodium channels has been observed in animal studies with regards to the ageing process which drive the arrhythmogenic pathology, with parallel observations made with regards to AF. This study will examine, and potentially unify, the narratives of ionic remodelling in AF and ageing, focusing specifically on the expression of two voltage-gated sodium channel (VGSC) isoforms within the human heart; Nav1.5 & Nav1.8. The former being the native cardiac isoform and principal driver for phase 0 of the action potential, and the latter a neuronal isoform implicated in pathological late currents which predispose the cardiomyocyte to electrical instability. This study involved sampling human right atrial appendage from patients undergoing routine cardiac surgery at Castle Hill Hospital. With increasing age, expression of Nav1.5 declined with a Pearson’s correlation coefficient of -0.25. Comparing the extremes in age of these samples, protein expression was decreased by 18.8% in the older group (P=0.18). The inverse trend was noted with regards to Nav1.8 with a positive correlation of +0.259. When comparing the extremes of age an increase of 32% was observed (P=0.039). These results suggest that the ageing process remodels the human heart in a manner which diminishes the capacity for sodium ion influx critical for conduction during action potential upstroke, meanwhile upregulating ion channels which enhance the aberrant late currents. To investigate the ionic landscape of cardiac tissue in AF, patients with the arrhythmia were matched on age with patients in sinus rhythm. AF patients were found to have significantly reduced expression of Nav1.5 (P=<0.05). These results suggest that the loss of native cardiac sodium channels may be a key step in the pathophysiology of cardiac arrhythmia in humans, and a process in which the ageing heart undergoes which underpins development of AF. In order to investigate the precise mechanics modulating the ionic redistribution observed, this study examined the role JNK may have as a potential regulator of sodium channel expression in the human heart. JNK has been suggested as having a strong influence in the expression of other ion channel proteins-specifically Cx43. Total expression of JNK was found to be 56 % greater in the oldest population compared to younger patients (P=0.05). Examination of the direct role increased levels of JNK may have on VGSC expression was investigated using pharmacological manipulation of this pathway through Anisomycin (JNK activator) and SP600125 (JNK inhibitor). Subjectively, it has been noted that inhibition of JNK markedly reduced the expression of Nav1.8, whereas upregulation of this protein seemed to increase the density of expression of the neuronal isoform

Technical Efficiency of Small Scale Maize Production inMasaiti District, Zambia: A Stochastic Frontier Approach

Maize is a major staple food crop of Zambia dominantly produced by smallholder farmers.  This paper examines technical efficiency of smallholder maize farmers in Zambia.  Data were collected using a structured questionnaire administrated to 100 randomly selected smallholder maize farmers in Masaiti district in Zambia.  The data were analyzed using descriptive statistics and a stochastic frontier production function approach.  The estimated stochastic frontier Cobb-Douglas production function showed that maize land size and fertilizer were the significant factors that affected maize production.   The efficiency analysis results indicated that farm level technical efficiency ranged between 52.2% and 93.2% with a mean of 79.6%.  This indicates that overall, there is potential to increase maize production among smallholder farmers in the study area by 20.4% through efficient use of present technology.  The results of the inefficiency model indicate that age of farmer, cooperative membership which implies access to fertilizer, and farm size, have significant positive effects of efficiency.  The seed types used, rotation practices, and education level of the farmer had negative effects on technical efficiency.  The policy implications are that to improve farm efficiency efforts should focus on access to improved inputs such as certified seed and fertilizer),  information on agronomic practices, and farmer’s education. Keywords: technical efficiency, stochastic production frontier, smallholder, maize, Zambia

Conformal Inference for Online Prediction with Arbitrary Distribution Shifts

We consider the problem of forming prediction sets in an online setting where the distribution generating the data is allowed to vary over time. Previous approaches to this problem suffer from over-weighting historical data and thus may fail to quickly react to the underlying dynamics. Here we correct this issue and develop a novel procedure with provably small regret over all local time intervals of a given width. We achieve this by modifying the adaptive conformal inference (ACI) algorithm of Gibbs and Cand\`{e}s (2021) to contain an additional step in which the step-size parameter of ACI's gradient descent update is tuned over time. Crucially, this means that unlike ACI, which requires knowledge of the rate of change of the data-generating mechanism, our new procedure is adaptive to both the size and type of the distribution shift. Our methods are highly flexible and can be used in combination with any baseline predictive algorithm that produces point estimates or estimated quantiles of the target without the need for distributional assumptions. We test our techniques on two real-world datasets aimed at predicting stock market volatility and COVID-19 case counts and find that they are robust and adaptive to real-world distribution shifts.Comment: 35 pages, 15 figure

Teacher Preparation: The Case of the Two Years “In” and One Year “Out” Policy of the In-In-Out Programme of Colleges of Education in Ghana

The study investigated into the ‘In-In-Out’ Programme of the Colleges of Education in some selected communities in the Aowin District in Ghana and their implication for teacher preparation. The sampling technique used was purposive and simple random sampling. The study involved 144 mentees, 24 Link-Tutors, 24 Lead Mentors and Mentors, 16 Opinion leaders, the District Director of Education and the Principal of Enchi Training College. Data was collected by the use of questionnaires. Major findings of the study are (a) enough preparation are given during the two years of on-campus training in the college, (b) some mentors were not up to task in supporting mentees. The study thus recommends that, all stakeholders should join hands to ensure the success and smooth running of the programme. Key-words: Teacher education. Teacher trainee. Teacher preparation. In-In-Out policy.  Colleges of Education

The impact of inward FDI on output growth volatility: A country-sector analysis

Abstract While existing literature points to a positive impact of FDI on host countries' growth, little is known about how inward FDI contributes to economic volatility in the host country. In this paper, we investigate the FDI-output growth volatility nexus focusing on manufacturing sectors of OECD countries over the period 1990 to 2015. We document a positive and statistically significant relationship between inward FDI stock and sectoral output volatility. We also show that the impact of inward FDI stock in downstream activities on volatility is larger compared to that of inward FDI stock in upstream activities which is not significant. Additionally, we find that the positive relationship between FDI and volatility is stronger in high capital-intensive industries. These results are robust to the use of a measure of FDI targeting practices

The Effect of the “Out”-Programme of the “In-In-Out” Policy of Teacher Education in Ghana: Implication for Human Resource Development

The effects of the ‘Out’ Policy of the ‘In-In-Out’ Programme of Colleges of Education in some selected communities in the Aowin and Suaman Districts and their implication for Human Resource Development was investigated. It primarily explored the effects of the programme on the professional preparation of the teacher trainees, the effects on the schools of attachment and the communities of attachment. The study involved 144 mentees, 24 Link-Tutors, 24 Lead Mentors and Mentors, 16 Opinion leaders, the District Director of Education and the Principal of Enchi Training College. Descriptive design was adopted and a questionnaire was the main data collection tool used; supported with interviews. It was concluded that mentees faced the problem of inadequate supervisory practices by their mentors. The mentees faced a number of socio-economic challenges that range from logistic and the lack of community support on the programme. The study thus recommends that, all stakeholders should join hands to ensure the success and smooth running of the programme. Keywords: Teacher, Teacher training, Teacher education, Out-programme, Human resource, Human resource development

Teachers' Awareness and Utilization of L2 Research Findings: Implications for L2 Teaching in Ondo State, Nigeria

Despite the number of research outputs from various post-graduate students across the country, Nigeria educational system is bedeviled with issues of mass failure in external examinations. This mismatch between students’ performances and the jillions of researches which are supposed to solve issues of mass failure among students informs this study. This study, therefore, examined teachers’ awareness and utilization of L2 research findings and implication for L2 teaching in Ondo State, Nigeria. Descriptive survey research design was adopted for this study. The simple random sampling technique was used to select forty-three L2 teachers form three local government areas in Ondo State, Nigeria. The instruments used for data collection was a questionnaire entitled Teachers’ Awareness and Utilization of L2 Research Findings (TAURFIQ). Two research questions were answered and two hypotheses were tested at 0.05 level of significance. Data were analysed using descriptive statistics and Pearson Product Moment Correlation Coefficient. The study found out that L2 teachers are moderately aware of L2 research findings. Also, the study indicated that there was no significant relationship between L2 teachers’ academic qualification and extent of L2 research awareness and utilization. Based on the findings of the study, it was recommended that universities should organize seminars for L2 teachers in order to discuss the applications of the various research findings in the classroom

Financial Deepening and Entrepreneurial Growth in Nigeria

The study examined the relationship between financial deepening and entrepreneurial growth in Nigeria. It used secondary data collected from Central Bank of Nigeria Statistical Bulletin spanning 1986 to 2016. The study employed Pearson Correlation in establishing relationships between the variables. The results revealed that the ratio of money supply to Gross Domestic Product (M2/GDP) has a positive but not significant relationship with entrepreneurial growth; the ratio of credit to private sector to GDP (CPS/GDP) has a positive (not significant) relationship with entrepreneurial growth; and the ratio of deposit money banks’ branches to GDP (DMBB/GDP) has a negative and significant relationship with entrepreneurial growth. Thus, the study concludes that money supply and credit to private sector are better indicators of financial deepening that can affect entrepreneurial growth positively in Nigeria. The study therefore recommends an effective manipulation of money supply to increase capital flows to the real sector of the economy to trigger entrepreneurial growth. In addition, the Central Bank of Nigeria should further compel commercial banks to grant more credit facilities to entrepreneurs (private sector), including the young graduates and new entrepreneurs without collaterals to enable them invest in viable projects. Also, more venture capital firms should be established to assist in funding small, early-stage, emerging firms that have high growth potentials resulting in creation of value and wealth. Keywords: Financial Deepening, Entrepreneurial Growth, Nigeri