The BOLD signal and neurovascular coupling in autism

BOLD (blood oxygen level dependent) fMRI (functional magnetic resonance imaging) is commonly used to study differences in neuronal activity between human populations. As the BOLD response is an indirect measure of neuronal activity, meaningful interpretation of differences in BOLD responses between groups relies upon a stable relationship existing between neuronal activity and the BOLD response across these groups. However, this relationship can be altered by changes in neurovascular coupling or energy consumption, which would lead to problems in identifying differences in neuronal activity. In this review, we focus on fMRI studies of people with autism, and comparisons that are made of their BOLD responses with those of control groups. We examine neurophysiological differences in autism that may alter neurovascular coupling or energy use, discuss recent studies that have used fMRI to identify differences between participants with autism and control participants, and explore experimental approaches that could help attribute between-group differences in BOLD signals to either neuronal or neurovascular factors

The design, development and evaluation of cross-platform mobile applications and services supporting social accountability monitoring

Local government processes require meaningful and effective participation from both citizens and their governments in order to remain truly democratic. This project investigates the use of mobile phones as a tool for supporting this participation. MobiSAM, a system which aims to enhance the Social Accountability Monitoring (SAM) methodology at local government level, has been designed and implemented. The research presented in this thesis examines tools and techniques for the development of cross-platform client applications, allowing access to the MobiSAM service, across heterogeneous mobile platforms, handsets and interaction styles. Particular attention is paid to providing an easily navigated user interface (UI), as well as offering clear and concise visualisation capabilities. Depending on the host device, interactivity is also included within these visualisations, potentially helping provide further insight into the visualised data. Guided by the results obtained from a comprehensive baseline study of the Grahamstown area, steps are taken in an attempt to lower the barrier of entry to using the MobiSAM service, potentially maximising its market reach. These include extending client application support to all identified mobile platforms (including feature phones); providing multi-language UIs (in English, isiXhosa and Afrikaans); as well as ensuring client application data usage is kept to a minimum. The particular strengths of a given device are also leveraged, such as its camera capabilities and built-in Global Positioning System (GPS) module, potentially allowing for more effective engagement with local municipalities. Additionally, a Short Message Service (SMS) gateway is developed, allowing all Global System for Mobile Communications (GSM) compatible handsets access to the MobiSAM service via traditional SMS. Following an iterative, user-centred design process, a thorough evaluation of the client application is also performed, in an attempt to gather feedback relating to the navigation and visualisation capabilities. The results of which are used to further refine its design. A comparative usability evaluation using two different versions of the cross-platform client application is also undertaken, highlighting the perceived memorability, learnabilitv and satisfaction of each. Results from the evaluation reveals which version of the client application is to be deployed during future pilot studies

A study of the cytoplasmic inclusions during oogenesis, spermatogenesis, maturation, fertilisation and the first cleavage division of the egg of the mouse (Mus musculus)

LISTS OF PAPERS EMBODIED IN THIS THESIS:"A Study of the Cytoplasmic Inclusions and Nucleolar Phenomena During the Oogenesis of the Mouse", 'Quart.Journ.Micr. Sci.' , vol.75, 1933."Effect of Ultra- centrifuging the Oocytes of the Mouse", 'Nature' , vol .142 , 1938."A Cytological Study of the Centrifuged Mouse", 'Quart. Journ. Micr. Aci.' , vo1.81,1940."A Study of the Cytoplasmic Inclusions during Maturation, Fertilisation and the First Cleavage Division of the Egg of the Mouse". Accepted for publication in Quart. Journ.Micr.Soi.1940.SUBMITTED AS ADDITIONAL EVIDEIVCE OF RESEARCH: "The Effect of Increased Daily Illumination and of Reversed Day and Night on the Oestrus Cycle of the Mouse (Mus musculus)", 'Proc. Roy. óc. Edin:r, vol.60, 1940

Identification and Functional Characterization of CNS Pericytes and the Role they Play in Neurovascular Coupling in Physiological and Pathological Conditions

Brain blood flow increases, evoked by neuronal activity, power neural computation and are the basis of BOLD functional imaging. However, it is controversial whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes. The experimental work within this thesis examines capillary pericytes, and the role they play in neurovascular coupling in physiological and pathological conditions. I show that pericytes can be identified using several protein markers and that, using the same technique, pericytes can be distinguished from other perivascular cell types. I demonstrate that pericytes respond to the neurotransmitters noradrenaline and glutamate. Noradrenaline depolarizes pericytes and constricts capillaries, and this constriction reflects pericyte contraction while glutamate, mimicking neuronal activity, hyperpolarizes pericytes and dilates capillaries, and this dilation reflects pericyte relaxation. Glutamate-evoked dilation is mediated by prostaglandin E₂ or a related compound acting at EP4 receptors, but requires nitric oxide release to suppress synthesis of the vasoconstrictor 20-HETE. In pathology, I show that pericytes die when exposed to ischaemia. This may lead to pericytes irreversibly constricting capillaries and to damage of the blood-brain barrier. Pericyte death increases on reperfusion after ischaemia, and is reduced by block of glutamate receptors or Ca2+ removal, but not by scavenging reactive oxygen species. These data establish pericytes as active regulators of capillary tone and thus as potential regulators of brain blood flow. My data also suggest prevention of pericyte death as a strategy to reduce the long-lasting blood flow decrease which contributes to neuronal death after stroke. This thesis also contains a discussion of how energy supply to the brain alters with age, and how this may affect the BOLD signal

Student Engagement and Learning Approaches during COVID-19: The Role of Study Resources, Burnout Risk, and Student Leader–Member Exchange as Psychological Conditions

Objectives: The primary objective of this study was to explore the interplay of psychological conditions that influenced personal engagement among university students. As a theoretical lens through which to investigate this, the study used the job demands-resources model, the study demands-resources model, and the leader–member exchange theory. This study further aimed to explore outcomes that supported students in becoming lifelong learners (i.e., deep-learning approach). Method: Participants were undergraduate students registered at a South African university. We used a purposive, non-probability sampling strategy and employed a cross-sectional survey research design. This study used Mplus version 8.6 for the statistical analyses. Results: Results showed that the psychological conditions of meaningfulness (study resources), availability (burnout risk), and safety (student–leader–member exchange) influenced student engagement. In addition, the results showed that study demands were positively associated with student engagement, although this association can be regarded as small. Furthermore, study resources and student engagement were associated with a deep approach to learning. Conclusions: Findings from the present study demonstrated that Kahn’s theory carried implications beyond the workplace and held true in a student learning environment. Further, an exploration of the psychological conditions that led to engagement showed that the job demands-resources model and the study demands-resources model could be used to operationalise study resources as psychological meaningfulness and burnout risk as availability. Similarly, in the context of exploring the student-lecturer relationship, student leader–member exchange could be operationalised as psychological safety. Implication for Practice: Leaders in higher education are encouraged to focus not only on ensuring that students receive adequate support in terms of structures and physical resources during periods of uncertainty, such as the global COVID-19 pandemic, but to adopt a holistic approach that includes considering all the psychological conditions that encourage and promote students’ engagement

The HIV Genomic Incidence Assay Meets False Recency Rate and Mean Duration of Recency Infection Performance Standards.

HIV incidence is a primary metric for epidemic surveillance and prevention efficacy assessment. HIV incidence assay performance is evaluated via false recency rate (FRR) and mean duration of recent infection (MDRI). We conducted a meta-analysis of 438 incident and 305 chronic specimens' HIV envelope genes from a diverse global cohort. The genome similarity index (GSI) accurately characterized infection stage across diverse host and viral factors. All except one chronic specimen had GSIs below 0.67, yielding a FRR of 0.33 [0-0.98] %. We modeled the incidence assay biomarker dynamics with a logistic link function assuming individual variabilities in a Beta distribution. The GSI probability density function peaked close to 1 in early infection and 0 around two years post infection, yielding MDRI of 420 [361, 467] days. We tested the assay by newly sequencing 744 envelope genes from 59 specimens of 21 subjects who followed from HIV negative status. Both standardized residuals and Anderson-Darling tests showed that the test dataset was statistically consistent with the model biomarker dynamics. This is the first reported incidence assay meeting the optimal FRR and MDRI performance standards. Signatures of HIV gene diversification can allow precise cross-sectional surveillance with a desirable temporal range of incidence detection

Engagement among academic staff and undergraduate students : a multilevel analysis

Higher education institutions have a great responsibility in that they play an important part in preparing and developing students who will one day be leaders, teachers, and influencers in their respective work environments. The COVID-19 pandemic has however had a real psychological impact on higher education institutions as it has influenced the engagement and overall well-being of academic staff and students. Past research has highlighted the importance of engagement in achieving positive organisational outcomes such as well-being and commitment, as well as both in-role and extra-role job performance among employees. In regard to students, engagement has been identified as a requisite for delivering quality work, developing life-long learners, and promoting students’ mental health. Scholars have further asserted that, to survive and ensure sustainable growth in a globally competitive and knowledge-driven society, a talented and engaged workforce needs to be cultivated and retained. Despite the proven importance of engagement, not enough research on this construct has been conducted. Scholars have called for further studies that assist learning institutions in understanding the conditions that lead to engagement and developing approaches or processes that foster such conditions. This research study drew on positive psychology, which is a field of study that focuses on positive emotions, meaning, and engagement with the aim of promoting optimal psychological functioning. Thus, in establishing positive outcomes for higher education institutions, this study set out to better understand what enabled engagement among both academic staff and students. For this study, three manuscripts were prepared. The first manuscript explored the conditions that cultivated engagement and psychological well-being among academic staff, and for this purpose the study established connections between Kahn’s theory on engagement, the job demands-resources model, organisational support theory, and the construct of reciprocity. In the second manuscript, the study demands-resources model and the leader-member exchange theory were used to operationalise Kahn’s psychological conditions beyond the employee–employer context to include university students. The study further set out to explore students’ learning approaches by extrapolating from work done using the job demands-resources model and the study demands-resources model so as to expand on the existing understanding of how student engagement influenced learning approaches. The third manuscript drew on crossover theory to explore mutual influences among academic staff and students, and the impact of these influences on the engagement of and outcomes relating to both parties. Purposive, non-probability sampling was used and cross-sectional data were collected through electronic surveys. The sample used in the first manuscript’s study comprised 160 academic staff members employed at a university in South Africa. The findings of this study revealed that the three psychological conditions (meaningfulness, safety, and availability), which were operationalised as lack of reciprocity, perceived organisational support, and burnout risk, were significantly related to emotional engagement. Perceived organisational support (job resources), which met the criteria for psychological safety and some components of meaningfulness, displayed the strongest association with engagement. Recommendations made to university management included considering policies, procedures, or interventions that gave employees the assurance that the university valued them, cared about their well-being, and regarded them as important contributors to institutional objectives, particularly during times of change or crisis. In the study presented in the second manuscript, the sample consisted of 1 594 undergraduate students enrolled at a South African university. The results showed that the psychological conditions of meaningfulness (study resources), availability (burnout risk), and safety (student leader-member exchange) as conceptualised in Kahn’s theory, influenced students’ engagement. Results further showed that high levels of student engagement fostered a deep-learning approach. University leaders were encouraged to take note of the clear gain in fostering student engagement and, therefore, to adopt an approach that considered all the psychological conditions that encouraged and promoted the engagement of students. In respect of the study presented in the third manuscript, a total of 1 594 students (level 1) were nested within 160 academic staff members (level 2). Findings from the study revealed non-significant relationships for both the crossover relationships proposed between academic staff and students. However, the findings did show that students’ perceptions of high-quality relationships with academic staff (student–LMX) were significantly related to their engagement. In terms of outcomes for academic staff, the results revealed that perceptions of lack of reciprocity from the student group were negatively associated with academic staff’s emotional engagement. University leaders were encouraged to consider interventions that might support and better equip academic staff to develop high-quality exchange relationships with students. The study recommended that university leaders should adopt a collective approach in addressing the component of mutual influences among academic staff and students. Such an approach would lead to the improvement of well-being among employees and the cultivation of a culture of life-long learning among students, which hold significant benefits.Thesis (PhD (Industrial and Organisational Psychology))--University of Pretoria, 2021.Human Resource ManagementPhD (Industrial and Organisational Psychology)Unrestricte

Emergencia del derecho a la alimentación: Latinoamérica en la construcción del régimen internacional de los derechos humanos

This article reconstructs the origin and the trajectory of the right to food from a constructivist perspective on the emergence of norms. To this end, a press review was conducted using the Google News archive, the speeches of delegations during the decision-making moments of the Universal Declaration of Human Rights were analyzed, and the process of including the right to food within this international document was reconstructed. The authors conclude that the role of Latin American delegations in the construction of the international human rights regime was crucial and, therefore, question the idea that its origin was in the matrix of the hegemonic countries of the international system. Likewise, they question the sequential vision of the stages of creation of a norm and the impossibility of observing trajectories after its process of creation. In this sense, this article, through a case study, not only contributes to the understanding of the right to food, but also works to question the dominant theory on the emergence of norms and both realistic and critical visions of human rights.El presente artículo reconstruye el origen y la trayectoria del derecho a la alimentación desde una perspectiva constructivista sobre la emergencia de las normas. Para ello, se hizo una revisión de prensa utilizando el archivo de Google News, se analizaron los discursos de las delegaciones durante los momentos de toma de decisión de la Declaración Universal sobre los Derechos del Hombre y se reconstruyó el proceso de inclusión del derecho a la alimentación dentro de ella. Los autores concluyen que el papel de las delegaciones latinoamericanas en la construcción del régimen internacional de los derechos humanos fue crucial y, por ende, cuestionan la idea de que su origen haya estado en la matriz de los países hegemónicos del sistema internacional. Asimismo, cuestionan la visión secuencial sobre las etapas de creación de una norma y la imposibilidad de observar su trayectoria luego del proceso de creación. En ese sentido, este artículo, a través de un estudio de caso, no solo contribuye al entendimiento sobre el derecho a la alimentación, sino que sirve para cuestionar la teoría dominante sobre la emergencia de las normas y las visiones tanto realistas como críticas sobre los derechos humanos