bluuebunny/crossref_metadata_2025 huggingface dataset:
Needle EMG findings in different pathologies
Authors: Pitt Matthew
Published: November 2017

In this chapter, the inability of electromyography (EMG) to be able to further progress the diagnosis of myopathy on its own—requiring muscle biopsy and other modalities such as genetics to complete this process—is emphasized. The role of EMG particularly in the era of genetics is discussed. Findings in neurogenic abnormality are next described and the important hereditary conditions such as spinal muscular atrophy (SMA), distal SMA, Brown–Vialetto–Van Laere syndrome, segmental anterior horn cell disease, conditions with progressive bulbar palsy, SMARD1, and pontocerebellar hypoplasia with spinal muscle are discussed in detail. The differential diagnosis of 5q SMA type 1 is specifically outlined. Acquired forms of anterior horn disease, including Hirayama disease, poliomyelitis and enteropathic motor neuropathy, Hopkins syndrome, tumours, and vascular lesions are covered. There is discussion of the use of physiological tests to monitor progress in SMA, with tests including compound muscle action potential amplitude and motor unit number estimation. Finally, the important correlation between muscle biopsy and EMG is highlighted.
Investigation of channelopathies
Authors: Pitt Matthew
Published: November 2017

The chapter begins with a general description of the clinical findings in conditions where hyperexcitability occurs. These are divided into the dystrophic conditions, such as myotonia dystrophy, and the non-dystrophic conditions, which include myotonia congenita, paramyotonia congenita, and potassium-aggravated myotonia. Conditions where hypoexcitability occurs such as periodic paralysis are next discussed. The associated disorders of sodium, calcium, chloride, and potassium channels are described. Next, the protocols for the neurophysiological tests that are used in myotonia, and the short exercise test either at room temperature or after cooling are introduced. The different patterns seen in these tests are outlined and the algorithms allowing precise targeting of genetic testing explained. The inter-discharge interval calculation that can be used in delineating the causes of myotonia is discussed. Other conditions where prominent spontaneous activity occurs such as Schwartz–Jampel syndrome and Pompe’s disease are described. The chapter concludes with details of the long exercise test used in diagnosis of periodic paralysis.
Techniques used to test the neuromuscular junction in children
Authors: Pitt Matthew
Published: November 2017

The tests used to measure the neuromuscular junction function in children are repetitive nerve stimulation (RNS) and single-fibre electromyography (SFEMG). The physiological changes which explain abnormalities in RNS are covered in this chapter as are those affecting jitter measurement when measured by SFEMG. Practical considerations of how to perform RNS in children are discussed, along with the reasons for using SFEMG in preference to RNS and the need to use stimulation techniques. Controversies concerning so-called stimulated SFEMG including needle selection, filter settings, and the origin of the potentials that are being sampled are all discussed. The term stimulated potential analysis using concentric needle electrodes (SPACE) is introduced to divert most if not all of these criticisms. Derivation of normative data from previous studies is described as well as the use of e-norm methodology on laboratory data. The chapter concludes with practical measures of how to analyse the data collected and reference is made to the cross-correlation technique for determining abnormalities.
Pathophysiological associations in paediatric neuromuscular junction disorders
Authors: Pitt Matthew
Published: November 2017

Myasthenia can be caused by acquired or autoimmune conditions and other conditions resulting from genetic abnormalities of the proteins in the neuromuscular junction. The clinical clues to diagnosis in the paediatric population are highlighted in this chapter. Among these are sudden death, episodic apnoea, stridor, association with myopathy, and limb-girdle weakness presentation. Acquired disorders of the neuromuscular junction occur, such as infantile botulism, tick paralysis, and persistence of neuromuscular blocking agents. Some patterns of abnormality are seen in the neurophysiological findings, the most notable of which is a repetitive compound muscle action potential at low rates of stimulation. Decrement only seen after long-duration, high-frequency repetitive nerve stimulation is described in choline acetyltransferase (CHAT) abnormalities. DOK7 myasthenia may demonstrate patchy abnormalities of jitter and this is described along with the profound increment of the high-frequency repetitive nerve stimulation in Lambert–Eaton syndrome.
Results of the clinical application of SPACE in suspected disorders of the neuromuscular junction
Authors: Pitt Matthew
Published: November 2017

Findings in a large cohort of children with disorders of the neuromuscular junction are presented along with those in non-primary neuromuscular junction abnormalities. From these results it is possible to derive test parameters for stimulated potential analysis using concentric needle electrodes (SPACE) including sensitivity and specificity, along with positive and negative predictive values. The differences between performing stimulation techniques to determine jitter in children and adults are highlighted as are technical aspects and the effects of the differential diagnosis on interpretation of results. An investigative strategy is outlined to be used with SPACE. The chapter concludes with discussion of the occurrence of normal jitter measurements with SPACE in proven cases of myasthenia as well as the phenomenon of delayed diagnosis of myasthenia and its relationship to the availability of neurophysiological testing.
How to make a deal: the role of rankings and personal ties in creating trust in the mergers and acquisitions market
Authors: Boussard Valérie , Godechot Olivier , Woloszko Nicolas
Published: November 2017

On the mergers and acquisitions (M&A) market, buyers and sellers resort to experts in order to secure deals. But as these experts might be prone to opportunism, firms need to find a way to build trust. We identify two trust devices: social ties and public rankings. We explore whether these personal and impersonal devices are substitutes, independent or complementary. We study the French M&A market through a mixed-method approach. We show that both previous contacts and league table rankings of firms contribute to trust and to making deals. These trust devices are all the more likely to be used if the deal is risky, especially within the sell side (more at risk). We also find that firms tend to make deals only with other firms at the same level in the rankings. Finally, we find some evidence of substitution between rankings and personal ties, especially for low-value deals.
Structure of the nucleotide exchange factor eIF2B reveals mechanism of memory-enhancing molecule
Authors: Tsai Jordan C. , Miller-Vedam Lakshmi E. , Anand Aditya A. , Jaishankar Priyadarshini , Nguyen Henry C. , Renslo Adam R. , Frost Adam , Walter Peter
Published: November 2017

Regulation by the integrated stress response (ISR) converges on the phosphorylation of translation initiation factor eIF2 in response to a variety of stresses. Phosphorylation converts eIF2 from substrate to competitive inhibitor of its dedicated guanine nucleotide exchange factor, eIF2B, inhibiting translation. ISRIB, a drug-like eIF2B activator, reverses the effects of eIF2 phosphorylation and, remarkably, in rodents enhances cognition and corrects cognitive deficits after brain injury. To determine its mechanism of action, we solved an atomic-resolution structure of ISRIB bound in a deep cleft within decameric human eIF2B by electron cryo-microscopy. Structural and biochemical analyses revealed that formation of fully active, decameric eIF2B holoenzyme depended on the assembly of two identical tetrameric subcomplexes, and that ISRIB promoted this step by cross-bridging a central symmetry interface. Regulation of eIF2B assembly emerges as a rheostat for eIF2B activity that tunes translation during the ISR and that can be further modulated by ISRIB.
Phenotyping ciliary dynamics and coordination in response to CFTR-modulators and Thymosin-α1 in Cystic Fibrosis respiratory epithelial cells
Authors: Chioccioli M. , Feriani L. , Kotar J. , Bratcher P. E. , Cicuta P.
Published: November 2017

The diagnosis and treatment of respiratory disorders are challenging and would benefit from new approaches to systematically assess ciliary beating dynamics and to test new drugs. A novel approach based on multiscale differential dynamic microscopy (multi-DDM) is shown to quantitatively assess collective beating of cilia in a non-biased automated manner, in human airway epithelial cells (HAECs) derived from subjects with cystic fibrosis (CF) and grown in 2D air-liquid interface culture. Multi-DDM can readily detect changes in both ciliary beat frequency (CBF) and cilia coordination that result from perturbations to the mucosal layer. The efficacy of three CFTR-modulating treatments is investigated: ivacaftor (VX-770) with lumacaftor (VX-809), VX-809 alone and Thymosin alpha 1 (Tα1) alone. All three treatments restore coordination of cilia beating in the CF cells, albeit to varying degrees. We argue cilia are affected by these treatments through the physical properties of the mucus. Phenotyping cilia dynamics through multi-DDM provides novel insight into the response of ciliary beating following treatment with drugs, and has application in the broader context of respiratory disease and for drug screening.

One sentence summary

A semi-automated and unbiased assay based on multiscale differential dynamic microscopy (multi-DDM) detects changes in the coordination and frequency of ciliary beating in F508del/F508del primary human airway cells under different conditions and in response to CFTR-modulating compounds.
RNA G-quadruplexes mark repressive upstream open reading frames in human mRNAs
Authors: Murat Pierre , Marsico Giovanni , Herdy Barbara , Ghanbarian Avazeh , Portella Guillem , Balasubramanian Shankar
Published: November 2017

RNA secondary structures in the 5’ untranslated regions (UTRs) of mRNAs have been characterised as key determinants of translation initiation. However the role of non-canonical secondary structures, such as RNA G-quadruplexes (rG4s), in modulating translation of human mRNAs and the associated mechanisms remain largely unappreciated. Here we use a ribosome profiling strategy to investigate the translational landscape of human mRNAs with structured 5’ untranslated regions (5’-UTR). We found that inefficiently translated mRNAs, containing rG4-forming sequences in their 5’-UTRs, have an accumulation of ribosome footprints in their 5’-UTRs. We show that rG4-forming sequences are determinants of 5’-UTR translation, suggesting that the folding of rG4 structures thwarts the translation of protein coding sequences (CDS) by stimulating the translation of repressive upstream open reading frames (uORFs). To support our model, we demonstrate that depletion of two rG4s-specialised DEAH-box helicases, DHX36 and DHX9, shifts translation towards rG4-containing uORFs reducing the translation of selected transcripts comprising proto-oncogenes, transcription factors and epigenetic regulators. Transcriptome-wide identification of DHX9 binding sites using individual-nucleotide resolution UV crosslinking and immunoprecipitation (iCLIP) demonstrate that translation regulation is mediated through direct physical interaction between the helicase and its rG4 substrate. Our findings unveil a previously unknown role for non-canonical structures in governing 5’-UTR translation and suggest that the interaction of helicases with rG4s could be considered as a target for future therapeutic intervention.
Time course analysis of the brain transcriptome during transitions between brood care and reproduction in the clonal raider ant
Authors: Libbrecht Romain , Oxley Peter R. , Kronauer Daniel J. C.
Published: November 2017

Division of labor between reproductive queens and non-reproductive workers that perform brood care is the hallmark of insect societies. However, the molecular basis of this fundamental dichotomy remains poorly understood, in part because the caste of an individual cannot typically be experimentally manipulated at the adult stage. Here we take advantage of the unique biology of the clonal raider ant,Ooceraea biroi, where reproduction and brood care behavior can be experimentally manipulated in adults. To study the molecular regulation of reproduction and brood care, we induced transitions between both states, and monitored brain gene expression at multiple time points. We found that introducing larvae that inhibit reproduction and induce brood care behavior caused much faster changes in adult gene expression than removing larvae. The delayed response to the removal of the larval signal prevents untimely activation of reproduction inO. biroicolonies. This resistance to change when removing a signal also prevents premature modifications in many other biological processes. Furthermore, we found that the general patterns of gene expression differ depending on whether ants transition from reproduction to brood care orvice versa, indicating that gene expression changes between phases are cyclic rather than pendular. Our analyses also identify genes with large and early expression changes in one or both transitions. These genes likely play upstream roles in regulating reproduction and behavior, and thus constitute strong candidates for future molecular studies of the evolution and regulation of reproductive division of labor in insect societies.
Classification and characterisation of brain network changes in chronic back pain: a multicenter study
Authors: Mano Hiroaki , Kotecha Gopal , Leibnitz Kenji , Matsubara Takashi , Nakae Aya , Shenker Nicholas , Shibata Masahiko , Voon Valerie , Yoshida Wako , Lee Michael , Yanagida Toshio , Kawato Mitsuo , Rosa Maria , Seymour Ben
Published: November 2017

Chronic pain is a common and often disabling condition, and is thought to involve a combination of peripheral and central neurobiological factors. However, the extent and nature of changes in the brain is poorly understood. Here, we investigated brain network architecture using resting state fMRI data collected from chronic back pain patients in UK and Japan (41 patients, 56 controls). Using a machine learning approach (support vector machine), we found that brain network patterns reliably classified chronic pain patients in a third, independent open data set with an accuracy of 63%, whilst 68% was attained in cross validation of all data. We then developed a deep learning classifier using a conditional variational autoencoder, which also yield yielded 63% generalisation and 68% cross-validation accuracy. Given the existence of reliable network changes, we next studied the graph topology of the network, and found consistent evidence of hub disruption based on clustering and betweenness centrality of brain nodes in pain patients. To examine this in more detail, we developed a multislice modularity algorithm to identify a consensus pattern of modular reorganisation of brain nodes across the entire data set. This revealed evidence of significant changes in the modular identity of several brain regions, most notably including broad regions of bilateral sensorimotor cortex, subregions of which also contributed to classifier performance. These results provide evidence of consistent and characteristic brain network changes in chronic pain, and highlight extensive reorganisaton of the network architecture of sensorimotor cortex.
Effects of background and contour luminance on the hue and brightness of the Watercolor effect
Authors: Gerardin Peggy , Dojat Michel , Knoblauch Kenneth , Devinck Frederic
Published: November 2017

Conjoint measurement was used to investigate the joint influences of the luminance of the background and the inner contour on hue- and brightness filling-in for a stimulus configuration generating a water-color effect (WCE), i.e., a wiggly bi-chromatic contour enclosing a region with the lower luminance component on the exterior. Two stimuli with the background and inner contour luminances covarying independently were successively presented, and in separate experiments, the observer judged which member of the pair’s interior regions contained a stronger hue or was brighter. Braided-contour control stimuli that generated little or no perceptual filling-in were also used to assess whether observers were judging the interior regions and not the contours themselves. Three nested models of the contributions of the background and inner contour to the judgments were fit to the data by maximum likelihood and evaluated by likelihood ratio tests. Both stimulus components contributed to both the hue and brightness of the interior region with increasing luminance of the inner contour generating an assimilative filling-in for the hue judgments but a contrast effect for the brightness judgments. Control analyses showed negligible effects for the order of the luminance of the background or inner contour on the judgments. An additive contribution of both components was rejected in favor of a saturated model in which the responses depended on the levels of both stimulus components. For the hue judgments, increased background luminance led to greater hue filling-in at higher luminances of the interior contour. For the brightness judgments, the higher background luminance generated less brightness filling-in at higher luminances of the interior contour. The results indicate different effects of the inner contour and background on the induction of the brightness and coloration percepts of the WCE, suggesting that they are mediated by different mechanisms.
Effective population size and durability of plant resistances in the potato cyst nematodeGlobodera pallida
Authors: Montarry Josselin , Petit Eric J. , Bardou-Valette Sylvie , Mabon Romain , Jan Pierre-Loup , Fournet Sylvain , Grenier Eric
Published: November 2017

The effective size of a population is the size of an ideal population which would drift at the same rate as the real population. The balance between selection and genetic drift depends on the population size expressed as the genetically effective population size (Ne), rather than the real numbers of individuals in the population (N).

The objectives of the present study were to estimate Nein the potato cyst nematodeGlobodera pallidausing artificial populations and to explore the link between Neand the durability of plant resistances.

Using a temporal method on 24 independent pairs of initial and final populations, the median Newas 58 individuals.

Neis commonly lower than N but in our case the Ne/N ratio was extremely low becauseG. pallidapopulations deviate in structure from the assumptions of the ideal population by having unequal sex-ratios, high levels of inbreeding and a high variance in family sizes. The consequences of a low Necould be important for the control of phytoparasitic nematodes becauseG. pallidapopulations will have a low capacity to adapt to changing environments unless selection intensity is very strong, which could be greatly beneficial for long-term use of plant resistances.
Dense reconstruction of brain-wide neuronal population close to the ground truth
Authors: Hang Zhou , Shiwei Li , Anan Li , Feng Xiong , Ning Li , Jiacheng Han , Hongtao Kang , Yijun Chen , Yun Li , Wenqian Fang , Yidong Liu , Huimin Lin , Sen Jin , Zhiming Li , Fuqiang Xu , Yu-hui Zhang , Xiaohua Lv , Xiuli Liu , Hui Gong , Qingming Luo , Tingwei Quan , Shaoqun Zeng
Published: November 2017

Recent progresses allow imaging specific neuronal populations at single-axon level across mouse brain. However, digital reconstruction of neurons in large dataset requires months of human labor. Here, we developed a tool to solve this problem. Our tool offers a special error-screening system for fast localization of submicron errors in densely packed neurites and along long projection across the whole brain, thus achieving reconstruction close to the ground-truth. Moreover, our tool equips algorithms that significantly reduce intensive manual interferences and achieve high-level automation, with speed 5 times faster compared to semi-automatic tools. We also demonstrated reconstruction of 35 long projection neurons around one injection site of a mouse brain at an affordable time cost. Our tool is applicable with datasets of 10 TB or higher from various light microscopy, and provides a starting point for the reconstruction of neuronal population for neuroscience studies at a single-cell level.
A hidden Markov model approach to characterizing the photo-switching behavior of fluorophores
Authors: Patel Lekha , Gustafsson Nils , Lin Yu , Ober Raimund , Henriques Ricardo , Cohen Edward
Published: November 2017

Fluorescing molecules (fluorophores) that stochastically switch between photon-emitting and dark states underpin some of the most celebrated advancements in super-resolution microscopy. While this stochastic behavior has been heavily exploited, full characterization of the underlying models can potentially drive forward further imaging methodologies. Under the assumption that fluorophores move between fluorescing and dark states as continuous time Markov processes, the goal is to use a sequence of images to select a model and estimate the transition rates. We use a hidden Markov model to relate the observed discrete time signal to the hidden continuous time process. With imaging involving several repeat exposures of the fluorophore, we show the observed signal depends on both the current and past states of the hidden process, producing emission probabilities that depend on the transition rate parameters to be estimated. To tackle this unusual coupling of the transition and emission probabilities, we conceive transmission (transition-emission) matrices that capture all dependencies of the model. We provide a scheme of computing these matrices and adapt the forward-backward algorithm to compute a likelihood which is readily optimized to provide rate estimates. When confronted with several model proposals, combining this procedure with the Bayesian Information Criterion provides accurate model selection.
Immediate effects of psychosocial stress on attention depend on subjective experience and not directly on stress-related physiological changes
Authors: Palacios-García I. , Villena-Gonzalez M. , Campos-Arteaga G. , Artigas-Vergara C. , Jaramillo K. , López V. , Rodríguez E. , Silva J. R.
Published: November 2017

Acute psychosocial stress is associated with physiological, subjective and cognitive changes. In particular, attention, which is considered one of the main processes driving cognition, has been related to different stress outcomes, such as anxiety, cortisol levels and autonomic responses, individually. Nonetheless, their specific contributions to and association with attention is still not fully understood. To study this association, 42 male participants were asked to perform an attentional task just before and immediately after being exposed to either an experimental treatment designed to induce psychosocial stress using the Trier Social Stress Test (TSST) or a matching stress-free control condition. The salivary cortisol concentration, heart rate, and self-reported anxiety were measured to assess the physiological response to stress and the subjective experience during the protocol. As expected, psychosocial stress induced increases in heart rate, salivary cortisol levels and anxiety. The behavioral analysis revealed that members of the control group performed better on the attentional task after the protocol, while members of the TSST group showed no changes. Moreover, after dividing the stress group into sub-groups of participants with high and low anxiety, we observed that participants in the high-anxiety group not only failed to perform better but also performed worse. Finally, after testing several single-level mediation models, we found that anxiety is sufficient to explain the changes in attention and that it mediates the effects between heart rate and cortisol levels on attention. Our results suggest that the immediate effects of acute psychosocial stress on attention are highly dependent on the participant’s subjective experience, which, in turn, is affected and can mediate stress-related physiological changes.
Ring gyroscope sensitive element based on nanoporous alumina
Authors: Gorokh Gennady , Belahurau Yauhen , Zakhlebayeva Anna , Taratyn Igor , Khatko Viatcheslav
Published: November 2017

Purpose

This paper aims to present new technological approaches of manufacturing of micromechanical gyroscope ring-sensitive element based on the nanoporous anodic alumina instead of traditional silicon technology. Simulation and the operation analyses of such elements have been performed.

Design/methodology/approach

The design of gyroscope represents a sensitive element on a glass substrate; in the center of a ring, there is a permanent magnet in a steel box. The sensitive element is made of profiled nanoporous anodic alumina consisting of an octagonal frame which is connected to a ring in the center with eight N-shaped spokes. The technology of the sensitive element fabrication involves the electrochemical formation of nanoporous anodic alumina substrate given the thickness and porosity and its chemical etching on the element topology. The basic parameters and the operation principle of the nanoporous alumina-sensitive element have been defined by finite element simulation.

Findings

It is shown that the resonance frequencies of the sensitive element change as functions of the alumina porosity. The main parameters of the nanoporous alumina-sensitive element have been compared with parameters of a silicon-sensitive element. Calculations have shown that the mechanical deformations of the von Mises are approximately lower by two times in the nanoporous alumina-sensitive element.

Practical implications

High-precision angular rate measurement will be achieved by reducing mechanical and electrical noises practically to zero through careful designing of a ring magnetoelectric gyroscope

Originality/value

The ring resonator made of nanoporous anodic alumina will allow to increase the threshold of sensitivity and stability of micromechanical gyroscope characteristics owing to the high precision of geometric dimensions, the stability of the elastic properties and the quality factor.
Effect of J3 perturbation on satellite position in LEO
Authors: Qi Nai-ming , Sun Qilong , Yang Yong
Published: November 2017

Purpose

The purpose of this paper is to study the effect of J3 perturbation of the Earth’s oblateness on satellite orbit compared with J2 perturbation.

Design/methodology/approach

Based on the parametric variation method in the time domain, considering more accurate Earth potential function by considering J3-perturbation effect, the perturbation equations about satellite’s six orbital elements (including semi-major axis, orbit inclination, right ascension of the ascending node, true anomaly, eccentricity and argument of perigee) has been deduced theoretically. The disturbance effects of J2 and J3 perturbations on the satellite orbit with different orbit inclinations have been studied numerically.

Findings

With the inclination increasing, the maximum of the semi-major axis increases weakly. The difference of inclination disturbed by the J2 and J3 perturbation is relative to orbit inclinations. J3 perturbation has weak effect on the right ascension and argument of perigee. The critical angle of the right ascension and argument of perigee which decides the precession direction is 90° and 63.43°, respectively. The disturbance effects of J2 and J3 perturbations on the argument of perigee, right ascension and eccentricity are weakened when the eccentricity increases, simultaneously, the difference of J2 and J3 perturbations on argument of perigee, right ascension and argument of perigee decreases with eccentricity increasing, respectively.

Practical implications

In the future, satellites need to orbit the Earth much more precisely for a long period. The J3 perturbation effect and the weight compared to J2 perturbation in LEO can provide a theoretical reference for researchers who want to improve the control accuracy of satellite. On the other hand, the theoretical analysis and simulation results can help people to design the satellite orbit to avoid or diminish the disturbance effect of the Earth’s oblateness.

Originality/value

The J3 perturbation equations of satellite orbit elements are deduced theoretically by using parametric variation method in this paper. Additionally, the comparison studies of J2 perturbation and J3 perturbation of the Earth’s oblateness on the satellite orbit with different initial conditions are presented.
Computational modeling of the flow in a wind tunnel
Authors: Khalid Mahmood , Juhany Khalid A. , Hafez Salah
Published: November 2017

Purpose

The purpose of this paper is to use a computational technique to simulate the flow in a two-dimensional (2D) wind tunnel where the effect of the solid walls facing the model has been addressed using a porous geometry so that interference arriving at the solid walls are duly damped and a flow suction procedure has been adopted at the side wall to minimize the span-wise effect of the growing side wall boundary layer.

Design/methodology/approach

A CFD procedure based on discretization of the Navier–Stokes equations has been used to model the flow in a rectangular volume with appropriate treatment for solid walls of the confined volume in which the model is placed. The rectangular volume was configured by stacking O-Grid sections in a span-wise direction using geometric growth from the wall. A porous wall condition has been adapted to counter the wall interference signatures and a separate suction procedure has been implemented for reducing the side wall boundary layer effects.

Findings

It has been shown that through such corrective measures, the flow in a wind tunnel can be adequately simulated using computational modeling. Computed results were compared against experimental measurements obtained from IAR (Institute for Aerospace, Canada) and NAL (National Aeronautical Laboratory, Japan) to show that indeed appropriate corrective means may be adapted to reduce the interference effects.

Research limitations/implications

The solutions seemed to converge a lot better using relatively coarser grids which placed the shock locations closer to the experimental values. The finer grids were more stiff to converge and resulted in reversed flow with the two equation k-w model in the region where the intention was to draw out the fluid to thin down the boundary layer. The one equation Spalart–Allmaras model gave better result when porosity and wall suction routines were implemented.

Practical implications

This method could be used by industry to point check the results against certain demanding flow conditions and then used for more routine parametric studies at other conditions. The method would prove to be efficient and economical during early design stages of a configuration.

Originality/value

The method makes use of an O-grid to represent the confined test section and its dual treatment of wall interference and blockage effects through simultaneous application of porosity and boundary layer suction is believed to be quite original.
Orbital perturbation due to orbit-attitude coupling near asteroids
Authors: Wang Yue , Zhong Rui , Xu Shijie
Published: November 2017

Purpose

The purpose of this paper is to assess the orbital perturbation caused by the gravitational orbit–attitude coupling of spacecraft in the proximity of asteroids.

Design/methodology/approach

The gravitational orbit–attitude coupling perturbation (GOACP), which has been neglected before in the close-proximity orbital dynamics about asteroids, is investigated and compared with other orbital perturbations. The GOACP has its origin in the fact that the gravity acting on a non-spherical extended body is actually different from that acting on a point mass located at the body’s center of mass, which is the approximated model in the orbital dynamics. Besides, a case study of a tethered satellite system is given by numerical simulations.

Findings

It is found that the ratio of GOACP to the asteroid’s non-spherical gravity is the order of ρ/ae, where ρ is the spacecraft’s characteristic dimension and ae is the asteroid’s mean radius. It can also be seen that as ρ increases, GOACP will also increase but the solar radiation pressure (SRP) will decrease due to the decreasing area-to-mass ratio. The GOACP will be more significant than SRP at small orbital radii for a large-sized spacecraft. Based on the results by analyses and simulations, it can be concluded that GOACP needs to be considered in the orbital dynamics for a large-sized spacecraft in the proximity of a small asteroid.

Practical implications

This study is of great importance for the future asteroids missions for scientific explorations and near-Earth objects mitigation.

Originality/value

The GOACP, which has been neglected before, is revealed and studied.
Backstepping sliding mode control for formation flying spacecraft
Authors: Guo Yong , Song Shen-Min , Li Xue-Hui
Published: November 2017

Purpose

This paper aims to investigate the problem of finite-time consensus tracking control without unwinding for formation flying spacecraft in the presence of external disturbances.

Design/methodology/approach

Two distributed finite-time controllers are developed using the backstepping sliding mode. The first robust controller can compensate for external disturbances with known bounds, and the second one can compensate for external disturbances with unknown bounds.

Findings

Because the controllers are designed on the basis of rotation matrix, which represents the set of attitudes both globally and uniquely, the system can overcome the drawback of unwinding, which results in extra fuel consumption. Through introducing a novel virtual angular velocity, exchange of control signals between neighboring spacecraft becomes unnecessary, and it is able to reduce the communication burden.

Practical implications

The two robust controllers can deal with unwinding that may result in fuel consumption by traveling a long distance before returning to a desired attitude when the closed-loop system is close to the desired attitude equilibrium.

Originality/value

Two finite-time controllers without unwinding are proposed for formation flying spacecraft by using backstepping sliding mode. Furthermore, exchange of control signals between neighboring spacecraft is unnecessary.
Five-axis milling of sculptured surfaces of the turbine blade
Authors: Gdula Michal , Burek Jan , Zylka Lukasz , Plodzien Marcin
Published: November 2017

Purpose

The purpose of this paper is to determine the influence of a toroidal cutter axis orientation and a variable radius of curvature of the machined contour of sculptured surface on the five-axes milling process. Simulation and experimental research performed in this work are aimed to determine the relationship between the parameters of five-axes milling process and the shape and dimensional accuracy of curved outline of Inconel 718 alloy workpiece.

Design/methodology/approach

A subject of research are sculptured surfaces of the turbine blade. Simulation research was performed using the method of direct mapping tools in the CAD environment. The machining research was carried out with the use of multi-axis machining center DMU 100 monoBLOCK DMG, equipped with rotating dynamometer to measure the components of the cutting force. To control the shape and dimensional accuracy, the coordinate measuring machine ZEISS ACCURA II was used.

Findings

In this paper, the effect of the toroidal cutter axis orientation and the variable radius of curvature of the machined contour on the parameters of five-axes milling process and the accuracy of the sculptured surfaces was determined.

Practical implications

Five-axes milling with the use of a toroidal cutter is found in the aviation industry, where sculptured surfaces of the turbine blades are machined. The results of the research allow more precise planning of five-axes milling and increase of the turbine blades accuracy.

Originality/value

This paper significantly complements the current state of knowledge in the field of five-axes milling of turbine blades in terms of their accuracy.
Building affective commitment in a financial institution through an ambidexterity context
Authors: Cegarra-Navarro Juan-Gabriel , Jiménez-Jiménez Daniel , García-Pérez Alexeis , Del Giudice Manlio
Published: November 2017

Purpose

Ambidexterity refers to the tension between two different business models within the same organisation. This paper examines the significance of individuals’ knowledge exploration and exploitation activities in an organisation’s ambidexterity context, along with how they affect the creation of an affective commitment in the workforce. The study then investigates how an organisation’s ambidexterity vision contributes to employees’ affective commitment to learning.

Design/methodology/approach

These relationships are examined through an empirical investigation of 219 employees in the financial sector, using structural equation modelling validated by factor analysis.

Findings

The results indicate that for a firm to successfully achieve ambidexterity, its managers need to explicitly work to nurture a context where explorative and exploitative activities take place simultaneously. Another relevant contribution of this study has been addressing the impact that explorative and exploitative activities may have on affective commitment. The results suggest that while the effect of the ambidexterity context on the affective commitment by way of explorative activities is statistically insignificant, the effects of exploitative activities on affective commitment are statistically significant.

Originality/value

While the extant literature provides useful insights into the relationship between contextual ambidexterity and organisational performance, the relationship between ambidexterity and affective commitment has been less researched. This study has shown that an ambidexterity context is a key component in the process of combining knowledge structures in ways which are appropriate for both exploring value of that knowledge for the company and being effective in exploiting its memory.
Work-integrated learning and the importance of peer support and sense of belonging
Authors: McBeath Margaret , Drysdale Maureen T.B. , Bohn Nicholas
Published: November 2017

Purpose

The purpose of this paper is to explore the relationship between peer support and sense of belonging on the mental health and overall well-being, with a specific focus on comparing the perceptions of students in a work-integrated learning (WIL) program to those in a traditional non-WIL program.

Design/methodology/approach

Semi-structured group interviews were conducted with 25 participants, selected from a university with a WIL program. Interview data captured perceptions of peer support, sense of belonging, and how these influenced mental health, overall well-being, and confidence in making school-to-work transitions. Analysis followed the grounded theory approach of Glaser.

Findings

The analysis revealed that peer support and sense of belonging were essential protective factors for university student’s mental health and well-being, particularly during off-campus work terms or when transitioning to the labor market after graduation. Data suggested that participating in a WIL program can exacerbate students’ perceived barriers to accessing peer support resources and, in turn, lead to poor mental health.

Originality/value

The findings provide evidence for the importance of peer support and sense of belonging on mental health and help-seeking behaviors. Findings are important for the development of health programs, initiatives, and policies, particularly in light of the increase in mental illness amongst university students during their studies and as they prepare for the competitive labor market after graduation.
Analysing public sector continuous improvement: a systems approach
Authors: Elias Arun A. , Davis Dona
Published: November 2017

Purpose

The purpose of this paper is to analyse the complexities involved in implementing continuous improvement (CI) initiatives in public sector organisations.

Design/methodology/approach

This paper is based on a case study of a private sector organisation based in New Zealand and its efforts in implementing CI activities in its public sector clients. In total, 12 semi-structured interviews were followed by group model building exercises based on system dynamics that led to the development of a systems model.

Findings

CI initiatives using public-private partnerships were successful in steadily improving the operational excellence and end-user satisfaction in this case. But client satisfaction was only increasing at a much slower rate. The underlying structure responsible for this behaviour was captured using a causal loop model and explained using seven interacting feedback loops.

Research limitations/implications

The major limitation of this research is that it is confined to one private sector organisation and its public sector clients. Thus, the generalisability cannot be utilised for future reference.

Practical implications

This paper illustrates the development of strategic initiatives based on a participative model building approach. It provides a practical method for initiating long-term structural changes while managing CI activities in public sector organisations.

Originality/value

This paper contributes a New Zealand case of public-private partnerships for implementing CI initiatives. It illustrates a systems approach to analyse the complexities involved in implementing CI initiatives in public sector organisations.
How to measure post-purchase customer experience in online retailing? A scale development study
Authors: Kumar Amresh , Anjaly Bhawna
Published: November 2017

Purpose

The advent of e-retailing has created multiple options for customers. Hence, most important concern is to identify the experience which entices customers for repurchase from the one particular e-retailer. This paper tries to identify the customer experience with reference to activities happening post-purchase. The purpose of this paper is to develop and validate online post-purchase customer experience (OPPCE).

Design/methodology/approach

The methodology of this scale development study starts with skimming of relevant literature to identify the knowledge gap and prepare a theoretical background for the study. Then scientific method is applied for scale creation. First, items of the scale been identified through interviews of online shoppers and marketing experts. Then the major dimensions were identified through exploratory factor analysis applied on the data collected from active shoppers, who transacted online in last six months, with the help of a structured questionnaire survey. These data are analyzed through structural equation modeling to validate the scale.

Findings

The study yields that the scale for measuring OPPCE is multi-dimensional. It has six dimensions, i.e. delivery, product-in-hand, return and exchange, customer support, benefits and feel-good factors. The proper focus on the items of these dimensions can help e-retailers improve customer experience and increase repeat purchase.

Originality/value

Post-purchase activities have a significant impact on customer and their repeat purchase intensions. But it has not received its due attention particularly in the online context. Hence, this paper fills this knowledge gap and gives e-retailers a tool to enhance their customers’ experience.
Exploring consumer support for CSR from the perspective of moral legitimacy
Authors: Abdulrazak Sham , Amran Azlan
Published: November 2017

Purpose

The primary purpose of this paper is to explore and interpret the perceptions of Malaysian consumers regarding the factors that facilitate their market support for corporate social responsibility (CSR) through the lens of moral legitimacy.

Design/methodology/approach

This paper interprets qualitative data gathered from in-depth interviews with Malaysian consumers. The findings are then mapped to four forms of evaluations for moral legitimacy identified in the literature, towards establishing a conceptual model of consumer support for CSR.

Findings

Overall, six factors were identified as facilitating consumer market support for CSR. Of these, consumers were found to perceive strategic alignment between a firm’s business and its CSR as the most fundamental. In the absence of which, all other considerations are rendered irrelevant. Upon the requirement for alignment being met, the consumers then place emphasis on the manner by which a CSR activity is executed, for deciding whether to support or otherwise.

Practical implications

In contrast to previous reports in the literature concerning Malaysian consumers and CSR, the findings suggest that Malaysian consumers now have increased levels of awareness and maturity with regard to CSR, not unlike that of consumers in the West. Therefore, Malaysian firms will have to stop treating their CSR activities as an add-on, as has been reported previously, and they should endeavour to integrate their CSR into their overall business strategy.

Originality value

This paper offers an important insight about the consumers’ market support for CSR in the context of a developing nation.
Transmitting competencies at universities in Kazakhstan: intellectual capital of teachers
Authors: Sultanova Gulbakhyt , Svyatov Serik , Ussenbayev Nurzhan
Published: November 2017

Purpose

The purpose of this paper is to measure individual intellectual capital (IC) of academic staff as well as to test its impact on the employability readiness of future graduates and the reduction of the discrepancy between competencies developed and grades obtained with the help of two indicators, i.e. intellectual capital indicator (ICI) and employability readiness indicator (ERI). While ICI measures the level of a teacher’s competencies to be transmitted in the education process, ERI measures the level of a student’s competencies developed after completing relevant courses.

Design/methodology/approach

This is an empirical research carried out in the form of a case study. Regression model is applied to find the influence of ICI on ERI. The minimisation problem is set with relevant constraints to decrease the discrepancy between ERI and traditional grade point average (GPA).

Findings

The data were collected at one Kazakh university and from experts from academia and industry by means of documentary analysis, specialised tests and structured interviews. The direct impact of ICI on ERI is confirmed and the optimal level of ICI that permits an effective decrease in the discrepancy between ERI and GPA is identified.

Research limitations/implications

A longitudinal study covering more programmes is necessary to draw conclusions concerning causality. The application of ICI as a university’s management tool is shown.

Originality/value

The novelty of this study lies in providing a consistent and simple approach for calculating a teacher’s IC and its impact on a student’s employability readiness.