16168 research outputs found
Sort by
Multi-objective hybrid optimization for optimal sizing of a hybrid renewable power system for home applications
Get PDFAn optimal energy mix of various renewable energy sources and storage devices is critical for a profitable and reliable hybrid microgrid system. This work proposes a hybrid optimization method to assess the optimal energy mix of wind, photovoltaic, and battery for a hybrid system development. This study considers the hybridization of a Non-dominant Sorting Genetic Algorithm II (NSGA II) and the Grey Wolf Optimizer (GWO). The objective function was formulated to simultaneously minimize the total energy cost and loss of power supply probability. A comparative study among the proposed hybrid optimization method, Non-dominant Sorting Genetic Algorithm II, and multi-objective Particle Swarm Optimization (PSO) was performed to examine the efficiency of the proposed optimization method. The analysis shows that the applied hybrid optimization method performs better than other multi-objective optimization algorithms alone in terms of convergence speed, reaching global minima, lower mean (for minimization objective), and a higher standard deviation. The analysis also reveals that by relaxing the loss of power supply probability from 0% to 4.7%, an additional cost reduction of approximately 12.12% can be achieved. The proposed method can provide improved flexibility to the stakeholders to select the optimum combination of generation mix from the offered solutions
Can large taonga bivalves speed up recovery in degraded estuaries?
Get PDFTHE QUESTION:
Will there introduction of adult, long-lived bivalves with differing functional traits speed up recovery of degraded soft sediment habitats in estuaries?
RESULTS:
Average bivalve survival after one year was 18% in + tuangi plot sand 59% in + hanikura plots. Sediment oxygen consumption (SOC) after one month was enhanced by 116% in treatments containing tuangi compared to control treatments. After one year those were similar to ambient levels, still showed higher SOC than control plots
Supplemental Material for Enhancing Precision of the Telephone Interview for Cognitive Status–Modified (TICS-M) Using the Rasch Model
No full textRasch analysis begins with examining the overall data fit to the Rasch model as well as individual item fit. It also includes the evaluation of residual correlations across items because it possibly influences fit to the Rasch model. Firstly, the overall model fit requires the estimate of item-trait interaction to be not significant, which is reflected by chi square index (p > .05). Secondly, the fit residuals for individual items should be in the range between −2.50 and +2.50. Thirdly, the residual correlations between individual items should be examined because values above 0.20 indicate local dependency that can affect both individual items and the overall model fit (1). Finally, there should be no DIF due to relevant individual characteristics (i.e. personal factors) meaning that all items should be invariant across different groups (e.g. age, sex). In addition, PSI is used to evaluate reliability in Rasch analysis, which is not the Rasch model fit criteria but reflects how well the scale discriminates between individuals with different levels of the latent trait (e.g. SCC). PSI is interpreted somewhat similar to Cronbach's alpha with values above 0.70 indicating acceptable reliability for group assessments and 0.80 and higher for individual assessments (2)
The microbiome of perennial ryegrass Lolium perenne L.
Get PDFPerennial ryegrass (Lolium perenne L.) is the most critical agricultural plant supporting New Zealand’s intensive pasture-based dairy industry. A substantial body of research exists on the physiology, genetics, and management of perennial ryegrass; however, the perennial ryegrass microbiome has not yet been investigated in detail. Poor persisting perennial ryegrass pastures are ongoing in some areas of the country. Microbiome research has already targeted one pasture persistence problem by applying Epichloë endophytes to combat invertebrate pest herbivory. The success of Epichloë encourages future research to explore additional microorganism applications to mitigate other significant contributors to poor pasture persistence, such as drought and water stress. This study explores the bacterial and fungal communities associated with the perennial ryegrass cultivar/Epichloë combination, One50 AR37. In total, 80 samples were collected from plots across four different New Zealand farming regions during April/May 2021 and examined alongside spatial, environmental, and host-plant-related metadata. Cultivation-independent methods, including DNA extraction, 16S and ITS rRNA gene PCR amplicon sequencing analysis (via amplicon sequence variants - ASVs), were used to characterise the perennial ryegrass bacterial and fungal communities. The below-ground (bulk soil, rhizosphere, and root endosphere) compared to the aboveground (shoot endosphere and phyllosphere) perennial ryegrass microbiome habitats represented significantly different ecological niches, correlating to differences in ASV richness, alpha and beta diversity, and the relative abundance of dominant genera. This study demonstrated evidence that the perennial ryegrass microbiome is strongly influenced by farming location and management practices. The large proportion of unique, site-specific taxa found at each farming location holds the potential to explain differences in pasture productivity and persistence. Location differences indicate that future microbiome research should compare ryegrass pastures on a regional basis rather than extrapolating the results to all New Zealand farming locations. A core microbiome was not identified in the current study; however, there is evidence for a wider functional selection of taxa across the individual microbiome habitats. Future studies should incorporate metagenomic sequencing to better understand the functional microbiome trends rather than solely focusing on taxa composition. This study provides the foundation for future perennial ryegrass research as it confirms the general trends and common taxa associated with the five microbiome habitats of this important pasture plant. Future pasture persistence research should compare the microbiome of high producing / persistent ryegrass pastures with low-producing ryegrass pastures whilst controlling as many variables as possible. Bacteria of interest, such as Bacillus and Pseudomonas, should be explored in greater detail at the species level and isolated and applied in manipulative trials to assess the effects on ryegrass production and persistence
Ka hao te rangatahi: Rangatahi Māori experiences of climate change
Get PDFKa pū te rūhā, ka hao te rangatahi - Climate change is well established as one of the earth’s most pressing global issues, whereby Māori and Indigenous communities are more vulnerable to its impacts. Internationally, youth have been participating in a range of climate activism, demanding rapid and adequate responses to climate change from decision makers; with Indigenous youth advocating for Indigenous rights to be centred in these responses. More often than not, research on youth involvement in climate change focusses on the general youth population and sidelines the experiences of minorities such as global Indigenous communities. Due to this inattention, there is a lack of research focussing on rangatahi Māori experiences and perceptions of climate change, leaving rangatahi Māori to advocate for their voices to be heard.
The purpose of this research is to amplify the voices of rangatahi Māori regarding climate change, beyond where rangatahi are already sharing their voices. It focusses on rangatahi perceptions of climate change, specifically exploring how being Māori, and youth, influence their experience. This includes investigating the role rangatahi have within climate change, and any challenges and supportive factors that rangatahi may experience related to climate change.
This thesis utilises Kaupapa Māori and its guiding principles to ground this research agenda, employing Pūrākau methodology to guide research methods. Specifically, semi-structured whakawhitinga kōrero were undertaken with five rangatahi Māori participants, who are passionate about climate change and the taiao, exploring each of their diverse experiences and understandings of climate change. Following a process involving thematic and Pūrākau methodology inspired analysis, key themes from each of the rangatahi whakawhitinga kōrero are presented within a case study, maintaining individual narratives for each rangatahi.
This research found that rangatahi experience is grounded in whakapapa, shaping connection to the taiao, motivations to care about climate change, and encompassed aspirations and hopes regarding climate change responses. These narratives highlight that the exclusion of rangatahi from research spaces leaves a gap in literature that explores youth understandings on climate change. Further findings established that the participants believe that being a rangatahi presents unique skills and perspective to offer to climate spaces. Lastly, through exploring participants experiences of specifically being a rangatahi Māori, the findings of this thesis offer tangible opportunities to support rangatahi in voicing their concerns regarding climate change, as this was an identified challenge.
Ultimately, exploring the rangatahi participants’ understandings contributes to: shaping the narratives of rangatahi Māori experience of climate change; further diversifying Māori understandings of climate change and responses; and amplifying the voices of Māori youth within the growing set of literature on youth engagement in climate change. This research lays a foundation for the voices of rangatahi Māori to be actively included in climate change research, and further contest Western misconceptions that rangatahi must gain more experience to contribute to changing the world
The housing market and economic inequality: An investigation into New Zealand
Get PDFNew Zealand has experienced unprecedented growth in house prices, rent prices, and net wealth per adult over the last three decades. This incredible growth has led to New Zealand political parties and media outlets arguing that the residential property market is driving economic inequality. Despite these claims, only a few studies have empirically tested the impact of house prices on income or wealth inequality using New Zealand data. This thesis contributes to those few studies, analysing the relationship using aggregated annual data from 1995 to 2020. This is the most extended period for any New Zealand analysis. The primary analysis approach is an autoregressive distributed lag (ARDL) model used in conjunction with a principal components analysis, both of which perform well with small sample sizes. An increase in house prices is found to decrease the wealth Gini coefficient and increase the income Gini coefficient in the short- and long-run; all else held constant.
The analysis gives evidence of heterogeneity in the relationship—different deciles experience varying changes in wealth or income share following a house price shock. Heterogeneity arises because housing-related assets are disproportionately allocated across the income and wealth distribution. The heterogeneity across deciles can lead to contrasting results for different inequality measures. Furthermore, the wealth inequality heterogeneity becomes accentuated during a negative house price shock in the short-run. This is driven by the differing ability of deciles to reshuffle their asset portfolios in response to a house price shock. However, the wealth inequality relationship becomes symmetric in the long-run, while for the income distribution, the heterogeneity is always symmetric. A non-linear ARDL approach estimates potential asymmetries and separates the behaviours in the short- and long-run.
Previous research rarely analyses wealth and income inequality measures concurrently, while this thesis employs two strategies to do so. First, a seemingly unrelated regression is used, which has an efficiency gain when accounting for the joint disturbances. The efficiency gain yields more accurate model estimates with less variance. Second, a system of equations is utilised. Controlling for income inequality in the wealth inequality model lowers the impact of house prices on wealth inequality. However, when the simultaneity issue is mitigated, controlling for both inequality types concurrently makes minimal difference to the house price estimates. Finally, introducing loan-to-value ratio restrictions for residential property is found to have no significant impact on wealth inequality but increases the income Gini coefficient in the same period. Overall, this thesis provides valuable insights into the complex relationship between the New Zealand housing market and economic inequality
The sex or the head? Feminine voices and academic women through the work of Hélène Cixous
Get PDFHélène Cixous is perhaps best known for her paper, ‘The Laugh of the Medusa’ (1976) and her literary contributions outside academia. In this paper, we pick up a lesser known Cixous text, ‘Le Sexe ou la tête?’ that offers an interesting and provocative perspective on the traps associated with being feminine in a masculine environment. As we converse with Cixous, weaving our own words and experiences with hers, we link her work more closely with the feminine in modern-day academia. We suggest that Cixous’s remarks on decapitation and voice offer a way forward for academic women to be; to speak; to recognise the double jeopardy of decapitation in the university; and to use laughter as a strategic, powerful, political act of resistance and subversion against oppressive masculine power structures. We draw on and seek to enact Cixous’s notion of écriture feminine—a disruptive style of writing that provides a mode of being, speaking, and writing that subverts the power of masculine norms in order to be heard and to bring possibilities for change
Talking together: The effects of traditional Māori Pedagogy on children’s early literacy development
Get PDFThis article presents findings from a project that sought to determine the effects of a home-based literacy intervention on bilingual (English and Te Reo Māori) preschool children’s early literacy skills. The culturally responsive intervention, which was adapted from Tender Shoots, incorporated traditional Māori teaching and learning approaches, such as the use of storytelling, songs, games, and reminiscing about the past, as practices for supporting key cognitive skills crucial to foundational literacy, specifically phonological awareness and vocabulary knowledge. Over a 12-week period, during which the intervention was conducted, data were gathered from eight Māori preschool children and their families. The study utilised a crossover design. Four children and their families participated in the Rich Reading and Reminiscing (RRR) component of the intervention, which ran for six weeks, followed by the Strengthening Sound Sensitivity (SSS) portion of the intervention. The remaining four children completed the intervention in the reverse order of delivery. The crossover approach established a control in the study and allowed the effects of each part of the intervention on the aforementioned cognitive skills to be more clearly revealed. Overall, the data indicate that traditional Māori pedagogical practices helped to strengthen the early literacy skills of the children participating in the study
Investigating drivers of cyanobacterial blooms in Aotearoa – New Zealand lakes using sedimentary ancient DNA
Get PDFHealthy lake ecosystems support biodiversity and human populations. They provide many ecosystem services such as water, food and energy. Lakes can be impacted by natural disturbances, but they are increasingly threatened by human-induced disturbances. Studies have shown that eutrophication and climate change often enhance cyanobacteria over other photosynthetic taxa. As cyanobacterial blooms are becoming more frequent and intense throughout the world, more lake systems are being investigated. In some cases there is not a clear link between eutrophication and cyanobacterial blooms. One such example is Lake Pounui (Wairarapa, New Zealand), which has little intensive agriculture in its catchment but water quality has degraded markedly in the last decade. The lake now experiences heavy cyanobacterial blooms every summer. This could be due to the presence of a non-native fish population, the European perch (Perca fluviatilis). This thesis examined the relationship between cyanobacterial blooms and perch introduction in New Zealand
lakes, including a multi-trophic study in Lake Pounui. Perch were introduced c. 1870 in New Zealand but introduction records are patchy and sometimes non-existent. Moreover, most lake systems are not studied until they are already degraded. This thesis used a combination of traditional proxies (pollen, charcoal, pigments) and modern proxies (sedimentary ancient DNA, XRF scanning) from lake sediment cores to reconstruct lake ecology in pre-human times, after M¯aori settlement between the 13th to 15th century, and after European settlement from 1840 AD. Timelines and intensity of human impact were reconstructed with pollen, charcoal analysis, and sediment dating when possible.
Cyanobacterial communities in six lakes were reconstructed through their sedimentary ancient DNA (sedaDNA) using metabarcoding and droplet digital PCR (ddPCR) in Chapter 2. Bloom-forming species were present in all lakes prior to human arrival; however their overall abundance was low. Total cyanobacteria abundance and richness increased in all lakes after European settlement but was very pronounced in four lakes, where bloom-forming taxa became dominant. The trends in cyanobacterial abundance from ddPCR were then compared to cyanobacterial pigments (canthaxanthin, echinenone, myxoxanthophyll and zeaxanthin) using highperformance liquid chromatography in Chapter 3, to assess the likelihood of the historical increase observed. Pigments / sedaDNA relationships were more consistent when all pigments were summed, which is likely due to differences in species composition across lakes. The positive correlations confirmed an increase in cyanobacterial biomass since European arrival.
Due to patchy records for fish introduction, fish sedimentary DNA was compared to environmental DNA (eDNA) from water samples as a methodological check (Chapter 4) before applying this method to the sediment cores. This study was undertaken in three small and shallow lowland lakes by targeting perch and rudd (Scardinius erythrophthalmus). Fish DNA was evenly distributed across the whole lake except when the fish population was low. Samples collected from the sediment contained fish DNA more often than water samples in two out of the three small shallow lakes (including Lake Pounui). Sediment geochemistry probably impeded detection in the third lake. Perch sedaDNA was therefore used as an indication of fish presence in Lake Pounui for Chapter 5, which explored multitrophic changes in Lake Pounui over the last c. 1,000 years. In addition to pollen, charcoal, and 14C dating, XRF scanning was used to reconstruct mineralogic shifts from the catchment (Ti/inc, K/inc) and within the lake (inc/coh). Biological trends were reconstructed
by targeting the sedaDNA of bacteria (16S rRNA), microeukaryotes (18S rRNA), metazoans (CO1), and macrophytes (rbcL, trnL). Complemented by historical records and studies, the data produced in this thesis indicated that the biggest changes in Lake Pounui happened after European settlement (c. 1845), with land clearance, perch introduction, climate change, and probable fertiliser application driving the degradation of the water quality in c. 180 years. This study revealed shifts in native communities (macrophytes, bacteria, oligochaete worms) and the appearance of new species (perch, macrophytes, freshwater nematodes) previously undocumented using sedaDNA. The results highlight just how complex yet fragile lake ecosystems can be and how little we still know about them. Sedimentary ancient DNA is a useful tool to study the insidious and long-lasting impact of nonnative species on freshwater ecosystems because it widens the range of species that can be studied. However, it needs to be complemented with other proxies. This thesis provides a framework to study fish DNA in small shallow lakes (Chapter 4). It can also inform future management and restoration strategies in lakes, especially in Lake Pounui, by retracing historical water quality (Chapter 2) and identifying taxa present prior to, during, and after lake degradation (Chapter 5)
Arts Festival: 'Moonwalking Backwards Into The Future: "Poi E", Music Video and Documentary'
No full textResearch presentation - an audiovisual presentation drawing upon my published research (book chapter: 'Moonwalking Backwards Into The Future: "Poi E", Music Video and Documentary'). This presentation presented a Matuaranga Maori perspective of the temporal travels of music video and documentary, framed by the concept of whakapap. This presentation took place as part of a panel of 4 presenters who represented Te Kura Toi at the Arts Festival during the University of Waikato Open Day, 2023. This was an oral presentation, which included projected slides and videos from a PPT presentation. The audience included prospective students, their teachers and family members, community members, and current students and academic staff from the University of Waikato. My presentation was documented and photographed