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Sculpting Visual Cortex: How Recurrent Structure, Modulatory Signals, and Development Shape V1 Responses
No full textThe primary visual cortex (V1) is the first cortical area to process retinal signals, and the classical picture featuring feedforward orientation-selective inputs and recurrent amplification is well established. However, this view is incomplete: V1 receives modulatory inputs from non-visual sources and orientation selectivity emerges even before visual experience.
My thesis explores how modulation and development shape V1 responses across three complementary projects. In my first project, I show that optogenetic stimulation of macaque V1 excitatory neurons produces diverse single-cell responses yet preserves the population statistics of neurons whose feature preferences match the visual stimulus – a phenomenon we term "rate reshuffling." While randomly connected networks can reproduce this effect, they require strong coupling and tight excitatory-inhibitory cancellation inconsistent with observations. In contrast, I show that networks with feature-dependent structure generate reshuffling robustly under more biologically plausible conditions.
My second project explores the underlying mechanisms by developing a mean-field framework for networks with feature-dependent structure in which decomposing global activity into tuned and untuned components reveals effective interactions between the visual-stimulus-matched and baseline populations. A linear response analysis then shows that strongly-coupled, feedback-inhibition-dominated networks exhibit suppressive baseline-to-matched interactions, robustly explaining the lack of matched responses to the optogenetic stimulus.
In my final project, I characterize how endogenous mechanisms generate orientation selective and spatially organized visual responses in ferret V1 before the onset of vision. I propose that strong receptive field biases drive recurrent interactions to form phase-insensitive responses in layer 4, which are transformed into orientation-selective and spatially periodic activity in layers 2/3. This structure differs from the mature architecture but naturally emerges from activity-dependent plasticity driven by geniculate activity prior to eye-opening. My findings reveal mechanisms by which visually and behaviorally relevant signals can coexist in separate populations and demonstrate that structured visual representations can emerge without prior visual experience
The Effect of Multimodal Conversational AI on Job Interview Anxiety and Performance among ESL Students
No full textSpeaking a second language is often considered one of the most anxiety-inducing skills to acquire. For many ESL learners, limited vocabulary, fear of judgement, and lack of sufficient practice in a crowded classroom can impede their speaking performance. Although the literature has predominantly focused on interventions in general English classrooms, English for Specific Purposes courses, where English focuses on professional communication, remain underdeveloped, with most research focused on writing and reading. This gap is evident in the context of job interviews, which require not only linguistic knowledge but also familiarity with domain-specific vocabulary and discourse competence.
This study employed a quasi-experimental, mixed-method design, where experimental groups practiced job interview questions with a multimodal embodied conversational AI (MECAI) in mixed reality (MR) simulation (Group1), or ChatGPT voice application (Group 2). The control group did not receive any treatment and relied on traditional classroom activities instead. Students (N = 55), ages 18-64 years from a community college participated in the study. All students completed a pretest and were randomly assigned to three conditions. The experimental conditions were assigned to a six-week intervention. After the intervention, all students completed a posttest questionnaire.
Finally, 36 students were interviewed to explore their perceptions of the study intervention. The pre-and posttest measures comprised eight mock job interview questions, where students’ responses were evaluated through a rubric that included seven criteria: fluency, pronunciation, intonation and stress, grammar and sentence structure, vocabulary use, content relevance, and the use of work-based examples. The pretest also included 33 Foreign Language Anxiety Scale (FLCAS) items rated on a 5-point Likert scale and heart rate measures during the pre-and post-mock job interviews. The interaction with AI conversation logs negotiation of meaning (NoM) patterns within the Task-based Language Teaching method (TBLT) were examined using a Computer Mediated Discourse Analysis (CMDA) coding scheme. The reflection interviews consisted of 11 questions examining students’ perceptions of their conditions, the teacher’s role, experimental students’ interaction with AI and the traditional condition experience, and whether each condition contributed to anxiety reduction and improved speaking performance.
Key findings showed that although there was no significant difference between all groups in the pre-intervention mock job interview, FLCAS, or heart rate, both AI groups (MECAI in MR and ChatGPT voice app) showed significant post-intervention improvement, with the MR group demonstrating the most improvement in fluency, vocabulary, and total language performance. However, despite the fact that students in the AI conditions expressed anxiety reduction during reflection interviews, posttests of FLCAS and heart rate demonstrated no statistically significant reduction in physiological or self-reported anxiety levels. The experimental groups conversational logs showed more NoM pattern production than the ChatGPT voice group. Both AI groups helped address gaps in teachers and curriculum knowledge in ESP-oriented pedagogy, where speaking remains underexplored
Exploring the Role of Coaching in Managing Emotional Job Demands and Developing Self-Efficacy for Black Male Principals: A Qualitative Case Study
No full textThis qualitative case study explored how Black male principals experience coaching, specifically examining its role in managing emotional job demands and developing self-efficacy.
Using a multiple perspective interview approach, the researcher conducted semi-structured interviews with nine participants: five current Black male principals, three coaches, and one founder of The Fellowship, a national leadership development organization. The study addressed three research questions examining the types of coaching received, how coaching helps manage emotional job demands, and its influence on self-efficacy development. Data analysis incorporated multiple sources including interviews, organizational documents, and Principal Self-Efficacy Scale responses, revealing four major themes that demonstrated coaching's multifaceted impact on Black male principals' leadership experiences.
Findings revealed that Black male principals experienced two fundamentally different developmental structures: true executive coaching that operated as inquiry-based, empowerment- focused support versus school-based supervision using coaching techniques while remaining compliance-focused. This distinction addressed widespread role conflation where coaching, mentoring, and supervision terms were conflated. Executive coaching served as a transformational intervention. Through The Fellowship's 5-Square Emotional Intelligence Framework, executive coaching provided systematic identity-affirming support that enabled participants to navigate racialized leadership challenges, process cultural taxation, and develop authentic leadership approaches while building self-efficacy across management, instructional leadership, and moral leadership domains.
The study's theoretical contributions include a proposed Developmental Structure Framework that organizes support along technical-to-adaptive and management-to-leadership dimensions, extending existing coaching theory to emphasize culturally responsive practices as potentially essential rather than optional for Black male principals. The research repositions executive coaching from optional professional development to critical infrastructure for supporting leaders from marginalized backgrounds, with findings suggesting that race-conscious, identity-affirming coaching addresses fundamental needs that other support structures fail to meet. The study extends the Job Demands-Resources Model by positioning coaching as both an emotional resource and sanctuary that provides therapeutic support within a professional development framework. Implications for practice, policy, and research emphasize the need for coach preparation programs to integrate racial literacy, organizations to create clear role boundaries between support types, and policy makers to recognize executive coaching as an evidence-based strategy for principal effectiveness and retention
Mediterranean Drying by a Positive North Atlantic Oscillation Trend over the Last 65 Years Is an Extreme Outlier in the CMIP6 Multimodel Ensemble
No full textThe Mediterranean region has experienced declining precipitation during the cool season since the 1950s, which is broadly consistent with climate model future projections. The observed drying is focused on midwinter and the central to western Mediterranean. Observed winter drying in the western Mediterranean is at the very edge of the CMIP6 ensemble range of historical simulations for the same time period and, in the central to eastern Mediterranean, is in the lowest percentiles of model ensemble distributions. Moisture budget analysis shows the drying to be dynamic, driven by changes in circulation, rather than thermodynamically related to changes in humidity. An observed positive trend in the North Atlantic Oscillation drives the drying by placing subsiding air over the Mediterranean augmented by dry northerly advection. The more modest radiatively forced drying in the CMIP6 multimodel ensemble is also dynamic but related to a high pressure anomaly over the eastern North Atlantic with a different pattern to the North Atlantic Oscillation. A small number of individual runs of some CMIP6 models do show trends in Mediterranean drying, the North Atlantic Oscillation, and moisture budget similar to that observed. However, the observed Mediterranean drying and North Atlantic Oscillation trends are at the very limit of what climate model simulations can do from the combination of variability and forced response over this time period. The observed drying is either (i) an extremely rare manifestation of natural multidecadal variability akin to that in models, (ii) a result of variability not captured in models, or (iii) a forced response that models are missing
GRID3 COD - Roads v1.0
No full textThe GRID3 COD - Roads v1.0 spatial dataset consists of road and path locations in the Democratic Republic of the Congo.
Keywords: Road
New Understanding of Climate Change and Food Systems since the IPCC Sixth Assessment Report: Global and Regional Impacts, Solutions, Structural Trends, and Research Directions
No full textWe survey advances contributed by peer-reviewed studies since the IPCC AR6 food system chapter. The focus is on recent (2020-present) assessments of climate change impacts both on global food systems and vulnerable agricultural regions, as well as promising actions for both mitigation and adaptation (Fig. 1). It includes a review of the ongoing structural changes in food production and processing and a description of how Shared Socioeconomic Pathways (SSPs), Representative Agricultural Pathways (RAPs), and AgMIP model ensembles are being used to study them. A new Global Adaptation Pathways effort is getting underway that will provide key tools for implementation. Finally, we identify important emerging areas for research
Wastewater Reuse Experiments in Algiers
No full textAlgiers faces severe water scarcity, driving the development of treated wastewater as a non-conventional resource. Algeria’s Wastewater Reuse (WWR) strategy promotes safe reuse for agriculture, municipal, and industrial purposes, supported by pilot projects, treatment upgrades, and energy recovery initiatives. While technical and economic challenges remain, coordinated governance and infrastructure investments make WWR a key component of sustainable urban water management
Plateau Environmental Protection and Sanitation Agency (PEPSA) in Jos, Nigeria
No full textRapid urbanization and population growth in Jos, Nigeria, have intensified solid waste management challenges, stressing existing infrastructure and contributing to environmental degradation. The Plateau Environmental Protection and Sanitation Agency (PEPSA) has implemented programs for waste collection, treatment, recycling, and public awareness, while promoting climate-adaptive practices. Adopting circular economy principles, enhancing infrastructure, and fostering multi-stakeholder collaboration are essential to improve sustainability, resource recovery, and climate resilience in Jos
Measurements of the Perpendicular Correlation Length of Coronal Alfvénic Waves with DKIST
No full textWe have measured the perpendicular correlation length L⊥ of Alfvénic waves in the corona using data from the Daniel K. Inouye Solar Telescope (DKIST) Cryogenic Near Infrared Spectropolarimeter (Cryo-NIRSP) instrument. These data have high spatial resolution and were collected using a raster, enabling us to unambiguously identify the parallel and perpendicular directions with respect to the wave propagation. We find that the measured median L⊥ ≈ 3.5 Mm, which is about half the value found by previous measurements. We ascribe the smaller value measured here to the improved spatial resolution of DKIST. There is a gradual decrease of L⊥ as a function of frequency. We also computed the spatial correlation length of the observed static density structures and found that their typical correlation lengths of ≈8.4 Mm were significantly larger than those of the waves
The Mechanisms of Instrumental Expansion: Musical Instruments and Their Gravitational Fields
No full textWhile most orchestral instruments reached their final design in the 19th century, the expansion and redesign of traditional instruments have become increasingly common in experimental contemporary music. This dissertation explores the deep interconnections and reciprocal relationships between musical instruments, their historical, conceptual and technical frameworks, and the contemporary practice of instrumental expansion. It argues that musical instruments are both socially and historically saturated objects, deeply enmeshed in genealogical traditions that continue to influence their roles and possibilities. As a result, they function as aesthetically regulative devices.
Through a critical analysis of instrumental expansion and the examination of two key works representing different philosophies of expansion, this paper seeks to problematize the implicit restraints inherent to musical instruments and magnify the moment of instrumental expansion, shedding light on the inner workings of this process.
The dissertation is structured into four chapters, with each of the first three posing a fundamental question concerning instrumental expansion. The first chapter, "Why Expand?" draws from Deleuze, Guattari, and Foucault to contextualize musical instruments as territorial entities that demarcate and regulate a technical as well as conceptual field, rendering latent aesthetic values. These values, I argue, are perpetuated by the interaction between performer and instrument, which is codified according to pre-existing aesthetic standpoints.
The second chapter, 'What is Expanded?', traces examples from the historical evolution of instrumental ideals, which, I argue, conflate the technical domain with changing notions of beauty. The third chapter, "How to Expand?" presents two contrasting case studies, representing different philosophies of expansion: Mauro Lanza and Andrea Valle’s Systema Naturae, and Lisa Streich’s Pietà. Rather than providing an exhaustive analysis of each piece, this chapter focuses on specific moments to explore their poetic and technical approaches to instrumental expansion.
The fourth and final chapter offers a macro perspective, reflecting on history’s unrelenting grip on the present and its connection to the current stagnated cultural, social, and political moment. The dissertation concludes with a brief contextualization of three of my own works, Bricolage, Inquiline, and Relics of Movement, which are inextricably linked to the themes explored in this paper