Modified multistep model predictive control for three-phase induction motor drive system considering the common-mode voltage minimization

It is acknowledged that the common-mode voltage may have detrimental effects on an induction motor (IM) drive system if not properly addressed. Therefore, in this paper, a modified multistep model predictive control method for IM drive system considering the common-mode voltage minimization is proposed. This research uses a multi-objective cost function, before applying the Sphere Decoding Algorithm to find the optimal control input. The results show that the proposed control method not only reduces the common-mode voltage significantly but also mitigates the computational burden of the microprocessor without affecting the system performance. The proposed control method is simulated by MATLAB-Simulink for an IM drive system with an 11-level cascaded H-bridge inverter.

Adaptive multistep model predictive control for tubular grid-connected solid oxide fuel cells

In the research of renewable energy power generation, tubular grid-connected solid oxide fuel cells with the apparent advantage in voltage regulation have been widely applied in power systems. Recently, a model predictive control has been applied to consider the nonlinear constraints of tubular grid-connected solid oxide fuel cells, which cannot be considered by a proportional-integral-derivative controller. While both model predictive control and proportional-integral-derivative controller achieve only 80% fuel efficiency, which should be improved. An adaptive multistep model predictive control (AMMPC) is proposed to improve the fuel efficiency of tubular grid-connected solid oxide fuel cells and simultaneously consider systemic thermodynamics and electrochemistry constraints. The AMMPC contains the advantages of adaptive control and multistep model predictive control. Both adaptive two-step model predictive control and three-step model predictive control are designed for tubular grid-connected solid oxide fuel cells. With the more accurate prediction ability, the AMMPC improves the fuel efficiency of tubular grid-connected solid oxide fuel cells with higher fuel efficiency (86.5%) than model predictive control (80%) and proportional-integral-derivative (80%). Both feasibility and effectiveness of the AMMPC are verified with high fuel efficiency under both simple and complex power demands cases.

Visualizing DEPICT: A Multistep Model for Participatory Analysis in Photovoice Research for Social Change

As a critical narrative intervention, photovoice invites community members to use photography to identify, document, and discuss issues in their communities. The method is often employed with projects that have a social change mandate. Photovoice may help participants express issues that are difficult to articulate, create tangible and meaningful research products for communities, and increase feelings of ownership. Despite being hailed as a promising participatory method, models for how to integrate diverse stakeholders feasibly, collaboratively, and rigorously into the analytic process are rare. The DEPICT model, originally developed to collaboratively analyze textual data, enhances rigor by including multiple stakeholders in the analysis process. We share lessons learned from Picturing Participation, a photovoice project exploring engagement in the HIV sector, to describe how we adapted DEPICT to collaboratively analyze participant-generated images and narratives across multiple sites. We highlight the following stages: dynamic reading, engaged codebook development, participatory coding, inclusive reviewing and summarizing of categories, and collaborative analysis and translation, and we discuss how participatory analysis is compatible with creative, interactive dissemination outputs such as exhibitions, presentations, and workshops. The benefits of Visualizing DEPICT include feelings of increased ownership by community researchers and participants, enhanced rigor, and sophisticated knowledge translation approaches that honor multiple forms of knowing and community leadership. The potential challenges include navigating team capacity and resources, transparency and confidentiality, power dynamics, data overload, and streamlining “messy” analytic processes without losing complexity or involvement. Throughout, we offer recommendations for designing participatory visual analysis processes that are connected to critical narrative intervention and social change aims.

Single cell trajectory analysis of human pluripotent stem cells differentiating towards lung and hepatocyte progenitors

ABSTRACTUnderstanding the development of human respiratory tissues is crucial for modeling and treating lung disorders. The molecular details for the specification of lung progenitors from human pluripotent stem cells (hPSCs) are unclear. Here, we use single cell RNA-sequencing with high temporal resolution along an optimized differentiation protocol to determine the transcriptional hierarchy of lung specification from human hPSCs and map out the underlying single cell trajectories. We show that Sonic hedgehog, TGF-β and Notch activation are required in an ISL1/NKX2-1 trajectory that gives rise to lung progenitors during the foregut endoderm stage. Induction of HHEX marks an alternative trajectory at the early definitive endoderm stage, which precedes the lung trajectory and generates a major hepatoblast population. Moreover, neither KDR+ nor mesendoderm progenitors are apparent intermediate states of lung and hepatic lineages. Our hierarchical multistep model predicts mechanisms leading to lung organogenesis, and creates a basis for studying early human lung development, as well as hPSC based disease and drug research.Abstract Figure

Genealogy of the neurodegenerative diseases based on a meta-analysis of age-stratified incidence data

While the central common feature of the neurodegenerative diseases (NDs) is the accumulation of misfolded proteins, they share other pathogenic mechanisms. However, we miss an explanation for the onset of the NDs. The mechanisms through which genetic mutations, present from conception are expressed only after several decades of life are unknown. We aim to find clues on the complexity of the disease onset trigger of the different NDs expressed in the number of steps of factors related to a disease. We collected brain autopsies on diseased patients with NDs, and found a dynamic increase of the ND multimorbidity with the advance of age. Together with the observation that the NDs accumulate multiple misfolded proteins, and the same misfolded proteins are involved in more than one ND, motivated us to propose a model for a genealogical tree of the NDs. To collect the dynamic data needed to build the tree, we used a Big-data approach that searched automatically epidemiological datasets for age-stratified incidence of NDs. Based on meta-analysis of over 400 datasets, we developed an algorithm that checks whether a ND follows a multistep model, finds the number of steps necessary for the onset of each ND, finds the number of common steps with other NDs and the number of specific steps of each ND, and builds with these findings a parsimony tree of the genealogy of the NDs. The tree discloses three types of NDs: the stem NDs with less than 3 steps; the trunk NDs with 5 to 6 steps; and the crown NDs with more than 7 steps. The tree provides a comprehensive understanding of the relationship across the different NDs, as well as a mathematical framework for dynamic adjustment of the genealogical tree of the NDs with the appearance of new epidemiological studies and the addition of new NDs to the model, thus setting the basis for the search for the identity and order of these steps. Understanding the complexity, or number of steps, of factors related to disease onset trigger is important prior deciding to study single factors for a multiple steps disease.

ssRNA phage penetration triggers detachment of the F-pilus

Although the F-specific ssRNA phage MS2 has long had paradigm status, little is known about penetration of the genomic RNA (gRNA) into the cell. The phage initially binds to the F-pilus using its maturation protein (Mat), and then the Mat-bound gRNA is released from the viral capsid and somehow crosses the bacterial envelope into the cytoplasm. To address the mechanics of this process, we fluorescently labeled the ssRNA phage MS2 to track F-pilus dynamics during infection. We discovered that ssRNA phage infection triggers the release of F-pili from host cells, and that higher multiplicity of infection (MOI) correlates with detachment of longer F-pili. We also report that entry of gRNA into the host cytoplasm requires the F-plasmid–encoded coupling protein, TraD, which is located at the cytoplasmic entrance of the F-encoded type IV secretion system (T4SS). However, TraD is not essential for pilus detachment, indicating that detachment is triggered by an early step of MS2 engagement with the F-pilus or T4SS. We propose a multistep model in which the ssRNA phage binds to the F-pilus and through pilus retraction engages with the distal end of the T4SS channel at the cell surface. Continued pilus retraction pulls the Mat-gRNA complex out of the virion into the T4SS channel, causing a torsional stress that breaks the mature F-pilus at the cell surface. We propose that phage-induced disruptions of F-pilus dynamics provides a selective advantage for infecting phages and thus may be prevalent among the phages specific for retractile pili.

Is death from Covid-19 a multistep process?

ABSTRACTCovid-19 death has a different relationship with age than is the case for other severe respiratory pathogens. The Covid-19 death rate increases exponentially with age, and the main risk factors are age itself, as well as having underlying conditions such as hypertension, diabetes, cardiovascular disease, severe chronic respiratory disease and cancer. Furthermore, the almost complete lack of deaths in children suggests that infection alone is not sufficient to cause death; rather, one must have gone through a number of changes, either as a result of undefined aspects of aging, or as a result of chronic disease. These characteristics of Covid-19 death are consistent with the multistep model of disease, a model which has primarily been used for cancer, and more recently for amyotrophic lateral sclerosis (ALS). We applied the multi-step model to data on Covid-19 case fatality rates (CFRs) from China, South Korea, Italy, Spain and Japan. In all countries we found that a plot of ln (CFR) against ln (age) was approximately linear with a slope of about 5. As a comparison, we also conducted similar analyses for selected other respiratory diseases. SARS showed a similar log-log age-pattern to that of Covid-19, albeit with a lower slope, whereas seasonal and pandemic influenza showed quite different age-patterns. Thus, death from Covid-19 and SARS appears to follow a distinct age-pattern, consistent with a multistep model of disease that in the case of Covid-19 is probably defined by comorbidities and age producing immune-related susceptibility. Identification of these steps would be potentially important for prevention and therapy for SARS-COV-2 infection.

What Do I Do Now? Resolving School-Based Ethical Challenges

Purpose The purpose of this article is to present a commonly used ethical decision-making approach and apply it to ethical situations commonly encountered by school-based clinicians. The application of a multistep model enables the individual to explore ethical dilemmas through fully understanding the situation and analysis of resources. These steps, followed by brainstorming, facilitate the speech-language pathologist's ability to arrive at a positive solution. Conclusion School-based speech-language pathologists deal with a variety of ethical dilemmas. Resolution can take many forms, including application of federal and state policies; professional development; and, perhaps most importantly, conversations with colleagues and administrators. The more positive solutions stem from a thorough review of the issue and policies influencing the issue followed by brainstorming a variety of potential approaches.