UPSpace
Institutional Repository
Faculty Research Collections
UP Research Output Collections
Featured
Recent Submissions
The road to a long lifespan in the Persian squirrel, a natural model for extended longevity : resisting free radical stress and healthy phospholipids
(Springer, 2025) Salehi, Fahimeh; Kavoosi, Gholamreza; Jacobs, Paul Juan; Bennett, Nigel Charles; Ahmadian, Shahin; Bastani, Babak; Gholami, Mahdi
Longevity is influenced by various factors, including fatty acid composition and free radical stress, which relate to the membrane pacemaker and rate of living hypotheses. While these aspects are well-documented in some long-lived species, they remain largely unexplored in tree squirrels. This study aimed to compare oxidative stress, antioxidant activity, nitrosative stress, and lipid composition between the long-lived Persian squirrel (Sciurus anomalus) and the short-lived Wistar rat across age cohorts (younger and older). Tissue homogenates from skin, liver, skeletal muscle, spleen, lung, and kidney were analysed for lipid composition (monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), arachidonic to linoleic acid ratio, peroxidation index, and unsaturation index. Oxidative, nitrosative, and antioxidant markers were assessed, including NADPH oxidase, superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase (GST), nitric oxide synthase, superoxide, hydrogen peroxide, nitric oxide, malondialdehyde, 4-hydroxynonenal, and total antioxidant capacity (TAC). Squirrels demonstrated higher GST activity, lower free radical stress, lower PUFA, and higher MUFA compared to rats. Antioxidant activities, except for TAC were negatively correlated with longevity. Older squirrels exhibited similar oxidative, nitrosative, and antioxidant profiles to younger squirrels, whereas younger rats displayed highly susceptible fatty acids, similar to older rats. The Persian squirrel’s longevity appears closely linked to fatty acid composition and free radical resistance, likely due to increased GST activity. We propose GST’s multifunctional role in reducing inflammation, enhancing immune response, providing disease resistance, and antioxidant activity contributes significantly to the longevity of the Persian squirrel.
A new index for climate-induced migration uncertainty
(Wiley, 2025-01) Salisu, Sulaiman; Salisu, Afees A.; afees.salisu@up.ac.za
The impact of climate change on the world has been significant, leading to various efforts to reduce its risks. This study aims to create a new index to measure the uncertainty surrounding migration due to climate change. It uses a range of international newspapers with a global readership. Although climate change has increasingly influenced migration decisions in vulnerable areas, there is still a lack of quantitative research exploring this connection, which our study aims to address. The index indicates a growing trend in climate-induced migration decisions, especially over the last two decades, supporting the study's purpose. We also present empirical results that validate the depressing effect of the uncertainty index on per Capita GDP growth at global, regional and country-specific levels. The index has various practical applications and can be useful for future research.
Simpler characterizations of total orderization invariant maps
(World Scientific Publishing, 2025) Schwanke, Christopher Michael
Given a finite subset A of a distributive lattice, its total orderization to(A) is a natural transformation of A into a totally ordered set. Recently, the author showed that multivariate maps on distributive lattices which remain invariant under total orderizations generalize various maps on vector lattices, including bounded orthosymmetric multilinear maps and finite sums of bounded orthogonally additive polynomials. Therefore, a study of total orderization invariant maps on distributive lattices provides new perspectives for maps widely researched in vector lattice theory. However, the unwieldy notation of total orderizations can make calculations extremely long and difficult. In this paper we resolve this complication by providing considerably simpler characterizations of total orderization maps. Utilizing these easier representations, we then prove that a lattice multi-homomorphism on a distributive lattice is total orderization invariant if and only if it is symmetric, and we show that the diagonal of a symmetric lattice multi-homomorphism is a lattice homomorphism, extending known results for orthosymmetric vector lattice homomorphisms.
Economic conditions, climate change and housing affordability across US states : the mediating role of interest rates in a panel data analysis
(Emerald, 2025) Salisu, Afees A.; Isah, Kazeem Ovanero; Olaniran, Abeeb Olatunde
PURPOSE : The issue of housing affordability is a serious concern, as it affects households’ ability to cover housing expenses without sacrificing other essential needs. However, housing affordability is not solely dependent on economic conditions. The consequences of climate change, such as extreme weather events can worsen the housing crisis by reducing the supply of affordable housing and driving up costs. Therefore, the purpose of this paper is to investigate how in addition to economic conditions, climate change affect the affordability of housing in the USA using state-level data covering the 50 states in the country.
DESIGN/METHODOLOGY/APPROACH : This study used a panel autoregressive distributed lag model to estimate short- and long-term effects and analyzed economic periods before and after the global financial crisis. This study also divided the states into two regions, the hottest and coldest, to examine differences in housing affordability.
FINDINGS : The findings reveal some crucial facts about housing affordability concerning economic conditions and climate change. The study shows result that suggests better economic conditions lead to increased housing affordability, particularly in colder regions. Additionally, climate change positively affects housing affordability in the short term. Finally, this study confirms the important role of interest rates in the relationship between economic conditions and housing affordability.
ORIGINALITY/VALUE : The review of existing works indicates that studies on housing concerning economic conditions and climate change at disaggregated levels are very scarce. As a result, this study pays attention to investigating the connection between housing affordability and economic conditions for 50 states in the USA. Additionally, this study makes some extensions by examining the role of climate change and how interest rates could mediate in the nexus given either improved or depressed economic conditions.
Contested heritage(s) - the case(s) of the battle of blood river (December 16th, 1838), Dundee and Nquthu, South Africa
(Publikon Kiadó, 2024) Van der Merwe, Clinton David; clinton.vandermerwe@up.ac.za
Battlefield tourism is a well-established niche in cultural and heritage tourism the world over. This paper explores the contested nature of a specific battlefield in KwaZulu-Natal, South Africa, where two separate museums exist to memorialise the same event, but from two perspectives. The Battle of Blood River (December 16th, 1838) remains a contested event in history books, portrayed from Afrikaner and AmaZulu points of view at the Blood River Heritage Site and Ncome Museum, respectively. People interested in visiting battlefields are slowly dying out, and if South Africa wants to take advantage of growing Battlefield Tourism in the future for surviving generations of those involved in these battles, a new approach will be necessary to sustain and develop this niche of cultural and heritage tourism in the country. This paper uses netnography to analyse the internet footprint of this historical event through the museums’ websites. The paper argues that a more balanced and two-sided perspective should be given at both museums to grow and develop the interest in battlefield tourism across South Africa and encourage mutual visitorship to both museums on the same battlefield site.