bluuebunny/crossref_metadata_2025 huggingface dataset:
Regression Models for Predictions of COVID-19 New Cases and New Deaths Based on May/June Data in Ethiopia
Authors: Argawu Alemayehu Siffir
Published: September 2020

As the 15 of June 2020, we have 7,984,067 total COVID-19 cases, globally and 435,181 total deaths. Ethiopia was ranked 2ndand 15thin the table by 176 new cases and by 3,521 total new cases from African countries. Then, this study aimed to predict COVID-19 new cases and new deaths based on May/June data in Ethiopia using regression model. In this study, I used Pearson’s correlation analysis and the linear regression model to predict COVID-19 new cases and new deaths based on the available data from 12thMay to 10thJune 2020 in Ethiopia. There was a significant positive correlation between COVID-19 new cases and new deaths with different related variables. In the regression models, the simple linear regression model was a better fit the data of COVID-19 new cases and new deaths than as compared with quadratic and cubic regression models. In the multiple linear regression model, variables such as the number of days, the number of new laboratory tests, and the number of new cases from AA city significantly predicted the COVID-19 new cases. In this model, the number of days and new recoveries significantly predicted new deaths of COVID-19. The number of days, daily laboratory tests, and new cases from Addis Ababa city significantly predicted new COVID-19 cases, and the number of days and new recoveries significantly predicted new deaths from COVID-19. According to this analysis, if strong preventions and action are not taken in the country, the predicted values of COVID-19 new cases and new deaths will be 590 and 12 after two months (after 9thof August) from now, respectively. The researcher recommended that the Ethiopia government, Ministry of Health and Addis Ababa city administrative should give more awareness and protections for societies, and they should also open more COVID-19 laboratory testing centers. Generally, the obtained results of this study may help Ethiopian decision-makers put short-term future plans to face this epidemic.
Lack of evidence for association of UQCRC1 with Parkinson’s disease in Europeans
Authors: Senkevich Konstantin , Bandres-Ciga Sara , Gan-Or Ziv , Krohn Lynne
Published: September 2020

Recently, a novel variant p.Y314S in UQCRC1 has been implicated as pathogenic in Parkinson’s disease (PD). In the current study, we aimed to examine the association of UQCRC1 with PD in large cohorts of European origin. We examined common and rare genetic variation in UQCRC1 using genome-wide association study data from the International Parkinson Disease Genomics Consortium (IPDGC), including 14,671 cases and 17,667 controls, and whole-genome sequencing data from the Accelerating Medicines Partnership - Parkinson’s disease initiative (AMP-PD), including 1,647 PD patients and 1,050 controls. No common variants were consistently associated with PD, and a variety of burden analyses did not reveal an association between rare variants in UQCRC1 and PD. Therefore, our results do not support a major role for UQCRC1 in PD in the European population, and additional studies in other populations are warranted.
COVID-19 Preprints and Their Publishing Rate: An Improved Method
Authors: Lachapelle Francois
Published: September 2020

Context

As the COVID-19 pandemic persists around the world, the scientific community continues to produce and circulate knowledge on the deadly disease at an unprecedented rate. During the early stage of the pandemic, preprints represented nearly 40% of all English-language COVID-19 scientific corpus (6, 000+ preprints | 16, 000+ articles). As of mid-August 2020, that proportion dropped to around 28% (13, 000+ preprints | 49, 000+ articles). Nevertheless, preprint servers remain a key engine in the efficient dissemination of scientific work on this infectious disease. But, giving the ‘uncertified’ nature of the scientific manuscripts curated on preprint repositories, their integration to the global ecosystem of scientific communication is not without creating serious tensions. This is especially the case for biomedical knowledge since the dissemination of bad science can have widespread societal consequences.

Scope

In this paper, I propose a robust method that will allow the repeated monitoring and measuring of COVID-19 preprint’s publication rate. I also introduce a new API called Upload-or-Perish. It is a micro-API service that enables a client to query a specific preprint manuscript’s publication status and associated meta-data using a unique ID. This tool is in active development.

Data

I use Covid-19 Open Research Dataset (CORD-19) to calculate COVID-19 preprint corpus’ conversion rate to peer-reviewed articles. CORD-19 dataset includes preprints from arXiv, bioRxiv, and medRxiv.

Methods

I utilize conditional fuzzy logic on article titles to determine if a preprint has a published counterpart version in the database. My approach is an important departure from previous studies that rely exclusively on bioRxiv API to ascertain preprints’ publication status. This is problematic since the level of false positives in bioRxiv metadata could be as high as 37%.

Findings

My analysis reveals that around 15% of COVID-19 preprint manuscripts in CORD-19 dataset that were uploaded on from arXiv, bioRxiv, and medRxiv between January and early August 2020 were published in a peer-reviewed venue. When compared to the most recent measure available, this represents a two-fold increase in a period of two months. My discussion review and theorize on the potential explanations for COVID-19 preprints’ low conversion rate.
CASCADES, a novelSOX2super-enhancer associated long noncoding RNA, regulates cancer stem cell specification and differentiation in glioblastoma multiforme
Authors: Shahzad Uswa , Li Christopher , Johnston Michael , Wang Jenny J. , Sabha Nesrin , Varn Frederick S. , Riemenschneider Alexandra , Krumholtz Stacey , Meda Pranathi , Smith Christian A. , Karamchandani Jason , Watts Jonathan K. , Verhaak Roel G.W. , Gallo Marco , Rutka James T. , Das Sunit
Published: September 2020

Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults, with a median survival of just over one year. The failure of available treatments to achieve remission in patients with GBM has been attributed to the presence of cancer stem cells (CSCs), which are thought to play a central role in tumor development and progression and serve as a treatment-resistant cell repository capable of driving tumor recurrence; in fact, the property of “stemness” itself may be responsible for treatment resistance. In this study, we identify a novel lncRNA, Cancer stem cell associated distal enhancer ofSOX2(CASCADES) that functions as an epigenetic regulator in glioma CSCs (GSCs).CASCADESis expressed in IDH-wild type GBM and significantly enriched in GSCs. Knockdown ofCASCADESin GSCs results in differentiation towards a neuronal lineage in a cell- and cancer-specific manner. Bioinformatics analysis reveals thatCASCADESfunctions as a super-enhancer associated lncRNA epigenetic regulator ofSOX2. Our findings identifyCASCADESas a critical regulator of stemness in GSCs and represent a novel epigenetic and therapeutic target for disrupting the cancer stem cell compartment in GBM.
TSC-Insensitive Rheb Mutations Induce Oncogenic Transformation Through a Combination of Hyperactive mTORC1 Signalling and Metabolic Reprogramming
Authors: Xie Jianling , De Poi Stuart P. , Humphrey Sean J. , Hein Leanne K. , Bruning John , Pan Wenru , Sargeant Timothy J. , Proud Christopher G.
Published: September 2020

The mechanistic target of rapamycin complex 1 (mTORC1) is an important regulator of cellular metabolism that is commonly hyperactivated in cancer. Recent cancer genome screens have identified multiple mutations in Ras-homolog enriched in brain (Rheb), the primary activator of mTORC1, that might act as driver oncogenes by causing hyperactivation of mTORC1. Here, we show that a number of recurrently occurring Rheb mutants drive hyperactive mTORC1 signalling through differing levels of insensitivity to the primary inactivator of Rheb, Tuberous Sclerosis Complex.

We show that two activated mutants, Rheb-T23M and E40K, strongly drive increased cell growth, proliferation and anchorage-independent growth resulting in enhanced tumour growthin vivo. Proteomic analysis of cells expressing the mutations revealed, surprisingly, that these two mutants promote distinct oncogenic pathways with Rheb-T23M driving metabolic reprogramming and an increased rate of glycolysis, while Rheb-E40K regulates the translation factor eEF2 and autophagy, likely through a differential interaction with AMPK.

Our findings suggest that unique ‘bespoke’ combination therapies may be utilised to treat cancers according to which Rheb mutant they harbour.
Myosin 7b is a regulatory long noncoding RNA (lncMYH7b) in the human heart
Authors: Broadwell Lindsey J. , Smallegan Michael J. , Rigby Kevin M. , Navarro-Arriola Jose S. , Montgomery Rusty L. , Rinn John L. , Leinwand Leslie A.
Published: September 2020

Myosin heavy chain 7b (MYH7b) is an ancient member of the myosin heavy chain motor protein family that is expressed in striated muscles. In mammalian cardiac muscle, MYH7b RNA is expressed along with two other myosin heavy chains, β-myosin heavy chain (β-MyHC) and α-myosin heavy chain (a-MyHC). However, unlike β-MyHC and α-MyHC which are maintained in a careful balance at the protein level, the MYH7b locus does not produce protein in the heart due to a post-transcriptional exon-skipping mechanism that occurs in a tissue specific manner. Whether this locus has a role in the heart beyond producing its intronic microRNA, miR-499, was unclear. Using cardiomyocytes derived from human induced pluripotent stem cells as a model system, we have found that the non-coding exon skipped RNA (lncMYH7b) affects the transcriptional landscape of the human heart, independent of miR-499. Specifically, lncMYH7b regulates the ratio of β-MyHC to α-MyHC, which is crucial for heart function. This regulation is likely achieved through control of members of the TEA domain transcription factor family (TEAD1 and TEAD3). Therefore, we conclude that this ancient gene has been repurposed by alternative splicing to produce a regulatory long-noncoding RNA in the human heart that affects the myosin composition of the heart.
TWIST1 and chromatin regulatory proteins interact to guide neural crest cell differentiation
Authors: Fan Xiaochen , Masamsetti V. Pragathi , Sun Jane Q. J. , Engholm-Keller Kasper , Osteil Pierre , Studdert Joshua , Graham Mark E. , Fossat Nicolas , Tam Patrick P.L.
Published: September 2020

Protein interaction is critical molecular regulatory activity underlining cellular functions and precise cell fate choices. Using TWIST1 BioID-proximity-labelling and network propagation analyses, we discovered and characterized a TWIST-chromatin regulatory module (TWIST1-CRM) in the neural crest cell (NCC). Combinatorial perturbation of core members of TWIST1-CRM: TWIST1, CHD7, CHD8, and WHSC1 in cell models and mouse embryos revealed that loss of the function of the regulatory module resulted in abnormal specification of NCCs and compromised craniofacial tissue patterning. Our results showed that in the course of cranial neural crest differentiation, phasic activity of TWIST1 and the interacting chromatin regulators promote the choice of NCC fate while suppressing neural stem cell fates, and subsequently enhance ectomesenchyme potential and cell motility. We have revealed the connections between TWIST1 and potential neurocristopathy factors which are functionally interdependent in NCC specification. Moreover, the NCC module participate in the genetic circuit delineating dorsal-ventral patterning of neural progenitors in the neuroepithelium.
Trends in environmental accounting research within and outside of the accounting discipline
Authors: Marrone Mauricio , Linnenluecke Martina K. , Richardson Grant , Smith Tom
Published: September 2020

Purpose

The purpose of this article is to track the emergence of topics and research trends in environmental accounting research by using a machine learning method for literature reviews. The article shows how the method can track the emergence of topics and research trends over time.

Design/methodology/approach

The analysis of the emergence of topics and shifts in research trends was based on a machine learning approach that allowed the authors to identify “topic bursts” in publication data. The data set of this study contained, 2,502 records published between 1972 and 2019, both within and outside of accounting journals. The data set was assembled through a systematic keyword search of the literature.

Findings

Findings indicated that research studies within accounting journals have addressed sustainability concerns in a general fashion, with a recent focus on broad topics such as corporate social responsibility (CSR) and stakeholder theory. Research studies published outside of accounting journals have focussed on more specific topics (e.g. the shift to a low-carbon or circular economy, the attainment of the sustainable development goals [SDGs], etc.) and new methodologies (e.g. accounting for ecosystem services).

Research limitations/implications

The method provides an approach for identifying “trending” topics within accounting and non-accounting journals and allows to identify topics and areas that could benefit from a greater exchange of ideas between accounting and non-accounting journals.

Originality/value

The authors provide a much needed review of research on the vitally important topic of environmental accounting not only in accounting journals but also in the broader research community.
Contribution of developed countries towards MOOCs: an exploration and assessment from a representative platform Coursera
Authors: Ayoub Arshia , Amin Raashida , Wani Zahid Ashraf
Published: September 2020

Purpose

The recent spate of eminence received by the MOOCs (massive open online courses) from media to academia is revolutionary in higher education. MOOCs are a disruptive technological innovation which offers open learning with the aid of the internet and delivered by the faculty of reputed institutions, globally. Since Coursera being one such significant platform, its exploration would display the broader picture of MOOCs. As a result, studying it from various dynamics has been the motive of the current endeavour.

Design/methodology/approach

The quantitative study of the collected data was applied with help of descriptive research methodology to measure the contribution of the top six countries namely US, China, Japan, Germany, India and UK. All these six countries were selected on the basis of GDP (harvested from official website World Bank – data.worldbank.org/ to Coursera––an online platform providing MOOCs. The involvement of these selected countries was gauged (from the official website of Coursera https://www.coursera.org/) in terms of number, type of contributing institutions, number of courses offered by those institutions, type of courses offered, number of instructors and instructor gender ratio.

Findings

The findings reveal that the United States (US) is the top contributor in terms of partner institutes (97), courses (Specialization courses – 1,267 and degree courses– 40) and number of instructors (1,290). Interestingly, it was also observed that universities are the major contributor institutes in all six studied countries. Most of the institutes provide specialization courses while a very few provide degree courses. A large number of instructors are involved for imparting these courses online. Instructor gender ratio on average is 2:1 (male: female). It was also observed that there is usually a specific common time of starting courses on Coursera.

Originality/value

Online platforms are the main delivery points for MOOCs; therefore, vibrancy and articulacy of such platforms make this innovation a success, and examining such a platform which exhibits such characteristics would present an overall picture of its functionality, development, evolution and future expansion of the innovation (MOOCs).
Corporate entrepreneurship, national policies and supply chain collaborations: an empirical study of Malaysian LED manufacturers
Authors: Mohezar Suhana , Sulaiman Ainin , Mohamad Nor Mohammad Nazri , Omar Safiah
Published: September 2020

Purpose

This paper aims to examine the impacts of corporate entrepreneurship, national policies and supply chain collaboration on the innovativeness of manufacturers of light emitting diode (LED) in Malaysia.

Design/methodology/approach

The data were collected by using questionnaire survey from the manufacturers involved in the various echelon of the supply chain. The data collected were analyzed by using partial least square (PLS).

Findings

Corporate entrepreneurship plays a moderating role in the relationship between national policies, supply chain collaboration and innovativeness.

Research limitations/implications

This study is only focusing on the supply chain of LED in Malaysia; hence, the results may not be suitable to be generalized to wider populations.

Practical implications

The findings of this study could help the local companies to understand on how, as entrepreneurs, they could expand from small scale to contract manufacturers through enhancing innovativeness. This is important as failure to do so may cause them to be excluded from the global supply chain.

Originality/value

This study expands the existing literature by providing empirical evidence from the perspective of an emerging country, namely, Malaysia. It also attempts to close the gaps by examining the role of corporate entrepreneurship as the moderating variable.
Brand experience and brand loyalty: is it a matter of emotions?
Authors: Mostafa Rania B. , Kasamani Tamara
Published: September 2020

Purpose

Based on the stimulus–organism–response (SOR) model, the aim of this study is to explore the impact of brand experience (BE) on brand loyalty, with the mediation effect of emotional brand attachment (EBA) dimensions, specifically brand passion, self-brand connection and brand affection.

Design/methodology/approach

The study utilized a sample of 278 smartphone users in Lebanon. A questionnaire was used for data collection and a mediation analysis was employed to test the hypothesized relationships.

Findings

The findings revealed that experiential brands promote long-lasting brand loyalty through building brand passion, self-brand connection and brand affection.

Practical implications

To achieve a long-standing brand–consumer relationship, marketing managers should enhance and augment experiential marketing practices as this triggers deep emotional links and builds strong emotional ties with customers.

Originality/value

In contrast to previous studies on BE and loyalty, this research contributes to the literature by deepening the impact of emotions from the EBA perspective, specifically brand passion, brand affection and self-brand connection and posits the latter as mediators to the link between the BE and brand loyalty in the smartphone industry.
The matching effect of anthropomorphized brand roles and product messaging on product attitude
Authors: He Yuanqiong , Zhou Qi , Guo Shuojia , Xiong Jie
Published: September 2020

Purpose

This study aims to investigate the construal congruence of anthropomorphized brand roles and product messaging and its underlying mechanism on consumers' product attitude.

Design/methodology/approach

Four experimental studies were conducted to test the hypotheses. Study 1 investigated the framing effect of anthropomorphized brand roles (servant vs partner) in consumers' minds. Study 2 examined the matching effect of anthropomorphized brand roles and product messaging on product attitude. 132 students were randomly assigned to a 2 (anthropomorphized roles: servant vs partner) × 2 (product messaging: higher-level construal vs lower-level construal) between-subject factorial design. Study 3 tested the mediation effect of processing fluency underlying the construal congruence mechanism. Study 4 replicated the results of study 3 and further examined the boundary conditions by introducing product innovation locus as a moderator. A total of 218 students were randomly assigned to a 2 (anthropomorphized role: servant vs partner) × 2 (product messaging: higher-level construal vs lower-level construal) × 2 (innovation locus: core innovation vs peripheral locus) between-subjects design experiment.

Findings

The results demonstrate that a construal match between product messaging and anthropomorphized brand roles –anthropomorphized “servant” with higher-level construal messaging and anthropomorphized “partner” with lower-level construal messaging – can positively influence consumers' attitude via enhanced processing fluency. Furthermore, this construal matching effect on product attitude is moderated by the innovation locus of the product.

Practical implications

This study reveals that anthropomorphized brand roles with compatible product messaging in the associated construal levels lead to more favorable product attitudes. Furthermore, the matching effect of anthropomorphized brand roles and product messaging is stronger for products with peripheral innovation than with core innovation.

Originality/value

Our study contributes to the literature in two ways. First, it provides new insights into the construal matching effect of anthropomorphized brand roles and product messaging. Second, it investigates the boundary conditions of the above-mentioned construal fit mechanism.
Factors influencing organizational agility in higher education
Authors: Menon Shalini , Suresh M.
Published: September 2020

Purpose

The purpose of this paper is to explore the factors that can facilitate agility in higher education and to analyze the interrelationship between the factors.

Design/methodology/approach

A structured model of factors facilitating agility in higher education was developed using total interpretive structural modeling (TISM). Cross-impact matrix multiplication (MICMAC) analysis helped in classifying the factors on the basis of their driving and dependency power.

Findings

An extensive literature review and expert opinion helped in identifying eight enablers that can promote agility in higher education. The ability to sense the environment, organizational structure, adoption of ICT, organizational learning, human resource strategies, leadership, readiness to change and collaboration with the stakeholders were the eight factors identified. The structural model revealed leadership as the most crucial enabler followed by human resource strategies and organizational structure.

Research limitations/implications

The model has incorporated and prioritized all the crucial drivers of agility that can help universities and colleges design, adopt and implement policies and practices that would facilitate agility.

Originality/value

So far, the research on agility in higher education has looked into each factor in isolation. This research provides a comprehensive list of the factors and establishes the interplay between the factors making this study new and original.
Students' satisfaction and continuance intention of the cloud-based e-learning system: roles of interactivity and course quality factors
Authors: Cheng Yung-Ming
Published: September 2020

Purpose

The purpose of this study is to propose a research model based on expectation-confirmation model (ECM) to examine whether interactivity and course quality factors (i.e. course content quality, course design quality) as antecedents to student beliefs can influence students' satisfaction and continuance intention of the cloud-based electronic learning (e-learning) system within the educational institution.

Design/methodology/approach

Sample data were collected from students enrolled in a comprehensive university in Taiwan. A total of 600 questionnaires were distributed in the campus, and 515 (85.8%) useable questionnaires were analyzed using structural equation modeling.

Findings

Findings showed that students' perceptions of interactivity, course content quality and course design quality positively significantly contributed to their perceived usefulness, confirmation and satisfaction with the cloud-based e-learning system, which in turn directly or indirectly led to their continuance intention of the system. Thus, the results strongly supported the research model based on ECM via positioning key constructs as the drivers with all hypothesized links being significant.

Originality/value

This study identifies three factors (i.e. interactivity, course content quality, course design quality) as drivers from the learner perspective within the cloud-based e-learning environment, and links these factors to students' satisfaction and continuance intention of the cloud-based e-learning system based on ECM. It is particularly worth mentioning that the three drivers can serve as precursors for recognizing the determinants that are crucial to understand students' satisfaction and continuance intention of the cloud-based e-learning system. Hence, this study may provide new insights in nourishing the cloud-based e-learning continuance literature in the future.
Towards a global model of accounting education – a South African case study
Authors: Lubbe Ilse
Published: September 2020

Purpose

The purpose of this paper is to provide a contextual analysis of the professional accounting education system of South Africa (SA).

Design/methodology/approach

The paper uses the Global Model of Accounting Education (Watty et al., 2012) to describe the accounting education system of SA, which is then compared with similar case studies of Australia, Japan and Sri Lanka. Information about the SA accounting education system is contextualised from multiple sources, using data triangulation.

Findings

Several similarities between the SA accounting education system and that of Australia are found, such as the role and involvement of the professional bodies in the accreditation processes, with less similarities with that of Japan and Sri Lanka. The comparisons illuminate the economic development of each country and the level of involvement in the education programmes by the profession. Specific challenges in SA include the entrance hurdles to higher education and emphasis on an accounting degree.

Practical implications

The application of the Global Model of Accounting Education helps to identify the similarities in the global accounting arena and illuminates the uniqueness of the SA accounting education system. This study illustrates the establishment of an accounting education system that aligns with the International Education Standards (IESs).

Originality/value

The study contributes to the discussions around challenges in accounting education, specifically those associated with accreditation and a strong controlling relationship between academe and the profession.
Abusive supervision as a trigger of malevolent creativity: do the Light Triad traits matter?
Authors: Malik Omer Farooq , Shahzad Asif , Waheed Aamer , Yousaf Zarash
Published: September 2020

Purpose

Drawing on affective events theory, the authors investigated whether exposure to abusive supervision triggers malevolent creativity among victims and the role of psychological contract violation (PCV) as a mediator in this relationship. The authors also examined the moderating effects of the Light Triad personality traits comprising Kantianism, humanism and faith in humanity.

Design/methodology/approach

The sample comprised 297 junior doctors working at various clinical departments of public sector hospitals in three major cities of Pakistan. Data were collected using a self-administered questionnaire and the hypothesized model was tested using the covariance-based structural equation modeling in Mplus.

Findings

Results demonstrated that abusive supervision influences malevolent creativity directly and indirectly mediated through PCV. Further, results showed that individuals high on the Light Triad traits are less likely to engage in malevolently creative acts in response to abusive supervision and feelings of violation than those low on the Light Triad.

Originality/value

The authors contribute to the literature by demonstrating that exposure to abusive supervision influences the generation of malevolently creative ideas among subordinates. Further, the authors showed that subordinates high on the Light Triad handle abusive supervisory behaviors and negative emotional reactions more productively and are less likely to retaliate against perceived mistreatment compared to their counterparts.
iPhone for data collection: distraction in low-technology home
Authors: Teichert Laura
Published: September 2020

Purpose

This paper describes the unintended and unanticipated ways an iPhone as a data collection tool created distractions during observations of five-year-old twins' digital literacy practices while in their home.

Design/methodology/approach

Situated in sociocultural theories of learning and development and new literacy studies, the 12-month-long case study examined young children's digital literacy practices in their homes before and during their transition into kindergarten. The article focuses on the data collection of five-year-old twins in their home with their parents, a family the author called the Skywalkers. Data sources included semistructured interviews, participant observations and informal conversations.

Findings

The mother was a low-technology user and preferred her children to engage in nondigital activities. The children were permitted 10 min every other day of “digital time.” The iPhone as a data collection tool provided them with digital access they would otherwise not have. The mother knew the focus of the study was digital engagement and that the iPhone was used for data collection (i.e. photographs and videos). Although the iPhone was intended to be used in establishing rapport and taking photographs, the children frequently asked to video record their play and therefore the iPhone became a distraction.

Originality/value

Given the prevalence of smartphones in Western society, the recruitment of a family with such low-technology use was unforeseen. As digital data collection increases in qualitative research, researchers should not assume that a smartphone is always appropriate for gathering photographic data. This is particularly important when investigating digital literacy practices of families in their homes.
Optimal Command Shaping Design for a Liquid Slosh Suppression in Overhead Crane Systems
Authors: Khorshid Emad , Al-Fadhli AbdulAziz
Published: September 2020

In many industries, liquid container transport is carried out by an overhead traveling crane. The operation of crane transferring liquid slosh containers required both operator experience and an automated control system. The goal of this research is to move the liquid inside a container in a short time and less spill for process effectiveness and safety. For controller design, a nonlinear mathematical model is developed to represent the actual system. A cost-effective, smooth continuous command shaper is presented to suppress sloshing vibration. The designed shaper is a multisine-wave function with adjustable and independent time maneuvering used to design the acceleration profile. The coefficients that control the shaper profile are obtained by solving a nonlinear constrained optimization problem using particle swarm algorithm. Simulation and experimental comparative results proved that the proposed command shaper can reduce transient peak slosh amplitudes. Moreover, it can simultaneously cancel both residual sloshing vibrations and container oscillations at the end of the transportation process which cannot be achieved using conventional zero-vibration (ZV), zero-vibration derivative (ZVD), and jerk-limited shaper. Furthermore, sensitivity analysis demonstrates that the proposed command shaper is robust to model parameters variation such as liquid depth, suspension length, or moving distance of the trolley.
Breathing Crack Model Effect on Rotor's Postresonance Backward Whirl
Authors: Alzarooni Tariq , Al-Shudeifat Mohammad A. , Shiryayev Oleg , Nataraj C.
Published: September 2020

In this work, we investigate the appearance of postresonance backward whirl (Po-BW) using the model of a rotor with a breathing crack. This phenomenon could be employed as an indicator of crack and bearing damage in rotor systems that undergo recurrent passage through critical forward whirl rotational speed during startup and coast down operations. The finite element (FE) model is used to develop the linear-time-varying equations of motion of the considered accelerating cracked rotor. The whirl response is obtained by direct numerical integration. In addition, the effect of bearing anisotropy on Po-BW excitation is investigated. It is found that the appearance of Po-BW zones is significantly affected by the depth of the crack, angular acceleration rate, anisotropy of bearings, and the orientation of the unbalance force vector with respect to the crack opening direction. The full spectrum analysis (FSA) is also employed and found to be an efficient tool for identifying the Po-BW zones of rotational speeds in the whirl response.
On Rigorous Model-Order Reduction of the Thermal and Oxygen Storage Dynamics of Three Way Catalytic Converters
Authors: Dettu Federico , Onori Simona
Published: September 2020

We present a reduced-order model (ROM) for the temperature and oxygen storage dynamics of three way catalysts (TWCs). The thermal and oxygen storage dynamics are described using a set of coupled, nonlinear partial differential equations (PDEs) developed and experimentally validated in previous research. Advancements in on-board diagnostic (OBD) design are moving in the direction of using physics-based models that would retain as much physical insights as possible. Retaining the one-dimensional (1D) evolution of the internal storage dynamics along the device length is key for the development of accurate emission control strategies. In this work, we adopt the numerical projection orthogonal approach combined with the analytical features of Galerkin reduction method to define a set of ordinary differential equations (ODEs) to describe the oxygen storage and temperature dynamics throughout the device life. Using experimental data collected over three TWC devices, each of different age, and under the excitation of different real drive cycles, we validate the model and quantify the relation between the number of reduced-order states versus model accuracy for devices both new and at different stages of life. The input dependent characteristics of the developed reduced-model model is also investigated using a power spectral density (PSD) analysis. Finally, we show that an initial tuning of the reduced model parameters for a fresh catalyst guarantees satisfactory modeling performance throughout the device life, regardless of the driving scenario.
Vibration and Event-Triggered Control for Flexible Nonlinear Three-Dimensional Euler–Bernoulli Beam System
Authors: Ji Ning , Liu Jinkun
Published: September 2020

In this study, we explore the event-triggered control of a flexible three-dimensional (3D) Euler–Bernoulli beam modeled by partial differential equations (PDEs). A novel event-triggered control strategy is developed, which can minimize the communication burden in the process of signal transmission. A larger threshold value can be selected when the control input signal value is large to limit the communication burden; a smaller threshold value can be selected when the control input signal value is close to zero in order to improve the control accuracy. The threshold is time-varying, which further preserves the system resources. The proposed control laws can realize both vibration and event-triggered control. All the system signals can be guaranteed as uniform ultimate bounds. The effectiveness of this approach is verified in a series of simulations.
Modeling and Dynamic Assignment of the Adaptive Buffer Spaces in Serial Production Lines
Authors: Huang Jing , Chang Qing , Arinez Jorge
Published: September 2020

In production systems, the buffer capacities have usually been assumed to be fixed during normal operations. Inspired by the observations from the real industrial operations, a novel concept of Adaptive Buffer Space (ABS) is proposed in this paper. The ABS is a type of equipment, such as movable racks or mobile robots with racks, which can be used to provide extra storage space for a production line to temporarily increase certain buffers’ capacities in a real-time fashion. A good strategy to assign and reassign the ABS can significantly improve real-time production throughput. In order to model the production systems with changing buffer capacities, a data-driven model is developed to incorporate the impact of buffer capacity variation in system dynamics. Based on the model, a real-time ABS assignment strategy is developed by analyzing real-time buffer levels and machine status. The strategy is demonstrated to be effective in improving the system throughput. An approximate dynamic programming algorithm, referred to as ABS-ADP, is developed to obtain the optimal ABS assignment policy based on the strategy. Traditional ADP algorithms often initialize the state values with zeros or random numbers. In this paper, a knowledge-guided value function initialization method is proposed in ABS-ADP algorithm to expedite the convergence, which saves up to 80% computation time in the case study.
Mechanical and Corrosion Assessment of Friction Self-Piercing Rivet Joint of Carbon Fiber-Reinforced Polymer and Magnesium Alloy AZ31B
Authors: Lim Yong Chae , Chen Jian , Jun Jiheon , Leonard Donovan N. , Brady Michael P. , Warren Charles David , Feng Zhili
Published: September 2020

In the present work, thermoset carbon fiber–reinforced polymer (CFRP) was spot joined to magnesium alloy AZ31B by a friction self-piercing riveting (F-SPR) process. Lap shear tensile and cross-tension testing were used to evaluate the mechanical joint performance. An average lap shear tensile load of 5.18 kN was achieved, while an average of 2.81 kN was found from cross-tension testing. All F-SPR samples showed a pullout of AZ31B after mechanical testing, indicating good mechanical interlocking between the steel rivet and AZ31B. Corrosion potential was measured for each material to establish the galvanic corrosion characteristics. As expected, AZ31B was found to be the most active, while thermoset CFRP was the most noble. The steel rivet fell between the AZ31B (active) and the thermoset CFRP (noble). Salt fog corrosion testing (ASTM B-117) was performed to evaluate the corrosion performance of the uncoated F-SPR joint. With up to 200 h of exposure, the post-corroded F-SPR joint integrity retained 81.2% of the pre-exposure F-SPR joint strength with AZ31B pullout failure mode. From cross-sectional analysis of the F-SPR joint, extensive corrosion of AZ31B was observed at the joint and other exposure areas. However, steel rivet was not significantly corroded due to sacrificial anode effect by which AZ31B corroded first in the galvanic couple.
Experimental Investigation of Lubrication Regimes of a Water-Lubricated Bearing in the Propulsion Train of a Marine Vessel
Authors: Avishai Dov , Morel Groper
Published: September 2020

Sliding bearings, operating in a full hydrodynamic lubrication regime, exhibit a low friction coefficient and extended life. In recent years, with the increase in environmental awareness and pollution prevention, attention is being directed to oil spills, which pollute the environment. This is extremely prominent in ships and submarines whose propeller shafts are typically supported by oil-lubricated sliding bearings. To reduce pollution risk and also to obtain a simpler and low-cost maintenance system, the propeller shafts of numerous modern marine vessels are supported by water-lubricated bearings. An experimental investigation into the lubrication regime of a water-lubricated bearing in the propulsion train of a naval vessel is presented. A test rig was designed and built to allow testing of a scaled water-lubricated composite bearing supporting a naval vessel propeller shaft. Experimental results quantifying the effect of the rotational speed on the operating eccentricity, the friction coefficient, and the bearing’s lubrication regimes are presented. The experimentally obtained results are compared with an elastohydrodynamic lubrication (EHL) model solved by employing comsol multiphysics modeling software, and the differences are addressed. Finally, conclusions that may assist in better understanding the operation profile of the bearing and thus improving the vessel’s operability are presented.
Optimal Design of Maxwell-Viscous Coulomb Air Damper With a Modified Fixed Point Theory
Authors: Wong Wai On , Wong Chun Nam
Published: September 2020

Air damper dynamic vibration absorber (DVA) is modeled using Maxwell transformed element and coulomb element. This damper serves to minimize vibration at resonant and operation of constant speed machine. Its stiffness and damping factor are transformed from Maxwell to Voigt arrangement. Meanwhile, viscous equivalent Coulomb damping is expressed by absolute relative motion. System transmissibility contours are plotted by min–max approach. Its optimal parameters are determined using this approach. Contour operation minimization is obtained from minimum system transmissibility. Moreover, exact solution of fixed points and optimal natural frequency ratio are obtained by a modified fixed point theory. Optimal design curve is derived by Coulomb damping derivative and maximum condition. Operational vibration level is minimized by 7% at the operation minimization using minimum condition. On the experimental side, test platform of the air damper is constructed using linear slide block system. Computational model of the air damper is established by its physical details and experimental data. Linear relationship is obtained between viscous and Coulomb damping angles. Modified fixed points are validated by frequency response function resonant peaks. Experimental vibration level is minimized by 5%, which being close to the minimization result. The model is validated within 5% accuracy by its optimal experimental curve.
Damping Mechanisms in Cable-Harnessed Structures for Space Applications: Experimental Validation
Authors: Agrawal Pranav , Salehian Armaghan
Published: September 2020

In this technical brief, the experimental study and model validations for the damping mechanisms of cable-harnessed beam structures are presented. The structure consists of cables wrapped around a host beam in a periodic zigzag pattern. A special case of cable attached along the beam length over its centerline is also considered. First, material damping in the cables is characterized using dynamic tests and the relevant cable damping factors are calculated for both the Kelvin–Voigt and hysteretic damping models. Experimental modal testing is then performed on the fabricated cable-harnessed beams to obtain the frequency response functions (FRFs). Finally, the experimental FRFs are compared with the damped analytical models. The test and model results are shown to be in very good agreements in predicting the structural damping induced by the cables.
A Floquet-Based Analysis of Parametric Excitation Through the Damping Coefficient
Authors: Afzali Fatemeh , Acar Gizem D. , Feeny Brian F.
Published: September 2020

The Floquet theory has been classically used to study the stability characteristics of linear dynamic systems with periodic coefficients and is commonly applied to Mathieu’s equation, which has parametric stiffness. The focus of this article is to study the response characteristics of a linear oscillator for which the damping coefficient varies periodically in time. The Floquet theory is used to determine the effects of mean plus cyclic damping on the Floquet multipliers. An approximate Floquet solution, which includes an exponential part and a periodic part that is represented by a truncated Fourier series, is then applied to the oscillator. Based on the periodic part, the harmonic balance method is used to obtain the Fourier coefficients and Floquet exponents, which are then used to generate the response to the initial conditions, the boundaries of instability, and the characteristics of the free response solution of the system. The coexistence phenomenon, in which the instability wedges disappear and the transition curves overlap, is recovered by this approach, and its features and robustness are examined.
Laccase Affects the Rate of Cryptococcus neoformans Nonlytic Exocytosis from Macrophages
Authors: Frazão Stefânia de Oliveira , Sousa Herdson Renney de , Silva Lenise Gonçalves da , Folha Jéssica dos Santos , Gorgonha Kaio César de Melo , Oliveira Getúlio Pereira de , Felipe Maria Sueli Soares , Silva-Pereira Ildinete , Casadevall Arturo , Nicola André Moraes , Albuquerque Patrícia
Published: September 2020

Cryptococcus neoformans
is a yeast that causes severe disease, primarily in immunosuppressed people. It has many attributes that allow it to survive and cause disease, such as a polysaccharide capsule and the dark pigment melanin produced by the laccase enzyme. Upon infection, the yeast is ingested by cells called macrophages, whose function is to kill them. Instead, these fungal cells can exit from macrophages in a process called nonlytic exocytosis. We know that this process is controlled by both host and fungal factors, only some of which are known. As part of an ongoing study, we observed that
C. neoformans
isolates that produce melanin faster are more-frequent targets of nonlytic exocytosis. Further experiments showed that this is probably due to higher production of laccase, because fungi lacking this enzyme are nonlytically exocytosed less often. This shows that laccase is an important signal/regulator of nonlytic exocytosis of
C. neoformans
from macrophages.
Integrated Metabolic Modeling, Culturing, and Transcriptomics Explain Enhanced Virulence of Vibrio cholerae during Coinfection with Enterotoxigenic Escherichia coli
Authors: Abdel-Haleem Alyaa M. , Ravikumar Vaishnavi , Ji Boyang , Mineta Katsuhiko , Gao Xin , Nielsen Jens , Gojobori Takashi , Mijakovic Ivan
Published: September 2020

Most studies proposing new strategies to manage and treat infections have been largely focused on identifying druggable targets that can inhibit a pathogen's growth when it is the single cause of infection.
In vivo
, however, infections can be caused by multiple species. This is important to take into account when attempting to develop or use current antibacterials since their efficacy can change significantly between single infections and coinfections. In this study, we used genome-scale metabolic models (GEMs) to interrogate the growth capabilities of
Vibrio cholerae
in single infections and coinfections with enterotoxigenic
E. coli
(ETEC), which cooccur in a large fraction of diarrheagenic patients. Coinfection model predictions showed that
V. cholerae
growth capabilities are enhanced in the presence of ETEC relative to
V. cholerae
single infection, through cross-fed metabolites made available to
V. cholerae
by ETEC.
In vitro
, cocultures of the two enteric pathogens further confirmed model predictions showing an increased growth of
V. cholerae
in coculture relative to
V. cholerae
single cultures while ETEC growth was suppressed. Dual RNAseq analysis of the cocultures also confirmed that the transcriptome of
V. cholerae
was distinct during coinfection compared to single-infection scenarios where processes related to metabolism were significantly perturbed. Further,
in silico
gene-knockout simulations uncovered discrepancies in gene essentiality for
V. cholerae
growth between single infections and coinfections. Integrative model-guided analysis thus identified druggable targets that would be critical for
V. cholerae
growth in both single infections and coinfections; thus, designing inhibitors against those targets would provide a broader spectrum of coverage against cholera infections.