As the momentum of climate action continues to shift from top-down, nation-state action to decentralized action by corporations, cities, and utilities, these actors are working to decarbonize their energy consumption and help drive the transition to a carbon-free grid. However, the current frameworks and metrics that drive voluntary decision making—GHG inventories and renewable energy procurement goals—do not always reflect the reality of the evolving power system, and thus can lead to decisions that do not effectively reduce emissions or address grid needs. This research seeks to fill the gaps in knowledge about how both regulatory and voluntary approaches to decarbonizing the electric grid can maximize their effectiveness and accurately measure and attribute emissions from electricity consumption. This dissertation draws upon power system engineering and industrial ecology research and applies data science and optimization methods to 1) identify whether there is a need to account for grid carbon emissions on an hourly basis, 2) introduce a comprehensive dataset of validated hourly emissions from the U.S. power sector, and 3) introduce a new modeling tool that enables greater understanding of the role of different voluntary clean energy procurement goals in the broader energy transition.

Collectivism, a cultural value which emphasizes interpersonal relationships and group cohesion, is endorsed to a greater degree among Latinx and Asian individuals than non-Latinx White (NLW) individuals and is thought to increase the salience of social context. The relationship between collectivism and social context may account for higher levels of social anxiety reported by Latinx and Asian adolescents. In line with this premise, errors or negative feedback that take place in a social context may be viewed by those with a collectivistic worldview to have greater consequences than to those with an individualistic perspective. Exaggerated error monitoring and response to negative feedback already have been implicated in models of social anxiety. The goal of this study is to determine the extent to which adolescents’ endorsement of collectivism interact with neural manifestations of error-monitoring (i.e., error-related negativity (ERN)) and feedback response (i.e., feedback-related negativity (FRN)) occurring in a social context, and the magnitude of the association of these event-related brain components with dimensional ratings of social anxiety. A community sample of Latinx, NLW, and Asian adolescents (n=102) was recruited for this study. Participants completed three complementary computerized speeded-response and feedback response tasks designed to elicit the ERN and FRN, as well as a battery of self-report questionnaires assessing demographic, cultural, and psychopathology constructs. Results from regression models supported the hypothesis that collectivism increases the salience of social context for adolescents, which is reflected in enhanced neural response to errors. Further, both ERN and FRN were found to be related to a dimensional measure of social anxiety. These relationships appear to be contingent on certain factors, namely, how social context is represented and the valence of social feedback. This project also found racial/ethnic group to be a moderator of identified associations. Although findings from this study are limited by methodological and conceptual issues, results could be used to inform future translation efforts of psychophysiological insights into treatment innovations.

The period following a first episode of schizophrenia (SZ) is considered a critical window for treating cognitive impairment, and cognitive training (CT) interventions have shown promising efficacy. Cognitive impairment in SZ is associated with widespread alterations in functional neural network connectivity. However, research has not identified consistent associations between specific connectivity measures and individual domains of cognitive impairment. Furthermore, few studies have examined whether CT works by promoting normalization of neural networks (i.e., reduction of pre-existing disturbances) and/or by fostering compensatory network processes. In the present studies, we used graph-theory connectivity analysis to evaluate properties of intrinsic functional network organization and their relationship to cognitive function in first-episode SZ before and after CT. Using resting-state fMRI data from 45 young adults with SZ and 32 healthy comparison participants (HC), we tested for group differences in graph properties of the ‘task-positive’ cingulo-opercular (CON) and frontoparietal (FPN) networks and the whole-brain network, as well as their relationship with global and domain-specific measures of cognitive function prior to CT. SZ and HC did not differ substantially on measures of network organization, and across groups, generalized cognitive performance was positively associated with centrality of a node in right dorsal anterior cingulate cortex (dACC). Cognitive function in SZ was more positively associated with whole-brain functional segregation than in HC. In SZ, cognitive performance appeared to be decoupled from bilateral dACC node centrality, though effects were non-significant after correcting for multiple comparisons. Next, using longitudinal data from 17 SZ who completed a six-month course of CT and 20 HC who received no intervention, we tested for network normalization and compensation following CT. Although effects were non-significant after correcting for multiple comparisons, we found preliminary evidence of compensation in SZ following CT. Centrality of a node in right dACC decreased after CT, and this decrease corresponded with gains in processing speed. Reduced centrality of two other nodes in right dACC following CT was associated with gains in working memory and generalized cognitive performance. Results illuminate a potential role for compensation in cognitive recovery from SZ and may contribute to increased precision of future CT interventions.

This dissertation focuses on nonlinear dynamical systems with net responses. In particular, we discover a steady field induced within liquids by a sinusoidal potential, referred to as Asymmetric Rectified Electric Field (AREF). AREF helps explain several long-standing discrepancies regarding the behavior of particles and electrically induced fluid flows in response to oscillatory potentials, broadly impacts the interpretation of the experiments, and offers new avenues for research in electrokinetics. Additionally, we demonstrate that non-antiperiodic, zero-time-average, excitation of a spatially symmetric system can yield net responses. We consider an object atop a flat surface that undergoes a dual-mode horizontal vibration. Our calculations, and subsequent experimental observations, show that the object experiences a net drift if the applied frequencies are the ratio of odd and even numbers (e.g., 1 Hz and 2 Hz). As a corollary, our theory suggests that swapping the powered (non-antiperiodic potential) and the grounded parallel electrodes of an electrochemical cell alters the system behavior, a prediction verified by our experimental observations on the AREF-induced electrophoresis.

Individuals with depression and anxiety have difficulty inhibiting their response to emotional information. Depression has been related to more attentional bias to negative information as well as less attentional bias to positive information. Anxiety has been associated with more attentional bias to high arousal, negative (or threat-related) stimuli. Independent of depression and anxiety symptoms, stress across the lifespan has also been linked to alterations in emotion inhibition along with increased risk for the development of internalizing psychopathology in adulthood. Three studies were conducted in order to identify behavioral and neural correlates of a novel emotion inhibition task, and evaluate a potential mechanistic pathway linking stress exposure to psychopathology via alterations to emotion inhibition. To better characterize the role that distracting emotional contexts plays in disruption of inhibitory control, the Image-Color-Word Stroop (IMCWS) task was developed. Participants (N=133) completed the IMCWS as well as questionnaires assessing life stress, resilience, depression, and anxiety. EEG data were collected on a subset of participants (N = 72) during completion of the IMCWS task. The inclusion of emotionally valenced, high-arousal scenes resulted in longer reaction times during high-conflict conditions of the superimposed color-word Stroop, indicating that the IMCWS task successfully enhanced the automatic recruitment of emotion processing to be inhibited. Further, the IMCWS was found to alter event-related potential (ERP) components commonly associated with allocation of attention and emotion processing (e.g., N250, P300) and inhibitory control processes (N450), suggesting that emotion inhibition during the IMCWS involved increased early attentional allocation to emotional contexts followed by increased recruitment of inhibitory control mechanisms. Current life stress (CLS) was found to be predictive of anhedonic depression, and both were associated with alterations in emotion inhibition. Whereas CLS was associated with more biased attention and, therefore, reduced emotion inhibition during the presentation of negative-valence context images, anhedonic depression was found to be related to less biased attention (i.e., increased emotion inhibition) during the presentation of positive-valence context images. Emotion inhibition was not found to play a mechanistic role in the pathway from CLS to anhedonic depression. Rather, results suggest distinct, yet complementary impacts of CLS and anhedonic depression on emotion inhibition function. Given the comorbidity of CLS and depression, CLS should be considered in future studies of emotion regulation and cognitive control disruptions in depression.