Author: Latest Results

Experimental Evaluation of Estimating Local Bed Shear Stress Using Log Law in a Straight River Channel

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Abstract

Bed shear stress is a critical parameter in riverine environments, directly influencing sediment transport, erosion, deposition, and flow dynamics. However, direct measurement of bed shear stress in natural rivers is nearly impossible, and estimating bed shear stress by extrapolating the Reynolds stress profile, though known for accuracy, faces practical limitations due to the challenges of measuring turbulence in natural rivers. As alternatives, indirect methods, such as global bed shear stress estimation based on bed slope and hydraulic radius (assuming uniform flow) and local bed shear stress estimation through regression of velocity profiles using the log law, have been employed. The estimation of local bed shear stress using the log law has primarily been derived from laboratory flow conditions due to the limitations in observing detailed turbulence in field conditions. Consequently, the applicability of the log-law method under field conditions has not been sufficiently evaluated. This study aims to assess local bed shear stress using the log law through a dedicated field experiment in a specific river condition, comparing it with methods utilizing the Reynolds stress profile. The experiment was conducted in a straight river channel with a width of approximately 6.5 m, a depth of 0.61 m, and a mean flow velocity of 0.56 m/s. A total of 197 points of regularly distributed velocity and turbulence data for the given cross-section were acquired using micro-acoustic Doppler velocimeter measurements with a duration of 90 s. We found that the log-law method overestimated local bed shear stress by an overall factor of 2.3 compared to the method using Reynolds stress profiles. Thus, the experimental results conclusively indicate that local bed shear stress estimated from the log law in natural river conditions could be overestimated. However, additional research is needed under more diverse flow and geometric conditions to develop a correction formula for applying the log law in estimating local bed shear stress.

Environmental impacts of mycelium-based bio-composite construction materials

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Abstract

In recent years, the applications of mycelium-based bio-composites (MBCs) have grown considerably in light of their alignment with the movement toward circularity and sustainability. These lightweight biodegradable materials provide a promising alternative to traditional materials that rely heavily on the consumption of nonrenewable natural resources and present an exceptional opportunity to valorize waste streams through the production of biologically augmented materials. A wide range of feedstock materials and fabrication approaches have been employed in their production thus far; yet the differences brought about by these variations have not been investigated from an environmental perspective. This study explores the environmental implications arising from the use of seven commonly used substrate materials in the production of fungal composites potentially used as construction materials through life-cycle assessment methodology. Nine life-cycle models were developed based on different procurement, production, and processing scenarios to account for parameters such as feedstock materials, geographical region and transportation distances, processing techniques, etc. The attributional cradle-to-gate analyses and end-of-life scenarios placed the single-score environmental burden of the materials in the range of 19–43 mPt, with an average of 26.8 mPt, and demonstrated the superiority of sawdust-based composites alongside specific cases of bamboo-based materials that do not require considerable transportation. Composting the material at its end of life, as opposed to landfilling or incineration, reduced the overall environmental impact by up to 8%. Moreover, it was found that pre-compression, while effective in improving mechanical properties, can increase the environmental burden by over 50% through the consumption of electrical energy.

Petroleum system and hydrocarbon potential of the Kolmani Basin, Northeast Nigeria

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Abstract

The exploration of hydrocarbons in the Kolmani Basin, located in Northeast Nigeria, has sparked curiosity regarding its potential for hydrocarbon production. This review addresses the controversies surrounding the tectonic evolution of the Kolmani Basin, its petroleum system, and its potentiality via conventional petroleum systems (CPS). It has two tectonic models, the pull-apart model and the rift model, that influenced the petroleum system. The primary source rocks in the basin are found in the Yolde Formation (1.4–12.5wt% TOC), Pindiga Formation (0.85–2.4wt% TOC), Fika Shale, and Gombe Formation (2–4.27wt% TOC), with the Yolde Formation proving to be the most promising. The main reservoirs consist of the sandy sections of the Yolde Formation, Pindiga Formation, Bima Formation, and Gombe Formation. The primary seals are the thick Fika Shale, which caps the Pindiga Reservoirs, and the intercalating silty shales of the Gombe Formation. Trap formation began in the late Albian age, while petroleum generation, migration, and accumulation processes commenced in the late Turonian age, resulting in existing traps. Hydrocarbon preservation began in the late Albian age, as evidenced by traces of hydrocarbons in the Bima Formation. All the necessary elements and processes for petroleum formation were in place before the critical point in the Maastrichtian age. The potential of the basin was confirmed by the drilling of three wells (Kolmani River-1, Nasara-1, and Kuzari-1), with Kolmani River-1 discovering 33 billion cubic feet of gas. In addition, the Nigerian National Petroleum Corporation (NNPC) identified six prospects using 3D seismic data.

Petroleum system and hydrocarbon potential of the Kolmani Basin, Northeast Nigeria

Latest Results

Abstract

The exploration of hydrocarbons in the Kolmani Basin, located in Northeast Nigeria, has sparked curiosity regarding its potential for hydrocarbon production. This review addresses the controversies surrounding the tectonic evolution of the Kolmani Basin, its petroleum system, and its potentiality via conventional petroleum systems (CPS). It has two tectonic models, the pull-apart model and the rift model, that influenced the petroleum system. The primary source rocks in the basin are found in the Yolde Formation (1.4–12.5wt% TOC), Pindiga Formation (0.85–2.4wt% TOC), Fika Shale, and Gombe Formation (2–4.27wt% TOC), with the Yolde Formation proving to be the most promising. The main reservoirs consist of the sandy sections of the Yolde Formation, Pindiga Formation, Bima Formation, and Gombe Formation. The primary seals are the thick Fika Shale, which caps the Pindiga Reservoirs, and the intercalating silty shales of the Gombe Formation. Trap formation began in the late Albian age, while petroleum generation, migration, and accumulation processes commenced in the late Turonian age, resulting in existing traps. Hydrocarbon preservation began in the late Albian age, as evidenced by traces of hydrocarbons in the Bima Formation. All the necessary elements and processes for petroleum formation were in place before the critical point in the Maastrichtian age. The potential of the basin was confirmed by the drilling of three wells (Kolmani River-1, Nasara-1, and Kuzari-1), with Kolmani River-1 discovering 33 billion cubic feet of gas. In addition, the Nigerian National Petroleum Corporation (NNPC) identified six prospects using 3D seismic data.

Populism, moral foundations, and vaccine hesitancy during COVID-19

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Abstract

Vaccine hesitancy is a significant global health concern, with over 90% of countries reporting such hesitancy. In the United States, vaccine hesitancy has risen significantly, with over 79 million cases and 950,000 deaths in 2022. This highlights the political importance of vaccine hesitancy in the coming years. Moral foundations are associated with political alignments on the left-right axis, but they do not extend to beliefs about political contexts. Populism, a belief in the power of the people to take back power from the elite, is particularly important in the COVID-19 pandemic. This study explores possible associations of vaccine hesitancy with both moral foundations and populism using survey research. Results from multiple regression analysis show that while moral foundations are not entirely accounted for, populism can impact vaccine hesitancy outside of its overlap with moral foundations. The study reveals a significant association between vaccine hesitancy and populism and four moral foundations. It suggests that vaccine hesitancy is linked to populist sentiment and moral orientations and suggests that further research could explore the relationship between these factors. The study also suggests that the challenge of vaccine hesitancy is not solely about vaccines, but rather exacerbated skepticism and lack of trust in institutions and elite knowledge. The findings could help policymakers and practitioners understand the motivational factors influencing vaccine hesitancy, focusing on moral reasoning and sociopolitical narratives rather than swaying people with scientific elite knowledge. Emphasizing messages about vaccination as a form of loyalty to family, friends, and country could be more effective.

Electromechanical Response of Mesenteric Ischemia Defined Through Simultaneous High-Resolution Bioelectrical and Video Mapping

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Abstract

Intestinal motility is governed in part by bioelectrical slow-waves and spike-bursts. Mesenteric ischemia is a substantial clinical challenge, but its electrophysiological and contractile mechanisms are not well understood. Simultaneous high-resolution bioelectrical and video mapping techniques were used to capture the changes in slow-waves, spike-bursts, and contractile activity during baseline, ischemia, and reperfusion periods. Experiments were performed on anesthetized pigs where intestinal contractions were quantified using surface strain and diameter measurements, while slow-wave and spike-bursts were quantified using frequency and amplitude. Slow-waves entrainment within the ischemic region diminished during ischemia, resulting in irregular slow-wave activity and a reduction in the frequency from 12.4 ± 3.0 cycles-per-minute (cpm) to 2.5 ± 2.7 cpm (p = 0.0006). At the end of the reperfusion period, normal slow-wave entrainment was observed at a frequency of 11.5 ± 2.9 cpm. There was an increase in spike-burst activity between the baseline and ischemia periods (1.1 ± 1.4 cpm to 8.7 ± 3.3 cpm, p = 0.0003) along with a spasm of circumferential contractions. At the end of the reperfusion period, the frequency of spike-bursts decreased to 2.7 ± 1.4 cpm, and contractions subsided. The intestine underwent tonal contraction during ischemia, with the diameter decreasing from 29.3 ± 2.6 mm to 21.2 ± 6.2 mm (p = 0.0020). At the end of the reperfusion period, the intestinal diameter increased to 27.3 ± 3.9 mm. The decrease in slow-wave activity, increase in spike-bursts, and tonal contractions can objectively identify ischemic segments in the intestine. It is anticipated that the use of electrophysiological slow-wave and spike-burst biomarkers, along with contractile measures, could identify mesenteric ischemia in surgical settings and allow an objective biomarker for successful revascularization.

[Re]Imagining Indigenous Educational Design: A Conceptual Manifesto to Grow Disruptive Indigenous Digital Activists

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Abstract

The ubiquity of digital technologies and the harvesting of individual data has modified global societies, reinforcing systems of oppression. While a contemporary phenomenon, the convergence of technology and human subjugation is historical, with links to the racialised reproduction of settler-colonialism. Australia, a settler-colonial state, has escalated the prioritisation of digital competitiveness with a recent policy directed at stimulating infrastructure and research-industry-government partnerships. Strategically, Indigenous communities remain constrained, where the ubiquity of technology and the escalation of digital competitiveness compounds the socio-economic impacts of continuing colonisation. Offline, Indigenous communities continue to face rigid political constraint that limits online access and denies opportunities for their people to live anchored to ancestral lands, seas, languages, and knowledge systems. Given the rapid advance of digital disruption, the inability to limit racialised socio-technical systems, or compete at parity in cyberspace, suppresses Indigenous digital activism, governance, and entrepreneurialism. This conceptual paper (part manifesto, part vision statement) offers initial thoughts intended to stimulate further research on twenty-first-century Indigenous educational design. Central to future design considerations is the search for pragmatic solutions capable of overcoming the racialised challenges limiting the collective development of digital activists essential for Indigenous nation-building. In [re]imagining an alternate digital educational agenda, Indigenous communities must collectively advance strategies that deliberately shift away from Australian schools toward local community digital learning hubs.

The ebbs and flows of equity work amongst organizational shocks and crises

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Abstract

We examine how the shock of the COVID-19 pandemic and the murder of George Floyd influenced how a mid-sized urban school district in the northeastern U.S. pursued organizational improvement for educational equity. We frame the global pandemic and the aftermath of the murder of George Floyd as organizational shocks that disrupted school and district operations that are relevant across borders and international contexts. We employed a chronological multi-layered qualitative design to understand how educational stakeholders made sense of equity work amid organizational shocks and how these shocks either catalyzed, stabilized, or hindered organizational improvement for equity as managerial priorities and organizational processes shifted from previously established goals. Data sources included interviews, document analyses, and school board meeting transcripts. Equity efforts were reactive to organizational shocks. Previously established equity efforts were diluted as core organizational operations changed in response to the shocks. Previous equity gains were quickly undone. However, the organizational shocks also allowed for innovative equity efforts to emerge that both fractured and strengthened staff orientations towards equity work-resulting in racial breakthroughs. The ebbs and flows of equity work appear to be a constant feature of organizational improvement for equity. In times of both stability and crisis, stakeholders must engage in strategic equity planning initiatives that are responsive to community needs and that have district-wide buy-in so that external threats do not undermine previously established gains.