A Hybrid Time-Scaling Transformation for Time-Delay Optimal Control Problems

In this paper, we consider a class of nonlinear time-delay optimal control problems with canonical equality and inequality constraints. We propose a new computational approach, which combines the control parameterization technique with a hybrid time-scaling strategy, for solving this class of optimal control problems. The proposed approach involves approximating the control variables by piecewise constant functions, whose heights and switching times are decision variables to be optimized. Then, the resulting problem with varying switching times is transformed, via a new hybrid time-scaling strategy, into an equivalent problem with fixed switching times, which is much preferred for numerical computation. Our new time-scaling strategy is hybrid in the sense that it is related to two coupled time-delay systems—one defined on the original time scale, in which the switching times are variable, the other defined on the new time scale, in which the switching times are fixed. This is different from the conventional time-scaling transformation widely used in the literature, which is not applicable to systems with time-delays. To demonstrate the effectiveness of the proposed approach, we solve four numerical examples. The results show that the costs obtained by our new approach are lower, when compared with those obtained by existing optimal control methods

Consequences of Eukaryotic Enhancer Architecture for Gene Expression Dynamics, Development, and Fitness

The regulatory logic of time- and tissue-specific gene expression has mostly been dissected in the context of the smallest DNA fragments that, when isolated, recapitulate native expression in reporter assays. It is not known if the genomic sequences surrounding such fragments, often evolutionarily conserved, have any biological function or not. Using an enhancer of the even-skipped gene of Drosophila as a model, we investigate the functional significance of the genomic sequences surrounding empirically identified enhancers. A 480 bp long “minimal stripe element” is able to drive even-skipped expression in the second of seven stripes but is embedded in a larger region of 800 bp containing evolutionarily conserved binding sites for required transcription factors. To assess the overall fitness contribution made by these binding sites in the native genomic context, we employed a gene-replacement strategy in which whole-locus transgenes, capable of rescuing even-skipped- lethality to adulthood, were substituted for the native gene. The molecular phenotypes were characterized by tagging Even-skipped with a fluorescent protein and monitoring gene expression dynamics in living embryos. We used recombineering to excise the sequences surrounding the minimal enhancer and site-specific transgenesis to create co-isogenic strains differing only in their stripe 2 sequences. Remarkably, the flanking sequences were dispensable for viability, proving the sufficiency of the minimal element for biological function under normal conditions. These sequences are required for robustness to genetic and environmental perturbation instead. The mutant enhancers had measurable sex- and dose-dependent effects on viability. At the molecular level, the mutants showed a destabilization of stripe placement and improper activation of downstream genes. Finally, we demonstrate through live measurements that the peripheral sequences are required for temperature compensation. These results imply that seemingly redundant regulatory sequences beyond the minimal enhancer are necessary for robust gene expression and that “robustness” itself must be an evolved characteristic of the wild-type enhancer

Cardiac Troponin T and Creatine Kinase MB Fraction Levels Among Patients with Acute Ischemic Stroke in Nigeria

Background: Stroke has been a global burden, with increasing morbidity and mortality. Serum cardiac troponin t (cTnT) and creatine kinase (CK-MB) fraction are reported to be elevated in patients admitted with acute ischaemic stroke and high level of these biomarkers indicated more severe stroke and neurologic deficit in some of the patients. Objective: To evaluate the serum levels cardiac troponin t (cTnT) and creatine kinase MB fraction (CK-MB) in patients with acute ischaemic stroke and relate the analytes to severity of stroke. Method: Patients with clinical diagnosis of ischaemic stroke diagnosed, confirmed by brain Computerized Tomography scan and equal number of apparently healthy age and sex-matched were recruited. Serum cardiac troponin t (cTnT) and creatine kinase MB fraction (CK-MB) were analysed using ELISA method and Stroke severity was determined using National Institute of Health Stroke Score (NIHSS). Results: Mean serum cardiac troponin t (cTnT) and creatine kinase MB fraction (CK-MB) in stroke patients were found to be higher than age sex matched control (p<0.05). NIHS Score of 12.2 ± 5.43 and 9.78 ± 3.97 were observed in Patients with elevated and normal cTnT respectively (p=0.009) while NIHS Score were similar in patients with elevated and normal CK-MB (p = 0.772). Conclusion: The mean values of serum cTnT and CK-MB were higher in acute ischaemic stroke patients compared to controls. Serum cardiac Troponin t level may be a significant biomarker of the severity of stroke.Keywords: Creatine kinase MB, Nigeria, serum cardiac troponin T, strok

Students’ perceptions of Education for Sustainable Development (ESD) to Achieve SDG 4 in Indonesia: a case study of Universitas Islam Riau

Sustainable development at higher education level plays an important role in achieving the Sustainable Development Goals (SDGs). Higher education holds a great responsibility to increase the awareness and knowledge of students who will manage and develop resources. For the purpose of the sustainability of resources, awareness and knowledge of sustainable development are needed. This knowledge can be conveyed through Education for Sustainable Development (ESD) to achieve high education quality and equal access to education for women and men. Perception ofESDmust be studied to gather information about the facts, problems and challenges faced by Universitas Islam Riau (UIR) to achieve SDGs, especially SDG 4 (Quality Education). This study aims to identify the perception students of both genders at Universitas Islam Riau (UIR) hold about Education for Sustainable Development (ESD). This research is a descriptive survey research conducted using a quantitative approach. There were 99 respondents in this study, Consisting of 43 men and 56 women. Data was collected by distributing questionnaires containing 70 statements, while processing of questionnaire data was done through the frequency analysis formula. Generally, the results of social, environmental and economic aspects in the ‘Good’ category are between 71.08 and 78.75%. Based on gender, both female and male students scored a higher percentage in economic aspect than other aspects, whereby female students scored 77.76%, whereas it was 76.50% for male students. Based on this study, it can be concluded that the students of Universitas Islam Riau have a good perception of Education for Sustainable Development. Therefore, the University must begin to apply the concept of sustainable development in every aspect in order to contribute to achieving SDG 4