bluuebunny/crossref_metadata_2025 huggingface dataset:
Hemorrhagic Shock/Resuscitation Reduces the M2 Phenotype of Alveolar Macrophages: A Potential Mechanism Contributing to Increased LPS-Induced Lung Injury
Authors: Safavian Dana , Leung Chung Ho , Kapus Andras , Ailenberg Menachem , Szaszi Katalin , Shani Ravi , Di Ciano-Oliveira Caterina , Ghazarian Magar , Rotstein Ori
Published: March 2018

Major hemorrhage is a significant contributor to the morbidity and mortality resulting from traumatic injury. In addition to its role in in early mortality, hemorrhagic shock followed by resuscitation (HS/R) is known to initiate immunological events that contribute to the development of organ dysfunction. The pathogenesis of acute lung injury following HS/R involves macrophage activation. Recent studies have shown that macrophage function may in part be regulated by polarization toward classical M1 pro-inflammatory cells or alternatively activated anti-inflammatory M2 cells. We hypothesized that alteration in the M1/M2 phenotypic balance of alveolar macrophages in the lung may contribute to a pro-inflammatory state following HS/R. Using a murine model, we show that HS/R causes a rapid reduction in surface cluster of differentiation (CD)206 and CD36, markers of M2 cells, as well as in CD206 messenger ribonucleic acid (mRNA). M1 markers including surface CD80 and tumour necrosis factor alpha and inducible nitric oxide synthase mRNA were increased, albeit in a somewhat delayed time course. The prostaglandin 5-deoxyDelta12,14 prostaglandin J2 (15d-PGJ2), known to polarize cells toward M2, restored levels of M2 macrophages toward control and prevented lung injury, as assessed by bronchoalveolar protein content. Adoptive cell transfer of in vitro M2 polarized macrophages also reduced lung inflammation/injury following hemorrhagic shock. Together, these studies demonstrate that HS/R increases M1/M2 ratio, predominantly by lowering M2 cells, and thus enhances the proinflammatory state. Various strategies aimed at promoting M2 polarization may lessen the magnitude of inflammation and injury. This represents a novel approach to the prevention/treatment of lung injury in critically ill trauma patients.
Virtual ChIP-seq: predicting transcription factor binding by learning from the transcriptome
Authors: Karimzadeh Mehran , Hoffman Michael M.
Published: March 2018

Motivation

Identifying transcription factor binding sites is the first step in pinpointing non-coding mutations that disrupt the regulatory function of transcription factors and promote disease. ChIP-seq is the most common method for identifying binding sites, but performing it on patient samples is hampered by the amount of available biological material and the cost of the experiment. Existing methods for computational prediction of regulatory elements primarily predict binding in genomic regions with sequence similarity to known transcription factor sequence preferences. This has limited efficacy since most binding sites do not resemble known transcription factor sequence motifs, and many transcription factors are not even sequence-specific.

Results

We developed Virtual ChIP-seq, which predicts binding of individual transcription factors in new cell types using an artificial neural network that integrates ChIP-seq results from other cell types and chromatin accessibility data in the new cell type. Virtual ChIP-seq also uses learned associations between gene expression and transcription factor binding at specific genomic regions. This approach outperforms methods that predict TF binding solely based on sequence preference, pre-dicting binding for 36 transcription factors (Matthews correlation coefficient > 0.3).

Availability

The datasets we used for training and validation are available athttps://virchip.hoffmanlab.org. We have deposited in Zenodo the current version of our software (http://doi.org/10.5281/zenodo.1066928), datasets (http://doi.org/10.5281/zenodo.823297), predictions for 36 transcription factors on Roadmap Epigenomics cell types (http://doi.org/10.5281/zenodo.1455759), and predictions in Cistrome as well as ENCODE-DREAMin vivoTF Binding Site Prediction Challenge (http://doi.org/10.5281/zenodo.1209308).
The yeast core spliceosome maintains genome integrity through R-loop prevention and α-tubulin expression
Authors: Tam Annie S. , Mathew Veena , Sihota Tianna S. , Zhang Anni , Stirling Peter C.
Published: March 2018

To achieve genome stability cells must coordinate the action of various DNA transactions including DNA replication, repair, transcription and chromosome segregation. How transcription and RNA processing enable genome stability is only partly understood. Two predominant models have emerged: one involving changes in gene expression that perturb other genome maintenance factors, and another in which genotoxic DNA:RNA hybrids, called R-loops, impair DNA replication. Here we characterize genome instability phenotypes in a panel yeast splicing factor mutants and find that mitotic defects, and in some cases R-loop accumulation, are causes of genome instability. Genome instability in splicing mutants is exacerbated by loss of the spindle-assembly checkpoint protein Mad1. Moreover, removal of the intron from the α-tubulin gene TUB1 restores genome integrity. Thus, while R-loops contribute in some settings, defects in yeast splicing predominantly lead to genome instability through effects on gene expression.
Morphology of Mitochondria in Spatially Restricted Axons Revealed by Cryo-Electron Tomography
Authors: Fischer Tara D. , Dash Pramod K. , Liu Jun , Waxham M. Neal
Published: March 2018

Neurons project axons to local and distal sites and can display heterogeneous morphologies with limited physical dimensions that may influence the structure of large organelles such as mitochondria. Using cryo-electron tomography (cryo-ET), we characterized native environments within axons and presynaptic varicosities to examine whether spatial restrictions within these compartments influence the morphology of mitochondria. Segmented tomographic reconstructions revealed distinctive morphological characteristics of mitochondria residing at the narrowed boundary between presynaptic varicosities and axons with limited physical dimensions (~80 nm), compared to mitochondria in non-spatially restricted environments. Furthermore, segmentation of the tomograms revealed discrete organizations between the inner and outer membranes, suggesting possible independent remodeling of each membrane in mitochondria at spatially restricted axonal/varicosity boundaries. Thus, cryo-ET of mitochondria within axonal subcompartments reveals that spatial restrictions do not obstruct mitochondria from residing within them but limited available space can influence their gross morphology and the organization of the inner and outer membranes. These findings offer new perspectives on the influence of physical and spatial characteristics of cellular environments on mitochondrial morphology and highlights the potential for remarkable structural plasticity of mitochondria to adapt to spatial restrictions within axons.
Clonal expansion of mitochondrial DNA deletions is a private mechanism of ageing in long-lived animals
Authors: Lakshmanan Lakshmi Narayanan , Yee Zhuangli , Ng Li Fang , Gunawan Rudiyanto , Halliwell Barry , Gruber Jan
Published: March 2018

Disruption of mitochondrial metabolism and loss of mitochondrial DNA (mtDNA) integrity are widely considered as evolutionarily conserved (public) mechanisms of ageing (López-Otín et al. 2013). Human ageing is associated with loss in skeletal muscle mass and function (Sarcopenia), contributing significantly to morbidity and mortality. Muscle ageing is associated with loss of mtDNA integrity. In humans, clonally expanded mtDNA deletions co-localize with sites of fiber-breakage and atrophy in skeletal muscle. mtDNA deletions may therefore play an important, possibly causal role in sarcopenia. The nematode Caenorhabditis elegans also exhibits age-dependent decline in mitochondrial function and a form of sarcopenia. However, it is unclear if mtDNA deletions play a role in C. elegans ageing. Here we report identification of 266 novel mtDNA deletions in ageing nematodes. Analysis of the mtDNA mutation spectrum and quantification of mutation burden indicates that (1) mtDNA deletions in nematode is extremely rare, (2) there is no significant age-dependent increase in mtDNA deletions and (3) there is little evidence for clonal expansion driving mtDNA deletion dynamics. Thus, mtDNA deletions are unlikely to drive the age-dependent functional decline commonly observed in C. elegans. Computational modelling of mtDNA dynamics in C. elegans indicates that the lifespan of short-lived animals such as C. elegans is likely too short to allow for significant clonal expansion of mtDNA deletions. Together, these findings suggest that clonal expansion of mtDNA deletions is likely a private mechanism of ageing predominantly relevant in long-lived animals such as humans and rhesus monkey and possibly in rodents.
The hippocampal film-editor: sensitivity and specificity to event boundaries in continuous experience
Authors: Ben-Yakov Aya , Henson Richard
Published: March 2018

The function of the human hippocampus is normally investigated by experimental manipulation of discrete events. Less is unknown about what triggers hippocampal activity during more naturalistic, continuous experience. We hypothesized that the hippocampus would be sensitive to the occurrence of event boundaries, i.e. moments in time identified by observers as a transition between events. To address this, we analysed functional MRI data from two groups: one (N=253, 131 female) who viewed an 8.5min film and another (N=15, 6 female) who viewed a 120min film. We observed a strong hippocampal response at boundaries defined by independent observers, which was modulated by boundary strength (the number of observers that identified each boundary). In the longer film, there were sufficient boundaries to show that this modulation remained after covarying out a large number of perceptual factors. The hippocampus was the only brain region whose response showed a significant monotonic increase with boundary strength in both films, suggesting that modulation by boundary strength is selective to the hippocampus. This hypothesis-driven approach was complemented by a data-driven approach, in which we identified hippocampal-events as moments in time with the strongest hippocampal activity: The correspondence between these hippocampalevents and event boundaries was highly-significant, revealing that the hippocampal response is not only sensitive, but also specific to event boundaries. We conclude that the hippocampus plays an important role in segmenting the continuous experience that is typical of naturalistic settings.

Significance statement

Recent years have seen the field of human neuroscience research transitioning from experiments with simple stimuli to the study of more complex and naturalistic experience. Nonetheless, our understanding of the function of many brain regions, such as the hippocampus, is based primarily on the study of brief, discrete events. As a result, we know little of what triggers hippocampal activity in real-life settings, when we are exposed to a continuous stream of information. When does the hippocampus “decide” to respond during the encoding of naturalistic experience? We reveal here that hippocampal activity measured by fMRI during film-watching is both sensitive and specific to event boundaries, identifying a potential mechanism whereby event boundaries shape experience by modulation of hippocampal activity.
GenBank 2 Sequin - a file converter preparing custom GenBank files for database submission
Authors: Lehwark Pascal , Greiner Stephan
Published: March 2018

The typical wet lab user often annotates smaller sequences in the GenBank format, but resulting files are not accepted for database submission by NCBI. This makes submission of such annotations a cumbersome task. Here we present “GenBank 2 Sequin” an easy-to-use web application that converts custom annotations in the GenBank format into the NCBI direct submission format Sequin. Additionally, the program generates a “five-column, tab-delimited feature table” and a FASTA file required for submission through BankIt or for the update an existing GenBank entry. We specifically developed “GenBank 2 Sequin” for the regular wet lab researcher with strong focus on user-friendliness and flexibility. It is equipped with an intuitive graphical interface and a comprehensive documentation. The application can be employed to prepare any GenBank file for database submission. It is freely available online at https://chlorobox.mpimp-golm.mpg.de/GenBank2Sequin.html.
Microbiome-TP53 Gene Interaction in Human Lung Cancer
Authors: Greathouse K. Leigh , White James R. , Vargas Ashely J. , Bliskovsky Valery V. , Beck Jessica A. , Muhlinen Natalia von , Polley Eric C. , Bowman Elise D. , Khan Mohammed A. , Robles Ana I. , Cooks Tomer , Ryan Bríd M. , Dzutsev Amiran H. , Trinchieri Giorgio , Pineda Marbin A. , Bilke Sven , Meltzer Paul S. , Hokenstad Alexis N. , Stickrod Tricia M. , Walther-Antonio Marina R. , Earl Joshua P. , Mell Joshua C. , Krol Jaroslaw E. , Balashov Sergey V. , Bhat Archana S. , Ehrlich Garth D. , Valm Alex , Deming Clayton , Conlan Sean , Oh Julia , Segre Julie A. , Harris Curtis C.
Published: March 2018

Background

Lung cancer is the leading cancer diagnosis worldwide and the number one cause of cancer deaths. Exposure to cigarette smoke, the primary risk factor in lung cancer, reduces epithelial barrier integrity and increases susceptibility to infections. Herein, we hypothesized that somatic mutations together with cigarette smoke generate a dysbiotic microbiota that is associated with lung carcinogenesis. Using lung tissue from controls (n=33) and cancer cases (n=143), we conducted 16S rRNA bacterial gene sequencing, with RNA-seq data from lung cancer cases in The Cancer Genome Atlas (n=1112) serving as the validation cohort.

Results

Overall, we demonstrate a lower alpha diversity in normal lung as compared to non-tumor adjacent or tumor tissue. In squamous cell carcinoma (SCC) specifically, a separate group of taxa were identified, in which Acidovorax was enriched in smokers (P =0.0013). Acidovorax temporans was identified by fluorescent in situ hybridization within tumor sections, and confirmed by two separate 16S rRNA strategies. Further, these taxa, including Acidovorax, exhibited higher abundance among the subset of SCC cases with TP53 mutations, an association not seen in adenocarcinomas (AD).

Conclusions

The results of this comprehensive study show both a microbiome-gene and microbiome-exposure interactions in SCC lung cancer tissue. Specifically, tumors harboring TP53 mutations, which can damage epithelial function, have a unique bacterial consortia which is higher in relative abundance in smoking-associated SCC. Given the significant need for clinical diagnostic tools in lung cancer, this study may provide novel biomarkers for early detection.
Genome-wide diversity in temporal and regional populations of the betabaculovirusErinnyis ello granulovirus(ErelGV)
Authors: Brito A. F. , Melo F. L. , Ardisson-Araújo D. M. P , Sihler W. , Souza M. L. , Ribeiro B.M.
Published: March 2018

Background

Erinnyis ello granulovirus(ErelGV) is a betabaculovirus infecting caterpillars of the sphingid mothE. ello ello(cassava hornworm), an important pest of cassava crops (Manihot esculenta). In this study, the genome of seven field isolates of the virus ErelGV were deep sequenced and their inter-and intrapopulational sequence diversity were analyzed.

Results

No events of gene gain/loss or translocations were observed, and indels were mainly found within highly repetitive regions (direct repeats,drs). A naturally occurring isolate from Northern Brazil (Acre State, an Amazonian region) has shown to be the most diverse population, with a unique pattern of polymorphisms. Overall, non-synonymous substitutions were found all over the seven genomes, with no specific gathering of mutations on hotspot regions. Independently of their sizes, some ORFs have shown higher levels of non-synonymous changes than others. Non-core genes of known functions and structural genes were among the most diverse ones; and as expected, core genes were the least variable genes. We observed remarkable differences on diversity of paralogous genes, as in multiple copies ofp10, fgf, andpep. Another important contrast on sequence diversity was found on genes encoding complex subunits and/or involved in the same biological processes, aslate expression factors(lefs) andper os infectivity factors(pifs). Interestingly, several polymorphisms in coding regions lie on sequences encoding specific protein domains.

Conclusions

By comparing and integrating information about inter-and intrapopulational diversity of viral isolates, we provide a detailed description on how evolution operates on field isolates of a betabaculovirus. Our results revealed that 35-41% of the SNPs of ErelGV lead to amino acid changes (non-synonymous substitutions). Some genes, especially non-core genes of unknown functions, tend to accumulate more mutations, while core genes evolve slowly and are more conserved. Additional studies would be necessary to understand the actual effects of such gene variations on viral infection and fitness.
Modulation of input sensitivity and output gain by retinal amacrine cells
Authors: Nategh Neda , Manu Mihai , Baccus Stephen A.
Published: March 2018

The prevailing hierarchical view of the visual system consists of parallel circuits that begin in the retina, which then sum effects across sequential levels, increasing in complexity. Yet a separate type of interaction, whereby one visual pattern changes the influence of another, known as modulation, has received much less attention in terms of its circuit mechanisms. Retinal amacrine cells are a diverse class of inhibitory interneurons that are thought to have modulatory effects, but we lack a general understanding of their functional types. Using dynamic causal experiments in the salamander retina perturbing amacrine cells along with an unsupervised computational framework, we find that amacrine cell modulatory effects cluster into two distinct types. One type controls ganglion cell sensitivity to individual visual features, and a second type controls the ganglion cell’s output gain, acting to gate all features. These results establish three separate general roles of amacrine cells – to generate primary visual features, to use context to select specific visual features and to gate retinal output.
The ecology of the Drosophila-yeast mutualism in wineries
Authors: Quan Allison S. , Eisen Michael B.
Published: March 2018

The fruit fly, Drosophila melanogaster, is preferentially found on fermenting fruits. The yeasts that dominate the microbial communities of these substrates are the primary food source for developing D. melanogaster larvae, and adult flies manifest a strong olfactory system-mediated attraction for the volatile compounds produced by these yeasts during fermentation. Although most work on this interaction has focused on the standard laboratory yeast Saccharomyces cerevisiae, a wide variety of other yeasts naturally ferment fallen fruit. Here we address the open question of whether D. melanogaster preferentially associates with distinct yeasts in different, closely-related environments. We characterized the spatial and temporal dynamics of Drosophila-associated fungi in Northern California wineries that use organic grapes and natural fermentation using high-throughput, short-amplicon sequencing. We found that there is nonrandom structure in the fungal communities that are vectored by flies both between and within vineyards. Within wineries, the fungal communities associated with flies in cellars, fermentation tanks, and pomace piles are distinguished by varying abundances of a small number of yeast species. To investigate the origins of this structure, we assayed Drosophila attraction to, oviposition on, larval development in, and longevity when consuming the yeasts that distinguish vineyard microhabitats from each other. We found that wild fly lines did not respond differentially to the yeast species that distinguish winery habitats in habitat specific manner. Instead, this subset of yeast shares traits that make them attractive to and ensure their close association with Drosophila.
Genome-reconstruction for eukaryotes from complex natural microbial communities
Authors: West Patrick T. , Probst Alexander J. , Grigoriev Igor V. , Thomas Brian C. , Banfield Jillian F.
Published: March 2018

Microbial eukaryotes are integral components of natural microbial communities, and their inclusion is critical for many ecosystem studies, yet the majority of published metagenome analyses ignore eukaryotes. In order to include eukaryotes in environmental studies, we propose a method to recover eukaryotic genomes from complex metagenomic samples. A key step for genome recovery is separation of eukaryotic and prokaryotic fragments. We developed ak-mer-based strategy, EukRep, for eukaryotic sequence identification and applied it to environmental samples to show that it enables genome recovery, genome completeness evaluation, and prediction of metabolic potential. We used this approach to test the effect of addition of organic carbon on a geyser-associated microbial community and detected a substantial change of the community metabolism, with selection against almost all candidate phyla bacteria and archaea and for eukaryotes. Near complete genomes were reconstructed for three fungi placed within the Eurotiomycetes and an arthropod. While carbon fixation and sulfur oxidation were important functions in the geyser community prior to carbon addition, the organic carbon-impacted community showed enrichment for secreted proteases, secreted lipases, cellulose targeting CAZymes, and methanol oxidation. We demonstrate the broader utility of EukRep by reconstructing and evaluating relatively high-quality fungal, protist, and rotifer genomes from complex environmental samples. This approach opens the way for cultivation-independent analyses of whole microbial communities.
RAINBOWS: refractive analysis of the incoming neutron beam over the white spectrum. A new fast neutron reflectometry technique exploiting a focusing prism
Authors: Cubitt Robert , Segura Ruiz Jaime , Jark Werner
Published: March 2018

Neutron reflectivity is a powerful technique for characterizing interfaces in many areas of science. The traditional method of time of flight for measuring the wavelength of neutrons in a white beam is extremely wasteful, as the vast majority of neutrons must be absorbed in the choppers in order to produce a pulsed beam. A prism operates continuously, with a transmission up to two orders of magnitude higher than choppers. The wavelength-dependent deflection of the beam by the prism, coupled with a high spatial resolution detector, results in excellent wavelength resolution. The theory of how the resolution is considerably enhanced by curving the surface of the prism is described in detail for a real experimental arrangement. It is demonstrated how this can be used for faster neutron reflectometry, including the merging of different angles and subtraction of background. The technique shows considerable promise for neutron reflectivity, opening up new areas of science particularly in the realms of kinetics and small samples.
Influence of microstructure morphology on multi-scale modeling of low-alloyed TRIP-steels
Authors: Prüger Stefan , Gandhi Ashutosh , Balzani Daniel
Published: March 2018

Purpose

The purpose of this study is to quantify the impact of the variation of microstructural features on macroscopic and microscopic fields. The application of multi-scale methods in the context of constitutive modeling of microheterogeneous materials requires the choice of a representative volume element (RVE) of the considered microstructure, which may be based on some idealized assumptions and/or on experimental observations. In any case, a realistic microstructure within the RVE is either computationally too expensive or not fully accessible by experimental measurement techniques, which introduces some uncertainty regarding the microstructural features.

Design/methodology/approach

In this paper, a systematical variation of microstructural parameters controlling the morphology of an RVE with an idealized microstructure is conducted and the impact on macroscopic quantities of interest as well as microstructural fields and their statistics is investigated. The study is carried out under macroscopically homogeneous deformation states using the direct micro-macro scale transition approach.

Findings

The variation of microstructural parameters, such as inclusion volume fraction, aspect ratio and orientation of the inclusion with respect to the overall loading, influences the macroscopic behavior, especially the micromechanical fields significantly.

Originality/value

The systematic assessment of the impact of microstructural parameters on both macroscopic quantities and statistics of the micromechanical fields allows for a quantitative comparison of different microstructure morphologies and a reliable identification of microstructural parameters that promote failure initialization in microheterogeneous materials.
Efficient hybrid algorithms to solve mixed discrete-continuous optimization problems
Authors: Liu Dianzi , Liu Chengyang , Zhang Chuanwei , Xu Chao , Du Ziliang , Wan Zhiqiang
Published: March 2018

Purpose

In real-world cases, it is common to encounter mixed discrete-continuous problems where some or all of the variables may take only discrete values. To solve these non-linear optimization problems, the use of finite element methods is very time-consuming. The purpose of this study is to investigate the efficiency of the proposed hybrid algorithms for the mixed discrete-continuous optimization and compare it with the performance of genetic algorithms (GAs).

Design/methodology/approach

In this paper, the enhanced multipoint approximation method (MAM) is used to reduce the original nonlinear optimization problem to a sequence of approximations. Then, the sequential quadratic programing technique is applied to find the continuous solution. Following that, the implementation of discrete capability into the MAM is developed to solve the mixed discrete-continuous optimization problems.

Findings

The efficiency and rate of convergence of the developed hybrid algorithms outperforming GA are examined by six detailed case studies in the ten-bar planar truss problem, and the superiority of the Hooke–Jeeves assisted MAM algorithm over the other two hybrid algorithms and GAs is concluded.

Originality/value

The authors propose three efficient hybrid algorithms, the rounding-off, the coordinate search and the Hooke–Jeeves search-assisted MAMs, to solve nonlinear mixed discrete-continuous optimization problems. Implementations include the development of new procedures for sampling discrete points, the modification of the trust region adaptation strategy and strategies for solving mix optimization problems. To improve the efficiency and effectiveness of metamodel construction, regressorsfdefined in this paper can have the form in common with the empirical formulation of the problems in many engineering subjects.
Statistical inference of empirical constituents in partitioned analysis from integral-effect experiments
Authors: Stevens Garrison N. , Atamturktur Sez , Brown D. Andrew , Williams Brian J. , Unal Cetin
Published: March 2018

Purpose

Partitioned analysis is an increasingly popular approach for modeling complex systems with behaviors governed by multiple, interdependent physical phenomena. Yielding accurate representations of reality from partitioned models depends on the availability of all necessary constituent models representing relevant physical phenomena. However, there are many engineering problems where one or more of the constituents may be unavailable because of lack of knowledge regarding the underlying principles governing the behavior or the inability to experimentally observe the constituent behavior in an isolated manner through separate-effect experiments. This study aims to enable partitioned analysis in such situations with an incomplete representation of the full system by inferring the behavior of the missing constituent.

Design/methodology/approach

This paper presents a statistical method for inverse analysis infer missing constituent physics. The feasibility of the method is demonstrated using a physics-based visco-plastic self-consistent (VPSC) model that represents the mechanics of slip and twinning behavior in 5182 aluminum alloy. However, a constituent model to carry out thermal analysis representing the dependence of hardening parameters on temperature is unavailable. Using integral-effect experimental data, the proposed approach is used to infer an empirical constituent model, which is then coupled with VPSC to obtain an experimentally augmented partitioned model representing the thermo-mechanical properties of 5182 aluminum alloy.

Findings

Results demonstrate the capability of the method to enable model predictions dependent upon relevant operational conditions. The VPSC model is coupled with the empirical constituent, and the newly enabled thermal-dependent predictions are compared with experimental data.

Originality/value

The method developed in this paper enables the empirical inference of a functional representation of input parameter values in lieu of a missing constituent model. Through this approach, development of partitioned models in the presence of uncertainty regarding a constituent model is made possible.
Sparse representation of delay differential equation of Pantograph type using multi-wavelets Galerkin method
Authors: Nemati Saray Behzad , Manafian Jalil
Published: March 2018

Purpose

The purpose of this study is an application of the multi-wavelets Galerkin method to delay differential equations with vanishing delay known as Pantograph equation.

Design/methodology/approach

The method consists of expanding the required approximate solution at the elements of the Alpert multi-wavelets. Using the operational matrices of integration and wavelet transform matrix, the authors reduce the problem to a set of algebraic equations.

Findings

Because of the large size of the system, thresholding is used to obtain a new sparse system, and then this new system is solved to reduce the computational effort and related computer run time. The authors demonstrate that the solutions may be efficiently represented in a multi-wavelets basis because of flexible vanishing moments property of this type of multi-wavelets.

Originality/value

The L2 convergence of the scheme for the proposed equation has been investigated. A series of numerical tests is provided to demonstrate the validity and applicability of the technique.
Statistical energy analysis for vibro-acoustic coupled system with fuzzy parameters
Authors: Wang Yue , Wu Di , Wang Lei , Wang Xiaojun
Published: March 2018

Purpose

This paper aims to propose a novel statistic energy analysis method with fuzzy parameters to study the dynamic and acoustic responses of coupled system with fuzzy parameters, which can expand the applied range of statistic energy analysis method in engineering to some extent.

Design/methodology/approach

On the basis of the property of membership level, the uncertain fuzzy parameters are expressed as the interval forms. Interval mathematics and interval expansion principle are adopted to solve the problem with interval parameters. At last, two numerical examples, which include a two-plate coupled system and a single-partition sound-insulation system, are carried out to demonstrate the feasibility and validity of the presented method.

Findings

Interval mathematics and interval expansion principle are adopted to solve the problem with interval parameters.

Originality/value

By integrating the interval analysis, optimization technique and Taylor expansion method, two non-probabilistic, set-theoretical statistical energy analyses are proposed for predicting the dynamical and acoustical response of the complex coupled system with uncertain parameters in high-frequency domain.
Optimization of hybrid polymer composites under uniaxial traction
Authors: Conde Fábio Monteiro , Coelho Pedro Gonçalves , Tavares Rodrigo Paiva , Camanho Pedro Castro , Guedes José Miranda , Rodrigues Helder Carriço
Published: March 2018

Purpose

This study aims to achieve a “pseudo-ductile” behaviour in the response of hybrid fibre reinforced composites under uniaxial traction by solving properly formulated optimization problems.

Design/methodology/approach

The composite material model is based on the combination of different types of fibres (with different failure strains or strengths) embedded in a polymer matrix. The composite failure under tensile load is predicted by analytical models. An optimization problem formulation is proposed and a Genetic Algorithm is used. Multi-objective optimization problems balancing failure strength and ductility criteria are solved providing optimal mixtures of fibres whose properties may come either from a pre-defined list of materials, currently available in the market, or simply assuming their continuum variation within predefined bounds, in an attempt to attain unprecedented performance levels.

Findings

Optimal solutions of hybrid fibre reinforced composites exhibiting pseudo-ductile behaviour are presented. It is found that a fibre made from a material exhibiting relatively low stiffness combined with high strength is preferred for hybridization. Furthermore, the ratio of the average failure/critical strains between the low and high elongation fibres to be hybridized must be equal or greater than two.

Originality/value

Typically, a ductile failure is an inherent property of metals, that is, their typical response curve after the linear (elastic) region exhibits a yielding plateau still followed by an increase in stress till collapse. In stark contrast, composite materials exhibit (under some loading conditions) brittle failure that may limit their widespread usage. Therefore, a “pseudo-ductility” in composites is valued and targeted through optimization which is the main original contribution here.
Evaluation of the FMBEM efficiency in the analysis of porous structures
Authors: Ptaszny Jacek , Hatłas Marcin
Published: March 2018

Purpose

The purpose of this paper is to evaluate the efficiency of the fast multipole boundary element method (FMBEM) in the analysis of stress and effective properties of 3D linear elastic structures with cavities. In particular, a comparison between the FMBEM and the finite element method (FEM) is performed in terms of accuracy, model size and computation time.

Design/methodology/approach

The developed FMBEM uses eight-node Serendipity boundary elements with numerical integration based on the adaptive subdivision of elements. Multipole and local expansions and translations involve solid harmonics. The proposed model is used to analyse a solid body with two interacting spherical cavities, and to predict the homogenized response of a porous material under linear displacement boundary condition. The FEM results are generated in commercial codes Ansys and MSC Patran/Nastran, and the results are compared in terms of accuracy, model size and execution time. Analytical solutions available in the literature are also considered.

Findings

FMBEM and FEM approximate the geometry with similar accuracy and provide similar results. However, FMBEM requires a model size that is smaller by an order of magnitude in terms of the number of degrees of freedom. The problems under consideration can be solved by using FMBEM within the time comparable to the FEM with an iterative solver.

Research limitations/implications

The present results are limited to linear elasticity.

Originality/value

This work is a step towards a comprehensive efficiency evaluation of the FMBEM applied to selected problems of micromechanics, by comparison with the commercial FEM codes.
Piezoresistive strain sensor array using polydimethylsiloxane-based conducting nanocomposites for electronic skin application
Authors: Chong Yung Sin , Yeoh Keat Hoe , Leow Pei Ling , Chee Pei Song
Published: March 2018

Purpose

This paper aims to report a stretchable piezoresistive strain sensor array that can detect various static and dynamic stimuli, including bending, normal force, shear stress and certain range of temperature variation, through sandwiching an array of conductive blocks, made of multiwalled carbon nanotubes (MWCNTs) and polydimethylsiloxane (PDMS) composite. The strain sensor array induces localized resistance changes at different external mechanical forces, which can be potentially implemented as electronic skin.

Design/methodology/approach

The working principle is the piezoresistivity of the strain sensor array is based on the tunnelling resistance connection between the fillers and reformation of the percolating path when the PDMS and MWCNT composite deforms. When an external compression stimulus is exerted, the MWCNT inter-filler distance at the conductive block array reduces, resulting in the reduction of the resistance. The resistance between the conductive blocks in the array, on the other hand, increases when the strain sensor is exposed to an external stretching force. The methodology was as follows: Numerical simulation has been performed to study the pressure distribution across the sensor. This method applies two thin layers of conductive elastomer composite across a 2 × 3 conductive block array, where the former is to detect the stretchable force, whereas the latter is to detect the compression force. The fabrication of the strain sensor consists of two main stages: fabricating the conducting block array (detect compression force) and depositing two thin conductive layers (detect stretchable force).

Findings

Characterizations have been performed at the sensor pressure response: static and dynamic configuration, strain sensing and temperature sensing. Both pressure and strain sensing are studied in terms of the temporal response. The temporal response shows rapid resistance changes and returns to its original value after the external load is removed. The electrical conductivity of the prototype correlates to the temperature by showing negative temperature coefficient material behaviour with the sensitivity of −0.105 MΩ/°C.

Research limitations/implications

The conductive sensor array can potentially be implemented as electronic skin due to its reaction with mechanical stimuli: compression and stretchable pressure force, strain sensing and temperature sensing.

Originality/value

This prototype enables various static and dynamic stimulus detections, including bending, normal force, shear stress and certain range of temperature variation, through sandwiching an array of conductive blocks, made of MWCNT and PDMS composite. Conventional design might need to integrate different microfeatures to perform the similar task, especially for dynamic force sensing.
Grattan Institute's Case for Sugar Tax Is Not Proven
Authors: Pincus Jonathan
Published: March 2018

Duckett, Swerissen and Wiltshire () advocated a 40‐cent tax per 100g of sugar in sugar‐sweetened beverages (SSB), because the tax would reduce the cost burden on the non‐obese. Duckett, Swerissen and Wiltshire took these ‘third‐party’ costs as indices of market failure. However, their distributional analysis is not an appropriate framework for the assessment of economic efficiency. Moreover, they did not quantify the causal mechanisms through which a small weight loss would appreciably lower health costs and increase employment of the obese. There may be an economic case for such a tax, but Duckett, Swerissen and Wiltshire have not made it.
Towards Understanding Macrofinancial Impacts of Loan‐to‐Value Ratio Policy in New Zealand: A General Equilibrium Perspective
Authors: Fukac Martin , Greig Lucy , Snethlage Daniel
Published: March 2018

We use a dynamic stochastic general equilibrium model as a framework for thinking about the transmission mechanism of loan‐to‐value macroprudential policy. We analyse the key channels through which the caps on loan‐to‐value ratios work to limit the speed of asset and credit cycles. We further analyse the mechanisms through which the caps support financial system resilience during asset price downturns that are of sufficient magnitude to cause financial and macroeconomic instability.
The Promise of Co‐Design for Public Policy
Authors: Blomkamp Emma
Published: March 2018

As a novel method for creatively engaging citizens and stakeholders to find solutions to complex problems, co‐design holds great promise for policy makers. It has been vaunted as a way to generate more innovative ideas, ensure policies and services match the needs of citizens, achieve economic efficiencies by improving responsiveness, foster cooperation and trust between different groups, meaningfully engage the ‘hard to reach’, and achieve support for change. This article considers how we might determine whether co‐design has real potential to dramatically improve policy processes and outcomes. Drawing on relevant literature on participatory design, design thinking and public sector innovation, this review explores the meaning and potential of co‐design in the context of public policy. It highlights the philosophical underpinnings and normative implications of participatory design, and questions the feasibility of achieving the promised outcomes in the challenging context of contemporary policy making.
‘I Feel Mad So I Be Bad’: The Role of Affect, Dissatisfaction and Stress in Determining Responses to Interpersonal Deviance
Authors: Michalak Rebecca T. , Kiffin‐Petersen Sandra A. , Ashkanasy Neal M.
Published: March 2018

Interpersonal deviance relates to a range of destructive individual and organizational outcomes. To date, however, scholars have largely failed to explore this issue from the perspective of the targeted individuals; and in particular how and why such negative outcomes manifest. To provide insights into this question, and based in principles of critical realism, we utilized semi‐structured in‐depth interviews to explore employees’ interpersonal deviance experiences, their responses and determinants of response selections, including: (1) emotions and feelings; (2) dissatisfaction and stress. We found that the traditional model, where responses are driven by dissatisfaction and confined to exit, voice, loyalty and neglect (EVLN), is inadequate. We therefore extend the EVLN model to include retaliation (EVLN‐R) and identify a range of other responses, including venting and seeking social support for inclusion in the typology. Moreover, contrary to traditional theorizing, we found that responses were determined first and foremost by emotions and feelings, followed by stress, with dissatisfaction of little to no importance. We propose a new, multi‐dimensional response typology including self‐orientated responses and make suggestions for future research to test our typology, before closing with the implications for practice.
GOING BACK TO OUR ROOTS
Authors: KESEBIR SELIN , KESEBIR PELIN
Published: March 2018

New research by Selin Kesebir and Pelin Kesebir shows that our use of words that describe the natural world has declined. That's not good for people or organisations – so don't shut the outdoors out
TRANSPARENTLY REWARDING
Authors: BALAKRISHNAN KARTHIK , ERTAN AYTEKIN
Published: March 2018

Banks may complain at having to disclose more about their business, but Karthik Balakrishnan and Aytekin Ertan show how they benefit, too
TECH UNTAMED
Authors: BIRKINSHAW JULIAN , LAURANCE BEN
Published: March 2018

We need to rethink the way we monitor the power of the huge companies now dominating the business landscape, say Julian Birkinshaw and Ben Laurance
WHEN STEREOTYPES COLLIDE
Authors: RATTAN ANEETA
Published: March 2018

Aneeta Rattan investigates what happens in the hiring process when preconceptions about identity come into conflict with each other
Reduction of Parenteral Opioid Use in Community Emergency Departments Following Implementation of Treatment Guidelines
Authors: Ghobadi Ali , Van Winkle Patrick J. , Menchine Michael , Chen Qiaoling , Huang Brian Z. , Sharp Adam L.
Published: March 2018

Objective

Opioid prescribing guidelines are commonly seen as part of the solution to America's opioid epidemic. However, the effectiveness of specific treatment guidelines on altering opioid prescribing in the emergency department (ED) is unclear. We examined provider ordering patterns before and after implementation of opioid use guidelines for ED patients overall and the specific subsets of ED patients with either chronic opioid use or fracture.

Methods

We conducted a pre–post interrupted time series analysis of adult (≥18 years old) ED encounters in 14 integrated community EDs before (2013) and after (2014) the implementation of opioid prescribing guidelines. We compared opioid use pre‐ and postintervention using segmented logistic regression for primary and secondary analyses. The primary outcome was parenteral opioid use in the ED, with additional subgroup analysis of chronic pain and fracture cohorts. We also examined ED oral opioid use and discharge prescribing.

Results

There were 508,337 pre‐ and 531,620 postintervention encounters. The intervention was associated with an initial reduction in the odds of parenteral opioids ordered (odds ratio [OR] = 0.89, 95% CI = 0.87–0.91) and a decrease in the monthly trend compared to the preintervention period (OR = 0.99, 95% CI = 0.99–0.99). The immediate reduction in parenteral opioid use was significantly larger in the cohort of patients with chronic pain (OR = 0.81, 95% CI = 0.72–0.91), whereas the fracture cohort showed no change (OR = 1.10, 95% CI = 0.97–1.25).

Conclusion

The use of an opioid ordering guideline was associated with significant reduction in parenteral opioid use in the ED and as intended subgroup comparisons suggest that acute fractures were not affected and chronic pain visits were associated with larger decreases in opioid use.