Methods for matrix completion

In this paper, we are going to provide major results for two sorts of Matrix Completion problems. One involves the recovery of a low rank matrix and the other involves the recovery of an approximately low rank matrix based on a small number of observed entries. In the end of the paper, we are going to demonstrate the feasibility of the recovery methods discussed on randomly generated low rank and approximately low rank matrices.Computer Scienc

Development of a new laser doppler vibrometer-based non-contact damage detection system for cracks in rail head

Rail defects are one of the dominant causes of train derailments and an essential factor affecting transportation safety. Among the rail defects, transverse defects (TDs), which are cracks located transversely in rail heads, are one of the main causes of derailments. When TDs are left undetected, their size expands, leading to rail breaks. Therefore, the railway transportation community is interested in the detection of such defects at speeds that do not obstruct the routine railroad operation. The goal of this research is to develop a novel LDV-based noncontact damage detection system for TDs. The tasks performed herein to achieve this goal (i.e., the objective of the study) were: (i) extensive literature review and in-situ testing to understand the vibrations resulting from the propagating waves in rail, (ii) numerical modeling of the damage detection system, (iii) rigorous laboratory and in-situ testing to understand the noise in LDV measurements as well as to evaluate the performance of the damage detection system, and (iv) analytical work to develop filters to minimize the noise in the LDV measurements. Accordingly, the configuration of the developed damage detection consists of two LDVs attached vertically in front of a rail car to measure guided waves in the rail head, which are induced by rail-wheel interaction. This system uses the LDV measurements to detect a change in the relative amplitudes of the recorded waves caused by a defect in the frequency range between 30 kHz to 100 kHz. The lower cut-off frequency was selected conservatively since it was shown in the literature that guided waves start to localize in the rail head after approximately 15 kHz. The higher cut-off frequency was selected since (i) the guided waves below 100 kHz can be used for transverse defect detection (as the frequency exceeds 100 kHz, waves are susceptible to surface defects), and (ii) the measurements collected from rail during the passage of operating trains showed that the power of the excitations induced by wheel-rail interactions is dominant up to approximately 100 kHz. The main challenge during the development of the system was speckle noise, which is inevitable due to the inherent nature of the measurements performed by LDVs placed on a moving platform. Consequently, the damage detection framework associated with the system operates as follows: 1) in the pre-processing stage, time-varying mean and impulsive noise in the recorded LDV signals are filtered and then the changes in the LDV signals in the frequency range of interest are quantified and monitored using moving standard deviation, 2) in the post-processing stage, two damage features, which are based on the relative change in the moving standard deviations and transfer functions between two measurement points are combined using multivariate statistical analysis to create a damage index that shows the location of rail segments which are affected by a defect. The goal of impulsive noise filtering and transfer functions in the framework is to minimize the speckle noise. The field tests demonstrated that rail segments consisting of a defect can be identified by the developed system.Civil, Architectural, and Environmental Engineerin

Factors associated with food delivery app use in young adults

Food delivery apps are highly popular among young adults and are often used to purchase calorie-dense foods, which are associated with a variety of health issues such as increased risk for obesity. Limited research exists on the use of food delivery apps and the research that has been conducted, focused on adults, suggests that food delivery app use differs by sociodemographic factors. Thus, the purpose of this study is 1) to describe food delivery app use among young adults, and 2) to examine the association between young adult food delivery app use and factors including age, race, ethnicity, sex, SES, food insecurity, living arrangement, financial responsibility, and full-time student status. Data are from the Promoting Young Adult Health Survey, a cross-sectional online survey with 1,038 young adults online from the Qualtrics panel January-February 2022. Poisson regression was used to examine the relationship between food delivery app use and the sociodemographic variables. Our results suggest that participants who reported being non-Hispanic Black and Hispanic had greater food delivery app use frequency as compared to participants who reported being white. Having higher perceived subjective social status, being food insecure, being financially responsible, and being a full-time student were all significantly associated with greater food delivery app use frequency. Living with someone else was significantly associated with lower food delivery app use frequency. Age, sex, and ‘Other’ Race/ethnicity were not associated with food delivery app use frequency. Overall, young adults use food delivery apps approximately twice a week with vulnerable groups such as Black and Hispanic young adults and young adults reporting food insecurity having greater frequency of use. This study provides a first step in understanding the characteristics of young adults who use food delivery apps more frequently. Given that this new technology can both increase access to unhealthy food options as well as healthy food options, future research is needed to better understand the types of food purchased through food delivery apps and the differences by the sociodemographic factors explored in this study.Kinesiology and Health Educatio

Under the aegis of the Archangel : fascism and divine kingship in interwar Romania

This report aims to take a decisive first step towards an analysis of fascism as a resuscitated form of that archaic political figuration known to religious studies scholars as divine kingship. I take this aspirational first step through a case study of The Legion of the Archangel Michael and Corneliu Zelea Codreanu, Romania’s interwar fascist movement and its founder. The report first situates itself within the ‘new consensus’ of fascist studies as represented by the theories of Roger Griffin and Emilio Gentile before delving into a history of the Legion of the Archangel Michael and C.Z. Codreanu. With this historical data in hand, I turn to an exegesis and application of some key theories on divine kingship from Ernst Kantorowicz’s The King’s Two Bodies (1957) and David Graeber & Marshall Sahlins’ On Kings (2017) to the Legion. What emerges is a distinct vision of the necessarily modern political phenomenon of fascism as in fact a kind of reboot of divine kingship for an era of mass, electoral politics.Religious Studie

“The City Residents Do Not Get Involved”: Understanding Barriers to Community Participation in a Small Texas Boomtown

Background: Professional communication researchers have engaged communities through community research and interventions, such as town halls, charettes, and participatory design work. Such interventions rely on community members who are willing to get involved, voicing their perspectives, and engaging in productive dialogue. Yet, some communities do not have these precursor conditions for intervention: they face significant social barriers that make such interventions unlikely to succeed. In an interview- and document-based study, we examine the social barriers described by interviewees in “Permia,” a small town in the Texas Permian Basin region. In contrast to the five other communities we studied, Permia participants demonstrate little readiness to engage in community dialogue. We explore how Permia interviewees made sense of unwillingness to participate in its public life, how their understandings contrasted with the other communities we investigated, and how this research might guide professional communicators as they plan future community-based interventions. Literature review: We review the professional communication research on community interventions as well as relevant sociological literature on boomtowns. Research questions: 1. How do community leaders understand their community heritage as constraining or enabling development? 2. Where do community leaders and members see potential for change and growth in community development? Where do they see barriers, threats, and hard choices? 3. How do community leaders describe the relations among community development stakeholders? How do they describe expectations and trust among them on interpersonal, intergroup, and interorganizational levels? Research methodology: We collected documents and statistics about six small Texas towns, then interviewed community leaders about the towns’ advantages and challenges. Based on those interviews, we collected further documents. We analyzed the data using deductive and inductive coding, as well as narrative analysis. Results/discussion: Through coding, we determined that interviewees saw Permia’s residents as unwilling to engage in deliberations in traditional forums such as city council meetings, and that their explanations for this unwillingness fell into three categories of barriers: distrust of institutions, dwindling personal ties, and lack of moral expectations for residents to engage in community dialogue. These three categories contrast with the other communities we studied. Through narrative analysis, we identify stories that were told by the interviewees to explain how these barriers developed in Permia. Conclusion: We conclude by discussing how professional communicators might survey barriers to community dialogue. Such surveys can help professional communicators choose a pathway for intervention in their community projects.IC2 Institut

Physical activity participation, physical fitness, psychosocial characteristics and academic achievement among adolescents

In this dissertation we will examine the effects of physical activity (PA) and physical fitness (PF) on academic achievement (AA), mediated by the psychosocial constructs of grit, self-efficacy (SE) and modality of physical education (PE). Given the known relationship between PF and AA (Castelli, Hillman, Buck & Erwin, 2007) the purpose of study one was to determine how psychosocial characteristics of grit and SE contribute to this relationship. Students completed the Perceptions of Barriers to PA (Motl, 2000) and the Short Grit Scale (Duckworth, Peterson & Mathews, 2007) at the beginning and end of the school year. PF was measured using the FitnessGram® test (Cooper Institute; Dallas, TX.). Results revealed students with higher grit (r [subscript s] = 0.21, P < 0.001) and had less school absences (r [subscript s] = -0.35, P < 0.001) performed better on AA (β = 0.13, P < 0.01and β = -0.35, P < 0.001, respectively). Despite PA’s connection to optimized cognitive functioning, the results among adolescents have been equivocal based on PA sampling technique (Tremblay, Inman, & Williams, 2000; Donnelly et al., 2016). The purpose of study two was to determine if objectively measured PA is related to AA in a low SES school setting and whether the psychosocial characteristics of grit and SE mediate this relationship. Student PA was sampled across four ten-hour periods. Results revealed that PF accounted for 5.8% of the variance in AA suggesting a non-significant relationship among the sample population. In study three a PE alternative (APE) was compared to traditional PE (TPE) examining if modality moderates the relationship of PF, AA, and grit. APE was a running club offered at low SES schools in the district as an option to TPE. Study methods were similar to previous studies, with the added independent variable of PE modality (traditional or APE). Results of MANOVA revealed despite the two populations similarity at onset for PF and grit. There was a 6.5% variance in AA that was accounted for by modality to the benefit of the APE (Pillais’ Trace = .065, F (14,700), p <.01 with η² = .065).Curriculum and Instructio

Switch-mode active EMI filtering

Power converters often require EMI filtering which usually involves bulky passive components. Active EMI filters (AEF) can reduce size but incur heavy losses in their linear amplifiers when designed to filter large ripple currents. This work proposes two different approaches for active EMI filters with a switch-mode amplifier to achieve reduced size and low loss penalty: a high-frequency AEF and a synchronous AEF. The high frequency AEF features a switching amplifier operating at 31 MHz to keep its own EMI out of the regulated EMI range. A fractional-order filtering technique is used to design the feedback compensation loop, achieving a high loop gain and thus high current attenuation of 30 dB from the active circuit at the dc-dc boost fundamental frequency of 150 kHz, while consuming only 1W for an output power of 120 W. The proposed high frequency AEF is compared to a passive LC filter for the same application and is shown to have a volume that is eight times smaller than that of the size-optimized LC filter. The proposed synchronous AEF, in contrast to the high-frequency AEF and other typical AEF circuits, does not use feedback, thereby avoiding the bandwidth and attenuation limitations associated with feedback stability. This AEF also has very low energy storage requirements compared to passive EMI filters and achieves very high efficiency compared to typical AEF circuits with linear amplifiers. Furthermore, it can simplify circuitry by directly utilizing the same gate signals as the main power converter. Additionally, the AEF does not interfere with the closed-loop controller of the main converter, a common challenge in the design of passive EMI filters or feedback-based AEFs. We demonstrated the proposed synchronous AEF through simulations and hardware prototypes for both a boost power factor correction (PFC) and a dc-dc boost converter, operating at different current control modes and switching frequencies. The AEFs achieved high differential-mode current attenuation from 20 dB to 65 dB at different harmonic frequencies and provided significant common-mode current attenuation of over 29 dB by injecting a common-mode current that largely cancels the common-mode current generated by the boost PFC. Additionally, the volumes of the synchronous AEFs are significantly smaller than those of conventional passive LC filters — approximately 1/16 to 1/32 of the size-optimized LC filter. They also have very low power consumption, with a maximum efficiency penalty of less than < 0.7% when filtering high current ripple ratios of up to R = 100% from the boost PFC, in contrast to AEFs based on linear amplifiers. Both AEF proposals present very promising approach to (mostly) replace the conventional LC filter and linear-mode AEFs for smaller volume and high efficiency. At the end of this work, we present the design and implementation of two ultra-fast isolated gate drivers with 2-8 ns propagation delays, one of which will be used to design the gate driver of the high-frequency AEF. This will help improve the compensator bandwidth of the high-frequency AEF, which is limited by propagation delays primarily caused by the bootstrap gate driver and the comparator in the previous design.Electrical and Computer Engineerin

Microdroplet assay development for metabolic engineering and synthetic biology applications

Sustainable, efficient production of societally relevant chemicals in microorganisms is the epicenter of the field of metabolic engineering. Modern developments in DNA synthesis and sequencing have enabled high-information gene perturbation and protein engineering libraries that require reliable, reproducible, high throughput screening assays. Detailed herein are examples of utilizing growth-based assays and microfluidic screening to extract pertinent information from different gene perturbation libraries, microbial consortia, and engineered proteins. The first study details an approach to regulate gene expression in S. cerevisiae through utilization of a single-guide RNA library paired with dCas9 fused to either Mxi1 or VPR. Through these fusions and targets of guide RNAs, genes are either up or down regulated at increasing degrees. Using this library it was possible to identify target genes for moderate up and down regulation to improve growth on alternative carbon sources, namely glycerol and galactose. Final analysis of enriched guides via next generation sequencing identified moderate down regulation of essential genes, novel perturbations that would not have been isolated in traditional gene knock-out approaches. The studies detailed in chapters 3 and 4 delve into technical applications of microfluidics to screen for improved small molecule production. In chapter 2, the library detailed above is utilized to screen for gene targets that improve small molecule production in S. cerevisiae. This study also results in the development of a pico-injection microdroplet approach that utilizes cell-based biosensors to transduce small molecule production into a fluorescent signal. The study in chapter three characterizes this application further, ultimately leading identifying gene perturbations that improve early productivity or higher overall production, based on the time at which they were screened. In the fourth study, a previously developed CuAAC probe for extracellular electron transfer (EET) is ported into droplets to analyze an environmental microbial consortium. This study centers on the development of an oxygen-limited platform for anaerobic microbe cultivation in microdroplets, ultimately enriching environmental microorganisms previously uncharacterized for EET. This work expands the range of microorganisms compatible with this microdroplet system. In the final study, the microorganism array is expanded further through the development of a cytotoxicity assay for Sf9 insect cells is developed for use in microdroplets. This work lays a foundation for future applications to identify novel insecticidal toxins from engineered protein libraries. Collectively, these studies establish generalizable assays for high throughput screening of a wide array of organisms related to the field of synthetic biology.Biochemistr

Expansion of Armatimonadetes through marine sediment sequencing reveals three classes with unique ecological roles

Marine sediments comprise one of the largest environments on the planet, and their microbial inhabitants are significant players in global carbon and nutrient cycles. With the advent of improved sampling techniques, recent scientific studies have shown the complexity of these communities and identified novel microorganisms from the ocean floor. Here we add to our understanding of understudied microbes by obtaining 77 metagenome-assembled genomes from the bacterial phylum Armatimonadetes in the Guaymas Basin, Gulf of California, and the Bohai Sea, coastal China. Seven of these MAGs are not classified at the class level. Thus, we propose to name these organisms Zipacnadia. Searches of public databases revealed that the 77 Armatimonadetes described in this study (including Zipacnadia) are globally distributed in hypoxic and anoxic environments and are dominant members of deep-sea sediments (up to 1.95% of the GB metagenomic raw reads). The Armatimonadetes described here also have unique metabolic capabilities for this phylum. They have pathways to reduce CO₂ to acetate via the Wood-Ljungdahl pathway (WLP) and generate energy through the oxidative branch of the Embden-Meyerhof-Parnas pathway using CO2 as an electron sink, maintaining the redox balance via WLP. Some of these organisms may also have an autotrophic lifestyle not previously identified in Armatimonadetes. Furthermore, these Armatimonadetes may play a role in sulfur and nitrogen cycling, using the intermediate compounds hydroxylamine and sulfite. The description of the Armatimonadetes identified in this study enhances our understanding of the diversity and metabolic potential of anoxic habitats worldwide.Marine Scienc

Examining physical activity among US college students following COVID-19 outbreaks and lockdowns : the role of race/ethnicity and acculturation

Objective: This study examined physical activity among US college students in the context following COVID-19 outbreaks and lockdowns, with a focus on racial/ethnic and cultural determinants. Sample: This study used cross-sectional data of the COVID-19 University Research on Education and Sustainability (CURES) project. Participants were college students from 7 public universities in the US (N = 1210; 75% female; 33.5% White, 9.1% Black, 47.6% Hispanic, and 7.1% Asian; Mage = 21.06; 85.6% born in the US, 51.6% had mother born in the US, and 49% had father born in the US). Method: The International Physical Activity Questionnaire - short form (IPAQ-SF) was used to assess physical activity and the Vancouver Index of Acculturation (VIA) – the American version was used to assess levels of heritage and US acculturation. Results: White students reported statistically significant higher physical activity than Hispanic (p < .05, Cohen’s d = .19) and Asian (p < .05, Cohen’s d = .36). In sedentary level, White students reported statistically significant lower levels than Asian (p < .05, Cohen’s d = -.45). Asian reported lowest physical activity, highest sedentary level, and highest prevalence of not meeting physical activity recommendation. Small negative correlation was found between heritage cultural level and total weekly physical activity among Hispanic students (r = - .09, p < .05). Conclusion: Race/ethnicity and cultural perception and practices could play a role in determine physical activity and sedentary behaviors among college students. The study calls for more qualitative research, and racial/ethnic and cultural-specific interventions to improve physical activity among Hispanic/Latin and Asian student populations.Kinesiology and Health Educatio