21436 research outputs found
Sort by
Mathematical modelling of growth and metabolism in anaerobic microbes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Mathematics at Massey University, Palmerston North, New Zealand
No full textThe growth rates of microbes can be thermodynamically limited by unfavourable ratios of energy substrates and end products. This thesis explored and expanded mathematical models that apply to a broad range of anaerobic microbes with different metabolisms, especially at low
substrate to product ratios.
The rates considered here fall into four categories based on how they are derived. Prima facie these rates are unrelated; however, for large concentrations of substrate they are in agreement. A new term based on the properties of the ATP synthase enzyme was added to a model derived from the Briggs-Haldane rate to allow the microbe to vary the energy required to produce ATP (∆GATP) at low substrate concentrations. Experimental data were used to show that different values of ∆GATP were better suited for predicting Kapp and Smin, substrate concentration values corresponding to half-maximal growth rate and growth shutoff, respectively. This term allowed growth to continue in challenging thermodynamic conditions by optimising ∆GATP to maximise the growth rate. When ∆GATP was considered variable between biologically relevant limits, the model predicted the measured Kapp and Smin values from the dataset.
Results from the model were compared with experimental data reported at multiple times as growth occurs. The results agreed qualitatively for batch cultures with and without thermodynamic inhibition. The model produced results that were consistent with experimental data for a continuous culture for two strains of microbe. In addition, it was adapted for modelling direct competition between the two strains which compete for the same energy substrate. Modelling this competition identified conditions for stable coexistence, a result that has yet to be shown
analytically.
Different approaches for modelling metabolisms where multiple substrates are simultaneously required to produce ATP were explored, with a focus on four variations of an analogy between microbes and enzymes. This analysis identified several rates that may have applications in different situations, and also identified a derivation for a widely-used empirical rate as a special case. An extension of a rate based on statistical mechanics to multiple substrates also showed promise
Embedded Learning Support Practices for Primary Caregivers of Autistic Children
No full textProviding quality naturalistic and intentional learning opportunities to young autistic children strengthens their engagement and participation in home and education settings. Effective early intervention involves building parents’ capacity to support children’s learning and communication in the home. This study examined a training plus coaching intervention to support parents’ implementation of embedded learning opportunities (ELOs) and complete learning opportunities (CLOs) within naturally occurring play routines. This type of Embedded Learning Support (ELS) is a novel area of research in early intervention in Aotearoa, New Zealand. Three parent–child dyads participated in this study, each including a preschool autistic child. A single group pre-test/post-test study explored intervention impact. Results showed that group training and individualised home-based coaching effectively supported parent capacity and confidence to create meaningful and sustained interactions with their children. Parents valued the systematic and intensive nature of ELOs and CLOs. This paper will highlight the relevance of these findings to the existing literature on parent-implemented interventions and naturalistic and intentional practices.fals
Food spaces that foster student capabilities: insights from a rural Aotearoa New Zealand high school
No full textThis study explores how a school wharekai (communal dining hall) implementing the Ka Ora, Ka Ako Healthy School Lunch Programme operates as a multidimensional health promotion setting that fosters student capabilities beyond nutrition. Using a qualitative approach grounded in mātauranga Māori (Māori knowledge) and community-based participatory research, we conducted focus groups with 22 students and semi-structured interviews with 12 staff members to examine how the wharekai promotes wellbeing. Findings show that the wharekai provides a culturally responsive environment where three interrelated capabilities flourish: self-management, interpersonal relationships, and community participation. Through daily routines and authentic roles in food preparation, students practise responsibility, initiative, and cooperation. Shared meals strengthen tuakana–teina (peer) relationships and build trust between students and staff, while collective activities foster belonging, reciprocity, and sustainability. Conceptualizing food spaces through cultural frameworks such as the wharekai demonstrates how school food programmes can simultaneously address food insecurity and create transformative learning environments. This study highlights how culturally grounded, settings-based approaches can integrate nutritional, social, and relational dimensions of health promotion, reimagining school food provision as a holistic, capability-building practice that enhances individual and collective wellbeing.fals
The Internet Research Agency Campaign to Influence the 2016 US Presidential Elections: A Rhetorical Analysis
No full textThe centrality of information and communicative processes in persuading society has, historically, made the media one of the key networks of power and influence in society. The rapid expansion of social media platforms has, however, enabled revolutionary changes in how this power is wielded and how persuasion occurs. This has had a profound impact on how political, economic, and social issues are understood and addressed. While a comprehensive body of social psychological theory and applied practice on the topic of persuasion has been developed over many years, persuasion in the contemporary social media environment is one that researchers are yet to fully understand. Methods for achieving this understanding continue to evolve. This article draws on a large corpus of material (2218 Facebook advertisements and metadata) which documented the Russian Internet Research Agency campaign to influence the outcome of the 2016 US presidential elections. Drawing on Aristotle's rhetorical framework, this article presents a process analysis to understand how political persuasion is undertaken in the contemporary social media environment. The findings provide new insights into the social psychological processes of persuasion in contemporary society and demonstrate the utility of a rhetorical framework in understanding persuasion campaigns in dynamic digital settings.fals
The Role of Agriculture Cooperatives in Green Agri-Food Value Chains in China: Cases in Shandong Province
No full textWhile escalating environment and food safety challenges underscore the need for sustainable agri-food systems, promoting green agri-food production provides a promising pathway. The green agri-food value chain integrates green agri-food production with coordinated value-adding activities across the value chain. In developing such value chains, agricultural cooperatives emerge as a key player. This research integrates sustainability and value chain theories, aiming to study the role of China’s cooperatives in enabling green production and green value chains. It used qualitative methodology and interviews with management and members of three green vegetable cooperatives in Shandong Province, China, to offer an initial examination into this research area. The findings reveal that cooperatives play an important role in the green vegetable value chain and have a different level of vertical integration, with some having control over the whole value chain from input supply to retail. They also provide essential input, technical, and market support to enable green vegetable production and facilitate various value-adding activities. The study offers valuable insights into recommendations for enhancing value addition and facilitating green value chains. It also holds practical implications for practitioners and policymakers to strengthen cooperative development in China as an important intermediary for advancing agriculture sustainability.fals
Environmental and occupational exposure to erionite and related health risks: Progress and prospects
No full textObjectives
Erionite, a naturally occurring fibrous zeolite classified as a human carcinogen, is believed to be more potent than asbestos in causing mesothelioma. However, unlike asbestos, erionite has rarely been used for commercial purposes and, as a result, knowledge about exposure pathways is limited. This paper provides a narrative review of the current knowledge regarding the associations between erionite exposure, health effects and exposure circumstances.
Methods
Medline/PubMed and Scopus were systematically searched up to the end of 2024 using keywords related to erionite exposure and health outcomes.
Results
We identified 26 peer-reviewed journal articles reporting on the health effects of erionite exposure, specifically mesothelioma and lung cancer, with mesothelioma being the most extensively studied outcome. Of these, 12 studies focussed on erionite-exposed populations in Turkey, 8 examined health effects among Turkish migrants in northern Europe, and 6 investigated erionite-related health risks in North America (3 in the United States and 3 in Mexico). These studies showed a very high incidence of mesothelioma, often in relatively young individuals, from the Cappadocia region of Turkey, with well-documented environmental exposures to erionite, contributing to a high proportion of all deaths (21% to 51%) in affected villages. Evidence of lung cancer associated with erionite exposure was also found. There is also evidence of erionite exposure-associated mesothelioma in Guanajuato, central Mexico. In the United States, erionite exposure-associated health effects (not mesothelioma) have been reported among people occupationally exposed to erionite. Studies on environmental exposures have shown outdoor concentrations ranging from 0.001 f/ml to 0.3 f/ml, while indoor concentrations have ranged from 0.005 to 1.38 f/ml. Occupational exposure to erionite has been less studied, with only one study in forestry workers showing elevated exposures to erionite ranging from non-detectable to 0.36 f/cc. Erionite deposits have also been identified in other countries such as Italy and New Zealand, but exposures and associated health effects have not yet been studied in these regions.
Conclusion
There is clear evidence that environmental exposure to erionite in the Cappadocia region of Turkey, and Guanajuato in central Mexico are causally associated with the high mesothelioma rates observed in these areas. Evidence for other parts of the world where there is naturally occurring erionite is limited. This review has highlighted significant knowledge gaps, and advocates for further research on occupational exposure to erionite fibres and associated health effects.fals
Who does not advance loses ground: Green investment as a strategic response by small and medium-sized enterprises to economic policy uncertainty
No full textThis study examines how listed small and medium-sized enterprises (SMEs) respond to economic policy uncertainty (EPU exposure) through their environmental decisions. We find that SMEs are associated with increased environmental investment when facing heightened EPU exposure. Notably, SMEs with greater EPU exposure are more likely to invest in clean energy-related initiatives, underscoring the important role of the energy sector in driving corporate sustainable strategies. Additionally, this study reveals that the impact of EPU exposure on environmental investments is more salient when SMEs face fewer financial constraints, are located in more marketized regions, operate in less competitive markets and non-heavily polluting industries, and after the implementation of the 2012 Green Credit Policy. These findings suggest that SMEs are more likely to adopt sustainable practices under heightened policy uncertainty, leveraging environmental initiatives as a strategic response to facilitate firm development and growth.fals
Sensitivity analysis of global food and nutrition modelling
No full textComputational models are often used to explore the future of the global food system, including the implications for human nutrition, an essential aspect of sustainability. However, the confidence that can be placed in the outputs of these models is often poorly quantified. Here, a sensitivity analysis of the DELTA Model® - a linear mass balance model calculating global nutrient supply using global and regional food balance sheet, processing, waste, inedible portion, composition, and bioavailability datasets - is conducted. First, a one-at-a-time analysis, varying 4019 underpinning datapoints from the above datasets individually by ± 50% was conducted to identify those with the greatest impact on calculated global nutrient supply. The most influential values from this initial analysis were then carried forward into a multiple value sensitivity analysis, where all possible combinations of ± 50% variations were simulated. Values related to cereals supply, waste, and nutritional value were the most influential on model output, with selenium, cystine, and carbohydrate supply the most sensitive nutrients. When compared to global nutrient requirements, variations in the calculated supply of some nutrients led to qualitative changes from a sufficient global supply to an insufficient supply. These results, while indicative rather than precise estimates of uncertainty, emphasise the critical importance of accurate cereals data in food system models, provide insight on the degree of sensitivity of similar linear models, and should encourage broader application of sensitivity analysis in the field.fals
Biochemical and haematological reference intervals for 3–4-week-old kiwi chicks (Apteryx mantelli) reared in captivity
No full textAims: To establish biochemical and haematological 95% reference intervals (RI) for juvenile North Island brown kiwi (Apteryx mantelli) chicks using parametric analysis.
Methods: Blood samples were collected from healthy 3–4-week-old, captive-reared North Island brown kiwi chicks (n = 32; male = 19, female = 13). Concentrations of total plasma protein (TPP), uric acid, glucose, phosphorus, calcium, albumin, globulin, potassium, and sodium and activities of aspartate aminotransferase and creatine kinase (CK) were measured using an automated VetScan VS2 laboratory analyser and the Abaxis Avian-Reptilian Profile Plus. Total and differential white blood cell counts were determined manually on blood smears prepared with a modified Wright-Giemsa stain. TPP was also measured manually using a refractometer, and packed cell volume (PCV) was measured using microhaematocrit tubes. RI were calculated using parametric and non-parametric methods depending on the distribution of the data. Confidence intervals (90%) around upper and lower bounds of the RI were calculated to assess certainty of the intervals.
Results: Biochemical (n = 28; male = 17; female = 11) and haematological (n = 22; male = 14, female = 8) 95% RI were generated for juvenile North Island brown kiwi. The 90% CI of the upper or lower limits of the majority of the RI generated were > 0.2 times the RI, reflecting the relatively small sample size. There was no evidence of a difference in mean biochemical values collected from sedated vs. un-sedated, and male vs. female chicks. However, the concentration of phosphorus was higher (p = 0.034) in samples that were analysed > 1 hour after collection (2.097 (SD 0.202) mmol/L) compared to samples analysed < 1 hour after collection (1.856 (SD 0.349) mmol/L).
Conclusions: This data provides the first comprehensive biochemical and haematological RI generated for Apteryx spp. chicks carried out under uniform collection and sample handling protocols, making the results robust and applicable to other captive-reared kiwi chicks.
Clinical relevance: In comparison to published RI from adult kiwi (Doneley 2006; Morgan 2008), kiwi chicks in this study had lower PCV, TPP and uric acid concentrations, and higher CK activities, white cell counts and lymphocyte counts. These RI are of value to wildlife veterinarians and conservation managers assessing the health of individual kiwi chicks, and for population-level comparison of birds of different ages and living in different managed or wild habitats.fals
Can fishery subsidy improve fishermen’s income?——evidence from China’s coastal areas
No full textNumerous studies have demonstrated that fishery subsidies play a role in income redistribution, potentially contributing to economic inequality. Additionally, since fishermen are highly dependent on the marine environment, there may be a connection between marine pollution and their income levels. This study explores the effects of fishery subsidies and marine environmental pollution on fishermen’s income and income inequality using panel data from 11 coastal provinces and municipalities in China from 2006 to 2020. Applying panel fixed effect model and quantile regression models, the results show that fishery subsidies significantly increase income, but disproportionately benefit higher-income fishermen, thereby exacerbating income inequality. Moreover, the relationship between marine pollution and income is non-linear: moderate pollution is associated with income gains, while severe pollution reduces income. These findings suggest that subsidy policies should be better targeted, and stricter marine environmental regulation is necessary to protect vulnerable fishing communitiesfals