San Diego State University
  • San Diego, California, United States
Recent publications
In the series-parallel (S-P) compensated inductive power transfer (IPT) system for the electric vehicle charging application, an inductive filter is required after the rectifier on the secondary side to avoid the large charging current surge when the diodes conduct. This article proposes a harmonic modeling method for the S-P compensated IPT systems with an inductive filter where both the fundamental and higher order harmonics are considered. Compared to the well-known fundamental harmonic approximation (FHA) method, a more accurate description can be obtained by constructing the circuit model at different harmonics, especially in a strongly coupled case. The zero-voltage switching (ZVS) condition is derived, which shows that a larger load current will cause the power switches to lose ZVS. A larger coupling coefficient will help increase the ZVS range. The output dc voltage will drop slightly due to the high order harmonics, which is different from the FHA method where the output voltage is constant regardless of the load. Experimental results are provided to validate the effectiveness of the proposed harmonic modeling method of the S-P compensated IPT system.
Despite concerted scholarly and managerial interests in sustainability, integrating the principle of sustainable development in small and medium-sized enterprises (SMEs) remains an elusive goal. This article examines the complex interdependent nature of three strategic orientations (entrepreneurial orientation, market orientation, and sustainability orientation) and two external environmental conditions (competitive intensity and institutional support) and how they may jointly affect SME's financial, social, and environmental goals (triple bottom line or TBL)—in a nonlinear, configurational way. In accordance with this broad objective, the authors utilize fuzzy-set qualitative comparative analysis (fsQCA) on a sample of 289 SMEs operating in a developing economy. This approach enables nuanced detection of the various ways in which causal conditions (i.e., strategic orientations) and contextual conditions (i.e., external environmental factors) together can lead to the presence and absence of TBL. The analyses reveal complex causality between TBL and its antecedent conditions that cannot be explained solely by isolated net effects. Specifically, for each TBL dimension, two distinctive configurations are found to be consistently sufficient, thereby providing important theoretical and managerial implications.
All biology happens in space, and spatial structuring plays an important role in mediating biological processes at all scales from cells to ecosystems. However, the metabolomic structuring of the coral holobiont has yet to be fully explored. Here, we present a method to detect high-quality metabolomic data from individual coral polyps and apply this method to study the patterning of biochemicals across multiple spatial (~1 mm - ~100 m) and organizational scales (polyp to population). The data show a strong signature for individual coral colonies, a weaker signature of branches within colonies, and variation at the polyp level related to the polyps’ location along a branch. Mapping metabolites to either the coral or algal components of the holobiont reveals that polyp-level variation along the length of a branch was largely driven by molecules associated with the cnidarian host as opposed to the algal symbiont, predominantly putative sulfur-containing metabolites. This work yields insights on the spatial structuring of biochemicals in the coral holobiont, which is critical for design, analysis, and interpretation of studies on coral reef biochemistry.
Functional near-infrared spectroscopy (fNIRS) is a promising tool for scientific discovery and clinical application. However, its utility depends upon replicable reporting. We evaluate reporting of sociodemographics in fNIRS studies of speech and language impairment and asked the following: (1) Do refereed fNIRS publications report participant sociodemographics? (2) For what reasons are participants excluded from analysis? This systematic review was preregistered with PROSPERO (CRD42022342959) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Searches in August 2022 included the terms: (a) fNIRS or functional near-infrared spectroscopy or NIRS or near-infrared spectroscopy, (b) speech or language, and (c) disorder or impairment or delay. Searches yielded 38 qualifying studies from 1997 to present. Eight studies (5%) reported at least partial information on race or ethnicity. Few studies reported SES (26%) or language background (47%). Most studies reported geographic location (100%) and gender/sex (89%). Underreporting of sociodemographics in fNIRS studies of speech and language impairment hinders the generalizability of findings. Replicable reporting is imperative for advancing the utility of fNIRS.
Background Safe drinking water is a fundamental human right, yet more than 785 million people do not have access to it. The burden of water management disproportionately falls on women and young girls, and they suffer the health, psychosocial, political, educational, and economic effects. While water conditions and disease outcomes have been widely studied, few studies have summarized the research on drinking water and implications for gender equity and empowerment (GEE). Methods A systematic review of primary literature published between 1980 and 2019 was conducted on drinking water exposures and management and the implications for GEE. Ten databases were utilized (EMBASE, PubMed, Web of Science, Cochrane, ProQuest, Campbell, the British Library for Development Studies, SSRN, 3ie International Initiative for Impact Evaluation, and Drinking water studies with an all-female cohort or disaggregated findings according to gender were included. Results A total of 1280 studies were included. GEE outcomes were summarized in five areas: health, psychosocial stress, political power and decision-making, social-educational conditions, and economic and time-use conditions. Water quality exposures and implications for women's health dominated the literature reviewed. Women experienced higher rates of bladder cancer when exposed to arsenic, trihalomethanes, and chlorine in drinking water and higher rates of breast cancer due to arsenic, trichloroethylene, and disinfection byproducts in drinking water, compared to men. Women that were exposed to arsenic experienced higher incidence rates of anemia and adverse pregnancy outcomes compared to those that were not exposed. Water-related skin diseases were associated with increased levels of psychosocial stress and social ostracization among women. Women had fewer decision-making responsibilities, economic independence, and employment opportunities around water compared to men. Conclusion This systematic review confirms the interconnected nature of gender and WaSH outcomes. With growing attention directed towards gender equity and empowerment within WaSH, this analysis provides key insights to inform future research and policy.
Frontline employees are inextricably linked to the perceived quality of hospitality service experiences and are fundamental to developing and securing customer loyalty and repeat visitation. Research has shown that hospitality service quality is heavily influenced by workers’ wellbeing which is linked to the emotional labor they must perform in their interactions with customers. For a sector that relies so heavily on the wellbeing of its workers, the hospitality industry suffers from extraordinarily high levels of workplace stress and burnout. Acknowledging the challenges being faced, a good deal of research has been dedicated to understanding the links between emotional labor, wellbeing, and service quality and devising practices and strategies to protect and enhance the wellbeing of frontline hospitality employees. This chapter provides a review of emotional labor and wellbeing in the hospitality workforce and makes the case for the inclusion of organizational leaders’ wellbeing. Particularly in light of the challenges faced by the hospitality industry as the world emerges from the COVID-19 pandemic, the wellbeing of leaders has the potential to impact the experience of large numbers of workers under their management. Thus, in addition to the on-going discussions on hospitality frontline employee wellbeing, this chapter raises the importance in understanding hospitality leaders’ wellbeing when studying hospitality organizations.
An IgE epitope is a part of an allergen that is capable of binding to IgE antibodies and eliciting an immune response. Identifying and characterizing human-allergy-relevant epitopes are important for diagnosis and prognosis of food allergy and development of immunotherapy treatments. This chapter describes the protocol for manual synthesis of overlapping peptides on a cellulose membrane and subsequent dot blotting of the peptides with allergic patients’ IgE to map the linear IgE-binding epitopes in food allergens.
Isolation of food allergens from natural sources enables their characterization in a naturally occurring state. Low-pressure liquid chromatographic methods can be used to purify such allergens with high purity and yield. In this chapter, we describe the protocol for isolating a nut seed protein from its natural source. Interfering macromolecules such as fats and carbohydrates are removed followed by solubilization and extraction of nut seed proteins. The target protein is purified using a combination of various chromatographic techniques.
Enzyme-linked immunosorbent assay (ELISA) is a widely used analytical technique for food allergen detection and quantification. Validating ELISA protocols is important for both assay developers and end users as it ensures method reliability. This chapter describes the protocols for validating the sensitivity, specificity, precision, accuracy, robustness, and ruggedness of an ELISA. Example procedures are also provided for sample preparation, allergen extraction, and ELISA operation.
Our earlier work in Nguyen et al. (Maximizing metapopulation growth rate and biomass in stream networks. arXiv preprint arXiv:2306.05555, 2023) shows that concentrating resources on the upstream end tends to maximize the total biomass in a metapopulation model for a stream species. In this paper, we continue our research direction by further considering a Lotka–Volterra competition patch model for two stream species. We show that the species whose resource allocations maximize the total biomass has the competitive advantage.
Social distancing is an important non-pharmaceutical intervention tool (NPIs) to prevent the spread of COVID-19. However, it also created negative impacts of economic activities. Understanding the emotions and public opinions about social distancing are important for the future policy making of COVID-19 mitigation and the assessment of public health impacts. This study collected 77,627 number of Twitter messages (tweets) between February 1, 2020 and April 30, 2020 from five English-speaking countries (United States, the United Kingdom, India, Canada, and Australia) using the social distancing keywords. We adopted a multi-module hybrid convolutional neural network model sentiment analysis on social distancing related tweets with 85.95% accuracy. This paper conducts a sentiment analysis of tweets from the public on social distancing measures in five countries. Our findings show similar sentiments in tweets from these five countries, which is more positives than negatives about social distancing measures in the public. Additionally, when the daily number of new cases changes, public sentiment fluctuates with it. We believe that social distancing is effective in preventing the spread of coronavirus.
Models of affect, like the tripartite model, suggest that positive affect (PA) and negative affect (NA) are independent between subjects and negatively correlated within. Correlations may differ in bipolar disorder (BD) and schizophrenia. Using ecological momentary assessment (EMA) and clinical ratings, this secondary analysis evaluated the tripartite model by examining PA and NA. Two hundred eighty-one participants with BD or a psychotic disorder completed 30 days of EMA of PA and NA, and clinical raters assessed depression. PA and NA were more related between subjects and less related within subjects among participants with schizophrenia. In BD, lower momentary PA was positively associated with clinical ratings of depression, although greater momentary NA was not significantly associated with clinical ratings. In schizophrenia, the inverse was found. These results suggest that the tripartite model was not confirmed in people with schizophrenia or BD. However, PA and NA manifested associations in BD that were more congruent with population studies than in schizophrenia. These findings may have implications for clinical interventions targeting depression, PA, and NA in these populations.
We examine how a CEO's family life affects their corporate decisions. Specifically, we investigate whether a CEO's spouse's professional status affects the CEO's risk‐taking behavior. Using a sample of S&P 500 firms from the 2010 to 2012 period, we find evidence that CEOs with spouses who are professionals, defined as working spouses, spouses holding graduate degrees, or spouses graduated from Ivy League schools, tend to adopt riskier corporate policies. Our evidence suggests that firms led by CEOs with professional spouses exhibit higher accounting return volatility, make more aggressive financial reporting decisions, and invest more in risky assets. We do not find a significant association between professional spouses and firms’ market return volatility. Our results are consistent with the indirect channel theory, which suggests that CEOs with professional spouses might be inclined to undertake higher risks, potentially stemming from heightened conflicts between family and work commitments or improved wealth diversification attributed to their spouses' professional standing.
This book explores how private security guards are a permanent, conspicuous fixture of everyday life in the Brazilian city of Rio de Janeiro. The book examines the provision of security in Rio from the perspective of security personnel, providing an analysis of the racialized logics that underpin the ongoing work of securing the city. It shows how guards communicate a sensação de segurança (a sensation of security) to clients and customers who have the capital to pay for it. Cultivated through performances by security laborers, the sensation of security is a set of culturally shaped racialized and gendered impressions related to safety, order, well-being, and cleanliness. While the sensação de segurança indexes an outward-facing task of allaying fears of crime and maintaining order in elite spaces, it also refers to the emotional labor and embodied worlds that security workers navigate.
This paper has proposed a hybrid seven-level inverter topology with a boosting capability three times that of conventional seven-level inverter topologies. It contains ten number of active switches and an internal flying capacitor unit that develops a composition like the combination of T-type and neutral point clamped (NPC) inverter topologies. The proposed inverter topology increases dc link voltage utilization and reduces the total standing voltages across the power switches. In addition, self-voltage balancing of the floating capacitor is achieved through a simple level shifted PWM modulation technique. The dc link requirement of the proposed inverter topology is reduced by 66% when compared to the conventional seven-level inverters, and it can be more useful in industrial applications, including grid-tied renewable generation units. The working methodology and steady state analysis of the topology are presented, and its operation is validated through the simulation results performed in both Matlab/Simulink and PSIM platforms. In addition, experimental results verify the proposed inverter topology.
Emergent behavior in complex networks can be predicted and analyzed via the mechanism of spontaneous symmetry-breaking bifurcation, in which solutions of related bifurcation problems lose symmetry as some parameters are varied, even though the equations that such solutions satisfy retain the full symmetry of the system. A less common mechanism is that of forced symmetry-breaking, in which either a bifurcation problem has symmetry on both the state variables and the parameters, or one where the equations have less symmetry when a certain parameter is varied. In this manuscript, it is shown that in certain networks with parameter mismatches the governing equations remain unchanged when the group of symmetries acts on both the state variables and the parameter space. Based on this observation we study the existence and stability of collective patterns in symmetric networks with parameters mismatches from the point of view of forced symmetry-breaking bifurcations. Treating the parameters as state variables, we perform center manifold reductions, which allow us to understand how the disorder in parameters affects the bifurcation points as well as the stability properties of the ensuing patterns. Theoretical results are validated with numerical simulations.
Objectives Characterizing the scope and import of early childhood irritability is essential for real‐world actualization of this reliable indicator of transdiagnostic mental health risk. Thus, we utilize pragmatic assessment to establish prevalence, stability, and predictive utility of clinically significant early childhood irritability. Methods Data included two independent, diverse community samples of preschool age children ( N = 1857; N = 1490), with a subset enriched for risk ( N = 425) assessed longitudinally from early childhood through preadolescence (∼4–9 years old). A validated, brief (2‐item) scale pragmatically assessed clinically significant irritability. In the longitudinal subsample, clinical interviews assessed internalizing/externalizing disorders. Results One in five preschool‐age children had clinically significant irritability, which was independently replicated. Irritability was highly stable through preadolescence. Children with versus without clinically significant early childhood irritability had greater odds of early onset, persistent internalizing/externalizing disorders. The pragmatic assessment effectively screened out low‐risk children and identified 2/3 of children with early‐onset, persistent psychopathology. Conclusions Clinically significant early childhood irritability prevalence is akin to the pediatric obesity epidemic and may warrant similar universal screening/intervention. Also, irritability's stability demonstrates the common guidance “they'll grow out of it” to be false. Finally, pragmatic irritability assessment has transdiagnostic predictive power and addresses a need for feasible measures to flag risk.
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7,761 members
fred joel harris
  • Department of Electrical and Computer Engineering
Tracy Love
  • School of Speech, Language, and Hearing Sciences
Carol Macera
  • Graduate School of Public Health
Barry Benton Hanan
  • Department of Geological Sciences
5500 Campanile Drive, 92182, San Diego, California, United States
Head of institution
Dr. Adela de la Torre