OPUS: Open Ulethbridge Scholarship
Open ULeth Scholarship (OPUS) is the University of Lethbridge's open access research repository. It contains a collection of materials related to research and teaching produced by the academic community.
Self-archiving your research in OPUS is one way to meet Open Access policies of granting agencies. It is important to retain your final, post-peer-reviewed drafts for submission to OPUS, as this is often the only version publishers will allow to be archived. Click here for information on the U of L Open Access Policy.
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Systematic noise removal from analytical ultracentrifugation data with UltraScan
(Springer Link, 2023) Mortezazadeh, Saeed; Demeler, Borries
A method for removing time- and radially invariant noise from sedimentation velocity and sedimentation equilibrium experiments performed in an analytical ultracentrifuge is presented. The method averages repeat radial incident light measurements as a function of the photomultiplier response at different wavelengths to remove the majority of the time-invariant noise contributions from intensity data measurements. The results of this method are compared to traditional absorbance data generated with a buffer reference and the Beckman Optima AUC data acquisition program, and with the standard UltraScan refinement workflow. The method avoids the amplification of stochastic noise inherent in the absorbance scan subtraction traditionally employed in sedimentation velocity and equilibrium data. In addition, the collection of intensity data frees up the reference channel for additional samples, doubling the capacity of the instrument. In comparison to absorbance data, the residual mean square deviation of a fitted sedimentation velocity experiment without additional noise correction by UltraScan was improved by a factor of 4.5 when using the new method. This improvement benefits sedimentation equilibrium experiments as well as analytical buoyant density equilibrium experiments where routine time-invariant noise correction calculations cannot be performed.
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Wildfire as a major driver of recent permafrost thaw in boreal peatlands
(Nature Portfolio, 2018) Gibson, Carolyn M.; Chasmer, Laura; Thompson, Dan; Quinton, William L.; Flannigan, Mike D.; Olefeldt, David
Permafrost vulnerability to climate change may be underestimated unless effects of wildfire are considered. Here we assess impacts of wildfire on soil thermal regime and rate of thermokarst bog expansion resulting from complete permafrost thaw in western Canadian permafrost peatlands. Effects of wildfire on permafrost peatlands last for 30 years and include a warmer and deeper active layer, and spatial expansion of continuously thawed soil layers (taliks). These impacts on the soil thermal regime are associated with a tripled rate of thermokarst bog expansion along permafrost edges. Our results suggest that wildfire is directly responsible for 2200 ± 1500 km2 (95% CI) of thermokarst bog development in the study region over the last 30 years, representing ~25% of all thermokarst bog expansion during this period. With increasing fire frequency under a warming climate, this study emphasizes the need to consider wildfires when projecting future circumpolar permafrost thaw.
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Integrative taxonomy, distribution, and host associations of Geocenamus brevidens and Quinisulcius capitatus from southern Alberta, Canada
(Sciendo, 2021) Munawar, Maria; Yevtushenko, Dmytro P.; Castillo, Pablo
Two stunt nematode species, Geocenamus brevidens and
Quinisulcius capitatus, were recovered from the potato growing regions
of southern Alberta, described and characterized based on integrative
taxonomy. Morphometrics, distribution, and host associations
of both species are discussed. The Canadian populations of both
species displayed minor variations in morphometrical characteristics
(viz., slightly longer bodies and tails) from the original descriptions.
The populations of G. brevidens and Q. capitatus species examined
in this study are proposed as standard and reference populations
for each respective species until topotype specimens become
available and molecularly characterized. Phylogenetic analyses,
based on partial 18S, 28S, and ITS sequences, placed both species
with related stunt nematode species. The present study updates
the taxonomic records of G. brevidens and Q. capitatus from a
new location, southern Alberta, Canada, and will aid in the decision
whether these stunt nematodes should be included in nematode
management programs.
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Quality not quantity: deficient juvenile play experiences lead to altered medial prefrontal cortex neurons and sociocognitive skill deficits
(Wiley, 2024) Ham, Jackson R.; Szabo, Madeline; Annor-Bediako, Jessica; Stark, Rachel A.; Iwaniuk, Andrew N.; Pellis, Sergio M.
Reduced play experience over the juvenile period leads to adults with impoverished social skills and to anatomical and physiological aberrations of the neurons found in the medial prefrontal cortex (mPFC). Even rearing rats from high-playing strains with low-playing strains show these developmental consequences. In the present study, we evaluated whether low-playing rats benefit from being reared with higher playing peers. To test this, we reared male Fischer 344 rats (F344), typically thought to be a low-playing strain, with a Long–Evans (LE) peer, a relatively high-playing strain. As juveniles, F344 rats reared with LE rats experienced less play and lower quality play compared to those reared with another F344. As adults, the F344 rats reared with LE partners exhibited poorer social skills and the pyramidal neurons of their mPFC had larger dendritic arbors than F344 rats reared with same-strain peers. These findings show that being reared with a more playful partner does not improve developmental outcomes of F344 rats, rather the discordance in the play styles of F344 and LE rats leads to poorer outcomes.
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Online social network fundraising: threats and potentialities
(Wiley, 2023) Wymer, Walter; Najev Cacija, Ljiljana
There has been a growth in online fundraising from crowdfunding apps, like GoFundMe, that propagate fundraising appeals on social networking sites. In the online space, these crowdfunding apps pose a potential threat to the traditional intermediation role of charities. The disintermediation threat is that donors choose crowdfunding intermediaries instead of charities to channel their giving. In this article, we discuss what makes crowdsourced fundraising effective and how charities can adapt to this new dynamic for more effective online fundraising emphasizing two key success factors: brand strength/reputation and managing the donor experience. In addition, we explain the advantages and disadvantages of social media fundraising and giving and propose ways charities can leverage their good reputations and public trust to stimulate reintermediation. Finally, we propose a landscape for future research based on model that emphases the fundraising campaign's ability to stimulate viral sharing within and between online social networks.