bluuebunny/crossref_metadata_2025 huggingface dataset:
Microbial interkingdom interactions in roots promote Arabidopsis survival
Authors: Durán Paloma , Thiergart Thorsten , Garrido-Oter Ruben , Agler Matthew , Kemen Eric , Schulze-Lefert Paul , Hacquard Stéphane
Published: June 2018

Roots of healthy plants are inhabited by soil-derived bacteria, fungi, and oomycetes that have evolved independently in distinct kingdoms of life. How these microorganisms interact and to what extent those interactions affect plant health are poorly understood. We examined root-associated microbial communities from three Arabidopsis thaliana populations and detected mostly negative correlations between bacteria and filamentous microbial eukaryotes. We established microbial culture collections for reconstitution experiments using germ-free A. thaliana. In plants inoculated with mono- or multi-kingdom synthetic microbial consortia, we observed a profound impact of the bacterial root microbiota on fungal and oomycetal community structure and diversity. We demonstrate that the bacterial microbiota is essential for plant survival and protection against root-derived filamentous eukaryotes. Deconvolution of 2,862 binary bacterial-fungal interactions ex situ, combined with community perturbation experiments in planta, indicate that biocontrol activity of bacterial root commensals is a redundant trait that maintains microbial interkingdom balance for plant health.
Disease transmission mode has little effect on simulated canine rabies elimination
Authors: Ward Jessica K. R. , Smith Graham C. , Massei Giovanna
Published: June 2018

Disease transmission in animal populations can be affected by density or by frequency of contacts between individuals, although many models assume linear density-dependent transmission. We used rabies and free-roaming dogs (Canis familiaris) in two Nepalese cities as a model system to explore the impact of linear and non-linear density-dependent disease transmission on disease elimination achieved through rabies vaccination or vaccination and sterilisation. Strongly non-linear transmission approximated realistic frequency dependent transmission. Free roaming dogs, abundant in many parts of the developing world, are responsible for most cases of rabies transmission to humans. Most models of rabies transmission assume that the disease transmission rate is linearly density-dependent, although a recent empirical study did not find evidence to support this assumption. Rabies vaccination, culling and dog sterilisation are employed to eliminate rabies or to reduce the numbers of human cases. We created a continuous-time deterministic compartmental model to describe rabies epidemiology within a dog population and to analyse the two modes of transmission. Under each transmission mode, we investigated the efficacy of dog vaccination and fertility control to eliminate rabies. To investigate the effect of dog density on disease control efforts, models were run for cities with high and low dog population densities using data from the Nepalese cities. The results showed that, at low population density, the amount of control effort required for disease elimination did not differ substantially between different transmission modes. At high population density, the effort required to achieve disease elimination was only higher for linear density-dependent than for non-linear transmission due to the exact value of the transmission rate, beta. The model suggests that although disease transmission mode may alter the impact of control on rabies elimination, this impact is relatively small and probably not relevant to disease management.
Chronic Electrical Stimulation Promotes the Excitability and Plasticity of ESC-derived Neurons following Glutamate-induced InhibitionIn vitro
Authors: Latchoumane Charles-Francois V. , Jackson LaDonya , Eslampanah Sendi Mohammad .S , Tehrani Kayvan F. , Mortensen Luke J. , Stice Steven L. , Ghovanloo Maysam , Karumbaiah Lohitash
Published: June 2018

Functional electrical stimulation (FES) is rapidly gaining traction as a therapeutic tool for mediating the repair and recovery of the injured central nervous system (CNS). However, the underlying mechanisms and impact of these stimulation paradigms at a molecular, cellular and network level remain largely unknown. In this study, we used embryonic stem cell (ESC)-derived neuron and glial cocultures to investigate network maturation following acute administration of L-glutamate, which is a known mediator of excitotoxicity following CNS injury. We then modulated network maturation using chronic low frequency stimulation (LFS) and direct current stimulation (DCS) protocols. We demonstrated that L-glutamate impaired the rate of maturation of ESC-derived neurons and glia immediately and over a week following acute treatment. The administration of chronic LFS and DCS protocols individually following L-glutamate infusion significantly promoted the excitability of neurons as well as network synchrony, while the combination of LFS/DCS did not. qRT-PCR analysis revealed that LFS and DCS alone significantly up-regulated the expression of excitability and plasticity-related transcripts encoding N-methyl-D-aspartate (NMDA) receptor subunit (NR2A), brain-derived neurotrophic factor (BDNF) and Ras-related protein (RAB3A). In contrast, the simultaneous administration of LFS/DCS down-regulatedBDNFandRAB3Aexpression. Our results demonstrate that LFS and DCS stimulation can modulate network maturation excitability and synchrony following the acute administration of an inhibitory dose of L-glutamate, as well as an upregulation of NR2A, BDNF and RAB3A gene expression. Our study also provides a novel framework for investigating the effects of electrical stimulation on neuronal responses and network formation/repair after traumatic brain injury.
A Drosophila CRISPR/Cas9 toolkit for conditionally manipulating gene expression in the prothoracic gland as a test case for polytene tissues
Authors: Huynh Nhan , King-Jones Kirst
Published: June 2018

Targeting gene function with spatial or temporal specificity is a key goal in molecular genetics. CRISPR-Cas9 has greatly facilitated this strategy, but some standard approaches are problematic. For instance, simple tissue-specific or global overexpression of Cas9 can cause significant lethality or developmental delays even in the absence of gRNAs. In particular, we found that Gal4-mediated expression of UAS-Cas9 in the Drosophila prothoracic gland (PG) was not a suitable strategy to disrupt gene expression, since Cas9 alone caused widespread lethality. The PG gland is widely used for studying endocrine gland function during animal development, but tools validating PG-specific RNAi phenotypes are lacking. Here, we present a collection of modular gateway-compatible CRISPR-Cas9 tools that allow precise modulation of target gene activity with temporal and spatial specificity. We also demonstrate that Cas9 fused to the progesterone ligand-binding domain can be used to activate gene expression via RU486. Using these approaches, we were able to avoid the lethality associated with simple GAL4-mediated overexpression of Cas9 in the PG. Given that the PG is a polytene tissue, we conclude that these tools work effectively in endoreplicating cells where Cas9 has to target multiple copies of the same locus. Our toolkit can be easily adapted for other tissues and can be used both for gain-and loss-of-function studies.
Insights on protein thermal stability: a graph representation of molecular interactions
Authors: Miotto Mattia , Olimpieri Pier Paolo , Rienzo Lorenzo Di , Ambrosetti Francesco , Corsi Pietro , Lepore Rosalba , Tartaglia Gian Gaetano , Milanetti Edoardo
Published: June 2018

Understanding the molecular mechanisms of thermal stability is a challenge in protein biology. Indeed, knowing the temperature at which proteins are stable has important theoretical implications, which are intimately linked with properties of the native fold, and a wide range of potential applications from drug design to the optimization of enzyme activity.

Here, we present a novel graph-theoretical framework to assess thermal stability based on the structure without any aprioriinformation. In our approach we describe proteins as energy-weighted graphs and compare them using ensembles of interaction networks. Investigating the position of specific interactions within the 3D native structure, we developed a parameter-free network descriptor that permits to distinguish thermostable and mesostable proteins with an accuracy of 76% and Area Under the Roc Curve of 78%.
An automated, high-throughput method for standardizing image color profiles to improve image-based plant phenotyping
Authors: Berry Jeffrey C. , Fahlgren Noah , Pokorny Alexandria A. , Bart Rebecca , Veley Kira M.
Published: June 2018

High-throughput phenotyping has emerged as a powerful method for studying plant biology. Large image-based datasets are generated and analyzed with automated image analysis pipelines. A major challenge associated with these analyses is variation in image quality that can inadvertently bias results. Images are made up of tuples of data called pixels, which consist of R, G, and B values, arranged in a grid. Many factors, for example image brightness, can influence the quality of the image that is captured. These factors alter the values of the pixels within images and consequently can bias the data and downstream analyses. Here, we provide an automated method to adjust an image-based dataset so that brightness, contrast, and color profile is standardized. The correction method is a collection of linear models that adjusts pixel tuples based on a reference panel of colors. We apply this technique to a set of images taken in a high-throughput imaging facility and successfully detect variance within the image dataset. In this case, variation resulted from temperature-dependent light intensity throughout the experiment. Using this correction method, we were able to standardize images throughout the dataset, and we show that this correction enhanced our ability to accurately quantify morphological measurements within each image. We implement this technique in a high-throughput pipeline available with this paper, and it is also implemented in PlantCV.
Chemically Accurate Relative Folding Stability of RNA Hairpins from Molecular Simulations
Authors: Smith Louis G. , Tan Zhen , Spasic Aleksandar , Dutta Debapratim , Salas-Estrada Leslie A. , Grossfield Alan , Mathews David H.
Published: June 2018

This study describes a comparison between melts and simulated stabilities of the same RNAs that could be used to benchmark RNA force fields, and potentially to determine future melt-ing experiments. Using umbrella sampling molecular simulations of three 12-nucleotide RNA hairpin stem loops, for which there are experimentally determined free energies of unfold-ing, we projected unfolding onto the reaction coordinate of end to end (5′ to 3′ hydroxyl oxygen) distance. We estimate the free energy change of the transition from the native con-formation to a fully extended conformation—the stretched state—with no hydrogen bonds between non-neighboring bases. Each simulation was performed four times using the AM-BER FF99+bsc0+χOL3 force field and each window, spaced at 1 Å intervals, was sampled for 1 μs, for a total of 552 μs of simulation. We compared differences in the simulated free energy changes to analogous differences in free energies from optical melting experiments using ther-modynamic cycles where the free energy change between stretched and random coil sequences is assumed to be sequence independent. The differences between experimental and simulated ΔΔG° are on average 1.00 ± 0.66 kcal/mol, which is chemically accurate and suggests analo-gous simulations could be used predictively. We also report a novel method to identify where replica free energies diverge along the reaction coordinate, thus indicating where additional sampling would most improve convergence. We conclude by discussing methods to more economically perform such simulations.
Dual RNAseq of human leprosy lesions identifies bacterial determinants linked to host immune response
Authors: Montoya Dennis , Andrade Priscila R. , Silva Bruno J. A. , Teles Rosane M. B. , Bryson Bryan , Sadanand Saheli , Noel Teia , Lu Jing , Sarno Euzenir , Arnvig Kristine B. , Young Douglas , Lahiri Ramanuj , Williams Diana L. , Fortune Sarah , Bloom Barry R. , Pellegrini Matteo , Modlin Robert L.
Published: June 2018

To understand how the interaction between an intracellular bacterium and the host immune system contributes to outcome at the site of infection, we studied leprosy, a disease that forms a clinical spectrum, in which progressive infection by the intracellular bacterium Mycobacterium leprae is characterized by the production of type | IFNs and antibody production. We performed dual RNAseq on patient lesions, identifying a continuum of distinct bacterial states that are linked to the host immune response. The bacterial burden, represented by the fraction of bacterial transcripts, correlates with a host type | IFN gene signature, known to inhibit antimicrobial responses. Second, the bacterial transcriptional activity, defined by the bacterial mRNA/rRNA ratio, links bacterial heat shock proteins with the BAFF-BCMA host antibody response pathway. Our findings provide a platform for interrogation of host and pathogen transcriptomes at the site of infection, allowing insight into mechanisms of inflammation in human disease.
Exocyst Dynamics During Vesicle Tethering and Fusion
Authors: Ahmed Syed Mukhtar , Nishida-Fukuda Hisayo , Li Yuchong , McDonald W. Hayes , Gradinaru Claudiu , Macara Ian G.
Published: June 2018

The exocyst is a conserved octameric complex that tethers exocytic vesicles to the plasma membrane prior to fusion. Exocyst assembly and delivery mechanisms remain unclear, especially in mammalian cells. Here we tagged multiple endogenous exocyst subunits with sfGFP or Halo using Cas9 gene editing, to create single and double knock-in lines of mammary epithelial cells, and interrogated exocyst dynamics by high-speed imaging and correlation spectroscopy. We discovered that mammalian exocyst is comprised of tetrameric subcomplexes that, unexpectedly, can associate independently with vesicles and plasma membrane and are in dynamic equilibrium. Membrane arrival times are similar for subunits and vesicles, but with a small delay (~80msec) between subcomplexes. Departure of Sec3 occurs prior to fusion, whereas other subunits depart just after fusion. Single molecule counting indicates ~9 exocyst complexes associated per vesicle. These data reveal the mammalian exocyst as a remarkably dynamic two-part complex and provide important new insights into assembly/disassembly mechanisms.
5′ Modifications Improve Potency and Efficacy of DNA Donors for Precision Genome Editing
Authors: Ghanta Krishna S , Chen Zexiang , Mir Aamir , Dokshin Gregoriy A , Krishnamurthy Pranathi M , Yoon Yeonsoo , Gallant Judith , Xu Ping , Zhang Xiao-Ou , Ozturk Ahmet , Shin Masahiro , Idrizi Feston , Liu Pengpeng , Gneid Hassan , Lawson Nathan D , Rivera-Pérez Jaime A , Sontheimer Erik J , Watts Jonathan K , Mello Craig C
Published: June 2018

Nuclease-directed genome editing is a powerful tool for investigating physiology and has great promise as a therapeutic approach to correct mutations that cause disease. In its most precise form, genome editing can use cellular homology-directed repair (HDR) pathways to insert information from an exogenously supplied DNA repair template (donor) directly into a targeted genomic location. Unfortunately, particularly for long insertions, toxicity and delivery considerations associated with repair template DNA can limit HDR efficacy. Here, we explore chemical modifications to both double-stranded and single-stranded DNA-repair templates. We describe 5′-terminal modifications, including in its simplest form the incorporation of triethylene glycol (TEG) moieties, that consistently increase the frequency of precision editing in the germlines of three animal models (Caenorhabditis elegans, zebrafish, mice) and in cultured human cells.
Brr2 is a splicing fidelity factor
Authors: Mayerle Megan , Guthrie Christine
Published: June 2018

Many spliceosomal DExD/H box helicases act as fidelity factors during pre-mRNA splicing, promoting on-pathway interactions while simultaneously minimizing errors. Mutations linked to Retinitis Pigmentosa (RP), a form of heritable blindness, map to key domains of spliceosomal helicase Brr2 (SNRNP200in humans). Previous data show that such mutations negatively impact spliceosome activation, likely due to defects inbrr2-RPRNA binding, helicase, and ATPase activities. Furthermore, data from human reporter constructs suggest thatbrr2-RPmight impact 5′ splice site selection. Here we undertake a systematic analysis ofbrr2-RPeffects on splicing fidelity. We show that a subset ofbrr2-RPmutants exhibit intron retentionin vivo. Furthermore,brr2-RPmutants display hyperaccurate and/or error-prone splicing of a variety of splicing reporters. Branch-site fidelity is particularly impacted in this reporter assay. In addition, multiplebrr2-RPalleles genetically interact withprp16alleles known to impact the fidelity of branch site selection. Together these data implicate Brr2 in the fidelity of branch-site selection, and suggest that RP results not just from defects in spliceosome activation, but also from fidelity defects arising throughout the splicing cycle and in splicing fidelity.
Can I have it all? Emerging adult women’s positions on balancing career and family
Authors: Ezzedeen Souha R. , Budworth Marie-Hélène , Baker Susan D.
Published: June 2018

Purpose

Emerging adult women are actively engaged in career and family explorations, amidst changing opportunities and constraints. The purpose of this paper is to investigate whether such women felt they could balance a high-achieving career and a family life, or what has become known in the popular discourse as women “having it all.”

Design/methodology/approach

This qualitative study utilized focus groups to explore subjective perceptions of balancing career and family held by emerging adult women. The sample (n=69) comprised female university students in a large Canadian metropolitan area.

Findings

Thematic analyses unearthed six distinct yet overlapping positions on the possibility of balancing career and family: Optimism (“I can have it all.”), Pessimism (“I cannot have it all.”), Uncertainty (“I am not sure I can have it all.”), Choice (“I don’t want to have it all.”), Pragmatism (“This is what I need to do to have it all.”) and Support (“Will I access the support necessary to have it all?”).

Research limitations/implications

Limitations include the potential of focus groups to elicit group polarization and to lead participants to censor opinions to conform to conversations. Still, the study reveals more nuanced positions held by women than reported earlier.

Originality/value

The study extends prior research by revealing the range of positions held by women toward career and family, highlighting women’s understanding of the complex issues involved and showcasing their awareness of the crucial role of social support.
ABBYY: the digitization of language and text
Authors: Shapenko Andrey , Korovkin Vladimir , Leleux Benoit
Published: June 2018

Subject area

Entrepreneurship, Innovation Management, Bringing Technology to Market, International Growth Strategy from Emerging Markets, Russia, B2B Marketing.

Study level/applicability

MBA and executive education programs, technology management programs and electives.

Case overview

The case investigates the 20-years growth story of ABBYY, one of the most successful Russian technological companies in a global market. It covers the company’s roots, development of unique technology, evolution of products, market development and globalization and discusses a strategic threat from Google Translate to the company’s sustainable position and its business model.

Expected learning outcomes

The expected learning outcome is to discuss the key issues associated with establishing, growing and globalizing technology-driven business in an emerging market: bringing technology to market, defining customer value proposition, entering overseas markets from Russia, building partnerships, developing organizational structure to fit growth, financing rapid growth and solving “Innovator’s Dilemma”.

Supplementary materials

Teaching Notes are available for educators only. Please contact your library to gain login details or email support@emeraldinsight.com to request teaching notes.

Subject code

CSS 3: Entrepreneurship.
Analyzing Iran’s science and technology foresight programs: recommendations for further practices
Authors: Hafezi Reza , Malekifar Siavosh , Akhavan Amirnaser
Published: June 2018

Purpose

Studying previous science and technology (S&T) foresight activities reveals information that helps decision makers to redesign policy-making templates aimed at dealing with new millennium challenges. To propose policy recommendations about further S&T foresight programs in Iran, this paper aims to propose a three-phase process to study historical S&T foresight activities at national and sub-national level since 2005 to 2015, to analyze the state of selected activities to discover weaknesses and potential solutions and, finally, to provide strategies and tactics to improve further S&T foresight activities through an expert-based process.

Design/methodology/approach

This paper provides a three-stage methodology, designed to survey Iranian historical foresight practices (study) using scoping framework equipped with additional features, diagnosis and evaluating (analyze) and finally proposing recommendations to organize and implement more efficient further foresight practices (design) to initialize further practices in developing countries such as Iran.

Findings

Although concerns about future and the importance of foresight activities are raised however Iranian foresight community needs to be developed. As noted in Section 5, Iranian foresight facilitators and specialist are biased to limited methodologies and methods; therefore, creating foresight networks and developing communities is strongly recommended.

Research limitations/implications

The main constraint of this research was lack of valid data in the case of some Iranian S&T foresight programs.

Originality/value

Iran as a developing country needs to plan for long-run programs; however, there is no integrated study which reviews and analyzes the previous attempts to dedicate insights about how to reframe existing foresight paradigms. As foresight practices facilitate the paths toward sustainability, analyzing and diagnosis of a series of foresight practices in a devolving country may initialize designing such efforts in less developed world.
Bank selection criteria and satisfaction of retail customers of Islamic banks in Bangladesh
Authors: Iqbal Mehree , Nisha Nabila , Rashid Mamunur
Published: June 2018

Purpose

The purpose of this paper is to argue that “being Islamic” is already embedded in the decision frame of the Muslim consumers when choosing their Islamic banks, and hence, the bank selection criteria of these Muslim consumers will be dominated by non-faith-based factors.

Design/methodology/approach

This study took the context of retail consumers of Islamic banks of Bangladesh—the fourth largest Muslim populated country in the world, having great potential of developing an Islamic ecosystem. The study employed survey method using structured questionnaire on 311 respondents from 35 branches of six Islamic banks in Dhaka—the capital city of Bangladesh. Exploratory factor analysis, followed by multivariate regression analysis, was conducted to identify the determinants of satisfaction among Muslim retail bank customers.

Findings

The study forwards three important findings. First, faith-based bank selection criterion (i.e. Islam) is not a stand-alone factor anymore; rather, the items of this factor are embedded into other non-faith-based factors. Second, among the non-faith-based factors, commitment of the bank, competence and compassion of the bank employees have topped the list of bank selection criteria. Third, competence, commitment and corporate image of the bank had relatively more influence on satisfaction when compared to compassion and convenience.

Practical implications

Since Shari’ah compliance is already embedded in Islamic banking system, Islamic bankers should now focus on strategic targeting of their customers based on non-faith-based operational determinants.

Originality/value

This study presents that non-faith-based selection criteria are more influential in Islamic bank selection decision.
Inter-organizational relationships with core and peripheral partners in heritage tourism clusters
Authors: Elche Dioni , García-Villaverde Pedro M. , Martínez-Pérez Ángela
Published: June 2018

Purpose

This paper aims to analyze the effects of inter-organizational relationships with core and peripheral partners on innovation in heritage tourism clusters.

Design/methodology/approach

The empirical analysis uses original data (collected by means of a postal questionnaire) based at UNESCO World Heritage Cities in Spain. The sample consists of 215 companies, and the methodology used is hierarchical linear regression.

Findings

The authors identify divergent effects of relationships with core and peripheral partners on innovation. In particular, the effect of core partners has an inverted U-shaped form, while that of peripheral partners is U-shaped.

Research limitations/implications

The results may be extrapolated to other heritage tourism clusters located in World Heritage Cities with some precaution. The paper does not jointly analyze the effects of relationships with core and peripheral partners on the innovation of firms in tourism clusters.

Practical/implications

Clustered tourism firms should not rely only on relationships with core agents, because beyond a critical threshold, returns in terms of innovation diminish. Firms should strive to establish relationships with peripheral agents in spite of the initial difficulties and the costs associated with network building, because positive returns soon materialize.

Originality/value

This paper contributes to the literature on inter-organizational relationships by analyzing the impact of relationships with core and peripheral partners on innovation in clustered firms. The authors highlight the existence of the divergent curvilinear effects of these relationships on heritage tourism clusters.
The dynamics of inflation, exchange rates and the trade balance in a small economy
Authors: Yiheyis Zelealem , Musila Jacob
Published: June 2018

Purpose

The purpose of this study is to examine the temporal relationships between inflation and exchange rate changes and their implications for the trade balance in Uganda, which saw persistent trade deficits, rising inflation and disinflation episodes, as well as significant exchange-rate realignments and other liberalization measures over the sample period considered.

Design/methodology/approach

The short-run dynamics of the variables in question and the pattern of their long-run relationships are examined applying the bounds testing approach to cointegration on quarterly data.

Findings

The estimates suggest that, in the long run, a real depreciation leads to an increase in inflation; and that both real depreciation and inflation exert no significant effect on the trade balance. The estimated short-run dynamics suggest a causal relationship between the trade balance and the real exchange rate and between the real exchange rate and inflation, which is also found responsive to developments in the foreign sector. Taken together, the short-run and long-run multipliers seem to provide a weak support for the J-curve effect, while no evidence is found for the presence of the S-curve effect.

Originality/value

The study sheds light on the relationship among real exchange rate, inflation and the trade balance in the context of a small developing economy; it highlights that an improvement in the trade balance requires more than an appropriate exchange rate policy and underscores the importance of other policies in strengthening the external sector of the economy.
Whistleblowing in Kuwait and UK against corruption and misconduct
Authors: Al-Haidar Faisal
Published: June 2018

Purpose

This paper aims to explore the nature and the scope of whistleblowing in Kuwait and in the UK. Whistleblowing is when a person, usually an employee, in a government agency or private enterprise, discloses information to the public or to those in authority, of mismanagement, corruption or other wrongdoing. Due to the unpredictable consequences of whistleblowing, it is probable that many employees who witness wrongdoing do not consider blowing the whistle, because they fear the impact of such action on their relationship with their employers.

Design/methodology/approach

The author evaluated the whistleblowing systems in different countries. He first tackled the nature of whistleblowing in general, proceeded to analyse whistleblowing in Kuwait with mentions from other countries and finally evaluated the whistleblowing process in the UK.

Findings

The whistleblowing situation in the UK is clearer than that in Kuwait. Recent improvements have been made in the UK to protect whistleblowers. In the UK, the whistleblowing law under the Public Interest Disclosure Act 1998 came into force in July 1999 to protect whistleblowers. Kuwait also has had some improvements, which were seen to offer legal protection for those raising concerns about corruption under Law no. 24 of 2012. However, the author recommends that the Kuwaiti Government should give more protection to whistleblowers, and there is a need to protect the whistleblowers.

Originality/value

Potential whistleblowers might feel discouraged from disclosing information against their organisation, fearing a backlash against them. This is where the law and the rights of employees must be clarified. This paper will, therefore, evaluate the system of whistleblowing in the UK under the Public Interest Disclosure Act 1998 and examine this against the whistleblowing law in Kuwait under the Whistleblowing Act no. 24 of 2012.
Effect of diagonal cracks on shear stiffness of pre-stressed concrete beam
Authors: Liu Jinliang , Jia Yanmin , Zhang Guanhua , Wang Jiawei
Published: June 2018

Purpose

During service period, due to the overload or other non-load factors, diagonal cracks of the pre-stressed concrete beam are seriously affecting the safety of the bridge structure. The purpose of this paper is to quickly realize the shear bearing capacity and shear stiffness through maximum width of the diagonal cracks and make correct judgments.

Design/methodology/approach

Through the shear failure test of four test beams, collecting data of diagonal cracks and shear stiffness loss value. According to the deformation curve of the shear stiffness, and combined with the calculation formula of the maximum width of diagonal cracks, the formula for calculating the effective shear stiffness based on the maximum width of diagonal cracks is deduced, then the results are verified by test data. Data regression method is used to establish the effective shear stiffness loss ratio calculation formula, the maximum width of diagonal cracks used as a variable factor, and the accuracy of this formula is verified by comparing the shear failure test results of pre-stressed hollow plates.

Findings

With the increase in width of the diagonal crack, the loss rate of shear stiffness of the concrete beams is initially fast and then becomes slow. The calculation formulae for shear stiffness based on the maximum width of the diagonal cracks were deduced, and the feasibility and accuracy of the formulae were verified by analysis and calculation of shear test data.

Originality/value

A method for quickly determine the shear stiffness loss of structures by using maximum width of the diagonal cracks is established, and using this method, engineers can quickly determine effective shear stiffness loss ratio, without complex calculations. So this method not only ensures the safety of human life, but also saves money.
Research on destructive test of pretensioning prestressed concrete hollow slab in service
Authors: Wang Jiawei , Zhang Guanhua , Liu Jinliang , Jia Yanmin
Published: June 2018

Purpose

During service period, the bridge structures will be affected by the environment and load, so the carrying capacity will decline. The purpose of this paper is to research on the bearing capacity of bridge structures with time.

Design/methodology/approach

Destructive test and non-linear finite element analysis are carried out by utilizing two pretensioning prestressed concrete hollow slabs in service for 20 years; using the structural test deflection value to simulate the stiffness degradation of the service bridge and the finite element calculation results verify the accuracy of the calculation.

Findings

The flexural rigidity of the main beam when the test beam is destructed is degraded to approximately 20 percent of that before the test, which agrees well with the result of finite element analysis and indicates that the method of deducing the flexural rigidity of the structure according to the measured deflection value can effectively simulate the rigidity degradation law of the bridge in service. The crack resistance property of the test beam degrades obviously and the ultimate bearing capacity of the bending resistance does not degrade obviously.

Originality/value

The research results truly reflect the destruction process, destructive form, bearing capacity and rigidity degradation law of the old beam of the concrete bridge in service for 20 years and can provide technical basis for optimization design of newly built bridges of the same type and maintenance and reinforcement design of existing old bridges.
Quasi-statically growing crack tip fields in plastically compressible hardening-softening-hardening solid
Authors: Singh Sushant , Khan Debashis
Published: June 2018

Purpose

As the normality concept for frictional dilatant material has a serious drawback, the key feature in this numerical study is that the material here is characterized by elastic-viscoplastic constitutive relation with plastic non-normality effect for two different hardness functions. The paper aims to discuss this issue.

Design/methodology/approach

Quasi-static, mode I plane strain crack tip fields have been investigated for a plastically compressible isotropic hardening–softening–hardening material under small-scale yielding conditions. Finite deformation, finite element calculations are carried out in front of the crack with a blunt notch. For comparison purpose a few results of a hardening material are also provided.

Findings

The present numerical calculations show that crack tip deformation and the field quantities near the tip significantly depend on the combination of plastic compressibility and slope of the hardness function. Furthermore, the consideration of plastic non-normality flow rule makes the crack tip deformation as well as the field quantities significantly different as compared to those results when the constitutive equation exhibits plastic normality.

Originality/value

To the best of the authors’ knowledge, analyses, related to the constitutive relation exhibiting plastic non-normality in the context of plastic compressibility and softening (or softening hardening) on the near tip fields, are not explored in the literature.
Tribological performance of avocado oil containing copper nanoparticles in mixed and boundary lubrication regime
Authors: Shafi Wani Khalid , Raina Ankush , Ul Haq Mir Irfan
Published: June 2018

Purpose

This paper aims to study the tribological performance of Cu nanoparticles mixed in avocado oil.

Design/methodology/approach

A Pin-on-Disc tribometer was used to determine the tribological performance of avocado oil as a lubricant as well as for measuring the effectiveness of Cu nanoparticles. Stribeck curve was generated with the base oil and the oil containing Cu nanoparticles. The nanoparticles are added in 0.5 wt. % and 1 wt. % concentration. The worn-out surfaces of aluminum alloy 6061 pins are explored by scanning electron microscopy (SEM).

Findings

The use of Cu nanoparticles led to a reduction in friction and wear. Coefficient of friction (COF) was found to be minimum at 1 wt. % concentration, whereas specific wear rate was minimum for 0.5 wt. % concentration. The film-formation capability of the Cu nanoparticles led to an overall improvement in the tribological properties of the base oil.

Originality/value

Experiments are performed to evaluate the tribological performance of avocado oil using Cu nanoparticles. The results obtained herein suggest that avocado oil has a great potential to replace the conventional mineral oils in the field of industrial lubrication.
Flexibility and agility: evolution and relationship
Authors: Abdelilah Bouchra , El Korchi Akram , Balambo Mohammed Amine
Published: June 2018

Purpose

The purpose of this paper is to clarify the confusion between flexibility and agility. The paper traces the evolution of agility and the evolution of flexibility over time, analyses their drivers and different elements, draws the boundaries between them and defines their relationship.

Design/methodology/approach

A systematic literature review of flexibility and agility was developed. Papers written between 1920 and 2017 were reviewed and analyzed using a structured review technique. The identified papers focus on flexibility and agility, relating both to manufacturing and the supply chain.

Findings

Agility is the natural evolution of flexibility. Until the 1990s, the term “flexibility” was used to refer to agility, but, because of market changes, competitiveness and the need for speed, the term “agility” was coined. While flexibility is considered as an operational ability, agility is a strategic ability that enables a firm to establish a strategic long-term vision. In fact, flexibility is an agility capability, among other capabilities such as responsiveness or speed. There are also several types of flexibility that are used as agility sub-capabilities, or as agility enablers, which further confirms the idea that flexibility is a part of agility.

Research limitations/implications

This research is a systematic review of the existing literature on the concepts of flexibility and agility. Although it is theoretical, it could provide a set of hypotheses that would enable an empirical study to be conducted into how firms from different industries perceive flexibility and agility and how they implement each of them.

Originality/value

Flexibility and agility are two distinct characteristics that enable a firm to gain a competitive advantage by responding quickly and effectively to changing customer demand. However, there is confusion between these two concepts in the academic and professional literature, with both terms being used to refer to the same idea. Our literature review aims to draw the boundaries between flexibility and agility by analyzing the evolution of the two concepts and detailing their respective drivers and elements, in order to bring more clarity to the nature of the relationship between flexibility and agility.
Social entrepreneurship and sense-making: evidence from the Global Social Benefit Institute
Authors: Sabbaghi Omid , Cavanagh, S.J. Gerald F.
Published: June 2018

Purpose

The study aims to provide an empirical investigation of social enterprises in the context of experiential learning. Specifically, the study aims to investigate the interplay between faith-based principles and the processes of opportunity recognition and exploitation through an in-depth, qualitative study of social enterprises offered through the Global Social Benefit Institute (GSBI).

Design/methodology/approach

In this study, student experiences with social entrepreneurship are examined and their subsequent reflections are analyzed. Applying the Gioia methodology to the sample of student reflection data, this study enriches the growing literature on sense-making by looking closely at how student entrepreneurs engage their own faith-based education in helping their teams, beneficiaries and stakeholders “make sense” of a social change opportunity.

Findings

This study finds evidence of variability in the elaboration of the faith-based principles when sampling on the social needs of affection, behavioral confirmation and status.

Originality/value

The results suggest a role for faith-based sense-making when confronting the realities of social change opportunities.
Modification of lipid A structure and activity by the introduction of palmitoyltransferase gene to the acyltransferase‐knockout mutant of Escherichia coli
Authors: Sugawara Takehiro , Onoue Sakura , Takimoto Hiroaki , Kawahara Kazuyoshi
Published: June 2018

Lauroyltransferase gene (lpxL), Myristoyltransferase gene (lpxM) and palmitoyltransferase gene (crcA) of Escherichia coli BL21 were independently disrupted by the insertional mutations. The knockout mutant of two transferase genes (lpxL and crcA) produced lipid A with no lauric or palmitic acids and only a little amount of myristic acid. The mutant was susceptible to polymyxin B, but showed comparable growth with the wild‐type strain at 30°C. The palmitoyltransferase gene from E. coli (crcA) or Salmonella (pagP) was amplified by PCR, cloned in pUC119, and transferred into the double‐knockout mutant by transformation. The transformant contained palmitic acid in the lipid A, and recovered resistance to polymyxin B. Mass spectrometric analysis revealed that palmitic acid was linked to the hydroxyl group of 3‐hydroxymyristic acid at C‐2 position of proximal (reducing‐end) glucosamine. LPS from the double‐knockout mutant showed reduced IL‐6‐inducing activity to macrophage‐like line cells compared to that of the wild‐type strain, and the activity was only slightly restored by the introduction of palmitic acid to the lipid A. These results suggested that the introduction of one palmitic acid was enough to recover the integrity of the outer membrane, but not enough for the stimulation of macrophages.
The influence of early‐life allocation to antlers on male performance during adulthood: Evidence from contrasted populations of a large herbivore
Authors: Lemaître Jean‐François , Cheynel Louise , Douhard Frédéric , Bourgoin Gilles , Débias François , Ferté Hubert , Gilot‐Fromont Emmanuelle , Pardonnet Sylvia , Pellerin Maryline , Rey Benjamin , Vanpé Cécile , Hewison A. J. Mark , Gaillard Jean‐Michel
Published: June 2018

To secure mating opportunities, males often develop and maintain conspicuous traits that are involved in intrasexual and/or intersexual competition. While current models of sexual selection rely on the assumption that producing such traits is costly, quantifying the cost of allocating to secondary sexual traits remains challenging.

According to the principle of allocation, high energy allocation to growth or sexual traits in males should lead to reduced energy allocation to the maintenance of cellular and physiological functions, potentially causing them to age faster, with impaired survival.

We evaluated the short‐term and delayed consequences of energy allocation to antlers early in life in two contrasted populations of roe deer, Capreolus capreolus. Although most males mate successfully for the first time in their fourth year, antlers are grown annually from the first year of life onwards. We tested the prediction that a high level of allocation to antler growth during the first two years of life should lead to lower body mass, antler size and survival during the early and late prime stages, as well as to reduced longevity overall.

Growing and carrying long antlers during the first years of life was not associated with any detectable cost in the late prime stage. The positive association between antler growth in early life and adult body mass instead supports that fawn antler acts as an honest signal of phenotypic quality in roe deer.

For a given body mass, yearling males growing longer antlers displayed impaired performance during their late prime. We also found a trend for a short‐term survival cost of allocation to relative antler length during the second year of life.

Yearling males that grow long antlers relative to their mass might display a fast life‐history tactic. We argue that differential allocation to secondary sexual traits generates a diversity of individual trajectories that should impact population dynamics.
Neurological and Psychological Changes in Hemodialysis Patients Before and After the Treatment
Authors: Lai Silvia , Molfino Alessio , Mecarelli Oriano , Pulitano Patrizia , Morabito Santo , Pistolesi Valentina , Romanello Roberto , Zarabla Alessia , Galani Alessandro , Frassetti Nicla , Aceto Paola , Lai Carlo ,   Study Group on Geriatric Nephrology of the Italian Society of Nephrology
Published: June 2018

Neurological, psychological, and cognitive disorders in chronic kidney disease may contribute to poor quality of life in these patients. The aim of this study was to assess the electroencephalographic, psychological, and cognitive changes before and after hemodialysis (HD) compared with healthy controls (HC). Sixteen HD patients and 15 HC were enrolled. Electroencephalogram (EEG), Minnesota multiphasic personality inventory (MMPI‐2) Satisfaction profile (SAT‐P), and Neuropsychological test Global z‐scores (NPZ5) were performed before (T0) and after (T1) HD treatment and in HC. Renal function, inflammatory markers and mineral metabolism indexes were also evaluated. Patients did not show significant differences before and after HD in the absolute and relative power of band of EEG, except in Theta/Alpha index (P < 0.001). At T1, HD patients showed significant differences in Beta, Delta and Theta band, in addition to Theta/alpha index, with respect to HC. Moreover, HD patients showed significant differences in specific MMPI‐2 clinical and content scales, SAT‐P domains and NPZ5 tests of memory and concentration with respect to HC. We also observed significant correlations between renal function, mineral metabolism, inflammatory markers and psychocognitive alterations. In our sample EEG abnormalities tend to reduce, but not significantly, after HD treatment and differences remain present with respect to HC. In HD patients cognitive and psychological alterations were associated with reduced quality of life and correlated with mineral metabolism and inflammation. Modification in EEG and in psychological and cognitive parameters should be assessed in a larger HD population to confirm our observation.