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Demand for schooling in rural Senegal
No full textThis thesis aims to understand the determinants of household demand for schooling in rural Senegal. Using an original dataset including 504 households living in the North of Senegal and based on the results of a literature review on the determinants of schooling, it analyses in three empirical chapters what explains household behaviour when it comes to investing in education.
The first empirical chapter explores determinants of schooling by fitting a logit model to estimate the likelihood of children being enrolled at school conditional on child, parent, household, school and community characteristics. It shows that the determinants of schooling for girls and boys must be analysed separately as the estimated coefficients are significantly different for the boy and girl subsamples. Girls’ education depends on family structure, notably the number of young children in the household, and the household’s income, whereas boys’ education depends on their mother’s education. This suggests that the opportunity cost of time may be a barrier for girls as they are usually required to help to take care of young children. However, the fact that the size of the area cultivated by the household is not statistically significant suggests that the need for child labour for agricultural work is not a barrier to schooling. Both girls and boys are affected by the availability of schools and the community social norms proxied by the share of children attending a Koranic school. Interestingly, girls and boys seem to benefit from living in a household with access to electricity and a robustness check using an instrumental variable approach shows that this result is not due to the endogeneity of the household’s access to electricity. Further robustness checks include different ways of measuring household income and parental education and alternative estimation methods. They confirm the conclusions of the main model.
The second empirical chapter deals with the intergenerational transmission of schooling and, more specifically, the relative effects of mother’s and father’s education on the level of schooling attained by a child. The chapter starts with a review of different published studies from Sub-Saharan African countries where the effects of mother’s and father’s education were simultaneously estimated. The review finds that, on average, mother’s education is more important than father’s education in explaining the educational achievement of young children, whereas the opposite is true for older children. Using my dataset, I then replicate a study on the effects of parental education on a child’s level of schooling attained in Senegal that found a larger effect of father’s education than mother’s education, after controlling for the endogeneity of education. Using a similar method, I also show that father’s education is more important than mother’s education in my sample but my results are sensitive to the estimation method used and age range of children included in the sample. Taking into consideration that the number of years of schooling are censored, that is children still enrolled at school have not achieved their final level of schooling, increases the importance of mother’s education relative to father’s education. Also, in line with my literature review and another published review, my results show that mother’s education is more important for younger children, whereas father’s education is more important for older children.
The third empirical chapter attempts to shed light on the decision process of polygynous households regarding children’s education. It contributes to the limited literature on the intra-household allocation of resources of polygynous households. First, it shows that despite the higher social status of their mother, children of senior co-wives do not enjoy more schooling. Secondly, the positive effect of other co-wives’ education on a child’s level of education suggests cooperation between co-wives in raising children. Finally, I test if, when it comes to decisions regarding schooling, polygynous households act as a single entity (unitary model) or as separate entities (collective model). I overcome the fact that I cannot account for unobserved heterogeneity of mother’s characteristics, which could explain differences in schooling achievement of siblings from different co-wives, by using an original method taking advantage of heterogeneous effects of additional brothers and sisters on a child’s education. My results show that, at least for girls, decisions regarding children’s education are made separately between co-wives. I argue that this finding suggests that husbands tend to equalise the number of educated children per co-wife. This is an important result for policies seeking to target children living in polygynous households. Moreover, this behaviour may have a detrimental effect on a child’s achievement as resources for education are less efficiently allocated than in monogamous households
Leptin and glucose homeostasis in the Zebrafish
No full textObesity and type 2 diabetes mellitus (T2DM) are among the most common and costly health-related issues worldwide, and both have been declared a global epidemic by the World Health Organization. A key characteristic of these conditions is disturbed leptin signalling. Leptin, named after the Greek word for ‘lean’ (λεπτός), is a hormone that plays a key role in energy homeostasis. Although known best for its adipostatic role in mammals, leptin also regulates glucose homeostasis independent of effects on adipostasis. To date, the mechanism through which leptin exerts its glucoregulatory actions remains largely unknown. This thesis investigates whether leptin regulates glucose homeostasis via the canonical WNT pathway in the zebrafish (Danio rerio). Non-mammalian leptin studies have been conducted for only a little bit over a decade, and still comprise but a tiny fraction (<2%) of the total research in this field. However, these studies are needed not only to answer comparative questions, but uncovering the evolutionary origins of leptin function will clarify our understanding of how this hormone functions in the human body.
Using the CRISPR/Cas9 mutagenesis system, stable mutant zebrafish lines were successfully generated (chapter 2). These fish had a homozygous knockout of either the leptin-a gene (lepa), the leptin-b gene (lepb) or the leptin receptor gene (lepr). Next, protocols were established to investigate glucose homeostasis in adult zebrafish (chapter 3). Existing procedures for intraperitoneal injection and blood sampling were adapted to create a protocol for intraperitoneal glucose tolerance tests in adult zebrafish. In addition to this acute hyperglycaemic challenge, a glucose-immersion protocol was established to allow for the investigation of artificially-induced persistent hyperglycaemia as well.
Combining the mutant fish generated in chapter 2 with the protocols established in chapter 3, the effects of leptin- and leptin receptor deficiency were characterized in adult zebrafish (chapter 4). It was confirmed that under normal feeding conditions, leptin regulates glucose homeostasis but not adipostasis in the zebrafish. However, in times of nutrient excess leptin was found to regulate body weight and standard length, and glucose homeostasis was impaired.
Next, the canonical WNT pathway was investigated as a potential mediator of the glucoregulatory effects of leptin. Taking advantage of the optical transparency of zebrafish larvae, a transgenic zebrafish line expressing fluorescence upon WNT pathway activation was used to demonstrate that leptin directly activates the canonical WNT pathway in vivo, specifically in the hypothalamus (chapter 5). Finally, various pharmacological manipulations of the canonical WNT pathway were performed in leptin-mutant fish and wild type controls to demonstrate that leptin regulates glucose homeostasis via the canonical WNT pathway (chapter 6).
Together, these findings show a novel essential role of the canonical Wnt pathway in the neuroendocrine control of glucose homeostasis in zebrafish. Furthermore, these data highlight that leptin may primarily have evolved as a glucoregulatory hormone with its role of an adipostat acquired later in evolution. Finally, the glucoregulatory action of leptin is mediated via the Wnt pathway - an essential mechanism that appears preserved throughout the vertebrate phylum
Musical activity in older adulthood reverses age-related emotion recognition decline
No full textEmotion recognition is key to social functioning, though it declines across the adult lifespan. Why decline occurs and how it should be addressed is yet to be understood. In this thesis I investigated potential causes of emotion recognition decline, as well as the efficacy of a novel music training intervention with older adults to improve emotion recognition. I put forth in the Introduction the argument that age-related declines in emotion recognition are primarily caused by neurodegeneration, and that because music training is a uniquely powerful stimulus for facilitating neuroplasticity, musical engagement in older adulthood should improve neuropsychological functioning by attenuating neurodegeneration, particularly in the frontal lobes.
In Study 1, young (aged 18 to 30 years) and older adults (aged 59 years and older) completed laboratory tasks assessing facial and musical emotion recognition, facial age estimation, fluid intelligence, and musical competence. During all but the musical competence task, surface-level activity in the medial and lateral prefrontal cortex (PFC) was monitored using functional near-infrared spectroscopy. Older adults performed more poorly on the musical emotion task relative to young adults, and this was not due to having worse musical competence or cognitive ability. Face processing decline also did not appear to cause emotion recognition difficulties among older adults, as performance on the two face tasks were not correlated. Older adults also showed greater left and right lateral PFC activation during the two emotion tasks compared to young adults, and a contrast between the two emotion tasks within the older group revealed greater music-related than face-related activation in the lateral regions. Neurodegeneration was the most compelling explanation of the findings. Older adults appeared to require greater activation in cognitive control areas to compensate for neurodegeneration, proportionate to task difficulty.
In Study 2, the older adults who participated in Study 1 were randomly assigned either to a four-month, group-based music appreciation or guitar learning intervention designed specifically for this research. After the intervention, participants completed the same tasks as outlined above, again, while cortical PFC activity monitored. Facial and musical emotion recognition improved between pre- and post-intervention, collapsing across both groups, but I did not find evidence for a relative benefit of one intervention over the other on the behavioural or neuroimaging measures. However, older adults’ age moderated the effect of intervention group on changes in behavioural musical emotion recognition and PFC activation during facial emotion recognition. For guitar learners but not music appreciators, advancing age was associated with greater improvements in musical emotion recognition and increases in facial emotion-related PFC activation. Guitar learning, thus, promoted emotion recognition for those at ages where neurodegeneration has had its greatest impact.
The implications of Study 1 and Study 2 and their relation to previous research are examined in the General Discussion. Overall, the take-home message is this: we should look to brain health to both understand and improve older adults’ emotion recognition, and music training is a suitable vehicle to do so
Effects of bathymetry, wave environment and sea level on rip current dynamics in a wave-resolving model
No full textRip currents and nearshore circulation are important as they influence sediment transport and have the potential to be hazardous to beach users. Obtaining field observations of the flow characteristics is expensive thus the need for cheaper options to gain understanding into how they work. Nearshore wave models can be used to provide insight on rip development despite being unsuitable for providing exact forecasts of beach response. This study aimed to simulate rip current formation under varying bathymetric and wave conditions.
A nearshore Boussinesq wave model (FUNWAVE) was used to simulate wave-driven currents in two bathymetric conditions: one domain based on bathymetric data collected from Ocean Beach, Dunedin, New Zealand, and the other using the same bathymetric data averaged to create an alongshore uniform domain with a single rip channel. Simulations were run that tested the effects of incrementally increasing the complexity of the wave field on both bathymetries. Variables included in the wave field were frequency distribution, directional spread and mean incidence. One set of wave conditions was also selected for use in simulations that represented high and low tide conditions at Ocean Beach.
Simulations with large significant wave heights (1.5 m) were less likely to retain material in the surf zone with ~10-15% fewer tracers retained compared to simulations with 0.5 m waves. Simulations of the alongshore averaged bathymetry all formed rip currents near the channel while more complex wave conditions generated eddies and multiple exit pathways from the surf zone. Complex conditions in both the bathymetry and wave field lead to the formation of multiple exit pathways from the surf zone. With increasingly “real-life” conditions, rip current dynamics became less tied to bathymetric variability.
Larger significant wave height was the most significant contributor to wave orbital velocity increase. Simulations with a large significant wave height featured a higher proportion of the domain exceeding the erosive threshold for wave orbital velocity.
Rip currents at Ocean Beach vary depending on the wave conditions with significant wave height and directional spread being particularly important. In addition, the amount of sediment exiting the surf zone is controlled by different processes that depend on wave conditions. For less energetic conditions the number of exit pathways will be important, in more energetic conditions sediment will likely leave the surf zone regardless of the directional spread or mean incidence of the wave field
NZDep2018 analysis of census 2018 variables - DHB08: Tairawhiti
No full textFor further information about data sources, interpretation of the graphs, and cautions, please see the separate Introduction Chapter
All data relating to the 2018 census is provided by Stats NZ, https://www.stats.govt.nz/
NZDep2018 analysis of census 2018 variables - TA003: Kaipara District
No full textFor further information about data sources, interpretation of the graphs, and cautions, please see the separate Introduction Chapter
All data relating to the 2018 census is provided by Stats NZ, https://www.stats.govt.nz/
Driving away rats: candidate fertility targets for mammalian gene drives
No full textThe dispersal and subsequent proliferation of mammalian invasive species in new environments has significant impacts on food security, disease, and conservation worldwide, particularly in island nations where they have disproportionately large consequences in these unique insular ecosystems. Traditional control techniques such as kill trapping, and poison control strategies have served well in the past for controlling problem species. However, concerns for animal welfare, off-target effects and limits to long-term efficiency have fuelled a search for novel, highly effective control techniques. Harnessing the power of “super Mendelian inheritance”, gene drive technology can propagate a particular gene through a population, even if it is deleterious to the organism. By targeting key genes associated with reproductive processes, gene drives can be used to control a species by inducing infertility in one sex, while the other sex continues to propagate the impaired fertility phenotype through the population. Despite established theory and empirical experiments using gene drives in insects, there is, as yet, no gene drive fertility control system established for mammals. A major current limitation is the lack of validated candidate genes for mammalian gene drive systems.
My research establishes the first systematic review framework for identifying candidate genes for a range of invasive species. Using this framework, I have subsequently identified a list of 17 genes that could be targeted in a rodent gene drive system. Remarkably, results are significantly biased towards genes with male-specific fertility phenotypes, as those with female fertility phenotypes demonstrate additional pleiotropic attributes. I also provide a foundational bioinformatics pipeline to characterise these loci across populations of target invasive species, applying this to whole genome sequences from 42 ship rat (Rattus rattus) samples representative of the Aotearoa New Zealand (NZ) population. Subsequently, highly conserved sequences were used to inform potential gRNA design and parameters in a computational model exploring the dynamics of a CRISPR-Cas9 homing gene drive in the NZ ship rat population. Results from the model are consistent with previous findings that suggest targeting female fertility more reliably results in successful eradication, compared with targeting male fertility. However, the evident disparity between optimal theoretical parameters (i.e., targeting female fertility), and biological feasibility (i.e., candidate gene bias towards the male reproductive system) presents an important technical challenge for the design and development of mammalian gene drives.
To investigate the feasibility of utilising the same gene drive targets across a cohort of species, I further employed comparative genomics to evaluate sequence conservation of my candidate genes across nine invasive species in NZ - house mouse (Mus musculus), Norway rat (Rattus norvegicus), ship rat (Rattus rattus), European rabbit (Oryctolagus cuniculus), European hedgehog (Erinaceus europaeus), domestic cat (Felis catus), domestic ferret (Mustela putorius furo), stoat (Mustela erminea), and brushtail possum (Trichosurus vulpecula). Although no target loci that met my criteria were conserved across my evaluated list of invasive species, it is evident that several candidate genes have highly conserved sequences between distantly related groups of invasive species, implying that the molecular co-design of mammalian gene drives across several invasive species may be feasible.
Gene drive technology is still in its infancy, and many questions regarding the risks and benefits of its applications are yet to be resolved. However, in an era of global biodiversity crisis, it is necessary to thoroughly assess promising new avenues for the control of invasive species. My research contributes a list of strong candidate genes that could be targeted in a rodent gene drive for population suppression, and I further refined that list by identifying genes that may have strong multi-species utility. Such results progress research in a highly economically, socially, and environmentally significant area for international conservation
NZDep2018 analysis of census 2018 variables - TA031: Napier City
No full textFor further information about data sources, interpretation of the graphs, and cautions, please see the separate Introduction Chapter
All data relating to the 2018 census is provided by Stats NZ, https://www.stats.govt.nz/
NZDep2018 analysis of census 2018 variables - TA035: South Taranaki District
No full textFor further information about data sources, interpretation of the graphs, and cautions, please see the separate Introduction Chapter
All data relating to the 2018 census is provided by Stats NZ, https://www.stats.govt.nz/
The Salmi Concertati (1626) of Giovanni Rovetta : a complete transcription with a general commentary
No full textGiovanni Rovetta’s Salmi Concertati (1626) is a collection of twenty compositions: four instrumental canzoni, four motets and twelve psalms with independent and accompanying violin parts. This set and other sacred works by Rovetta seem to have been neglected in favour of the brilliant ‘stile concerto’ settings of Claudio Monteverdi (1567-1643). Rovetta, a figure neither as forceful nor as celebrated as Monteverdi, has been overlooked or airily dismissed by musicologists. Yet during the period in which he lived Rovetta’s church music would have been well-known by the public because of its extraordinarily wide distribution. [Extract from Introduction