bluuebunny/crossref_metadata_2025 huggingface dataset:
Individuals with 22q11.2 deletion syndrome show intact prediction but reduced adaptation in responses to repeated sounds: evidence from Bayesian mapping
Authors: Larsen Kit Melissa , Mørup Morten , Birknow Michelle Rosgaard , Fischer Elvira , Olsen Line , Didriksen Michael , Christiaan Baaré William Frans , Werge Thomas Mears , Garrido Marta Isabel , Siebner Hartwig Roman
Published: October 2018

Background

One of the most common copy number variants, the 22q11.2 microdeletion, confers an increased risk for schizophrenia. Since schizophrenia has been associated with an aberrant neural response to repeated stimuli through both reduced adaptation and prediction, we here hypothesized that this may also be the case in nonpsychotic individuals with a 22q11.2 deletion.

Methods

We recorded high-density EEG from 19 individuals with 22q11.2 deletion syndrome (12-25 years), as well as 27 healthy volunteers with comparable age and sex distribution, while they listened to a sequence of sounds arranged in a roving oddball paradigm. Using posterior probability maps and dynamic causal modelling we tested three different models accounting for repetition dependent changes in cortical responses as well as in effective connectivity; namely an adaptation model, a prediction model, and a model including both adaptation and prediction.

Results

Repetition-dependent changes were parametrically modulated by a combination of adaptation and prediction and were apparent in both cortical responses and in the underlying effective connectivity. This effect was reduced in individuals with a 22q11.2 deletion and was negatively correlated with negative symptom severity. Follow-up analysis showed that the reduced effect of the combined adaptation and prediction model seen in individuals with 22q11.2 deletion was driven by reduced adaptation rather than prediction failure.

Conclusions

Our findings suggest that adaptation is reduced in individuals with a 22q11.2 deletion, which can be interpreted in light of the framework of predictive coding as a failure to suppress prediction errors.
Long-range phase synchronization of high-gamma activity in human cortex
Authors: Arnulfo G , Wang SH , Toselli B , Williams N , Hirvonen J , Fato MM , Nobili L , Cardinale F , Rubino A , Zhigalov A , Palva S , Palva JM
Published: October 2018

Inter-areal synchronization of neuronal oscillations below 100 Hz is ubiquitous in cortical circuitry and thought to regulate neuronal communication. In contrast, faster activities are generally considered to be exclusively local-circuit phenomena. We show with human intracerebral recordings that 100–300 Hz high-gamma activity (HGA) may be synchronized between widely distributed regions. HGA synchronization was not attributable to artefacts or to epileptic pathophysiology. Instead, HGA synchronization exhibited a reliable cortical connectivity and community structures, and a laminar profile opposite to that of lower frequencies. Importantly, HGA synchronization among functional brain systems during non-REM sleep was distinct from that in resting state. Moreover, HGA synchronization was transiently enhanced for correctly inhibited responses in a Go/NoGo task. These findings show that HGA synchronization constitutes a new, functionally significant form of neuronal spike-timing relationships in brain activity. We suggest that HGA synchronization reflects the temporal microstructure of spiking-based neuronal communication per se in cortical circuits.
Microridges are apical projections formed of branched F-actin networks that organize the glycan layer
Authors: Pinto Clyde Savio , Khandekar Ameya , Bhavna Rajasekaran , Kiesel Petra , Pigino Gaia , Sonawane Mahendra
Published: October 2018

Apical projections are integral functional units of epithelial cells. Microvilli and stereocilia are cylindrical apical projections that are formed of bundled actin. Microridges on the other hand, grow laterally long, forming labyrinthine patterns on surfaces of various kinds of squamous epithelial cells. So far, the structural organization and functions of microridges have remained elusive. We have analyzed microridges on zebrafish epidermal cells using confocal and electron microscopy methods including electron tomography, to show that a microridge is formed of a network of F-actin and requires the function of the Arp2/3 complex for its maintenance. During development, microridges begin as F-actin punctae showing signatures of branching and requiring an active Arp2/3 complex. Using inhibitors of actin polymerization and the Arp2/3 complex, we show that microridges organize the surface glycan layer. Our analyses have unraveled the F-actin organization supporting the most abundant and evolutionarily conserved apical projection, which functions in glycan organization.
Transitions in paternal dominance regulate offspring growth and metabolic transcription
Authors: Cauceglia Joseph W. , Nelson Adam C. , Rubinstein Nimrod D. , Kukreja Shweta , Sasso Lynsey N , Beaufort John A. , Rando Oliver J. , Potts Wayne K
Published: October 2018

Parental effects are an important source of adaptive traits. By contrast, parental effects failing to regulate offspring phenotype to fit current conditions could be deleterious. Although adaptive parental responses to single cues have been identified, we lack an understanding of the reversibility of parental effects across breeding cycles in a fluctuating environment. Social status of parents can occasionally fluctuate and, in turn, influence high-fitness pathways available to offspring. We show that social competition status results in robust parental effects on growth in mice. Dominant males produce faster growing offspring because of status related cues, not genetic associations. The timing, effect-size, and sex-specificity of this paternal effect are modulated by maternal experience. We experimentally demonstrate that status-ascending males produce heavier sons than before, and status-descending males produce lighter sons than before. Paternal status predicts genome-wide transcription in the liver, including transcriptional networks controlling xenobiotic and fatty acid metabolism, and oxidative phosphorylation. Our study demonstrates that paternal social status reversibly conditions offspring growth in naturalistic environments.
Non-functional and weak alleles of FRIGIDA and FLOWERING LOCUS C reduce lifetime water-use independent of leaf-level water-use-efficiency traits in Arabidopsis thaliana
Authors: Ferguson J.N. , Meyer R.C. , Edwards K.D. , Humphry M. , Brendel O. , Bechtold U.
Published: October 2018

Natural selection driven by water availability has resulted in considerable variation for traits associated with drought tolerance and leaf level water-use efficiency (WUE). In Arabidopsis, little is known about the variation of whole-plant water use (PWU) and whole-plant WUE (TE). To investigate the genetic basis of PWU, we developed a novel proxy trait by combining flowering time and rosette water use to estimate lifetime PWU. We validated its usefulness for large scale screening of mapping populations in a subset of ecotypes. This parameter subsequently facilitated the screening of water-use but also drought tolerance traits in a recombinant inbred line population derived from two Arabidopsis accessions with distinct water use strategies, namely C24 (low PWU) and Col-0 (high PWU). Subsequent quantitative trait loci (QTL) mapping and validation through near-isogenic lines identified two causal QTLs, which showed that a combination of weak and non-functional alleles of the FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) genes substantially reduced plant water-use without penalising reproductive performance. Drought tolerance traits, stomatal conductance, intrinsic water use efficiency (δ13C) and rosette water-use were independent of allelic variation at FRI and FLC, suggesting that flowering is critical in determining life-time plant water use, but not leaf-level traits.
The genetics of morphological and behavioural island traits in deer mice
Authors: Baier Felix , Hoekstra Hopi E.
Published: October 2018

Animals on islands often exhibit dramatic differences in morphology and behaviour compared to mainland individuals, a phenomenon known as the “island syndrome”. These differences are thought to be adaptations to island environments, but the extent to which they have a genetic basis or instead represent plastic responses to environmental extremes is often unknown. Here, we revisit a classic case of island syndrome in deer mice (Peromyscus maniculatus) from British Columbia. We first show that Saturna Island mice and those from neighbouring islands are ∼35% (∼5g) heavier than mainland mice and diverged approximately 10 thousand years ago. We then established laboratory colonies and find that Saturna Island mice are heavier both because they are longer and have disproportionately more lean mass. These trait differences are maintained in second-generation captive-born mice raised in a common environment. In addition, island-mainland hybrids reveal a maternal genetic effect on body weight. Using behavioural testing in the lab, we also find that wild-caught island mice are less aggressive than mainland mice; however, lab-raised mice born to these founders do not differ in aggression. Together, our results reveal that these mice respond differently to environmental conditions on islands – evolving both heritable changes in a morphological trait and also expressing a plastic phenotypic response in a behavioural trait.
Distinct functional roles for hopanoid composition in the chemical tolerance ofZymomonas mobilis
Authors: Brenac Léa , Baidoo Edward E.K. , Keasling Jay D. , Budin Itay
Published: October 2018

Hopanoids are abundant membrane lipids found in diverse bacterial lineages, but their physiological roles are not well understood. The ethanol fermenterZymomonas mobilisfeatures the highest measured concentration of hopanoids, leading to the hypothesis that these lipids can protect against bacterial solvent toxicity. However, the lack of genetic tools for manipulating hopanoid compositionin vivohas limited their further functional analysis. Because of polyploidy (> 50 genome copies per cell), we found that disruptions of essential hopanoid biosynthesis (hpn) genes inZ. mobilisact as genetic knockdowns, reliably modulating the abundance of different hopanoid species. Using a set ofhpntransposon mutants, we demonstrate that both reduced hopanoid content and modified hopanoid head group composition mediate growth and survival in ethanol. In contrast, the amount of hopanoids, but not their polar group composition, contributes to fitness at low pH. Spectroscopic analysis of model membranes showed that hopanoids protect against several ethanol-driven phase transitions in membrane structure, including lipid interdigitation and bilayer dissolution. We propose that hopanoids act through a combination of hydrophobic and inter-lipid hydrogen bonding interactions to stabilize bacterial membranes against solvent stress.

Graphical abstract
Dissection of protonation sites for antibacterial recognition and transport in QacA, a multi-drug efflux transporter
Authors: Majumder Puja , Khare Shashank , Athreya Arunabh , Hussain Nazia , Gulati Ashutosh , Penmatsa Aravind
Published: October 2018

QacA is a drug:H+ antiporter (DHA2) with 14 transmembrane helices, that renders antibacterial resistance to methicillin-resistant Staphylococcus aureus (MRSA) strains, with homologues in other pathogenic organisms. It is a highly promiscuous antiporter, capable of H+- driven efflux of a wide array of cationic antibacterial compounds and dyes. Our study, using a homology model of QacA, reveals a group of six protonatable residues in its vestibule. Systematic mutagenesis resulted in identification of D34 (TM1), and a cluster of acidic residues in TM13 including E407 and D411 and D323 in TM10, as being crucial for substrate recognition and transport of monovalent and divalent cationic antibacterial compounds. The transport and binding properties of QacA and its mutants were explored using whole cells, inside-out vesicles, substrate-induced H+ release and microscale thermophoresis. We identify two sites, D34 and D411 as vital players in substrate recognition while E407 facilitates substrate efflux as a protonation site. We also observe that E407 plays a moonlighting role as a substrate recognition site for dequalinium transport. These observations rationalize the promiscuity of QacA for diverse substrates. The study unravels the role of acidic residues in QacA with implications for substrate recognition, promiscuity and processive transport in multidrug efflux transporters, related to QacA.

Highlights

A homology model of QacA with 14 TM helices was used to test the importance of acidic residues within the vestibule.

Mono and Divalent cationic substrate recognition requires two sites D34 (TM1) and D411 (TM13).

E407 (TM13) is important for protonation driven efflux.

Substrate recognition of a divalent substrate, dequalinium occurs at E407 instead of D411 providing glimpses into the promiscuity of substrate recognition in QacA.
Adaptive disinhibitory gating by VIP interneurons permits associative learning
Authors: Krabbe Sabine , Paradiso Enrica , D’Aquin Simon , Bitterman Yael , Xu Chun , Yonehara Keisuke , Markovic Milica , Gründemann Jan , Ferraguti Francesco , Lüthi Andreas
Published: October 2018

Learning drives behavioral adaptations necessary for survival. While plasticity of excitatory projection neurons during associative learning is studied extensively, little is known about the contributions of local interneurons. Using fear conditioning as a model for associative learning, we find that behaviorally relevant, salient stimuli cause learning by tapping into a local microcircuit consisting of precisely connected subtypes of inhibitory interneurons. By employing calcium imaging and optogenetics, we demonstrate that vasoactive intestinal peptide (VIP)-expressing interneurons in the basolateral amygdala are activated by aversive events and provide an instructive disinhibitory signal for associative learning. Notably, VIP interneuron responses are plastic and shift from the instructive to the predictive cue upon memory formation. We describe a novel form of adaptive disinhibitory gating by VIP interneurons that allows to discriminate unexpected, important from irrelevant information, and might be a general dynamic circuit motif to trigger stimulus-specific learning, thereby ensuring appropriate behavioral adaptations to salient events.
Bud13 Promotes a Type I Interferon Response by Countering Intron Retention in Irf7
Authors: Frankiw Luke S. , Majumdar Devdoot , Burns Christian , Moradian Annie , Sweredoski Michael J. , Baltimore David
Published: October 2018

Intron retention (IR) has emerged as an important mechanism of gene expression control. Despite this, the factors that control IR events remain poorly understood. We observed consistent IR in one intron of the Irf7 gene and identified Bud13 as an RNA-binding protein that acts at this intron to increase the amount of successful splicing. Deficiency in Bud13 led to increased IR, decreased mature Irf7 transcript and protein levels, and consequently to a dampened type I interferon response. This impairment of Irf7 production in Bud13-deficient cells compromised their ability to withstand VSV infection. Global analysis of Bud13 knockdown and BUD13 cross-linking to RNA revealed a subset of introns that share many characteristics with the one found in Irf7 and are spliced in a Bud13-dependent manner. Deficiency of Bud13 led to decreased mature transcript from genes containing such introns. Thus, by acting as an antagonist to IR, Bud13 facilitates the expression of genes at which IR occurs.
Diversity and population genetic structure of the wax palmCeroxylon quindiuensein the Colombian Coffee Region
Authors: González-Rivillas Natalia , Bohórquez Adriana , Patricia Gutierrez Janeth , García-Merchán Víctor Hugo
Published: October 2018

The wax palm from Quindío (Ceroxylon quindiuense) is an icon of the cultural identity of the coffee growing eco-region and of all Colombia. Processes of urbanization, expansion of the agricultural and livestock area, among others, have increased its level of threat. Protecting this palm from extinction is important at an ecological level, given its function as a key species in Andean ecosystems. This work evaluated the diversity and population genetic structure of the wax palm from Quindío in five populations of the Colombian coffee region eco-region (Andean zone) by using ten microsatellite molecular markers. Two groups were identified at genetic diversity level, along with a heterozygote deficiency in all the populations possibly due to cryptic population structure effects mediated by loss of habitat. The five sampling units considered presented a total significant genetic structure, revealing a high degree of reproductive isolation. The results presented here add to the Conservation Plan for this species existing in Colombia.
The effect of butyrate-supplemented parenteral nutrition on intestinal defence mechanisms and the parenteral nutrition-induced shift in the gut microbiota
Authors: Jirsova Z , Heczkova M , Dankova H , Malinska H , Videnska P , Vespalcova H , Micenkova L , Bartonova L , Sticova E , Lodererova A , Prefertusová L. , Sekerkova A , Cahova M
Published: October 2018

Butyrate produced by the intestinal microbiota is essential for proper functioning of the intestinal immune system. Total dependence on parenteral nutrition (PN) is associated with numerous adverse effects, including severe microbial dysbiosis and loss of important butyrate producers. We hypothesised that a lack of butyrate produced by the gut microbiota may be compensated by its supplementation in PN mixtures. We tested whetheri.v.butyrate administration would (a) positively modulate intestinal defence mechanisms and (b) counteract PN-induced dysbiosis. Male Wistar rats were randomised to chow, PN, and PN supplemented with 9 mM butyrate (PN+But) for 12 days. Antimicrobial peptides, mucins, tight junction proteins and cytokine expression were assessed by RT-qPCR. T-cell subpopulations in mesenteric lymph nodes (MLN) were analysed by flow cytometry. Microbiota composition was assessed in caecum content. Butyrate supplementation resulted in increased expression of tight junction proteins (ZO-1, claudin-7, E-cadherin), antimicrobial peptides (Defa 8, Rd5, RegIIIγ) and lysozyme in the ileal mucosa. Butyrate partially alleviated PN-induced intestinal barrier impairment and normalised IL-4, IL-10 and IgA mRNA expression. PN administration was associated with an increase in Tregs in MLN, which was normalised by butyrate. Butyrate increased the total number of CD4+ and decreased a relative amount of CD8+ memory T cells in MLN. Lack of enteral nutrition and PN administration led to a shift in caecal microbiota composition. Butyrate did not reverse the altered expression of most taxa but did influence the abundance of some potentially beneficial/ pathogenic genera, which might contribute to its overall beneficial effect.
Bidirectional action of nitric oxide on mitochondrial respiration and permeability transition pore induced by calcium and palmitoylcarnitine
Authors: Dynnik Vladimir V. , Grishina Elena V. , Fedotcheva Nadezhda I
Published: October 2018

The role of mitochondrial calcium-dependent NO synthase in the control of respiration and mitochondrial permeability transition pore (MPTP) opening, as well as possible involvement of mitochondrial NO synthase/guanylate cyclase/kinase G-signaling system (mtNOS-SS) in the regulation of these processes are not sufficiently studied. In this work, using rat liver mitochondria, we applied specific inhibitors of the enzymes of this signaling system to evaluate its role in the control of respiration and MPTP. The respiration was supported by pyruvate and glutamate or succinate in the presence of hexokinase, glucose and ADP. The results indicate that L-arginine and NO donors SNP and SNAP produce bidirectional concentration-dependent effects on the respiration and MPTP opening evoked by calcium ions or D,L-palmitoylcarnitine. Maximal activation of respiration was observed at 20 µM of L-arginine or SNP. At low concentrations, L-arginine (to 500 µM) and NO donors (to 50 µM) increased the threshold concentrations of calcium and D,L-palmitoylcarnitine required for the dissipation of the mitochondrial membrane potential and pore opening. The application of the inhibitors of NO synthase, guanylate cyclase, and kinase G eliminated both effects. These data indicate the involvement of mtNOS-SS in the activation of respiration and deceleration of MPTP opening. At high concentrations, L-arginine and NO donors inhibited the respiration and promoted pore opening, indicating that the inhibition induced by NO excess dominates over the protection caused by mtNOS-SS. These results demonstrate that the functioning of mtNOS-SS might provide a feedforward activation of respiration and a lowering of MPTP sensitivity to calcium and palmitoylcarnitine overload.
Using pan RNA-seq analysis to reveal the ubiquitous existence of 5’ end and 3’ end small RNAs
Authors: Xu Xiaofeng , Ji Haishuo , Cheng Zhi , Jin Xiufeng , Yao Xue , Liu Yanqiang , Zhao Qiang , Zhang Tao , Ruan Jishou , Bu Wenjun , Chen Ze , Gao Shan
Published: October 2018

In this study, we used pan RNA-seq analysis to reveal the ubiquitous existence of 5’ end and 3’ end small RNAs. 5’ and 3’ sRNAs alone can be used to annotate mitochondrial with 1-bp resolution and nuclear non-coding genes and identify new steady-state RNAs, which are usually from functional genes. Using 5’, 3’ and intronic sRNAs, we revealed that the enzymatic dsRNA cleavage and RNAi could involve in the RNA degradation and gene expression regulation of U1 snRNA in human. The further study of 5’, 3’ and intronic sRNAs help rediscover double-stranded RNA (dsRNA) cleavage, RNA interference (RNAi) and the regulation of gene expression, which challenges the classical theories. In this study, we provided a simple and cost effective way for the annotation of mitochondrial and nuclear non-coding genes and the identification of new steady-state RNAs, particularly long non-coding RNAs (lncRNAs). We also provided a different point of view for cancer and virus, based on the new discoveries of dsRNA cleavage, RNAi and the regulation of gene expression.
Behavioral tagging in infant rats
Authors: Bae Sarah E. , Richardson Rick
Published: October 2018

Recent studies have shown that exposure to a novel environment may stabilize the persistence of weak memories, a phenomenon often attributed to a process referred to as “behavioral tagging.” While this phenomenon has been repeatedly demonstrated in adult animals, no studies to date have examined whether it occurs in infant animals, which is surprising given that infants exhibit an impaired ability to form long-term memories (LTMs). In the present study, infant (i.e., postnatal day (P) 17) rats were placed in a context and repeatedly shocked. Infant rats given brief open field exposure 1 h, but not 2 h, prior to conditioning exhibited enhanced retention when tested 1 d later (Experiments 1 and 2), but comparable retention when tested shortly after training (Experiment 2). Thus, exploration of an open field facilitates subsequent context fear memories by enhancing the persistence of the memory rather than strengthening the context-shock association at encoding. While exploration of an open field did not lead to better memory when animals were tested 3 d later (Experiment 3), a brief pretest shock led to a more pronounced reinstatement effect in rats exposed to the open field 1 h before conditioning (Experiment 4). Finally, unlike what has been reported in adults, Experiments 5 and 6 suggest that familiarization of the open field before subsequent exposure does not abolish the behavioral tagging effect in infants. Overall, while these findings suggest that similar behavioral tagging mechanisms to those reported in adults might be involved in the formation of LTMs in infant rats, they also suggest that there may be developmental differences in the retention of familiarization experiences.
Temporal order memory of the rat in spontaneous object recognition: effects of number of items, exposure interval, and retention time
Authors: Hatakeyama Taichi , Sugita Manami , Yamada Kazuo , Ichitani Yukio
Published: October 2018

Temporal order memory was analyzed using a spontaneous object recognition (SOR) paradigm in rats. In SOR, animals were allowed to explore freely two or five different objects sequentially in the sample phase, and then, two different objects shown in the sample phase were simultaneously presented, and exploration time of object shown earlier compared with that shown later was regarded as a discrimination index. Here we investigated the effects of (1) number of sample items, (2) sample exposure interval, and (3) retention time between the sample and test phases on temporal order memory in SOR. In experiment 1, rats showed significant discrimination between the objects presented earlier and later under five-item, but not two-item, condition. In experiment 2, using the five-item condition, longer retention time (between sample and test phases) induced lower discrimination and longer sample exposure interval produced higher discrimination. In experiment 3, using the two-item condition, longer sample exposure interval produced higher discrimination and longer retention time tended to make rats’ discrimination worse. Taken together, these results indicate that rats’ performance in this test paradigm was better with more sample items and longer exposure intervals as well as shorter retention time, suggesting that the familiarity to items and the temporal distance from the present to the occurrence of events affect temporal order memory.
Identification of therapeutic targets in chordoma through comprehensive genomic and transcriptomic analyses
Authors: Liang Winnie S. , Dardis Christopher , Helland Adrienne , Sekar Shobana , Adkins Jonathan , Cuyugan Lori , Enriquez Daniel , Byron Sara , Little Andrew S.
Published: October 2018

Chordoma is a rare, orphan cancer arising from embryonal precursors of bone. Surgery and radiotherapy (RT) provide excellent local control, often at the price of significant morbidity because of the structures involved and the need for relatively high doses of RT; however, recurrence remains high. Although our understanding of the genetic changes that occur in chordoma is evolving rapidly, this knowledge has yet to translate into treatments. We performed comprehensive DNA (paired tumor/normal whole-exome and shallow whole-genome) and RNA (tumor whole-transcriptome) next-generation sequencing analyses of archival sacral and clivus chordoma specimens. Incorporation of transcriptomic data enabled the identification of gene overexpression and expressed DNA alterations, thus providing additional support for potential therapeutic targets. In three patients, we identified alterations that may be amenable to off-label FDA-approved treatments for other tumor types. These alterations include FGFR1 overexpression (ponatinib, pazopanib) and copy-number duplication of CDK4 (palbociclib) and ERBB3 (gefitinib). In a third patient, germline DNA demonstrated predicted pathogenic changes in CHEK2 and ATM, which may have predisposed the patient to developing chordoma at a young age and may also be associated with potential sensitivity to PARP inhibitors because of homologous recombination repair deficiency. Last, in the fourth patient, a missense mutation in IGF1R was identified, suggesting potential activity for investigational anti-IGF1R strategies. Our findings demonstrate that chordoma patients present with aberrations in overlapping pathways. These results provide support for targeting the IGF1R/FGFR/EGFR and CDK4/6 pathways as treatment strategies for chordoma patients. This study underscores the value of comprehensive genomic and transcriptomic analysis in the development of rational, individualized treatment plans for chordoma.
RBF network based adaptive sliding mode control for solar sails
Authors: Lian Xiaobin , Liu Jiafu , Wang Chuang , Yuan Tiger , Cui Naigang
Published: October 2018

Purpose

The purpose of this paper is to resolve complex nonlinear dynamical problems of the pitching axis of solar sail in body coordinate system compared with inertial coordinate system. And saturation condition of controlled torque of vane in the orbit with big eccentricity ration, uncertainty and external disturbance under complex space background are considered.

Design/methodology/approach

The pitch dynamics of the sailcraft in the prescribed elliptic earth orbits is established considering the torques by the control vanes, gravity gradient and offset between the center-of-mass (cm) and center-of-pressure (cp). The maximal torques afforded by the control vanes are numerically determined for the sailcraft at any position with any pitch angle, which will be used as the restriction of the attitude control torques. The finite/infinite time adaptive sliding mode saturation controller and Bang–Bang–Radial Basis Function (RBF) controller are designed for the sailcraft with restricted attitude control torques. The model uncertainty and the input error (the error between real input and ideal control law input) are solved using the RBF network.

Findings

The finite true anomaly adaptive sliding mode saturation controller performed better than the other two controllers by comparing the numerical results in the paper. The control torque saturation, the model uncertainty and the external disturbance were also effectively solved using the infinite and finite time adaptive sliding mode saturation controllers by analyzing the numerical simulations. The stabilization of the pitch motion was accomplished within half orbit period.

Practical implications

The complex accurate dynamics can be approximated using the RBF network. The controllers can be applied to stabilization of spacecraft attitude dynamics with uncertainties in complex space environment.

Originality/value

Advanced control method is used in this paper; saturation of controlled torque of vane is resolved when the orbit with big eccentricity ration is considered and uncertainty and external disturbance under complex space background are settled. Moreover, complex and accurate nonlinear dynamical model of pitching axis of solar sail in body coordinate system compared with inertial coordinate system is provided.
Hardware-in-the-loop flight motion simulation of flexible variable sweep aircraft
Authors: Inayat Irum , Amin Rooh ul , Ali Malik Mazhar
Published: October 2018

Purpose

This paper aims to propose an improved and computationally efficient motion simulation of a flexible variable sweep aircraft.

Design/methodology/approach

The motion simulation is performed on hardware-in-the-loop simulation setup using 6 degree-of-freedom motion platform. The dynamic model of a flexible variable sweep aircraft, Rockwell B-1 Lancer is presented using equations of motions for combined rigid and flexible motions. The peak filter is introduced as a new method to separate flexible motion from aircraft motion data. Standard adaptive washout filter is modified and redesigned for an accurate flexible aircraft flight simulation. The flight data are generated using FlightGear software. Another motion profile with significant oscillations is also tested. The peak filter and the modified adaptive washout filter both are used to process the data according to the motion envelop of motion platform.

Findings

The performance of the modified adaptive washout filter is evaluated using hardware-in-the-loop simulation setup and results are compared with the standard adaptive washout filter. Results exhibit that the proposed method is computationally cost-effective and improves the motion simulation of flexible aircraft with close to realistic motion cues.

Originality/value

The proposed work presents motion simulation of a flexible aircraft by introducing a peak filter to extract flexible motion in contrast to the traditional motion separation methods. Also, a modified adaptive washout filter is designed and implemented in place of the traditional washout filters for improved flexible aircraft flight motion simulation.
A dynamic simplified Lund model for large-eddy simulation and its application to a centrifugal pump
Authors: Huang Xianbei , Qiu Baoyun , Guo Qiang , Liu Zhuqing , Yang Wei , Li Yaojun
Published: October 2018

Purpose

Construct a new sub-grid scale (SGS) model which can improve the efficiency and maintain comparative accuracy comparing to the existing dynamic cubic non-linear SGS model (DCNM).

Design/methodology/approach

The polynomial constitutive relation between the SGS stress tensor and both strain and rotation rate is selected as a basement. Simplification is achieved by eliminating the solid-body rotation term and adopting the assumption proposed by Kosovic. A dynamic procedure is applied to calculate three model coefficients in the new model. The new model (named dynamic simplified Lund model) and DCNM are applied to the rotating channel flow and the internal flow in a centrifugal pump impeller to examine the performance.

Findings

The new model is as accurate as DCNM but decreases 25 per cent computational resources. The ability of capturing rotation effect and reflecting backscatter is verified through cases. In addition, good numerical stability is shown during the calculation.

Research limitations/implications

More benchmark and engineering cases should be used to get further confidence on the new model.

Practical implications

The new model is promising in industrial application with the advantage of both accuracy and efficiency. For the flow with large-scale separation or more complicate phenomenon, the model is thought to give accurate flow structure.

Originality/value

A new non-linear SGS model is proposed in this paper. The accuracy, numerical stability and efficiency are validated for this model. Therefore, it is promising in the prediction of the flow structure in centrifugal pumps.
Numerical analysis for interphase forces of gas-liquid flow in a multiphase pump
Authors: Liu Ming , Cao Shan , Cao Shuliang
Published: October 2018

Purpose

The modeling of interphase forces plays a significant role in the numerical simulation of gas–liquid flow in a rotodynamic multiphase pump, which deserves detailed study.

Design/methodology/approach

Numerical analysis is conducted to estimate the influence of interphase forces, including drag force, lift force, virtual mass force, wall lubrication force and turbulent dispersion force.

Findings

The results show that the magnitude of the interphase forces can be sorted by: drag force > virtual mass force > lift force > turbulent dispersion force > wall lubrication force. The relations between interphase forces and velocity difference of gas–liquid flow and also the interphase forces and gas volume fraction are revealed. The distribution characteristics of interphase forces in the passages from impeller inlet to diffuser outlet are illustrated and analyzed. According to the results, apart from the drag force, the virtual mass force, lift force and turbulent dispersion force are required, whereas wall lubrication force can be neglected for numerical simulation of gas–liquid flow in a rotodynamic multiphase pump. Compared with the conventional numerical method which considers drag force only, the relative errors of predicted pressure rise and efficiency based on the proposed numerical method in account of four major forces can be reduced by 4.95 per cent and 3.00 per cent, respectively.

Originality value

The numerical analysis reveals the magnitude and distribution of interphase forces inside multiphase pump, which is meaningful for the simulation and design of multiphase pump.
Evidential uncertainty quantification of the Park–Ang damage model in performance based design
Authors: Tang Hesheng , Li Dawei , Deng Lixin , Xue Songtao
Published: October 2018

Purpose

This paper aims to develop a comprehensive uncertainty quantification method using evidence theory for Park–Ang damage index-based performance design in which epistemic uncertainties are considered. Various sources of uncertainty emanating from the database of the cyclic test results of RC members provided by the Pacific Earthquake Engineering Research Center are taken into account.

Design/methodology/approach

In this paper, an uncertainty quantification methodology based on evidence theory is presented for the whole process of performance-based seismic design (PBSD), while considering uncertainty in the Park–Ang damage model. To alleviate the burden of high computational cost in propagating uncertainty, the differential evolution interval optimization strategy is used for efficiently finding the propagated belief structure throughout the whole design process.

Findings

The investigation results of this paper demonstrate that the uncertainty rooted in Park–Ang damage model have a significant influence on PBSD design and evaluation. It might be worth noting that the epistemic uncertainty present in the Park–Ang damage model needs to be considered to avoid underestimating the true uncertainty.

Originality/value

This paper presents an evidence theory-based uncertainty quantification framework for the whole process of PBSD.
Waste identification diagram and value stream mapping
Authors: Dinis-Carvalho Jose , Guimaraes Levi , Sousa Rui M. , Leao Celina Pinto
Published: October 2018

Purpose

The purpose of this paper is to compare the well-known value stream mapping (VSM) with a recent tool named waste identification diagram (WID), regarding the capacity of information representation and easiness of interpretation.

Design/methodology/approach

The work begins with a brief literature review comparing the main tools for representation of production units, with special emphasis on VSM and WID, in terms of ability to identify several types of waste. Then, the authors developed the VSM and the WID of a specific production unit and after that several groups composed by students of Industrial Engineering (IE) and/or professionals from industry were asked to analyse/interpret only one of these diagrams. Finally, a questionnaire with closed and open questions was applied to the groups to evaluate the analysed tool.

Findings

In general, the results revealed that WID is more effective than VSM and participants recognized that most of the WID elements are relevant. Specifically, a measure coined overall effectiveness was applied (based on the response time and percentage of correct interpretations), indicating a clear advantage of WID (22 per cent of correct interpretations per minute) compared to VSM (9 per cent of correct interpretations per minute). The main drawback pointed to the WID is the lack of representation of the information flow.

Originality/value

This work contributes to the IE field by revealing WID as a new promising graphical tool for representation of production units, especially in terms of identification/quantification of wastes. The tool was quantitative and qualitatively evaluated by persons both from academia and industry.
Knowledge accumulation, development potential and efficiency evaluation: an example using the Hainan free trade zone
Authors: Song Malin , Wang Jing , Wang Shuhong , Zhao Danqing
Published: October 2018

Purpose

The establishment of free trade zones (FTZs) is an important experiment as part of the reform and opening up policy. This paper aims to focus on the issue of production efficiency of environmental protection enterprises in FTZs. Changes in the external and internal environments of enterprises can easily lead to changes in the production efficiencies of enterprises. The establishment of FTZs can change the external environment of enterprises. Knowledge accumulation changes the internal environment of enterprises. However, traditional efficiency analysis has usually ignored the internal and external heterogeneity of decision-making units, resulting in the distortion of the evaluation results.

Design/methodology/approach

This paper examines the relationship between knowledge accumulation and development potential based on financial data of environmental protection enterprises that were listed in Shanghai and Shenzhen A stocks, from 2009 to 2016. Then, through data envelopment analysis cross-efficiency analysis of the listed environmental protection enterprises from external heterogeneity, BP neural network model is set up.

Findings

The results show that the model set up in this paper is stable and reliable. The paper makes policy suggestions such as stimulating trade inside industry, quickening technological progress and enhancing environmental protection.

Originality/value

This paper analyzes the economy, environmental protection, science and technology and education to simulate the external environment of enterprises. Based on the experience data from the completion of Shanghai FTZ, this paper predicts the future development potential of Hainan FTZ enterprises.
Researchers’ online visibility: tensions of visibility, trust and reputation
Authors: Kjellberg Sara , Haider Jutta
Published: October 2018

Purpose

The purpose of this paper is to understand what role researchers assign to online representations on the new digital communication sites that have emerged, such as Academia, ResearchGate or Mendeley. How are researchers’ online presentations created, managed, accessed and, more generally, viewed by academic researchers themselves? And how are expectations of the academic reward system navigated and re-shaped in response to the possibilities afforded by social media and other digital tools?

Design/methodology/approach

Focus groups have been used for empirical investigation to learn about the role online representation is assigned by the concerned researchers.

Findings

The study shows that traditional scholarly communication documents are what also scaffolds trust and builds reputation in the new setting. In this sense, the new social network sites reinforce rather than challenge the importance of formal publications.

Originality/value

An understanding of the different ways in which researchers fathom the complex connection between reputation and trust in relation to online visibility as a measure of, or at least an attempt at, publicity (either within academia or outside it) is essential. This paper emphasizes the need to tell different stories by exploring how researchers understand their own practices and reasons for them.
School principals’ perceptions and requirements of school evaluators
Authors: Cohen-Azaria Yael , Zamir Sara
Published: October 2018

Purpose

The purpose of this paper is to examine the perceptions of school principals of the evaluator’s role and to learn about their requirements of school evaluators.

Design/methodology/approach

The current study is based on the qualitative paradigm of data collection and analysis. This paradigm provides a profound a description of the phenomenon in the context in which it takes place, based on the respondents’ perceptions and how they interpret their experiences. In the course of the study, the authors used semi-structured in-depth interviews.

Findings

Findings indicated that principals had regarded the role of the school evaluator mainly as that of an expert, a managerial partner and an implementer of school evaluation culture.

Research limitations/implications

The interviewers were the teachers who had been trained for the school evaluator’s position.

Practical implications

The “school evaluator” and the principals bear the complex task of evaluation on their shoulders, and their success in fulfilling it depends on their insights about how to delineate and implement the evaluator’s role. The paper outlines some crucial benchmarks for resolving the issue of role definitions between them.

Social implications

As a relatively new profession, derived from other professions and research areas, evaluation has no solid, historical occupational legacy in schools. This paper broadens the merit of school evaluator as the facilitator of quality assurance.

Originality/value

The increased responsibility placed on schools, the demand of accountability as well as transparency, have obliged the schools to broaden and deepen the internal evaluation activities. This paper reveals the essence of school evaluator’s role and suggests some key points for his/her valuable work.
Teacher evaluation following reform: the Israeli perspective
Authors: Avidov-Ungar Orit
Published: October 2018

Purpose

This study aims to examine teachers’ perceptions of teacher evaluation (also known as teacher appraisal). In Israel and elsewhere, teacher evaluation is a cornerstone of teaching quality assurance measures; however, detailed knowledge is lacking regarding how teachers themselves perceive it in that context.

Design/methodology/approach

Semi-structured interviews were conducted with 22 state primary school teachers. The data were analyzed thematically.

Findings

Four themes emerged from the interviews: how teachers conceive of teacher evaluation; teachers’ perceptions of how the teacher evaluation process should proceed; the advantages and disadvantages of the teacher evaluation process; and ways to increase the effectiveness of teacher evaluation. A further four themes emerged regarding the purposes of evaluation from the teachers’ perspective: judgment and control, dialogue, promotion and professional improvement. Overall, the teachers interviewed perceived that their evaluation serves summative control purposes far more than the formative professional improvement purposes for which the evaluation policy was explicitly developed. On the basis of these and previous findings, a theoretical model of teacher evaluation and career development is proposed.

Research limitations/implications

This qualitative study interviewed a relatively small number of teachers. The findings suggest that teacher evaluation conducted to assure quality teaching should be more comprehensive and should take place throughout the school year.

Originality/value

This study is one of only very few to examine teachers’ perceptions of teacher evaluation in detail.
The video cover letter: embedded assessment of oral communication skills
Authors: Sautter Elise Pookie , Zúñiga Miguel Angel
Published: October 2018

Purpose

This paper aims to describe the development and execution of the video cover letter exercise. This learning innovation challenges students to develop a concise, targeted marketing message using video technologies and tools.

Design/methodology/approach

In the first full semester of mandatory implementation, a pre-test/post-test design using McCroskey's measure of communication apprehension (CA) examined the effects of the exercise in reducing students' levels of CA. There were 200 students in the course, of which 139 completed both the pre-test and post-test measure survey. The measure captures overall levels of CA and more specifically examines anxiety associated with oral communication in group discussions, dyads, group meetings and public speaking.

Findings

Paired sample t-tests revealed that the CA was significantly reduced overall and more specifically in settings related to group discussions and public speaking. The tool provides an effective and efficient means for assessing basic oral communication skills. It also advances oral communication skills by significantly reducing levels of CA in undergraduate business students.

Originality/value

Oral communication skills are consistently ranked toward the top of faculty, student and recruiter lists of requisite skills for successful business graduates (Maes et al., 1997) and marketing majors more specifically (Nicholson et al., 2005). It is not surprising then that oral communication skills are also typically included as one of the most commonly assessed learning outcomes in college of business programs (Martell, 2007). Unfortunately, decreasing resources, growing class sizes and diverse course formats (e.g. online, face-to-face and blended) create ever growing challenges to effective development and assessment of oral communication skills in our marketing and business student populations.