Understanding Opportunities and Barriers to Engineering Student Success and Persistence

The objective of this work was to determine what opportunities and barriers exist for University of Saskatchewan engineering students that may affect persistence and/or academic success. A systematic literature review analyzing factors impacting student retention and attrition provided a framework to guide this study. As the factors identified by the systematic review include both cognitive and non-cognitive factors, a convergent mixed methodology study was chosen. Data was collected from a pilot survey, engineering student demographic databases, a final (full) survey, interviews, and a focus group to assess each factor in the framework. A pragmatic epistemological approach was employed, allowing the researcher to utilize constructivist and post-positivist stances as appropriate, based on the type of data collected/analysis conducted, with corresponding quality criteria indicated explicitly. Upon completion of the convergent analysis of these data sources, the framework was corroborated, suggesting that the factors that impact student attrition/retention include: institutional climate, curriculum, mentorship, peer influence/sense of belonging, faculty engagement, student access to professional role models, a student’s academic achievement history, learning style, intrinsic motivation and attitude, self-efficacy, and demographics (gender, Indigenous ancestry, rural/urban, etc.). Those factors most pronounced in this study’s context were peer influence and sense of belonging, faculty engagement, and student workload/curriculum, and it is recommended that these issues are further investigated by the College of Engineering in order to identify what actions may be taken to optimise student experience with regard to these three factors

Particle simulation of lower hybrid waves in tokamak plasmas

Global particle simulations of the lower hybrid waves have been carried out using fully kinetic ions and drift kinetic electrons with a realistic electron-to-ion mass ratio. The lower hybrid wave frequency, mode structure, and electron Landau damping from the electrostatic simulations agree very well with the analytic theory. Linear simulation of the propagation of a lower hybrid wave-packet in the toroidal geometry shows that the wave propagates faster in the high field side than the low field side, in agreement with a ray tracing calculation. Electromagnetic benchmarks of lower hybrid wave dispersion relation are also carried out. Electromagnetic mode conversion are observed in toroidal geometry, slow waves are launched at the plasma boundary and converts to fast waves at the mode conversion layer, which is consistent with linear theory.Comment: 8 pages, 11 figure

Histamine and tyramine production by bacteria isolated from spoiled sardine (Sardina pilchardus)

Bacterial strains (32) from spoiled sardine were isolated and investigated for their ability to produce histamine and tyramine in histidine and tyrosine decarboxylase broth, respectively by a rapid highperformance liquid chromatography (HPLC) method. The predominant microflora of sardine consisted of the genera Enterobacteriaceae, Pseudomonas, Chryseobacterium, Vibrio, Photobacterium, and Stenotrophomonas. In histidine-enriched broth, the highest levels of histamine were observed in Proteus mirabilis (5201.95 mg/L), followed by Enterobacter cloacae (2333.99 mg/L), whilst the lowest histamine accumulation was found for Kluyvera spp. and Listeria monocytogenes at the level of 0.38 and 0.45 mg/L, respectively. However, Pseudomonas oryzihabitans, Chryseobacterium indologenus and Vibrio vulnificus showed the highest accumulation of tyramine in tyrosine decarboxylase broth with values of 1648.85, 774.20 and 187.96 mg/L, respectively. Serratia liquefaciens produced more than 1000 mg/L putrescine in both enrichment broths, although Serratia rulnidace did not have the ability to produce amines (except for dopamine, serotonin and agmatine) in tyrosine decarboxylase broth. The study results show that P. mirabilis and  Enterobacter cloacae, which were dominantly found in spoiled sardine, were strong amine producers.Keywords: Biogenic amines, histamine, tyramine, spoilage, sardineAfrican Journal of Biotechnology Vol. 12(21), pp. 3288-329

Plasma asymmetry, electron and ion energy distribution function in capacitive discharges excited by tailored waveforms

Using particle-in-cell simulation technique, we investigate the plasma and ionization asymmetry, electron and ion energy distribution function in capacitive discharges excited by tailored waveforms. At a base frequency of 13.56 MHz, three different waveforms namely, sinusoidal, saw-tooth, and square are applied for a constant current density of 50 A/m2 and 5 mTorr argon gas pressure. The simulation results show that the square waveform produces the highest plasma density in the discharge, whereas maximum asymmetry is observed for plasma excited by sawtooth like waveform. Both square and sawtooth waveforms generate multiple beams of high-energy electrons from near to the expanding phase of the sheath edge followed by the high-frequency modulations up to 100 MHz on the instantaneous sheath position. The electron energy distribution function depicts 3 electron temperature and highly elevated tail-end electrons for the square waveform in comparison to the sinusoidal and sawtooth waveform. The ion energy distribution function is bimodal at both powered and grounded electrodes with a large asymmetry and narrow type distribution in the case of sawtooth like waveform. These results suggest that the choice of the waveform is highly critical for achieving maximum asymmetry and plasma density simultaneously in the discharge

A systematic investigation of electric field nonlinearity and field reversal in low pressure capacitive discharges driven by sawtooth-like waveforms

Understanding electron and ion heating phenomenon in capacitively coupled radio-frequency plasma discharges is vital for many plasma processing applications. In this article, using particle-in-cell simulation technique we investigate the collisionless argon discharge excited by temporally asymmetric sawtooth-like waveform. In particular, a systematic study of the electric field nonlinearity and field reversal phenomenon by varying the number of harmonics and its effect on electron and ion heating is performed. The simulation results predict higher harmonics generation and multiple field reversal regions formation with an increasing number of harmonics along with the local charge separation and significant displacement current outside sheath region. The field reversal strength is greater during the expanding phase of the sheath edge in comparison to its collapsing phase causing significant ion cooling. The observed behavior is associated with the electron fluid compression/rarefaction and electron inertia during expanding and collapsing phase respectively