Predictive Factors to Explain the Export of Hazardous Waste by Parties to the Basel Convention

The number of legal and illegal transboundary shipments of hazardous waste has been increasing in the past decade. The mismanagement of some of these shipments has resulted in illness and death, along with widespread environmental contamination. Despite efforts of the Basel Convention, a treaty that limits the transboundary shipment of waste, to reduce these shipments through mandating the treatment and disposal of any wastes as close as possible to the point of generation, recent national export data indicates that over 80% of all reporting parties to the Basel Convention export part or all of their hazardous waste. The amount of hazardous waste involved in a transboundary movement increased 22% between 2004 and 2006. This study examines select social (level of human development), economic (trade extent, structure, and openness), political (level of democracy and tolerance to civil society), and technological (technology development support) factors that may drive a country to export its waste rather than manage it within xiii its national borders. This issue is examined at the national level because it is the responsibility of the national government to grant permission for these shipments to proceed. Self-reported national data is often incomplete, so missing values analysis was conducted and multiple imputation was performed on the research dataset. Multivariate linear regression was then conducted on each of the five imputed datasets, and the results were pooled. The results of this analysis indicate that technology development support, as determined by a proxy variable consisting of a country’s gross expenditure on research and development in relation to its gross domestic product is a significant predictor of hazardous waste export and that, as technology development increases, hazardous waste exports decrease. The development of in-country waste minimization and waste treatment/disposal technologies may be one explanation for this result. Additional exploratory analyses indicate that the broadness of the trade structure, related to trade diversity, and the level of democracy are predictors of a country’s propensity to export waste, when the technology development support variable is removed from the regression analysis. National-level policy options to address these results may include the encouragement of increased support of research and development, especially in the area of environmentally sound waste management technologies. Also examined are the more immediate needs of the government officials who are responsible for these transboundary shipments. Collective action theory provides the framework through which interactions relating to these shipments will be examined at the national, regional, and international levels

Cell Assembly Formation and Retrieval in a Biologically Constrained CA3 Network

When we reminisce about our past, the evoked memory typically consists of specifics including where and when an event occurred, what happened, and how we felt about it. Our brain remembers these multi-faceted experiences by co-activating groups of neurons, so-called cell assemblies. A leading neuroscience theory posits that hippocampal area Cornu Ammonis 3 (CA3) binds together details to form an episodic memory via auto-association (cell assembly formation), and the memory is later recalled through pattern completion (cell assembly retrieval). However, the exact mechanisms of how circuits of diverse neurons communicating via spikes and complex synaptic signals implement these processes are still unknown. To address this open problem, I created a full-scale spiking neural network (SNN) simulation of the mouse CA3 that integrated data-driven properties from the Hippocampome.org open-access knowledge base. I first simulated the SNN without prolonged stimulation to investigate the network dynamics before memory storage. The resultant network activity was stable and rhythmic in the beta band (12-30 Hz), consistent with empirical evidence when awake mice are not performing a memory task. Building on this work, I demonstrated the SNN was capable of robust auto-association and pattern completion via cell assemblies. The assemblies could successfully and systematically retrieve patterns from heavily incomplete or corrupted cue presentations. A broad range of assembly sizes, consistent with theory and experiments in rodents and humans, supported strong auto-association and pattern completion. The CA3 SNN performance was robust with respect to partial overlap of assemblies through shared cells, substantially enhancing memory capacity. These results provided computational evidence that the specific biological properties of the CA3 circuit produce an effective neural substrate for associative learning in the mammalian brain. Furthermore, previous studies highlighted the importance of acetylcholine as a neuromodulator in memory formation and retrieval. Therefore, I assessed the dynamics of acetylcholine in the medial septum, the major source of cholinergic modulation for the hippocampal formation, in mice foraging for food in an open environment. Machine learning classification of the movement of mice revealed four distinct behaviors of exploratory running and walking, grooming, and rearing. Linear regression further demonstrated an increase of cholinergic activity in the MS during rearing, when a mouse scans its surroundings on its hindlimbs from an elevated perspective, suggesting a role in encoding information for spatial memories. Taken together, the results of this thesis demonstrate the capability of a biologically realistic SNN of the mouse CA3 to encode and retrieve memories, as well as the utility of deep learning in uncovering correlations between neuromodulation and behavior. These advances afford the community complementary and synergistic opportunities to better understand episodic memory in future studies

EPA's Radioactive Source Program

This presentation discusses the U.S. Environmental Protection Agency's (EPA) Radioactive Source Program

The colonial legacy in Cambridge Assessment literature syllabi

This study analyzes the literature syllabi of Cambridge Assessment International Education (CAIE), a highly influential international education organization that determines curricula and conducts examinations for nearly one million students annually. Although CAIE describes its syllabi as internationalized and free from cultural bias and discrimination, little research has been conducted to confirm or reject these claims. Using a framework of postcolonial feminism and postdevelopment theory, this study analyzes author representation in CAIE literature syllabi to reveal potential colonial and patriarchal dimensions. We analyze the six CAIE literature syllabi in terms of author nationality, world region, and gender. The results indicate a clear bias in favor of European male authors and a consistent underrepresentation of women authors from the Global South. Authors of the MENA region are entirely excluded from the syllabi. Women authors from Latin America are also almost entirely absent. The study concludes that CAIE literature syllabi are not sufficiently international or multicultural, but instead reflects the continued legacy of colonial relations between British education and the Global South. Since the colonial era, CAIE has continued to enact banking education at a global scale by conceiving of the Global South as lacking in literature worthy of study. In order to begin to decolonize their literature syllabi, we suggest that CAIE should draw from diverse literature throughout World Englishes, especially literature written by women authors in the Global South

Formation and Retrieval of Cell Assemblies in a Biologically Realistic Spiking Neural Network Model of Area CA3 in the Mouse Hippocampus

<p>Dataset accompanying the manuscript "Formation and Retrieval of Cell Assemblies in a Biologically Realistic Spiking Neural Network Model of Area CA3 in the Mouse Hippocampus". This dataset is used to re-create all figure panels with underlying data in the manuscript.</p&gt

Temporal dynamics of cholinergic activity in the septo-hippocampal system

ABSTRACTCholinergic projection neurons in the medial septum and diagonal band of Broca are the major source of cholinergic modulation of hippocampal circuit functions that support neural coding of location and running speed. Changes in cholinergic modulation are known to correlate with changes in brain states, cognitive functions, and behavior. However, whether cholinergic modulation can change fast enough to serve as a potential speed signal in hippocampal and parahippocampal cortices and whether the temporal dynamics in such a signal depend on the presence of visual cues remain unknown. In this study, we use a fiber-photometric approach to quantify the temporal dynamics of cholinergic activity in freely moving mice as a function of the animal’s running speed and visual cues. We show that the population activity of cholinergic neurons in the medial septum and diagonal band of Broca changes fast enough to be aligned well with changes in the animal’s running speed and is strongly and linearly correlated to the logarithm of the animal’s running speed. Intriguingly, the cholinergic modulation remains strongly and linearly correlated to the speed of the animal’s neck movements during periods of stationary activity. Furthermore, we show that cholinergic modulation is unaltered during darkness. Lastly, we identify rearing, a discrete behavior where the mouse stands on its hindlimbs to scan the environment from an elevated perspective, is associated with higher cholinergic activity than expected from neck movements on the horizontal plane alone. Taken together, these data show that temporal dynamics in the cholinergic modulation of hippocampal circuits are fast enough to provide a potential running speed signal in real-time. Moreover, the data show that cholinergic modulation is primarily a function of the logarithm of the animal’s movement speed, both during locomotion and during stationary activity, with no significant interaction with visual inputs. These data advance our understanding of temporal dynamics in cholinergic modulation of hippocampal circuits and their functions in the context of neural coding of location and running speed.</jats:p