title: The genomic footprint of coastal earthquake uplift

authors: Parvizi, Elahe

subjects: Science & Technology

abstract: Theory suggests that catastrophic earth-history events can drive rapid biological evolution, but empirical evidence for such processes is scarce. Destructive geological events such as earthquakes can represent large-scale natural experiments for inferring such evolutionary processes. We capitalized on a major prehistoric (800 yr BP) geological uplift event affecting a southern New Zealand coastline to test for the lasting genomic impacts of disturbance. Genome-wide analyses of three co-distributed keystone kelp taxa revealed that post-earthquake recolonization drove the evolution of novel, large-scale intertidal spatial genetic ‘sectors’ which are tightly linked to geological fault boundaries. Demographic simulations confirmed that, following widespread extirpation, parallel expansions into newly vacant habitats rapidly restructured genome-wide diversity. Interspecific differences in recolonization mode and tempo reflect differing ecological constraints relating to habitat choice and dispersal capacity among taxa. This study highlights the rapid and enduring evolutionary effects of catastrophic ecosystem disturbance and reveals the key role of range expansion in reshaping spatial genetic patterns.

text: The genomic footprint of coastal earthquake uplift Theory suggests that catastrophic earth-history events can drive rapid biological evolution, but empirical evidence for such processes is scarce. Destructive geological events such as earthquakes can represent large-scale natural experiments for inferring such evolutionary processes. We capitalized on a major prehistoric (800 yr BP) geological uplift event affecting a southern New Zealand coastline to test for the lasting genomic impacts of disturbance. Genome-wide analyses of three co-distributed keystone kelp taxa revealed that post-earthquake recolonization drove the evolution of novel, large-scale intertidal spatial genetic ‘sectors’ which are tightly linked to geological fault boundaries. Demographic simulations confirmed that, following widespread extirpation, parallel expansions into newly vacant habitats rapidly restructured genome-wide diversity. Interspecific differences in recolonization mode and tempo reflect differing ecological constraints relating to habitat choice and dispersal capacity among taxa. This study highlights the rapid and enduring evolutionary effects of catastrophic ecosystem disturbance and reveals the key role of range expansion in reshaping spatial genetic patterns.

year: 2020

title: Dynamics and precursor signs for phase transitions in neural systems

authors: Negahbani, Ehsan

subjects: nonlinear dynamics

abstract: This thesis investigates neural state transitions associated with sleep, seizure and anaesthesia. The aim is to address the question: How does a brain traverse the critical threshold between distinct cortical states, both healthy and pathological? Specifically we are interested in sub-threshold neural behaviour immediately prior to state transition. We use theoretical neural modelling (single spiking neurons, a network of these, and a mean-field continuum limit) and in vitro experiments to address this question.
Dynamically realistic equations of motion for thalamic relay neuron, reticular nuclei, cortical pyramidal and cortical interneuron in different vigilance states are developed, based on the Izhikevich spiking neuron model. A network of cortical neurons is assembled to examine the behaviour of the gamma-producing cortical network and its transition to lower frequencies due to effect of anaesthesia. Then a three-neuron model for the thalamocortical loop for sleep spindles is presented. Numerical simulations of these networks confirms spiking consistent with reported in vivo measurement results, and provides supporting evidence for precursor indicators of imminent phase transition due to occurrence of individual spindles.
To complement the spiking neuron networks, we study the Wilson–Cowan neural mass equations describing homogeneous cortical columns and a 1D spatial cluster of such columns. The abstract representation of cortical tissue by a pair of coupled integro-differential equations permits thorough linear stability, phase plane and bifurcation analyses. This model shows a rich set of spatial and temporal bifurcations marking the boundary to state transitions: saddle-node, Hopf, Turing, and mixed Hopf–Turing. Close to state transition, white-noise-induced subthreshold fluctuations show clear signs of critical slowing down with prolongation and strengthening of autocorrelations, both in time and space, irrespective of bifurcation type.
Attempts at in vitro capture of these predicted leading indicators form the last part of the thesis. We recorded local field potentials (LFPs) from cortical and hippocampal slices of mouse brain. State transition is marked by the emergence and cessation of spontaneous seizure-like events (SLEs) induced by bathing the slices in an artificial cerebral spinal fluid containing no magnesium ions. Phase-plane analysis of the LFP time-series suggests that distinct bifurcation classes can be responsible for state change to seizure. Increased variance and growth of spectral power at low frequencies (f < 15 Hz) was observed in LFP recordings prior to initiation of some SLEs. In addition we demonstrated prolongation of electrically evoked potentials in cortical tissue, while forwarding the slice to a seizing regime. The results offer the possibility of capturing leading temporal indicators prior to seizure generation, with potential consequences for understanding epileptogenesis.
Guided by dynamical systems theory this thesis captures evidence for precursor signs of phase transitions in neural systems using mathematical and computer-based modelling as well as in vitro experiments.

text: Dynamics and precursor signs for phase transitions in neural systems This thesis investigates neural state transitions associated with sleep, seizure and anaesthesia. The aim is to address the question: How does a brain traverse the critical threshold between distinct cortical states, both healthy and pathological? Specifically we are interested in sub-threshold neural behaviour immediately prior to state transition. We use theoretical neural modelling (single spiking neurons, a network of these, and a mean-field continuum limit) and in vitro experiments to address this question.
Dynamically realistic equations of motion for thalamic relay neuron, reticular nuclei, cortical pyramidal and cortical interneuron in different vigilance states are developed, based on the Izhikevich spiking neuron model. A network of cortical neurons is assembled to examine the behaviour of the gamma-producing cortical network and its transition to lower frequencies due to effect of anaesthesia. Then a three-neuron model for the thalamocortical loop for sleep spindles is presented. Numerical simulations of these networks confirms spiking consistent with reported in vivo measurement results, and provides supporting evidence for precursor indicators of imminent phase transition due to occurrence of individual spindles.
To complement the spiking neuron networks, we study the Wilson–Cowan neural mass equations describing homogeneous cortical columns and a 1D spatial cluster of such columns. The abstract representation of cortical tissue by a pair of coupled integro-differential equations permits thorough linear stability, phase plane and bifurcation analyses. This model shows a rich set of spatial and temporal bifurcations marking the boundary to state transitions: saddle-node, Hopf, Turing, and mixed Hopf–Turing. Close to state transition, white-noise-induced subthreshold fluctuations show clear signs of critical slowing down with prolongation and strengthening of autocorrelations, both in time and space, irrespective of bifurcation type.
Attempts at in vitro capture of these predicted leading indicators form the last part of the thesis. We recorded local field potentials (LFPs) from cortical and hippocampal slices of mouse brain. State transition is marked by the emergence and cessation of spontaneous seizure-like events (SLEs) induced by bathing the slices in an artificial cerebral spinal fluid containing no magnesium ions. Phase-plane analysis of the LFP time-series suggests that distinct bifurcation classes can be responsible for state change to seizure. Increased variance and growth of spectral power at low frequencies (f < 15 Hz) was observed in LFP recordings prior to initiation of some SLEs. In addition we demonstrated prolongation of electrically evoked potentials in cortical tissue, while forwarding the slice to a seizing regime. The results offer the possibility of capturing leading temporal indicators prior to seizure generation, with potential consequences for understanding epileptogenesis.
Guided by dynamical systems theory this thesis captures evidence for precursor signs of phase transitions in neural systems using mathematical and computer-based modelling as well as in vitro experiments.

year: 2014

title: Social marketing in Aotearoa New Zealand: Analysing its evolution to  inform, improve, and justify its future

authors: Antric, Tim

subjects: Social marketing

abstract: Plotting the evolution and experience of social marketing in Aotearoa New Zealand, this thesis charts a creative landscape of productive future research directions in the field.
Starting with the question, “What can the social marketing discipline learn from the unique experience of social marketers in Aotearoa New Zealand?”, the research draws from appreciative inquiry interviews with 20 experienced social marketers and reviews of relevant government documents and published commentaries. Analysis of the findings sparked three substantive papers included in this thesis by publication: two of these have already been published, and one is currently being revised for resubmission. Presented in chapters four to six, the three papers analyse the growth and decline of social marketing in Aotearoa New Zealand; the overlapping functions of social marketing and public relations; and the incorporation of indigenous communities’ values into social marketing.
1.	The growth and decline of social marketing
In an original developmental framework for social marketing in Aotearoa New Zealand, the first of the three papers tracks four phases through four different governments as follows: (1) Foundation (1984-1990); (2) Establishment (1990-1999); (3) Growth (1999-2008); and (4) Decline (2008-2017).  The research found that political support is key to enabling ongoing social marketing contributions to social change and argues for the development of an evidence base for effective communication to political decision-makers to attract such support.
2.	Public relations, reputation and social marketing 
In identifying the strong interdisciplinary nature of social marketing in Aotearoa New Zealand, the second paper focuses on the intersections of public relations, marketing, advertising and health promotion. It illustrates how local definitions of, and practices within, social marketing draw from different disciplines. 
Social marketing has also been shaped by the nation’s founding document, Te Tiriti o Waitangi (The Treaty of Waitangi). The Crown’s revised principles of Te Tiriti offer further opportunity to improve social marketing through indigenous autonomy, partnership, active protection, equity and options.
3.	Decolonising social marketing through an indigenous lens
The third paper tackles the question: can social marketing address health inequity between Māori and non-Maori? It deals with this question in the context of the international shift in social marketing away from a focus on individual change to a focus on societal and social change. The paper’s findings support an ongoing critical analysis of social marketing from an indigenous worldview.
Conclusions
Overall, the thesis looks at the impact of political ideologies on the function of social marketing and makes novel suggestions on how social marketing academics and practitioners can attract political support. It calls for increasing interdisciplinarity to engage effectively with contemporary issues and encourages social marketers to search for “soul” in organisations. 
The thesis also identifies indigenous Māori culture as a potential inspiration for social marketers to improve their interactions with indigenous people in Aotearoa New Zealand as well as across the globe. It recommends that future social marketing interventions not only be informed by indigenous worldviews but also be led by indigenous communities involved from the planning stages.

text: Social marketing in Aotearoa New Zealand: Analysing its evolution to  inform, improve, and justify its future Plotting the evolution and experience of social marketing in Aotearoa New Zealand, this thesis charts a creative landscape of productive future research directions in the field.
Starting with the question, “What can the social marketing discipline learn from the unique experience of social marketers in Aotearoa New Zealand?”, the research draws from appreciative inquiry interviews with 20 experienced social marketers and reviews of relevant government documents and published commentaries. Analysis of the findings sparked three substantive papers included in this thesis by publication: two of these have already been published, and one is currently being revised for resubmission. Presented in chapters four to six, the three papers analyse the growth and decline of social marketing in Aotearoa New Zealand; the overlapping functions of social marketing and public relations; and the incorporation of indigenous communities’ values into social marketing.
1.	The growth and decline of social marketing
In an original developmental framework for social marketing in Aotearoa New Zealand, the first of the three papers tracks four phases through four different governments as follows: (1) Foundation (1984-1990); (2) Establishment (1990-1999); (3) Growth (1999-2008); and (4) Decline (2008-2017).  The research found that political support is key to enabling ongoing social marketing contributions to social change and argues for the development of an evidence base for effective communication to political decision-makers to attract such support.
2.	Public relations, reputation and social marketing 
In identifying the strong interdisciplinary nature of social marketing in Aotearoa New Zealand, the second paper focuses on the intersections of public relations, marketing, advertising and health promotion. It illustrates how local definitions of, and practices within, social marketing draw from different disciplines. 
Social marketing has also been shaped by the nation’s founding document, Te Tiriti o Waitangi (The Treaty of Waitangi). The Crown’s revised principles of Te Tiriti offer further opportunity to improve social marketing through indigenous autonomy, partnership, active protection, equity and options.
3.	Decolonising social marketing through an indigenous lens
The third paper tackles the question: can social marketing address health inequity between Māori and non-Maori? It deals with this question in the context of the international shift in social marketing away from a focus on individual change to a focus on societal and social change. The paper’s findings support an ongoing critical analysis of social marketing from an indigenous worldview.
Conclusions
Overall, the thesis looks at the impact of political ideologies on the function of social marketing and makes novel suggestions on how social marketing academics and practitioners can attract political support. It calls for increasing interdisciplinarity to engage effectively with contemporary issues and encourages social marketers to search for “soul” in organisations. 
The thesis also identifies indigenous Māori culture as a potential inspiration for social marketers to improve their interactions with indigenous people in Aotearoa New Zealand as well as across the globe. It recommends that future social marketing interventions not only be informed by indigenous worldviews but also be led by indigenous communities involved from the planning stages.

year: 2021