bluuebunny/crossref_metadata_2025 huggingface dataset:
System Biology Modeling with Compositional Microbiome Data Reveals Personalized Gut Microbial Dynamics and Keystone Species
Authors: Li Chenhao , Tucker-Kellogg Lisa , Nagarajan Niranjan
Published: March 2018

A growing body of literature points to the important roles that different microbial communities play in diverse natural environments and the human body. The dynamics of these communities is driven by a range of microbial interactions from symbiosis to predator-prey relationships, the majority of which are poorly understood, making it hard to predict the response of the community to different perturbations. With the increasing availability of high-throughput sequencing based community composition data, it is now conceivable to directly learn models that explicitly define microbial interactions and explain community dynamics. The applicability of these approaches is however affected by several experimental limitations, particularly the compositional nature of sequencing data. We present a new computational approach (BEEM) that addresses this key limitation in the inference of generalised Lotka-Volterra models (gLVMs) by coupling biomass estimation and model inference in an expectation maximization like algorithm (BEEM). Surprisingly, BEEM outperforms state-of-the-art methods for inferring gLVMs, while simultaneously eliminating the need for additional experimental biomass data as input. BEEM’s application to previously inaccessible public datasets (due to the lack of biomass data) allowed us for the first time to analyse microbial communities in the human gut on a per individual basis, revealing personalised dynamics and keystone species.
PGP-UK: a research and citizen science hybrid project in support of personalized medicine
Authors:   PGP-UK Consortium, Beck Stephan , Berner Alison M , Bignell Graham , Bond Maggie , Callanan Martin J , Chervova Olga , Conde Lucia , Corpas Manuel , Ecker Simone , Elliott Hannah R , Fioramonti Silvana A , Flanagan Adrienne M , Gaentzsch Ricarda , Graham David , Gribbin Deirdre , Guerra-Assunção José Afonso , Hamoudi Rifat , Harding Vincent , Harrison Paul L , Herrero Javier , Hofmann Jana , Jones Erica , Khan Saif , Kaye Jane , Kerr Polly , Libertini Emanuele , McCormack Laura , Moghul Ismail , Pontikos Nikolas , Rajanayagam Sharmini , Rana Kirti , Semega-Janneh Momodou , Smith Colin P , Strom Louise , Umur Sevgi , Webster Amy P , Wint Karen , Wood John N
Published: March 2018

Molecular analyses such as whole-genome sequencing have become routine and are expected to be transformational for future healthcare and lifestyle decisions. Population-wide implementation of such analyses is, however, not without challenges, and multiple studies are ongoing to identify what these are and explore how they can be addressed. Defined as a research project, the Personal Genome Project UK (PGP-UK) is part of the global PGP network and focuses on open data sharing and citizen science to advance and accelerate personalized genomics and medicine. Here we report our findings on using an open consent recruitment protocol, active participant involvement, open access release of personal genome, methylome and transcriptome data and associated analyses, including 47 new variants predicted to affect gene function and innovative reports based on the analysis of genetic and epigenetic variants. For this pilot study, we recruited ten participants willing to actively engage as citizen scientists with the project. In addition, we introduce Genome Donation as a novel mechanism for openly sharing previously restricted data and discuss the first three donations received. Lastly, we present GenoME, a free, open-source educational app suitable for the lay public to allow exploration of personal genomes. Our findings demonstrate that citizen science-based approaches like PGP-UK have an important role to play in the public awareness, acceptance and implementation of genomics and personalized medicine.
Hampered motility promotes the evolution of wrinkly phenotype in Bacillus subtilis
Authors: Richter Anne , Hölscher Theresa , Pausch Patrick , Sehrt Tim , Brockhaus Franziska , Bange Gert , Kovács Ákos T.
Published: March 2018

Selection for a certain trait in microbes depends on the genetic background of the strain and the selection pressure of the environmental conditions acting on the cells. In contrast to the sessile state in the biofilm, various bacterial cells employ flagellum-dependent motility under planktonic conditions suggesting that the two phenotypes are mutually exclusive. However, flagellum dependent motility facilitates the prompt establishment of floating biofilms on the air-medium interface, called pellicles. Previously, pellicles of B. subtilis were shown to be preferably established by motile cells, causing a reduced fitness of non-motile derivatives in the presence of the wild type strain. Here, we show that lack of fully assembled flagella promotes the evolution of matrix overproducers that can be distinguished by the characteristic wrinkled colony morphotype. The wrinkly phenotype is associated with amino acid substitutions in the master repressor of biofilm-related genes, SinR. By analyzing one of the mutations, we show that it alters the tetramerization and DNA binding properties of SinR, allowing an increased expression of the operon responsible for exopolysaccharide production. Finally, we demonstrate that the wrinkly phenotype is advantageous when cells lack flagella, but not in the wild type background.

Graphical Abstract

Abbreviated Summary

During biofilm establishment at the air-liquid interface, Bacillus subtilis evolves matrix overproducers with a wrinkly colony phenotype (WS). This is caused by mutations in the regulator SinR which alter its dimerization and DNA interaction properties. The matrix overproducers appear mostly in a non-motile mutant where they possess a competitive advantage for biofilm formation, which is not present in the wild type background.
Ecological and evolutionary consequences of viral plasticity
Authors: Choua Melinda , Bonachela Juan A.
Published: March 2018

Viruses can infect any organism. Because viruses use the host machinery to replicate, their performance depends on the host physiological state. For bacteriophages, this host-viral performance link has been characterized empirically and with intracellular theories. Such theories are too detailed to be included in models that study host-phage interactions in the long term, which hinders our understanding of systems that range from pathogens infecting gut bacteria to marine phage shaping present and future oceans. Here, we combined data and models to study the short- and long-term consequences that host physiology has on bacteriophage performance. We compiled data showing the dependence of lytic-phage traits on host growth rate (viral phenotypic “plasticity”) to deduce simple expressions representing such plasticity. We included these expressions in a standard host-phage model, to understand how viral plasticity can break the expected evolutionary trade-off between infection time and viral offspring number. Furthermore, viral plasticity influences dramatically dynamic scenarios (e.g. sudden nutrient pulses or host starvation). We show that the effect of plasticity on offspring number, not generation time, drives the phage ecological and evolutionary dynamics. Standard models do not account for this plasticity, which handicaps their predictability in realistic environments. Our results highlight the importance of viral plasticity to unravel host-phage interactions, and the need of laboratory and field experiments to characterize viral plastic responses across systems.
A thermo-responsive plasmid for biconditional protein expression
Authors: Lermant Agathe , Magnanon Alicia , Silvain Alexandra , Lubrano Paul , Lhuissier Marie , Dury Camille , Follenfant Maryne , Guiot Zoe , Christien Gaëtan , Coudert Pauline , Arvor Antoine , Sportich Maxime , Vuillaume Gabrielle , Delettre Nicolas , Henry Julie , Lafon Eliott , Lhernould Thomas , Richard Fanny , Ismail Alexandre
Published: March 2018

Here we develop a temperature sensitive expression vector that allows the selective production of distinct proteins over different temperature ranges with a single plasmid. We use theE. colicold shock translational control system (the cspA 5’Untranslated Transcribed Region - UTR) to drive the expression of a desired protein below a certain temperature threshold, and the lambda phage pL/cI857 transcriptional repressor system to drive the expression of a different protein above a certain temperature threshold. In this developmental work we use the chromogenic reporter proteins amilCP (blue chromoprotein) and monomeric red fluorescent protein (mRFP) to assess the function of the thermo-sensitive regulatory sequences over the desired temperature ranges. Our results show temperature dependent response of the cold shock regulatory sequence. However, our sequence design for the heat shock regulatory sequence did not give the intended result. The integration of these two temperature sensitive elements into a single plasmid awaits the re-design of the heat shock sequence.
PRY-1/AXIN signaling regulates lipid metabolism inCaenorhabditis elegans
Authors: Ranawade Ayush , Mallick Avijit , Gupta Bhagwati P
Published: March 2018

The nematodeCaenorhabditis elegansis a leading animal model to study how signaling pathway components function in conserved biological processes. Here, we describe the role of an Axin family member,pry-1, in lipid metabolism. As a central component of the canonical Wnt signaling pathway,pry-1acts as a scaffold to multiprotein destruction complex that negatively regulates the expression of Wnt target genes. A genome-wide transcriptome profiling ofpry-1mutant revealed genes associated with aging and lipid metabolism such as vitellogenins (yolk lipoproteins), fatty acid desaturases, lipases, and fatty acid transporters. Consistent with this we found thatpry-1is crucial for the normal adult lifespan and maintenance of lipid levels. Knock-downs ofvitgenes inpry-1mutant background restored lipid levels, suggesting that Vitellogenins contribute to PRY-1 function in lipid metabolic processes. Additionally, lowered expression of desaturases and lipidomics analysis provided evidence that the fatty acid synthesis is reduced inpry-1mutants. In agreement with this an exogenous supply of oleic acid restored depleted lipids in somatic tissues of worms. Overall, our findings demonstrate that PRY-1/Axin signaling is essential for lipid metabolism and involves regulation of yolk proteins.
Low dose resveratrol promotes hypertrophy in wildtype skeletal muscle and reduces damage in skeletal muscle of exercised mdx mice
Authors: Woodman KG , Coles CA , Toulson SL , Knight M , McDonagh M , Lamandé SR , White JD
Published: March 2018

Duchenne muscular dystrophy (DMD) is a progressive and fatal neuromuscular disorder for which there is no treatment. Therapies to restore dystrophin deficiency are not ready for clinical use and long-term efficiency is yet to be established. Therefore, there is a need to develop alternative strategies to treat DMD. Resveratrol is a nutraceutical with anti-inflammatory properties and previous studies have shown that high doses can benefit mdx mice. We treated 4-week-old mdx and wildtype mice with low-dose resveratrol (5mg/kg bodyweight/day) for 15 weeks. A voluntary exercise protocol was added to test if low dose resveratrol could reduce exercise-induced damage. We showed that resveratrol promoted skeletal muscle hypertrophy in the wildtype mice. There was no change in markers of pathology in the mdx mice; however, the low-dose resveratrol reduced exercised induced damage. Gene expression of immune cell markers such as CD86, CD163 and PCNA was reduced; however signalling targets associated with resveratrol’s mechanism of action of action including SIRT1 and NF-κB were unchanged. In conclusion, low-dose resveratrol was not effective in reducing disease pathology; however, its ability to promote hypertrophy in wildtype skeletal muscle could have direct applications to the livestock industry or in sports medicine.
DSeg: A dynamic image segmentation program to extract backbone patterns for filamentous bacteria and hyphae structures
Authors: Zhang Hanqing , Söderholm Niklas , Sandblad Linda , Wiklund Krister , Andersson Magnus
Published: March 2018

Motivation

Quantitative image analysis of growing filamentous fungi and prokaryotes are important to detect and evaluate morphological effects of growth conditions, compounds and mutations. However, analysis of time-series image data is often limited by the ability of the algorithms to accurately segment structures that are complicated or if an organism is within a crowded population. To overcome these issues we present DSeg; an image analysis program designed to process time-series image data as well as single images to find multiple filamentous structures e.g., filamentous prokaryotes, yeasts and molds using a dynamic segmentation approach. DSeg automatically segments and analyzes objects, includes drift correction, and outputs statistical data such as persistence length, growth rate and growth direction.

Availability and implementation

DSeg is a free open-source program written in MATLAB. DSeg can be downloaded as a package from https://sourceforge.net/projects/dseg-software.

Contact

magnus.andersson@umu.se and hanqing.zhang@umu.se

Supplementary information

Supplementary data are available at online.
Cystinosin regulates kidney inflammation through its interaction with galectin-3
Authors: Lobry Tatiana , Miller Roy , Nevo Nathalie , Rocca Celine J. , Zhang Jinzhong , Catz Sergio D. , Moore Fiona , Bailleux Anne , Guerrera Ida Chiara , Gubler Marie-Claire , Wilson Cheung W. , Mak Robert H. , Montier Tristan , Antignac Corinne , Cherqui Stephanie
Published: March 2018

Inflammation is implicated in the pathogenesis of many disorders. Here, we show that cystinosin, protein defective in the lysosomal storage disorder cystinosis, is a critical regulator of galectin-3 during inflammation. Cystinosis is a lysosomal storage disorder and despite ubiquitous expression of cystinosin, kidney is the primary organ to be impacted by the disease. Here, we show that cystinosin interacts with galectin-3 and enhances its lysosomal localization and degradation. Galectin-3 is also found overexpressed in the kidney of the mouse model of cystinosis,Ctns-/-mice. Absence of galectin-3 inCtns-/-mice led to a better renal function and structure, and decreased macrophage/monocyte infiltration in the kidney. Finally, galectin-3 interacts with a protein implicated in the recruitment of monocytes and macrophages during inflammation, Monocyte Chemoattractant Protein-1 (MCP1), that was found increased in the serum ofCtns-/-mice. These findings highlight a new role of cystinosin and galectin-3 interaction in inflammation, providing a mechanistic explanation for kidney disease pathogenesis in cystinosis, which may lead to the identification of new drug targets to delay its progression.
Comparing methanol-glucose and dimethyl-sulfoxide based extender for milt cryopreservation of brown trout (Salmo trutta)
Authors: Nusbaumer David , Marques da Cunha Lucas , Wedekind Claus
Published: March 2018

The potential importance of sperm cryopreservation for aquaculture and conservation management seems still undervalued, probably because the available protocols often lead to reduced fertilization success. We experimentally compared the effectiveness of two different freezing extenders for cryopreservation of brown trout (Salmo trutta) semen, controlling for possible male and female effects. The methanol-glucose based extender that we tested was significantly more effective than a common dimethyl-sulfoxide based extender (a commercial cryopreservation kit). We then studied the effectiveness of the methanol-glucose based extender at different sperm-egg ratios and found no significant differences in fertilization ability of fresh and cryopreserved milt at a sperm-egg ratio of at least 110,000:1. We conclude that brown trout sperm cryopreserved with this extender can be used even at low sperm-egg ratios without significant effects on fertilization rates.
Intronic non-coding RNAs within ribosomal protein coding genes can regulate biogenesis of yeast ribosome
Authors: Pande Akshara , Sharma Rani , Iyengar Bharat Ravi , Scaria Vinod , Pillai Beena , Brahmachari Samir K
Published: March 2018

The genome of the budding yeast (Saccharomyces cerevisiae) has selectively retained introns in ribosomal protein coding genes. The function of these introns has remained elusive in spite of experimental evidence that they are required for the fitness of yeast. Here, we computationally predict novel small RNAs that arise from the intronic regions of ribosomal protein (RP) coding genes in Saccharomyces cerevisiae. Further, we experimentally validated the presence of seven intronic small RNAs (isRNAs). Computational predictions suggest that these isRNAs potentially bind to the ribosomal DNA (rDNA) locus or the corresponding rRNAs. Several isRNA candidates can also interact with transcripts of transcription factors and small nucleolar RNAs (snoRNAs) involved in the regulation of rRNA expression. We propose that the isRNAs derived from intronic regions of ribosomal protein coding genes may regulate the biogenesis of the ribosome through a feed-forward loop, ensuring the coordinated regulation of the RNA and protein components of the ribosomal machinery. Ribosome biogenesis and activity are fine-tuned to the conditions in the cell by integrating nutritional signals, stress response and growth to ensure optimal fitness. The enigmatic introns of ribosomal proteins may prove to be a novel and vital link in this regulatory balancing act.
Modern spandrels: The roles of genetic drift, gene flow and natural selection in the formation of parallel clines
Authors: Santangelo James S. , Johnson Marc T. J. , Ness Rob W.
Published: March 2018

Urban environments offer the opportunity to study the role of adaptive and non-adaptive evolutionary processes on an unprecedented scale. While the presence of parallel clines in heritable phenotypic traits is often considered strong evidence for the role of natural selection, non-adaptive evolutionary processes can also generate clines, and this may be more likely when traits have a non-additive genetic basis due to epistasis. In this paper, we use spatially-explicit simulations modelled according to the cyanogenesis (HCN) polymorphism in white clover (Trifolium repens) to examine the formation of phenotypic clines along urbanization gradients under varying levels of drift, gene flow and selection. HCN results from an epistatic interaction between two Mendelian-inherited loci. Our results demonstrate that the genetic architecture of this trait makes natural populations susceptible to decreases in HCN frequencies via drift. Gradients in the strength of drift across a landscape resulted in phenotypic clines with lower frequencies of HCN in strongly drifting populations, giving the misleading appearance of deterministic adaptive changes in the phenotype. Studies of heritable phenotypic change in urban populations should generate null models of phenotypic evolution based on the genetic architecture underlying focal traits prior to invoking selection’s role in generating adaptive differentiation.
Identification and characterization of a transporter complex responsible for the cytosolic entry of nitrogen-containing-bisphosphonates
Authors: Yu Zhou , Surface Lauren E. , Park Chong Yon , Horlbeck Max A. , Wyant Gregory A. , Abu-Remaileh Monther , Peterson Timothy R. , Sabatini David M. , Weissman Jonathan S. , O’Shea Erin K.
Published: March 2018

Abstract

Nitrogen-containing-bisphosphonates (N-BPs) are a class of drugs widely prescribed to treat osteoporosis and other bone-related diseases. Although previous studies have established that N-BPs function by inhibiting the mevalonate pathway in osteoclasts, the mechanism by which N-BPs enter the cytosol from the extracellular space to reach their molecular target is not understood. Here we implemented a CRISPRi-mediated genome-wide screen and identifiedSLC37A3(solute carrier family 37 member A3) as a gene required for the action of N-BPs. We observed that SLC37A3 forms a complex with ATRAID (all-trans retinoic acid-induced differentiation factor), a previously identified genetic target of N-BPs. SLC37A3 and ATRAID localize to lysosomes and are required for releasing N-BP molecules that have trafficked to lysosomes through fluid-phase endocytosis into the cytosol. Our results elucidate the route by which N-BPs are delivered to their molecular target, addressing a key aspect of the mechanism of action of N-BPs that may have significant clinical relevance.
Sexual reproduction in the fungal foliar pathogen Zymoseptoria tritici is driven by antagonistic density-dependence mechanisms
Authors: Suffert Frédéric , Delestre Ghislain , Gélisse Sandrine
Published: March 2018

This study provides empirical evidence for antagonistic density-dependence mechanisms driving sexual reproduction in the wheat fungal pathogen Zymoseptoria tritici. Biparental crosses with 12 increasing inoculum concentrations, in controlled conditions, showed that sexual reproduction in Z. tritici was impacted by an Allee effect due to mate limitation and a competition with asexual multiplication for resource allocation. We found that asexual multiplication was itself affected by competition for host resources between the two parental isolates, as illustrated by the decrease in asexual fruiting body density and sporulation intensity observed with increasing lesion density. Consistent with these results for controlled co-inoculation, we found that the intensity of sexual reproduction varied with both cropping period and the vertical position of the host tissues in the field. An optimal lesion density maximizing offspring (ascospores) number was established, and its eco-evolutionary consequences are considered here. Two ecological mechanisms may be involved: competition for resources between the two modes of reproduction (decrease in the host resources available for sexual reproduction due to their prior use in asexual multiplication), and competitive disequilibrium between the two parental isolates, due to differential interaction dynamics with the host, for example, leading to an imbalance between mating types. Conceptual models based on these results suggest that sexual reproduction plays a key role in the evolution of pathogenicity traits, including virulence and aggressiveness. Ecological knowledge about the determinants of sexual reproduction in Z. tritici may, therefore, open up new perspectives for the management of other fungal foliar pathogens with dual modes of reproduction.
taxMaps: comprehensive and highly accurate taxonomic classification of short-read data in reasonable time
Authors: Corvelo André , Clarke Wayne E. , Robine Nicolas , Zody Michael C.
Published: March 2018

High-throughput sequencing is a revolutionary technology for the analysis of metagenomic samples. However, querying large volumes of reads against comprehensive DNA/RNA databases in a sensitive manner can be compute-intensive. Here, we present taxMaps, a highly efficient, sensitive, and fully scalable taxonomic classification tool. Using a combination of simulated and real metagenomics data sets, we demonstrate that taxMaps is more sensitive and more precise than widely used taxonomic classifiers and is capable of delivering classification accuracy comparable to that of BLASTN, but at up to three orders of magnitude less computational cost.
I’ll do whatever I want … who are you to prohibit me? A tattle tale of workplace deviance
Authors: Mohammad Jihad , Quoquab Farzana , Bt Rashid Norsyila , Bt Rashid Nur Azlina , Bt Osman Fazilah , Hamka Wan Shamsudin Wan Muhammad
Published: March 2018

Subject area

This case can be used in teaching business ethics, organizational behaviour and human resource management. More specifically, romance in the workplace, discrimination, absenteeism, sneaking and cyberloafing in the workplace.

Study level/applicability

This case can be used for both undergraduate and postgraduate students particularly for business ethics, organizational behaviour, human resource management and leadership courses. Students/participants are challenged to identify the major issue in the case and help the decision maker to make a decision.

Case overview

This case demonstrates the unethical behaviour of Natacha and Noman Ali. Natacha refused to comply with the company’s code of conduct and breached the company’s rules and regulations. Natacha used the company’s resources to carry out her personal business and also cheated on her attendance records, and the Director of Enforcement and the Inspectorate Division, Noman, continued to back and support her. Madam Siti Hajar had consulted and advised her many times, but Natacha did not pay attention to her advice. Madam Siti was in a dilemma: whether to report this unethical situation to the top management or to tolerate this situation and remain silent.

Expected learning outcomes

Expected learning outcomes are as follows: to identify and describe major issues related to workplace unethical behaviour; to provide examples of the concepts of commitment, dedication, fairness, discrimination and ethical leadership; to identify and analyse individual and organizational factors that may affect individuals’ unethical behaviour; to instruct students of the scientific methods involved in making decisions; and. to help students to think thoroughly, deeply and critically to make decisions that can solve the problem at hand.

Supplementary materials

Teaching Notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes.

Subject code

CSS 6: Human Resource Management.
Employability, work placements, and outward mobility: views from England and Germany
Authors: Fowlie Julie , Forder Clare
Published: March 2018

Purpose

A central role of UK higher education institutes is preparing graduates for the global economy. However, UK outward mobility targets for students set in 2017 remain lower than the original set by the Bologna Process in 1999; with other European countries achieving substantially higher outward mobility. Research in this field concentrates primarily on studying abroad, prompting exploration of the work placement context. The purpose of this paper is to examine employability and outward mobility in the context of the perceived reluctance of UK students to undertake work placements abroad.

Design/methodology/approach

The views of undergraduate business management students at the Brighton Business School were compared with those of German students studying at the Goethe University in Frankfurt. Staff from Brighton Business School and other UK universities were also surveyed to gather data on attitudes towards work placements abroad.

Findings

Students from Brighton and Frankfurt displayed similar barriers to going abroad but were motivated by different drivers. The difference in these drivers is further echoed in the variations of their definitions of “employability”. The research also found that lack of staff awareness or interest in placements abroad could negatively affect the students’ decisions about going abroad.

Research limitations/implications

A small-scale study such as this presents only indicative findings. Further research is necessary to explore its implications in more depth.

Originality/value

The research provides more scope to the existing literature on outward mobility by addressing work placements rather than typically focusing on studying abroad. It adds value to the debate by examining placements and mobility through two different cultural lenses.
Freedom of conscience: a benefit to health care worker and patient alike
Authors: Kiska Roger
Published: March 2018

Purpose

The purpose of this paper is to determine the appropriate legal balance and framework whereby issues of health care, patient access and rights of conscience can be best accommodated.

Design/methodology/approach

A review of existing case law, statutes and conscience clauses as applied to the philosophical debate surrounding conscience in health care.

Findings

Freedom of conscience is strongly anchored in British law and policy. Practice within the health care industry, however, has been slow and resistant to rights of conscience. Respecting the right of health care workers to exercise that right, benefits the health care industry at large, and patients themselves.

Originality/value

This debate, particularly since the so-called “Scottish mid-wives case” and the recent General Pharmaceutical Council consultation on religion and personal values, has come to the forefront of bio-ethical discourse in recent months. As such, this treatment provides a valuable legal tool to answering the various positions involved in the debate.
Investigation of sustainability of lubricated journal bearing under relevant design parameters
Authors: Shahin M.M. , Chowdhury Mohammad Asaduzzaman , Kowser Md. Arefin , Debnath Uttam Kumar , Monir M.H.
Published: March 2018

Purpose

The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation.

Design/methodology/approach

A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance.

Findings

An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil.

Originality/value

It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.
Study the formation of mechanically mixed layer and subsurface behavior of worn-out surfaces of aged hybrid metal matrix composites
Authors: B.M. Viswanatha , Prasanna Kumar M. , Basavarajappa S. , Kiran T.S.
Published: March 2018

Purpose

This paper aims to investigate the wear behaviors of aged metal matrix composites and of the as-cast Al-Si alloy by using a pin-on-disk wear testing machine at room temperature.

Design/methodology/approach

Hypoeutectic (Al-7Si) alloy reinforced with low volume fractions of SiC particles (SiCp) and graphite (Gr) particles were prepared by the stir-casting process. It was found that the addition of 9 Wt.% of SiCp and 3 Wt.% of Gr particles conferred a beneficial effect in reducing the wear rate of the composites.

Findings

The worn-out surfaces of the specimens were examined using scanning electron microscopy (SEM); the extensive micro cracking occurs on the surface of the Al-7Si alloy tested at lower loads. The growth of these microcracks finally led to the delamination of the base alloy surface. The reinforcements (SiCp and Gr) particles tended to reduce the extent of plastic deformation in the surface layer, thereby reducing extensively the occurrence of micro cracking in the composites.

Originality/value

From the results, it is revealed that the quantity of wear rate was less for aged specimens compared to the as-cast specimens. The worn-out surfaces were studied using electron dispersive spectroscopy, and wear debris was analyzed using SEM.
Estimation of rolling friction coefficients in a tribosystem using optical measurements
Authors: Li Yiling , Xi Yinhu , Shi Yijun
Published: March 2018

Purpose

This paper aims to present a method to measure the rolling friction coefficient in an easy and fast way. The aim is also to measure the rolling friction coefficient between a small steel ball and a cylindrical aluminum surface.

Design/methodology/approach

An analytical model of the tribosystem of a freely rolling ball and a cylindrical surface is established. The rolling friction coefficient is evaluated from images recorded by a high-speed camera. The coefficient between a 1.58-mm diameter steel ball and a cylindrical aluminum surface is measured. A background subtraction algorithm is used to determine the position of the small steel ball.

Findings

The angular positions of the ball are predicted using the analytical model, and a good agreement is found between the experimental and theoretical results.

Originality/value

An optical method for evaluating the rolling friction coefficient is presented, and the value of this coefficient between a small steel ball and a cylindrical aluminum surface is evaluated.
A study of dynamic behaviors of contact pair in lubricated ball linear guide
Authors: Li Linlin , Yang Jiajun
Published: March 2018

Purpose

This paper aims to predict the dynamic behaviors of contact between the steel ball and raceway in the elastohydrodynamically lubricated ball linear guide, thus providing a guidance for lubrication design for ball linear guide.

Design/methodology/approach

Based on the point contact elastohydrodynamic lubrication (EHL) theory, the free vibration model of contact pair is presented to qualitatively analyze the effect of vibration on the film characteristics. The models of the film stiffness and damping coefficient under the EHL condition are built to investigate the effects of the working conditions on the dynamic parameters. The full numerical solutions are obtained using the multigrid technique.

Findings

It is found that there exists damping from the decay of oscillations of the pressure and film thickness in the lubricated ball linear guide. Furthermore, the working conditions of the high load or low velocity can lead to the increase in the film stiffness in the steel ball-raceway contact, but there is a reverse variation trend for the film damping coefficient.

Originality/value

The contact pair has been usually treated as dry in past studies on dynamics of the ball linear guide, and the damping is neglected. This research considers the actual lubrication and working conditions and predicts the dynamic behaviors of contact pair.
Microstructure and friction-wear performances of cathodic arc ion plated TiAlSiCN coatings on YT14 cemented carbide cutting tools
Authors: Jun Kong de , Donghui Zhang
Published: March 2018

Purpose

The purpose of this study was to develop a TiAlSiCN coating with high bonding and hardness, ultra-low friction and good lubrication characteristics, which provided an experimental basis for the surface modification of YT14 cemented carbide cutting tools.

Design/methodology/approach

In this work, a TiAlSiCN coating was deposited on YT14 cemented carbide cutting tool through cathodic arc ion plating. The surface-interface morphologies, distributions of chemical elements, phases, bonding energy and surface roughness were analyzed using field emission scanning electron microscopy, energy-dispersive spectroscopy (EDS), X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy, respectively, and the coating the bonding strength were quantitatively characterized with a scratch.

Findings

The average COFs of the TiAlSiCN coating at 700°C, 800°C and 900°C were 0.68, 0.57 and 0.38, respectively, showing that the TiAlSiCN coating was an effective lubricant at a high temperature, and the wear rate of the coating increases with wear temperature. After wearing at 700°C, 800°C and 900°C, the Ti, Si and N elements form atom-poor regions, while Al forms an atom-rich region, showing that the oxides of Ti, Al and Si are formed to improve the wear resistance of the coating. The wear mechanism of TiAlSiCN coating at high temperatures was composed of abrasive wear and oxidation wear.

Originality/value

The friction-wear behaviors of TiAlSiN coating were investigated using an HT-1000-type high-temperature friction wear tester, and the worn tracks on the coatings were analyzed using an EDS plane scan, thus obtaining the wear mechanism of TiAlSiN coating.
Piston skirt friction loss and dynamic analyses based on FEM method
Authors: He Zhenpeng
Published: March 2018

Purpose

The analysis carried out in this study can provide guidance for manufacturers and researchers to design a piston for the development of engines.

Design/methodology/approach

Running conditions for pistons have become very severe because of the high combustion pressure and increase in piston temperature in the past 10 years. The precision of the model has a great effect on the power transmission, vibration noise emission. In this paper, the model was established with lubrication and dynamic governing equations, which were solved using finite element method coupled with Runge–Kutta method. A piston of an inline six-cylinder engine was studied, and some structural parameters were used to investigate its effect on the friction loss with lubrication and dynamic motion theory.

Findings

Based on the analyses, the effect of the friction load at the oil groove and thermal deformation of piston skirt were added to the model, and some useful information about the friction loss and dynamic characteristics were compared.

Originality/value

All the results will provide guidance for the development of the piston and reduction in the friction loss and wear.
Low friction states for thin solid lubricant film of MoS2
Authors: Chu Kwang-Hua R.
Published: March 2018

Purpose

During the operation of Wendelstein 7-X (W7-X), any mechanical disturbance such as stick-slip may cause quenching of superconducting (SC) coils. The friction behavior of MoS2 lubrication (thin film) for narrow support elements between the SC coils in W7-X is rather important, as there is a design requirement for a coefficient of friction (COF) 0.05 between the sliding surfaces to control the stress contribution (from friction).

Design/methodology/approach

The author has carried out intensive calibrations or verifications using verified models considering previous friction tests on various samples which measured the COF in 4.2 K, 77 K and room temperature conditions (at high vacuum) to simulate the actual working condition.

Findings

The author has given useful explanations and diagnosis for previous anomalous scattered data. To improve the performance of MoS2, the author has predicted its better COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS2 thin films considering the long-term operation requirement W7-X.

Originality/value

In this paper, the author has adopted Eyring’s approach to predict the low COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS2 thin films considering the long-term operation requirement W7-X. Finally, some recent progresses about the possible few-layer MoS2 role in the electromagnetic loads have been provided.
The impact of mixed eWOM sequence on brand attitude change: cross-cultural differences
Authors: Park Hyun Hee , Jeon Jung Ok
Published: March 2018

Purpose

Despite the importance of electronic word-of-mouth (eWOM) in e-commerce transactions on the global market, there is still limited understanding about the effect of eWOM sequence and its psychological mechanism in cross-cultural settings. Therefore, the purpose of this paper is to investigate the differences in brand attitude changes according to the eWOM sequence, as well as cross-culturally, based on thinking styles. Furthermore, the authors examine the moderated mediation effect of perceived cognition congruency across cultures to explain its underlying mechanism.

Design/methodology/approach

The authors use a 2 (eWOM sequence: positive/negative, negative/positive) × 2(culture: East (South Korea), West (USA)) factorial design. Perceived cognition congruency is measured as a within-group variable.

Findings

First, brand attitude changes in the West (USA) for the negative/positive presentation order are significantly larger than for the positive/negative presentation order, while, in the East (South Korea), no significant differences exist. Second, in the Westerner group (analytical thinking style), the perceived cognition congruency shows a significant difference according to the eWOM sequence, whereas in the Easterner group (holistic thinking style), the perceived cognition congruency does not show a significant difference according to the eWOM sequence.

Practical implications

As such, a strategic interpretation of the mixed eWOM presentation order across cultures is needed. In the West, interest and attention are necessary for the eWOM sequence. However, in the East, a different strategic approach, except for the presentation order of mixed eWOM, is required. The other elements of the mixed eWOM, such as attribute type or intensity of negative information, need to be considered for mixed eWOM management.

Originality/value

This study expands the existing body of knowledge on the sequence effect of mixed eWOM. Furthermore, it provides strategic direction and practical implications for mixed eWOM-driven information management, focusing on sequence in cross-cultural settings.
Leading with compassion in health care organisations
Authors: Hewison Alistair , Sawbridge Yvonne , Cragg Robert , Rogers Laura , Lehmann Sarah , Rook Jane
Published: March 2018

Purpose

The purpose of this paper is to report an evaluation of a leading-with-compassion recognition scheme and to present a new framework for compassion derived from the data.

Design/methodology/approach

Qualitative semi-structured interviews, a focus group and thematic data analysis. Content analysis of 1,500 nominations of compassionate acts.

Findings

The scheme highlighted that compassion towards staff and patients was important. Links to the wider well-being strategies of some of the ten organisations involved were unclear. Awareness of the scheme varied and it was introduced in different ways. Tensions included the extent to which compassion should be expected as part of normal practice and whether recognition was required, association of the scheme with the term leadership, and the risk of portraying compassion as something separate, rather than an integral part of the culture. A novel model of compassion was developed from the analysis of 1,500 nominations.

Research limitations/implications

The number of respondents in the evaluation phase was relatively low. The model of compassion contributes to the developing knowledge base in this area.

Practical implications

The model of compassion can be used to demonstrate what compassion “looks like”, and what is expected of staff to work compassionately.

Originality/value

A unique model of compassion derived directly from descriptions of compassionate acts which identifies the impact of compassion on staff.
Political connections, family firms and earnings quality
Authors: Hashmi Muhammad Arsalan , Brahmana Rayenda Khresna , Lau Evan
Published: March 2018

Purpose

This paper aims to investigate the effect of political connections on earnings quality by simultaneously controlling the firm characteristics; to test whether Pakistani firms’ ownership, specifically family ownership, plays a significant role in political connections–earnings quality association; to draw a conclusion about the agency theory in the context of Pakistan.

Design/methodology/approach

A quantitative approach was used to examine the influence of political connections and family ownership on the earnings quality of listed firms in Pakistan. The study uses historical data from 238 active non-financial firms listed on the Pakistan Stock Exchange during the period of 2009-2015. The final data set comprises more than 1,600 firm-year observations from ten major non-financial industry classifications. To enhance the robustness of the empirical relationship, the study used several proxies of earnings quality in conjunction with robust regression methods and diagnostic checks.

Findings

The present study’s findings are consistent with the findings of the studies on agency theory previous literature, where politically connected firms have significantly lower earnings quality as compared to non-connected firms. The results also indicate that family firms have superior earnings quality than non-family–controlled firms. Furthermore, family ownership moderates the negative influence of political connections on earnings quality. This implies that family ownership diminishes the costs of political connections and improves the earnings quality of the firm.

Originality/value

This study is different from previous research in three respects. First, it examines whether family ownership concentration has a moderating influence on the relationship between political connections and earnings quality. Second, it uses a robust methodology and extensive data set to examine the influence of political connections and family ownership concentration on earnings quality. Further, this study is the first to analyze the nexus between financial reporting quality and the political business environment in the context of Pakistan.
Resilience in agri-food supply chains: a critical analysis of the literature and synthesis of a novel framework
Authors: Stone Jamie , Rahimifard Shahin
Published: March 2018

Purpose

Resilience in agri-food supply chains (AFSCs) is an area of significant importance due to growing supply chain volatility. While the majority of research exploring supply chain resilience has originated from a supply chain management perspective, many other disciplines (such as environmental systems science and the social sciences) have also explored the topic. As complex social, economic and environmental constructs, the priority of resilience in AFSCs goes far beyond the company specific focus of supply chain management works and would conceivably benefit from including more diverse academic disciplines. However, this is hindered by inconsistencies in terminology and the conceptual components of resilience across different disciplines. The purpose of this study is to use a systematic literature review to identify which multidisciplinary aspects of resilience are applicable to AFSCs and to generate a novel AFSC resilience framework.

Design/methodology/approach

This paper uses a structured and multidisciplinary review of 137 articles in the resilience literature followed by critical analysis and synthesis of findings to generate new knowledge in the form of a novel AFSC resilience framework.

Findings

Findings indicate that the complexity of AFSCs and subsequent exposure to almost constant external interference means that disruptions cannot be seen as a one-off event; thus, resilience must concern the ability to not only maintain core function but also adapt to changing conditions.

Practical implications

A number of resilience elements can be used to enhance resilience, but their selection and implementation must be carefully matched to relevant phases of disruption and assessed on their broader supply chain impacts. In particular, the focus must be on overall impact on the ability of the supply chain as a whole to provide food security rather than to boost individual company performance.

Originality/value

The research novelty lies in the utilisation of wider understandings of resilience from various research fields to propose a rigorous and food-specific resilience framework with end consumer food security as its main focus.