bluuebunny/crossref_metadata_2025 huggingface dataset:
Loquacious Modulates Flaviviral RNA Replication in Mosquito Cells
Authors: Shivaprasad Shwetha , Weng Kuo-Feng , Ooi Yaw Shin , Belk Julia , Carette Jan E. , Flynn Ryan , Sarnow Peter
Published: December 2021

Arthropod-borne viruses infect both mosquito and mammalian hosts. While much is known about virus-host interactions that modulate viral gene expression in their mammalian host, much less is known about the interactions that involve inhibition, subversion or avoidance strategies in the mosquito host. A novel RNA-Protein interaction detection assay was used to detect proteins that directly or indirectly bind to dengue viral genomes in infected mosquito cells. Membrane-associated mosquito proteins SEC61A1 and Loquacious (Loqs) were found to be in complex with the viral RNA. Depletion analysis demonstrated that both SEC61A1 and Loqs have pro-viral functions in the dengue viral infectious cycle. Co-localization and pull-down assays showed that Loqs interacts with viral protein NS3 and both full-length and subgenomic viral RNAs. While Loqs coats the entire positive-stranded viral RNA, it binds selectively to the 3’ end of the negative-strand of the viral genome. In-depth analyses showed that the absence of Loqs did not affect translation or turnover of the viral RNA but modulated viral replication. Loqs also displayed pro-viral functions for several flaviviruses in infected mosquito cells, suggesting a conserved role for Loqs in flavivirus-infected mosquito cells.

Author Summary

There is a wealth of information that dictates virus-host interactions in flavivirus-infected mammalian cells, yet there is only sparse information on the mechanisms that modulate viral gene expression in the mosquito host. Using a novel RNA-protein detection assay, the interactions of SEC61A1 and Loqs with the dengue viral genome were found to have proviral functions in infected mosquito cells. In particular, Loqs forms complexes with the positive-strand of the viral RNA and the very 3’ end of the negative-strand viral RNA. Further analyses showed that Loqs modulates viral RNA replication of dengue virus and gene amplification of several other flaviviral genomes. These findings argue that Loqs is an essential proviral host factor in mosquitos.
An unusual trafficking domain in MSRP6 defines a complex needed for Maurer’s clefts anchoring and maintenance inP. falciparuminfected red blood cells
Authors: Blancke Soares Alexandra , Stäcker Jan , Schwald Svenja , Hoijmakers Wieteke , Metwally Nahla Galal , Cronshagen Jakob , Schoeler Hanno , Flemming Sven , Höhn Katharina , Fröhlke Ulrike , Mesén-Ramírez Paolo , Bergmann Bärbel , Khosh-Naucke Melissa , Bruchhaus Iris , Bártfai Richárd , Spielmann Tobias
Published: December 2021

Intracellular malaria blood stage parasites remodel their host cell, a process essential for parasite survival and a cause of pathology in malaria infections. Host cell remodeling depends on the export of different classes of exported parasite proteins into the infected red blood cell (RBC). Here we show that members of a recently discovered group of difficult to predict exported proteins harbor an N-terminal export domain, similar to other classes of exported proteins, indicating that this is a common theme among all classes of exported proteins. For one such protein, MSRP6 (MSP-7 related protein 6), we identified a second, untypical export-mediating domain that corresponded to its MSP7-like region. In addition to its function in export, this domain also mediated attachment to the Maurer’s clefts, prominent parasite-induced structures in the host cell where MSRP6 is located. Using BioID with the Maurer’s clefts attachment domain of MSRP6 to identify interactors and compartment neighbors in live parasites we discovered a novel complex of proteins at the Maurer’s clefts. We show that this complex is necessary for the anchoring and maintaining the structural integrity of the Maurer’s clefts. The Maurer’s clefts are believed to be involved in the transport of the major virulence factor PfEMP1 to the host cell surface where it mediates cytoadherence of infected RBCs to endothelial cells, a main reason for the importance of host cell modifications for parasite virulence in the human host. Taking advantage of MSRP6 complex mutants and IT4 parasites that we modified to express only one specific PfEMP1 we find that abolishing Maurer’s clefts anchoring was neither needed for PfEMP1 transport to the host cell surface nor for cytoadherence. Altogether, this work reveals parasite proteins involved in Maurer’s clefts anchoring and maintenance and unexpectedly finds that these functions seem to be dispensable for virulence factor transport and surface display.
DExCon, DExogron, LUXon: on-demand expression control of endogenous genes reveals differential dynamics of Rab11 family members
Authors: Gemperle Jakub , Harrison Thomas , Flett Chloe , Adamson Antony , Caswell Patrick
Published: December 2021

CRISPR technology has made generation of gene knockouts widely achievable in cells. However, once inactivated, their reactivation remains difficult, especially in diploid cells. Here, we present DExCon (Doxycycline-mediated endogenous gene Expression Control), DExogron (DExCon combined with auxin-mediated targeted protein degradation) and LUXon (light responsive DExCon), approaches which combine one-step CRISPR-Cas9 mediated targeted knock-in of fluorescent proteins with an advanced Tet-inducible TRE3GS promoter. These approaches combine blockade of active gene transcription with the ability to reactivate transcription on demand, including activation of silenced genes. Systematic control can be exerted using doxycycline or spatiotemporally by light, and we demonstrate functional knockout/rescue in the closely related Rab11 family of vesicle trafficking regulators. Fluorescent protein knock-in results in bright signals compatible with low-light live microscopy from monoallelic modification, the potential to simultaneously image different alleles of the same gene and bypasses the need to work with clones. Protein levels are easily tunable to correspond with endogenous expression through cell sorting (DExCon), timing of light illumination (LUXon) or by exposing cells to different levels of auxin (DExogron). Furthermore, our approach allowed us to quantify previously unforeseen differences in vesicle dynamics, expression kinetics and protein stability among highly similar endogenous Rab11 family members and their colocalization in triple knock-in cells.

GRAPHICAL ABSTRACT

IN BRIEF

We describe development of DExCon, LUXon and DExogron approaches, where a single CRIPR/Cas9-mediated gene editing event can block endogenous gene expression, with the ability to reactivate expression encoded such that even silent genes can be expressed. Expression can be controlled systematically using doxycycline, or spatiotemporally by light, allowing fluorescent tagging of endogenous proteins and quantification of expression kinetics, protein dynamics and stability for highly similar genes such as members of the Rab11 family.
Metformin abrogates pathological TNF-α-producing B cells through mTOR-dependent metabolic reprogramming in polycystic ovary syndrome
Authors: Xiao Na , Wang Jie , Wang Ting , Xiong Xingliang , Zhou Junyi , Su Xian , Peng Jing , Yang Chao , Li Xiaofeng , Lin Ge , Lu Guangxiu , Gong Fei , Cheng Lamei
Published: December 2021

B cells contribute to the pathogenesis of polycystic ovary syndrome (PCOS). Clinically, metformin is used to treat PCOS, but it is unclear whether metformin exerts its therapeutic effect by regulating B cells. Here, we showed that the expression level of TNF-α in peripheral blood B cells from PCOS patient was increased. Metformin used in vitro and in vivo was able to reduce the production of TNF-α in B cells from PCOS patient. Administration of metformin improved mouse PCOS phenotypes induced by dehydroepiandrosterone (DHEA) and also inhibited TNF-α expression in splenic B cells. Further, metformin induced metabolic reprogramming of B cells in PCOS patients, including the alteration in mitochondrial morphology, the decrease in mitochondrial membrane potential, ROS production and glucose uptake. In DHEA-induced mouse PCOS model, metformin altered metabolic intermediates in splenic B cells. Moreover, the inhibition of TNF-α expression and metabolic reprogramming in B cells of PCOS patients and mouse model by metformin were associated with decreased mTOR phosphorylation. Together, TNF-α-producing B cells are involved in the pathogenesis of PCOS, and metformin inhibits mTOR phosphorylation and affects metabolic reprogramming, thereby inhibiting TNF-α expression in B cells, which may be a new mechanism of metformin in the treatment of PCOS.
High Throughput Characterization of V(D)J Recombination Signal Sequences Redefines the Consensus Sequence
Authors: Hoolehan Walker , Harris Justin C. , Byrum Jennifer N. , Rodgers Karla K.
Published: December 2021

In the adaptive immune system, V(D)J recombination initiates the production of a diverse antigen receptor repertoire in developing B and T cells. Recombination activating proteins, RAG1 and RAG2 (RAG1/2), catalyze V(D)J recombination by cleaving adjacent to recombination signal sequences (RSSs) that flank antigen receptor gene segments. Previous studies defined the consensus RSS as containing conserved heptamer and nonamer sequences separated by a less conserved 12 or 23 base-pair spacer sequence. However, many RSSs deviate from the consensus sequence. Here, we developed a cell-based, massively parallel V(D)J recombination assay to evaluate RAG1/2 activity on thousands of RSSs. We focused our study on the RSS heptamer and adjoining spacer region, as this region undergoes extensive conformational changes during RAG-mediated DNA cleavage. While the consensus heptamer sequence (CACAGTG) was marginally preferred, RAG1/2 was highly active on a wide range of non-consensus sequences. RAG1/2 generally preferred select purine/pyrimidine motifs that may accommodate heptamer unwinding in the RAG1/2 active site. Our results suggest RAG1/2 specificity for RSS heptamers is primarily dictated by DNA structural features dependent on purine/pyrimidine pattern, and to a lesser extent, RAG:RSS base-specific interactions. Further investigation of RAG1/2 specificity using this new approach will help elucidate the genetic instructions guiding V(D)J recombination.

Summary Statement

Partially conserved recombination signal sequences (RSSs) govern antigen receptor gene assembly during V(D)J recombination. Here, a massively parallel analysis of randomized RSSs reveals key attributes that allow DNA sequence diversity in the RAG1/2 active site and that contribute to the differential utilization of RSSs in endogenous V(D)J recombination. Overall, these results will assist identification of RAG1/2 off-target sites, which can drive leukemia cell transformation, as well as characterization of bona fide RSSs used to generate antigen receptor diversity.
Modelling of filamentous phage-induced antibiotic tolerance of P.aeruginosa
Authors: van Rossem Maria , Wilks Sandra , Kaczmarek Malgosia , Secor Patrick R. , D’Alessandro Giampaolo
Published: December 2021

Filamentous molecules tend to spontaneously assemble into liquid crystalline droplets with a tactoid morphology in the environments with the high concentration on non-adsorbing molecules. Tactoids of filamentous Pf bacteriophage, such as those produced by Pseudomonas aeruginosa, have been linked with increased antibiotic tolerance. We modelled this system and show that tactoids, composed of filamentous Pf virions, can lead to antibiotic tolerance by acting as an adsorptive diffusion barrier. The continuum model, reminiscent of descriptions of reactive diffusion in porous media, has been solved numerically and good agreement was found with the analytical results, obtained using a homogenisation approach. We find that the formation of tactoids significantly increases antibiotic diffusion times leading to stronger antibiotic resistance.
Methylation pattern of polymorphically imprinted nc886 is not conserved across mammalia
Authors: Kostiniuk Daria , Tamminen Hely , Mishra Pashupati P. , Marttila Saara , Raitoharju Emma
Published: December 2021

Background

In humans, the nc886 locus is a polymorphically imprinted metastable epiallele. Periconceptional conditions have an effect on the methylation status of nc886, and further, this methylation status is associated with health outcomes in later life, in line with the Developmental Origins of Health and Disease (DOHaD) hypothesis. Animal models would offer opportunities to study the associations between periconceptional conditions, nc886 methylation status and metabolic phenotypes further. Thus, we set out to investigate the methylation pattern of the nc886 locus in non-human mammals.

Data

We obtained DNA methylation data from the data repository GEO for mammals, whose nc886 gene included all three major parts of nc886 and had sequency similarity of over 80% with the human nc886. Our final sample set consisted of DNA methylation data from humans, chimpanzees, bonobos, gorillas, orangutangs, baboons, macaques, vervets, marmosets and guinea pigs.

Results

In human data sets the methylation pattern of nc886 locus followed the expected bimodal distribution, indicative of polymorphic imprinting. In great apes, we identified a unimodal DNA methylation pattern with 50% methylation level in all individuals and in all subspecies. In Old World monkeys, the between individual variation was greater and methylation on average was close to 60%. In guinea pigs the region around the nc886 homologue was non-methylated. Results obtained from the sequence comparison of the CTCF binding sites flanking the nc886 gene support the results on the DNA methylation data.

Conclusions

Our results indicate that unlike in humans, nc886 is not a polymorphically imprinted metastable epiallele in non-human primates or in guinea pigs, thus implying that animal models are not applicable for nc886 research. The obtained data suggests that the nc886 region may be classically imprinted in great apes, and potentially also in Old World monkeys, but not in guinea pigs.
What can cold-induced transcriptomes of Arctic Brassicaceae tell us about the evolution of cold tolerance?
Authors: Birkeland Siri , Slotte Tanja , Brysting Anne K. , Gustafsson A. Lovisa S. , Hvidsten Torgeir R. , Brochmann Christian , Nowak Michael D.
Published: December 2021

Little is known about the evolution of cold tolerance in polar plant species and how they differ from their temperate relatives. To gain insight into their biology and the evolution of cold tolerance, we compared the molecular basis of cold response in three Arctic Brassicaceae species.

We conducted a comparative time series experiment to examine transcriptional responses to low temperature. RNA was sampled at 22 °C, and after 3h, 6h, and 24h at 2 °C. We then identified sets of genes that were differentially expressed in response to cold and compared them between species, as well as to published data from the temperate Arabidopsis thaliana.

Most differentially expressed genes were species-specific, but a significant portion of the cold response was also shared among species. Among thousands of differentially expressed genes, ∼200 were shared among the three Arctic species and A. thaliana, while ∼100 were exclusively shared among the three Arctic species.

Our results show that cold response differs markedly between Arctic Brassicaceae species, but likely builds on a conserved basis found across the family. They also confirm that highly polygenic traits such as cold tolerance may show little repeatability in their patterns of adaptation.
Large genetic divergence underpins cryptic local adaptation across ecological and evolutionary gradients
Authors: Sparks Morgan M. , Kraft Joshua C. , Subida Blackstone Kliffi M. , McNickle Gordon G. , Christie Mark R.
Published: December 2021

Environmentally covarying local adaptation is a form of cryptic local adaptation in which the covariance of the genetic and environmental effects on a phenotype obscures the divergence between locally adapted genotypes. Here, we systematically document the magnitude and drivers of the genetic effect (VG) for two forms of environmentally covarying local adaptation: counter- and cogradient variation. Using a hierarchical Bayesian meta-analysis, we calculated the overall effect size of VG as 1.05 and 2.13 for populations exhibiting countergradient or cogradient variation, respectively. These results indicate that the genetic contribution to phenotypic variation represents a 1.05 to 2.13 standard deviation change in trait value between the most disparate populations depending on if populations are expressing counter- or cogradient variation. We also found that while there was substantial variance among abiotic and biotic covariates, the covariates with the largest mean effects were temperature (2.41) and gamete size (2.81). Our results demonstrate the pervasiveness and large genetic effects underlying environmentally covarying local adaptation in wild populations and highlights the importance of accounting for these effects in future studies.
Structure-based discovery of small molecule inhibitors of the autocatalytic proliferation of α-synuclein aggregates
Authors: Chia Sean , Brotzakis Z. Faidon , Horne Robert I. , Possenti Andrea , Mannini Benedetta , Cataldi Rodrigo , Nowinska Magdalena , Staats Roxine , Linse Sara , Knowles Tuomas P. J. , Habchi Johnny , Vendruscolo Michele
Published: December 2021

The presence of amyloid fibrils of α-synuclein is closely associated with Parkinson’s disease and related synucleinopathies. It is still very challenging, however, to systematically discover small molecules that prevent the formation of these aberrant aggregates. Here, we describe a structure-based approach to identify small molecules that specifically inhibit the surface-catalyzed secondary nucleation step in the aggregation of α-synuclein by binding to the surface of the amyloid fibrils. The resulting small molecules are screened using a combination of kinetic and thermodynamic assays for their ability to bind α-synuclein fibrils and prevent the further generation of toxic oligomers. This study demonstrates that the combination of structure-based and kinetic-based drug discovery methods can lead to the identification of small molecules that selectively inhibit the autocatalytic proliferation of α-synuclein aggregates.
Mosquito excreta reveals circulation of West Nile virus and its underlying ecosystem
Authors: L’Ambert Grégory , Gendrot Mathieu , Briolant Sébastien , Nguyen Agnès , Pages Sylvain , Bosio Laurent , Palomo Vincent , Gomez Nicolas , Benoit Nicolas , Savini Hélène , Pradines Bruno , Durand Guillaume André , Leparc-Goffart Isabelle , Grard Gilda , Fontaine Albin
Published: December 2021

Emerging and endemic mosquito-borne viruses can be difficult to detect and monitor because they often cause asymptomatic infections in human or vertebrate animals or cause nonspecific febrile illness with a short recovery waiting period. Cases’ detection in vertebrate hosts can be complemented by entomological surveillance, but this method is not adapted to low infection rates in mosquito populations that typically occur in low or non-endemic areas. We identified West Nile Virus circulation in Camargue, a wetland area in South of France, using a cost effective innovative xenomonitoring method based on the molecular detection of virus in excreta from trapped mosquitoes. We also succeeded at identifying the mosquito community diversity dynamic on several sampling sites, together with the vertebrate hosts on which they fed prior to be captured using amplicon-based metagenomic on mosquito excreta without processing any mosquito. Mosquito excreta-based virus surveillance can be considered as a cost-effective and non-invasive strategy that offers the additional asset to reveal the ecological network underlying arbovirus circulation.
Barrier mitigation measures trigger the rapid recovery of genetic connectivity in five freshwater fish species
Authors: Prunier Jérôme G. , Loot Géraldine , Veyssiere Charlotte , Poulet Nicolas , Blanchet Simon
Published: December 2021

Rivers are heavily fragmented by man-made instream barriers such as dams and weirs. This hyper-fragmentation is a major threat to freshwater biodiversity and restoration policies are now adopted worldwide to mitigate these impacts. However, there is surprisingly little feedback on the efficiency of barrier mitigation measures in restoring riverine connectivity, notably for non-migratory fish species. Here, we implemented a “before-after genetic monitoring” of the restoration of 11 weirs in France using a dedicated genetic index of fragmentation (the FINDEX), with a focus on five fish species from two genera. We found that most obstacles actually had a significant impact on connectivity before restoration, especially the highest and steepest ones, with an overall barrier effect of about 51% of the maximal theoretical impact. Most importantly, we demonstrated for the first time that mitigation measures such as dam removal or fish pass creation significantly and rapidly improved connectivity, with –for some barriers-a complete recovery of the genetic connectivity in less than twelve months. Our study provides a unique and strong proof-of-concept that barrier removal is an efficient strategy to restore riverine connectivity and that molecular tools can provide accurate measures of restoration efficiency within a few months.

Graphical Abstract
Biofilm Growth Under Elastic Confinement
Authors: Fortune George T. , Oliveira Nuno M. , Goldstein Raymond E.
Published: December 2021

Bacteria often form surface-bound communities, embedded in a self-produced extracellular matrix, called biofilms. Quantitative studies of their growth have typically focused on unconfined expansion above solid or semi-solid surfaces, leading to exponential radial growth. This geometry does not accurately reflect the natural or biomedical contexts in which biofilms grow in confined spaces. Here we consider one of the simplest confined geometries: a biofilm growing laterally in the space between a solid surface and an overlying elastic sheet. A poroelastic framework is utilised to derive the radial growth rate of the biofilm; it reveals an additional self-similar expansion regime, governed by the stiffness of the matrix, leading to a finite maximum radius, consistent with our experimental observations of growing Bacillus subtilis biofilms confined by PDMS.
Germline mosaicism of a missense variant in KCNC2 in a multiplex family with autism and epilepsy
Authors: Mehinovic Elvisa , Gray Teddi , Campbell Meghan , Ekholm Jenny , Wenger Aaron , Rowell William , Grudo Ari , Grimwood Jane , Korlach Jonas , Gurnett Christina , Constantino John N. , Turner Tychele N.
Published: December 2021

Currently, protein-coding de novo variants and large copy number variants have been identified as important for ∼30% of individuals with autism. One approach to identify relevant variation in individuals who lack these types of events is by utilizing newer genomic technologies. In this study, highly accurate PacBio HiFi long-read sequencing was applied to a family with autism, treatment-refractory epilepsy, cognitive impairment, and mild dysmorphic features (two affected female full siblings, parents, and one unaffected sibling) with no known clinical variant. From our long-read sequencing data, a de novo missense variant in the KCNC2 gene (encodes Kv3.2 protein) was identified in both affected children. This variant was phased to the paternal chromosome of origin and is likely a germline mosaic. In silico assessment of the variant revealed it was in the top 0.05% of all conserved bases in the genome, and was predicted damaging by Polyphen2, MutationTaster, and SIFT. It was not present in any controls from public genome databases nor in a joint-call set we generated across 49 individuals with publicly available PacBio HiFi data. This specific missense mutation (Val473Ala) has been shown in both an ortholog and paralog of Kv3.2 to accelerate current decay, shift the voltage dependence of activation, and prevent the channel from entering a long-lasting open state. Seven additional missense mutations have been identified in other individuals with neurodevelopmental disorders (p = 1.03 × 10−5). KCNC2 is most highly expressed in the brain; in particular, in the thalamus and is enriched in GABAergic neurons. Long-read sequencing was useful in discovering the relevant variant in this family with autism that had remained a mystery for several years and will potentially have great benefits in the clinic once it is widely available.
A hybrid ant colony–particle swarm optimization method (ACOPSO) for aerospace propulsion systems
Authors: Piskin Altug , Baklacioglu Tolga , Turan Onder
Published: December 2021

Purpose

The purpose of this paper is to introduce a hybrid, metaheuristic, multimodal and multi-objective optimization tool that is needed for aerospace propulsion engineering problems.

Design/methodology/approach

Multi-objective hybrid optimization code is integrated with various benchmark and test functions that are selected suitable to the difficulty level of the aero propulsion performance problems.

Findings

Ant colony and particle swarm optimization (ACOPSO) has performed satisfactorily with benchmark problems.

Research limitations/implications

ACOPSO is able to solve multi-objective and multimodal problems. Because every optimization problem has specific features, it is necessary to search their general behavior using other algorithms.

Practical implications

In addition to the optimization solving, ACOPSO enables an alternative methodology for turbine engine performance calculations by using generic components maps. The user is flexible for searching various effects of component designs along with the compressor and turbine maps.

Originality/value

A hybrid optimization code that has not been used before is introduced. It is targeted use is propulsion systems optimization and design such as Turboshaft or turbofan by preparing the necessary engine functions. A number of input parameters and objective functions can be modified accordingly.
Financial statement analysis: a review and current issues
Authors: Jackson Andrew B.
Published: December 2021

Purpose

The literature on financial statement analysis attempts to improve fundamental analysis and to identify market inefficiencies with respect to financial statement information.

Design/methodology/approach

In this paper, the author reviews the extant research on financial statement analysis.

Findings

The author then provides some preliminary evidence using Chinese data and offer suggestions for future research, with a focus on utilising unique features of the Chinese business environment as motivation.

Originality/value

The author notes that there has been no work that the author could locate specifically on Chinese FSA research. The unique business environment in China, relative to the US where the vast majority of this work has been conducted, should motivate any studies, especially given the author documents the robust finding in terms of the mean reversion in profitability.
Grey wolf optimizer algorithm for the performance predetermination of variable speed self-excited induction generators
Authors: R. Essaki Raj , Sridhar Sundaramoorthy
Published: December 2021

Purpose

This paper aims to apply grey wolf optimizer (GWO) algorithm for steady state analysis of self-excited induction generators (SEIGs) supplying isolated loads.

Design/methodology/approach

Taking the equivalent circuit of SEIG, the impedances representing the stator, rotor and the connected load are reduced to a single loop impedance in terms of the unknown frequency, magnetizing reactance and core loss resistance for the given rotor speed. This loop impedance is taken as the objective function and minimized using GWO to solve for the unknown parameters. By including the value of the desired voltage as a constraint, the formulated objective function is also extended for estimating the required excitation capacitance.

Findings

The experimental results obtained on a three phase 415 V, 3.5 kW SEIG and the corresponding predetermined performance characteristics agree closely, thereby validating the proposed GWO method. Moreover, a comparative study of GWO with genetic algorithm and particle swarm optimization techniques reveals that GWO exhibits much quicker convergence of the objective function.

Originality/value

The important contributions of this paper are as follows: for the first time, GWO has been introduced for the SEIG performance predetermination and computation of the excitation capacitance for attaining the desired terminal voltage for the given load and speed; the predicted performance accuracy is improved by considering the variable core loss of the SEIG; and GWO does not require derivations of lengthy equations for calculating the SEIG performance.
Performance comparison between Islamic and conventional stocks: evidence from Pakistan's equity market
Authors: Jabeen Munazza , Kausar Saba
Published: December 2021

Purpose

This paper aims to examine the performance of Islamic and conventional stocks listed at the Pakistan Stock Exchange by using both parametric and non-parametric approaches. The motivation is to do risk-return analysis of Islamic stock prices and conventional stock prices.

Design/methodology/approach

It uses various measures of performance, e.g. Sharpe ratio, Treynor ratio, Jensen's alpha, beta, generalized auto-regressive conditional heteroskedasticity and stochastic dominance. Using the Karachi Meezan Index-30 (KMI-30) and the Karachi Stock Exchange Index-30 (KSE-30) as proxies for Islamic and conventional stock prices, respectively, it examines the performance of Islamic and conventional stocks. The daily data of KMI-30 and KSE-30, covering period from June 9, 2009 to June 20, 2020 are used.

Findings

The results show that the overall KMI-30 outperforms the KSE-30. The returns of the KMI-30 are greater than the KSE-30. However, the risk and volatility of the KMI-30 and KSE-30 are similar. Further, the KMI-30 has higher excess returns per unit of total risk than the KSE-30. But both indexes have similar excess returns per unit of systematic risk. Moreover, the KMI-30 returns have stochastically dominance over the KSE-30 returns. These results reveal that the Islamic index performs better than the conventional index.

Practical implications

The findings provide several practical implications in financial and investment decisions making by investors, managers and policymakers such as strategies for asset allocation and investment. Further, in risk management, it provides guidance for allocating portfolios and managing risk. The investment in Islamic stocks may mitigate potential risk within asset portfolios.

Originality/value

This research is unique in its approach to the analysis of the performance comparison of conventional and Islamic stock by using comprehensive parametric and non-parametric estimation techniques. Such research has not been undertaken in the Pakistan's equity market since.
A systematic review of innovation in family firms and future research agenda
Authors: Akram Manzoor Ul , Ghosh Koustab , Sharma Dheeraj
Published: December 2021

Purpose

In this paper, the authors have used a systematic literature review methodology of 147 journal articles published in peer-reviewed journals. The analysis includes studies based on country of origin, the periodic proliferation of studies and the methodological design of the studies. As an outcome of the review, the studies are classified on the innovation in family firms under four broad categories – innovation input, family governance mechanisms, innovation output and the external environment. Some fruitful avenues of research are outlined in this domain.

Design/methodology/approach

The literature on innovation in family firms – the most dominant and ubiquitous form of organization across the world – is gaining pace. The influence of family by way controlling ownership, management and governance on, and in interaction with business acts as a complex proposition that shapes the strategic decision-making in the family firm including innovation. The purpose of this paper, therefore, is to advance the understanding of innovation in family firms and provide a list of future research questions of theoretical and practical value.

Findings

Based on this review, the authors provide future research directions pertaining to innovation in emerging economy family firms, effect of the institutional environment of family firm innovation as well family firms' innovativeness in the wake of pro-market reforms, different classes of ownership in family firms and innovation, family firm goal heterogeneity and innovation, and family firm dynamic capabilities and innovation.

Originality/value

The review provides a comprehensive understanding, trends and future research directions in the domain of innovation in family firms.
Performance measurement and management. A literature review focussed on the role played by management theories with a deep dive into the industry 4.0 environment
Authors: Demartini Melissa , Taticchi Paolo
Published: December 2021

Purpose

The aim of this paper is to review the theoretical lenses used in performance measurement and management in a traditional and industry 4.0 environment and to contribute to understanding the current state of research in the field and its future development.

Design/methodology/approach

This paper performs a structured review of the existing performance measurement and management literature, with the objective to investigate the current state of research, looking at popular theories in more detail, as well as to propose possible avenues for future consideration for the field to develop further moving forward. Particularly, this paper focusses on and identifies (1) theoretical lenses that are dominating this field, (2) the role played by specific theories and the way different theories are used together and finally, (3) an in-depth dive into relevant theories for performance measurement and management applied in an industry 4.0 environment.

Findings

Key findings highlight the growing number of publications, leading authors and journals where research is published. The findings also include the identification and detailed analysis of the most popular theories leveraged by scholars also in reference to research methodologies. A thorough analysis of Industry 4.0 performance measurement and management is then carried out, as this is one of the identified emerging themes in the research field. Findings here include the identification of relevant research and the suggestion of significant theories that can help build this specific body of knowledge.

Originality/value

This research offers a key contribution by providing a powerful “theoretical toolkit” to researchers and practitioners working in performance measurement and management and industry 4.0 fields.
Corporate governance and firm value: a study on European financial institutions
Authors: Ben Fatma Hanen , Chouaibi Jamel
Published: December 2021

Purpose

The purpose of this paper is to examine the impact of the characteristics of two corporate governance mechanisms, namely, board of directors and ownership structure, on the firm value of European financial institutions.

Design/methodology/approach

Using the market-to-book ratio calculated by the Thomson Reuters Eikon ASSET4 database, this study measures the firm value of 111 financial institutions belonging to 12 European countries listed on the stock exchange during the period 2007–2019. Multivariate regression analysis on panel data is used to estimate the relationship between corporate governance attributes, such as board size, board independence, board gender diversity, ownership concentration and CEO ownership, and the firm value of European financial institutions.

Findings

The empirical results reveal that board gender diversity and CEO ownership are positively related to the firm value, whereas board size and ownership concentration are negatively related. Furthermore, the findings suggest that board independence is insignificantly correlated with the firm value. Regarding the control variables, the results show that financial institutions' size, age and legal system are significant factors in changing the firm value. Nevertheless, financial institutions' leverage and activity sector are not significantly correlated with their value.

Originality/value

This research contributes to the literature by providing the significant links between some corporate governance mechanisms and the firm value of companies from the financial industry, by addressing the information gap for this critical industry in the context of a developed market like Europe.
Study on the influence of radial stiffness on the nonlinear vibration of brake system
Authors: Yan Xiaoyu , Fan Chenglong , Wang Wei , Liu Xiaojun , Chen Bingsan
Published: December 2021

Purpose

A dynamic model of the brake system considering the tangential and radial motion of the pad, and the torsion and wobbling motion of the disk is established in this paper. The influence of radial stiffness on the brake system is investigated under different tribological conditions. This paper aims to prove that sufficient radial stiffness is indispensable in the design of the brake system with good tribological performance.

Design/methodology/approach

By using the lumped mass method, a dynamic model of the brake system is established. A Stribeck-type friction model is applied to this model to correlate the frictional velocity, pressure and friction force. The stability of pad vibration is analysed by analysis methods. A new stability evaluation parameter is proposed to study the influence of radial stiffness on stability of pad vibration in a certain friction coefficient brake pressure range.

Findings

The findings show that the tangential vibration of the pad transits from periodic motion to quasi-periodic motion under a low tangential stiffness. The influence of radial stiffness on motion stability is stronger under a low nominal brake radius. The stability of the brake system can be ensured when the brake radius and radial stiffness are sufficient.

Originality/value

The influence of tangential stiffness of pad on stability of the brake system has been researched for decades. The insufficiency of stiffness in radial direction may also generate certain levels of instabilities but has not been fully investigated by modelling approach. This paper reveals that this parameter is also strongly correlated to nonlinear vibration of the brake pad.
Barrier Lyapunov function-based robot control with an augmented neural network approximator
Authors: Zhang Zuguo , Wu Qingcong , Li Xiong , Liang Conghui
Published: December 2021

Purpose

Considering the complexity of dynamic and friction modeling, this paper aims to develop an adaptive trajectory tracking control scheme for robot manipulators in a universal unmodeled method, avoiding complicated modeling processes.

Design/methodology/approach

An augmented neural network (NN) constituted of radial basis function neural networks (RBFNNs) and additional sigmoid-jump activation function (SJF) neurons is introduced to approximate complicated dynamics of the system: the RBFNNs estimate the continuous dynamic term and SJF neurons handle the discontinuous friction torques. Moreover, the control algorithm is designed based on Barrier Lyapunov Function (BLF) to constrain output error.

Findings

Lyapunov stability analysis demonstrates the exponential stability of the closed-loop system and guarantees the tracking errors within predefined boundaries. The introduction of SJFs alleviates the limitation of RBFNNs on discontinuous function approximation. Owing to the fast learning speed of RBFNNs and jump response of SJFs, this modified NN approximator can reconstruct the system model accurately at a low compute cost, and thereby better tracking performance can be obtained. Experiments conducted on a manipulator verify the improvement and superiority of the proposed scheme in tracking performance and uncertainty compensation compared to a standard NN control scheme.

Originality/value

An enhanced NN approximator constituted of RBFNN and additional SJF neurons is presented which can compensate the continuous dynamic and discontinuous friction simultaneously. This control algorithm has potential usages in high-performance robots with unknown dynamic and variable friction. Furthermore, it is the first time to combine the augmented NN approximator with BLF. After more exact model compensation, a smaller tracking error is realized and a more stringent constraint of output error can be implemented. The proposed control scheme is applicable to some constraint occasion like an exoskeleton and surgical robot.
Constant force control for aluminum wheel hub grinding based on ESO + backstepping
Authors: Dai Shijie , Zhao Yufeng , Ji Wenbin , Mu Jiaheng , Hu Fengbao
Published: December 2021

Purpose

This paper aims to present a control method to realize the constant force grinding of automobile wheel hub.

Design/methodology/approach

A constant force control strategy combined by extended state observer (ESO) and backstepping control is proposed. ESO is used to estimate the total disturbance to improve the anti-interference and stability of the system and Backstepping control is used to improve the response speed of the system.

Findings

The simulation and grinding experimental results show that, compared with the proportional integral differential control and active disturbance rejection control, the designed controller can improve the dynamic response performance and anti-interference ability of the system and can quickly track the expected force and improve the grinding quality of the hub surface.

Originality/value

The main contribution of this paper lies in the proposed of a new constant force control strategy, which significantly improved the stability and precision of grinding force.
The role of organizational culture in normalizing paramedic exposure to violence
Authors: Mausz Justin , Johnston Mandy , Donnelly Elizabeth Anne
Published: December 2021

Purpose

Violence against paramedics is a complex – but underreported – problem. Extant research suggests organizational culture may play a role in sustaining cultural norms that downplay the significance and limit reporting. The purpose of this paper is to qualitatively explore paramedics’ experience with violence, with particular emphasis on understanding how organizational culture contributes to under-reporting.

Design/methodology/approach

The authors surveyed paramedics from a single, large, urban service in Ontario, Canada, asking participants to describe their experiences with violence, including whether – and why or why not – the incidents were reported. Within a constructivist epistemology, we used inductive thematic analysis with successive rounds of coding to identify and then define features of organizational culture that limit reporting.

Findings

A total of 196 (33% of eligible) paramedics completed the survey. Fully 98% of participants disclosed having experienced some form of violence; however, only a minority (40%) reported the incidents to management, or the police (21%). The authors defined a framework within which a lack of support from management, and consequences for offenders, implicitly positions the ability of paramedics to “brush off” violent encounters as an expected professional competency. Disclosing emotional or psychological distress in response to violent encounters invited questions as to whether the individual is personally suited to paramedic work.

Originality/value

While the extant research has indicated that underreporting is a problem, the findings shed light on why – a critical first step in addressing what has been described as a serious public health problem.
Quality determinates of rice price in open bag markets in Sub-Saharan Africa
Authors: Peterson-Wilhelm Bailey , Nalley Lawton , Durand-Morat Alvaro , Shew Aaron , Tsiboe Francis , Mulimbi Willy
Published: December 2021

Purpose

Weaknesses in the grades and standards system in low-income countries across Sub-Saharan Africa undermine the transparency of agricultural markets. In the Democratic Republic of the Congo (DRC), Ghana and Mozambique rice is predominately sold in open bags and if rice price does not reflect its quality, then inefficiencies may lead to consumer welfare losses. Importantly, it is possible that impoverished communities are priced out of the market due to inflated and inefficient prices. The objective of this study is to examine determinates of rice price by estimating the impact of selected rice quality attributes on rice prices in Democratic Republic of the Congo, Ghana and Mozambique.

Design/methodology/approach

We collected 363 rice samples from open air markets in Bukavu (DRC), Nampula (Mozambique) and across Ghana in 2019. Each rice sample was analyzed in a food science lab for the quality attributes: percentage of chalk and brokens, chalk impact, length and length-to-width ratio. We used multiple regression analysis to estimate if and to what extent quality attributes were the drivers of price.

Findings

Findings suggest that there are irregularities in the Ghanaian market for broken rice and that regardless of quality, imported rice is priced higher than domestic rice. In the DRC and Mozambique, our results indicate price is driven by length and length-to-width ratio in the former and length-to-width ratio in the latter.

Research limitations/implications

Rice samples were purchased from market vendors and thus consumer preferences for attributes were not revealed.

Originality/value

These results provide valuable insight to policymakers regarding the need for proper labeling and regulation of open bag rice sales in an effort to increase consumer welfare and improve food security.
Why are strangers trusted more during trade fairs? A literature review on the conceptual model of general trust formation
Authors: Jia Minjiang , Wan Chunlin
Published: December 2021

Purpose

Considering that low-level general trust may hinder communication, this study aims to detect the factors that can influence general trust between exhibitors and visitors during business-to-business trade fairs.

Design/methodology/approach

Based on a literature review and stakeholders’ behavior analysis, a conceptual model of general trust formation between exhibitors and visitors is proposed.

Findings

The preconditions of strangers’ general trust patterns mainly include their early experience regarding trust, institutional trust in the environment and trust propensity. Stakeholders’ treatment, trust transfer, on-site restraints, reward and punishment expansion and on-site personnel arrangement may facilitate the formation of general trust between exhibitors and visitors.

Research limitations/implications

This paper is a conceptual article that requires further investigation to verify the main factors that influence general trust and the impact of general trust on other trust components between exhibitors and visitors.

Practical implications

Organizers, exhibitors and visitors should pay attention to participants’ selection, supervision, self-discipline and personnel management before and during trade fairs. International and small-scale, especially new trade fairs in developed and developing countries, must consider additional measures to improve general trust.

Originality/value

The existing literature has not focused on general trust in the trade fair context. In this paper, research on network and relationship marketing is further deepened in terms of a specific trust type. The interactions between stakeholders before and during fair may promote general trust among participants than in other settings, which partially explains why trade fair (even other two-sided markets) can increase social capital.