bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct photoresponsive inhibition of a p53-like transcription activation domain in PIF3 by Arabidopsis phytochrome B
Authors: Yoo Chan Yul , Sang Qing , He Jiangman , Qiu Yongjian , Long Lingyun , Kim Ruth Jean-Ae , Chong Emily G. , Hahm Joseph , Morffy Nicholas , Zhou Pei , Strader Lucia C. , Nagatani Akira , Mo Beixin , Chen Xuemei , Chen Meng
Published: May 2021

Phytochrome B (PHYB) triggers diverse light responses in Arabidopsis by binding to a group of antagonistically acting PHYTOCHROME-INTERACTING transcription FACTORs (PIFs) to promote PIF degradation, consequently downregulating PIF target genes. However, whether PHYB directly controls the transactivation activity of PIFs remains ambiguous. Here we show that the prototypic PIF, PIF3, possesses a p53-like transcription activation domain (TAD) consisting of a sequence-specific, hydrophobic activator motif surrounded by acidic residues. A PIF3mTAD mutant in which the activator motif is replaced with alanines fails to activate PIF3 target genes in Arabidopsis in dark, light, and shade conditions, validating the in vivo functions of the PIF3 TAD. Intriguingly, binding of PHYB’s N-terminal photosensory module to the PHYB-binding site adjacent to the TAD inhibits its transactivation activity. These results unveil a photoresponsive transcriptional switching mechanism in which photoactivated PHYB directly masks the transactivation activity of PIF3. Our study also suggests the unexpected conservation of sequence-specific TADs between the animal and plant kingdoms.
Rapid analysis of strigolactone receptor activity in aNicotiana benthamiana dwarf14mutant
Authors: White Alexandra R.F. , Mendez Jose A. , Khosla Aashima , Nelson David C.
Published: May 2021

DWARF14 (D14) is an ɑ/β-hydrolase and receptor for the plant hormone strigolactone (SL) in angiosperms. Upon SL perception, D14 works with MORE AXILLARY GROWTH2 (MAX2) to trigger polyubiquitination and degradation of DWARF53(D53)-type proteins in the SUPPRESSOR OF MAX2 1-LIKE (SMXL) family. We used CRISPR-Cas9 to generate knockout alleles of the two homoeologousD14genes in theNicotiana benthamianagenome. TheNbd14a,bdouble mutant had several phenotypes that are consistent with the loss of SL perception in other plants, including increased axillary bud outgrowth, reduced height, shortened petioles, and smaller leaves. A ratiometric fluorescent reporter system was used to monitor degradation of SMXL7 fromArabidopsis thaliana(AtSMXL7) after transient expression inN. benthamianaand treatment with the strigolactone analog GR24. AtSMXL7 was degraded after treatment with GR245DS, which has the stereochemical configuration of SLs, as well as its enantiomer GR24ent-5DS. InNbd14a,bleaves, AtSMXL7 abundance was unaffected by GR24. Transient coexpression of AtD14 with the AtSMXL7 reporter inNbd14a,brestored the degradation response to GR24, but required an active catalytic triad. With this platform, we evaluated the ability of several AtD14 mutants that had not been characterized in plants to target AtSMXL7 for degradation.
Structure supports function: informing directed and dynamic functional connectivity with anatomical priors
Authors: Pascucci David , Rubega Maria , Rué-Queralt Joan , Tourbier Sebastien , Hagmann Patric , Plomp Gijs
Published: May 2021

The dynamic repertoire of functional brain networks is constrained by the underlying topology of structural connections: the lack of a direct structural link between two brain regions prevents direct functional interactions. Despite the intrinsic relationship between structural (SC) and functional connectivity (FC), integrative and multimodal approaches to combine the two remain limited, especially for electrophysiological data. In the present work, we propose a new linear adaptive filter for estimating dynamic and directed FC using structural connectivity information as priors. We tested the filter in rat epicranial recordings and human event-related EEG data, using SC priors from a meta-analysis of tracer studies and diffusion tensor imaging metrics, respectively. Our results show that SC priors increase the resilience of FC estimates to noise perturbation while promoting sparser networks under biologically plausible constraints. The proposed filter provides intrinsic protection against SC-related false negatives, as well as robustness against false positives, representing a valuable new method for multimodal imaging and dynamic FC analysis.
Ultraviolet-A light increases mitochondrial anti-viral signaling protein in confluent human tracheal cells even at a distance from the light source
Authors: Leite Gabriela , Rezaie Ali , Mathur Ruchi , Barlow Gillian , Melmed Gil Y. , Pimentel Mark
Published: May 2021

Mitochondrial antiviral signaling (MAVS) protein mediates innate antiviral responses, including responses to certain coronaviruses such as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). We have previously shown that ultraviolet-A (UVA) therapy can prevent virus-induced cell death in human ciliated tracheal epithelial cells (HTEpC) infected with coronavirus-229E, and that UVA treatment results in an increase in intracellular levels of MAVS. In this study, we set out to determine the mechanisms by which UVA light can activate MAVS, and whether local UVA light application can activate MAVS at locations distant from the light source (such as via cell-to-cell communication). MAVS levels were compared in HTEpC exposed to 2 mW/cm2 narrow band (NB)-UVA for 20 minutes and in unexposed controls, at 30-40% and at 100% confluency. MAVS levels were also compared in unexposed HTEpC treated with supernatants or lysates from UVA-exposed cells or from unexposed controls. Also, MAVS was assessed in different sections of confluent monolayer plates where only one section was exposed to NB-UVA. The results show that UVA increases the expression of MAVS protein. Cells in a confluent monolayer exposed to UVA were able to confer an elevation in MAVS in cells adjacent to the exposed section, and even cells in the most distant sections not exposed to UVA. In this study, human ciliated tracheal epithelial cells exposed to UVA demonstrate increased MAVS protein, and also appear to transmit this influence to distant confluent cells not exposed to light.
easyXpress: An R package to analyze and visualize high-throughput C. elegans microscopy data generated using CellProfiler
Authors: Nyaanga Joy , Crombie Timothy A. , Widmayer Samuel J. , Andersen Erik C.
Published: May 2021

High-throughput imaging techniques have become widespread in many fields of biology. These powerful platforms generate large quantities of data that can be difficult to process and visualize efficiently using existing tools. We developed easyXpress to process and review C. elegans high-throughput microscopy data in the R environment. The package provides a logical workflow for the reading, analysis, and visualization of data generated using CellProfiler’s WormToolbox. We equipped easyXpress with powerful functions to customize the filtering of noise in data, specifically by identifying and removing objects that deviate from expected animal measurements. This flexibility in data filtering allows users to optimize their analysis pipeline to match their needs. In addition, easyXpress includes tools for generating detailed visualizations, allowing the user to interactively compare summary statistics across wells and plates with ease. Researchers studying C. elegans benefit from this streamlined and extensible package as it is complementary to CellProfiler and leverages the R environment to rapidly process and analyze large high-throughput imaging datasets.
Machine learning algorithms can predict tail biting outbreaks in pigs using feeding behaviour records
Authors: Ollagnier Catherine , Kasper Claudia , Wallenbeck Anna , Keeling Linda , Bee Giuseppe , Bigdeli Siavash A.
Published: May 2021

Tail biting is a damaging behaviour that impacts the welfare and health of pigs. Early detection of precursor sig outbreaks, using feeding behaviour data recorded by an electronic feeder. Prediction capacities of seven machine learning algorithms (Generalized Linear Model with Stepwise Feature Selection, random forest, Support Vector Machines with Radial Basis Function Kernel, Bayesian Generalized Linear Model, Neural network, K-nearest neighbour, and Partial Least Squares Discriminant Analysis) were evaluated from daily feeding data collected from 65 pens originating from two herds of grower-finisher pigs (25-100kg), in which 27 tail biting events occurred. Data were divided into training and testing data in two different ways, either by randomly splitting data into 75% (training set) and 25% (testing set), or by randomly selecting pens to constitute the testing set. In the first data splitting, the model is regularly updated with previous data from the pen, whereas in the second data splitting, the model tries to predict for a pen that it has never seen before. The K-nearest neighbour algorithm was able to predict 78% of the upcoming events with an accuracy of 96%, when predicting events in pens for which it had previous data. The detection of events for unknown pens was less sensitive, and the neural network model was able to detect 14% of the upcoming events with an accuracy of 63%. Our results indicate that machine learning models can be considered for implementation into automatic feeder systems for real-time prediction of tail biting events.
Unravelling consensus genomic regions conferring leaf rust resistance in wheat via meta-QTL analysis
Authors: Aduragbemi Amo , Soriano Jose Miguel
Published: May 2021

Leaf rust, caused by the fungusPuccinia triticinaErikss (Pt), is a destructive disease affecting wheat and a threat to food security. Developing resistant varieties represents a useful method of disease control, and thus, understanding the genetic basis for leaf rust resistance is required. To this end, a comprehensive bibliographic search for leaf rust resistance quantitative trait loci (QTLs) was performed, and 393 QTLs were collected from 50 QTL mapping studies. Afterwards, a consensus map with a total length of 4567 cM consisting of different types of markers (SSR, DArT, Chip-based SNP markers and SNP markers from GBS) was used for QTL projection, and meta-QTL analysis was performed on 320 QTLs. A total of 75 genetic map positions (gmQTLs) were discovered and refined to 15 high confidence mQTLs (hcmQTLs). The candidate genes discovered within the hcmQTL interval were then checked for differential expression using data from three transcriptome studies, resulting in 92 differentially expressed genes (DEGs). The expression of these genes in various leaf tissues during wheat development was explored. This study provides insight into leaf rust resistance in wheat and thereby provides an avenue for developing resistant varieties by incorporating the most important hcmQTLs.
Elongation factor ELOF1 drives transcription-coupled repair and prevents genome instability
Authors: Geijer Marit E , Zhou Di , Selvam Kathiresan , Steurer Barbara , Evers Bastiaan , Mukherjee Chirantani , Cugusi Simona , van Toorn Marvin , van der Woude Melanie , Gong Wenzhi , Janssens Roel , Raams Anja , Lebbink Joyce HG , Geverts Bart , Plummer Dalton A , Bezstarosti Karel , Theil Arjan F , Mitter Richard , Houtsmuller Adriaan B , Vermeulen Wim , Demmers Jeroen AA , Li Shisheng , Lans Hannes , Bernards René , Svejstrup Jesper Q , Chaudhuri Arnab Ray , Wyrick John J , Marteijn Jurgen A
Published: May 2021

Correct transcription is crucial for life. However, DNA damage severely impedes elongating RNA Polymerase II (Pol II), causing transcription inhibition and transcription-replication conflicts. Cells are equipped with intricate mechanisms to counteract the severe consequence of these transcription-blocking lesions (TBLs). However, the exact mechanism and factors involved remain largely unknown. Here, using a genome-wide CRISPR/cas9 screen, we identified elongation factor ELOF1 as an important new factor in the transcription stress response upon DNA damage. We show that ELOF1 has an evolutionary conserved role in Transcription-Coupled Nucleotide Excision Repair (TC-NER), where it promotes recruitment of the TC-NER factors UVSSA and TFIIH to efficiently repair TBLs and resume transcription. Additionally, ELOF1 modulates transcription to protect cells from transcription-mediated replication stress, thereby preserving genome stability. Thus, ELOF1 protects the transcription machinery from DNA damage by two distinct mechanisms.
Maxicircle architecture and evolutionary insights intoTrypanosoma cruzicomplex
Authors: Berná Luisa , Greif Gonzalo , Pita Sebastián , Faral-Tello Paula , Díaz-Viraqué Florencia , De Souza Rita De Cássia Moreira , Vallejo Gustavo Adolfo , Alvarez-Valin Fernando , Robello Carlos
Published: May 2021

We sequenced maxicircles fromT. cruzistrains representative of the species evolutionary diversity by using long-read sequencing, which allowed us to uncollapse their repetitive regions, finding that their real lengths range from 35 to 50 kb.T. cruzimaxicircles have a common architecture composed of four regions: coding region (CR), AT-rich region, short (SR) and long repeats (LR). Distribution of genes, both in order and in strand orientation are conserved, being the main differences the presence of deletions affecting genes coding for NADH dehydrogenase subunits, reinforcing biochemical findings that indicate that complex I is not functional inT. cruzi. Moreover, the presence of complete minicircles into maxicircles of some strains lead us to think about the origin of minicircles. Finally, a careful phylogenetic analysis was conducted using coding regions of maxicircles from up to 29 strains, and 1023 single copy nuclear genes from all of the DTUs, clearly establishing that taxonomicallyT. cruziis a complex of species composed by group 1 that contains clades A, B and D, and group 2 containing clade C. No significant differences were found in hybrid strains that justify the existence of TcV and Tc VI as separate clades: our results indicate that a unique event of hybridization between TcII and TcIII occurred. Three variants of maxicircles exist inT. cruzi: a, b and c, in correspondence with clades A, B, and C from mitochondrial phylogenies. While A and C carry maxicircles a and c respectively, both clades B and D carry b maxicircle variant; hybrid strains also carry the b- variant. We then propose a new nomenclature that is self-descriptive and makes use of both the phylogenetic relationships and the maxicircle variants present inT. cruzi.
Development and genetics of red coloration in the zebrafish relativeDanio albolineatus
Authors: Huang Delai , Lewis Victor M. , Toomey Matthew B. , Corbo Joseph C. , Parichy David M.
Published: May 2021

Animal pigment patterns play important roles in behavior and, in many species, red coloration serves as an honest signal of individual quality in mate choice. AmongDaniofishes, some species develop erythrophores, pigment cells that contain red ketocarotenoids, whereas other species, like zebrafish (D. rerio) only have yellow xanthophores. Here, we use pearl danio (D. albolineatus) to assess the developmental origin of erythrophores and their mechanisms of differentiation. We show that erythrophores in the fin ofD. albolineatusshare a common progenitor with xanthophores and maintain plasticity in cell fate even after differentiation. We further identify the predominant ketocarotenoids that confer red coloration to erythrophores and use reverse genetics to pinpoint genes required for the differentiation and maintenance of these cells. Our analyses are a first step towards defining the mechanisms underlying the development of erythrophore-mediated red coloration inDanioand reveal striking parallels with the mechanism of red coloration in birds.
Spatiotemporal single cell transcriptomic analysis of human gut macrophages reveals multiple functional and niche-specific subsets
Authors: Domanska Diana , Majid Umair , Karlsen Victoria T. , Merok Marianne A. , Beitnes Ann-Christin , Yaqub Sheraz , Bækkevold Espen S. , Jahnsen Frode L.
Published: May 2021

Macrophages are a heterogeneous population of cells involved in tissue homeostasis, inflammation and cancer. Although macrophages are densely distributed throughout the human intestine, our understanding of how gut macrophages maintain tissue homeostasis is limited. Here we show that colonic lamina propria (LpM) and muscularis macrophages (MM) consist of monocyte-like cells that differentiate into multiple transcriptionally distinct subsets. LpM comprise subsets with proinflammatory properties and subsets high antigen presenting and phagocytic capacity. The latter are strategically positioned close to the surface epithelium. Most MM differentiate along two trajectories; one that upregulates genes associated with immune activation and angiogenesis, whereas the other upregulates genes associated with neuronal homeostasis. Importantly, MM are located adjacent to neurons and vessels. Cell-cell interaction and gene network analysis indicated that survival, migration, transcriptional reprogramming, and niche-specific localization of LpM and MM are controlled by an extensive interaction with tissue-resident cells and a few key transcription factors.
Kinase independent function of PI3Kγ modulates calcium re-uptake by regulating phospholamban function
Authors: Mohan Maradumane L. , Witherow Connner P. , Papay Robert S. , Sun Yu , Stenson Kate , Prasad Sathyamangla V. Naga
Published: May 2021

Rationale

Genetic deletion of Phosphoinositide 3-kinase (PI3Kγ) in mice (PI3Kγ−/−) results in increased cAMP levels and enhanced ventricular rate/contractility. Whether PI3Kγ plays a role in cardiac contractility by altering intracellular calcium recycling is not known.

Objective

To understand the mechanism of PI3Kγ mediated regulation of cardiac contractility.

Methods and Results

Caffeine treatment of adult cardiomyocytes from PI3Kγ−/− mice showed significantly reduced calcium reuptake by sarcoendoplasmic reticulum (SR) indicating that PI3Kγ locally regulates SR function. This resulted in elevated levels of intracellular calcium for prolonged period following caffeine. Our findings show that delayed re-uptake of calcium was caused by changes in phosphorylation of phospholamban (PLN), a major regulator of SR calcium reuptake. PI3Kγ−/− cardiomyocytes show significantly reduced PLN phosphorylation due to increase in PLN-associated protein phosphatase (PP) activity as reflected by decreased demethylated-PP2A. Consistently, the altered calcium regulation in the cardiomyocytes of PI3Kγ−/− can be restored by inhibition of PP by okadaic acid. Unexpectedly, cardiomyocyate-specific overexpression of kinase-dead PI3Kγ PI3Kγinact) in the global PI3Kγ−/− cardiomyocytes normalized caffeine induced calcium reuptake, restored PLN phosphorylation, and decreased PLN-associated PP activity reflected by increased demethylated-PP2A.

Conclusions

These studies bring-to-fore an unrecognized regulation of PLN by PI3Kγ through PP2A with implications in deleterious cardiac remodeling as PI3Kγ is significantly upregulated following cardiac stress.
Engineered type six secretion systems deliver active exogenous effectors and Cre recombinase
Authors: Hersch Steven J. , Lam Linh , Dong Tao G.
Published: May 2021

Genetic editing has revolutionized biotechnology but delivery of endonuclease genes as DNA can lead to aberrant integration or overexpression, leading to off-target effects. Here we develop a mechanism to deliver Cre recombinase as a protein by engineering the bacterial type six secretion system (T6SS). Using multiple T6SS fusion proteins, Aeromonas dhakensis or attenuated Vibrio cholerae donor strains, and a gain-of-function cassette for detecting Cre recombination, we demonstrate successful delivery of active Cre directly into recipient cells. Most efficient transfer was achieved using a truncated version of PAAR2 from V. cholerae, resulting in a relatively small (118 amino acid) ‘delivery tag’. We further demonstrate the versatility of this system by delivering an exogenous effector, TseC, enabling V. cholerae to kill Pseudomonas aeruginosa. This implicates that P. aeruginosa is naturally resistant to all native effectors of V. cholerae and that the TseC chaperone protein is not required for its activity. Moreover, it demonstrates that the engineered system can improve T6SS efficacy against specific pathogens, proposing future application in microbiome manipulation or as a next-generation antimicrobial. Inexpensive and easy to produce, this protein delivery system has many potential applications ranging from studying T6SS effectors to genetic editing.

Importance

Delivery of protein-based drugs, antigens, and gene-editing agents has broad applications. The type VI protein secretion system (T6SS) can target both bacteria and eukaryotic cells and deliver proteins of diverse size and function. Here we harness the T6SS to successfully deliver Cre recombinase to genetically edit bacteria without requiring the introduction of exogenous DNA into the recipient cells. This demonstrates a promising advantage over current genetic editing tools that require transformation or conjugation of DNA. The engineered secretion tag can also deliver a heterologous antimicrobial toxin that kills an otherwise unsusceptible pathogen, Pseudomonas aeruginosa. These results demonstrate the potential of T6SS-mediated delivery in areas including genome editing, killing drug-resistant pathogens, and studying toxin functions.
Colicin-mediated transport of DNA through the iron transporter FepA
Authors: Cohen-Khait Ruth , Harmalkar Ameya , Pham Phuong , Webby Melissa N. , Housden Nicholas G. , Elliston Emma , Hopper Jonathan TS. , Mohammed Shabaz , Robinson Carol V. , Gray Jeffrey J. , Kleanthous Colin
Published: May 2021

Colicins are protein antibiotics used by bacteria to eliminate competing Escherichia coli. Colicins frequently exploit outer membrane (OM) nutrient transporters to penetrate through the strictly impermeable bacterial cellular envelope. Here, applying live-cell fluorescence imaging we were able to follow colicin B (ColB) into E. coli and localize it within the periplasm. We further demonstrate that single-stranded DNA coupled to ColB is also transported into the periplasm, emphasizing that the import routes of colicins can be exploited to carry large cargo molecules into bacteria. Moreover, we characterize the molecular mechanism of ColB association with its OM receptor FepA, applying a combination of photo-activated crosslinking, mass spectrometry, and structural modeling. We demonstrate that complex formation is coincident with a large-scale conformational change in the colicin. Finally In vivo crosslinking experiments and supplementary simulations of the translocation process indicate that part of the colicin engages active transport by disguising itself to part of the cellular receptor.
Temporal fine structure influences voicing confusions for consonant identification in multi-talker babble
Authors: Viswanathan Vibha , Shinn-Cunningham Barbara G. , Heinz Michael G.
Published: May 2021

To understand the mechanisms of speech perception in everyday listening environments, it is important to elucidate the relative contributions of different acoustic cues in transmitting phonetic content. Previous studies suggest that the envelope of speech in different frequency bands conveys most speech content, while the temporal fine structure (TFS) can aid in segregating target speech from background noise. However, the role of TFS in conveying phonetic content beyond what envelopes convey for intact speech in complex acoustic scenes is poorly understood. The present study addressed this question using online psychophysical experiments to measure the identification of consonants in multi-talker babble for intelligibility-matched intact and 64-channel envelope-vocoded stimuli. Consonant confusion patterns revealed that listeners had a greater tendency in the vocoded (versus intact) condition to be biased toward reporting that they heard an unvoiced consonant, despite envelope and place cues being largely preserved. This result was replicated when babble instances were varied across independent experiments, suggesting that TFS conveys voicing information beyond what is conveyed by envelopes for intact speech in babble. Given that multi-talker babble is a masker that is ubiquitous in everyday environments, this finding has implications for the design of assistive listening devices such as cochlear implants.
Beat Perception in Polyrhythms: Time is Structured in Binary Units
Authors: Møller Cecilie , Stupacher Jan , Celma-Miralles Alexandre , Vuust Peter
Published: May 2021

In everyday life, we group and subdivide time to understand the sensory environment surrounding us. Our perceptual system establishes hierarchical structures by nesting different groups of time intervals. Organizing time in units such as diurnal rhythms, phrases, and beat patterns, is fundamental to everyday behavior, speech, and music. When listening to music, we extract rhythmic regularities to create a hierarchical metrical structure that enables us to predict the timing of the next events. Foot tapping and head bobbing to musical rhythms are observable evidence of this process. In the special case of polyrhythms, at least two metrical structures compete to become the reference for these temporal regularities, rendering several possible beats with which we can synchronize our movements. While there is general agreement that tempo, pitch, and loudness influence beat perception in polyrhythms, we focused on the yet neglected influence of beat subdivisions. In three online experiments, 300 participants listened to a range of polyrhythms and tapped their index fingers in time with the perceived beat. The polyrhythms consisted of two simultaneously presented isochronous pulse trains with different ratios (2:3, 2:5, 3:4, 3:5, 4:5, 5:6) and different tempi. For ratios 2:3 and 3:4, we additionally manipulated the pitch of the pulse trains. Results showed a highly robust influence of subdivision grouping on beat perception manifested as a propensity towards beats that are subdivided into two or four equally spaced units, as opposed to beats with three or more complex groupings of subdivisions. Additionally, lower pitched pulse trains were more likely to be perceived as the beat. Our findings suggest that subdivisions, not beats, are the basic unit of beat perception, and that the principle underlying the binary grouping of subdivisions reflects a propensity towards simplicity. This preference for simple grouping is widely applicable to human perception and cognition of time.
Human-robot skills transfer interface for UAV-based precision pesticide in dynamic environments
Authors: Zhou Xuanyi , He Jilin , Chen Dingping , Li Junsong , Jiang Chunshan , Ji Mengyuan , He Miaolei
Published: May 2021

Purpose

Nowadays, the global agricultural system is highly dependent on the widespread use of synthetic pesticides to control diseases, weeds and insects. The unmanned aerial vehicle (UAV) is deployed as a major part of integrated pest management in a precision agriculture system for accurately and cost-effectively distributing pesticides to resist crop diseases and insect pests.

Design/methodology/approach

With multimodal sensor fusion applying adaptive cubature Kalman filter, the position and velocity are enhanced for the correction and accuracy. A dynamic movement primitive is combined with the Gaussian mixture model to obtain numerous trajectories through the teaching of a demonstration. Further, to enhance the trajectory tracking accuracy under an uncertain environment of the spraying, a novel model reference adaptive sliding mode control approach is proposed for motion control.

Findings

Experimental studies have been carried out to test the ability of the proposed interface for the pesticides in the crop fields. The effectiveness of the proposed interface has been demonstrated by the experimental results.

Originality/value

To solve the path planning problem of a complex unstructured environment, a human-robot skills transfer interface is introduced for the UAV that is instructed to follow a trajectory demonstrated by a human teacher.
Optimal grasp force for robotic grasping and in-hand manipulation with impedance control
Authors: Li Xiaoqing , Chen Ziyu , Ma Chao
Published: May 2021

Purpose

The purpose of this paper is to achieve stable grasping and dexterous in-hand manipulation, the control of the multi-fingered robotic hand is a difficult problem as the hand has many degrees of freedom with various grasp configurations.

Design/methodology/approach

To achieve this goal, a novel object-level impedance control framework with optimized grasp force and grasp quality is proposed for multi-fingered robotic hand grasping and in-hand manipulation. The minimal grasp force optimization aims to achieve stable grasping satisfying friction cone constraint while keeping appropriate contact forces without damage to the object. With the optimized grasp quality function, optimal grasp quality can be obtained by dynamically sliding on the object from initial grasp configuration to final grasp configuration. By the proposed controller, the in-hand manipulation of the grasped object can be achieved with compliance to the environment force. The control performance of the closed-loop robotic system is guaranteed by appropriately choosing the design parameters as proved by a Lyapunove function.

Findings

Simulations are conducted to validate the efficiency and performance of the proposed controller with a three-fingered robotic hand.

Originality/value

This paper presents a method for robotic optimal grasping and in-hand manipulation with a compliant controller. It may inspire other related researchers and has great potential for practical usage in a widespread of robot applications.
Which intermediate import source is best for innovation in MNEs?
Authors: Ramírez-Alesón Marisa , Fernández-Olmos Marta
Published: May 2021

Purpose

This paper explores the importance of the importing intensity for different intermediate inputs depending on their source (internal sourcing or intra-firm trade versus external sourcing or foreign suppliers) for different types of innovation (product and process innovation) and applied to MNEs (foreign versus domestic).

Design/methodology/approach

The sample contains 2,448 firm-year observations (2006–2016) of firms located in Spain that belong to an MNE group. The authors applied a conditional mixed process to a panel recursive bivariate probit model with robust standard errors.

Findings

The authors obtained three key results. First, intermediate imports do not always contribute to improving innovation, since their effects vary depending on their source. Second, intermediate imports from foreign suppliers (external source) are more advantageous for product innovation than those from intra-firm trade (internal source). Third, intermediate imports from intra-firm trade are more important for process innovation than those from foreign suppliers. Thus, the impact of importing intermediate inputs on innovation is contingent on the source of the imports, the ownership of the MNE and the type of innovation.

Originality/value

The paper contributes to this topic with new insights and results for MNEs. It identifies which import source is best for innovation depending on the type of innovative result expected. Moreover, it helps to uncover simultaneity and causal relationships between product and process innovation, issues which have not previously been considered in the literature.
It is not a case of “one size fits all”: the need for customized HRM practices for employee engagement
Authors: Jose Geetha , M. Nimmi P. , Mampilly Sebastian Rupert
Published: May 2021

Purpose

This study seeks to evaluate the role of HRM practices in enhancing Employee Engagement, particularly at varying levels of perceived psychological safety.

Design/Methodology/Approach

Data collected through a questionnaire survey of 151 nurses are analyzed with warp-PLS structural equation modeling.

Findings

Perceived HRM practices lead to higher engagement levels. Psychological safety moderates the relationship between HRM practices and employee engagement inversely.

Originality/value

An un-preceded study examining the moderating role of Psychological safety on the instrumentality of HRM practices on engagement particularly among experienced medical care providers. Results suggest to provide customized HRM practices to experienced nurses in order to enhance their engagement levels.
On the forced convective flow inside thermal collectors enhanced by porous media: from macro to micro-channels
Authors: Dehghan Maziar , Azari Nesaz Zahra , Pourrajabian Abolfazl , Rashidi Saman
Published: May 2021

Purpose

Aiming at finding the velocity distribution profile and other flow characteristic parameters such as the Poiseuille (Po) number, this study aims to focus on the three-dimensional forced convective flow inside rectangular ducts filled with porous media commonly used in air-based solar thermal collectors to enhance the thermal performance. The most general model for the fluid flow (i.e. the non-linear Darcy–Brinkman–Forchheimer partial differential equation subjected to slip and no-slip boundary conditions) is considered.

Design/methodology/approach

The general governing equations are solved analytically based on the perturbation technique and the results are validated against numerical simulation study based on a finite-difference solution over a non-uniform but structured grid.

Findings

The analytical velocity distribution profile based on exponential functions for the above-mentioned general case is obtained, and accordingly, expressions for the Po are introduced. It is found that the velocity distribution tends to be uniform by increasing the aspect ratio of the duct. Moreover, a criterion for considering/neglecting the nonlinear drag term in the momentum equation (i.e. the Forchheimer term) is proposed. According to the sensitivity analysis, results show that the nonlinear drag term effects on the Nusselt number are important only in porous media with high Darcy numbers.

Originality/value

A general analytic solution for three-dimensional forced convection flows through rectangular ducts filled with porous media for the general model of Darcy–Brinkman–Forchheimer and the general boundary condition including both no-slip and slip-flow regimes is obtained. An analytic expression to calculate Po number is obtained which can be practical for engineering estimations and a basis for validation of numerical simulations. A criterion for considering/neglecting the nonlinear drag term in the momentum equation is also introduced.
COVID-19 and overconfidence bias: the case of developed, emerging and frontier markets
Authors: Shrotryia Vijay Kumar , Kalra Himanshi
Published: May 2021

Purpose

The main purpose of the present study is to delve into the overconfidence bias in global stock markets during both pre COVID-19 and COVID-19 phases.

Design/methodology/approach

The present study makes use of daily adjusted closing prices and volume of the broad market indices of 46 global stock markets over a period ranging from July 2015 till June 2020. The sample period is split into pre COVID-19 and COVID-19 phases. In order to test the overconfidence fallacy in the chosen stock markets, bivariate market-wide vector auto regression (VAR) models and impulse response functions (IRFs) have been employed in both phases.

Findings

A highly significant contemporaneous relationship between market return and volume appears to be more pronounced in the Japanese, US, Chinese and Vietnamese stock markets in the pre COVID-19 era for the relevant coefficients are positive and highly significant for most lags. Coming to the period of turbulence, the present study discovers strong overconfident behavior in the Chinese, Taiwanese, Turkish, Jordanian and Vietnamese stock markets during COVID-19 phase.

Practical implications

A stark finding is that none of the developed stock markets reveal strong overconfidence bias during pandemic, suggesting a loss or decline in the investors' confidence. Therefore, the regulators should try to regain the investors' trust and confidence in the markets by ensuring honest, fair and transparent practices. The money managers should reduce the transaction cost to encourage trading and educate investors to hold a well-diversified portfolio to mitigate risk in the long run. The governments may launch recovery packages focusing on sustaining and improving economic activities. Finally, a better investment culture may be built by the corporate houses through good corporate governance practices to regain lost trust.

Originality/value

The present study appears to be the very first attempt to gauge overconfidence bias in the wake of a recent COVID-19 pandemic.
Catastrophic supply chain disruptions and supply network changes: a study of the 2011 Japanese earthquake
Authors: Son Byung-Gak , Chae Sangho , Kocabasoglu-Hillmer Canan
Published: May 2021

Purpose

Catastrophic supply chain disruptions can significantly damage the operational and financial performance of firms. While a growing body of literature on supply network structures has studied what influences supply networks' vulnerability to supply chain disruptions and capability to recover from them, it remains unclear how supply network structures change after major supply chain disruptions. We aim to provide an understanding of how these changes occur.

Design/methodology/approach

Using a natural experiment approach and supply network data from Factset, this study investigates how firms' supply network structures change after experiencing the catastrophic supply chain disruptions caused by the 2011 Tohoku earthquake and tsunami in Japan. We capture post-earthquake supply network changes using the measures of degree centrality and ego network density.

Findings

The results of the analysis suggest that compared to unaffected firms, the affected firms experience changes in their supply network structures tending toward lower complexity measured by in-degree centrality, out-degree centrality and ego network density.

Originality/value

This study contributes to social network theory and the complex adaptive supply network literature by providing empirical evidence of structural changes in supply networks after catastrophic supply chain disruptions. A managerial contribution is made by providing a reflection on why these changes might be occurring and alert firms to the challenges of managing complexity in their supply networks.
Determinants of corruption in developing countries: case of Tunisia
Authors: Zouaoui Azzouz , Ben Arab Mounira , Alamri Ahmad Mohammed
Published: May 2021

Purpose

This paper aims to investigate the economic, political or sociocultural determinants of corruption in Tunisia.

Design/methodology/approach

To better understand the main determinants of corruption in Tunisia. This study uses The Bayesian Model Averaging (BMA) model, which allows us to include a large number of explanatory variables and for a shorter period.

Findings

The results show that economic freedom is the most important variable of corruption in Tunisia. In second place comes the subsidies granted by the government, which is one of the best shelters of corruption in Tunisia through their use for purposes different from those already allocated to them. Third, this paper finds the high unemployment rate, which, in turn, is getting worse even nowadays. The other three factors considered as causal but of lesser importance are public expenditures, the human development index (HDI) and education. Education, the HDI and the unemployment rate are all socio-economic factors that promote corruption.

Originality/value

The realization of this study will lead to triple net contributions. The first is to introduce explicitly and simultaneously political, social and economic determinants of corruption in developing countries. Second, unlike previous studies based on the simple and generalized regression model, the present research uses another novel and highly developed estimation method. More precisely, this study uses the BMA model, on the set of annual data for a period of 1998–2018. The third contribution of this research resides in the choice of the sample.
Selected factors related to behavior control by executive function in Thai preschool children with epilepsy
Authors: Panjatharakul Pawanrat , Phuphaibul Rutja , Wongvatunyu Suporn , Visudtibhan Anannit
Published: May 2021

Purpose

This descriptive correlational study describes behavior control by executive function (EF) and explores the relationship among age at seizure onset, duration of epilepsy, seizure frequency, number of antiepileptic drugs (AEDs), family income, the caregiver's education, home environment and behavior control by EF in preschool children with epilepsy.

Design/methodology/approach

The purposive sample was 69 caregivers of preschool children with epilepsy. Data were collected in two medical centers in Bangkok from June 2019 to February 2020. The research instruments constituted: (1) a sociodemographic and medical information form for children with epilepsy and the caregiver; (2) early childhood-home observation for the measurement of the environment (EC-HOME) inventory and (3) the behavior rating inventory of executive function-preschool version® (BRIEF-P). The data were analyzed using Pearson's product-moment correlation and Spearman's Rho correlation.

Findings

Most of the participants had quite high scores on home environment (mean = 44.35) and mildly elevated levels of EF deficit (mean = 61.04). The duration of epilepsy and the number of AEDs were positively correlated with behavior control by EF. Family income was negatively associated with behavior control by EF. However, age at seizure onset, seizure frequency, the caregiver's education and home environment had no association with behavior control by EF.

Originality/value

Preschool children with epilepsy have poor behavioral control by EF. Consequently, healthcare providers should promote interventions in children to control seizures and to decrease the factors that impact the development of EF.
A strategy development process for Smart Maintenance implementation
Authors: Lundgren Camilla , Bokrantz Jon , Skoogh Anders
Published: May 2021

Purpose

Technological advancements are reshaping the manufacturing industry toward digitalized manufacturing. Despite the importance of top-class maintenance in such systems, many industrial companies lack a clear strategy for maintenance in digitalized manufacturing. The purpose of this paper is to facilitate the implementation of maintenance in digitalized manufacturing by proposing a strategy development process for the Smart Maintenance concept.

Design/methodology/approach

This study is designed as a multiple-case study, where the strategy development in three industrial cases is analyzed. Several methods were used to collect data on the case companies' development of smart maintenance strategies. The data were analyzed with an inductive approach.

Findings

A process of strategy development for smart maintenance is proposed, including six steps: benchmarking, setting clear goals, setting strategic priority, planning key activities, elevating implementation and follow-up.

Practical implications

The proposed process provides industry practitioners with a step-by-step guide for the development of a clear smart maintenance strategy, based on the current state of their maintenance organization. This creates employee engagement and is a new way of developing maintenance strategies.

Originality/value

Maintenance strategies are traditionally regarded as a selection of corrective/reactive and preventive maintenance actions using a top-down approach. By contrast, the proposed process is starting from the current state of the maintenance organization and allows a mixture of top-down and bottom-up approaches, supporting organizational development. This is a rare perspective of maintenance strategies and will make maintenance organizations ready for the demands of digitalized manufacturing.
Data-based decision-making in maintenance service delivery: the D3M framework
Authors: Sala Roberto , Bertoni Marco , Pirola Fabiana , Pezzotta Giuditta
Published: May 2021

Purpose

This paper aims to present a dual-perspective framework for maintenance service delivery that should be used by manufacturing companies to structure and manage their maintenance service delivery process, using aggregated historical and real-time data to improve operational decision-making. The framework, built for continuous improvement, allows the exploitation of maintenance data to improve the knowledge of service processes and machines.

Design/methodology/approach

The Dual-perspective, data-based decision-making process for maintenance delivery (D3M) framework development and test followed a qualitative approach based on literature reviews and semi-structured interviews. The pool of companies interviewed was expanded from the development to the test stage to increase its applicability and present additional perspectives.

Findings

The interviews confirmed that manufacturing companies are interested in exploiting the data generated in the use phase to improve operational decision-making in maintenance service delivery. Feedback to improve the framework methods and tools was collected, as well as suggestions for the introduction of new ones according to the companies' necessities.

Originality/value

The paper presents a novel framework addressing the data-based decision-making process for maintenance service delivery. The D3M framework can be used by manufacturing companies to structure their maintenance service delivery process and improve their knowledge of machines and service processes.
Low‐quality carbon and lack of nutrients result in a stronger fungal than bacterial home‐field advantage during the decomposition of leaf litter
Authors: Benito‐Carnero Garazi , Gartzia‐Bengoetxea Nahia , Arias‐González Ander , Rousk Johannes
Published: May 2021

Decomposition of litter is a key biochemical process that regulates the rate and magnitude of CO2 fluxes from biosphere to atmosphere and determines soil nutrient availability. Although several studies have shown that plant litter decomposition accelerated in their native compared to a foreign environment, that is, a home‐field advantage (HFA) for litter degradation, to date HFA has only been considered in terms of respiration or litter mass loss.

The competitive success of the decomposer micro‐organism will be determined by its ability to transform used OM into population growth. Therefore, we hypothesized that HFA for microbial growth would be more pronounced than that for decomposition. We also expected that HFA effect for decomposition and microbial growth would increase with lower quality litter, which the fungal role in litter decomposition would be more dominant than that of bacteria, and that HFA effects would strengthen with more pronounced differences between ‘home’ and ‘away’ environments.

We designed a 2‐month microcosm reciprocal transplant experiment with litter from two sites with contrasting climates (Atlantic and Sub‐Mediterranean climates) and including three tree species (Quercus robur, Pinus sylvestris and Fagus sylvatica).

We found a stronger HFA for microbial growth than for decomposition, that the nutrient content and C‐quality of litter influenced the microbial HFA and that interactions between bacterial and fungal communities during litter decomposition modulated the HFA for litter degradation.

Low litter nutrient content, strong nutrient limitations and low C‐qualities all favoured fungal over bacterial decomposers, and our results suggest a dominant functional role of the fungal community and gave rise to HFA effect for fungal growth but that this translated to only marginal implications for overall decomposition of litter.

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