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Diverse and alternative forms of economies have recently gained increased attention for their potential to transform conceptually and empirically the mainstream economic system. Around the world, scholars have documented the emergence and impact of economic practices that do not necessarily align with the principles and functioning mechanisms of the capitalist system. However, to this date, little is known about the contribution of migrant communities to diverse collaborative economic practices as they increasingly play a significant socio-economic role in the United States. This dissertation research relies on a postructuralist and postcolonial conceptualization of the economy as a diverse, contested, and situated realm to produce nuanced understandings of diverse economic practices developed by migrant communities in the US and to fill in the gaps of current understandings of diverse economies, ethnic economies, and ethnic foodscapes. This exploratory study relies on a relational comparative case study to investigate three dimensions of Latinx food-based collaborative practices (individual, collective, and contextual) in two urban contexts in the US – Boston (MA) and Charlotte (NC). By relying on a mixed-method approach in each context of study, this dissertation demonstrates the existence of multiple, diverse, and intertwined food-based collaborative networks assembled through the enactment of economic practices and informed by values of solidarity, interdependence, and cooperativism rooted in Latinx individuals’ non-static identity, cultural background, and past experiences. It also shows the heterolocal spatial form of food-based collaborative networks in the two contexts of study and the extension of their constitutive relational linkages across non-hierarchical scales. Finally, it demonstrates the mutually constitutive relationships between Latinx food-based diverse economic practices and the contexts in which they emerge, alongside the important transformative power these practices have for individuals, groups, and the context. Through this research I extend ontological economic value to diverse food-based collaborative economic practices and show how these Latinx communities are already diversifying the economy in highly capitalist contexts, such as the United States, and, more importantly, are already assembling the conditions to develop more sustainable economic scenarios.
The electrical grid is a complex network becoming increasingly linked with smart devices and energy sources, such as electric vehicles, appliances, grid support systems, and renewable energy resources. However, the power delivery systems in use today are antiquated and have been in operation for over a hundred years. In this dissertation, several methodologies for optimal management of electric vehicle (EV) fleets connected to the power grid are discussed. First, a hybrid methodology is suggested for determining the quickest way for a vehicle to reach the charging station, taking into account both the distance and the current traffic conditions developed based on graph theory. The strategy is accurate, more efficient, and scalable. Second, a technique that considers the shortest distance to the charging station considering the impact and optimal use of the electric grid is developed. The method takes advantage of distance and simultaneously considers the influence on the grid, such as variations in voltage or power. The procedure is tested and quantitative and qualitative analysis is conducted. Also, with the help of a convex optimization methodology, a speed optimization framework is developed that mitigates range anxiety. Next, an optimization methodology is developed that addresses real-time electric car charging congestion as well as centralized and decentralized charging scheduling of electric vehicles. The charging of plug-in electric vehicles (PEVs) has to be handled through the use of "smart" charging processes to lessen the demand that PEVs have on the electrical grid. These studies examine the impact that the actual implementation of four distinct smart charging architectures has on the electric grid, including a centralized and decentralized design. The capabilities of each method are summarized.
Further, a methodology for demand-side management and distributed load management is developed, considering customer comfort with the help of an electric vehicle fleet. A new mathematical model of household loads such as air conditioners, water heaters, clothes dryers, and dishwashers considering the weather conditions is developed. It was identified that during high temperatures, the system's operational architecture may derive a significant advantage from these massive demand-responsive loads. Further, a robust energy optimization framework is proposed that suggests healthy results to keep the grid stable and sustained after optimizing household loads avoiding customer comfort violation. The proposed methodologies are scalable, field implementable, and have a significant advantage in collectively managing electric vehicle fleets, customer comfort, and energy usage considering road and grid conditions.
National mathematics achievement results show elementary students in the United States are not increasing in cognitive ability or critical thinking skills (NAEP, 2019). Furthermore, students who are mathematically promising need more opportunities for cognitively demanding mathematics instruction in order for this increase to occur. Therefore, this descriptive case study focused on the interactions and emergence of Mathematical Practices in seven third grade students with a series of five tasks. The seven third grade students were identified by their teachers as mathematically promising. The tasks used in the two suburban classrooms observations of the study were from the Tools 4 NC teachers framework (Tools 4 Teachers, 2019). Data sources collected included pre- and post-focus group audiotapes, classroom observations via audio and video, field notes, as well as document analysis of student work and a teacher debrief form. Blumer's theory of social constructivism (1969) and Tripathi’s Multiple Reasoning (2008) guided this study.
Findings from the students' interactions with tasks showed the following themes: students used a variety of interpersonal interactions between themselves, the teacher, and visual representations. Students used mathematical writing to justify their reasoning and reflection to communicate their conceptual mathematical understanding. Students grew in their emergence of the Mathematical Practices of perseverance through problem solving, productive struggle, the construction of arguments, and the ability to make connections. These findings indicate the importance of ongoing curriculum development to include differentiated teacher guidance for mathematically promising students. Additionally, the findings of this study will support mathematics teachers and leaders with a student-centered approach to teaching inquiry-based instruction.
Over the space of three articles, we attempt to answer two broad questions related to public sector voluntary environmental programs (VEP) through a case study on the National Association of Swedish Eco-municipalities (SEKOM). The first question asks what are the municipal factors that influence the decision to participate in the program. The second set of questions has to do with whether participation in SEKOM improves the environmental performance of members.
In article 1, we consider the factors that influence the eco-municipality participation decision and find that even after accounting for spatial dependence; environmental consciousness, municipality type (urban/suburban/rural), the level of education, industry structure, and environmental vulnerability (as proxied by proximity to the coast) are significant determinants of the municipality’s decision to participate in the program.
Article two attempts to determine whether SEKOM improves municipal environmental performance as measured by two environmental policy performance measures: the adoption of environmentally classified vehicles (ECVs) and the implementation of food waste collection policies by Swedish local governments. We make use of a two-stage estimation procedure to account to the self-selection bias that plagues most VEP studies. Our results suggest that SEKOM membership is associated with an increased adoption of ECVs and a higher likelihood of implementing a food waste collection program.
Article three examines the effect of SEKOM membership on the adoption of wind power in Sweden. We make use of a difference-in-difference design with a matched control group. Our results regarding the existence of a positive and significant overall effect are negative. However, we have evidence of the presence of cohort specific effects. Specifically, these suggest that the length of exposure to the program matters for the magnitude and significance of the effect. Eco-municipalities that joined in the earliest cohorts in our sample had the only significant improvement in both the number of wind power projects and the operational installed capacity.
This work presents new protection methods for addressing challenges related to integrating a fully inverter-based generation resource microgrid into the power distribution system. Renewable-energy-sourced microgrids offer promise in providing sustainable energy solutions to meet energy needs. Most of the widely used renewable resources and energy storage systems are interfaced with the power grid through power electronic devices, such as inverters. Diverse expertise is required for the design, construction, and operation of an inverter-based microgrid (IBMG). First, this dissertation provides a comprehensive overview of IBMG characteristics and highlights key obstacles in the design of these systems. The difference between the response of inverter-based resources and synchronous machine-based resources and the dependency of inverter response on its control modes are discussed. Second, a method for distribution system short circuit study considering inverter-based distributed generation is designed. Third, an Electromagnetic Transient (EMT) based inverter modeling for grid following and grid forming mode for both balanced and unbalanced distribution systems is proposed. Fourth, a method is proposed for controlling transient overvoltage in a microgrid-integrated power distribution system. Finally, a new protection method for detecting faults in an IBMG system helps to address the well-known issue of microgrid protection sensitivity and selectivity. The effectiveness of the overall framework is tested with small test systems and large IEEE test systems with relevant data sets. The studies show that the proposed approaches can improve the IBMG system design and increase the reliability of such systems.
Clinical supervision is the primary method to educate and train professional counselors (Baltrinic & Wachter Morris, 2020). While clinical supervision tends to be positive and constructive, harmful clinical supervision occurs. As defined by Ellis et al. (2014a), harmful clinical supervision includes any inappropriate action or inaction by the supervisor that causes psychological, emotional, or physical harm or trauma to the supervisee. Research on harmful clinical supervision is growing (Cook & Ellis, 2021; Ellis et al., 2014a, 2015), but the focus remains on how counselors are traumatized by these experiences (Ellis et al., 2017; McNamara et al., 2017). This qualitative study takes a novel approach using the lens of Tedeschi and Calhoun’s (1996) theory of posttraumatic growth to explore the positive effects of harmful clinical supervision. A sample of 12 licensed counselors completed semi-structured interviews to share their experiences. Five main themes emerged through data analysis: Confusion, Support and Encouragement, Safety and Protection, Financial Security, and Professional Duty. These findings align with the five growth categories described by Tedeschi and Calhoun, but an additional category, Professional Duty, was also identified. This study answers the research questions by providing insight into the context and process of counselor posttraumatic growth. Implications for the profession, study limitations, and suggestions for future research are discussed.
Clinical care guidelines optimize patient care, including Enhanced Recovery after Surgery (ERAS) guidelines specific to surgery. However despite their efficacy, compliance to guidelines by providers remains a challenge. Understanding ways to predict, and thus prevent, non-compliance can aid in improving uptake by providers and post-surgical recovery for patients.
Four approaches were taken to understand the issue. A novel method coined Vertical Compliance for measuring ERAS compliance in real-time can predict and prevent adverse surgical outcomes before they occur. Next, a multi-institutional, multi-surgical specialty retrospective data analysis revealed specific ERAS recommendations that - if not performed - predict adverse patient outcomes such as increased length of stay (LOS) and clinically-relevant complications. To understand the barriers to compliance, a meta-analysis was conducted for all medical literature and regression models developed to understand which barriers predict non-compliance to guidelines. Finally, to understand barriers to compliance specific to surgery and ERAS, a survey was developed and analyzed using a mixed-methods approach to understand which barriers to compliance predict reduces feelings of compliance assurance amongst ERAS professionals.
While conceptually different, vertical compliance and multi-institutional data analysis revealed similarities in which specific recommendations predict adverse outcomes, including oral carbohydrate loading, early removal of Foley catheter, and limited use of nasogastric tubes affected LOS. The two studies examining barriers to compliance revealed lack of familiarity and acceptance, and presence of external barriers were drivers of non-compliance.
Taken both individually and collectively, these four studies reveal why predicting adverse surgical outcomes due to non-compliance to evidence-based care is important, yet, predicting barriers may prove a critical element to preventing that non-compliance before it occurs.
Compositional data refers to any data that represents parts of a whole, and DNA sequencing data is compositional in nature. This is due to the constraint on our current sequencing technologies that allow us to record a sample of the sequences rather than recording all the sequences. This means that sequencing data breaks the assumption of independence (Gloor et al., 2017). It has been long known that analysis of compositional data is challenging and can lead to spurious correlations. However, DNA sequencing data is inherently noisy due to both limitations of sequencing technology and its biological nature. Read depth, the number of sequencing reads from each sample, is known to be a confounding factor in many studies also plays a role in creating artifacts in this type of data. In this work, we demonstrate that read depth drives variance in four different datasets and propose a method for quantifying artifacts generated by read depth. We use this new method to compare untransformed data, several compositionally aware transformations, and a transformation which we call “lognorm” that normalizes samples by read depth in log space. Ultimately, we find that lognorm consistently had less read depth artifacts than the other transformations.
One way to determine the value of a data transformation is to show that it improves the performance of a machine learning classifier. We compared several common transformations to see if they improve the accuracy of a random forest and found that lognorm consistently significantly improves the accuracy of random forest. We believe that lognorm improves accuracy by reducing read depth artifacts and allows the MLA to learn from smaller signals within the data.
Continuous scaling of complementary metal-oxide-semiconductor (CMOS) transistor technology over the past few decades following Moore’s law has led to significant enhancement in the speed and performance of computing architectures. In today’s world with high demand in data processing, CMOS scaling is focusing more on low power, cost-effective processes, and high performance to meet the requirements of high-end computations. To meet the high computation demands, reengineered, high performance, and low power device structures were necessary, and hence field effect transistors (FET) structures have evolved from planner to multi-gate, and gate all around (GAA) structures. Also, other than the very well matured silicon electronics, advanced technologies allowing heterogeneous integration of different materials systems (e.g., Si, Ge, III–V, and II-VI groups) have been developed. Though heterogeneous integration of silicon electronics with compound semiconductors can be beneficial, such developments in hybrid integration cannot address the fundamental limitations of the pure CMOS circuits, the resistive capacitive (RC) delay associated with metallic wires, and the dielectric gate delay associated with FETs. These delays ultimately limit the data speed and energy consumption.
In this research work we have explored novel applications in electronic-photonic integrated circuits of a special type of metal-semiconductor-metal (MSM) photoconductive structure known as the light effect transistor (LET) which can emulate the current voltage characteristics of a FET but with much better performances in terms of switching speed (considering carrier transit delay), energy consumption per switch and Ion/Ioff ratio, and also other optoelectronic functions like optical iv
logic gates, optical summation, optical amplification, and optoelectronic analog operation using LETs, which cannot be done using FETs. The LET can provide extremely fast optoelectronic switching (of the order of ~ ps), and its simplistic structure does-not add unwanted parasitic and leakages which are common in all gated FETs.
To understand the superiority of LETs over FETs, particularly the potential vast performance improvement in a hybrid integrated circuit of the two types of devices, we have explored the possibilities of LETs to replace some FETs in various pure electronic circuits. Using analytical relations and simulations, we have extensively studied the effect of replacing the access FETs in a 6T SRAM (six transistor static random-access memory) structure with LETs and have made some drastic changes in the hybrid 6T FET - LET structure by replacing the whole electrical word line with an optical waveguide (OWG). We have also proposed a prototype novel hybrid 3D integration scheme for the 6T SRAM architecture where all the typical electronic and optoelectronic components (4T FET latch, access LETs, bit lines, peripherals, etc.) will be placed on a single electronic layer while photonic components (OWGs, on-chip lasers to drive the OWGs, etc.) will be placed separately on the photonic layer with regularly spaced openings that provide the optical signal for switching four LETs grouped together from two adjacent hybrid 6T cells in the electronic layer. Also a fully functional FET - LET hybrid SRAM bit cell with superior performance has been designed and implemented using the mixed-mode design environment of Synopsys Sentaurus TCAD.
Continuous scaling of complementary metal-oxide-semiconductor (CMOS) transistor technology over the past few decades following Moore’s law has led to significant enhancement in the speed and performance of computing architectures. In today’s world with high demand in data processing, the CMOS scaling is focusing more on low power, cost-effective processes, and high performance to meet the requirements of high-end computations. To meet the high computation demands, reengineered, high performance, and low power device structures were necessary, and hence field effect transistors (FET) structures have evolved from planner to multi-gate, and gate all around (GAA) structures. Also, other than the very well matured silicon electronics, advanced technologies allowing heterogeneous integration of different materials systems (e.g., Si, Ge, III–V, and II-VI groups) have been developed. Though heterogeneous integration of silicon electronics with compound semiconductors can be beneficial, such developments in hybrid integration cannot address the fundamental limitations of the pure CMOS circuits, the resistive capacitive (RC) delay associated with metallic wires, and the dielectric gate delay associated with FETs. These delays ultimately limit the data speed and energy consumption.
The shift of paradigm in computer architecture that enables significant parallelism based on a radically new communication landscape will be a remarkable breakthrough. Converging electronic and photonic integrated circuits on a single chip platform to enable functional diversification emerges as one promising approach which could be realized by taking the advantage of potential low energy and huge data capacity of optical interconnects. It has been well established that monolithic integration of electronic and photonic elements on the same chip can bring about a huge change in the process of computation though the use of photons. Due to the advanced fabrication technologies, it is now possible to integrate a large number of electronic and photonic components on a single chip to perform logic, memory, and analog functions. However, in these applications, typically the photonic components only play the roles of optical interconnect between different electronic subsystems, for instance, in a photonic dynamic random-access memory (DRAM), rather than any active roles in computation, processing, or modifying data like other analog and digital circuits.
In this research work we have explored novel applications in electronic-photonic integrated circuits of a special type of metal-semiconductor-metal (MSM) photoconductive structure known as the light effect transistor (LET) which can emulate the current voltage characteristics of a FET but with much better performances in terms of switching speed (considering carrier transit delay), energy consumption per switch and Ion/Ioff ratio, and also other optoelectronic functions like optical logic gates, optical summation, optical amplification, and optoelectronic analog operation using LETs, which cannot be done using FETs. The LET can provide extremely fast optoelectronic switching (of the order of ~ ps), and its simplistic structure does-not add unwanted parasitic and leakages which are common in all gated FETs.
To understand the superiority of LETs over FETs, particularly the potential vast performance improvement in a hybrid integrated circuit of the two types of devices, we have explored the possibilities of LETs to replace some FETs in various pure electronic circuits. Using analytical relations and simulations, we have extensively studied the effect of replacing the access FETs in a 6T SRAM (six transistor static random-access memory) structure with LETs and have made some drastic changes in the hybrid 6T FET - LET structure by replacing the whole electrical word line with an optical waveguide (OWG). We have also proposed a prototype novel hybrid 3D integration scheme for the 6T SRAM architecture where all the typical electronic and optoelectronic components (4T FET latch, access LETs, bit lines, peripherals, etc.) will be placed on a single electronic layer while photonic components (OWGs, on-chip lasers to drive the OWGs, etc.) will be placed separately on the photonic layer with regularly spaced openings that provide optical signal for switching the LETs in the electronic layer. To increase the illumination efficiency, allowing for adequate spacing, and reduce the loss due to each OWG opening, LETs from two adjacent 6T cells are grouped together and illuminated simultaneously from a single OWG opening.
The OWG structure with a large number of periodic openings for the hybrid array has been designed and simulated and optimized using the Synopsys RSoft optical design suite and the fully functional 6T hybrid SRAM bit cell with its superior performance has been designed and implemented using the mixed mode design environment of Synopsys Sentaurus TCAD.
