bluuebunny/crossref_metadata_2025 huggingface dataset:
Producing multi-coloured bunches through beam-induced ionization injection in plasma wakefield accelerator
Authors: Vafaei-Najafabadi N. , Amorim L. D. , Adli E. , An W. , Clarke C. I. , Clayton C. E. , Corde S. , Gessner S. , Green S. Z. , Hogan M. J. , Joshi C. , Kononenko O. , Lindstrøm C. A. , Litos M. , Lu W. , Marsh K. A. , Mori W. B. , San Miguel Claveria P. , O'Shea B. , Raj G. , Storey D. , White G. , Xu Xinlu , Yakimenko V.
Published: June 2019

This paper discusses the properties of electron beams formed in plasma wakefield accelerators through ionization injection. In particular, the potential for generating a beam composed of co-located multi-colour beamlets is demonstrated in the case where the ionization is initiated by the evolving charge field of the drive beam itself. The physics of the processes of ionization and injection are explored through OSIRIS simulations. Experimental evidence showing similar features are presented from the data obtained in the E217 experiment at the FACET facility of the SLAC National Laboratory.

This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration’.
FLASHForward: plasma wakefield accelerator science for high-average-power applications
Authors: D'Arcy R. , Aschikhin A. , Bohlen S. , Boyle G. , Brümmer T. , Chappell J. , Diederichs S. , Foster B. , Garland M. J. , Goldberg L. , Gonzalez P. , Karstensen S. , Knetsch A. , Kuang P. , Libov V. , Ludwig K. , Martinez de la Ossa A. , Marutzky F. , Meisel M. , Mehrling T. J. , Niknejadi P. , Põder K. , Pourmoussavi P. , Quast M. , Röckemann J. -H. , Schaper L. , Schmidt B. , Schröder S. , Schwinkendorf J. -P. , Sheeran B. , Tauscher G. , Wesch S. , Wing M. , Winkler P. , Zeng M. , Osterhoff J.
Published: June 2019

The FLASHForward experimental facility is a high-performance test-bed for precision plasma wakefield research, aiming to accelerate high-quality electron beams to GeV-levels in a few centimetres of ionized gas. The plasma is created by ionizing gas in a gas cell either by a high-voltage discharge or a high-intensity laser pulse. The electrons to be accelerated will either be injected internally from the plasma background or externally from the FLASH superconducting RF front end. In both cases, the wakefield will be driven by electron beams provided by the FLASH gun and linac modules operating with a 10 Hz macro-pulse structure, generating 1.25 GeV, 1 nC electron bunches at up to 3 MHz micro-pulse repetition rates. At full capacity, this FLASH bunch-train structure corresponds to 30 kW of average power, orders of magnitude higher than drivers available to other state-of-the-art LWFA and PWFA experiments. This high-power functionality means FLASHForward is the only plasma wakefield facility in the world with the immediate capability to develop, explore and benchmark high-average-power plasma wakefield research essential for next-generation facilities. The operational parameters and technical highlights of the experiment are discussed, as well as the scientific goals and high-average-power outlook.

This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration’.
Directions in plasma wakefield acceleration
Authors: Hidding B. , Foster B. , Hogan M. J. , Muggli P. , Rosenzweig J. B.
Published: June 2019

This introductory article is a synopsis of the status and prospects of particle-beam-driven plasma wakefield acceleration (PWFA). Conceptual and experimental breakthroughs obtained over the last years have initiated a rapid growth of the research field, and increased maturity of underlying technology allows an increasing number of research groups to engage in experimental R&D. We briefly describe the fundamental mechanisms of PWFA, from which its chief attractions arise. Most importantly, this is the capability of extremely rapid acceleration of electrons and positrons at gradients many orders of magnitude larger than in conventional accelerators. This allows the size of accelerator units to be shrunk from the kilometre to metre scale, and possibly the quality of accelerated electron beam output to be improved by orders of magnitude. In turn, such compact and high-quality accelerators are potentially transformative for applications across natural, material and life sciences.

This overview provides contextual background for the manuscripts of this issue, resulting from a Theo Murphy meeting held in the summer of 2018.

This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration’.
Spatiotemporal trends in polychlorinated biphenyl concentrations in seafood based on long-term monitoring and remediation in New Bedford Harbor, Massachusetts
Authors: Crawford Kathryn A. , Schlezinger Jennifer J. , Craffey Paul , Heiger-Bernays Wendy
Published: June 2019

Electrical manufacturing near New Bedford Harbor (NBH), MA in the mid-1900s led to severe polychlorinated biphenyl (PCB) contamination, which resulted in the harbor’s designation as a Superfund Site. Restrictions on the harvest of seafood from NBH have been in effect since 1979. Efforts to reduce the overall mass of PCBs in NBH by dredging PCB-contaminated sediments have been ongoing since the late 1980s. One goal of dredging is to reduce PCB concentrations in NBH seafood, monitored annually by Massachusetts Department of Environmental Protection (DEP) and Massachusetts Division of Marine Fisheries (MDMF). We used PCB concentrations in quahogs (2003-2016) and scup (2003-2014) to evaluate PCB distribution across seafood management areas and over time. Seafood PCB concentrations were used to evaluate improvements in environmental quality by examining total PCBs and patterns of PCB congeners within homolog groups, and by assessing human cancer risk from seafood consumption in the past (1980) and present (2012-2016). PCB concentrations in quahogs generally declined with increased time and distance from the PCB source, as does the cancer risk associated with their consumption. PCB concentrations in scup follow similar spatial patterns but show high annual variability. We conclude that quahogs are a reliable proxy for in-situ conditions, environmental quality, and human health risk.
Acoustic Measures of Prosody in Right-Hemisphere Damage: A Systematic Review and Meta-Analysis
Authors: Weed Ethan , Fusaroli Riccardo
Published: June 2019

The right hemisphere has often been claimed to be a locus for affective prosody, and people with right-hemisphere damage (RHD) have often been reported to show impairments in this domain. This phenomenon has been primarily investigated in terms of perception, more rarely in terms of production, and more rarely still using acoustic analysis. Our goal was to systematically review the papers reporting acoustic features of prosodic production in RHD, to identify strengths and weaknesses in this field, suggest guidelines for future research, and to support cumulative research by estimating the meta-analytic effect size of those features. We queried PubMed, PsychINFO, Web of Science, and Google Scholar, using the following combination of search terms: (prosody OR intonation OR inflection OR intensity OR pitch OR fundamental frequency OR speech rate OR voice quality) AND (RHD OR right hemisphere) AND (stroke) AND (acoustic). Standardized mean differences were extracted from all papers meeting inclusion criteria, and aggregated effect sizes were estimated using hierarchical Bayesian regression models. Sixteen papers met our inclusion criteria. We did not find strong evidence in the literature to indicate that the prosodic productions of people with RHD is substantially different from that of NBD controls, when measured in terms of acoustic features. However, the acoustic features of productions by people with RHD did differ from those of participants with NBD and LHD in some ways, notably in F0 variation and pause duration. Prosody type (emotional vs. linguistic) had very little effect. Taken together, currently available data show only a weak effect of RHD on prosody production. However, more accurate analyses are hindered by small sample sizes, lack of detail on lesion location, and divergent measuring techniques. Cumulative open science practices are recommended to overcome these issues.
Assembly of a persistent apical actin network by the formin Frl/Fmnl tunes epithelial cell deformability
Authors: Dehapiot Benoit , Clément Raphaël , Gazsó-Gerhát Gabriella , Philippe Jean-Marc , Lecuit Thomas
Published: June 2019

Tissue remodeling during embryogenesis is driven by the apical contractility of the epithelial cell cortex. This behavior arises notably from Rho1/Rok induced transient accumulation of non-muscle myosin II (MyoII pulses) pulling on actin filaments (F-Actin) of the medio-apical cortex. While recent studies begin to highlight the mechanisms governing the emergence of Rho1/Rok/MyoII pulsatility in different organisms, little is known about how the F-Actin organization influences this process. Focusing onDrosophilaectodermal cells during germband extension and amnioserosa cells during dorsal closure, we show that the medio-apical actomyosin cortex consists of two entangled F-Actin subpopulations. One exhibits pulsatile dynamics of actin polymerization in a Rho1 dependent manner. The other forms a persistent and homogeneous network independent of Rho1. We identify the Frl/Fmnl formin as a critical nucleator of the persistent network since modulating its level, in mutants or by overexpression, decreases or increases the network density. Absence of this network yields sparse connectivity affecting the homogeneous force transmission to the cell boundaries. This reduces the propagation range of contractile forces and results in tissue scale morphogenetic defects. Our work sheds new lights on how the F-Actin cortex offers multiple levels of regulation to affect epithelial cells dynamics.
The 14q32.31DLK1-DIO3 MIR300 tumor suppressorpromotes leukemogenesis by inducing cancer stem cell quiescence and inhibiting NK cell anti-cancer immunity
Authors: Silvestri Giovannino , Trotta Rossana , Stramucci Lorenzo , Ellis Justin J. , Harb Jason G. , Neviani Paolo , Wang Shuzhen , Eisfeld Ann-Kathrin , Walker Christopher , Zhang Bin , Srutova Klara , Gambacorti-Passerini Carlo , Pineda Gabriel , Jamieson Catriona H. M. , Stagno Fabio , Vigneri Paolo , Nteliopoulos Georgios , May Philippa , Reid Alistair , Garzon Ramiro , Roy Denis C. , Moutuou Moutua-Mohamed , Guimond Martin , Hokland Peter , Deininger Michael , Fitzgerald Garrett , Harman Christopher , Dazzi Francesco , Milojkovic Dragana , Apperley Jane F. , Marcucci Guido , Qi Janfei , Machova-Polakova Katerina , Zou Ying , Fan Xiaoxuan , Baer Maria R. , Calabretta Bruno , Perrotti Danilo
Published: June 2019

Drug-resistance of tumor-initiating cells, impaired NK cell immune-response, PP2A loss-of-function and aberrant miRNA expression are cancer features resulting from microenvironmental- and tumor-specific signals. Here we report that genomic-imprintedMIR300is a cell context-independent dual function tumor suppressor which is upregulated in quiescent leukemic stem (LSC) and NK cells by microenvironmental signals to induce quiescence and impair immune-response, respectively, but inhibited in CML and AML proliferating blasts to prevent PP2A-induced apoptosis.MIR300anti-proliferative and PP2A-activating functions are differentially activated through dose-dependent CCND2/CDK6 and SET inhibition, respectively. LSCs escape PP2A-mediated apoptosis through TUG1 lncRNA that uncouples and limitsMIR300functions to cytostasis by regulating unbound-MIR300levels. HaltingMIR300homeostasis restores NK cell activity and suppresses leukemic but not normal hematopoiesis by eradicating nearly all LSCs. Thus,MIR300tumor suppressor activity is essential and therapeutically important for LSC-driven leukemias.
Screening of clustered regulatory elements reveals functional cooperating dependencies in Leukemia
Authors: Benbarche Salima , Lopez Cécile K , Salataj Eralda , Thirant Cécile , Laiguillon Marie-Charlotte , Aid Zakia , Lecourt Séverine , Antonini Marion , Pardieu Bryan , Petit Arnaud , Puissant Alexandre , Chaumeil Julie , Mercher Thomas , Lobry Camille
Published: June 2019

In the recent years, massively parallel sequencing approaches identified hundreds of mutated genes in cancer(1) providing an unprecedented amount of information about mechanisms of cancer cell maintenance and progression. However, while (it is widely accepted that) transformation processes result from oncogenic cooperation between deregulated genes and pathways, the functional characterization of candidate key players is mostly performed at the single gene level which is generally inadequate to identify these oncogene circuitries. In addition, studies aimed at depicting oncogenic cooperation involve the generation of challenging mouse models or the deployment of tedious screening pipelines. Genome wide mapping of epigenomic modifications on histone tails or binding of factors such as MED1 and BRD4 allowed identification of clusters of regulatory elements, also termed Super-Enhancers (SE)(2). Functional annotation of these regions revealed their high relevance during normal tissue development and cancer ontogeny(3). An interesting paradigm of the tumorigenic function of these SE regions comes fromETO2-GLIS2-driven acute megakaryoblastic leukemia (AMKL) in which the fusion protein ETO2-GLIS2 is sufficient to promote an aberrant transcriptional network by the rewiring of SE regions(4). We thus hypothesized that important regulatory regions could control simultaneously expression of genes cooperating in functional modules to promote cancer development. In an effort to identify such modules, we deployed a genome-wide CRISPRi-based screening approach and nominated SE regions that are functionally linked to leukemia maintenance. In particular, we pinpointed a novel SE region regulating the expression of both tyrosine kinases KIT and PDGFRA. Whereas the inhibition of each kinase alone affected modestly cancer cell growth, combined inhibition of both receptors synergizes to impair leukemia cell growth and survival. Our results demonstrate that genome-wide screening of regulatory DNA elements can identify co-regulated genes collaborating to promote cancer and could open new avenues to the concept of combined gene inhibition upon single hit targeting.
Genomics of Egyptian Healthy Volunteers: The EHVol Study
Authors: Aguib Yasmine , Allouba Mona , Afify Alaa , Halawa Sarah , ElKhateb Mohamed , Sous Marina , Galal Aya , Abdelrahman Eslam , Shehata Nairouz , Sawy Amr El , Maghawry Mohamed , Anwer Shehab , Kamel Omnia , El-Mozy Wessam , Khedr Hadir , Essam Ahmed , Thabet Nagwa , Theotokis Pantazis , Buchan Rachel , Govind Risha , Whiffin Nicola , Walsh Roddy , Aguib Heba , Elguindy Ahmed , Cook Stuart A , Barton Paul J , Ware James , Yacoub Magdi
Published: June 2019

Comprehensive genomic databases offer unprecedented opportunities towards effective tailored strategies for the prevention and treatment of disease. The integration of genomic and phenotypic data from diverse ethnic populations is also key to advancements in precision medicine and novel diagnostic technologies. Current reference genomic databases, however, are not representative of the global human population, making variant interpretation challenging and uncertain, especially in underrepresented populations such as the North African population. To address this, a study of 391 Egyptian healthy volunteers (EHVols) was initiated as a milestone towards establishing the 1000 Egyptian Genomes project.
RNA polymerase active centre compensates for the absence of transcription proofreading factors in Cyanobacteria
Authors: Riaz-Bradley Amber , James Katherine , Yuzenkova Yulia
Published: June 2019

The vast majority of organisms possess transcription elongation factors, the functionally similar bacterial Gre and eukaryotic TFIIS/TFS. Their main cellular functions are to proofread errors of transcription and to restart elongation via stimulation of RNA hydrolysis by the active centre of RNA polymerase (RNAP). Very few taxons lack these factors, including the large evolutionarily ancient group of cyanobacteria and their descendants, the chloroplasts. How do they cope? What compensatory mechanisms they possess?

We found that cyanobacterial RNAP functionally substitutes for Gre/TFIIS - it does not stall on DNA, it efficiently catalyses the proofreading reaction of RNA hydrolysis, and the drop in transcription fidelity is only fractional, as confirmed by NGS. This alternative, presumably primordial, route to fidelity and processivity in the absence of Gre/TFIIS factors is based on the active site of RNAP stabilisation in a closed conformation. However, here lies a trade off - a severely reduced ability of this active site to recognise regulatory pausing signals. We suggest that perhaps the main advantage of Gre/TFIIS acquisition was to allow transcription regulation via pausing; with increase in fidelity as a bonus side effect.
Pulmonary natural killer cells control neutrophil intravascular motility and response to acute inflammation
Authors: Secklehner J. , De Filippo K. , Mackey J. B. G. , Vuononvirta J. , Raffo Iraolagoitia X. L. , McFarlane A. J. , Neilson M. , Headley M. B. , Krummel M. F. , Guerra N. , Carlin L. M.
Published: June 2019

The pulmonary immune system defends a huge surface area directly in contact with the contents of the air we breathe. Neutrophils, the most abundant immune cell in the pulmonary vasculature, are critical to immunity but they are also capable of generating life-threatening pathology. Natural Killer cells are the most highly represented lymphocyte subset in the lung, but relatively little is known about their localization, motility or the specific mechanisms by which they contribute to local homeostasis. Here, we used lung-intravital microscopy to directly visualise and quantify neutrophil and natural killer cell dynamics in the pulmonary vasculature of live mice. This approach revealed unexpected sessile behaviour by intravascular natural killer cells. Interactions with natural killer cells made neutrophils scan the endothelium more slowly over larger distances and reduced the number of neutrophils that accumulated in an LPS-triggered inflammatory challenge. This represents a new paradigm by which natural killer cells contribute to lung physiology by diminishing potentially pathogenic neutrophil accumulation.
Machine Learning based histology phenotyping to investigate epidemiologic and genetic basis of adipocyte morphology and cardiometabolic traits
Authors: Glastonbury C. A , Pulit S. L , Honecker J. , Censin J. C , Laber S. , Yaghootkar H. , Rahmioglu N. , Pastel E. , Kos K. , Pitt A. , Hudson M. , Nellåker C. , Beer N. L , Hauner H. , Becker C. M , Zondervan K. T , Frayling T. M , Claussnitzer M. , Lindgren C. M
Published: June 2019

Genetic studies have recently highlighted the importance of fat distribution, as well as overall adiposity, in the pathogenesis of obesity-associated diseases. Using a large study (n = 1,288) from 4 independent cohorts, we aimed to investigate the relationship between adipocyte area and obesity-related traits, and identify genetic factors associated with adipocyte cell size. To perform the first large-scale study of automatic adipocyte phenotyping using both histological and genetic data, we developed a deep learning-based method, the Adipocyte U-Net, to rapidly derive area estimates from histology images. We validate our method using three state-of-the-art approaches; CellProfiler, Adiposoft and floating adipocytes fractions, all run blindly on two external cohorts. We observe high concordance between our method and the state-of-the-art approaches (Adipocyte U-net vs. CellProfiler: R2visceral= 0.94, P < 2.2 × 10−16, R2subcutaneous= 0.91, P < 2.2 × 10−16), and faster run times (10,000 images: 6mins vs 3.5hrs). We applied the Adipocyte U-Net to 4 cohorts with histology, genetic, and phenotypic data (total N = 820). After meta-analysis, we found that adipocyte area positively correlated with body mass index (BMI) (Psubq = 8.13 × 10−69, βsubq = 0.45; Pvisc= 2.5 × 10−55, βvisc= 0.49; average R2 across cohorts = 0.49) and that adipocytes in subcutaneous depots are larger than their visceral counterparts (Pmeta= 9.8 × 10−7). Lastly, we performed the largest GWAS and subsequent meta-analysis of adipocyte area and intra-individual adipocyte variation (N = 820). Despite having twice the number of samples than any similar study, we found no genome-wide significant associations, suggesting that larger sample sizes and a homogenous collection of adipose tissue are likely needed to identify robust genetic associations.
PICKER-HG: a web server using random forests for classifying human genes into categories
Authors: Fabris Fabio , Palmer Daniel , Farooq Zoya , de Magalhães João Pedro , Freitas Alex A
Published: June 2019

Motivation

One of the main challenges faced by biologists is how to extract valuable knowledge from the data produced by high-throughput genomic experiments. Although machine learning can be used for this, in general, machine learning tools on the web were not designed for biologist users. They require users to create suitable biological datasets and often produce results that are hard to interpret.

Objective

Our aim is to develop a freely available web server, named PerformIng Classification and Knowledge Extraction via Rules using random forests on Human Genes (PICKER-HG), aimed at biologists looking for a straightforward application of a powerful machine learning technique (random forests) to their data.

Results

We have developed the first web server that, as far as we know, dynamically constructs a classification dataset, given a list of human genes with annotations entered by the user, and outputs classification rules extracted of a Random Forest model. The web server can also classify a list of genes whose class labels are unknown, potentially assisting biologists investigating the association between class labels of interest and human genes.

Availability

http://machine-learning-genomics.com/
Capture of a functionally active methyl-CpG binding domain by an arthropod retrotransposon family
Authors: de Mendoza Alex , Pflueger Jahnvi , Lister Ryan
Published: June 2019

The repressive capacity of cytosine DNA methylation is mediated by recruitment of silencing complexes by methyl-CpG binding domain (MBD) proteins. Despite MBD proteins being associated with silencing, we discovered that a family of arthropod Copia retrotransposons have incorporated a host-derived MBD. We functionally show how retrotransposon-encoded MBDs preferentially bind to CpG-dense methylated regions, which correspond to transposable element regions of the host genome, in the myriapod Strigamia maritima. Consistently, young MBD-encoding Copia retrotransposons (CopiaMBD) accumulate in regions with higher CpG densities than other LTR-retrotransposons also present in the genome. This would suggest that retrotransposons use MBDs to integrate into heterochromatic regions in Strigamia, avoiding potentially harmful insertions into host genes. In contrast, CopiaMBD insertions in the spider Stegodyphus dumicola genome disproportionately accumulate in methylated gene bodies compared with other spider LTR-retrotransposons. Given that transposons are not actively targeted by DNA methylation in the spider genome, this distribution bias would also support a role for MBDs in the integration process. Together, these data show that retrotransposons can co-opt host-derived epigenome readers, potentially harnessing the host epigenome landscape to advantageously tune the retrotransposition process.
A hybrid conceptual model for BIM in FM
Authors: Hilal Mustafa , Maqsood Tayyab , Abdekhodaee Amir
Published: June 2019

Purpose

The purpose of this paper is to develop a hybrid conceptual model for building information modelling (BIM) adoption in facilities management (FM) through the integration of the technology task fit (TTF) and the unified theory of acceptance and use of technology (UTAUT) theories. The study also aims to identify the influence factors of BIM adoption and usage in FM and identify gaps in the existing literature and to provide a holistic picture of recent research in technology acceptance and adoption in the construction industry and FM sector.

Design/methodology/approach

The research methodology was to first review the literature to determine how users come to accept new technologies and what leads to adoption of BIM in the construction industry and in FM and to identify gaps as the starting point for developing a conceptual framework for greater adoption of BIM in FM. Using the results from the literature review, the conceptual framework for BIM adoption in FM has been formulated.

Findings

The resulting model of the current research is expected to improve our understanding of the acceptance and adoption of BIM by FM.

Research limitations/implications

The research hypotheses need to be tested for validation. Future works includes survey and experts’ interviews for model validation.

Originality/value

This paper fulfils an identified need to study how FM come to accept and adopt BIM through the integration of TTF and UTAUT.
Continuous local material model for the mechanical stress-dependency of magnetic properties in non-oriented electrical steel
Authors: Karthaus Jan , Elfgen Silas , Hameyer Kay
Published: June 2019

Purpose

Magnetic properties of electrical steel are affected by mechanical stress. In electrical machines, influences because of manufacturing and assembling and because of operation cause a mechanical stress distribution inside the steel lamination. The purpose of this study is to analyse the local mechanical stress distribution and its consequences for the magnetic properties which must be considered when designing electrical machines.

Design/methodology/approach

In this paper, an approach for modelling stress-dependent magnetic material properties such as magnetic flux density using a continuous local material model is presented.

Findings

The presented model shows a good approximation to measurement results for mechanical tensile stress up to 100 MPa for the studied material.

Originality/value

The presented model allows a simple determination of model parameters by using stress-dependent magnetic material measurements. The model can also be used to determine a scalar mechanical stress distribution by using a known magnetic flux density distribution.
LSTM multichannel neural networks in mental task classification
Authors: Opałka Sławomir , Szajerman Dominik , Wojciechowski Adam
Published: June 2019

Purpose

The purpose of this paper is to apply recurrent neural networks (RNNs) and more specifically long-short term memory (LSTM)-based ones for mental task classification in terms of BCI systems. The authors have introduced novel LSTM-based multichannel architecture model which proved to be highly promising in other fields, yet was not used for mental tasks classification.

Design/methodology/approach

Validity of the multichannel LSTM-based solution was confronted with the results achieved by a non-multichannel state-of-the-art solutions on a well-recognized data set.

Findings

The results demonstrated evident advantage of the introduced method. The best of the provided variants outperformed most of the RNNs approaches and was comparable with the best state-of-the-art methods.

Practical implications

The approach presented in the manuscript enables more detailed investigation of the electroencephalography analysis methods, invaluable for BCI mental tasks classification.

Originality/value

The new approach to mental task classification, exploiting LSTM-based RNNs with multichannel architecture, operating on spatial features retrieving filters, has been adapted to mental tasks with noticeable results. To the best of the authors’ knowledge, such an approach was not present in the literature before.
Influence of shape and material of rotor bars on performance characteristics of single-phase self-excited induction generators
Authors: Leicht Aleksander , Makowski Krzysztof
Published: June 2019

Purpose

The purpose of the paper is to present an analysis of an influence of shape and material of rotor bars on the process of self-excitation and performance characteristics of single-phase, self-excited induction generator (SP-SEIG).

Design/methodology/approach

The presented analysis is based on the results of transient simulations of SP-SEIG performed with the use of field-circuit model of the machine. Four various shapes of the rotor bars and two different conductor materials were investigated. The results for the base model with rounded trapezoidal rotor slots were validated by measurements.

Findings

An improvement of the performance characteristics – the extension of the stable operating range of the generator – was obtained for rectangular copper rotor bars. The improvement is the result of strong skin effect in the squirrel rotor cage. Application of round rotor slots results in shorter time of voltage build-up during the self-excitation of the generator caused by less apparent deep bar effect in round bars.

Originality/value

The originality of the paper is the application of the copper rotor cage in the single-phase, self-excited induction generator. Its use is beneficial, as it allows for extension of the range of stable operating range. The results may be used for designing new constructions of the single-phase, self-excited induction generators, as well as the constructions based on general purpose single-phase induction motors.
Market-oriented interest rate, deposit insurance system and bank runs
Authors: Tian Guoqiang , Zhao Yupu , Gong Rukai
Published: June 2019

Purpose

In the transitional process of promoting market-oriented interest rate, China is confronted with an important theoretical and practical issue: how to avoid bank runs and realize the smooth operation of the financial system. The purpose of this paper is to construct a bank-run dynamic model by taking into account a market environment with the transmission of multiple rounds of noise information, a comprehensive consideration of depositors’ expectation of return on assets (or earning rate/yields of assets), the efficiency of information processing and dissemination, and the different motives for premature withdrawal.

Design/methodology/approach

The authors discussed the dynamic process of bank runs, furnished the ratio and number of each round of bank run, and characterized the corresponding dynamic equilibrium as well. Furthermore, the authors expanded the benchmark model by incorporating the deposit insurance system (DIS) to discuss the action mechanism of DIS overruns.

Findings

The results show that DIS implementation has two opposite effects: stabilized expectation and moral hazard, by virtue of its influence over the two types of premature withdrawal motives of depositors; the implementation effect of DIS rests with the dual-effect comparison, which is endogenous to the institutional environment.

Originality/value

The policy implications are as follows: while implementing DIS, it is necessary to establish and improve the corresponding institutional construction and supporting measures, to consolidate market discipline and improve the supervisory role of the bank’s internal governance mechanism, so as to reduce the potential moral hazards. The financial system reform shall be furthered and the processing and dissemination efficiency of information be elevated to prompt depositors to form stable withdrawal expectations, thereby enhancing the stabilizing effect of DIS.
Research note: customer experience management in cruise pre-consumption
Authors: Sharples Liz
Published: June 2019

Purpose

This study aims to apply the relatively new concept of customer experience management (CXM) to the pre-consumptive stage within a cruise tourist’s journey.

Design/methodology/approach

The work will apply CXM to the tourism sector and, in particular to the cruise market. Academics have noted how CXM needs to takes a holistic integrated approach and focus on the complete customer experience. The cruise sector has been selected for this research because, it is the fastest growing tourism sector globally and the pre-consumption stage for cruise passengers is longer than for other vacation types.

Findings

This study has shown how CXM has emerged from the more traditional marketing concept of relationship marketing and has highlighted its relevance within the tourism industry, in particular, the cruise sector. In addition, the work has shown how adapting CXM to the pre-consumptive phase more fully will enhance consumer relationships and improve business performance.

Research limitations/implications

This work is conceptual. It is proposed that the research propositions should be verified within the pre-consumptive stage of cruise passenger journeys. Another limitation is that the focus has been solely on the cruise sector and future research could be extended to other tourism service industries.

Practical implications

This work will provide tourism and other service industry managers with a new strategy to enhance consumer experience and improve business performance in the pre-consumptive stage and extend academic understanding within this stage of a cruise tourist’s vacation.

Originality/value

This research is significant because CXM is a model, which has been used within service businesses, but had a limited application to the cruise sector and to the pre-consumption timeframe. It is important to understand cruise passengers in this time-frame to encourage positive relationships, to potentially increase revenue opportunities and provide an overall improved consumer experience.
Motives for writing online reviews in post-vacation phase
Authors: Mladenovic Dusan , Krajina Anida , Milojevic Ivana
Published: June 2019

Purpose

This quantitative study aims to examine background motives that navigate individuals to share their opinions, in the context of an individual’s post-vacation phase and its relation to the destination of Serbia, from the standpoint of age, gender and nationality.

Design/methodology/approach

The data were collected throughout six weeks via a self-administered Web survey. The survey was adopted and based on the scale developed by Bronner and de Hoog (2011).

Findings

Results indicate that the dominant driver to submit an online review after a trip is to help vacationers (altruism) and that men and women display differences in this, but not in other motives. Both age and nationality do not influence the particular motive to leave an online review.

Research limitations/implications

The main limitation of this study is the total number of answers. However, sampling was rather purposive, which gives us a good indicator of the population behavior.

Practical implications

Understanding these drivers is essential in formulating strategies for managing the interaction with opinion leaders. On a larger scale, the results can contribute the market segmentation and customer communication approaches in Serbian tourism marketing.

Originality/value

Motives that trigger individuals to compose an online review have not been investigated and thematic studies are still missing, in the case of Serbia in particular.
A factual and perceptional framework for assessing diversity effects of online recommender systems
Authors: Matt Christian , Hess Thomas , Weiß Christian
Published: June 2019

Purpose

The purpose of this paper is to explore the effects of online recommender systems (RS) on three types of diversity: algorithmic recommendation diversity, perceived recommendation diversity and sales diversity. The analysis distinguishes different recommendation algorithms and shows whether user perceptions match the actual effects of RS on sales.

Design/methodology/approach

An online experiment was conducted using a realistic shop design, various recommendation algorithms and a representative consumer sample to ensure the generalizability of the findings.

Findings

Recommendation algorithms show a differential impact on sales diversity, but only collaborative filtering can lead to higher sales diversity. However, some of these effects are subject to how much information firms have about users’ preferences. The level of recommendation diversity perceived by users does not always reflect the factual diversity effects.

Research limitations/implications

Recommendation and consumption patterns might differ for other types of products; future studies should replicate the study with search or credence goods. The authors also recommend that future research should move from taking a unidimensional measure for the assessment of diversity and employ multidimensional measures instead.

Practical implications

Online shops need to conduct a more comprehensive assessment of their RS’ effect on diversity, taking into account not only the effects on their sales distribution, but also on users’ perceptions and faith in the recommendation algorithm.

Originality/value

This study offers a framework for assessing different forms of diversity in online RS. It employs various recommendation algorithms and compares their impact using not just one but three different types of diversity measures. This helps explaining some of the contradictious findings from the previous literature.
The impact of Sarbanes–Oxley and Dodd–Frank on executive compensation
Authors: Hughen Linda , Malik Mahfuja , Shim Eunsup Daniel
Published: June 2019

Purpose

The recent economic and political focus on rising income inequality and the extent of government intervention into pay policies has renewed the interest in executive compensation. The purpose of this paper is to examine the impact of changing regulatory landscapes on executive pay and its components.

Design/methodology/approach

This study examines a recent 23-year period divided into three distinct intervals separated by two major regulatory changes, the Sarbanes–Oxley Act (SOX) and the Dodd–Frank Act. Bonus, long-term and total compensation are separately modeled as a function of each regulatory change while controlling for firm size, performance and year. The model is estimated using panel data with firm fixed effects. An industry analysis is also conducted to examine sector variations.

Findings

Total compensation increased 29 percent following SOX and 21 percent following Dodd–Frank, above what can be explained by size, firm performance and time. Total compensation increased following both SOX and Dodd–Frank in all industries except for the financial services industry where total compensation was unchanged. Results are robust to using smaller windows around each regulation.

Research limitations/implications

This study does not seek to determine whether executive compensation is at an optimal level at any point in time. Instead, this study focuses only on the change in executive compensation after two specific regulations.

Originality/value

The debate over the extent to which the government should intervene with executive compensation has become a frequent part of political and non-political discourse. This paper provides evidence that over the long-term, regulation does not curtail executive compensation. An important exception is that total compensation was restrained for financial services firms following the Dodd–Frank Act.
Emotional and cognitive involvement of consumers with hotel brands on social networking sites
Authors: Su Na , Mariadoss Babu John , Reynolds Dennis
Published: June 2019

Purpose

Based on persuasion theories, the purpose of this paper is to examine relationships between four types of interactive consumer activities (viewing, liking, sharing and commenting) on hotel brand social networking sites (SNSs) and their cognitive and emotional responses to understand the psychological states underlying such actions and assess their influence on brand attitude and the brand–consumer relationship.

Design/methodology/approach

A survey was administrated using an online platform. Participants who had been following a hotel brand on any of its SNSs were screened to fill out the questionnaire. Eventually, 226 valid responses were collected and analyzed using structure equation modeling.

Findings

The findings suggest that although both emotional and cognitive involvement can enhance a consumer’s hotel brand attitude, cognitive involvement is associated with a slightly stronger effect in the context of SNSs. Three of the four interactive actions – viewing, liking and sharing – were found to be positively associated with emotional involvement, but only two actions – viewing and liking – were found to be positively related to cognitive involvement. No connection was identified for commenting.

Practical implications

The study suggests that practitioners should turn their attention to the emotional and cognitive responses their SNSs provoke in consumers, rather than simply on the number of likes, shares and comments they induce.

Originality/value

A recent research trend indicates widespread interest in the button functions offered by SNSs (such as “like,” “share” and “comment”) and many studies have tested means of stimulating such physical actions. This study is one of the few to explore the psychological states behind such actions and assess their influence on brand attitude and the self-brand connection.
The role of feedback in training psychiatrists
Authors: Rubí González Patricia S. , De la Barra Vivallos Luis , Schaefer Hardy , Vergara-Barra Pablo
Published: June 2019

Purpose

Feedback is a tool that informs students about their learning process and facilitates necessary changes. It looks for the students’ own perceptions of their performance and how to improve it, developing permanent learning skills vital for autonomous practice. It is useful for improving one’s performance, clinical skills, communication and treatment of patients. If carried out improperly, it causes a lack of motivation and a collapse in the teacher–student relationship. The purpose of this paper is to analyze the perceptions and experiences of the residents and graduates of the psychiatry specialty at the Universidad of Concepción with respect to the feedback received on their performance during their training.

Design/methodology/approach

The study was conducted using a qualitative approach of an exploratory, descriptive and interpretative nature that was also based on Grounded Theory. Ten in-depth voluntary interviews were conducted with residents-in-training and graduates from within the last two years of the Adult Psychiatry specialty at the Universidad of Concepción. Subsequently, the data were codified to create a theoretical model.

Findings

The interpersonal teacher–resident relationship, when based on collaboration and an openness to dialogue, is fundamental in producing effective feedback.

Research limitations/implications

The limitations of this study were based mainly on the qualitative methodology used, so it is not possible to generalize the results. Although the above limitation, this study seems to reaffirm the importance of feedback for residents in training, so it would be advisable to reproduce it in various training contexts and extend it to the perception of the teachers involved. On the other hand, to follow this research line, it is essential to create instruments that facilitate the use of quantitative research methodology, which allows the generalization and comparison of results in different areas.

Social implications

This research opens a first line of research regarding subjective experience when receiving feedback, which will allow the creation of instruments to objectify how it is being developed in different educational contexts and to propose strategies to standardize its realization.

Originality/value

There are no other studies of this type published. The originality of this research was that beyond the mention made about the known characteristics that a feedback must have to be effective, the participants gave special emphasis to the fact that it is a social relationship, which should be based on a horizontal interaction between two actors, in addition to promoting dialogue and mutual involvement in the task that brings them together. Thus it is an effective teaching strategy, fulfilling the objective of motivating the learning and autonomy of the resident.
“We’re not uber:” control, autonomy, and entrepreneurship in the gig economy
Authors: Ravenelle Alexandrea J.
Published: June 2019

Purpose

Unlike the effect of management styles on employee attitudes, little is known about the effect of managerial assumptions on workers within the gig economy. The purpose of this paper is to utilize McGregor’s Theory X and Theory Y as a framework to discuss two gig economy platforms and how their differing management assumptions affect worker perceptions of themselves as entrepreneurs.

Design/methodology/approach

The author utilized qualitative interviews and demographic surveys with 41 contract workers from TaskRabbit, a personal assistant platform, and Kitchensurfing, a “rent-a-chef” service, to examine the impact of differing management assumptions on independent contractor perceptions of themselves as entrepreneurs.

Findings

The Theory X management assumptions and correlated behaviors directly contradict the entrepreneurial ethos marketed by the platforms, resulting in a psychological contract violation for workers and negative responses to the platform. In comparison, Theory Y managerial assumptions and correlated behaviors can be utilized to encourage worker innovation, creativity and sense of self as an entrepreneur.

Practical implications

As the gig economy continues to grow, algorithms are likely to take on increased importance as a management tool. Although some have suggested that such algorithms may reduce the impact of a capricious manager, the fact remains that algorithms are created by management. If the gig economy intends to encourage entrepreneurship, additional attention must be paid to how differing management assumptions, and their resulting behaviors and algorithms, affect worker attitudes and experience.

Originality/value

This study represents one of the initial academic investigations into how the Theory X and Theory Y management assumptions and correlated perspectives may be applied to independent contractors within the gig economy. Additionally, this study is among the first to examine how gig worker attitudes toward platform firms, and views of themselves as entrepreneurs, are affected by algorithm-implemented management policies.