Проектирование и исследование режимов работы ГИН в среде Micro-Cap

Выпускная квалификационная работа объемом 90 страниц, 42 рисунок, 14 таблиц, 15 использованных источников, 3 приложения.Final qualifying work of 90 pages, 42 picture, 14 tables, 15 sources used, 3 applications

Striking Photospheric Abundance Anomalies in Blue Horizontal-Branch Stars in Globular Cluster M13

High-resolution optical spectra of thirteen blue horizontal-branch (BHB) stars in the globular cluster M13 show enormous deviations in element abundances from the expected cluster metallicity. In the hotter stars (T_eff > 12000 K), helium is depleted by factors of 10 to 100 below solar, while iron is enhanced to three times the solar abundance, two orders of magnitude above the canonical metallicity [Fe/H] ~= -1.5 dex for this globular cluster. Nitrogen, phosphorus, and chromium exhibit even more pronounced enhancements, and other metals are also mildly overabundant, with the exception of magnesium, which stays very near the expected cluster metallicity. These photospheric anomalies are most likely due to diffusion --- gravitational settling of helium, and radiative levitation of the other elements --- in the stable radiative atmospheres of these hot stars. The effects of these mechanisms may have some impact on the photometric morphology of the cluster's horizontal branch and on estimates of its age and distance.Comment: 11 pages, 1 Postscript figure, uses aaspp4.sty, accepted for publication in ApJ Letter

Ignition of typical gel-fuel at local heating

In this paper, we determined the ignition delay for a typical gel fuel by metal particles of various form. Also, determined the ignition delay times by varying the initial particle temperature

Safety measures in the workplace: a case study of Federal Road Safety Corps (FRSC) vehicle plate manufacturing plant, Ojodu – Lagos, Nigeria

Introduction: Hazards associated with vehicle number plate manufacturing processes in developing countries have not been well elucidated. There is a need to investigate hazards in the vehicle number plate manufacturing plant. The study aimed to identify self-reported hazards in the vehicle plate manufacturing factory, explore their effect on workers’ health and recommend mitigation strategies. Methods: A descriptive cross-sectional study of workers in the vehicle plate manufacturing plant was done to identify hazards, protective measures and self-reported effects on workers’ health. Biochemical analysis of blood samples was also done and outliers were noted. ANOVA test was performed to determine differences in mean values of selected biochemical parameters. A p-value of less than 0.05 was considered statistically significant. Results: Exposure to toxic chemicals 38(69%), excessive noise 36 (65%) and heat 28 (51%) were the major hazards in the factory. Major health problems were stress and fatigue 41 (71%), skin disorders 28 (51%), respiratory problems 18 (33%) and hearing loss 16 (29%). More than one quarter, 17 (30 %) of the workers admitted not using personal protective equipment (PPE) regularly. Periodic medical tests were not done for 13 (24%) of the workers. Potassium (3%), Urea (10%),   Creatinine (7%), Aspartate transaminase (18%) and Alanine transaminase (8%) were elevated among the workers but no significant association could be established between elevated levels and work post. Conclusion: Workers in the plate number manufacturing plant were mostly exposed to toxic chemicals and noise. Elevated electrolyte levels cut across departments.   There is a need for better enforcement of safety rules, and periodic medical examinations should be conducted more consistently

Ion-Mediated Structural Discontinuities in Phospholipid Vesicles

Despite intense research, methods for controlling soft matter's spontaneous self-assembly in-to well-defined layers remain a significant challenge. We observed ion-induced structural disconti-nuities of phospholipid vesicles that can be exploited for controlled self-assembly of soft materials. We used dynamic light scattering, zeta-potential measurement, cryo-electron microscopy, small-angle X-ray, and small-angle neutron scattering. All the experimental observations indicate that de-clining solvent quality and increasing osmotic pressure direct lipids to expel preferentially to the inner compartment. Upon reaching a critical concentration, excess lipids can form a new bilayer. This spontaneous self-assembly process causes simultaneous shrinkage of the aqueous core and expansion of the vesicle. This approach opens an intriguing path for controlling the self-assembly of bioinspired colloids, which can also serve as a vehicle to control the polymerization of multilayer polymeric systems

Perceived Influence of Lecturers’ Rating of Accreditation Exercise on Quality Assurance in Universities in South East States, Nigeria

This study examined perceived influence of lecturers’ ratings of accreditation exercise on quality assurance in universities in south east states in Nigeria. The study was carried out using two research questions and two hypotheses. The research design adopted for the study is a descriptive survey design which involved inferential approach. The population of the study comprise 3,843 members of academic staff of the five public state owned universities in south east geo-political zone of Nigeria. The sample for this study is 384 academic staff from the five state universities in the South East Geo-Political Zone of Nigeria. Proportionate cluster random sampling technique was used as the sampling technique for this study. The instrument used for collecting the data for the study is a rating scale titled: “Extent of Accreditation Exercise Influence on Quality Assurance Scale (EAEIQAS)”. The instrument was validated by two experts in Measurement and Evaluation and three experts in Educational Management. The reliability index of 0.80 was gotten for the instrument using Cronbach alpha statistics. The research questions were answered using mean score and standard deviation statistics while the hypotheses were tested using one sample t-test statistics at 0.05 level of significance. The major findings are that the lecturers’ ratings of accreditation exercise on academic content of state universities in South East is high and significantly above average, and the ratings of accreditation exercise on staffing of state universities in South East is high and significantly above average. Based on the findings, it was recommended among others that the universities should improve more on their academic content as this will help to inculcate the required academic knowledge and skills to her graduates as a sign of quality indicator

Imaging markers of disability in aquaporin-4 immunoglobulin G seropositive neuromyelitis optica: a graph theory study

Neuromyelitis optica spectrum disorders lack imaging biomarkers associated with disease course and supporting prognosis. This complex and heterogeneous set of disorders affects many regions of the central nervous system, including the spinal cord and visual pathway. Here, we use graph theory-based multimodal network analysis to investigate hypothesis-free mixed networks and associations between clinical disease with neuroimaging markers in 40 aquaporin-4-immunoglobulin G antibody seropositive patients (age = 48.16 ± 14.3 years, female:male = 36:4) and 31 healthy controls (age = 45.92 ± 13.3 years, female:male = 24:7). Magnetic resonance imaging measures included total brain and deep grey matter volumes, cortical thickness and spinal cord atrophy. Optical coherence tomography measures of the retina and clinical measures comprised of clinical attack types and expanded disability status scale were also utilized. For multimodal network analysis, all measures were introduced as nodes and tested for directed connectivity from clinical attack types and disease duration to systematic imaging and clinical disability measures. Analysis of variance, with group interactions, gave weights and significance for each nodal association (hyperedges). Connectivity matrices from 80% and 95% F-distribution networks were analyzed and revealed the number of combined attack types and disease duration as the most connected nodes, directly affecting changes in several regions of the central nervous system. Subsequent multivariable regression models, including interaction effects with clinical parameters, identified associations between decreased nucleus accumbens (β = −0.85, P = 0.021) and caudate nucleus (β = −0.61, P = 0.011) volumes with higher combined attack type count and longer disease duration, respectively. We also confirmed previously reported associations between spinal cord atrophy with increased number of clinical myelitis attacks. Age was the most important factor associated with normalized brain volume, pallidum volume, cortical thickness and the expanded disability status scale score. The identified imaging biomarker candidates warrant further investigation in larger-scale studies. Graph theory-based multimodal networks allow for connectivity and interaction analysis, where this method may be applied in other complex heterogeneous disease investigations with different outcome measures

Adaptive synchronization in delay-coupled networks of Stuart-Landau oscillators

We consider networks of delay-coupled Stuart-Landau oscillators. In these systems, the coupling phase has been found to be a crucial control parameter. By proper choice of this parameter one can switch between different synchronous oscillatory states of the network. Applying the speed-gradient method, we derive an adaptive algorithm for an automatic adjustment of the coupling phase such that a desired state can be selected from an otherwise multistable regime. We propose goal functions based on both the difference of the oscillators and a generalized order parameter and demonstrate that the speed-gradient method allows one to find appropriate coupling phases with which different states of synchronization, e.g., in-phase oscillation, splay or various cluster states, can be selected.Comment: 8 pages, 7 figure