bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of familiarity in signaller–receiver interactions
Authors: Ma Wei Ji , Higham James P.
Published: December 2018

In animal communication, individuals of species exhibiting individual recognition of conspecifics with whom they have repeated interactions, receive signals not only from unfamiliar conspecifics, but also from individuals with whom they have prior experience. Empirical evidence suggests that familiarity with a specific signaller aids receivers in interpreting that signaller's signals, but there has been little theoretical work on this effect. Here, we develop a Bayesian decision-making model and apply it to the well-studied systems of primate ovulation signals. We compare the siring probability of learner males versus non-learner males, based on variation in their assessment of the best time to mate and mate-guard females. We compare males of different dominance ranks, and vary the number of females, and their cycle synchrony. We find strong fitness advantages for learners, which manifest very quickly. Receivers do not have to see the full range of a signaller's signals in order to start gaining familiarity benefits. Reproductive asynchrony and increasing the number of females both enhance learning advantages. We provide theoretical evidence for a strong advantage to specific learning of a signaller's range of signals in signalling systems. Our results have broad implications, not only for understanding communication, but in elucidating additional fitness benefits to group-living, the evolution of individual recognition, and other characteristics of animal behavioural biology.
Instability-driven oscillations of elastic microfilaments
Authors: Ling Feng , Guo Hanliang , Kanso Eva
Published: December 2018

Cilia and flagella are highly conserved slender organelles that exhibit a variety of rhythmic beating patterns from non-planar cone-like motions to planar wave-like deformations. Although their internal structure, composed of a microtubule-based axoneme driven by dynein motors, is known, the mechanism responsible for these beating patterns remains elusive. Existing theories suggest that the dynein activity is dynamically regulated, via a geometric feedback from the cilium’s mechanical deformation to the dynein force. An alternative, open-loop mechanism based on a ‘flutter’ instability was recently proven to lead to planar oscillations of elastic filaments under follower forces. Here, we show that an elastic filament in viscous fluid, clamped at one end and acted on by an external distribution of compressive axial forces, exhibits a Hopf bifurcation that leads to non-planar spinning of the buckled filament at a locked curvature. We also show the existence of a second bifurcation, at larger force values, that induces a transition from non-planar spinning to planar wave-like oscillations. We elucidate the nature of these instabilities using a combination of nonlinear numerical analysis, linear stability theory and low-order bead–spring models. Our results show that, away from the transition thresholds, these beating patterns are robust to perturbations in the distribution of axial forces and in the filament configuration. These findings support the theory that an open-loop, instability-driven mechanism could explain both the sustained oscillations and the wide variety of periodic beating patterns observed in cilia and flagella.
Developmental regulators FlbE/D orchestrate the polarity site-to-nucleus dynamics of the fungal bZIP FlbB
Authors: Otamendi Ainara , Perez-de-Nanclares-Arregi Elixabet , Oiartzabal Elixabet , Cortese Marc S. , Espeso Eduardo A. , Etxebeste Oier
Published: December 2018

Permanently polarized cells have developed transduction mechanisms linking polarity-sites with gene regulation in the nucleus. In neurons, one mechanism is based on long-distance retrograde migration of transcription factors (TFs).Aspergillus nidulansFlbB is the only known fungal TF shown to migrate retrogradely to nuclei from the polarized region of fungal cells known as hyphae. There, FlbB controls developmental transitions by triggering the production of asexual multicellular structures. FlbB dynamics in hyphae is orchestrated by regulators FlbE and FlbD. At least three FlbE domains are involved in the acropetal transport of FlbB, with a final MyoE/actin filament-dependent step from the subapex to the apex. Experiments employing a T2A viral peptide-containing chimera (FlbE::mRFP::T2A::FlbB::GFP) suggest that apical FlbB/FlbE interaction is inhibited in order to initiate a dynein-dependent FlbB transport to nuclei. FlbD controls the nuclear accumulation of FlbB through a cMyb domain and a C-terminal LxxLL motif. Overall, results elucidate a highly dynamic pattern of FlbB interactions, which enable timely developmental induction. Furthermore, this system establishes a reference for TF-based long-distance signaling in permanently polarized cells.
Acquisition of visual priors and induced hallucinations in chronic schizophrenia
Authors: Valton Vincent , Karvelis Povilas , Richards Katie L. , Seitz Aaron R. , Lawrie Stephen M. , Seriès Peggy
Published: December 2018

Prominent theories suggest that symptoms of schizophrenia stem from learning deficiencies resulting in distorted internal models of the world. To further test these theories, we here use a visual statistical learning task known to induce rapid implicit learning of the stimulus statistics (Chalk et al., 2010). In this task, participants are presented with a field of coherently moving dots and need to report the presented direction of the dots (estimation task) and whether they saw any dots or not (detection task). Two of the directions were more frequently presented than the others. In controls, the implicit acquisition of the stimuli statistics influences their perception in two ways: 1-motion directions are perceived as being more similar to the most frequently presented directions than they really are (estimation biases); 2-in the absence of stimuli, participants sometimes report perceiving the most frequently presented directions (a form of hallucinations). Such behaviour is consistent with probabilistic inference, i.e. combining learnt perceptual priors with sensory evidence. We investigated whether patients with chronic, stable, treated schizophrenia (n=20) differ from controls (n=23) in the acquisition of the perceptual priors and/or their influence on perception. We found that, although patients were slower than controls, they showed comparable acquisition of perceptual priors, correctly approximating the stimulus statistics. This suggests that patients have no statistical learning deficits in our task. This may reflect our patients relative wellbeing on antipsychotic medication. Intriguingly, however, patients made significantly fewer hallucinations of the most frequently presented directions than controls and fewer prior-based lapse estimations. This suggests that prior expectations had less influence on patients’ perception than on controls when stimuli were absent or below perceptual threshold.
Predicting circRNA-RBP interaction sites using a codon-based encoding and hybrid deep neural networks
Authors: Zhang Kaiming , Pan Xiaoyong , Yang Yang , Shen Hong-Bin
Published: December 2018

Circular RNAs (circRNAs), with their crucial roles in gene regulation and disease development, have become a rising star in the RNA world. A lot of previous wet-lab studies focused on the interaction mechanisms between circRNAs and RNA-binding proteins (RBPs), as the knowledge of circRNA-RBP association is very important for understanding functions of circRNAs. Recently, the abundant CLIP-Seq experimental data has made the large-scale identification and analysis of circRNA-RBP interactions possible, while no computational tool based on machine learning has been developed yet.

We present a new deep learning-based method, CRIP (CircRNAs Interact with Proteins), for the prediction of RBP binding sites on circRNAs, using only the RNA sequences. In order to fully exploit the sequence information, we propose a stacked codon-based encoding scheme and a hybrid deep learning architecture, in which a convolutional neural network (CNN) learns high-level abstract features and a recurrent neural network (RNN) learns long dependency in the sequences. We construct 37 datasets including sequence fragments of binding sites on circRNAs, and each set corresponds to one RBP. The experimental results show that the new encoding scheme is superior to the existing feature representation methods for RNA sequences, and the hybrid network outperforms conventional classifiers by a large margin, where both the CNN and RNN components contribute to the performance improvement. To the best of our knowledge, CRIP is the first machine learning-based tool specialized in the prediction of circRNA-RBP interactions, which is expected to play an important role for large-scale function analysis of circRNAs.
Identification of QTL for leaf angle at canopy-wide levels in maize
Authors: Tang Dengguo , Chen Zhengjie , Ni Jixing , Jiang Qin , Li Peng , Wang Le , Zhou Jinhong , Li Chenyang , Liu Jian
Published: December 2018

Leaf angle (LA) is one of the most important canopy architecture related traits of maize (Zea mays L.). Currently, there is an urgent need to elucidate the genetic mechanism of LA at canopy-wide levels for optimizing dense-planting canopy architecture. In present study, one RIL population derived from two parent lines which show distinct plant architecture was used to perform QTL mapping for LA at eight leaves below the tassel under three environments. Dozens of QTL for LA at eight leaves were identified, which were mapped on all maize chromosomes except for the tenth chromosome. Among them, there were nine common QTL as they were identified for LA more than 1 leaves or in two or three environments. And individual QTL could explain 1.29% - 20.14% of the phenotypic variation and affect LA of 1-8 leaves, including qLA5.1 affected LA of all eight leaves, qLA3.1 affected LA of the upper leaves (1stLA to 4thLA), and qLA9.1 could affect LA of the lower leaves (5thLA to 8thLA). Furthermore, the results indicated that the genetic architecture of LA at eight leaves was different. Specifically, 8thLA was mainly affected by major and minor QTL; 1stLA, 4thLA and 5thLA were affected by epistatic interactions beside major and minor QTL; while the other four LAs were simultaneously affected by major QTL, minor QTL, epistatic interactions and environments. These results provide a comprehensive understanding of genetic basis of LA at canopy-wide levels, which will be beneficial to design ideal plant architecture under dense planting in maize.

Author contribution statement

J. L. and D. T. designed and supervised the study, D. T., Z.C., J.N., Q.J., P.L., L.W., J.Z., C.L. performed the phenotypic data collection. D. T. analyzed the data and drafted the manuscript, D. T. and Z.C. revised and finalized the manuscript. All the authors read and approved the manuscript.

Key message

Dozens of QTL for leaf angle of eight consecutive leaves were identified in the RIL population across three environments, providing the information that optimization of canopy architecture at various canopy levels.
A common deliberative process underlies model-based planning and patient intertemporal choice
Authors: Hunter Lindasy E , Bornstein Aaron M , Hartley Catherine A
Published: December 2018

Humans and animals consistently forego, or 'discount' future rewards in favor of more proximal, but less valuable, options. This behavior is often thought of in terms of a failure of 'self-control', a lack of inhibition when considering the possibility of immediate gratification. However, rather than overweighting the near-term reward, the same behavior can result from failing to properly consider the far-off reward. The capacity to plan for future gains is a core construct in Reinforcement Learning (RL), known as 'model-based' planning. Both discounting and model-based planning have been shown to track everyday behaviors from diet to exercise habits to drug abuse. Here, we show that these two capacities are related via a common mechanism -- people who are more likely to deliberate about future reward in an intertemporal choice task, as indicated by the time they spend considering the choice, are also more likely to make multi-step plans for reward in a sequential reinforcement learning task. In contrast, the degree to which people's intertemporal choices were driven by a more automatic bias did not correspond to their planning tendency, and neither did the more standard measure of discounting behavior. These results suggest that the standard behavioral economic measure of discounting is more fruitfully understood by decomposing it into constituent parts, and that only one of these parts corresponds to the sort of multi-step thinking needed to make plans for the future.
A High-Quality De Novo Genome Assembly from a Single Mosquito using PacBio Sequencing
Authors: Kingan Sarah B. , Heaton Haynes , Cudini Juliana , Lambert Christine C. , Baybayan Primo , Galvin Brendan D. , Durbin Richard , Korlach Jonas , Lawniczak Mara K. N.
Published: December 2018

A high-quality reference genome is a fundamental resource for functional genetics, comparative genomics, and population genomics, and is increasingly important for conservation biology. PacBio Single Molecule, Real-Time (SMRT) sequencing generates long reads with uniform coverage and high consensus accuracy, making it a powerful technology for de novo genome assembly. Improvements in throughput and concomitant reductions in cost have made PacBio an attractive core technology for many large genome initiatives, however, relatively high DNA input requirements (∼5 µg for standard library protocol) have placed PacBio out of reach for many projects on small organisms that have lower DNA content, or on projects with limited input DNA for other reasons. Here we present a high-quality de novo genome assembly from a single Anopheles coluzzii mosquito. A modified SMRTbell library construction protocol without DNA shearing and size selection was used to generate a SMRTbell library from just 100 ng of starting genomic DNA. The sample was run on the Sequel System with chemistry 3.0 and software v6.0, generating, on average, 25 Gb of sequence per SMRT Cell with 20 hour movies, followed by diploid de novo genome assembly with FALCON-Unzip. The resulting curated assembly had high contiguity (contig N50 3.5 Mb) and completeness (more than 98% of conserved genes are present and full-length). In addition, this single-insect assembly now places 667 (>90%) of formerly unplaced genes into their appropriate chromosomal contexts in the AgamP4 PEST reference. We were also able to resolve maternal and paternal haplotypes for over 1/3 of the genome. By sequencing and assembling material from a single diploid individual, only two haplotypes are present, simplifying the assembly process compared to samples from multiple pooled individuals. The method presented here can be applied to samples with starting DNA amounts as low as 100 ng per 1 Gb genome size. This new low-input approach puts PacBio-based assemblies in reach for small highly heterozygous organisms that comprise much of the diversity of life.
The making of a Lewy body: the role of alpha-synuclein post-fibrillization modifications in regulating the formation and the maturation of pathological inclusions.
Authors: Mahul-Mellier Anne-Laure , Altay Firat , Burtscher Johannes , Maharjan Niran , Ait Bouziad Nadine , Chiki Anass , Vingill Siv , Wade-Martins Richard , Holton Janice , Strand Catherine , Haikal Caroline , Li Jia-yi , Hamelin Romain , Croisier Marie , Knott Graham , Mairet-Coello Georges , Weerens Laura , Michel Anne , Downey Patrick , Citron Martin , Lashuel Hilal A
Published: December 2018

Although converging evidence point to alpha-synuclein (a-syn) aggregation and Lewy body (LB) formation as central events in Parkinson's disease (PD), the molecular mechanisms that regulate these processes and their role in disease pathogenesis remain poorly understood. Herein, we applied an integrative biochemical, structural and imaging approach to elucidate the sequence, molecular and cellular mechanisms that regulate LB formation in primary neurons. Our results establish that post-fibrillization C-terminal truncation mediated by calpains 1 and 2 and potentially other enzymes, plays critical roles in regulating a-syn seeding, fibrillization and orchestrates many of the events associated with LB formation and maturation. These findings combined with the abundance of a-syn truncated species in LBs and pathological a-syn aggregates have significant implications for ongoing efforts to develop therapeutic strategies based on targeting the C-terminus of a-syn or proteolytic processing of this region.
Image Quality Causes Substantial Bias in Three-Dimensional Speckle-Tracking Echocardiography Measures
Authors: Al Saikhan Lamia , Park Chloe , Hughes Alun
Published: December 2018

BACKGROUND: Three-dimensional speckle-tracking echocardiography (3D-STE) is increasingly used to assess left ventricular (LV) mechanics but the quantitative effect of image quality on measurements is not known.
OBJECTIVES: To assess the impact of image quality on 3D-STE derived LV indices.
METHODS: Echocardiography was performed in two groups of 18 healthy participants. In the first study, optimal and intentionally poor-quality images were acquired. In the second study, a sheet of ultrasound-attenuating material (neoprene rubber) of three different thicknesses (2, 3 and 4 mm) was used to mimic mildly, moderately and severely impaired image quality respectively.
RESULTS: In both studies sub-optimal image quality resulted in a systematic underestimation bias in all LV deformation and rotational indices. LV ejection fraction and volumes were also consistently underestimated. The extent of the bias was proportional to the impairment in image quality (i.e. the poorer the image quality the larger the bias). Reproducibility was also less good for sub-optimal images, although LV volumes and ejection fraction showed excellent reproducibility irrespective of image quality.
CONCLUSIONS: Sub-optimal image quality introduces a substantial systematic bias and impairs the reproducibility of 3D-STE. Bias related to image quality might have important clinical implications since its magnitude is similar to that reported in association with disease and may confound associations between disease and LV mechanics.
Lipopolysaccharide (LPS) induces increased epidermal green autofluorescence of mouse
Authors: Li Yujia , Zhang Mingchao , Tao Yue , Ying Weihai
Published: December 2018

Our recent studies have suggested that characteristic ‘Pattern of Autofluorescence (AF)’ of each disease could be a novel biomarker for non-invasive diagnosis of multiple major diseases such as acute ischemic stroke. It is necessary to determine if increased epidermal green AF may be produced by major pathological factors such as inflammation. In our current study, we used C57BL/6Slac mice exposed to LPS to test our hypothesis that inflammation may induce increased epidermal green AF: LPS rapidly induced significant increases in the epidermal green AF of the mice’s ears at 1 hr after LPS injection. LPS also dose-dependently increased the epidermal green AF. The AF intensity had a linear relationship with the LPS dosages at both 3 and 7 days after the LPS administration. The AF images exhibited the characteristic structure of the keratinocytes in Stratum Spinosum, suggesting that the origin of the increased AF was keratin 1 and/or keratin 10. Collectively, our current study has provided the first evidence indicating that inflammation can rapidly and dose-dependently induce increased epidermal green AF, suggesting that the green AF may be the first biomarker for non-invasive and rapid detection of systemic inflammation. Since inflammation is a key pathological factor of numerous diseases, our finding has highlighted the value of the epidermal AF as a novel diagnostic biomarker for numerous diseases.
gencore: An Efficient Tool to Generate Consensus Reads for Error Suppressing and Duplicate Removing of NGS data
Authors: Chen Shifu , Zhou Yanqing , Chen Yaru , Huang Tanxiao , Liao Wenting , Xu Yun , Li Zhicheng , Gu Jia
Published: December 2018

Background

Removing duplicates might be considered as a well-resolved problem in next-generation sequencing (NGS) data processing domain. However, as NGS technology gains more recognition in clinical applications (i.e. cancer testing), researchers start to pay more attention to its sequencing errors, and prefer to remove these errors while performing deduplication operations. Recently, a new technology called unique molecular identifier (UMI) has been developed to better identify sequencing reads derived from different DNA fragments. Most existing duplicate removing tools cannot handle the UMI-integrated data. Some modern tools can work with UMIs, but are usually slow and use too much memory, making them not suitable for cloud-based deployment. Furthermore, existing tools rarely report rich statistical results, which are very important for quality control and downstream analysis. These unmet requirements drove us to develop an ultra-fast, simple, little-weighted but powerful tool for duplicate removing and sequence error suppressing, with features of handling UMIs and reporting informative results.

Results

This paper presents an efficient tool gencore for duplicate removing and sequence error suppressing of NGS data. This tool clusters the mapped sequencing reads and merges reads in each cluster to generate one single consensus read. While the consensus read is generated, the random errors introduced by library construction and sequencing can be removed. This error-suppressing feature makes gencore very suitable for the application of detecting ultra-low frequency mutations from deep sequencing data. When unique molecular identifier (UMI) technology is applied, gencore can use them to identify the reads derived from same original DNA fragment. gencore reports statistical results in both HTML and JSON formats. The HTML format report contains many interactive figures plotting statistical coverage and duplication information. The JSON format report contains all the statistical results, and is interpretable for downstream programs.

Conclusions

Comparing to the conventional tools like Picard and SAMtools, gencore greatly reduces the output data’s mapping mismatches, which are mostly caused by errors. Comparing to some new tools like UMI-Reducer and UMI-tools, gencore runs much faster, uses less memory, generates better consensus reads and provides simpler interfaces. To our best knowledge, gencore is the only duplicate removing tool that generates both informative HTML and JSON reports. This tool is available at: https://github.com/OpenGene/gencore
High temperature corrosion behaviour of aluminised FC 25 cast iron using pack cementation
Authors: Chandra-Ambhorn Somrerk , Krasaelom Neramit , Thublaor Tummaporn , Leelachao Sirichai
Published: December 2018

Purpose

This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the alloy.

Design/methodology/approach

Pack cementation was applied on the surface of FC 25 cast iron at 1,050°C. The bare and aluminised alloys were subjected to the oxidation test in 20 per cent O2-N2 at 850 °C. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used for characterisation.

Findings

The layers of pack cementation consisted of Fe2Al5, FeAl2 and FeAl, and solid solution alloyed with Al. The oxidation kinetics of the bare cast iron was parabolic. Mass gain of the aluminised cast iron was significantly decreased compared with that of the bare cast iron. This was because of the protective alumina formation on the aluminised alloy surface. Al in the Fe–Al layer also tended to be homogenised during oxidation.

Originality/value

Even though the aluminising of alloys was extensively studied, the application of that process to the FC 25 cast iron grade was originally developed in this work. The significantly reduced mass gain of the aluminised FC 25 cast iron makes the studied alloy be promising for the use as a valve seat insert in an agricultural single-cylinder four-stroke engine, which might be run by using a relatively cheaper fuel, i.e. LPG, but as a consequence requires the higher oxidation resistance of the engine parts.
4D-trajectory time windows: definition and uncertainty management
Authors: Rodríguez-Sanz Álvaro , Gómez Comendador Fernando , Arnaldo Valdés Rosa M. , Pérez-Castán Javier A. , González García Pablo , Najar Godoy Mar Najar Godoy
Published: December 2018

Purpose

The use of the 4D trajectory operational concept in the future air traffic management (ATM) system will require the aircraft to meet very accurately an arrival time over a designated checkpoint. To do this, time intervals known as time windows (TW) are defined. The purpose of this paper is to develop a methodology to characterise these TWs and to manage the uncertainty associated with the evolution of 4D trajectories.

Design/methodology/approach

4D trajectories are modelled using a point mass model and EUROCONTROL’s BADA methodology. The authors stochastically evaluate the variability of the parameters that influence 4D trajectories using Monte Carlo simulation. This enables the authors to delimit TWs for several checkpoints. Finally, the authors set out a causal model, based on a Bayesian network approach, to evaluate the impact of variations in fundamental parameters at the chosen checkpoints.

Findings

The initial results show that the proposed TW model limits the deviation in time to less than 27 s at the checkpoints of an en-route segment (300 NM).

Practical implications

The objective of new trajectory-based operations is to efficiently and strategically manage the expected increase in air traffic volumes and to apply tactical interventions as a last resort only. We need new tools to support 4D trajectory management functions such as strategic and collaborative planning. The authors propose a novel approach for to ensure aircraft punctuality.

Originality/value

The main contribution of the paper is the development of a model to deal with uncertainty and to increase predictability in 4D trajectories, which are key elements of the future airspace operational environment.
A novel improvement of Kriging surrogate model
Authors: He Wei , Xu Yuanming , Zhou Yaoming , Li Qiuyue
Published: December 2018

Purpose

This paper aims to introduce a method based on the optimizer of the particle swarm optimization (PSO) algorithm to improve the efficiency of a Kriging surrogate model.

Design/methodology/approach

PSO was first used to identify the best group of trend functions and to optimize the correlation parameter thereafter.

Findings

The Kriging surrogate model was used to resolve the fuselage optimization of an unmanned helicopter.

Practical implications

The optimization results indicated that an appropriate PSO scheme can improve the efficiency of the Kriging surrogate model.

Originality/value

Both the STANDARD PSO and the original PSO algorithms were chosen to show the effect of PSO on a Kriging surrogate model.
Data flows and the digital economy: information as a mobile factor of production
Authors: Mueller Milton , Grindal Karl
Published: December 2018

Purpose

This paper aims to analyze the direction and balance of transnational information flows and look at how nonpriced digital information exchanges related to international trade in goods and services.

Design/methodology/approach

The authors obtained quantitative data about Web-related data flows between countries and regions using Telegeography data on “Server Location as a Percentage of Top Websites.” They then explore how those flows are correlated to trade in goods.

Findings

Web traffic is highly transnational. More than half of the top 100 websites in 9 of the world’s 13 sub-regions are hosted in the USA. More than 15 per cent of the top 100 websites in 9 of the 13 subregions are hosted in Western Europe. East Asia has the largest negative balance in the relationship between incoming and outgoing Web requests. The authors found a very strong negative correlation (−0.878) between Web traffic balances and the balance of trade in goods across all subregions. A similarly strong positive correlation was found with services trade; however, the incompleteness of the data does not allow for strong conclusions yet.

Research limitations/implications

Further research is needed to correlate Web traffic flows with capital flows. The authors also do not have a well-developed theory to explain the strong negative correlation between information flows and goods trade.

Practical implications

The data and analysis have useful implications for digital economy policy. It indicates that digital protectionism of the sort practice by China may succeed in increasing domestic producers’ share of Web requests, but does not make them globally competitive. The strong negative correlation between the balance of unpriced Web information and the balance of trade in goods indicates interdependence rather than domination, challenging narratives that information flow imbalances are caused by market power of the big platforms.

Social implications

The paper demonstrates the degree to which unpriced digital exchanges are transnational and how various countries are more or less globally competitive in the supply of information that the rest of the world finds attractive.

Originality/value

No other published papers have used the data on website traffic data, and previous research has not explored empirically the correlation between information flows and goods trade.
Heat transfer in a porous cavity in presence of square solid block
Authors: Nandalur Ameer Ahamad , Kamangar Sarfaraz , Badruddin Irfan Anjum
Published: December 2018

Purpose

The purpose of this study was to analyze the heat transfer in a square porous cavity that has a solid block placed at its center. The prime focus of this study is to investigate the effect of size of the square solid block and other physical parameters on the heat transfer rate from the hot surface into the porous medium. The left vertical surface of cavity is maintained at a hot temperature and the right vertical surface at a cool temperature, Tc. The finite element method is used to simplify the governing equations and is solved iteratively. It is noted that the size of the solid block plays a vital role in dictating the heat transfer from the hot surface to porous medium.

Design/methodology/approach

The current work is based on finite element formulation of a square porous cavity that has a solid square block placed at its center. Governing equations were solved iteratively.

Findings

The size of the solid block has a pronounced effect on the heat transfer behavior inside the porous cavity.

Originality/value

This study highlights the heat transfer due to a conducting square solid block at mid of porous cavity.
Positivity at the workplace
Authors: Shahid Sehrish , Muchiri Michael K.
Published: December 2018

Purpose

Recognising the value of positive organisational behaviour at the workplace, this paper aims to provide a major review of the current state of research on positivity, and subsequently proposes new pathways for more theory building relating to important constructs conceptually related to positivity. Following the integration of emerging but disparate research on workplace positivity and related concepts, the paper develops a conceptual framework depicting the relationships amongst authentic leader behaviours, organisational virtuousness, psychological capital, thriving and job performance.

Design/methodology/approach

The paper offers a systematic critical review of published studies representing the literature addressing authentic leadership, organisational virtuousness, thriving, psychological capital and job performance. The paper relied on computerised keyword searches in the main business source databases of Emerald, ProQuest, ScienceDirect, EBSCOhost and SpringerLink.

Findings

This paper leads to a conceptual framework proposing direct relationships between authentic leadership, psychological capital, organisational virtuousness and job performance. Further, authentic leadership is proposed to potentially nurture organisational virtuousness, psychological capital, employee thriving and job performance, given the theoretical linkages between these conceptually relevant variables related to positivity. Additionally, organisational virtuousness and psychological capital are projected to mediate the relationship between authentic leadership and employee thriving. Finally, organisational virtuousness, psychological capital and employee thriving are designated as mediators of the relationship between authentic leadership and job performance.

Research limitations/implications

This paper proposes a conceptual framework focusing on one form of positive leader behaviour and also assumes specific causal pathways using a positivistic research approach to understanding the leadership–performance relationship. The paper did not examine all possible antecedents of positivity at the workplace.

Practical implications

The proposed conceptual framework should form the basis of many organisational interventions, especially in relation to boosting authentic leadership, organisational virtuousness, psychological capital, employee thriving and job performance. By suggesting the association between authentic leadership, psychological capital and organisational virtuousness, this paper highlights potential benefits from effective leaders’ commitment to enhancing psychological capital and organisational virtuousness and engendering thriving behaviour and job performance.

Originality/value

This novel paper has the potential to stimulate the empirical studies on workplace positivity through the association of authentic leadership, psychological capital, organisational virtuousness and thriving.
The impact of 360 feedback appraisal system on organizational justice and sustainability
Authors: El Haddad Rania , Karkoulian Silva , Nehme Rabih
Published: December 2018

Purpose

This paper aims to extend previous results demonstrating a statistically significant causal relationship between the implementation of 360-degree feedback in an organization and employees’ perceptions of organizational justice. It explores the sustainability of this justice, ultimately making it an integral part of the organizational culture. The paper examines whether the previous model (based on relationships among 360-degree feedback, organizational justice and sustainability of organizational justice) is invariant across different levels of management (i.e. operational and top/middle managers) and across a group of female versus male employees.

Design/methodology/approach

Structural equation modeling multigroup analysis and invariance tests were conducted with a cross-sectional sample of 400 employees in various positions in home appliances and electronics organizations.

Findings

The results further sustain/contest previous findings on the relationships among appraisal, organizational justice and sustainability among respondents of different genders and at different managerial levels. The results also provide significant practical implications. Top managers and supervisors can incorporate gender and managerial level differences identified in this study to modify their management styles and appraisal techniques to install high levels of organizational justice and achieve a competitive edge through the sustained levels of this organizational justice.

Originality/value

This study is the first to explore the impact of implementing a 360-degree appraisal system on employees’ perceptions of justice, while taking into consideration gender differences, i.e. whether males or females tend to perceive different types of justice within the organization and whether they differ in the way that they react to the appraisal system being implemented within the workplace. Given all the positive traits associated with a 360-feedback appraisal system, the way that this feedback is viewed and interpreted by employees can differ according to the employee’s rank within the organization, i.e. whether he/she belongs to top/middle management team or the operational/front-line management team.
The relationship between tax avoidance and firm value with income smoothing
Authors: Akbari Farzana , Salehi Mahdi , Bagherpour Vlashani Mohammad Ali
Published: December 2018

Purpose

The purpose of this paper is to investigate the relationship between tax avoidance, firm value and managerial ability in Tehran Stock Exchange and Over the Counter (OTC), according to the related theoretical foundations.

Design/methodology/approach

To calculate the managerial ability in this study, DEA is used based on the accounting data, company profile and industry and the hypotheses are estimated in a period of 12 years during 2004 to 2015 in TSE and OTC. Within the previous studies, to test the hypotheses, only the classical regression method is usually used and most of the times the effect of macroeconomic variables is not considered. In this study, in a new act for testing the hypotheses, three statistical methods are used, that is, classical regression models, mixed effects multilevel models and Bayesian multilevel models. Also in this study, the test of structural change is used to control the effects of macroeconomic variables, like inflation and other economic and political influence, on the results.

Findings

The results of these three methods show that the effect of income smoothing and earnings quality on the relationship between tax avoidance and firm value are significant.

Originality/value

Although several studies are conducted so far on the subject of the study, the current study is the first project which combined Bayesian econometrics. Therefore, the results are quite noble.
Team psychological safety and team performance
Authors: Jha Sumi
Published: December 2018

Purpose

The purpose of this paper is to examine the relationships between team psychological safety and team performance and to test the mediating effect of learning orientation and moderating effect of psychological empowerment on that relationship.

Design/methodology/approach

Data were collected from 50 teams and 345 team members from 20 different organizations. The moderated mediation analysis of psychological empowerment was tested using hierarchical regression analysis (PROCESS Macro) in SPSS.

Findings

The results show that higher the psychological empowerment, higher is the effect of psychological safety and learning orientation on team performance. Results supported the moderated mediation analysis of psychological empowerment.

Practical implications

Given that psychological empowerment and learning orientation of team members will effect team performance, organizational efforts to foster psychological empowerment should be rewarding. Focusing on channelizing team psychological safety to improve team members’ relationship, openness and comfort with each other will increase team performance.

Originality/value

The study incorporated learning orientation and psychological empowerment to redefine the relationship between psychological safety and team performance.
Erosion studies of cermet-coated ASTM A36 steel
Authors: Shibe Vineet , Chawla Vikas
Published: December 2018

Purpose

This paper aims to perform the solid particle erosion studies in simulated coal-fired boiler conditions with a view to compare the erosion behavior of two different types of detonation gun (D-Gun) sprayed cermet coating powders, that is, WC-12%Co and Cr3C2-25%NiCr on ASTM A36 steel and bare (uncoated) ASTM A36 steel.

Design/methodology/approach

Erosion studies were performed using an air jet erosion test rig at impingement angles of 45°, 60° and 90°. During the erosion studies weight loss, erosion rates in terms of volume loss (mm3/g) and measurement of erosion profiles were determined using optical profilometer.

Findings

Both cermet coatings had successfully protected the ASTM A36 steel from erosion at impingement angles of 45°, 60° and 90°. In the case of bare ASTM A36 steel, the erosion rates were maximal at an impingement angle of 45° and minimal at an impingement angle of 90°, thus depicting the peculiar erosion behavior of ductile materials. WC-12%Co coated specimens exhibited erosion behavior that is closer to the behavior of ductile materials. Cr3C2-25%NiCr coated specimens exhibited the maximum erosion rate at an impingement angle of 90° and minimum at an impingement angle of 45°, hence depicting the typical behavior of brittle materials.

Practical implications

It is expected that these results will contribute to the improvement of erosion resistance of induced draft fans, by the application of D-Gun sprayed WC-12%Co and Cr3C2-25%NiCr cermet coatings.

Originality/value

This paper evaluates the solid particle erosion behavior of bare and cermet-coated ASTM A36 steel which will be helpful in choosing the suitable cermet coating for induced draft fan applications.
The investigation of tribological behavior of carbon fiber-reinforced composite materials
Authors: Kaya İsmail , Parlar Zeynep
Published: December 2018

Purpose

The tribological behavior of composites varies on matrices materials, the reinforcement material and the direction of reinforcement materials. The purpose of this study is to examine the effects of fiber orientation on the tribological properties of carbon fiber–reinforced epoxy composite.

Design/methodology/approach

The experiments were carried out with a pin-on-ring tribometer. The tests were executed according to three different parameters: load, sliding velocity and direction of reinforcement. Loads measuring 92 N and 150 N were applied at sliding velocities of 1 and 2 m/s, in parallel, antiparallel and normal directions of fiber reinforcements. The frictional force was read every 500 m of sliding distance. To calculate specific wear rate, the mass of the samples was measured before and after each experiment. Moreover, temperature was measured every 1000 m of sliding distance via three-point infrared thermometer, to examine the effect of temperature variations. The sample surfaces were also examined in optic microscope after the experiments. Higher friction coefficient values were obtained in the normal direction-oriented carbon fiber specimen.

Findings

Comparing the friction coefficient values, antiparallel and parallel direction-oriented carbon fiber specimens gave lower friction coefficient values. The increase of sliding velocity and normal load resulted in the increase of surface temperature and this lead to the increase of friction coefficient.

Originality/value

This study shows the effects of fiber orientation on the tribological behavior of carbon fiber–reinforced epoxy composite. According to fiber orientations, relatively moving counter surfaces of this material shows different tribological behaviors.
Design and optimisation of advanced bearing system for ultra-precision plastic electronics production systems
Authors: Zhao Gang
Published: December 2018

Purpose

The paper aims to use aluminium alloy to substitute steel as the main material of ultra-precision hydro-static bearing system for an ultra-precision plastic electronics production system to lower the manufacturing cost. The total cost of diamond turning and nickel-based electroless coating of an aluminium alloy bearing is expected to be less than the cost of manufacturing a stainless steel bearing.

Design/methodology/approach

The paper used a large amount of theoretical calculation to obtain optimal specifications of the bearing system. ANSYS modelling was selected to simulate the deflection of the bearing shaft under high oil pressure. Hundreds of measurements were conducted after the bearing had been manufactured.

Findings

The paper provides industrial application insights on using aluminium alloy with a high-quality nickle-based electroless coating as a successful substitution of stainless steel. This created a more economic hydro-static bearing system.

Research limitations/implications

Because of the time limit, different rotational speed tests shall be conducted in the future.

Practical implications

The paper provides implications for the application of nickel-based electroless coating to improve the surface property and bending strength of aluminium alloy, as well as classifying ultra-precision diamond turning as an economic finishing process.

Originality/value

This paper has identified the importance of aluminium alloy with a nickel-based electroless coating as the substitution of stainless steel in a precision hydro-static bearing system.
The bottleneck dilemma at headquarters: new product development for local markets
Authors: Kim Heejin , Kim Seong-Young
Published: December 2018

Purpose

This paper aims to explore the condition under which a multinational company’s organizational headquarters influences its development of a localized overseas product.

Design/methodology/approach

Drawing on interviews with members at a Japanese multinational company’s headquarters, the authors’ analysis shows two invisible bottlenecks in the headquarters organization: the psychological resistance of the headquarters’ engineers and a lack of communication channels between the headquarters and overseas units.

Findings

The authors’ analysis shows two invisible bottlenecks in the headquarters organization: the psychological resistance of the headquarters’ engineers and a lack of communication channels between the headquarters and overseas units.

Originality/value

The authors’ research provides a rare glimpse into the ways that the conditions of local knowledge and foreign subsidiaries and the organizational conditions of home country headquarters are intertwined with one another during a period of product development.
Energy absorbing capability of additive manufactured multi-material honeycomb structure
Authors: Rajendra Boopathy Vijayanand , Sriraman Anantharaman , G. Arumaikkannu
Published: December 2018

Purpose

The present work aims in presenting the energy absorbing capability of different combination stacking of multiple materials, namely, Vero White and Tango Plus, under static and dynamic loading conditions.

Design/methodology/approach

Honeycomb structures with various multi-material stackings are fabricated using PolyJet 3D printing technique. From the static and dynamic test results, the structure having the better energy absorbing capability is identified.

Findings

It is found that from the various stacking combinations of multiple materials, the five-layered (5L) sandwich multi-material honeycomb structure has better energy absorbing capability.

Practical implications

This multi-material combination with a honeycomb structure can be used in the application of crash resistance components such as helmet, knee guard, car bumper, etc.

Originality/value

Through experimental work, various multi-material honeycomb structures and impact resistance of single material clearly indicated the inability to absorb impact loads which experiences a maximum force of 5,055.24 N, whereas the 5L sandwich multi-material honeycomb structure experiences a minimum force of 1,948.17 N, which is 38.5 per cent of the force experienced by the single material. Moreover, in the case of compressive resistance, 2L sandwich multi-material honeycomb structure experiences a maximum force of 5,887.5 N, whereas 5L sandwich multi-material honeycomb structure experiences a minimum force of 2,410 N, which is 40.9 per cent of the force experienced by two-layered (2L) sandwich multi-material honeycomb structure. In this study, the multi-material absorbed most of the input energy and experienced minimum force in both compressive and impact loads, thus showing its energy absorbing capability and hence its utility for structures that experience impact and compressive loads. A maximum force is required to deform the single and 2L material in terms of impact and compressive load, respectively, under maximum stiffness conditions.